JPS59176489A - Screw fluid machine - Google Patents

Abstract

PURPOSE:To decrease the transmission error of a timing gear, reduce the clearance between rotors, and obtain a single-stage oil-free screw compressor with high performance and high reliability by adjacently arranging a radial bearing and the timing gear. CONSTITUTION:A thrust bearing 70 of a male rotor 1 is arranged at the end of an axis adjacently to the drive side, i.e., a pinion gear 11. The thrust force of a female rotor 2 is supported by an angular ball bearing 60 of the suction side. Accordingly, timing gears 9, 10 can be arranged adjacently to a radial bearing 6 of the discharge side. Thereby, an increase of the end surface clearance during operation can be prevented, and in addition, the axial action can be decreased by suppressing the axial displacement of the timing gear portion to a low level and as a result, the clearance between rotors can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to screw fluid machines in general, and particularly to a single-stage oil-free screw compressor which has severe operating conditions and requires high-speed operation.

[Background of the Invention 1] 1. The overall structure of an oil-free screw compressor will be explained with reference to FIG. 1. A male rotor 1 and a female rotor 2 are housed in a casing in a meshed state. The casing consists of a suction casing 4, a discharge casing 3, and an end wall 5. Both rotors are housed in the discharge casing 3, the suction casing 4 is arranged at the suction side end, and the rotor shafts Is, 2
It is inserted into the shaft seal material 8 placed in the shaft penetration part of the S, lcl, and 2di casings, and this shaft seal 8 seals the compressed air and seals the oil sent to the bearing.

Furthermore, the radial load of both rotors is supported by a bearing 6, and the thrust load is supported by a bearing 7, respectively. A pair of timing gears 9 and 10 are disposed in mesh with each other at the discharge l1ll@ ends of the male rotor and the female rotor, and the two rotors are arranged to rotate without contacting each other. A pinion 11 is attached to the ISO shaft end of the male rotor on the suction side, and is driven by a pull gear (not shown). When rotational force is transmitted to the pinion 11 from the drive source, the pair of male and female rotors rotate synchronously while maintaining a small gap by the timing gears 9 and 10. As a result, the intake air passes through a suction passage (not shown) and is drawn into the intake space formed by the tooth profiles of both rotors, and as both rotors rotate, the tooth profile space gradually decreases and the sealed air is discharged.
The compressed air is discharged from a discharge boat (not shown) and used for various purposes.

In the prior art, as shown in FIG. 1, a sluth bridge was placed on the high pressure side of the compressor. Therefore, the temperature of the rotor increases during operation, and the clearance between the high-pressure side end face of the rotor and the casing wall (hereinafter referred to as end face clearance) increases due to thermal expansion, resulting in a decrease in performance. Furthermore, since the timing gear was located far away from the radial bearing, the shaft displacement of the timing gear portion due to the gas load was large, causing shaft vibration. When the displacement of the timing gear section becomes large, even if the annual salary accuracy of the gear is high, the 1st station becomes irregular. This means that the timing gear's rotational transmission error (advance/delay in the female rotor's rotational direction when the male rotor is rotated at one rotational speed and the female rotor is driven) becomes large. As a result, when the inter-rotor clearance is reduced in order to improve performance, the rotors come into contact with each other and burnout occurs, which reduces the inter-rotor clearance and thus impedes performance improvement.

[Purpose of the invention]

An object of the present invention is to provide a high-performance, highly reliable single-stage oil-free screw compressor that reduces inter-rotor clearance by increasing end face clearance and reducing shaft vibration due to rise in rotor temperature.

[Summary of the invention]

The present invention is characterized in that the timing gear is disposed as close to the radial bearing as possible to reduce shaft displacement in order to suppress the rotation transmission error of the timing gear.

[Embodiments of the invention]

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

The thrust bearing 7o of the male rotor 1 is disposed on the drive side, that is, at the shaft end adjacent to the pinion gear IIK.

Further, the thrust force of the female rotor 2 is supported by an angular ball bearing 60 on the suction side. By doing so, the timing gears 9, 1 (l) can be placed adjacent to the discharge side radial bearing 6.

Figure g3 shows the meshing state between the pinion gear 11 and the pull gear 300. A portion of the casing 40 is cut out, exposing a portion of the pinion gear 11. That is, the pinion gear 11 meshes with the pull gear 300 in the state shown in FIG. 3, and is driven by a drive source (not shown).

In the conventional technology, the thrust bearing 7 was placed on the discharge side (see Fig. 1), so the end face clearance B in Fig. 2 increases due to thermal expansion when the compressor is operated and the rotor temperature rises, and the compressor performance deteriorates. On the other hand, in the case of the present invention, the thrust bearings 60 and 70 are arranged on the suction side (second
(see figure), the end face clearance B often decreases during compressor operation, contrary to the case of the prior art.
It becomes possible to provide a high-efficiency compressor. In addition, in the case of the present invention, as shown in FIG.
The end face clearance B can be arbitrarily changed by adjusting the thickness of the spacers 220, 120, that is, the values of A and C.

Next, we will explain the difference between the present invention and the prior art with reference to FIG.
As a result, an axial displacement δ occurs in the rotor. In the present invention, since the timing gear is arranged adjacent to the radial bearing on the discharge side, the axial displacement of the timing gear part is 3 ri.
δ2 in the case of the prior art is obviously smaller. As a result of trial calculation of the numerical value, δ1/δ2 < 0.5, and in the case of the present invention, the axial displacement can be halved.

If the shaft displacement of the timing gear section becomes large, it will cause shaft vibration, and it will also prevent the reduction of the clearance between the rotors, which will be a major factor in reducing the efficiency of the compressor.

Moreover, no matter how high the processing precision of the timing gear is, it is meaningless.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to prevent an increase in the end face clearance during operation, and by suppressing the shaft displacement of the timing gear part, the shaft vibration is completely reduced, and as a result, it is possible to reduce the clearance between the rotors. . Therefore, a compressor with high efficiency and high reliability can be provided.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view showing the prior art, Fig. 2 is a cross-sectional view showing the present invention, Fig. 3 is an explanatory view of the pinion gear driving method, and Fig. 4 is an explanatory view of the axial displacement of the rotor. be.

Claims (1)

[Claims] 1. A male rotor and a female rotor are included in the casing,
A screw fluid machine in which each rotor rotates with a minute gap maintained by a timing gear, characterized in that a radial bearing and a timing gear are arranged adjacent to each other. 2. The first aspect is characterized in that a bearing that supports radial and thrust forces is used as the low-pressure side bearing of the female rotor.
Section Screw Fluid Machinery.