JP5235569B2 - Capacity control valve, variable capacity compressor and capacity control system of variable capacity compressor - Google Patents

Description

  The present invention relates to a capacity control valve, a variable capacity compressor, and a capacity control system for a variable capacity compressor, and more particularly to a capacity control valve, a variable capacity compressor, and a capacity control system for a variable capacity compressor that are suitable for a vehicle air conditioning system. About.

For example, a reciprocating variable displacement compressor used in a vehicle air conditioning system includes a housing, and a discharge chamber, a crank chamber, a suction chamber, and a cylinder bore are defined in the housing. A piston is disposed in the cylinder bore, and a drive shaft is rotatably supported in the housing.
The drive shaft rotates using the engine as a power source, and a conversion mechanism converts the rotation of the drive shaft into a reciprocating motion of the piston. As the piston reciprocates, the working fluid is sucked into the cylinder bore from the suction chamber, the sucked working fluid is compressed, and the compressed working fluid is discharged into the discharge chamber.

  In a reciprocating variable displacement compressor, the stroke length of the piston, that is, the discharge capacity of the compressor is variable by changing the pressure (control pressure) in the crank chamber (control pressure chamber). A capacity control valve for controlling the discharge capacity is disposed in an air supply passage communicating the discharge chamber and the crank chamber. On the other hand, a throttle is disposed in the bleed passage that connects the crank chamber and the suction chamber.

The capacity control valve is controlled by a control device, which controls the pressure difference (differential pressure) between the pressure in the discharge chamber (discharge pressure) and the pressure in the suction chamber (suction pressure) close to the target value. The discharge capacity is feedback controlled by the method (see, for example, Patent Document 1).
JP 2001-132650 A

  In the variable capacity compressor as described above, when the cooling load is small, the differential pressure as the control target is set small. However, when the differential pressure is reduced, the supply amount of the working fluid (discharge gas) in the discharge chamber to the crank chamber decreases, and the discharge capacity may not be stably controlled. As a result, the drive torque of the variable capacity compressor fluctuates, which may adversely affect engine speed control. In addition to this, the discharge capacity does not become smaller than the target, and there is a risk that the suction pressure will drop and the evaporator will freeze.

On the other hand, for example, it is assumed that the refrigerant charging amount in the refrigeration circuit is insufficient. In this case, the differential pressure is lower than when the filling amount is appropriate. According to the differential pressure control method, if the differential pressure is to decrease, the control device increases the discharge capacity so as to maintain the differential pressure at a predetermined value.
In such a differential pressure control method, the discharge capacity is increased until the differential pressure reaches the target value. However, when the refrigerant charge amount is insufficient and the circulation amount is insufficient, the differential pressure does not reach the target value, and the discharge capacity is increased at an accelerated rate, and finally reaches the maximum capacity. For this reason, in the case of the above assumption, the differential pressure control method has a drawback of accelerating the breakage of the compressor.

  An object of the present invention is to provide a capacity control valve, a variable capacity compressor, and a capacity control system in which the discharge capacity is stably controlled even when the cooling load is small and the risk of damage to the compressor is reduced even when the refrigerant amount is insufficient. Is to provide.

  In order to solve the above-described problem, according to one aspect of the present invention, the variable displacement compressor is disposed in a communication path that communicates a discharge pressure region and a control pressure chamber, and controls the discharge capacity of the variable displacement compressor. Therefore, a displacement control valve for adjusting the pressure of the control pressure chamber, wherein the pressure in the discharge pressure region of the solenoid unit and the variable displacement compressor acts in the valve opening direction, and the variable displacement compressor A valve body in which the pressure in the suction pressure region and the electromagnetic force of the solenoid unit act in a valve closing direction opposite to the valve opening direction, and a pressure sensor in which the pressure in the discharge pressure region acts, When the pressure is lower than a set pressure, the valve body is connected to the valve body to apply an urging force in the valve opening direction corresponding to the pressure in the discharge pressure area to the valve body, and the pressure in the discharge pressure area is larger than the set pressure. When the valve body Capacity control valve, characterized in that it comprises a pressure sensitive unit which is released is provided (claim 1).

In a preferred embodiment, the first pressure receiving area where the pressure in the discharge pressure region acts on the valve body is larger than the second pressure receiving area where the pressure in the suction pressure region of the variable capacity compressor acts on the valve body. Equal or larger (claim 2).
In a preferred aspect, the pressure sensor is arranged so that the pressure sensor and the valve body act in a direction in which the pressure in the discharge pressure region opposes (Claim 3).

In a preferred aspect, the first pressure receiving area is set to be substantially equal to a third pressure receiving area at which the pressure in the discharge pressure region acts on the pressure sensor.
In a preferred aspect, the pressure sensor is arranged in a region extending between the discharge pressure region and the valve hole of the displacement control valve in the communication passage.
Further, according to one aspect of the present invention, a discharge chamber as the discharge pressure region, a crank chamber as the control pressure chamber, a suction chamber, and a housing in which a cylinder bore is partitioned and disposed in the cylinder bore A piston, a drive shaft rotatably supported in the housing, a conversion mechanism including a variable tilting swash plate element that converts the rotation of the drive shaft into a reciprocating interlock of the piston, and any of the aforementioned capacities There is provided a variable capacity compressor comprising a control valve (Claim 6).

  Furthermore, according to one aspect of the present invention, a control target value is set based on any of the capacity control valves described above, external information detection means for detecting external information, and external information detected by the external information detection means. A control target setting means for setting; and a current adjusting means for adjusting a current supplied to the solenoid unit based on a control target value set by the control target setting means, and adjusting the pressure of the control pressure chamber. In the capacity control system of the variable capacity compressor for controlling the discharge capacity of the variable capacity compressor, the external information detection means includes a discharge pressure detection means for detecting the pressure in the discharge pressure region, and the discharge pressure When the pressure in the discharge pressure region detected by the detection unit is lower than the set pressure, the control target setting unit sets the control target value to the pressure in the suction pressure region. A capacity control system for a variable capacity compressor, wherein a target suction pressure which is a standard value is set, and the current adjusting means adjusts a current supplied to the solenoid unit based on the target suction pressure. (Claim 7).

  In a preferred aspect, when the pressure in the discharge pressure region detected by the discharge pressure detection unit is higher than the set pressure, the control target setting unit sets a target suction pressure that is a target value of the pressure in the suction pressure region. The control target value is set, and the current adjusting means adjusts the current supplied to the solenoid unit based on the pressure in the discharge pressure region detected by the discharge pressure detecting means and the target suction pressure (claim). Item 8).

  In a preferred aspect, when the pressure in the discharge pressure region detected by the discharge pressure detection means is higher than the set pressure, the control target setting means sets the target value of the current supplied to the solenoid unit to the control target. The current adjusting means adjusts the current supplied to the solenoid unit so as to approach the target value of the current.

  When the displacement control valve according to claim 1 of the present invention is applied to a variable displacement compressor, in the control range where the pressure in the discharge pressure region is lower than the set pressure, the pressure in the suction pressure region is targeted instead of the differential pressure control method. The discharge capacity can be controlled by a suction pressure control system approaching the pressure. As a result, the discharge capacity is stably controlled even when the cooling load is small, and the risk of breakage of the compressor is reduced even when the refrigerant amount is insufficient.

According to the capacity control valve of the second aspect, the excessive opening operation of the valve body is suppressed, and the opening / closing operation of the valve body is stabilized.
According to the capacity control valve of the third aspect, the influence of the pressure in the discharge pressure region acting on the valve body is reduced, and the suction pressure control accuracy is improved.
According to the capacity control valve of the fourth aspect, the influence of the pressure in the discharge pressure region acting on the valve body is substantially eliminated, and the suction pressure control accuracy is further improved.

The capacity control valve of claim 5 has a simple structure.
In the variable displacement compressor according to the sixth aspect, the minimum piston stroke is defined by the minimum inclination angle of the swash plate. In this type of compressor, the piston stroke can be set very small, thereby reducing the minimum discharge capacity and widening the control range of the discharge capacity. According to the present invention, since the volume control is stably performed even with the minimum discharge capacity, a wide control range is effectively used.

  According to the capacity control system of the variable capacity compressor of claim 7 of the present invention, in the control range in which the pressure in the discharge pressure region is lower than the set pressure, the pressure in the suction pressure region is targeted instead of the differential pressure control method. The discharge capacity is controlled by the approaching suction pressure control method. As a result, the discharge capacity is stably controlled even when the cooling load is small, and the risk of breakage of the compressor is reduced even when the refrigerant amount is insufficient.

  According to the capacity control system of the variable capacity compressor of claim 8, even when the pressure in the discharge pressure region is higher than the set pressure, the discharge capacity is controlled by the suction pressure control system that brings the pressure in the suction pressure region closer to the target. The That is, the discharge capacity is controlled by the suction pressure control method regardless of the pressure in the discharge pressure region. When this capacity control system is applied to a refrigeration cycle of an air conditioning system, the pressure in the suction pressure region has a strong correlation with the temperature of the evaporator, so that the control accuracy of the room temperature by the air conditioning system is improved.

  According to the capacity control system of the variable capacity compressor of the ninth aspect, the discharge capacity is controlled by the differential pressure control method in the control range where the pressure in the discharge pressure region is higher than the set pressure. According to the differential pressure control method, it is easy to estimate the torque of the compressor, and the torque control of the compressor can be stably performed in a region where the pressure in the discharge pressure region is relatively high (medium / high load region).

Hereinafter, a capacity control system A for a variable capacity compressor according to an embodiment of the present invention will be described.
FIG. 1 shows a refrigeration cycle 10 of a vehicle air conditioning system to which a capacity control system A is applied. The refrigeration cycle 10 includes a circulation path 12 through which a refrigerant as a working fluid circulates. In the circulation path 12, a compressor 100, a radiator (condenser) 14, an expander (expansion valve) 16, and an evaporator 18 are sequentially inserted in the refrigerant flow direction. When the compressor 100 is operated, the refrigerant circulates through the circulation path 12 according to the discharge capacity of the compressor 100. That is, the compressor 100 performs a series of processes including a refrigerant suction process, a suction refrigerant compression process, and a compressed refrigerant discharge process.

The evaporator 18 also constitutes a part of an air circuit of the vehicle air conditioning system. The air flow passing through the evaporator 18 is cooled by taking heat of vaporization by the refrigerant in the evaporator 18.
The compressor 100 to which the capacity control system A is applied is a variable capacity compressor, for example, a swash plate type clutchless compressor. The compressor 100 includes a cylinder block 101, and the cylinder block 101 is formed with a plurality of cylinder bores 101a. A front housing 102 is connected to one end of the cylinder block 101, and a rear housing (cylinder head) 104 is connected to the other end of the cylinder block 101 via a valve plate 103.

  The cylinder block 101 and the front housing 102 define a crank chamber 105, and a drive shaft 106 extends longitudinally through the crank chamber 105. The drive shaft 106 passes through an annular swash plate 107 disposed in the crank chamber 105, and the swash plate 107 is hinged to a rotor 108 fixed to the drive shaft 106 via a connecting portion 109. Accordingly, the swash plate 107 can tilt while moving along the drive shaft 106.

  A portion of the drive shaft 106 extending between the rotor 108 and the swash plate 107 is provided with a coil spring 110 that urges the swash plate 107 toward the minimum inclination angle. A coil spring 111 that urges the swash plate 107 toward the maximum inclination angle is attached to a portion of the drive shaft 106 that extends between the swash plate 107 and the cylinder block 101. The drive shaft 106 penetrates through a boss portion 102a protruding outside the front housing 102, and is connected to a pulley 112 as a power transmission device at the outer end of the drive shaft 106. The pulley 112 is rotatably supported by a boss portion 102a via a ball bearing 113, and a belt 115 is wound around a pulley of an engine 114 as an external drive source.

  A shaft seal device 116 is disposed inside the boss portion 102 a, and the shaft seal device 116 blocks the inside and the outside of the front housing 102. The drive shaft 106 is rotatably supported by bearings 117, 118, 119, and 120 in the radial direction and the thrust direction. When power from the engine 114 is transmitted to the pulley 112, the drive shaft 106 can rotate in synchronization with the rotation of the pulley 112.

  A piston 130 is disposed in the cylinder bore 101 a, and a tail portion protruding into the crank chamber (control pressure chamber) 105 is integrally formed with the piston 130. A pair of shoes 132 is disposed in a recess 130a formed in the tail portion, and the shoes 132 are in sliding contact with the outer peripheral portion of the swash plate 107 so as to be sandwiched therebetween. Therefore, the piston 130 and the swash plate 107 are interlocked with each other via the shoe 132, and the piston 130 reciprocates in the cylinder bore 101a by the rotation of the drive shaft 106.

  A suction chamber (suction pressure region) 140 and a discharge chamber (discharge pressure region) 142 are defined in the rear housing 104, and the suction chamber 140 communicates with the cylinder bore 101 a through a suction hole 103 a provided in the valve plate 103. Is possible. The discharge chamber 142 communicates with the cylinder bore 101a through a discharge hole 103b provided in the valve plate 103. The suction hole 103a and the discharge hole 103b are opened and closed by a suction valve and a discharge valve (not shown), respectively.

  A muffler 150 is provided outside the cylinder block 101. A muffler base 101b is formed integrally with the cylinder block 101, and a muffler casing 152 is joined to the muffler base 101b via a seal member (not shown). The muffler casing 152 and the muffler base 101b define a muffler space 154, and the muffler space 154 communicates with the discharge chamber 142 via the rear housing 104, the valve plate 103, and a discharge passage 156 that passes through the muffler base 101b.

  A discharge port 152a is formed in the muffler casing 152, and a check valve 200 is disposed in the muffler space 154 so as to block between the discharge passage 156 and the discharge port 152a. Specifically, the check valve 200 opens and closes according to the pressure difference between the pressure on the discharge passage 156 side and the pressure on the muffler space 154 side, and closes when the pressure difference is smaller than a predetermined value, and the pressure difference is predetermined. If it is larger than the value, it opens.

Therefore, the discharge chamber 142 can communicate with the forward portion of the circulation path 12 via the discharge passage 156, the muffler space 154, and the discharge port 152a, and the muffler space 154 is interrupted by the check valve 200. On the other hand, the suction chamber 140 communicates with the return path portion of the circulation path 12 via a suction port 104 a formed in the rear housing 104.
A capacity control valve (electromagnetic control valve) 300 is accommodated in the rear housing 104, and the capacity control valve 300 is inserted in the air supply passage 160. The air supply passage 160 extends from the rear housing 104 to the cylinder block 101 through the valve plate 103 so as to communicate between the discharge chamber 142 and the crank chamber 105.

  On the other hand, the suction chamber 140 communicates with the crank chamber 105 via the extraction passage 162. The extraction passage 162 includes a clearance between the drive shaft 106 and the bearings 119 and 120, a space 164, and a fixed orifice 103 c formed in the valve plate 103. The suction chamber 140 is connected to the capacity control valve 300 independently of the air supply passage 160 through a pressure sensitive passage 166 formed in the rear housing 104.

  More specifically, as shown in FIG. 2, the capacity control valve 300 includes a valve unit 300A and a solenoid unit 300B that opens and closes the valve unit 300A. The valve unit 300 </ b> A has a substantially cylindrical valve housing 301, and a valve hole 301 a is formed in a substantially central portion of the valve housing 301. The valve hole 301 a extends in the axial direction of the valve housing 301, and one end of the valve hole 301 a opens into a first pressure sensing chamber 302 defined in the valve housing 301.

A communication hole 301 b is formed in a portion of the valve housing 301 that forms the peripheral wall of the first pressure sensing chamber 302. The communication hole 301 b communicates with the discharge chamber 142 via the upstream portion of the air supply passage 160. Accordingly, the valve hole 301a communicates with the discharge chamber 142 via the first pressure sensing chamber 302, the communication hole 301b, and the upstream portion of the air supply passage 160.
The other end of the valve hole 301 a opens to a valve chamber 303 defined inside the valve housing 301. The valve chamber 303 has an outlet port 301c that passes through the valve housing 301 in the radial direction. Therefore, the valve chamber 303 communicates with the crank chamber 105 via the outlet port 301 c and the downstream portion of the air supply passage 160.

  One end of an insertion hole 304 is opened in the valve chamber 303 on the side opposite to the valve hole 301a, and the insertion hole 304 extends on the axis of the valve housing 301, like the valve hole 301a. The other end of the insertion hole 304 opens to the second pressure sensing chamber 305, and a pressure sensing port 301 d that penetrates the valve housing 301 in the radial direction opens to the second pressure sensing chamber 305. Therefore, the second pressure sensing chamber 305 communicates with the suction chamber 140 through the pressure sensing port 301d and the pressure sensing path 166.

A cylindrical valve body 306 is disposed in the valve housing 301. As shown in an enlarged view in FIG. 3, one end side of the cylindrical sliding portion 307 is integrally and coaxially connected to the back surface of the valve body 306, and the sliding portion 307 is slidably supported by the insertion hole 304. Has been.
One end side of the shaft portion 308 is continuous and coaxial with the opposite side of the sliding portion 307, and the shaft portion 308 is located in the second pressure sensing chamber 305. On the opposite side of the shaft portion 308, a hemispherical head portion 309 having a larger diameter than the shaft portion 308 is integrally formed. An open spring 310 made of a conical coil spring is disposed between the end wall of the second pressure sensing chamber 305 where the insertion hole 304 is opened and the head portion 309, and the open spring 310 is separated from the valve hole 301a ( The valve body 306 is urged in the valve opening direction).

On the other hand, the base end side of the transmission rod 311 is coaxially and integrally connected to the front surface of the valve body 306, and the transmission rod 311 passes through the valve hole 301a. The outer diameter of the transmission rod 311 is smaller than the inner diameter of the valve hole 301 a, and the distal end of the transmission rod 311 reaches the first pressure sensing chamber 302.
Referring to FIG. 2 again, the solenoid unit 300B has a substantially cylindrical solenoid housing 320, and the solenoid housing 320 is coaxially connected to the other end of the valve housing 301 by press fitting. The open end of the solenoid housing 320 is closed by an end cap 322, and a cylindrical coil (solenoid coil) 326 covered with a resin member 324 is accommodated in the solenoid housing 320.

  In the solenoid housing 320, a substantially cylindrical fixed core 328 is concentrically housed, and the fixed core 328 extends from the valve housing 301 toward the end cap 322 to the center of the coil 326. The end cap 322 side of the fixed core 328 is surrounded by a cylindrical tubular member 330, and the tubular member 330 has a closed end on the end cap 322 side. A support member 332 is disposed inside the cylindrical member 330 in close contact with the closed end of the cylindrical member 330, and a substantially cylindrical movable core 334 is interposed between the fixed three arm 318 and the support member 332. A movable core housing space 335 for housing is defined.

  Here, the fixed core 328 has a central hole 328 a, and one end of the central hole 328 a opens into the movable core accommodating space 335. A solenoid rod 336 is inserted into the central hole 328a, and the solenoid rod 336 protrudes from both ends of the fixed core 328. A movable core 334 is integrally fixed to a portion of the solenoid rod 336 that vertically cuts through the movable core housing space 335. The solenoid rod 336 reaches the support member 332, and the end of the solenoid rod 336 on the support member 332 side is slidably supported by the cylindrical bottomed hole of the support member 332.

The movable core 334, the fixed core 328, the solenoid housing 320, and the end cap 322 are made of a magnetic material and constitute a magnetic circuit. The cylindrical member 330 is made of a non-magnetic stainless steel material.
A compression coil spring 338 is disposed between the movable core 334 and the support member 332, and the compression coil spring 338 biases the movable core 334 in a direction away from the support member 332 (valve closing direction).

However, a predetermined gap is secured between the movable moving core 324 and the fixed core 328. Further, the outer diameter of the movable core 334 is smaller than the inner diameter of the tubular member 330, and a gap is secured between the movable core 334 and the tubular member 330.
On the other hand, the other end of the central hole 328a opens into the second pressure sensing chamber 305. Referring to FIG. 3 again, the inner diameter of the central hole 328a is the protruding end of the fixed core 328 protruding into the pressure sensing chamber side 305. Has been reduced. The end of the solenoid rod 336 on the second pressure sensing chamber 305 side is slidably supported by the protruding end of the fixed core 328, that is, the reduced diameter portion of the central hole 328a. The end of the solenoid rod 336 that protrudes into the second pressure sensing chamber 305 is in contact with the head 309.

  A communication hole 339 is formed at the base of the protruding end of the fixed core 328, and the second pressure sensing chamber 305 communicates with the movable core housing space 335 through the communication hole 339 and the central hole 328a. Accordingly, since the entire solenoid rod 336 is exposed to the pressure of the suction chamber 140, that is, the suction pressure Ps, it is defined by the cross-sectional area of the sliding portion 307 that partitions the second pressure sensing chamber 305 and the valve chamber 303. In the region, the suction pressure Ps acts on the valve body 306 in the valve closing direction.

  A control device 400 provided outside the compressor 100 is connected to the coil 326 (see FIG. 2). When the control current I is supplied from the control device 400 to the coil 326, the solenoid unit 300B is F (I) is generated. The electromagnetic force F (I) of the solenoid unit 300B attracts the movable core 334 toward the fixed core 328, and acts on the valve body 306 in the valve closing direction via the solenoid rod 336.

As shown in an enlarged view in FIG. 4, a pressure sensor 340 is disposed in the first pressure chamber 302, and the pressure sensor 340 has a disk-shaped base 341. The base 341 is press-fitted into the opening end of the peripheral wall of the valve housing 301, thereby being fitted in an airtight manner.
A cylindrical stopper 342 protrudes integrally from the center of the inner surface of the base 341, and a bellows 343 is disposed around the stopper 342. One end of the bellows 343 is airtightly fixed to the base 341, and the other end of the bellows 343 is airtightly fixed to the cap 344. The inside of the bellows 343 is maintained in a vacuum (a reduced pressure state).

The cap 344 includes a cylindrical portion 344a, a flange portion 344b connected to one end of the cylindrical portion 344a, and an end wall portion 344c that closes the other end of the cylindrical portion 344a. A compression coil spring 345 is disposed between the base 341 and the flange portion 344 b of the cap 344, and the compression coil spring 345 surrounds the bellows 343.
The compression coil spring 345 and the bellows 343 can expand and contract in the axial direction of the valve housing 301, that is, in the valve opening direction or the valve closing direction. Therefore, the pressure sensor 340 is displaced in the valve opening direction or the valve closing direction according to the pressure in the first pressure sensing chamber 302 (pressure in the discharge pressure region), but the expansion / contraction amount of the pressure sensor 340 is limited, and the cap The contraction of the pressure sensor 340 is limited by the end wall portion 344 c of the 344 coming into contact with the stopper 342.

The cylindrical portion 344 a and the end wall portion 344 c of the cap 344 form a recess that is recessed from the end face of the pressure sensor 340 toward the stopper 342, and the tip of the transmission rod 311 is in the recess of the cap 344 of the pressure sensor 340. Has reached. The end wall portion 344 c of the cap 344 can be brought into contact with and separated from the distal end of the transmission rod 311 corresponding to the amount of expansion and contraction of the pressure sensor 340.
FIG. 4 shows a state where the pressure sensor 340 is extended and the tip of the transmission rod 311 is in contact with the end wall portion 344c of the cap 344. In this state, the pressure sensor 340 and the valve body 306 The gaps are connected via a transmission rod 311.

  On the other hand, FIG. 5 shows a state in which the pressure sensor 340 contracts compared to FIG. 4 and the tip of the transmission rod 311 is separated from the end wall portion 344 c of the cap 344. In this state, the pressure sensor 340 and the valve body 306 are separated from each other. The tip of the transmission rod 311 does not come out of the recess of the cap 344 even when the pressure sensor 340 contracts most. The concave portion of the cap 344 functions as a guide when the end wall portion 344c of the cap 344 contacts and separates from the tip of the transmission rod 311.

  Therefore, as the pressure in the discharge chamber 142, that is, the discharge pressure region (hereinafter referred to as discharge pressure Pd) decreases, the pressure sensor 340 expands, and the cap 344 of the pressure sensor 340 moves toward the valve body 306. . Then, after the end wall portion 344 c of the cap 344 comes into contact with the tip of the transmission rod 311, when the pressure sensor 340 further extends, the valve body 306 is pressed through the transmission rod 311 in the valve opening direction.

The amount of press-fitting of the base 341 of the pressure sensor 340 to the valve housing 301 is adjusted so that the displacement control valve 300 performs a desired operation.
Here, the force acting on the valve body 306 of the capacity control valve 300 is as follows depending on the case.
Case A: Pressure sensor 340 contracts and pressure sensor 340 is separated from the tip of transmission rod 311 In this case, the pressure from pressure sensor 340 does not act on valve body 306. The valve body 306 includes a discharge pressure Pd, a crank chamber 105 pressure (crank pressure Pc), a suction chamber 140, that is, a suction pressure region pressure (suction pressure Ps), an urging force fs1 of the release spring 310, and a compression coil spring 338. The urging force fs2 and the electromagnetic force F (I) of the solenoid unit 300B are applied.

  The pressure receiving area (first pressure receiving area) of the valve body 306 on which the discharge pressure Pd acts in the valve opening direction through the first pressure sensing chamber 305 and the valve hole 301a is defined by Sv, and the sectional area of the sliding portion 307, 2 If the pressure receiving area (second pressure receiving area) of the valve body 306 on which the suction pressure Ps in the pressure sensing chamber 305 acts in the valve closing direction is Sr, preferably the first pressure receiving area Sv is the second pressure. It is set slightly larger than the pressure receiving area Sr. As a result, the crank pressure Pc slightly acts on the valve body 306 in the valve closing direction in the area of (Sv−Sr). As a result, the excessive opening operation of the valve body 306 is suppressed, and the opening / closing operation of the valve body 306 is stabilized.

Accordingly, the discharge pressure Pd acts on the valve body 306 in the valve opening direction, and the suction pressure Ps and the crank pressure Pc act on the valve closing direction opposite thereto.
In the case A, the force acting on the valve body 306 can be expressed by the following expression (1), and the expression (2) is obtained by modifying the expression (1) with Pc = Ps + α. It is empirically known that Pc = Ps + α, that is, the difference α between the crank pressure Pc and the suction pressure Ps falls within a substantially constant range. If equation (2) is modified and the left side is Pd-Ps, equation (3) is obtained. Then, if the solenoid unit 300B is designed so that the electromagnetic force F (I) is proportional to the control current I, the equation (3) is modified by F (I) = A · I (A is a coefficient). Equation (4) is obtained.

  Note that Sv> Sr and fs1> fs2.

  Equation (3) is an electromagnetic force F (I) generated in the solenoid unit 300B, that is, a current supplied to the coil 326 of the solenoid unit 300B, which is a differential pressure between the discharge pressure Pd and the suction pressure Ps (Pd-Ps differential pressure). (Control current) I indicates that adjustment is possible. The electromagnetic force F (I) is proportional to the control current I, and the electromagnetic force F (I) acts on the valve body 306 in the valve closing direction. For this reason, as shown in FIG. 6, as the control current I is increased, the Pd-Ps differential pressure increases. That is, by adjusting the control current I, the Pd-Ps differential pressure can be set to an arbitrary value.

Control device 400 sets a target value of control current I based on the external information detected by the external information detection means. When the control current I is supplied to the coil 326 at the target value, the valve opening degree of the capacity control valve 300 is adjusted so that the Pd−Ps differential pressure approaches the target differential pressure ΔPset. That is, in the case A, the Pd-Ps differential pressure is feedback controlled.
Since the biasing force fs1 of the release spring 310 is set larger than the biasing force fs2 of the compression coil spring 338, the valve body 306 opens the valve hole 301a by the biasing force of the release spring 310 when the control current I is zero. To do. As a result, the refrigerant (discharge gas) in the discharge chamber 142 is introduced into the crank chamber 105, and the discharge capacity is kept to a minimum.

Case B: When the pressure sensor 340 extends and the pressure sensor 340 is in contact with the tip of the transmission rod 311 In this case, a pressing force acts on the valve body 306 from the pressure sensor 340 in the valve opening direction. Therefore, the force acting on the valve body 306 is obtained by adding (fs3-Pd · Sb) as a pressing force from the pressure sensor 340 to the left side of the equation (1) as shown in the following equation (5). Become. fs3 is an urging force of the compression coil spring 345, and Sb is an effective area of the bellows 343, that is, a pressure receiving area where the discharge pressure Pd acts on the pressure sensor 340 in the contraction direction (third pressure receiving area). It is.

  When formula (5) is modified with Pc = Ps + α and Sv = Sb, formula (6) is obtained. If Expression (6) is transformed and the left side is Ps, Expression (7) is obtained. Then, Expression (8) is obtained by modifying Expression (7) as F (I) = A · I (A is a coefficient).

  When the pressure sensor 340 is in contact with the tip of the transmission rod 311, the direction in which the discharge pressure Pd directly acts on the valve body 306 and the direction in which the discharge pressure Pd acts on the bellows 343 are mutually different. The reverse direction. In addition, since the first pressure receiving area Sv and the third pressure receiving area Sb are set to be approximately equal (Sv = Sb), the discharge pressure Pd in the opposite direction (counter direction) is canceled out, and the valve body 306 The influence of the discharge pressure Pd on is substantially eliminated. Note that the case where the first pressure receiving area Sv and the third pressure receiving area Sb are substantially equal is the case where the first pressure receiving area Sv and the third pressure receiving area Sb are equal, as well as the first pressure receiving area Sb. This includes a case where there is a difference between Sv and the third pressure receiving area Sb so that the designed first pressure receiving area Sv and the third pressure receiving area Sb can be regarded as the same level (for example, the first pressure receiving area Sb). (Including the case where there is a difference caused by manufacturing variations in component dimensions for defining the pressure receiving area Sv and the third pressure receiving area Sb).

Therefore, Expression (8) indicates that the suction pressure Ps can be adjusted by the electromagnetic force F (I) generated by the solenoid unit 300B, that is, the control current I. When the control current I is increased, the electromagnetic force F (I) acts on the valve body 306 in the valve closing direction. For this reason, as shown in FIG. 7, the suction pressure Ps can be lowered as the current I is increased.
The control device 400 sets a target suction pressure Pss that is a target value of the suction pressure Ps based on the external information from the external information detection means. Setting the target suction pressure Pss is equivalent to setting the target value of the control current I. When the control current I is supplied to the coil 326 of the solenoid unit 300B at the target value, the valve opening of the capacity control valve 300 is adjusted so that the suction pressure Ps approaches the target suction pressure Pss.

  In other words, the capacity control system A uses the differential pressure control method that feedback-controls the Pd-Ps differential pressure when the pressure sensor 340 contracts and the pressure sensor 340 is separated from the tip of the transmission rod 311. To control. On the other hand, the capacity control system A controls the discharge capacity by the suction pressure control method in which the suction pressure Ps is feedback-controlled in the case B where the pressure sensor 340 extends and the pressure sensor 340 is in contact with the tip of the transmission rod 311. .

  A state where the biasing force fs3 of the compression coil spring 345 of the pressure sensor 340 and the discharge pressure Pd acting on the pressure sensor 340 are balanced is expressed by the equation: fs3-Pd · Sb = 0. When the pressure sensor 340 is in a balanced state and the valve body 306 is in the valve closing position that closes the valve hole 301a, the pressure sensor 340 is installed so as to simply contact with the tip of the transmission rod 311 without pressing. .

If the discharge pressure Pd in the balanced state is the set pressure Pds of the pressure sensor 340, then Pds = fs3 / Sb. Considering the set pressure Pds, expansion / contraction of the pressure sensor 340 from the balanced state and contact / separation between the pressure sensor 340 and the tip of the transmission rod 311 are determined under the following conditions.
When the discharge pressure Pd is larger than the set pressure Pds (Pd> Pds), the pressure sensor 340 contracts and the pressure sensor 340 is separated from the tip of the transmission rod 311. That is, the pressure sensor 340 and the valve body 306 are separated.

When the discharge pressure Pd is equal to or lower than the set pressure Pds (Pd ≦ Pds), the pressure sensor 340 extends and the pressure sensor 340 comes into contact with the tip of the transmission rod 311. That is, the pressure sensor 340 and the valve body 306 are connected.
Therefore, if the discharge pressure Pd is equal to or lower than the set pressure Pds, the capacity control system A adopts the suction pressure control system via the capacity control valve 300. Thereby, even when the cooling load is small, the discharge capacity is stably controlled, and the risk of breakage of the compressor 100 is reduced even when the refrigerant amount is insufficient.

FIG. 8 is a block diagram showing a schematic configuration of the capacity control system A including the control device 400. The capacity control system A has external information detection means for detecting one or more external information, and the external information detection means has an evaporator target outlet air temperature setting means 401 and an evaporator temperature sensor 402.
The evaporator target outlet air temperature setting means 401 sets the evaporator target outlet air temperature Tes based on various external information including the vehicle compartment temperature setting. The evaporator target outlet air temperature Tes is a final target of the discharge capacity control of the compressor 100, and is a target value of the air temperature Te at the outlet of the evaporator 18. Then, the evaporator target outlet air temperature setting means 401 inputs the set evaporator target outlet air temperature Tes to the control device 400 as one of external information. The evaporator target outlet air temperature setting means 401 can be constituted by, for example, a part of an air conditioner ECU that controls the operation of the entire air conditioning system. That is, the evaporator target outlet air temperature setting means 401 may set the target value for the control amount of the vehicle air conditioning system.

The evaporator temperature sensor 402 is installed at the outlet of the evaporator 18 in the air circuit, and detects the air temperature Te immediately after passing through the evaporator 18 (see FIG. 1). The detected air temperature Te is input to the control device 400 as one piece of external information.
Further, the external information detecting means includes a discharge pressure detecting means, and the discharge pressure detecting means has a pressure sensor 403 constituting a part thereof. The discharge pressure detecting means is means for detecting the discharge pressure Pd. The pressure sensor 403 is mounted on, for example, the inlet side of the radiator 14 and detects the pressure of the refrigerant in the part, and inputs it to the control device 400 (see FIG. 1). If there is a pressure difference between the installation site of the pressure sensor 403 and the discharge chamber 142, the discharge pressure Pd can be detected by correcting the pressure detected by the pressure sensor 403 by the pressure difference.

The control device 400 includes a control target setting unit 410 and a current adjustment manual 411.
The control target setting means 410 is a deviation Δ between the evaporator outlet air temperature Te actually detected by the evaporator temperature sensor 402 and the evaporator target outlet air temperature Tes set by the evaporator target outlet air temperature setting means 401. Based on T, the target of the control current I is set as the control target. Specifically, the target of the control current I is set by PI control or PID control based on the deviation ΔT.

When the discharge pressure Pd exceeds the set pressure Pds of the pressure sensor 340, the capacity control valve 300 is set apart from the transmission rod 311 so that the target of the control current I cannot be set. The target differential pressure ΔPset is set as the target of the Pd−Ps differential pressure.
In this case, for example, as shown in FIG. 6, the target differential pressure ΔPset is set within a range between a preset upper limit ΔPmax and lower limit ΔPmin of the target differential pressure ΔP. Then, the target of the control current I is set based on the target differential pressure ΔPset.

The target of the control current I is set within a range between a preset lower limit IL1 and upper limit IH1.
When the discharge pressure Pd is equal to or lower than the set pressure Pds of the pressure sensor 340, the capacity control valve 300 is in a state in which the pressure sensor 340 is in contact with the transmission rod 311. Is that the target suction pressure Pss is set as the target of the suction pressure Ps.

For example, when the discharge pressure Pd detected by the discharge pressure detection means is equal to or lower than the set pressure Pds of the pressure sensor 340, as shown in FIG. 7, a preset target suction pressure Pss is set. The target of the control current I is set in a range between the lower limit IL2 and the upper limit IH2 of the control current I corresponding to the upper limit PssH and the lower limit PssL, respectively.
The upper limit PssH can be set to a value lower than the set pressure Pds (= fs3 / Sb) of the pressure sensor 340 by a predetermined value, and the lower limit PssL should be set from the viewpoint of air conditioning capability and protection in case of refrigerant shortage. Can do.

The current adjusting unit 411 supplies the control current I to the coil 326 based on the target of the control current I set by the control target setting unit 410 and drives the capacity control valve 300.
FIG. 9 illustrates a schematic configuration of the current adjusting unit 411. The current adjusting unit 411 includes a switching element 420, and the switching element 420 is inserted in series with the coil 326 of the capacity control valve 300 in a power supply line extending between the power supply 430 and the ground. The switching element 420 can connect and disconnect the power supply line, and the control current I is supplied to the coil 326 by PWM (pulse width modulation) at a predetermined drive frequency (for example, 400 to 500 Hz) by the operation of the switching element 420. A diode 421 is connected in parallel with the coil 326 to form a flywheel circuit.

A predetermined drive signal is input to the switching element 420 from the control signal generating means 422, and the duty ratio in PWM is changed corresponding to this signal.
In addition, a current sensor 423 is inserted in the power supply line, and the current sensor 423 detects a control current I flowing through the coil 326. Regarding the current sensor 423, the installation location is not particularly limited as long as the control current I can be detected. The current sensor 423 is not limited to an ammeter as long as a physical quantity corresponding to the control current I can be detected, and may be a voltmeter. .

  The current sensor 423 inputs the detected control current I to the control current comparison / determination unit 424, and the control current comparison / determination unit 424 detects the target of the control current I set by the control target setting unit 410 and the current sensor 423. The control current I is compared. Then, the control current comparison determination unit 424 changes the drive signal generated by the control signal generation unit 422 so that the detected control current I approaches the target of the control current I based on the comparison result.

The present invention is not limited to the above-described embodiment, and various modifications can be made.
For the capacity control valve, for example, the following modifications are possible.
The pressure sensor 340 includes a compression coil spring 345 disposed around the bellows 343, but a pressure sensor in which a compression coil spring is disposed inside the bellows may be used.
The transmission rod may be composed of a separate part from the valve body.

Instead of the bellows 343, a pressure sensor using a diaphragm may be used.
The first pressure receiving area Sv of the valve body 306 and the pressure receiving area of the pressure sensor 340, that is, the effective area Sb of the bellows 343 are not set to be substantially equal, but are set as Sb> Sv or Sb <Sv. Thus, the discharge pressure Pd may be intentionally applied to the valve body 306.
The biasing force fs1 of the release spring 310 is set to be larger than the biasing force fs2 of the compression coil spring 338 (fs1> fs2), but may be fs1 <fs2.

  In the first embodiment, the set pressure Pds of the pressure sensor 340 is assumed to be a relatively low value within the variable range of the discharge pressure Pd, but the urging force of the compression coil spring 345 is increased. The set pressure Pds may be increased. By increasing the set pressure Pds, the control range in the suction pressure control method can be expanded. The set pressure Pds can be appropriately selected according to design conditions.

For the variable capacity compressor, for example, the following modifications are possible.
Although the compressor 100 of the first embodiment is a swash plate type clutchless compressor, a compressor having a clutch mechanism may be used. Further, as long as the discharge capacity can be controlled by adjusting the pressure in the control pressure chamber, the swash plate type is not limited, and a variable capacity compressor such as a swing plate type, a scroll type, or a vane type may be used. Further, a compressor driven by an electric motor may be used.

The refrigerant used in the refrigeration cycle 10 is not particularly limited.
For the capacity control system, for example, the following modifications are possible.
When the discharge pressure Pd exceeds the set pressure Pds of the pressure sensor 340, since the capacity control valve 300 and the pressure sensor 340 are separated, the control target setting means 410 is the target of the Pd-Ps differential pressure. Although the target differential pressure ΔPset is set and the target of the control current I is set, the control target setting unit 410 may set a target of a physical quantity other than the Pd−Ps differential pressure as the control target value.

For example, when the capacity control valve 300 and the pressure sensor 340 are separated, the control target setting unit 410 sets a target suction pressure Pss that is a target value of the suction pressure Ps, and the suction pressure Ps is set to the target suction pressure Pss. The control current I may be adjusted so as to approach.
Specifically, if the above-described equation (4) is modified, the following equation (9) is obtained. Although there is a term including the discharge pressure Pd on the right side of the equation (9), the discharge pressure Pd can be detected by the pressure sensor 403. Therefore, equation (9) shows that the suction pressure Ps can be controlled if the discharge pressure Pd can be detected with reference to FIG. By transforming equation (9) and substituting target suction pressure Pss into suction pressure Ps, equation (10) is obtained. In Expression (10), Sv> Sr and fs1> fs2.

  In this case, the control target setting means 410 includes the evaporator outlet air temperature Te actually detected by the evaporator temperature sensor 402, and the evaporator target outlet air temperature Tes set by the evaporator target outlet air temperature setting means 401. The target suction pressure Pss as a control target can be set based on the deviation ΔT. Then, the target of the control current I is calculated from the target suction pressure Pss and the discharge pressure Pd detected by the pressure sensor 403 based on the equation (10), and the current adjusting unit 411 controls the control calculated by the control target setting unit 410. The control current I may be supplied to the coil 326 so as to approach the target of the current I. Even if the target suction pressure Pss is constant, if the discharge pressure Pd varies, the target of the control current I changes based on the equation (10). Therefore, the control current I in this case is not the control target value.

  According to this method, even if the pressure sensor 340 is separated from the transmission rod 311, the suction pressure Ps can be controlled as a control target. For this reason, the suction pressure Ps can be controlled regardless of the level of the discharge pressure Pd. According to this method, since the suction pressure Ps is controlled without substantially using the pressure sensor 340, the control range of the suction pressure Ps is wider than in the past.

It is a figure which shows schematic structure of the refrigerating cycle of the vehicle air conditioning system to which the capacity | capacitance control system which concerns on 1st Embodiment is applied with the longitudinal cross-section of a variable capacity | capacitance compressor. It is a figure for demonstrating the connection state of the capacity | capacitance control valve in the compressor of FIG. It is a figure which expands and shows the area | region III in FIG. FIG. 3 is an enlarged sectional view showing a pressure sensor and its vicinity in the capacity control valve of FIG. 2 in a state where the pressure sensor and the tip of a transmission rod are in contact with each other. It is sectional drawing which expands and shows the pressure sensor in the capacity | capacitance control valve of FIG. 2, and its vicinity in the state which the pressure sensor and the front-end | tip of a transmission rod are spaced apart. It is a graph which shows the relationship between the control current I and the Pd-Ps differential pressure | voltage in the capacity | capacitance control system of FIG. 1 in the state which the valve body and the pressure sensor are spaced apart. It is a graph which shows the relationship between the control current I and the suction pressure Ps in the capacity | capacitance control system of FIG. 1 in the state which the valve body and the pressure sensor connected. It is a block diagram which shows schematic structure of the capacity | capacitance control system of FIG. It is a block diagram for demonstrating schematic structure of the current adjustment means in the capacity | capacitance control system of FIG. It is a graph which shows the relationship between the control current I, the discharge pressure Pd, and the suction pressure Ps in the state which the valve body and the pressure sensor are spaced apart in the capacity | capacitance control system of a modification.

Explanation of symbols

140 Suction chamber (suction pressure range)
142 Discharge chamber (Discharge pressure area)
300B Solenoid unit 306 Valve body 340 Pressure sensor

Claims (9)

The displacement control valve is disposed in a communication path that connects the discharge pressure region of the variable capacity compressor and the control pressure chamber, and is a capacity control valve for adjusting the pressure of the control pressure chamber to control the discharge capacity of the variable capacity compressor. And
A solenoid unit;
The valve closing direction in which the pressure in the discharge pressure region of the variable capacity compressor acts in the valve opening direction, and the pressure in the suction pressure region of the variable capacity compressor and the electromagnetic force of the solenoid unit oppose the valve opening direction. A valve element that acts on
A pressure sensor in which the pressure in the discharge pressure region acts, and when the pressure in the discharge pressure region is lower than a set pressure, the pressure sensor is connected to the valve body and biased in the valve opening direction according to the pressure in the discharge pressure region And a pressure sensor that is separated from the valve body when the pressure in the discharge pressure region is larger than a set pressure.   The first pressure receiving area where the pressure in the discharge pressure region acts on the valve body is equal to or larger than the second pressure receiving area where the pressure in the suction pressure region of the variable capacity compressor acts on the valve body. The capacity control valve according to claim 1.   The capacity control valve according to claim 2, wherein the pressure sensor is arranged so that the pressure in the discharge pressure region acts in a direction in which the pressure sensor and the valve body oppose each other.   The capacity control valve according to claim 3, wherein the first pressure receiving area is set to be substantially equal to a third pressure receiving area on which the pressure in the discharge pressure region acts in the pressure sensor.   5. The capacity according to claim 1, wherein the pressure sensor is disposed in an area extending between the discharge pressure area and a valve hole of the capacity control valve in the communication path. Control valve. A housing in which a discharge chamber as the discharge pressure region, a crank chamber as the control pressure chamber, a suction chamber, and a cylinder bore are defined;
A piston disposed in the cylinder bore;
A drive shaft rotatably supported in the housing;
A conversion mechanism including a variable tilt angle swash plate element that converts rotation of the drive shaft into reciprocating interlocking of the piston;
A variable displacement compressor comprising the displacement control valve according to any one of claims 1 to 5. The capacity control valve according to any one of claims 1 to 5, an external information detection means for detecting external information, and a control target value based on the external information detected by the external information detection means. A control target setting unit; and a current adjusting unit that adjusts a current supplied to the solenoid unit based on a control target value set by the control target setting unit, and adjusting a pressure of the control pressure chamber. In the capacity control system of the variable capacity compressor that controls the discharge capacity of the variable capacity compressor by
The external information detection means includes discharge pressure detection means for detecting the pressure in the discharge pressure region,
When the pressure in the discharge pressure area detected by the discharge pressure detection means is lower than the set pressure, the control target setting means is a target suction pressure that is a target value of the pressure in the suction pressure area as the control target value. And the current adjusting means adjusts the current supplied to the solenoid unit based on the target suction pressure. When the pressure in the discharge pressure region detected by the discharge pressure detection unit is higher than the set pressure, the control target setting unit sets a target suction pressure, which is a target value of the pressure in the suction pressure region, to the control target value. And the current adjusting means adjusts the current supplied to the solenoid unit based on the pressure in the discharge pressure region detected by the discharge pressure detecting means and the target suction pressure. Item 8. The capacity control system for a variable capacity compressor according to Item 7. When the pressure in the discharge pressure region detected by the discharge pressure detection means is higher than the set pressure, the control target setting means sets a target value of the current supplied to the solenoid unit as the control target value. 8. The capacity control system for a variable capacity compressor according to claim 7, wherein the current adjusting means adjusts a current supplied to the solenoid unit so as to approach a target value of the current.

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