GB2255156A

GB2255156A - A thermostatic valve

Info

Publication number: GB2255156A
Application number: GB9206936A
Authority: GB
Inventors: Roland Saur; Barbu Frunzetti
Original assignee: Behr Thomson Dehnstoffregler GmbH and Co
Current assignee: Behr Thomson Dehnstoffregler GmbH and Co
Priority date: 1991-04-23
Filing date: 1992-03-31
Publication date: 1992-10-28
Also published as: GB9206936D0; IT1258745B; ITMI920014A1; ES1019311U; DE9104964U1; ES1019311Y; ITMI920014A0; FR2675878A1

Abstract

In a thermostatic valve with a thermostatic working element the housing (10) of which has a collar (14), a valve disc (12), carried by the collar (14) and made of plastics material, is mounted, in the direction of valve disc movement, in form-locking manner on the housing (10). The valve disc (12) is provided with an annular groove (13) which receives the collar (14). The valve is particularly used in the cooling system of an internal combustion engine. <IMAGE>

Description

A thermostatic valve The invention relates to a thermostatic valve with a thermostatic working element, the housing of which has a collar carrying a valve disc.

Such thermostatic valves, which are used particularly but not exclusively, as coolant thermostats for the cooling installations of motor vehicles have valve discs which are made from metal plate. In such manufacture use is made of plate in a non-rusting material, or plate with an elastomer coating. These valve discs are secured by a press-fit on the housing of the thermostatic working element.

The present invention seeks to reduce the cost of manufacture of a thermostatic valve of the type referred to in the first paragraph.

According to the present invention there is provided a thermostatic valve with a thermostatic working element, the housing of which has a collar carrying a valve disc, wherein the valve disc is made of plastics material and is mounted on the housing in form-locking manner in the axial direction.

Such a valve disc is made simply, particularly as an injection-moulded part, in which process, on account of the material used, it does not rust and requires no additional protection against oxidation. Furthermore, this becomes possible at the outset as a consequence of the fact that a positive connection is produced between the housing of the thermostatic working element and the valve disc. This connection, preferably constructed as a snap-in connection, ensures that the valve disc- is fitted in lasting manner without the danger of becoming detached from the housing of the working element. It would not be possible to achieve this by a press-fit, as practically every plastic material tends to creep under the influence of creep and loading.

In a further embodiment of the invention it is provided that a defining wall of an annular-groove-like recess of the valve disc is given an insertion bevelling. This facilitates the manufacture of the snap-in connection between the working element housing and the valve disc.

In a further embodiment of the invention it is provided that a defining wall of the annular-groove-like recess of the valve disc is given at least one slot extending substantially axially. By this means it will be possible to divide this particular defining wall into one or more elastic tongues which permit in simple manner the effecting of the snap-in connection.

In a further embodiment of the invention it is provided that the inner outline of the annular-groove-like recess in the axial direction is made slightly smaller than the collar. By this means a surface of the valve disc is held permanently by means of a tensioning force against a counter-surface of the housing of the working element, so that at least an adequate seal is ensured between the valve disc and the housing.

In a further embodiment of the invention it is provided that the valve disc is fitted with a receiving space for an elastic sealing ring protruding over it. This elastic sealing ring permits a secure sealing between the valve disc and a valve seat without the need to have to conform to very high manufacturing accuracy for both the valve disc and the valve seat. In a further embodiment it is advantageously provided that the sealing ring should be positively held in the receiving space.

In a further embodiment of the invention it is provided that the valve disc is given at least one limit stop set back relative to the sealing ring. This stop defines the maximum path of the valve disc on the closing of the valve, and therefore the compression of the sealing ring. This prevents the sealing ring from being pressed too hard and, as a consequence, damaged.

Further characteristics and advantages of the invention will be found in the following description of a preferred embodiment illustrated in the drawing which shows an axial section through a valve disc of the invention for a thermostatic valve, the thermostatic working element being only indicated in outline.

Thermostatic valves are used in coolant circuits of internal combustion engines in order to maintain the coolant temperature and therefore the engine temperature at a predetermined temperature level, and reach this temperature level as soon as possible. They regulate the flow of coolant between the internal combustion engine and the radiator by means of a short-circuiting path.

Of the thermostatic valve a thermostatic working element has been represented in the drawing only with a dotdashed line. It has a housing 10 which contains a material which expands dependent on temperature, and as a result of this temperature-dependent expansion a working piston 11 is expanded out of the housing 10. The working piston 11 acts against a stop not shown, so that, as a result of its extension, the housing 10 is displaced against the direction of extension. Secured to the housing 10 is a valve disc 12 with which a valve seat (not shown) is associated. Acting on the valve disc 12 is a readjusting spring (not represented) which is designed as a helical spring surrounding the housing 10 at a distance.This readjusting spring pushes the valve disc 12 and therefore the housing 10 when the coolant is cold into the closing position in which the working piston 11 is retracted into the housing 10.

The valve disc 12 is made in a heat-resistant plastics material, e.g., ultra-amide. It is positively connected with the housing 10 so that, even under the influence of load and temperature, it does not alter its relative position to the housing 10.

The valve disc 12 has an annular shape and a central recess 13 the inner outline of which is adapted to the outer outline of a collar 14 of the housing 10. This collar 14 is situated in the region of the open end of the housing 10 out of which the working piston 11 can be extended. The region of the valve disc facing away from the working piston 11 is designed as a collar-like projection which contains a part of the annular-groove-like recess 13. This annular-groovelike recess 13 has a groove bottom 15 which is substantially cylindrical and which is matched to a cylindrical portion of the collar 14. Connecting onto the side facing away from the working piston 11 is a supporting surface 16 in the shape of a truncated cone which is also matched to a corresponding surface of the collar 14.Connecting further thereonto is a cylindrical collar 17 which surrounds the housing 10 with a small space in between.

Connecting onto the bottom 15 of the annular groove 13, on the side facing the working piston 11 is a further limiting wall 18 the inner surface of which matches the truncated-cone-shaped outline of a counter-surface of the collar 14 of the housing 10. This limiting wall 18 is provided with several axial slots 19 which extend as far as into the region of the groove bottom 15. As a result of this slotting 19 the limiting wall 18 is divided into several portions bendable in the manner of flexible tongues in the radial direction, so that this limiting wall 18 can be snapped with elastic expansion over the collar 14 of the housing 10. The inner edge of the limiting wall 18 is provided with an insertion collar 20. The valve disc is pushed from the side opposite the working piston 11 onto the housing 10, in the course of which operation, on reaching the collar 14 the elastic-tongue-like portions of the limiting wall 18 are elastically bent up outwards. After reaching the final position these portions of the limiting wall 18 snap back and surround the collar 14 of the housing, so that a positive connection is produced. The axial length of the groove bottom 15 of the recess 13 is preferably shorter by a small amount that the axial length of the corresponding cylindrical portion of the collar 14 of the housing 10. In this way it is ensured that the elastictongue-like portions of the limiting wall 18 hold the surface 16 of the valve disc with tension on the collar 14 so that an enhanced sealing effect is ensured.

The valve disc 12 is provided in the region of its outer sealing surface associated with a non-represented valve seat, with an elastic sealing ring 21 particularly a o-ring. This elastic sealing ring 21 is positively held in an annular-groove-like recess 22 of the valve disc. The annular-groove-like recess 22 surrounds over half the crosssection of the sealing ring 21, so that the latter is securely held. On the side opposite the working piston 11 and in the area of which the readjusting spring not represented acts, the sealing ring is supported by a support surface of the valve disc which protrudes outwards over the centre of the cross-section of the sealing ring 21.The border 23 of the recess 22 of the valve disc 12 facing the working piston 11 is designed as a stop which, after the sealing ring 21 has been compressed to the predetermined permissible extent, contacts the valve seat and thus prevents a further compression of the sealing ring 21 and thus the destruction of this sealing ring 21.

A positive connection between the valve disc 12 made of plastic material and the housing 10 of the thermostatic working element may also be effected in that the valve disc 12 is designed to consist of two parts in the region of the recess 3, i.e. of one part which can be mounted on the region of the collar 14 situated opposite the working piston 11, and.a part which can be mounted on the side of the working piston 11, this being a cover-type supporting part.

These two parts can then be locked or screwed together or joined together in some other way. In this connection it is also possible to make in a plastic material only that part of the valve disc 12 which receives the sealing ring 21, and to make the cover-like holding part in another material, for example as an elastic metal strip or an U-shaped spring of metal.

Claims

1. A thermostatic valve with a thermostatic working element, the housing of which has a collar carrying a valve disc, wherein the valve disc is made of plastics material and is mounted on the housing in form-locking manner in the axial direction.

2. A thermostatic valve according to claim 1, wherein the valve disc has a recess in the form of an annular groove which surrounds the collar of the housing in form-locking manner.

3. A thermostatic valve according to claim 1 or 2, wherein a limiting wall of the annular-groove recess of the valve disc is provided with an insertion collar.

4. A thermostatic valve according to any one of claims 1 to 3, wherein a limiting wall of the annular-groove recess of the valve disc is provided with at least one slot extending substantially axially.

5. A thermostatic valve according to claim 4, wherein at least one slot extends as far as the groove bottom of the annular-groove recess.

6. A thermostatic valve according to any one of claims 1 to 5, wherein the inner outline of the annular-groove recess is slightly smaller in the axial direction than the collar of the housing.

7. A thermostatic valve according to any one of claims 1 to 6, wherein the valve disc is provided with a receiving area for an elastic sealing ring.

8. A thermostatic valve according to claim 2, wherein the sealing ring is positively held in the receiving area.

9. A thermostatic valve according to claim 7 or 8, wherein the receiving area has a support surface which protrudes in a radial direction beyond the centre of the cross-section of the sealing ring.

10. A thermostatic valve according to any one of claims 7 to 9, wherein the valve disc is provided with at least one stop set back relative to the sealing ring.

11. A thermostatic valve substantially as described herein, with reference to, and as illustrated in the accompanying drawing.