JP3319652B2 - Refrigeration circuit using variable displacement compressor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigeration circuit mainly used for vehicle air conditioning, and more particularly to a variable refrigeration circuit having a swash plate element capable of changing the stroke of a piston based on the pressure in a crankcase. The present invention relates to a refrigeration circuit including a displacement compressor.

[0002]

2. Description of the Related Art In a refrigeration circuit for vehicle air conditioning, a wobble type,
There is a tendency that variable displacement compressors such as swash type are frequently used. Usually, these compressors are driven by the power of the engine being transmitted through an electromagnetic clutch, and the compression work of the refrigerant gas is performed through a change in the volume of the bore. Then, the high-temperature and high-pressure refrigerant gas sent from the compressor is liquefied in a condenser and adiabatically expanded by an expansion valve, so that the low-temperature and high-pressure refrigerant gas is cooled.
After being made into a low-pressure gas-liquid two-phase flow, it evaporates in an evaporator. At that time, it draws heat of evaporation from the surrounding air to contribute to cooling in the vehicle compartment, and then is sucked into the compressor again.

The capacity control (reduction) of the compressor is usually performed by selectively supplying a discharge pressure to a crank chamber by a capacity control valve responsive to a suction pressure, and a tilt displacement of a swash plate element caused by an increase in crank chamber pressure. In other words, the displacement is controlled by the fluctuation of the piston stroke.However, when such displacement control is performed, the compressor must be operated under the most severe conditions in terms of both temperature and lubrication for high-speed rotation or a compressor with a small heat load and a small amount of refrigerant circulation. In this regard, some conservation measures are desired.

The electromagnetic clutch connected to a drive shaft of a compressor generally includes a rotor supported by a housing of the compressor and driven by an engine, and an armature and an exciting coil disposed opposite to the rotor. When the compressor is started, the armature is attracted to the rotor by energizing the exciting coil, and power from the engine is transmitted to the drive shaft via the hub.

[0005] However, such electromagnetic clutches that are universally used have the following various problems. That is, a relatively heavy and expensive electromagnetic clutch results in a large increase in the total weight of the compressor and a high cost.
Moreover, the sudden load fluctuation of the engine that occurs when the electromagnetic clutch is turned on / off not only impairs the driving feeling, but also compels the idle-up control to prevent engine stall, and naturally reduces the fuel consumption. We cannot help but get worse. Also, since the power consumption required to energize the excitation coil is unexpectedly large, there is a case where a correspondingly large alternator must be mounted.

[0006] Japanese Patent Application Laid-Open No. HEI-3-3737 exemplified here.
Japanese Patent Application Laid-Open No. 8 (Kokai) No. 8-28139 discloses a clutchless variable displacement compressor in which an electromagnetic clutch is omitted. The compressor is capable of changing a discharge capacity in accordance with a suction pressure, and a drive shaft directly connected to a pulley extends into a crank chamber, and a rotating body is fixed to the drive shaft in the crank chamber. ing. The rotating body supports a rotary swash plate via a hinge mechanism and the drive shaft via a sleeve, whereby the rotary swash plate rotates together with the drive shaft in the crank chamber and can be displaced at an angle. . A plurality of single-headed pistons are linked to the rotating swash plate via a swinging plate and a piston rod, and each single-headed piston reciprocates in each bore formed in the cylinder block based on the forward and backward swinging of the swinging plate. I do. The housing has a suction chamber for supplying refrigerant gas into each bore, and a discharge chamber for discharging refrigerant gas compressed in each bore. The housing and the cylinder block have a crank chamber and a discharge chamber. And a bleed passage with a throttle connecting the crank chamber and the suction chamber.
The displacement control valve provided in the housing can introduce the discharge chamber pressure into the crank chamber by the displacement of the bellows for detecting the suction pressure.

As a characteristic configuration of the compressor, an electromagnetic valve for opening and closing the suction system passage by an external signal is provided at a suction pipe connected to the suction chamber or at an inlet of the suction chamber. Therefore, when the power source is started, power is directly transmitted to the drive shaft via the pulley, and the compressor is also started.
During the operation of the compressor, the displacement control valve constantly adjusts the crank chamber pressure, and changes the volume of refrigerant gas taken into each bore and eventually the displacement through the displacement of the rotary swash plate from the minimum tilt angle to the maximum tilt angle. Let it. Here, if the cooling operation becomes unnecessary during the operation of the compressor, the solenoid valve is closed by an external signal and the gas suction of the compressor is prevented, so that the pressure in the suction chamber rapidly decreases. As a result, the displacement control valve responsive to this supplies the discharge chamber pressure to the crank chamber to increase the crank chamber pressure. As a result, the rotary swash plate is displaced to the minimum tilt state, and the compressor shifts to the minimum displacement state.

[0008]

By the way, in the refrigeration circuit including the compressor described in the above publication, when the cooling operation is not required during the operation of the compressor and the solenoid valve is closed, The compressor shifts to the minimum capacity state by the reduction of the suction chamber pressure and the operation of the capacity control valve in response thereto, but in this state, a small amount of refrigerant gas as it participates in the compression work flows from the discharge chamber to the supply passage. To the crank chamber, and further from the crank chamber to the suction chamber via the throttled bleed passage. However, since the flow of the refrigerant gas is different from that flowing through a regular refrigeration circuit and only circulates in the compressor, the temperature of sliding parts such as a swash plate, a shoe, and a shaft sealing device is particularly low. In addition to raising the oil pressure to lower the durability, when the circuit is closed with a small amount of oil stored in the crank chamber, a problem of poor lubrication also occurs.

A first object of the present invention is to reliably maintain a variable displacement compressor at the time of displacement control (reduction), and a second solution is to provide a sufficient compressor even when cooling operation is not required. An object of the present invention is to improve the durability of a clutchless variable displacement compressor by ensuring proper cooling and lubrication.

[0010]

According to a first aspect of the present invention, there is provided a piston for reciprocating in a bore formed in a cylinder block and compressing and discharging refrigerant sucked from a suction chamber; It rotates with the drive shaft in the crank chamber,
A variable displacement compressor including a swash plate element capable of changing the stroke of the piston based on the pressure of the crank chamber and capable of tilting displacement, and a bleed passage with a throttle communicating the crank chamber and the suction chamber. A refrigeration circuit for circulating the refrigerant delivered from the compressor through a condenser, an expansion valve, and an evaporator. It is characterized in that a supply pressure line to be connected is provided, and a capacity control valve for constantly adjusting the crank chamber pressure in response to the suction system pressure is disposed in the pressure supply line.

In a preferred embodiment, the displacement control valve is
It responds to the outlet pressure of the evaporator. According to a third aspect of the present invention, the drive shaft of the compressor is directly connected to a power source via a pulley, and the pipeline is selectively opened / closed to a pipeline extending from a branch point of the pressure supply pipeline to an expansion valve. A switching valve is provided.

In a preferred aspect, the switching valve is an electromagnetically operated valve that responds to an on / off signal of a refrigeration circuit. According to a fifth aspect of the present invention, the drive shaft of the compressor is directly connected to a power source via a pulley, and the expansion valve is controlled to open and close by the on / off signal of a refrigeration circuit. The electronic expansion valve adjusts the opening degree in accordance with the detection signal of the electronic expansion valve.

The swash plate element is a wobble type in which an oscillating plate combined with a rotary swash plate is connected to a piston via a connecting rod, and a rotary swash plate is directly linked to a piston via a shoe. The swash plate element includes any of the swash-types.

[0014]

In the refrigeration circuit according to the first aspect, when the compressor is started by transmission means such as an electromagnetic clutch, the refrigerant gas sucked from the suction chamber is compressed and discharged to the discharge chamber.
Then, the high-temperature, high-pressure refrigerant gas sent from the compressor is sent to a condenser to be liquefied, and further adiabatically expanded by an expansion valve to be converted into a low-temperature, low-pressure gas-liquid two-phase flow.
It evaporates in an evaporator, and at this time, for example, the interior of the vehicle is cooled by removing heat of evaporation from the surrounding air. Then, the low-temperature, low-pressure refrigerant gas is sucked into the compressor again.

During operation of the compressor, if the heat load decreases or the suction system pressure falls below a set value due to the transition to high-speed rotation, the pressure control line corresponding thereto opens the pressure supply line and condenses. The high-pressure liquid refrigerant passed through the compressor is supplied to the crank chamber of the compressor through the pressure line, which causes the pressure in the crank chamber to rise, causing the swash plate element to be displaced in the direction of decreasing the tilt angle, and the compressor Move to reduced state.

In this case, the liquid refrigerant cooled and liquefied by passing through the condenser is further decompressed by the throttling effect received when passing through the capacity control valve and vaporized in the crank chamber. Instead, it acts as an evaporator and contributes to the cooling of the compressor.Moreover, most of the mixed oil particles in the liquid refrigerant introduced into the crankcase are stored without entraining the vaporized refrigerant. And contributes well to the lubrication inside the machine. That is, even under the most severe conditions with a small amount of refrigerant circulation, the maintenance of the compressor is sufficiently achieved. In the case where the detected pressure of the capacity control valve is determined from the outlet pressure of the evaporator as in the refrigeration circuit according to the second aspect, the temperature control of the evaporator can be performed more accurately without being affected by the pressure loss of the suction system piping. Can be realized.

Further, in the refrigeration circuit according to the third aspect, a so-called clutchless variable displacement compressor in which a drive shaft is directly connected to a power source via a pulley is employed, and a cooling operation is performed during the cooling operation. The function of the refrigeration circuit is not different from that of the first embodiment. However, during the operation of the compressor, when the cooling operation becomes unnecessary and the line leading to the expansion valve is closed by the switching valve, the capacity control valve immediately opens the pressure supply line based on the decrease in the suction system pressure. All of the high-pressure liquid refrigerant that has passed through the condenser is supplied to the crankcase of the compressor through the pressure supply line, which causes the crankcase pressure to rise, and the swash plate element is displaced to the minimum tilt state, and Shifts to the minimum capacity state. Then, a small amount of refrigerant gas sent from the compressor is supplied to the condenser, pressure line (capacity control valve),
It is continuously circulated in the same route as the crank chamber, the bleed passage, the suction chamber, the bore, and the discharge chamber.

In this case, as described above, the circulating refrigerant is cooled and liquefied by passing through the condenser, and is further reduced in pressure by the throttle action of the capacity control valve and vaporized in the crank chamber. And the lubrication is kept very good. In this manner, the compressor when the cooling operation is not necessary only sucks and discharges a small amount of the refrigerant gas, and most of the rotational power can be limited to the frictional loss. It is desirable to dispose the liquid refrigerant near the shaft so that the liquid refrigerant does not flow into the suction chamber.

Further, in the refrigeration circuit according to the fifth aspect, together with the clutchless variable displacement compressor, the refrigeration circuit is controlled to open and close by an on / off signal of the refrigeration circuit, and the degree of opening is controlled in accordance with a detection signal of the circuit. An electronic expansion valve for adjustment is employed, and in addition to omitting the above-mentioned switching valve, stable responsiveness with higher accuracy can be obtained.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. The refrigeration circuit of the present embodiment shown in FIG. 1 is used for vehicle air conditioning, and includes a variable capacity compressor (hereinafter, simply referred to as a compressor) 100, a condenser 101, a liquid receiver 102, and a thermostatic automatic compressor. Expansion valve (hereinafter simply referred to as expansion valve)
Ordinary components including an evaporator 103 and an evaporator 104 are connected by pipes P1 to P5, and an expansion valve 103 is connected to a gas pressure of a temperature-sensitive cylinder 103b connected via a capillary tube 103a. Thereby, the valve opening degree, that is, the degree of superheat, is adjusted.

A supply pressure line P6, which is a characteristic configuration of the present embodiment, connects a branch point S in the line P3 from the condenser 101 to the expansion valve 103, for example, and a crank chamber of a compressor described later. The pressure control line 50 is provided with a capacity control valve 50. P7 is a bleed passage with a throttle in the compressor that communicates the crank chamber and the suction chamber.
The drawing shows a form connected to the suction pipe line P5 for easy understanding.

2, the front end of the cylinder block 1 is closed by a front housing 2 and the rear end of the cylinder block 1 is closed by a rear housing 3 via a valve plate 4, as shown in FIG. Are fastened together by a through bolt 21. A drive shaft 6 extending in the axial direction is accommodated in a crank chamber 5 formed by the cylinder block 1 and the front housing 2, and is rotatably supported by radial bearings 7a and 7b. The front end of the drive shaft 6 is connected to an automobile engine via, for example, an electromagnetic clutch MC and a transmission mechanism shown in FIG. A plurality of bores 8 are bored in the cylinder block 1 at positions surrounding the drive shaft 6, and a piston 9 is fitted in each bore 8 so as to be able to reciprocate.

In the crank chamber 5, a rotor 10 is coupled to the drive shaft 6 so as to be able to rotate synchronously with the front housing 2 via a thrust bearing 11, and a swash plate 12 is fitted behind the rotor 10. ing. And the swash plate 12
Is always urged rearward by a pressing spring 13 interposed between the rotor and the rotor 10. The swash plate 12 has smooth sliding surfaces 12a formed on the outer peripheral sides of both end surfaces, and hemispherical shoes 14 are in contact with the sliding surfaces 12a. The spherical surface is engaged with the concave spherical surface of the piston 9.

A pair of brackets 12b, 12b are provided on the rotor 10 side inward of the sliding surface 12a of the swash plate 12.
Projecting from the top dead center position T of the swash plate 12, the base ends of the guide pins 12 c, 12 c are fixed to the brackets 12 b, 12 b, and the guide pins 12 c, 12 c
Spherical portions 12d, 12d are formed at the tip of c.
Thus, in this compressor, a part of the hinge mechanism K is constituted by the brackets 12b, 12b, the guide pins 12c, 12c, and the spherical portions 12d, 12d.

In the center of the swash plate 12, a bent through hole 20 is formed through the drive shaft 6 to allow the swash plate 12 to be tilted. On the side, a counter weight 15 extending radially outward from the axis of the drive shaft 6 and covering the sliding surface 12a while avoiding the shroud 14 on the rotor 10 side is mounted by a rivet 16. . The swash plate 12 has a counter weight 1
The front end face 12e closer to the center than 5 is in contact with the rear end face 10a of the rotor 10 to restrict the maximum inclination angle, while the rear end face in contact with the circlip 22 limits the minimum inclination angle. ing.

On the upper part of the rotor 10, a pair of support arms 17, 17 constituting the rest of the hinge mechanism K are projected rearward in the axial direction so as to align with the guide pins 12c, 12c. At the tip of 17, 17,
Guide holes 17a, 17a penetrate in parallel with a plane determined by the axis of the drive shaft 6 and the top dead center position T of the swash plate 12 and approach the axis of the drive shaft 6 from outside. Have been.
The orientation of the guide holes 17a, 17a is set so that the top dead center position of the piston 9 is kept immovable regardless of the inclination displacement of the swash plate 12, and the guide holes 17a, 17a
Inside the sphere portion 1 of the guide pins 12c, 12c, respectively.
2d and 12d are slidably inserted.

A suction chamber 30 and a discharge chamber 31 are defined in the rear housing 3, and a suction port 32 and a discharge port 33 are opened in the valve plate 4 corresponding to the bore 8. A compression chamber formed between the piston 9 and the piston 9 communicates with the suction chamber 30 and the discharge chamber 31 via the suction port 32 and the discharge port 33. Each suction port 32 is provided with a suction valve (not shown) that opens and closes the suction port 32 according to the reciprocating motion of the piston 9. Each discharge port 33 restricts the discharge port 33 to a retainer 34 according to the reciprocating motion of the piston 9. A discharge valve (not shown) that opens and closes while being opened is provided. As shown in FIG. 1, P7 is a bleed passage with a throttle that connects the crank chamber 5 and the suction chamber 30. At least the opening of the bleed passage P7 on the side of the crank chamber 5 is located near the periphery of the drive shaft 6. It is arranged so that the liquid refrigerant does not flow into the suction chamber 30.

Reference numeral 50 denotes a displacement control valve arranged in the pressure supply line P6 for adjusting the amount of refrigerant supplied to the crank chamber 5 in response to the pressure of the suction system (P5), and is schematically represented. The displacement control valve 50 includes a diaphragm 52 biased by a spring 51, and a valve body 53 coupled to the diaphragm 52, and the diaphragm 52 is displaced against the detection pressure of the pipeline P5. The opening and closing of the conduction valve seat 54 of the pressure supply pipe line P6 via the valve body 53 is controlled.

The detected pressure of the capacity control valve 50 may be obtained from the inlet pressure or the internal pressure of the evaporator 104, and the position of the capacity control valve 50 may be freely selected. For example, similarly to the evaporator 104, it can be disposed in a vehicle room having a relatively good environment. In the refrigeration circuit configured as described above, when the electromagnetic clutch MC is turned on, power is transmitted to the drive shaft 6 to start the compressor 100, and the refrigeration circuit functions as follows.

That is, in the compressor 100, each piston 9 reciprocates in the bore 8 based on the rotational swing of the swash plate 12 accompanying the rotation of the drive shaft 6. As a result, the return refrigerant is drawn into each of the bores from the evaporator 104 via the pipe P5 and the suction chamber 30, and the refrigerant gas compressed in each of the bores 8 is discharged into the discharge chamber 31.
Is discharged to The high-temperature, high-pressure refrigerant gas discharged from the discharge chamber 31 is sent to the condenser 101 via the pipe P1, and the refrigerant cooled and liquefied by the condenser 101 is supplied to the pipe P2, the liquid receiver 102, and the pipe P2. It circulates with P3 and is adiabatically expanded by the expansion valve 103. At the same time, the supply amount is adjusted to the supply amount according to the detection pressure of the temperature-sensitive cylinder 103b and sent into the evaporator 104 from the pipeline P4. When the refrigerant that has become a gas-liquid two-phase flow at a low temperature and a low pressure evaporates in the evaporator 104, it cools the vehicle interior by removing heat of evaporation from the surrounding air.
After that, it is sucked into the compressor 100 again.

During operation of the compressor 100, the heat load is reduced or the intake system (P
5) When the pressure falls below the set value, the conduction valve seat 54 of the capacity control valve 50 corresponding thereto is opened to open the pressure supply line P6, and the high-pressure liquid refrigerant passing through the condenser 101 is supplied to the pressure supply line P6.
6 to the crankcase 5 of the compressor 100, which causes an increase in the crankcase pressure and the swash plate 12
Is displaced in the inclination reduction direction, and the compressor 100 shifts to a capacity reduction state.

In this case, the liquid refrigerant cooled and liquefied by passing through the condenser 101 is further supplied to the capacity control valve 5.
Since the pressure in the crank chamber 5 is reduced by the throttling action received when passing through the cylinder chamber 0 and vaporized in the crank chamber 5, the crank chamber 5 acts as an evaporator and contributes to the cooling of the compressor 100. Most of the mixed oil particles in the liquid refrigerant introduced into the chamber 5 are stored without being entrained by the vaporized refrigerant, and thus contribute well to the lubrication inside the machine. That is, even under the most severe conditions with a small amount of refrigerant circulation, the maintenance of the compressor is sufficiently achieved. In addition, as shown in FIG. 3, when the detected pressure of the capacity control valve 50 is obtained as the outlet pressure of the evaporator 104, the temperature control of the evaporator 104 can be performed more accurately without being affected by the pressure loss of the suction system piping. Can be realized.

The refrigeration circuits of the other embodiments shown in FIGS. 4 and 5 have a compressor 100 of a clutchless type. As is apparent from FIG. A pulley 41 connected to the front housing 2 via a belt is fixed, and the pulley 41 is supported on the front housing 2 by a radial bearing 42. Then, a pipe P3 extending from the branch point S of the pressure supply pipe P6 to the expansion valve 103 is provided.
An electromagnetically operated valve (two-port normally open switching valve) 105 for selectively opening and closing the pipeline P3 is provided.

Therefore, when the automobile engine is started, the compressor 100 is simultaneously started via the pulley 41 and the drive shaft 6. If the solenoid operated valve 105 is in a cooling operation state in which the valve is opened as shown in FIG. 4 by operating a switch in the vehicle cabin, for example, the refrigeration circuit functions in the same manner as in the previous embodiment. When the cooling operation becomes unnecessary during the operation of the compressor 100 and the line P3 leading to the expansion valve 103 is closed by the OFF operation of the electromagnetic operation valve 105, the capacity control valve 50 based on the decrease in the suction system pressure. Is opened and the pressure supply line P6 is opened.
Is opened, and all of the high-pressure liquid refrigerant passing through the condenser 101 flows from the pressure supply line P6 to the crank chamber 5 of the compressor 100.
Which causes a rapid rise in the crankcase pressure, causing the swash plate 12 to move to the minimum tilt position,
Shifts to the minimum capacity state. Then, a small amount of refrigerant gas sent from the compressor 100 is supplied to the condenser 101, the pressure supply line P6 (capacity control valve 50), the crank chamber 5, and the bleed passage P.
7, the suction chamber 30, the bore 8, and the discharge chamber 31 are continuously circulated in the same route.

In this case, the circulating refrigerant is cooled and liquefied by passing through the condenser 101 as described above, and is further decompressed by the throttle action of the capacity control valve 50 to be vaporized in the crank chamber 5. Cooling and lubrication of the compressor 100 are kept in very good condition. In this way, the compressor 100 during the cooling operation unnecessary period only sucks and discharges a small amount of the refrigerant gas, and can suppress most of the rotational power to friction loss.
An opening of at least the side of the crank chamber 5 is disposed in the vicinity of the periphery of the drive shaft 6, so that the outflow of the liquid refrigerant to the suction chamber 30, that is, the liquid back is skillfully prevented.

A refrigeration circuit according to still another embodiment shown in FIGS. 6 and 7 is obtained by replacing the electromagnetically operated valve 105 and the thermostatic automatic expansion valve 103 employed in the other embodiment with an electronic expansion valve 60. Out. That is, as shown in FIG. 7, the electronic expansion valve 60 has a valve member 61 disposed so as to be movable in the axial direction, and a valve element 61 a formed at the tip of the valve member 61 can be seated on the valve seat 62. Have been. A nut member 63 is fixed to the base end of the valve member 61, and the nut member 63 is threaded on a rotary shaft 65 of a stepping motor 64.
The valve member 61 is moved in the axial direction by screwing with the valve member 5a.
Thus, the opening of the orifice between the valve element 61a and the valve seat 62 is adjusted, and the orifice is completely closed by the valve element 61a sitting on the valve seat 62. One end of the internal passage 66 is connected to a pipe P3 connected to the liquid receiver 102, and the other end is connected to a pipe P4 connected to the evaporator 104.

The opening and opening / closing of the electronic expansion valve 60 is controlled by a control unit 90. That is, the evaporator 10
The detection signal of the thermistor 90a disposed at the outlet of the control unit 90 is input to the control unit 90, and the control unit 90 responds to the detection signal.
From the electronic expansion valve 60.
And the opening is adjusted. Also, a command signal from an on / off switch disposed in the vehicle compartment is transmitted to the control unit 90.
The signal from the control unit 90 corresponding to the command signal is sent to the stepping motor 64 of the electronic expansion valve 60, and the opening and closing control of the electronic expansion valve 60 is performed.

That is, in the refrigeration circuit of the present embodiment, the use of the electronic expansion valve 60 not only enables the omission of the solenoid-operated valve 105 but also allows the opening degree to be adjusted with high accuracy in accordance with the detection signal of the thermistor 90a. It is possible to stably maintain the cooling capacity and the cooling efficiency.

[0039]

As described above in detail, since the present invention has the structure described in the claims, severe conditions such as a reduction in the discharge capacity of the compressor and a reduction in the amount of circulating refrigerant are obtained. Even below, compressor maintenance is fully achieved. Also, in a refrigeration circuit employing a clutchless variable displacement compressor, even when severe cooling operation is unnecessary, the compressor can be cooled and lubricated, and its durability and reliability can be significantly improved. At the same time, power losses can be minimized.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a refrigeration circuit according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a compressor used in the embodiment of the present invention.

FIG. 3 is a circuit diagram showing a modification of the detection pressure of the displacement control valve.

FIG. 4 is a circuit diagram showing a refrigeration circuit according to another embodiment of the present invention.

FIG. 5 is a sectional view showing a compressor used in another embodiment of the present invention.

FIG. 6 is a circuit diagram showing a refrigeration circuit according to still another embodiment of the present invention.

FIG. 7 is a partial sectional view showing an electronic expansion valve used in still another embodiment of the present invention.

[Explanation of symbols]

5 is a crank chamber, 30 is a suction chamber, 31 is a discharge chamber, 50 is a capacity control valve, 60 is an electronic expansion valve, 100 is a compressor, 10
1 is a condenser, 103 is an expansion valve, 104 is an evaporator, 105
Is a solenoid operated valve, P6 is a pressure supply line, and P7 is a bleed passage with a throttle.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Shigeyuki Hidaka 2-1-1, Toyota-cho, Kariya-shi, Aichi Prefecture Inside Toyota Industries Corporation (56) References JP-A-3-37378 (JP, A) (58) ) Surveyed field (Int.Cl. ⁷ , DB name) F25B 1/00-1/10 F04B 27/10

Claims (5)

(57) [Claims] A piston that reciprocates in a bore formed in a cylinder block, compresses and discharges refrigerant drawn from a suction chamber, and a piston that rotates together with a drive shaft in a crank chamber and that is based on pressure in the crank chamber. A swash plate element capable of changing the stroke of the piston and a bleed passage with a throttle communicating the crank chamber and the suction chamber. A refrigerant circuit for circulating the refrigerant through a condenser, an expansion valve and an evaporator, wherein a pressure supply line branched from a line from the condenser to the expansion valve and connected to the crank chamber is provided. ,
A refrigeration circuit using a variable displacement compressor, wherein a displacement control valve for constantly adjusting a crank chamber pressure in response to a suction system pressure is disposed in the pressure supply line. 2. The refrigeration circuit according to claim 1, wherein the capacity control valve is responsive to an outlet pressure of the evaporator. 3. A switching valve for directly connecting a drive shaft of the compressor to a power source via a pulley, and selectively opening and closing a line from a branch point of the pressure supply line to an expansion valve. 3. The refrigeration circuit according to claim 1, wherein the refrigeration circuit is arranged. 4. The refrigeration circuit according to claim 3, wherein said switching valve is an electromagnetically operated valve responsive to an on / off signal of the refrigeration circuit. 5. A drive shaft of the compressor is directly connected to a power source via a pulley, and the expansion valve is turned on and off of a refrigeration circuit.
3. The refrigeration circuit according to claim 1, wherein an electronic expansion valve controls opening and closing of the circuit by an off signal, and adjusts an opening degree of the circuit in accordance with a detection signal in the circuit.