Patent Publication Number: US-6702251-B2

Title: Control valve in variable displacement compressor and method of manufacturing the same

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a displacement control valve controlling the discharge capacity of variable displacement compressors that are included in the refrigerant circuit of air conditioners. 
     A typical control valve incorporates a solenoid valve, which is externally controllable. FIG. 4 shows an example of an electromagnetic actuator portion  101  in the control valve. A retainer cylinder  102  having a bottom portion is disposed in the electromagnetic actuator portion  101 . A stationary core  103  and a movable core (plunger)  104  are disposed in the retainer cylinder  102 . A coil  105  is disposed at outside of the retainer cylinder  102 . Electric current through the coil  105  generates electromagnetic force between stationary core  103  and movable core  104 . The electromagnetic force is applied to the movable core  104  to slide along an inner cylindrical surface of the retainer cylinder  102 . This movement is transmitted to a valve body (not shown in the drawing) through a rod  106 . The displacement of valve body based on the movable core  104  serves to adjust the opening degree of the valve to control a discharge displacement of the compressor. 
     The discharge displacement is achieved by, for example, changing a pressure in a crank chamber in which a swash plate is disposed. To change the pressure in the crank chamber, the control valve regulates the degree of the opening in a pressurizing passage, which supplies a pressurized refrigerant gas from the discharge chamber to the crank chamber. 
     Recently, air conditioners utilizing carbon dioxide as a refrigerant gas has become generally used. In such system, the pressure of the refrigerant gas is much higher than that of a conventional CFC (chlorofluorocarbon) gas. Accordingly, in order to control the displacement of the compressor that deal with carbon dioxide, it is necessary to increase the withstanding pressure of the control valve as well as the compressor. For example, a cylindrical wall of the retainer cylinder  102  may be thick to resist the internal pressure. 
     However, the retainer cylinder  102  is made of non-magnetic material to prevent magnetic flux from leaking out between the stationary core  103  and the movable core  104 . Therefore, if the wall of the retainer cylinder  102  is thickened to resist the high internal pressure sufficiently, it will be harder for the magnetic flux to go through between the coil  105  and the movable core  104 . 
     SUMMARY OF THE INVENTION 
     Accordingly, an object of the present invention is to provide a control valve, especially control valve in variable displacement compressor, in which a magnetic flux can easily go through between a coil and movable core even if a wall of the retainer cylinder is thickened in order to increase its withstanding pressure. 
     Another objective of the present invention is a method of adjusting the tolerance of the movable extent in the control valve, which is caused during its manufacture. 
     To achieve the foregoing, the present invention provides a control valve for operating fluid flow that goes through the control valve. The control valve includes a retainer cylinder, a stationary core, a movable core, a shim, a coil and a valve body. The retainer cylinder includes a first cylindrical member made of non-magnetic material and a second cylindrical member made of magnetic material, the second cylindrical member having a bottom portion. The stationary core is disposed in the retainer cylinder. The movable core is disposed in the retainer cylinder, and located between the stationary core and the bottom portion of the second cylindrical member. The shim is made of non-magnetic material, and disposed in the retainer cylinder and located between the movable core and the bottom portion of second cylindrical member. The coil is disposed around the retainer cylinder. The valve body is movably linked with the movable core. The valve body is actuated by a movement of the movable core in an elongated direction of the retainer cylinder. The movement of the movable core is based on an electromagnetic force that is generated between the stationary core and the movable core in accordance with an electric current supplied to the coil. 
     The control valve is appropriate for a variable displacement compressor that adjusts the discharge displacement in accordance with the inclination of a drive plate located in a crank chamber. 
     Also, the present invention provides a method of adjusting the amount of movable extent of a movable core in a control valve for operating fluid flow that goes through the control valve including a step of adjusting a thickness of the shim so that the amount of movable extent of the movable core in the retainer cylinder is adjusted. 
     Regarding the description of the invention, the term of “bottom” refers to a relative location with respect to the other structural elements described below, and is illustrated, by way of example, in FIG.  2 . Therefore, if the control valve of the invention is installed in practical use “upside down” with respect to the orientation depicted in FIGS. 1-3, the term “bottom” should mean the reverse as 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention, together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawing in which: 
     FIG. 1 is a cross-sectional view of a variable displacement type of swash plate compressor according to one embodiment of the present invention; 
     FIG. 2 is a cross-sectional view of a control valve; 
     FIG. 3 is an enlarged partial cross-sectional view of the control valve of FIG. 2; and 
     FIG. 4 is an enlarged partial cross sectional view of a prior art control valve. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A control valve for a variable displacement compressor according to an embodiment of the present invention will now be described. 
     As shown in FIG. 1, a housing  11  of a variable displacement type swash plate compressor (hereinafter, compressor) defines a crank chamber  12  by an inner wall of the housing  11 . A drive shaft  13  is rotatably supported in the housing  11 . The drive shaft  13  is connected to an engine E as a power source of a vehicle, so that the engine E rotatably drives the drive shaft  13 . 
     In the crank chamber  12 , a lug plate  14  is fixed to the drive shaft  13  in order to rotate integrally with drive shaft  13 . A swash plate  15 , which serves as a cam plate, is disposed in the crank chamber  12 . The swash plate  15  is supported by the drive shaft  13 , to be slidable along and inclinable with respect to the axis of drive shaft  13 . A hinge mechanism  16  is intervened between the lug plate  14  and the swash plate  15 . Accordingly, the hinge mechanism  16  enables the swash plate  15  to rotate integrally with drive shaft  13  and to vary its inclination with respect to the axis of the drive shaft  13 . 
     Cylinder bores  11   a  are formed in the housing  11  (in FIG. 1, only one cylinder bore is shown). A single-headed piston  17  is accommodated in the each cylinder bore  11   a . Each piston  17  is coupled to the periphery of the swash plate  15  through shoes  18 . Rotation of the drive shaft  13  is converted into reciprocation of the pistons  17  through the lug plate  14 , the hinge mechanism  16 , the swash plate  15  and the shoes  18 . 
     At a rear side of the cylinder bores  11   a  (right side of FIG.  1 ), compression chambers  20  are defined by pistons  17  and valve-port assembly  19  that is disposed in the housing  11 . Suction ports  23 , suction valves  24 , discharge ports  25  and discharge valves  26  are formed in the valve-port assembly  19 . At the rear side in the housing  11 , a suction chamber  21 , which is a suction pressure zone, and a discharge chamber  22 , which is a discharge pressure zone, are individually formed. 
     The movement of each piston  17  from the top dead center to the bottom dead center draws refrigerant gas to the corresponding compression chamber  20  through the corresponding suction port  23  and suction valve  24  in the valve-port assembly  19 . The movement of each piston  17  from the bottom dead center to the top dead center compresses refrigerant gas in the corresponding compression chamber  20  to a predetermined pressure and discharges the refrigerant gas to the discharge chamber  22  through the discharge port  25  and discharge valve  26 . 
     The variable displacement mechanism will now be described. 
     As shown in FIG. 1, a bleed passage  27  and a pressurizing passage  28  are respectively disposed in the housing  11 . The bleed passage  27  continuously connects the crank chamber  12  to the suction chamber  21 . The pressurizing passage  28  connects the discharge chamber  22  to the crank chamber  12 . A control valve CV is located in the pressurizing passage in the housing  11 . 
     The control valve CV adjusts the degree of the valve opening in order to control the flow of the high-pressured refrigerant gas through the pressurizing passage  28  from the discharge chamber  22  to the crank chamber  12 . The bleed passage  27  releases the refrigerant gas from the crank chamber  12  to the suction chamber  21 . Therefore, the pressure in the crank chamber  12  is controlled by the balance of the rate of inflow and the rate of outflow of refrigerant gas in crank chamber  12 . The pressure in the crank chamber  12  is applied to the front side of the piston, and the pressure in the compression chambers  20  is applied to piston heads, respectively. Accordingly, the variation of the pressure balance varies the inclination of the swash plate  15 . This varies the stroke of the pistons  17  and the displacement as well. 
     For example, when the pressure in the crank chamber  12  decreases, the inclination of the swash plate  15  increases in order to increase the displacement of the compressor. Contrary, when the pressure in the crank chamber  12  increases, the inclination of the swash plate  15  decreases in order to decrease the displacement of the compressor. 
     A refrigerant circuit will be now described. 
     As shown in FIG. 1, the refrigerant circuit for the air conditioner of the vehicle comprises the compressor and an external refrigerant circuit  30 . The external refrigerant circuit  30  includes a condenser  31 , an expansion valve  32 , and an evaporator  33 . Carbon dioxide is provided as refrigerant gas in the refrigerant circuit  30 . 
     A first pressure detection point P 1  is located in the discharge chamber  22 . A second pressure detection point P 2  is located in a refrigerant passage, which is predetermined distance downstream (the evaporator  31  side) from the first pressure detection point P 1 . As shown in FIG. 2, the first pressure detection point P 1  is connected to the control valve CV through a first pressure introduction passage  35 . The second pressure detection point P 2  is connected to the control valve CV through a second pressure introduction passage  36 . 
     The valve opening control and pressure detecting structure in the control valve will be now described. 
     As shown in FIG. 2, a valve housing  41  of the control valve CV defines a valve chamber  42 , a communication passage  43  and a pressure sensing chamber  44 . In the valve chamber  42  and the communication passage  43 , a rod  45  is disposed for reciprocation in the axial direction (the vertical direction in FIG.  2 ). The communication passage  43  is isolated from the pressure sensing chamber  44  by the upper end portion of the rod  45  that blocks the upper communication passage  43 . The valve chamber  42  is connected to the discharge chamber  22  through the upstream pressurizing passage  28 . The communication passage  43  is connected to the crank chamber  12  through the downstream pressurizing passage  28 . The valve chamber  42  and the communication passage  43  comprise a part of the pressurizing passage  28  as well. 
     A valve body portion  46 , which is formed in the middle of rod  45 , is disposed in the valve chamber  42 . A step, which is located at a border between the valve chamber  42  and the communication passage  43 , is formed as a valve seat  47 . The communication passage  43  functions as a valve hole. Accordingly, the rod  45  is lifted up from the position as shown in FIG. 2 (bottom position) to a top position of which the valve body portion  46  is seated on the valve seat  47 , then the communication passage  43  is shut down. Namely, the valve body portion  46  functions as a valve body to adjust the degree of the valve opening in the pressurizing passage  28 . 
     A pressure sensing member  48  including a bellows is accommodated in the pressure sensing chamber  44 . The top end of the pressure sensing member  48  is fixed on the valve housing  41 . The bottom end of the pressure sensing member  48  is fitted on the top end of the rod  45 . In the pressure sensing chamber  44 , the pressure sensing member  48  divides into two separate chambers. One is a first pressure chamber  49  that is the inside of the pressure sensing member  48 , and another is a second pressure chamber  50  that is the outside of the pressure sensing member  48  pressure PdH at the pressure detection point P 1  is conducted into the first pressure chamber  49  through the first pressure introduction passage  35 . A pressure PdL at the pressure detection point P 2  is conducted into the second pressure chamber  50  through the second introduction passage  36 . 
     An electromagnetic actuator portion  51  in the control valve will now described. 
     As shown in FIG. 3, the electromagnetic actuator portion  51  is located at the bottom of the valve housing  41 . In the electromagnetic actuator portion  51 , a retainer cylinder  52  having a bottom portion is disposed at the center portion of the valve housing  41 . A center post  53 , which serves as a stationary core, is made of magnetic material (such as alloy with an iron base), and fitted on the opening top of the retainer cylinder  52 . A plunger chamber  54  is defined in the retainer cylinder  52  by fitting the center post  53  on the retainer cylinder  52 . The center post  53 , therefore, serves as a separator of the valve chamber  42  and the plunger chamber  54 , as well. 
     A plate  55  is attached at a bottom-opening end in the valve housing  41 . The plate  55  is formed in a ring-shape and is made of magnetic material. The inner circumference of the plate  55  is bent upward to form a cylindrical portion  55   a . The plate  55  with the cylindrical portion  55   a  is fitted on the periphery of the retainer cylinder  52  so that the plate  55  block up an annular opening that exists between the bottom portion of the retainer cylinder  52  and the bottom of the valve housing  41 . 
     A plunger  56 , which serves as a movable core, is formed in a cylindrical shape and is made of magnetic material. The plunger  56  is accommodated in the plunger chamber  54  so that the plunger may move in the axial direction of the retainer cylinder  52 . The movement of the plunger  56  is slidably guided by the inner surface of the retainer cylinder  52 . A guide hole  57  is bored through the center of the center post  53 . The bottom portion of the rod  45  is disposed in the guide hole  57  so that the rod  45  may move in the axial direction of the rod  45 . The bottom end of the rod  45  contacts the top surface of the plunger  56  in the plunger chamber  54 . 
     A projection portion  53   a  is annularly projected on the periphery of the bottom end of the center post  53  around the center axis of the valve housing  41 . The projection portion  53   a  is downwardly tapered away to the plunger  56 . A peripheral edge portion  56   b  is chamfered off from the edge of the plunger  56 , in order to avoid the projection portion  53   a  and be faced along the inclined surface of the projection portion  53   a . According to the structure, an electromagnetic attraction (See the following details), which is generated between the center post  53  and the plunger  56 , has a linear characteristic with respect to the distance therebetween. 
     A spring  60  is accommodated between the bottom portion of the retainer cylinder  52  and the plunger  56  in the plunger chamber  54 . The spring  60  urges the plunger toward the rod  45 . The rod  45  is also urged by elastic character of the pressure sensing member  48  (hereinafter, a bellows spring  48 ) toward the plunger  56 . Accordingly, the plunger  56  and the rod  45  are always moved up and down together. The urging elastic force of the bellows spring  48  is set to be greater than that of the spring  60 . 
     The valve chamber  42  and the plunger chamber  54  are connected to each other through a space between the guide hole  57  and the rod  45 . Therefore, the discharge pressure of the refrigerant gas is supplied into both the valve chamber  42  and the plunger chamber  54 . It is generally known that a characteristic to control the valve is improved by supplying the same gas pressure into both the valve chamber  42  and the plunger chamber  54 . 
     The retainer cylinder  52  includes a first cylindrical member  58 , which is formed in a hollow shape and is made of non-magnetic material (such as non-magnetic stainless material), and a second cylindrical member  59  having a bottom portion, which is made of magnetic material. The entire second cylindrical member  59  including the side cylindrical portion as well as the bottom portion is made of non-magnetic material, in order to be easy to manufacture it. 
     The first cylindrical member  58  is disposed for surrounding the center post  53  and the plunger  56 . The bottom-opening end of the first cylindrical member  58  is thinner than the other part (a large diameter portion  58   a ) and the bottom-opening end comprises a small diameter portion  58   b . The second cylindrical member  59  is fitted with the outer surface of the small diameter portion  58   b  of the first cylindrical member  58 . The outer cylindrical surface of the second cylindrical member  59  has almost the same diameter as the large diameter portion  58   a  of the first cylindrical member  58 . 
     A shim  65  is located between a bottom surface  56   a  of the plunger  56  and an inner bottom surface  59   a  of the second cylindrical member  59  in the plunger chamber  54 . The shim  65  is formed in a ring plate shape and is made of non-magnetic material. During the assembly of the control valve CV, a number of shims  65  having various thickness are provided so that the particular shim may be selected to correct an unevenness of the control valve CV. In the other words, providing the various thickness of the shims  65  is for adjusting the tolerance of movable extent of the plunger  56 , even if the tolerance of each part or assembling each part in the control valve CV is added to increase the unevenness. The thickness of the shim  65  is greater than the thickness of the small diameter portion  58   b  of the first cylindrical member  58 . 
     The inner circumference of the shim  65  is intervened between the inner bottom surface  59   a  and spring  60  so that the shim  65  serves as a spring seat as well. According to such structure, the spring  60  urges the shim  65  toward the inner bottom surface  59   a . The shim  65  is, therefore, stably located in the plunger chamber  54  without fixing the shim  65  on the bottom surface of the plunger  56  or on the inner bottom surface  59   a  of the second cylindrical member  59 . Further, regarding the present invention, the shim  65  may be fixed on the bottom surface of the plunger  56  or on the inner bottom surface  59   a  of the second cylindrical member  59 . 
     A coil  61  is wound or disposed around the retainer cylinder  52  along a length thereof that surrounds portions of the center post  53  and the plunger  56 . The coil  61  receives a electric current from a drive circuit  71  based on a signal from a control device  70  (such as computer) that receives external signals from an external sensing means  72 , such as an On/Off signal of air-conditioner switch, an actual temperature in the passenger compartment, target temperature set by a adjuster, etc. 
     According to the electric current from the control device  70 , magnetic flux is generated around the coil  61 . The magnetic flux goes from the coil  61  through the plate  55  or the second cylindrical member  59  to the small diameter portion  58   b  of the first cylindrical member  58  and the plunger  56 , and further, it goes through the plunger  56  to the center post  53 . The electromagnetic force (electromagnetic attraction), which is corresponds to the amount of electric current flowing to the coil  61 , is generated between the plunger  56  and the center post  53 . This force is transmitted from the plunger to the rod  45 . The electric current is controlled by an adjustment of the voltage to the coil  61 . For the adjustment of the voltage, a PWM (pulse-width modulation) control is applied to the drive circuit  71 . 
     An operating characteristic of the control valve CV will be now described. Regarding the illustrated control valve CV, the position of the rod  45  decides the valve opening degree of the valve body portion  46  as follows; 
     First, as shown in FIG. 2, the position of the rod  45  is determined by the downward force of the bellows spring  48  when no electric current is supplied to the coil  61  (duty of PWM=0%). Accordingly, the rod  45  is located at a bottom position in order to fully open the valve body portion  46  in the communication passage  43 . The pressure in the crank chamber  12  is therefore to be a maximum under the condition. A differential pressure between the crank chamber  12  and the compression chamber  20  through the piston  17  is, therefore, a maximum under this condition. Consequently, the inclination angle of the swash plate  15  is at the maximum and the displacement of the compressor will be the minimum. 
     Next, when the current with a minimum duty (&gt;0%) in the variable duty range is supplied to the coil  61 , the electromagnetic force is generated and added upward to the urging force of the spring  60 . When the added upward force exceeds the downward force of the bellows spring  48 , the rod  45  moves upward. In this situation, the upward force, which comprises the electromagnetic force added to the urging force of the spring  60 , is opposed by the downward force, which comprises the force resulting from the differential pressure ΔPd (=PdH-PdL) added to the downward force of the bellows spring  48 . The valve body portion  46  with the rod  45  is positioned at the location where the forces applied to the rod  45  are equilibrated. 
     For example, if the amount of the refrigerant gas flow decreases based on a decrease of the engine E speed, the downward force of the differential pressure ΔPd decreases. Due to this change, the forces applied to the rod  45  lose their equilibrium. Accordingly, the rod  45  with the valve body portion  46  is lifted up to reduce the opening in the communication passage  43  so that the pressure in the crank chamber  12  decreases. The inclination angle of the swash plate  15  is increased to increase the displacement of the compressor. Consequently, the amount of the refrigerant gas flow in the refrigerant circuit  30  increases based on the larger displacement of the compressor, and the differential pressure ΔPd increases. 
     Contrary, if the amount of the refrigerant gas flow increases based on an increase of the engine E speed, the downward force resulting from the differential pressure ΔPd increases. Due to the change, the forces applied to the rod  45  lose their equilibrium. Accordingly, the rod  45  with the valve body portion  46  is lowered to enlarge the opening in the communication passage  43  so that the pressure in the crank chamber  12  increases. The inclination angle of the swash plate  15  is decreased to decrease the displacement of the compressor. Consequently, the amount of refrigerant gas flow in the refrigerant circuit  30  decreases based on the smaller displacement of the compressor, and the differential pressure ΔPd decreases. 
     Further to above, when the current duty to the coil  61  increases in order to increase the magnitude of the upward electromagnetic force, the forces applied to the rod  45  lose their equilibrium. Accordingly, the rod  45  with the valve body portion  46  is lifted up to reduce the opening in the communication passage  43  so that the displacement of the compressor increases. Consequently, the amount of refrigerant gas flow increases based on the larger displacement of the compressor, and the differential pressure ΔPd increases. 
     Contrary, when the current duty to the coil  61  decreases in order to decrease the magnitude of the upward electromagnetic force, the forces applied to the rod  45  lose their equilibrium. Accordingly, the rod  45  with the valve body portion  46  is lowered to enlarge the opening in the communication passage  43  so that the displacement of the compressor decreases. Consequently, the amount of refrigerant gas flow decreases based on the smaller displacement of the compressor, and the differential pressure ΔPd decreases. 
     In other words, the control valve CV has the structure that the rod  45  is automatically positioned based on the actual differential pressure ΔPd in order to maintain the differential pressure ΔPd at the control target (target differential pressure) that is determined by the electric current duty into the coil  61 . The target differential pressure is externally variable by adjusting the current duty to the coil  61 . 
     By the way, in the illustrated embodiment, the language of “bottom” describes the relative location with respect to the other structural elements the illustrated in FIG.  2 . If the control valve or the compressor is installed in practical use upside down, the term “bottom” should mean the reverse as “top”. The other words such as the “top”, “up”, “upward”, “down” and “downward” should mean the reverse as well. 
     The illustrated embodiment has the following advantage. 
     (1) The retainer cylinder  52  includes the first cylindrical member  58  made of non-magnetic material and a second cylindrical member  59  having a bottom portion that is made of magnetic material. Accordingly, the magnetic permeability between the coil  61  and the plunger  56  is improved, even though the retainer cylinder  52  may be thickened to improve its withstanding pressure to the internal refrigerant gases such as the carbon dioxide. 
     (2) The shim  65 , which is formed from non-magnetic material, is intervened between the bottom surface  56   a  of the plunger  56  and inner bottom surface  59   a  of the second cylindrical member  59 . Therefore, the non-magnetic gap, which is formed by non-magnetic material of the shim  65 , is secured between the magnetic material of the second cylindrical member  59  and the plunger  56 , even though the plunger  56  is located at the lowest position. It enables to suppress the downward electromagnetic attraction between the bottom surface  56   a  of the plunger  56  and the inner bottom surface  59   a  of the second cylindrical member  59 . Because the shim  65  is non-magnetic, there is a little downward electromagnetic attraction that would offset the upward electromagnetic force acting on the plunger  56  and the rod  45  from the coil  61 . Furthermore, the upward electromagnetic force is conventionally controlled by the chamfered peripheral edge portion  56   b  of the plunger  56  in order to obtain the linear characteristic of the upward electromagnetic force to the distance between the center post  53  and the plunger  56 . However, the downward electromagnetic attraction between the bottom surface  56   a  and the inner bottom surface  59   a  is extremely strong where the bottom surface  56   a  approaches the inner bottom surface  59   a , on condition that there is no gap between them. According to the illustrated embodiment, the shim  65  secures the non-magnetic gap to suppress the downward electromagnetic attraction between the bottom surface  56   a  of the plunger  56  and the inner bottom surface  59   a  of the second cylindrical member  59 . The external controllability of the control valve CV is, therefore, improved so that the control of the displacement of the compressor may be more accurate. 
     (3) The first cylindrical member  58  is disposed for directly surrounding the plunger  56 , and the second cylindrical member  59  is disposed for surrounding the small diameter portion  58   b  of the first cylindrical member  58 . During the operation, the plunger  56  is guided to slide on the inner cylindrical wall of the first cylindrical member  58  that is made of non-magnetic material. Generally, magnetic material tends not to slide well on other magnetic materials. Therefore, the illustrated embodiment has the advantage of the slidablity of the plunger  56  on the inner wall of the first cylindrical member  58 . Further to above, the inner cylindrical wall of the first cylindrical member  58  covers the full extent of the plunger&#39;s range of movement in order to slidably guide the plunger  56 . Accordingly, the sliding resistance between the plunger  56  and the retainer cylinder  52  is decreased. This structure suppresses the hysteresis characteristics, which appears in the degree of the control valve opening in accordance with the current duty rate into the coil  61 . 
     (4) Regarding the first cylindrical member  58  made of non-magnetic material, the portion in the vicinity of the plunger  56  (small diameter portion  58   b ) is thinned. Therefore, the magnetic permeability between the coil  61  and plunger  56  is improved so that even a small coil  61  may generate sufficient electromagnetic force to actuate the plunger  56 . This serves to miniaturize the electromagnetic actuator portion  51  as well as the control valve CV. 
     (5) The second cylindrical member  59  is fixed to the outer surface of the small diameter portion  58   b  of the first cylindrical member  58 . The second cylindrical member  59  serves to reinforce the small diameter portion  58   b . The retainer cylinder  52 , therefore, maintains the strengths even though the wall of the first cylindrical member  58  is thinned. According to this structure, the withstanding pressure is improved so that the hi-pressured carbon dioxide may be applied as the refrigerant gas. As well, it is easier to introduce the hi-pressured discharge gas into the plunger chamber  54 . 
     (6) The non-magnetic shim  65  serves as the adjustment member for adjusting the tolerance of the movable extent of the plunger  56 . Accordingly, the illustrated method corrects the unevenness of the movable extent of the plunger  56  in connection with an unevenness of the valve opening control. 
     The present invention can further be embodied, for example, in; 
     a control valve that is not disposed in the pressurizing passage  28 , but in the bleed passage  27  to control the pressure in the crank chamber  12 . This type is generally called a bleeding control valve. 
     the other type of electromagnetic control valves, such as the valve is operated by only electromagnetic power without any pressure sensing mechanism (pressure sensing member  48 ). 
     a control valve for controlling a wobble type compressor. 
     Therefore, the present examples and embodiments are to be considered as illustrative and not restrictive and the invention is not to be limited to the details given herein but may be modified within the scope of the appended claims.