The present invention relates to an antibody or functional fragment thereof which binds to a mammalian (e.g., human) CC-chemokine receptor 4 (CCR4) or a portion of the receptor and blocks binding of a ligand to the receptor. The invention further relates to a method of inhibiting the interaction of a cell bearing mammalian CCR4 with a ligand thereof, and to use of the antibodies and fragments in research, therapeutic, prophylactic and diagnostic methods.

Over the last decade chemokines have emerged as key mediators of inflammation as a result of their numerous proinflammatory activities which affect virtually every leukocyte type. More recently, chemokines have been recognized as a critical component of basal leukocyte trafficking essential for normal immune surveillance and response, as well as for several other functions in hematopoiesis, angiogenesis, control of viral infection, and T cell differentiation (Baggiolini et al., Ann. Rev. Immunol. 15:675 (1997); Zou et al., Nature 393:595 (1998); Tachibana et al., Nature 393:591 (1998)). This diverse array of biological activities, including mediation of a range of pro-inflammatory effects on leukocytes, such as triggering of chemotaxis, degranulation, synthesis of lipid mediators, and integrin activation, together with their critical role in the initiation and maintenance inflammatory diseases, and the recent identification of certain chemokine receptors as co-receptors for HIV-1 entry, have made chemokines and chemokine receptors an attractive new set of therapeutic targets.
Members of the chemokine family are produced and secreted by many cell types in response to early inflammatory mediators such as IL-1xcex2 or TNFxcex1. The chemokine superfamily comprises two main branches: the xcex1-chemokines (or CXC chemokines) which are characterized by a single amino acid separating the first 2 cysteines, and the xcex2-chemokines (CC chemokines), which contain two adjacent cysteines. The xcex1-chemokine branch includes proteins such as IL-8, neutrophil activating peptide-2 (NAP-2), melanoma growth stimulatory activity (MGSA/gro or GROA), and ENA-78, each of which have attracting and activating effects predominantly on neutrophils. The members of the xcex2-chemokine branch affect other cell types such as monocytes, lymphocytes, basophils, and eosinophils (Oppenheim, J. J. et al., Annu. Rev. Immunol., 9:617-648 (1991); Baggiolini, M., et al., Adv. Imunol., 55:97-179 (1994); Miller and Krangel, Crit. Rev. Immunol., 12:17-46 (1992); Jose, P. J., et al., J. Exp. Med., 179:881-118 (1994); Ponath, P. D., et al., J. Clin. Invest., 97:604-612 (1996)), and include proteins such as monocyte chemotactic proteins 1-4 (MCP-1, MCP-2, MCP-3, and MCP-4), RANTES, macrophage inflammatory proteins (MIP-1xcex1, MIP-1xcex2), thymus and activation-regulated chemokine (TARC; Imai et al., J. Biol. Chem. 271:21514-21521 (1996)) and macrophage-derived chemokine (MDC; Godiska et al., J. Exp. Med. 185:1595-1604 (1997)).
Chemokines bind to 7 transmembrane spanning G protein-coupled receptors (Murphy, P. M., Annu. Rev. Immunol., 12:593-633 (1994)). A number of xcex2 chemokine receptors (CCR1-CCR10) have been identified to date, and the search for additional chemokine receptors is the subject of active research (Baggiolini, Nature 392:565-568 (1998)). Chemokine receptor CCR4 was identified by Power et al. (J. Biol. Chem. 270:19495-19500 (1995); Genbank accession number X85740) and Meyer et al. (J. Biol. Chem. 271(24):14445-14451 (1996); Genbank accession number X94151). A murine homolog of human CCR4 has also been identified (Youn et al., Blood 89(12):4448-4460 (1997)). CCR4 was originally found to signal in response to MCP-1, MIP-1xcex1, and RANTES but more recently has been shown to be specific for the chemokines TARC and MDC (Imai et al., J. Biol. Chem. 272(23):15036-15042 (1997); Imai et al., J. Biol. Chem. 273:1764-1768 (1998)).
The selective recruitment of leukocyte subsets to sites of inflammation and the ordered trafficking of leukocytes through the circulation, tissues, lymphatic system and secondary lymphoid organs is controlled in part by the differential expression of chemokine receptors on subsets of cells. Such expression patterns would seem to ensure that a functionally related group of leukocytes can coordinately respond to a specific set of chemokines induced by a given stimulus. For T cells, PCR or Northern blotting indicates that the known receptors for CC chemokines are expressed on subsets of T cells. Delineating exactly which subsets express particular receptors is an area of intense study, because chemokine receptor expression may explain the localization or migration of various cell types, such as TH1 or TH2 T cells or tissue homing subsets. It may also determine which T cells are infected with different strains of HIV-1. However, most leukocytes express several chemokine receptors, many with complex and promiscuous ligand interactions. This makes elucidating the normal immune function for a specific receptor on a given cell type and determining the relevance to initiation and progression of disease difficult, especially since specific antibodies are not available for many chemokine receptors.
The present invention relates to an antibody (immunoglobulin) or functional fragment thereof (e.g., an antigen-binding fragment) which binds to a mammalian CC-chemokine receptor 4 (also referred to as CCR4, CKR-4, TARC-receptor and MDC receptor) or portion of the receptor (anti-CCR4). In one embodiment, the antibody of the present invention or fragment thereof has specificity for human CCR4 or a portion thereof. In another embodiment, the antibody or fragment of the invention blocks binding of a ligand (e.g., TARC, MDC, MCP-1, MIP-1xcex1, RANTES) to the receptor and inhibits function associated with binding of the ligand to the receptor (e.g., leukocyte trafficking). In a preferred embodiment, the ligand is TARC and/or MDC. For example, as described herein, antibodies and fragments thereof of the present invention which bind human CCR4 or a portion thereof, can block binding of a chemokine (e.g., TARC, MDC, MCP-1, MIP-1xcex1, RANTES) to the receptor and inhibit function associated with binding of the chemokine to the receptor. In a preferred embodiment, the chemokine is TARC and/or MDC. In one embodiment, the antibody is monoclonal antibody (mAb) LS141-1G1 (1G1) or an antibody which can compete with 1G1 for binding to human CCR4 or a portion of human CCR4. In another embodiment, the antibody is monoclonal antibody (mAb) LS185-2B10 (2B10) or an antibody which can compete with 2B10 for binding to human CCR4 or a portion of human CCR4. Functional fragments of the foregoing antibodies are also envisioned.
The present invention also relates to an antibody or functional fragment thereof (e.g., an antigen-binding fragment) which binds to a mammalian CCR4 or portion of the receptor and provides increased fluorescent staining intensity of CCR4 or compositions comprising CCR4 relative to other anti-CCR4 antibodies. In one embodiment, the antibody is monoclonal antibody 1G1 or 2B10 or an antibody which can compete with 1G1 or 2B10 for binding to human CCR4 or a portion of human CCR4.
The present invention further relates to a method of inhibiting the interaction of a cell bearing mammalian (e.g., human, non-human primate or murine) CCR4 with a ligand thereof, comprising contacting the cell with an effective amount of an antibody or functional fragment thereof which binds to a mammalian CCR4 or a portion of CCR4. Suitable cells include granulocytes, leukocytes, such as monocytes, macrophages, basophils and eosinophils, mast cells, and lymphocytes including T cells (e.g., CD8+ cells, CD4+ cells, CD25+ cells, CD45RO+ cells) such as Th1 and Th2 cells, and other cells expressing CCR4, such as a recombinant cell expressing CCR4 or portion thereof (e.g., transfected cells). In a particular embodiment, the antibody is 1G1 or 2B10 or an antibody which can compete with 1G1 or 2B10 for binding to human CCR4 or a portion of human CCR4.
Another embodiment of the invention relates to a method of inhibiting the interaction of a cell bearing mammalian CCR4 with a chemokine, comprising contacting said cell with an effective amount of an antibody or functional fragment thereof which binds to CCR4 or a portion of said receptor. In one embodiment of the method, the antibody or functional fragment thereof is any one or more of 1G1, 2B10, an antigen-binding fragment of 1G1 or 2B10, or an antibody or fragment thereof having an epitopic specificity which is the same as or similar to that of 1G1 or 2B10. Furthermore, the invention relates to a method of inhibiting a function associated with binding of a chemokine to CCR4, comprising administering an effective amount of an antibody or functional fragment thereof which binds to mammalian CCR4 or a portion of said receptor. In one aspect of the method, the antibody or functional fragment thereof is any one or more of 1G1, 2B10, an antigen-binding fragment of 1G1 or 2B10, or an antibody or fragment thereof having an epitopic specificity which is the same as or similar to that of 1G1 or 2B10.
Another aspect of the invention is a method of identifying expression of a mammalian CCR4 or portion of the receptor by a cell. According to the method, a composition comprising a cell or fraction thereof (e.g., a membrane fraction) is contacted with an antibody or functional fragment thereof (e.g., 1G1 or 2B10) which binds to a mammalian CCR4 protein or portion of the receptor under conditions appropriate for binding of the antibody thereto, and the formation of a complex between said antibody or fragment and said protein or portion thereof is detected. Detection of the complex, directly or indirectly, indicates the presence of the receptor or portion thereof on the cell or fraction thereof. The present invention also relates to a kit for use in detecting the presence of CCR4 or a portion thereof in a biological sample, comprising an antibody or functional fragment thereof which binds to a mammalian CCR4 or a portion of said receptor, and one or more ancillary reagents suitable for detecting the presence of a complex between said antibody or fragment and said protein or portion thereof.
Also encompassed by the present invention are methods of identifying additional ligands or other substances which bind a mammalian CCR4 protein, including inhibitors and/or promoters of mammalian CCR4 function. For example, agents having the same or a similar binding specificity as that of an antibody of the present invention or functional fragment thereof can be identified by a competition assay with said antibody or fragment. Thus, the present invention also encompasses methods of identifying ligands or other substances which bind the CCR4 receptor, including inhibitors (e.g., antagonists) or promoters (e.g., agonists) of receptor function. In one embodiment, cells which naturally express CCR4 receptor protein or suitable host cells which have been engineered to express a CCR4 receptor or variant encoded by a nucleic acid introduced into said cells are used in an assay to identify and assess the efficacy of ligands, inhibitors or promoters of receptor function. Such cells are also useful in assessing the function of the expressed receptor protein or polypeptide.
Thus, the invention also relates to a method of detecting or identifying an agent which binds a mammalian CCR4 or ligand binding variant thereof, comprising combining an agent to be tested, an antibody or antigen-binding fragment of the present invention (e.g., monoclonal antibody 1G1, monoclonal antibody 2B10, an antibody having an epitopic specificity which is the same as or similar to that of 1G1 or 2B10, antigen-binding fragments of 1G1 or 2B10) and a composition comprising a mammalian CCR4 protein or a ligand binding variant thereof. The foregoing components can be combined under conditions suitable for binding of the antibody or antigen-binding fragment to mammalian CCR4 protein or a ligand binding variant thereof, and binding of the antibody or fragment to the mammalian CCR4 protein or ligand binding variant is detected or measured, either directly or indirectly, according to methods described herein or other suitable methods. A decrease in the amount of complex formed relative to a suitable control (e.g., in the absence of the agent to be tested) is indicative that the agent binds said receptor or variant. The composition comprising a mammalian CCR4 protein or a ligand binding variant thereof can be a membrane fraction of a cell bearing recombinant CCR4 protein or ligand binding variant thereof. The antibody or fragment thereof can be labeled with a label such as a radioisotope, spin label, antigen label, enzyme label, fluorescent group and chemiluminescent group. These and similar assays can be used to detect agents, including ligands (e.g., chemokines which interact with CCR4) or other substances, including inhibitors or promoters of receptor function, which can bind CCR4 and compete with the antibodies described herein for binding to the receptor.
According to the present invention, ligands, inhibitors or promoters of receptor function can be identified in a suitable assay, and further assessed for therapeutic effect. Inhibitors of receptor function can be used to inhibit (reduce or prevent) receptor activity, and ligands and/or promoters can be used to induce (trigger or enhance) normal receptor function where indicated. The present invention also provides a method of treating inflammatory diseases, autoimmune diseases, atherosclerosis, and graft rejection, or HIV infection, comprising administering an inhibitor of receptor function (e.g., chemokine binding or HIV binding) to an individual (e.g., a mammal, such as a human). The present invention further provides a method of stimulating receptor function by administering a novel ligand or promoter to an individual, providing a new approach to selective stimulation of leukocyte function, which is useful, for example, in the treatment of infectious diseases and cancer.
The present invention also encompasses a method of inhibiting leukocyte trafficking in a patient, comprising administering to the patient an effective amount of an antibody or functional fragment thereof which binds to a mammalian CCR4 or portion of said receptor and inhibits function associated with binding of a ligand to the receptor.
The present invention also relates to a method of inhibiting or treating CCR4-mediated disorders, such as inflammatory disorders, comprising administering to a patient an effective amount of an antibody or functional fragment thereof which binds to a mammalian CCR4 or portion of said receptor and inhibits CCR4-mediated function.
The present invention further relates to an antibody or fragment thereof as described herein (e.g., monoclonal antibody 1G1, monoclonal antibody 2B10, an antigen-binding fragment of 1G1 or 2B10, an antibody having an epitopic specificity which is the same as or similar to that of 1G1 or 2B10) for use in therapy (including prophylaxis) or diagnosis, and to the use of such an antibody or fragment for the manufacture of a medicament for the treatment of a CCR4-mediated disorder, or other disease or inflammatory condition as described herein.

Anti-CCR4 antibodies and methods of use therefor


Methods for the therapeutic use of competitive inhibitors of the CCR5/CCL5 axis that express antagonist activity for RANTES (CCL5) for immunomodulatory treatment of subjects in need thereof. The competitive inhibitors may not have CCL5 agonist activity and can be used to inhibit, interrupt, block, mitigate, slow the progress of, and/or treat inflammation and/or various other CCR5/CCL5 axis signaling dependent down-stream activities associated with transplantation, including graft versus host disease, autoimmune disorders, infectious agents, chronic inflammation, and cancer, etc.

Inflammation may occur in response to trauma, chemical or physical injury, autoimmune responses, infectious agents, cancer, etc. Inflammation is an important component of innate immunity and is necessary for priming adaptive immunity and for the effecter phase of the immune response. Soluble mediators, such as chemokines, are shown to play an important role in driving the various components of inflammation, especially leukocyte influx.
Chemokines bind to their receptors which are expressed on many cell types, including, for example, leukocytes, endothelial cells, fibroblasts, epithelial, smooth muscle and parenchymal cells. Chemokines play an important role in leukocyte biology, by controlling cell recruitment and activation in basal and in inflammatory circumstances. In addition, because chemokine receptors are expressed on other cell types, chemokines have multiple other roles, including angiogenesis, tissue and vascular remodeling, pathogen elimination, antigen presentation, leukocyte activation and survival, chronic inflammation, tissue repair/healing, fibrosis, embryogenesis, tumorigenesis, etc.
CCL5 (C-C chemokine ligand 5), an inflammatory chemokine also known as regulated upon activation and normal T cell expressed and secreted (RANTES), plays an important role in these immunologic mechanisms. CCL5 acts as a key regulator of T-cell migration to inflammatory sites, directing migration of T cells to damaged or infected sites. CCL5 also regulates T-cell differentiation. Many biologic effects of chemokines are mediated by their interaction with chemokine receptors on cell surfaces. In the present invention, the most relevant known receptor for CCL5 is the CCR5 receptor; however, CCR1 and CCR3 are also known CCL5 receptors and CCR4 and CD44 are auxiliary receptors. Tamamis et al., Elucidating a Key Anti-HIV-1 and Cancer-Associated Axis: The Structure of CCL5 (Rantes) in Complex with CCR5, SCIENTIFIC REPORTS; 4:5447 (2014).
Inflammatory chemokines have long been viewed mainly as indispensable "gate keepers" of immunity and inflammation. However, recent research indicates that, for example, cancer cells subvert the normal chemokine system and these molecules and their receptors become important constituents of the tumor microenvironment with very different ways to exert tumor-promoting roles. While the CCR5 receptor and the CCL5 ligand have been detected in some hematological malignancies, lymphomas, and a great number of solid tumors, extensive studies on the role of the CCL5 ligand/CCR5 receptor axis have only been performed only in a limited number of cancers. Aldinucci et al., The Inflammatory chemokine CCL5 and Cancer Progression, MEDIATORS OF INFLAMMATION, vol. 2014, article ID 292376, 12 pages.
The CCR5 receptor is a C-C chemokine G-coupled protein receptor expressed on lymphocytes, monocytes, macrophages, dendritic cells, a subset of T cells, etc. The CCR5 receptor spans the cellular plasma membrane seven times in a serpentine manner. The extracellular portions represent potential targets for HIV-inhibitory mAbs and comprise an amino-terminal domain (Nt) and three extracellular loops (ECL1, ECL2, and ECL3). The extracellular portions of CCR5 comprise just 90 amino acids distributed over four domains. The largest of these domains are at the Nt and ECL2 at approximately 30 amino acids each. Olson et al., CCR5 Monoclonal Antibodiesfor HIV-1 Therapy, CURR. OPIN. HIV AIDS, March; 4(2): 104-111 (2009).
The formation of the CCRL ligand and CCR5 receptor complex causes a conformational change in the receptor that activates the subunits of the G-protein, inducing signaling and leading to changed levels of cyclic AMP (cAMP), inositol triphosphate, intracellular calcium and tyrosine kinase activation. These signaling events cause cell polarization and translocation of the transcription factor NF-kB, which results in the increase of phagocytic ability, cell survival, and transcription of proinflammatory genes. Once G-protein dependent signaling occurs, the CCL5/CCR5 receptor complex is internalized via endocytosis.
A complete complex structure of CCL5 in complex with CCR5 was recently computationally derived. It is reported that the 1-15 residue moiety of CCL5 is inserted into the CCR5 binding pocket; the 1-6 N-terminal domain of CCL5 is buried within the transmembrane region of CCR5, and the 7-15 residue moiety of CCL5 is predominantly encompassed by the N-terminal domain and extracellular loops of CCR5. CCL5 residues Ala16, Arg17 and additional residues of the 24-50 residue moiety interact with the upper N-terminal domain and extracellular loop interface of CCR5. It is further reported that the integrity of the amino terminus of CCL5 is crucial to receptor binding and cellular activation. Further, it has been reported that CCL5 and HIV-1 primarily interact with mostly the same CCR5 residues, and share the same chemokine receptor binding pocket. See Tamamis et al., Elucidating a Key Anti-HIV-1 and Cancer-Associated Axis: The Structure of CCL5 (Rantes) in Complex with CCR5, SCIENTIC REPORTS; 4:5447 (2014). It is also separately reported that chemokines, such as the CCL5 ligand, principally bind the CCR5 receptor through ECL2. Olson et al., CCR5 Monoclonal Antibodies for HIV-1 Therapy, CURR. OPIN. HIV AIDS, March; 4(2): 104-111 (2009).
Evidence suggests that CCL5/CCR5 axis signaling may be preferentially activated in certain types of cancers, for example breast and prostate cancers, and that such signaling facilitates disease progression. Exploratory efforts using anti-CCR5 binding agents to alter CCL5/CCR5 signaling in connection with some cancer types have been made. Sicoli et al., CCR5 Receptor Antagonists Block Metastasis to Bone of v-Src Oncogene-Transformed Metastatic Prostate Cancer Cell Lines, CANCER RES. 74(23), (2014); Velasco-Velizquez et al., The CCL5/CCR5Axis Promotes Metastasis In Basal Breast Cancer, ONCOIMMUNOLOGY, vol. 2, issue 4 (2013); and Velasco-Velázquez et al., CCR5Antagonis Blocks Metastasis of Basal Breast Cancer Cells, CANCER RES. 72(15), (2012).
Various compounds exist that inhibit, interrupt, block, alter, or modify the CCR5/CCL5 receptor/ligand axis (i.e., CCR5 receptor/CCL5 ligand axis). Many of these compounds have been developed for the treatment of HIV-1, which also binds with the CCR5 receptor and is known to share some binding commonalities with CCL5. Such compounds include extracellular or cell transmembrane CCR5 binding agents such as, for example, PRO 140 (extracellular) and maraviroc (transmembrane), and other compounds such as vicriviroc, aplaviroc, SCH-C, TAK-779, and antibodies such as PA14, 2D7, RoAb13, RoAb14, 45523, etc. It has been found that the most potently antiviral anti-CCR5 monoclonal antibodies including, for example, PRO140, bind CCR5 receptor amino acid residues in EL2 alone or in combination with Nt residues. It has also been determined that the CCR5 receptor binding sites for anti-CCR5 monoclonal antibodies are distinct from small-molecule CCR5 antagonists. That is, available small-molecule CCR5 antagonists, such as maraviroc, bind the hydrophobic cavity formed by the transmembrane helices, i.e., not the extracellular Nt or loop regions. The amino acid residue E283 in the seventh transmembrane region has been specifically identified as a principle site or interaction for small molecules, and maraviroc and vicriviroc were found to bind to identical sets of CCR5 receptor amino acids. Olson et al., CCR5 Monoclonal Antibodies for HIV-1 Therapy, CURR. OPIN. HIV AIDS, March; 4(2): 104-111 (2009).
It has also been reported, however, that the CCL5 ligand and maraviroc dock on the CCR5 receptor by sharing two receptor sites: the Nt and the ECL2, and that synthetic CCL5-derived peptides may also be used to block the CCR5 receptor. Secchi et al., Combination of the CCL5-Derived Peptide R4.0 with Different HIV-1 Blockers Reveals Wide Target Compatibility and Synergic Cobinding to CCR5, ANTIMICROBIAL AGENTS AND CHEMOTHERAPY, pp. 6215-6223; October (2014).
In vitro studies to investigate the effects of CCR5 receptor blockade by maraviroc on activated human T cells on potential immunological mechanisms have been conducted. It was found that blocking CCR5 by maraviroc not only can block CCR5 and CCR2 internalization processes induced by CCL5 and CCL2, but can also inhibit T cell chemotactic activities toward their cognate ligands, respectively. Further, blocking CCR5 with maraviroc at high doses tends to decrease production of TNF-α and IFN-γ. It was also noted that the effect of maraviroc on CCR5 was temporary and reversible. Yuan et al., In Vitro Immunological Effects of Blocking CCR5 on T Cells, INFLAMMATION, vol. 38, no. 2, (2015); see Arberas et al., In vitro effects of the CCR5 inhibitor maraviroc on human T cell function, J. ANTIMICROB. CHEMOTHER., 68: 577-586 (2013).
There exists a need, however, for improved competitive inhibitors to the CCR5 receptor and methods of use that can be used to inhibit, dampen, interrupt, block, alter, or modify the CCR5/CCL5 receptor/ligand axis for therapeutic purposes without triggering, or that reduce the impact of, unintended side effects. Further, there is a need for such competitive inhibitors to the CCR5 receptor and methods of use that cause fewer and less severe side effects, are longer-lasting, and facilitate improved patient compliance due to decreased dosing demands and improved patient experience (due to fewer undesirable side effects), including side effects caused by the competitive inhibitor itself.
Optimal therapeutic modalities using the CCL5/CCR5 axis as a therapeutic target will need to accommodate two opposing demands: the need to inhibit the detrimental involvement of CCL5 and CCR5 in specific malignant diseases while protecting their potentially beneficial activities in immunity.

Inhibition of CCL5 ligand binding to CCR5 receptor and alteration of CCR5/CCL5 axis signaling in inflammation, cancer, autoimmune, and other conditions


A selective etching process cuts shapes from amorphous metal strip feedstock. The etching process comprises depositing a chemically resistant material to one side of the strip in a pattern that defines the requisite shape, mating the metal strip with a carrier strip, exposing at least one side of the metal strip to an etching agent to selectively etch the desired shape, and separating the shape from the strip feedstock. A plurality of layers of the shapes is assembled by adhesive lamination to form a generally polyhedrally shaped bulk amorphous metal magnetic component useful in high efficiency electric motors and inductive devices. The bulk amorphous metal magnetic component may include an arcuate surface, and preferably includes two arcuate surfaces that are disposed opposite to each other. The magnetic component is operable at frequencies ranging from about 50 Hz to about 20,000 Hz. When the component is operated at an excitation frequency “f” to a peak induction level Bmax, the component exhibits a core-loss less than about “L” wherein L is given by the formula L=0.005 f(Bmax)1.5+0.000012 f1.5(Bmax)1.6, said core loss, said excitation frequency and said peak induction level being measured in watts per kilogram, hertz, and teslas, respectively. Performance characteristics of the bulk amorphous metal magnetic component of the present invention are significantly better than those of silicon-steel components operated over the same frequency range.

1. Field of the Invention
This invention relates to a process for producing cut shapes of amorphous metal, and more particularly, to a selective etching process for producing cut laminations that are bonded together to form a generally polyhedrally shaped, low core loss, bulk amorphous metal magnetic component useful in electric motors and inductive magnetic devices.
2. Description of the Prior Art
Magnetic components made from a plurality of stacked laminations of sheet-form magnetic materials are widely used in electric motors and in inductive devices such as transformers, ballasts, inductors, saturable reactors, and the like. The magnetic material is typically selected based on both the required device properties and economic considerations.
Non-oriented electrical steel is most frequently chosen for electric motor components. In variable reluctance motors and eddy current motors, the stators are made from stacked laminations. Both the stator and the rotor are made from stacked laminations in squirrel cage motors, reluctance synchronous motors and switched reluctance motors. Each lamination is typically formed by stamping, punching or cutting the mechanically soft, non-oriented electrical steel into the desired shape. The formed laminations are then stacked and bound to form rotors or stators that have the desired geometry, along with sufficient mechanical integrity to maintain their configuration during production and operation of the motor.
The stator and the rotor in a rotating electrical machine are separated by small gaps that are either: (i) radial, i.e., generally perpendicular the axis of rotation of the rotor, or (ii) axial, i.e., generally parallel to the rotation axis and separated by some distance. In a dynamoelectric machine, lines of magnetic flux link the rotor and stator by traversing the gaps. Electromagnetic machines thus may be broadly classified as radial or axial flux designs, respectively. The corresponding terms radial and axial gap designs are also used in the motor art. Radial flux machines are by far most common. The aforesaid punching and stacking methods are widely used for constructing rotors and stators for radial flux motors.
Although amorphous metals offer superior magnetic performance when compared to non-oriented electrical steels, they have long been considered unsuitable for use in bulk magnetic components such as the rotors and stators of electric motors due to certain physical properties and the ensuing impediments to fabrication. For example, amorphous metals are thinner and harder than non-oriented steel, and consequently cause fabrication tools and dies to wear more rapidly. The resulting increase in the tooling and manufacturing costs makes fabricating bulk amorphous metal magnetic components using such conventional techniques, such as punching and stamping, commercially impractical. The thinness of amorphous metals also translates into an increased number of laminations in the assembled components, further increasing the total cost of an amorphous metal rotor or stator magnet assembly.
Amorphous metal is typically supplied in a thin continuous ribbon having a uniform ribbon width. However, amorphous metal is a very hard material, making it very difficult to cut or form easily. Once annealed to achieve peak magnetic properties, amorphous metal ribbon becomes very brittle. This makes it difficult and expensive to use conventional approaches to construct a bulk amorphous metal magnetic component. The brittleness of amorphous metal ribbon may also cause concern for the durability of the bulk magnetic component in an application such as an electric motor.
Magnetic stators are subject to extremely high magnetic forces, which vary rapidly at the frequencies needed for high rotational speed. These magnetic forces are capable of placing considerable stresses on the stator material, and may damage an amorphous metal magnetic stator. Rotors are further subjected to mechanical forces due both to normal rotation and to rotational acceleration when the machine is energized or de-energized and when the loading changes, perhaps abruptly.
A limited number of non-conventional approaches have been proposed for constructing amorphous metal components. For example, U.S. Pat. No. 4,197,146 to Frischmann discloses a stator fabricated from molded and compacted amorphous metal flake. Although this method permits formation of complex stator shapes, the structure contains numerous air gaps between the discrete flake particles of amorphous metal. Such a structure greatly increases the reluctance of the magnetic circuit and thus the electric current required to operate the motor.
The approach taught by German Patents DE 28 05 435 and DE 28 05 438 divides the stator into wound pieces and pole pieces. A non-magnetic material is inserted into the joints between the wound pieces and pole pieces, increasing the effective gap, and thus increasing the reluctance of the magnetic circuit and the electric current required to operate the motor. The layers of material that comprise the pole pieces are oriented with their planes perpendicular to the planes of the layers in the wound back iron pieces. This configuration further increases the reluctance of the stator, because contiguous layers of the wound pieces and of the pole pieces meet only at points, not along full line segments, at the joints between their respective faces. In addition, this approach teaches that the laminations in the wound pieces are attached to one another by welding. The use of heat intensive processes, such as welding, to attach amorphous metal laminations will recrystallize the amorphous metal at and around the joint. Even small sections of recrystallized amorphous metal will normally increase the magnetic losses in the stator to an unacceptable level.
Another difficulty associated with the use of ferromagnetic amorphous metals arises from the phenomenon of magnetostriction. Certain magnetic properties of any magnetostrictive material change in response to imposed mechanical stress. For example, the magnetic permeability of a component containing amorphous materials typically is reduced and the core losses increased when the component is subjected to stress. The degradation of soft magnetic properties of the amorphous metal device due to the magnetostriction phenomenon may be caused by stresses resulting from any combination of sources, including: (i) magnetic and mechanical forces during the operation of the electric motor; (ii) mechanical stresses resulting from mechanical clamping or otherwise fixing the bulk amorphous metal magnetic components in place; or (iii) internal stresses caused by the thermal expansion and/or expansion due to magnetic saturation of the amorphous metal material. As an amorphous metal magnetic stator is stressed, the efficiency at which it directs or focuses magnetic flux is reduced, resulting in higher magnetic losses, reduced efficiency, increased heat production, and reduced power. The extent of this degradation may be considerable depending upon the particular amorphous metal material and the actual intensity of the stresses, as indicated by U.S. Pat. No. 5,731,649 ("the '649 patent"). The degradation of core loss is often expressed as a destruction factor, i.e., a ratio of the core loss actually exhibited by a finished device and the inherent core loss of the constituent material tested under stress-free, laboratory conditions.
Moreover, amorphous metals have far lower anisotropy energies than other conventional soft magnetic materials, including common electrical steels. As a result, stress levels that would not have a deleterious effect on the magnetic properties of these conventional metals have a severe impact on magnetic properties important for motor components, e.g. permeability and core loss. For example, the '649 patent further discloses that forming amorphous metal cores by rolling amorphous metal into a coil, with lamination using an epoxy, detrimentally restricts the thermal and magnetic saturation expansion of the coil of material, resulting in high internal stresses and magnetostriction that reduces the efficiency of a motor or generator incorporating such a core. In order to avoid stress-induced degradation of magnetic properties, the '649 patent discloses a magnetic component comprising a plurality of stacked or coiled sections of amorphous metal carefully mounted or contained in a dielectric enclosure without the use of adhesive bonding.
A number of applications in current technology, including such widely diverse areas such as high-speed machine tools, aerospace motors and actuators, and spindle drive motors for magnetic and optical disk drives used for data storage in computers and other microelectronic devices, require electrical motors operable at high speeds, many times in excess of 15,000-20,000 rpm, and in some cases up to 100,000 rpm. The limitations of magnetic components made using existing materials entail substantial and undesirable design compromises. In many applications, the core losses of the electrical steels typically used in motor components are prohibitive. In such cases a designer may be forced to use a permalloy alloy as an alternative. However, the attendant reduction in saturation induction (e.g. 0.6-0.9 T or less for various permalloy alloys versus 1.8-2.0 T for ordinary electrical steels) necessitates an increase in the size of magnetic components comprised of permalloy or variants thereof. Furthermore, the desirable soft magnetic properties of the permalloys are adversely and irreversibly affected by plastic deformation, which can occur at relatively low stress levels. Such stresses may occur either during manufacture or operation of the permalloy component.
Inductive devices are essential components of a wide variety of modern electrical and electronic equipment, most commonly including transformers and inductors. Most of these non-rotating devices employ a core comprising a soft ferromagnetic material and one or more electrical windings that encircle the core. Inductors generally employ a single winding with two terminals, and serve as filters and energy storage devices. Transformers generally have two or more windings. They transform voltages from one level to at least one other desired level, and electrically isolate different portions of an overall electric circuit. Inductive devices are available in widely varying sizes with correspondingly varying power capacities. Different types of inductive devices are optimized for operation at frequencies over a very wide range, from DC to GHz. Virtually every known type of soft magnetic material finds application in the construction of inductive devices. Selection of a particular soft magnetic material depends on the combination of properties needed, the availability of the material in a form that lends itself to efficient manufacture, and the volume and cost required to serve a given market. In general, a desirable soft ferromagnetic core material has high saturation induction Bsat to minimize core size, along with low coercivity Hc, high magnetic permeability μ, and low core loss to maximize efficiency.
Components of small to moderate size inductors and transformers for electrical and electronic devices are also frequently constructed using laminations punched from various grades of magnetic steel supplied in sheets having thickness as low as 100 μm. The laminations are generally stacked and secured and subsequently wound with the requisite one or more electrical windings that typically comprise high conductivity copper or aluminum wire. These laminations are commonly employed in cores with a variety of known shapes.
Many of the shapes used for inductor and transformer cores are assembled from constituent components that have the general form of certain block letters, such as "C," "U," "E," and "I", by which the components are often identified. The assembled shape may further be denoted by the letters reflecting the constituent components; for example, an "E-I" shape would be made by assembling an "E" component with an "I" component. Other widely used assembled shapes include "E-E," "C-I," and "C-C." Constituent components for prior art cores of these shapes have been constructed of both laminated sheets of conventional crystalline ferromagnetic metal and machined bulk soft ferrite blocks.
A significant trend in recent electronics technology has been the design of power supplies, converters, and related circuits using switch-mode circuit topologies. The increased capabilities of available power semiconductor switching devices have allowed switch-mode devices to operate at increasingly high frequencies. Many devices that formerly were designed with linear regulation and operation at line frequencies (generally 50-60 Hz on the power grid or 400 Hz in military applications) are now based on switch-mode regulation at frequencies that are often 5-200 kHz, and sometimes as much as 1 MHz. A principal driving force for the increase in frequency is the concomitant reduction in the size of the required magnetic components, such as transformers and inductors. However, the increase in frequency also markedly increases the magnetic losses of these components. Thus there exists a significant need to lower these losses.
The limitations of magnetic components made using existing materials entail substantial and undesirable design compromises. In many applications, the core losses of the common electrical steels are prohibitive. In such cases a designer may be forced to use a permalloy alloy or a ferrite as an alternative. However, the attendant reduction in saturation induction (e.g. 0.6-0.9 T or less for various permalloy alloys and 0.3-0.4 T for ferrites, versus 1.8-2.0 T for ordinary electrical steels) necessitates an increase in the size of the resulting magnetic components. Furthermore, the desirable soft magnetic properties of the permalloys are adversely and irreversibly affected by plastic deformation which can occur at relatively low stress levels. Such stresses may occur during either manufacture or operation of the permalloy component. While soft ferrites often have attractively low losses, their low induction values result in impractically large devices for many applications wherein space is an important consideration. Moreover, the increased size of the core undesirably necessitates a longer electrical winding, so ohmic losses increase.
For electronic applications such as saturable reactors and some chokes, amorphous metal has been employed in the form of spirally wound, round toroidal cores. Devices in this form are available commercially with diameters typically ranging from a few millimeters to a few centimeters and are commonly used in switch-mode power supplies providing up to several hundred volt-amperes (VA). This core configuration affords a completely closed magnetic circuit, with negligible demagnetizing factor. However, in order to achieve a desired energy storage capability, many inductors include a magnetic circuit with a discrete air gap. The presence of the gap results in a non-negligible demagnetizing factor and an associated shape anisotropy that are manifested in a sheared magnetization (B-H) loop. The shape anisotropy may be much higher than the possible induced magnetic anisotropy, increasing the energy storage capacity proportionately.
Toroidal cores made with discrete air gaps and conventional material have been proposed for such energy storage applications. However, the gapped toroidal geometry affords only minimal design flexibility. It is generally difficult or impossible for a device user to adjust the gap so as to select a desired degree of shearing and energy storage. In addition, the equipment needed to apply windings to a toroidal core is more complicated, expensive, and difficult to operate than comparable winding equipment for laminated cores. Oftentimes a core of toroidal geometry cannot be used in a high current application, because the heavy gage wire dictated by the rated current cannot be bent to the extent needed in the winding of a toroid. In addition, toroidal designs have only a single magnetic circuit. As a result, they are not well suited and are difficult to adapt for polyphase transformers and inductors, including especially common three-phase devices. Other configurations more amenable to easy manufacture and application are thus sought.
Moreover, the stresses inherent in a strip-wound toroidal core give rise to certain problems. The winding inherently places the outside surface of the strip in tension and the inside in compression. Additional stress is contributed by the linear tension needed to insure smooth winding. As a consequence of magnetostriction, a wound toroid typically exhibits magnetic properties that are inferior to those of the same strip measured in a flat strip configuration. Annealing in general is able to relieve only a portion of the stress, so only a part of the degradation is eliminated. In addition, gapping a wound toroid frequently causes additional problems. Any residual hoop stress in the wound structure is at least partially removed on gapping. In practice the net hoop stress is not predictable and may be either compressive or tensile. Therefore the actual gap tends to close or open in the respective cases by an unpredictable amount as required to establish a new stress equilibrium. Therefore, the final gap is generally different from the intended gap, absent corrective measures. Since the magnetic reluctance of the core is determined largely by the gap, the magnetic properties of finished cores are often difficult to reproduce on a consistent basis in the course of high-volume production.
Amorphous metals have also been used in transformers for much higher power devices, such as distribution transformers for the electric power grid that have nameplate ratings of 10 kVA to 1 MVA or more. The cores for these transformers are often formed in a step-lap wound, generally rectangular configuration. In one common construction method, the rectangular core is first formed and annealed. The core is then unlaced to allow pre-formed windings to be slipped over the long legs of the core. Following incorporation of the pre-formed windings, the layers are relaced and secured. A typical process for constructing a distribution transformer in this manner is set forth in U.S. Pat. No. 4,734,975 to Ballard et al. Such a process understandably entails significant manual labor and manipulation steps involving brittle annealed amorphous metal ribbons. These steps are especially tedious and difficult to accomplish with cores smaller than 10 kVA. Furthermore, in this configuration, the cores are not readily susceptible to controllable introduction of an air gap, which is needed for many inductor applications.
Notwithstanding the advances represented by the above disclosures, there remains a need in the art for improved amorphous metal magnetic components that exhibit a combination of excellent magnetic and physical properties needed for high speed, high efficiency rotating electric machines, as well as other non-rotating inductive devices. Construction methods are also sought that use amorphous metal efficiently and can be implemented for high volume production of motors of various types and magnetic components.

This patent is subject to a terminal disclaimer.

Selective etching process for cutting amorphous metal shapes and components made thereof


A method of recovering a lost or corrupted data packet of a plurality of data packets transmitted by a transmitting computer system to a target computer system over an unreliable computer network. In one embodiment, the transmitting computer system generates parity information by padding the plurality of data packets to the length of the longest data packet with a suitable bit pattern. The parity information is then generated using a suitable algorithm, such as an exclusive OR (XOR) operation. The parity information and the packet lengths of the data packets are used to form the parity packet. The transmitting computer system then sends both the data packets and the parity packet to the target computer. If the target computer system detects a lost or corrupted data packet, the target computer attempts to reconstruct the lost or corrupted data packet. The received uncorrupted data packets are padded with the suitable bit pattern described above. Note that it is useful to pad up to the length of the lost data packet. The inverse operation of the parity generating algorithm is then applied to the padded data packets and the parity packet to reconstruct the lost or corrupted data packet.

1. Field of the Invention
The present invention relates to network reliability. More particularly, the present invention relates to the recovery of lost data packets over a network.
2. Description of the Related Art
With the proliferation of connections to the internet by a rapidly growing number of consumers, traffic on the internet has increased correspondingly. As a result, network congestion and the loss of data packets at the network level are serious problems.
While higher level protocols such as TCP/IP can guarantee packet arrival in an otherwise low reliability network, reliability is generally accomplished at the cost of increased overhead resulting from additional handshaking and retransmissions. Hence, efficiency is sacrificed for increased reliability.
There are several conventional schemes for increasing network level reliability. One conventional scheme for recovering of lost/corrupted data packets is striping. Striping involved the generation and transmission of parity information for a block of data packets having equal packet lengths. Accordingly, striping is not suitable for data packets having unequal packet lengths.
Another conventional scheme for error recovery of corrupted data packets is packet-level parity in which parity information of each data packet is embedded within and transmitted with the respective data packets. However, in the case of a catastrophic loss, e.g., a loss of the entire packet, embedded parity information is not helpful because the parity information was transmitted with the data packet, and presumed to have suffered the same fate, e.g., lost, as the data portion of the data packet.
In view of the foregoing, there are desired improved techniques for efficient recovery of lost/corrupted packets having different packet lengths transmitted over a computer network which efficiently utilizes the network resources.

Error correction and loss recovery of packets over a computer network


Embodiments of the present invention are directed to techniques for selecting a data path over which to exchange information between a client device and a storage system by making a selection between a file system server (NAS) data path type (a first data path type) and a direct (SAN) data path type (a second data path type) based on one or more adjustable path selection factors and/or information regarding components of the computer system. For example, a data path may be selected based on one or more performance characteristics of a computer system in which a path selection module is acting and/or any other suitable path selection factor.

1. Field of Invention
Embodiments of the present invention relate to techniques for selecting a data path over which to exchange information between a client device and a storage system. More specifically, embodiments of the invention relate to processes and systems for making a selection between a first data path and a second data path extending between the client device and the storage system, in which the first data path passes through a file system server so that the client device exchanges the information with the storage system using a file system interface for the storage system, and in which the second data path does not pass through the file system server.
2. Discussion of Related Art
In some conventional computer configurations, a data storage system is employed to provide a centralized storage point for data which may be written to or read from by one or more computers including, for example, clients and servers (referred to collectively as clients) coupled to the storage system. These conventional data storage systems may be accessed in a number of ways. In one implementation, a file system interface is provided for the data storage system, and as the one or more clients exchanges data with the storage system, the file system determines where the data should be written to or read from. This is often referred to as a network-attached storage (NAS) system wherein the file system interface enables data on the storage system to be shared by the clients.
A file system interface may be provided via a server that is separate from the data storage system. This implementation removes the processing associated with the file system functionality from the data storage system. In a computer configuration according to this implementation, a computer seeking to exchange data with the data storage system will instead exchange data with the file system server, and the file system server will use its knowledge of the structure and format of the data storage system to write the data to the data storage system or read the data from the data storage system.
In some conventional networks operating according to the latter technique discussed above, it was appreciated that transferring the data from the storage system to the file system server and from the file system server to the requesting client can result in an inefficient extra step in the exchange for some transactions. Some NAS computer configurations therefore used a third technique. In this third implementation, a computer seeking to exchange small amounts of data (e.g., amounts of data below a specified threshold amount) would exchange the data through the file system server over a first data path in the conventional manner, but for large amounts of data (e.g., amounts of data above the specified threshold amount) the client would interact directly with the data storage system over a second data path that does not include the file system server. For large amounts of data, then, a client would request from the file system server information (e.g., metadata) about where the requested data is stored on the storage system, and then would use this information to interact with the data storage system directly to retrieve the data. An illustrative system which operates according to this technique is the Celerra Multi-Path File System (MPFS) (also known as the HighRoad system) available from EMC Corporation of Hopkinton, Mass.
A conventional computer system implementing the third technique is shown in FIG. 1. A client computer 102 is shown in a computer system 100 along with a file system server 104 and a data storage system 106. The client computer 102 is connected to the file system server 104 and to the data storage system 106, and the file system server 104 is connected to the data storage system 106. Computer software is installed on the client computer 102 having instructions on how to exchange data between the client computer 102 and the data storage system 106, and the computer software is configured by an administrator with a threshold size (e.g., 64 kilobytes). This threshold is used by the computer 102 (i.e., by the computer software executing on the computer 102) when determining how to exchange data between the client computer 102 and the data storage system 106. For example, if a computer 102 seeks to write 32 KB of data to a file stored on the data storage system 106, then the computer 102 will send the 32 KB of data to the file system server 104 and the file system server 104 will write the 32 KB of data to the appropriate location in the data storage system 106 (i.e., the location of the file in the data storage system 106). If, however, the computer 102 seeks to write 128 KB of data to a file stored on the data storage system 106, then the computer 102 will receive from the file system server 104 metadata specifying the location in the data storage system 106 of the data blocks that make up the file, and then will write the 128 KB of data directly to the data storage system 106 in the location(s) specified by the file system server 104.
It should be appreciated that the diagram of FIG. 1 is merely a simple, conceptual representation of the types of systems which may be implemented in accordance with the third technique. In the diagram, while one of each element (e.g., client computer, file system server, data storage system) is shown, in some implementations there may be a plurality of client computers, a plurality of file system servers, and/or a plurality of storage systems. Additionally, while the data paths between the elements of the network are shown in FIG. 1 as direct connections, the data paths may be implemented in any suitable manner, such as in a computer network comprising a plurality of network links and networking devices such as routers and switches. Each of the three data paths shown in FIG. 1 may be implemented as a separate computer network implemented in any suitable manner (i.e., with any suitable network links and any suitable protocol) or otherwise. Additionally, each of the data paths shown in FIG. 1 may be implemented as a plurality of parallel links (e.g., the data path between the client computer 102 and the data storage system 106 may be a number of links all connecting the client computer to the data storage system 106 in parallel). Selecting an individual link of a data path, once a data path type is selected, may be done in any suitable manner. An example of a system that may be used to select a specific link once a path type is selected is the PowerPath system available from EMC Corporation.
When parallel links are employed (e.g., between the client computer and the file system server and/or the storage system), the techniques described above can be employed to select a data path type for handling an I/O operation (i.e., a data path that passes through the file system server or one that does not), and any suitable technique can be employed for selecting one or more specific links of the selected type.

Selection of a data path based on one or more performance characteristics of a computer system


An improved method of printing with a machine having at least one printing head and at least one platen registerable therewith. The method may include the steps of placing an article on the platen, bringing the platen and article into registerable contact with a printing screen supported at the printing head and transferring ink through the printing screen to the article after which the platen and article are separated from the printing screen. The method is improved by additional steps of extending a heating element into the space and directing heat toward the platen to cure the ink printed thereon.

1. Field of the Invention
The present invention pertains to methods of printing. More specifically, it pertains to an improved method of printing especially suitable for automatic printers with multiple printing stations.
2. Description of the Prior Art
The printing of paper textiles and other materials has been done, of course, in many ways over the centuries. In recent decades, the printing of paper posters and prints and textile articles such as blouses and shirts, with a myriad of designs, has become very popular. In such methods, the article to be printed in typically mounted on some sort of platen by which it is brought into contact with a mesh screen on which a particular print pattern is disposed. Some type of ink dispensing device is engaged with the screen and ink dispensed through the pattern for transfer to the article.
In recent years, printing of textile articles such as shirts and blouses has been done on a machine referred to as an automatic textile printer. These automatic textile printers usually have a frame about which is supported, perhaps on radial arms, a plurality of printing head each one of which may be capable of supporting a printing screen for engagement by an ink dispensing device. The frame of the automatic textile printer also supports a platen assembly which has a number of platens which are sequentially moveable into registration with usually adjacent ones of the printing heads. Typically, there are two more platens than the number of printing heads so that a textile article may be simultaneously placed on one and removed from another without interference from components at the printing heads.
In a typical method, a textile article is placed on a platen and the platen is moved into registration with one of the printing heads. After registration, the platen and textile article are brought into contact with a printing screen and a pattern is applied to the textile article by engaging the printing screen with an ink dispensing device after which the platen and textile article are separated from the printing screen.
If a design of more than one color is to be applied to the textile article, the platen and textile article may be moved into registration with another printing head, brought into contact with another printing screen supported thereby and printed by an ink dispensing device associated therewith. This process may continue to additional printing heads for additional colors, some of these automatic textile printers being designed with as many as twenty printing stations for application of ten colors. For a ten color machine, ten printing heads would be provided and the platen assembly would typically be provided with twelve platens, ten for registration with printing heads, one for mounting of an article to be printed and one for removing an article on which printing has been completed. Thus, an article such as a shirt may be placed on the first platen and printed at the first printing head while another shirt is being placed on the next platen. Of course, this process can continue so than ten shirts are being printed with different colors at the same time.
One of the problems in printing an article with several colors is allowing for the ink deposited at one printing station to dry 2 "or cure" prior to printing another color on the article. In some cases, this problem has been solved by placing a heating device at adjacent print heads so that after an article is printed at one print head it moves to the adjacent print head for drying and then a third print head for the application of another color. However, if a textile article is dried at alternate printing heads it cannot be printed with another color. Thus, the number of colors capable of being applied to the shirt would be reduced. For example, with a ten head automatic textile printer, in which every other head were provided with a drying device, only five colors could be applied. Solutions to these problems are needed. Furthermore, instead of purchasing a five or six color printer for $25,000 the operator may have to purchase a ten color printer for $50,000.
Many printing machines use a pivotable printing head. When the print head pivots upwardly away from the platen, heat is rapidly dissipated away from the printing screen. These pivoting head printing machines do not require shielding to protect the printing screen from heat. Unfortunately, such pivoting head printing machines require complex mechanisms to suitably pivot the printing head. These complex mechanisms can lead to a lack of printing accuracy, extra expense, and more repair. However, if the printing head does not pivot, then any application of heat can damage the printing screen. As such, a need has developed for the use of a non-pivoting head which can avoid the problems associated with the damage to the printing screen and the drying of the ink caused by the application of heat.


A turbine exhaust section comprises a turbine exhaust case having radially outer and inner ducts defining therebetween an annular exhaust portion for the hot exhaust gases, and an exhaust mixer projecting axially rearwardly from the turbine exhaust case for mixing the hot exhaust gases with a cooler bypass duct flow. The upstream end of the exhaust mixer surrounds a downstream end of the outer duct and defines therewith an axially extending overlap joint with a radial play between the outer duct and the exhaust mixer. A sliding attachment in the radial direction is provided between the outer duct and the exhaust mixer for accommodating differences in thermal growth during engine operation. The sliding attachment includes a circumferential array of sliding guides extending radially through the axially extending overlap joint. A resilient sealing ring seals the radial play between the outer duct and the exhaust mixer at the overlap joint.

In bypass-type gas turbine engines, high velocity, high temperature gases from the engine core is mixed with low velocity, low temperature air from the bypass duct before being exhausted from the engine. Exhaust mixers are often integrated to the exhaust section of the engine in order to increase the mixing of the high and low velocity fluid flows. Typically, the exhaust mixer and the turbine exhaust case are made from the same high-temperature resistant material and are welded together at a butt joint. For certain applications, it would be advantageous to have the ability to use a different material in the manufacturing of the exhaust mixer. For instance, that could contribute to reducing the overall weight of the engine.
Therefore, there is a need for a new gas turbine exhaust section.

Exhaust section for bypass gas turbine engines


A method for determining/dimensioning measures for restoring an electrical power system, which experiences or is heading for a voltage instability, to a steady-state condition, wherein there is no immediate risk of instability. An actual voltage/phase angle in the electrical power system is determined. The power unbalance within at least one sub-area in the electrical power system is determined. Suitable power-balancing measures are determined. The extent of the respective measures is determined. The power-balancing measures are carried out. Also, a device for carrying out the method.

It is already known to plan, dimension and design an electrical power system for normal as well as disturbed operation by using dimensioning criteria, set in advance, for various system quantities, such as operating voltage and mains frequency.
The voltage levels of the electrical power system at different network points or nodes constitute a measure of the condition of the electrical power system, that is, the ability of the system to continue to supply the loads of connected areas with the desired power. During normal operation, the operating voltage at a network point or a node is to lie within a pre-allowed interval, normally within a few percent of the stated nominal voltage. Examples of normally occurring nominal voltages are 400 kV, 130 kV and 50 kV. The construction, function, operation, automatic and protective equipment of an electrical power system are described, as far as Swedish conditions are concerned, in our Swedish patent SE 0101061-0 entitled "An electric power plant with means for damping power oscillations".
In case of disturbances in the electrical power system, preferably when the transmission capacity is weakened or decreasing, but also in the event of loss of electricity production plants or loss of other components with a voltage-controlling function, and combinations of these, the voltage distribution in the electrical power system is changed in such a way that the voltage level across the loads drops, which leads to a drop also of the voltage level in the transmission network. The corresponding phenomena may also arise in case of too fast a load increase.
Common in both cases is that the electrical power system is not capable, in the steady state, to supply the load connected to the network. Unless measures are taken, the different component-protective functions of the electrical power system, which are adapted to react on changes in voltages and/or currents, will successively disconnect components in the electrical power system. Normally, disconnection of transmission lines is the first thing that happens. Disconnection of components may occur over time, from a few seconds up to several hours.
A typical scenario is that the voltages at the measuring points of the impedance-measuring line protection device decrease and the currents increase, whereby the most sensitive measuring zone of the protection device disconnects the line in question. The remaining lines, in the network thus weakened, are then further loaded, whereby more transmission lines are disconnected. This proceeds until the remaining electrical power network is able to maintain a constant electricity operation and achieve a balance between production, transmission capacity and load.
Examples of events such as those mentioned above are the major power failures in the USA/Canada, Sweden and Italy in 2003. Scenarios such as those described above are, of course, desirable to avoid and there are a plurality of methods to detect incipient voltage instability in an electrical power system. In such systems, voltages and reactive power flows are measured, and devices for limiting the current on generators for detecting voltage instability have also been used, see, for example, Ingelsson, Karlsson, Lindström, Runvik, Sjödin: "Special Protection Scheme against Voltage Collapse in the South Part of the Swedish Grid", CIGRE Conference, Paris, 1996.
Still more advanced detectors, with or without possibilities of communication, have been presented and tested. One such example is the so-called VIP algorithm (Voltage Instability Predictor) described in Begovic, Milosevic, Novosel: "A Novel Method for Voltage Instability Protection", Proceedings of the 35th Hawaii International Conference on System Sciences, 2002. This system compares the impedance at a certain network point, in the direction of the load, with the impedance in a direction towards the production source. The relation between the load impedance, thus measured, and the source impedance may then be used as a measure for detecting incipient voltage instability.
One common method, which is efficient in this context, for mitigating or preventing voltage instability, after such instability has been detected, is to disconnect parts of the load in the network. By disconnecting a load corresponding to some ten percent of the total load in the inflicted area, the remaining load may often be adequately supplied. By intentionally and in a controlled manner disconnecting some load objects in a stressed operating situation, at least the operation of the major part of the inflicted area is saved, while at the same time the transmission network is kept energized and intact. The disconnected loads may be energized more rapidly again when stability has been resumed, for example by switching operations in the network and start-up of local electricity production.
By selecting and determining in advance what load objects are to be disconnected and in what sequence, a possibility is obtained of selecting objects such that the harmful effects in the system are limited. A frequency-controlled load disconnection for disconnection of load objects at too low or decreasing frequency is already available in most electrical power systems, that is, when the balance between actual electricity production and the desired consumption has been disrupted, for example in case of a major loss of production.
Other measures than load disconnection, such as the connection of shunt reactors and shunt capacitors, the connection of emergency power via dc links, etc., may also be used.
Existing non-connected electric power-generating objects cannot be connected to the transmission network if the line voltage is lower than a lowest value given in advance. For this reason, it may be necessary to disconnect part of the load such that reserve power plants may then be connected. These reserve power plants may then be used to increase the reactive generation and additionally increase the line voltage. In addition, they are to deliver active power and make it possible again to connect the previously disconnected load without the balance between production and consumption being lost.
With a view to designing a selective protection against voltage instability, based on the use of load disconnection, primarily three questions need to be answered in view of the prevailing operating situation:                1) When should the load disconnection take place?        2) Where should the load disconnection take place?        3) How much load should be disconnected?
The voltage level is normally a sufficiently good criterion for determining where the load disconnection should take place.
Disconnection may take place "without unnecessary delay", that is, as quickly as possible after a margin has been allowed for reserve disconnection of a shunt fault, that is, short circuits and ground contacts. The speed should also be adapted to the speed of the on-load tap changer control of the power transformers connected in the vicinity thereof. The time delay should normally be a few seconds.
However, the extent of the load disconnection is more difficult to determine. One method is to proceed by trial and error by disconnecting one or more loads, load areas, at a time. This is a relatively slow method since the system response to each disconnection must be awaited.
Another method is to use a comfortable margin and disconnect a larger number of loads. The disadvantage of such a method is that an unnecessarily large part of the load is disconnected and also that this involves a risk of obtaining high voltages in the electrical power system.
At present, there is no known method of dimensioning or determining the magnitude of a necessary load disconnection, when the need of such a measure has been detected. The fulfilled criteria normally result directly in load disconnection via a preselected circuit-breaker function with a suitable time delay, typically a few seconds.
U.S. Pat. No. 6,219,591, "Voltage instability predictor (VIP)—method and system for performing adaptive control to improve voltage stability in power systems", shows a method for detecting that the power system, or parts thereof, is/are heading for instability. However, the method only mentions the need of load disconnection in general, as a suitable measure for how this threatening instability is to be cancelled or mitigated.
The invention according to U.S. Pat. No. 6,242,719, "Applications and methods for voltage instability predictor (VIP)", is a further development of the invention according to U.S. Pat. No. 6,219,591, which, among other things, relates to masked transmission networks. However, none of these publications suggests any measure of magnitude of that quantity of load disconnection that is required for stabilizing the system.
Several patent specifications deal with the VIP algorithm, which suggest stability measures of various kinds and predict an imminent voltage collapse, but do not suggest the extent of or magnitude of the load disconnection that is necessary to prevent a power failure or a collapse in the electrical power network.

Method and a device for selecting and dimensioning measures in a case of instability in an electrical power system


A bicycle freewheel assembly is provided which is capable of being readily and reversibly switched from fixed-gear to freewheel operation, without the necessity of removing the wheel from the bicycle. The freewheel assembly is mountable on pre-existing freewheel hubs.

Almost all consumer-grade bicycles sold today are multi-speed bikes, in which a sprocket package, also referred to as a cogset, is connected via a freewheel mechanism to the rear wheel hub. A derailleur is used to move the drive chain from one sprocket to another, enabling the rider to select the gearing. Some bicycles employ gear hubs, wherein a planetary epicyclic gearset is contained within the hub. These usually feature a single sprocket, but a freewheel mechanism is still needed.
One design employs an assembly of a cogset and a drive ring, the assembly having built within it a ratchet mechanism. The cogset, drive ring, and internal ratchet are collectively referred to as a freewheel assembly, which in older designs is threaded onto a freewheel hub. More modern designs employ splines to couple the freewheel hub to the drive ring.
An alternative design employ a cassette, which is a bolted-together cluster of sprockets having no internal ratchet, and a "freehub" which contains the ratchet mechanism. A set of interior straight splines around the open axis of the cassette align with matching splines on the freehub axle, enabling the cassete to be rotationally locked to the freehub axle when mounted thereon. The freehub body and axle are in a freewheeling relationship.
There are two common ratchet mechanisms in use today. One design employs movable pawls distributed around (or within) the circumference of an internal ratchet. The pawls ride on the ratchet, sliding up the gently sloped side of each tooth when the ratchet and pawls are rotated in one relative direction, but rigidly engaging the other, steeply-sloped side of the ratchet teeth when the ratchet and pawls rotate in the opposite relative direction. The other design is the "star ratchet", in which two disks with spur or face gearing face each other and are biased against each other. The biasing force is provided by a spring, or in some cases by magnets. Relative rotation in one direction engages opposing, steeply-faced ratchet teeth, rotationally locking the disks together and enabling pedaling force to be transmitted from one disk (coupled to the sprocket or cogset) to the other (coupled to a drive ring or to the hub). Relative rotation in the opposite direction, as when the rider stops pedaling, results in opposed, sloped surfaces of the ratchet teeth sliding past one another. The resulting axial displacement of the disks against the biasing force results in decoupling and free relative rotation of the disks. Representative examples of the star ratchet may be found in U.S. Pat. Nos. 6,588,564, 7,562,755 and 8,757,341, the disclosures of which are incorporated herein by reference in their entireties.
Whether it is of the pawl-and-ratchet or star-ratchet design, the freewheel mechanism ensures that during a forward motion of the pedals the drive force, transmitted via the chain, is transmitted to the rear wheel, and that during a motion in the opposite direction, i.e., when the crank is moving backwards or is at a standstill, the sprocket or cogset is decoupled from the wheel, which therefore rotates freely.
In contrast to the above-described multi-speed bicycles with freewheel mechanisms, there is the simple fixed-gear bicycle, or "fixie", featuring a single sprocket rigidly attached to the wheel hub. The rider of a fixed-gear bicycle cannot stop pedaling while the bike is in motion, due to the absence of a freewheel mechanism between the pedal crank and the rear wheel, although some riders learn to brake by kicking back and locking the pedals and rear wheel, causing the bike to skid to a stop. The fixed-gear design, commonly found on track racing bicycles, has become popular with urban riders, particularly bicycle messengers, and a fixie sub-culture has emerged among riders in many U.S. and European cities. The fixed-gear bicycle has certain advantages, chiefly light weight, simplicity, and reliability, and the fixed connection between rider and wheel enables stunts that are difficult or impossible with a freewheel. A fixed-gear bicycle generally offers a low gearing ratio, which is well-suited to stop-and-go urban riding, although some riders prefer the high ratio of a track bicycle, which affords greater speed.
Riders of fixed-gear bicycles find that the design, while suited for short trips in a city, is not convenient for long rides or touring, where high gearing ratios are desirable for high speeds, and where the ability to coast on downhill runs conserves a rider's energy. High speed downhill runs are particularly problematic for the rider of a fixed-gear bike, because there is a limit to how fast the legs can be moved. Riders of freewheel, multispeed bicycles find that their machines are not suited for stunt riding, and that—because a derailleur cannot function when the bike is stopped—shifting gears in stop-and-go city riding can become a chore. In both cases, an expensive solution is to own two bicycles, one of each design, but this still requires that the rider select one bicycle or the other prior to setting out for the day.
A common solution to this problem is the "flip-flop hub", a rear bicycle hub that features a fixed cog on one side and a freewheel on the other. The rider can switch between freewheel and fixie modes by removing and flipping the rear wheel. While this is, in principle, a simple solution, the flip-flop hub has some disadvantages. Although long dropouts permit some variation, the gearing on the freewheel side of a flip-flop hub cannot much differ from the gearing on the fixed side, unless one also alters the chain length. Given that higher gearing is one of the principal reasons one would want to switch out of the fixed-gear mode, this is a major shortcoming. The need to not only remove the rear wheel, but to add or remove links from the chain, or to substitute a chain of different length, makes the switch between modes an inconvenient, messy operation if altered gearing is desired. Also, given the different axial dimensions of fixed sprockets and freewheel assemblies, dishing of the rear wheel may not be symmetrical, and the brakes may require re-alignment when the wheel is flipped. Brakes may also need re-positioning if a long dropout is relied on to enable altered gearing.
A complicated friction clutch mechanism, that reversibly fixes a freewheel hub via the engagement and disengagement of male and female conical surfaces, is described in U.S. Pat. No. 1,278,648 (issued to G. Henry in 1918.) The design, intended for a stationary exercise bike, suffers from weak frictional coupling of the surfaces, which cannot hold against the forces applied by a rider engaged in braking or in performing stunts.
A design for a hub in which pawls are reversibly engaged or disengaged from a ratchet to effect a switch between fixed-gear and freewheel modes is disclosed in U.S. patent application publication No. 2013/0299293 (Nov. 14, 2013). In this design, in order to switch modes, it is necessary to disassemble the hub, remove and relocate springs that bias the pawls into or out of engagement with the ratchet, and then re-assemble the hub. This is an inconvenient process for the user, and is impractical for use when on the road.
Further designs are disclosed in GB Patent Nos. 446,136 (to J. MacKay et al., 1936) and 451,299 (to W. Woodcock, 1936). In these designs, pawls are mechanically displaced to disengage them from their ratchets. These designs are mechanically complex, and cannot be retroactively installed on an existing hub assembly.
A more recent design for a hub in which pawls are reversibly engaged or disengaged from a ratchet to effect a switch between fixed-gear and freewheel modes is disclosed in U.S. Pat. No. 8,100,242 (to M. Schneider and K.-J. Kiihne, Jan. 24, 2012). A commercial embodiment of this design is marketed by SRAM Deutschland GmbH of Schweinfurt, Germany under the trade name "Torpedo Singlespeed". This hub weighs 480 g, which would be considered heavy by riders of track and fixie bicycles. The hub is switched between fixed and freewheel modes by driving an axial screw inwards or outwards, thereby sliding a set of pawl-blocking blades into or out of place between the pawls and the ratchet. This requires components specifically manufactured with and installed within the hub, and thus the device cannot be installed on an existing bicycle hub. A would-be user must purchase the entire specialized hub, and then build (or have built) a wheel around it. Furthermore, the construction of this custom wheel is limited to the number of spokes supported by the hub.
There remains a need for a bicycle that can be quickly, conveniently, and easily switched between freewheel and fixed-gear modes. There is a need for a device which provides positive engagement between the hub and sprocket, and which can be installed by bike shops or consumers on their current wheels and hubs.

Freewheel assembly switchable between fixed-gear and freewheel modes


An electrolytic method and apparatus for treating a solution sample allowing for the accurate and substantially real-time and on-line analysis of trace contaminants in the solution sample. The method of the present invention includes two stages. The solution sample is electrolyzed during a first stage to decompose the matrix, thereby substantially neutralizing the matrix, while during a second stage deposited or precipitated metals are recovered and/or stabilized in solution. An apparatus for carrying out the method is also disclosed.

1. Field of Invention
The present invention generally relates to analysis of solutions. More particularly, the present invention relates to online automated matrix elimination and trace contaminant analysis of process chemical solutions.
2. Discussion of the Related Art
Chemical solutions are used in various manufacturing processes in a multitude of industries, including the semiconductor, environmental, and pharmaceutical industries. A solution sample includes a matrix, defined herein as a liquid solution, suspension, or colloid, and may or may not include a detectable amount of at least one analyte of interest. Examples of matrixes are diluted or concentrated acids, bases, oxidants, reducing reagents, solvents (such as alcohols, esters, ethers, glycols, ketones, amides, amines, or their mixtures), cleaning solutions, photoresists, strippers, and developers. Examples of analytes of interest are metals and their species.
The matrix of a solution sample has a pronounced effect on the quantification of trace constituents by modern analytical instruments. For example, a common problem is detecting analytes of interest in a matrix including one or more compounds of high ionic strength. Many times, the desired analyte peaks or signals are obscured by the large interfering peak of a matrix ion. In many analytical instruments, the detector is saturated with matrix ion signals and is not able to distinguish the desired analyte signal.
In some cases, the desired signal is suppressed because the matrix ions compete with the desired analyte ions when ionization of the sample occurs for analysis purposes. For example, during ion formation in electrospray ionization, the matrix ions can solvate or deprotonate the analyte of interest resulting in less ion formation of the analyte of interest.
The composition or properties of a matrix may also change from process to process and during the life of the sample, which may then affect the recovery of an analyte from a complex matrix. Analyte speciation may further compound this effect. The stability of a sample/analyte may also change during analysis because of a changing thermal regime or photolytic effect. Thus, inaccurate analysis of a sample may occur because of the transitory nature of the matrix.
In many instances, however, accurately monitoring the analytes of a sample at a specific point in time during a process is highly desirable. For example, in semiconductor manufacturing processes, monitoring the metallic impurities in a cleaning solution is of immense importance for producing reliable devices with high yield. Purity of these solutions during offline and online processes is very important as well.
Reliably measuring the metallic contaminants in a cleaning solution at a parts-per-trillion level, especially in the presence of a high matrix, is not only complicated but also laborious and time consuming. For example, a solution of hydrochloric acid (HCl), hydrogen peroxide (H2O2), and water in varying ratio may be used to remove the metallic residues from the surface of a silica wafer by forming chloride complexes and dissolving in the solution. The solution is commonly known as a Standard Clean 2 solution (SC2). The most common ratio for SC2 used in semiconductor manufacturing is one part of 37% HCl to one part of 30% H2O2 to six parts of ultra pure water (UPW).
The continuous decrease in the geometry of devices requires increased control of the contaminants in a solution such as SC2. Control over the contaminants is important because SC2 comes in direct contact with the electronic circuitry during device fabrication. Thus, the quantitative determination of metallic contaminants in fresh and spent SC2 solution is of immense importance, for example in determining the cause of a defect or the endpoint of a process.
Due to the high matrix of chloride ions in SC2, the simultaneous online determination of trace levels of many metals is very difficult. In the absence of an analytical instrument that can monitor online all the contamination levels of metals in SC2, it is common practice to collect the SC2 sample before, during, and/or after a process of interest and to send the samples to an offline analytical laboratory for analysis. Typically, it takes between 4 to 24 hours before the analysis results are received by process personnel. Accordingly, in most cases, if a problem is detected, such as impurities in the SC2, processing of defective product will have occurred for some time and the cost related to low yield will be high.
Another problem with offline analysis is maintaining the integrity of the SC2 sample starting from collection to the end of analysis. First, SC2 cleaning is typically done at elevated temperatures, between about 60° C. to about 75° C., and at this temperature the matrix of SC2 is dynamic in nature such that the components of the SC2 are continually reacting with other components and can change over time. Thus, by the time the sample reaches a laboratory for analysis, the sample may not be in a representative formulation as it was at the time of collection. Second, the SC2 matrix is a strong absorption media for airborne soluble contaminants such that if samples are exposed to air at any stage during sampling, transportation, or analysis, the matrix of the sample may be altered or contaminated. Third, the cleanliness of the sampling containers is important and a large amount of time and money is spent on cleaning sampling containers. The amount of time the sample is allowed to sit in the sampling container before being analyzed can also affect the analysis outcome. It has been reported that even the cleanest of sampling containers can leach out many undesirable contaminants. Fourth, offline elimination, neutralization, or modification of matrixes generally poses a high risk of contamination that can affect the integrity of the sample for the reasons stated above.
Depending on the nature and concentration of the SC2 matrix, various analytical laboratories have developed their own methods to test a sample including an SC2 matrix. For example, some laboratories dilute the sample to reduce the effect of the matrix but by doing so many ultra low trace level contaminants may not be detected. Other laboratories eliminate the matrix by heat and/or evaporation but by doing so potentially lose the integrity of the sample constituents.
As a result, many semiconductor device manufacturers are in need of online measurements to provide substantially real-time analysis. Therefore, a method and apparatus for accurate online elemental and molecular analysis of process solutions, such as SC2, on a substantially real-time basis are highly desirable.

Electrolytic method and apparatus for trace metal analysis


An exhaust-gas temperature raising system, installed in an in-cylinder injection type internal combustion engine adapted to spark-ignite fuel injected from a fuel injection valve directly into a combustion chamber, includes an electronic control unit which controls the fuel injection valve to inject the fuel, at a delayed fuel-injection timing in a compression stroke of the engine, in such an amount as to form an overrich air-fuel mixture locally around an ignition plug together with air in the combustion chamber, when the engine is in an operating condition in which an exhaust-gas temperature is required to rise. The electronic control unit controls an engine control parameter so that the fuel injected at the delayed fuel-injection timing and spark-ignited is insufficiently combusted around the ignition plug, and is then mixed with extra oxygen in the combustion chamber so as to be combusted while being affected by a gas flow in the combustion chamber, whereby the exhaust-gas temperature is effectively raised while suppressing the fuel consumption rate to a minimum.

1. Technical Field of the Invention
The present invention relates to an in-cylinder injection type internal combustion engine adapted to inject fuel directly into a combustion chamber and to cause the injected fuel to be spark-ignited for stratified combustion, and more particularly, to a system for raising the exhaust-gas temperature to thereby enable immediate activation of an exhaust-gas purification device of an in-cylinder injection type internal combustion engine when the engine continuously effects a lean combustion operation.
2. Description of the Related Art
For spark-ignition type automotive internal combustion engines, various in-cylinder injection type gasoline engines have been proposed. These types of engines inject fuel directly into a combustion chamber, unlike conventional intake-manifold injection type engines, in which fuel is injected into an intake manifold and transferred to a combustion chamber. An in-cylinder injection type engine is typically arranged to inject fuel from a fuel injection valve into a cavity formed in the top of a piston of the engine, to locally generate an air-fuel mixture having an air-fuel ratio close to the stoichiometric air-fuel ratio around an ignition plug at ignition timing. This enables a proper combustion of a lean air-fuel mixture, whose average air-fuel ratio observed in the entirety of the combustion chamber is lean, reduce the emission of harmful exhaust-gas components, and improve fuel consumption. However, if the engine performs such a lean-combustion operation through the entire operating region, a deficient engine output may occur in some operating condition. To obviate this, the in-cylinder injection type engine is arranged to switch the injection mode between a compression-stroke injection mode and an intake-stroke injection mode depending upon engine operating conditions.
When the engine is in a low-load operating region, the compression-stroke injection mode is selected, in which fuel is injected mainly during compression stroke. In this mode, most of the fuel, injected toward the cavity of the piston during compression stroke, stays in the cavity because of the action of a tumble flow of intake air sucked into the combustion chamber during intake stroke. Therefore, even if such a small amount of fuel, as to make the average air-fuel ratio large, is injected (compression-lean mode), an air-fuel mixture having an air-fuel ratio close to the stoichiometric air-fuel ratio is formed in the cavity around a spark plug, at ignition timing, at which the piston approaches the spark plug. Hence, the, inflammation of the air-fuel mixture by a spark may become possible. This permits a large amount of intake air to be supplied into the cylinder in the compression-stroke injection mode, so that pumping loss is decreased and fuel consumption is greatly improved.
When the engine is in a medium- or high-load operating region, fuel is injected mainly during intake stroke, so as to form a mixture with a uniform air-fuel ratio in the combustion chamber. In this case, a large amount of fuel can be burnt without causing any misfire due to the presence of an overrich mixture around the spark plug, whereby the engine output required at the time of acceleration or during high speed running of a vehicle can be ensured.
At the time of cold start of engine, or during a low-load engine operation at a low ambient air temperature, an in-cylinder injection type internal combustion engine may take much time to activate a catalyst of an exhaust-gas purification device disposed in the exhaust passage of the engine. When the engine is operated in the compression-lean mode where a large amount of intake air is supplied into a cylinder, the flow rate of exhaust gas is high, and hence the exhaust-gas temperature tends to become low. Accordingly, the catalyst may fail to maintain its activated temperature, when the engine is operated in the compression-lean mode even if the catalyst has once reached the activation temperature. To eliminate these problems, various methods are proposed for raising the exhaust-gas temperature to effect a rapid activation of catalyst.
For example, an in-cylinder injection type internal combustion engine proposed in JP-A-4-183922 operates a fuel injection valve during compression stroke of the engine to inject a main fuel into a combustion chamber, and actuates a spark plug to ignite the main fuel. Then, the fuel injection valve is operated again during expansion stroke or during an early stage of exhaust stroke in which the intake valve is kept closed, to thereby inject an additional fuel into the combustion chamber, and the spark plug is actuated again to ignite the additional fuel. However, the proposed system requires a complicated ignition-control logic and cannot produce sufficient energy for the second ignition.
In this regard, JP-A-8-100638 proposes a method for permitting an additional fuel to be burnt without utilizing spark ignition. In the proposed method, a main fuel is injected during compression stroke of an engine, a spark plug is actuated to ignite the main fuel, and an additional fuel is injected during expansion stroke. A flame produced by the inflammation of the main fuel initiated upon spark-operation of the spark plug propagates to the additional fuel and causes the same to be burnt. By this method, the additional fuel can be burnt without the need of re-actuating the spark plug, and the combustion of the additional fuel raises the exhaust-gas temperature, to thereby shorten a time required for activation of the catalyst.
However, according to the proposed method, the additional fuel must be injected during that time period in which the additional fuel can be enflamed by the flame which propagates during the main combustion. Actually, in the proposed method, the injection timing of the additional fuel is set to a value ranging from, e.g., 10.degree. to 80.degree. ATDC in terms of crank angle. However, if the additional fuel is injected during an early stage of expansion stroke like this, part of the thermal energy produced at the time of combustion of the additional fuel is wasted for the work of expansion, so that an intended rise of the exhaust-gas temperature may not be sufficiently achieved. Furthermore, an amount of additional fuel must be increased in order to sufficiently raise the exhaust-gas temperature, causing the fuel consumption to be further worsened.

Exhaust-gas temperature raising system for an in-cylinder injection type internal combustion engine

Mitsubishi Jidosha Kogyo Kabushiki Kaisha