A rotary valve of a hydraulic power steering gear includes an input-shaft journalled within a sleeve. In the bore of the sleeve, an array of eight axially extending blind-ended slots and an array of two primary and two secondary axially extending return channels are formed. The primary return channels are diametrically opposed, and the secondary return channels are diametrically opposed. The return channels extend to at least one axial extremity of the bore to communicate hydraulic fluid to a return port. Further, the radial depth of the secondary return channels is substantially less than the radial depth of the primary return channels at or near the axial extremity.

Such rotary valves typically include an input-shaft which incorporates in its outer periphery a plurality of blind-ended, axially extending grooves separated by lands. Journalled on the input-shaft is a sleeve having in its bore an array of axially extending blind-ended slots circumferentially aligned with the lands on the input-shaft. The interfaces between the coacting input-shaft grooves and sleeve slots define axially extending orifices which open and close when relative rotation occurs between the input-shaft and the sleeve. The sides of the input-shaft grooves are contoured so as to provide a specific orifice configuration and are referred to as metering edge contours. These orifices are ported as a network such that they form sets of hydraulic Wheatstone bridges which act in parallel. Such hydraulic Wheatstone bridges are analogous in operation to conventional electrical Wheatstone bridges.
Drilled passages in the input-shaft and sleeve, together with circumferential grooves in the periphery of the sleeve, serve to communicate oil between the grooves in the input-shaft and the slots in the sleeve, a hydraulic pump, and right-hand and left-hand hydraulic assist cylinder chambers incorporated in the steering gear.
A torsion bar incorporated in the input-shaft serves to urge the input-shaft and sleeve towards a neutral, centred position when no power assistance is required. When input torque is applied by the driver to the steering wheel, the torsion bar deflects, causing relative rotation of the sleeve and input-shaft from the neutral position. This so called "valve operating angle" imbalances the sets of hydraulic Wheatstone bridges and hence causes a differential pressure to be developed between the right-hand and left-hand cylinder chambers. The "boost characteristic" of the rotary valve, that is the functional relationship between the above mentioned input torque and differential pressure, is largely determined for a given steering gear application by the geometry of the metering edge contours.
Traditionally the networl(of orifices in a rotary valve employ 2, 3 or 4 Wheatstone bridges, necessitating respectively 4, 6 or 8 input-shaft grooves and sleeve slots. Each Wheatstone bridge comprises a right-hand and a left-hand oil flow path, henceforth termed "limbs", and each right-hand and left-hand limb in turn comprises upper and lower portions. The upper and lower portions of each right-hand and left-hand limb meet respectively at a point of connection to the right-hand and left-hand cylinder chamber, henceforth termed the right-hand and left-hand "cylinder ports" of the valve.
In the neutral position of the rotary valve, oil from the hydraulic pump divides and enters each Wheatstone bridge at the valve "inlet port". At this point flow further divides and enters the upper right-hand and left-hand limbs, each containing an "inlet orifice". After being metered through such inlet orifices, oil is communicated to the respective cylinder ports and to the respective interconnection to the lower limbs. Depending on the intercylinder flow rate drawn by the motion of the piston in the cylinder chamber, oil continues to flow through the tower right-hand and left-hand limbs, metering through a "return orifice" in each limb, and recombining immediately upstream of the "return port" of the rotary valve.
The networl of two inlet orifices and two return orifices, constituting each Wheatstone bridge, is ported in the rotary valve such that, for a given relative angular displacement of the input-shaft and sleeve from their neutral position, mutually opposite orifices on each Wheatstone bridge simultaneously close or open. For example, the left-hand inlet and right-hand return orifices both close (ie. increase in restriction to oil flow) while the right-hand inlet and left-hand return orifices both open (ie. decrease in restriction to oil flow). According to classical Wheatstone bridge theory, for a given oil flow through each Wheatstone bridge, a differential pressure is therefore developed between the right-hand and left-hand cylinder ports, providing the necessary level of power assistance for each value of valve operating angle.
The general method of operation of such traditional rotary valves is well known in the prior art of power steering design and described in greater detail in U.S. Pat. No. 3,022,772 (Zeigler et al), commonly held as being the "original" patent describing the rotary valve concept. Rotary valves of this format will henceforth be termed "direct mode valves" since all Wheatstone bridges within the valve incorporate direct hydraulic communication to the cylinder ports.
Rotary valves are nowadays regularly incorporated in firewall-mounted rack and pinion steering gears, and in this situation, any noises such as hiss emanating from the valve are very apparent to the driver. Hiss results from cavitation of the hydraulic oil as it flows in the orifices defined by the metering edge contours and the adjacent edges of the sleeve slots, particularly during times of high pressure operation of the valve such as during parking, where differential pressures of 8-10 MPa or more can be generated. It is well known in the art of power steering valves that an orifice is less prone to cavitation if the associated metering edge contour has a high aspect ratio of axial length to radial depth, thereby constraining the oil to flow as a thin sheet of constant depth along the full axial extent of one metering edge contour and if, furthermore, the flow of oil is evenly divided amongst several metering edge contours ported to act in parallel, so further effectively reducing the flow of oil that may flow through any one orifice. It is also well known that cavitation is less likely to occur if the metering edge contour, where it intersects the outside diameter of the input-shaft, is nearly tangential thereto, hence constituting a shallow chamfer typically inclined at an angle of between 4 deg and 8 deg.
Such shallow chamfers have been widely used in rotary valves for noise suppression over the last 20 years. In order to achieve the necessary depth and form accuracy, these chamfers are normally ground in special indexable or cam- type grinding machines resulting in long overall cycle times, relatively expensive capital equipment, and hence high overall manufacturing cost.
Another requirement which is increasingly becoming accepted for the design of rotary valves is the need for a linear boost characteristic. During vehicle cornering, it is advantageous that a substantially linear relationship exists between the driver's input torque and the differential pressure associated with such a cornering manoeuvre. This leads to the sensation of "progression" in the power assistance and maximises steering feel in such critical situations. Associated with the requirement for a linear boost characteristic, it is also highly desirable to maximise the extent of the linear region before the maximum parking torque (and hence parking pressure) is reached. This necessitates a fast transition or "turn-around" of the linear boost characteristic to a region of much steeper slope associated with the higher differential pressures used for parking. For a given slope and extent of the linear boost characteristic of the rotary valve during cornering, the torque required to be exerted by the driver during parking is therefore minimised.
Chamfer type metering edge contours can, to some limited degree, generate a low noise linear boost characteristic if the chamfer is designed as a scroll, as disclosed in U.S. Pat. No. 5,267,588 (Bishop et al), or as a series of flat facets, as disclosed in U.S. Pat. No. 4,460,016 (Haga et al). However, in both these cases, the extent of the linear boost region is relatively short and the transition to the steeper parking region of the boost characteristic is prolonged, and therefore not optimal in terms of minimising parking torque.
Another technique, well known in the art, for suppressing valve noise in power steering valves is the application of back pressure to an otherwise cavitating orifice, thereby raising pressures within the orifice above the vapour pressure of the hydraulic oil and hence preventing the onset of cavitation. Chamfer style metering edge contours need not necessarily be used on the input-shaft if this alternative method of noise suppression is employed. Much steeper and axially shorter metering edge contours can in fact be used, contours which would otherwise be excessively noisy in the absence of such back pressure. Such steeper and generally more complex shaped metering edge contours can be manufactured by coining, roll-imprinting or traditional hobbing methods and, if appropriately designed, can generate the previously described desirable linear boost characteristic with a fast turn-around. U.S. Pat. No. 4,335,749 (Walter) shows a direct mode valve incorporating an extra (second) orifice in the lower portions of the left-hand and right-hand limbs of each bridge. This orifice progressively closes with increasing valve operating angle until a constant orifice area is reached which, based on the flow through the limb, applies a predetermined back pressure to the closing upstream inlet orifice. Such a valve format is based on 6 orifices per bridge and, if 3 bridges are employed in the valve, requires 9 input-shaft grooves and 9 sleeve slots. If 4 bridges are employed (as in the case of a traditional 8 groove/slot rotary valve), 12 input-shaft grooves and 12 sleeve slots are required. This format is therefore non-standard and requires extra manufacturing cost.
Further however, experiments have shown that elimination of cavitation noise in an orifice generating 10 MPa (say) differential pressure requires a downstream back pressure to be applied which is as much as 1 MPa or more . If such high levels of back pressure were generated by the return orifices according to the methodology disclosed in U.S. Pat. No. 4,335,749 (Walter), this back pressure would raise the inlet pressure required to be supplied by the hydraulic pump by the same 1 MPa, without any of this additional pressure being applied differentially at the cylinder chamber. This is because this direct mode valve arrangement contains cylinder port connections in every bridge and the return orifice used for back pressure generation is downstream of such connections. The 1 MPa increase in valve inlet pressure would be totally wasted in terms of generating power assistance force and would simply raise the operating pressure of the hydraulic pump. The latter situation is highly undesirable since energy loss in the hydraulic system is proportionally increased. Also pump noise, leakage and potential hydraulic line failure all become bigger problems as the pump relief valve setting is necessarily increased to accommodate the increased valve operating pressure, for example from 10 MPa to 11 MPa in this case.
For this reason the practical level of back pressure that can be applied by the return orifice according to the above prior art invention is limited to about 300-400 kPa, well short of the 1 MPa or more needed to substantially eliminate cavitation noise through the operating pressure range of the power steering valve.
Another class of rotary valve, henceforth termed "bypass mode valves", is quite distinct from the class of direct mode valves earlier described. Bypass mode valves also utilise parallel arrangements of Wheatstone bridges, however not all bridges in this case contain a hydraulic connection to a cylinder port between the inlet and return orifices. The bridges which employ a cylinder connection will henceforth be termed "primary bridges" and those which don't employ a cylinder connection termed "secondary bridges". In the latter case the left-hand and right-hand limbs contain one or more inlet and return orifices but with no interposed cylinder port connection. In this manner, for certain valve operating angles, hydraulic oil at least partially by-passes the primary bridge(s) which incorporate the connection to the cylinder.
Such bypass mode valves were first put forward for speed sensitive power steering applications. For example, arrangements described in U.S. Pat. Nos. 4,570,735 (Duffy) and 4,570,736 (Waldorf) and Japanese Patent 04-031175 (Suzuki et al) involve a bypass mode valve with an electronically modulated variable orifice residing in the inlet to the secondary bridges and modulated as a function of vehicle speed. Other later arrangements such as shown in Japanese Patent 02-306878 (Suzuki) and U.S. Pat. No. 5,092,418 (Suzuki et al) use an electronically modulated variable orifice residing in the return line from the secondary bridges. In such speed sensitive applications, the degree of bypass of hydraulic oil through the secondary bridges is used to control the boost characteristic as a function of vehicle speed.
Bypass mode valves have also been utilised in a non-speed sensitive format to improve the linearity and produce a fast turn-around of the boost characteristic for valves employing chamfered metering edge contours. For example Japanese Patents 04-031176, 05-042880 and 06-278623 (all Suzuki et al) and U.S. Pat. No. 4,470,432 (Kervagoret) show orifice networks very similar to the abovementioned speed sensitive applications except that the electronically modulated variable orifice is now a fixed "drill-hole" style orifice either upstream or downstream of the secondary bridges. In situations where relatively conventional metering edges are used in the orifices of the secondary bridges, such arrangements will tend to be noisy for two reasons. Firstly the very low aspect ratio of the fixed orifices (ie. unity for a drill hole will be a source of cavitation for the relatively high oil flows involved. Secondly in these arrangements, for high valve operating pressures, all pump flow is communicated to the return port via only two stages of pressure drop: the restrictions offered by relevant closing secondary orifice and the fixed orifice (or vice versa).
U.S. Pat. No. 4,577,660 (Haga) shows an 8 slot by-pass valve again intended to produce a linear boost characteristic with a fast turn around. In this case the secondary inlet orifices are overlapped and in fact closed on-centre, their sudden opening off-centre intended to produce the required discontinuity in the boost characteristic. However such an arrangement, with a substantial portion of the valve closed on-centre, would naturally exhibit higher than usual back pressure on-centre and would therefore be energy inefficient.
Japanese Patent 04-292265 (Suzuki et al) shows a relatively complex by-pass mode valve employing 10 input-shaft grooves and corresponding 10 sleeve slots. An extra orifice is positioned in the lower portion of each secondary bridge limb and, as it closes, provides a similar flow redistribution function to the earlier mentioned fixed orifice. Such a valve arrangement is expensive because of the larger quantity of input-shaft grooves and sleeve slots, and the associated interconnecting porting (eg. drill holes) to hydraulically communicate such slots/grooves. Moreover 10 input-shaft grooves and 10 sleeve slots are difficult to package using a standard input-shaft outside diameter (or corresponding sleeve inside diameter), typically in the range 19.0-22.5 mm, and yet still retain sufficient inter and intra slot/groove spacing to accommodate such interconnecting porting.
However the nature of the diversion of oil flow in bypass mode valves between the primary and secondary bridges means that, when such valves generate a large differential pressure at the cylinder, essentially only the secondary bridges transmit any oil flow. This means that the individual orifices in the secondary bridges tend to be prone to cavitation noise even if shallow chamfers are employed as the metering edge contours according to the prior art. Japanese Patent 05-310136 (Suzuki et al) proposes to reduce this problem by employing an electronically modulated variable orifice positioned at the return port of a bypass mode valve, this variable orifice controlled to produce a restriction (and hence generate back pressure) as a function of the sensed inlet pressure to the valve. For reasons earlier described, such an arrangement is energy inefficient and, moreover in this case, adds significant cost to the power steering system.
Nevertheless, bypass mode valves do offer a major advantage over direct mode valves in that, any back pressure applied within the secondary bridge network to suppress cavitation noise generated by the respective orifices does not raise the overall inlet pressure to the valve, as supplied by the hydraulic pump, for a given differential pressure applied at the cylinder. Hence such back pressure is not wasteful in terms of energy and in fact is usefully used to generate some portion of the power assistance at the cylinder. There is therefore no need to use higher pump relief valve settings and the previously referred to large levels of back pressure (eg. 1 MPa) can be theoretically utilised to substantially eliminate cavitation noise without any major disadvantage in terms of valve function.
The first and second aspects of the present invention are directed at utilising the above mentioned benefits of bypass mode valves, and yet provide low levels of cavitation noise in a rotary valve without necessarily increasing the number of input-shaft grooves or sleeve slots. Another aim is to permit such low levels of cavitation noise to be achieved using metering edge contours of the more steeply sloping variety earlier referred to. Such metering edge contours can be produced by coining, roll-imprinting or hobbing and not only offer significant cost savings compared to shallow chamfers which generally must be ground, but also enable much more flexibility in the design of the boost characteristic, particularly the provision of a linear boost characteristic with a fast turn-around. Also such steeply sloping metering edge contours can generally be designed to be axially shorter than the comparable shallow chamfer, enabling the overall rotary valve package to be likewise shortened.
The first aspect of the present invention consists in a rotary valve for a hydraulic power steering gear comprising a valve housing having an inlet port to receive hydraulic fluid from a pump, a return port to return hydraulic fluid to the pump, and cylinder ports to communicate hydraulic fluid to left and right-hand cylinder chambers of the power steering gear, the valve also comprising an input-shaft having in its outer periphery a plurality of axially extending grooves separated by lands, a sleeve journalled on said input-shaft, said sleeve having in its bore an array of axially extending slots circumferentially aligned with the lands on the input-shaft, the interfaces between the coacting input-shaft grooves and sleeve slots defining axially extending orifices controlling fluid flow within the valve, the orifices opening and closing when relative rotation occurs between the input-shaft and sleeve from a neutral position, the orifices being ported as a network such that they form one or more primary and one or more secondary hydraulic Wheatstone bridges arranged in parallel, each said bridge comprising two limbs hydraulically communicating the inlet and return ports, each said limb containing an inlet orifice hydraulically communicating to the inlet port and a return orifice hydraulically communicating to the return port, the magnitude of the hydraulic flow through each bridge varying in accordance with the restriction offered by the respective inlet and return orifices in that bridge, the limbs of the primary bridge incorporating means providing hydraulic communication to one of the cylinder ports at a point of interconnection of the respective inlet and return orifices in that limb, the limbs of the secondary bridge not incorporating means providing hydraulic communication to the cylinder ports, characterised in that the return orifice in each limb of said secondary bridge is formed by a metering edge contour on the edge of the secondary return groove associated with said return orifice, said metering edge contour circumferentially overlapping the adjacent sleeve bore land when the rotary valve is in its neutral position to such an extent that said return orifice provides a restriction to hydraulic flow as the upstream inlet orifice in the same limb closes for all valve operating angles from said neutral position, said return orifice applying a back pressure to said upstream inlet orifice, said back pressure being sufficient to significantly suppress the generation of cavitation noise in said inlet orifice.
It is preferred that a substantially constant restriction area is provided by said return orifice as the upstream inlet orifice in the same limb closes for all valve operating angles from said neutral position.
It is preferred that the input-shaft metering edge contour employed in said return orifice is formed in cross-section such that a region of locally reduced metering edge depth lies in the overlapped region of the coacting input-shaft metering edge contour and adjacent sleeve bore land, that is in the region lying radially inside the adjacent sleeve land. Said substantially constant restriction area provided by said return orifice can be considered as constituting a hydraulic throat which serves to significantly suppress cavitation noise or turbulence as the hydraulic oil flows past the adjacent sleeve edge and enters this return orifice.
It is preferred that cavitation and other flow noise can be further reduced by raising the back pressure downstream of the secondary return orifice.
It is preferred that hydraulic flow from the primary bridge is hydraulically communicated to the return port via a primary return path and the hydraulic flow from the secondary bridge is hydraulically communicated to the return port via a secondary return path, a restriction existing in the secondary return path.
In first and second embodiments it is preferred that the secondary return path passes through the bore of the input-shaft.
In a first embodiment it is preferred that the radial holes which hydraulically communicate the secondary return groove to the input-shaft bore are reduced in diameter, thereby generating back pressure in the secondary return groove downstream of the secondary return orifice.
The capability of these radial holes to apply such back pressure without themselves causing a noise problem can be further enhanced if conical or tapered entries are employed on these holes. This can be readily and cheaply achieved via a step form on the drill used to machine these holes or by laser erosion.
In the case of this first embodiment, it is also preferred that the primary return path also passes through the bore of the input-shaft. However the radial holes which hydraulically communicate the primary return grooves to the input-shaft bore are sufficiently large in diameter in this case that no substantial restriction is generated.
In a second embodiment, and also in a later referred to fifth embodiment, the restriction existing in the secondary return path is preferably annular in geometry. It is preferred that this annular restriction has a cross-section to flow which has a high aspect ratio, in order to suppress its generation of cavitation noise. In this second embodiment it is preferred that only the secondary return path passes through the bore of the input-shaft. Oil entering the input-shaft bore via the aforementioned radial holes is restricted using a diametrically enlarged portion on the torsion bar. This enlarged portion is arranged to have a small radial clearance with respect to the input-shaft bore, hence creating an annular restriction for hydraulic oil as it flows axially in this bore towards the return port of the valve housing.
According to this embodiment, hydraulic oil from the primary bridge is ported directly to the return port so that it is not required to flow through the input-shaft bore, and hence is not subject to this additional restriction. This is achieved by axially extending the input-shaft grooves associated with the primary return orifices in the form of channels, allowing hydraulic oil flow in the primary bridge to exit directly axially from these grooves through these channels.
The diametrically enlarged portion of the torsion bar can be integrally machined as part of the torsion bar during its manufacture. However, in order to maximise the working length of the reduced diameter portion of the torsion bar, and hence lower the maximum stress endured by the torsion bar for a given working diameter and torsional spring rate, the diametrically enlarged portion on the torsion bar is preferably formed as an annular bush which is plastic moulded around the metallic portion of the torsion bar as a separate subsequent operation. The plastic material must be chemically resistant to hydraulic oil and is preferably an engineering plastic such as Delrin.RTM. or Lurathane.RTM..
If the annular bush is made to additionally extend axially such that it overlaps the secondary return radial holes in the input-shaft, the use of such compliant plastic material for this bush has been found to assist dampening the hydraulic turbulence noise generated by the secondary return oil as it flows radially into the input-shaft bore and thence necessarily turns perpendicularly to continue flowing axially down this bore.
In a third embodiment it is preferred that the secondary return path does not pass through the bore of the input-shaft. Axially extending secondary return channels are formed in the sleeve bore which are circumferentially aligned with the secondary return grooves. The channels extend to the axial extremity of the sleeve bore and arranged to communicate hydraulic fluid to the return port. The radial depth of the channels is small, thereby interacting with the adjacent outside diameter of the input-shaft to form a high aspect ratio restriction in the secondary return path downstream of the secondary return grooves. It is preferred that at least one secondary return channel extends to both axial extremities of the sleeve bore.
It is also preferred that axially extending primary return channels are formed in the sleeve bore and arranged to be circumferentially aligned with the primary return grooves. These additional channels also extend to the axial extremity of the sleeve bore and are arranged to communicate hydraulic fluid to the return port. It is preferred that the radial depth of the primary return channels is larger than that of the aforementioned shallow secondary return channels since no restriction is required to be generated in the primary return path. It is also preferred that at least one of the primary return channels extends to both axial extremities of the sleeve bore.
For reasons of ease of manufacture, it is preferred that all primary and secondary return channels extend to both axial extremities of the sleeve bore, enabling all such channels to be formed with a single multi-tooth broaching tool.
In a fourth embodiment it is also preferred that the secondary return path does not pass through the bore of the input-shaft. The secondary return grooves are axially extended as shallow, high aspect ratio channels formed via their interaction with the adjacent sleeve bore. These channels extend to the axial extremity of the sleeve bore, thereby providing a restriction in the secondary return path. It is also preferred that the primary return grooves are similarly axially extended as radially deeper channels to facilitate a relatively unrestricted primary return path.
In a fifth embodiment is is also preferred that the secondary return path does not pass through the bore of the input-shaft. The secondary return grooves are axially extended in at least one direction to communicate with an annular cavity formed by the interaction of a reduced diameter portion of the input-shaft outer periphery and the sleeve bore. The annular cavity acts as a manifold to gather secondary return oil flow, which is then communicated via an annular restriction to the return port. The annular restriction is preferably generated by a predetermined small radial clearance existing between the above mentioned reduced diameter portion of the input-shaft and the inside diameter of a radially inwardly extending portion of the sleeve bore. Preferably the radially inwardly extending portion of the sleeve bore is formed as an accurately internally and externally sized annular pressed-metal cup which is press-fitted inside the sleeve skirt to seal against the axial extremity of the sleeve bore. Preferably the predetermined radial clearance is such that the resulting annular restriction has a high aspect ratio in order to suppress its generation of cavitation noise. It is also preferred that the primary return path passes through the bore of the input-shaft in a similar manner to that described in reference to the first embodiment, thereby bypassing the annular restriction en-route to the return port.
It is preferred that the rotary valve has eight input-shaft grooves.
It is preferred that the rotary valve has eight sleeve slots.
The second aspect of the present invention consists in a rotary valve for a hydraulic power steering gear comprising a valve housing having an inlet port to receive hydraulic fluid from a pump, a return port to return hydraulic fluid to the pump, and cylinder ports to communicate hydraulic fluid to left and right-hand cylinder chambers of the power steering gear, the valve also comprising an input-shaft having in its outer periphery a plurality of axially extending grooves separated by lands, a sleeve journalled on said input-shaft and rotationally secured to a driven member, said sleeve having in its bore an array of axially extending slots circumferentially aligned with the lands on the input-shaft, the interfaces between the coacting input-shaft grooves and sleeve slots defining axially extending orifices controlling fluid flow within the valve, the orifices opening and closing when relative rotation occurs between the input-shaft and sleeve from a neutral position, a torsion bar residing in a bore of the input-shaft compliantly connecting the input-shaft and driven member, and arranged to urge the sleeve and input-shaft to the neutral position, the orifices being ported as a network such that they form one or more primary and one or more secondary hydraulic Wheatstone bridges arranged in parallel, each said bridge comprising two limbs hydraulically communicating the inlet and return ports, each said limb containing an inlet orifice hydraulically communicating to the inlet port and a return orifice hydraulically communicating to the return port, the magnitude of the hydraulic flow through each bridge varying in accordance with the restriction offered by the respective inlet and return orifices in that bridge, the limbs of the primary bridge incorporating means providing hydraulic communication to one of the cylinder ports at a point of interconnection of the respective inlet and return orifices in that limb, the limbs of the secondary bridge not incorporating means providing hydraulic communication to the cylinder ports, characterised in that hydraulic flow from said primary bridge is hydraulically communicated to the return port via a primary return path and the hydraulic flow from the secondary bridge is hydraulically communicated to the return port via a secondary return path, an annular restriction existing in the secondary return path.
It is preferred that the annular restriction existing in the secondary return path has a cross-section to flow which has a high aspect ratio.
It is preferred that the aspect ratio be greater than 10.
It is preferred that one but not both of the primary or secondary return paths passes through the bore of the input-shaft.
In a first embodiment it is preferred that the secondary return path passes through the bore of the input-shaft and the annular restriction is formed within this bore.
It is preferred that the annular restriction formed in the bore of the input-shaft is generated by virtue of a small radial clearance existing between a diametrically enlarged portion of the torsion bar and the input-shaft bore.
It is preferred that hydraulic flow from the primary bridge is directly communicated to the return port via channels formed as an axial extension of the input-shaft grooves associated with the primary return orifices. Because this hydraulic flow is not communicated through the input-shaft bore, it is not subject to the abovementioned annular restriction.
Various preferred embodiments are possible for the geometry and construction of the diametrically enlarged portion of the torsion bar and have already been described in reference to the first aspect of the present invention.
In a second embodiment is is preferred that the secondary return path does not pass through the bore of the input-shaft and the annular restriction is formed at the input-shaft/sleeve interface. The secondary return grooves are axially extended in at least one direction to communicate with an annular cavity formed by the interaction of a reduced-diameter portion of the input-shaft outer periphery and the sleeve bore. The annular cavity acts as a manifold to gather secondary return oil flow, which is then communicated via an annular restriction to the return port. The annular restriction is preferably generated by a predetermined small radial clearance existing between the above mentioned reduced diameter portion of the input-shaft and the inside diameter of a radially inwardly extending portion of the sleeve bore. Preferably the radially inwardly extending portion of the sleeve bore is formed as an accurately internally and externally sized annular pressed metal cup which press-fitted inside the sleeve skirt to seal against the axial extremity of the sleeve bore. Preferably the predetermined radial clearance is such that the resulting annular restriction has a high aspect ratio in order to suppress its generation of cavitation noise. It is also preferred that the primary return path passes through the bore of the input-shaft in a similar manner to that described in reference to the first embodiment of the first aspect of the present invention, thereby bypassing the annular restriction en-route to the return port.
In the case of both first and second embodiments of the second aspect of the present invention, hydraulic flow from the secondary bridge passes axially through the relevant annular restrictions and hence applies a back pressure to all secondary orifices upstream of this restriction. The restriction area is therefore substantially constant and arranged to provide sufficient back pressure to suppress the generation of cavitation noise in these secondary orifices for all valve operating angles.
It is preferred that the rotary valve has eight input-shaft grooves.
It is preferred that the rotary valve has eight sleeve slots.


An inquiry respondinq apparatus receives an inquiry and stores a response to the inquiry in a first database. The apparatus determines whether or not the first database can be searched for the response to the inquiry, and when it is determined that the first database can be searched for the response to the inquiry, and when it is determined that the first database can be searched, a search for the response is performed. However, when it is determined that the first database cannot be searched, the apparatus transmits the inquiry to an external information processing device, and the apparatus receives a response to the inquiry which is transmitted from the external information processing device. Then, one of the response obtained by searching the first database and the response received from the external device is displayed on a display.

1. Field of the Invention
The present invention relates to inquiry responding apparatuses and methods, and programs used therewith, and in particular, to an inquiry responding apparatus and method in which responses to inquiries are stored in internal and external databases, and a program used therewith.
2. Description of the Related Art
In order that an enterprise may efficiently respond to inquiries from customers, an inquiry responding system has conventionally been proposed which uses a World Wide Web (WWW) browser to receive inquiries and respond (reply) thereto.
This inquiry responding system is realized by using a single (common) database. Thus, when the system has possible responses which are geographically different, it has the following problems:    (1) The common database must be updated despite the geographically different responses (replies) in the system;    (2) A customer must use the system while being aware of which region each customer belongs to; and    (3) The use and handling of languages are complicated.

Inquiry responding apparatus and method, and program used therewith


An arrangement for producing an imaging region of increased maximum radial diameter in a magnetic resonance imaging (MRI) system, comprising a solenoidal magnet arrangement (30) comprising primary magnet coils (32) arranged symmetrically about an axis (A-A) and a shim coil set.

The following description makes specific reference to axisymmetric cylindrical systems using solenoidal magnet arrangements. The terms "radial", "axial" and the like should be interpreted accordingly, unless the context requires otherwise.
The size and shape of the imaging volume of an MRI imaging system is an important driver in the design and cost of a magnet for such a system. The size and shape of the imaging volume also known as the field-of-view (FOV) can be defined by a homogeneity contour, such as the 3 ppm pk-pk contour, depending on the type of imaging required. The required radial diameter of the imaging volume is often determined by the requirement for shoulder and breast imaging. To achieve imaging volumes with sufficient radial width, magnet designers typically target a radially distended, oblate ellipsoidal imaging volume in their design.
However, there is also a demand for imaging volumes of a cylindrical shape, which are advantageous in the imaging of large areas, such as the abdomen. It is presently known to effectively achieve such cylindrical imaging volumes by joining two images each derived from an oblate ellipsoidal imaging volume, taken with the patient moved along the axis of the magnet, in the post processing stage of the imaging procedure. The use of a substantially cylindrical imaging region has the advantage that, for a given volume of the FOV, a composite image of the human abdominal region may be formed with less patient table moves than with a FOV of more conventional elliptical shape.
FIG. 1 shows example cross-sections of a presently achievable oblate ellipsoid imaging volume 10, and a presently achievable cylindrical imaging region 12 of the same volume, each being defined lying within an appropriate homogeneity contour. Note that the patient is aligned with the spine parallel to the Z axis 16 of the magnet. The ellipsoidal imaging volume 10 has an axial length z of approximately 35 cm and a radial diameter x of about 44 cm. The cylindrical imaging region 12 has an axial length z of approximately 28 cm and a radial diameter x of about 40 cm.
A possible disadvantage of such a cylindrical FOV 12 is that human shoulder areas may at least partially fall outside of the cylindrical FOV, as can be appreciated by comparing FIGS. 2A and 2B, which show views of a toroidal volume 14, in which imaging is required to be possible, relative to a cylindrical FOV 12 and an elliptical FOV 10. This is a particular issue for magnets with a limited radial width of FOV.
When a shoulder image is required in an MRI system with a FOV of limited radial width, such as the cylindrical imaging volume 12 of FIGS. 1, 2, the homogeneity can be restored by a local, passive shim. This has been shown to work, but is cumbersome and requires manual intervention for mounting and removing the passive shim.
It has been found theoretically possible to arrange for electrically operated shim coils to be switchable to convert a nominal ellipsoidal imaging volume 10, capable of imaging in toroidal volume, into a cylindrical imaging volume 12 with the same volume as the ellipsoidal imaging volume 10 and useful for imaging the abdomen. However, as illustrated in FIG. 1, this will result in a cylindrical imaging volume 12 with less radial width x than the equivalent ellipsoid volume 10. The ellipsoidal imaging volume 10, and the magnet to produce it, is typically designed to have a maximum radial diameter x sufficient to accommodate a patient's shoulders. As the cylindrical volume 12, adapted from the ellipsoid volume 10, has a reduced radial diameter x, the cylindrical volume will miss a significant part of the shoulder volume which is included within the ellipsoid volume 10. Although theoretically possible, the shim coils required to achieve this field adjustment have been found to be impractically large.
The present invention aims to address the above-mentioned difficulties, to provide a practical arrangement for generating an imaging volume of increased maximum radial diameter for a given MRI imaging system, by adaptation of a nominally substantially cylindrical imaging region.
An active, resistive shim coil has been considered which would change the imaging volume from a nominally cylindrical volume to an elliptical one suitable for imaging the toroidal volume, but such a shim is considered to be impractical, because of the amount of electrical power required. A resistive shim which specifically targets the toroidal volume, by deformation of a nominally substantially cylindrical imaging region is shown to be practical, according to the present invention. Such a shim coil will be referred to herein as a toroidal shim.
Accordingly, the present invention provides arrangements and methods as defined in the appended claims.


A single-handed manual drive wheelchair assembly (20) for a wheelchair (10) is provided for triplegic persons having use of only one hand. A first drive wheel (22) is provided rotatably mounted to one side (13) of a wheelchair frame (11), while a second drive wheel (23) is rotatably mounted to an opposite side (14) of the frame (20). A manual hand-rim assembly (26) positioned proximate the first drive wheel (22) which is mounted for rotation relative to the first drive wheel (22) about a common wheel axis (24). An elongated drive axle member (30) is coupled between the hand-rim assembly (26) and the second drive wheel (23) which is substantially axially aligned to rotate about the common wheel axis (24). The axle member (30) includes a first latching mechanism (31) on one end thereof which is releasably coupled to the hand-rim assembly (26). The axle member (30) further includes a second latching mechanism (32) on an opposite end thereof which is releasably coupled to the second drive wheel (23) such that manual rotation of the hand-rim assembly (26) from a working-hand side of the wheelchair (10) rotatably drives the second drive wheel (23).

Most conventional manually driven wheelchair assemblies are directed toward paraplegic persons having full or partial use of both hands. Triplegic or monobrachius persons having use of only a single hand (i.e., one-handed persons), however, cannot manually operate these assemblies. Modifications to the drive wheels are generally required which allow manual operation of both wheels from the working-hand side of the wheelchair.
Ordinarily, single-handed drive assemblies for manual wheelchairs provide two individually operable and concentrically positioned manual hand-rim assemblies, each driving one wheel, which are mounted on the working-hand side of the wheelchair frame. A first hand-rim assembly is directly mounted to the rim of a first wheel on one side of the wheelchair, while the second hand-rim assembly, located adjacent to and concentric with the first hand-rim assembly, is operably coupled to an opposite second wheel positioned on an opposing side of the wheelchair frame. An elongated drive axle operably couples the central hub of the second wheel to the second hand-rim assembly. Typically, the drive axle extends coaxially with the central hub of the first wheel and is rotationally independent thereof. Accordingly, the second hand-rim assembly is operably coupled to the second drive wheel in a manner enabling the second drive wheel to be driven by manual rotation of the second hand-rim assembly, which is positioned adjacent to the first hand-rim assembly of the working hand side on the wheelchair.
While these prior art single-handed manual drive wheelchair configurations have successfully provided one-handed persons with a means for operating a manual wheelchair, such wheelchairs often present transportation or portability problems in vehicles. Two-handed manually operated wheelchairs, for example, often include wheelchair frames which are collapsible, that is, the side frames are mounted to scissor-like cross frame members such that the opposing sides of the frame can be repositioned into close proximity to one another. Hence, the overall dimension of standard two-handed manual wheelchairs can be substantially reduced, which facilitates portability, storability and transportability in vehicles. Most transport vehicles, accordingly, will not require any special modifications to carry these manual wheelchairs when the frame is collapsed.
Providing collapsible frames for one-handed manual drive wheelchairs, however, is much more difficult and problematic to achieve. As above-indicated, the rigid drive axle usually extends transverse to the sides of the wheelchair frame in an orientation essentially parallel to the direction of the collapse of the conventional collapsing frame. Accordingly, without significant alteration, the drive axle substantially opposes this collapse.
One attempt to overcome this problem includes providing a pivotal joint or series of pivotal joints along the drive axle which allows the drive axle to fold in discrete sections. These sections pivot about a joint axis or axes which is/are oriented perpendicular to the longitudinal axis of the drive axle. Hence, during collapse of the wheelchair frame from the deployed position to a collapsed position, the drive axle similarly moves from an extended position, where each axle section is coaxial with the longitudinal drive axis of the drive axle, to a collapsed position, where the discrete sections of the drive axle pivot about the joints in a manner away from axial alignment.
Pivotally jointed drive axles, however, have several disadvantages. For instance, the drive axle may have to be rotated to a specific orientation to properly align the joint axes so that the axle segments can correctly pivotally fold before the wheelchair frame can be collapsed. These two maneuvers (i.e., aligning the joints of the drive axle and collapsing the wheelchair frame) may be extremely difficult for one-handed persons to simultaneously coordinate. Moreover, these jointed drive axles cause substantial backlash between the hand-rim assembly and the connected drive wheel as the pivotal joints tend to loosen with time and wear. This results in poor response of the connected second drive wheel upon initial manual rotation of the hand-rim assembly. When the operator grips both hand-rim assemblies at the same time to move the chair forward, the first drive wheel will be initially responsive while the second drive wheel, coupled to the drive axle, will not. Hence, the wheelchair operator has start-up problems driving the wheelchair in the desired direction.

Single-hand manual drive wheelchair assembly


A preventive or improving agent for medical symptoms accompanying delayed allergy reactions which contains an .omega.9-unsaturated fatty acid as an effective component is provided.

1. Field of Invention
The present invention relates to a preventive or alleviating agent for medical symptoms by delayed allergy reactions, which contains an .omega.9-unsaturated fatty acid as an effective component, and to a food or drink with a preventive or alleviating effect on medical symptoms by delayed allergy reactions. Specifically, it relates to a preventive or alleviating agent, or a food or drink with a preventive or alleviating effect against medical symptoms by delayed allergy reactions which contains as an effective component at least one selected from the group consisting of 6,9-octadecadienoic acid, 8,11-eicosadienoic acid and 5,8,11-eicosatrienoic acid.
2. Related Art
Allergy reactions are classified into 4 types, types I to IV, based on the antibodies contributing to the reaction, differences in the reaction mechanisms, presence of complement, etc. Of these, type IV allergy reactions differ from the other types of allergy reactions in that antibodies thereto cannot be detected in the blood of individuals in such an allergic state, and it is elicited by lymphocytes. Because at least 12 hours must pass from invasion of the antigen into the allergic individual until appearance of the inflammatory reaction, the type IV allergy reaction is known as "delayed type hypersensitivity".
The T lymphocytes (sensitized T lymphocytes) of individuals in an allergic condition react with the antigen, triggering the T lymphocytes to release lymphokines (macrophage migration inhibitory factor (MIF), macrophage activating factor (MAF), mitogenic factor (MF), skin-reactive factor (SRF), chemotactic factor, neovascularization-accelerating factor, etc.), which function as inflammation mediators, and the biological activity of these lymphokines, together with the direct and indirect effects of locally appearing lymphocytes and other inflammatory cells, give rise to the type IV allergy reaction (delayed allergy reaction).
Delayed allergy reactions include tuberculin type reaction, homograft rejection reaction, cell-dependent type protective reaction, contact dermatitis hypersensitivity reaction, and the like, which are known to be most strongly suppressed by steroidal agents. Consequently, steroidal agents are effective against diseases which are caused by delayed allergy reactions; however, since long-term use of steroidal agents leads to the serious side-effect known as steroid dependence, there are difficulties associated with the termination periods and methods for their administration. It has been strongly desired, therefore, to develop non-steroidal delayed allergy reaction suppressants, which have few side effects.
On the other hand, it has been reported that synthesis of leucotriene B.sub.4 is inhibited in the cells of rats raised on feed containing the .omega.9-unsaturated fatty acid, 5,8,11-cis-eicosatrienoic acid (mead acid) (J. Exp. Med., The Rockefeller University Press, vol.178, Dec. 1993, p.2261-5), although it was not clear whether or not delayed allergy reaction was suppressed.

.omega.9-unsaturated fatty acid compositions for preventing or alleviating medical symptoms caused by delayed allergy reactions


In an integrated circuit, test signals are routed from test points through a hierarchy of distributed multiplexers to output pads. The multiplexers are distributed locally to various regions that are arranged in a hierarchy of regional levels. Thus, each test signal is routed to the locally distributed multiplexer, and only a portion of the test signals reach the top-level multiplexer.

As integrated circuits (IC's) have become more complex with larger numbers of components (e.g. transistors, capacitors, etc.), techniques for testing and debugging the circuitry on the IC chips have also become more complex. Original testing techniques usually involved applying stimulus signals to the input pins of the IC and monitoring the output results and also reading internal registers of the IC. Due to the complexity of current IC's, however, it is no longer sufficient merely to supply a series of test signals at the input pins of the IC chip under test and see what happens on the output pins and to read the registers. Instead, it has become necessary to tap various internal signals at various internal test points of the IC chip that would otherwise be hidden from the outputs, so that a more detailed view of the internal workings of the many components or sub-circuits of the IC chip may be obtained. The internal signals are, thus, routed to test pads, where the signals can be measured by probes touching the test pads. Ordinarily, several such test pads and probes are used for one IC chip. As the IC chips have become more complex with larger numbers of components, however, it has become impractical to simultaneously probe each test point, since there may be several hundred or thousands of desired test points. There is physically not enough room to apply a test probe to a test pad for each test point or internal signal. Therefore, it has become necessary to multiplex the internal signals together to select only a subset of the internal signals to be sent to a reasonable number of the test pads at one time. The tests are typically repeated with different subsets of the internal signals selected each time in order to sample all of the desired test points and internal signals.
All of the internal signals from all test points 100 are, thus, routed to a multiplexer 102, as shown for an exemplary IC 104 in FIG. 1. Each of the dots in FIG. 1 represents a test point 100 from which signal traces, wires or conductive paths 106 carry the internal signals to the multiplexer 102. The test points 100 are typically arranged in hierarchical levels 108, 110 and 112 that correspond to levels of "functional blocks" or "functional units" of the IC 104. At the lowest level 108 (level 3), the test points 100 typically involve groups 114 of related test points 100, such as for a particular small portion of the overall IC 104. The lowest levels 108 (levels 3), which are typically "component blocks" of the IC 104, may include one or more of the groups 114 of related test points 100. The next level 110 (level 2) may include one or more of the previous levels 108 (levels 3), and so on. At each succeeding level 108, 110 and 112, the signal traces 106 are typically aggregated into ever larger groups, so that by the time the signal traces 106 reach the multiplexer 102, there may be several hundred or thousands of the signal traces 106. Under control of test equipment (not shown), the multiplexer 102 typically selects one of the groups 114 of the signal traces 106 to supply selected internal signals to test pads 116.
With several hundred or thousands of the signal traces 106 to be routed around the IC 104 from the test points 100 to the multiplexer 102, chip layout becomes more costly, difficult and time-consuming. The signal traces 106 take up considerable space on the IC 104, which already contains many components for performing the actual functions of the IC 104. Determining the most efficient, economical and unobtrusive layout for the signal traces 106 to avoid interfering with the spaces for the components of the IC 104 requires significant time and resources.
It is with respect to these and other background considerations that the subject matter herein has evolved.

Routing of test signals of integrated circuits


An operating method of a nonvolatile memory device controller includes generating a code word through polar encoding of information bits, reading a mapping pattern, generating a repeated mapping pattern through iteration of the mapping pattern, and mapping each bit of the code word onto a specific bit of multi-bit data of the nonvolatile memory device, based upon the repeated mapping pattern.

1. Technical Field
The present disclosure relates to a semiconductor memory device, and more particularly, relates to an operating method of a controller for controlling a nonvolatile memory device and a mapping pattern selecting method for selecting a mapping pattern mapping a polar coded code word onto multi-bit data of the nonvolatile memory device.
2. Discussion of Related Art
A semiconductor memory device is a memory device which is fabricated using semiconductors such as silicon (Si), germanium (Ge), gallium arsenide (GaAs), indium phosphide (InP), and the like. Semiconductor memory devices are classified into volatile memory devices and nonvolatile memory devices.
The volatile memory devices may lose stored contents at power-off. The volatile memory devices include various random access memory (RAM) devices, such as a static random access memory (SRAM), a dynamic RAM (DRAM), a synchronous DRAM (SDRAM), and the like. The nonvolatile memory devices may retain stored contents even at power-off. The nonvolatile memory devices include a read only memory (ROM), a programmable ROM (PROM), an electrically programmable ROM (EPROM), an electrically erasable and programmable ROM (EEPROM), a flash memory device, a phase-change RAM (PRAM), a magnetic RAM (MRAM), a resistive RAM (RRAM), a ferroelectric RAM (FRAM), and the like. The flash memory device is roughly divided into a NOR type and a NAND type.
Polar encoding has recently been introduced as a low-complexity coding scheme for a large class of channels. Polar encoding typically represents bits by using two levels of polarity or amplitude: positive and negative. A common type is polar encoding is Non Return to Zero (NRZ). With NRZ the level of signal is determined by the binary digit being sent. Binary 1's are indicated by positive voltages and binary 0's by negative voltages. However, a need exists for a method and apparatus configured to control nonvolatile memory devices using polar encoding.

Operating method of controller controlling nonvolatile memory device and mapping pattern selecting method of selecting mapping pattern mapping polar coded code word with multi bit data of nonvolatile memory device


Apparatus, system and method is provided in which a primary printer prepares print data for use by its resident print engine, or by an alternate printer. The primary printer includes subsystems for receiving original print data from a device, such as a computer or scanner, and for converting the original print data into a data format compatible with the alternate printer.

The quality of the output generated by modern computer printing systems has increased greatly in recent years. Among the improvements seen are higher resolution, device independent color and contone (continuous tone) imaging. These advanced capabilities greatly increase the requirements for computing resources available to the printer controller. Included among these are requirements for greater amounts of main memory for storing data as well as a sophisticated control program and means to store it. These features add significantly to the cost of the printer.
One way to provide advanced functionality while maintaining low cost is to provide a host raster image processor (RIP). RIP is a program that generates a bit map of the image to be printed. This bit map is used by printing hardware to produce the printed page. Normally the RIP resides in the printer where it interprets commands received from the host computer. In the case of a host RIP, the print data is processed on the host computer and the resulting bit map is then sent to the printer. This means that the RIP makes use of the computing resources in the host computer rather than in the printer. Since the printer does not need to provide these resources, the printer can be simpler and cheaper to manufacture.
A host RIP suffers a number of disadvantages. For example, demanding computing resources from the host computer to perform the RIP function takes the computing resources away from the user. A host RIP can greatly increase the delay between when a user issues a command to print and when the user is able to use the computer again. Another disadvantage is that the host RIP must download the entire bit map to the printer. Modern printer data streams are based upon concise descriptions of a page. Downloading a full bit map involves transferring a much greater amount of data than the data required if the bit map is generated at the printer, thereby involving still more work for the host to perform, as well as tying up a communications channel for a longer period of time. In addition, some print mechanisms have strict time constraints on when the data must be available. For example, once a laser printer begins to print a page, all the data for that page must be available without interruption. Typical communications channels between the host and print mechanism cannot be relied upon to supply the data at exactly the correct rate, thereby requiring either buffers in the print mechanism or a dedicated real time communications circuit within the host. Even when a communication channel supports the time constraints for data to such print mechanisms, a typical data processing host cannot satisfy the time constraints. Guaranteed response to requests with real time constraints defines a particular class of processing known as "real time operating systems".
Low cost basic printers will often have only very limited capabilities. In some cases, such a printer may be upgraded by adding more advanced features. This has the shortcoming of requiring "upgradeability" to be part of the printer's initial design. This may require the inclusion of extra sockets or connectors, as well as a more complex design, or even the inclusion of empty space under the covers to provide room for upgrades. In addition, there are features which may be difficult or unsuitable to provide as upgrades, or may be incompatible with one another. For example, full color laser printers do exist, yet it may always be impractical to upgrade to this capability starting from a monochrome laser printer.
When new printing requirements cannot be satisfied by upgrading current hardware, the only apparent solution is to provide a multiple printing system. Each printer of the system operates independently of any other printer in the system, and therefore, has independent requirements for memory and control programs. For example, a user may require the use of both a laser printer and a color ink jet printer. If both of these printers were originally configured such that they could only interpret a less sophisticated data stream, upgrading the control program of one would not benefit the other. Similarly, if both printers are constrained by limited memory resources, adding memory to one will not benefit the other.
Printers typically include many subsystems, such as an input/output (IO) subsystem for handling communication, a controller, and a print engine. Typically, the printer receives a data stream from a computer through the IO subsystem, the controller processes the data stream to generate a bit map, and the controller sends the bit map to the print engine to form an image corresponding to the data stream on a print media.
During operation, the controller executes a printer control program designed with an understanding of the hardware constraints, or characteristics, of the hardware it is to control. Among these characteristics are resolution, print media size, color capability, binary vs. contone printing, etc. Some of these characteristics can be manipulated among a finite set of values, while other characteristics cannot be modified at all. For example, the size of the paper might be changed from letter size to legal size, but the print mechanism places an absolute upper limit on what sizes of print media can be supported.
The print engine dictates how many bit planes the bit map should contain. For example, a monochrome print engine uses only a single bit plane for each page. Print engines which produce color output require multiple bit planes in order to produce a multiplicity of colors, one for each primary color utilized by the print engine. For example, a print engine which uses the primary colors cyan, magenta, and yellow (CMY) requires three bit planes, and a print engine which uses the primary colors cyan, magenta, yellow, and black (CMYK), requires four bit planes.
Because these and other characteristics are determined by the print engine, they are either fixed or limited to a specific set of possible values. Thus, prior to the invention the controller of a printer would not configure the bit map using parameters outside of the range of values which are appropriate for the print engine of the printer. For example, the controller would not produce a bit map for a tabloid size page if the print engine is unable to handle media that large, or would not generate multiple bit planes if the print engine is monochrome.


The carbon dioxide recovery method and apparatus are capable of reducing energy for regenerating the absorbing liquid and operating cost. An absorption column has first and second absorbing sections that a gas is supplied through the first absorbing section to the second absorbing section and the absorbing liquid absorbs carbon dioxide. A regeneration column regenerating the absorbing liquid has first and second regenerating sections. The first regenerating section has an external heating implement and the second regenerating section is heated by the gas discharged from the first regeneration section. Circulation mechanism has a circulation system circulating the absorbing liquid between the second absorbing section and the first regenerating section, and a branch path branched from the circulation system. A part of the absorbing liquid circulating the circulation system flows from the second absorbing section through the first absorbing section and the second regenerating section successively to the first regenerating section.

Field of the Invention
The present invention relates to a method of recovering carbon dioxide and recovery apparatus of carbon dioxide to return a clean gas into the air by separating and recovering carbon dioxide from a gas containing carbon dioxide such as a combustion gas.
Description of the Related Art
A large amount of fuel such as coal, heavy oil and extra heavy oil is used in facilities such as thermal power stations, ironworks and boilers. In regard to sulfur oxide, nitrogen oxide and carbon dioxide discharged by burning of the fuel, quantitative/concentration restriction on emissions has been required from the viewpoint of prevention of air pollution and global environmental protection. In recent years, carbon dioxide has been viewed as a problem as is a major contributor to global warming, and moves to suppress carbon dioxide emissions have been active worldwide. Therefore, various kinds of research have been vigorously conducted in order to enable recovery/storage of carbon dioxide from a combustion exhaust gas or a process exhaust gas instead of emitting carbon dioxide in the air. For example, a PSA (pressure swing adsorption) method, a membrane separation concentration method, and a chemical absorption technique using reaction absorption with a basic compound have been known as a method of recovering carbon dioxide.
In the chemical absorption technique, a basic compound that typically belongs to alkanolamines is mainly used as an absorbent, and the absorbing liquid is circulated in the treatment process thereof, generally, with use of an aqueous solution containing the absorbent as the absorbing liquid, by alternately repeating an absorption step of causing the absorbing liquid to absorb carbon dioxide contained in the gas and a regeneration step of regenerating the absorbing liquid by causing the absorbing liquid to release the absorbed carbon dioxide (see, for example, Publication Document 1 described below). Heating for the release of carbon dioxide is needed in the regeneration step, and it becomes important to reduce energy required for heating/cooling for the regeneration, in order to reduce the operation cost of carbon dioxide recovery.
As disclosed in Publication Document 1, a high-temperature absorbing liquid from which carbon dioxide has been discharged (lean solution) in the regenerating step is subjected to heat exchange with an absorbing liquid in which carbon dioxide has been absorbed (rich solution) in the absorbing step. In this way, thermal energy is possibly recovered to reuse in the regenerating step.
In order to reduce the energy required for recovering carbon dioxide from the absorbing liquid, according to Publication Document 2 listed below, the following is used for heating the absorbing liquid: residual heat of steam-condensed water generated from a regenerating heater for pulling out the absorbing liquid in the regenerating step and then subjecting the absorbing liquid to heat exchange with high-temperature steam. Furthermore, Publication Document 3 listed below states that, in order to promote the discharge of absorbed carbon dioxide, a stripping gas is introduced to be accompanied with carbon dioxide. Moreover, Publication Document 4 listed below states that two regeneration towers in each of which the absorbing liquid is heated to a high temperature or a low temperature are used and the absorbing liquid regenerated at the low temperature is supplied to a middle stage of an absorption column, thereby reducing energy required for heating.

This patent is subject to a terminal disclaimer.

Method of recovering carbon dioxide and recovery apparatus


A chemical anchor bolt and cap assembly installable in a hole drilled in masonry for fastening an object thereto The threaded shank of the bolt and the hollow cap extending from its end are inserted into the hole, causing an uncured bonding agent deposited in the hole, such as an epoxy, to surround the cap and the shank. When the epoxy hardens the cap is then embedded in the epoxy to create a void below the end of the shank. Cast in the epoxy surrounding the shank is a female thread that complements the shank thread. To permit the bolt to turn and cause the end of the shank to advance into the void and thereby tighten the fastening, the threaded shank has coated thereon a releasable barrier layer that acts to masks surface irregularities in the shank thread and to slightly space the shank thread from the female thread. As a consequence, the female thread cast in the epoxy is functionally free of irregularities and is loosely intermeshed with the shank thread whereby the bolt can then be easily turned.

1. Field of Invention
This invention relates generally to chemical anchors installable in a hole drilled in masonry in which is deposited a chemical bonding agent to fasten a fixture or other object to the surface of the masonry, and more particularly to a chemical anchor bolt and cap assembly in which the threaded shank of the bolt is coated with a releasable barrier layers making it possible to turn the bolt and thereby tighten or remove the fastening.
2. Status of Prior Art
The term masonry refers to a construction of stone or similar material such as concrete and brick. The walls, ceiling and floors of many edifices are formed of masonry. In order, therefore, to fasten fixtures, machines, structural members or other objects to masonry, a masonry anchor is required for this purpose.
In the case of concrete or other forms of masonry, one cannot drill a hole therein and then tap this hole so that it can receive an anchor bolt, a threaded stud or other threaded mounting means to secure a fixture or other object to the face of the masonry. The nature of masonry is such that a cutting action to cut female threading into the bank of the hole cannot be effected, for this action will disintegrate the masonry material.
In order, therefore, to anchor a threaded rod or stud in a hole drilled in masonry, the present practice is to use a curable chemical bonding agent for this purposes. The typical agent of this type has two flowable components, one being a resinous bonding agent, the other a hardener therefor. The resins may be phenol, vinyl, ester or epoxy based. The two components, when stored, must be separated to prevent interaction therebetween. Many bonding agents currently available have an accelerated curing time and set within 10 to 30 minutes to afford substantial holding power. In practice, a charge of the resinous component and sufficient hardener intermixed therewith are deposited in the hole, and a threaded mounting stud is then inserted in the hole.
To this end, use may be made of a dispenser gun to inject a charge of the flowable bonding agent into the drilled hole. Or the charge may be contained in a capsule that is deposited in the drilled hole and is ruptured to release the bonding agent when the stud is inserted in the hole.
After the resinous interfacial layer between the stud and the bank of the hole cures and rigidifies, it then bonds itself both to the stud and to the masonry whereby the stud is permanently anchored in the hole. In order now to secure a fixture to the masonry face, the fixture which has a mounting hole therein is placed onto the projecting stud and locked thereto by a washer and nut.
A chemical anchor in accordance with the invention is useable with any type of curable bonding agent capable of setting in a reasonable time. The term epoxy, as hereafter used, is intended to cover a two-component epoxy and any other suitable curable bonding agent.
The concern of the present invention is with a chemical anchor that makes use of a bolt from whose head extends an externally-threaded cylindrical shank coated with a release agent. When the shank of the bolt is inserted in a drilled masonry hole having a charge of an uncured bonding agent deposited therein the release coating prevents this bonding agent, when cured and hardened from adhering to the shank.
A chemical anchor of this type is disclosed in the Kellison U.S. Pat. No. 4,642,964 and also in the Roth U.S. Pat. No. 5,590,360. In the chemical anchors disclosed in these patents, when the bonding agent hardens in the drilled masonry hole, a female thread is then cast in the hardened epoxy surrounding the shank. This female thread mates with the male thread of the release-coated shank; hence the bolt is then free to turn in the female thread in either direction.
In order to be able to tighten the fastening of the fixture against the masonry, a torque tool is used to engage the head of the bolt which is above the surface of the fixture and to turn the bolt to threadably advance the shank which is received in the masonry hole, thereby pressing the bolt head against the fixture.
To make this advance possible Kellison attaches a hollow cap to the end of the shank while Roth attaches a cylindrical housing to the end of the shank. In both cases, this creates in the hardened epoxy below the end of the shank in the drilled masonry hole a void to accommodate the advancing shank. As the shank advances into the void, the head of the bolt then presses harder against the surface of the fixture to tighten the fastening.
In Kellison, the release agent which coats the threaded shank to permit it to turn includes commercially-available waxes or greases. Kellisone's preferred release agent is PTFE (Teflon) particles dispersed throughout a grease or a grease-like lubricant. In Roth, the release agent is Teflon tape wrapped around the thread of the shank, or a wax or plastic coating applied to the thread.
The practical drawback of a release coating of the types disclosed in the Kellison and Roth patents is that they fail to take into account imperfections in commercially-available bolts having a threaded shank. These mass-produced bolts do not have a perfectly machined helical thread, for in manufacturing the bolt the shape of the thread will often vary to some degree along the length of the shank. The surfaces of the thread flanks are somewhat irregular or rough, and the actual pitch diameter of the thread varies within the allowable tolerances of standard thread specifications.
The fact that commercially-produced bolts are imperfect does not interfere with the normal uses to which these bolts are put. Thus if the bolt cooperates with a nut that turns on the threaded shank, irregularities on the surfaces of the shank thread will not prevent the nut from turning.
But when the same bolt is used for chemical anchoring in which the thread on the shank acts to mold a female thread in the epoxy surrounding the shank, then irregularities in the shank thread are reflected in the female threads even though the shank thread is thinly coated with a grease-like release agent. Similarly, when a Teflon tape is wrapped about the shank thread to serve as a release agents the tape conforms to the irregularities of the shank thread and these irregularities are reflected in the cast female thread.
Because irregularities impressed in the female thread in the epoxy surrounding the shank thread mate with irregularities in the surface of the shank thread, this interferes with the ability of the bolt to turn to tighten the fastening of the chemical anchor. Thus if there is a small projection on the surface of the shank thread, this will create a matching indentation in the female thread cast in the epoxy that will resist turning of the bolt.
Because in a typical commercially-produced bolt, irregularities on the shank thread are dispersed throughout the surface of the bolt, it becomes very difficult to turn the bolt to tighten the fastening, even when the release agent coating the shank is a lubricant.
When as in the Roth patent, the release agent is wax or plastic, it is difficult with these materials to create on the threaded shank of the bolt a barrier layer of uniform thickness on the flank surfaces of the thread, as is necessary in a releasable barrier in accordance with the present invention. Moreover, a wax coating will not survive when the wax coated bolts are stored in a heated environment as is often the case.
A drawback of grease-like release agents on anchor bolts is that when used at construction sites where holes are being drilled in concrete masonry, then concrete dust from these drilling operations is picked up by the grease and contaminate the release agent.

Releasable barrier coating for chemical anchor bolt


Encoded data may be generated and transmitted from one computing device to another via a network. To address bandwidth use efficiency issues, an available bandwidth for the other computing device may be determined or acquired. A time at which the available bandwidth is determined/acquired may be estimated. Media data (e.g., audio, video, etc.) may be encoded for transmission. Scheduled change time, at which a setting of an encoding condition is expected to be changed, is further determined. Change timing, at which the setting of an encoding condition is to be changed, is determined on the basis of the scheduled change time and the estimated time. The setting of the encoding condition may then be changed in accordance with the available bandwidth when the change timing is reached.

1. Field of the Disclosure
The present disclosure relates to encoding media data depending on a bandwidth between a data transmission source communication apparatus and a transmission destination communication apparatus, as well as a storage medium.
2. Description of the Related Art
The volume of data that a communication apparatus can transmit over a network per unit of time is referred to as an available bandwidth (in bps). The number of bits that a communication apparatus conveys per unit of time over a network is referred to as a transmission bit rate (in bps). A transmission bit rate higher than the available bandwidth causes problems such as data congestion, packet loss, etc. A transmission bit rate lower than or equal to the available bandwidth might not be as susceptible to the problems of data congestion, packet loss, etc. However, if the transmission bit rate is significantly lower than the available bandwidth, the communication apparatus cannot make the best use of the available bandwidth (e.g., efficiency or effectiveness of bandwidth usage may be low). Accordingly, it is preferable that an encoding apparatus that encodes media data performs encoding in accordance with an available bandwidth that changes depending on the circumstances, such as an area, provider, and time zone, to adjust the transmission bit rate.
For example, a known moving-image distribution apparatus measures an available bandwidth by transmitting a fixed volume of moving-image data in burst manner and determining the amount of time required to complete the transmission. The transmission bit rate is adjusted on the basis of this measurement result.
If the setting of encoding conditions is changed to adjust a transmission bit rate to a target value, it takes a substantial amount of time before the transmission bit rate actually attains the target value. Even if the encoding apparatus continuously changes the setting of encoding conditions before the transmission bit rate attains the target value, the transmission bit rate cannot be suitably controlled. That is, suitable timing for changing the setting of encoding conditions might not be achieved. The time required to measure an available bandwidth sometimes changes under the influence of a network environment. Accordingly, it is also difficult for the encoding apparatus to acquire the measurement result of an available bandwidth in time to change the setting of encoding conditions. Thus, encoding apparatuses in the related art cannot change the setting of encoding conditions at suitable timing according to the measurement result of an available bandwidth.

Encoding apparatus, encoding method, and storage medium


A wireless communication system grey-lists those channels that interfere with channels used by a second wireless communication system. The wireless communication system reduces the rate at which the grey-listed channels are utilized in the channel-hopping pattern, but does not completely eliminate use of the grey-listed channels.

The present invention is related to wireless communication systems, and in particular to channel selection in wireless communication systems.
In many industrial settings, control systems are used to monitor and control inventories, processes, and the like. Often, such control systems have a centralized control room with a host computer that communicates with field devices that are separated or geographically removed from the control room.
Generally, each field device includes a transducer, which may generate an output signal based on a physical input or generate a physical output based on an input signal. Types of transducers used in field devices include various analytical equipment, pressure sensors, thermistors, thermocouples, strain gauges, flow sensors, positioners, actuators, solenoids, indicators, and the like. Traditionally, analog field devices have been connected to the process subsystem and the control room by two-wire twisted-pair current loops, with each device connected to the control room by a single two-wire twisted pair loop. Typically, a voltage differential is maintained between the two wires of approximately 20 to 25 volts, and a current between 4 and 20 milliamps (mA) runs through the loop. An analog field device transmits a signal to the control room by modulating the current running through the current loop to a current proportional to the sensed process variable. An analog field device that performs an action under the control of the control room is controlled by the magnitude of the current through the loop, which is modulated by the ports of the process subsystem under the control of the controller.
Wireless communications between field devices and controls rooms have begun to replace the traditional two-wire twisted-pair current loops. For example, each field device and/or node associated with a field device is equipped with a wireless transceiver that allows the field device to communicate messages wirelessly via a wireless communication protocol such as WirelessHART (IEC 62591). The plurality of field devices and/or nodes equipped with wireless transceivers create a wireless mesh network that allows a communication between the control room and any field device within range of the wireless mesh network, with messages hopping from node to node across the mesh network to the desired location.
Like other wireless communication protocols, wireless communication protocols such as WirelessHART employed in control system operate in a defined frequency range that is further sub-divided into a plurality of channels. Communication between two devices using WirelessHART (or some other wireless communication protocol) requires agreement as to the channel on which the communication will occur. However, problems can occur when additional wireless communication protocols (such as WiFi) are operational in the same geographic location as the control system wireless communication protocol. For example, a facility using a control system wireless communication protocol such as WirelessHART may also be employing a WiFi type wireless communication protocol to allow employees to exchange data over a wireless local area network (WLAN). Overlap between the frequencies employed by WirelessHART and by WiFi will result in interference, which may result in messages being lost (i.e., sometimes referred to as packet loss).
To avoid interference between competing wireless communication protocols, it is common to identify the channel(s) being utilized by the competing wireless communication protocol such as WiFi, and then program the control system wireless communication protocol (e.g., WirelessHART) to avoid those overlapping channels. However, blacklisting channels available to the control system wireless communication protocol decreases the number of channels that can be used in a channel hopping sequence and therefore decreases the resiliency of the wireless communication system. The term "resiliency" is used to describe the ability of the wireless network to operate despite intentional or unintentional interference on a channel. For example, typical wireless systems employ channel-hopping among a plurality of channels to prevent a malicious user from jamming a particular frequency to disrupt communications. As the number of channels used by a particular wireless system decreases, the resiliency of the system similarly decreases.


A socket having an overheating destructive limiting element includes a housing, a live wire conductive plate, a neutral wire conductive plate, at least one live wire terminal, at least one neutral wire terminal, and at least one limiting element. The live wire terminal includes a live wire contact portion in contact with the live wire conductive plate. The neutral wire terminal includes a neutral wire contact portion in contact with the neutral wire conductive plate. The limiting element is an insulating body, and is placed at contact parts of the live wire conductive plate and the live wire contact portion, and/or at contact parts of the neutral wire conductive plate and the neutral wire contact portion. When an operating temperature becomes excessively high, the limiting element becomes deformed and destructed to form a turn-off position.

a) Field of the Invention
The invention relates in general to a socket having an overheating destructive limiting element, and more particularly, to a socket having a limiting element made of an insulation material that positions a live wire terminal, a live wire conductive plate and/or a neutral wire terminal and a neutral conductive plate at a turn-on position. When an operating temperature gets too high, the limiting element becomes deformed and destructed to change the live wire terminal, the live wire conductive plate and/or the neutral wire terminal and the neutral conductive plate to a turn-off position.
b) Description of the Prior Art
To prevent a circuit from issues of current overload, short circuit and overheating, a fuse or an overload protector is usually provided at the circuit. When the temperature of the circuit gets too high or the current gets too large, the fuse affected by the high temperature becomes blown or a bi-metal shrapnel of the overload protector becomes disengaged, so as to cause the circuit become open circuit and turned off to ensure electricity safety.
Regarding the prior art of a fuse structure, for example, the Taiwan Patent No. 1371053 discloses "Temperature Fuse Connection Structure", which mainly includes two terminals and a meltable metal. The two terminals are fixed and assembled at circuit wires, with two free ends of the two terminals respectively disposed with through openings. When not receiving an external force, the two free ends of the two terminals are kept at a distance in between. At least one of the two terminals is made of a flexible conductive material and is thus a flexible terminal. With the flexibility of the flexible element, an elastic force that separates the two free ends of the two terminals is formed. The meltable metal is penetrated through the openings of the two free ends. Two ends of the meltable metal are impinged by a riveting means to enlarge the two ends of the meltable metal. Further, the free ends of the two separated terminals are electrically connected, such that the free ends of the two terminals inwardly and closely come into contact while also being respectively separated outwards by the elastic force. In the event of current overload, circuit overheating or an excessively high ambient temperature, the meltable metal is heated to cause a rise in the temperature and becomes molten and broken. As such, the free ends of the two terminals become disconnected and the circuit then becomes a turn-off state.
However, due to reasons below, the above disclosure or the overload protector needs to be further improved.
First of all, in the "Temperature Fuse Connection Structure" disclosed by the Taiwan Patent No. 1371053, the meltable metal is a conductive material, and is shaped in a rivet form to electrically connect the free ends of two separate terminals. When the meltable metal is molten, it is possible that the molten and broken meltable metal be expelled from an original position by the elastic force of the two terminals, or remain stuck to the two terminals. If the molten meltable metal is expelled from the original position, with collisions against other objects or subsequent external forces, it is much likely that the molten meltable metal be moved back to between the two terminals or other positions that may connect the two terminals. As a result, the two terminals intended to be disconnected may again erroneously come in contact to form close circuit. If a part of the molten meltable metal remains stuck to the two terminals, the stuck molten meltable metal may also result in an erroneous contact between the two terminals to fail in a complete disconnection. Further, the expelled molten meltable metal also has a chance of coming into contact with other surrounding electronic elements to cause a short circuit. Therefore, such conventional solution is exposed to potential hazards and needs to be improved.
Secondly, in the "Temperature Fuse Connection Structure" disclosed by the Taiwan Patent No. 1371053, the meltable metal fixes the two terminals by a riveting means, which requires the two terminals to be provided with corresponding through openings. The presence of the two openings equivalently reduces the mutual contact area between the two terminals. When the current passes through the contact part of the two terminals, a higher operating temperature is caused because of the smaller contact area. More particularly, when the two terminals are selected from a thinner material with a preferred flexibility, e.g., when the two terminals are conductive copper plates having a thickness of 0.2 mm to 0.4 mm, the rise in temperature is very noticeable.
Thirdly, a conventional overload protector has a large volume. To apply the overload protector to a socket to obtain an auto power-off effect in the event of overheating, the socket also needs a larger volume. Especially for an extension socket, e.g., an extension socket having six socket units, if each of the socket units is provided with one overload protector, the volume of the extension socket will become huge as six socket units and six overload protectors are at the same time accommodated therein. Whether for storage, transportation or usage, such excessive volume inevitably causes complications and inconveniences.

Socket having overheating destructive limiting element


A sealed power distribution module includes a nonconductive body defining a terminal receptacle, a barrier seal engaged to and surrounding the body adjacent the receptacle on an exterior surface of the body, a terminal element grid fitted within the receptacle, and provisions for installing commercially available sealed terminals to complete the wiring. The grid is engaged to the body at a location interior to the barrier seal. The power distribution module may also include one or more bus bar assemblies oriented such that simultaneous switching of relay packages is possible.

This invention relates generally to power distribution blocks or terminal blocks and, more particularly, to power distribution blocks for vehicle electrical systems.
Fuses are widely used as overcurrent protection devices to prevent costly damage to electrical circuits. Fuse terminals typically form an electrical connection between an electrical power source and an electrical component or a combination of components arranged in an electrical circuit. One or more fusible links or elements, or a fuse element assembly, is connected between the fuse terminals, so that when electrical current through the fuse exceeds a predetermined limit, the fusible elements melt and opens one or more circuits through the fuse to prevent electrical component damage
Power distribution blocks and terminal blocks are sometimes utilized to collect a plurality of fuses in a central location in an electrical system. Conventionally, fuse blocks include individually wired circuits within the block for power input. As such, when it is desired to power more than one circuit with the same power source, a jumper is installed for this purpose. Installation of jumpers, however, is costly, labor intensive, and time consuming. In addition, added circuits require the use of larger gauge wiring in order to handle the additional current load. Accommodation of additional loads and auxiliary circuits with conventional fuse blocks used in, for example, vehicle electrical systems, is therefore difficult. Electrical systems of many vehicles now include expanded electrical systems to accommodate additional vehicle features and entertainment devices. Some types of vehicles, for example, watercraft, buses, and recreational vehicles include separately powered auxiliary loads for such purposes, and wiring these loads to auxiliary power sources adds to the complexity and difficulty of wiring the electrical system of the vehicle.
At least some existing fuse blocks are configured for plug-in connection to circuitry to avoid labor intensive hard-wired connections. See for example, U.S. Pat. No. 6,431,880. Connections in such fuse blocks are made to one or more internal buses to selectively distribute electrical power to, for example, different electrical subsystems of a vehicle. The use of a second internal bus allows a user to switch a bank of relays at the same time. This type of switching can be used accomplished using either power or ground. Such fuse blocks, however, are commonly used with switching elements which must be separately wired from the fuse block so that power can be selectively switched to certain components or circuits in the electrical system. Additionally, switching elements permit convenient disconnection of associated circuits from the power source during maintenance procedures, and avoids a need to remove and reinstall fuses in vehicle environments where access to the fuses is often restrictive.
Power distribution blocks are known which may accommodate fuse, circuit breakers, and relay switches in a single package, and thus provide both overcurrent protection and convenient switching of power in a single package. One such power distribution block, sometimes referred to as a vehicle electrical center (VEC) is commercially available from Cooper/Bussmann of St. Louis, Mo. However, these power distribution blocks tend to be too large and/or too expensive for use in certain applications, and also contain features that are not necessary for many applications. For example, some specialty vehicles, construction and agricultural equipment, marine applications, and truck, bus, and RV applications do not require the sophistication of the VEC or justify the cost of such distribution blocks.
Additionally, specialty vehicles, construction and agricultural equipment, marine applications, and truck, bus, and RV applications often entail additional moisture, vibration, and contaminant issues in use which are not experienced by conventional fuse blocks or power distribution blocks for automotive applications. Thus, conventional fuse blocks and power distribution are poorly suited for certain applications.

Sealed compact power distribution module