Patent Application
20070183904
The present invention relates to a displacement control valve of a clutchless variable displacement inclined plate-type compressor which is connected directly to a drive source without using a clutch.
Patent Document 1 discloses a displacement control valve of a clutchless variable displacement inclined plate-type compressor for controlling a discharge displacement of the compressor by opening and closing a valve hole formed in a communication path between a discharge chamber and a crank chamber of the compressor, the displacement control valve including the valve hole always communicating with the crank chamber, an inside control valve for opening and closing the valve hole by a valve body operated in response to expansion and contraction of a pressure sensing member for sensing a suction pressure, and an electromagnetic solenoid connected to the inside control valve for switching the inside control valve between an operating condition where the valve body opens and closes the valve hole in response to the expansion and contraction of the pressure sensing member and a non-operating condition where the valve body opens the valve hole independently of the expansion and contraction of the pressure sensing member, and the displacement control valve controls the discharge displacement so that a suction pressure and a discharge pressure have a predetermined correlation. This Patent Document 1 describes that the displacement control property is expressed by the following equation in a region of Pd>Pd0.
Ps=P0−(Pd−Pc)S1/S2
Where,
However, there are the following problems in the displacement control valve disclosed in the above-described Patent Document 1.
Because the discharge pressure Pd urges the valve body in a direction of valve closing, in order to forcibly open the valve body by degaussing of the electromagnetic solenoid, it is necessary to set the force of a releasing spring of the electromagnetic solenoid at a value of (Pd-31 Ps)S1 or more. In order to forcibly open the valve body in a region with a high discharge pressure Pd, it is necessary to use a releasing spring with a great spring force, and it is necessary to generate a great electromagnetic force for exciting the electromagnetic solenoid and attracting a movable core against the spring force of the releasing spring, and whereby, the electromagnetic solenoid becomes large.
Accordingly, paying attention to the above-described problems, an object of the present invention is to provide a displacement control valve of a clutchless variable displacement inclined plate-type compressor, which can be made smaller than the displacement control valve disclosed in Patent Document 1.
To achieve the above-described object, a displacement control valve of a clutchless variable displacement inclined plate-type compressor according to the present invention is provided as a displacement control valve for controlling a discharge displacement of the compressor by opening and closing a communication path between a discharge chamber and a crank chamber of the compressor. The displacement control valve comprises a valve hole formed in the communication path and always communicating with the discharge chamber, an inside control valve for opening and closing the valve hole by a valve body operated in response to expansion and contraction of a pressure sensing member for sensing a suction pressure, and an operation switching device connected to the inside control valve for switching the inside control valve between an operating condition where the valve body opens and closes the valve hole in response to the expansion and contraction of the pressure sensing member and a non-operating condition where the valve body opens the valve hole independently of the expansion and contraction of the pressure sensing member.
In the present invention, because the valve hole is always communicated with the discharge chamber, the force for urging the valve body in a valve opening direction by a discharge pressure Pd can be decreased as compared with that in the displacement control valve disclosed in the aforementioned Patent Document 1, and the switching device for forcibly opening the valve body may be made smaller.
In such a displacement control valve according to the present invention, a structure is preferably employed wherein the above-described operation switching device has an electromagnetic solenoid, when the electromagnetic solenoid is excited, the inside control valve becomes the operating condition, and when the electromagnetic solenoid is degaussed, the inside control valve becomes the non-operating condition. In such a structure, because the variable displacement inclined plate-type compressor can be switched to between a displacement control condition and a minimum displacement condition by exciting/degaussing the electromagnetic solenoid, the control unit for the variable displacement inclined plate-type compressor may be simplified.
Further, in the displacement control valve according to the present invention, it is preferred that the electromagnetic solenoid includes a movable core connected to the inside control valve and a positioning member for positioning the inside control valve at an operating position when the electromagnetic solenoid is excited. By providing such a positioning member, it becomes possible to position the inside control valve at an operating position by exciting the electromagnetic solenoid, and the switching of the variable displacement inclined plate-type compressor to its operating condition becomes possible by the excitation of the electromagnetic solenoid.
Further, in the displacement control valve according to the present invention, it is preferred that the positioning member is formed by one end of the pressure sensing member and an end surface of a case of the electromagnetic solenoid. By forming the positioning member with one end of the pressure sensing member and the case of the electromagnetic solenoid, it is not necessary to dispose a particular positioning member separately, and the structure of the displacement control valve may be simplified.
Further, in the displacement control valve according to the present invention, it is preferred that the electromagnetic solenoid includes a releasing spring for urging a movable core in a direction apart from a fixed core, and when the electromagnetic solenoid is degaussed, the inside control valve becomes the non-operating condition by the releasing spring. Because the releasing spring of the electromagnetic solenoid can turn the inside control valve into the non-operating condition, it is not necessary to provide a spring separately for turning the inside control valve into the non-operating condition, and the structure of the displacement control valve may be simplified.
Further, in a preferred embodiment of the present invention, the inside control valve includes a pressure sensing rod which is slidably inserted into a hole formed in a valve housing and communicating with the valve hole and which is connected to the valve body, and a cross-sectional area of the pressure sensing rod is set greater than a cross-sectional area of the valve hole. In such a structure, because a control property is realized wherein the suction pressure decreases when the discharge pressure increases, the discharge displacement increases in a high thermal-load region with a high discharge pressure. Therefore, a cooler comprising a variable displacement inclined plate-type compressor with this displacement control valve does not deteriorate in cooling performance even in a high thermal-load region with a high discharge pressure.
Alternatively, in another preferred embodiment of the present invention, the inside control valve includes a pressure sensing rod which is slidably inserted into a hole formed in a valve housing and communicating with the valve hole and which is connected to the valve body, and a cross-sectional area of the pressure sensing rod is set smaller than a cross-sectional area of the valve hole. In such a structure, because a control property is realized wherein the suction pressure increases when the discharge pressure increases, the discharge displacement decreases in a region of a high discharge pressure. As a result, occurrence of a condition, in which the compressor operates at an excessive load, may be prevented.
In the displacement control valve of a clutchless variable displacement inclined plate-type compressor according to the present invention, because the valve hole is always communicated with the discharge chamber, the force for urging the valve body in a valve opening direction by a discharge pressure can be decreased as compared with that in the displacement control valve disclosed in the aforementioned Patent Document 1, and the switching device for forcibly opening the valve body may be made smaller than that in the displacement control valve of Patent Document 1. Therefore, the displacement control valve of a clutchless variable displacement inclined plate-type compressor according to the present invention can be made smaller than the displacement control valve of Patent Document 1.
Hereinafter, desirable embodiments of a displacement control valve of a clutchless variable displacement inclined plate-type compressor according to the present invention will be explained referring to figures.
A crank chamber 17 containing main shaft 10, rotor 11 and inclined plate 12 is formed by cylinder block 16 and a dish-like front housing 18. Main shaft 10 extends to outside through front housing 18. A shaft seal member 19 is disposed for sealing the through portion of main shaft 10 in front housing 18. A pulley 20 is fixed at a tip portion of main shaft 10. In a case where variable displacement inclined plate-type compressor 1 is a compressor used for a refrigeration cycle of an air conditioning system for vehicles, pulley 20 is connected, for example, to an engine of a vehicle (not shown) via a belt (not shown).
A cylinder head 23 forming a suction chamber 21 and a discharge chamber 22 is disposed at a position on a side of cylinder block 16 opposite to the side of front housing 18. Suction chamber 21 is connected to an evaporator (not shown), which is provided in an external circuit, for example, a refrigeration cycle of an air conditioning system for vehicles, via a suction port (not shown). Discharge chamber 22 is connected to a condenser (not shown), which is provided in an external circuit, for example, a refrigeration cycle of an air conditioning system for vehicles, via a discharge port (not shown).
A valve plate 24 formed with suction hole 21a and discharge hole 22a communicating with cylinder bore 16a is provided between cylinder block 16 and cylinder head 23. A discharge valve and a suction valve (not shown) are attached to the valve plate 24. Crank chamber 17 and suction chamber 21 are communicated with each other via an orifice hole 24a formed on valve plate 24.
Front housing 18, cylinder block 16, valve plate 24 and cylinder head 23 are integrally fastened by a plurality of through bolts 25 disposed at intervals along the circumference with a center of main shaft 10.
A displacement control valve 2 for controlling the discharge displacement of variable displacement inclined plate-type compressor 1 is fitted into and fixed in a concave portion 26 which is formed in cylinder head 23 at a position adjacent to discharge chamber 22. As shown in
Inside control valve 100 has a cylindrical valve housing 101. Three closed spaces 27a, 27b and 27c are defined around valve housing 101 by two O-rings 101a and 101b tightly fitted onto the periphery of valve housing 101 and one O-ring 121a tightly fitted onto the periphery of a case 121 of electromagnetic solenoid 120.
In valve housing 101, a lateral partition wall 104 is formed for dividing the inside space of valve housing 101 into a pressure sensing chamber 102 on one end side and a valve chamber 103 on the other end side. On lateral partition wall 104, a rod insertion hole 105 communicating with pressure sensing chamber 102 and a valve hole 106 communicating with valve chamber 103 are formed. Rod insertion hole 105 and valve hole 106 are disposed on the same axis and communicated with each other. A communication hole 107 extending in the radial direction through lateral partition wall 104 is formed in lateral partition wall 104 passing through the communicating portion between rod insertion hole 105 and valve hole 106.
Pressure sensing chamber 102 communicates with suction chamber 21 via a communication hole 108 formed on the circumferential wall of valve housing 101, closed space 27c and a communication path 23a formed in cylinder head 23. Communication hole 107 communicates with discharge chamber 22 via closed space 27b and a communication path 23b formed in cylinder head 23. Valve hole 106 communicating with communication hole 107 always communicates with discharge chamber 22. Valve chamber 103 communicates with crank chamber 17 via closed space 27a, a communication path 23c formed in cylinder head 23 and communication path 16b formed in cylinder block 16.
A bellows assembly 109 functioning a pressure sensing member, in which a spring is disposed at a vacuum inside condition, is disposed in pressure sensing chamber 102. One end of a pressure sensing rod 110 is connected to one end 109a of bellows assembly 109, and the other end of pressure sensing rod 110 is slidably inserted into rod insertion hole 105. A small-diameter rod 111 extending from the other end of pressure sensing rod 110 is inserted into valve hole 106 at a movable condition with a gap. A spring 113 for urging a valve body 112 in a direction approaching valve hole 106 is disposed in valve chamber 103. Inside control valve 100 is formed by a series of structures from valve housing 101 to spring 113.
The end portion of pressure sensing chamber 102 side of valve housing 101 of inside control valve 100 is press fitted into one end of case 121 of electromagnetic solenoid 120. As aforementioned, O-ring 121a for forming closed space 27c is fitted onto the periphery of the one end portion of case 121.
Electromagnetic solenoid 120 has a fixed core 122 disposed in case 121, a movable core 123 disposed facing its one end to one end of fixed core 122, a releasing spring 124 for urging movable core 123 in a direction apart from the fixed core, and an electromagnetic coil 125 surrounding fixed core 122 and movable core 123. The space for containing movable core 123 is communicated with pressure sensing chamber 102, and is in a condition of the same pressure as that in pressure sensing chamber 102. The other end 109a of bellows assembly 109 is connected to the other end of movable core 123. The other end 109a is disposed so as to be able to engage with an end surface inner edge 121a near the above-described one end of case 121 of electromagnetic solenoid 120.
Next, the operation of displacement control valve 2 will be explained.
In a case where clutchless variable displacement inclined plate-type compressor 1 is operated at a displacement control condition, as shown in
When inside control valve 100 is in the operating condition, if the suction pressure is lower than a set value, as shown in
If the suction pressure exceed the set value, as shown in
Thus, by the operation of inside control valve 100, the opening/closing of valve hole 106 is repeated so that the suction pressure becomes the set value, and the discharge displacement of variable displacement inclined plate-type compressor 1 is variably controlled.
When electromagnetic coil 125 is degaussed, as shown in
The control property of displacement control valve 2 is represented by the following equation (1).
Ps=−(Sr−Sv)Pd/{Sb−(Sr−Sv)}+(f+αSv−F)/{Sb−(Sr−Sv)} (1)
Where,
In displacement control valve 2, because discharge pressure Pd acts on both valve body 112 and pressure sensing rod 110, the force of discharge pressure Pd for urging valve body 112 in the valve closing direction is (Sr−Sv)Pd. Because (Sr−Sv) is very small, the (Sr−Sv)Pd is much smaller than PdSv in the aforementioned Patent Document 1. Therefore, displacement control valve 2 can be made smaller that the displacement control valve of Patent Document 1.
In the displacement control valve of the aforementioned Patent Document 1, because the gradient of the correlation line of Ps relative to Pd is −-S1/S2, the gradient cannot be changed unless a cross-sectional area S1 of a valve hole or an effective cross-sectional area S2 of a bellows, which are base specifications of a displacement control valve, is changed. Namely, the property of the displacement control cannot be easily changed. On the other hand, in displacement control valve 2, because the gradient of the correlation line of Ps relative to Pd is −(Sr−Sv)/{Sb−(Sr−Sv)}, if the sectional area Sr ofthe pressure sensing rod is changed, even if the cross-sectional area Sv of the valve hole and the effective cross-sectional area Sb of the bellows assembly, which are base specifications of displacement control valve 2, are not changed, the gradient can be changed. Therefore, the property of the displacement control can be easily changed.
Further, in the displacement control valve of the aforementioned Patent Document 1, if it is tried to make the displacement control valve smaller without changing the gradient of the correlation line of Ps relative to Pd, ultimately, without changing the property of the displacement control, it is necessary to make SI and S2 smaller simultaneously. If a cross-sectional area S1 of a valve hole is made smaller, the velocity of high-pressure refrigerant gas, flowing into a crank chamber through a valve hole after a valve body is forcibly opened, decreases, the time required for changing the displacement of the inclined plate-type compressor to the minimum displacement increases, and the property of the displacement control deteriorates. Therefore, it is difficult to make it smaller. On the other hand, in displacement control valve 2, because the gradient of the correlation line of Ps relative to Pd is −(Sr−Sv)/{Sb−(Sr−Sv)}, the effective cross-sectional area Sb of the bellows can be made smaller by changing the cross-sectional area Sr of pressure sensing rod 110 without changing the cross-sectional area Sv of valve hole 106. Therefore, it is easy to make it smaller.
Because displacement control valve 2 can switch clutchless variable displacement inclined plate-type compressor 1 between a displacement control condition and a minimum displacement condition by excitation/degaussing of electromagnetic solenoid 120, by using this displacement control valve 2, the control unit for variable displacement inclined plate-type compressor 1 may be simplified.
Further, in displacement control valve 2, because provided is the positioning member formed by the other end 109b of bellows assembly 109 and the end surface inner edge 121b of case 121 of electromagnetic solenoid 120, it is possible to position inside control valve 100 at its operating position by the excitation of electromagnetic solenoid 120, and it is possible to switch variable displacement inclined plate-type compressor 1 to the displacement control condition by the excitation of electromagnetic solenoid 120. In displacement control valve 2, because the positioning member is formed by the other end 109b of bellows assembly 109 and the end surface inner edge 121b of case 121 of electromagnetic solenoid 120, it is not necessary to provide a particular positioning member separately, and the valve structure is simplified.
Further, in displacement control valve 2, because releasing spring 124 of electromagnetic solenoid 120 turns inside control valve 100 to the non-operating condition, it is not necessary to provide a spring for turning inside control valve 100 to the non-operating condition separately, and the valve structure is simplified.
In displacement control valve 2, when the cross-sectional area Sr of pressure sensing rod 110 is set greater than the cross-sectional area Sv of the valve hole. as shown in
On the other hand, when the cross-sectional area Sr of pressure sensing rod 110 is set smaller than the cross-sectional area Sv of the valve hole. as shown in
In the above-described embodiment, although the positioning member is formed by the other end 109b of bellows assembly 109 and the end surface inner edge 121b of case 121 of electromagnetic solenoid 120, the positioning member may be formed by the attractive portions of movable core 123 and fixed core 122. Moreover, an adjusting member for adjusting the urging force of spring 113 from outside may be provided.
The present invention can be applied broadly for displacement control valves of clutchless variable displacement inclined plate-type compressors. In particular, it is suitable as a displacement control valve for a compressor provided in a refrigeration cycle of an air conditioning system for vehicles.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2004-206550 | Jul 2004 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP05/12760 | 7/11/2005 | WO | 1/9/2007 |
