JPH0429100Y2 - - 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. 6 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 even in autumn 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, 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 high revolutions, especially when the engine speed is high. However, it became difficult to control the refrigerant flow rate according to the cycle load using only the expansion valve, and power consumption had to increase.

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 drive swash plate that reciprocates the piston changes the pressure in the crank chamber installed inside, thereby changing the stroke of the piston according to the suction pressure of the compressor. The discharge amount of each compressor 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.

Furthermore, even when the outside air temperature is high and the heat load is large, the capacity of the compressor changes accordingly, resulting in a reduction in power consumption.

(Problem to be solved by the invention) Recently, however, vehicles with higher engine speeds have been developed, and when such vehicles are equipped with the variable capacity swash plate type compressor, When the cycle load is high and the engine speed (that is, the compressor speed) increases, the amount of work done by the compressor increases, and the amount of heat generated by friction in the sliding parts of the compressor increases. There was a risk that the durability of the compressor would be impaired due to insufficient lubrication in the parts.

The present invention was developed in view of these circumstances, and provides control for a variable capacity swash plate type compressor that contributes to energy saving and improves durability by improving lubrication of the sliding parts of the compressor. 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 driving swash plate according to a change in the differential pressure of the variable capacity swash plate type compressor. a cycle load detection means for detecting; a cycle load comparison means for comparing whether the cycle load detected by the cycle load detection means is a predetermined value or more; and a compressor rotation speed detection means for detecting the actual rotation speed of the compressor; Limit rotation speed calculation means for calculating a limit compressor rotation speed at the cycle load based on the cycle load detected by the cycle load detection means; and the actual rotation speed detected by the compressor rotation speed detection means is the limit rotation speed. A compressor rotation speed comparison means for comparing whether the rotation speed is below the limit rotation speed calculated by the calculation means; and a crank chamber pressure for changing the pressure in the crank chamber according to output signals from the compressor rotation speed comparison means and the cycle load comparison means. control means, when the actual rotation speed compared by the compressor rotation speed comparison means is larger than the limit rotation speed, the crank chamber pressure is preferentially controlled based on the output signal from the crank chamber pressure comparison means. The present invention is characterized in that the pressure in the crank chamber is increased by the pressure control means, and the discharge capacity of the compressor is controlled to be decreased.

(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. at the same time,
A compressor rotation speed detection means 73 detects the actual rotation speed of the compressor (corresponding to the engine rotation speed). Next, based on the cycle load detected by the cycle load detection means, the limit rotation speed of the compressor at the cycle load is calculated by the limit rotation speed calculation means 74. Next, the actual rotation speed of the compressor detected by the compressor rotation speed detection means 73 (hereinafter referred to as "compressor rotation speed")
The compressor rotation speed comparison means 75 compares whether or not the rotation speed is larger than the limit rotation speed calculated by the limit rotation speed calculation means 74. If the actual compressor rotation speed is larger than the limit rotation speed, heat generation due to friction in the sliding parts of the compressor is large, which is not a desirable condition. is used to increase the pressure in the crank chamber.
This changes the reciprocating stroke of the piston and reduces the displacement of the compressor. Therefore, even if the rotational speed of the compressor does not change, the amount of work of the compressor itself decreases, making it possible to suppress heat generation in sliding parts and maintain good lubrication in those parts. becomes.

Further, when the compressor rotation speed calculated by the comparator rotation speed comparison means 75 is less than or equal to the limit rotation speed, the crank chamber pressure control means 72 is controlled in accordance with the output signal of the cycle load comparison means 71.
The cycle load comparison means 72 performs a comparison calculation to determine whether the cycle load detected by the cycle load detection means 70 is greater than or equal to a predetermined value. If the cycle load calculated by the cycle 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, so in this case,
The crank chamber pressure control means 72 adjusts the pressure in the crank chamber, increases the stroke of the reciprocating piston, and flows an appropriate flow rate of refrigerant into the cycle in accordance with the large load. Furthermore, if the cycle load calculated by the cycle comparison means 71 is less than or equal to the 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 Controls the pressure in the crank chamber,
The stroke of the reciprocating piston is made smaller, allowing an appropriate flow rate of refrigerant to flow within the cycle in accordance with the small heat load. Therefore, it contributes to fuel efficiency and energy saving of the engine that drives the compressor.

(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 sectional views of the variable capacity swash plate type compressor according to the same embodiment, and FIG. 5 is a graph showing the action of the limit rotation speed calculation means according to the same embodiment, and the members shown in FIG. The same reference numerals are given to the same members, 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 28a that communicates with a discharge port 33 formed in the head 30.
b is formed. Furthermore, this valve plate 27 has an inlet 2 at the time of the suction stroke when the piston 23 moves backward.
A suction valve 34a is installed which opens the suction port 8a and closes the suction port 28b during the discharge process.
The discharge valve 34 opens the discharge port 28b during the discharge process and closes the discharge port 28b during the suction process when the valve 3 moves forward.
b 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. Note that 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 has a built-in circuit corresponding to the crank chamber pressure control means 72, and the energization is controlled by this. It's getting old. In addition to the crank chamber pressure control means 72 shown in FIG. 1, this microcomputer 62 includes a cycle load comparison means 71, a limit rotation speed calculation means 74,
A circuit corresponding to the compressor rotation speed comparing means 75 is built-in. 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 corresponds to the cycle load detection means 70 shown in FIG. 1, and detects the heat load acting on the cooling cycle. Further, a rotation speed sensor 64 is connected to the microcomputer 62 and is attached to the pulley 2a or the drive shaft 11 to detect the rotation speed of the compressor 50. This rotation speed sensor 64 corresponds to the compressor rotation speed detection means 73 shown in FIG.

Next, the operation of the control device for such a variable capacity swash plate compressor will be explained based on the flowchart shown in FIG.

In step 80, when the automotive cooling cycle is activated and the control device according to the present embodiment is activated, first, the pressure sensor 6 shown in FIG. 2 is activated.
3, 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 into the microcomputer 62 (step 3).
81). This pressure 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 the cycle load can be determined from this.

Next, in step 82, the compressor limit rotation speed Nc at that cycle load is calculated based on the compressor suction pressure Ps. This calculation is performed by the limit rotational speed calculation means 74 shown in FIG. 1, which is built in the microcomputer 62 shown in FIG.
The limit rotation speed Nc is the limit rotation speed that does not adversely affect the durability of the compressor, and as shown in FIG. 5, it can be expressed as a function of cycle load. The straight line a showing the relationship between the cycle load and the limit rotational speed Nc shown in FIG. 5 is determined by, for example, experiments, and it can be seen that the larger the cycle load, the lower the limit rotational speed. Since such data shown in FIG. 5 is stored in the microcomputer 62, the limit rotation speed calculation means 74 calculates the limit rotation speed Nc based on this data.

Next, in step 83, the actual compressor rotation speed (compressor rotation speed) N is read into the microcomputer 62 by the rotation speed sensor 64 connected to the microcomputer 62.

Next, in step 84, the compressor rotation speed comparison means 75 shown in FIG. 1 compares whether the compressor rotation speed N read in step 83 is less than or equal to the limit rotation speed Nc calculated in step 82. If the compressor rotational speed N is less than the limit rotational speed Nc, the process goes to step 85; otherwise, the process goes to steps 89 and 90 preferentially.

Next, in step 85, it is determined whether this compressor suction pressure Ps is greater than a predetermined target suction pressure Pe. This determination is made by cycle load comparison means 71 shown in FIG. 1 built into the microcomputer 62. When the compressor suction pressure Ps is larger than the target suction pressure Pe, it indicates that the cycle load is high. Therefore, in such a case, proceed to steps 86 and 87. In the opposite case, it is determined that the cycle load is low, and in this case, the process goes to steps 89 and 90.

In steps 86 and 87, the crank chamber pressure control means 72 shown in FIG. 1 opens the first solenoid valve 57 and closes the second solenoid valve 58, as shown in FIG. 4A. By opening the first solenoid valve 57 in this manner, the compressor suction pressure Ps, which is lower than the compressor discharge pressure Pd, is guided into the crank chamber 12 via the suction side communication passage 54 and the supply passage 53. Therefore, 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. 4B becomes small, and the drive swash plate 13 as shown in FIGS. That is, the inclination angle of the non-rotating wobble plate 16 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 a state in which the illustrated piston 23 has advanced to the top dead center, and FIG. 4B shows a state in which the illustrated piston 23 has retreated to the bottom dead center.

Next, in step 88, it is determined whether or not to end the control. If it is to be continued, the process returns to step 82; otherwise, the control is ended (step 100). The decision whether to continue with this control is
For example, this is done based on whether the air conditioner switch is on.

In step 85, the compressor suction pressure Ps reaches the predetermined pressure Po.
If it is determined that the cycle load is low, please proceed to step 89.
Go to 90. There, by the action of the crank chamber pressure control means 72 shown in FIG. 1, as shown in FIG. 4C,
The first solenoid valve 57 is closed and the second solenoid valve 58 is opened.
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 in the suction process
(The state shown in Fig. 4B) The pressure difference between the front and rear of the piston becomes large, and the non-rotating wobble plate 1
A moment acts in the direction that makes 6 stand up. 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 rotational speed is reduced, allowing an appropriate flow rate of refrigerant to flow into the cycle in accordance with the low load.

Next, when steps 89 and 90 are completed, step
Go to 88, and if the control is not finished, repeat the steps described above.

According to such control, it is determined in step 84 whether the compressor rotation speed is below the limit rotation speed,
If the rotation speed is higher than the limit, step 89, 90
The compressor discharge pressure continues to be forcibly introduced into the crank chamber 12 to increase the pressure in the crank chamber 12, thereby minimizing the reciprocating stroke of the piston 23. If the reciprocating stroke of the piston 23 is minimized, even if the compressor rotation speed is high,
The displacement will be reduced and the amount of work done by the compressor will be reduced. If the amount of work of the compressor decreases, the limit rotational speed in that state relatively increases, and as a result, the rotational speed of the compressor is suppressed below the limit rotational speed. Therefore, in this case, the discharge capacity of the compressor cannot be controlled according to the cycle load, and there is a risk that sufficient cooling cannot be achieved, but the compressor should not be operated in a condition that impairs the durability of the compressor. can be avoided.

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, the crank chamber 12
Since the cycle load can be estimated by detecting the internal pressure, 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. Furthermore, since the cycle load can be estimated from the compressor discharge pressure itself, as a cycle load detection means,
It may also be a pressure sensor that detects the discharge pressure of the compressor.

Further, in the above embodiment, the pressure in the crank chamber 12 is electrically controlled by the crank chamber pressure control means 72 using the pressure control valve 51.
The present invention is not limited to this, and the crank chamber pressure control means 72 may be a self-supporting control valve using a bellows or the like that automatically opens and closes depending on the surrounding pressure.

[Effect of the invention] As explained above, according to the invention, in the variable capacity swash plate type compressor, the rotational speed of the compressor is always below the limit rotational speed, so there is no excessive load on the sliding parts of the compressor. This eliminates the generation of frictional heat, eliminates the occurrence of poor lubrication in the sliding parts, and has the excellent effect of improving the durability of the compressor. Furthermore, as long as the rotational speed of the compressor is below the limit rotational speed, the discharge capacity of the compressor is also controlled according to the heat load in the cooling cycle, contributing to fuel efficiency and energy saving of the engine that drives the compressor.

[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 sectional views of the variable capacity swash plate type compressor according to the same embodiment, FIG. 5 is a graph showing the action of the limit rotation speed calculation means according to the same embodiment, and FIG.
The figure is a schematic diagram showing an automobile cooling cycle. 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, 64... Rotation speed sensor, 70... Cycle load detection means, 71... Cycle load comparison means, 72... Crank chamber pressure control means, 73...
Compressor rotational speed detection means, 74... limit rotational speed calculation means, 75... compressor rotational speed comparison 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 installed; cycle load comparison means 71 for comparing whether the cycle load detected by the cycle load detection means is equal to or greater than a predetermined value; and the compressor. compressor rotation speed detection means 64, 73 for detecting the actual rotation speed of the compressor, and limit rotation speed calculation means 74 for calculating the limit compressor rotation speed at the cycle load based on the cycle load detected by the cycle load detection means. , a compressor rotation speed comparison means 75 for comparing whether the actual rotation speed detected by the compressor rotation speed detection means 73 is equal to or less than the limit rotation speed calculated by the limit rotation speed calculation means 74; and the compressor rotation speed comparison means 75. and a crank chamber pressure control means 72 that changes the pressure in the crank chamber 12 according to the output signal from the cycle load comparison means 71, and the actual rotation speed compared by the compressor rotation speed comparison means 75 is the limit. If the rotation speed is greater than the
Based on the output signal from the crank chamber pressure comparison means 75, the crank chamber pressure control means 7
2. A control device for a variable capacity swash plate type compressor, characterized in that the pressure in the crank chamber 12 is increased by 2, and the discharge capacity of the compressor is controlled to be decreased.