JPH0355828Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The present invention relates to a control device for a compressor used in an automobile cooling cycle, and in particular, a variable capacity swash plate type compressor that can change the internal volume of a compression chamber. This invention relates to improvements in control devices for.

(Prior Art) As shown in FIG. 6, a cooling cycle 1 used in a general automobile air conditioner is driven by an engine (not shown) via a belt, a pulley 2, and a magnetic clutch 2a. a compressor 3; a condenser 4 that exchanges heat with external air to convert the gaseous refrigerant that has been adiabatically compressed into a high temperature and high pressure state into a low temperature and high pressure liquid refrigerant;
A liquid tank 5 temporarily stores this liquid refrigerant and removes moisture and dust in the refrigerant, and an expansion valve 6 that squeezes and expands this liquid refrigerant to form a low-pressure mist refrigerant.
It is comprised of an evaporator 7 that vaporizes this low-pressure mist refrigerant and cools the air blown into the vehicle interior.

A device for controlling the compressor 3 is shown in FIG. 7, and is constructed as follows.

A switch 50 that operates the coil 52 and contacts 53 of a relay 51 and the compressor 3 is connected to the battery B that operates this circuit via a fuse F that protects the circuit. A coil 57 of a relay 56 is connected to the switch 50 via an abnormality detection device 55 that detects an abnormal temperature of the evaporator 7. Further, the contact 53 includes a contact 58 of a relay 56 connected to the FICD 60 that increases the idling speed of the engine, and a contact 58 of the magnetic clutch 2.
A contact 59 of a relay 56 is connected to the coil 52, and an acceleration cutoff switch 54 is connected to the coil 52, which operates when the vehicle suddenly accelerates or climbs up the hill.

The circuit configured in this way has the switch 5
0 is ON, and when both the abnormality detection device 55 and the acceleration cut switch 54 are not working, the FICD 60 and the magnetic clutch 2a operate.

On the other hand, the compressor 3 used in such a cooling cycle 1 has recently been developed by Japanese Patent Application Laid-Open No.
A swash plate type compressor having a structure shown in Publication No. 158382 has been proposed. In this swash plate type compressor, the internal volume of the compression chamber in the cylinder is changed in accordance with the suction pressure of the compressor, thereby changing the discharge amount of the compressor, so that the suction pressure of the compressor remains constant.

When the suction pressure of the compressor 3 shown in FIG. 6 becomes constant, the refrigerant pressure at the outlet of the evaporator 7 (that is, the evaporation pressure of the refrigerant in the evaporator 7) becomes constant to some extent. Therefore, when the heat load becomes small, for example when you want to dehumidify using the evaporator 7 when the outside air temperature is low, the expansion valve 6 that tries to keep the amount of superheat at the outlet of the evaporator 7 constant This is convenient because it is possible to avoid the so-called freezing of the evaporator under low load, which occurs when the refrigerant is throttled too much to improve performance, lowering the evaporation pressure of the refrigerant in the evaporator 7, and causing the condensed water in the evaporator 7 to freeze.

FIGS. 8 and 9 show the structure of a swash plate compressor in which the internal volume of the compression chamber in the cylinder is changed in accordance with the suction pressure of the compressor, so that the suction pressure is kept constant as a result.

As shown in the figure, the variable capacity swash plate type compressor 3 has a drive shaft 11 that is rotationally driven by an engine via a belt, a pulley 2, and a magnetic clutch 2a. A drive rod 11 a is fixed to the drive shaft 11 in a direction perpendicular to the shaft 11 and rotates together with the drive shaft 11 within the crank chamber 12 . A drive swash plate 13 is connected to the drive rod 11a at an angle with respect to the drive shaft 11 using a pin 11b as a fulcrum, so that the rotational force of the drive shaft 11 is transmitted to the drive swash plate 13 via the pin b. ing. A non-rotating wobble plate 16 is slidably connected to the drive swash plate 13 via a thrust bearing 14 and a radial bearing portion 15. The radial bearing portion 15 is formed on the inner peripheral side of the wobble plate 16, and its thrust direction movement is caused by the thrust washer 2.
0 and a snap spring 21.

The wobble plate 16 is connected to a shoe 19 that is slidably connected to a guide pin 18 fixed to a casing 17, and the shoe 19 prevents rotation and guides movement in the direction of the drive shaft 11. It is becoming more and more like this. This wobble board 1
Pistons 23 are connected to each of the pistons 6 at approximately equal intervals in the circumferential direction via a plurality of rods 22, and the rotation of the drive swash plate accompanying the rotation of the drive shaft 11 causes the non-rotating wobble plate 16 to swing. , piston 23
is starting to move back and forth.

This piston 23 is mounted in a cylinder 25 formed in a cylinder block 24. Inside the cylinder 25, a compression chamber 2 is provided in front of the piston 20.
6 is formed, and the rear surface of the piston 20 communicates with the crank chamber 12.

A suction port 27 and a discharge port 28 are formed in the compression chamber 26 . This suction port 27 is connected to the suction port 2 to which the refrigerant from the evaporator 7 shown in FIG.
9 through a valve (not shown). This suction port 29 communicates with a suction side pressure chamber 32 via a communication passage 31 formed in the head 30.
Further, the discharge port 28 communicates with a discharge port 33 that communicates with a pipe for feeding refrigerant into the condenser 4 shown in FIG. This discharge port 33 communicates with a discharge side pressure chamber 35 .

In the suction side pressure chamber 32, a first control valve 36 is held by a bellows part 37, and the bellows part moves up and down according to the pressure inside the suction side pressure chamber 32 to control the opening degree of the suction side communication port 41. It's starting to adjust.
Further, a second control valve 39 is connected to the first control valve 36 via a rod 38, and the two control valves operate in conjunction with each other. This second control valve 39
is provided in the discharge side pressure chamber 35 and is adapted to adjust the opening degree of the discharge side communication port 40.

These first and second control valves 36 and 39 are controlled by a bellows portion 37 that moves up and down according to the pressure inside the suction side pressure chamber 32, and when the pressure inside the suction side pressure chamber 32 becomes high, the suction side communication port 41 The opening degree of the discharge side communication port 40 is increased, and as the opening degree becomes lower, the opening degree of the discharge side communication port 40 is increased. Therefore, when the heat load in the cooling cycle is small, the pressure in the suction side pressure chamber 32 becomes low, the bellows part 37 extends upward, the opening degree of the discharge side communication port 40 is increased, and the crank chamber 12 to increase its internal pressure. Therefore, the pressure difference between the front and rear sides of the piston 23 during the suction stroke increases, and as shown in FIG. 9, a moment acts on the wobble plate 16 and the drive swash plate 13 in the direction of raising them relative to the drive shaft 11. Therefore, the reciprocating stroke of the piston 23 is shortened, the internal volume of the compression chamber 26 is reduced, and the flow rate of refrigerant circulating within the cooling cycle is reduced, resulting in an appropriate flow rate of refrigerant corresponding to the low heat load. The suction pressure of the compressor gradually increases, and as a result, the suction pressure is kept constant.

Further, when the heat load in the cooling cycle is large, the pressure in the suction side pressure chamber 32 increases,
The bellows part 37 moves downward, and the suction side communication port 41
Since the opening degree of the crank chamber 12 is increased and suction pressure is introduced into the crank chamber 12, its internal pressure becomes approximately equal to the suction pressure. Therefore, the pressure difference between the front and rear of the piston 23 during the suction stroke is almost eliminated, and as shown in FIG.
The reciprocating stroke of the piston 23 becomes longer. Therefore, the internal volume of the compression chamber 26 increases, and the flow rate of refrigerant circulating within the cooling cycle increases, resulting in an appropriate flow rate of refrigerant corresponding to the high heat load, so the suction pressure of the compressor gradually decreases, resulting in The suction pressure is maintained at a constant level.

(Problem to be solved by the invention) Capacity control in such a variable capacity swash plate compressor is effective only within a predetermined capacity control range, as shown in Figure 5, and is not effective in other ranges. I couldn't go to

In particular, during low heat loads outside the capacity control range, the pressure Pc in the crank chamber 12 suddenly becomes equal to the compressor discharge pressure PD, as shown by the dotted line in FIG. The pressure difference between the For this reason, the 9th
As shown in the figure, the wobble plate 16 and the drive swash plate 1
3 rises to the maximum angle with respect to the main shaft 11,
Furthermore, since a moment acts in the direction of raising the wobble plate 16, an abnormal force acts in the direction of shearing the thrust washer 20 and the snap spring 21. Such an abnormal force is not preferable because it not only accelerates fatigue of the thrust washer 20 and the snap spring 21 but also causes uneven wear of the radial bearing portion 15.

The present invention was developed to solve the above-mentioned problems, and when the load is low and the capacity cannot be controlled effectively, abnormal force is applied to the sliding part between the wobble plate and the drive swash plate. It is an object of the present invention to provide a compressor control device having a function of stopping the variable capacity swash plate type compressor when the above-mentioned variable capacity swash plate type compressor occurs.

(Means for solving the problem) A compressor discharge pressure detection means for detecting the pressure of refrigerant discharged from a compressor that compresses refrigerant, and a compressor crank chamber for detecting the pressure inside a crank chamber formed in the compressor. The pressure detection means calculates the difference between the discharge pressure and the crank chamber pressure detected by the compressor discharge pressure detection means and the compressor crank chamber pressure detection means, and generates a signal when this difference is smaller than a set value. The present invention is characterized in that it is provided with a calculation means for outputting a signal, and a compressor stop signal output means for outputting a stop signal to a device that controls the compressor when a signal is output from the calculation means.

(effect) The operation of the present invention will be explained below.

Calculates the difference between both pressures based on signals from a sensor that detects the pressure of the refrigerant discharged from the variable capacity swash plate compressor and a sensor that detects the pressure inside the crank chamber formed within the variable capacity swash plate compressor. However, when this differential pressure is smaller than a predetermined value, an abnormal force will be applied to the sliding part between the wobble plate and the drive swash plate, so the magnet that transmits the engine output to the variable capacity swash plate compressor will By turning off the net clutch, the variable capacity swash plate compressor can be protected.

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIG. 4 shows a schematic sectional view of a variable capacity swash plate type compressor according to the present invention.

As shown in the figure, the variable capacity swash plate compressor 3 has the same mechanical structure as that shown in FIG. 8, but the casing 17 of the variable capacity swash plate compressor 3 according to the present invention includes: a crank chamber pressure detection sensor 71 that detects the pressure within the crank chamber 12 formed in the compressor 3;
A discharge pressure detection sensor 70 that detects the pressure inside the discharge side pressure chamber 35 is inserted. These sensors 70 and 71 are connected to a control device that controls the compressor 3.

Next, a schematic configuration diagram of the control device is shown in FIG. 2, and is configured as follows. The coil 5 of the relay 51 is connected to the battery B that operates the circuit through the fuse F that protects the circuit.
2. A contact 53 and a switch 50 for operating the compressor 3 are connected. A low load detector 61 is connected to the switch 50 to detect a low load on the compressor 3 based on signals output from the crank chamber pressure detection sensor 71 and the discharge pressure detection sensor 70. Further, a coil 57 of a relay 56 is connected to the low load detector 61 via an abnormality detection device 55 that detects abnormal temperature of the evaporator 7 .

Further, the contact point 53 includes a contact point 58 of a relay 56 connected to the FICD 60 that increases the idling speed of the engine, and a magnetic clutch 2.
A contact 59 of a relay 56 is connected to the coil 52, and an acceleration cutoff switch 54 is connected to the coil 52, which operates when the vehicle suddenly accelerates or climbs up the hill.

The operation of the circuit configured as described above will be explained in detail based on the program flowchart shown in FIG.

STEP 1 First, both counters i and T are initialized to 0.

STEP 2 The compressor 3 is compressed by the discharge pressure sensor 70.
The discharge pressure PD in the discharge side pressure chamber 35 formed in
is detected and a signal is sent to the low load detector 61.

STEP 3 The pressure inside the crank chamber 12 formed in the compressor 3 by the crank chamber pressure sensor 71
PC is detected and a signal is sent to the low load detector 61.

STEP 4 It is determined whether the counter i is 0 or not. If i is 0, proceed to STEP5; if i is not 0, proceed to STEP11.

STEP 5 It is determined whether the difference between the discharge pressure PD and the pressure P detected in STEP 2 and STEP 3 is smaller than the set value a. If PD-Pc<a, proceed to STEP6; if PD-P≧a, proceed to STEP10.

STEP 6 In STEP 5, if it is determined that PD-Pc<a, the timer is activated.

STEP 7 It is determined whether the timer counter T is equal to the set value B. If T=B, proceed to STEP 8; if T≠B, return to STEP 2.

STEP 8 Set counter i to 1.

STEP 9 Since the compressor 3 continues to operate under low load, a signal is output from the calculation means 72 shown in FIG.
The circuit connecting coil 57 is opened, and contacts 58 and 59 of relay 56 are opened.
FICD 60 and magnetic clutch 2a stop their operations.

STEP 10 If it is determined that PD-Pc≧a in STEP 5,
The timer counter T is set to 0,
Return to STEP2.

STEP 11 If it is determined that i is not 0 in STEP 4,
In the same way as processed in STEP5, STEP2 and
It is determined whether the difference between the discharge pressure PD and the pressure Pc detected in STEP 3 is smaller than a set value a.
If PD-Pc<a, proceed to STEP9, PD-Pc≧a
If so, return to STEP1.

As explained above, this program detects that a low load on the compressor has continued for a predetermined period of time or more and stops the compressor. A computer or hardware may be used to process this program.

(Effects of the invention) As described above, the present invention includes a compressor discharge pressure detection means for detecting the pressure of refrigerant discharged from a compressor that compresses refrigerant, and a compressor discharge pressure detection means for detecting the pressure inside the crank chamber formed in the compressor. Calculating the difference between the compressor crank chamber pressure detecting means, the discharge pressure and crank chamber pressure detected by the compressor discharge pressure detecting means and the compressor crank chamber pressure detecting means, and the difference is smaller than a set value. By providing a calculation means that outputs a signal at certain times, and a compressor stop signal output means that outputs a stop signal to a device that controls the compressor when the signal is output from the calculation means, the compressor can be operated under low load. This has the effect of preventing local fatigue and wear of the compressor components caused by continuous use.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a compressor control device according to the present invention, FIG. 2 is a schematic configuration diagram of a compressor control device according to the present invention, and FIG. 3 is a flowchart of a program of a compressor control device according to the present invention. , FIG. 4 is a schematic cross-sectional view of the variable capacity swash plate type compressor according to the present invention, FIG. 5 is a graph showing the discharge pressure and crank chamber pressure with respect to the heat load of the conventional variable capacity swash plate type compressor, and FIG. , a schematic configuration diagram of a general cooling circuit, FIG.
Schematic configuration diagram of a conventional compressor control device, No. 8
9 and 9 are schematic cross-sectional views of a conventional variable capacity swash plate type compressor. 2a...Magnetic clutch, 3...Compressor, 12...Crank chamber, 35...Discharge side pressure chamber, 61...Low load detector, 70...Discharge pressure sensor, 71...Crank chamber pressure sensor.

Claims (1)

[Scope of utility model registration request] Compressor discharge pressure detection means 70 that detects the pressure of refrigerant discharged from the compressor 3 that compresses refrigerant; Compressor crank chamber pressure detection means 71 that detects the pressure within the crank chamber 12 formed in the compressor 3. , calculates the difference between the discharge pressure and crank chamber pressure detected by the compressor discharge pressure detection means 70 and the compressor crank chamber pressure detection means 71, and outputs a signal when this difference is smaller than a set value. A compressor control device characterized in that it is provided with a calculation means 72 for calculating the compressor, and a compressor stop signal output means 73 for outputting a stop signal to a device controlling the compressor 3 when a signal is output from the calculation means 72. .