JPH0783165A - Sliding structure of swash plate type compressor - Google Patents

Abstract

PURPOSE:To reduce the weight and the cost without deteriorating the sliding characteristics. CONSTITUTION:Shoes 19, 20 are formed of bearing steel, and the amorphous hard carbon film is coated on the sliding surface on the swash plate side of the shoes 19, 20. The coefficient of friction of the amorphous hard carbon film with the aluminum material is extremely small, and the amorphous hard carbon film is difficult to cause the seizure or abnormal abrasion when the alternative coolant is used. The forming temperature of the amorphous hard carbon film is low, i.e., about 160 deg.C, and the post-processing after forming the film is unnecessary, and the work can simply be done.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sliding structure of a swash plate type compressor, and more particularly to a sliding structure of a swash plate type compressor which can be reduced in weight and cost.

[0002]

2. Description of the Related Art In recent years, the weight reduction of automobile parts has been promoted, and the material of refrigerant compressors has been changed from iron-based alloys to aluminum-based alloys. However, in the refrigerant compressor, the aluminum-based material is inferior to the iron-based material in terms of wear resistance, and therefore, the iron-based material is partially used or the following surface treatment is performed.

As a first conventional technique, for example, the surface of a swash plate or shoe made of an aluminum material is covered with an anodized film, and a plating layer of lead, indium, tin or the like is further formed on the surface of the anodized film. Some are formed (JP-A-4-180599).

As a second conventional technique, there is one in which the surface of a swash plate made of a high silicon aluminum alloy is covered with an anodized film, and a solid lubricant layer such as molybdenum disulfide is formed on the surface of the anodized film ( JP-A-5-10513).

As a third prior art, there is one in which a bearing steel is used for the shoe and a hard ion plating film such as CrN is formed on the surface thereof (Japanese Patent Laid-Open No. 1-130074).

[0006]

However, the above surface treatment causes deterioration of sliding characteristics such as seizure and abnormal wear due to deterioration of sliding environment due to change to alternative refrigerant (for example, HFC-134a). was there.

Further, when the surface treatment is performed on the swash plate or both the swash plate and the shoe, there is a problem that the cost increases because the area to be surface treated is large.

Furthermore, in the case where a hard ion plating film is formed on the surface of the bearing steel shoe, the film forming temperature (40
Since 0 to 600 ° C) exceeds the tempering temperature (180 ° C) of the bearing steel, quenching and tempering operations must be performed after the film formation, which is a problem that the work is complicated.

It is also conceivable to form the shoe with a high silicon aluminum alloy in order to further reduce the weight, but in this case, it is necessary to coat the shoe with a coating having high strength and high wear resistance.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a sliding structure for a swash plate compressor which can reduce the weight and cost without deteriorating the sliding characteristics. Is.

[0011]

In order to solve the above problems, a sliding structure of a swash plate type compressor according to a first aspect of the present invention comprises a cylinder block having a plurality of cylinder bores and a rotary shaft in the cylinder block. The rotating cylinder includes a rotating swash plate, a piston slidably accommodated in the cylinder bore, and a shoe interposed between the piston and the swash plate. In a swash plate compressor that reciprocates inside, at least the sliding surface of the shoe is coated with an amorphous hard carbon film.

Further, in the sliding structure of the swash plate type compressor according to a second aspect of the present invention, the shoe is formed of bearing steel.

Further, in the sliding structure of the swash plate type compressor according to the third aspect of the present invention, the shoe is made of a high silicon aluminum alloy.

Further, in the sliding structure of the swash plate type compressor according to a fourth aspect of the present invention, the amorphous hard carbon film has a thickness of 2 to 20.
μm.

[0015]

[Function] Although the sliding surface of the shoe is coated with an amorphous hard carbon film, the amorphous hard carbon film has a remarkably low friction coefficient with an aluminum-based material, so seizure and abnormal wear occur even when using an alternative refrigerant. Is unlikely to occur. Further, since the film forming temperature of the amorphous hard carbon film is as low as about 160 ° C., post-treatment after film formation is unnecessary, and the work is easy.

By forming the shoe with a high silicon aluminum alloy and coating the sliding surface with an amorphous hard carbon film, it is possible to reduce the wear resistance and the friction loss as well as the weight reduction.

Further, the film thickness is preferably 2 to 20 μm in order to prevent image sticking due to peeling of the amorphous hard carbon film. As a result, it is possible to prevent the amorphous hard carbon film from peeling off due to the dropping or protrusion of the primary crystal silicon of the counterpart material.

[0018]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a vertical sectional view of a swash plate compressor having a sliding structure according to an embodiment of the present invention.

The front cylinder block 1 and the rear cylinder block 2 are joined to each other so as to face each other.
A front head 4 is fixed to one end of the joined cylinder blocks 1 and 2 via a valve seat 3, and a rear head 6 is fixed to the other end thereof via a valve seat 5.

A drive shaft 7 is arranged at the center of the cylinder blocks 1 and 2, and a swash plate 8 is fixed to the drive shaft 7. The drive shaft 7 and the swash plate 8 are rotatably supported by bearings 9 and 10. Has been done. The swash plate 8 is made of aluminum or a high aluminum alloy, and is housed in a swash plate chamber 37 formed at the joint between the cylinder blocks 1 and 2.

The cylinder blocks 1 and 2 are provided with three cylinder bores 11. The cylinder bores 11 are parallel to the drive shaft 7 and are arranged at predetermined intervals on a circle centered on the drive shaft 7. A piston 12 is slidably accommodated in the cylinder bore 11.

The piston 12 has cylindrical portions 12a and 12b.
And a bridge portion 12c that integrally connects the cylindrical portions 12a and 12b. Pistons 1 facing each other
In the inner wall surfaces 31 and 32 of the two cylindrical portions 12a and 12b, concave surface portions 33 and 34 are formed, respectively, and in the space formed by the inner wall surfaces 31 and 32 of the cylindrical portions 12a and 12b and the inner wall surface 35 of the bridge portion 12c. A part of the swash plate 8 has entered (see FIG. 1). The swash plate 8 is rotatably sandwiched by shoes 19 and 20 slidably accommodated in the concave portions 33 and 34.

The shoes 19, 20 are formed of bearing steel (SUJ2) in a substantially hemispherical shape, and the swash plate side sliding surfaces 19a, 20a of the shoes 19, 20 are coated with an amorphous hard carbon film. The amorphous hard carbon film contains silicon or silicon and nitrogen, and is synthesized by ion plating, plasma CVD or the like. Film formation by high frequency plasma CVD is preferable because the film formation temperature can be lowered. The thickness of the amorphous hard carbon film is 2 to 20 μm.

The thickness of the amorphous hard carbon film containing silicon is set in the range of 4 to 15 μm from the viewpoint that it is difficult to wear and peel off even if foreign matter enters between the sliding surfaces. 4μ
If it is less than m, sufficient abrasion resistance cannot be obtained, and if it exceeds 15 μm, peeling easily occurs. Similarly, the thickness of the amorphous hard carbon film containing nitrogen and silicon is in the range of 2 to 20 μm from the viewpoint that it is difficult to wear and peel off even if foreign matter enters between the sliding surfaces. . If it is less than 2 μm, sufficient abrasion resistance cannot be obtained, and if it exceeds 20 μm, peeling easily occurs.

The valve seats 3 and 5 have suction ports 3a and 5a.
And discharge ports 3b, 5b are provided, and the suction port 3a,
The compression chambers 21 and 22 communicate with the suction chamber 23 via 5a, and the compression chambers 21 and 22 communicate with the discharge chamber 24 via discharge ports 3b and 5b. A suction valve 2 is provided at the suction ports 3a and 5a.
5, 26, and discharge valves 27, 28 are attached to the discharge ports 3b, 5b, respectively. The deformation amount of the discharge valves 27 and 28 is regulated by the valve retainers 29 and 30.

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

When the drive shaft 7 rotates, the swash plate 8 also rotates integrally. The rotation of the swash plate 8 causes the piston 12 to reciprocate. When the piston 12 is located at the bottom dead center on the compression chamber 21 side, if the swash plate 8 makes a 1/2 turn from this position, the piston 12 moves to the position shown in FIG. 1 and the suction stroke is completed on the compression chamber 21 side. However, the compression stroke is completed on the compression chamber 22 side.
When the swash plate 8 further rotates 1/2 from this state, the suction stroke is completed on the compression chamber 22 side, and the compression stroke is completed on the compression chamber 21 side.

In the intake stroke, the intake valves 25 and 26 are opened,
From the suction chamber 23 to the compression chamber 21, through the suction ports 3a and 5a.
Refrigerant gas flows into 22. In the compression stroke, the compression chamber 21,
The refrigerant gas compressed in 22 opens the discharge valves 27, 28, and the refrigerant gas is discharged from the compression chambers 21, 22 to the discharge chamber 24 through the discharge ports 3b, 5b.

According to the swash plate type compressor of this embodiment, since the swash plate side sliding surfaces 19a, 20a of the shoes 19, 20 are coated with the amorphous hard carbon film, the amorphous hard carbon film is formed. Since the temperature is as low as about 160 ° C., post-treatment after film formation is unnecessary, the work is simple, and the area to be surface-treated is small, so that the cost can be reduced. Further, since the amorphous hard carbon film has a remarkably low friction coefficient with aluminum (preferably high silicon aluminum alloy), it is unlikely to cause seizure or abnormal wear even when the alternative refrigerant is used.

In this example, the high-pressure atmosphere wear tester shown in FIG. 2 was used, in an alternative refrigerant (HFC134a + refrigerator oil),
The surface pressure was increased stepwise for the four combinations described below, and the friction coefficient was obtained from the surface pressure and the wear torque.

Test conditions: constant friction load time 2 min, pressure-up surface pressure 3,2 MPa / step, pressure-up time 1 min, rotation speed / peripheral speed 1000 rpm, 0.84 m / sec As shown in FIG. 3, powder extruded high silicon aluminum Amorphous hard carbon film (film thickness: 4 μm) on alloy (ASCM) and bearing steel (SUJ2) Film forming condition: Raw material gas = Ethylene + TM
S reaction pressure = 0.53Pa input power = 150W) and particle size 10 ~
From the abrasion test results with the high silicon aluminum alloy (A390) containing 30 μm of primary crystal silicon, a very low friction coefficient (about 0.03) was obtained only by coating the high silicon aluminum alloy (ASCM) on one side. In addition, the sliding surface after the test showed no signs of damage on both the amorphous hard carbon film side and the A390 side, and the wear amount was beyond the detection limit (0.00
It was 1 g or less).

On the other hand, in a wear test of a high silicon aluminum alloy (A390) containing primary silicon having a grain size of 10 to 30 μm coated with MoS2 and a bearing steel (SUJ2) coated with CrN, a low surface area was observed. From the pressure side, a higher friction coefficient (about 0.04) was obtained than the amorphous hard carbon film. Furthermore, when the sliding surface after the test was observed, partial peeling of MoS2 was observed. At the peripheral speed expected from an actual machine (2 to 20 m / sec), it is considered that when the surface pressure becomes high, it will wear out and cause seizure.

Also, bearing steel (SUJ2) coated with CrN and high silicon aluminum alloy (A390) containing primary crystal silicon with a grain size of 10 to 30 μm without surface treatment.
In the abrasion test with and, seizure occurs at the stage of low surface pressure. Therefore, although the seizure resistance is improved by coating with MoS2, it is considered that the seizure of MoS2 leads to seizure when sliding for a long time at a high surface pressure due to the low wear resistance of MoS2.

From the above results, the amorphous hard carbon film was used as the shoe 1.
By coating 9 and 20, seizure resistance,
Not only the wear resistance is improved, but also the swash plate does not need to be surface-treated, resulting in cost reduction, and further, friction loss is reduced due to reduction of friction coefficient.

In the above-described embodiment, the case where the shoes 19 and 20 are made of bearing steel has been described, but instead of this, the shoes 19 and 20 are made of high silicon aluminum alloy,
The amorphous hard carbon film is used as the sliding surface 19a, 20 of the shoe on the swash plate side.
By covering the sliding surface a and the piston side, weight reduction, wear resistance, and reduction of friction cloth can be achieved.

FIG. 4 is a vertical sectional view of a swash plate type compressor having a sliding structure according to another embodiment of the present invention. In the above-described embodiment, the case where the shoes 19 and 20 are formed of bearing steel into a substantially hemispherical shape has been described, but instead of this, as shown in FIG. 4, the shoes 49 and 50 are formed of high carbon steel. The ball-shaped sliding surfaces 51, 52 of the shoe plates 49b, 50b and the plate-side sliding of the swash plate 8 are composed of spherical balls 49a, 50a and plate-shaped shoe plates 49b, 50b made of high silicon aluminum alloy. The moving surfaces 8a and 8b may be covered with an amorphous hard carbon film.

[0038]

As described above, according to the sliding structure of the swash plate type compressor of the present invention, the post-treatment after film formation is unnecessary, the work is simple, and the area to be surface-treated is small. Therefore, the cost can be reduced. Further, since the amorphous hard carbon film has a remarkably low coefficient of friction with an aluminum-based material, seizure and abnormal wear are unlikely to occur even when an alternative refrigerant is used.

Further, by forming the shoe with a high silicon aluminum alloy and coating the sliding surface with an amorphous hard carbon film, it is possible to achieve not only weight reduction but also wear resistance and reduction of friction loss.

Furthermore, the thickness of the amorphous hard carbon film is 2 to 2
By setting the thickness to 0 μm, it is possible to prevent the primary crystal silicon of the mating material from falling off or protruding.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a swash plate compressor having a sliding structure according to an embodiment of the present invention.

FIG. 2 is a schematic view of a high pressure atmosphere wear tester.

FIG. 3 is a curve diagram showing a relationship between a friction coefficient and a surface pressure.

FIG. 4 is an enlarged sectional view showing a sliding structure of a swash plate compressor according to another embodiment of the present invention.

[Explanation of symbols]

 1, 2 Cylinder block 7 Drive shaft 8 Swash plate 11 Cylinder bore 12 Piston 19,20 Shoe 19a, 20b Shoe plate sliding surface of shoe

Claims (4)

[Claims] 1. A cylinder block having a plurality of cylinder bores, a swash plate that rotates by a rotary shaft in the cylinder block, a piston slidably accommodated in the cylinder bore, and a space between the piston and the swash plate. In a sliding structure of a swash plate compressor in which the piston reciprocates in the cylinder bore according to the rotation of the swash plate, amorphous hard carbon is present on at least the sliding surface of the shoe. A sliding structure for a swash plate type compressor characterized by being coated with a film. 2. A sliding structure for a swash plate compressor according to claim 1, wherein the shoe is formed of bearing steel. 3. The sliding structure for a swash plate compressor according to claim 1, wherein the shoe is formed of a high silicon aluminum alloy. 4. The amorphous hard carbon film has a thickness of 2 to 20.
The sliding structure of the swash plate compressor according to claim 1, wherein the sliding structure is μm.