JPH08247027A - Double-end swash plate compressor - Google Patents

Abstract

PURPOSE: To effectively prevent the abrasion and seizure on a sliding face between a piston and a bore inner face caused by the side force applied to the piston by gas compressive force in a double-end piston type swash plate compressor. CONSTITUTION: Vertex faces 12a of a double-end piston 12 are inclined to be extended in the centrifugal direction from the inscribed circles of cylinder bores 11 arranged in parallel around a drive shaft 9. When discharge pressure is applied to the vertex faces 12a of the piston 12, the component force is applied to tilt the vertex face 12a side of the piston 12 applied with the discharge pressure outward in the radial direction. The component force can cope with the side force applied to the piston 12 from a shoe 13, thus the abrasion and seizure on a sliding face between the piston 12 and the inner face of the bore 11 can be effectively prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a double-headed swash plate type compressor used in a vehicle air conditioner or the like.

[0002]

2. Description of the Related Art In many double-headed swash plate type compressors used for air conditioning of a vehicle, the outer ends of a pair of cylinder blocks arranged in front and back are closed by front and rear housings via valve plates. A drive shaft is supported in a common central shaft hole of each cylinder block. A swash plate chamber is formed in the connecting portion of both cylinder blocks, and a swash plate fixed to the drive shaft is housed therein. In addition, a plurality of bores are arranged parallel to each other around the drive shaft in each cylinder block, and a double-headed piston moored via a hemispherical shoe is reciprocatably fitted in each swash plate in each bore. ing. As shown in FIG. 4, the shoe 95 is a flat surface 93 a of the swash plate 93.
And a hemispherical portion 95b bulging behind the flat surface 95a. The hemispherical portion 95b of the shoe 95 is engaged with the hemispherical bearing surface that is recessed in the neck portion at the center of the piston in the axial direction.

In such a compressor, when the swash plate 93 is rotated by the rotation of the drive shaft, each shoe 95 having the hemispherical portion 95b engaged with the hemispherical bearing surface of the piston is against the plane 93a of the swash plate 93. The plane 95a of the shoe 95 slides in an elliptical orbit. The sliding of the elliptical orbit is performed by relative displacement of the swash plate 93 in the circumferential direction (arrow A) and relative displacement of the swash plate 93 in the radial direction (arrow C). Also, each shoe 95
At this time, the hemisphere portion 95b and the hemisphere bearing surface of the piston oscillate in the radial direction (arrow B). Thus
The swinging motion of the swash plate 93 is converted into the reciprocating motion of each piston in the bore, whereby suction, compression and discharge of the refrigerant gas are performed.

[0004]

By the way, the shoe 95 of the compressor has a hemispherical portion 95 between the shoe 95 and the piston.
Although the displacement of the swash plate 93 in the radial direction is restricted by the engagement of b with the hemispherical support portion of the piston, the inclined swash plate 9
3, the flat surface 95a of the shoe 95 is only in contact with the flat surface 93a of the swash plate 93, so that the radial displacement is allowed.

Here, as shown in FIG. 5, when the discharge pressure acts on the crown surface 96a of the piston 96 during the discharge stroke,
An axial gas compression force F acts on the swash plate 93 from the piston 96 via the shoe 95, and the piston 96 receives an axial reaction force F ′ from the swash plate 93 via the shoe 95. At this time, since the shoe 95 is allowed to be displaced in the radial direction as described above, as a part of the reaction force received by the piston 96 from the swash plate 93 via the shoe 95, in addition to the axial force, an oblique force is generated. A radial component force f'according to the inclination angle of the plate 93, that is, a side force for inclining the crown 96a side of the piston 96, on which the discharge pressure acts, inward in the radial direction, is received. In the double-headed piston type compressor, the piston 96 receives the above-mentioned component force f'on the sliding surface with the bore inner surface 97a of the cylinder block 97. Therefore, on this sliding surface,
In particular, problems such as wear and seizure are likely to occur at high loads (at high discharge pressure) or when lubrication is poor due to gas leakage or the like.

The present invention has been made in view of the above circumstances, and in a double-headed piston type swash plate compressor, sliding between the piston and the bore inner surface caused by the side force received by the piston due to the gas compression load. The technical problem to be solved is to effectively prevent wear and seizure on the moving surface.

[0007]

SUMMARY OF THE INVENTION A double-headed swash plate compressor according to the present invention for solving the above-mentioned problems includes a cylinder block having a plurality of bores and a swash plate chamber which support a drive shaft and are arranged in parallel around the drive shaft. A housing before and after closing the front and rear ends of the cylinder block via valve plates, a swash plate housed in the swash plate chamber and cooperating with the drive shaft, and moored to the swash plate via shoes. In a double-headed swash plate compressor including a double-headed piston that reciprocates in the bore, the crown surface of the piston is inclined so as to extend from the inscribed circle of each bore toward the centrifugal direction. It is a feature.

In a preferred aspect, the valve plate is provided with an inclined surface which is aligned with the crown surface of each piston and which is aligned with the crown surface, and the inclined surface is formed by a conical tapered surface. Has been done.

[0009]

In the swash plate compressor, when the discharge pressure acts on the top surface of the piston during the discharge stroke as described above, the gas compression force F in the axial direction acts on the swash plate from the piston through the shoe, and the piston moves obliquely. The reaction force F'from the board is received via the shoe. At this time, since the shoe is allowed to be displaced in the radial direction, the side force in the radial direction according to the inclination angle of the swash plate, that is, the top surface side on which the piston discharge pressure acts is tilted inward in the radial direction. An attempt is made to exert a component force f ′ from the swash plate on the piston via the shoe. And this component force f '
Are received on the sliding surface between the piston and the inner surface of the bore.

In the compressor of the present invention, the top surface of the piston is inclined so as to extend in the centrifugal direction from the inscribed circle of each bore. Therefore, when the discharge pressure acts on the crown surface of the piston, a component force f acts to tilt the crown surface side on which the piston discharge pressure acts radially outward, and the crown on which the piston discharge pressure acts acts. It opposes the component force f ′ that tends to tilt the surface side inward in the radial direction. Thereby, the force received by the sliding surface between the piston and the inner surface of the bore can be reduced.

Further, when the valve plate is provided with an inclined surface aligned with the crown surface of each piston at a position facing the crown surface of each piston, the top clearance due to the tilted crown surface of the piston is provided. Can be prevented from increasing. When the inclined surface of this valve plate is formed by a conical taper surface, the inclined surface can be formed by cutting a thick plate-like one, so that its manufacture is easy. Become.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a swash plate type compressor embodying the present invention will be described below with reference to FIGS. The figure shows a swash plate type compressor with five cylinders on each side. Both ends of cylinder blocks 1 and 2 arranged in front and back are closed by front and rear housings 5 and 6 via front and rear valve plates 3 and 4, respectively. Is
These are connected by a plurality of bolts 7 inserted in the bolt insertion holes 1a, 2a. A swash plate chamber 8 is formed in the connecting portion of the cylinder blocks 1 and 2, and a swash plate 10 fixed to a drive shaft 9 penetrating the central shaft holes 1b and 2b of both cylinder blocks 1 and 2 is housed therein. There is. The cylinder blocks 1 and 2 have five pairs of cylinder bores 1.
1 is formed in parallel with the drive shaft 9 and at a radial position with the drive shaft 9 as the center, and a double-headed piston 12 is inserted into each cylinder bore 11 so that each piston 12 has a hemispherical shoe 13. It is moored to the swash plate 10 through.

In the compressor of this embodiment, the front and rear crown surfaces 12a, 12a of the piston 12 are inclined by a predetermined angle α so as to extend from the inscribed circle of each cylinder bore 11 toward the centrifugal direction. Further, the front and rear valve plates 3 and 4 are provided with inclined surfaces 3a and 4a which are aligned with the crown surface 12a of each piston 12 and which are aligned with the crown surface 12a. The inclined surface 3a (4a) is formed by a conical taper surface as shown in FIG. That is,
The valve plate 3 (4) is inclined as a conical taper surface by cutting a thick plate having a predetermined thickness while leaving the central flat surface 3b (4b) and the peripheral flat surface 3c (4c). The surface 3a (4a) is formed, and thereafter, a suction port 18 (19) and a discharge port 20 (21) which will be described later are provided at predetermined positions so as to penetrate therethrough.

The front and rear housings 5 and 6
The suction chambers 14 and 15 are formed on the center side of each of them, and the discharge chambers 16 and 17 are formed on the outer peripheral side thereof. Further, the front and rear valve plates 3 and 4 have suction ports 18 and 19 for sucking the low-pressure refrigerant gas G into the cylinder bores 11 from the suction chambers 14 and 15, respectively, and the discharge chambers 1 from the cylinder bores 11.
Discharge ports 20 and 21 for discharging the compressed high-pressure refrigerant gas are formed in 6 and 17, respectively. Further, the intake valves 22, 2 are provided on the cylinder blocks 1, 2 side of the valve plates 3, 4, respectively.
3, a housing 5 for the valve plates 3 and 4,
Discharge valves 24 and 25 are provided on the 6 side. The intake valve 22 (23) has a surface of the valve plate 3 (4) on the cylinder block 1 (2) side, that is, an inclined surface 3a (4a), a central flat surface 3b (4b) and a peripheral flat surface 3c (4c). ), The outer end surface of the cylinder block 1 (2) has the same shape.

This embodiment is constructed as described above,
When the swash plate 10 is rotated by the rotation of the drive shaft 9, each piston 12 is reciprocated in the cylinder bore 11, thereby sucking, compressing and discharging the refrigerant gas. In the swash plate compressor, as described above, the piston 12 is used during the discharge stroke.
When the discharge pressure acts on the top surface 12a of the piston, the piston 12
The gas compressive force F in the axial direction from the swash plate 1 via the shoe 13
0, the piston 12 receives the reaction force F ′ from the swash plate 10 via the shoe 13. At this time, since the shoe 13 is allowed to be displaced in the radial direction, the side force in the radial direction according to the inclination angle of the swash plate 10, that is, the piston 12
The component force f ′ for tilting the crown surface 12a side on which the discharge pressure is applied inward in the radial direction via the shoe 13
Acts on the piston 12. And this component force f '
Are received on the sliding surface between the piston 12 and the inner surface of the bore 11.

In the compressor of this embodiment, the top surface 12a of the piston 12 is inclined so as to extend from the inscribed circle of each bore 11 toward the centrifugal direction. Therefore, the piston 12
When the discharge pressure acts on the top surface 12a of the head, for example, the top surface 12a on the rear end side as shown in FIG. 3, a component force f for tilting the top surface 12a on the backward side in the radial direction works. , The crown surface 12a on which the discharge pressure of the piston 12 acts
It opposes the component force f'which tends to tilt the side inward in the radial direction. Thereby, the force received by the sliding surface between the piston 12 and the inner surface of the bore 11 can be reduced. Therefore, the problem of wear and seizure on the sliding surface can be effectively prevented.

Further, in the compressor of this embodiment, the valve plates 3, 4 are
In addition, since the inclined surfaces 3a and 4a which are aligned with the crown surface 12a of the piston 12 are provided at positions facing the crown surface 12a of each piston 12, the top clearance due to the tilted crown surface 12a of the piston 12 is Can be prevented from increasing. Furthermore, since the inclined surfaces 3a, 4a of the valve plates 3, 4 are formed by conical tapered surfaces, they can be easily manufactured.

The angle α for inclining the crown surface 12a of the piston 12 can be set by a mechanical calculation of the relationship of the load acting on the piston 12. That is,
Gas compression force F, inertial force of piston 12, inclination angle of swash plate,
In consideration of the shape of the piston (length of each portion of the piston, etc.) and the like, the force received by the sliding surface between the piston 12 and the inner surface of the bore 11 can be effectively reduced within a range in which the crown surface 12a can be effectively reduced. The tilting angle α can be set.

In the above embodiment, a hemispherical shoe is interposed between the swash plate 10 and the piston 12, but
The shape of the shoe is not limited to this, and for example, a shoe formed by combining a disk and a ball may be interposed.

[0020]

As described above in detail, in the compressor of the present invention, the crown surface of the double-headed piston is inclined at a predetermined angle, which is an extremely advantageous method in terms of the number of parts and manufacturing.
It is possible to effectively eliminate the problem of wear and seizure on the sliding surface between the piston and the bore caused by the side force that the piston receives.

Further, the load on the sliding surface between the piston and the bore is reduced, which contributes to energy saving.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the entire structure of a compressor according to an embodiment of the present invention.

FIG. 2 is a perspective view showing an overall shape of a valve plate of the compressor.

FIG. 3 is a partial sectional view showing a piston shape of the compressor.

FIG. 4 is an exploded perspective view of main parts of a conventional compressor.

FIG. 5 is a partial cross-sectional view showing a piston shape of a conventional compressor.

[Explanation of symbols]

1, 2 are cylinder blocks, 3 and 4 are valve plates, 3a and 4a
Is an inclined surface, 5 and 6 are housings, 9 is a drive shaft, 10 is a swash plate, 11 is a bore, 12 is a piston, 12a is a crown surface, 1
3 is a shoe.

Claims (3)

[Claims] 1. A cylinder block having a plurality of bores and swash plate chambers that support a drive shaft and are arranged in parallel around the drive shaft, and housings before and after closing front and rear ends of the cylinder block via valve plates. A double-headed swash plate compressor including a swash plate housed in the swash plate chamber and cooperating with a drive shaft, and a double-headed piston moored to the swash plate via a shoe and reciprocating in the bore. In the double-headed swash plate compressor, the top surface of the piston is inclined so as to extend from the inscribed circle of each bore toward the centrifugal direction. 2. The double-headed swash plate compressor according to claim 1, wherein the valve plate is provided with an inclined surface aligned with the crown surface of each piston at a position facing the crown surface. 3. The double-headed swash plate compressor according to claim 2, wherein the inclined surface of the valve plate is formed by a conical tapered surface.