JP2003193968A - Piston and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent performance of a compressor from decreasing by removing adverse affects due to dissolution of an adhesive agent. <P>SOLUTION: In this piston having two support parts for supporting a pair of shoes 50a, 50b, the two support parts composed of bushes 72, 73 formed of a material (iron-based material) having a higher hardness and a higher melting point than those of a piston body 71 formed of an alminum-based material, and the bushes 72, 73 are formed by molding on the piston body 71. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a piston,
In particular, the present invention relates to a piston for a swash plate compressor of an automobile air conditioner and a method for manufacturing the piston.

[0002]

2. Description of the Related Art Conventionally, as a piston of this type, there is one described in Japanese Patent Application Laid-Open No. 5-149246.

This piston is provided so as to face the piston body and the piston body with a gap therebetween.
And two supporting portions. The two support portions support a pair of shoes arranged so as to sandwich the swash plate. The support portion has a concave surface that rotatably supports the convex surface of the shoe.

The piston main body and the two supporting portions are manufactured separately, and the two supporting portions are fitted to predetermined positions of the piston main body and adhered with an adhesive.

[0005]

However, during operation of the compressor, the adhesive may dissolve and mix with the refrigerant gas, which may adversely affect the performance of the compressor. For example, when the refrigerant is carbon dioxide, the adhesive may dissolve when the refrigerant reaches the supercritical temperature.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a swash plate type compressor capable of eliminating the adverse effect caused by the dissolution of the adhesive.

[0007]

In order to solve the above-mentioned problems, the invention according to claim 1 is, in a piston connected to a swash plate via a pair of shoes, provided with a piston main body and the piston main body, 2 for supporting the pair of shoes
One of the two support portions, at least one of the two support portions closer to the top surface of the piston body is formed of a bush made of a material having a hardness and a melting point higher than that of the piston body. The bush is molded in the piston body.

In comparison with the conventional example in which two support parts are fitted in predetermined positions of the piston body and adhered with an adhesive, in the invention according to claim 1, a bush forming the support part is molded in the piston body. Therefore, the adhesive does not melt into the refrigerant gas during operation of the compressor.

According to a second aspect of the present invention, in a piston connected to a swash plate via a pair of shoes, the piston main body and two support portions provided on the piston main body and supporting the pair of shoes are provided. And the two supports are
It is characterized in that it is constituted by a bush formed of a material having a hardness and a melting point higher than that of the piston body, and the bush is molded in the piston body.

In comparison with the conventional example in which two support parts are fitted at predetermined positions of the piston body and adhered with an adhesive, in the invention according to claim 1, a bush forming the support part is molded in the piston body. Therefore, the adhesive does not melt into the refrigerant gas during operation of the compressor.

According to a third aspect of the invention, in the piston of the first or second aspect of the invention, the piston body is made of an aluminum material and the bush is made of an iron material. .

According to a fourth aspect of the present invention, in a method of manufacturing a piston connected to a swash plate via a pair of shoes, the piston body is formed of a material having a hardness and a melting point higher than that of the piston body when the piston body is molded. A first step of casting the bush, a second step of cutting a part of the bush after the first step, and a concave surface for supporting the shoe on the end surface of the bush after the second step And a third step.

After casting the bush into the piston body,
Since the concave surface is formed on the bush, the centering of the piston body and the concave surface (the center axis of the piston body and the center of the concave surface are aligned) becomes easy.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a longitudinal sectional view showing a variable displacement type swash plate compressor having a piston according to an embodiment of the present invention. Carbon dioxide is used as a refrigerant in this variable capacity swash plate compressor.

A rear head 3 is fixed to one end surface of a cylinder block 1 of this variable displacement type swash plate compressor via a valve plate 2, and a front head 4 is fixed to the other end surface thereof.

The cylinder block 1 has a plurality of cylinder bores 6 around the shaft 5 at predetermined intervals in the circumferential direction.
Is provided. A piston 7 is slidably accommodated in each of the cylinder bores 6.

A crank chamber 8 is formed in the front head 4, and a swash plate 10 is accommodated in the crank chamber 8. The swash plate 10 is slidably and tiltably attached to the shaft 5 via a hinge ball 9.

The swash plate 10 includes a pair of hemispherical shoes 50a,
It is connected to the piston 7 via 50b.

The planes f of the shoes 50a and 50b are in contact with the front sliding surface 10a and the rear sliding surface 10b of the swash plate 10, respectively.

A discharge chamber 12 and a suction chamber 13 located around the discharge chamber 12 are formed in the rear head 3. The rear head 3 is provided with a discharge port 3a leading to an inlet of a gas cooler (not shown).

The valve plate 2 has a discharge port (not shown) for connecting the compression chamber 14 of the cylinder bore 6 and the discharge chamber 12, and the compression chamber 14 and the suction chamber 13 of the cylinder bore 6.
And a suction port (not shown) that communicates with each other are provided at predetermined intervals in the circumferential direction. The discharge port is opened and closed by a discharge valve (not shown), and the suction port is opened and closed by a suction valve (not shown).

A thrust flange 40 for transmitting the rotation of the shaft 5 to the swash plate 10 is fixed to the front end of the shaft 5, and the thrust flange 40 is attached to the inner wall surface of the front head 4 via a thrust bearing 33. It is rotatably supported.

The thrust flange 40 and the swash plate 10 are connected via a link mechanism 41.

FIG. 2 is a sectional view of the piston of the variable displacement type swash plate compressor of FIG. 1, FIG. 3 is a conceptual view showing the side surface of the piston before cutting the bush, and FIG. 4 is a concave surface on the end surface of the bush. It is a conceptual diagram which shows the side surface of the piston of the state after forming.

The piston 7 includes a piston body 71 formed of an aluminum material and a pair of shoes 50a, 5
0b is provided. The two support portions are cylindrical bushes 7 formed of a material having a hardness and a melting point higher than that of the piston body 71, for example, an iron-based material.
It is composed of 2,73. The bushes 72, 73 are molded in when the piston body 71 is cast. The bushes 72, 73 are provided with concave surfaces 72a, 73a for rotatably supporting the convex surfaces c of the shoes 50a, 50b. Threads or knurls are formed on the outer peripheral surfaces of the bushes 72, 73.

The piston body 71 has a cylindrical head portion 71a that slides in the cylinder bore 6, a holding portion 71b that is located at one end of the head portion 71a and that holds the bush 73, and a space S in the holding portion 71b. A holding portion 71c that holds the bush 72, and a bridge portion 71d that connects the holding portions 71b and 71c are provided.

Next, a method of manufacturing the piston will be described with reference to FIGS.

First, one bush base material 710 made of an iron-based material is manufactured in advance.

Next, when casting the piston body 71, as shown in FIG.
As shown in FIG. 5, the bush base material 710 is cast (first step). As described above, the bush base material 710 (the bush 7
Since the melting point of the material of (2, 73) is higher than that of the material of the piston body 71, the bush base material 710 maintains the shape before casting.

After that, the exposed bush base material 71
The middle portion of 0 is cut (second step). Bush base material 7
10 is divided into bushes 72, 73.

Finally, as shown in FIG. 4, the bushes 72, 73 facing each other through the space S have concave surfaces 72a,
73a is formed (3rd process).

In this way, the piston 7 is completed.

FIG. 5 is a conceptual view showing a side surface of the piston for explaining another method of manufacturing the piston. This figure shows a state after the bush base material 711 is cast into the piston body 71 '. The piston body 71 'has a shape in which two piston bodies 71 of FIG. 3 are integrally coupled in the axial direction. That is, the piston body 71 ′ has two cylindrical heads 7
1a, a holding portion 71b that is located at one end of the head portion 71a and holds the bush 73, a holding portion 71c that faces the holding portion 71b via a space S, and holds the bush 72, and holding portions 71b, 71c. And a bridge portion 71d for connecting

One bush base material 711 is bridged from the holding portion 71b of the one head portion 71a to the holding portion 71b of the other head portion 71a and penetrates the holding portion 71c.

The manufacturing method of this piston is basically the same as the manufacturing method of FIGS. 3 and 4, but the piston body 71 'and the bush base material 711 are cut into two at an intermediate position of the holding portion 71c. The difference is that the process is added. According to this manufacturing method, the two pistons can be manufactured efficiently.

Next, the operation of this variable displacement type swash plate compressor will be described.

When the rotational power of the vehicle-mounted engine (not shown) is transmitted to the shaft 5, the rotational force of the shaft 5 is transmitted to the swash plate 10 via the thrust flange 40 and the link mechanism 41, and the swash plate 10 rotates.

By rotating the swash plate 10, the shoes 50a, 50
Since b rotates relatively on the sliding surfaces 10a and 10b of the swash plate 10, the rotation of the swash plate 10 is converted into a linear reciprocating motion of the piston 7.

The piston 7 reciprocates in the cylinder bore 6, and as a result, the volume of the compression chamber 14 in the cylinder bore 6 changes. Due to this volume change, the suction, compression and discharge of the refrigerant gas are sequentially carried out, and the swash plate 10 moves. Refrigerant gas having a volume corresponding to the tilt angle is discharged.

At the time of suction, a low-pressure refrigerant gas is sucked from the suction chamber 13 into the compression chamber 14 in the cylinder bore 6 through the suction port, and at the time of discharging, a high-pressure refrigerant gas from the compression chamber 14 to the discharge chamber 12 through the discharge port. Gas is discharged.

As described above, the piston 7 linearly reciprocates in the cylinder due to the rotation of the swash plate 10. At this time, the plane f of the shoes 50a and 50b is the sliding surface 10a of the swash plate 10.
10b slides relative to each other, and the convex surfaces c of the shoes 50a and 50b
Relatively rolls on the concave surfaces 72a and 73a of the bushes 72 and 73.

Since carbon dioxide is used as the refrigerant, the load of the piston 7 acting on the swash plate 10 during compression of the refrigerant (compression reaction force of the refrigerant) is 20 to 30% larger than that when CFC is used as the refrigerant. . Therefore, a large load acts on the compression-side bush 72, but the bush 7
Since 2 is made of an iron-based material, the concave surface 72a is hard to wear.

Further, the pressure and temperature in the crank chamber 8 are also higher than when CFC is used as the refrigerant, but the bushes 72, 73 are molded in when the piston body 71 is cast, and after the piston body 71 is cast the pistons Since the bushes 72 and 73 are not fixed to the main body 71 with an adhesive, the adhesive is dissolved during the operation of the compressor and the bush 7
The 2, 73 will not come off from the piston body 71.

According to this embodiment, since the bushes 72, 73 forming the supporting portion are not fixed to the piston body 71 with the adhesive, the adhesive is not melted and mixed with the refrigerant gas, and the compressor It is possible to prevent performance deterioration.

In addition, the piston 72 has a bush 72,
After casting 73, the bushes 72, 73 have a concave surface 72
a and 73a are formed, the piston body 71 and the concave surface 7
The centering with 2a, 73a (the center axis of the piston body 71 and the centers of the concave surfaces 72a, 73a are aligned) becomes easy. When the piston body 71 is cast, the bushes 72, 73 that form the support portion are inserted and integrally molded. Therefore, the manufacturing process of fitting and bonding the support portion after the piston body 71 is manufactured is unnecessary, Work becomes simple.

Further, the bushes 72, 73 whose supporting portions are iron-based
Since the outer diameter of the shoes 50a, 50b is increased, the shoes 50a, 50b and the concave surfaces 72a, 73a are formed.
Even if the contact area with the piston 7 is not increased, the abrasion of the piston 7 can be suppressed, and it is not necessary to increase the amount of protrusion of the bridge portion 71d to the outside in the radial direction. Therefore, it is possible to prevent the compressor from increasing in size. The ratio of the iron-based bushes 72, 73 to the entire piston is smaller than that of the piston formed of an iron-based material, and the weight reduction of the piston 7 is not impaired.

Further, since the threads or knurls are formed on the outer peripheral surfaces of the bushes 72, 73 (bush base material), after the bushes 72, 73 are cast into the piston main body 71, the bushes 72, 73 are replaced by pistons. It is difficult to separate from the main body 71. The shapes of the outer peripheral surfaces of the bushes 72, 73 are not limited to the threads, and any surface may be used so that the bushes 72, 73 do not easily come off.

In this embodiment, the two supporting portions are constituted by the bushes 72 and 73, but only one supporting portion, for example, the supporting portion on the compression side (the supporting portion closer to the compression chamber 14) is bushed. It may be configured by 72.

FIG. 6 is a sectional view of another piston according to another embodiment of the present invention.

In the above-mentioned embodiment, the so-called single-headed piston for the variable displacement type swash plate compressor is described, but in this embodiment, the so-called double-headed piston for the fixed displacement type swash plate compressor is described.

The aluminum type piston body 81 is
Two cylindrical heads 81a and 81b and two heads 81
and a bridge portion 81c that connects a and 81b. Iron-based bushes 82 and 83 are embedded in the end portions of the facing head portions 81a and 81b on the bridge portion side, respectively. The bushes 82, 83 are inserted when the piston body 81 is cast.

To manufacture the piston shown in FIG. 6, first, the bush base material is cast during casting of the piston body 81, and then the intermediate portion of the bush base material is cut to form the bush base material into the bush 82, 83, and finally, a concave surface 82 is formed on each of the bushes 82, 83 facing each other through the space S.
a and 83a are formed.

According to this embodiment, the same effect as that of the above-mentioned embodiment can be obtained.

[0055]

As described above, according to the piston of the first, second or third aspect of the present invention, it is possible to prevent the deterioration of the performance of the compressor due to the dissolution of the adhesive.

According to the method of manufacturing a piston of the fourth aspect of the present invention, since the concave surface is formed in the bush after the bush is cast in the piston main body, the piston main body and the concave surface can be easily centered and extended. In addition, the manufacture of the piston is simplified.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a variable displacement swash plate compressor including a piston according to an embodiment of the present invention.

FIG. 2 is a sectional view of a piston of the variable displacement swash plate compressor of FIG.

FIG. 3 is a conceptual diagram showing a side surface of the piston before cutting the bush.

FIG. 4 is a conceptual diagram showing a side surface of the piston in a state after forming a concave surface on the end surface of the bush.

FIG. 5 is a conceptual diagram showing a side surface of a piston for explaining another method for manufacturing the piston.

FIG. 6 is a sectional view of another piston according to another embodiment of the present invention.

[Explanation of symbols]

7 pistons 10 swash plate 10a, 10b sliding surface 50a, 50b shoes 71,81 Piston body 71a, 81a, 81b Head 71b, 71c, 81c, 81d Holding part 71d, 81e Bridge part 72, 73, 82, 83 Bush 72a, 73a, 82a, 83a concave surface S void

Claims (4)

[Claims] 1. A piston connected to a swash plate via a pair of shoes, comprising: a piston body, and two support portions provided on the piston body and supporting the pair of shoes. Of the parts, at least the support portion closer to the top surface of the piston body is composed of a bush formed of a material having a hardness and a melting point higher than that of the piston body, and the bush is molded in the piston body. A piston characterized by being present. 2. A piston connected to a swash plate via a pair of shoes, comprising: a piston main body, and two support portions provided on the piston main body and supporting the pair of shoes. The piston is characterized in that the portion is formed of a bush formed of a material having a hardness and a melting point higher than that of the piston body, and the bush is molded in the piston body. 3. The piston according to claim 1, wherein the piston body is made of an aluminum material and the bush is made of an iron material. 4. A method of manufacturing a piston connected to a swash plate via a pair of shoes, wherein a bush formed of a material having a hardness and a melting point higher than that of the piston body is cast during molding of the piston body.
And a second step of cutting a part of the bush after the first step
A method for manufacturing a piston, comprising: a step; and, after the second step, a third step of forming a concave surface for supporting the shoe on an end surface of the bush.