JPS58160621A - Bearing device for screw compressor - Google Patents

Abstract

PURPOSE:To lengthen the life of a bearing by supporting a radial load by means of a bearing with a small contact angle and supporting an axial load by means of a bearing with a large contact angle. CONSTITUTION:A contact angle alpha2 of bearings 72, 82 receiving an axial load is larger than a contact angle alpha1 of bearings 71, 81 mainly receiving a radial load. Further, inner races 71a and 72a of the bearings 71, 72 adhere closely to each other at their end faces and are fitted on the shaft of a rotor 2, while a minute gap is provided between outer races 71b and 72b so that each bearing is not pressurized during operation stoppage. Furthermore, an escape 4a is provided on the outer periphery of the outer race 72b of the bearing 72 mainly receiving the axial load so that the bearing 72 may not receive any radial load.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a screw compressor, and more particularly to a combination bearing device that supports a radial load and a thrust load.

Conventionally, angular contact ball bearings with the same contact angle have been used for combination bearings that support rotating shafts. When angular contact ball bearings support radial loads, axial loads are generated. However, when the contact angle is increased to withstand a large axial load, the axial load generated from the bearing receiving the radial load increases, which reduces the effect of increasing the contact angle. Furthermore, supporting a radial load with a bearing having a large contact angle tends to shorten the life of the bearing, which also poses a problem.

Here, if a cylindrical roller bearing is used as the bearing that receives the radial load, the life will be the most advantageous because no axial load will occur, but it will be extremely weak against the axial load in the opposite direction, and the compressor will start up. The use of frK is restricted in cases where an axial load in the opposite direction must be supported by the engagement of the rotor, such as when the rotor is stopped.

An object of the present invention is to provide a bearing device with a long bearing life, in which a bearing with a small contact angle supports a radial load, and a bearing with a large contact angle supports an axial load. It is characterized by reducing the axial load generated by the bearing that supports it.

An embodiment in which the present invention is applied to a screw compressor will be described below with reference to the drawings.

FIG. 1 is an overall sectional view. Screw compression IaFi
A pair of rotors (1) (2), a casing (3) (4) surrounding them and forming a compression chamber, and a rotor bearing device (5).
) (6) (Composed of 7 bar f9. Rotor (1) @
are provided with grooves that engage with each other while rotating, and the grooves and the casing create a compression chamber. Gas l? , air is sucked into the compression chamber from the inlet (9), is compressed, and then passes through the outlet (9).
1G). The rotors a) and @ receive a radial load in the direction in which the rotors (1) and (2) move away from each other and a 7-axial load in the direction from the discharge side to the suction side as compression reaction forces. The bearings (5) (6) ff bar... support these loads and also support the rotor (1) (2) casing (3) (
4) 0 parts with positioning function between (12) (13
) (14) and (15) are disc-shaped holding plates for the bearings (7) and (8), which are fastened to the casing (4) and rotors (1) and (2) with bolts, respectively.

The present invention relates to a bearing device (η(8)s).

As the details of the main parts are shown in Fig. 2, the contact angle α1 of the bearings (71) and (81) that receive the axial load and the radial load.
It has become larger by 1. In addition, the inner race (71a) of the bearing (71) and the inner race (7
2m) are attached to the shaft of the rotor 2 with their end faces in close contact with each other, and the outer race (71b) of the bearing (71) and the outer race (71b) of the bearing (72) are designed so that there is no difference between them.

Furthermore, the outer periphery of the outer race (72b) of the bearing (72), which mainly receives the axial load, has a relief of 4 m, so that the bearing (72) does not receive the radial load. Bearing that supports radial load pr (
71), (81)K Axial load generated p a /
It shows the size of , and is expressed as Fa'=Prtaaα weight.

From this formula, the bearing (71) that mainly receives radial load,
The contact angle αl of (81) is 1.2 for the axial S bearing.
・μ-ta, 3, 4...Casing, 5, 6...Cylindrical roller bearing, 71.81, 72.82...Angi 5-2
Combination bearing, 9...Suction port, lo...Discharge port, 11
-...Shaft cool, 12, 13, 14.15...Bearing holder, ・:

Claims (1)

[Claims] In a bearing structure in which angular contact ball bearings are combined as a bearing for a screw compressor, and a gap is provided between the outer ring of the bearing that supports the axial load and the housing,
A bearing device for a screw compressor, characterized in that the contact angle of the bearing supporting the axial load is larger than the contact angle of the remaining bearings.