JP2001323872A - Swash plate type compressor piston - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce size and weight of a compressor and increase the strength of a neck portion of a piston. SOLUTION: This single-headed piston 14 of a swash plate type compressor is provided with a hollow head portion 76, a pair of engaging portions 70, 72 engaged with a swash plate 50, and a neck portion 74 coupling the engaging portions 70, 72 on the outer peripheral side of the4 swash plate 50. The engaging portions 70, 72 slidably sandwich the outer periphery portion of the swash plate 50 from both sides through a pair of hemispherical shoes 78. On surfaces opposite to each other of the engaging portions 70, 72, concave portions 140 are provided, which slidably holds the shoes 78 at a convex spherical surface 144 thereof. These concave portions 140 have a common spherical center, the spherical center passing a center axis line of the head portion 76, locating on a plane parallel to an extending direction of the engaging portion 70, 72, and having eccentricity to the opposite side to the head portion 74 (an inner periphery side of the compressor) from the center axis line of the head portion 76. The amount of eccentricity is preferably not less than 1/30 of the diameter of the head portion 76. The thickness of the head portion 74 can be increased, and the bending strength of the head portion 74 is improved. By decreasing the diameter of the swash plate 50, the compressor can be reduced in weight and improved in durability.

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 compressor, and more particularly to an improvement of a piston.

[0002]

2. Description of the Related Art Swash plate compressors are widely used, for example, as refrigerant compressors for air conditioners for vehicles.
As one type of the swash plate compressor, (1) a swash plate that rotates while being inclined from a state perpendicular to the rotation axis, and (2) a swash plate formed at a position eccentric from the rotation axis and parallel to the rotation axis. A housing having a cylinder bore, (3) a pair of engaging portions that engage with both surfaces of the outer peripheral portion of the swash plate via the shoe device, respectively, a neck portion that connects the both engaging portions on the outer peripheral side of the swash plate, and And a piston integrally provided with a head slidably fitted in the cylinder bore.

[0003] In the piston of this type of swash plate type compressor, securing the strength of the neck is one of the important problems.
The neck extends through a gap between the outer peripheral surface of the swash plate and the inner peripheral surface of the housing and connects the pair of engagement portions. However, in order to reduce the size and weight of the compressor, the inner peripheral surface of the housing is formed. There is a strong requirement that the diameter be as small as possible, for which purpose it is desirable to position the back of the neck as close as possible to the axis of rotation of the swash plate. On the other hand, it is also required to increase the maximum discharge flow rate of the swash plate type compressor. In order to satisfy both this requirement and the above-mentioned requirement for small size and light weight, it is effective to increase the rotation speed of the swash plate. It is. However, if the rotation speed of the swash plate is increased, the inertial force accompanying the reciprocating motion of the piston increases, and based on this, the bending moment acting on the neck near the top dead center of the piston increases, resulting in the required bending of the neck. Strength increases. Bringing the back position of these necks as close as possible to the rotation axis of the swash plate and increasing the bending strength of the neck are mutually exclusive requirements, and it is important to meet these conflicting requirements. It is one of the.

[0004]

SUMMARY OF THE INVENTION The object of the present invention is to satisfy the conflicting demands of a compact and lightweight compressor and an increase in the strength of the neck portion of a piston in view of the above circumstances. According to the present invention, a swash plate type compressor and a piston for the swash plate type compressor according to the following embodiments can be obtained. As in the case of the claims, each aspect is divided into sections, each section is numbered, and if necessary, the other sections are cited in a form in which the numbers are cited. This is for the purpose of facilitating the understanding of the present invention and should not be construed as limiting the technical features and combinations thereof described in the present specification to those described in the following sections. . Further, when a plurality of items are described in one section, the plurality of items need not always be adopted together. It is also possible to select and adopt only some of the items.

(1) A pair of engaging portions which engage with both surfaces of the outer peripheral portion of the swash plate via the respective shoe devices, a neck portion connecting the both engaging portions on the outer peripheral side of the swash plate, and a cylinder bore. A swash plate compressor piston integrally provided with a movably fitted head, the piston having a concave spherical surface formed on each of the pair of engaging portions and engaging with a convex spherical surface of the shoe device. A piston for a swash plate type compressor, wherein a spherical center is located on a side opposite to the neck with respect to a center axis of the head (Claim 1). The shoe device of the swash plate compressor may be configured by a ball and a shoe having a concave spherical surface that receives the spherical surface of the ball, or may be configured by only a semi-spherical semi-spherical shoe. In this case, a concave spherical surface is formed in the engagement portion of the piston so as to receive a convex spherical surface of a ball or a hemispherical shoe. Conventionally, it has been considered that the spherical center of the concave spherical surface must be located on the central axis of the head of the piston. This is to prevent an eccentric load from acting on the piston. For it,
In the present invention, the spherical center of the concave spherical surface is eccentric to the side opposite to the neck from the center axis of the piston, that is, the side closer to the rotation axis side of the swash plate (hereinafter referred to as the compressor inner peripheral side). As a result, the outer diameter of the swash plate can be reduced, and if the inner diameter of the housing is the same, the gap between the outer peripheral surface of the swash plate and the inner peripheral surface of the housing increases. Therefore, it is possible to increase the thickness of the neck portion passing through this gap (the radial dimension of the swash plate compressor). In order to increase the bending strength of the neck, it is much more effective to increase the thickness of the neck than to increase the width (dimension in the circumferential direction of the swash plate type compressor). The strength of the neck can be effectively increased. Further, if the spherical center of the concave spherical surface is moved to the inner peripheral side of the compressor, the spherical center of the convex spherical surface of the shoe device received by the concave spherical surface also moves to the inner peripheral side of the compressor. The outer diameter of the swash plate to be combined can be small, and the weight of the swash plate compressor can be reduced accordingly. Further, the effect of reducing the PV value, which is one of the indexes indicating the physical strength of the compressor, can be obtained. Here, P is the force of the swash plate pushing the piston, and V is the peripheral speed at the contact point between the swash plate and the shoe device. As described above, the smaller the diameter of the swash plate, the smaller the peripheral speed V, and the smaller the PV value, as long as the force P is constant. Alternatively, it is possible to increase the maximum discharge capacity by increasing the peripheral speed V while keeping the PV value as usual. (2) The piston for a swash plate compressor according to (1), wherein the amount of eccentricity of the ball center from the center axis is not less than 1/30 of the diameter of the head. The eccentricity is set to 1/30 or more, 1/20 or more, 1/16 or more, 1/1 of the diameter of the head.
The strength of the neck can be increased as the size is increased to 4 or more and 1/12 or more. (3) The piston for a swash plate type compressor according to (1) or (2), wherein the head is provided only on one side of the pair of engagement portions and the neck portion (Claim 3). A piston having a head only on one side is called a single-headed piston, and can be used for a fixed displacement compressor in which the inclination angle of the swash plate does not change.However, discharge is achieved by changing the inclination angle of the swash plate. This is particularly effective for a variable displacement compressor whose capacity is changed. This is because, if the present invention is applied to this single-headed piston, in addition to the above-described effects, a unique effect of favorably affecting the operation of the piston can be obtained. For example, in a variable displacement type swash plate compressor, after the operation of the compressor is stopped in a state where the inclination angle of the swash plate is large, the swash plate is returned to the minimum inclination angle state by the urging force of the urging device. However, the effect of facilitating the return is obtained. When the operation of the compressor is stopped in a state where the displacement is large, one of the pistons has a particularly short fitting length with the cylinder bore.
In order to return the swash plate to the minimum inclination angle state by the biasing device, it is necessary to push a piston having a short fitting length with the cylinder bore into the cylinder bore, but the swash plate is inclined. Therefore, the force applied from the swash plate to the piston via the shoe device has a component directed toward the outer periphery. Due to this component, the piston is squeezed in the cylinder bore, and the surface pressure of the neck side portion (compressor outer side portion) of the inner peripheral surface of the cylinder bore and the outer peripheral surface of the piston head increases, thereby increasing the frictional resistance. . Therefore, conventionally, the portion of the cylinder bore on the outer peripheral side of the compressor is made longer than the portion on the inner peripheral side of the compressor to reduce the surface pressure of the portion on the neck side, but according to the present invention, When the point of action of the force applied to the piston via the shoe device is shifted toward the inner peripheral side of the compressor, a rotational moment is generated in the piston by an eccentric load. Since the direction of the rotational moment is opposite to the direction of the rotational moment based on the component toward the outer periphery, the latter can be reduced by the former. (4) The piston for a swash plate compressor according to any one of (1) to (3), wherein the two concave spherical surfaces of the pair of engaging portions have a common spherical center. The piston for a swash plate type compressor according to this embodiment is particularly effective for a variable displacement compressor. Assuming that the two concave spherical surfaces of the pair of engaging portions have a common spherical center, even if the inclination angle of the swash plate changes, the pair of hemispherical shoes are farthest apart in a direction parallel to the central axis of the piston. This is because the distance between the portions does not change, and therefore, the gap between the pair of engagement portions and the shoe device does not change. However, it can of course be used for a fixed capacity compressor. (5) The back surface of the neck is located closer to the center axis of the head than the outer peripheral surface of the head of the piston. (1) to (4)
Item 6. A piston for a swash plate type compressor according to any one of the above items. The piston of this embodiment does not require machining the back of the neck. Usually, the head must be machined in order to be fitted with the cylinder bore with high precision. that time,
If the back surface of the neck is located closer to the central axis than the outer peripheral surface of the head, the back surface does not need to be machined. As a result, the number of processing steps can be reduced, but the strength of the neck can be improved. Piston materials are usually manufactured by forging or casting, but these materials have higher strength when the surface is not machined. In the single-headed piston, an anti-rotation portion having a partial cylindrical surface having a larger radius of curvature than the outer peripheral surface of the head is formed. The engagement of the anti-rotation portion with the inner peripheral surface of the housing causes the central axis of the single-headed piston to move. It is common that the rotation around is prevented, and the outer peripheral surface of the anti-rotation part is also usually machined. If it is located on the inner circumferential side of the compressor, which is closer to the side, the back surface of the neck does not need to be machined even when machining the rotation preventing portion. (6) Of the pair of engaging portions, at least a tip of the engaging portion on the head side, which is an end farther from the neck portion, is located within an extended cylindrical surface extending the outer peripheral surface of the head. The piston for a swash plate type compressor according to any one of (1) to (5). With this configuration, even when the engaging portion on the head side enters the cylinder bore at the top dead center of the piston, interference between the distal end of the engaging portion and the inner peripheral surface of the cylinder bore can be avoided. (7) The piston for a swash plate type compressor according to any one of (1) to (6), wherein the neck portion has a rib extending in an axial direction on a back surface. By forming a rib extending in the axial direction on the back surface of the neck, the bending strength of the neck can be effectively increased while avoiding an increase in the weight of the piston. Although only one rib may be provided, it is often more effective to use a plurality of ribs. (8) A swash plate that rotates while being inclined from a state perpendicular to the rotation axis, a housing having a cylinder bore formed eccentrically from the rotation axis and parallel to the rotation axis, and an outer periphery of the swash plate A pair of engaging portions that engage with both surfaces of the portion via the shoe device, a neck portion that connects the two engaging portions on the outer peripheral side of the swash plate, and a head that is slidably fitted to the cylinder bore are integrally formed. A swash plate type compressor including a piston provided on the head, a spherical center of a concave spherical surface formed on each of the pair of engaging portions and engaging with the convex spherical surface of the shoe device, from the center axis of the head. A swash plate type compressor, which is located on the rotation axis side. The above (2)
The configurations described in the paragraphs, (3) and (5) to (7) can be adopted also in the swash plate type compressor of this paragraph. (9) The shoe device is a hemispherical shoe having a substantially hemispherical shape having the convex spherical surface and a substantially flat sliding surface.
The swash plate compressor according to item (8). (10) A tilt angle changing device for changing the tilt angle of the swash plate is provided, and two concave spherical surfaces of the pair of engaging portions have a common spherical center.
The swash plate compressor according to item (9).

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A swash plate type compressor used in a vehicle air conditioner according to an embodiment of the present invention and a piston therefor will be described below in detail with reference to the drawings.
FIG. 1 shows a swash plate type compressor according to the present embodiment. In FIG. 1, reference numeral 10 denotes a cylinder block, and a plurality of cylinder bores 12 extending in parallel with the central axis are formed at equal angular intervals on one circumference around the central axis of the cylinder block 10. Each of the cylinder bores 12 is provided with a single-headed piston 14 (hereinafter abbreviated as piston 14) so as to be able to reciprocate. A front housing 16 is mounted on one axial end surface of the cylinder block 10 (the left end surface in FIG. 1 and referred to as a front end surface), and the other end surface (the right end surface in FIG. 1 and a rear end surface). )
A rear housing 18 is mounted via a valve plate 20. The front housing 16, the rear housing 18, and the cylinder block 10 constitute a housing of the swash plate type compressor. A suction chamber 22 and a discharge chamber 24 are formed between the rear housing 18 and the valve plate 20, and are connected to a refrigeration circuit (not shown) via a suction port 26 and a supply port 28, respectively. The valve plate 20 has a suction hole 32, a suction valve 34, a discharge hole 3
6, a discharge valve 38 and the like are provided.

On the central axis of the cylinder block 10,
A rotation shaft 44 is rotatably provided. Rotating shaft 44
Are supported by the front housing 16 and the cylinder block 10 via bearings at both ends. A center support hole 48 is formed in the center of the cylinder block 10, and is supported by the center support hole 48. The end of the rotating shaft 44 on the front housing 16 side is connected to a vehicle engine as an external drive source, which is a kind of a drive source (not shown), via a clutch mechanism such as an electromagnetic clutch. Therefore, when the rotating shaft 44 is connected to the vehicle engine by the clutch mechanism during operation of the vehicle engine, the rotating shaft 44 is rotated around its own axis.

A swash plate 50 is attached to the rotating shaft 44 so as to be relatively movable and tiltable in the axial direction. Swash plate 50
Is formed with a through hole 52 passing through the center of the swash plate 50, and the rotating shaft 44 passes through the through hole 52. Through hole 52
The inner dimensions are gradually increased in the up and down direction toward the both end opening sides, and the cross-sectional shapes of both end portions are elongated holes. The rotating shaft 44 also has a rotating plate 54 as a rotation transmitting member.
Is fixed, and is engaged with the front housing 16 via a thrust bearing 56. The swash plate 50 is rotated integrally with the rotation shaft 44 by the hinge mechanism 60, and is allowed to tilt with movement in the axial direction. The hinge mechanism 60 includes a support arm 62 fixedly provided on the rotating plate 54 and an engagement pin 66 fixedly provided on the swash plate 50 and slidably fitted in an engagement hole 64 of the support arm 62. , The through hole 52 of the swash plate 50, and the outer peripheral surface of the rotating shaft 44. In the present embodiment, the rotating shaft 44, the hinge mechanism 60 constituting the rotation transmitting device, and the like constitute a swash plate driving device, and this swash plate driving device constitutes a reciprocating driving device for reciprocating the piston 14 together with the swash plate 50. are doing.

The piston 14 is a kind of a hollow piston, and has a pair of engaging portions 70 and
72, a neck 74 connecting the two engaging portions 70, 72 on the outer peripheral side of the swash plate 50, and a engaging portion 70, 7
2, a hollow head 76 provided integrally with the neck 74 and slidably fitted to the cylinder bore 12. Note that the engaging portions 70 and 72, the neck 74 and the head 76 may not be integrated, but may be integrated by a coupling means such as screwing. The swash plate 50 is engaged with the engagement portions 70 and 72 via a pair of hemispherical shoes 78. A detailed description of the shapes of the piston 14 and the shoe 78 will be given later.

The rotational movement of the swash plate 50 is converted via a shoe 78 into a reciprocating linear movement of the piston 14. In the suction stroke in which the piston 14 moves from the top dead center to the bottom dead center,
The refrigerant gas in the suction chamber 22 is supplied to the suction hole 32 and the suction valve 34.
Through the cylinder bore 12. Piston 14
In the compression stroke in which the refrigerant moves from the bottom dead center to the top dead center, the refrigerant gas in the cylinder bore 12 is compressed and discharged to the discharge chamber 24 through the discharge hole 36 and the discharge valve 38. An axial compression reaction force acts on the piston 14 as the refrigerant gas is compressed. The compression reaction force is received by the front housing 16 via the piston 14, the swash plate 50, the rotating plate 54, and the thrust bearing 56.

An air supply passage 80 is provided through the cylinder block 10. The discharge chamber 24 and the swash plate chamber 86 formed between the front housing 16 and the cylinder block 10 are connected by the air supply passage 80. In the middle of the air supply passage 80, a capacity control valve 90 is provided. The capacity control valve 90 is an electromagnetic valve, and the solenoid 92 is energized and demagnetized by a control device (not shown) mainly composed of a computer, and the amount of supplied current is controlled in accordance with information such as a cooling load. Is adjusted.

A discharge passage 100 is provided inside the rotary shaft 44. The discharge passage 100 has one end opened to the center support hole 48 and the other end opened to the swash plate chamber 86. The center support hole 48 communicates with the suction chamber 22 via the discharge port 104.

The swash plate type compressor is of a variable displacement type, and the pressure in the swash plate chamber 86 is controlled by utilizing the pressure difference between the discharge chamber 24 as a high pressure source and the suction chamber 22 as a low pressure source. , Cylinder bore 1 acting before and after piston 14
The difference between the pressure of the compression chamber in 2 and the pressure of the swash plate chamber 86 is adjusted, the inclination angle of the swash plate 50 is changed, the stroke of the piston 14 is changed, and the displacement of the compressor is adjusted.
Specifically, the pressure of the swash plate chamber 86 is controlled by controlling the demagnetization and the excitation of the capacity control valve 90 so that the swash plate chamber 86 is communicated with the discharge chamber 24 or cut off. The maximum inclination angle of the swash plate 50 is defined by the contact of the stopper 106 provided on the swash plate 50 with the rotating plate 54, and the minimum inclination angle is determined by the contact of the swash plate 50 with the stopper 108 on the rotating shaft 44. Defined by The air supply passage 80, the swash plate chamber 86, the displacement control valve 90, the discharge passage 100, the discharge port 104, the control device, and the like constitute a tilt angle changing device or a discharge displacement control device.

A compression coil spring 110 is disposed between the swash plate 50 and the rotary plate 54 as an elastic member which is a kind of a biasing device. (The rotation axis of the rotation shaft 44). If the operation of the compressor is stopped, the swash plate 50
Is stopped by the urging force of the spring 110.
8 and is in a state of waiting for restart. At the end of the through hole 52 of the swash plate 50 on the rotating plate 54 side,
When the concave portion 112 having a larger diameter than other portions is formed and the swash plate 50 is inclined to the maximum inclination angle, the spring 110 is formed on the receiving surface 114 of the concave portion 112 which is perpendicular to the center axis of the cylinder block 10. In a state where one end is received and has the minimum inclination angle, the concave portion 112 is received on the receiving surface 116 perpendicular to the central axis.

Cylinder block 10 and piston 14
Is made of an aluminum alloy, which is a kind of metal, and the outer peripheral surface of the piston 14 is coated with a fluororesin. By coating with a fluororesin, the fitting gap with the cylinder bore 12 can be reduced as much as possible while avoiding direct contact with the same kind of metal and preventing seizure. It is desirable that the cylinder block 10 and the piston 14 be made of an aluminum-silicon alloy. However, the material of the cylinder block 10 and the piston 14, the material of the coating layer, and the like are not limited to the above-described materials, and may be other materials.

The piston 14 will be described with reference to FIGS. Although not shown in detail, the head 76 is a hollow head formed by a closed-end cylindrical portion having one end opened and a closing member closing the opening of the bottomed cylindrical portion,
Weight has been reduced. The bottomed cylindrical portion constituting the main part of the head 76 is formed integrally with the engaging portion 72 on the bottom wall. The outer peripheral surface 120 of the head 76 has an engaging portion 72
A ring-shaped annular groove 122 for holding lubricating oil (see FIG. 2) is formed in the vicinity of the top surface, which is the opposite end surface.

As shown in FIG. 3, the neck 7 of the piston 14
The inner surface 130 of the fourth swash plate 50 side is a flat surface, and the rear surface 132 opposite to the inner surface 130 is a partially cylindrical surface that protrudes outward in the radial direction. The back surface 132 is located on the inner peripheral side that is the center axis side of the head 76 from the outer peripheral surface 120 of the head 76. The engagement part 70 includes the rotation prevention part 13.
6 (see FIG. 2) are provided integrally. The rotation preventing portion 136 is integrally provided on the base end side of the engaging portion 70 that is connected to the neck 74, protrudes outward from the outer peripheral surface 120 of the head 76, and has a curvature from the outer peripheral surface 120. It has a partial cylindrical surface with a large radius. Rotation prevention unit 136
By contacting the inner peripheral surface of the front housing 16 on this partial cylindrical surface, the rotation of the piston 14 around the central axis is prevented, and the collision between the piston 14 and the swash plate 50 is avoided. The distal ends of the engaging portions 70 and 72 opposite to the proximal end side connected to the neck portion 74 are located on the inner peripheral side with respect to the extended cylindrical surface extending from the outer peripheral surface 120 of the head portion 76. Interference with the inner peripheral surface is avoided.

Recesses 140 are formed on the inner surfaces of the engaging portions 70 and 72, respectively, facing each other. The inner surfaces of these recesses 140 have a concave spherical shape, and two of the two recesses 140
Two concave spherical surfaces are located on one spherical surface. The pair of shoes 78 are slidably held in the concave portion 140 on the convex spherical surface 144, abut on both sliding surfaces of the swash plate 50 on the substantially flat sliding surface 146, and move the outer peripheral portions of the swash plate 50 on both sides. Slidable from the front. The spherical center, which is the center of the concave spherical surface of each concave portion 140, includes the central axis of the head 76 of the piston 14, is located on a plane parallel to the extending direction of the engaging portions 70, 72, and Neck 7 than center axis
4 is eccentric by a fixed distance α on the opposite side. This eccentric amount α is desirably 1/30 or more of the diameter of the head 76, and in this embodiment, is 3 mm corresponding to 1/10 to 1/11 of the diameter of the head 76. .

In the present embodiment, the hemispherical shoe 7
8 independently constitutes a shoe device. According to the present embodiment, the spherical center of the concave portion 140 is eccentric from the center axis of the head portion 76 on the side opposite to the neck portion 74 (the inner peripheral side in the compressor), so that the thickness of the neck portion 74 (the neck portion 74) is reduced. (The dimension in the direction parallel to the extending direction of the engaging portions 70 and 72) can be increased, and the bending strength of the neck portion 74 can be improved, so that the durability of the piston 14 is improved.

Further, after the operation of the compressor is stopped with the inclination angle of the swash plate 50 being large, it is easy to return the swash plate 50 to the minimum inclination angle state. After the compressor is stopped, the swash plate 50 is returned to the minimum inclination state by the urging force of the compression coil spring 110.
Since the direction of the pressing force applied from 0 to the piston 14 is inclined with respect to the center axis of the piston 14, the piston 14 has a rotation in a direction in which the back surface 132 of the neck 74 approaches the inner peripheral surface of the housing. A moment is generated. On the other hand, in the present embodiment, the concave portions 1 of the engaging portions 70 and 72 are provided.
By being eccentric from the center axis of the head 76 toward the inner circumference side of the compressor (the center axis side of the compressor),
Due to the force applied from the swash plate 50 via the shoe 78 and the recess 140, a rotational moment is generated in the piston 14 in a direction opposite to the direction of the rotational moment, and the rotational moment is reduced. Accordingly, the surface pressure of the outer peripheral surface of the head 76 of the piston 14 on the outer peripheral side of the compressor and the corresponding portion of the inner peripheral surface of the cylinder bore 12 is reduced, and the swash plate 5
It is easy to return to the minimum inclination angle state of zero. Further, the diameter of the swash plate 50 engaged with the engaging portions 70 and 72 can be reduced by shifting the spherical center of the concave portion 140 toward the inner peripheral side of the compressor. The reciprocating drive device of the piston 14 including the piston 54 can be reduced in weight. Further, by reducing the diameter of the swash plate 50, as described above, the PV value can be reduced, and the durability of the compressor improves.

The strength of the neck may be improved by providing a plurality of ribs on the back of the neck. One embodiment is shown in FIG. The single-headed piston 200 of FIG. 4 also has a pair of engaging portions 202 (only one of which is shown in FIG. 4), a neck portion 206 connecting the base ends of these engaging portions 202, A hollow cylindrical head 208 provided integrally with the engaging portion 202 is provided.

Inner surface 212 of swash plate side of neck portion 206
And the back surface 214 formed on the opposite side are both flat. A plurality of reinforcing ribs are provided integrally on the back surface 214. On the back surface 214, the engaging portion 2
02 in the width direction, which is a direction perpendicular to both the extending direction of the head part 208 and the central axis of the head part 208, and the head part 208
A plurality (three in the illustrated example) of axial ribs 220, 222, 224 are integrally provided in a state extending in parallel with the central axis of.

In the engagement portion 202 and the engagement portion extending similarly and separated from the engagement portion 202, concave inner surfaces 2 each having the same configuration as the concave portion 140 are formed on inner surfaces facing each other.
30 are formed. The spherical centers of the concave portions 230 are common, pass through the central axis of the head 208 of the piston 200, and are located on a plane parallel to the extending direction of the engaging portion 202. It is eccentric to the side opposite to 206. In the illustrated example, the engaging portion 2
02 is located farthest from the neck 206 within a range that does not protrude from an extended cylindrical surface that extends the outer peripheral surface 232 of the head 208, and
Since the amount of eccentricity of the head 208 from the central axis is increased, the neck 206 has high axial ribs 220, 222, 2.
24 can be formed.

According to this embodiment, by eccentricizing the spherical center of the concave portion 230, the same effect as that described in the above embodiment can be obtained, and the axial ribs 220 and 22 can be obtained.
Due to the formation of 2, 224, the bending strength of the neck 74 can be increased while the weight of the piston 14 is prevented from increasing as much as possible, and the durability of the piston 14 can be improved.

The axial ribs 220, 2 in the present embodiment
Reference numerals 22 and 224 are examples of ribs, and the ribs may have various shapes, dimensions, and the number of ribs. For example, one axial rib is formed at each of both edges in the width direction of the neck portion, or one axial rib is formed at the center portion in the width direction.

The necks 74, 206 of the pistons 14, 200
Inner surfaces 130, 212 may be partially cylindrical surfaces that protrude outward in the radial direction.

The pistons 14 and 200 may be configured such that the closing member and the engaging portion are integrally formed, and the opening of the bottomed cylindrical member constituting the main part of the head is closed by the closing member. The piston may be divided at a central portion in the axial direction of the head so as to have a side provided with the engaging portion and a side not provided with the engaging portion.

The structure of the swash plate type compressor is not limited to the one described in the above embodiment, but may be another structure. For example, the capacity control valve 90 is not indispensable, and an opening / closing valve that is mechanically opened / closed based on a pressure difference between the pressure of the discharge chamber 24 and the pressure of the swash plate chamber 86 may be provided. Further, instead of or together with the capacity control valve 90,
An electromagnetic control valve similar to the capacity control valve 90 may be provided in the middle of the discharge passage 100, or may be opened and closed mechanically based on the pressure difference between the pressure in the swash plate chamber 86 and the pressure in the suction chamber 22. A valve may be provided.

The present invention can also be applied to a single-headed piston for a fixed displacement swash plate type compressor or a double-headed piston having heads on both sides of an engaging portion with a swash plate.

Although some embodiments of the present invention have been described in detail above, these are merely examples, and the present invention is not limited to the above-mentioned [Problems to be solved by the invention, means for solving problems and effects]. The present invention can be implemented in various modified and improved forms based on the knowledge of those skilled in the art, including the described embodiment.

[Brief description of the drawings]

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

FIG. 2 is a front view showing a piston of the swash plate type compressor.

FIG. 3 is a sectional view taken along line AA of FIG. 2;

FIG. 4 is a side sectional view of a piston for a swash plate type compressor according to another embodiment of the present invention.

[Explanation of symbols]

12: Cylinder bore 14: Single head piston 50:
Swash plate 70, 72: engaging part 74: neck part 76:
Head 78: Shoe 120: Outer peripheral surface 132:
Back surface 140: concave portion 144: convex spherical surface 146:
Sliding surface 200: single head piston 202: engagement part
206: neck 208: head 214: back
220, 222, 224: axial rib 230: recess 232: outer peripheral surface

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Takayuki Kato 2-1-1 Toyota-cho, Kariya-shi, Aichi F-term in Toyota Industries Corporation (reference) 3H003 AA03 AB07 AC03 CB00 3H076 AA06 BB26 BB38 CC12 CC20 CC31

Claims (3)

[Claims] 1. A pair of engaging portions which engage with both surfaces of an outer peripheral portion of a swash plate via respective shoe devices, a neck portion connecting the both engaging portions on an outer peripheral side of the swash plate, and a cylinder bore. A piston for a swash plate type compressor integrally provided with a head to be fitted so as to be able to fit, wherein each of the pair of engagement portions is formed with a concave spherical surface which engages with a convex spherical surface of the shoe device. A piston for a swash plate compressor, wherein a center is located on a side opposite to the neck with respect to a center axis of the head. 2. The swash plate compressor piston according to claim 1, wherein the amount of eccentricity of the sphere from the center axis is 1/30 or more of the diameter of the head. 3. The swash plate type compressor piston according to claim 1, wherein the head is provided only on one side of the pair of engagement portions and the neck portion.