GB2264151A

GB2264151A - Elastic ring seal

Info

Publication number: GB2264151A
Application number: GB9302512A
Authority: GB
Inventors: Georges Hammann
Original assignee: PU SA
Current assignee: PU SA
Priority date: 1992-02-13
Filing date: 1993-02-09
Publication date: 1993-08-18
Anticipated expiration: 2013-02-09
Also published as: FR2687443A1; DE4304289A1; GB9302512D0; DE4304289C2; GB2264151B; FR2687443B1

Description

2264151 TITLE: Elastic rina seal The present invention relates to an

elastic ring seal consisting of a metal washer and an elastic ring, capable of being fitted on the shaft of a connecting device between two mutually supporting metal parts, such as a clamp bolt f or mounting a sump on an engine block., while avoiding any metal-to-metal contact liable to transmit vibrations between these two parts.

In order to achieve the disconnected clamping of two metal parts, that is clamping where one avoids any inetal-to-metal contact, one normally uses a clamping ring seal made of an elastomer, possibly reinforced with a metal washer.

Such seals are designed for example to be fitted on clamp bolts used to mount a sump on an engine block, with a static seal placed between opposing surfaces of the sump and the engine block.

The latter seal separates the two metal parts from each other while the ring seal fitted around the bolt prevents any metal-to-metal contact between the sump and the bolt which keeps it in position on the engine block.

Such ring seals are subject to high axial stress which has the effect of causing the elastomer material constituting the seal to creep outwards.

In addition, when the engine is in operation, the seal is subjected to a sharp rise in temperature which causes the elastomer material to expand even further.

The creep in the elastomer material is highly damaging insofar as it causes external cracks which are sometimes accompanied by splitting if the elastomer is squeezed too tightly against an acute angle of the metal reinforcement.

If there is too much creep, it can also cause the ring seal reinforcement to become warped.

Sometimes also the tightly squeezed elastomer cannot creep outwards as its entire volume is trapped. In such cases, its expansion can cause the fastening bolt to become loose.

The present invention is aimed at providing a simple and economical means of separating a part from the device clamping it to a support; a means which, while serving to transmit the clamping force, avoids the drawbacks described above.

The present invention provides an elastic ring seal comprising an elastic ring and a rigid washer attached to the said ring, the seal being capable of being fitted on the shaft of a bolt connecting a first metal part to a second metal part, the elastic ring comprising opposite the rigid washer a surface for bearing on the first metal part during use, characterised in that the outer peripheral wall of the ring has an annular cavity along part of its axial extent.

The ring seal according to invention can thus be used to separate a connecting device such as a bolt from the part which it holds in position by clamping.

During clamping, the elastic ring of the seal according to the invention is compressed and the elastic material of which it is made yields laterally.

Inward creep is limited by the shaft of the connecting device, which has the effect of increasing the outward creep and consequently the outward expansion of material.

According to the invention, the annular cavity in the outer peripheral wall of the elastic ring limits this excess material since a gap is left which the material fills initially.

In a preferred embodiment of the invention, the annular cavity in axial section is concave in shape with no sharp angles.

4 During clamping therefore, no folds are formed which could contribute to the deterioration of the seal.

The surface of the rigid washer i,,,hich is in contact with the elastic ring should preferably not have any sharp edges, which also helps to limit the risk of damage to the elastic material during clamping.

In a further embodiment of the invention, the outer periphery of the rigid washer is folded over to cover part of the elastic ring, the outer periphery of the rigid washer ending in a flat annular surface which is generally perpendicular to the clamping direction. One thus avoids squeezing the elastic ring against the rigid washer, which in any case has no sharp edges.

The rigid washer should preferably be adhered to the elastic ring.

It is also possible to mould the rigid washer onto the elastic ring, or to combine these two methods of bonding.

In order to provide a better understanding of the invention, we will now describe a method of construction, cited by way of example and which should in no way be regarded as limitative, with reference to the enclosed diagram where:

- f igure 1 shows an axial section of an elastic ring seal according to one version of the invention, - figure 2 shows the seal of figure 1 in clamping position, - figure 3 shows various clamping stages of the seal featured in figure 2, and - f igure 4 shows a an integrally noulded embodiment according to the invention.

In figure 1, an elastic ring seal 1 is shown in axial section. It is composed of an elastic ring 2 and a rigid washer 3 placed on the upper part of the elastic ring 2.

Figure 1 clearly illustrates the concave shape of the annular cavity 4 in the outer peripheral wall 5 of the elastic ring 2.

The outer peripheral wall 5 comprises an annular surface 5a corresponding to that part of the ring 2 which is compressed during clamping, a ringshaped collar 5b whereby the seal 1 rests on the part which receives it, and an annular surface 5c which holds the seal 1 in position on this part.

According to this version of the invention, the annular cavity 4 is made on the annular surface Sa of the wall 5.

The internal wall 6 of the elastic body 2 is divided into three sections.

The upper section 6a is tapered and opens outwards. it helps to guide the shaf t of a connecting device such as a bolt for example when fitting the latter.

The central surface 6b is cylindrical and holds the shaft of the connecting device in position prior to clamping. it joins the lower surface 6c in the plane of the collar 5b.

The lower section 6c is tapered and opens outwards. it allows the centring surface Sc to change shape where necessary when fitting the seal 1 onto a part.

The elastic ring 2 duplicates the shape of the rigid washer 3, its inner wall 6 extends the full height of the seal 1 and it fills a circular groove 7 on the upper side 8 of the washer 3.

Two circular ridges with triangular sections 9 project from the upper surface 8. Alternatively, the elastic ring seal 1 may only have one recess 9 or on the contrary more than two, which may also have a different shaped section.

Figure 2 shows the seal of figure 1 in clamped position.

In this figure, a sump io is clamped against an engine block 11 by means of a bolt 12.

A sump seal 13 is used here in combination with the elastic ring seal 1 to separate both the sump 10 f rom the engine block 11 and the sump 10 from the bolt 12.

The clamping f orce applied by the bolt 12 both to the ring seal 2 and to the sump seal 13 is limited by the fact that the bolt engages the engine block 11 by a collar 14.

Radial spacing 15 between the shaft of the bolt 12 and the hole in the sump 10 prevents any metal-to-metal contact between these two metal parts at those points where there is no elastic material.

The bolt is centred in the hole in the sump 10 both by the seal 1 and the seal 13.

The clamping force which results from bolting the connecting device 12 onto the block 11 is fully transmitted by the rigid washer 3 which acts as a reinforcement for the ring seal 1. This force is distributed between the ring seal 1 and the sump gasket 13.

Figure 3 shows an axial section of part of the seal 1 during clamping. The material used in the elastic ring 2 creeps laterally.

The solid line represents the outline of the elastic ring seal 2 before clamping.

The broken line illustrates the intermediate stage in which the outer peripheral wall 5,1 of the elastic ring 2 is virtually parallel to the axis of the seal and the annular cavity 41 is almost filled.

The dot-and-dash line illustrates the clamped position of the seal in which the outer peripheral wall 511 is more or less in the shape of an S, a shape which results f rom competition between the concavity of the annular cavity 411 and the lateral creep of the material.

It can be observed that, thanks to this S-shape, the thickness of the ring seal 2 can be significantly reduced without giving rise to excessive creep in the compressed material.

In the embodiment illustrated, it can be clearly seen from f igure 3 that the side of the rigid washer 3 which is in contact with the elastic ring 2 ends in a f lat annular surface 3a which is more or less perpendicular to the clamping direction. The lower face of the rigid washer 3 and the outer peripheral wall 5 of the elastic ring 2 tangentially join, which has the effect of accentuating the S-shape of the wall 5.

Figure 4 shows an embodiment whereby the rigid washer 3 is moulded onto the elastic ring 2.

The figure shows an axial section of the upper inner part of the elastic ring seal 1.

According to this embodiment, the lower surface of the rigid washer 3 which is situated under the annular groove 7 has a distinct annular bearing area 3b, the main purpose of which is to prevent the rigid washer 3 from coming away from the elastic ring 2.

It is evident that the ways of carrying out the invention which have just been described are in no way limitative and can be modified as required providing one remains within the scope of the invention.

Claims

An elastic ring seal comprising an elastic ring and a rigid washer attached to the said ring, the seal being capable of being fitted on the shaft of a bolt connecting a first metal part to a second metal part, the elastic ring comprising opposite the rigid washer a surface for bearing on the first metal part during use, characterised in that the outer peripheral wall of the ring has an annular cavity along part of its axial extent.
An elastic ring seal according to claim 1, characterised in that, shown in axial section, the annular cavity is concave in shape with no sharp angles.
3. An elastic ring seal according to claim 1 or claim 2, characterised in that the surface of the rigid washer that is in contact with the elastic ring does not have any sharp edges.
An elastic ring seal according to claim 3, in which the outer periphery of the rigid washer is folded over to cover part of the elastic ring, further characterised in that the outer periphery of the rigid washer ends in a flat annular surface which is generally perpendicular to the axis of the ring seal.
An elastic ring seal according to any of the preceding claims, characterised in that the rigid washer is adhered to the elastic ring.
6. An elastic ring seal according to any of the preceding claims, characterised in that the rigid washer is moulded onto the elastic ring.
7.

An elastic ring seal substantially as described herein with reference to the drawings.