JPH1089246A - Compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compressor to regulate rotation around the axis of a piston through simple constitution and simplify machining of the piston and reduce the weight thereof. SOLUTION: In a compressor formed such that through rotation of a drive shaft, a piston 21 is reciprocated through a cam plate 19, a curve part 33 or a chamfered part is formed on the outer periphery of the cam plate 19. Contact parts 34 are formed in a protrusion state on the two side edges of the inner surface of the neck part 21c of the piston 21. When a rotation moment around an axis is exerted on the piston 21, the curve part 33 or the chamfered part of the cam plate 19 and the contact part 34 of the piston 21 are arranged in a touchable state. The curve part 33 or the chamfered part of the cam plate 19 and the contact part 34 of the piston 21 are brought into contact with each other to regulate rotation of the piston 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compressor used for, for example, a vehicle air conditioner.

[0002]

2. Description of the Related Art As a compressor of this type, the following configuration is known. That is, a crank chamber is formed inside the housing, and the drive shaft is rotatably supported. A plurality of cylinder bores are formed in a cylinder block constituting a part of the housing, and a piston is accommodated in each cylinder bore so as to be able to reciprocate. In the crank chamber, a cam plate is mounted on the drive shaft so as to be integrally rotatable, and the cam plate is moored to each piston at the periphery of the cam plate. Then, the rotational motion of the drive shaft is converted into the reciprocating motion of the piston via the cam plate, and the compression operation is performed.

[0003] During the compression operation of such a compressor, the piston is reciprocated in the axial direction with the rotation of the cam plate by the drive shaft, and at the same time, a rotational moment about the axis is applied. That is, the piston may be rotated around the axis while being reciprocated in the cylinder bore.

In order to restrict the rotation of the piston about the axis, a compressor as disclosed in Japanese Utility Model Laid-Open No. 63-93480 has been proposed. In this conventional configuration, a rotation preventing projection is formed on the outer periphery of the neck of the piston, and an engagement surface is formed on the inner peripheral surface of the cylinder block corresponding to the crank chamber. The rotation prevention projection is slidably engaged with the engagement surface, whereby the rotation of the piston in the cylinder bore is restricted.

[0005]

However, in this conventional compressor, since a large anti-rotation projection is formed on the outer periphery of the neck portion of the piston, processing of the anti-rotation projection is troublesome, and the production cost is high. There was a problem of inviting the rise. In addition, there is a problem that the entire piston becomes heavy, causing an increase in the weight of the entire compressor.

The present invention has been made by paying attention to such problems existing in the conventional technology. It is an object of the present invention to provide a compressor capable of restricting rotation of a piston about an axis thereof with a simple configuration and simplifying and reducing the weight of the piston.

[0007]

In order to achieve the above object, according to the first aspect of the present invention, a crank chamber is formed inside a housing, a drive shaft is rotatably supported, and a part of the housing is formed. A cylinder bore is formed in a cylinder block that constitutes, a piston is reciprocally housed in the cylinder bore, a cam plate is supported on the drive shaft so as to be integrally rotatable in the crank chamber, and the cam plate is rotated by the rotation of the drive shaft. In a compressor that reciprocates a piston through, a curved surface portion or a chamfered portion is formed on the outer periphery of the cam plate,
The curved surface portion or the chamfered portion is arranged so as to be able to contact the inner surface of the neck portion of the piston.

According to a second aspect of the present invention, in the compressor according to the first aspect, an abutting portion which abuts on a curved surface portion or a chamfered portion of the cam plate is provided on the inner surface of the neck portion of the piston toward the cam plate. It is formed to protrude.

According to a third aspect of the present invention, in the compressor according to the first or second aspect, the contact portions are provided near both side edges of the inner surface of the neck. According to a fourth aspect of the present invention, in the compressor according to any one of the first to third aspects, the inner surface of the neck of the piston substantially corresponds to the outer periphery of the cam plate along the circumferential direction of the cam plate. It is formed in.

[0010] According to the fifth aspect of the present invention, the first to fourth aspects are provided.
In the compressor according to any one of the above, a guide portion engageable with an outer peripheral surface of the piston is formed on an inner peripheral surface of the housing corresponding to the crank chamber.

According to a sixth aspect of the present invention, in the compressor according to the fifth aspect, the cylinder block is extended to the crank chamber side, and the guide portion is provided with a cylinder bore on an inner peripheral surface of the extension portion of the cylinder block. It is formed so as to be continuous.

[0012] In the invention described in claim 7, claims 1 to 6 are provided.
In the compressor according to any one of the above, the cam plate is swingably supported on a drive shaft, and a pressure in a crank chamber and a pressure in a cylinder bore are transmitted through the piston based on adjustment of an opening of a capacity control valve. The differential pressure is changed, and the inclination of the cam plate is changed according to the differential pressure to control the discharge capacity.

In the compressor according to the first aspect, when the drive shaft is rotated by an external drive source such as a vehicle engine, the cam plate is rotated. Along with the rotation of the cam plate, the piston is reciprocated in the axial direction, and at the same time, a rotational moment about the axis is applied to the piston. When the piston starts to rotate due to this rotational moment, the curved surface or the chamfer formed on the outer periphery of the cam plate comes into contact with the inner surface of the neck of the piston. For this reason, rotation around the axis is reliably restricted without further rotation of the piston.

Here, since the curved surface portion or the chamfered portion is formed on the outer circumference of the cam plate, the inner surface of the neck portion of the piston and the outer circumference of the cam plate are prevented from coming into contact with each other. For this reason, the contact surface pressure between the contact surfaces does not greatly increase, and the possibility that damage occurs between the contact surfaces is reduced. In addition, since the curved surface portion and the chamfered portion effectively contribute to drawing in the lubricating oil scattered in the compressor, it is possible to further reduce the possibility of causing damage between the contact surfaces.

In the compressor according to the second aspect of the present invention, on the inner surface of the neck portion of the piston, a contact portion with the curved surface portion or the chamfered portion of the cam plate is formed to protrude toward the cam plate. That is, the thickness of the neck portion of the piston is increased at a portion corresponding to the contact portion with the cam plate. For this reason, the portion corresponding to the contact portion is reinforced, and the risk of damage to the neck of the piston due to contact with the outer periphery of the cam plate is reduced.

According to the third aspect of the present invention, the inner surface of the neck of the piston and the outer periphery of the cam plate come into contact with each other near the both side edges of the inner surface of the neck. For this reason,
Due to the contact with the outer periphery of the cam plate, the vicinity of the center where the strength is most required in the neck portion of the piston is hardly damaged, and the breakage of the neck portion is suppressed.

In the compressor according to the fourth aspect, in the circumferential direction of the cam plate, the inner surface of the neck of the piston is formed in a shape substantially corresponding to the outer periphery of the cam plate. For this reason, it is suppressed that the outer periphery of the cam plate and the inner surface of the neck portion of the piston come into strong contact locally. Then, the contact surface pressure between the contact surfaces does not greatly increase, and the risk of occurrence of damage between the contact surfaces is further reduced in combination with the invention described in the first aspect.

In the compressor according to the fifth aspect, a guide portion which can be engaged with the outer peripheral surface of the piston is formed on the inner peripheral surface corresponding to the crank chamber of the housing. For this reason, the piston is smoothly reciprocated while correcting the operation in the twisting direction along the guide portion.

In the compressor according to the present invention, the cylinder block is extended toward the crank chamber, and the guide portion is formed on the inner peripheral surface of the extension of the cylinder block so as to be continuous with the cylinder bore. For this reason, there is no seam in the middle of the guide portion, and the reciprocating motion of the piston is further smoothed.

In the compressor according to the present invention, the pressure difference between the pressure in the crank chamber and the pressure in the cylinder bore via the piston is changed based on the adjustment of the opening of the displacement control valve. Thus, the inclination of the cam plate is changed to control the discharge capacity. A curved surface or a chamfered portion is formed on the outer periphery of the cam plate, and the curved surface or the chamfered portion is configured to be able to abut the inner surface of the neck of the piston. Therefore, especially when the curved portion is formed on the outer periphery of the cam plate, the contact surface pressure between the contact surfaces does not greatly increase regardless of the inclination angle of the cam plate. In addition, even when the cam plate is tilted in a state where the outer periphery of the cam plate is in contact with the inner surface of the neck of the piston, smooth tilting of the cam plate is ensured.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) A first embodiment in which the present invention is embodied in a single-head piston type variable displacement compressor will be described below in detail with reference to FIGS.

As shown in FIG. 1, a front housing 11 forming a part of the housing is joined and fixed to a front part of a cylinder block 12 also forming a part of the housing. A rear housing 13, which also forms a part of the housing, is fixedly connected to a rear portion of the cylinder block 12 via a valve plate 14.

In the rear housing 13, the suction chamber 1 is provided.
3a and the discharge chamber 13b are defined. The valve plate 14 is provided with a suction valve 14a and a discharge valve 14b. The closed space formed by the front housing 11 and the cylinder block 12 is a crank chamber 1
5 is made. The front housing 11 and the cylinder block 12 extend through the crank chamber 15.
The drive shaft 16 has a pair of radial bearings 1.
7, and is rotatably supported by a bridge.

The rotary support 18 is provided with the drive shaft 16.
It is fixed to. Also, a swash plate 1 as a cam plate
9 is supported by a drive shaft 16 in a crank chamber 15 so as to be slidable and tiltable in the axial direction. The swash plate 19 is connected to the rotating support 18 via a hinge mechanism 20. The swash plate 19 is guided by its hinge mechanism 20 in sliding movement and tilting in the axial direction, and is rotated integrally with the drive shaft 16.

The maximum inclination angle of the swash plate 19 is determined by the stopper 19a provided on the swash plate 19 and the rotation support member 18.
Stipulated by the abutment. The minimum inclination angle of the swash plate 19 is determined by the circlip 16 attached to the drive shaft 16.
b and the swash plate 19 are in contact with each other.

A plurality of cylinder bores 12a are formed in the cylinder block 12. Single-headed piston 2
1 is a cylinder bore 12 in the head portion 21a.
The tail part 21b is moored on the outer periphery of the swash plate 19 via a pair of shoes 22.
The compression reaction force accompanying the compression operation of the piston 21 is applied to the shoe 22, the swash plate 19, the hinge mechanism 20, and the rotation support member 18.
And received by the front housing 11 via a thrust bearing 23.

The supply passage 24 is formed to connect the discharge chamber 13b and the crank chamber 15. The capacity control valve 25 is disposed in the air supply passage 24. The displacement control valve 25 includes a control valve element 26 and the control valve element 26.
And a diaphragm 28 for adjusting the opening of the control valve hole 27 with respect to the control valve hole 27. Then, according to the suction pressure Ps acting on the diaphragm 28 via the pressure-sensitive passage 29,
The opening of the control valve hole 27 by the control valve body 26 is adjusted.

By adjusting the opening of the displacement control valve 25, the supply amount of the refrigerant gas supplied from the discharge chamber 13b to the crank chamber 15 through the air supply passage 24 is changed. Then, the pressure difference between the pressure in the crank chamber 15 acting before and after the piston 21 and the pressure in the cylinder bore 12a is adjusted. Thereby, the inclination angle of the swash plate 19 is changed, the stroke of the piston 21 is changed, and the discharge capacity is adjusted.

The bleed passage 30 is formed to connect the crank chamber 15 and the suction chamber 13a. The bleed passage 30 includes an axial passage 16 a formed at the center of the drive shaft 16, a housing recess 12 b formed at the center of the rear end side of the cylinder block 12, and a discharge passage formed at the rear end face of the cylinder block 12. It comprises a pressure passage 12c and a pressure release hole 14c formed in the valve plate 14. The front end of the axial passage 16a is a radial bearing 1 having a front end.
7 is open to the crank chamber 15. The thrust bearing 31 and the shaft support spring 32 are interposed between the rear end of the drive shaft 16 and the valve plate 14 in the accommodation recess 12b.

As shown in FIGS. 1 to 3, a curved surface portion 33 is formed on the outer periphery of the swash plate 19. On the other hand, on the inner surface of the neck 21 c of the piston 21, abutting portions 34 are formed to protrude toward the swash plate 19 in the vicinity of both side edges. The inner surface of the neck 21c of the piston 21 is formed in a cylindrical shape having a radius of curvature substantially equal to the radius of curvature of the outer circumference of the swash plate 19 in the circumferential direction. That is, the inner surface of the neck 21 c of the piston 21 is formed in a shape substantially corresponding to the outer periphery of the swash plate 19 along the circumferential direction of the swash plate 19. When a rotational moment about the axis of the piston 21 is applied to the piston 21, the curved surface portion 33 on the outer periphery of the swash plate 19 and the contact portion 34 of the neck 21 c of the piston 21.
Are arranged so as to be able to abut.

Next, the operation of the variable displacement compressor configured as described above will be described. In this compressor, when the drive shaft 16 is rotated by an external drive source such as a vehicle engine, the swash plate 19 is integrally rotated via the rotation support 18 and the hinge mechanism 20. The rotational movement of the swash plate 19 is converted into a reciprocating linear movement of the piston 21 via the shoe 22, and the head 21a of the piston 21 is reciprocated in the cylinder bore 12a. By the reciprocating motion of the piston 21, the refrigerant gas is sucked from the suction chamber 13a into the cylinder bore 12a via the suction valve 14a, compressed until reaching a predetermined pressure, and discharged through the discharge chamber 13b through the discharge valve 14b.
Is discharged to

Next, the capacity control operation of the variable capacity compressor will be described. When the compressor is stopped, the suction chamber 1
The pressures in the discharge chamber 3a, the discharge chamber 13b, and the crank chamber 15 are substantially balanced. At this time, the control valve body 26 of the capacity control valve 25 is held at a position where the control valve hole 27 is closed. In this state, when the compressor is started,
As described above, the head portion 21a of the piston 21 is reciprocated in the cylinder bore 12a. The reciprocating motion of the piston 21 compresses the refrigerant gas and discharges the refrigerant gas to the discharge chamber 13b.

When the temperature in the vehicle compartment is high and the cooling load is large, the suction pressure Ps in the suction chamber 13a is high,
There is almost no pressure difference between the pressure Pc in the crank chamber 15 and the pressure in the cylinder bore 12a via the piston 21. For this reason, the swash plate 19 is arranged at the maximum inclination state shown by the solid line in FIG. 1, the stroke of the piston 21 is increased, and the compressor is operated at the maximum displacement. At this time, since the high suction pressure Ps acts on the diaphragm 28 of the displacement control valve 25 via the pressure sensing passage 29, the control valve body 26 remains in the state where the control valve hole 27 is closed. That is, the supply passage 24 is shut off, and the supply of the high-pressure refrigerant gas from the discharge chamber 13b to the crank chamber 15 is stopped.

During the compression and discharge strokes in which the piston 21 is moved from the bottom dead center position to the top dead center position, blow-by gas flows into the crank chamber 15 from the gap between the outer peripheral surface of the piston 21 and the inner peripheral surface of the cylinder bore 12a. Inflow. Here, the blow-by gas flowing into the crank chamber 15 is supplied to the axial passage 16 a forming the bleed passage 30 and the accommodating recess 12.
b, and is returned to the suction chamber 13a through the pressure release passage 12c and the pressure release hole 14c. Thereby, the crankcase 1
The rise in pressure due to the blow-by gas in 5 is suppressed,
The operation of the compressor with the large displacement is continued.

When the temperature in the passenger compartment decreases and the cooling load decreases, the suction pressure Ps in the suction chamber 13a decreases. This low suction pressure Ps is applied to the displacement control valve 2 via the pressure sensing passage 29.
5 acts on the diaphragm 28 and the diaphragm 2
8 is displaced according to the degree of reduction of the suction pressure Ps. With the displacement of the diaphragm 28, the control valve body 26 is moved in a direction to open the control valve hole 27, and the opening area of the supply passage 24 at the capacity control valve 25 is increased. Then, high-pressure refrigerant gas is supplied from the discharge chamber 13b to the air supply passage 2
4 to the crank chamber 15. The flow rate of the refrigerant gas supplied to the crank chamber 15 is controlled by the control valve hole 27.
Is changed according to the opening of the vehicle. As a result, the crank chamber 15
, The pressure difference between the pressure Pc in the crank chamber 15 and the pressure in the cylinder bore 12a through each piston 21 increases. In accordance with this differential pressure, the swash plate 19 is moved to the minimum tilt angle side, the stroke of the piston 21 is reduced, and the discharge capacity is reduced.

When the temperature in the passenger compartment further decreases and approaches a state where the cooling load hardly exists, the suction chamber 1
The suction pressure Ps in the pressure control valve 3a further decreases, and the displacement control valve 2
The fifth control valve hole 27 is opened at the maximum opening. In this state, high-pressure refrigerant gas is discharged from the discharge chamber 13b into the air supply passage 2
4 to the crank chamber 15 in large quantities. For this reason, the pressure difference between the pressure Pc in the crank chamber 15 and the pressure in the cylinder bore 12a through the respective pistons 21 is further increased, and the swash plate 19 is arranged in the minimum inclination state shown by the chain line in FIG. Then, the stroke of the piston 21 is further reduced, and the compressor is operated at the minimum displacement.

On the other hand, when the operation of the compressor in a certain discharge capacity state is continued and the temperature in the passenger compartment increases and the cooling load increases, the suction pressure Ps in the suction chamber 13a increases. In this state, the increased suction pressure Ps acts on the diaphragm 28 of the capacity control valve 25 via the pressure-sensitive passage 29, and the diaphragm 28 is displaced in accordance with the degree of increase of the suction pressure Ps. With the displacement of the diaphragm 28, the control valve body 26 is moved in a direction to close the control valve hole 27, and the opening area of the supply passage 24 at the capacity control valve 25 is reduced. Then, the flow rate of the high-pressure refrigerant gas supplied from the discharge chamber 13b to the crank chamber 15 through the air supply passage 24 is reduced. As a result, the pressure Pc of the crank chamber 15
And the pressure difference between the pressure Pc in the crank chamber 15 and the pressure in the cylinder bore 12a via each piston 21 decreases. In accordance with this differential pressure, the swash plate 19 is moved to the maximum tilt angle side, the stroke of the piston 21 is increased, and the displacement is increased.

When the temperature in the passenger compartment further increases and the cooling load further increases, the suction pressure Ps in the suction chamber 13a also increases accordingly. When the high suction pressure Ps acts on the diaphragm 28 of the capacity control valve 25 via the pressure sensing passage 29, the control valve body 26 closes the control valve hole 27, and the air supply passage 24 is shut off. Then, the high-pressure refrigerant gas from the discharge chamber 13b is not supplied to the crank chamber 15. Then, the refrigerant gas in the crank chamber 15 is exclusively extracted into the suction chamber 13a via the bleed passage 30, and the pressure Pc in the crank chamber 15 decreases so as to approach the suction pressure Ps in the suction chamber 13a. Therefore, the differential pressure between the pressure Pc in the crank chamber 15 and the pressure in the cylinder bore 12a through each piston 21 becomes small, and the swash plate 1
9 is arranged in a maximum tilt state. And the piston 21
Is increased, and the compressor is operated at the maximum displacement.

As described above, in this variable displacement compressor, the pressure Pc of the crank chamber 15 rises and falls by adjusting the opening of the displacement control valve 25 in accordance with the cooling load, that is, the fluctuation of the suction pressure Ps. As a result, the pressure difference between the pressure Pc in the crank chamber 15 and the pressure in the cylinder bore 12a is changed, and the swash plate 19 is set between the maximum tilt state and the minimum tilt state to an arbitrary tilt angle corresponding to the differential pressure. Be placed. And piston 2
The stroke is changed, the discharge capacity is changed, and finally, the suction pressure Ps is controlled to be substantially constant.

During operation of the compressor, the drive shaft 16 is rotated, and the swash plate 19 is rotated integrally with the drive shaft 16. The rotational motion of the swash plate 19 is converted into an axial reciprocating motion of each piston 21 via a pair of shoes 22. At the same time, each piston 21 is also provided with a rotational moment to rotate around its axis. As described above, when a rotational moment acts on the piston 21, the curved portion 33 formed on the outer periphery of the swash plate 19 and the contact portion 34 formed on the inner surface of the neck 21 c of the piston 21 come into contact with each other. For this reason, the piston 21
The rotation around the further axis is reliably restricted.

The effects that can be expected from the first embodiment will be described below. (A) In the compressor of the first embodiment, a curved surface portion 33 is formed on the outer periphery of the swash plate 19, and the curved surface portion 33 contacts the contact portion 34 on the inner surface of the neck 21 c of the piston 21. They are arranged as possible. For this reason, the swash plate 19
When a rotational moment about the axis is applied to the piston 21 with the rotation of the swash plate, the curved surface portion 33 of the swash plate
Then, the contact portion 34 of the piston 21 abuts, and the rotation of the piston 21 is restricted. Moreover, the configuration for restricting the rotation of the piston 21 is simple. Therefore, unlike the conventional configuration, it is not necessary to form a large anti-rotation projection on the outer periphery of the neck 21c of the piston 21. Therefore, the piston 21 can be easily processed, and the weight of the piston 21 can be reduced.

Further, since the curved surface portion 33 is formed on the outer periphery of the swash plate 19, when the outer periphery of the swash plate 19 and the contact portion 34 of the piston 21 come into contact with each other, the outer periphery of the swash plate 19 and the piston 2
The inner surface of the first neck portion 21c does not come into contact with the corner. Therefore, the curved portion 33 of the swash plate 19 and the piston 21
A large increase in the contact surface pressure between the contact portion 34 is suppressed. Therefore, it is possible to prevent the inner surface of the neck 21a of the piston 21 from being damaged by the contact with the outer periphery of the swash plate 19, and it is possible to reduce the risk of damage to the neck 21b.

Further, the curved surface portion 33 of the swash plate 19 is
This effectively contributes to the lubricating oil scattered in the crank chamber 15 between the contact surface between the outer periphery of the piston 9 and the contact portion 34 of the piston 21. For this reason, the possibility of further damage occurring between the contact surfaces can be reduced.

(B) In the compressor of the first embodiment, the swash plate 1 is formed on the inner surface of the neck 21c of the piston 21.
An abutting portion 34 that abuts the curved surface portion 33 of the swash plate 9 protrudes toward the swash plate 19. That is, the neck 21 of the piston 21
The thickness of c is large at a portion corresponding to the contact portion 34. Therefore, the portion corresponding to the contact portion 34 is reinforced, and the risk of damage to the neck 21c of the piston 21 due to contact with the outer periphery of the swash plate 19 can be reduced.

(C) In the compressor according to the first embodiment, the contact portions 34 of the piston 21 are formed near both side edges of the inner surface of the neck 21c. Therefore, the piston 2
The abutment between the inner surface of the neck 21c and the outer periphery of the swash plate 19 is made near both side edges of the inner surface of the neck 21c. Therefore, by contact with the outer periphery of the swash plate 19, it is possible to prevent the neck 21c of the piston 21 from being damaged in the vicinity of the center where the highest strength is required, and to prevent the neck 21c from being damaged. .

(D) In the compressor of the first embodiment, the inner surface of the neck 21c of the piston 21 is
Is formed in a shape substantially corresponding to the outer periphery of the swash plate 19 along the circumferential direction of the swash plate 19. For this reason, it is suppressed that the outer periphery of the swash plate 19 and the inner surface of the neck 21c of the piston 21 come into strong contact locally. Accordingly, the contact surface pressure between the contact surfaces does not greatly increase, and the risk of occurrence of damage between the contact surfaces can be further reduced in combination with the effect described in the above item (1).

(E) In the compressor of the first embodiment, the difference between the pressure Pc in the crank chamber 15 and the pressure in the cylinder bore 12a via the piston 21 is determined based on the adjustment of the opening of the displacement control valve 25. The pressure is changed, and the inclination angle of the swash plate 19 is changed in accordance with the pressure difference to control the discharge capacity. In other words, in this compressor, the swash plate 19 is arranged at an arbitrary inclination according to the differential pressure between the maximum inclination state and the minimum inclination state. A curved surface portion 33 is formed on the outer periphery of the swash plate 19 that is in contact with the inner surface of the neck portion 21c of the piston 21. Therefore, regardless of the inclination angle of the swash plate 19, the swash plate 19
Of the piston 21 and the inner surface of the neck 21c of the piston 21 do not come into contact with each other. That is, avoiding a large increase in the contact surface pressure, the outer periphery of the swash plate 19 and the neck 2 of the piston 21 are prevented.
1c can be brought into contact with the inner surface. Also, swash plate 1
Even when the swash plate 19 is tilted in a state in which the outer periphery of the swash plate 9 and the inner surface of the neck 21c of the piston 21 are in contact with each other, it is possible to ensure a smooth tilt of the swash plate 19. (Second Embodiment) Next, similarly to the first embodiment, the second embodiment in which the present invention is embodied in a single-head piston type variable displacement compressor is different from the first embodiment. The description will focus on the parts.

In the second embodiment, as shown in FIGS. 4 and 5, a cylindrical extension 37 is integrally formed in front of the cylinder block 12 so as to protrude. This extension 3
A crank chamber 15 is formed by the front housing 11 and the substantially flat front housing 11. The plurality of concave guide portions 38 are formed on the inner peripheral surface of the extension portion 37 of the cylinder block 12 so as to be continuous with each of the cylinder bores 12a. Each of the pistons 2 is
The outer peripheral surface of the first member is slidably engaged.

When the piston 21 is reciprocated by the rotation of the swash plate 19, the piston 21 is largely exposed in the crank chamber 15 near the bottom dead center position. In this state, the piston 21 may be twisted between the head 21a housed in the cylinder bore 12a and the tail 21b moored to the swash plate 19. Here, in the compressor according to the second embodiment, the piston 21 is configured such that the outer peripheral surface thereof is slidably moved along the guide portion 38, so that the operation in the torsional direction is corrected. Thus, accurate reciprocation of the piston 21 in the axial direction is ensured.

Among the effects that can be expected from the second embodiment, the effects different from those of the first embodiment will be described below. (A) In the compressor of the second embodiment, a guide portion 38 engageable with the outer peripheral surface of each piston 21 is provided on the inner peripheral surface of the cylinder block 12 corresponding to the crank chamber 15.
Are formed. Therefore, the piston 21 can be smoothly reciprocated along the guide portion 38 while correcting the operation in the twisting direction between the head portion 21a and the tail portion 21b.

(B) In the compressor of the second embodiment, a cylindrical extension 37 is formed by extending the cylinder block 12 toward the crank chamber 15, and a guide portion is formed on the inner peripheral surface of the extension 37. 38 is formed so as to be continuous with the cylinder bore 12a. Therefore, there is no seam of the housing in the middle of the guide portion 38, and the piston 21 can reciprocate more smoothly.

The present invention can be embodied with the following modifications. (1) Instead of the curved surface portion 33 on the outer periphery of the swash plate 19 in the above embodiment, a round or tapered chamfered portion is formed on both side edges of the outer periphery of the swash plate 19.

(2) The present invention is embodied in a compressor having a double-headed piston. (3) The present invention is embodied in a fixed displacement compressor having a fixed discharge capacity.

Even with such a configuration, substantially the same operation and effect as those of the above-described embodiments can be exerted. (4) Both ends of the contact portion 34 on the piston 21 in the above embodiment are formed in a curved shape.

With this configuration, when the outer periphery of the swash plate 19 is in contact with the inner surface of the neck 21c of the piston 21, the contact surface pressure between the contact surfaces can be further reduced.

[0056]

The present invention is configured as described above, and has the following effects. According to the first aspect of the present invention, the rotation of the piston around the axis can be reliably restricted with a simple configuration. Further, it is not necessary to form a large rotation restricting portion on the outer peripheral surface of the piston, so that the processing of the piston can be simplified and the weight can be reduced.

The contact between the outer periphery of the cam plate and the inner surface of the neck of the piston does not significantly increase the contact surface pressure between the contact surfaces, and effectively removes the lubricating oil scattered in the compressor. Can be pulled in between. Therefore, it is possible to reduce a possibility that damage occurs between the contact surfaces.

According to the second aspect of the present invention, the portion corresponding to the contact portion of the piston with the cam plate is reinforced, and the risk of damage to the neck portion of the piston due to the contact with the outer periphery of the cam plate is reduced. can do.

According to the third aspect of the present invention, the abutment with the outer periphery of the cam plate hardly damages the vicinity of the center where the strength is most required at the neck of the piston, and suppresses the damage of the neck. can do.

According to the fourth aspect of the present invention, the contact surface pressure between the contact surface between the outer periphery of the cam plate and the inner surface of the neck of the piston does not greatly increase. In addition, the possibility of occurrence of damage between the contact surfaces can be further reduced.

According to the fifth aspect of the present invention, the piston can be smoothly reciprocated along the guide portion while correcting the operation in the torsional direction. According to the sixth aspect of the present invention, the joint of the housing does not exist in the middle of the guide portion, and the piston can reciprocate more smoothly.

According to the seventh aspect of the present invention, in the variable displacement compressor, the contact surface pressure between the outer periphery of the cam plate and the inner surface of the neck of the piston is prevented from greatly increasing, regardless of the inclination of the cam plate. Can be brought into contact. Further, even when the cam plate is tilted in a state where the outer periphery of the cam plate is in contact with the inner surface of the neck of the piston, smooth tilting of the cam plate can be ensured.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a variable displacement compressor according to a first embodiment.

FIG. 2 is an enlarged front view showing a piston of the variable displacement compressor.

FIG. 3 is a sectional view taken along line 3-3 in FIG. 2;

FIG. 4 is a sectional view showing a variable displacement compressor according to a second embodiment.

FIG. 5 is a sectional view taken along line 5-5 in FIG. 4;

[Explanation of symbols]

Reference numeral 11: a front housing constituting a part of the housing; 12, a cylinder block constituting a part of the housing; 12a, a cylinder bore; 13, a rear housing constituting a part of the housing; 15, a crank chamber; 16, a drive shaft; 19 ... swash plate as cam plate, 21 ...
Piston, 21c: neck, 25: capacity control valve, 33: curved surface, 34: abutment, 37: extension, 38: guide.

Claims (7)

[Claims] 1. A crank chamber is formed inside a housing and a drive shaft is rotatably supported. A cylinder bore is formed in a cylinder block constituting a part of the housing, and a piston is reciprocally movable in the cylinder bore. A housing that accommodates and supports a cam plate on a drive shaft so as to be integrally rotatable in the crank chamber and that reciprocates a piston via the cam plate by rotation of the drive shaft; Alternatively, a compressor in which a chamfered portion is formed, and the curved portion or the chamfered portion is arranged so as to be able to abut on the inner surface of the neck of the piston. 2. The compressor according to claim 1, wherein a contact portion that contacts a curved surface portion or a chamfered portion of the cam plate is formed on the inner surface of the neck portion of the piston so as to project toward the cam plate. 3. The compressor according to claim 1, wherein the contact portions are provided near both side edges of the inner surface of the neck. 4. The compressor according to claim 1, wherein the inner surface of the neck of the piston is formed in a shape substantially corresponding to the outer periphery of the cam plate along the circumferential direction of the cam plate. 5. The compressor according to claim 1, wherein a guide portion engageable with an outer peripheral surface of the piston is formed on an inner peripheral surface of the housing corresponding to the crank chamber. 6. The compressor according to claim 5, wherein the cylinder block is extended toward the crank chamber, and the guide portion is formed on an inner peripheral surface of the extension of the cylinder block so as to be continuous with the cylinder bore. 7. The cam plate is swingably supported on a drive shaft, and a pressure difference between a pressure in a crank chamber and a pressure in a cylinder bore through the piston is changed based on adjustment of an opening of a displacement control valve. The compressor according to any one of claims 1 to 6, wherein the displacement is controlled by changing the inclination angle of the cam plate according to the differential pressure.