GB2140089A

GB2140089A - Sliding-vane rotary compressor

Info

Publication number: GB2140089A
Application number: GB08412720A
Authority: GB
Inventors: Hiroshi Sakamaki; Sasumu Sugishita; Yukio Horikoshi
Original assignee: Nippon Piston Ring Co Ltd
Current assignee: Nippon Piston Ring Co Ltd
Priority date: 1983-05-20
Filing date: 1984-05-18
Publication date: 1984-11-21
Also published as: DE3418251A1; GB8412720D0; JPS59213968A; GB2140089B

Abstract

To reduce friction between the vanes 16 and the rotor 10 the walls of the vane grooves 15 are coated with a metal oxide 1. The oxide may be formed by anodic treatment of the groove walls. Preferably, the rotor is made of aluminium and the vanes are made of carbon. The entire rotor may be anodically oxidized and, saving the groove walls, thereafter covered with a layer of resin e.g. a polyimide, polyester, phenol, or polytetrafluoroethylene resin, Fig. 4, so as to reduce friction between the rotor and the casing. The radically outer edges of the vanes may engage with a rotary casing- liner, or "sleeve", 30 supported by an air bearing 40, to further reduce friction. <IMAGE>

Description

SPECIFICATION Rotary fluid pump The present invention relates to an improved construction for the rotor of a vane-type rotary compressor.

Rotary compressors have been widely used in industrial applications for the compression of fluids and gases. Prior art compressors have been relatively heavy and a longstanding effort has been made to construct a lightweight compressor that still provides high performance characteristics with a minimum of maintenance. To that end, the rotor in a vane-type rotary pump must rotate smoothly.

Efforts to use aluminium rotors have so far encountered problems with scuffing due to friction with the vanes in the rotor and due to friction between the rotor and the housing in which it rotates.

It is the principal object of the present invention to provide a rotor for a vane-type compressor wherein friction between the vanes and the rotor within the vane grooves is reduced.

An additional object of the invention is to reduce friction between the rotor and the housing in which it rotates.

These and other objects of the invention are achieved by providing a vane-type compressor having a rotor disposed to rotate eccentrically.

The rotor contains a plurality of grooves each disposed to contain a movable vane therein.

The surface of the grooves has a coating of metal oxide thereon. The compressor further includes a housing for containing the rotor.

Preferably, the rotor body is aluminium and the oxide coating is formed by anodic oxidation of the metal forming the grooves. It is further preferred that the vanes be comprised of carbon.

The invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a cross-sectional view of a vanetype rotary compressor constructed according to this invention, Figure 2 is a cross-sectional view taken along the line A-A' of Fig. 1, Figure 3 is an end view of a rotor whose vane grooves have an anodic film formed thereon, and Figure 4 is an end view of a rotor wherein all the surfaces of the rotor except the vane grooves have a resin coating.

The present invention provides an improved vane-type compressor exhibiting reduced internal friction due to the coating of specific portions of the device.

The compressor includes a rotor body 10 disposed to rotate eccentrically. The rotor body contains a plurality of grooves, each containing a movable vane. As here embodied, the rotor body 10 has a number of radially oriented vane grooves 1 5 disposed therein. As shown most dearly in Fig. 2 each vane groove 1 5 is disposed to contain a movable vane 1 6. Rotation of the eccentrically mounted rotor body 10 results in the vanes 16 moving radially within the vane grooves 1 5 and subjects the vanes to bending loads due to frictional resistance of the vane tips against the interior of the compressor housing.

The surface of each of the vane grooves has a coating of a metal oxide thereon. As here embodied and most clearly depicted in Fig. 3, the rotor 10 has a coating 1 on the interior surface of the vane grooves 1 5. Preferably, the rotor body is of aluminum and the coating is produced by anodically oxidizing the surface of the metal forming the vane grooves.

Such a coating reduces friction with the vanes and in the case where the vanes are carbon, a particularly effective means of reducing vane friction is afforded by an anodized aluminum coating in the vane grooves.

The compressor further includes a shaft affixed to the rotor body at its axis of rotation.

As here embodied and depicted in Fig. 1, the shaft 1 2 is affixed to the rotor body 10 and supports the rotor body by means of the shaft's interface with a front bearing 1 8 and a rear bearing 19.

The compressor further includes a housing containing the rotor body and supporting the shaft. As here embodied, the housing is comprised of a front end housing 21 containing front bearing 18, and rear end housing 23 containing rear bearing 1 9. A central housing 22, depicted here, includes a rotary sleeve 30 that rotates within the central housing 22 by means of an air bearing. The vanes 16 contact the inner surface of the sleeve 30 to form the chambers that effect compression of the material passing through the compressor. The present invention, however, is also operable where the vanes 1 6 contact the inner surface of the housing without an intermediate rotating sleeve.

An additional means of reducing friction in a compressor of the type disclosed herein is to coat or impregnate the surface of the rotor body, except for the surface of the vane grooves, with a resin. In addition, the resin coating or resin impregnation is not applied to the shaft because coating of the shaft would change the shat dimensions and disturb the dimensional accuracy of the shaft and thereby affect the insertion of the bearings. Such a coating reduces scuffing where there is intermittent contact between the rotor and the housings or the rotatable sleeve and improves the durability of such devices.

As here embodied and depicted in Fig. 4, the rotor 10 0 includes an oxide layer 1 on the surface of the rotor, including the vane grooves 1 5 as well as a resin coating 2 on the remaining surface of the rotor. Specifically, the outer radial surface of the rotor includes the resin coating 2 while the vane grooves do not include such a coating.

Resins may be applied to the surface of the rotor by conventional means and the resins such as polyimide resin, polyester resin, phenol resin and polytetrafluoroethylene resin are effective with the present invention. In this case, the entire surface of the rotor is subjected to anodic oxidation treatment.

Such resins are most effective when they comprise a coating having a thickness in the range of from 0.01 to 0.25 mm.

The present invention will be more fully disclosed in connection with the embodiment of Figs. 1-4.

As shown in Figs. 1 and 2, a shaft 1 2 integral with the rotor 10 of a compressor is supported by bearings 1 8 and 1 9 provided in front and rear side housings 21 and 23, and a pulley 14, to which rotation is transmitted from an engine, is fitted to the end of the shaft on the front end thereof.

Vanes 1 6 are inserted in each of a plurality of vane grooves 1 5 on the rotor 10 so as to be movable, and the tips of vanes 1 6 are in contact with a rotary sleeve 30 encompassing the rotor 10.

The rotary sleeve 30 is installed in the center housing 22 interposing an air bearing chamber 40 between them. At the rear of the rear end housing 23, a rear cover 24 is fixed through a gasket, and the cover is provided with a delivery chamber 41 and a suction chamber 51. The delivery chamber 41 is connected with a delivery port 42 through a delivery valve 60, the delivery port being connected with a delivery side actuating chamber 43 formed between the rotor 10 and the rotary sleeve 30. There are provided vane groove back pressure passages 48 running from the delivery chamber 41 to the bottom of the vane grooves to lead delivery pressure to vane grooves 1 5 to promote radial projection of the vanes 16. The suction chamber 51 is connected with a suction side actuating chamber 53 on the opposite side through a suction port 52.On the sliding surfaces of front and rear end housings 21 and 23 against the rotary sleeve 30, there are provided circular grooves 26 in which an oil-free sliding member 25 is inserted.

Bolts 27 passing through the thick wall portion 28 of center housing 22 clamp the front and rear side housings 21 and 23, the center housing 22 and the rear cover 24 together in the axial direction. As shown in Fig. 1, a high-pressure bore 44 and a lowpressure bore 54 run from the delivery chamber 41 and the suction chamber 52 to the end face of the center housing 22 through the rear side housing 23. An inlet port 71 and an outlet port 72 extend in the axial direction from the end face of center housing 22 in contact with the high and low pressure bores.

The inlet port 71 and the outlet port 72 open on the inside surface of center housing 22 in the form of grooves, each of them connecting with the high-pressure bore 44 and the low-pressure bore 54 in the rear side housing 23, respectively.

Since the contact area on the inside surface of center housing 22 in contact with the rotary sleeve 30 exists on the delivery side, the air flow in the contact area is increased by installing the inlet port 71 and the outlet port 72 at the start and terminal points on the delivery side. However, when the position of contact area can be determined from the beginning, the inlet and outlet ports should be installed so as to agree with the contact area.

Because the rotary sleeve 30 rotates at a high speed and creates a suction effect on the inlet port 71, it is not required to connect the inlet port 71 with the delivery chamber of high pressure. Atmospheric air may be ingested through the inlet port by connecting it with the atmosphere. The air in the contact area can enter the suction side actuating chamber through the end face of rotary sleeve 30, so the outlet port 72 may be omitted.

The compressor of the present invention is an efficient means of compressing materials such as air and the supercharging of an internal combustion engine. The means of reducing friction both between the vanes and rotor and the rotor and housing render the compressor significantly more durable and maintenance free.

Claims

1. A vane-type compressor comprising: a) a motor body disposed to rotate eccentrically, said rotor body containing a plurality of grooves each disposed to contain a movable vane therein, at least the surface of said grooves having a coating of a metal oxide thereon; b) a shaft affixed to said rotor body at its axis of rotation; and c) a housing for containing said rotor body and supporting said shaft.

2. A compressor as claimed in claim 1, wherein said oxide coating is formed by anodic oxidation of the metal forming at least said grooves.

3. A compressor as claimed in claim 2, wherein said rotor body is comprised of aluminium.

4. A compressor as claimed in any one of claims 1 to 3, wherein said vanes are comprised of carbon.

5. A compressor as claimed in any one of the preceding claims, wherein the entire surface of said rotor is subjected to anodic oxidation treatment, and wherein the surface of said rotor body except for said grooves is covered with a layer of resin.

6. A compressor as claimed in any one of the preceding claims, wherein said pump in cludes a rotatable sleeve between said housing and said rotor body.

7. A compressor as claimed in claim 5 or claim 6, wherein said vanes are comprised of carbon.

8. A rotor assembly for a vane-type compressor, said rotor assembly comprising: a) a generally cylindrical rotor body disposed to rotate eccentrically in said compressor, said rotor body having a plurality of generally radially orientated grooves therein, each of said grooves being disposed to contain a movable vane therein, at least the surface of said grooves having an anodically produced oxide coating thereon to reduce friction between said vane and said groove; b) a shaft affixed to said rotor body at its axis of rotation; and c) movable vanes in said grooves.

9. A rotor assembly as claimed in claim 8, wherein said vanes are comprised of carbon.

10. A rotor assembly as claimed in claim 8 or claim 9, wherein said rotor body is comprised of aluminum.

11. A rotor assembly as claimed in any one of claims 8 to 10, wherein the entire surface of said rotor is subjected to anodic oxidation treatment, and wherein the surface of said rotor body, except said grooves, are coated with a layer of resin.

12. A vane-type compressor substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

1 3. A rotor assembly for a vane type compressor substantially as hereinbefore described with reference to and as shown in the accompanying drawings.