JPS6241980A - Shoe for swash plate type compressor - Google Patents

Abstract

PURPOSE:To compensate the accuracy of the spherical surface of a shoe while improve conformability by covering the spherical surface side of said shoe made of a ceramic with a soft and thin layer. CONSTITUTION:A shoe 12 has a semispherical shape having a projected spherical surface 13 which is slidingly brought into contact with the recessed spherical surface 7a of a piston 7, and a plane surface 14 which is slidingly brought into contact with the smooth plane of a swash plate 5. This shoe 12 is molded by sintering the mixture of ceramic particles and talc. And, the spherical surface 13 side of the molded shoe 12 is covered by a solid lubricant formed by hardening the powder of molybdenum disulfide, graphite, fluorine plastic, etc. with a resin, or a soft metal such as lead, tin, etc., to form a soft thin layer 15.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a shoe for a swash plate type compressor, which is used, for example, in an automobile air conditioning system and which causes a swash plate and a piston to interlock.

[Prior Art] In a swash plate compressor used in, for example, an automobile air conditioning system, shoes made of steel or aluminum alloy are used.

This shoe is provided between the swash plate and the piston, and has a flat surface that slides on the swash plate and a concave spherical surface that slides on the concave or convex spherical surface on the piston side. The spherical precision of this spherical surface is required to be extremely accurate in order to ensure smooth power transmission to the piston.

By the way, since a large load and a rapid reaction force are applied to the shoe, the shoe is likely to seize under conditions where the supply of lubricating oil is insufficient, such as when the shoe is out of oil. Particularly in swash plate compressors, the more lubricating oil in the refrigerant, the lower the refrigerating capacity. H people) tend to reduce the amount of 11 (there are 2, and the shoe is more likely to seize).

In order to suppress seizure, the entire shoe can be made of ceramics1, but since ceramics are hard and brittle after firing, it is impossible to machine the spherical surface to a roughness of less than 5tt. Although this is not a problem, the cost will be significantly higher in order to accurately process the shoe to the roughness of 2μ or less required. Therefore, although shoes made of ζ lamix can suppress seizure, they pose a problem for practical use.

[Object of the Invention] The present invention has been made to overcome the problems of the prior art described above. Accordingly, an object of the present invention is to provide a shoe made of ceramics which has improved accuracy of the spherical surface, improved conformability, and further improved seizure resistance.

[Structure of the Invention] As a result of intensive research for the above purpose, the present inventor has found that the seizure resistance of the shoe can be improved by manufacturing the shoe from ceramics and coating the spherical side of the shoe with a soft thin layer. 1! Tsutsu,
Improved smearing properties of ceramic shoes! I discovered that 4iJ. This invention originates from this! , At; 21,9th (completed l, -〇(・there is).

That is, the shoe of the present invention is a shoe having a flat surface that slides in contact with a smooth plane and a spherical surface that contacts a convex or concave spherical surface, the shoe having a base material of ceramics, and at least the spherical surface being in contact with the base material. It is characterized by being composed of the surface of a soft thin layer formed on a material.

A convex ball used in a swash plate compressor 1 of an automobile air conditioning system 1) of the present invention
, a hemispherical shoe with a shaped surface, or a plate-shaped shoe with a concave spherical surface into which the convex spherical surface of the ball fits = 4
- It's a shoe.

The shoe of the present invention has a flat surface that comes into sliding contact with a smooth plane, and a spherical surface that comes into sliding contact with a convex or concave spherical surface. Here, the flat surface of the shoe means that it is flat or nearly flat when observed with the naked eye. In other words, in addition to the exact flat surface with the surface directly below, there are some mounds, depressions, and undulations when viewed microscopically.
The meaning includes the surface. The raised portion may be raised in the central portion of the flat surface by, for example, several to ten-odd micrometers.

By forming such a raised portion, an oil film can be formed satisfactorily between the flat surface and its counterpart.

A spherical surface of a shoe usually means a convex or concave surface consisting of a locus of points at equal or approximately equal distances from a fixed point. That is, in the case of a hemispherical shoe, the spherical surface is convex, whereas in the case of a plate-shaped shoe into which a ball is fitted, the spherical surface is concave.

The shoe of the present invention is based on ceramics. 1
! -5= It is possible to use lamics and () (' is the usual I), that is, saponide-based, carbide-based, nitride-based, etc. For example, alumina, silicon nitride, silicon carbide, zirconia, mica, magnesia , aluminum nitride, titanium nitride, sialon, etc. can be used in some cases. Alumina has high mechanical strength at room temperature and high temperature, and has the widest range of uses among oxide ceramics.

A small amount of magnesia may be added to the alumina to suppress the growth of alumina crystal particles during firing and to make the structure fine.

Additionally, zirconia may be dispersed in alumina to improve the τ° strength and toughness. Silicon nitride typically has a bending strength of 80 to 130 k per square millimeter.

Furthermore, since the thermal expansion coefficient is about 1 attenuation compared to that of oxide-based ceramics, the thermal shock resistance is large.

When using silicon nitride, if sintering is performed with beryllium, magnesium, alumina, yttrium oxide, magnesium aluminum spinel, etc. added as sintering aids to the raw material powder, sintering will occur due to the reaction between silicon nitride and the sintering aid. The liquid phase promotes the progress of sintering, resulting in high strength. Silicon carbide usually has a bending strength of 45 to 1 mm per square millimeter.
60ko, which is not as high as silicon nitride, but the decrease in strength in the high temperature range is smaller than that of silicon nitride. Zirconia (
Even if the strength is increased by mixing several mol% of iso1 to ria, J,
stomach. Mica is mixed with alumina and carbon powder and sintered 4
Rudoyoi. Note that mica can improve the machinability of ceramics. The iron can be obtained by sintering a mixed powder of silicon nitride, aluminum nitride, and aluminum oxide at a temperature of 150(')°C or higher. The bending strength of Sialon's pressurized sintered body is 1 to 1 mm per square millimeter.
j'j 7+j' Fl O・=70 k(1(- exists.

The ceramic that is the base material of the shoe has an average particle size of 2 to 10
It is preferable to use powder No. 11, and after molding this mixed powder into a predetermined shape, it is preferable to sinter at 1500 to 1700°C. As the molding method and sintering method, commonly used methods can be used. For example, molding methods include press molding method, hot press method, rubber press method, injection molding method,
Extrusion molding method <1 etc. can be used. As a sintering method, sintering is performed in a pressure vessel.
tic, press) method, normal pressure sintering method, pressure sintering method in which sintering is performed while applying pressure in a mold, and reactive sintering method in which synthesis reaction and sintering are performed simultaneously. According to the HIP method or the pressure sintering method, it is possible to obtain a seal with almost no pores.

In general, the higher the temperature of sintering, the higher the density of the sintered body. However, silicon nitride is easily thermally decomposed at high temperatures.
Pores are generated on the surface of the sintered body, which reduces the strength of the sintered body. Therefore, in the case of silicon nitride, it is better to sinter under pressure. Sintering is preferably performed in an inert gas atmosphere such as nitrogen, helium, or argon, or under high vacuum.

The spherical surface of the shoe of the present invention is comprised of the surface of a soft thin layer formed on a base material. The soft thin layer refers to a layer made of a soft material that is softer than the base material of the shoe or the mating member. As the shaft 1 is driven, the soft thin layer partially transfers to the mating material and comes to correspond to the concave or convex spherical shape of the mating material.
In other words, the conformability is improved, and therefore the spherical accuracy of the spherical surface of the shoe can be compensated for.

The soft thin layer can be made of a solid lubricant or a soft metal, and is preferably made of a solid lubricant layer. The solid lubricant layer can be made by hardening solid lubricant powder such as molybdenum disulfide, fluororesin, tungsten disulfide, Graphite, boron nitride, or lead oxide with resin, or by hardening solid lubricant powder such as lead, indium, or tin with soft lubricant such as lead, indium, or tin. Structure J- may be achieved by plating metal or coating with a fluororesin such as polytetrafluorotobrene. The solid lubricant layer may be composed of fluorine-containing molybdenum.

In addition, when solidifying the powder of the solid ai'l H'l agent with a resin, the surface of the base material of the shoe is appropriately ground and polished, and a resin paste containing a solid lubricant is applied to the surface of the base material.
It is preferable to form a solid lubricant layer on the shoe by solidifying this at room temperature or by heating or other methods. As for the application method, there can be any conventional application method such as a spray method, a tampling method, a brush application method, and the like.

As the resin, thermosetting resins such as phenol resin, epoxy resin, furan resin, amino resin, lily A7 resin, polyamideimide resin, unsaturated polyester, and diallyl phthalate resin are preferred. Also, depending on the usage conditions, fluororesin, polyacetal resin, nylon resin, ABS
Thermoplastic resins such as resins, polyethylene terephthalate resins, and polycarbonate resins can also be used.

The thickness, type, etc. of the soft thin layer of the present invention are determined in consideration of various conditions such as the magnitude of the load acting on the +- and the J-slipping speed. The thickness of the soft thin layer is generally 1μ to 5μ.
Although approximately tt is preferable, it is related to the surface roughness of the ceramic base material. The greater the roughness of the base material, the greater the thickness of the soft thin layer. In addition, if the surface of the base material is smooth and lubricating oil is sufficiently supplied, sufficient durability can be obtained even if the soft thin layer is relatively thin, about 1 μm. Note that in the case of special uses, it may be preferable that the thickness of the soft thin layer be approximately 8 μm or more.

[Effects of the Invention] The shoe of the present invention has a flat surface in contact with a smooth plane and a spherical surface in sliding contact with a convex or concave spherical surface, and the shoe is made of ceramic as a base material, At least the spherical surface is characterized in that it is constituted by the surface of a soft thin layer formed on the base material.

Therefore, in the present invention, as the shoe is driven at the initial stage of sliding, the surface of the soft thin layer wears out and comes to correspond to the shape of the concave or convex spherical surface of the mating material. Even if the spherical accuracy is poor, it can be compensated for by a soft thin layer. In this way, the surface of the soft thin layer can be made to match the concave or convex spherical surface of the mating material.
The shoe can be driven well.

In addition, when the soft thin layer is used as a solid lubricant layer, the surface effect of the solid lubricant h°・1 is i' can.

Therefore, even when the swash plate compressor is operated under severe conditions such as when lubricating oil is temporarily not supplied, such as at the beginning of startup, the sliding movement between the shoe and the mating member can be ensured in a favorable manner.

In addition, since ceramics are inorganic and have excellent seizure resistance and heat resistance, the shoes and shields are designed to have sea 2-5 (Kawamukai's seizure resistance l'-4!f).

[Embodiment] FIGS. 1 and 2 show an embodiment in which the present invention is applied to a hemispherical shoe used in a swash plate compressor, which is a main element of an automobile air conditioning system.

First, the overall configuration of the swash plate type amplifier 4J- will be explained. In FIG. 1, 1 is a cylinder block, and a rotating shaft 2 is rotatably supported in the cylinder block 1 via a bearing 3.4, and a swash plate 5 made of Alsil alloy is mounted on this rotating shaft 2. Connection is fixed. A plurality of cylinder bores 6 are formed in the cylinder block 1, and a piston 7 is slidably fitted into each bore 6. A concave spherical surface 7a is formed in the central portion of the piston 7. The left end opening of this cylinder tab 1 is closed by the valve plates 1 and 8 and the front housing 9, and the right end opening is closed by the valve plates 1 to 10 and the rear housing 11. Here, the valve plate 8 has an inlet 8aA3 and an outlet 8b. Furthermore, valve series 1 to ε3
A suction valve 8C functioning as an intake valve is provided, and a disk charge valve 8d functioning as a discharge valve is also provided.

Similarly, the valve plate 10 is provided with a friction valve 10c that functions as an intake valve, and a disk charge valve 10d that functions as a discharge valve.

Next, the configuration of the main parts will be explained. That is, 12 is a hemispherical mark, and this FLG has a convex spherical surface 13 that slides on the concave spherical surface 7a of the piston l, and a flat surface 14 that slides on the smooth plane of the swash plate 5. We are prepared. This shoe 1
2 uses ceramic as a base material and has a diameter of 13.5111
111. Shoe 12 was manufactured as follows. That is, a compacted body was produced by using alumina ceramic particles having an average particle size of 1 to 10 μm, adding 5irj 1% of talc, and performing mixing, granulation, pressing with a rubber press, etc. Next, this compacted body is heated to about 1500 to 1700℃ for about 50 minutes.
It was sintered by heating for an hour. Thereafter, a paste made by kneading molybdenum disulfide and graphite with phenol resin is applied by spraying to the spherical side of the ceramic shoe 12, and this is solidified by firing to form the solid lubricant layer 15.
And so. The surface of the solid lubricant layer 15 formed in this way becomes the spherical surface 13. Note that the thickness of the solid lubricant layer 15 in this example is 2 to 4 μm.

In this example, the roughness of the spherical surface 12a side of the shoe 12 is 5.
Even when the spherical accuracy was as low as μ, the solid lubricant layer 15 was able to sufficiently compensate for the low spherical accuracy.

The flat surface 14 of the shoe 12 in this example has a central portion 14a raised by several micrometers, and a chamfered portion 16 is formed at the peripheral edge of the flat surface 14. If the central portion 14a of the flat surface 14 is raised or the chamfered portion 16 is formed in this way, it becomes easier to form an oil film between the swash plate 5, which is the mating material, and the flat surface 14, which may lead to seizure. Effective in prevention.

Incidentally, the shoe may be a hemispherical shoe 12 as in the swash plate compressor of the above embodiment, but it may also be used by combining a flat shoe 24 and a ball 25 as shown in FIG. J, yes. The flat shoe 24 is made of ceramic. Figure 3 (J 'a:'
l It is a flat sheet 1-24 in the formula konbu 1 nori.
The ball 25 is interposed between the concave spherical surface 70a of the screw 70 and the concave spherical surface 28 of the shoe 21. The spherical surface 28 of the shoe 24 is covered with a solid lubricant layer as in the previous example.

4. Inside the drawing 1. Figures 1 and 2 show one embodiment of the present invention. Figure 1 is a longitudinal cross-sectional view of a swash plate compressor using hemispherical shoes, and Figure 2 is a diagram showing this embodiment. FIG. 3 is a sectional view of the shoe. FIG. 3 is a longitudinal sectional view of a swash plate compressor using flat shoes.

In the figure, 12 is a hemispherical shoe, 15 is a solid lubricant layer, 2
4 indicates a flat shoe.

Claims (1)

[Scope of Claims] (1) A cylinder block having a plurality of cylinder bores provided parallel to the axis, a swash plate rotated by a rotating shaft within the cylinder block, and a swash plate slidably fitted into the cylinder bore. In a shoe for a swash plate compressor in which the piston is combined with the piston and the piston is reciprocated by rotation of the swash plate, the shoe has a flat surface in sliding contact with a smooth surface;
A bevel comprising a ceramic base material having a convex or concave spherical surface and a spherical surface in sliding contact, and the spherical surface is composed of the surface of a soft thin layer formed on the base material. Shoe for plate compressor. (2) The soft thin layer contains one or more of molybdenum disulfide, tungsten disulfide, fluororesin, lead oxide, graphite, boron nitride, lead, indium, and tin. Shuttle for plate type compressor. (3) The swash for a swash plate compressor according to claim 1, wherein the soft thin layer has a thickness of 1 to 5 μm. (4) The swash for a swash plate compressor according to claim 1, wherein the ceramic is alumina, silicon nitride, silicon carbide, zirconia, or mica with a porosity of 2% or less.