GB2253679A

GB2253679A - Non-return valve for a compressor

Info

Publication number: GB2253679A
Application number: GB9203222A
Authority: GB
Inventors: Manfred Bauch; Heinrich Schlossarczyk; Jens Tiedmann
Original assignee: Wabco Standard GmbH; Wabco Westinghouse Fahrzeugbremsen GmbH
Current assignee: Wabco Standard GmbH; Wabco Westinghouse Fahrzeugbremsen GmbH
Priority date: 1991-02-18
Filing date: 1992-02-14
Publication date: 1992-09-16
Anticipated expiration: 2012-02-14
Also published as: BR9200497A; GB9203222D0; GB2253679B

Description

PRESSURE VALVE FOR A COMPRESSOR 225-5679 The invention relates to a

pressure valve for a compressor.

A pressure valve for a compressor is already known from DE 39 09 343 Al. The known pressure valve has a plate-like valve seat which is fixed in position by fixing means, for example a bolted or rivetted connection, to a separating wall separating a compression space from a pressure space of the compressor. The fixing means are intended to hold and to press the valve seat against the separating wall. This is especially important in the region of the valve passages. The valve seat is intended to be prevented from lifting away from the separating wall as a consequence of changes in load caused by operating conditions during the suction and pressure phases of the compressor.

The valve seat and the separating wall need different properties and are preferably made of different materials. The different expansion characteristics of these components in response to changes in temperature between the rest and operational phases of the compressor can therefore adversely affect the desirable close contact of the valve seat with the separating wall.

In the case of a valve seat secured at two or more places on the separating wall, the different expansion behaviour can be compensated for by allowing play between the fixing holes in the valve seat and the fixing means on the separating wall. However, that means that the valve seat is pressed to a correspondingly reduced degree against the separating wall. On change-over from the operational to the rest phase, that is to say, when the contraction of these components due to cooling is different, the frictional force around the fixing elements may still be sufficient, however, to cause warping of the valve seat.

Lifting of the valve seat from the separating wall caused by that warping then leads to a reduction in the output of the compressor, because the pressure valve is imperfectly closed during the suction phase. Leakage through the gap between the valve seat and the separating wall could cause encrustation resulting from increased deposition of oil carbons. The action of the pressure valve would be impaired even further by this.

Were the valve seat to be secured at only one end, the different expansion behaviour would not have any effect. But the pressure of the valve seat against the separating wall decreases with increase in the distance from the end at which the fixing means are located. Here too, as a result of poor pressure between the valve seat and the separating wall, the deposition of oil carbons can reduce the efficiency of the pressure valve.

An object of the present invention is to improve a pressure valve of the kind mentioned above, so that, compared with the above-mentioned pressure valve, any different thermal expansion of the valve parts is compensated and the pressure of the valve seat against the separating wall is maintained virtually constant in all operational states of the compressor.

The problem is solved at least in part by the embodiments of the invention specified in patent claims 1 and 10. Developments and advantageous embodiments are specified in the subsidiary claims.

The invention can be used advantageously for a valve seat which is positively connected at only one of its extreme ends to the separating wall by fixing means.

FIGURE 1 shows a pressure valve with a plate-like valve seat; FIGURE 2 shows a detail of the pressure valve according to Figure 1; FIGURES 3 and 4 show a first variant of the pressure valve according to Figure 1; FIGURE 5 shows a second variant of the pressure valve according to Figure 1; and FIGURES 5 and 6 show details of modifications to the pressure valve according to Figure 5.

Figure 1 shows part of a compressor with a compression space 1 and a pressure space 3 formed in a cylinder head 2. The compression space 1 and the pressure space 3 are separated from one another by a separating wall 4 provided with a member in the form of a valve seat 5. The pressure space 3 is arrhnged to be connected by wa of a pressure outlet 9 to a pressure medium consumer apparatus. The pressure valve 5, 6 is constituted by the valve seat 5 and a resilient valve-closing body 6. The valve-closing body 6 covers a valve passage 7 passing through the valve seat 5 and the separating wall 4. A lift stop 8 is provided for the valve- closing body 6.

The valve seat 5 is formed by a plate-like component which is secured to the separating wall 4 and is of a material having a wear-resistance that is greater than that of the separating wall 4. The component 5 can be formed, for example, by a spring steel plate. In the region of the valve passage, the valve seat 5 has an opening 10. The cross-section of the opening 10 is at least the same as that of the valve passage 7.

The valve seat 5 is a separate member on the separating wall 4 and is fixed to the separating wall 4 by screw attachment 11. Instead of the screw attachment 11, customary rivetted mounting could be provided as the fixing means. The member 5, the lift stop 8 and the valve closing body 6 are all fixed to the separating wall 4 by the fixing means 11. It is also possible for the valveclosing body 6 to be arranged on.the separating wall 4 separ:ately from the member 5 and the lift stop 8.

4 - The member 5 has an area of support 12 which is arranged on the region 13 of the member 5 remote from the fixing means 11. At its end remote from the fixing means the lift stop 8 has a stop 14, against which the area of support 12 is biassed. The bias force is produced because the region 13 of the member 5 with the area of support 12 is of resiliently deformable construction. That is achieved by the region 13 with the area of support 12 being formed by a partly curled-in end of the member 5.

Figure 2 illustrates diagrammatically the forces occurring between the stop 14 of the lift stop 8 and the area of support 12 of the member 5 as a result of the above-mentioned bias. Because the abutting faces of the stop 14 and the area of support 12 are arranged at an angle to the separating wall 4, a resulting force R is produced, which can be divided into a force component xl directed towards the separating wall 4 and a force component x2 directed in the extension direction of the member 5. The size ratio of the force components xl, x2 to one another can be varied by suitable inclination of the stop 14 and the area of support 12, and can thus be adapted to suit different operating conditions.

Because of the different thermal expansion of the components associated with the pressure valve 5, 6, an increase in the temperature of the compressor brought about during operation causes the separating wall 4, the member 5 and the lift stop 8 to be displaced to different extents relative to one another. While the expansion of the separating wall 4 has no influence on the remaining parts 5, 8 of the pressure valve 5, 6, by suitable choice of materials the bias between the stop 14 and the area of support 12 can be made to increase as a result of a greater thermal expansion of the lift stop 8 compared with the member 5. The force components xl and x2 effective as the extension force and the contact force are thereby increased. on contraction of the said components 5, 8 as a consequence of cooling, the effective force components xi, x2 are again returned to their initial magnitudes. This means that in every operational state, for example even at the start of heating, there can be an adequate pressure x1 of the member 5 against the separating wall 4. The force component x2 effective in the extension direction prevents the above-mentioned warping or lifting of the member 5 from the separating wall 4 as a result of a change in load resulting from operating conditions between the suction and pressure strokes.

Figure 3 shows a variant of the pressure valve according to Figure 1, with a valve-closing body 18 illustrated in Figure 4 (section A-B of Fig. 3), which covers two valve passages 19 and 20 arranged side by side with respect to the longitudinal axis of the valve-closing body 18. A lift stop 15 adapted to this construction is provided, with a stop member 17 that is in the form of a wall of an aperture 21 of the lift stop 15. By means of an area of support 22 on the member 16 constructed as the valve seat, the member 16 is urged in the contact and extension directions as described with reference to Figure 2 by the bias force imposed by the stop 17. The region 50 of the member 16 having the area of support 22 is arranged between the valve passages 19, 20 and the screw attachment 11.

Figure 5 shows a member in the form of a valve seat 30 which, together with a valve-closing body 31, forms a pressure valve 30, 31. The pressure valve 30, 31 covers valve passages 24, 25 through a separating wall 26. A lift stop 27 for the valve-closing body 31 is fixed to the separating wall 26 at its extreme ends by fixing means 28, 29. A stop 32 is provided in the form of a wall of an aperture 33 in the lift stop 27. By means of an area of support 34 on the component 30, the component 30 is urged by the stop 32 in the contact and extension directions as described above with reference to Figure 2.

The fixing means 28, 29 at the extreme ends of the lift stop 27 impart a greater rigidity to the stop 32 of the latter compared with the fixing means 11 arranged at one side only in the embodiments of the pressure valve according to Figures 1 and 3. The construction according to Figure 5 can then advantageously be used for pressure valves that are intended for covering a relatively long valve region.

Instead of the member 30, a member 51, as shown in Figures 6 and 7, can also be used, the regions 36, 37 thereof provided with areas of support 38,39 being arranged on both sides of the longitudinal axis of the member 51. In the corresponding construction according to Figure 6, a lift stop 44 is provided with stops 40,41 at openings 46, 47 on both sides of the longitudinal axis of the lift stop 44 and which co-operate with the areas of support 38, 39 of the member 51 in the above-described manner.

In the construction according to Figure 7, a lift stop 45 with stops 42, 43 is provided, the stops being arranged on projections 48, 49 on both sides of the longitudinal axis of the lift stop 45 and bearing on the areas of support 38, 39 of the member 51.

The bias force under which the member 5, 16, 30, 51 in the form of a valve seat bears against the separating wall 4 can also be generated by a spring element, for example, one that is constructed and arranged so that at one end it bears against the lift stop or a part connected to the lift stop, and at its other end it urges the member constructed as valve seat, or a part connected thereto, towards the separating wall 4.

It is equally possible to generate the bias force under which the member 5, 16, 30, 51 bears against the separating wall 4 by making the lift stop 8, 15, 27, 44, 45 resiliently deformable, at least for a part of its length, so that the lift stop 8, 15, 27, 44, 45 is biassed against the area of support of the member 5, 16, 30, 51.

The stop can be arranged either on the lift stop 8 15, 27, 44, 45, or on the member 5, 16, 30, 51. Correspondingly, the area of support is provided on the member 5. 16, 30, 51 or lift stop 8, 15, 27, 44, 45.

The force component x2 directed in the extension direction of the member 5, 16, 30, 51 can also be approximately or exactly equal to zero.

Claims

CLAIMS:

A pressure valve for a compressor, having the following features: the compressor has a compression volume and a pressure volume, which are separated from one another by a separating wall with a valve seat for the pressure valve; the pressure valve is constructed as a non-return valve with a resilient valve-closing body and a lift stop for the valve-closing body, the valve-closing body covering the valve seat and the valve passage passing through the separating wall; the valve seat is formed by a separate member which is fixed to the separating wall by fixing means; characterised by the following features: the member has at least one area of support which is arranged at a position on the member remote from the fixing means; the lift stop has. at least one stop which is biassed against the area of support so as to press the valve seat member against the separating wall.
A pressure valve according to claim 1, characterised in that the stop and the area of support are arranged relative to one another so that the bias force between the area of support and the stop has a force component directed towards the separating wall and a force component directed in the extension direction of the member.
A pressure valve according to claim 1 or 2, characterised in that the line of action of the bias force between the stop and the area of support on the member within the region of the member where it bears on the separating wall.
4. A pressure valve according to any one of the preceding claims, characterised in that the bias force is provided by constructing the region of the member that includes the area of support to be resiliently deformable.
5. A pressure valve according to claim 4, characterised in that the region of the member that includes the area of support is formed by partly curled-in end of the member.
A pressure valve according to claim 1 to 5, characterised in that the member has regions provided with areas of support which are arranged on both sides of the longitudinal axis of the member.
7. A pressure valve according to any one of the preceding claims, characterised in that the stop of the lift stop is in the form of a wall of an aperture in the lift stop.
8. A pressure valve according to any one of the preceding claims, having at least two stops on the lift stop, characterised in that the stops of the lift stop are provided at openings on both sides of the longitudinal axis of the lift stop.
9. A pressure valve according to any one of claims 1 to 6 having at least two stops on the lift stop, characterised in that the stops on the lift stop are provided on projections on both sides of the longitudinal axis of the lift stop.
10. A pressure valve according to at least one of the preceding claims, characterised in that the lift stop is of resiliently deformable construction, for at least part of its length, and it is arranged so that the stop is biassed against the area of support-of the member.
11. A pressure valve for a compressor, having the following features: the compressor has a compression volume and a pressure volume, which are separated from one another by a separating wall with a valve seat for the pressure valve; the pressure valve is constructed as a non-return valve with a resilient valve-closing body and a lift stop for the valve-closing body, the valve-closing body covering the valve seat and the valve passage passing through the separating wall; the valve seat is formed by a separate member which is fixed to the separating wall by fixing means; characterised in that a spring element is provided, which is constructed and arranged so that the separate member in the form of a valve seat is biassed against the separating wall.
12. A pressure valve according to claim 11, characterised in that the spring element bears with one end against the lift stop or a part connected thereto, and with its other end biasses the member in the form of a valve seat, or a part connected thereto, towards the separating wall.
13. A pressure valve for a compressor substantially as described herein and as illustrated by Figure 1 and Figure 2, Figure 3 and Figure 4, or Figure 5 of the accompanying drawings, or modified as herein described with or without reference to Figure 6 or Figure 7 of the accompanying drawings.