CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    The present application claims priority to Korean Patent Application Number 2008-0050371 filed May 29, 2008, the entire contents of which application is incorporated herein for all purposes by this reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to an electromagnetic active engine mount apparatus, and more particularly, to an electromagnetic active engine mount apparatus, in which a sub-channel through which working fluid flows is formed in the central portion of an electromagnetic drive so as to cool heat generated from a coil of a solenoid section of the electromagnetic drive by repetitive operation of a vibrating member, thereby inhibiting the heat generated from the coil to thus protect various components formed of rubber from thermal damage, and providing improvement of its durability, reduction of its size, and simplification of its structure. 
         [0004]    2. Description of Related Art 
         [0005]    The engine of a vehicle may be regarded as a kind of vibration generating source. Thus, when the engine is mounted on a body of the vehicle, a medium called an engine mount is used, thereby preventing vibration generated from the engine and its resultant noise from being transmitted to the vehicle body. 
         [0006]    Generally, in the case of small gasoline engine vehicles, a bush-type mount apparatus formed of rubber has been mainly used. In the case of large gasoline engine vehicles and diesel engine vehicles, a hydraulic type engine mount apparatus in which fluid is encapsulated has been used. However, this passive engine mount apparatus cannot block the vibration and noise within all the ranges including a variable operation region from the viewpoint of its structure. 
         [0007]    The vibration generated from the engine is varied in idling, low-speed running, and high-speed running. As such, the engine mount apparatus requires different levels of dynamic stiffness in the idling and low-speed running and the high-speed running. In detail, low dynamic stiffness is required in the idling and low-speed running, whereas high dynamic stiffness is required in the high-speed running. In connection with a frequency of the vibration generated from the engine, the vibration can be divided into three regions: a shaking region where low-frequency and high-amplitude vibration occurs, an idle region where middle-frequency and middle-amplitude vibration occurs, and a booming region where high-frequency and low-amplitude vibration occurs. In order to produce a more excellent vibration damping effect, the engine mount apparatus must have different dynamic stiffness according to each region. 
         [0008]    However, the aforementioned bush-type or hydraulic-type engine mount apparatus cannot have a vibration damping function for the viewpoint of its structure in all these variable regions. Thus, a recent tendency shows that an active engine mount apparatus is developed so as to be able to control the vibration of the engine in all the variable regions. 
         [0009]    Generally, the active engine mount apparatus is configured to reduce the vibration of the engine by mounting a separate vibrating member on the liquid-filled engine mount apparatus and thus actively controlling the vibrating member so as to be vibrated according to a vibration state of the engine. The active engine mount apparatus can be classified as an electromagnetic type, a pneumatic type, etc. according to a mode of operating the vibrating member. 
         [0010]      FIG. 1  is a schematic cross-sectional view illustrating the structure of a conventional electromagnet active engine mount apparatus. 
         [0011]    As illustrated in  FIG. 1 , the electromagnet active engine mount apparatus is configured so that a center bolt  11  for coupling with an engine is inserted and coupled into and to the central portion of a main rubber  10 . The main rubber  10  is coupled on an upper side of a hollow main pipe  20  by, for instance, curing bonding, and is adhered with a diaphragm  30  on an upper circumference thereof. At this time, an orifice section  50  and a vibrating member  60  are air-tightly coupled on a lower side of the main pipe  20 , thereby defining a damping chamber  40  such that a working fluid is encapsulated in an inner space defined by the main rubber  10 , diaphragm  30  and main pipe  20 . The damping chamber  40  is partitioned into a main liquid chamber  41  and an auxiliary liquid chamber  42  by the orifice section  50  and the vibrating member  60 . The main and auxiliary liquid chambers  41  and  42  communicate with each other through an orifice channel  51  formed in the orifice section  50 . 
         [0012]    Generally, the vibrating member  60  is composed of a vibrating plate  61  and a vibrating rubber  62 . The vibrating plate  61  is coupled to the orifice section  50  through the vibrating rubber  62 , and is vibrated by an electromagnetic drive  70  mounted at a lower portion thereof. 
         [0013]    The electromagnetic drive  70  is mounted below the vibrating member  60  and the orifice section  50 , and includes a ring-shaped solenoid  74  generating an electromagnetic force, an armature  75  connected to the vibrating member  60  and moving up and down by means of the solenoid  74 , and a case  76  enclosing the armature  75 . Here, the solenoid  74  includes a coil  71  wound in a ring shape, a yoke  72  enclosing the outside of the coil  71 , and a core  73  repeatedly attaching and detaching the armature  75  by means of the electromagnetic force. 
         [0014]    With this configuration, when electric current flows through the coil  71 , the armature  75  is repeatedly attached to and detached from the core  73  while moving up and down. Simultaneously, the vibrating plate  61  coupled to the armature  75  also repeatedly moves up and down to generate vibration. The vibration of the vibrating plate  61  is transmitted to the working fluid in the main liquid chamber  41 . Owing to this transmission of the vibration of the vibrating plate  61 , the vibration transmitted from the engine is reduced. 
         [0015]    More specifically, a separate controller controls the solenoid  74  according to the vibration state of the engine to generate a waveform having the same phase as that of the vibration of the engine so as to offset the vibration of the engine. At this time, a filtering plate  80 , which has a through-hole  81  in the central portion thereof above the vibrating plate  61 , is mounted on the orifice section  50 , so that the vibration created by the vibrating plate  61  is transmitted to the main liquid chamber  41  through the through-hole  81  of the filtering plate  80 . 
         [0016]    Meanwhile, this vibration damping effect caused by the vibrating plate  61  is mainly used to reduce the high-frequency vibration of the engine. In the case of the low-frequency vibration of the engine, as in the ordinary liquid-filled engine mount apparatus, the vibration is reduced by inertial resistance of the working fluid flowing between the main and auxiliary liquid chambers  41  and  42  through the orifice section  50 . 
         [0017]    Accordingly, this electromagnetic active engine mount apparatus can reduce the vibration of the engine in both the high and low frequency ranges. However, from the viewpoint of its structure, when the vibrating plate  61  is repeatedly operated, heat is generated from the coil  71  of the solenoid  74 . Due to this heat generating phenomenon, various rubber components of the engine mount apparatus may be damaged by the heat. As a result, the engine mount apparatus cannot smoothly perform the function of reducing the vibration of the engine, and thus must be frequently replaced by periods. 
         [0018]    The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art. 
       BRIEF SUMMARY OF THE INVENTION 
       [0019]    Various aspects of the present invention are directed to provide an electromagnetic active engine mount apparatus, in which a sub-channel through which working fluid flows is formed in the central portion of an electromagnetic drive so as to be able to cool heat generated from the coil of a solenoid section of the electromagnetic drive by repetitive operation of a vibrating member, thereby inhibiting the heat generated from the coil to thus protect various components formed of rubber from thermal damage, and providing improvement of its durability, reduction of its size, and simplification of its structure. 
         [0020]    In an aspect of the present invention, the electromagnetic active engine mount apparatus may include a main rubber, into and to which a center bolt is inserted and coupled, a main pipe, one end of which is coupled to the main rubber, a diaphragm coupled to the other end of the main pipe, a damping chamber defined by coupling of the main rubber, main pipe and diaphragm so as to be air-tightly filled therein with a working fluid, and an orifice section and a vibrating member mounted in the damping chamber, the vibrating member being operated by an electromagnetic drive so as to generate vibration to reduce vibration of an engine, wherein the damping chamber is partitioned into an upper liquid chamber and a lower liquid chamber by the orifice section and vibrating member, wherein the lower liquid chamber is partitioned into first and second auxiliary liquid chambers by the electromagnetic drive, the first auxiliary liquid chamber being formed by the vibrating member and the electromagnetic drive and the second auxiliary liquid chamber being formed by the electromagnetic drive and the diaphragm, and wherein the electromagnetic drive includes a sub-channel passing along a central portion thereof such that the first and second auxiliary chambers communicate with each other. 
         [0021]    The electromagnetic drive may include a solenoid section generating an electromagnetic force, and an armature coupled with the vibrating member on one side thereof such that the vibrating member generates vibration, and moving up and down by means of the electromagnetic force of the solenoid section, the sub-channel vertically passes along the central portions of the solenoid section and armature. 
         [0022]    The solenoid section may include a coil wound in a ring shape, a yoke enclosing the coil, a core to and from which the armature is repeatedly attached and detached by the electromagnetic force, and a case enclosing the yoke and core, and the sub-channel passes through central portions of the core and case, wherein the yoke, core, and case are integrally formed by injection molding such that the working fluid does not flow into the case, wherein the case includes a sealing member in order to prevent the working fluid from flowing from the sub-channel to the yoke through a gap occurring when the armature is detached from the core, and wherein the sealing member is mounted on the case adjacent to the yoke and configured to and dimensioned to seal the core and the case such that the working fluid is filled in the gap. 
         [0023]    In another aspect of the present invention, the orifice section may include an orifice body in which an orifice channel is formed, and a disc-shaped orifice upper plate coupled to an upper surface of the orifice body and having at least one through hole in a central portion thereof, and the vibrating member is elastically coupled to the orifice body so as to be located on a lower side of the through-hole of the orifice upper plate, wherein the orifice body has a U-shaped vertical cross section where one side thereof is open and communicates between the upper damping chamber, the sub channel and the lower damping chamber. 
         [0024]    The methods and apparatuses of the present invention have other features and advantages which will be apparent from or are set forth in more detail in the accompanying drawings, which are incorporated herein, and the following Detailed Description of the Invention, which together serve to explain certain principles of the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0025]      FIG. 1  is a schematic cross-sectional view illustrating a conventional electromagnetic active engine mount apparatus. 
           [0026]      FIG. 2  is a schematic cross-sectional view illustrating the structure of an exemplary electromagnetic active engine mount apparatus according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0027]    Reference will now be made in detail to various embodiments of the present invention(s), examples of which are illustrated in the accompanying drawings and described below. While the invention(s) will be described in conjunction with exemplary embodiments, it will be understood that present description is not intended to limit the invention(s) to those exemplary embodiments. On the contrary, the invention(s) is/are intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the invention as defined by the appended claims. 
         [0028]      FIG. 2  is a schematic cross-sectional view illustrating the structure of an electromagnetic active engine mount apparatus according to various embodiments of the present invention. 
         [0029]    As illustrated in  FIG. 2 , the electromagnetic active engine mount apparatus includes a damping chamber  400  defined by coupling of a main rubber  100 , into and to which a center bolt  110  for coupling with an engine is inserted and coupled at a central portion thereof, a main pipe  200 , and a diaphragm  300 , and air-tightly filled therein with a working fluid. Here, the main rubber  100  is coupled to the main pipe  200 , particularly on an upper side of the main pipe  200 , by bonding such as curing bonding. The diaphragm  300  is coupled to the main pipe  200 , particularly on a lower side of the main pipe  200 . 
         [0030]    The damping chamber  400  is provided therein with an orifice section  500  and a vibrating member  600 , which partition the damping chamber  400  into an upper liquid chamber  410  and a lower liquid chamber  420 , as illustrated in  FIG. 2 . Further, an electromagnetic drive  700  is mounted on a lower side of the orifice section  500  in order to operate the vibrating member  600 . Here, the lower liquid chamber  420  is partitioned into two auxiliary liquid chambers by the electromagnetic drive  700 , i.e. a first auxiliary liquid chamber  421  located above the electromagnetic drive  700 , and a second auxiliary liquid chamber  422  located blow the electromagnetic drive  700 . 
         [0031]    Here, as illustrated in  FIG. 2 , a sub-channel  730  passing through the electromagnetic drive  700  is formed, as a linear channel, in the central portion of the electromagnetic drive  700 . 
         [0032]    Further, according to various embodiments of the present invention, the electromagnetic drive  700  includes a ring-shaped solenoid section  710  generating an electromagnetic force, and an armature  720  coupled with the vibrating member  600  on one side thereof such that the vibrating member  600  generates vibration, and moving up and down by means of the electromagnetic force of the solenoid section  710 . Here, the solenoid section  710  includes a coil  711  wound in a ring shape, a yoke  712  enclosing the coil  711 , a core  713  to and from which the armature  720  is repeatedly attached and detached by the electromagnetic force, and a case  714  enclosing the yoke  712  and core  713 . 
         [0033]    With this configuration, the sub-channel  730  passes through central portions of the solenoid section  710  and armature  720  in a vertical direction so as to function as a linear channel. At this time, the sub-channel  730  can be formed so as to pass through the core  713  and the case  714  of the solenoid section  710 . 
         [0034]    Meanwhile, according to various embodiments of the present invention, as illustrated in  FIG. 2 , the vibrating member  600  includes a vibrating plate  610  coupled with the armature  720 , and a vibrating rubber  620  adhered to the vibrating plate  610  at an inner end thereof and an orifice body  510  at an outer end thereof. 
         [0035]    With this configuration, the electromagnetic active engine mount apparatus reduces ordinary low-frequency-band vibration of the engine by means of inertial resistance of the working fluid flowing between the upper liquid chamber  410  and the lower liquid chamber  420  through the orifice section  500 , and high-frequency-band vibration of an engine by the electromagnetic drive  700  operating the vibrating member  600  so as to generate vibration whose waveform has the same phase as that of the vibration of the engine, thereby offsetting the vibration of the engine. At this time, the electromagnetic drive  700  is preferably configured to be controlled by a separate controller (not shown) such that the vibrating member  600  generates vibration so as to be suitable for a vibration state of the engine. Thus, the electromagnetic drive  700  can be controlled so as to reduce the vibration of the engine having the high frequency band as well as the low frequency band. 
         [0036]    Further, unlike a conventional electromagnetic active engine mount apparatus, the electromagnetic active engine mount apparatus according to various embodiments of the present invention is configured so that the coil  711  is cooled through the sub-channel  730  although heat is generated from the coil  711  of the solenoid section  710  of the electromagnetic drive  700  by the electric current supplied to the coil  711 . This is because the sub-channel through which the working fluid passes is formed in the central portion of the electromagnetic drive  700 . Thus, the sub-channel  730  may be formed around the solenoid section  710  in order to cool the coil  711 . However, according to various embodiments of the present invention, it is more excellent in the aspect of cooling efficiency to form the sub-channel  730  in the central portion of the electromagnetic drive  700 . In detail, since the heat generated from the coil  711  is partially cooled around the solenoid section  710  by the air, the generation of the heat becomes more serious at the central portion of the solenoid section  710 . As such, the sub-channel  730  is preferably formed in the central portion of the solenoid section  710 . Further, in the case in which the sub-channel  730  is formed in the central portion of the solenoid section  710 , the solenoid section  710  can reduce its size and weight compared to the case in which the sub-channel  730  is formed around the solenoid section  710 . 
         [0037]    Meanwhile, as illustrated in  FIG. 2 , the electromagnetic drive  700  is configured so that a gap “X” occurs when the armature  720  is detached from the core  713 . In order to prevent the working fluid from flowing from the sub-channel  730  to the yoke  712  through this gap “X,” a separate sealing member  800  is preferably mounted on the case  714  at one end of the gap “X.” Thereby, the coil  711  can be prevented from causing a short circuit due to inflow of the working fluid. Further, the sealing member  800  is preferably mounted on the case  714  adjacent to the yoke  712  as illustrated in  FIG. 2 . Thus, the working fluid is filled in the gap “X” through the sub-channel  730 . This filling of the working fluid can remarkably reduce noise generated by mutual contact when the armature  720  is repeatedly attached to and detached from the core  713 . 
         [0038]    Alternatively, the yoke  712 , core  713 , and case  714  may be integrally formed by injection molding without this separate sealing member  800  such that the working fluid does not flow into the case  714 . 
         [0039]    Further, according to various embodiments of the present invention, the orifice section  500  includes a ring-shaped orifice body  510  in which an orifice channel  511  is formed, and a disc-shaped orifice upper plate  520  coupled to an upper surface of the orifice body  510  and having at least one through hole  521  in a central portion thereof. Here, the vibrating member  600  is preferably located on a lower side of the through-hole  521  of the orifice upper plate  520 . Further, the orifice section  500  is preferably configured so that the orifice body  510  has a U-shaped vertical cross section where one side thereof is open, and that the orifice upper plate  520  is coupled to the open upper surface of the orifice body  510 , thereby defining the orifice channel  511  therein. 
         [0040]    In detail, the orifice upper plate  520  is designed to constitute the orifice section  500 , and simultaneously function as a filtering plate (see the reference numeral  80  of  FIG. 1 ) filtering the vibration generated by the vibrating member  600  so as to be transmitted to the upper liquid chamber  410  through the through-hole  521 , as described above. 
         [0041]    Further, the orifice body  510  is formed of aluminum by die casting so as to be easily formed in a simple shape. 
         [0042]    For convenience in explanation and accurate definition in the appended claims, the terms “upper” and “lower” are used to describe features of the exemplary embodiments with reference to the positions of such features as displayed in the figures. 
         [0043]    The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teachings. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and their practical application, to thereby enable others skilled in the art to make and utilize various exemplary embodiments of the present invention, as well as various alternatives and modifications thereof. It is intended that the scope of the invention be defined by the Claims appended hereto and their equivalents.
An electromagnetic active engine mount apparatus includes a sub-channel through which working fluid flows is formed in the central portion of an electromagnetic drive so as to be able to cool heat generated from the coil of a solenoid section of the electromagnetic drive by repetitive operation of a vibrating member. Thus, the electromagnetic active engine mount apparatus can inhibit the heat generated from the coil to thus prevent thermal damage to various components formed of rubber, and provide improvement of its durability, reduction of its size, and simplification of its structure.