JP2001329952A - Oblique plate type variable displacement compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oblique plate type variable displacement compressor capable of improving volume efficiency and discharge capability. SOLUTION: This oblique plate type variable displacement compressor compresses and discharges a sucked coolant by reciprocating pistons 6 in plural cylinder bores 10 in conjunction with the rotation of an oblique plate 5 installed in an oblique plate chamber 26, and can vary its discharge capacity by varying the tilt angle of the oblique plate 5 by adjusting the pressure of the coolant in the oblique plate chamber 26. Plural suction passages 36 allowing the oblique plate chamber 26 to communicate with the respective cylinder bores 10 are formed so that plural opening parts 360 opening from the respective suction passages 36 to the side walls 100 of the respective cylinder bores 10 are opened when the tilt angle of the oblique plate 5 is maximum and the respective pistons 6 are positioned at their dead center.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a swash plate type variable displacement compressor suitable for use in, for example, a vehicle air conditioner, and to an improvement in performance thereof.

[0002]

2. Description of the Related Art Conventional swash plate type variable displacement compressors include:
By converting the rotational motion of the swash plate into a reciprocating motion of the piston, the refrigerant is sucked and compressed, and the inclination angle of the swash plate is changed to change the stroke amount of the piston, thereby changing the discharge capacity. Are known.

[0003] Specifically, a swash plate connected to a rotor via a hinge mechanism is fitted into a guide hole so as to be variable in inclination angle by inserting a shaft into the guide hole, and is housed in a swash plate chamber. Due to the rotation of the swash plate, the plurality of pistons reciprocate in the cylinder bore, compressing and discharging the sucked refrigerant. Then, a part of the discharged refrigerant is supplied to or discharged from the swash plate chamber by the pressure control valve, and by adjusting the back pressure applied to each piston, the inclination angle of the swash plate is changed, and the stroke of each piston is changed. The amount is changed to control the discharge capacity.

[0004]

However, in recent years,
Although the need for improving the discharge capacity of the compressor for improving the cooling capacity has become extremely high, one of the bottleneck items is a decrease in volumetric efficiency due to blow-by of the refrigerant during compression.

That is, a clearance is provided between the pistons so that they can reciprocate slidably in the cylinder bores. During the compression stroke, the refrigerant leaks from the clearances to the swash plate chamber side, so that the refrigerant is sucked. As the refrigerant volume decreases, the volume efficiency decreases, and consequently the discharge capacity decreases.

An object of the present invention is to provide a swash plate type variable displacement compressor capable of improving volumetric efficiency and improving discharge capacity in view of the above problems.

[0007]

The present invention employs the following technical means to achieve the above object.

According to the first aspect of the present invention, the swash plate chamber (26), the suction chamber (23),
A discharge chamber (22) and a multiple number of cylinder bores (10) connected thereto are defined and rotated together with a shaft (4) which rotates by receiving an external driving force, and the swash plate (the inclination angle of which changes). 5) is provided in the swash plate chamber (26),
The plurality of pistons (6) reciprocate in the plurality of cylinder bores (10) with the rotation of the swash plate (5), thereby compressing the fluid sucked from the suction chamber (23) to the discharge chamber (22). Discharge, supply a part of the fluid in the discharge chamber (22) to the swash plate chamber (26), or discharge a part of the fluid in the swash plate chamber (26), and swash plate according to the fluid pressure in the swash plate chamber (26). In the swash plate type variable displacement compressor having the pressure control means (37) for changing the inclination angle in (5), the swash plate chamber (26)
And a plurality of suction passages (36) communicating with the cylinder bores (10), and a plurality of openings (360) opening from the suction passages (36) to the side walls (100) of the cylinder bores (10) are inclined. The plate (5) is characterized in that the inclination angle of the plate (5) is maximum and each piston (6) is opened at the bottom dead center position.

Thus, when each piston (6) is not at the bottom dead center position, the communication between the swash plate chamber (26) and each cylinder bore (10) can be interrupted, so that the operation of the compressor is not affected. In addition, when each piston (6) is at the bottom dead center position at the end of the suction stroke, fluid flows into the swash plate chamber (2).
Since the pressure flows from 6) into each cylinder bore (10) due to the pressure difference between them, the volume efficiency when the discharge capacity is maximum can be improved, and the maximum discharge capacity of the compressor itself can be improved.

The reference numerals in parentheses of the above means indicate the correspondence with specific means described in the embodiment described later.

[0011]

FIG. 1 shows a swash plate type variable displacement compressor according to an embodiment of the present invention. The compressor has a plurality of cylinder bores 10 at the rear end of the front housing 1.
And a rear housing 3 is further joined to the rear end side thereof via a valve plate 8, and these are fixed to each other by through bolts 9.

A swash plate chamber 26 formed by the front housing 1 and the middle housing 2 accommodates the shaft 4 extending in the axial direction and is sealed by a shaft seal 19. The shaft 4 is a needle bearing. 11 and 12 rotatably supported.
A plurality of cylinder bores 10 are formed in the middle housing 2 at positions surrounding the shaft 4, and the pistons 6 are fitted into the respective cylinder bores 10.

In the swash plate chamber 26, a rotor 34 is provided on the shaft 4 and is rotatably supported between the shaft 4 and the front housing 1 through a thrust bearing 13.
A swash plate 5 having a shaft 4 penetrated in a guide hole 35 is provided behind the rotor 34. The guide hole 35 is shaped so that the swash plate 5 can be tilted from a position nearly perpendicular to the shaft 4 to a maximum tilt position as shown in FIG.

Thrust bearings 13, 14 and a spring 140 are provided to support the axial load of the shaft 4, and a spring 18 is provided between the rotor 34 and the swash plate 5 so that the swash plate 5 has a play. Has been prevented.
Further, a plurality of shoes 7 having a spherical shape as a connection mechanism are in contact with the outer peripheral portion of the swash plate 5.
Is engaged with the ball bearing surface of each piston 6. Thus, each piston 6 engaged with the swash plate 5 via each shoe 7 is housed in each cylinder bore 10 so as to be able to reciprocate.

On the front surface of the swash plate 5, a pair of brackets 50 constituting a hinge mechanism K is provided so as to protrude with the shaft 4 interposed therebetween. One end of a guide pin 51 is fixed to the bracket 50, and A ball portion 52 is fixed to the end. Further, a pair of support arms 3 is provided above the rotor 34.
40 projects toward the rear of the shaft 4 so as to face the guide pin 51. An arm hole 341 penetrates the distal end of the support arm 340, and the ball 52 of the guide pin 51 is inserted so as to rotate and slide. When the guide pin 51 rotates and slides in the arm hole 341, the inclination angle of the swash plate 5 changes.

The interior of the rear housing 3 is divided into a suction chamber 23 and a discharge chamber 22. The valve plate 8 has a suction hole 25 and a discharge hole 24 corresponding to each cylinder bore 10.
Are formed, and a compression chamber formed between the valve plate 8 and each piston 6 is provided with a suction hole 25 and a discharge hole 2.
4 communicates with the suction chamber 23 and the discharge chamber 22. Each suction hole 25 is provided with a suction valve 15 that opens and closes the suction hole 25 according to the reciprocating motion of each piston 6, and each discharge hole 24 is provided with a discharge hole 2 according to the reciprocating motion of each piston 6.
A discharge valve 16 that opens and closes while restricting the valve 4 by a valve stop plate 17 is provided.

Further, a suction port 21 is provided in the rear housing 3.
And the suction chamber 23 is connected to the evaporator of the external refrigeration cycle. Similarly, a discharge port 20 is provided in the rear housing 3, and the discharge chamber 22 is connected to a condenser of an external refrigeration cycle. In addition, a pressure control valve 37 (shown in a schematic diagram) as pressure control means is installed in the rear housing 3 to adjust the pressure of the swash plate chamber 26. This opens and closes channels 370, 371, 372,
The pressure in the swash plate chamber 26 is adjusted by supplying a part of the refrigerant to the swash plate chamber 26 or discharging a part of the refrigerant from the swash plate chamber 26.

The middle housing 2 is provided with a suction passage 36, which is a main part of the present invention, corresponding to each cylinder bore 10. Each suction passage 36 is a passage communicating the swash plate chamber 26 and each cylinder bore 10, and has an opening 360 in the side wall 100 of each cylinder bore 10, and the swash plate 5 has an inclination angle corresponding to the maximum suction and discharge capacity. Is maximum, and each piston 6 is opened at the bottom dead center position, and the swash plate chamber 26 is opened.
And communicate with them. The suction passage 36 allows the refrigerant to be sucked from the swash plate chamber 26 into each of the cylinder bores 10 to improve the volumetric efficiency and thus the discharge capacity.
To increase the maximum discharge capacity of the compressor itself, a swash plate 5
Is located at the maximum inclination angle position, and the opening 360 is set at the above position in order to prevent the refrigerant from flowing back to the swash plate chamber 26 during the compression process of each piston 10.

Next, the operation of the embodiment of the present invention will be described. When the swash plate 5 rotates via the rotor 34 and the hinge mechanism K with the driving of the shaft 4, each piston 6 reciprocates in each cylinder bore 10 via each shoe 7, thereby moving from the suction chamber 23 to the compression chamber. The refrigerant is sucked in, and is discharged into the discharge chamber 22 after being compressed. Then, a part of the refrigerant on the discharge side is supplied to the swash plate chamber 26 or a part of the refrigerant is discharged from the swash plate chamber 26 by the pressure control valve 37 provided in the rear housing 3 so that the pressure in the swash plate chamber 26 is reduced. Is adjusted, and the swash plate 5 is adjusted by the pressure balance between the swash plate chamber 26 and the cylinder bore 10 of each piston 6.
Is determined, and the discharge capacity is controlled.

Specifically, the pressure control valve 37 is connected to the flow path 370
371 communicates with the discharge chamber 22.
Of the refrigerant from the swash plate chamber 26 is supplied to the swash plate chamber 26.
The pressure inside rises. Since the back pressure acting on each piston 6 is increased, the inclination angle of the swash plate 5 is reduced, the stroke of each piston 6 is reduced, and the discharge capacity is reduced. Conversely, when the pressure control valve 37 operates so as to connect the flow paths 371 and 372, a part of the refrigerant from the swash plate chamber 26 is discharged to the suction chamber 23, and the pressure in the swash plate chamber 26 decreases. Then, since the back pressure acting on each piston 6 decreases, the inclination angle of the swash plate 5 increases, the stroke of each piston 6 increases, and the discharge capacity increases.

As described above, the pressure control valve 37 is provided in the swash plate chamber 26.
Therefore, a certain pressure is always applied. Here, if the pressure in the swash plate chamber 26 is Pc, the pressure in the suction chamber 23 is Ps, and the pressure in the discharge chamber 22 is Pd, Pc is P
d and has an intermediate pressure between Ps and Pd, and these pressures have a relationship of Ps <Pc <Pd. That is, Pc is always higher than Ps.

On the other hand, when the inclination angle of the swash plate 5 is maximum and each piston 6 reaches the bottom dead center position where the suction stroke has been completed, the opening 360 is opened, and the swash plate chamber 26 and each cylinder bore 10 are opened by the suction passage 36. And the pressure difference (Pc
From the swash plate chamber 26 to each cylinder bore 10
The refrigerant flows into the inside.

As a result, the suction volume in each cylinder bore 10 can be increased and the volume efficiency can be improved. And swash plate 5
Since the opening 360 is provided in accordance with the position of the bottom dead center of the piston 10 when the inclination angle is the maximum, the maximum discharge capacity of the compressor itself can be improved. When each piston 6 is not at the bottom dead center position, communication between the swash plate chamber 26 and each cylinder bore 10 can be interrupted, so that the operation of the compressor is not affected. In addition, when the refrigerant flows from the swash plate chamber 26 into each of the cylinder bores 10, a change in the pressure in the swash plate chamber 26 may be considered. Therefore, the operation at the time of the maximum discharge capacity is not affected.

The position of the opening 360 in this embodiment only needs to be near the bottom dead center position when the inclination angle of the swash plate 5 is at the maximum, and the adverse effect of the opening 360 in other operation steps of the compressor. It is permissible if the position does not occur or the shape of the opening.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing the overall configuration of an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Front housing 2 Middle housing 3 Rear housing 4 Shaft 5 Swash plate 6 Piston 10 Cylinder bore 100 Side wall 22 Discharge chamber 23 Suction chamber 26 Swash plate chamber 36 Suction passage 360 Opening 37 Pressure control valve (pressure control means)

Claims (1)

[Claims] A housing (1, 2, 3) in which a swash plate chamber (26), a suction chamber (23), a discharge chamber (22) and a number of cylinder bores (10) connected thereto are formed.
A shaft (4) that rotates by receiving an external driving force; a swash plate (5) provided in the swash plate chamber (26), the swash plate (5) rotating with the shaft (4), the inclination angle of which can be changed; A plurality of pistons reciprocate in the plurality of cylinder bores (10) with the rotation of the swash plate (5), compress the fluid sucked from the suction chamber (23), and discharge the fluid to the discharge chamber (22). 6), and a part of the fluid in the discharge chamber (22) is transferred to the swash plate chamber (26).
Or a pressure control means (37) for discharging a part of the fluid in the swash plate chamber (26) and changing the inclination angle of the swash plate (5) in accordance with the fluid pressure in the swash plate chamber (26). A plurality of suction passages (36) that communicate the swash plate chamber (26) with the cylinder bores (10), and the cylinder passages (36) are provided from the suction passages (36). 10) Side wall (1)
00), the inclination angle of the swash plate (5) is maximum, and each of the pistons (6)
Swash plate type variable displacement compressor characterized in that it is opened at the bottom dead center position.