JPH0429099Y2 - - Google Patents

Description

[Detailed description of the invention] [Purpose of the invention] (Field of industrial application) The invention is used for automotive cooling cycles,
The present invention relates to a control device for a variable capacity swash plate compressor capable of changing the internal volume of a compression chamber.

(Prior Art) FIG. 5 is a diagram showing a cooling cycle 1 used in a general automobile air conditioner. When a compressor 3 is driven by an engine (not shown) via a belt, a pulley 2, and a magnetic clutch 2a, the compressor 3 adiabatically compresses the gaseous refrigerant to a high temperature and high pressure, and supplies the gaseous refrigerant to a 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 from the refrigerant,
The refrigerant is throttled and expanded in the expansion valve 6 and flows into the evaporator 7 as a low-pressure mist of refrigerant. As a result, the air flowing into the vehicle interior is cooled by the evaporator 7 and becomes cold air, thereby cooling the vehicle interior.

When the cooling cycle 1 is activated, it has the effect of dehumidifying the air flowing into the vehicle interior, so the cooling cycle 1 can be used not only in the summer but also in the spring.
It is designed to operate in both summer and winter. In the normal compressor 3, compressor 3
The amount of refrigerant discharged per rotation of the rotor portion is always constant, and 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, if the outer surface of the evaporator 7 falls below a predetermined temperature, a thermoswitch 8 and an amplifier 9 are used to turn off the compressor 3. I'm trying to stop it. Therefore, when the outside air temperature is low and the heat load on the evaporator 7 is small, such as in the winter, the compressor 3 is turned on and off more frequently by the clutch 2a than when the heat load is large, such as in the summer. will be repeated. As a result, as shown by the dotted line a in FIG. 6, power consumption is achieved in accordance with the heat load of the evaporator, that is, the heat load of the cooling cycle (hereinafter referred to as "cycle load"), thereby saving energy.

However, in such a conventional compressor 3, the amount of refrigerant discharged per revolution is always constant, so the compressor must also rotate at a high speed, especially when the engine speed is high. However, it becomes difficult to control the refrigerant flow rate according to the cycle load using only the expansion valve, and power consumption inevitably increases.

Therefore, recently, as the compressor 3 used in such a cooling cycle 1, the
A variable capacity swash plate type compressor having a structure shown in Japanese Patent No. 158382 has been proposed. In this variable capacity swash plate type compressor, the stroke of the piston in the cylinder is changed in accordance with the suction pressure of the compressor, so that the discharge amount of the compressor per rotation of the rotor is changed. Therefore, in such a variable capacity compressor, a desired amount of refrigerant depending on the cycle load is circulated within the cooling cycle while the suction pressure of the compressor is kept constant.

According to such a variable capacity compressor, for example, when the outside air temperature is low and the heat load is small, but 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, the evaporation pressure of the refrigerant in the evaporator 7 is prevented from becoming too low due to excessive throttling in the expansion valve 6. Therefore, it is possible to avoid a so-called freezing phenomenon of the evaporator 7 at low load, which causes the condensed water in the evaporator 7 to freeze, and therefore a thermoswitch or the like to prevent this is not necessary.

In addition, even when the outside air temperature is high and the heat load is large, the capacity of the compressor changes accordingly, so as a result, the power consumption in the capacity control region changes as shown by the solid line b in Figure 6. can be reduced.

(Problems to be solved by the invention) However, in the case of such a variable capacity swash plate type compressor, as shown by the solid line b in Fig. 6,
In the capacity control region, power consumption can be reduced by allowing the refrigerant flow rate to flow through the cycle in accordance with the cycle load. However, at low loads outside the capacity control region, conventional compressors with a constant capacity can be replaced with thermoswitches. Compared to the one in which on/off control was performed by the method No. 8 (indicated by dotted line a in the figure), the power consumption was higher and the energy saving was inferior. This is because the variable capacity swash plate type compressor continues to rotate even under low load conditions outside the capacity control range, although the compressor's discharge capacity decreases.

The present invention was developed in view of these circumstances, and provides control for a variable capacity swash plate compressor that consumes less power and saves energy even when the cycle load is low outside the capacity control range. The purpose is to provide equipment.

[Structure of the invention] (Means for solving the problem) In order to achieve the above object, the present invention integrates a plurality of pistons, which are mounted in a cylinder block so as to be able to reciprocate in the axial direction, into a drive shaft. The piston is rotated and reciprocated by a driving swash plate attached so that its inclination angle can be changed, and the pressure in the compression chamber formed in front of the piston and the pressure in the crank chamber formed in the rear of the piston are adjusted. In the variable capacity swash plate type compressor, the stroke of the piston is changed by changing the inclination angle of the drive swash plate in accordance with a change in the differential pressure of the compressor. a cycle load detection means for detecting; a comparison means for comparing whether the cycle load detected by the cycle load detection means is greater than or equal to a predetermined value; and a crank for changing the pressure in the crank chamber in accordance with an output signal from the comparison means. a room pressure control means; a time measuring means for measuring whether the cycle load calculated by the comparing means continues to be below a predetermined value for a predetermined time or more; It is characterized by comprising a clutch control means for controlling drive stop.

(effect) Next, the operation of the present invention will be explained based on FIG.

First, the thermal load acting on the evaporator in the cooling cycle is detected as a cycle load by the cycle load detection means 70. Next, comparison means 71 performs a comparison calculation to determine whether the cycle load detected by cycle load detection means 70 is greater than or equal to a predetermined value. If the cycle load calculated by comparison means 71 is equal to or higher than a predetermined value, it is considered that a large load is acting on the cooling cycle. The pressure is adjusted, the stroke of the reciprocating piston is increased, and an appropriate flow rate of refrigerant flows through the cycle in response to the large load. Furthermore, if the cycle load calculated by the comparison means is less than or equal to a predetermined value, it is considered that the heat load acting on the cooling cycle is relatively small, so in this case, the crank chamber pressure control means 72 The refrigerant pressure is controlled, the stroke of the reciprocating piston is reduced, and an appropriate flow rate of refrigerant is allowed to flow within the cycle in accordance with the small heat load.

Further, if the cycle load calculated by the comparing means remains below a predetermined value for a predetermined time or more, the time measuring means 73 detects this state, and in that case, the cooling cycle is so affected that the capacity cannot be controlled. Since it is considered that a low load is acting on the compressor, the clutch control means 74 stops driving the compressor. By controlling in this way,
As shown by the dashed-dotted line c in FIG. 6, even under low load outside the capacity control region, power consumption is reduced and energy can be saved.

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

Figure 1 is a block diagram showing the configuration of the present invention;
The figure is a schematic configuration diagram of a variable capacity swash plate compressor and its control device according to an embodiment of the present invention, and FIG. 3 is a flowchart showing the operation of the embodiment.
4A to 4C are schematic cross-sectional views of a variable capacity swash plate type compressor according to the same embodiment, and members common to those shown in FIG. 5 are denoted by the same reference numerals, and some explanations thereof will be omitted.

As shown in FIGS. 2 and 4, the variable capacity swash plate compressor 50 according to this embodiment includes a cylinder block 24, a crankcase 17 attached to the rear end of the cylinder block 24, and a crankcase 17 attached to the tip of the cylinder block 24. The compressor body 10 includes a head 30. For example, five pistons 23 are mounted within a cylinder 25 formed in the cylinder block 24 so as to be able to reciprocate in the axial direction. On the other hand, a crank chamber 12 is formed in the crankcase 17, and a drive rod 11a is fixed to the drive shaft 11, which is rotatably supported by the cylinder block 24 and the crankcase 17.
A drive swash plate 13 is mounted within the crankcase 12 so as to be rotatable about a pin 11b.
Therefore, this drive swash plate 13 rotates together with the drive shaft 11, and also rotates together with the drive shaft 11.
The angle of inclination relative to the base is freely variable.

A non-rotating wobble plate 16 is in contact with the drive swash plate 13 through a thrust bearing 14 at its radial end surface and a radial bearing 15 at its inner peripheral surface. The angle changes as the inclination angle changes. The movement of the non-rotating wobble plate 16 in the thrust direction is regulated by a thrust washer 20 and a snap spring 21. The non-rotating wobble plate 16 is connected to a shoe 19 slidably connected to a guide pin 18 fixed to a casing 17.
Rotation is prevented and movement in the direction of the drive shaft 11 is guided.

The piston 23 and the non-rotating wobble plate 16 are connected by a rod 22, and as the inclination angle of the drive swash plate 13 changes, the reciprocating stroke of each piston 23 is changed via the non-rotating wobble plate 16. Things are starting to change.

A valve plate 27 is attached between the cylinder block 24 and the head 30.
A compression chamber 26 is formed on the front surface of the piston 23, and a crank chamber 1 is formed on the rear surface of the piston 23.
It communicates with 2. As shown in the figure, this valve plate 27 has a suction port 28a that communicates with a suction port 29 formed in the head 30, and a discharge port 28b that communicates with a discharge port 33 formed in the head 30.
is formed. Furthermore, this valve plate 27 has a suction port 28 during the suction process when the piston 23 moves backward.
A suction valve 34a is installed to open the valve a and close the discharge port 28a during the discharge process.
A discharge valve 34b opens the discharge port 28b during the discharge process in which the valve moves forward and closes the discharge port 28b during the suction process.
is installed.

The inclination angle of the drive swash plate 13 is changed by changing the pressure difference before and after the piston 23, that is, by changing the pressure inside the crank chamber 12. In order to control this pressure, a pressure control valve 51 is attached to the head 30, and a valve body 52 embedded in the head 30 has a
A suction side pressure chamber 32 is formed which communicates with the suction port 29 via a communication path 31. This valve body 52 has a supply passage 53 formed in the cylinder block 24 and the head 30, and a suction port 29.
A suction-side communication passage 54 is formed that communicates the two via the suction pressure chamber 32 and the communication passage 31. Further, a discharge side communication passage 55 is formed in the valve body 52, which communicates the discharge port 33 with the supply passage 53 via a discharge side pressure chamber 35 formed in the head 30. Incidentally, one supply passage 53 may be formed corresponding to each of the suction side communication passage 54 and the discharge side communication passage 55.

A first electromagnetic valve 57 for opening and closing the suction side communication passage 54 is provided in the cylinder body 56 provided in the valve body 52.
Further, a second electromagnetic valve 58 for opening and closing the discharge side communication passage 55 is provided. These electromagnetic valves 57 and 58 are provided with a resilient force by a coil spring 59 in the direction of closing the communication passages 54 and 55, respectively.

In order to control the opening and closing of the first electromagnetic valve 57, the pressure control valve 51 actually has a
An electromagnetic coil 60 is provided. Further, in order to control opening and closing of the second electromagnetic valve 58, an electromagnetic coil 61 is provided on the valve body 52. These electromagnetic coils 6
0 and 61 are connected to a microcomputer (hereinafter simply referred to as "microcomputer") 62 shown in FIG. 2, which includes a built-in circuit corresponding to the crank chamber pressure control means 72. In addition to the crank chamber pressure control means 72 shown in FIG. 1, the microcomputer 62 includes circuits corresponding to a comparison means 71, a time measurement means 73, and a clutch control means 74. Further, a pressure sensor 63 for detecting the pressure of the refrigerant on the outlet side of the evaporator 7 is connected to the microcomputer 62, as shown in FIG. This pressure sensor 63 is
This corresponds to the cycle load detection means 70 shown in FIG. 1, and detects the heat load acting on the cooling cycle. Furthermore, the microcomputer 62 includes the drive shaft 11 and pulley 2 of the variable capacity swash plate compressor 50.
A clutch 2a is connected to control the transmission of driving force to and from the clutch 2a. The clutch 2a is for appropriately transmitting the rotational force of the pulley 2 connected to the driving engine via a belt or the like to the drive shaft 11.

Next, the operation of the control device for the variable capacity swash plate compressor having such a configuration will be explained with reference to the flowchart shown in FIG.

In step 80, when the automobile cooling cycle is activated and the control device according to the present embodiment is activated, first, the microcomputer 62 shown in FIG.
In order to initialize the time t, the time measuring means 73 shown in FIG. 1, which is built in the 100, substitutes t=0 (step 81).

Next, in step 82, the refrigerant pressure on the discharge side of the evaporator 7, that is, the refrigerant pressure on the suction side of the compressor 50 (compressor suction pressure) Ps is read from the pressure sensor 63 shown in FIG. This Ps has a correlation with the heat load acting on the evaporator 7, that is, the heat load (cycle load) of the cooling cycle, and from this, the cycle load can be known.

Next, in step 83, it is determined whether this compressor suction pressure Ps is greater than a predetermined pressure Po. This determination is made by comparison means 71 built into the microcomputer 62. If the compressor suction pressure Ps is greater than the predetermined pressure Po, this indicates that the cycle load is high. Therefore, in such a case, proceed to steps 84 and 85. In addition, in the opposite case, the cycle load is determined to be low, so in this case, the step
Go to 89, 90.

In steps 84 and 85, the crank chamber pressure control means 7
2, the first solenoid valve 57 is opened and the second solenoid valve 58 is closed, as shown in FIG. 4A. By opening the first solenoid valve 57 in this manner, a compressor suction pressure Ps lower than the compressor discharge pressure (compressor discharge pressure) Pd is generated in the crank chamber 12 through the suction side communication passage 54 and the supply passage 53. , the pressure difference between the pressure acting on the rear surface of the piston and the pressure acting on the front surface during the suction stroke as shown in FIG. The drive swash plate 13, that is, the non-rotating wobble plate 1
The inclination angle of No. 6 with respect to the drive shaft 11 becomes larger.
As a result, the stroke of the reciprocating piston 23 becomes longer, the compressor discharge capacity for the same number of revolutions increases, and an appropriate flow rate of refrigerant corresponding to the high load flows into the cycle. Note that FIG. 4A shows the illustrated piston 23 advanced to the top dead center, and FIG. 4B shows the illustrated piston 23.
This shows the state in which the motor has retreated to the bottom dead center.

Next, in step 86, the time measuring means 73 shown in FIG. 1 initializes the time t and substitutes t=0.

Next, in step 87, the clutch control means 74 shown in FIG. 1 continues to keep the clutch 2a in the ON state, and the compressor 50 continues to move. and,
In step 88, it is determined whether the control has ended or not. If the control is to be continued, the process returns to step 82; otherwise, the control is ended (step 100).

If it is determined in step 83 that the compressor suction pressure Ps is less than the predetermined pressure Po, it is considered that the cycle load is low, and in that case, the process proceeds to steps 89 and 90. There, by the action of the crank chamber pressure control means 72 shown in FIG. 1, as shown in FIG. 4C, the first
Close the solenoid valve 57 and open the second solenoid valve 58. When the second electromagnetic valve 58 opens in this manner, the compressor discharge pressure Pd of the discharge port 33, which is a relatively high pressure, is supplied into the crank chamber 12 via the supply path 53.
Then, the piston 23 (fourth
The pressure difference between the front and rear of the piston in the state shown in FIG. As a result, the inclination angle of the non-rotating wobble plate 16 becomes almost perpendicular to the drive shaft 11. Therefore, the reciprocating stroke of the piston becomes shorter, the discharge capacity of the compressor for the same number of rotations decreases, and an appropriate flow rate of refrigerant corresponding to the low load flows into the cycle.

Next, in step 91, the time measuring means 73 shown in FIG. It's getting old.

In step 92, the time measuring means 7 shown in FIG.
3 turns the timer on, assigns t=1, and moves to step 87.

Also, in step 93, t+1 is substituted for time t, and the timer is used to step 82→83→89→90→91.
Measure the loop time of →93→94→82. This loop time indicates the time when the cycle load is low.

Next, in step 94, it is determined whether the loop time t is longer than a predetermined time. This loop time t
is longer than the predetermined time to, the cycle load is very small and is considered to be a low load outside the capacity control region shown in FIG. 6. In that case, the clutch control means 74 shown in FIG. Declutch 2a
is controlled, and transmission of the rotational force of the pulley 2 to the drive shaft 11 of the compressor is interrupted (step 95).
Therefore, by performing such control, even when the cycle load is low outside the capacity control region, as shown by the dashed line c in FIG.
Power consumption is reduced.

Also, in step 94, the loop time t is set to a predetermined time.
If it is below, the process returns to step 82. This is to prevent the compressor from stopping due to malfunction or the like.

Note that the present invention is not limited to the embodiments described above, and can be modified in various ways.

For example, the cycle load detection means 70 is not limited to the pressure sensor 63, but may be a temperature sensor that detects the temperature of the refrigerant on the discharge side of the evaporator 7, or a combination of the pressure sensor and the temperature sensor. The sub-cooling amount detecting means for the refrigerant may be made of: Furthermore, since the cycle load can be estimated by detecting the pressure inside the crank chamber, the cycle load detection means 70 may be a pressure sensor provided inside the crank chamber. Further, since the cycle load can be estimated by detecting the compression ratio of the compressor, the cycle load detection means 70 may be a compression ratio detection means of the compressor.

Further, the crank chamber pressure control means 72 is not limited to a control method using an electromagnetic valve, but may be a mechanical self-supporting method using, for example, a bellows or the like.

[Effects of the invention] As explained above, according to the invention, in a variable capacity swash plate type compressor, the operation of the compressor is stopped during low cycle loads outside the capacity control area, so that the cycle load is controlled by the capacity control. This has the excellent effect of reducing power consumption even when the load is low outside the range, thereby improving the fuel efficiency of the engine that drives the compressor and saving energy.

[Brief explanation of the drawing]

Figure 1 is a block diagram showing the configuration of the present invention;
The figure is a schematic configuration diagram of a variable capacity swash plate compressor and its control device according to an embodiment of the present invention, and FIG. 3 is a flowchart showing the operation of the embodiment.
4A to 4C are schematic cross-sectional views of a variable capacity swash plate compressor according to the same embodiment, FIG. 5 is a schematic diagram showing an automobile cooling cycle, and FIG. 6 is a compressor control device according to the conventional example and the present invention. It is a graph showing the effect of. 11... Drive shaft, 12... Crank chamber, 13...
... Drive swash plate, 16 ... Wobble plate, 23 ... Piston, 26 ... Compression chamber, 28a ... Suction port,
28B...Discharge port, 54...Suction side communication path,
55...Discharge side communication path, 57...First solenoid valve, 5
8...Second solenoid valve, 62...Microcomputer, 63...
Pressure sensor, 70... Cycle load detection means, 7
1... Comparison means, 72... Crank chamber pressure control means, 73... Time measuring means, 74... Clutch control means.

Claims (1)

[Claims for Utility Model Registration] A plurality of pistons 23 mounted in a cylinder block 24 so as to be able to reciprocate in the axial direction are connected to the drive shaft 11.
The pressure in the compression chamber 26 formed in front of the piston 23 and the pressure in the compression chamber 26 formed in the rear of the piston 23 are reciprocated by a drive swash plate 13 which rotates integrally with the piston 23 and is attached with a variable inclination angle. In the variable capacity swash plate type compressor, the stroke of the piston 23 is changed by changing the inclination angle of the drive swash plate 13 in accordance with a change in the pressure difference between the pressure inside the crank chamber 12 and the pressure inside the crank chamber 12. Cycle load detection means 63, 70 for detecting the heat load of the cooling cycle to which the compressor is attached, and comparison means 7 for comparing whether the cycle load detected by the cycle load detection means is equal to or higher than a predetermined value.
1, crank chamber pressure control means 51, 72 for changing the pressure in the crank chamber 12 according to the output signal from the comparison means; Crank chamber pressure control means 51, 72 for changing the pressure; time measuring means 73 for measuring whether the cycle load calculated by the comparing means 71 remains below a predetermined value for a predetermined time or more; and the time measuring means 7. A control device for a variable capacity swash plate type compressor, comprising clutch control means 2a and 74 for controlling driving and stopping of the compressor according to an output signal from a compressor.