GB2234016A

GB2234016A - Rotor for a sliding-vane vacuum pump or compressor

Info

Publication number: GB2234016A
Application number: GB9013851A
Authority: GB
Inventors: Katharina Koterewa; Zwetko Zwetkow
Original assignee: Medizin und Labortechnik Leipzig VEB
Current assignee: Medizin und Labortechnik Leipzig VEB
Priority date: 1989-06-22
Filing date: 1990-06-21
Publication date: 1991-01-23
Also published as: FR2648873A1; DE4001691A1; DD299483A7; GB9013851D0

Abstract

The rotor 1 includes a hub comprising two rotor segments 2a, 2b separated by flange members 5a, 5b, thereby defining a slot therebetween through which the sliding vane 12 extends. The hub parts are clamped together by screws 3a, 3b and any part of bores 9a, 9b not occupied by the screws is filled with a filler material. The rotor segments 2a, 2b may also be glued to the flange members 5a, 5b. The vane may be in two halves 12a, 12b. <IMAGE>

Description

1 Rotor for a vacuum pump or compressor The invention relates to a rotor

for use in vacuum pumps or compressors.

In US-PS 27 82 725 a rotor is shown, comprising two parts that are joined to form a whole after their manufacture. The end faces of the rotor parts are provided with matching projections and recesses.

The disadvantage of this is that all of the parts have to be made extremely accurately, in order to eliminate excessively large tolerances, which would in turn require considerable reworking of the assembled rotor in order to ensure fault-free running of the rotor and perfect operation of the pump. The necessary financial and technical cost of the satisfactory manufacture of the rotor is relatively high.

In order to eliminate this disadvantage, the rotor shown in DE-PS 29 20 626 is assembled from two rotor parts, which are initially only roughly pre-drilled and are provided with slits for the sliding vane and bores for clamping screws. In one arrangement, each of the rotor parts is provided with a contact surface which is fully machined and completely overlaps the contact surface on the other rotor part. (i.e. lying one on top of the other and in full alignment).

During the finishing process the length and diameter of the rotor are completed. This rotor has considerable deficiencies. It is not applicable to all rotor sizes, in particular to small rotors. It requires an 2 extremely precise machining of the contact surf aces of the rotor halves, because otherwise there could be an overf low of air from one side of the pump chamber to the other.

A further disadvantage is given by the milling in of the slit portions f or the sliding vane. There is the danger that the walls of the slit portions will not run parallel but will form a cone and will not f it each other exactly.

The rotor parts are hardened after inserting the slit portions, whereby the material, and thus the slit portions, may shrink and twist.

The present invention provides a low-cost, uncomplicated rotor which may be used and manufactured in all of the sizes required for vacuum pumps and compressors.

The objects were to design a rotor f or vacuum pumps and compressors so that its components were at least partly standard, and to eliminate any damage, at least in normal operation, for even the smallest rotor sizes. Further objects were for the rotor to maintain its specified size and shape in use, and for reworking of the sliding vane slit and the bores for the screws to be unnecessary and to avoid rejects in manufacture.

According to the invention there is provided a rotor for a vacuum pump or compressor, comprising a hub and a sliding vane extending therethrough, the hub comprising two rotor segments separated by two flange members thereby defining a slot therebetween, through zl- 3 which the sliding vane extends.

In accordance with the invention the objects have been achieved by (1) fitting pivot pins on the end faces of the rotor, each with a f lange on their inner f aces bored radially radially of the ideal rotor axis (2) by providing rotor segments which have both been provided with a f lat guide for the sliding vane and/or the sliding vane halves which fit between the pivot pins and are adjacent to their inner surfaces and resting on the upper and lower faces of the flanges. By firmly connecting the pivot pins and the rotor segments with screws (4) by providing an air gap between the sides of the sliding vane and/or the sliding vane halves and one or both of the end edges of the f langes (5) by f illing the parts of the bores in the rotor segments not filled by the screws with a filling substance. and by gluing the rotor segments to the flanges.

The invention will be described together with the drawings by way of an embodiment. In which:

Figure 1 shows a section through a rotor built into a pump casing; and Figure 2 shows an exploded diagram of the parts of the rotor in perspective.

The two pivot pins la, 1b and the rotor segments 21,2b are joined to form the rotor 1 by screws 3a,3b.

Flat flanges Sa,5b are formed by milling the inner surfaces 4a,4b of the pivot pins la,lb. Each flange which is provided with a bore 7a,7b for the screws X 4 3a,3b which is formed radially of the ideal longitudinal axis 6 of the rotor 1. The rotor segments 2a,2b are made from rounded material and are each equipped with a flat slide 8a,8b and two bores 9a,9b running radially of the longitudinal axis 6. The ends of slide 8a,8b are so placed on the flanges 5a,5b that their end surfaces 10a, 10b touch the inner surfaces 4a, 4b of the pivot pins la, Ib and the bores 7a and 9a and 7b and 9b each form a passage for the screws 3a,3b. After inserting the screws 3a,3b into the passages they are firmly tightened, and in conjunction with the thread in the bores 9b, make an immovable connection between the pivot pins la, Ib and the rotor segments 2a,2b.

The portions of the slides 8a,8b not bearing on the flanges 5a,5b form guide surfaces for the sliding surfaces 11 of the sliding vane 12 and/or the sliding vane halves 12a,12b. The side edges 13 of the sliding vane 12 and/or of the sliding vane halves 12a, 12b are guided by the side walls 14 of the pump chamber 15. The portions of the bores 9a,9b not filled by the screws 3a,3b represent damaging areas and are filled with resin 20 in order to eliminate the known disadvantages resulting from these areas.

Should the necessity arise for the parts of the rotor to be connected by further fixing means in addition to the screws 3a,3b, then this may be effected, for example, with the aid of glue, which is applied, before screwing the screws 3a,3b, into the upper and lower faces of the flanges 5a,5b, and to the portions of the sliding tracks 8a,8b, and/or to the inner surfaces 4a,4b and the end surfaces 10,10b. A special clamping 1 device for holding together the rotor parts until the glue has set is not necessary; the screws 3a, 3b are quite sufficient for this.

The manufacture of the individual components takes place using known technologies. The pivot pins la, 1b are initially made as turned parts. Then, the milling of the flanges Sa,5b is carried out with an interlocking side milling cutter (straddle cutter), after which the bores 7a, 7b are f ormed. Then, both rotor segments 2a..2b, formed from a semi- circular profile rod, are given bores 9a,9b. While the bore 9a on the curved f ace of the rotor segment is provided with an extended recess f or the head of the screws 3a,3b, the bore 9b is given a threaded portion for the screws, or is provided with a continuous thread.

In order that the rotor parts may be assembled accurately to size, and any tolerances which may have arisen during manufacture of the individual parts may be met, the bores 7a and/or 9a have been given a slightly larger diameter than the screws 3a,3b. Since the rotor is assembled in an arrangement, which is not specifically shown, the finished rotor will not have any size differences.

i Before assembly, the slides 8a,8b and the end surfaces 10a,10b of the rotor segments 2a,2b are precision ground, which is important since the slides also define the thickness of the guide slit 16, which corresponds to the thickness of the sliding vane 12 and/or the sliding vane halves 12a,12b which rest on each other.

The width of the guide slit 16 is limited by the end edges 17a,17b of the flanges 5a,5b.The side edges 13 6 of the sliding vane 12 and/or the sliding vane halves 12a, 12b however do not usually lie on the end edges 17a, 17b. Between then is located rather an air gap. The sliding vane and/or the sliding vane halves is/are laterally secured by the side walls 14. By abutting these parts against the side walls 14 short-circuiting between the suction side and the compression side of the pump chamber 15 is prevented at these points. Small inaccuracies in the length of the flanges 5a,5b or of the installation size of the rotor towards its axis 6 are compensated by air gaps 18, without there being any f ear of leaks between the two sides of the pump chamber 15.

If, contrary to expectations, it is necessary to undertaking reworking of the periphery of the rotor 1, then this may be clamped into a machine tool by its centring elements 19 and either redrilled or reground.

other reworking may be regarded as unnecessary in this. rotor.

f 7 claims 1. A rotor for a vacuum pump or compressor, comprising a hub and a sliding vane extending therethrough, the hub comprising two rotor segments separated by two flange members thereby defining a slot therebetween, through which the sliding vane extends.

Claims

2. A rotor according to Claim 1, wherein there is a gap between the edges

of the flange member that define the slot, and the edges of the sliding vane.

3. A rotor according to Claims 1 or 2, wherein the slot and sliding vane are rectangplar in cross section.

4. A rotor according to any preceding Claim, wherein the faces of the rotor segments that define the slot are adapted to allow the sliding vane to slide thereacross.

5. A rotor according to Claim 4, wherein the separation between said faces is substantially equal to the thickness of the sliding vane.

6. A rotor according to any preceding Claim, wherein there are bores extending through the hub, the flange members and the rotor segments, and the hub is held together by a plurality of screws.

7. A rotor according to Claim 6.-. wherein any part of the bores not occupied by the screws, is filled with filler material.

t_ a 8. A rotor according to any preceding claim, wherein the rotor segments are glued to the flange members.

9. A rotor according to any preceding Claim, wherein the sliding vane comprises two sliding vane halves.

10. A rotor for a vacuum pump or compressor, comprising a hub and a sliding vane extending therethrough, the hub having a slot extending fright through it, through the centre thereof, through which the sliding vane extends, wherein the sliding vane can move laterally and longitudinally in the slot.

11. A rotor for a vacuum pump or compressor substantially as described herein, with reference to the drawings.

7 Published 1991 at 7be Patent Office. State House. 66/71 High Holborn. London WCIR47P. Further copies may be obtained from Sales Branch. Unit6. Nine Mile Point Cwmfelinfach. Cross Keys, Newport. NPI 7HZ. printed by Multiplex techniques ltd, St Mazy Cray. Kent