JPH11223179A - Method and device for controlling operation of variable displacement compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accomplish reduction in power consumption and in a load in a variable displacement compressor used in a freezing circuit for cooling down a refrigerant in a supercritical area beyond a critical temperature of the refriger ant. SOLUTION: A displacement control valve 25 controlling the supply of a refrigerant from a discharge chamber 132 to a control pressure chamber 121 is operated so as to keep a discharge pressure constant. A solenoid 26 of the displacement control valve 25 receives current supply control from a controller 33. A flow rate regulating condition determining unit 331 constituting the controller 33 decides a flow rate regulating condition of a variable displacement type compressor on the basis of the external information provided from an outside air temperature detector 34, a room temperature detector 35, and a target room temperature setting device 36. A current supply control unit 332 controls current supply to the solenoid 26 in the displacement control valve 25 so that the flow rate regulating condition determined by means of the flow rate regulating condition determining unit 331 is attained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in a refrigeration circuit for performing heat exchange including cooling a refrigerant in a supercritical region exceeding a critical temperature of the refrigerant, and comprises a control pressure of a control pressure chamber and a suction pressure region. TECHNICAL FIELD The present invention relates to an operation control method and apparatus for a variable displacement compressor that changes capacity based on a change in a differential pressure from a suction pressure of the compressor.

[0002]

2. Description of the Related Art In a variable displacement compressor in which the displacement of a swash plate is changed by changing the tilt angle of a swash plate that converts the rotation of a rotary shaft into reciprocating motion of a piston, the tilt angle of the swash plate is changed by changing the tilt angle of the swash plate in a control pressure chamber that houses the swash plate. This is done by changing the pressure. In this type of variable displacement compressor, the tilt 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 through the piston. As the differential pressure increases, the inclination angle of the swash plate decreases, and the stroke of the piston decreases. That is, as the differential pressure increases, the discharge capacity decreases.

Although chlorofluorocarbon is generally used as a refrigerant in a refrigeration circuit, Japanese Patent Application Laid-Open No. Hei 8-110104 discloses a refrigeration circuit using carbon dioxide (CO ₂ ) as a refrigerant. The critical temperature of carbon dioxide is about 31 ° C., which is about 20 ° lower than that of Freon. The heat exchange of the CFC in the condenser in the refrigeration circuit, that is, the cooling of the CFC, is performed in a temperature range not exceeding the critical temperature of the CFC. However, the cooling of the carbon dioxide refrigerant is often performed in a supercritical region exceeding the critical temperature of carbon dioxide in summer when the outside air temperature increases.

[0004] In a refrigeration circuit using a Freon refrigerant, a temperature expansion valve is used. As the rotational speed of the compressor increases, the flow rate of the CFC refrigerant circulating in the refrigeration circuit increases, and heat exchange in the evaporator is not sufficiently performed. Therefore, the degree of superheat on the outlet side of the evaporator decreases. The temperature expansion valve operates in a direction to reduce the flow rate of the CFC refrigerant in accordance with the decrease in the degree of superheat. The suction pressure decreases due to the flow rate adjusting operation of the temperature expansion valve, and the differential pressure in the variable displacement compressor increases.
As a result, the discharge capacity is reduced, and the cooling capacity is adjusted.
Further, the evaporating temperature for evaporating the CFC refrigerant decreases due to a decrease in the suction pressure. Accordingly, the capacity down control corresponding to the fluctuation of the suction pressure can be performed by detecting the pressure or the temperature of the CFC refrigerant at the outlet side of the evaporator.

[0005] In a refrigeration circuit using carbon dioxide refrigerant, a pressure 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 in a direction to increase the flow rate of the carbon dioxide refrigerant as the discharge pressure increases. Such a flow rate adjusting operation of the pressure expansion valve does not immediately reduce the suction pressure, and does not immediately increase the differential pressure in the variable displacement compressor.
As a result, the discharge capacity is not immediately reduced, and the cooling capacity is not quickly adjusted. Further, the evaporation temperature for evaporating the carbon dioxide refrigerant does not immediately decrease. Therefore, it is difficult to perform the capacity down control corresponding to the fluctuation of the suction pressure based on the detection of the pressure or temperature of the carbon dioxide refrigerant at the outlet side of the evaporator.
Such difficulties cause the variable capacity compressor to do more work than necessary, resulting in excessive power consumption and load on the variable capacity compressor.

SUMMARY OF THE INVENTION An object of the present invention is to reduce power consumption and load in a variable displacement compressor used in a refrigeration circuit for performing heat exchange including cooling a refrigerant in a supercritical region exceeding a critical temperature of the refrigerant. And

[0007]

SUMMARY OF THE INVENTION Accordingly, the present invention is directed to a refrigeration circuit for performing heat exchange including cooling a refrigerant in a supercritical region exceeding a critical temperature of the refrigerant. The present invention is directed to a variable displacement compressor that changes the capacity based on a change in a pressure difference between the pressure and a suction pressure in a suction pressure region. A refrigerant extraction from the chamber to the suction pressure region is controlled by an electric capacity control valve, and a flow rate adjustment state of the variable displacement compressor for adjusting a flow rate of the refrigerant flowing through the refrigeration circuit is determined based on external information, The current supply to the electric displacement control valve is controlled to bring the determined flow regulation state.

The flow rate adjustment state of the variable displacement compressor is adjusted by controlling the current supply to the electric displacement control valve. Therefore, the flow rate of the refrigerant is quickly adjusted to the flow rate corresponding to the flow rate adjustment state determined based on the external information, and the variable displacement compressor does not perform unnecessary work.

According to the invention of claim 2, in claim 1,
The heat load was included in the external information. The heat load is suitable as external information for quickly adjusting the refrigerant flow rate. According to a third aspect of the present invention, in the second aspect, the outside air temperature is detected, the flow rate adjustment state of the variable displacement compressor is provisionally determined based on the detected outside air temperature, and the thermal load is detected. The flow adjustment state is determined based on the heat load and the temporarily determined flow adjustment state.

It is necessary to increase the flow rate of the refrigerant as the outside air temperature increases, and the appropriate level of the flow rate of the refrigerant depends on the outside air temperature. The flow rate adjustment state provisionally determined from the outside air temperature defines an appropriate level of refrigerant flow rate. If external information such as an increase in heat load is obtained, the provisionally determined flow adjustment state is changed to increase the refrigerant flow.

According to a fourth aspect of the present invention, in any one of the first to third aspects, the electric capacity control valve is
The operation of controlling the supply of the refrigerant from the discharge pressure region to the control pressure chamber and keeping the discharge pressure constant is performed.

The discharge pressure is substantially proportional to the flow rate of the refrigerant. As the flow rate of the refrigerant increases, the discharge pressure also increases. The discharge pressure maintained by the electric displacement control valve reflects the flow rate adjustment state, and the increase or decrease of the differential pressure between the control pressure of the control pressure chamber and the suction pressure depends on the value of the discharge pressure maintained by the electric displacement control valve. Reflect changes. That is, the refrigerant flow rate is adjusted by changing the value of the discharge pressure maintained by the electric displacement control valve.

According to a fifth aspect of the present invention, in any one of the first to third aspects, the electric capacity control valve is
The refrigerant supply from the discharge pressure region to the control pressure chamber is controlled, and the suction pressure is kept constant.

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 held by the electric displacement control valve reflects the flow rate adjustment state, and the increase / decrease in the differential pressure between the control pressure of the control pressure chamber and the suction pressure depends on the value of the suction pressure held by the electric displacement control valve. Reflect changes. That is, the flow rate of the refrigerant is adjusted by changing the value of the suction pressure held by the electric capacity control valve.

According to the present invention, an electric capacity control valve for controlling the supply of refrigerant from the discharge pressure area to the control pressure chamber or the extraction of refrigerant from the control pressure chamber to the suction pressure area, and an external valve for generating external information Information generation means, flow rate adjustment state determination means for determining a flow rate adjustment state of the variable displacement compressor for adjusting the flow rate of the refrigerant flowing through the refrigeration circuit based on the generated external information, and the determined flow rate An operation control device is provided that includes current supply control means for controlling current supply to the electric capacity control valve so as to bring about an adjustment state.

The flow adjustment state determining means determines the flow adjustment state of the variable displacement compressor based on the external information generated by the external information generation means. The electric supply control means controls the current supply to the electric displacement control valve to bring the determined flow regulation state, and the electric displacement control valve operates to bring the decided flow regulation state. The flow adjustment state of the variable displacement compressor is quickly controlled by controlling the current supply to the electric displacement control valve.
Therefore, the flow rate of the refrigerant is quickly adjusted to the flow rate corresponding to the flow rate adjustment state determined based on the external information, and the variable displacement compressor does not perform unnecessary work.

According to the invention of claim 7, in claim 6,
The heat load detected by the heat load detection means is included in the generated external information. The flow adjustment state determining means determines a flow adjustment state of the variable displacement compressor based on the detected heat load.

In the invention according to claim 8, in claim 7,
An outside air temperature detection unit that detects an outside air temperature is provided, and the flow rate adjustment state determination unit temporarily determines a flow rate adjustment state of the variable displacement compressor based on the outside air temperature detected by the outside air temperature detection unit, The flow control state is determined from the provisionally determined flow control state based on the detected heat load.

The flow rate adjustment state provisionally determined from the outside air temperature by the flow rate adjustment state determining means defines an appropriate level of refrigerant flow rate. If external information such as an increase in heat load is obtained, the provisionally determined flow adjustment state is changed to increase the refrigerant flow.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.

As shown in FIG. 1, the cylinder block 11
A front housing 12 and a rear housing 13 are joined and fixed before and after. A rotary shaft 14 is rotatably supported by the cylinder block 11 and the front housing 12 via radial bearings 15 and 16.
The rotating shaft 14 obtains rotational force from an engine of a vehicle equipped with a compressor via an electromagnetic clutch (not shown). A rotating support 1 having a disk shape is provided on a rotating shaft 14 in the front housing 12.
7 is fixed, and a guide hole 172 is formed in a support arm 171 formed on a peripheral portion of the rotary support 17.

A swash plate 18 is supported on the rotating shaft 14 so as to be tiltable and slidable in the axial direction of the rotating 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 a distal end of the connecting piece 181. The guide pin 19 is engaged with the guide hole 172, and the guide hole 172 guides the tilt of the swash plate 18 via the guide pin 19. The swash plate 18 can swing in the direction of the rotating shaft 14 and can rotate integrally with the rotating shaft 14 by the guiding action and the supporting action of the rotating shaft 14.

A piston 20 is accommodated in a cylinder bore 111 penetrating through the cylinder block 11. The piston 20 defines a compression chamber 112 inside the cylinder bore 111. A pair of shoes 21 is interposed between the neck 201 of the piston 20 and the swash plate 18. Control pressure chamber 12
Rotational movement of the swash plate 18 accommodated in 1 is converted into reciprocating movement of the piston 20 via the shoe 21, and the piston 20 moves back and forth in the cylinder bore 111.

As shown in FIGS. 1 and 3, a suction chamber 131 serving as a suction pressure area and a discharge chamber 132 serving as a discharge pressure area are formed 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.
The partition plate 22 has a suction port 221 and a discharge port 222.
Is provided. 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 of the discharge valve 241 is regulated 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 performing the discharge operation. The refrigerant in the suction chamber 131 is returned to the suction valve 231 by the reciprocation of the piston 20 in the suction operation.
And is sucked into the compression chamber 112 from the suction port 221.

The refrigerant flowing from the discharge chamber 132 to the external refrigerant circuit 38 is cooled by the condenser 39. Condenser 39
The refrigerant having undergone the cooling operation at step (1) reaches the evaporator 41 via the pressure expansion valve 40. The pressure expansion valve 40 operates to increase the passage cross-sectional area according to the rise of the discharge pressure Pd. Evaporator 41
The refrigerant heated in step (1) returns to the suction chamber 131.

FIG. 5 is a Mollier diagram. Curve E1 represents a saturated liquid line and a saturated vapor line. Curve E2 represents the 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,
Curve D2 represents the compression stroke of the variable displacement compressor,
3 represents a condensation stroke in the condenser 39, and a straight line D4 represents an expansion stroke in the pressure expansion valve 40. In the illustrated example, the curve E
3 is higher than the critical temperature represented by the critical temperature curve E2, and the carbon dioxide refrigerant is condensed in a supercritical region.

The stroke of the piston 20 is controlled by the control pressure chamber 12.
1 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, and affects the discharge capacity. The inclination angle of the swash plate 18 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 displacement control valve 25 in the rear housing 13 is connected to the control pressure chamber 12 from the discharge chamber 132.
1 is controlled. Refrigerant in the control pressure chamber 121 passes through a pressure release passage 113 having a throttling function to a suction chamber 131.
Has leaked to The control pressure Pc in the control pressure chamber 121 is controlled by the refrigerant flowing out of the control pressure chamber 121 to the suction chamber 131 through the discharge passage 113 having a throttling action, and the refrigerant supply of the capacity control valve 25.

As shown in FIG. 4, the displacement control valve 25 comprises a solenoid 26 and a valve mechanism 27. Solenoid 26
Are a coil 261, a fixed iron core 262, and a movable iron core 26.
3 and 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 housed in a valve chamber 281 in the housing 28, and a holding spring 30 for holding 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 through the driving rod 264 to the valve element 29.
And the valve body 29 is urged in a direction to close the valve hole 282. The return spring 265 fixes the movable iron core 263 to the fixed iron core 2.
It is urged in the direction away from 62.

The housing 28 has a port 283 formed therein. The valve chamber 281 communicates with the control pressure chamber 121 via the port 283 and the passage 31, and the valve hole 282 communicates with the discharge chamber 132 via the passage 32. That is, when the valve element 29 is at the position where the valve hole 282 is opened, the high-pressure refrigerant in the discharge chamber 132 is supplied to the passage 32, the valve hole 282, and the valve chamber 2.
The refrigerant is sent to the control pressure chamber 121 via a refrigerant supply passage 81, a port 283, and a passage 31.

The driving force Fo of the solenoid 26 and the holding spring 3
0 and the spring force F2 are equal to the discharge pressure P acting on the valve body 29.
d against the sum of the total pressure Pd1 and the spring force F1 of the return spring 265. That is, the total pressure Pd1 of the discharge pressure Pd is (Fo)
If (+ F2-F1) is exceeded, the valve body 29 opens the valve hole 282, and the high-pressure refrigerant in the discharge chamber 132 flows into the control pressure chamber 121. The total pressure Pd1 of the discharge pressure Pd is (Fo + F2-F1)
Is not exceeded, the valve body 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 displacement control valve 25 is connected to the control pressure chamber 12 from the discharge chamber 132.
1 so as to control the supply of the refrigerant to the pump 1 and keep the discharge pressure Pd constant.

The solenoid 26 is controlled by a controller 33 to supply current. The controller 33 includes a flow rate adjustment state determination unit 331 serving as a flow rate adjustment state determination unit and a current supply control unit 332 serving as a current supply control unit. The flow adjustment state determining unit 331 determines the flow adjustment state of the variable displacement compressor that adjusts the flow rate of the refrigerant. The flow rate adjustment state determining unit 331 includes an outside air temperature detector 3 that detects an outside air temperature.
4. The flow rate adjustment state is determined based on the external information obtained from the indoor temperature detector 35 for detecting the indoor temperature of the vehicle equipped with the compressor and the target indoor temperature setter 36 for setting the target indoor temperature. The current supply control unit 332 controls the current supply to the solenoid 26 of the capacity control valve 25 so as to provide the flow control state determined by the flow control state determination unit 331.

The controller 33 controls the flow rate adjustment state of the variable displacement compressor based on the flow rate adjustment state control program shown in the flowchart of FIG. The flow rate adjustment state determining unit 331 samples the outside air temperature Te detected by the outside air temperature detector 34 and the room temperature Ts detected by the room temperature detector 35 at predetermined time intervals. The flow rate adjustment state determination unit 331 temporarily determines the minimum target discharge pressure Pdx based on the sampled outside air temperature Te. The temporarily determined target discharge pressure Pdx and the outside air temperature Te are determined in advance by a map unit in which the relationship indicated by the line E4 in FIG. 5 and the line H in the graph of FIG. Temporarily determines the minimum target discharge pressure Pdx based on the map means.

The flow rate adjustment state determining section 331 determines the appropriate range of the indoor temperature [To−ΔT, To + ΔT] based on the target indoor temperature To set by the target indoor temperature setter 36.
Set. Then, the flow rate adjustment state determining unit 331 determines that the sampled room temperature Ts is within the appropriate range [To−ΔT,
To + ΔT] is determined. The sampled room temperature Ts is within an appropriate range [To−ΔT, To + ΔT]
Does not reach, that is, if Ts <(To−ΔT), the flow rate adjustment state determination unit 331 increases and changes the provisionally determined target discharge pressure Pdx according to the difference [(To−ΔT) −Ts]. . The sampled room temperature Ts is within the proper range [T
o−ΔT, To + ΔT], that is, (To + ΔT)
T) <Ts, the flow rate adjustment state determination unit 331 subtracts the provisionally determined target discharge pressure Pdx by the difference [Ts− (To + Δ
T)]. When the sampled room temperature Ts falls within the appropriate range [To-ΔT, To + ΔT], that is, (To−ΔT) ≦ Ts ≦ (To + ΔT), the flow rate adjustment state determination unit 331 determines the provisionally determined target discharge pressure. Do not change Pdx.

In the state of Ts <(To−ΔT), the heat load is lower than the cooling capacity, and in the state of Ts> (To + ΔT), the heat load is higher than the cooling capacity. (To−ΔT) ≦ T
In the state of s ≦ (To + ΔT), the cooling capacity is appropriate. That is, the flow rate adjustment state determination unit 331 determines the true target discharge pressure Tdo with respect to the outside air temperature Te based on the detection of the heat load and the provisionally determined target discharge pressure Pdx.

The current supply control section 332 controls the current supply to the solenoid 26 based on the true target discharge pressure Tdo determined by the flow rate adjustment state determination section 331.
When the true target discharge pressure Tdo is increased, the current supply control unit 332 increases the supply current value to the solenoid 26.
When the true target discharge pressure Tdo is reduced, the current supply control unit 332 reduces the supply current value to the solenoid 26.
The solenoid 26 generates a driving force according to the supply current value,
The displacement control valve 25 operates to provide a discharge pressure defined by the supply current value, that is, a true target discharge pressure Pdo.

In the first embodiment, the following effects can be obtained. (1-1) The discharge capacity increases as the inclination angle of the swash plate 18 increases, and the discharge capacity decreases as the inclination angle of the swash plate 18 decreases. The flow rate adjustment state of the variable displacement compressor is represented by the tilt angle of the swash plate 18, and the tilt angle of the swash plate 18 is adjusted by the differential pressure between the control pressure Pc in the control pressure chamber 121 and the suction pressure Ps. The pressure difference between the control pressure Pc and the suction pressure Ps is quickly adjusted by controlling the current supply to the electric displacement control valve 25. The discharge capacity indicates the refrigerant flow rate, and the discharge pressure Pd reflects the refrigerant flow rate. That is, the target discharge pressure Pdo defines the flow rate adjustment state of the variable displacement compressor. The flow rate adjustment state determination unit 331 quickly determines the target discharge pressure Pdo based on external information such as heat load. The variation in the rotation speed of the vehicle engine causes a variation in the rotation speed of the rotating shaft 14, and the discharge capacity, and thus the discharge pressure Pd, tends to fluctuate. The convergence is quickly adjusted to the pressure Pdo. Therefore, the variable displacement compressor does not perform more work than necessary, and the power consumption and load in the variable displacement compressor are not excessive. (1-2) It is necessary to increase the refrigerant flow rate when the heat load is high, and it is necessary to decrease the refrigerant flow rate when the heat load is low. Therefore, the heat load grasped based on the indoor temperature Ts detected by the indoor temperature detector 35 constituting the heat load detecting means and the target indoor temperature To set by the target indoor temperature setter 36 can rapidly increase the refrigerant flow rate. It is appropriate as external information to adjust to. (1-3) It is necessary to increase the refrigerant flow rate as the outside air temperature Te increases, and the appropriate level of the refrigerant flow rate depends on the outside air temperature Te. The target discharge pressure Pdx tentatively determined based on the outside air temperature Te defines an appropriate level of the refrigerant flow rate, and the flow rate adjustment state determination unit 331 determines the flow rate adjustment state by adjusting the discharge pressure by the fluctuation of the outside air temperature Te. Variations in levels are factored in. Therefore, the true target discharge pressure Pdo determined based on the heat load and the provisionally determined target discharge pressure Pdx
Is set from an appropriate level to an optimal value, and optimal control of the cooling capacity is performed. (1-4) The discharge pressure Pd is substantially proportional to the refrigerant flow rate, and the discharge pressure Pd increases as the refrigerant flow rate increases. Electric capacity control valve 2
5 reflects the flow rate adjustment state, and the increase or decrease of the differential pressure (Pc−Ps) between the control pressure Pc and the suction pressure Ps depends on the target discharge pressure Pdo maintained by the electric displacement control valve 25. Reflects an increase or decrease in the value. Therefore, the electric displacement control valve 25 that operates so as to maintain the discharge pressure at a constant value is optimal as a means for adjusting the flow rate of the refrigerant. (1-5) The pressure expansion valve 40 detects the discharge pressure and controls the flow rate of the refrigerant, so that fluctuations in the discharge pressure due to fluctuations in the number of revolutions are quickly suppressed. Therefore, the pressure expansion valve 40 contributes to the improvement of the responsiveness of the constant pressure control of the discharge pressure Pd.

Next, a second embodiment shown in FIGS. 8 and 9 will be described. The internal structure of the variable displacement 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.

An electric displacement control valve 42 for controlling a differential pressure between the control pressure Pc and the suction pressure Ps is provided with a solenoid 43 and a valve mechanism 4.
4 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 and a housing 4.
5, a valve body 46 housed in a valve chamber 451, a holding spring 47 for holding the valve body 46, and a pressure-sensitive chamber 4 in a housing 45.
A bellows 48 housed in the interior 52 and coupled to the drive rod 434, and a pressure receiving plate 481 in a direction in which the bellows 48 extends.
And a spring 49 acting on the spring. The suction pressure Ps of the suction chamber 131 is supplied through the passage 50 and the port 455 to the pressure-sensitive chamber 452.
And the spring force F4 of the spring 49 is applied to the pressure receiving plate 481.
Opposes the total pressure Ps1 of the suction pressure Ps acting on. The movable iron core 433 is urged toward the fixed iron core 432 by the current supply to the coil 431. That is, the driving force of the solenoid 43 opposes the spring force of the spring 49. Return spring 435
Urges the movable iron core 433 in a direction away from the fixed iron core 432.

The housing 45 has ports 453 and 45
4,455 are formed. Valve hole 456 is port 45
3 and the passage 31 communicate with the control pressure chamber 121, and the valve chamber 451 communicates with the discharge chamber 132 via the port 454 and the passage 32. The port 455 communicates with the suction chamber 131 via the passage 50. The valve body 29 is the valve hole 4
When the valve 56 is in the open position, the high-pressure refrigerant in the discharge chamber 132 passes through the refrigerant supply passages of the passage 32, the port 454, the valve chamber 451, the valve hole 456, the port 453, and the passage 31 to the control pressure chamber 121. Sent.

The driving force Fo of the solenoid 43 and the bellows 4
8 and the total pressure Ps1 of the suction pressure Ps for the pressure receiving plate 481
Is opposed to the sum of the spring force F3 of the return spring 435 and the spring force F4 of the spring 49. The total pressure Ps1 is (F3 + F
4-Fo), the valve body 46 opens the valve hole 456, and when the total pressure Ps1 exceeds (F3 + F4-Fo), the valve body 46 opens.
Closes the valve hole 456. That is, the capacity control valve 42 operates to control the supply of the refrigerant from the discharge chamber 132 to the control pressure chamber 121 and to keep the suction pressure Ps constant.

The solenoid 43 is controlled by the controller 51 to supply current. The controller 51 includes a flow rate adjustment state determination unit 511 serving as a flow rate control state determination unit and a current supply control unit 512 serving as a current supply control unit. The flow adjustment state determination unit 511 determines the flow adjustment state of the variable displacement compressor that adjusts the flow rate of the refrigerant. The flow adjustment state determination unit 511 determines the flow adjustment state based on external information obtained from the indoor temperature detector 35 and the target indoor temperature setter 36. The current supply control unit 512 controls the current supply to the solenoid 43 of the capacity control valve 42 so as to provide the flow adjustment state determined by the flow adjustment state determination unit 511.

The controller 51 controls the flow adjustment state of the variable displacement compressor based on the flow adjustment state control program shown in the flowchart of FIG. The flow adjustment state determining unit 511 temporarily determines the target suction pressure Psx based on the target indoor temperature To set by the target indoor temperature setter 36. In addition, the flow rate adjustment state determining unit 511 determines the appropriate range of the indoor temperature [To−ΔT, To + ΔT] based on the target indoor temperature To set by the target indoor temperature setter 36.
Set. The flow rate adjustment state determination unit 511 samples the room temperature Ts detected by the room temperature detector 35 at predetermined time intervals. Then, the flow rate adjustment state determining unit 511 determines whether or not the sampled room temperature Ts falls within the appropriate range [To−ΔT, To + ΔT]. If Ts <(To−ΔT), the flow rate adjustment state determination unit 511 subtracts the provisionally determined target suction pressure Psx by the difference [(T
o-ΔT) -Ts]. (To + Δ
T) <Ts, the flow rate adjustment state determination unit 511 subtracts the provisionally determined target suction pressure Psx by the difference [Ts− (To + Δ
T)]. (To−ΔT) ≦ Ts ≦
In the case of (To + ΔT), the flow rate adjustment state determination unit 511
Does not change the provisionally determined target suction pressure Psx.

In the state of Ts <(To−ΔT), the heat load is lower than the cooling capacity, and in the state of Ts> (To + ΔT), the heat load is higher than the cooling capacity. (To−ΔT) ≦ T
In the state of s ≦ (To + ΔT), the cooling capacity is appropriate. That is, the flow rate adjustment state determination unit 511 determines the true target suction pressure Pso with respect to the target room temperature To based on the detection of the heat load and the provisionally determined target suction pressure Psx.

The current supply control section 512 controls the current supply to the solenoid 43 based on the true target suction pressure Pso determined by the flow rate adjustment state determination section 511.
When the true target suction pressure Pso is increased, the current supply control unit 512 decreases the supply current value to the solenoid 43.
When the true target suction pressure Pso is reduced, the current supply control unit 512 increases the supply current value to the solenoid 43.
The solenoid 43 generates a driving force according to the supply current value,
The displacement control valve 42 operates to provide a suction pressure defined by the supply current value, that is, a true target suction pressure Pso.

The following effects can be obtained in the second embodiment. (2-1) When the target suction pressure Pso is reduced, the valve hole 456 opens, and the differential pressure (Pc-Ps) increases. Therefore, the flow rate of the refrigerant decreases, and the suction pressure Ps decreases. Target suction pressure Ps
When o is increased, the valve hole 456 closes and the differential pressure (Pc-P
s) becomes smaller. Therefore, the flow rate of the refrigerant increases, and the suction pressure Ps increases. The suction pressure Ps reflects the flow rate of the refrigerant, and the target suction pressure Pso defines the flow adjustment state of the variable displacement compressor. The flow rate adjustment state determination unit 511 quickly determines the target suction pressure Pso based on external information such as heat load. The change in the rotation speed of the vehicle engine causes a change in the rotation speed of the rotating shaft 14, and the discharge capacity, that is, the suction pressure Ps tends to change. However, the suction pressure Ps reflecting the refrigerant flow rate is determined based on external information such as a heat load. The convergence is quickly adjusted to the target suction pressure Pso. Therefore, the variable displacement compressor does not perform more work than necessary, and the power consumption and load in the variable displacement compressor are not excessive. (2-2) The suction pressure Ps reflects the refrigerant flow rate, and the suction pressure maintained by the electric capacity control valve 42 reflects the flow rate adjustment state. Therefore, the electric capacity control valve 42 that operates so as to maintain the suction pressure at a constant value is suitable as a means for adjusting the flow rate of the refrigerant.

In the present invention, the following embodiments are also possible. (1) The sampling interval of the outside air temperature is made longer than the sampling interval of the room temperature, and the change amount of the target discharge pressure for each sampling of the heat load is set to a constant value. (2) The amount of the refrigerant supplied from the discharge pressure region to the control pressure chamber is made constant, and the discharge of the refrigerant from the control pressure chamber to the suction pressure region is controlled by an electric displacement control valve that operates so as to keep the suction pressure constant. thing.

[0047]

As described in detail above, in the present invention, the supply of refrigerant from the discharge pressure region to the control pressure chamber or the extraction of refrigerant from the control pressure chamber to the suction pressure region is controlled by the electric capacity control valve. The flow rate adjustment state of the variable capacity compressor is determined based on external information, and the current supply to the capacity control valve is controlled to bring the determined flow rate adjustment state. The present invention has an excellent effect of reducing power consumption and load in a variable displacement compressor used in a refrigeration circuit for performing heat exchange including cooling a refrigerant in a supercritical region.

[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 sectional view taken along line AA of FIG.

FIG. 3 is a sectional view taken along line BB of FIG. 1;

FIG. 4 is an enlarged side sectional view of a main part.

FIG. 5 is a Mollier diagram.

FIG. 6 is a graph showing a relationship between an outside air temperature and a provisional target discharge pressure.

FIG. 7 is a flowchart showing a flow control state control program.

FIG. 8 is an enlarged side sectional view of a main part showing a second embodiment.

FIG. 9 is a flowchart showing a flow control state control program.

[Explanation of symbols]

121: a control pressure chamber; 131: a suction chamber serving as a suction pressure area;
132: a discharge chamber serving as a discharge pressure region; 25, 42: a capacity control valve; 331, 511: a flow rate adjustment state determination unit serving as a flow rate adjustment state determination unit; 332, 512: a current supply control unit serving as a current supply control unit; 34: an outside air temperature detector serving as external information generating means; 35: an indoor temperature detector constituting heat load detecting means serving as external information generating means; 36 ... a target indoor temperature setting device serving as external information generating means.

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Toshiro Fujii 2-1-1 Toyota-machi, Kariya-shi, Aichi Prefecture Inside Toyota Industries Corporation

Claims (8)

[Claims] 1. A refrigeration circuit for performing heat exchange including cooling a refrigerant in a supercritical region exceeding a critical temperature of the refrigerant, wherein a difference between a control pressure in a control pressure chamber and a suction pressure in a suction pressure region is used. In a variable displacement compressor that changes capacity based on a change in pressure, supply of refrigerant from a discharge pressure region to the control pressure chamber or extraction of refrigerant from the control pressure chamber to the suction pressure region is controlled by an electric displacement control valve. And determining a flow rate adjustment state of the variable displacement compressor that adjusts the flow rate of the refrigerant flowing through the refrigeration circuit based on external information, and controlling the electric capacity control valve so as to bring the determined flow rate adjustment state. An operation control method for a variable displacement compressor that controls current supply. 2. The operation control method for a variable displacement compressor according to claim 1, wherein said external information includes a heat load. 3. An outside air temperature is detected, a flow rate adjustment state of the variable displacement compressor is provisionally determined based on the detected outside air temperature, a heat load is detected, and the detected heat load and the provisional determination are detected. The operation control method for a variable displacement compressor according to claim 2, wherein the flow control state is determined based on the performed flow control state. 4. The valve according to claim 1, wherein the electric displacement control valve controls the supply of refrigerant from the discharge pressure region to the control pressure chamber and maintains the discharge pressure constant. The operation control method for a variable displacement compressor according to claim 1. 5. The electric capacity control valve according to claim 1, wherein the electric capacity control valve operates so as to control the supply of the refrigerant from the discharge pressure region to the control pressure chamber and to keep the suction pressure constant. The operation control method for a variable displacement compressor according to claim 1. 6. A difference between a control pressure in a control pressure chamber and a suction pressure in a suction pressure region, which is used in a refrigeration circuit for performing heat exchange including cooling a refrigerant in a supercritical region exceeding a critical temperature of the refrigerant. An electric displacement control valve for controlling the supply of refrigerant from a discharge pressure area to the control pressure chamber or the extraction of refrigerant from the control pressure chamber to the suction pressure area in a variable displacement compressor that changes capacity based on a change in pressure. An external information generating means for generating external information; and a flow adjustment state determination for determining a flow adjustment state of the variable displacement compressor for adjusting a flow rate of the refrigerant flowing through the refrigeration circuit based on the generated external information. And a current supply control means for controlling a current supply to the electric displacement control valve so as to bring about the determined flow regulation state. 7. The operation control device for a variable displacement compressor according to claim 6, wherein said generated external information includes a heat load detected by a heat load detecting means. 8. An outside air temperature detecting means for detecting an outside air temperature, wherein the flow rate adjusting state determining means determines a flow rate adjusting state of the variable displacement compressor based on the outside air temperature detected by the outside air temperature detecting means. 8. The operation control device for a variable displacement compressor according to claim 7, wherein the flow control state is temporarily determined and the flow rate adjustment state is determined from the temporarily determined flow adjustment state based on the detected heat load.