GB2220996A

GB2220996A - Resiliently deformable gasket washer

Info

Publication number: GB2220996A
Application number: GB8915784A
Authority: GB
Inventors: Kurt Stoll
Original assignee: Festo SE and Co KG
Current assignee: Festo SE and Co KG
Priority date: 1988-07-23
Filing date: 1989-07-10
Publication date: 1990-01-24
Anticipated expiration: 2009-07-10
Also published as: FR2634533A1; GB8915784D0; GB2220996B; IT1234848B; IT8984961A0; DE8809436U1

Abstract

A gasket washer more especially for pneumatic systems has sealing parts (34 and 35) on its two axially facing sides, and externally (3) and also internally (4) has a frustoconical form with axial taper (5) extending in the same direction. The gasket is preferably resilient e.g. of aluminium or steel, or being compressed between nut (18, Fig 3) and e.g. a pneumatic cylinder (16) it is elastically deformed flat, thus biassing the sealing parts against the nut and cylinder. The ring may be square, rectangular or elliptical in cross-section. <IMAGE>

Description

Gasket The invention relates to a gasket ring and more particularly to such a ring for use in pneumatic system joints having sealing parts on its two sides facing along its axis.

Gasket rings are more especially used in pneumatic systems for sealing joint connections between pneumatic components, as for instance to provide a pressure-tight seal between the cylinder of a piston and cylinder unit actuator and a pressure pipe union fitting having its male threaded part screwed into the cylinder wall. The gasket ring is in each case placed between the two components between which a sealing joint is required so that when the components are pressed together, for example by screwing up, a sealing joint results. Then the two sides of the gasket ring facing along its axis come into abutting engagement with the two components and at the same time are axially pressed by them.

Commonly used forms of such gasket rings are O-rings or flat gasket rings with a rectangular cross section. However there is the disadvantage that during the course of time leaks are prone to occur owing to fatigue of the material of the gasket ring and the consequent decrease in the thrust thereon due to the components to be sealed. The joints thus frequently have to be inspected to see if they are still fluid-tight and if there Is a leak they have to be tightened up. This work is slow and if by accident a leak is overlooked, the result may be substantial damage. A further problem is that if excessive force is applied to the two components to be drawn together, the ring may be crushed so that it may be fractured.

One object of the present invention is to provide a gasket ring of the initially specified type which is simple to produce A further object of the invention is to provide such a gasket ring which even after a long period of service ensures a reliable sealing action with respect to the components to be jointed.

In order to achieve these and/or objects the gasket ring is made internally and externally with a frustoconical form having the same direction of axial taper. This ensures that on tightening the components to be joined together there is a deformation of the gasket ring placed between them in the axial direction in the course of which its tapered part is practically invaginated so that the cone angle increases pari passu with the increase in deformation. In this respect the sealing ring has a tendency to change from its initial frustoconical form into the flat form of an annular disk.However at all times this deformation is opposed by the intrinsic material forces of the gasket ring so that between the two extreme positions mentioned on may be certain of a full, annular engagement of the gasket ring on the two components between which a sealing joint is to be created. It is therefore not even necessary to screw the two components very firmly together since the gasket ring guarantees s full sealing effect even if it is not so firmly squeezed as to reduce its wall thickness. Accordingly failures may be reduced which have so far been liable to occur owing to the joint connection being excessively tightly pressed into engagement. A further advantage of the invention is that the novel gasket ring has a self-resetting effect.The annular form selected ensures sufficient elasticity so that even after a long period of use there is a sufficient force to make the desired engagement with the components between which a sealing joint is desired. As a consequence of this time consuming checking and inspection of the connections in the plant are no longer needed. In addition to all these advantages there is the benefit that the gasket ring is simple to produce, since it may be made by stamping or embossing at a favorable price.

Advantageous further features of the invention will be seen from the claims It is convenient if the gasket ring is so designed that it has the form of the wall of a frustoconical funnel. In this respect the two annular section faces of the ring or annulus in a plane extending radially and axially are preferably set at an oblique angle to the longitudinal direction of the ring. It is furthermore an advantage if the two sealing parts are in the form of sealing edges arranged peripherally on the ring and having different diameters which are then offset from each other in the axial direction. There has a particularly advantageous effect on the costs of production if the gasket ring has a square or other rectangular form.Furthermore, in the case of such a design of the ring there is the further useful effect that the sealing edges are formed by the annular, peripheral edges, which are turned in opposite directions, of the ring section faces.

In the case of a rectangular annular section face the longitudinal axes, running parallel to the major lateral edges of this surface, are preferably set at the same angle to the longitudinal axis thereof and converge towards each other so that they meet in the longitudinal ring axis clear of the radial plane of the ring.

Preferably, also, the sealing edges of the ring edges, which are diagonally opposite to each other in relation to the ring section face, are formed in the opposite external axial ring parts.

It is furthermore an advantage if the gasket ring is made with oval or elliptical ring section faces.

If in the gasket ring is made so as to be soft in the axial direction and more especially is made to be resilient in this direction, then it will possess a particularly long working life without the sealing function being impaired.

It is preferred for the gasket ring to be made of aluminium or an aluminium alloy. In certain circumstances it may be made of steel. It is convenient if it is made by stamping or embossing, although it may be made by turning at a comparatively low price.

The invention will now be described with reference to the accompanying drawings in more detail.

Figure 1 shows a first embodiment of the invention in section.

Figure 2 and Figure 3 show the gasket ring as in figure 1 in conjunction with a joint connection, which is to be sealed, between a male union part and the wall of a pneumatic component, figure 2 showing the state of things before the production of the joint and figure 3 the condition after the joint has been produced.

Figure 4 shows a further design of the gasket ring in accordance with the invention in section.

Figures 1 and 4 show two advantageous embodiments of the gasket ring in accordance with the invention, which are generally denoted 1 and, respectively, 1'. The longitudinal axis of the gasket rings 1 and 1' is marked in broken lines at 2. Both of the gasket rings 1 and 1' are characterized in that when looked at from the inside (4), that is to say looking towards the axis and also when looked at from the inside (4), that is to say looking away from the axis, they have a frustoconical form, the frustum of the cone tapering in both cases in the same axial direction 5.

This way of viewing the ring enables one to visualize the general configuration of the gasket rings 1 and 1' without having to consider in detail the actual form of the contours of the annular surface sections.

The form of the gasket rings 1 and 1' may also be described in other ways by saying that it resides in the type of wall configuration of a frustoconical funnel.

In both figures 1 and 4 the respective gasket ring 1 and 1' is shown in section, the plane of the section simultaneously extending in the axial direction 2 and in the radial direction 6 of the ring, this section being denoted as the cross section in what follows. As part of such a cross section it will be seen that there are two diameterally opposite annular section faces 7 and 7' and, respectively, 8 and 8', which are identical in form.

Owing to the conical gasket ring form the two ring section faces 7 and 7' and, respectively, 8 and 8' of each ring are set obliquely in relation to the longitudinal direction 2 of the ring.

On looking at the ring 1 in figure 1 in detail it is possible to see the advantageous rectangular form of the two ring section faces of the respective rectangle. The longitudinal axes 9 and 9' extending parallel to the major side edges of the respective rectangle of the two rectangular faces 7 and 7' are arranged at the same angle 10 and 11 to the longitudinal axis 2 of the ring and intersect at a common point 14 with the longitudinal 2 on one side of the ring at a distance therefrom.

A design of the ring is also possible if the ring section faces 7 and 7' are square.

In the case of the gasket ring 1' of figure 4 the ring section faces 8 and 8' are made oval and have the form of a compressed or deformed circle. An elliptical form would be possible in this case as well. As regards the longitudinal axes 15 and 15' of these ring section faces 8 and 8' the same applies as for the longitudinal axes 9 and 9' of the ring section faces 7 and 7' of the gasket ring 1, for which reason no further comments are necessary here.

In both cases 1 and 1' the gasket ring is preferably made of aluminium or a material containing a large percentage of aluminium. This ensures that the ring is resilient in the axial direction 2. The advantages resulting from this resilient elasticity may best be explained with reference to figures 2 and 3.

These two figures 2 and 3 show an identical pneumatic system part in different settings. In each case the reader will be able to see the wall 16 of a pneumatic component, In the case of which it is for instance a question of the wall of a cylinder of a piston and cylinder actuator. The inner space 17 indicated and enclosed by the wall 16 of the component is suitable for receiving a pneumatic fluid, as for instance compressed air. By means of a union 18 a fluid line, not shown, or a fluid hose is to be connected with the space 17 in order to supply and discharge fluid from the cylinder.For this purpose the wall has a screw threaded through hole 19, in which the union 18 is to be screwed by means of its screwed spigot 20. 21 denotes a nut or the like on the spigot so that a tool such as a spanner may be applied thereto and following this nut in the axial direction there is a male member 22 over which a conductor or hose may be slipped in a detachable manner. The union 18 has a coaxial bore 23 therethrough.

In order to provide a seal in the part 24 between the two parts 10 and 20 there is a gasket ring in the form of the ring 1 as in figure 1 which is placed between the union 18 and the wall 16. Its internal diameter is somewhat larger than the external diameter of the threaded spigot 20, which is surrounded by the ring 1 coaxially with radial clearance, it being flanked on both sides, that is to say its two surfaces directed along the axis, by planar sealing faces 30 and 31, which on the one had are arranged on the outer side of the wall 16 and on the other hand on the facing side of the nut 21 and more specially are molded or formed thereon.

In the position shows in figure 2 the union 18 is not fully screwed into the breaded bore 19 so that the gasket ring 1 has axial play and assumes a first ring position which is identical to the original or basic position or condition as shown in connection with figure 1. If now the union 18 is screwed in further the two sealing faces 30 and 31 will exert an increasing thrust as indicated by the arrows 32 and 33 in figure 1 in opposite directions along the axial direction 2 on the gasket ring 1. The consequence of this is that the gasket ring 1 is progressively invaginated with an increase in the angles 10 and 11 until they amount to around 900 and the gasket ring assumes the condition as shown in figure 3 in which state it now corresponds to the configuration of a flat washer.The longitudinal sides of the ring section faces 7 and 7' which were originally oblique in relation to the longitudinal axis 2 are now generally at a right angle to the longitudinal axis 2.

Owing to the resilient properties of the gasket ring when in any form departing from the basic setting as in figure 1 the ring will tend to return to such original setting, even if It is in the setting as in figure 3. The resilient property offers the advantage that the gasket ring is always biased so that the sealing parts 34 and 35 on the two sides of the ring are constantly pressed against the components between which a joint is needed.The result of this is an excellent sealing contact and even after a long period of time there is no fatigue of the material of the gasket ring so that there are no gaps which would lead to leakage of material The gasket ring 1 and 1' may thus be said to have a self-resetting effect and owing to the configuration in accordance with the invention it is substantially more elastic that conventional gasket rings, it furthermore being able to cope with larger axial gaps between the components between which sealing joint is needed.

Since the gasket ring 1 and 1' thus simultaneously serves a sort of resilient ring, there is the advantage of dealing with any accidental loosening of the screw joint between the union 18 and the wall 16.

The use of aluminium as a material for the gasket ring ensures an optimum seal.

Reverting now to figure 1 it will be seen that the rectangular ring section faces 7 and 7' are the reason for the two sealing parts 34 and 35 on the ring each having a peripheral sealing edge 36 and 37 on the axial ring parts. In this respect it is a question of ring edges formed by two corners, which are diagonally opposite each other in relation to the ring section face, of the, such ring edges having two different diameters, the diameter of the sealing edge 36 directed in the direction 5 of taper being smaller than that of the opposite sealing edge 37.

The axial distance of the two sealing edges 36 and 37 depends on the angles 10 and .11 of the oblique setting of the section faces 7 and 7'.

It is in this manner that there is linear contact between the gasket ring and the associated joint faces 30 and 31 of the two components between which the joint is to be produced, such joint being ensured by the high specific surface pressure with an optimum sealing effect. It is only in the setting of the ring shown in figure 3 that a sealing contact over a wide area is possible with the two ring faces, while in all other intermediate settings linear contact will predominate.

It is thus even possible for the gasket ring 1 and 1' to be so placed between the two components that in the terminal setting it does not assume an exactly disk-like form, and the angles 10 and 11 are less than 900. Without impairing the sealing properties this reliably prevents excessive squeezing or crushing of the gasket ring so that damage during assembly is prevented right from the start.

The simple structure of the gasket ring makes it possible for it to be produced by stamping and/or embossing as a stamping or embossed member. In this respect it is possible to use follow-up tools so that only a single working operation is required. In the case of a gasket ring 1 or 1' of steel as well good sealing properties are possible with a simple and low-price manufacturing routine.

The gasket ring may also be produced by turning on a lathe but this is somewhat more expensive.

A further advantage is that the gasket ring 1 and 1' in accordance with the invention may be caused to change its radial dimensions to a certain extent by the application of force as indicated by the arrows 32 and 33. It is in this manner that an additional sealing effect in the radial direction may be produced, if the joint faces on the components are arranged radially externally and/or radially internal to be opposite thereto and to correspond therewith.

Lastly the fact is an advantage that for the production of the gasket ring of the invention only a small amount of material is needed, since the ratio between the outer and inner diameters of the ring may be made very small without the elasticity in the axial direction being unfavorably affected.

Claims

1. An annular gasket having sealing means on axially facing sides thereof, the gasket having a configuration which both externally and internally is frustoconical with respective axial taper extending in the same direction.

2. A gasket according to claim 1, having the form of the wall of a frustoconical funnel.

3. A gasket according to claim 1 or 2, wherein, in cross-section, in a plane extending in an axial and a radial direction, the gasket has opposed faces extending obliquely in relation to the axial direction.

4. A gasket according to claim 3, which is square in said cross-section.

5. A gasket according to claim 3, which is rectangular in said cross-section.

6. A gasket according to claim 5, wherein longitudinal axes extending respectively through the opposed faces and parallel to the major side edges of the gasket in said cross-section, are arranged at the same angle to the longitudinal axis and converge towards each other, such axes meeting in the longitudinal axis of the gasket at a distance therefrom.

7. A gasket according to any of the preceding claims, wherein the sealing means comprise opposed sides having peripheral sealing edges of different diameters.

8. A gasket according to claim 7, when dependent on any of claims 3 to 6, wherein the sealing edges are located diagonally opposite to each other on respective sides of each of the opposed faces.

9. A gasket according toaclaim 3, which is oval or elliptical in said cross-section.

10. A gasket according to any of the preceding claims, which is movable between two settings, a first setting in which the gasket has a frustoconical form and a second setting in which the gasket has the form of a flat annular disc.

11. A gasket according to any of the preceding claims, which is in the form of a ring with resilient properties in the axial direction.

12. A gasket according to any of the preceding claims, which is made of a material with resiliently elastic properties.

13. A gasket according to any of claims 1 to 11, which is made of a material of which at least the greater part is aluminimum.

14. A gasket according to any of claims 1 to 12, which is made of steel.

15. A gasket according to any of claims 1 to 13, which is in the form of a stamped or embossed part.

16. A gasket according to any of claims 1 to 13, which is made by turning.

17. A gasket substanitally as described above with reference to figures 1 to 3 of the accompanying drawings.

18. A gasket ring substantially as described above with reference to figure 4 of the accompanying drawings.

19. Any novel subject matter or combination including novel subject matter herein disclosed, whether or not within the scope of or relating to the same invention as any of the preceding claims.