JPH04134192A - Reciprocating compressor - Google Patents

Abstract

PURPOSE:To obtain a compact and non-oiling reciprocating compressor having a large capacity by making the sliding surfaces of a cylinder and a piston of ceramics, and making at least one of them of oil-impregnated ceramics. CONSTITUTION:A cylinder 2 is fixed on a base 1 of a main frame, and a cylinder linear 3 made of the ceramics material is installed to the inner wall of the cylinder 2. On the other hand, a piston ring 5 made of the ceramics material and a guide ring 6 made of the ceramics material similarly are installed to the peripheral surface of a piston 4. The piston ring 5 and the guide ring 6 are made of the oil-impregnated ceramics. Furthermore, a connecting rod 7 connected to a driving source through an eccentric shaft is fitted to a piston pin 8 fixed on the piston 4 freely to be oscillated. When the piston 4 is lowered, the gas is sucked through an intake valve 10 on an upper cover 9, and reversely, when the piston 4 is raised, the gas is discharged through a discharge valve 11.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the structure of a reciprocating compression section in a mechanism in which a piston reciprocates within a cylinder, such as a reciprocating air compressor.

[Prior Art] Conventionally, a reciprocating compressor has a structure in which a piston D equipped with a piston ring B1 and a guide ring C reciprocates inside a cylinder A, as shown in FIG. At that time, gas is sucked in through the suction valve F on the upper lid E, and the gas is sucked through the discharge valve G.
It is then discharged.

The material of the inner wall of the cylinder A and the outer periphery of the piston ring B1 and guide ring C during the reciprocating motion of the piston D is mostly a combination of metal or plastic. If the material of the piston ring B1 guide ring C is metal, it is usually oil-lubricated, and if it is made of plastic, it is usually self-lubricated.

There have also been proposals to make the cylinder A1 or the piston D, in which the piston ring B and guide ring C are integrated, made of ceramics with excellent wear resistance (for example, Japanese Patent Application Laid-open No. 79277/1983). .

[Problems to be Solved by the Invention] However, according to the former prior art, in the case of oil lubrication, oil and carbide are
Furthermore, even in the case of self-lubrication, there is a problem in that wear debris such as plastic and carbide are mixed into the discharged gas, making it impossible to obtain clean air.

In addition, according to the latter conventional technology, when reciprocating compressors are made smaller and larger in capacity, that is, under operating conditions such as high speed and high load, even ceramic materials are not versatile and have high frictional resistance without oil. When wear begins, the hard wear particles become trapped between the sliding surfaces, causing rapid wear.

The present invention has been made in order to solve the above-mentioned problems, and an object of the present invention is to obtain a small, large-capacity, oil-free reciprocating compressor.

[Means for Solving the Problem] In order to achieve this object, the reciprocating compressor of the present invention has the following features:
The sliding surfaces of the cylinder and piston that make up the sliding mechanism are made of ceramic material, and the pores inside one of the sliding surfaces of the cylinder and piston are impregnated with lubricating oil. It is made of ceramics.

[Function] The technical means of the present invention having the above configuration prevents impregnation in the pores inside the ceramic even if a local load is applied to the sliding surfaces of the cylinder and piston during reciprocating sliding. As the temperature rises, oil oozes out onto the sliding parts on the surface, supporting the load without lubrication.
It can prevent seizure and wear.

[Example] Hereinafter, an example embodying the present invention will be described with reference to the drawings.

FIG. 1 is a longitudinal sectional view of a reciprocating compressor of the present invention.

A cylinder 2 is fixed on a main body base 1, and a cylinder liner 3 made of ceramic material is attached to the inner wall of the cylinder 2.

On the other hand, a piston ring 5 made of a ceramic material and a guide ring 6 similarly made of a ceramic material are attached to the outer peripheral surface of the piston 4.

The piston ring 5 and guide ring 6 are made of oil-impregnated ceramics. Note that only the cylinder liner 3 may be formed of oil-impregnated ceramics, or both the cylinder liner 3, the piston ring 5, and the guide ring 6 may be formed of oil-impregnated ceramics.

The piston ring 5 and the guide ring 6 have a cylindrical shape, and are slidably fitted into the inner surface of the cylinder liner 3, which also has a cylindrical shape.

A connecting rod 7 connected to a drive source (motor) via an eccentric shaft (not shown) is attached to be swingable with respect to a piston pin 8 fixed to the piston 4. When the drive source is driven, its rotational motion is transmitted to the piston 4 as a linear reciprocating motion, so that the piston ring 5 and the guide ring 6 slide against the cylinder liner 3.

Here, when the piston 4 descends, gas is sucked in through the suction valve 10 on the top cover 9, and conversely, when the piston 4 rises, gas is discharged through the discharge valve 11 on the top cover.

The cylinder liner 3 and the cylinder 2, or the piston ring 5, the guide ring 6, and the piston 4 may each be formed integrally with a ceramic material.

Next, test results of the wear characteristics of this embodiment and the conventional example will be explained.

FIG. 2 shows a test device used to evaluate wear characteristics, in which a test block 13 is pressed with a certain load against the outer tank surface of a reciprocating test pin 12. Figure 3,
FIG. 5 is a characteristic diagram of the present example and the conventional example evaluated using the test apparatus.

As is clear from the figure, compared to the conventional combination of ceramics, that is, chromia (Cr203) and silicon carbide (S i C), the chromia and oil-impregnated silicon carbide of this example are better on the pin side and the block side. It can be seen that the amount of wear is small in both cases. In particular, the reason why the wear on the pin side of the conventional example increases rapidly over the course of sliding time is because adhesion occurs due to local load. In the case of this example, even if such a local load is applied, the oil impregnated in the pores inside the silicon carbide oozes out between the sliding surfaces, supporting the load and preventing adhesion. can.

In addition, in a reciprocating compressor, the piston ring 5 is distorted to improve the sealing effect of the compressed gas.
Many have a mechanism that applies preload to the Therefore, when applying a combination of chromia and silicon carbide to a reciprocating compressor, the elastic modulus of the piston ring 5 side is lower than that of ceramics.
It is preferable that ceramics be sprayed on a metal base having a large amount of elastic deformation, and that the cylinder liner 3 side be made of an oil-impregnated ceramic sintered body.

[Effects of the Invention] As is clear from the above detailed description, according to the reciprocating compressor of the present invention, the sliding surfaces of the cylinder and piston are made of ceramics, and at least one of them is made of oil-impregnated ceramics. Therefore, low wear can be maintained without seizure even when sliding under high speed and high load without lubrication. Further, since the amount of oil impregnated is very small, the discharged gas will not be contaminated. Therefore, a small-sized, large-capacity, oil-free reciprocating compressor can be obtained.

[Brief explanation of drawings]

Fig. 1 shows an embodiment embodying the present invention; Fig. 2 is a longitudinal sectional view of a reciprocating compressor; Fig. 2 is a schematic explanatory drawing showing a test device used for evaluating wear resistance; and Fig. 3 is a longitudinal sectional view of a reciprocating compressor. FIG. 4 is a longitudinal sectional view of a reciprocating compressor according to a conventional example, and FIG. 5 is a characteristic diagram showing wear resistance of the conventional example. In the figure, 2 is a cylinder, 3 is a cylinder liner, 4 is a piston, 5 is a piston ring, and 6 is a guide ring.

Claims (1)

[Claims] 1. In a reciprocating compressor in which a piston moves up and down in a cylinder, the sliding surfaces of the cylinder and piston are made of ceramics, and at least one of the sliding surfaces of the cylinder and piston is made of oil-impregnated ceramics. A reciprocating compressor characterized by: