JPH01305182A - Screw compressor - Google Patents

Abstract

PURPOSE:To prevent seizure of the end face of a rotor by providing a ring-like thrust bearing whose outer diameter is smaller than the diameter of root circle of the screw rotor and which is formed to be projected from the face of a casing to the casing opposed to the delivery side end face of the rotor. CONSTITUTION:During a normal operation, a thrust bearing 5 takes a thrust from the delivery side of a rotor 1 to the suction side. At the time of starting or stopping, or during operations such as a defrosting operation, etc. where an abrupt change in pressure occurs, a force from the suction side to the delivery side can act on the rotor 1, and the force is received by a thrust bearing 4a. Since the thrust bearing 4a is ring-like, and its outer diameter is smaller than the diameter of root circle of the rotor and formed to be projected from the delivery casing 3, the tooth end face where land parts and groove parts alternate and an oil film is difficult to be formed, does not contact the casing 3, and the rotor 1 is supported by the root circle of the rotor 1 where load faces are formed continuously. As a result, a reliable thrust bearing 4a capable of preventing seizure of the rotor end face can be obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a screw compressor used in refrigeration/air conditioning equipment, etc. Regarding thrust bearing structure.

[Conventional technology]

Conventionally, as a structure to prevent seizure between the rotor end face and the casing of a screw compressor, Japanese Patent Application Laid-Open No. 60-2488
As described in No. 9, it is known to apply a heat-resistant resin coating to the entire end surface of the casing.

[Problem to be solved by the invention]

The above conventional technology does not take into consideration the fact that land portions and groove portions are intermittently formed on the outer diameter side of the end face of the screw rotor, and there is a problem in that seizure is likely to occur due to lack of oil film in this portion.

An object of the present invention is to provide a highly reliable thrust bearing structure that prevents seizure of the rotor end face.

[Means for Solving Problem 1] The above object is to provide a ring-shaped thrust bearing whose outer diameter is smaller than the root diameter of the rotor in the casing facing the discharge side end surface of the rotor, and to insert the thrust bearing from the casing surface. This is achieved by forming it convexly. In addition, the object can be similarly achieved by forming the portion near the tooth bottom of the rotor's discharge side end surface to be more convex than the land portion of the rotor; The same effect can also be achieved by forming a film layer containing a highly lubricating material such as molybdenum disulfide on the surface.

[Effect]

When a force is applied to the screw rotor in the direction of the discharge side,
The discharge side end surface of the rotor is supported by a thrust bearing provided on the Keirin. Since the outer diameter of the thrust bearing is formed into a ring shape smaller than the tooth bottom diameter of the rotor, an oil film is likely to be formed thereon, and since the thrust bearing is formed to be convex than the surface of the casing, The tooth end face of the screw rotor never comes into contact with the casing.

A structure in which a ring-shaped convex portion smaller than the tooth bottom diameter is provided on the discharge side end face of the rotor also has the same effect as described above.

Furthermore, in a rotor in which a highly lubricating film layer is formed on the surface of the ring-shaped convex portion, even if an excessive load is applied to the rotor and the oil film is broken, the function of the thrust bearing can be maintained without seizing.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1, 2, and 3.
This will be explained using figures.

Figure 1 is an enlarged sectional view of the male rotor discharge side of a screw compressor to which the present invention is applied, Figure 2 is a right side view of the male rotor, and Figure 3 is a right side view of the male rotor.
The figure is a longitudinal sectional view of a screw compressor.

1 to 3, a male rotor 1 and a female rotor (not shown) are meshed with each other to form a main casing 2. It is housed in the discharge casing 3. An electric motor 7 directly connected to the male rotor 1 is disposed in the main casing 2, and a suction port 8 is formed therein. The discharge casing 3 is provided with a discharge port 9 communicating with a discharge chamber 10 containing an oil separation element 11.

On the discharge side of the male rotor, there is a thrust bearing 50 that supports the load from the discharge side of the rotor toward the suction side. A runner 6 is provided, and a thrust bearing 4a integrally molded with the radial bearing 4 is also provided.

The thrust bearing 4a has a ring shape with an inner diameter substantially equal to the shaft 1a of the male rotor, and an outer diameter smaller than the tooth bottom diameter, as shown by a dashed line 41 in FIG. Further, the thrust bearing 4a is formed to be more convex than the surface of the discharge casing 3.

In the screw compressor configured as described above, the male rotor 1 is rotated by the electric motor 7 while meshing with the female rotor. Due to the rotation of the rotor.

Gas is drawn in through the suction port 8, compressed and expelled through the discharge port 9 into the discharge chamber 10.

During normal operation, since the discharge pressure is higher than the suction pressure, a thrust force acts on the rotor from the discharge side toward the suction side, and this thrust force is supported by the thrust bearing 5.

When the rotor is started, stopped, or when there is a sudden pressure change such as during defrosting operation of an air conditioner, a force may be applied to the rotor from the suction side to the discharge side. This force is supported by the thrust bearing 4a.

According to this embodiment, the thrust bearing 4a is formed into a ring shape with an outer diameter smaller than the root diameter of the screw rotor and is formed to be more convex than the discharge casing 3, so that the land portion and the groove portion are discontinuous. A highly reliable thrust bearing can be obtained because the tooth end face on which an oil film is difficult to form does not come into contact with the casing and is supported by the bottom of the rotor tooth where the load surface is continuous.

FIG. 4 shows another embodiment of the present invention, showing the discharge side end face of the male rotor.

A ring-shaped convex portion 1b having an outer diameter smaller than the root circle is provided on the discharge side end surface of the male rotor 1.

The surface of the thrust bearing 4a provided in the casing 3 is finished to be the same surface as the surface of the casing 3. According to this embodiment, the surfaces of the casing 3 and the thrust bearing 4a are the same surface that can be easily machined. It is possible to obtain the same effect as in the embodiment described above.

FIG. 5 shows still another embodiment of the present invention, showing the discharge side end face of the male rotor.

A ring-shaped convex portion 1b is provided on the discharge side end surface of the male rotor 1, and the outer diameter is smaller than the root circle.
For example, the film layer 1c is formed of a highly lubricating material such as molybdenum disulfide.

The discharge casing 3 facing the screw rotor is not particularly provided with a thrust bearing.

According to this embodiment, since a highly lubricating film is formed on the ring-shaped convex portion provided on the end surface of the discharge side of the screw rotor, there is no need to provide a thrust shaft on the discharge casing side. You can get the same effect as .

〔Effect of the invention〕

According to the present invention, it is possible to prevent the discharge side end face of the screw rotor from seizing due to metal contact with a simple structure, and therefore it is possible to provide a highly reliable screw compressor.

[Brief explanation of the drawing]

FIG. 1 is an enlarged sectional view of the discharge side end face of a male rotor according to an embodiment of the present invention, FIG. 2 is a right side view of the male rotor in FIG. 1, and FIG.
The figure is a longitudinal sectional view of a screw compressor to which the present invention is applied, FIG. 4 is an enlarged sectional view of the Usui rotor discharge side end face of another embodiment, and FIG. 5 is a male rotor discharge side showing still another embodiment. FIG. 3 is an enlarged sectional view of a side end surface portion. DESCRIPTION OF SYMBOLS 1... Male rotor, 2... Casing, 3... Discharge casing, 4... Radial bearing, 4a... Thrust bearing. Vine l Eye 2nd mouth 3rd eye 4th mouth

Claims (1)

[Claims] 1. A pair of male and female rotors each having a spiral land portion and a groove are rotatably housed in a casing, and a working chamber is formed by both rotors and the casing, and the gas trapped in the working chamber is removed. In a screw compressor that compresses as the rotor rotates and discharges from the discharge port, a screw compressor is formed on the casing facing the discharge side end surface of the rotor, the outer diameter of which is smaller than the tooth bottom diameter of the screwer and which is convex from the casing surface. A screw compressor characterized by being equipped with a ring-shaped thrust bearing.