JPS62247184A - Variable displacement swash plate type compressor - Google Patents

Abstract

PURPOSE:To improve the fuel consumption of an engine, by controlling a displacement of a refrigerant discharged from a compressor and a pressure of the refrigerant in an evaporator according to a heat load of the evaporator. CONSTITUTION:A signal from a temperature sensor 62 for detecting a temperature of a refrigerant flowing into a suction port and a signal from a pressure sensor 63 for detecting a pressure are inputted to a computing means 64 to compute a super heat value of the refrigerant. The super heat value computed is inputted to a comparing means 80 to compare same with a super heat value data. Then, the compared value is inputted to a compressor operating means 70 for operating a pressure regulating valve 51 and an expansion valve control means 67 for controlling an expansion valve 6 to control a suction pressure of a compressor and an opening angle of the expansion valve 6 according to a heat load of an evaporator. Accordingly, the compressor may be properly controlled according to the condition of the heat load of the evaporator, thereby improving the fuel consumption of an engine.

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention J (Industrial Field of Application) The present invention relates to a variable capacity swash plate compressor that is used in an automatic stream cooling cycle and is capable of changing the internal volume of a compression chamber.

(Prior Art) Fig. 6 is a diagram showing a cooling cycle 1 used in a general air layer f4' device for automobiles, in which a compressor 3 is operated by an engine (not shown) via a belt, a pulley 2, and a magnetic clutch 2a. When driven, the gaseous refrigerant that has been adiabatically compressed by the compressor 3 to a high temperature and high pressure is supplied to the condenser 4. In this condenser 4, the refrigerant is cooled by exchanging heat with external air, and becomes a high-pressure liquid refrigerant.

The refrigerant that has passed through the liquid tank 5, which temporarily stores this liquid refrigerant and removes moisture and dust in the refrigerant, is throttled and expanded in the expansion valve 6, and flows into the evaporator 7 as a low-pressure mist refrigerant. As a result, the air flowing into the vehicle interior is cooled by the evaporator 7, and the interior of the vehicle is cooled. Such a cooling cycle is shown in FIG. 7 using a Mollier diagram.

When such cooling cycle 1 is operated, it has the effect of dehumidifying the air flowing into the vehicle interior, so cooling cycle 1 is operated not only in summer JIIJ but also in spring, Ω, and winter. There is.

In a normal compressor 3, the amount of refrigerant discharged per rotation of the rotor section of the compressor 3 is always constant.
The amount of refrigerant flowing into the evaporator 7 is controlled by the expansion valve 6 according to the heat load. In order to prevent the condensed water adhering to the outer surface of the evaporator 7 from freezing, the compressor 3 is stopped by a thermoswitch (not shown) when the outer surface of the evaporator 7 becomes less than a predetermined moisture level. I am trying to make it so that
When the outside temperature is low and the heat load on the evaporator 7 is small, such as in winter, p! J! Compressor 3 engages clutch 2 more frequently than when the load is large.
By a, the on-ono will be repeated. In addition, as mentioned above, in a normal compressor 3 in which the discharge amount of refrigerant per revolution is constant, even when the heat load is small, the power required to drive the compressor is different from when the heat load is large. do not have.

Therefore, as a compressor 3 used in such a cooling cycle 1, recently, Japanese Patent Application Laid-Open No. 58-158.38
A swash plate compressor having a structure shown in Publication No. 2 has been proposed. In this swash plate type compressor, the stroke of the piston within the cylinder is changed in accordance with the suction pressure of the compressor, thereby changing the discharge amount of the compressor. Therefore, a desired amount of refrigerant is circulated according to the heat load of the evaporator 7 while keeping the suction pressure of the compressor constant.

According to such a variable air compressor, although the outside air temperature is low and the heat load is small, when the cooling cycle 1 is operated to perform dehumidification in the evaporator 7, the refrigerant flowing through the entire cooling cycle 1 is Since the amount of refrigerant is small, it is avoided that the M pressure of the refrigerant in the evaporator 7 becomes too low due to excessive throttling in the expansion step 6. Therefore, it is possible to avoid a so-called freezing phenomenon of the evaporator 7 during low load, which causes condensed water in the evaporator 7 to freeze, and therefore a thermoswitch or the like for preventing this is not necessary.

(Problem to be Solved by the Invention) In such a conventional variable capacity swash plate compressor, since the stroke of the piston is changed based on the suction pressure of the compressor 3, for example, 2
．． When using Freon 12, which becomes saturated vapor at 0°C at a pressure of g/cd, the pressure of the refrigerant in the evaporator 7 should be adjusted so that the condensed water in the evaporator 7 does not freeze.
In other words, the suction pressure ps of the compressor 3 is 2. IKq/ca
The flow rate of the refrigerant in the cooling cycle 1 is controlled by tl by changing the stroke of the piston so that t.

However, when the heat load on the evaporator 7 is large, such as under the scorching sun in midsummer, even if the evaporation pressure of the refrigerant in the evaporator 7 is lowered below the above-mentioned 2.1 KG/cm, the temperature of this refrigerant is lower than 0°C. Even if the pressure is lowered, the condensed water in the evaporator 7 will not freeze, but considering the case where the heat load is small, it is necessary to always maintain the above-mentioned suction pressure PS in order to prevent freezing. Therefore, conventionally, even when the heat load on the evaporator 7 is quite large, the expansion valve 6 is not necessarily throttled down, and the amount of refrigerant discharged from the compressor 3 is increased to achieve the desired cooling. Furthermore, when the cooling cycle is started under the scorching sun, it takes time for the evaporation pressure in the evaporator 7 to reach the predetermined one shift, so the so-called cool-down characteristics are not improved.

As mentioned above, the pressure at the outlet of the evaporator 7, that is, the suction pressure of the compressor 3 is always, for example, 2.1
Kg/aj to tilltll,, if the evaporator 7 is like spring, autumn and winter 1tll
Even when the thermal load on the compressor 3 is small, the pressure inside the vaporizer 7 is controlled to the above-mentioned value by relatively strong throttling with the dilation valve 6, and the load on the compressor 3 is relatively large.

In addition, even if the temperature of the outside air is the same, the humidity of the outside air is large.
In regions where the air conditioner is heated, the heat dissipation capacity applied to the condenser 4 and the heat load applied to the evaporator 7 may not correspond to the predetermined relationship, and the cooling cycle is inevitably not in a proper operating state.

For example, if the heat dissipation capacity of the condenser 4 is set considering the operation of the cooling cycle 1 in a relatively humid region, if the cooling cycle is operated in a dry region, condensed water will flow into the evaporator 7. Since there is less slippage, the heat load on the evaporator 7 is reduced. This also applies when the cooling cycle is changed from a state in which air from outside the vehicle is supplied to the evaporator 7 to a state in which air from inside the vehicle is introduced into the evaporator 7. In other words, the air inside the vehicle is evaporator 7
Since the condensed water is removed by the evaporator 7, it is drier than the outside air, and when such dry air is introduced into the evaporator 7, the evaporator 7 The heat load is reduced.

It is clear from the psychrometric diagram shown in diagram M5 that the heat load on the evaporator 7 necessarily differs depending on the humidity state of the air introduced into the evaporator 7. In other words, air with a soft bulb temperature of 25°C and a relative humidity of 65% is transferred to the evaporator 7.
The enthalpy △h1 in this evaporator 7 when the soft bulb temperature is 70°C and the relative humidity is 88%, and the enthalpy △h1 when the 92 bulb temperature is 25°C and the relative humidity is 40% as described above. Comparing the enthalpy Δh2 when air is introduced into the evaporator 7 and cooled until the soft ball temperature reaches 70°C in the evaporator 7, the enthalpy indicating the heat load of the evaporator 7 is determined by the latent heat of the condensed water. It is understood that the heat load on the evaporator 7 will be smaller if the dry air is cooled.

In view of the above-mentioned problems of the prior art, the present invention has been developed to change the inclination angle of the drive swash plate based on the pressure at the outlet of the evaporator, that is, the inlet of the compressor in the conventional variable capacity swash plate compressor. However, by detecting the heat load state of the evaporator based on the superheat discharge of the refrigerant at the compressor inlet and controlling the compressor discharge capacity accordingly, the compressor can be operated with less driving force. The purpose is to make it possible to operate.

[Structure J of the Invention (Means for Solving the Problems) The present invention for achieving the above object includes a plurality of pistons mounted in a cylinder block so as to be movable in the axial direction and connected to a drive shaft. It rotates integrally and reciprocates by a drive swash plate attached so that its inclination angle can be changed, and the pressure in the compression chamber formed in front of the screw and the pressure in the compression chamber formed in the rear of the piston are In a variable capacity swash plate type compressor, the inclination angle of the drive swash plate is changed according to a change in the pressure difference between the pressure in the crank chamber and the stroke of the piston (6). a pressure control valve having a first solenoid valve that opens and closes a suction side communication passage to communicate with the crank chamber; and a second solenoid valve that opens and closes a discharge side communication passage that communicates the discharge boat and the crank chamber; a control means for calculating a superheat value of the refrigerant flowing into the suction port based on signals from a temperature sensor that detects temperature and a pressure sensor that detects pressure; and a signal from the superheat value data and the control means. a comparison means for comparing the superheat value signal of the controller, a compressor control means for sending an iQ control signal to the compressor operation means for operating the pressure control valve in response to the signal from the comparison means, and a and an expansion valve control means that sends a control signal to an expansion valve operating means that controls the opening degree of the expansion valve according to the signal, and controls the suction pressure of the compressor and the opening degree of the expansion valve according to the thermal load of the evaporator. This is a variable capacity swash plate type compressor characterized by being controlled.

(Operation) The superheat value of the refrigerant in the evaporator, that is, in the suction boat flowing into the compressor, is calculated based on the signals from the temperature sensor and the pressure sensor. Then, based on this kneeper heat value, it is detected whether the heat load on the evaporator is in a high region, a medium region, or a small region.

When the pressure is in the high range, the expansion valve is placed in an intermediate throttling state by a signal from the expansion valve control means, and the compressor is placed in a low pressure setting control state. Further, when the heat load is in the medium range, the compressor 1 is in a state of reference pressure control, and the expansion 37 controls the refrigerant law according to a signal from the expansion valve control means. Furthermore, when the heat load is in a small region, the expansion jt is at the minimum throttle, and the compressor is at the reference pressure? It becomes a state of S control. In this way, by controlling the expansion valve opening and the compressor suction pressure according to the heat load of the evaporator, it is possible to properly control the compressor with less driving force, and the engine for driving the compressor can be controlled. It becomes possible to achieve lower fuel consumption.

(Example) An embodiment of the present invention will be described below.

FIGS. 1A to 1C are cross-sectional views showing a variable capacity swash plate compressor according to an embodiment of the present invention, and FIG. 2 is a block diagram showing a control device according to the embodiment.

In the present invention, the super top-1 of the evaporator 7
Since it is possible to detect the value of the heat load on the evaporator 7 by detecting the amount, the pressure inside the rank chamber is electrically controlled, and the opening degree of the expansion valve is electrically driven to open/close. This controls the compressor. As is clear from FIG. 7, the amount of heat load on the evaporator 7 corresponds to the superheat fitsH within the evaporator 7.

This superheat m5) J is determined by the temperature and pressure P of the refrigerant at the outlet of the evaporator 7, and the state shown by the imaginary line in FIG. 7 is when the pressure of the refrigerant flowing into the compressor 3 is shown by the solid line. Even if it is similar to
A case is shown in which superheat WksH increases due to a rise in temperature. This situation occurs when the heat load on the evaporator 7 is large compared to the amount of refrigerant that has passed through the expansion valve.

The variable capacity swash plate compressor 3 of the present invention has a compressor main body 70 consisting of a cylinder block 24, a crankcase 17 attached to the rear end of the cylinder block 24, and a head 30 attached to the tip of the cylinder block 24. The cylinder 25 formed in the cylinder block 24
Inside, for example, five pistons 2 are movable in the axial direction.
3 has been improved. A crank chamber 12 is formed in the crankcase 17, and a drive 1111 is rotatably supported by the cylinder block 24 and the crankcase 17.
A drive rod 11aIfi is fixed to the drive rod 11.
A drive side Fi 13 is attached to the crank case 72 so as to be rotatable about the bin 11b. Therefore, this drive side #fi13 is drive 1! I! 11, it rotates together with this, and the inclination angle with respect to the drive 4m11 is variable.

A non-rotating wobble plate 16 is in contact with the drive swash plate 13 through a thrust bearing 14 on its radial end surface and a radial bearing 15 on its inner peripheral surface.
6 is adapted to change the angle by changing the inclination angle of the drive swash plate 13. Note that movement of the non-rotating wobble plate 16 in the thrust direction is restricted by a thrust washer 20 and a snap ring 21. The non-rotating wall plate 16 is slidably connected to the guide pin 1B fixed to the casing 17.
9, the shaft 19 prevents rotation and guides movement in one direction of the drive shaft.

The piston 24 and the non-rotating wobble Fi 16 are connected to the rod 2
2, and as the inclination angle of the drive swash plate 13 changes, the reciprocating stroke of each piston 24 changes via the non-rotating wobble plate 16.

A valve plate 2 is provided between the cylinder block 24 and the head 30.
7 is attached, and a compression chamber 26 is formed between the valve plate 27 and the front surface of the piston 20.
The rear surface of the engine 0 communicates with the crank chamber 12. This valve plate 2
As shown in Figure 7, a suction port 28a is formed which communicates with the suction boat 29 formed in the head 30.
A discharge port 28b communicating with a discharge boat 33 formed in
is formed. Furthermore, this valve plate 27 has a piston 2
A suction valve 34a is installed which opens the suction port 28a and closes the suction port 28a during the reverse stroke during the suction stroke B in which the piston 23 moves backward, and during the discharge stroke when the piston 23 moves forward, the discharge port 28b is opened during the reverse stroke. A discharge valve 34b is attached to close the discharge port 28b during the process.

The inclination angle of the drive swash plate 13 is changed by changing the pressure within the crank chamber 12. In order to control this pressure, the head 30 has a pressure t++wJ valve 5.
1 is attached to the valve body 52 embedded in the head 30, a suction side pressure g32 is formed which is communicated with the suction boat 29 via the communication path 3]. This valve body 52 is connected to one of the two supply passages 53a and 53b formed in the cylinder block 24 and the head 30, and the suction boat 29 via the suction pressure chamber 32 and the communication passage 3. A suction side communication path 54 is formed for communication. Further, a discharge side communication passage 55 is formed in the valve body 52, which communicates the discharge port 33 with the supply passage 53b via the discharge side pressure chamber 35 formed in the head 30.

A first solenoid valve 57 for opening and closing the suction side communication passage 54 is provided in a cylinder 56 provided in the valve body 52, and a second solenoid valve 5B for opening and closing the discharge side communication passage 55. is provided. These electromagnetic valves 57 and 58 are given a resilient force by a coil spring 59 in the direction of closing the respective communication passages 54 and 55. In order to control the opening and closing of the first shoulder valve 57, the valve body 52 is provided with an electromagnetic coil 60, as shown in FIG. 52 is provided with six electromagnetic coils.

As shown in FIG. 6, the evaporator 7 and compressor 3
A temperature sensor 62 for detecting the temperature of the refrigerant flowing into the compressor 3 is attached to the pipe connecting the compressor 3, and a pressure sensor 63 for detecting the pressure of this refrigerant is further attached.

The temperature and pressure information fH of this refrigerant is detected by these sensors 62.
63, as is clear from the Mollier diagram shown in FIG.
is calculated. In order to calculate this, the temperature sensor 62
and pressure sensor 63 are connected to calculation means 64 of a microcomputer.

The calculation means 64 is connected to the comparison means 80, and the signal from the calculation means 64 is sent to the comparator Vj, 80, and R
The signal from the reference superheat value data 81 stored in the OM and the signal from the calculation means 64 are compared by the comparison means 80, and a signal of the N difference amount Bh (expansion valve control means 67, combustor υ control means 68 sent to.

As shown in FIG. 4, the expansion valve 6 of the present invention has a refrigerant flow path 71
The valve body 72 that adjusts the opening degree by K111 is driven by a pulse motor 69 as an expansion valve operating means shown in FIG. Motor 79 is activated. Also,
] The pressure control valve 51 in the compressor 3 is operated by the signal from the compressor 1 control means 68 via the compressor operation/cutting means 6 and 3.

The comparison calculation means 64 calculates the superheat value 5t-1 of the refrigerant flowing into the compressor 3 based on the signal from the temperature sensor and the signal from the pressure sensor 63, and sends the result to the comparison means 80. As a result, the evaporator 7
The signal differs depending on whether the superheat value S1 in the area is in a small region or a medium region, and whether it is in a high region.
It is issued to the expansion valve i1d control means t11267 and the compressor control means 81.

When the superheat value SR is in a small area, it is when the heat load on the evaporator 7 is small, such as in winter, and when it is in a high area, it is when the heat load on the evaporator 7 is small, such as in the midsummer sun.
This is a case where the heat load is large, and when it is in the middle range, it is a case where the evaporator 7 has a negative fA load that is about the middle of the above-mentioned cases. Note that even under the scorching sun in midsummer, this heat load may be reduced by the humidity of the air sent to the evaporator 7, as described above.

If the superheat value SH is in a small area, the expansion valve 6
is set to the 4λ state in which the 51 body 72 considerably restricts the flow 171, that is, the minimum restriction state. And compressor 3
At this time, the pressure of the refrigerant in the evaporator 7 is
．． It should be about 3.1 verse/ci higher than IKV (
The pressure R11I'njT 51 is controlled.

If the superheat value 5t-( occurs in the middle region, the expansion valve 6 atllft!l the cabinet of the flow path 71 so that the superheat (1α5)-1 enters the region,
The compressor 3 is pressure controlled so that the pressure of the refrigerant in the evaporator 7 becomes the reference pressure, that is, 2.1 q/cffi.

When the superheat value 311 is in the high range, the valve body 72 of the expansion valve 6 is set to an intermediate throttle state in which the flow path 7 is slightly throttled, and the compressor 3 is operated at the reference pressure 2.1. nig/cti J: For example, 1.
The pressure is set to about 8 (]/crd).

The block diagram shown in FIG. 2(B) is a diagram showing the ft, l control means of the compressor according to another embodiment of the present invention. In this case, the heat load of the evaporator 7 is controlled by the superheat value SH. It detects the state (not just when the cooling cycle 1 starts), but also attempts to improve the so-called cool-down characteristics.

Therefore, the pressure sensor 63 is connected to the high pressure determining means 65 and the high pressure state where the cooling cycle 1 is almost uniform, such as when the cooling cycle 1 starts to start, is recorded in the ROM. ! ! The high voltage determining means 65 detects the high voltage by comparing it with the signal from the high voltage data 66 that has been detected. The high pressure value of the refrigerant d3 in the population section of the compressor 3 before the compressor 3 operates is:
For example, the pressure is about 7 Ka/cM.

This 1st and 3rd pressure determination means 65 is connected to the expansion 11[f control means 67 and the compressor control means 68, and is connected to the expansion 11[f control means 67 and the compressor control means 68,
The opening degree of the expansion valve t6 is controlled via the second operating means 69, and the first electromagnetic valve 60 and the second electromagnetic valve 61 are controlled via the compressor operating means 70 in response to a signal from the combination control stage 68. Pressure control V↑51 is controlled. When the pressure at the inlet of the compressor 3 is equal to or higher than the predetermined pressure (7 Ko/cti), the valve body 72 in the expansion valve 6 is activated by a signal from the high pressure determining means 65.
is controlled so that the flow path 71 is completely closed or almost completely closed. Further, in response to a signal from the high pressure determination means 65, the pressure side m-valve 51 determines that the refrigerant pressure in the suction boat 29 of the compressor 3, that is, the pressure at the outlet of the evaporator 7, is the reference pressure, for example, the above-mentioned 2.1 KQ/l''/
May it be A! 1JiI! It will be IIl.

Next, the operation of the variable capacity swash plate compressor having such a configuration will be explained with reference to the flowchart shown in FIG. Incidentally, FIG. 3 is a flowchart showing the control of the variable capacity swash plate type compressor 3 of the present invention having the control means shown in FIG. 2(B).

As the refrigerant circulates within the cooling cycle as the drive shaft 11 rotates, the pressure Ps of the refrigerant d5 in the suction boat 29 is detected by the pressure sensor 63, and the temperature T of the refrigerant is detected by the temperature sensor 62. is detected (step ■■). These signals are sent from the performance means 65 shown in FIG. 2 to the comparison means 80, and first the super heat value SH
It is determined whether or not the area is a high area (step ■). If it is in the high range, this is when the heat load on the evaporator 7 is large, such as under the scorching sun in midsummer, and at this time, the expansion tube t6 is in the middle throttle state (step ■),
The pressure of the refrigerant in the evaporator 7, that is, the compressor 3
The pressure PS of the suction boat 29 is the reference pressure 2. Pressure 1.8KQ/c lower than 1 to 17/ri
Five pressure control valves operate so that i (step ■
). In this case, the refrigerant in the evaporator 7 is lower than the standard pressure of 2.1 Klll/C at which it becomes OoC, but since the heat load on the evaporator 7 is high, even if the temperature of the refrigerant in the evaporator 7 becomes lower than 0°C. Freezing of condensed water does not occur. In this way, the temperature of the refrigerant in the evaporator 7 is OoC
Since it is set lower than , it is possible to improve the cooling capacity in a state of high heat load.

When the heat load is large like this, it is necessary to discharge a large amount of refrigerant from the compressor 3, as shown in Fig. 1 (A>
As shown in , the first solenoid valve 57 of the pressure control valve 51 is controlled so that the second solenoid jf5B is closed.

As the first electromagnetic valve 57 listens in this way, a suction pressure P which is lower than the discharge pressure Pd is created in the crank chamber 2.
Since S is guided through the suction side communication M54 and the supply path 53, the pressure acting on the surface of the screws 1 to 1 in the suction process (not shown) becomes smaller than the pressure acting on the front surface. As shown in Figure 1 (Δ) (B), drive swash plate 1
3, that is, the inclination angle of the non-rotating wobble slope 16 with respect to the drive shaft 11 becomes large. In addition, FIG. 1 (A>) shows the state in which the illustrated piston 23 has advanced to the top dead center, and FIG. 7 (B) shows the 4λ state in which the illustrated piston 23 has reached the bottom dead center. .

If it is determined that the super heat 1 direct SH is in the middle range (step ■), in this case the heat load on the evaporator 7 is less than in the above case, and the expansion valve 6 has a valve body 72. The opening and closing of the cold gX flow path 71 is controlled (in steps) so that the medium chain J is reached, and the pressure of the refrigerant in the evaporator 7, that is, the pressure PS of the suction boat 29 of the compressor 3, is set to the reference pressure as described above. 2.1KI
)/-, the pressure control valve 51 is operated (step ■).

In this case, since the pressure of the refrigerant in the evaporator 7 is set to the above-mentioned M sub-pressure 2.1 KQ/cti, freezing of condensed water in the evaporator 7 occurs even if the heat load is lower than in the above-mentioned case. Super Heat 1
The expansion valve 6 controls the flow rate of the refrigerant flowing into the evaporator 7 in response to a signal from the expansion valve control means 67 so that rfJ S H is in the middle range.

The discharge amount of the compressor 3 in this case is controlled by setting the inside of the crank chamber 12 to a predetermined pressure using the pressure control valve 51.

If it is determined that the super heat #FiSH is in a small region (step ■), in this case, the heat load at tT3 on the evaporator 7 is very small, such as in winter, and the expansion valve 6 is closed. The body 72 has a minimum constriction that considerably constricts the flow path 71 (Step Co., Ltd.). Further, the pressure is adjusted so that the pressure of the refrigerant in the evaporator 7, that is, the pressure PS of the suction boat 29 of the compressor 3, becomes a high pressure as described above, for example, 3.0 KQ/cti! i control valve 5
1 is activated (step ■). In this case, since the pressure of the refrigerant in the evaporator 7 is kept high, the driving torque of the compressor 3 is reduced, and the fuel efficiency of the engine for driving the compressor 3 is improved.

When the heat load is small in this way, the pressure ti (second electromagnetic j? of the J control valve 51, 58
Since the discharge port 33 is opened, the pressure is relatively high.
The pressure Pd is supplied into the crank chamber 12 via the supply lit 53b, and the inclination angle of the non-rotating wobble plate 16 is nearly perpendicular to the drive N111. As a result, the capacity of the refrigerant discharged from the compressor 3 decreases.

As shown in Figure 3, the temperature of the refrigerant in the evaporator 7 is quickly lowered, for example, when the cooling cycle 1 is started in midsummer. If you want to rapidly cool the interior of the vehicle, use the pressure sensor 63.
is in a state where the pressure of the refrigerant in the evaporator 7 is higher than during normal operation of the cooling cycle 1, e.g. 7.0, /
When it is detected that the cti is greater than or equal to cti (step @
), whether the valve body 72 of the expansion valve 7 completely closes the flow path 71, or
Alternatively, the expansion is controlled to a state of maximum aperture with only a slight opening (step 2). In this case, the pressure control 1 #51 of the compressor 3 is controlled until the pressure of the refrigerant in the evaporator 7 reaches the above-mentioned reference pressure. As a result, the expansion valve 6 becomes the maximum throttle state, so the refrigerant pressure in the evaporator 7 quickly decreases, and the evaporator 7
temperature will drop rapidly. When the pressure of the refrigerant in the evaporator 7 falls below the above-mentioned value, a predetermined ajlJ control is performed on the heat load of the evaporator 7 according to the superheat value SH.

[Effect of the Invention J As explained above, according to the present invention, the opening degree of the expansion 5↑ is controlled by an electric signal, and the pressure of the fluid supplied into the crankshaft is adjusted to a desired value by the electric signal. The pressure of the refrigerant in the evaporator is controlled based on the superheat hfi of the refrigerant flowing into the compressor, and the stroke of the piston is also controlled. The capacity of the discharged refrigerant and the pressure of the refrigerant in the evaporator are controlled, making it possible to control the compressor more appropriately by making the compressor correspond to the heat load state of the evaporator.

Thereby, the fuel efficiency of the engine for driving the compressor can be improved.

[Brief explanation of drawings]

Figures 1 (△) to (C) are schematic rIfI side views showing a variable capacity swash plate type compressor according to an embodiment of the present invention, and Figure 2 (C) is a variable capacity swash plate type compressor according to an embodiment of the present invention. A block diagram showing a compressor control device, FIG. 2 (8) is a block diagram showing a control wJ device according to another embodiment of the present invention,
3 is a flowchart showing the operating state of the wJ control device shown in FIG. 2(B), FIG. 4 is a sectional view showing the expansion valve of the present invention, and FIG. The psychrometric diagram, FIG. 6 is a schematic diagram showing a cooling cycle for an automobile, and FIG. 7 is a Mollier diagram of the cooling cycle shown in diagram M6. 11... Drive shaft, 12... Crank chamber, 13...
Drive swash plate, 16... wobble plate, 23... piston, 26... compression chamber, 28a... suction port, 28b
...Discharge boat, 54...Suction side communication path, 55...
・Discharge side communication path, 57...First solenoid valve, 58...Second solenoid valve, 62...Temperature sensor, 63...Pressure sensor, 64...Calculating means, patent applicant Nippon Radiator Co., Ltd. Figure 5 @ Figure 6

Claims (1)

[Claims] A plurality of pistons (23) mounted in the cylinder block (24) so as to be movable in the axial direction are connected to the drive shaft (11).
A compression chamber (26) formed in front of the piston (23) is configured to rotate integrally with the piston (23) and reciprocate by a driving swash plate (13) attached so that its inclination angle can be changed.
The stroke of the piston is changed by changing the inclination angle of the drive swash plate (13) by changing the pressure difference between the pressure in the crank chamber (12) and the pressure in the crank chamber (12) formed behind the piston (23). In the variable capacity swash plate compressor, a first electromagnetic valve (57) and a discharge port (33) open and close a suction side communication passage (54) that communicates the suction port (29) with the crank chamber (12). and a discharge side communication path (55) that communicates with the crank chamber (12).
) has a second solenoid valve (58) that opens and closes the pressure control valve (
51), a temperature sensor (62) that detects the temperature of the refrigerant flowing into the suction port (29), and a pressure sensor (63) that detects the pressure.
calculation means (64) for calculating the superheat value of the refrigerant flowing into the refrigerant (29); and comparison means (64) for comparing the signal from the superheat value data (81) and the superheat value signal from the calculation means (64). 80) and compressor operating means (70) for operating the pressure control valve (51).
a compressor control means (68) that sends a control signal in response to a signal from the comparison means (80); and a compressor control means (68) for controlling the opening degree of the expansion valve (6) in accordance with the signal from the comparison means (80). The expansion valve control means (67) sends a control signal to the expansion valve actuation means (69), and the suction pressure of the compressor and the opening degree of the expansion valve are controlled according to the thermal load of the evaporator. A variable capacity swash plate compressor featuring: