Screw compressor

Abstract

Screw compressor having male- and female rotors for extremely high discharge pressures, the radial bearings and the supporting flanges enclosing the radial bearings tight-fitting adjoin the housing bores with their centres arranged on two parallel axes of the housing.

Description

The invention relates to a design of screw compressor housing for compressing a working fluid to an extremely high discharge pressure featuring two rotors with parallel axes, a male rotor having essentially convex-shaped lobe flanks with at least four lobes and a female rotor having essentially. The male rotor has a drive-shaft end. Both rotors are enclosed in a housing featuring at least an inlet port for passing of the working fluid into the lobes of the rotor pair and at least an outlet port for discharge of the gas out of the lobes of the rotor pair due to rotation of the rotors. The profile sections of the rotors have shaft ends enclosed in radial bearings. The resulting axial forces of the rotors are being supported by axial bearings. The profile section of the rotors is extremely short, as described in U.S. Pat. No. 4,412,796, U.S. Pat. No. 3,787,154, U.S. Pat. No. 4,080,119, U.S. Pat. No. 5,269,667. The axial length of the profile section of the rotor pair corresponds to approx. 1.4 the value of the axial lobe pitch which corresponds to the axial distance between two lobe-flank points of neighbouring lobe flanks. Known compressors have several housing sections accommodating the bearings of the rotors. These housing sections are connected with each other by suitable means after having been fixed at reference points. (U.S. Pat. No. 4,042,310, U.S. Pat. No. 4,004,864, U.S. Pat. No. 4,084,405, U.S. Pat. No. 4,455,131, U.S. Pat. No. 4,597,726, US This configuration leads needs expensive alignment or it causes to impermissible inclined positions of the bearings, if there are rotors with very short profile sections e.g. male rotor profile length to outer diameter ratio of 0.35, as the axial distance between the radial bearings arranged on both sides of the rotors is very short.

This has an impermissible impact on both the service life and load-carrying capacity of the bearings.

The feature of the invention is that all built-in components radial bearing housings enclosing the rotor profile and the rotor shafts are arranged in housing bores which centres are all arranged on two parallel axes. Built-in components are supporting flanges for the radial bearings on the suction side, and for the radial bearings on the discharge side. The build in components are concentric arranged in supporting flanges. Due to the features of the invention the machining of the rotor—housing bores—is possible from one side of the rotor housing in concentric manner which guarantee highest machining accuracy.

Due to this configuration, the bearings and the components like supporting flanges adjacent to the bearings are guided at their periphery in the same housing concentric sections so that there will be no coaxial deviations from coaxial position of rotor caused by assembly.

Advantageously the assembling of supporting flanges, male and female rotor and bearings is possible with out alignment and with out adjustment from one side of the housing.

The FIG. 1 shows cross section through the screw compressor regarding the invention.

FIG. 2 shows a sample of a rotor pair consisting of male and female regarding the invention.

FIG. 3 shows the outer shape of a sample of a screw compressor regarding the invention.

The screw compressor shown in FIG. 1 designed for compression of a working fluid to a discharge pressure of 120 bar featuring two rotors, a male rotor 1 and a female rotor 2 with the male rotor 1 having a drive-shaft end 3, and both rotors are enclosed in a housing 8 featuring an inlet port 7 which is connected with a not shown suction flange for passing of the working fluid into the cavities 12, 13 of the rotor pair and an outlet port 14 for discharge of the gas out of the cavities of the rotor pair due to rotation of the rotors. The profile sections 15 of the rotors have shaft shoulders 4 enclosed in radial bearings 5 on the suction side and in radial bearings 9 on the discharge side with the resulting axial forces being supported by axial bearings 6. The supporting flanges 10 adjacent to the radial bearings are guided at their periphery in the housing 8 so that there will arise no coaxial deviations caused by assembly. The supporting flanges 10 are axially fixed by the end housing 11.

Regarding FIG. 2 the wrap angle 13 of male rotor 1 is about 100°. Caused by teeth ration 5:6 between male and female teeth index angle 12 between neighbouring teeth of male rotor 1 is 72°. The rotor length 17 is short related to male rotor diameter 16.

In FIG. 3 is shown the economiser port 14 located on the part of the surroundings of the rotor pair.

List of reference numerals used:

• 1 Male rotor
• 2 Female rotor
• 3 Drive-shaft end
• 4 Shaft shoulders
• 5 Radial bearing, suction side
• 6 Axial bearing
• 7 Inlet port
• 8 Housing
• 9 Radial bearing, discharge side
• 10 Supporting flanges
• 11 End housing
• 12 teeth index angle
• 13 wrap angle male rotor
• 16 male rotor diameter
• 17 rotor length

Claims

1. Screw compressors for extremely high discharge pressures up to 160 bar featuring two parallel rotors, a male rotor and a female rotor with the male rotor having a drive-shaft end for drive of the compressor linguine or electric motor, and both rotors are enclosed in a housing having an inlet port and an outlet port, rotors with profile sections and shaft ends enclosed in radial bearings and with axial bearings wherein radial bearings and supporting flanges enclosing the radial bearings tight-fitting adjoin the housing bores the centres of which are arranged on two parallel axes of the housing.

2. Screw compressor according to claim 1 wherein the outer races 15, 16 of the radial bearings on the compressor suction side directly adjoin the housing.

3. Screw compressor according to claim 1 wherein the outer races of the radial bearings on the discharge side tight-fitting adjoin concentric supporting flanges.

4. Screw compressor according to claim 1 wherein the supporting flanges axially adjoin the end housing.