JPS58222993A - Screw hydraulic machine - Google Patents

Abstract

PURPOSE:To reduce the elastic deformation of the outer race of a thrust bearing mounted on one of both rotor shafts and prevent misalignment on assembling and to damp the rotor shaft vibration by press fitting a ring in said outer race and increasing its rigidity. CONSTITUTION:A reinforcing ring 12, which is press fitted in an outer race 7a of a thrust bearing 7 mounted on a female rotor shaft 2a, is axially clamped by a bearing retainer 11. But, since the reinforcing ring 12 increases the rigidity of the outer race 7a, the elastic deformation of the outer race 7a is greatly reduced. Press fitting the reinforcing ring 12 also prevents the misalignment on assembling to some extent, that damps the radial vibration of the rotor shaft 2a thereby further reducing the gap between the two rotors, thus reducing the noise, and providing higher performance than the conventional units.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a screw fluid machine, and particularly to an oil-free screw compressor having a rolling bearing and rotating at high speed.

As shown in Fig. 1, a conventional oil-free screw compressor houses a pair of mutually meshing male and female rotors 1 and 2 in a discharge casing 3, and a suction casing 4 is attached to the discharge casing 3. axis 1allb and 2
a, 2b are passed through the shaft sealing material 8 provided in the shaft penetration part of the casing 3.4, and the rotor shafts 1a, 2a are inserted into the radial bearing 6 and the thrust bearing 7, and the rotor 4M+
tb.

2b are respectively supported by radial bearings 6.

A binio/11 is attached to the end of the rotor 1liIIIllb, and timing gears 9 and 10 are attached to the ends of the rotor shafts 1a and 2a, respectively. The pair of timing gears 9 and 10 are in mesh with each other so that both rotors 1 and 2 rotate in a non-contact manner. The timing gears 9 and 10 are covered by an end cover 5 attached to the discharge side of the discharge casing 3.

When the pinion 11 is rotated by a drive source (not shown), both rotors 1 and 2 are rotated through a timing gear 9-10.
The rotors 1 and 2 rotate synchronously while maintaining a small gap, so that intake air is drawn into the space formed by the teeth of both rotors 1 and 2 through an intake passage (not shown). both rotors 1,
As the space is sequentially reduced as the number 2 rotates, the air sucked into the space is compressed and discharged from the n1 discharge port (not shown), and is used for moderate purposes.

However, if an oil-free screw compressor is not operated at high speed, not only the desired performance cannot be achieved, but the rotor shaft is likely to vibrate. If the amplitude of the radial vibration of the rotor becomes large, there is a risk that both rotors will come into contact with each other. Therefore, in order to obtain high performance by reducing the minute gap between the meshing portions of both rotors (hereinafter referred to as the inter-rotor gap), it is essential to take measures against radial vibration allocation.

In particular, the above radial imaging has a small capacity and a high pressure ratio.
This becomes a problem in the case of stage compressors. This is because the bearing rigidity is low and the compressed gas load fluctuations are large due to the high pressure ratio, and this large load fluctuation becomes an excitation force.

In particular, the thrust bearing on the female rotor side has a small load capacity and is therefore prone to elastic deformation. Further, since no restraining force acts on the outer ring of the thrust bearing, misalignment is likely to occur during assembly. These factors are major causes of shaft vibration during high-speed operation.

The purpose of the present invention is to suppress the radial vibration of the irrigation rotor as described above, and to provide a low-noise, high-performance screw fluid machine. A screw fluid machine supported by a bearing and a thrust bearing is characterized in that a ring is press-fitted into an outer ring of a thrust bearing which is attached to at least one of the two rotor shafts.

An embodiment of the present invention will be described below with reference to the drawings.

Among the reference numerals shown in FIG. 2, the same reference numerals as those shown in FIG. 1 refer to the same or corresponding parts.

In FIG. 2, 11 is a bearing holder for the thrust bearing 7;
2 is the outer ring 7 of the thrust bearing 7 mounted on the female rotor shaft 2a.
This is a reinforcing ring press-fitted into a.

The rest of the structure is the same as the conventional example shown in FIG.
Drawings and descriptions are omitted.

This example has the above structure υ, reinforcement y/1゛2itNl receiving '"□"K1" axis 7 direction 1 tightening +tub
,.

However, since the stiffness of the outer ring 7a is increased by the reinforcing ring 12, the elastic deformation of the outer ring 7a is very small. Further, by press-fitting the reinforcing ring 12, misalignment during assembly can be prevented to some extent, so that radial vibration &lI' of the rotor shaft 2a can be suppressed.

In this embodiment, the reinforcing ring 12 is attached to the thrust bearing 7 attached to the shaft end of the female rotor shaft 2a, but the same effect can be obtained by attaching the reinforcing ring to the thrust bearing attached to the shaft end of the male rotor shaft 1a instead. effective. Also, both rotor shafts 1a, 2
By attaching reinforcing rings to both thrust bearings attached to the shaft ends of a, there is an advantage that shaft vibration can be further suppressed.

As explained above, according to the present invention, the rigidity of a thrust bearing with a small load capacity can be increased by extremely simple means,
Misalignment during assembly can be prevented. Therefore, the shaft vibration of the rotor can be reduced, making it possible to further reduce the gap between the rotors compared to the conventional method, thereby making it possible to put into practical use a low-noise, high-performance screw fluid machine. be able to.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a conventional oil-free screw compressor, and FIG. 2 is an enlarged cross-sectional view of essential parts of an embodiment of the screw fluid machine of the present invention. 1a, 2a... Roll shaft, 7... Thrust bearing 7
a...Outer ring, 12...Ring.

Claims (1)

[Claims] In a screw fluid machine in which the shafts of a pair of mutually meshing female and male rotors are supported by radial bearings and thrust bearings, a ring is press-fitted into the outer ring of the thrust bearing mounted on at least one of the two rotor shafts. A screw fluid machine characterized by: