JP3752816B2 - Operation control method and operation control apparatus for variable capacity compressor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is used in a refrigeration circuit that performs heat exchange including the case where the refrigerant is cooled in a supercritical region that exceeds the critical temperature of the refrigerant, and the differential pressure between the control pressure in the control pressure chamber and the suction pressure in the suction pressure region. The present invention relates to an operation control method and apparatus for a variable displacement compressor that changes the discharge capacity based on the change in the pressure.
[0002]
[Prior art]
In variable displacement compressors that change the discharge capacity by changing the tilt angle of the swash plate that converts the rotation of the rotating shaft into the reciprocating motion of the piston, changing the tilt angle of the swash plate changes the pressure in the control pressure chamber that houses the swash plate Is done by. In this type of variable displacement compressor, the inclination angle of the swash plate is defined by the pressure in the compression chamber defined by the piston, that is, the pressure difference between the suction pressure and the control pressure chamber via the piston. As the differential pressure increases, the inclination angle of the swash plate decreases and the piston stroke decreases. That is, the discharge volume decreases as the differential pressure increases.
[0003]
Freon is generally used as a refrigerant in a refrigeration circuit, but Japanese Patent Application Laid-Open No. 8-110104 discloses carbon dioxide (CO₂) As a refrigerant is disclosed. The critical temperature of carbon dioxide is about 31 ° C, which is about 20 ° lower than that of Freon. Heat exchange related to the chlorofluorocarbon refrigerant in the condenser in the refrigeration circuit, that is, cooling of the chlorofluorocarbon refrigerant is performed in a temperature range that does not exceed the critical temperature of the fluorocarbon. However, the cooling of the carbon dioxide refrigerant is often performed in a supercritical region exceeding the critical temperature of carbon dioxide in the summer when the outside air temperature becomes high.
[0004]
A temperature expansion valve is used in a refrigeration circuit using a fluorocarbon refrigerant. As the rotational speed of the compressor increases, the flow rate of the chlorofluorocarbon refrigerant circulating in the refrigeration circuit increases, and heat exchange in the evaporator is not sufficiently performed. For this reason, the degree of superheat on the outlet side of the evaporator is reduced. The temperature expansion valve operates to reduce the flow rate of the chlorofluorocarbon refrigerant as the degree of superheat decreases. By such a flow rate adjusting operation of the temperature expansion valve, the suction pressure is reduced, and the differential pressure in the variable capacity compressor is increased. As a result, the discharge capacity is reduced and the cooling capacity is adjusted. Further, the evaporation temperature for evaporating the chlorofluorocarbon refrigerant decreases as the suction pressure decreases. Therefore, the capacity reduction control corresponding to the fluctuation of the suction pressure can be performed by detecting the pressure or temperature of the chlorofluorocarbon refrigerant at the outlet side of the evaporator.
[0005]
In refrigeration circuit using carbon dioxide refrigerantIn some cases, the refrigerant is cooled in the supercritical region, and the pressure changes depending on the heat load even at the same temperature. Therefore, the pressure that controls the flow rate by pressureA force expansion valve is used. As the rotational speed of the compressor increases, the flow rate of the carbon dioxide refrigerant circulating in the refrigeration circuit increases, and the discharge pressure increases. The pressure expansion valve operates to increase the flow rate of the carbon dioxide refrigerant as the discharge pressure increases. By such a flow rate adjusting operation of the pressure expansion valve, the suction pressure does not immediately decrease, and the differential pressure in the variable displacement compressor does not increase immediately. As a result, the discharge capacity does not decrease immediately and the cooling capacity is not adjusted quickly. Further, the evaporation temperature for evaporating the carbon dioxide refrigerant does not immediately decrease. Therefore, it is difficult to perform capacity down control corresponding to fluctuations in the suction pressure based on detection of the pressure or temperature of the carbon dioxide refrigerant on the outlet side of the evaporator. Such difficulty causes the variable capacity compressor to perform more work than necessary, and power consumption and load in the variable capacity compressor become excessive.
[0006]
An object of the present invention is to reduce power consumption and load in a variable capacity compressor used in a refrigeration circuit that performs heat exchange including cooling a refrigerant in a supercritical region that exceeds the critical temperature of the refrigerant.
[0007]
[Means for Solving the Problems]
  For this purpose, the present invention is used in a refrigeration circuit that performs heat exchange including the case where the refrigerant is cooled in a supercritical region that exceeds the critical temperature of the refrigerant, and the control pressure in the control pressure chamber and the suction pressure in the suction pressure region. The present invention is directed to a variable displacement compressor that changes a discharge capacity based on a change in differential pressure. In the first aspect of the invention, the differential pressure between the control pressure and the suction pressure is determined by a first displacement control valve and a second displacement control. Controlled by valve andThe first capacity control valve is an electric capacity control valve for setting a target discharge pressure that operates so as to keep the discharge pressure constant. The first capacity control valve detects an outside air temperature and a thermal load, and detects the detected outside air temperature and the heat load. Based on this, the target discharge pressure is determined, and the current supply to the first capacity control valve is controlled so as to bring the determined target discharge pressure. According to this configuration, the discharge capacity of the variable capacity compressor is quickly adjusted to the discharge capacity corresponding to the capacity adjustment state determined based on the external information from the capacity adjustment state of the first capacity control valve. Therefore, the variable capacity compressor is prevented from performing more work than necessary. The discharge pressure maintained by the electric capacity control valve reflects the capacity adjustment state, and the increase / decrease in the differential pressure between the control pressure in the control pressure chamber and the suction pressure is the value of the discharge pressure maintained by the first capacity control valve. Reflect the increase or decrease. That is, the discharge pressure is substantially proportional to the discharge capacity, and the discharge pressure increases as the discharge capacity increases. Therefore, the discharge capacity is adjusted by changing the value of the discharge pressure maintained by the electric capacity control valve. The outside air temperature and heat load are appropriate as external information for adjusting the discharge capacity of the variable capacity compressor.
[0008]
  According to a second aspect of the present invention, in the first aspect, the refrigerant supply from the discharge pressure region to the control pressure chamber is controlled by the first capacity control valve, and the refrigerant is extracted from the control pressure chamber to the suction pressure region. Controlled by two capacity control valvesThe second2 capacity control valveNoThe amount adjustment stateIncludes ambient temperature or heat loadThe decision was made based on external information.
[0013]
  Claim3In the invention of claim 1,as well asClaim2In any one of the above, the second capacity control valve is an electric capacity control valve for setting a target suction pressure that operates so as to keep the suction pressure constant.
[0014]
When the suction pressure increases, the differential pressure between the control pressure and the suction pressure decreases, and the discharge capacity increases. The suction pressure maintained by the second capacity control valve reflects the capacity adjustment state, and the increase / decrease in the differential pressure between the control pressure in the control pressure chamber and the suction pressure is the same as the suction pressure maintained by the second capacity control valve. Reflects changes in value. That is, the discharge capacity is adjusted by changing the value of the suction pressure maintained by the second capacity control valve.
[0016]
  Claim4In the invention of claim3, Detecting a thermal load, determining the target suction pressure based on the detected thermal load, and controlling a current supply to the second capacity control valve to provide the determined target suction pressure did.
[0017]
  Claim5In the invention, a first capacity control valve that controls a differential pressure between the control pressure and the suction pressure, a second capacity control valve that controls a differential pressure between the control pressure and the suction pressure,at least,The first capacity controlValveCapacity adjustment statusDecideCapacity adjustment state control meansAn outside air temperature detecting means for detecting the outside air temperature and a heat load detecting means for detecting the heat load;WithThe capacity adjustment state control means determines the target discharge pressure based on the outside air temperature detected by the outside air temperature detection means and the thermal load detected by the heat load detection means; First current supply control means for controlling current supply to the first capacity control valve so as to provide the determined target discharge pressure.An operation control device was configured.According to this configuration, the target discharge pressure determining means determines the target discharge pressure based on the detected outside air temperature and thermal load. The first electric supply control means controls the current supply to the first capacity control valve so as to provide the determined target discharge pressure, and the first capacity control valve operates so as to provide the determined target discharge pressure. To do. The discharge pressure is quickly controlled by controlling the current supply to the first capacity control valve. Therefore, the discharge pressure reflecting the capacity adjustment state is quickly adjusted based on the external information, and the variable capacity compressor is prevented from performing work more than necessary.
[0018]
  Claim6In the invention of claim5The first capacity control valve controls refrigerant supply from the discharge pressure region to the control pressure chamber, and the second capacity control valve controls refrigerant extraction from the control pressure chamber to the suction pressure region. I did it.
[0022]
  Claim7In the invention of claim5And claims6In any one of the above, it is provided with a thermal load detection means for detecting a thermal load, and the capacity adjustment state control means determines the target suction pressure based on the thermal load detected by the thermal load detection means. An operation control device comprising pressure determining means and second current supply control means for controlling current supply to the second capacity control valve so as to bring the determined target suction pressure is configured.
[0023]
The target suction pressure determining means determines the target suction pressure based on the detected thermal load. The second electric supply control means controls the current supply to the second capacity control valve so as to provide the determined target suction pressure, and the second capacity control valve operates so as to provide the determined target suction pressure. To do. The suction pressure is quickly controlled by controlling the current supply to the second capacity control valve. Therefore, the suction pressure reflecting the capacity adjustment state is quickly adjusted based on the external information, and the variable capacity compressor is prevented from performing work more than necessary.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
[0025]
As shown in FIG. 1, a front housing 12 and a rear housing 13 are joined and fixed before and after the cylinder block 11. A rotating shaft 14 is rotatably supported on the cylinder block 11 and the front housing 12 via radial bearings 15 and 16. The rotating shaft 14 obtains a rotational force from the engine of the compressor-equipped vehicle via an electromagnetic clutch (not shown). In the front housing 12, a disc-shaped rotary support 17 is fixed to the rotary shaft 14, and a guide hole 172 is formed in a support arm 171 formed at the peripheral edge of the rotary support 17. .
[0026]
A swash plate 18 is supported on the rotary shaft 14 so as to be tiltable and slidable in the axial direction of the rotary shaft 14. As shown in FIGS. 1 and 2, a connecting piece 181 is fixed to the swash plate 18, and a guide pin 19 is attached to the distal end portion of the connecting piece 181. The guide pin 19 is engaged with the guide hole 172, and the guide hole 172 guides the tilting of the swash plate 18 through the guide pin 19. The swash plate 18 can swing in the direction of the rotation shaft 14 and can rotate integrally with the rotation shaft 14 by the guide operation and the support operation of the rotation shaft 14.
[0027]
A piston 20 is accommodated in a cylinder bore 111 penetrating the cylinder block 11. The piston 20 defines a compression chamber 112 in the cylinder bore 111. A pair of shoes 21 are interposed between the neck portion 201 of the piston 20 and the swash plate 18. The rotational movement of the swash plate 18 accommodated in the control pressure chamber 121 is converted into the back-and-forth reciprocating movement of the piston 20 via the shoe 21, and the piston 20 moves back and forth in the cylinder bore 111.
[0028]
As shown in FIGS. 1 and 3, a suction chamber 131 serving as a suction pressure region and a discharge chamber 132 serving as a discharge pressure region are defined in the rear housing 13. A partition plate 22 and a pair of valve forming plates 23 and 24 are interposed between the cylinder block 11 and the rear housing 13, and a suction port 221 and a discharge port 222 are provided on the partition plate 22. The suction port 221 is opened and closed by a suction valve 231 on the valve forming plate 23, and the discharge port 222 is opened and closed by a discharge valve 241 on the valve forming plate 24. The opening degree of the discharge valve 241 is restricted by the retainer 37. The refrigerant in the compression chamber 112 is pushed out of the discharge valve 241 and discharged from the discharge port 222 to the discharge chamber 132 by the forward movement of the piston 20 that is in the discharge operation. The refrigerant in the suction chamber 131 is pushed away from the suction valve 231 by the backward movement of the piston 20 in the suction operation, and is sucked into the compression chamber 112 from the suction port 221.
[0029]
The refrigerant flowing out from the discharge chamber 132 to the external refrigerant circuit 38 is cooled by the condenser 39. The refrigerant that has been cooled by the condenser 39 reaches the evaporator 41 via the pressure expansion valve 40. The pressure expansion valve 40 operates to increase the passage cross-sectional area as the discharge pressure Pd increases. The refrigerant heated by the evaporator 41 returns to the suction chamber 131.
[0030]
FIG. 6 is a Mollier diagram. Curve E1 represents a saturated liquid line and a saturated vapor line. A curve E2 represents a critical temperature curve of the carbon dioxide refrigerant. The horizontal axis represents enthalpy and the vertical axis represents pressure. The straight line D1 represents the evaporation stroke in the evaporator 41, the curve D2 represents the compression stroke in the variable displacement compressor, the straight line D3 represents the condensation stroke in the condenser 39, and the straight line D4 represents the expansion stroke in the pressure expansion valve 40. In the illustrated example, the outside air temperature Te represented by the curve E3 is higher than the critical temperature represented by the critical temperature curve E2, and the condensation of the carbon dioxide refrigerant is performed in the supercritical region.
[0031]
The stroke of the piston 20 depends on the pressure difference between the control pressure Pc in the control pressure chamber 121 and the pressure in the compression chamber 112 via the piston 20, that is, the pressure difference (Pc−Ps) between the control pressure Pc and the suction pressure Ps. Thus, the inclination angle of the swash plate 18 that affects the discharge capacity changes. When the differential pressure (Pc−Ps) increases, the inclination angle of the swash plate 18 decreases, and the discharge capacity decreases. When the differential pressure (Pc−Ps) decreases, the inclination angle of the swash plate 18 increases and the discharge capacity increases. The electric first capacity control valve 25 in the rear housing 13 controls the refrigerant supply from the discharge chamber 132 to the control pressure chamber 121. The electric second capacity control valve 42 in the rear housing 13 controls the extraction of the refrigerant from the control pressure chamber 121 to the suction chamber 131. The control pressure Pc in the control pressure chamber 121 is controlled by supplying the refrigerant from the first capacity control valve 25 and extracting the refrigerant from the second capacity control valve 42.
[0032]
As shown in FIG. 4, the first capacity control valve 25 includes a solenoid 26 and a valve mechanism 27. The solenoid 26 includes a coil 261, a fixed iron core 262, a movable iron core 263, a drive rod 264 fixed to the movable iron core 263, and a return spring 265. The valve mechanism 27 includes a housing 28, a valve body 29 accommodated in a valve chamber 281 in the housing 28, and a holding spring 30 that holds the valve body 29. The movable iron core 263 is attracted and biased toward the fixed iron core 262 by supplying current to the coil 261. That is, the driving force of the solenoid 26 is transmitted to the valve body 29 via the drive rod 264, and the valve body 29 is biased in the direction of closing the valve hole 282. The return spring 265 biases the movable iron core 263 in a direction away from the fixed iron core 262.
[0033]
A port 283 is formed in the housing 28. The valve chamber 281 communicates with the control pressure chamber 121 through the port 283 and the passage 31, and the valve hole 282 communicates with the discharge chamber 132 through the passage 32. As shown in FIG. 4, when the valve element 29 is in a position where the valve hole 282 is opened, the high-pressure refrigerant in the discharge chamber 132 is a refrigerant supply passage including a passage 32, a valve hole 282, a valve chamber 281, a port 283, and a passage 31. Is sent to the control pressure chamber 121 via.
[0034]
The sum of the driving force Fd of the solenoid 26 and the spring force F2 of the holding spring 30 opposes the sum of the total pressure Pd1 of the discharge pressure Pd acting on the valve body 29 and the spring force F1 of the return spring 265. That is, when the total pressure Pd1 of the discharge pressure Pd exceeds (Fd + F2-F1), the valve element 29 opens the valve hole 282, and the high-pressure refrigerant in the discharge chamber 132 flows into the control pressure chamber 121. When the total pressure Pd1 of the discharge pressure Pd does not exceed (Fd + F2-F1), the valve element 29 closes the valve hole 282, and the high-pressure refrigerant in the discharge chamber 132 does not flow into the control pressure chamber 121. That is, the first capacity control valve 25 that controls the supply of refrigerant from the discharge chamber 132 to the control pressure chamber 121 operates so as to keep the discharge pressure Pd constant.
[0035]
The second capacity control valve 42 includes a solenoid 43 and a valve mechanism 44. The solenoid 43 includes a coil 431, a fixed iron core 432, a movable iron core 433, a drive rod 434 fixed to the movable iron core 433, and a return spring 435. The valve mechanism 44 includes a housing 45, a valve body 46 that is coupled to the drive rod 434 and accommodated in the valve chamber 451 in the housing 45, a bellows 48 that is accommodated in the valve chamber 451 and coupled to the drive rod 434, The spring 49 acts on the pressure receiving plate 481 in the direction in which the bellows 48 extends. The valve chamber 451 communicates with the control pressure chamber 121 via the valve hole 453 and the passage 47, and the port 452 communicates with the suction chamber 131 via the passage 50. As shown in FIG. 5, when the valve element 29 is in a position where the valve hole 453 is opened, the refrigerant in the control pressure chamber 121 is a refrigerant extraction passage including a passage 47, a valve hole 453, a valve chamber 451, a port 452, and a passage 50. It flows out to the suction chamber 131 via.
[0036]
The suction pressure Ps of the suction chamber 131 is applied to the valve chamber 451 via the passage 50 and the port 452, and the spring force F4 of the spring 49 opposes the total pressure Ps1 of the suction pressure Ps acting on the pressure receiving plate 481. The movable iron core 433 is attracted and biased toward the fixed iron core 432 by supplying current to the coil 431. That is, the driving force of the solenoid 43 opposes the spring force of the spring 49. The return spring 435 biases the movable iron core 433 in a direction away from the fixed iron core 432.
[0037]
  The sum of the driving force Fs of the solenoid 43 and the total pressure Ps1 of the suction pressure Ps with respect to the pressure receiving plate 481 is opposite to the sum of the spring force F3 of the return spring 435 and the spring force F4 of the spring 49. Total pressure Ps1 is (F3 + F4-Fs), The valve body 46 closes the valve hole 453 and the total pressure Ps1 is (F3 + F4-F).s), The valve body 46 opens the valve hole 453. That is, the second capacity control valve 42 that controls the extraction of the refrigerant from the control pressure chamber 121 to the suction chamber 131 operates to keep the suction pressure Ps constant.
[0038]
The solenoid 26 of the first capacity control valve 25 and the solenoid 43 of the second capacity control valve 42 are subjected to current supply control by the controller 33. The controller 33 includes a target discharge pressure determination unit 331 serving as a target discharge pressure determination unit, a target suction pressure determination unit 332 serving as a target suction pressure determination unit, and a first current supply control unit serving as a first current supply control unit. 333 and a second current supply control unit 334 serving as a second current supply control means. The controller 33 controls the capacity adjustment states of the first capacity control valve 25 and the second capacity control valve 42 based on the capacity adjustment state control program shown in the flowchart of FIG. The target discharge pressure determining unit 331 samples the outdoor temperature Te detected by the outdoor temperature detector 34 and the indoor temperature Ts detected by the indoor temperature detector 35 at predetermined time intervals. The target suction pressure determination unit 332 samples the room temperature Ts detected by the room temperature detector 35 at a predetermined time interval.
[0039]
The target discharge pressure determination unit 331 sets the outside air temperature Te detected by the outside air temperature detector 34, the indoor temperature Ts detected by the indoor temperature detector 35, and the target indoor temperature To set by the target indoor temperature setter 36. Based on this, the target discharge pressure Pdo is determined. If the outside air temperature Te increases, the discharge capacity needs to be increased. Further, if the heat load increases in a high level region, it is necessary to increase the discharge capacity. The relationship between the outside air temperature Te and the thermal load and the target discharge pressure Pdo is determined in advance based on the necessity as described above, and the target discharge pressure determination unit 331 is based on the outside air temperature information, the heat load information, and the relationship. The target discharge pressure Pdo is determined. The first current supply control unit 333 controls current supply to the solenoid 26 of the first capacity control valve 25 so as to bring about the target discharge pressure Pdo determined by the target discharge pressure determination unit 331.
[0040]
The target suction pressure determining unit 332 determines the target suction pressure Pso based on the detected room temperature Ts and the target room temperature To. The difference between the target room temperature To and the room temperature Ts reflects the heat load, and the target suction pressure determination unit 332 determines the target suction pressure Pso based on the heat load. If the heat load increases, the suction pressure Ps needs to be lowered. The relationship between the heat load and the target suction pressure Pso is determined in advance based on the necessity as described above, and the target suction pressure determination unit 332 determines the target suction pressure Pso based on the heat load information and the relationship. . The second current supply control unit 334 controls the current supply to the solenoid 43 of the second capacity control valve 42 so as to bring about the target suction pressure Pso determined by the target suction pressure determination unit 332.
[0041]
The following effects can be obtained in the first embodiment.
(1-1) The discharge capacity is adjusted by the differential pressure between the control pressure Pc in the control pressure chamber 121 and the suction pressure Ps, and the differential pressure between the control pressure Pc and the suction pressure Ps is the current to the first capacity control valve 25. It is quickly adjusted by supply control. The discharge capacity is substantially proportional to the discharge pressure Pd, and the discharge pressure Pd reflects the discharge capacity. That is, the target discharge pressure Pdo defines the capacity adjustment state of the first capacity control valve 25. The target discharge pressure determining unit 331 quickly determines the target discharge pressure Pdo based on external information such as the outside air temperature Te and the heat load. The change in the rotational speed of the vehicle engine causes the rotational speed of the rotating shaft 14 to change, and the discharge pressure Pd tends to change. The discharge pressure Pd reflecting the discharge capacity is determined based on the external information such as the outside air temperature Te. The constant pressure is controlled to a constant value of the pressure Pdo. Therefore, the fluctuation of the discharge capacity due to the fluctuation of the rotation speed of the rotating shaft 14 is suppressed by the constant pressure control of the discharge pressure according to the outside air temperature Te by the controller 33 and the first capacity control valve 25. As a result, the variable displacement compressor is prevented from performing more work than necessary due to the fluctuation in the rotational speed of the compressor, and the power consumption and load in the variable displacement compressor are reduced.
(1-2) The differential pressure between the control pressure Pc and the suction pressure Ps is quickly adjusted also by current supply control to the second capacity control valve 42. The suction pressure Ps directly reflects the heat load, and the heat load directly reflects the room temperature. Therefore, the suction pressure Ps is preferably controlled for controlling the room temperature. The target suction pressure Pso defines the capacity adjustment state of the second capacity control valve 42. The target suction pressure determination unit 332 quickly determines the target suction pressure Pso based on external information such as heat load. Although the fluctuation of the heat load causes the fluctuation of the suction pressure Ps, the suction pressure Ps reflecting the heat load is quickly controlled to the target suction pressure Pso determined based on the external information of the heat load. Therefore, it is possible to prevent the variable capacity compressor from performing more work than necessary due to fluctuations in the heat load.
(1-3) Even when the thermal load is in a high level region, the discharge pressure Pd is controlled to a constant value, ie, a target discharge pressure Pdo determined based on external information such as the heat load. Accordingly, the fluctuation of the discharge capacity corresponding to the fluctuation of the heat load in the high level range is appropriately adjusted by the control of the discharge pressure according to the heat load by the controller 33 and the first capacity control valve 25, and the variable capacity compression The machine is prevented from doing more work than necessary.
(1-4) It is desirable that the indoor temperature can be controlled precisely. The second capacity control valve 42 for controlling the suction pressure Ps is suitable for fine control of the room temperature, but is not suitable for capacity adjustment with respect to a large rotational speed fluctuation of the compressor. The first capacity control valve 25 that controls the discharge pressure Pd is suitable for adjusting the capacity against a large fluctuation in the rotational speed of the compressor, but is not suitable for fine control of the room temperature. The configuration in which the discharge pressure control with respect to the rotational speed fluctuation and the suction pressure control with respect to the thermal load fluctuation are appropriately shared by the two capacity control valves 25 and 42, while reducing the power consumption and load in the variable capacity compressor, is good. Enables air conditioning to be achieved.
(1-5) Since the fluctuation of the outside air temperature and the heat load are moderate, the controller 33 is not required to have such a high speed processing function. Therefore, the control system can be constructed at low cost.
(1-6) When the heat load is high, it is necessary to increase the discharge capacity. When the heat load is low, it is necessary to reduce the discharge capacity. Therefore, the thermal load grasped based on the room temperature Ts and the target room temperature To is appropriate as external information for quickly adjusting the discharge capacity.
[0042]
Next, a second embodiment of FIG. 8 will be described. The internal structure of the variable capacity compressor is the same as that of the first embodiment, and the same components as those of the first embodiment are denoted by the same reference numerals.
[0043]
In the second capacity control valve 51 in this embodiment, the suction pressure Ps of the suction chamber 131 is spread to the pressure sensing chamber 511, and the suction pressure Ps in the pressure sensing chamber 511 is springed by the spring 52 via the diaphragm 512. The spring force of the spring 52 can be adjusted by the screwing position of the screw 53. The displacement of the diaphragm 512 is transmitted to the valve body 514 through the displacement transmission rod 513. The second capacity control valve 51 is also a control valve for setting the target suction pressure, like the second capacity control valve 42 in the first embodiment, but the target suction pressure is set by setting the spring force of the spring 52. . The capacity adjustment state of the first capacity control valve 25 is performed by the controller 54 including the target discharge pressure determination unit 331 and the first current supply control unit 333 as in the case of the first embodiment.
[0044]
Also in this embodiment, the same effect as the items (1-1) and (1-3) in the first embodiment can be obtained.
Next, a third embodiment of FIG. 9 will be described. The internal structure of the variable capacity compressor is the same as that of the first embodiment, and the same components as those of the first embodiment are denoted by the same reference numerals.
[0045]
The solenoid 56 of the second capacity control valve 55 includes a coil 561, a fixed iron core 562, a movable iron core 563, a drive rod 564 secured to the movable iron core 563, and a return spring 565. The valve mechanism 44 is housed in a housing 57, a valve body 58 accommodated in a valve chamber 571 in the housing 57, a holding spring 59 that holds the valve body 58, and a pressure sensing chamber 572 in the housing 57. A bellows 60 coupled to the rod 564 and a spring 61 acting on the pressure receiving plate 601 in a direction in which the bellows 60 is extended. The suction pressure Ps of the suction chamber 131 is spread to the pressure sensing chamber 572 via the passage 50 and the port 575, and the spring force F4 of the spring 61 opposes the total pressure Ps1 of the suction pressure Ps acting on the pressure receiving plate 601. The movable iron core 563 is attracted and biased toward the fixed iron core 562 by supplying current to the coil 561. That is, the driving force of the solenoid 56 opposes the spring force of the spring 61. The return spring 565 biases the movable iron core 563 in a direction away from the fixed iron core 562. When the valve hole 573 is opened, the high-pressure refrigerant in the discharge chamber 132 is sent to the control pressure chamber 121 via the passages 62 and 63. The suction pressure Ps in the suction chamber 131 is spread to the pressure sensitive chamber 572 via the passage 64.
[0046]
The sum of the driving force Fo of the solenoid 56 and the total pressure Ps1 of the suction pressure Ps with respect to the pressure receiving plate 601 is opposite to the sum of the spring force F5 of the return spring 565 and the spring force F6 of the spring 61. When the total pressure Ps1 falls below (F5 + F6-Fo), the valve element 58 opens the valve hole 573. When the total pressure Ps1 exceeds (F5 + F6-Fo), the valve element 58 closes the valve hole 573. That is, the capacity control valve 55 operates to control the supply of refrigerant from the discharge chamber 132 to the control pressure chamber 121 and keep the suction pressure Ps constant.
[0047]
Refrigerant extraction from the control pressure chamber 121 to the suction chamber 131 is performed via the throttle passage 66.
The target discharge pressure determining unit 651 of the controller 65 determines the target discharge pressure Pdo based on the outside air temperature Te detected by the outside air temperature detector 34. If the outside air temperature Te increases, the discharge capacity needs to be increased. The first current supply control unit 653 controls the current supply to the solenoid 26 of the first capacity control valve 25 so as to bring the target discharge pressure Pdo determined by the target discharge pressure determination unit 651.
[0048]
The target intake pressure determination unit 652 determines the target intake pressure Pso based on the indoor temperature Ts detected by the indoor temperature detector 35 and the target indoor temperature To set by the target indoor temperature setter 36. The second current supply control unit 654 controls current supply to the solenoid 56 of the second capacity control valve 55 so as to bring about the target suction pressure Pso determined by the target suction pressure determination unit 652.
[0049]
In this embodiment, the first capacity control valve 25, the target discharge pressure determination unit 651, and the first current supply control unit 653 take charge of the discharge pressure fluctuation suppression control with respect to the rotation speed fluctuation, and the second capacity control valve 55, The target suction pressure determination unit 652 and the second current supply control unit 654 are responsible for suction pressure control for thermal load fluctuations. Therefore, also in this embodiment, the same effect as the item (1-4) in the first embodiment can be obtained.
[0050]
In the present invention, the following embodiments are also possible..
(1) In the third embodiment, the target discharge pressure is determined from the outside air temperature and the thermal load as in the case of the first embodiment.
(2) The first capacity control valve is an electromagnetic on-off valve, and the on-off control of the electromagnetic on-off valve is performed so as to bring about a target discharge pressure.
(3) The second capacity control valve is an electromagnetic on-off valve, and the on-off control of the electromagnetic on-off valve is performed so as to bring about the target suction pressure.
[0051]
【The invention's effect】
  As described above in detail, in the present invention, the first capacity control for controlling the refrigerant supply from the discharge pressure region to the control pressure chamber.ValveSince the capacity adjustment state is determined based on external information, in a variable capacity compressor used in a refrigeration circuit that performs heat exchange, including cooling the refrigerant in a supercritical region exceeding the critical temperature of the refrigerant. There is an excellent effect that power consumption and load can be reduced.
[Brief description of the drawings]
FIG. 1 is a side sectional view of an entire compressor showing a first embodiment of the present invention.
FIG. 2 is a cross-sectional view taken along line AA in FIG.
3 is a cross-sectional view taken along line BB in FIG.
FIG. 4 is an enlarged side sectional view of a main part.
FIG. 5 is an enlarged side sectional view of a main part.
FIG. 6 is a Mollier diagram.
FIG. 7 is a flowchart showing a capacity adjustment state control program.
FIG. 8 is an enlarged cross-sectional side view of a main part showing a second embodiment.
FIG. 9 is an enlarged side cross-sectional view of a main part showing a third embodiment.
[Explanation of symbols]
121: Control pressure chamber, 131: Suction chamber as a suction pressure region, 132: Discharge chamber as a discharge pressure region, 25: First capacity control valve, 42, 51 ... Second capacity control valve, 33, 54, 65 ... Controller as capacity adjustment state control means, 331, 651 ... Target discharge pressure determination section as target discharge pressure determination means, 332, 652 ... Target suction pressure determination section as target suction pressure determination means, 333, 653 ... No. A first current supply control unit serving as one current supply control unit, 334, 654 ... a second current supply control unit serving as a second current supply control unit, 34 ... an outside air temperature detector serving as an outside air temperature detection unit, 35 ... Indoor temperature detector constituting thermal load detecting means.

Claims (7)

Used in refrigeration circuits that perform heat exchange, including cooling the refrigerant in a supercritical region that exceeds the critical temperature of the refrigerant, and based on the change in the differential pressure between the control pressure in the control pressure chamber and the suction pressure in the suction pressure region In variable displacement compressors that change the discharge capacity
A differential pressure between the control pressure and the suction pressure is controlled by a first capacity control valve and a second capacity control valve, and the first capacity control valve operates to keep the discharge pressure constant. An electric capacity control valve for detecting outside air temperature and heat load, determining the target discharge pressure based on the detected outside air temperature and heat load, and providing the determined target discharge pressure An operation control method for a variable displacement compressor in which current supply to a first displacement control valve is controlled . The refrigerant supply from the discharge pressure region to the control pressure chamber is controlled by the first capacity control valve, the refrigerant extraction from the control pressure chamber to the suction pressure region is controlled by the second capacity control valve , operation control method for a variable displacement compressor according to claim 1 for determining on the basis of external information including the capacity adjustment state of the second capacity control valve outside air temperature or thermal load. 3. The variable capacity compression according to claim 1, wherein the second capacity control valve is an electric capacity control valve for setting a target suction pressure that operates so as to keep the suction pressure constant. 4. Machine operation control method. 4. The method according to claim 3 , wherein a thermal load is detected, the target suction pressure is determined based on the detected thermal load, and a current supply to the second capacity control valve is controlled so as to bring about the determined target suction pressure. The operation | movement control method of the variable capacity compressor of description. Used in refrigeration circuits that perform heat exchange, including cooling the refrigerant in a supercritical region that exceeds the critical temperature of the refrigerant, and based on the change in the differential pressure between the control pressure in the control pressure chamber and the suction pressure in the suction pressure region In variable displacement compressors that change the discharge capacity
A first capacity control valve that controls a differential pressure between the control pressure and the suction pressure;
A second capacity control valve for controlling a differential pressure between the control pressure and the suction pressure;
Capacity adjustment state control means for determining at least the capacity adjustment state of the first capacity control valve;
An outside air temperature detecting means for detecting an outside air temperature and a heat load detecting means for detecting a thermal load, wherein the capacity adjustment state control means is detected by the outside air temperature detected by the outside air temperature detecting means and the load detecting means. Target discharge pressure determining means for determining the target discharge pressure based on the thermal load, and first current supply means for controlling the current supply to the first capacity control valve so as to bring the determined target discharge pressure An operation control device for a variable capacity compressor . The first capacity control valve controls refrigerant supply from a discharge pressure region to the control pressure chamber, and the second capacity control valve controls refrigerant extraction from the control pressure chamber to the suction pressure region. 5. An operation control device for a variable capacity compressor according to claim 5 . The capacity adjustment state control means includes target suction pressure determination means for determining the target suction pressure based on the thermal load detected by the thermal load detection means, and the second target so as to bring the determined target suction pressure. The variable capacity compressor operation control device according to any one of claims 5 and 6, further comprising second current supply control means for controlling current supply to the capacity control valve .

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