JPH048876A - Swash plate type variable displacement compressor - Google Patents

Abstract

PURPOSE:To restrain the occurrence of bearing separation phenomenon by using a corrosion resistance material containing at least the specified ratio or more of chrome for both or one of race and rolling element materials in all or at least one of the aforesaid bearings positioned in a compressor. CONSTITUTION:When a drive shaft 1 rotates, a swash plate 2 rotates as well. Then, a piston support 7 retained on the swash plate 2 via a thrust roller bearing 5 and a radial ball bearing 6, performs oscillation motion. As a result, a piston 9 connected to the piston support 7 via a connecting rod 8 reciprocally moves within the bore 11 of a cylinder 10. Consequently, a low pressure refrigerant passes the suction port 26 of a rear cover 19 and is absorbed from a low pressure chamber 17 into the bore 11 via a suction valve 15 located at a suction port 12. The low pressure refrigerant is thereby turned into a high pressure refrigerant, thereby causing the separation of the surface layer of a bearing rolling element in a short time. In the aforesaid constitution, a martensite stainless steel (SUS 440C as per JIS) having corrosion resistance quality and a less hydrogen diffusion factor than conventional bearing steel, for example, is selected as the material of the aforesaid bearing material.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a compressor used in a car air conditioner system using R134a as a refrigerant, and particularly relates to a bearing material suitable for suppressing bearing flaking phenomenon. This is related to the structure used.

[Conventional technology]

Bearing steel is commonly used as a bearing material in conventional swash plate compressors as shown in Japanese Patent Application Laid-Open No. 63-309786.

Case hardened steel, tool steel, etc. are used as bearing materials.

In addition, CFCl2, which contains chlorine in its molecules, is conventionally used as a refrigerant for car air conditioners, and when an active surface is formed on a metal surface such as the shaft moving surface of a bearing, the chlorine in CFCl2 becomes a type of polar It adhered to the active surface as a pressure agent and had the effect of supplementing bearing lubrication.

On the other hand, when O-C134a, which does not contain chlorine in its molecules, is used as a refrigerant, the active surface formed on the bearing's axial moving surface is exposed to the inert atmosphere of HFC134a, which lubricates the bearing. depends largely on the properties of the lubricating oil and the various additives contained in the lubricating oil. Also HFC134a
When PAG oil is used as a refrigerant, polyalkylene gellicol oil (hereinafter referred to as PAG oil), which is easily dissolved in the refrigerant, is used as a lubricating oil.

The saturated water content of PAG oil is generally 20,0OOpPffi
As mentioned above, there is a problem in that the inert atmosphere created by the HFC134a and the moisture in the PAG oil combine to promote stress corrosion on the rolling surface of the bearing, significantly shortening the life of the bearing.

[Problem to be solved by the invention]

When the above-mentioned conventional technology is used in an air conditioner cycle in which HFC134a is used as a refrigerant and, in particular, PAG oil is used as a lubricant, the above-mentioned stress corrosion problem manifests as a peeling phenomenon of the bearing due to the following factors.

(1) Insufficient supply of oil due to low refrigerant operation and the resulting rise in temperature of the bearing rolling surface.

(2) Increase in Hertzian surface pressure on the bearing rolling surface due to a decrease in the lubricating oil EHL film during high-load, low-speed operation. The purpose is to suppress the peeling phenomenon.

[Means to solve the problem]

In order to achieve the above objective, we selected a corrosion-resistant material that is less likely to cause stress corrosion for the bearing material. As the corrosion-resistant material, martensitic stainless steel, which can generally be used as a bearing material, was used. However, martensitic stainless steel has lower surface hardness than conventional bearing steel, etc.
It is necessary to increase the capacity of the bearing itself (increase the size and quantity of rolling elements).

[Effect]

By changing the bearing material from conventional materials (bearing steel, etc.) to corrosion-resistant materials, stress corrosion on the bearing rolling surfaces caused by the combination of the inert atmosphere created by the refrigerant HFC134a and the high water content contained in PAG oil can be prevented. can be suppressed,
It is possible to prevent the bearing from peeling off, which occurs under severe oil-sliding conditions.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

A drive plate 2 is fixed to the drive shaft 1, and a swash plate 3 is connected to the drive plate. The swash plate is inclined with respect to the drive shaft, and this inclination angle changes 8.
The drive plate is provided with a cam groove 4 so that the swash plate is connected to the drive plate through the cam groove. The swash plate includes a thrust roller bearing 5. A piston support 7 is rotatably held via a radial ball bearing 6, and as the swash plate having an inclination angle with respect to the drive shaft rotates, the piston support performs a rocking motion. . The piston 9 is connected to the piston support via the connecting rod 8 by the rocking motion of the piston support.
It reciprocates within a bore 11 provided in a cylinder 10.

A cylinder head 14 provided with a suction port 12 and a discharge boat 13 is disposed on the end surface of the piston near the top dead center of the cylinder.
7 and a rear cover 19 having a high pressure chamber 18, which is fixed with tightening bolts. Further, a crank chamber 2 surrounding the swash plate is provided on the end surface of the piston in the cylinder on the bottom dead center side.
0 is fixed. A thrust roller bearing 22 is provided on the F cover, and supports the drive shaft in the thrust direction together with a thrust roller bearing 23 provided at the center of the bore arrangement of the cylinder. Further, the F cover is provided with a radial roller bearing 24,
Together with a radial roller bearing 25 provided in the cylinder, the drive shaft is supported in the radial direction. here,
The thrust roller bearing 5°22.23, the radial ball bearing 6. The material of the radial roller bearings 24 and 25 is martensitic stainless steel 5US440C.

Next, the operation will be explained. When the drive shaft 1 rotates by receiving power from a drive system (not shown), the swash plate 2 fixed to the drive shaft rotates and is held by the swash plate via a thrust roller bearing 5 and a radial ball bearing 6. The piston support 7 that is located therein performs a rocking motion. Due to this rocking motion, the piston 9, which is connected to the piston support via the connecting rod 8, reciprocates within the bore 11 of the cylinder 1o. Due to this reciprocating movement, the low-pressure refrigerant returning from the air conditioner cycle (not shown) is transferred to the suction port 2 of the rear cover 19.
6, the refrigerant is sucked into the bore from the low pressure chamber 17 through the suction valve 15 located at the suction port 12 section, becomes high temperature and high pressure refrigerant, and is discharged from the high pressure chamber 18 through the discharge valve located at the discharge port 13 section. , and is again discharged into the air conditioner cycle through a discharge port (not shown).

Here, the thrust force and radial force generated by the differential pressure before and after the piston and the inertia of the rotating system and reciprocating system are:
The thrust roller bearings 2, 22° 23, radial ball bearings 6. It is supported by radial roller bearings 24 and 25.

When a variable capacity single swash plate compressor having the above structure is applied to an air conditioner cycle using HFC134a as a refrigerant and PAG oil as a lubricating oil, the bearings present in the compressor will absorb the inert atmosphere of HFC134a and saturated moisture. A corrosive atmosphere is created by the moisture supplied by the large amount of PAG oil and the acid generated by decomposition of the PAG oil. When a conventional bearing material (for example, bearing steel 5UJ2) is used in the above-mentioned corrosive atmosphere, microcracks (metal active surface) that occur due to some cause (for example, high Hertz surface pressure caused by using PGA oil) Hydrogen compounds such as moisture and acids are adsorbed and atomic hydrogen is generated, which causes corrosive corrosion due to hydrogen embrittlement, causing the bearing rolling surface to flake off in a short period of time.

In this example, martensitic stainless steel 5US440C, which is a corrosion-resistant material and has a smaller hydrogen diffusion coefficient than conventional bearing steel, is selected as the bearing material,
Stress corrosion of bearings, which occurs significantly when HFC134a is used as a refrigerant and PAG oil is used as a lubricant, is suppressed. Note that this embodiment uses conventionally used refrigerants (e.g., CFCl2) and lubricating oils (e.g., paraffinic mineral oil).
Needless to say, it is also applicable to an air conditioner cycle using HFC134a as the refrigerant and PAG oil as the lubricant, which is a mixture of both or one of the conventionally used refrigerant and lubricant.

〔Effect of the invention〕

In order to verify the present invention, elemental tests of the bearing were conducted to confirm the effects of this example. The bearing atmosphere and test conditions of the test machine used in this elemental test are shown below.

Refrigerant: FIFC134a Lubricating oil: PAG oil Internal pressure: 2 kg/aifG Rotation speed: 2000 rpm Maximum Hertzian surface pressure on bearing rolling part: 230 kg/■ The results of two tests are shown in Figure 2. The vertical axis shows the bearing life.The horizontal axis shows the moisture content in the oil.As a result, we evaluated the influence of the bearing material on the bearing life.We found that bearings made of conventional 5UJZ material have a water content of over 200 ppm in the oil. It was found that the life was below the rated life. On the other hand, the bearing material 5O selected in this example
Bearings using 5440C material have a moisture content of 20. It was confirmed that the rated life was not exceeded even at around OOOppm. Furthermore, when this example was subjected to a compressor durability test using severe conditions in which flaking of the bearing raceway was likely to occur, as shown in Figure 3, flaking of the bearing raceway did not occur even once. There wasn't. Therefore, according to the present invention, it is possible to prevent the peeling phenomenon on the bearing shaft moving surface that conventionally occurs when HFC134a is used as the refrigerant and PAG oil is used as the lubricant.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view of a variable capacity single swash plate compressor showing an embodiment of the present invention, FIG. 2 is a diagram showing the results of a bearing element test showing the effects of the present invention, and FIG. 3 is a diagram showing the results of a bearing element test showing the effects of the present invention. It is a figure which shows the result of the severe durability test which shows an effect. 1... Drive shaft, 2... Drive plate, 3...
Swash plate, 5, 22. 23...Thrust roller bearing, 6゛・
Radial ball bearing, 24.25...Radial roller bearing. 7... Piston support, 8... Connecting rod, 9...
··piston.

Claims (2)

[Claims] 1. a cylinder having a plurality of bores, a piston that reciprocates within the bore, a swash plate that rotates together with a drive shaft located at the center of the bore arrangement of the cylinder, and a radial ball bearing in a radial direction of the swash plate; A piston support is fixed in the thrust direction via a thrust roller bearing and allows the piston to reciprocate via connecting rods, and an F cover that forms a crank chamber surrounding the swash plate together with the cylinder, and the cylinder and F cover is provided with a radial roller bearing that rotatably supports the drive shaft and a thrust roller bearing that supports the thrust direction, the inclination angle of the swash plate changes depending on the differential pressure before and after the piston, and HFC134a is used as the refrigerant. In a variable capacity single swash plate compressor applied to an air conditioner cycle, the race material and rolling elements (rollers, rollers, A variable capacity single swash plate compressor characterized in that a corrosion-resistant material containing at least 3.5% chromium is used for both or one of the ball and the ball. 2. 2. The variable capacity single swash plate compressor according to claim 1, wherein said corrosion-resistant material is martensitic stainless steel.