WO2009157267A1

WO2009157267A1 - Shoe in piston type compressor

Info

Publication number: WO2009157267A1
Application number: PCT/JP2009/059645
Authority: WO
Inventors: 淳志斉藤; 隆弘杉岡; 崇行加藤
Original assignee: 株式会社豊田自動織機
Priority date: 2008-06-25
Filing date: 2009-05-27
Publication date: 2009-12-30

Abstract

Disclosed is a shoe provided in a piston-type compressor, which is equipped with a cam plate and a piston that moves in reciprocating fashion due to the rotation of said cam plate. Said shoe is equipped with a convex surface part and a flat surface part. The convex surface part fits into a concave seating surface formed on said piston. Said flat surface part faces the sliding surface of said cam plate. Said shoe has a first coating layer and a second coating layer. Said first coating layer is formed on said flat surface part and said convex surface part. Said second coating layer is provided on the first coating layer on said convex surface part. Said second coating layer is formed from diamond‑like carbon. The first coating layer on said flat surface part is the outermost coating layer.

Description

Shoe in piston type compressor

The present invention relates to a shoe in a piston type compressor.

In a piston compressor in which a hemispherical shoe is arranged between the sliding surface of the rotating swash plate and the piston, the wear of the sliding contact portion between the swash plate and the shoe and the sliding contact portion between the piston and the shoe In order to prevent wear, a coating layer having excellent slidability may be provided on the surface of the shoe (see, for example, FIG. 5 of Patent Document 2).

As a typical material for the coating layer, for example, there is nickel-phosphorous plating (hereinafter sometimes referred to as Ni-P plating). When Ni-P plating is provided on the surface of the shoe and a coating layer is provided on the concave seating surface of the piston that fits the convex surface of the shoe, the concave seating surface of the piston is made of a material different from Ni-P plating. A coating layer, for example tin plating, is provided. When Ni-P plating is provided on the surface of the shoe and a coating layer is provided on the sliding surface of the swash plate that is in sliding contact with the flat surface portion of the shoe, the Ni-P plating is applied to the sliding surface of the swash plate. A coating layer of a different material, for example, a resin layer containing a solid lubricant (such as molybdenum disulfide or graphite) is provided.

In the compressor, lubricating oil flowing together with the refrigerant lubricates the sliding contact portion in the compressor. Since the shoe slides with the rotation of the swash plate against the annular sliding surface of the swash plate that goes around the axis of the rotation shaft, the sliding between the sliding surface of the swash plate and the flat surface portion of the shoe. The contact part is easily lubricated by the lubricating oil.

However, the relative movement that occurs between the convex part of the shoe and the concave seating surface of the piston is slight and the speed of the relative movement is slow, so that the lubricating oil hardly enters between the convex part and the concave seating surface. Therefore, the sliding contact portion between the convex surface portion and the concave seat surface is not easily lubricated. When the Ni—P plating provided on the convex surface portion of the shoe is worn while the sliding contact portion is not sufficiently lubricated, the wear powder of the Ni—P plating adheres to the concave seating surface of the piston. Then, the wear powder of the Ni—P plating adhering to the concave seat surface and the Ni—P plating on the convex portion adhere to each other, thereby causing abnormal wear.

In order to prevent this abnormal wear, Patent Documents 1 and 2 disclose using diamond-like carbon (amorphous hard carbon film) as a coating layer provided on the surface of the shoe. Diamond-like carbon is a high-hardness carbon film having excellent slidability even when not sufficiently lubricated.

However, when using a low hardness material such as aluminum as the shoe base material (base metal) and providing high hardness diamond-like carbon directly on the shoe surface, the shoe base material Due to the large difference between the hardness and the hardness of diamond-like carbon, diamond-like carbon tends to peel off from the shoe.

Patent Document 3 discloses that Ni—P plating is provided on the surface of a shoe base material, and diamond-like carbon is provided on the Ni—P plating. The difference between the hardness of the Ni-P plating and the hardness of diamond-like carbon is smaller than the difference between the hardness of the base material of the shoe and the hardness of diamond-like carbon, so the diamond-like carbon is removed from the shoe. It becomes difficult to peel.

JP-A-6-346074 JP 2002-5013 A JP 2002-194565 A

However, the diamond-like carbon with high hardness provided on the flat surface portion of the shoe may wear the coating layer on the sliding surface of the swash plate that slides at high speed with respect to the shoe at an early stage.

An object of the present invention is to provide a shoe excellent in wear suppression.

In order to achieve the above object, according to an aspect of the present invention, there is provided a shoe provided in a piston compressor including a swash plate and a piston that reciprocates by rotation of the swash plate. The shoe includes a convex surface portion and a flat surface portion. The convex portion fits into a concave seat surface formed on the piston. The flat surface portion faces the sliding surface of the swash plate. The shoe includes a first coating layer and a second coating layer. The first coating layer is formed on the flat surface portion and the convex surface portion. The second coating layer is provided on the first coating layer on the convex surface portion. The second coating layer is formed of diamond-like carbon. The first coating layer on the flat surface portion is the outermost coating layer.

(A) is a side sectional view of a variable capacity piston type compressor provided with a shoe concerning one embodiment which materialized the present invention, and (b) is a partial expanded sectional view of Drawing 1 (a). (A), (b) is a figure which shows the result of the sliding test of the shoes of FIG.

Hereinafter, an embodiment embodying the present invention will be described with reference to FIGS. 1 and 2.
As shown in FIG. 1A, the housing of the variable displacement piston compressor 10 is joined to a cylinder block 11, a front housing member 12 joined to the front end of the cylinder block 11, and a rear end of the cylinder block 11. The rear housing member 17 is provided. The front housing member 12 and the cylinder block 11 form a control pressure chamber 121 between them. The front housing member 12 and the cylinder block 11 support the rotating shaft 13 in a rotatable manner. The rotating shaft 13 rotates by obtaining a driving force from an external driving source (for example, a vehicle engine). A rotary support 14 is fixed to the rotary shaft 13, and a swash plate 15 is supported so as to be movable and tiltable in the axial direction of the rotary shaft 13. The base material (metal) of the swash plate 15 is iron-based. The swash plate 15 includes an annular substrate portion 20 and an annular sliding plate portion 21 provided on the radially outer side of the substrate portion 20. The swash plate 15 is movable in the axial direction of the rotary shaft 13 while being tilted by the linkage between the guide hole 141 formed in the rotary support 14 and the guide pin 16 provided in the substrate portion 20 of the swash plate 15. And it can rotate integrally with the rotating shaft 13.

The inclination angle of the swash plate 15 changes according to the pressure in the control pressure chamber 121. The maximum inclination angle of the swash plate 15 is defined by the contact between the swash plate 15 and the rotary support 14. The swash plate 15 indicated by a chain line in FIG. 1A is at a position where the minimum inclination angle is obtained.

Pistons 18 are accommodated in a plurality of cylinder bores 111 (only two are shown in FIG. 1A) penetrating the cylinder block 11. The piston 18 has a head portion 181 and a neck portion 182, and the head portion 181 fitted in the cylinder bore 111 defines a compression chamber 112 in the cylinder bore 111. The piston 18 is made of an aluminum-based material containing silicon.

As shown in FIG. 1B, a recess 19 is formed in the neck 182, and a sliding plate portion 21 of the swash plate 15 is inserted in the recess 19. The sliding plate portion 21 has a first sliding surface 22A and a second sliding surface 22B. The pair of

inner wall surfaces

23 and 24 forming the recess 19 face each other and have a concave first spherical seat surface 25A and a second concave seat surface 25B, respectively.

The hemispherical first shoe 26A is fitted to the first concave seat surface 25A, and the hemispherical second shoe 26B is fitted to the second concave seat surface 25B. The base material (base metal) of the first shoe 26A and the second shoe 26B is an aluminum-based material containing silicon.

The first shoe 26A and the second shoe 26B have a spherical convex surface portion 27 and a planar flat surface portion 28, respectively. In the present embodiment, the flat surface portion 28 is strictly composed of a plurality of curved surfaces having a large curvature. The convex surface portion 27 of the first shoe 26A can slide on the first concave seat surface 25A, and the convex surface portion 27 of the second shoe 26B can slide on the second concave seat surface 25B. The flat surface portion 28 of the first shoe 26 </ b> A can be slidably contacted with the first sliding surface 22 </ b> A of the sliding plate portion 21, and the flat surface portion 28 of the second shoe 26 </ b> B is the second sliding surface of the sliding plate portion 21. 22B can be slidably contacted.

That is, the first shoe 26A is disposed between the first sliding surface 22A and the first concave seating surface 25A, and the second shoe 26B is provided between the second sliding surface 22B and the second concave seating surface 25B. It is arranged between. The rotational movement of the swash plate 15 is converted into the reciprocating movement of the piston 18 via the first shoe 26A and the second shoe 26B, and the piston 18 reciprocates in the cylinder bore 111.

When the piston 18 moves from the top dead center to the bottom dead center in the cylinder bore 111 (moving from the right side to the left side in FIG. 1A), the refrigerant in the suction chamber 29 formed in the rear housing member 17 is sucked. The air is sucked into the compression chamber 112 through the port 30. When the piston 18 moves in the cylinder bore 111 from the bottom dead center to the top dead center (from the left side to the right side in FIG. 1A), the refrigerant in the compression chamber 112 passes through the discharge port 31 and the rear housing. The ink is discharged into the discharge chamber 32 formed in the member 17.

As shown in FIG. 1B, a coating layer 33A is provided on the flat surface portion 211 of the base material (base metal) of the sliding plate portion 21 of the swash plate 15, and the surface of the coating layer 33A is the first surface. A sliding surface 22A is formed. Similarly, a coating layer 33B is provided on the flat surface portion 212 of the base material of the sliding plate portion 21, and the surface of the coating layer 33B forms the second sliding surface 22B. In the present embodiment, the coating layers 33A and 33B are each made of a resin material containing a solid lubricant. The solid lubricant is, for example, molybdenum disulfide or graphite.

A coating layer 34 is provided on the entire surface of the base material (metal) of the piston 18. In the present embodiment, the base material of the piston 18 is an aluminum-based material containing silicon, and the coating layer 34 is tin-plated.

The first coating layer 35 is provided on the entire surface of the base material of the first shoe 26A. In the present embodiment, the first coating layer 35 is nickel-phosphorous plating (hereinafter referred to as Ni-P plating). A second coating layer 36 is provided on the first coating layer 35 on the convex surface portion 27 of the first shoe 26A. The second coating layer 36 is diamond-like carbon (hereinafter referred to as DLC). That is, the outermost coating layer on the convex surface portion 27 of the first shoe 26A is the second coating layer 36, and the outermost coating layer on the flat surface portion 28 of the first shoe 26A is the first coating layer 35. is there.

The second shoe 26B is provided with a first coating layer 35 and a second coating layer 36 in the same manner as the first shoe 26A.
The first coating layer 35 made of Ni—P plating is formed by electroless plating. In the present embodiment, the weight% of P (phosphorus) in the first coating layer 35 (Ni—P plating) is 5% by weight or less, and the thickness of the first coating layer 35 is 40 μm. The second coating layer 36 that is DLC is formed by a vapor deposition method such as a CVD method or a PVD method. In the present embodiment, the thickness of the second coating layer 36 is 3 μm.

When the swash plate 15 rotates, the first coating layer 35 on the flat surface portion 28 of the first shoe 26A comes into sliding contact with the first sliding surface 22A of the swash plate 15, and the second on the convex surface portion 27 of the first shoe 26A. The coating layer 36 and the coating layer 34 on the first concave seat surface 25A of the piston 18 are in sliding contact. Further, the first coating layer 35 on the flat surface portion 28 of the second shoe 26B and the second sliding surface 22B of the swash plate 15 are in sliding contact, and the second coating layer 36 on the convex surface portion 27 of the second shoe 26B and the piston. The coating layer 34 on the 18th second concave seat surface 25B comes into sliding contact.

FIG. 2 (a) shows the results of a reciprocating sliding test on the

shoes

26A and 26B. The reciprocating sliding test was performed as follows. That is, the predetermined portion of the test member (a member corresponding to a piston) formed of an aluminum-based material containing silicon is fitted to the concave surface of the shoe, and the shoe is pressed against the concave surface. A weight (for example, 10 kg) was connected to the shoe. The entire surface of the test member (member corresponding to the piston) is provided with tin plating. Then, in a non-lubricated state, the shoe was slid against the concave seat surface by reciprocating the weight while pressing the shoe against the concave seat surface.

In the case where the first coating layer (Ni—P plating) was not provided on the convex portion of the shoe, adhesion occurred when the weight reciprocated 6 to 8 times.
When the first coating layer (Ni—P plating) was provided on the convex surface portion of the shoe, adhesion occurred when the weight reciprocated 10 to 12 times.

When the first coating layer (Ni-P plating) and the second coating layer (DLC) were provided on the convex surface of the shoe, no adhesion occurred even when the weight reciprocated 15 to 20 times. .

Even when the second coating layer (DLC) was directly provided on the convex portion of the shoe without the first coating layer, adhesion did not occur even when the weight reciprocated 15 to 20 times.
FIG. 2 (b) shows the result of the rotational sliding test on the

shoes

26A and 26B. In the rotational sliding test, the lubricating oil is applied in a state where the flat surface portions of a plurality of shoes (same as the number of pistons 18) are pressed against a coating layer provided on a rotating flat plate made of the same material as the swash plate 15. While spraying, the rotating plate was rotated while pressing the shoe against the coating layer of the rotating plate. At this time, the pressing load of the shoe against the rotating flat plate was gradually increased. The coating layer provided on the rotating flat plate is the same as the coating layers 33A and 33B. The pressing load started from 0.4 kN and increased stepwise by 0.4 kN every 5 minutes. Lubricating oil was sprayed at 25 mg per minute. The number of rotations of the rotating plate was 2000 rpm. The rotary sliding test was performed twice.

When only the heel Ni—P plating coating layer is provided on the flat surface portion of the shoe as in the

shoes

26A and 26B of the present embodiment, the seizure occurs when the pressing load is 4.8 kN in the first test. In the second test, seizure occurred when the pressing load reached 4.4 kN.

When only the DLC coating layer is provided on the flat surface portion of the shoe, seizure occurs when the pressing load is 3.2 kN in the first test, and the pressing load is 2.8 kN in the second test. Burning occurred when

2B shows that when a DLC coating layer is provided on the flat surface portion 28 of the shoe that is in sliding contact with the sliding

surfaces

22A and 22B of the swash plate 15, the sliding

surfaces

22A and 22B of the swash plate 15 are DLC. It shows that it becomes easy to wear due to the presence of the coating layer.

The above embodiment has the following advantages.
(1) The second coating layer 36 (DLC) provided on the first coating layer 35 (Ni—P plating) is worn by the first coating layer 35 (Ni—P plating) provided on the convex portion 27. Therefore, abnormal wear of the convex portion 27 and the

concave seat surfaces

25A and 25B that are difficult to be lubricated is avoided.

Since only the first coating layer 35 (Ni—P plating) is provided on the flat surface portion 28 and there is no DLC coating layer, the sliding

surfaces

22A and 22B of the swash plate 15 are easily worn due to the presence of DLC. The problem is avoided. Further, since an oil film is likely to be formed on the flat surface portion 28, that is, it is easily lubricated, only the first coating layer 35 (Ni-P plating) is provided between the sliding

surfaces

22A, 22B and the first coating layer 35. Abnormal wear does not occur as in the prior art.

(2) The hardness of the first coating layer 35 (Ni-P plating) interposed between the high hardness second coating layer 36 (DLC) and the base material of the

shoes

26A and 26B is lower than the hardness of DLC. The hardness of aluminum containing silicon which is a base material of the

shoes

26A and 26B is higher. That is, the 1st coating layer 35 relieves the malfunction resulting from the difference of the hardness of DLC and the hardness of the member coated with this DLC. Therefore, the stress generated in the DLC is relaxed, and the second coating layer 36 is prevented from being peeled off from the

shoes

26A and 26B.

(3) Since the second coating layer 36 is provided only on the convex surface portion 27 of the

shoes

26A and 26B, when forming the second coating layer 36, the flat surface portion 28 is placed on the flat seat so as to contact the flat seat. The second coating layer 36 can be formed on the convex portion 27 in a state where the

shoes

26A and 26B are placed. Such a method of forming the second coating layer 36 eliminates the need for a complicated jig for supporting the

shoes

26A and 26B.

(4) Ni—P plating as the first coating layer 35 is Ni-based plating formed by electroless plating, and can be formed by simply immersing the base material of the

shoes

26A and 26B in the plating solution. Therefore, Ni—P plating is suitable as the first coating layer 35 that covers the entire surface of the base material of the

shoes

26A and 26B.

In the present invention, the following embodiments are also possible.
The flat surface portion 28 may be a complete plane.
The base material of the

shoes

26A and 26B may be titanium or iron.

The first coating layer 35 may be copper-based plating formed by electroless plating.
The present invention may be applied to a compressor in which a coating layer is not provided on an iron-based swash plate.
The present invention may be applied to a compressor in which a coating layer is not provided on an iron-based piston.

A large discharge reaction force in the discharge stroke is applied only to the second shoe 26B and not to the first shoe 26A. Therefore, when there is no fear of abnormal wear on the convex portion 27 of the first shoe 26A, the first shoe Only the first coating layer 35 may be provided on 26A.

DESCRIPTION OF SYMBOLS 15 ... Swash plate, 18 ... Piston, 22A, 22B ... Sliding surface, 25A, 25B ... Concave seat surface, 26A, 26B ... Shoe, 27 ... Convex part, 28 ... Flat view, 35 ... 1st coating layer, 36 ... second coating layer.

Claims

A shoe provided in a piston-type compressor including a swash plate and a piston that reciprocates by rotation of the swash plate, wherein the shoe includes a convex surface portion that fits into a concave seat surface formed on the piston, A flat surface portion facing the sliding surface of the swash plate, the shoe,
A first coating layer formed on the flat surface portion and the convex surface portion;
A second coating layer provided on the first coating layer on the convex surface part,
The second coating layer is formed of diamond-like carbon,
The shoe according to claim 1, wherein the first coating layer on the flat surface portion is an outermost coating layer.
The shoe according to claim 1, wherein the first coating layer is formed of a material other than diamond-like carbon.
The shoe according to claim 1 or 2, wherein the hardness of the first coating layer is higher than the hardness of the base material of the shoe and lower than the hardness of the diamond-like carbon.
The shoe according to any one of claims 1 to 3, wherein the first coating layer is nickel-based plating.
The shoe according to claim 4, wherein the nickel-based plating is nickel-phosphorus plating.
The shoe according to claim 4 or 5, wherein the first coating layer is formed by electroless plating, and the second coating layer is formed by a vapor deposition method including a CVD method or a PVD method.
6. The shoe according to claim 4, wherein a coating layer made of a resin containing a solid lubricant is formed on the sliding surface of the swash plate.
The shoe according to claim 7, wherein the solid lubricant is molybdenum disulfide or graphite.