JPS5848792A - Screw compressor - Google Patents

Abstract

PURPOSE:To prevent seizure damage of the end face of a rotor and improve reliability by a method wherein a film layer (babitt metal for example) high in the initial fitting property thereof is formed on the end face in the axial direction of the rotor, in the screw compressor accommodating the rotor. CONSTITUTION:The film layer 9 high in the initial draping property thereof is formed on the surface of the end faces in the axial directions of the rotors 2a, 2b. Said film layer 9 is formed by a substance having a small friction coefficient such as tetrafluoroethylene, a substance having a good oil lubricating property such as carbon graphite or a soft metal such as the babbitt metal, for example. According to this method, there is no fear that the seizure damage is caused on the end face 8 of the rotor even if the same 8 is contacted with the inner surface of a casing 1, and the rotor may be assembled so as to have a minimum gap between the end face 8 of the rotor and the casing 1.

Description

[Detailed description of the invention] The present invention relates to improvements in screier compressors.

As shown in FIG. 1, a conventional screw compressor houses a female rotor 2a and a male rotor 2b that engage with each other in a casing 1 having an inlet 6 and a discharge lower, and a rotor 2'* attached to the discharge lower. 2b is housed in a slide valve 3, which is connected to a piston 5 via a piston rod 4.

In such a structure, the rotor 2a l 21) is always pressed from the discharge lower side to the suction 6 side, and instead of gas sealing with a piston ring as in the case of uniform recipe pressure,
All parts are sealed with a thin oil film. Therefore, it is necessary to make the gaps between each part as small as possible.

However, among the various gaps, the gap between the axial end faces of the rotor can be adjusted during assembly, so variations in assembly work greatly affect performance. For this reason, in order to improve the performance of conventional screier compressors, the gap between the rotor end faces was generally reduced during assembly.

If the rotor and rotor are configured in this way, it will be effective in improving the performance of the compressor, but since the gap is small, not only will foreign matter get caught, but there is also the risk of galling damage to the rotor end face due to thermal expansion imbalance. There is.

The present invention has been made to solve the above-mentioned drawbacks, and is a screw compressor having a built-in rotor, characterized in that a film layer with high initial conformability is formed on the axial end face of the rotor. In FIG. 2, which describes an embodiment of the present invention with reference to the drawings, 1 is a casing;
&12t' are a female rotor and a male rotor that are interlocked with each other and rotatably housed in the casing 1, and a film layer 9 with high initial conformability is formed on the surface of the axial end face 8 of the rotor 2aw2b. ing. This film layer 9 is formed of a soft metal such as Babbitt metal, a material with good oil lubricity such as carbon graphite, or a material with a small coefficient of friction such as tetrafluoroethylene. Since it is the same as the conventional example shown in the figure, the drawing and explanation are omitted.

If the film layer 9 with high initial conformability is formed on the axial end face 8 of the rotor as described above, even if the rotor end face 8 comes into contact with the inner surface of the casing 1, there is a risk of galling damage to the rotor end face 8. It is possible to assemble the lock with the minimum gap between the rotor end face and the casing without having to worry about any problems.

As explained above, according to the present invention, it is possible to prevent damage to the rotor end surface and improve reliability.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a conventional screw compressor, and FIG. 2 is a sectional view of essential parts showing an embodiment of the screw compressor of the present invention. 2 & e2b... Rotor 8... Axial end [9...
film layer

Claims (1)

[Claims] 1. In a screw compressor with a built-in rotor,
A screw compressor characterized in that a film layer having high initial conformability is formed on an axial end face of the rotor. 26. The screw compressor according to claim 1, wherein the highly compatible coating layer is Babbitt metal. 3. The screw compressor according to claim 1, wherein the coating layer with high conformability is carbon graphite. 4. The screw compressor according to claim 1, wherein the film layer having high conformability is made of 4-fluorinated ethylene.