JPH09280169A - Capacity control device for variable displacement compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To regulate the rise of inlet pressure at the time of the low discharge pressure of a compressor by simple structure, to prevent the occurrence of dewing in a compartment due to the insufficient function of an evaporator. SOLUTION: A valve unit driving means 50 is provided which is making a valve element 43 move in a direction nearing the valve element 43 to a valve seat 35 when pressure Ps is increased, in accordance with the pressure Ps in a low-pressure chamber 34; and making the valve element 43 move in a direction receding from the valve seat 35 when the pressure Ps is reduced. Also, valve seat driving means 36 and 55 are provided which is making the valve seat 35 move in a direction receding from the valve element 43 when the different pressure (Pd-Pc) is increased in accordance with the different pressure between the pressure Pd in a high-pressure chamber 32 and pressure Pc in a middle pressure chamber 33; and move the valve seat 35 in a direction nearing the valve seat 35 to the valve element 43 when the different pressure (Pd-Pc) is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a capacity control device for a capacity variable compressor used for compressing a refrigerant in a refrigeration cycle of an air conditioner for an automobile.

[0002]

2. Description of the Related Art A compressor used in a refrigeration cycle of a vehicle air conditioner cannot directly control the number of revolutions because it is directly connected to an engine by a belt. Therefore, a variable capacity compressor capable of changing the capacity (discharge amount) of the refrigerant is used in order to obtain an appropriate cooling capacity without being restricted by the engine speed.

In such a variable displacement compressor, generally, an oscillating plate provided with a variable tilt angle in an airtightly formed crank chamber is driven by the rotational motion of a rotary shaft to oscillate.

A piston that reciprocates due to the oscillating motion of the oscillating plate sucks the refrigerant in the suction chamber into the cylinder, compresses it, and then discharges it to the discharge chamber, depending on the difference between the pressure in the crank chamber and the pressure in the suction chamber. By changing the inclination angle of the oscillating plate, the discharge amount of the refrigerant is changed.

In such a variable displacement compressor, a displacement control valve is provided to change the inclination angle of the oscillating plate as needed, but when the discharge pressure is low (low outside air temperature), for example, as shown in FIG. As shown, the suction pressure (Ps) tends to increase, and it is difficult for the evaporator to remove water, so that dew tends to adhere to the window inside the vehicle.

Therefore, conventionally, when the differential pressure (Pd-Pc) between the discharge pressure (Pd) and the crank chamber pressure (Pc) falls below a predetermined pressure, it operates to correct the high-pressure influence characteristic of the main valve body. The correction valve body was provided in the main valve body (Japanese Patent Application Laid-Open No. 7-83200).
-279843).

[0007]

However, Japanese Patent Application Laid-Open No. Hei 7-2
The conventional device described in Japanese Patent No. 79843 and the like has a complicated structure such as a valve having a double structure as described above, and thus has a problem in terms of manufacturing cost and operational stability.

Therefore, the present invention has a simple structure
(EN) Provided is a capacity control device for a variable capacity compressor, which can prevent an increase in suction pressure at a low discharge pressure of a compressor and prevent dew condensation in a vehicle interior due to insufficient functioning of an evaporator. To aim.

[0009]

In order to achieve the above object, the capacity control device for a variable capacity compressor according to the present invention is provided in an airtightly formed crank chamber with a variable inclination angle with respect to a rotary shaft. An oscillating body driven by the rotational movement of the rotary shaft to oscillate, and a reciprocating movement connected to the oscillating body sucks the refrigerant in the suction chamber into the cylinder, compresses it, and then discharges it to the discharge chamber. A piston, and a pressure (Pc) in the crank chamber and a pressure (Ps) in the suction chamber.
In the displacement control device of the variable displacement compressor, wherein the inclination angle of the rocking body is changed by the pressure difference between the variable pressure compressor and the refrigerant discharge amount, a high pressure chamber communicating with the discharge chamber and a crank chamber are provided. A medium pressure chamber communicating with the low pressure chamber and a low pressure chamber communicating with the suction chamber are arranged, and a valve seat and a valve facing the valve seat from the high pressure chamber side between the high pressure chamber and the medium pressure chamber. The body is disposed, and when the pressure (Ps) in the low pressure chamber increases in response to the pressure (Ps) in the low pressure chamber, the valve body is moved toward the valve seat to move the pressure (Ps) in the low pressure chamber.
When s) becomes low, a valve body driving means for moving the valve body in a direction away from the valve seat is provided, and the differential pressure between the pressure (Pd) in the high pressure chamber and the pressure (Pc) in the intermediate pressure chamber is dealt with. Then, when the pressure difference (Pd-Pc) increases, the valve seat is moved away from the valve body, and when the pressure difference (Pd-Pc) decreases, the valve seat moves toward the valve body. It is characterized in that a valve seat driving means for moving is provided.

The valve seat is formed on the movable member, and the flexible thin film sheet is movable so that the high pressure chamber and the medium pressure chamber are not communicated with each other via the outer peripheral portion of the movable member. The members may be arranged in close contact with each other from the end surface of the member facing the high pressure chamber to the outer portion thereof.

[0011]

Embodiments of the present invention will be described with reference to the drawings. FIG. 4 shows a variable capacity compressor 10 used in a refrigeration cycle of an automobile air conditioner and a capacity control valve 30 thereof.

Reference numeral 11 denotes an airtight crank chamber 12
An oscillating plate 14 disposed inside the crank chamber 12 that is inclined with respect to the rotating shaft 11 and is rotatably driven by the drive pulley 13 oscillates as the rotating shaft 11 rotates. To do.

A piston 17 is reciprocally movable in a cylinder 15 arranged in the peripheral portion of the crank chamber 12, and the piston 17 and the oscillating plate 1 are connected by a rod 18.
4 are connected.

Therefore, when the rocking plate 14 rocks, the piston 17 reciprocates in the cylinder 15 and the cylinder 1
5, the refrigerant is sucked into the cylinder 15 from the suction chamber 20 formed on the upstream side, compressed in the cylinder 15, and then discharged to the discharge chamber 21 on the downstream side.

Reference numeral 30 denotes a displacement control valve 30 for controlling the discharge amount (capacity) of the refrigerant discharged from the cylinder 15 into the discharge chamber 21, and FIG. 1 shows an enlarged cross section of that portion. .

Within the body 31 of the capacity control valve 30, there are a high pressure chamber 32 communicating with the discharge chamber 21, a medium pressure chamber 33 communicating with the crank chamber 12, and a low pressure chamber 34 communicating with the suction chamber 20 in that order. It is formed separately.

A valve seat 35 formed by a taper surface facing the high pressure chamber 32 is formed between the high pressure chamber 32 and the intermediate pressure chamber 33 in a tubular member 36 arranged in the main body 31. Has been done.

The tubular member 36 includes a high pressure chamber 32 and an intermediate pressure chamber 33.
It is loosely fitted in the hole that communicates with and is movable in the axial direction. However, the body 31 has a tubular member 36.
Is formed with a stepped portion 37 for restricting its movement in the axial direction.

As shown in FIG. 1, on the high pressure chamber 32 side, when the end face of the tubular member 36 is flush with the inner end face 38 formed in the body 31 around it, the intermediate pressure chamber 3
On the third side, a slight clearance is set between the end surface of the tubular member 36 and the step portion 37.

The tubular member 36 is biased by the first compression coil spring 39 from the medium pressure chamber 33 side toward the high pressure chamber 32 side, and the pressure Pd in the high pressure chamber 32 and the pressure in the medium pressure chamber 33 are increased. It stands still at a position balanced with the pressure difference (Pd-Pc) from Pc. The effective pressure receiving area of the tubular member 36 at that time is the area of the portion surrounded by the outer diameter of the tubular member 36.

A flexible sealing sheet 41 made of, for example, a polyimide resin thin sheet is closely arranged from the end surface of the tubular member 36 on the high pressure chamber 32 side to the inner end surface 38 of the main body 31 on the outer side thereof. ing.

As a result, the high pressure chamber 32 and the intermediate pressure chamber 33 are prevented from communicating with each other via the outer peripheral portion of the tubular member 36. Therefore, the refrigerant does not leak from the high pressure chamber 32 to the intermediate pressure chamber 33 through the portion other than the gap between the valve body 43 and the valve seat 35. Reference numeral 42 is a stopper for pressing the sealing sheet 41 to hold it at a predetermined position and for restricting the movement of the tubular member 36 toward the high-pressure chamber 32 within a certain range.

In the case of a specification in which even a slight amount of refrigerant leak from the high pressure chamber 32 to the medium pressure chamber 33 is allowed, the fitting gap of the outer peripheral surface of the tubular member 36 is made as small as possible. The sealing sheet 41 may be omitted.

Reference numeral 43 denotes a spherical valve body which is arranged to face the valve seat 35 from the high pressure chamber 32 side, and the tip of a rod 44 which penetrates the inside of the medium pressure chamber 33 and the inside of the low pressure chamber 34. Is in contact with. The valve body 43 may be welded to the tip of the rod 44.

The rod 44 passes through the inside of the tubular member 36 with a sufficient gap. Therefore, when there is a gap between the valve body 43 and the valve seat 35, the refrigerant flows from the high pressure chamber 32 to the intermediate pressure chamber 33 side in accordance with the size of the gap, and the valve body 43 moves to the valve seat 35. When they come into close contact with each other, the space between the high pressure chamber 32 and the medium pressure chamber 33 is shielded.

The rod 44 is axially slidably fitted in the hole 45 formed in the main body 31 between the intermediate pressure chamber 33 and the low pressure chamber 34. However, in order to minimize the leakage of the refrigerant between the medium pressure chamber 33 and the low pressure chamber 34, the gap between the outer peripheral surface of the rod 44 and the hole 45 is made as narrow as possible.

Reference numeral 50 is a vacuum chamber whose inside is in a substantially vacuum state, and the suction hole is closed by a tight plug 51. 5
Reference numeral 2 denotes a diaphragm made of a flexible thin film, which airtightly partitions the vacuum chamber 50 and the low pressure chamber 34.

The diaphragm 52 is sandwiched by a pair of receiving plates 53, 54 made of metal from both sides, and the receiving plate 53 arranged inside the vacuum chamber 50 is the vacuum chamber 50.
It receives one end of a second compression coil spring 55 arranged therein.

The base end of the rod 44 is in contact with the receiving plate 54 located on the low pressure chamber 34 side. Therefore, the valve element 43, which abuts on the tip of the rod 44, stands still at a position where the pressure Ps in the low pressure chamber 34 and the urging force of the second compression coil spring 55 are balanced.

In the displacement control device for a variable displacement compressor according to the embodiment configured as described above, the valve element 43 moves due to a change in the pressure in the low pressure chamber 34, that is, a change in the pressure Ps in the suction chamber 20.

Specifically, when the load of the evaporator increases and Ps increases, the valve element 43 approaches the valve seat 35 and Ps increases.
Since c decreases and (Pc-Ps) decreases, the swing plate 1
The inclination angle of 4 increases, the stroke of the piston 17 increases, and the discharge amount (capacity) of the variable displacement compressor 10 increases.

On the contrary, when the load of the evaporator is reduced and Ps is reduced, the valve body 43 moves away from the valve seat 35 and Pc is reduced.
Is increased and (Pc-Ps) is increased, the swing plate 14
Of the variable displacement compressor 10 becomes smaller and the stroke of the piston 17 becomes smaller.

In this way, the variable capacity compressor 1 is changed by changing the pressure Ps of the suction chamber 20 according to the load of the evaporator.
The capacity of 0 changes automatically, but the tubular member 36 moves due to the change of the differential pressure (Pd-Pc) between the pressure Pd in the high pressure chamber 32 and the pressure Pc in the intermediate pressure chamber 33.
The position of the valve seat 35 with respect to the valve body 43 changes.

That is, when the pressure Pd in the high-pressure chamber 32 becomes larger than that in the state of FIG. 1, the tubular member 36 moves away from the valve body 43 (until the maximum step 37 is reached), and the valve body 43 and the valve seat 35 are separated from each other. The gap between them widens.

In this state, the valve gradually becomes easier to open,
As shown in FIG. 2, in the state where the tubular member 36 collides with the stepped portion 37, the pressure in the low pressure chamber 34 (that is, the pressure in the suction chamber 20) Ps is less than that in the state shown in FIG. The valve (the gap between the valve body 43 and the valve seat 35) opens even if the valve is not lowered. This state is the point in FIG.

On the contrary, when Pd becomes small, as shown in FIG. 3, the tubular member 36 approaches the valve body 43 (until the movement is restricted by the stopper 42 to the maximum), and the valve body 43 is closed.
The gap between the valve seat 35 and the valve seat 35 is narrowed.

In this state, the valve gradually becomes difficult to open, and in order to open the valve (the gap between the valve body 43 and the valve seat 35), the pressure in the low pressure chamber 34 (that is, the pressure in the suction chamber 20). P
s needs to be lower.

As a result, as shown in FIG. 5, it is possible to regulate the rise of the suction pressure Ps when the discharge pressure Pd is low (the region where Pd is lower). The broken line portion of FIG. 5 shows the conventional characteristic shown in FIG.

[0039]

According to the present invention, the valve body is driven by the pressure (Ps) in the suction chamber, and the valve seat has a pressure difference (Pd) between the pressure (Pd) in the discharge chamber and the pressure (Pc) in the crank chamber. P
d-Pc), the differential pressure (Pd-Pc)
As the valve pressure decreases, the valve seat moves toward the valve body, making it difficult for the valve to open. In order to open the valve, the suction chamber (Ps) needs to be lower and the discharge pressure (Ps) decreases.
It is possible to regulate the rise of the suction pressure (Ps) when d) is low.

As a result, it is possible to prevent the occurrence of dew condensation in the vehicle compartment due to the insufficient functioning of the evaporator, and it is possible to achieve it with a very simple structure.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a capacity control device according to an embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view showing a state in which the discharge pressure of the capacity control device according to the embodiment of the present invention is increased.

FIG. 3 is a vertical cross-sectional view showing a state in which the discharge pressure of the capacity control device according to the embodiment of the present invention is lowered.

FIG. 4 is a schematic diagram of an overall configuration of a variable capacity compressor according to an embodiment of the present invention.

FIG. 5 is a characteristic diagram of the embodiment of the present invention.

FIG. 6 is a characteristic diagram of a conventional example.

[Explanation of symbols]

 10 Variable capacity compressor 12 Crank chamber 14 Oscillating plate 20 Suction chamber 21 Discharge chamber 30 Capacity control valve 32 High pressure chamber 33 Medium pressure chamber 34 Low pressure chamber 35 Valve seat 36 Cylindrical member 39 Compression coil spring 43 Valve body 44 Rod 55 Compression coil spring

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location F16K 31/385 F04B 27/08 S

Claims (2)

[Claims] 1. An oscillating body, which is provided in an airtightly formed crank chamber with a variable inclination angle with respect to a rotating shaft and is oscillated by being driven by the rotational movement of the rotating shaft, and is connected to the oscillating body. And a piston that compresses the refrigerant in the suction chamber into the cylinder by reciprocating the compressed air and then discharges the compressed refrigerant to the discharge chamber. The pressure in the crank chamber (Pc) and the pressure in the suction chamber (Ps) In a displacement control device of a variable displacement compressor, wherein the inclination angle of the oscillator is changed by a pressure difference to change the discharge amount of the refrigerant, a high pressure chamber communicating with the discharge chamber and a crank chamber communicating with the crank chamber. A medium pressure chamber and a low pressure chamber communicating with the suction chamber are arranged, and a valve seat and a valve body facing the valve seat from the high pressure chamber side between the high pressure chamber and the medium pressure chamber. The pressure in the low pressure chamber (Ps) Correspondingly, the pressure (P
s) is increased, the valve body is moved in a direction to approach the valve seat, and when the pressure (Ps) in the low pressure chamber is decreased, the valve body drive means is provided to move the valve body in a direction to move away from the valve seat. , The pressure in the high pressure chamber (Pd) and the pressure in the medium pressure chamber (Pd)
When the differential pressure (Pd-Pc) increases corresponding to the differential pressure with c), the valve seat is moved away from the valve body, and when the differential pressure (Pd-Pc) decreases, the valve seat moves. A displacement control device for a variable displacement compressor, comprising valve seat driving means for moving the valve seat in a direction to approach the valve body. 2. The valve seat is formed on a movable member, and the flexible thin film sheet is movable so that the high pressure chamber and the intermediate pressure chamber do not communicate with each other via the outer peripheral portion of the movable member. 2. The displacement control device for a variable displacement compressor according to claim 1, wherein the displacement control device is closely arranged from an end face of the member facing the high pressure chamber to an outer portion thereof.