JPS58200093A - Screw type fluid machine - Google Patents

Abstract

PURPOSE:To reduce the noise of a screw type fluid machine and to improve its performance, by attaching a vibration-damping member to one end of either of two rotor shafts, and thereby damping radial vibration of two rotors. CONSTITUTION:When a compressor is set into rated operation, one end portion 2d1 of the shaft of a female rotor 2 tends to cause radial vibration almost in the state of resonance. However, since the radial vibration is damped by a vibration-damping member 13 attached to the outer circumference of a bearing 12, vibration of the end portion 2d1 of the shaft of the female rotor 2 can be damped. Thus, since the vibrational energy is absorbed by the vibration-damping member 13, almost no vibration is caused at the portion of the shaft of the female rotor 2 located on the left side of the end portion 2d1. Therefore, it is enabled to reduce the noise of a screw type fluid machine and to improve its performance.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a screw fluid machine, particularly a roller bearing t*L
This invention relates to an oil-free screw compressor operated at high speed.

It is common practice to make improvements to the circumference d of a rolling bearing to make the characteristics of the support structure as a whole effective in reducing vibrations. However, most of the known examples are machines consisting of a single shaft, in which a vibration distribution mechanism is provided on the outer periphery of a radial bearing. is hardly an issue.

However, in a screw fluid machine, that is, a compressor that has a structure in which a female rotor and a male rotor are mounted on two shafts and are meshed with each other, especially an oil-free screw pressure S machine in which both rotors rotate without contact, the rotation speed is quite constant. Since the gap between the meshing portion of the male rotor and female rotor is small in terms of numbers, damping of shaft vibration is essential.

Such a conventional oil-less screw compressor t [1 As shown in Figure 1, a suction cage/g 3a, a discharge casing 3
It is composed of a casing 3 consisting of an end cover 3C and an end cover 3C, and a mausoleum rotor l and a female rotor 2 which are housed in the casing 3 and mesh with each other. That is, both the rotors l.

2 is housed in the discharge casing 3b, and the suction casing 3a is attached to the suction side end of the suction cage/gage 3a.
Both rotor shafts Is, 2s machining 1d, 2d are inserted into the shaft seal 8a provided in the inner shaft penetration part and the shaft seal 8b provided in the shaft penetration part on the side opposite to the suction casing in the discharge casing 3b. I'm here.

The shaft seals 9a and $b seal compressed air and oil supplied to the bearings 6.7, which are connected to both rotors 1.
．． The radial load storm and thrust load acting on 2 are supported respectively. Timing gears 9°10 that mesh with each other are attached to the discharge side shafts 1d and 2d (Dls parts) of the male rotor 1 and the female rotor 2, and both rotors 1,
2 are arranged so as to rotate in a non-contact manner.

Further, a pinion 11 that is connected to a drive source (not shown) is attached to the ISO end of the suction side shaft of the mausoleum rotor 1.

When the above-mentioned pinion 11 is rotated by the drive source, the pair of female rotors 1 and 2 rotate synchronously while maintaining a very small distance through the timing gear 9°10t. is sucked into the suction space formed by the teeth of both rotors 1 and 2 through a suction passage (not shown). Both rotors1.
As the tooth shape space gradually decreases as the tooth shape space rotates, the air sealed in the tooth shape space is compressed and discharged from a discharge boat (not shown) to be used for various purposes.

However, oil-free screw compressors cannot achieve desirable performance unless operated at high speeds, so both rotors 1.
2 has the disadvantage of easily generating shaft vibration. If the amplitude of this radial vibration of the rotor increases, there is a risk that the two rotors 1.2 will come into contact with each other.

Therefore, in order to achieve high performance by reducing the minute gap between the meshing parts of both rotors 1 and 2, it is essential to take measures to suppress the radial vibration of the rotor. This becomes a problem in the case of a single-stage compressor. This is because the bearing rigidity is low and the pressure ratio causes large load fluctuations in the compressed gas, which becomes an excitation force.

Since the radial bearing needs to be supported by a rigid body, it is not possible to provide an allocation mechanism on the outer periphery of the radial bearing as in the conventional example. Furthermore, in order to suppress the radial vibration of the rotor, it is desirable to reduce the radial clearance of the bearing as much as possible, but from the standpoint of bearing reliability, it is impossible to reduce the radial clearance of the bearing alone. .

In view of the above, it is an object of the present invention to provide a low-noise, high-performance screw fluid machine that suppresses the radial vibration of both rotors. In the screw fluid machine that is housed, an allocation member is attached to at least one force shaft end of the two rotors.

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

Among the reference numerals shown in FIG. 2, the reference numerals shown in FIG.

In FIG. 2, 2d is a discharge side shaft of the female rotor 2, and the leading end of this shaft 2d is formed into a small diameter shaft 2d. The specifications of the small diameter shaft 2d, namely the moment of inertia, length, and mass including the final end bearing, are designed to be equal to the natural bending frequency of the female rotor shaft system. 12 is a bearing fitted into the small diameter portion 2dl of the female rotor shaft 2d, and 13 is a known vibration member, such as a laminated damper or an oil damper, interposed between the inner part 1i 3't of the end cover 3C and the bearing 12. This is a squeeze film damper, and oil is supplied to this distribution member 13 from an oil supply hole (not shown).

14 is a 7-lunge that closes the opening of the end cover 3C. The rest of the structure is the same as the conventional example shown in Figure 1.

Oka-, so the explanation will be omitted.

This embodiment has the above-described configuration.9 When the compressor is operated at its rated value, the shaft end 2d1 of the female rotor 2 tries to vibrate in the radial direction in a state close to resonance. Since the damping effect is applied by the damping member 13, the vibration of the shaft end portion 2d1 can be suppressed. In this way, the vibration energy of the shaft end 2d1 of the female rotor shaft 2d is absorbed by the allocation member 13, so that the shaft end 2d of the female rotor 2, the left III (suction side) part hardly vibrates. .

Although the above-described embodiments have been described with respect to an oil-free screw compressor, the present invention is not limited thereto and can also be applied to a general screw compressor. Further, although the allocation member 13 is attached to the shaft 2d of the female rotor 2, the same functions and effects can be obtained even if the allocation member 13 is attached to the shaft 1d of the male rotor 1. Of course, it will be even more effective if vibration damping members 13 are attached to both shafts 2d and ld of the female and s2°1.

As explained above, according to the present invention, it is possible to suppress the radial vibration of the rotor and further reduce the gap t between the meshing portions of both rotors, thereby reducing noise and improving performance. can.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a conventional oil-free screw compressor, and FIG. 2 is a cross-sectional view showing an embodiment of the screw fluid machine of the present invention. 1...Jiota, 2...Female rotor, 1d, 2d.
...Rotor shaft, 3...Casing, 12...Bearing,
13... Allocation member.

Claims (1)

[Claims] 1. A pair of females interlocking with each other within the casing. In a screw fluid machine that houses a mausoleum rotor,
1-** A screw fluid machine, wherein an allocation member is attached to the shaft end of at least one of the two rotors. 2. A screw fluid machine according to claim MIJJ, in which the use of a dynamic pumper as an allocation member is a characteristic feature.