JP5046914B2 - Capacity control system for variable capacity compressor - Google Patents

Description

  The present invention relates to a capacity control system for a variable capacity compressor applied to an air conditioning system.

The discharge capacity control of the variable capacity compressor includes feedback control or a combination of feedback control and feedforward control, but the latter is usually selected for stabilization of the discharge capacity control.
The feedback control is represented by PI control or PID control. In the feedback control, for example, the capacity based on the deviation between the control amount and the target value so that the control amount such as the outlet air temperature of the evaporator approaches the set target value. A control current (control output value) supplied to the control valve is calculated.

In the feedforward control, the control output value is calculated from the target value and other parameters so that the control amount approaches the set target value.
More specifically, as a control combining feedback control and feedforward control, for example, a control method for a variable capacity compressor disclosed in Patent Document 1 is known. According to this control method, the switching compensation amount is added to the duty ratio control amount in conjunction with these switching settings when the evaporator air volume setting means is switched or when the blowing temperature setting means is switched.
Japanese Unexamined Patent Publication No. 1-121572

  The feedback control of the discharge capacity of the variable capacity compressor is to detect the control amount and then operate the control current supplied to the capacity control valve based on the detected control amount to bring the control amount close to the target value. is there. Therefore, in the feedback control, even if an external factor (disturbance) that disturbs the control occurs, the control output value cannot be adjusted or corrected in response to the disturbance unless the influence appears in the control amount. .

In the feedback control, by manipulating the control output value so as to correct the influence of the apparent disturbance, a state where the control output value fluctuates and does not converge, a so-called hunting state may occur. Thus, in feedback control, discharge volume control may become unstable due to disturbance.
Even if feedback control and feedforward control are combined, as long as feedback control is being performed, the discharge volume control becomes unstable due to disturbance.

  The present invention has been made based on the above-described circumstances, and an object thereof is to provide a capacity control system for a variable capacity compressor in which the frequency of feedback control is minimized and the discharge capacity is stably controlled.

  In order to achieve the above object, according to the present invention, the present invention is applied to a variable capacity compressor inserted together with a radiator, an expander and an evaporator in a circulation path through which a refrigerant circulates to constitute a refrigeration cycle of an air conditioning system. In a capacity control system that controls the discharge capacity of the variable capacity compressor by adjusting a control pressure so that the control amount of the air conditioning system approaches a target value, a control object detection means that detects the control amount, and an opening / closing operation An electromagnetic control valve capable of adjusting the control pressure; and a control device that calculates a discharge capacity control signal from the target value based on an arithmetic expression and supplies a control current corresponding to the discharge capacity control signal to the electromagnetic control valve; And the control device calculates the calculation formula based on a deviation between the control amount detected by the control target detection means and the target value only when a determination criterion is satisfied. Correctly, the determination criterion includes a condition that the discharge capacity of the variable capacity compressor includes a condition that the discharge capacity of the variable capacity compressor is continuously smaller than a maximum discharge capacity for a threshold time or longer. (Claim 1).

Preferably, the determination criterion further includes a condition that an average change rate of the control amount detected by the control target detection unit during the threshold time is equal to or less than an upper limit value (Claim 2).
Preferably, the apparatus further comprises an evaporator air flow detecting means for detecting the air flow to the evaporator, and the determination criterion is that the air flow of the evaporator detected by the evaporator air flow detecting means is not more than an upper limit value. (Claim 3).

Preferably, the determination criterion is a condition that an average value of the deviation between the target value set by the control target setting unit and the control amount detected by the control target detection unit is not less than a lower limit value. (Claim 4).
Preferably, further comprising a thermal load detection means for detecting the thermal load of the refrigeration cycle,
The control device includes: a target suction pressure setting unit that sets a target suction pressure that is a target of a suction pressure based on the target value and the thermal load detected by the thermal load detection unit; and the target suction pressure setting unit. A storage unit that stores a calculation formula for calculating the discharge capacity control signal from the set target suction pressure as the calculation formula, and a control amount that is detected by the control target detection unit, and is stored in the storage unit. And a correction means for correcting the calculation formula.

Preferably, the apparatus further comprises a rotation speed detection means for detecting a physical quantity corresponding to the rotation speed of the variable capacity compressor, wherein the target suction pressure setting means is the target value, the thermal load, and the rotation speed detection means. The target suction pressure is set based on the detected physical quantity (Claim 6).
Preferably, the arithmetic expression stored in the storage means is updated with the arithmetic expression corrected by the correcting means (claim 7).

Preferably, the threshold time is increased every time the arithmetic expression is corrected (claim 8).
Preferably, the correction amount of the arithmetic expression by the correcting means is limited within a range set based on the first arithmetic expression (claim 9).
Preferably, the electromagnetic control valve includes a pressure sensor that mechanically controls the control pressure in response to the suction pressure.

  Preferably, the electromagnetic control valve has a valve body in which the discharge pressure acts in a direction opposite to the suction pressure and the electromagnetic force of the solenoid unit.

  In the capacity control system of the variable capacity compressor according to claim 1 of the present invention, the control device detects the control object detecting means when the discharge capacity of the variable capacity compressor is continuously smaller than the maximum discharge capacity for a threshold time or more. The arithmetic expression is corrected based on the deviation between the control amount detected by the step and the target value. That is, the discharge capacity is feedback controlled only when a predetermined condition is satisfied, and the frequency of feedback control is reduced. As a result, according to this capacity control system, the instability of the discharge capacity is suppressed, and the discharge capacity is stably controlled.

Further, when the discharge capacity is continuously smaller than the maximum discharge capacity for the threshold time or more, the discharge capacity is controlled relatively stably. If the control current is adjusted based on the deviation between the control amount detected at this time and the target value, the deviation between the control amount and the target value is reduced, and the accuracy of capacity control is improved.
In the capacity control system of the variable capacity compressor according to claim 2, the determination criterion further includes a condition that an average rate of change in the threshold time of the control amount detected by the control target detection unit is equal to or less than an upper limit value. For this reason, the discharge capacity is feedback-controlled only under more limited conditions, and the frequency of feedback control is further reduced. As a result, according to this capacity control system, the destabilization of the discharge capacity is further suppressed, and the discharge capacity is controlled more stably.

Also, the discharge capacity is controlled relatively stably when the average rate of change of the control amount in the threshold time is equal to or less than the upper limit value. If the control current is adjusted based on the deviation between the control amount detected at this time and the target value, the deviation between the control amount and the target value is reduced, and the accuracy of capacity control is improved.
In the capacity control system of the variable capacity compressor according to the third aspect, the determination criterion further includes a condition that the air flow rate to the evaporator detected by the evaporator air flow rate detecting means is not more than the upper limit value. Therefore, the discharge capacity is feedback controlled only under more limited conditions, and the frequency of feedback control is further reduced. As a result, according to this capacity control system, the destabilization of the discharge capacity is further suppressed, and the discharge capacity is controlled more stably.

Further, when the amount of air blown to the evaporator is less than or equal to the upper limit value, the control amount is sufficiently close to the target value, and the discharge capacity is controlled relatively stably. If the control current is adjusted based on the deviation between the control amount detected at this time and the target value, the deviation between the control amount and the target value is reduced, and the accuracy of capacity control is improved.
In the capacity control system of the variable capacity compressor according to claim 4, the determination criterion further includes a condition that an average value in a threshold time of a deviation between the target value and the control amount is not less than a lower limit value. For this reason, the discharge capacity is feedback-controlled only under more limited conditions, and the frequency of feedback control is further reduced. As a result, according to this capacity control system, the destabilization of the discharge capacity is further suppressed, and the discharge capacity is controlled more stably.

Also, when the average value of the deviation between the target value and the control amount in the threshold time is below the lower limit value, the feedback capacity is not stable, and the discharge capacity becomes unstable while trying to reduce the deviation further. Is avoided. As a result, according to this capacity control system, instability of the discharge capacity is suppressed, and the discharge capacity is stably controlled.
The capacity control system of the variable capacity compressor according to claim 5 employs a suction pressure control system that controls the discharge capacity so that the suction pressure approaches the target suction pressure. Based on this, the target suction pressure is set. For this reason, even if the frequency of the feedback control is low, the control amount approaches the target value with certainty when the target suction pressure approaches the suction pressure.

In the capacity control system of the variable capacity compressor according to claim 6, the target intake pressure is accurately set based on the target value, the thermal load, and the physical quantity corresponding to the rotation speed of the variable capacity compressor. The deviation of the target value is further reduced.
In the capacity control system of the variable capacity compressor according to the seventh aspect, the deviation is surely reduced even if the frequency of the feedback control is low by updating the arithmetic expression whenever it is corrected.

In the capacity control system of the variable capacity compressor according to the eighth aspect, the threshold time becomes longer each time the arithmetic expression is corrected. As a result, according to this capacity control system, the frequency of feedback control is further reduced, and the discharge capacity is controlled more stably.
In the capacity control system of the variable capacity compressor according to claim 9, by limiting the correction amount of the arithmetic expression, for example, even if some abnormality occurs in the capacity control system, the arithmetic expression is greatly changed from the initial one. It is prevented.

In the capacity control system of the variable capacity compressor according to claim 10, although the frequency of feedback control by the control device is reduced, the discharge capacity is mechanically feedback controlled by the pressure sensor, so that the deviation between the control amount and the target value is achieved. Is reliably reduced.
According to the capacity control system of the variable capacity compressor of the eleventh aspect, when the suction pressure is viewed, the discharge capacity is stably controlled over a wide range.

Hereinafter, the capacity control system A of the variable capacity compressor according to the first 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, the compressor 100, the radiator (condenser or gas cooler) 14, the expander 16, and the evaporator 18 are sequentially inserted in the flow direction of the refrigerant, and when the compressor 100 is activated, the compressor 100 The refrigerant circulates through the circulation path 12 in accordance with the discharge capacity of the refrigerant.

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 radiator 14 has a function of cooling the refrigerant discharged from the compressor 100, and the cooled refrigerant is expanded by passing through the expander 16. The expanded refrigerant is vaporized in the evaporator 18, and the vaporized refrigerant is sucked into the compressor 100.

The evaporator 18 also constitutes a part of the air circuit of the vehicle air conditioning system, and the air flow passing through the evaporator 18 is cooled by taking heat of vaporization by the refrigerant in the evaporator 18. The vaporized refrigerant has a superheat degree at the outlet of the evaporator 18, but the superheat degree is substantially kept at a predetermined value by the expander 16.
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 102a to block the inside and the outside of the front housing 102 from each other. The drive shaft 106 is rotatably supported by bearings 117, 118, 119, and 120 in the radial direction and the thrust direction. Power from the engine 114 is transmitted to the pulley 112, and can rotate in synchronization with the rotation of the pulley 112.
A piston 130 is disposed in the cylinder bore 101a, and a tail portion protruding into the crank chamber 105 is formed integrally 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 140 and a discharge chamber 142 are defined in the rear housing 104, and the suction chamber 140 can communicate with the cylinder bore 101 a through a suction hole 103 a provided in the valve plate 103. 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, and the muffler casing 152 is joined to a muffler base 101b formed integrally with the cylinder block 101 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 a discharge passage 156 that passes through the rear housing 104, the valve plate 103, and the muffler base 101b.

  A discharge port 152a is formed in the muffler casing 152, and a check valve 170 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 170 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.

Accordingly, 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 intermittently connected by the check valve 170. 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) 200 is accommodated in the rear housing 104, and the capacity control valve 200 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 200 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 200 includes a valve unit and a solenoid unit. The valve unit has a cylindrical valve housing 202, and a valve hole 204 is formed in the valve housing 202. The valve hole 204 extends in the axial direction of the valve housing 202, and one end of the valve hole 204 is connected to the outlet port 206. The outlet port 206 passes through the valve housing 202 in the radial direction, and the valve hole 204 communicates with the crank chamber 105 via the outlet port 206 and the downstream portion of the air supply passage 160.

  A valve chamber 208 is defined on the solenoid unit side of the valve housing 202, and the other end of the valve hole 204 opens at the end wall of the valve chamber 208. A cylindrical valve body 210 is accommodated in the valve chamber 208, and the valve body 210 can move in the valve chamber 208 in the axial direction of the valve housing 202. When one end of the valve body 210 abuts against the end wall of the valve chamber 208, the valve body 210 can close the valve hole 204, and the end wall of the valve chamber 208 functions as a valve seat.

  An inlet port 212 is formed in the valve housing 202, and the inlet port 212 also penetrates the valve housing 202 in the radial direction. The inlet port 212 communicates with the discharge chamber 142 through the upstream portion of the air supply passage 160. The inlet port 212 opens at the peripheral wall of the valve chamber 208, and the discharge chamber 142 and the crank chamber 105 can communicate with each other through the inlet port 212, the valve chamber 208, the valve hole 204, and the outlet port 206.

  Furthermore, a pressure sensitive chamber 214 is defined in the valve housing 202 on the side opposite to the solenoid unit, and a pressure sensitive port 216 is formed on the peripheral wall of the pressure sensitive chamber 214. The pressure sensing chamber 214 communicates with the suction chamber 140 through the pressure sensing port 216 and the pressure sensing passage 166. An axial hole 218 is provided between the pressure sensitive chamber 214 and the valve hole 204, and the axial hole 218 extends coaxially with the valve hole 204.

  A pressure sensitive rod 220 is integrally and coaxially connected to the other end of the valve body 210. The pressure sensitive rod 220 extends through the valve hole 204 and the axial hole 218, and the tip of the pressure sensitive rod 220 protrudes into the pressure sensitive chamber 214. The pressure-sensitive rod 220 has a large-diameter portion on the distal end side, and the large-diameter portion of the pressure-sensitive rod 220 is slidably supported by the inner peripheral surface of the axial hole 218. Therefore, the airtightness between the pressure sensitive chamber 214 and the valve hole 204 is ensured by the large diameter portion of the pressure sensitive rod 220.

The end wall of the pressure sensitive chamber 214 is formed by a cap 222 that is press-fitted into the end of the valve housing 202, and the cap 222 has a stepped bottomed cylindrical shape. A cylindrical portion of the support member 224 is slidably fitted to the small diameter portion of the cap 222, and a forced release spring 226 is disposed between the bottom wall of the cap 222 and the support member 224.
A pressure sensor 228 is accommodated in the pressure sensing chamber 214, and one end of the pressure sensor 228 is fixed to the support member 224. Therefore, the cap 222 supports the pressure sensor 228 via the support member 224.

  The pressure sensor 228 has a bellows 230, and the bellows 230 can expand and contract in the axial direction of the valve housing 202. Both ends of the bellows 230 are hermetically closed by caps 232 and 234, and the inside of the bellows 230 is kept in a vacuum state (depressurized state). In addition, a compression coil spring 236 is disposed inside the bellows 230, and the compression coil spring 236 biases the caps 232 and 234 away from each other so that the bellows 230 extends.

The cap 234 of the pressure sensor 228 can come into contact with the pressure sensitive rod 220 via the adapter 238. When the pressure in the pressure sensitive chamber 214 decreases and the pressure sensitive device 228 expands, The valve body 210 is urged in the valve opening direction.
Note that the amount of press-fitting of the cap 222 to the valve housing 202 is adjusted so that the displacement control valve 200 performs a predetermined operation.

On the other hand, the solenoid unit has a cylindrical solenoid housing 240 coaxially connected to the valve housing 202, and a cylindrical fixed core 242 is disposed concentrically within the solenoid housing 240. One end portion of the fixed core 242 is fitted to the end portion of the valve housing 202 to partition the valve chamber 208 and supports the valve body 210 slidably.
A bottomed sleeve 244 is fitted into a portion extending from the center to the other end of the fixed core 242. A core housing space 246 is defined between the bottom wall of the sleeve 244 and the other end of the fixed core 242, and a movable core 248 is disposed in the core housing space 246. The movable core 248 is slidably supported by the sleeve 244 and can reciprocate in the axial direction of the solenoid housing 240.

  One end of a solenoid rod 250 extending in the fixed core 242 contacts the other end of the valve body 210, and the other end of the solenoid rod 250 is fixed integrally with the movable core 248. Therefore, the valve body 210 moves in the valve closing direction in conjunction with the movable core 248. A compression coil spring 252 is disposed between the movable core 248 and the bottom wall of the sleeve 244, and the compression coil spring 252 constantly urges the valve body 210 in the valve closing direction via the movable core 248 and the solenoid rod 250. To do.

  A cylindrical coil (solenoid coil) 254 wound around the bobbin 253 is disposed around the sleeve 244, and the bobbin 253 and the coil 254 are surrounded by an integrally molded resin member 255. The solenoid housing 240, the fixed core 242 and the movable core 248 are all formed of a magnetic material to constitute a magnetic circuit, while the sleeve 244 is formed of a nonmagnetic stainless steel material.

  Here, a radial hole 256 is formed at the root of the tip of the fixed core 242, and a communication hole 258 that connects the radial hole 256 and the pressure sensing chamber 214 is formed in the valve housing 202. Further, the inner diameter of the central portion and the other end portion of the fixed core 242 is larger than the outer diameters of the valve body 210 and the solenoid rod 250, and the central portion of the fixed core 242 is between the pressure sensing chamber 214 and the core housing space 246. And the inside of the other end part, it communicates via the radial hole 256 and the communication hole 258.

Accordingly, the pressure of the crank chamber 105 (crank pressure Pc) acts on one end surface of the valve body 210 as a force in the valve opening direction, while the pressure of the suction chamber 140 (suction pressure Ps) acts on the other end surface of the valve body 210. ) Acts as a force in the valve closing direction.
Note that by setting the area of the valve hole 204 equal to the cross-sectional area of the portion of the valve body 210 supported by the distal end portion of the fixed core 242, the opening and closing operation of the valve body 210 is performed in the valve chamber 208. The pressure, in other words, the pressure in the discharge chamber 142 (discharge pressure Pd) is not involved. In this case, the suction pressure control characteristic of the capacity control valve 200 is not affected by the discharge pressure Pd.

Further, by setting the area of the valve hole 204 equal to the step area of the portion of the pressure-sensitive rod 220 that slides with the axial hole 218, the pressure in the valve hole 204 is used for opening and closing the valve body 210. In other words, the pressure in the crank chamber 105 (crank pressure Pc) is not involved.
As a result, the suction pressure control characteristic of the capacity control valve 200 is substantially unaffected by the discharge pressure Pd and the crank pressure Pc. For this reason, as shown in FIG. 3, Formula (1) and Formula (2), based on the current (control current I) supplied to the coil 254, the target value (target suction pressure Pss) of the suction pressure Ps to be controlled. ) Is uniquely determined.

  In Formula (1), F (I) is an electromagnetic force acting on the movable core 248 by energizing the coil 254, and Sb is an effective area of the bellows 230. Further, fs1 is an urging force of the compression coil spring 252 and fs2 is an urging force of the compression coil spring 236 of the pressure sensor 228. F (I) = A · I (where A is a constant), and taking this relationship into account, transforming equation (1) yields equation (2).

A control device 400A provided outside the compressor 100 is connected to the coil 254, and when a control current I is supplied from the control device 400A to the coil 254, an electromagnetic force F (I) acts on the movable core 248. The movable core 248 is attracted toward the fixed core 242 by the electromagnetic force F (I), and thereby the valve body 210 is urged in the valve closing direction.
FIG. 4 is a block diagram showing a schematic configuration of the capacity control system A including the control device 400A.

The capacity control system A has external information detection means for detecting one or more external information, and the external information detection means is an evaporator temperature sensor as an evaporator target temperature setting means 401 and an evaporator outlet air temperature detection means. 402.
The evaporator target temperature setting means 401 is based on various external information including vehicle compartment temperature setting, and the target value (evaporator outlet air temperature Te) of the air temperature at the outlet of the evaporator 18 in the air circuit (evaporator outlet air temperature Te) A target outlet air temperature Tes) is set. The evaporator outlet air temperature Te is a control target (control amount) of the vehicle air conditioning system, and the evaporator temperature sensor 402 is a means for detecting the control target (control target detection means).

The evaporator target outlet air temperature Tes is a target value for the vehicle air conditioning system, and is also a final target value for the capacity control system A. The evaporator target temperature setting means 401 inputs the set evaporator target outlet air temperature Tes as one piece of external information to the control device 400A.
The evaporator temperature sensor 402 is installed at the outlet of the evaporator 18 in the air circuit (see FIG. 1), and detects the evaporator outlet air temperature Te. The detected evaporator outlet air temperature Te is input to the control device 400A as one piece of external information.

The external information detection means includes thermal load detection means for detecting the thermal load applied to the refrigeration cycle 10, and the thermal load detection means includes an outside air temperature sensor 403, a solar radiation sensor 404, and an evaporator fan voltage detection means 405. Have.
The outside air temperature sensor 403 is disposed at the outside air intake port of the vehicle and detects the temperature Ta of the outside air introduced into the air circuit of the vehicle air conditioning system.

The solar radiation sensor 404 is disposed on a dashboard in the vehicle cabin and detects the solar radiation amount Ws that passes through the windshield of the vehicle.
The evaporator fan voltage detection means 405 detects a voltage (fan voltage) VL supplied to a fan that generates an air flow in the air circuit. The fan voltage VL is a physical quantity corresponding to the amount of air blown to the evaporator 18, and the fan air blown amount to the evaporator 18 is indirectly detected based on the fan voltage VL.

  Further, the external information detection means includes vehicle driving state detection means for detecting the driving state of the vehicle, and the vehicle driving state detection means has a vehicle speed sensor 406. The vehicle speed sensor 406 detects the traveling speed VS of the vehicle. The vehicle speed sensor 406 can detect the number of revolutions of the engine 114 or the number of revolutions of the compressor 100, and the vehicle speed sensor 406 also functions as a thermal load detection unit.

The control device 400A is configured by, for example, an independent ECU (electronic control unit), and includes a target suction pressure setting unit 410, a control signal calculation unit 411, and a solenoid driving unit 412.
The target suction pressure setting means 410 calculates and sets the target suction pressure Pss. The target suction pressure Pss is a target value of the suction pressure Ps that is a control target.

  In the present embodiment, the target suction pressure setting means 410 includes an evaporator target outlet air temperature Tes set by the evaporator target temperature setting means 401, an outside air temperature Ta detected by the outside air temperature sensor 403, and a solar radiation sensor 404. The target suction pressure Pss is set based on the detected solar radiation amount Ws, the fan voltage VL detected by the evaporator fan voltage detection means, and the vehicle running speed VS detected by the vehicle speed sensor 406.

Specifically, the target suction pressure Pss is calculated by subtracting the first correction amount P1 from the reference pressure Pe and adding a second correction amount P2 described later. That is, the target suction pressure Pss is calculated by an arithmetic expression: Pss = Pe−P1 + P2.
Here, the reference pressure Pe is calculated by a function that includes the evaporator target outlet air temperature Tes as a variable: Pe = f (Tes). More specifically, the reference pressure Pe is set to be equal to the refrigerant saturation pressure at the evaporator target outlet air temperature Tes.

The first correction amount P1 is determined based on the heat load applied to the refrigeration cycle 10. That is, the first correction amount P1 is calculated by a function: P1 = g (Ta, Ws, VL, VS) including the outside air temperature Ta, the solar radiation amount Ws, the fan voltage VL, and the vehicle traveling speed VS as variables.
As shown in FIG. 5, if the heat load is large, the first correction amount P1 is also large, and if the heat load is small, the first correction amount P1 is set to zero. Therefore, when the heat load is small and the first correction amount P1 is zero, the target suction pressure Pss is equal to the value obtained by adding the second correction amount P2 to the reference pressure Pe.

The control signal calculation unit 411 calculates the control current I by substituting the target suction pressure Pss set by the target suction pressure setting unit 410 into the above equation (2). The calculated control current I is input to the solenoid driving means 412 as a discharge capacity control signal.
The solenoid drive unit 412 adjusts the current supplied to the coil 254 of the capacity control valve 200 so as to be equal to the control current I calculated by the control signal calculation unit 411. The adjustment of the control current I is performed by changing the duty ratio in PWM (pulse width modulation) at a predetermined drive frequency (for example, 400 to 500 Hz).

  FIG. 6 shows the configuration of the solenoid driving means 412. The solenoid driving means 412 has a switching element 430. The switching element 430 is inserted in series with the coil 254 of the capacity control valve 200 in a power supply line extending between the power supply 450 and the ground. The switching element 430 can electrically connect the power supply line, and the control current I is supplied to the coil 254 by PWM of a predetermined driving frequency by the operation of the switching element 430.

A diode 432 is connected in parallel with the coil 254 to form a flywheel circuit.
A predetermined drive signal is input to the switching element 430 from the control signal generating means 434, and the duty ratio in PWM is changed corresponding to this signal.
In addition, a current sensor 436 is inserted in the power supply line, and the current sensor 436 detects the control current I flowing through the coil 254.

  The current sensor 436 inputs the detected control current I to the control current comparison / determination unit 438, and the control current comparison / determination unit 438 receives the control current I input from the control signal calculation unit 411 as the discharge capacity control signal and the current sensor. The control current I detected by 436 is compared. Then, the control current comparison determination unit 438 changes the drive signal generated by the control signal generation unit 434 so that the detected control current I approaches the input control current I based on the comparison result.

  When the solenoid drive unit 412 adjusts the control current I with the duty ratio, the control signal calculation unit 411 may calculate the duty ratio as a parameter related to the control current I. In this case, the control signal calculation unit The discharge capacity control signal generated by 411 is a signal for causing the solenoid driving means 412 to supply the control current I at a predetermined duty ratio.

That is, the discharge capacity control signal may be a signal corresponding to the control current I or a signal corresponding to a parameter such as a duty ratio related to the control current I.
In addition, the control device 400A includes a storage unit 413. The storage unit 413 uses the arithmetic expression used by the target suction pressure setting unit 410 to calculate the target suction pressure Pss, the reference pressure Pe, and the first correction amount. Each of the arithmetic expressions used for calculating P1 is stored. The target suction pressure setting unit 410 reads the calculation formula stored in the storage unit 413 every time the target suction pressure Pss is calculated.

Further, the control device 400A includes a discharge capacity determination unit 414 and a correction unit 415.
The discharge capacity determination unit 414 determines whether the discharge capacity of the compressor 100 is the maximum discharge capacity or smaller than the maximum discharge capacity, and inputs the determination result to the correction unit 415.
The determination of the discharge capacity is performed by collating with a map prepared in advance using the evaporator target outlet air temperature Tes, the outside air temperature Ta, the solar radiation amount Ws, the fan voltage VL and the vehicle running speed VS as input values.

  When the discharge capacity is the maximum discharge capacity, an excessive control current I is normally supplied to the coil 254, and there is no correlation between the control current I and the discharge capacity. For this reason, when the discharge capacity is the maximum discharge capacity, it cannot be said that the discharge capacity is substantially controlled. Therefore, the determination of whether the discharge capacity of the compressor 100 is the maximum discharge capacity or smaller than the maximum discharge capacity means that the discharge capacity determination means is not in the control state or in the control state. Is to determine.

The correction means 415 calculates a temperature deviation ΔT between the evaporator target outlet air temperature Tes set by the evaporator target temperature setting means 401 and the evaporator outlet air temperature Te detected by the evaporator temperature sensor 402, and An average value (average temperature deviation ΔTm) of the temperature deviation ΔT during a predetermined threshold time ta is calculated.
Further, the correction unit 415 calculates an average change rate α of the evaporator outlet air temperature Te detected by the evaporator temperature sensor 402 during the threshold time ta. The average change rate α is a value obtained by dividing the change amount ΔTe of the evaporator outlet air temperature Te during the threshold time ta by the threshold time ta.

On the other hand, the determination result of the discharge capacity determination unit 414 is input to the correction unit 415.
The correction unit 415 corrects and updates the arithmetic expression of the target suction pressure Pss stored in the storage unit 413 only when a predetermined determination criterion is satisfied. Specifically, the second correction amount P2 included in the arithmetic expression is changed by the change amount ΔP2 only when a predetermined determination criterion is satisfied. The change amount ΔP2 is determined such that the deviation ΔT or the average temperature deviation ΔTm is reduced, and is calculated by, for example, a function including the average temperature deviation ΔTm as a variable: ΔP2 = h (ΔTm). This function: ΔP2 = h (ΔTm) can be obtained in advance.

The determination criteria include the following three conditions (i) to (iii).
(I) As a result of the determination by the discharge capacity determination means 414, the discharge capacity is continuously smaller than the maximum discharge capacity for the threshold time ta or longer.
(Ii) The average change rate α of the evaporator outlet air temperature Te during the threshold time ta is equal to or less than a predetermined upper limit value β.
(Iii) The average temperature deviation ΔTm during the threshold time ta is greater than or equal to a predetermined lower limit value γ.

Only when all the conditions (i) to (iii) are satisfied, the second correction amount P2 is changed by the change amount ΔP2, thereby correcting and updating the arithmetic expression of the target suction pressure Pss.
The update means that the arithmetic expression stored in the storage unit 413 is rewritten to the corrected arithmetic expression every time it is corrected. That is, the value after the second correction amount P2 is changed by the change amount ΔP2 is stored as the latest second correction amount P2.

The absolute value of the second correction amount P2 is limited to a predetermined upper limit value σ or less. For example, the upper limit value σ is set with reference to the target suction pressure Pss when the second correction amount P2 is zero.
The corrected arithmetic expression can be expressed as Pss = Pe−P1 + ΔP2 ₁ + ΔP2 ₂ assuming that correction is performed twice and the respective change amounts are ΔP2 ₁ and ΔP2 ₂ . Therefore, the arithmetic expression can also be expressed as the following expression (3). The initial value of the second correction amount P2 is zero, it is 0. The initial value [Delta] P2 ₀ changes the amount [Delta] P2 in the equation (3).

As can be seen from Equation (3), the second correction amount P2 can be defined as the sum of the change amounts ΔP2 of each correction.
Hereinafter, the operation (usage method) of the above-described vehicle air conditioning system will be described.
FIG. 7 shows a main routine of a program executed by the control device 400A. The main routine is started when, for example, the engine key of the vehicle is turned on, and is stopped when the vehicle is turned off.

In the main routine, first, initial conditions are set (S10). Specifically, the flag F is set to zero, the control current I to be supplied to the coil 254 is set to an initial value I _0. During the initial value I ₀ is supplied, the displacement control valve 200 is in the open state, the capacity of the compressor 100 is the smallest volume that is mechanically determined. The initial value I ₀ may be zero.

  When the capacity of the compressor 100 is minimum, the pressure difference before and after the check valve 170 is lower than a predetermined value, and the compressor 100 cannot discharge the refrigerant to the refrigeration cycle 10. For this reason, the refrigerant discharged from the cylinder bore 101a to the discharge chamber 142 with the minimum discharge capacity flows into the crank chamber 105 from the discharge chamber 142 via the air supply path 160, and then sucked from the crank chamber 105 via the extraction passage 162. Return to chamber 140. That is, when the capacity of the compressor 100 is minimum, the refrigerant circulates inside the compressor 100.

  After S10, it is determined whether or not the air conditioner switch (A / C switch) of the vehicle air conditioning system is on (S12). That is, it is determined whether or not the occupant is requesting cooling or dehumidification of the passenger compartment. If the air conditioner switch is on (Yes), the external information detected by the external information detecting means is read (S14). That is, the evaporator target outlet air temperature Tes set by the evaporator target temperature setting means 401, the evaporator outlet air temperature Te detected by the evaporator temperature sensor 402, the outside air temperature Ta detected by the outside air temperature sensor 403, The solar radiation amount Ws detected by the solar radiation sensor 404, the fan voltage VL detected by the evaporator fan voltage detection means 405, and the vehicle speed VS detected by the vehicle speed sensor 406 are read.

Based on the external information read in S14, the target suction pressure setting means 410 calculates the reference pressure Pe and the first correction amount P1 (S16), and then executes the target suction pressure setting routine S18 to execute the target suction pressure. The pressure Pss is calculated.
Based on the target suction pressure Pss calculated in the target suction pressure setting routine S18, the control signal calculation unit 411 calculates the control current I to be supplied to the coil 254 (S20). Then, the control signal calculation means 411 compares and determines whether or not the calculated control current I is greater than or equal to a predetermined lower limit value Imin (S22). When the control current I is smaller than the lower limit value Imin, the control signal calculation unit 411 reads the lower limit value Imin as the control current I (S24) and outputs the lower limit value Imin as the control current I (S26). The control current I output in S26 is input to the solenoid driving unit 412, and the control current I supplied to the coil 254 is adjusted by the solenoid driving unit 412.

  On the other hand, when the calculated control current I is equal to or greater than the lower limit value Imin in the determination result of S22, the control signal calculation means 411 compares / determines whether the calculated control current I is equal to or less than the predetermined upper limit value Imax. (S28). When the control current I exceeds the upper limit value Imax, the control signal calculation unit 411 reads the upper limit value Imax as the control current I (S30), and outputs the upper limit value Imax as the control current I (S26).

If the calculated control current I is less than or equal to the upper limit value Imax in the determination result of S28, the control signal calculation unit 411 outputs the control current I calculated in S20 (S26).
After S26, the program returns to S12, but if the air conditioner switch is OFF (No) in S12, it is determined whether or not the flag F is 1 (S32). If the flag F is 1 in S32, the flag F is set to zero and the timer is reset (S34). Also, if the flag F in S32 is 1, the initial value _{I 0} is read again (S36), the initial value _{I 0} is output as the control current I as a control current I (S26).

On the other hand, if it is zero rather than the flag F is 1 in step S32, the control current I remains the initial value I _0, the initial value I ₀ is output as the control current I (S26).
FIG. 8 is a flowchart showing details of the target suction pressure calculation routine S18.
In the target suction pressure calculation routine S18, it is first determined whether or not the flag F is 1 (S100). Since the initial value of the flag F is zero, the first determination result of S100 is always No. If the determination result in S100 is No, the timer is started, the elapsed time t is measured (S102), and the flag F is set to 1 (S104).

Thereafter, the difference (temperature deviation ΔT) between the evaporator target outlet air temperature Tes set by the evaporator target temperature setting means 401 and the evaporator outlet air temperature Te detected by the evaporator temperature sensor 402 is calculated ( S106). Further, it is determined by the discharge capacity determining means 414 whether or not the discharge capacity of the compressor 100 is the maximum discharge capacity (S108).
Regarding the determination of the discharge capacity in S108, the discharge capacity determination means 414 maps the evaporator target outlet air temperature Tes, the outside air temperature Ta, the solar radiation amount Ws, the evaporator fan voltage VL and the vehicle speed VS inputted to itself. By matching with.

  Then, it is determined whether or not the elapsed time t from the start of the timer in S102 is less than a predetermined threshold time ta, that is, whether or not the time is up (S110), and the elapsed time t is less than the threshold time ta The target suction pressure Pss is calculated by a predetermined calculation formula: Pss = Pe−P1 + P2 (S112). Note that the initial value of the second correction amount P2 is zero. When the target suction pressure Pss is calculated in S112, the process returns from the target suction pressure calculation routine S18 to S20 of the main routine.

  On the other hand, when the elapsed time t is equal to or greater than the threshold time ta in S110, the timer is reset (S113) and the flag F is set to zero (S114). Further, the average temperature deviation ΔTm is calculated as the average value of the temperature deviation ΔT during the threshold time ta (S116), and the average change rate α of the evaporator outlet air temperature Te during the threshold time ta is calculated. (S118).

More specifically, the target suction pressure calculation routine S18 is repeatedly executed, and the temperature deviation ΔT is calculated at S105 each time. The average temperature deviation ΔTm is an arithmetic average of the temperature deviation ΔT repeatedly calculated during the threshold time ta.
On the other hand, the average change rate α is the difference between the evaporator outlet air temperature Te read in S12 immediately before the timer start in S102 and the evaporator outlet air temperature Te read in S12 immediately before the time up in S110. , A value obtained by dividing by the threshold time ta.

After S118, it is determined whether or not to correct the arithmetic expression of the target suction pressure Pss (S120). In the present embodiment, the arithmetic expression is corrected only when the determination criterion is satisfied, that is, when all of the above three conditions (i) to (iii) are met.
When it is determined in S120 that the arithmetic expression of the target suction pressure Pss is to be corrected, the correction unit 415 calculates the change amount ΔP2 of the second correction amount P2 in the arithmetic expression (S122). Specifically, the correction unit 415 calculates the change amount ΔP2 based on a function: ΔP2 = h (ΔTm) including the average temperature deviation ΔTm as a variable so that the average temperature deviation ΔTm is reduced.

  The correction unit 415 preferably has a provisional value obtained by adding the change amount ΔP2 to the current second correction amount P2 stored in the storage unit 413, less than a predetermined lower limit value −σ, or a predetermined upper limit. It is determined whether the value σ is exceeded or the lower limit value −σ is equal to or greater than the upper limit value σ (S124). As a result of the determination in S124, when the provisional value is not less than the lower limit value −σ and not more than the upper limit value σ, the second correction amount P2 stored in the storage unit 413 is updated to the provisional value calculated in S122. (S126) The target suction pressure Pss is calculated based on the updated calculation formula (S112).

On the other hand, if the result of determination in S124 is that the provisional value is less than the lower limit value −σ, the second correction amount P2 stored in the storage means 413 is updated to the lower limit value −σ (S128), and the provisional value is If the upper limit value σ is exceeded, the second correction amount P2 stored in the storage means 413 is updated to the upper limit value σ (S130).
That is, it is preferable that the second correction amount P2 is limited to a range between the lower limit value −σ and the upper limit value σ. Here, σ of the upper limit value σ is a positive value, and is preferably set based on the sum of the reference pressure Pe and the first correction amount P1.

The updated second correction amount P2 is maintained in the storage unit 413 even when the power of the control device 400A is turned off and the main routine is stopped, and is used when the main routine is restarted.
The capacity control system B according to the second embodiment of the present invention will be described below.
The capacity control system B controls the discharge capacity of the compressor 100 using the capacity control valve 300 shown in FIG. 9 instead of the capacity control valve 200.

  More specifically, the capacity control valve 300 includes a valve unit and a drive unit that opens and closes the valve unit. The valve unit has a cylindrical valve housing 301, and an inlet port (valve hole 301 a) is formed at one end of the valve housing 301. The valve hole 301 a communicates with the discharge chamber 142 via the upstream portion of the air supply passage 160 and opens to the valve chamber 303 defined inside the valve housing 301.

A cylindrical valve body 304 is accommodated in the valve chamber 303. The valve body 304 can move in the valve chamber 303 in the axial direction of the valve housing 301, and can close the valve hole 301 a by contacting the end face of the valve housing 301. That is, the end surface of the valve housing 301 functions as a valve seat.
Further, an outlet port 301 b is formed on the outer peripheral surface of the valve housing 301, and the outlet port 301 b communicates with the crank chamber 105 through a downstream portion of the air supply passage 160. The outlet port 301b also opens into the valve chamber 303, and the discharge chamber 142 and the crank chamber 105 can communicate with each other through the valve hole 301a, the valve chamber 303, and the outlet port 301b.

  The drive unit has a cylindrical solenoid housing 310, and the solenoid housing 310 is coaxially connected to the other end of the valve housing 301. The open end of the solenoid housing 310 is closed by an end cap 312, and a cylindrical coil (solenoid coil) 316 wound around a bobbin 314 is accommodated in the solenoid housing 310.

Further, a concentric cylindrical fixed core 318 is accommodated in the solenoid housing 310, and the fixed core 318 extends from the valve housing 301 toward the end cap 312 to the center of the coil 316. The end cap 312 side of the fixed core 318 is surrounded by a sleeve 320, and the sleeve 320 has a closed end on the end cap 312 side.
The fixed core 318 has an insertion hole 318 a at the center, and one end of the insertion hole 318 a opens into the valve chamber 303. Further, a movable core accommodating space 324 for accommodating the cylindrical movable core 322 is defined between the fixed core 318 and the closed end of the sleeve 320, and the other end of the insertion hole 318a is opened to the movable core accommodating space 324. is doing.

  A solenoid rod 326 is slidably inserted into the insertion hole 318a, and a valve body 304 is integrally and coaxially connected to one end of the solenoid rod 326. The other end of the solenoid rod 326 projects into the movable core housing space 324, and the other end of the solenoid rod 326 is fitted into a through-hole formed in the movable core 322 so that the solenoid rod 326 and the movable core 322 are integrated. Has been. An open spring 328 is disposed between the stepped surface of the movable core 322 and the end surface of the fixed core 318, and a predetermined gap is secured between the movable core 322 and the fixed core 318.

The movable core 322, the fixed core 318, the solenoid housing 310, and the end cap 312 are made of a magnetic material and constitute a magnetic circuit. The sleeve 320 is made of a non-magnetic stainless steel material.
A pressure-sensitive port 310 a is formed in the solenoid housing 310, and a suction chamber 140 is connected to the pressure-sensitive port 310 a through a pressure-sensitive passage 166. A pressure-sensitive groove 318b extending in the axial direction is formed on the outer peripheral surface of the fixed core 318, and the pressure-sensitive port 310a and the pressure-sensitive groove 318b communicate with each other. Accordingly, the suction chamber 140 and the movable core housing space 324 communicate with each other through the pressure-sensitive port 310a and the pressure-sensitive groove 318b, and the suction chamber 140 is arranged in the valve closing direction on the back side of the valve body 304 via the solenoid rod 326. , That is, the suction pressure Ps acts.

A control device 400B provided outside the compressor 100 is connected to the coil 316, and when the control current I is supplied from the control device 400B, the coil 316 generates an electromagnetic force G (I). The electromagnetic force G (I) of the coil 316 attracts the movable core 322 toward the fixed core 318 and acts on the valve body 304 in the valve closing direction.
In the capacity control valve 300, preferably, when the valve body 304 closes the valve hole 301a, the pressure in the discharge chamber 142, that is, the pressure receiving area of the valve body 304 on which the discharge pressure Pd acts (referred to as the seal area Sv). And the area of the valve body 304 on which the suction pressure Ps acts, that is, the cross-sectional area of the solenoid rod 326 is formed to be equal.

  In this case, the pressure of the crank chamber 105, that is, the crank pressure Pc substantially does not act on the valve body 304 in the opening / closing direction. Accordingly, the force acting on the valve body 304 is the discharge pressure Pd, the suction pressure Ps, the electromagnetic force G (I) of the coil 316, and the biasing force fs3 of the release spring 328, and the discharge pressure Pd and the release spring 328 The urging force fs3 acts in the valve opening direction, and the other suction pressure Ps and the electromagnetic force G (I) of the coil 316 act in the valve closing direction opposite to the valve opening direction.

  This relationship is expressed by Expression (4), and Expression (5) is obtained by transforming Expression (4). From these equations (4) and (5), it is understood that the suction pressure Ps is determined if the discharge pressure Pd and the electromagnetic force G (I), that is, the control current I are determined. Note that G (I) = B · I (B is a constant).

  Based on such a relationship, as shown in FIG. 10 and formula (6), the target suction pressure Pss is determined in advance as the target value of the suction pressure Ps, and is generated if information on the changing discharge pressure Pd is known. The power electromagnetic force G (I), that is, the control current I can be calculated. If the control current I supplied to the coil 316 is adjusted to be equal to the calculated control current I, the valve body 304 operates so that the suction pressure Ps approaches the target suction pressure Pss, and the crank pressure Pc is reduced. Adjusted. That is, the discharge capacity is controlled so that the suction pressure Ps approaches the target suction pressure Pss.

  In the control in which the suction pressure Ps is brought close to the target suction pressure Pss as described above, referring to FIG. 10, the target suction pressure is determined according to the level of the discharge pressure Pd from the minimum discharge pressure Pdmin to the maximum discharge pressure Pdmax. The set range of Pss, in other words, the control range of the suction pressure Ps can be slid up and down. That is, the control range of the suction pressure Ps at the arbitrary discharge pressure Pd1 is slid to the higher side than the control range of the suction pressure Ps at the discharge pressure Pd2 lower than the discharge pressure Pd1. For this reason, according to the capacity control system B, the discharge capacity can be controlled even in a region where the heat load is high.

  It can also be seen from equation (5) that if the seal area Sv is set small, the control range of the target suction pressure Pss at any discharge pressure Pd can be expanded with a small electromagnetic force G (I). If the synergistic effect of the slide of the control range of the target suction pressure Pss and the expansion of the control range is exhibited, the control range of the target suction pressure Pss is greatly expanded. Therefore, according to the capacity control system B, the discharge capacity control can be performed immediately after the compressor 100 is started even in a region where the heat load is high.

Note that the suction pressure Ps can be reduced by increasing the amount of current supplied to the coil 316. On the other hand, if the energization amount to the coil 316 is zero, the valve body 304 is separated by the biasing force fs3 of the opening spring 328 and the valve hole 301a is forcibly opened. As a result, the refrigerant is introduced from the discharge chamber 142 into the crank chamber 105, and the discharge capacity is kept to a minimum.
FIG. 11 is a block diagram showing a schematic configuration of a capacity control system B including the control device 400B.

The capacity control system B is different from the capacity control system A in that it has a pressure sensor 451 and a pressure correction means 452, and has a control signal calculation means 453 instead of the control signal calculation means 411. Therefore, hereinafter, the pressure sensor 451, the pressure correction unit 452, and the control signal calculation unit 453 will be described.
In the capacity control system B, the external information detection means includes a discharge pressure detection means, and the discharge pressure detection means has a pressure sensor 451 constituting a part thereof. The discharge pressure detection means is a means for detecting the discharge pressure Pd that is the pressure of the refrigerant in the discharge chamber 142. The pressure sensor 451 is mounted on the inlet side of the radiator 14 (see FIG. 1), detects the refrigerant pressure (hereinafter referred to as a detected pressure Ph) at the part, and inputs the detected pressure to the pressure correction means 452 of the control device 400B.

  The discharge pressure Pd and the detection pressure Ph are discharge pressures in the general sense of the pressure in the discharge pressure region of the refrigeration cycle 10. The discharge pressure region of the refrigeration cycle 10 refers to a region from the discharge chamber 142 to the inlet of the radiator 14. The high pressure region of the refrigeration cycle 10 refers to a region from the discharge chamber 142 to the inlet of the expander 16. The pressure sensor 451 only needs to be able to detect the pressure of the refrigerant at any part of the high pressure region.

On the other hand, the suction pressure region of the refrigeration cycle 10 refers to a region extending from the outlet of the evaporator 18 to the suction chamber 140. The discharge pressure region and the high pressure region also include a cylinder bore 101a in the compression process, and the suction pressure region also includes a cylinder bore 101a in the suction process.
The pressure correcting means 452 constitutes a discharge pressure detecting means together with the pressure sensor 451, and calculates the discharge pressure Pd by correcting the detected pressure Ph detected by the pressure sensor 451. Then, the pressure correction unit 452 inputs the calculated discharge pressure Pd to the control signal calculation unit 453.

The reason why the detection pressure Ph is corrected in this manner is that the refrigerant pressure differs between the discharge chamber 142 and the inlet of the radiator 14 even in the same discharge pressure region, particularly when the heat load is large. It is. The discharge pressure Pd can be calculated by a function Pd = j (Ph) using the detected pressure Ph as a variable. The function j (Ph) can be obtained in advance.
The control signal calculation unit 453 calculates the control current I based on the target suction pressure Pss set by the target suction pressure setting unit 410 and the discharge pressure Pd calculated by the pressure correction unit 452. At this time, the control signal calculation means 453 can calculate the control current I based on the above-described equation (6).

FIG. 12 shows a main routine executed by the capacity control system B. In the main routine of the capacity control system B, the same steps as the main routine of the capacity control system A are denoted by the same reference numerals including the target suction pressure calculation routine S18, and the description thereof is omitted.
In the main routine of the capacity control system B, the detected pressure Ph detected by the pressure sensor 451 is further read in the sensor input reading step S37. Then, the pressure correction means 452 calculates the discharge pressure Pd from the detected pressure Ph (S38). The discharge pressure calculation step (S38) may be executed between the sensor input reading step S37 and the control current calculation step S44.

  Further, in the main routine of the capacity control system B, it is compared and determined whether or not the target suction pressure Pss calculated in the target suction pressure calculation routine S18 is equal to or higher than a predetermined lower limit value PssL (S40). When the target suction pressure Pss is less than the lower limit value PssL, the lower limit value PssL is read as the target suction pressure Pss (S42), and the control signal calculation means 453 controls by substituting the target suction pressure Pss and the discharge pressure Pd into the calculation formula. The current I is calculated (S44).

  In S40, when the target suction pressure Pss calculated in the target suction pressure calculation routine S18 is equal to or higher than the lower limit value PssL, it is compared and determined whether or not the calculated target suction pressure Pss is equal to or lower than a predetermined upper limit value PssH ( S46). If the target suction pressure Pss exceeds the upper limit value PssH in S46, the upper limit value PssH is read as the target suction pressure Pss (S48), and the control signal calculation means 453 calculates the target suction pressure Pss and the discharge pressure Pd using the calculation formulas. And the control current I is calculated (S44).

In S46, if the target suction pressure Pss calculated in the target suction pressure calculation routine S18 is equal to or lower than the upper limit value PssH, the target suction pressure Pss calculated in the target suction pressure calculation routine S18 and the discharge pressure calculation step S38 are calculated. The control current I is calculated by substituting the discharge pressure Pd into the calculation formula (S44).
In the capacity control systems A and B of the variable capacity compressor 100 described above, the control devices 400A and 400B are based on the evaporator outlet air temperature Te detected by the evaporator temperature sensor 402 only when the determination criterion is satisfied. The calculation formula of the target suction pressure Pss is corrected. That is, the discharge capacity is basically feedforward controlled, and is feedback controlled only when the criterion is satisfied.

As a result, according to the capacity control systems A and B, the frequency of feedback control is reduced, the instability of the discharge capacity is suppressed, and the discharge capacity is stably controlled.
Further, as one condition (i) included in the determination criterion, when the discharge capacity is continuously smaller than the maximum discharge capacity for the threshold time ta or more, the discharge capacity is controlled relatively stably. If the control current I is adjusted based on the deviation ΔT between the evaporator outlet air temperature Te and the evaporator target outlet air temperature Tes detected at this time, the deviation ΔT is reduced and the accuracy of capacity control is improved.

  In the capacity control systems A and B described above, the determination criterion is the condition (ii) that the average rate of change α at the threshold time ta of the evaporator outlet air temperature Te detected by the evaporator temperature sensor 402 is equal to or less than the upper limit value. In addition. For this reason, compared to when the criterion includes only one condition (i), the discharge capacity is feedback-controlled only under more limited conditions, and the frequency of feedback control is further reduced.

As a result, according to the capacity control systems A and B, the instability of the discharge capacity is further suppressed, and the discharge capacity is controlled more stably.
Further, when the average change rate α of the evaporator outlet air temperature Te at the threshold time ta is equal to or lower than the upper limit value β, the discharge capacity is controlled relatively stably. If the control current I is adjusted based on the deviation ΔT between the evaporator outlet air temperature Te and the evaporator target outlet air temperature Tes detected at this time, the deviation ΔT is reduced and the accuracy of capacity control is improved.

In the capacity control systems A and B described above, the criterion is that the average value ΔTm in the threshold time ta of the deviation Δ between the evaporator target outlet air temperature Tes and the evaporator outlet air temperature Te is not less than the lower limit value γ ( further includes iii). For this reason, the discharge capacity is feedback-controlled only under more limited conditions, and the frequency of feedback control is further reduced.
As a result, according to the capacity control systems A and B, the instability of the discharge capacity is further suppressed, and the discharge capacity is controlled more stably.

  In addition, when the average value of the deviation ΔT in the threshold time ta, that is, the average temperature deviation ΔTm is below the lower limit value γ, feedback control is not performed, so that the discharge capacity is unstable while trying to reduce the deviation ΔT further. The situation of becoming is avoided. As a result, according to the capacity control systems A and B, the instability of the discharge capacity is suppressed, and the discharge capacity is stably controlled.

  Although the capacity control systems A and B described above employ a suction pressure control system that controls the discharge capacity so that the suction pressure Ps approaches the target suction pressure Pss, the evaporator target outlet air temperature Tes and the refrigeration cycle 10 are controlled. A target suction pressure Pss is set based on the heat load. For this reason, even if the frequency of the feedback control is low, the evaporator outlet air temperature Te reliably approaches the evaporator target outlet air temperature Tes when the target suction pressure Pss approaches the suction pressure Ps.

In the capacity control systems A and B, in addition to the evaporator target outlet air temperature Tes and the heat load applied to the refrigeration cycle 10, the target suction pressure is also based on the vehicle speed VS as a physical quantity corresponding to the rotation speed of the compressor 100. Pss is set correctly. As a result, the deviation ΔT is further reduced.
In the capacity control systems A and B described above, the deviation ΔT is reliably reduced even when the frequency of the feedback control is low, by updating each time the arithmetic expression is corrected.

In the capacity control systems A and B described above, since the second correction amount P2 is limited within a predetermined range, for example, even if some abnormality occurs in the capacity control systems A and B, the arithmetic expression is changed from the initial one. Large changes are prevented.
In the capacity control system A described above, the frequency of feedback control is reduced, but the deviation ΔT is reliably reduced by mechanically feedback controlling the discharge capacity by the pressure sensor 228.

According to the capacity control system B described above, the discharge capacity is stably controlled over a wide range when the suction pressure Ps is viewed. That is, in the capacity control system B, the suction pressure Ps and the electromagnetic force G (I) of the coil 316 are opposed to the discharge pressure Pd acting on the valve body 304, so that the control range of the suction pressure Ps is limited. wide.
The present invention is not limited to the first and second embodiments described above, and various modifications are possible.

In the first embodiment and the second embodiment, in the calculation formula update determination step S120 of the target suction pressure calculation routine S18, the above-described conditions (i) to (iii) are used as the determination criteria for determining whether or not to update the calculation formula. However, it is sufficient that at least the condition (i) is included.
Therefore, the criteria include (i) alone, a combination of (i) and (ii), a combination of (i) and (iii), and a combination of (i), (ii) and (iii). There are four ways. Each of these four determination criteria may further include a condition that the fan voltage VL detected by the evaporator fan voltage detection means 405 is not more than a predetermined upper limit value.

  The condition that the evaporator fan voltage VL is equal to or lower than the upper limit value is the same as the condition that the air flow rate to the evaporator 18 is equal to or lower than the upper limit value, and the air flow rate to the evaporator 18 is equal to or lower than the upper limit value. Such a condition may be included in the criterion. When the amount of air blown to the evaporator 18 is small, the heat load on the refrigeration cycle 10 is small, and the calculation error of the first correction amount P1 is also small. For this reason, the suction pressure Ps can be accurately brought close to the target suction pressure Pss by updating the second correction amount P2.

  In the first embodiment and the second embodiment, whether or not to update the arithmetic expression of the target suction pressure Pss is determined every predetermined threshold time ta, but every time the arithmetic expression is updated, the threshold time ta May be lengthened. By updating the arithmetic expression, the offset between the target evaporator air outlet temperature Tes that is the target value and the evaporator outlet air temperature Te that is the control target is reduced, and the evaporator target outlet air temperature Tes is reduced to the evaporator outlet air temperature Tes. Te agrees well. For this reason, it is not necessary to frequently determine update, and the discharge capacity is further stabilized by increasing the threshold time ta and further reducing the frequency of feedback control.

  In the first embodiment and the second embodiment, the controlled object is the evaporator outlet air temperature Te, but the controlled object is not limited to this. For example, the control target is the pressure of the refrigerant in the high pressure region of the refrigeration circuit 10, the temperature of the refrigerant in the high pressure region, the temperature of the cylinder block 101 of the compressor 100, the temperature of the front housing 102 or the rear housing 104 (housing temperature), The driving torque may be used.

In 1st Embodiment and 2nd Embodiment, although the outdoor temperature Ta, the solar radiation amount Ws, and the evaporator fan voltage VL were detected as information (thermal load information) about the thermal load concerning the refrigerating cycle 10, thermal load information is It is not limited to these.
For example, as the heat load information, outside air humidity, various settings of the vehicle air conditioning system (inside / outside air switching door position, inside temperature setting, outlet position, air mix door position), inside temperature, inside humidity, evaporator inlet air temperature, You may detect the evaporator inlet air humidity, the surface temperature of each part of a vehicle interior, the pressure or humidity of a high pressure area or a low pressure area, the number of passengers of a vehicle, and the like. However, in order to detect the thermal load with high accuracy, the thermal load detection means preferably includes at least the outside air temperature sensor 403 and the evaporator fan voltage detection means 405.

In the first embodiment and the second embodiment, the vehicle speed sensor 406 is used as a means for detecting the rotational speed of the engine 114 or the compressor 100. However, the means for directly detecting the rotational speed of the engine 114 or the compressor 100 is used. Also good.
In the first embodiment and the second embodiment, the solenoid driving unit 412 has the current sensor 436 to detect the control current I supplied to the coils 254 and 316. However, the arrangement of the current sensor 436 is as follows. There is no particular limitation as long as the control current I can be detected. Further, as long as the control current I can be detected, other means such as a voltmeter may be used instead of the current sensor 436.

  Further, the solenoid driving means 412 may not have a means for detecting the control current I. In this case, a correlation between the target suction pressure Pss or the control current I and the duty ratio for driving the switching element 430 may be obtained in advance. Then, based on the correlation, the control signal calculation unit 411 calculates a duty ratio from the target suction pressure Pss or the control current I, and the calculated duty ratio may be input to the solenoid drive unit 412.

In the first embodiment and the second embodiment, the control devices 400A, B of the capacity control systems A, B are independent, but the control devices 400A, B are used as an air conditioner ECU that controls the operation of the entire air conditioning system. You may comprise as a part.
In the first embodiment, the discharge pressure Pd and the crank pressure Pc are not applied in the opening / closing direction to the valve body 210 of the capacity control valve 200, but the discharge pressure Pd or the crank pressure Pc in the opening / closing direction is applied to the valve body. You may use the capacity control valve which acts.

In the second embodiment, the discharge pressure Pd and the suction pressure Ps act in the opening / closing direction on the valve body 304 of the capacity control valve 300. However, the capacity control valve on which the crank pressure Pc further acts on the valve body is provided. It may be used.
The compressor 100 to which the capacity control systems A and B of the first and second embodiments are applied is a clutchless compressor, but the capacity control systems A and B are also applied to a compressor equipped with an electromagnetic clutch. Is possible. Although the compressor 100 is a swash plate type reciprocating compressor, it may be a rocking plate type reciprocating compressor. The oscillating plate compressor has an element for oscillating the oscillating plate. The swash plate 107 and these elements are collectively referred to as a swash plate element. The compressor 100 may be driven by an electric motor.

Further, the capacity control systems A and B can be applied to a scroll type or vane type variable capacity compressor. That is, any variable displacement compressor can be used as long as the control pressure for changing the discharge capacity can be changed by the valve opening of the capacity control valve using the capacity control valve in which the electromagnetic force of the solenoid unit acts on the valve body. Applicable.
The control pressure is the crank chamber pressure (crank pressure Pc) in the case of a reciprocating compressor.

In the compressor 100 to which the capacity control systems A and B of the first and second embodiments are applied, in order to increase the crank pressure Pc by regulating the flow rate of the extraction passage 162, a fixed orifice as a throttle element is provided in the extraction passage 162. Although 103c is arranged, a throttle with variable flow rate may be used as the throttle element, or a valve may be arranged to adjust the valve opening.
In the capacity control systems A and B of the first and second embodiments, the capacity control valves 200 and 300 are disposed in the air supply passage 160 that connects the discharge chamber 142 and the crank chamber 105. In the case of the swash plate type or the oscillating plate type, the capacity control valves 200 and 300 are not disposed in the air supply passage 160, but the capacity control valve is disposed in the bleed passage 162 connecting the crank chamber 105 and the suction chamber 140. Also good. That is, the present invention is not limited to the inlet control that controls the opening degree of the air supply passage 160, and may be the outlet control that controls the opening degree of the extraction passage 162.

In the refrigeration cycle 10 to which the capacity control systems A and B of the first and second embodiments are applied, the refrigerant is not limited to R134a or carbon dioxide, and other new refrigerants may be used. That is, the capacity control systems A and B can be applied to a conventional air conditioning system.
Finally, the capacity control system of the variable capacity compressor according to the present invention is applicable to air conditioning systems in general, such as indoor air conditioning systems other than vehicle air conditioning systems.

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 of 1st Embodiment is applied with the longitudinal cross-section of a variable capacity | capacitance compressor. It is a figure for demonstrating schematic structure of the capacity | capacitance control valve used for the refrigerating cycle of FIG. 1 with the connection state of the capacity | capacitance control valve in a compressor. 2 is a graph showing a relationship between a control current of a capacity control valve and a target suction pressure in the refrigeration cycle of FIG. 1. It is a block diagram which shows schematic structure of the capacity | capacitance control system of 1st Embodiment. It is a graph which shows the relationship between the thermal load and the target suction pressure in the refrigerating cycle of FIG. It is a block diagram which shows the detail of the solenoid drive means in FIG. 6 is a control flowchart showing a main routine executed by the capacity control system of FIG. 4. 8 is a control flowchart of a target suction pressure calculation routine included in the main routine of FIG. It is a figure for demonstrating schematic structure of the capacity control valve used for the capacity control system of 2nd Embodiment with the connection state of the capacity control valve in a compressor. 12 is a graph showing a relationship among a control current, a target suction pressure, and a discharge pressure in the capacity control valve of FIG. It is a block diagram which shows schematic structure of the capacity | capacitance control system of 2nd Embodiment. 12 is a control flowchart illustrating a main routine executed by the capacity control system of FIG. 11.

Explanation of symbols

254 Coil 400A Control device 402 Evaporator temperature sensor (control target detection means)

Claims (11)

It is applied to a variable capacity compressor inserted together with a radiator, an expander and an evaporator in a circulation path through which a refrigerant circulates to constitute a refrigeration cycle of an air conditioning system, so that the control amount of the air conditioning system approaches a target value, In a capacity control system that controls the discharge capacity of the variable capacity compressor by adjusting the control pressure,
Control target detection means for detecting the control amount;
An electromagnetic control valve capable of adjusting the control pressure by opening and closing;
A controller that calculates a discharge capacity control signal from the target value based on an arithmetic expression, and supplies a control current corresponding to the discharge capacity control signal to the electromagnetic control valve;
The control device corrects the arithmetic expression based on a deviation between the control amount detected by the control target detection unit and the target value only when a determination criterion is satisfied,
The determination criterion includes a condition that a discharge capacity of the variable capacity compressor is continuously smaller than a maximum discharge capacity for a threshold time or longer.   2. The variable capacitor according to claim 1, wherein the determination criterion further includes a condition that an average rate of change of the control amount detected by the control target detection unit during the threshold time is equal to or less than an upper limit value. Compressor capacity control system. Further comprising an evaporator air volume detecting means for detecting the air volume to the evaporator;
3. The capacity control of the variable capacity compressor according to claim 2, wherein the determination criterion further includes a condition that an air flow rate of the evaporator detected by the evaporator air flow rate detection unit is not more than an upper limit value. system.   The determination criterion further includes a condition that an average value in a threshold time of a deviation between a target value set by the control target setting unit and a control amount detected by the control target detection unit is not less than a lower limit value. 4. The capacity control system for a variable capacity compressor according to claim 2, wherein the capacity control system is a variable capacity compressor. It further comprises a thermal load detection means for detecting the thermal load of the refrigeration cycle,
The controller is
Target suction pressure setting means for setting a target suction pressure, which is a target of suction pressure, based on the target value and the thermal load detected by the thermal load detection means;
Storage means for storing an arithmetic expression for calculating the discharge capacity control signal from the target suction pressure set by the target suction pressure setting means as the arithmetic expression;
5. The variable capacitor according to claim 1, further comprising a correction unit that corrects an arithmetic expression stored in the storage unit based on a control amount detected by the control target detection unit. Compressor capacity control system. A rotation speed detecting means for detecting a physical quantity corresponding to the rotation speed of the variable capacity compressor;
6. The variable according to claim 5, wherein the target suction pressure setting means sets the target suction pressure based on the target value, the thermal load, and a physical quantity detected by the rotation speed detection means. Capacity control system for capacity compressor.   The capacity control system for a variable capacity compressor according to claim 5 or 6, wherein the arithmetic expression stored in the storage means is updated by the arithmetic expression corrected by the correction means.   8. The capacity control system for a variable capacity compressor according to claim 1, wherein the threshold time is increased each time the arithmetic expression is corrected.   The capacity of the variable capacity compressor according to any one of claims 5 to 8, wherein the correction amount of the arithmetic expression by the correcting means is limited to a range set with reference to the first arithmetic expression. Control system.   The capacity control system for a variable capacity compressor according to any one of claims 1 to 9, wherein the electromagnetic control valve includes a pressure sensor that mechanically controls the control pressure in response to a suction pressure.   10. The variable capacity compressor according to claim 1, wherein the electromagnetic control valve has a valve body whose discharge pressure acts in a direction opposite to the suction pressure and the electromagnetic force of the solenoid unit. Capacity control system.

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