JP2000002179A - Variable capacity swash plate type compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a variable capacity swash plate type compressor, which can meet the requirements of the product performance in all external air temp. load regions while the capacity control stability is secured. SOLUTION: A variable capacity swash plate type compressor is composed of a bellow chamber 64 formed in a valve case, bellows 37 installed in the chamber 64 to expand and contract with the pressure of a refrigerant, a first passage R1 to put the discharge port in communication with inside a crank chamber 12 through a valve port 47 whose degree of opening is controlled by expansion and contraction of the bellows 37, a second passage R2 to put inside the crank chamber 12 in communication with the suction port 29, a third passage R3 to generate communication between inside the crank chamber 12 and the suction port 29 via the bellow chamber 64, a solenoid valve V1 installed on the third passage R3 between the inside the crank chamber 12 and the bellow chamber 64, and an auto-amplifier 100 to open the solenoid valve V1 in case the discharge side pressure Pd of the compressor is below the specified value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable displacement swash plate type compressor, and more particularly to a variable displacement type swash plate type compressor capable of satisfying an operation performance relating to dehumidification and the like at low outside air while ensuring a stable capacity control. .

[0002]

2. Description of the Related Art A variable displacement swash plate type compressor is known as a compressor used in an air conditioner for a vehicle. In the variable displacement swash plate compressor, pistons inserted into a plurality of cylinder bores formed at equal intervals in the circumferential direction are continuously reciprocated through swinging of the swash plate. The amount of refrigerant discharged can be adjusted by changing the inclination angle of the swash plate that swings in accordance with the change in the cooling load in the vehicle compartment.

As one of the mechanisms for changing the inclination angle of the swash plate in such a variable displacement swash plate type compressor, as shown in FIG. 6, a communication passage for communicating a crank chamber with a suction chamber 29 is provided. The chamber and the discharge chamber 33 are provided so as to communicate with each other through a supply passage R1 for discharge pressure, a control valve 39 is provided interposed in the supply passage R1, and the control valve 39 expands and contracts the bellows 37 due to a change in suction-side pressure. There has been proposed a device which can be freely opened and closed via a cable (see Japanese Patent Publication No. 4-74549).

In this variable displacement swash plate compressor, when the cooling load is large, the control valve 39 is closed, the crank chamber pressure becomes the same as the suction side pressure, and the swash plate swings with a large inclination angle. On the other hand, when the cooling load is small, the control valve 39 is opened and the discharge side pressure is supplied to the crank chamber, whereby the swash plate swings with a small inclination angle. Is obtained.

As described above, by adjusting the supply of the discharge side pressure to the crank chamber by the control valve 39 linked to the expansion and contraction of the bellows 37, the inclination angle of the swash plate is quickly changed in response to the fluctuation of the cooling load. It is possible to make it.

[0006]

However, in the variable displacement swash plate type compressor described in the above publication, although a change in the suction side pressure can be sensed, stable displacement control can be performed. There was a problem.

That is, when considering the control diagram of the control valve represented by the relationship between the discharge side pressure Pd and the suction side pressure Ps shown in FIG. 7, the control valve shown in FIG. Control (which is a straight line in the figure) must be performed.

On the other hand, the discharge-side pressure Pd is linked to the ambient temperature load, and the lower the suction-side pressure Ps, the more work the compressor performs. In summer, when the discharge-side pressure Pd is high, the suction-side pressure Ps If the pressure is too high, sufficient cooling power cannot be obtained (the shaded area indicated by Su in the figure), and if the suction side pressure Ps is too low, the evaporator may freeze or the compressor may be damaged (the shaded area indicated by Sl in the figure). region). In winter, when the discharge side pressure Pd becomes low, if the suction side pressure Ps is too high, dehumidification is insufficient and window fogging occurs, and the control line of the control valve is higher than the control line of the expansion valve in the figure. Therefore, there is a possibility that control interference will occur and the refrigerant flow will fluctuate (shaded area indicated by Wu in the figure), and if the suction side pressure Ps is too low, the evaporator may freeze (Wl in the figure). Hatched area).

For this reason, the control line of the linear control valve should be set so as to avoid the performance failure area shown by hatching in FIG. 7 so as to satisfy the operation performance as a product in all the outside air temperature load areas. However, there is a problem that the dehumidifying ability of the evaporator may be reduced and control interference with the expansion valve may occur particularly at a low outside air temperature load.

The present invention has been made in view of the above-mentioned problems of the prior art, and has as its object the following:
It is an object of the present invention to provide a variable displacement swash plate type compressor capable of satisfying product performance in all outside air temperature load regions while ensuring displacement control stability.

[0011]

According to a first aspect of the present invention, there is provided a bellows chamber formed in a valve case, and a bellows provided in the bellows chamber, which expands and contracts by the pressure of a refrigerant. A first flow path that communicates between a discharge port and a crank chamber through a valve opening whose opening is controlled by expansion and contraction of the bellows, a second flow path that communicates the crank chamber with the suction port, A third passage that passes through the chamber and communicates the crank chamber with the suction port, a valve disposed between the crank chamber and the bellows chamber of the third passage, and a discharge pressure of the compressor. Control means for controlling the opening degree of the valve based on the pressure, and adjusting the pressure in the crank chamber to adjust the stroke of the piston to adjust the amount of refrigerant discharged. It is an expression compressor.

According to a second aspect of the present invention, in the variable displacement swash plate type compressor according to the first aspect, there is provided a pressure detecting means for detecting a discharge side pressure of the compressor,
The control means performs control so as to open when the discharge-side pressure falls below a predetermined value.

According to a third aspect of the present invention, in the variable displacement swash plate type compressor according to the first aspect, the control means is a mechanical valve that operates based on the discharge side pressure. I do.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing a variable displacement swash plate type compressor according to an embodiment of the present invention.
FIG. 3 is a schematic block diagram for explaining an operation mechanism of the control valve shown in FIG. 1, and FIG. 3 is a configuration diagram of a refrigeration cycle showing installation locations of a discharge-side pressure sensor shown in FIG.

Variable capacity swash plate type compressor 3 shown in FIG.
Changes the volume of the compression chamber in the cylinder 25 according to the suction pressure of the refrigerant returning to the compressor 3,
The amount of refrigerant discharged from the compressor 3 is adjusted so that the suction pressure of the compressor 3 becomes constant.

The variable displacement swash plate type compressor 3 has a drive shaft 11 which is rotationally driven by an engine via a belt, a pulley 2 and a magnet clutch 2a.
A drive rod 11 a is provided on the drive shaft 11 in a direction perpendicular to the drive shaft 11, and rotates together with the drive shaft 11 in the crank chamber 12. A drive swash plate 13 is connected to the drive rod 11a so that the drive swash plate 13 can tilt and swing with respect to the drive shaft 11 with the pin 11b as a fulcrum. The signal is transmitted to the swash plate 13. A non-rotating socket plate 16 is slidably attached to the drive swash plate 13 via a thrust bearing 14 and a radial bearing 15. The socket plate 16 has a shoe 19 slidably connected to a guide pin 18 fixed to a body casing 17 of the crank chamber 12, the rotation of which is prevented by the shoe 19, and the axial reciprocation. Is acceptable. A plurality of piston rods 22 are attached to the socket plate 16 at equal intervals in the circumferential direction, and a piston 23 is connected to the other end of the piston rod 22.

The rotation of the drive swash plate 13 causes the socket plate 16 to reciprocate in the axial direction by performing a so-called razor-like operation, whereby the piston 23 is reciprocated via the piston rod 22 and the piston 23 is reciprocated. 23
The front side portion of the piston 23 of the cylinder 25 into which is inserted is a compression chamber, and the rear side portion communicates with the crank chamber 12.

The cylinder head 30 is provided with a suction port 29 and a discharge port 33. The return port refrigerant from the evaporator flows into the suction port 29, and the refrigerant returns to the suction port 27 opened in the valve plate 20. It flows into a compression chamber formed in the cylinder bore 26 against the closing resilience of the suction valve 34 to be closed.

After passing through the suction side pressure chamber 32 which is in communication with the suction port 29 formed in the cylinder head 30, the refrigerant passes through the first communication passage C1 and communicates with the inside of the bellows chamber 64. Has become.

On the other hand, the compressed refrigerant flows out to the discharge port 33, and the discharge port 2 formed in the valve plate 20 is opened.
A pipe (not shown) for sending the refrigerant discharged from the condenser 8 to the condenser is connected to the condenser.
It also flows into the discharge-side pressure chamber 35 formed therein.

A control valve Cv for sensing the suction pressure Ps of the return refrigerant of the variable displacement swash plate type compressor 3 is provided in a valve chamber V opened in the cylinder head 30. The control valve Cv has a valve case h mounted in the valve chamber V. A first communication passage C1 is opened below the bellows chamber 64 formed in the valve case h. The passage C1 is in communication with the suction side pressure chamber 32, that is, the suction port 29. In the bellows chamber 64, a bellows 37 which expands and contracts according to the internal pressure of the suction side pressure chamber 32, and a spring 38 provided in the bellows 37 are provided.

A discharge side pressure chamber 35 into which the compressed refrigerant is introduced from a passage 35a is provided at an upper portion of the valve case h, and passes through the center hole 44, the center passage 45 and the like via the discharge side pressure chamber 35. Thus, the first flow path R1 that connects the discharge port 33 and the inside of the crank chamber 12 is formed. A valve opening 47 is provided in the middle of the first flow passage R1. The opening of the valve opening 47 is controlled by a high-pressure side control valve 39 which is operated via an operating rod 46 by expansion and contraction of a bellows 37. Is controlled.

The inside of the crank chamber 12 and the suction port 29
Is formed to communicate the pressure Pc to the suction port 29. The second flow path R2 may be formed at any position as long as the refrigerant does not flow around the bellows 37 and can guide the pressure Pc in the crank chamber 12 to the suction port 29. Here, from the viewpoint of simplifying the configuration of the variable displacement compressor, the bolt insertion hole 73 of the mounting bolt 72 extended through the crank chamber 12 is used to communicate the bolt insertion hole 73 with the suction port 29. As such, it is desirable to open an orifice passage Ro having a diameter of, for example, about 1.2 mm.

The mounting bolt 72 is for connecting the body casing 17, the cylinder 25, the cylinder head 30 and the like to each other, and is provided in a bolt insertion hole 73 provided through the cylinder 25 and the like. It is inserted with a certain gap. This gap is the crank chamber 12
It is used as a part of a second flow path R2 for guiding the internal pressure Pc to the suction port 29.

In this embodiment, the bellows chamber 64 and the crank chamber 1 are connected via an electromagnetic valve V1 and a low-pressure side valve port 40, which will be described later.
2 is provided with a second communication passage C2 communicating with the inside of the second communication passage. By the second communication passage C2 and the first communication passage C1 described above,
A third flow path R3 that passes through the bellows chamber 64 and connects the inside of the crank chamber 12 and the suction port 29 is formed.

The opening of the valve port 40 is controlled by a low pressure side control valve 36 which is operated by expansion and contraction of a bellows 37. The two control valves 36, 3 are operated by the operating rod 46.
When the low pressure side control valve 36 increases the opening of the low pressure side valve port 40, the high pressure side control valve 39 operates so as to decrease the opening degree of the high pressure side valve port 47. Has become.

As shown in FIGS. 1 and 2, an electromagnetic valve V1 is disposed between the inside of the crank chamber (12) of the third flow path R3 and the bellows chamber (64). This solenoid valve V1
Are connected to an auto amplifier 100 as control means. Further, as shown in FIG. 3, a discharge side pressure sensor 105 for detecting the discharge side pressure Pd of the compressor is attached to the high pressure side refrigerant pipe downstream of the liquid tank 102, and the detection value from the discharge side pressure sensor 105 Is input to the auto amplifier 100. In the refrigeration cycle shown in FIG. 3, the refrigerant discharged from the compressor 3 returns to the compressor 3 again through the condenser 101, the liquid tank 102, the expansion valve 103, and the evaporator 104, and is repeatedly circulated.

The auto amplifier 100 is configured to control the opening and closing of the solenoid valve V1 based on the detection value from the discharge side pressure sensor 105. Here, the discharge side pressure Pd
Is smaller than, for example, 7 kg / cm ² , the solenoid valve V1 is opened, and if it is larger than 7 kg / cm ² , the solenoid valve V1 is closed. However, in practice, in order to prevent control fluctuations, the operating pressure for opening and closing the solenoid valve V1 is set to 7 kg / cm.
^{In the} vicinity of ² , the pressure is set slightly higher when the discharge side pressure rises and slightly lower when it drops.

The operating pressure for switching the opening and closing of the solenoid valve V1 is not limited to 7 kg / cm ² but can be changed as appropriate. When the solenoid valve V1 is closed, there may be, for example, a small leak hole (for example, having a diameter of about 0.5 mm) without completely stopping the flow of the refrigerant. Further, the solenoid valve V1 can be a flow rate regulating valve that continuously changes the flow rate instead of the on / off control. In this case, the engine speed obtained from the engine speed detecting means 106 can be reduced. By adjusting the opening of the solenoid valve V1 in response, more fine-grained capacity control becomes possible.

The auto amplifier 100 is connected to the above-described magnet clutch 2a, other various actuators, sensors, and the like, and the auto amplifier 100 performs general control of the automotive air conditioner.

Next, the operation will be described.

When the heat load in the cooling cycle is small, the return refrigerant having a low suction pressure Ps enters the bellows chamber 64 from the suction port 29, the bellows 37 is extended upward by the force of the spring 38, and the control valve 39 is opened. The opening 47 is opened, and a part of the refrigerant having a high discharge pressure Pd compressed by the piston 23 is introduced into the crank chamber 12 through the first communication passage R1, thereby increasing the crank chamber pressure Pc. As a result, the piston 23 in the suction process cannot retreat so as to have a sufficiently large stroke, the compression stroke becomes small, the amount of compressed refrigerant is small, and the amount of refrigerant is appropriate for a low heat load. Due to the decrease in the refrigerant amount, the suction pressure Ps of the compressor 3 gradually increases, and as a result, is maintained at a constant suction pressure Ps.

When the heat load in the cooling cycle is large, the return refrigerant having a high suction side pressure Ps is supplied to the suction port 29.
The bellows 37 enters the bellows chamber 64 and the bellows 37
The opening of the control valve 39 is closed slightly against the force of the above. As a result, the high discharge pressure P compressed by the piston 23
The refrigerant d is not introduced into the crankcase 12.
In this case, the refrigerant in the medium pressure crank chamber 12 flows to the suction side through the second flow path R2, so that the refrigerant does not flow around the bellows 37, and the bellows 37 accurately pressurizes the refrigerant. Will work.

As a result, the drive inclined plate 13 and the like
, The reciprocating stroke of the piston 23 becomes longer. If compressed in this state, the discharged refrigerant amount will increase,
The refrigerant flow rate becomes appropriate in accordance with the high heat load, and the suction-side pressure Ps of the compressor 3 gradually decreases. As a result, a constant suction-side pressure Ps is maintained.

Here, when the outside air temperature is low and the discharge side pressure Pd detected by the discharge side pressure sensor 105 is, for example, 7 k
If it is not more than g / cm ² , the auto amplifier 100 performs control to switch the solenoid valve V1 from closed to open. As a result, the second communication passage C2 is conducted, and the third communication passage C2 which communicates with the inside of the crank chamber 12 and the suction port 29 through the bellows chamber 64 is formed.
The flow path R3 is ready to function. In this case,
A solenoid valve V2 is provided in the second flow path R2 at a location indicated by a two-dot chain line in FIG.
The solenoid valve V2 is controlled to be closed when the solenoid valve V1 is open, and to be opened when the solenoid valve V1 is closed,
It is also possible to configure so that the second flow path R2 and the third flow path R3 can selectively function.

Thus, when the refrigerant in the crank chamber 12 flows through the third flow path R3, the dynamic pressure of the refrigerant acts on the bellows 37, and the actual suction pressure Ps and the suction pressure Ps sensed by the bellows 37 ′, Ps ′> Ps
State occurs. In such a state, the bellows 37 changes the inclined state of the socket plate 16 and the drive inclined plate 13 with respect to the drive shaft 11 as in the case where the thermal load is large, and the reciprocating stroke of the piston 23 becomes long. As a result, the suction side pressure Ps of the compressor 3 decreases.

As a result, as shown in the control diagram of the control valve according to the present embodiment in FIG. 4, the linear control shown by the two-dot chain line in the figure is performed from the top of the control valve mechanism. In the embodiment, in the region of 7 kg / cm ² or less, the suction side pressure P is more than the straight line shown by the two-dot chain line in the figure.
s is lower. It should be noted that Su, Sl, Wu,
Wl indicates each performance failure area described with reference to FIG.

For this reason, at the time of low outside air temperature, necessary compressor work is secured, and an appropriate evaporation pressure is obtained.
Very good dehumidification. In addition, control interference with the expansion valve can be avoided, and hunting of the pressure or temperature of the refrigerant can be prevented, and noise associated with the hunting can be prevented. Therefore, it is possible to satisfy the product performance in all the outside air temperature load regions.

Further, since the suction side pressure Ps is reduced only when necessary at low outside air temperature, the dynamic pressure of the refrigerant is not applied to the bellows 37 in other cases as described above. The change in the suction side pressure Ps with respect to the change in the rotation of the compressor is suppressed, so that the air conditioner can properly exert its ability according to the outside air temperature, and the stability and the durability of the capacity control are improved.

FIG. 5 is a schematic block diagram for explaining an operation mechanism of a control valve according to another embodiment.

This embodiment differs from the above-described embodiment in that a mechanical valve 110 that operates based on the discharge side pressure Pd is provided as control means. However, the other points are the same as those of the above-described embodiment, and the common members are denoted by the same reference numerals, and description thereof will be omitted.

The mechanical valve 110 has a through hole 111
In order to control the operation of the valve body 111 serving as a valve having a discharge port pressure P
d, the resilient force of the spring member 112 is urged to the other end, and the crank chamber pressure Pc or the suction side pressure Ps is derived as the back pressure. C2 is opened and closed to regulate the flow to the control valve. FIG. 5 (A) shows the conduction state of the second communication path C2, and FIG. 5 (B) shows the second communication path C2.
2 shows a non-conductive state. According to this embodiment, the same effect as in the above embodiment can be obtained. The second
The flow path R2 is formed as shown by a two-dot chain line in FIG.
In the state (A), the second flow path R2 may be shut off.

The embodiments described above are not described to limit the present invention, and various modifications can be made by those skilled in the art within the technical concept of the present invention.

[0044]

As described above, according to the present invention, the opening degree of the valve is controlled based on the discharge side pressure, so that the third opening through the bellows chamber and the communication between the crank chamber and the suction port. Since the flow path can be made to function, the suction pressure of the compressor can be reduced by positively applying the dynamic pressure of the refrigerant to the bellows when necessary.

Thus, for example, at a low outside air temperature,
The necessary compressor work is ensured, an appropriate evaporation pressure is obtained, and the dehumidification is very good. In addition, control interference with the expansion valve can be avoided, and hunting of the pressure or temperature of the refrigerant can be prevented, and noise associated with the hunting can be prevented. Therefore, it is possible to satisfy the product performance in all the outside air temperature load regions.

In addition, since the control for reducing the suction side pressure can be performed only when necessary at a low outside air temperature, in other cases, the dynamic pressure of the refrigerant is not applied to the bellows and the rotation of the compressor is reduced. The suction-side pressure against the change is suppressed, and the ability of the air conditioner appropriate for the outside air temperature can be exhibited, and the stability and the durability of the capacity control are improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a variable displacement swash plate type compressor according to an embodiment of the present invention.

FIG. 2 is a schematic block diagram for explaining an operation mechanism of a control valve shown in FIG.

FIG. 3 is a configuration diagram of a refrigeration cycle showing locations where discharge-side pressure sensors shown in FIG. 2 are installed.

FIG. 4 is a control diagram of the control valve of the present embodiment.

FIG. 5 is a schematic block diagram for explaining an operation mechanism of a control valve according to another embodiment.

FIG. 6 is a view for explaining an operation mechanism of a conventional control valve.

FIG. 7 is a control diagram of a conventional control valve.

[Explanation of symbols]

 Reference numeral 12: crank chamber, 23: piston, 29: suction port, 33: discharge port, 37: bellows, 47: valve port, 64: bellows chamber, 100: auto amplifier (control means), 105: discharge side pressure sensor (pressure) Detecting means), 110: mechanical valve (control means), 111: valve body (valve), h: valve case, Pd: discharge side pressure, R1: first flow path, R2: second flow path, R3: second flow path 3 flow paths, V1 ... solenoid valve (valve).

Claims (3)

[Claims] A bellows chamber (64) formed in a valve case (h); a bellows (37) provided in the bellows chamber (64), which expands and contracts by the pressure of a refrigerant; Valve opening (4
A first flow path (R1) communicating between the discharge port (33) and the inside of the crank chamber (12) via a second port; and a second flow path communicating between the inside of the crank chamber (12) and the suction port (29). A flow path (R2), a third flow path (R3) passing through the bellows chamber (64) and communicating the inside of the crank chamber (12) with the suction port (29), and a third flow path (R3 The valve (V1) disposed between the inside of the crank chamber (12) and the bellows chamber (64), and the opening degree of the valve (V1) is controlled based on the discharge side pressure (Pd) of the compressor. Control means (100, 110) for adjusting the stroke of the piston (23) by changing the pressure (Pc) in the crank chamber (12), thereby adjusting the amount of refrigerant to be discharged. Variable capacity swash plate compressor. 2. A pressure detecting means (105) for detecting a discharge side pressure (Pd) of a compressor, wherein the control means (100) comprises:
2. The variable displacement swash plate compressor according to claim 1, wherein the compressor is controlled to open when the discharge side pressure (Pd) becomes equal to or less than a predetermined value. 3. The control means (110) is configured to control the discharge side pressure.
2. The variable displacement swash plate compressor according to claim 1, wherein the compressor is a mechanical valve that operates based on (Pd).