SWASH PLATE TYPE COMPRESSOR

TECHNICAL FIELD

The present invention relates to a swash plate type compressor used in an air conditioner for vehicle.

BACKGROUND ART

The swash plate type compressor includes a fixed capacity swash plate type compressor in which a swash plate is directly fixed to a drive shaft rotatably disposed in a housing with tilt, and a variable capacity swash plate type compressor in which a swash plate is attached to the drive shaft through a connecting member to make tilt angle variable and slidable. In both of the swash plate type compressors, the swash plate slide on a shoe and a rotation of the swash plate is converted into a reciprocal movement of a piston through the shoe to compress and expand a refrigerant.

In the swash plate type compressors, as the swash plate slides along the shoe in an early stage of the operation before a lubricant contained in the refrigerant reaches the sliding portion, the sliding portion is made dry lubrication state without lubricant, and adhesion tends to occur. So, a lubrication film is provided on the sliding portion of the swash plate against a shoe for preventing adhesion in general. For example, Patent Document 1 discloses a swash plate in which an intermediate layer composed of tin, copper or metal phosphate is first formed on a sliding surface of a swash plate substrate, followed by forming a lubrication film composed of a thermosetting resin such as polyamideimide resin or polyimide resin and a solid lubricant such as molybdenum disulfide or graphite on the intermediate layer. Patent Document 2 discloses a swash plate in which an intermediate layer made of a heat resistant resin such as polyamideimide resin or a polyimide resin is provided on a sliding surface of a swash plate substrate, followed by forming a lubrication film composed of a solid lubricant such as polytetrafluoroethylene, molybdenum disulfide or graphite, and a heat resistant resin such as polyamideimide resin or a polyimide resin on the intermediate layer. Patent Document 3 discloses a swash plate in which a lubrication film composed of a solid lubricant such as polytetrafluoroethylene, molybdenum disulfide or graphite, and polyamideimide resin having a grass transition temperature of 270° C. or more is provided on a sliding surface of a smash plate substrate. Patent Document 4 discloses a swash plate in which a lubrication film composed of polyamideimide resin or a polyimide resin having tensile strength and elongation at 25° C. falling in specific ranges, and a solid lubricant such as polytetrafluoroethylene or graphite is provided on a sliding surface of a swash plate substrate.

Patent Document 1: Japanese Patent Laid-Open No. 11-13638

Patent Document 2: Japanese Patent Laid-Open No. 2005-146366

Patent Document 3: Japanese Patent Laid-Open No. 2005-30376

Patent Document 4: Japanese Patent Laid-Open No. 2009-62935

SUMMARY OF THE INVENTION
Problems to be Solved

However, the methods including formation of an intermediate layer disclosed in Patent Documents 1 and 2 has a drawback of increased manufacturing cost results from the intermediate layer. The methods forming a single layer of a lubrication film disclosed in Patent Documents 3 and 4 exclude the drawback of the increased manufacturing cost results from the intermediate layer, and the adhesion resistance may be improved up to a considerable level. However, these methods are not sufficient to achieve a strict adhesion resistance required in further developed swash plate type compressor, and further improvement in adhesion resistance is required.

The present invention is accomplished in consideration of the situation of the conventional technologies, and object of the present invention is to provide a swash plate type compressor improved in the adhesion resistance of the swash plate.

Means to Solve the Problem

To solve the problem described above, the swash plate type compressor according to the present invention including a drive shaft rotatably disposed in a housing, a swash plate fixed directly to the drive shaft with an inclination angle or attached to the drive shaft via a connecting member with a variable inclination-angle and slidable and rotate integrally with the drive shaft, a shoe disposed between the swash plate and a piston, and the piston reciprocating in a cylinder bore; and the swash plate type compressor converts rotational movement of the swash plate into reciprocating movement of the piston to compress and expand a refrigerant; wherein a lubrication film made of a cured coating film composed of a binder resin containing 100 parts by weight of polyamideimide resin and 2 to 18 parts by weight of bisphenol-A epoxy resin and a solid lubricant containing polytetrafluoroethylene and graphite is provided on a surface of a swash plate substrate.

Advantages of the Invention

According to the present invention, the adhesion resistance of a swash plate substrate provided at sliding portion of the swash plate against a shoe is greatly improved by the increased resin density caused by improved film strength as compared with a case where just polyamideimide resin is used as a binder resin because a resin composition containing 100 parts by weight of polyamideimide resin and 2 to 18 parts by weight of bisphenol-A epoxy resin is used as a binder resin.

BRIEF DESCRIPTION OF DRAWINGS

[FIG. 1] FIG. 1 is a cross-sectional view of a swash plate type compressor.

[FIG. 2] FIG. 2 is a perspective view of an assembled drive shaft, a rotor, a swash plate and a linking arm disposed in the swash plate type compressor.

[FIG. 3] FIG. 3 is a partial enlarged view of a sliding portion of the swash plate against a shoe.

PREFERRED EMBODIMENTS OF THE INVENTION

The embodiment of a swash plate type compressor according to the present invention will be described.

As shown in FIG. 1, the swash plate type compressor 100 is a variable capacity swash plate type compressor. The compressor 100 includes the drive shaft 1, the rotor 2 fixed on the drive shaft 1, and the swash plate 3 supported on the drive shaft 1 with the variable inclination-angle and slidable manner. The swash plate 3 includes the swash plate substrate 3a and the swash plate boss 3b, and the swash plate substrate 3a is fixed on the swash plate boss 3b with the rivet. The piston 5 moored to the swash plate 3 via a pair of shoes 4 sandwiching the peripheral portion of the swash plate 3 is slidably fit in the cylinder bore 6a formed in the cylinder block 6. The drive shaft 1, the rotor 2 and the swash plate 3 are housed in the front housing 7. An outlet chamber and the inlet chamber are provided in the cylinder head 8. The cylinder block 6 and the cylinder head 8 sandwich the valve plate 9. The cylinder block 6, the front housing 7, the cylinder head 8 and the valve plate 9 are integrally assembled. The drive shaft 1 is rotatably supported by the front housing 7 and the cylinder block 6.

As shown in FIG. 1 and FIG. 2, circular through-holes 2b and 2c are formed in the pair of rotor arms 2a extending from the rotor 2 toward the swash plate 3. The circular through-holes 2b and 2c coaxially extend perpendicularly to a plane formed by the central axis X of the drive shaft 1 and the top dead point Dp of the swash plate 3. The circular through-hole 3d is formed in the single swash plate arm 3c extending from the swash plate 3 toward the rotor 2. The circular through-hole 3d extends perpendicularly to the plane formed by the central axis X of the drive shaft 1 and the top dead point Dp of the swash plate 3. The linking arm 10 linking the rotor arms 2a and the swash plate arm 3c is disposed. The circular through-hole 10a is formed at one end portion of the linking arm 10, and circular through-holes 10b and 10c are formed in forked portions at the other end of the linking arm 10. The pair of rotor arms 2a sandwich one end portion of the linking arm 10, and the forked portions at the other end of the linking arm 10 sandwich the swash plate arm 3c.

The pin 11 is interlocked in the circular through-hole 3d with its both ends slidable in the circular through-holes 10b and 10c. The pin 12 is interlocked in the circular through-hole 10a with its both ends slidable in the circular through-holes 2b and 2c. The link mechanism 13 is constituted by the rotor arm 2a, the swash plate arm 3c, the linking arm 10 and the pins 11 and 12. The link mechanism 13 links the rotor 2 and the swash plate 3 with each other while making the inclination angle of the swash plate 3 variable and not rotatable around the drive shaft 1.

In the swash plate type compressor 100, an external driving source rotates the drive shaft 1, rotation of the drive shaft 1 rotates the swash plate 3, and rotation of the swash plate 3 reciprocates the piston 5 via the shoes 4. A refrigerant gas reflows from the external refrigerant system and flows into the compressor 100 through the inlet port into the inlet chamber 14. Then, the refrigerant gas is introduced into the cylinder bore 6a through the inlet hole and the inlet valve formed in the valve plate 9, followed by being compressed under pressure by the piston 5. After that, the refrigerant gas is discharged through the outlet hole and the outlet valve formed in the valve plate 9 into the outlet chamber to return to the external refrigerant system via the outlet port. Note that the inclination angle of the swash plate 3 is controlled by a control system not shown by controlling a pressure difference between the pressures in the inlet chamber 14 and the crank chamber 15 by a pressure difference control valve in accordance with the thermal load on the air conditioner.

As shown in FIG. 3, the lubrication film 3e as the cured lubricous coating paint is formed on a sliding portion of the swash plate substrate 3a against each shoe 4. Regarding formation of the lubrication film 3e, the lubricous coating paint having composition for lubrication film composed of a binder resin containing 100% by weight of polyamideimide resin and 2 to 18% by weight of bisphenol-A epoxy resin and a solid lubricant including polytetrafluoroethylene (hereinafter referred to as PTFE) and graphite is first coated on a surface of the swash plate substrate 3a to be a sliding portion, in the amount making a film thickness after drying 35 to 70 micron-meters, followed by curing at 180 to 270° C. for 15 to 80 minutes. Then, the cured film is ground by a grinder to adjust surface roughness in Ra to be 0.6 to 1.6 micron-meters. Although an iron-based, copper-based or aluminum-based substrate may be used as the swash plate substrate 3a, an iron-based substrate is used in general.

The maximum adhesion resistance (time for adhesion) of the swash plate 3 provided with the lubrication film 3e relates to the content of bisphenol-A epoxy resin against polyamideimide resin. The adhesion resistance is the maximum if bisphenol-A epoxy resin content is approximately 5 parts by weight against 100 parts by weight of polyamideimide resin. Bisphenol-A epoxy resin content of less than 2 parts by weight is not so different from the composition excluding bisphenol-A epoxy resin. Further, bisphenol-A epoxy resin content of exceeding 18 parts by weight makes the adhesion resistance equivalent to or less than the composition excluding bisphenol-A epoxy resin.

The swash plate substrate 3a is subjected to a degreasing treatment before coating the lubricous coating paint. After the degreasing treatment, the swash plate substrate 3a is preferable to be subjected to a roughening treatment by shot blasting to adjust the surface roughness of the substrate in Rzjis to be 8.0 to 13.0 micron-meters. Maximum adhesion resistance (load at adhesion) has a relationship if the surface roughness of the swash plate substrate is in the range. If the surface roughness in Rzjis is less than 8.0 micron-meters, the load at adhesion decrease, and if the surface roughness in Rzjis exceeds 13.0 micron-meters, the lubrication film 3e may be worn away in a projected portion of the rough surface to expose the base metal of the swash plate substrate 3a, and makes it tends to adhere.

Regarding the solid lubricant used, preferable average particle size of PTFE is 1 to 15 micron-meters, and preferable average particle size of graphite is 1 to 10 micron-meters. PTFE lowers the friction coefficient of the lubrication film under high-speed sliding conditions to prevent wear and ablation of the film surface. Although, the friction coefficient is made low with the increased content of PTFE, too large content of PTFE decreases the shear strength of the lubrication film to easily generate inter-layer separation. So, content of PTFE is preferable to be 40 to 70 parts by weight and is more preferable to be 50 to 60 parts by weight against 100 parts by weight of the binder resin. Although graphite increases the load resistance of the lubrication film, increased content of graphite increases the friction coefficient. So, the content of graphite is preferable to be 1 to 20 parts by weight and is more preferable to be 5 to 15 parts by weight against 100 parts by weight of the binder resin.

The lubricous coating paint may be prepared by kneading to disperse a composition including polyamideimide resin, bisphenol-A epoxy resin, PTFE and graphite in prescribed ratio in a proper amount of organic solvent (such as a mixed solvent of N-methylolpyrrolidone as a main component and xylene) by using a ball mill, a bead mill, a triple roller mill or a planetary mill. As the organic solvent, a high-boiling point polar solvent good in dissolubility of the binder resin, such as N-methylpyrrolidone, 2-pyrrolidone, methylisopyrrolidone, dimethylformamide, or dimethylacetamide; an aromatic solvent such as toluene or xylene; a ketone such as acetone or methyl ethyl ketone; an ester such as methyl acetate or ethyl acetate; or a mixed solvent of any of these is used in general.

EXAMPLES

Following examinations were carried out to investigate the influence of the content of bisphenol-A epoxy resin in the binder resin on the adhesion resistance. The lubricous coating paint having compositions shown in Table 1 were prepared as the composition for film formation. Further, the swash plate substrates made of steel were subjected to the degreasing treatment, followed by shot blasting for roughening the surface and adjust the surface roughness in Rzjis to be 9.0 micron-meters. The lubricous coating paints were applied on the surface of the swash plate substrates to make the dried film thickness of 60 micron-meters followed by by heating at 230° C. for 30 minutes for curing. Then, the cured coating films were ground by a grinder to smoothen the surface to finish a lubrication films having surface roughness in Ra of 0.8 micron-meters. The average particle size of a used PTFE particle was 10 micron-meters, and the average particle size of graphite was 4 to 5 micron-meters.

Each of the swash plate substrates provided with the lubrication films were subjected to the sliding performance test under the test conditions described below:

Test condition 1

Test machine: Rotary friction wear test machine

Lubrication: Dry lubrication

Load: 8.8 MPa

Speed: 2000 rpm

Counter shaft: SUJ2 (in the shoe shape)

The test results are as follows:

Composition
Test result

(parts by weight)
Time for Adhesion

PAI
BPER
PTFE
Gr
(sec)

Example
1
100
2
50
5
296

2
100
5
50
5
379

3
100
10
50
5
364

4
100
15
50
5
323

5
100
18
50
5
298

6
100
5
30
5
295

7
100
5
40
5
356

8
100
5
55
5
375

9
100
5
60
5
385

10
100
5
70
5
337

11
100
5
80
5
308

12
100
5
55
0
292

13
100
5
55
1
322

14
100
5
55
10
408

15
100
5
55
15
390

16
100
5
55
20
355

17
100
5
55
25
295

Comparative
1
100
0
50
5
270

Example
2
100
1
50
5
273

3
100
20
50
5
268

PAI: Polyamideimide resin HPC-6000 (manufactured by Hitachi Chemical Company, Ltd.)

BPER: Bisphenol-A epoxy resin EPICLON 850 (liquid at 25° C.) (manufactured by DIC Corporation)

PTFE: Polytetrafluoroethylene KTL-10N (manufactured by KITAMURA LIMITED)

Gr: Graphite CSSP (manufactured by Nippon Graphite Industries, Co., Ltd.)

In the test results shown above, the time for adhesion is the longest if the content of bisphenol-A epoxy resin is 5 parts by weight against 100 parts by weight of polyamideimide resin, and if the content is 2 to 18 parts by weight, the time for adhesion is longer than the composition excluding bisphenol-A epoxy resin. If the content is less than 2 parts by weight or exceeding 18 parts by weight, however, the time for adhesion is equivalent to or less than the composition excluding bisphenol-A epoxy resin. In contrast, if the content of PTFE is 50 to 60 parts by weight and content of graphite is 5 to 15 parts by weight against 100 parts by weight of polyamideimide resin, good adhesion resistance is achieved. If the content of PTFE is less than 40 parts by weight or exceeding 70 parts by weight, or if the content of graphite is less than 1 part by weight or exceeding 20 parts by weight, the time for adhesion is short.

Next, the following examination was carried out to investigate the influence of the surface roughness of a swash plate substrate on the load at adhesion. A plurality of swash plate substrates whose surface roughness were adjusted to as shown in Table 2 by shot blasting were prepared. A lubrication film was formed on these swash plate substrates by the same manner as in the examples described above. A lubricous coating paint having a composition of 100 parts by weight of polyamideimide resin, 5 parts by weight of bisphenol-A epoxy resin, 50 parts by weight of PTFE and 5 parts by weight of graphite was used.

The swash plate substrates provided with the lubrication films were subjected to the sliding performance test under the test conditions described below:

Test conditions 2

Test machine: Rotary friction abrasion test machine

Lubrication: Semi-dry lubrication (a refrigerating oil was supplied onto a sliding surface at 0.4 g/100 sec)

Load: 0.2 MPa/60 sec (gradually increased) in load range of 0.5 to 12 MPa

Speed: 3500 rpm

Counter shaft: SUJ2 (in the shoe shape)

Test results are as follows:

Surface roughness of
Test result

swash plate substrate
Load at adhesion

Rzjis (micron-meters)
(MPa)

Example
18
8.05
5.1

19
8.54
5.5

20
9.95
6.2

21
11.04
6.0

22
12.11
5.7

23
13.20
5.8

24
3.45
4.2

25
6.22
4.1

26
13.98
3.7

In the test results described above, if the surface roughness of the swash plate substrate in Rzjis is in a range of 8.0 to 13 micron-meters, the maximum load at adhesion relates to the surface roughness of the swash plate substrate, and the maximum value appears at the surface roughness in Rzjis of approximately 10 micron-meters. If the surface roughness in Rzjis is less than 8.0 micron-meters or exceeding 13.0 micron-meters, the load at adhesion is smaller than that achieved if the surface roughness in Rzjis is 8.0 to 13 micron-meters.

INDUSTRIAL APPLICABILITY

The swash plate type compressor according to the present invention is industrially useful because the adhesion resistance of the swash plate is greatly improved as compared with that achieved by the prior art because a mixed resin is used as a binder resin contained in a lubrication film provided on the swash plate.

Symbol List

1 Drive shaft

2 Rotor

2
a Rotor arm

2
b,
2
c Circular through-hole

3 Swash plate

3
a Swash plate substrate

3
b Swash plate boss

3
c Swash plate arm

3
d Circular through-hole

3
e Lubrication film

4 Shoe

5 Piston

6 Cylinder block

6
a Cylinder bore

7 Front housing

8 Cylinder head

9 Valve plate

10 Linking arm

10
a,
10
b,
10
c Circular through-hole

11, 12 Pin

13 Link mechanism

14 Inlet chamber

15 Crank chamber

SWASH PLATE TYPE COMPRESSOR

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