FR2687443A1 - ELASTIC ANNULAR JOINT. - Google Patents

Abstract

The invention relates to an elastic annular seal able to be engaged on the rod of a connecting member of two metal parts in mutual support comprising an elastic annular body, in particular in elastomer, and a rigid washer, in particular metal arranged at the upper part of said annular body. The annular body (2) comprises in its outer peripheral wall (5) an annular recess (4) extending over at least part of the height of said annular body (2).

Description

The present invention relates to an elastic annular seal constituted

  by a metal washer and an elastic annular body, adapted to be engaged on the rod of a connecting member of two metal parts in mutual abutment for example a clamping screw for fixing a housing on an engine block avoiding any metal contact on metal

  likely to transmit vibrations between these two parts.

  To perform the uncoupled clamping of two metal parts, that is to say a clamping in which metal-to-metal contact is avoided, annular clamping gaskets, made of elastomer, possibly equipped with a metal washer, are commonly used. These seals are for example intended to be put in place on the clamping screws used to fix a casing on an engine block, a gasket being placed between the surfaces facing the casing and the casing.

engine block.

  The latter insulates the two metal parts together while the annular seal engaged around the screw prevents any metal-to-metal contact between the housing and the screw which holds it on the engine block. Such annular seals are subjected to high axial pressures which have the effect of causing creep of the elastomeric material

  forming the seal to the outside.

  In addition, during engine operation, the seal is subjected to a high temperature rise which accentuates the expansion of the engine.

elastomeric material.

  The creep of the elastomeric material is highly detrimental insofar as it causes the appearance of external cracks which can be accompanied by cuts in the case where the elastomer is too much

  strongly compressed against a sharp angle of the metal frame.

  If the creep is too important, it can also cause

  a deformation of the reinforcement of the annular seal.

  Moreover, it happens that the elastomer, highly compressed, can not flow outward due to imprisonment of its entire volume In this case, its expansion can cause

tearing of the fixing screw.

  The present invention aims at providing a simple and economical means for isolating a workpiece and its clamping member on a support, which medium, while fulfilling its role transmitting effort of

  tightening, avoids the disadvantages described above.

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  The subject of the present invention is an elastic annular seal capable of being engaged on the rod of a connecting member of two mutually supporting metal parts, comprising an elastic annular body, in particular made of elastomer, and a rigid washer, in particular a metallic washer, arranged at the upper part of said annular body, characterized in that the annular body has in its outer peripheral wall an annular recess extending over at least a part of the height

said annular body.

  The annular seal according to the invention thus makes it possible to isolate a connecting member such as a screw, from the part which it holds in position

by tightening.

  During tightening, the resilient annular body of the seal according to the invention crushes and the elastic material of which it is constituted flue laterally. Inward creep is limited by the rod of the connecting member, which has the effect of increasing the effect of creep towards

  the outside and consequently the overflow of matter.

  According to the invention, the annular recess formed on the outer peripheral wall of the elastic body limits this excess material

  since there remains a free volume that matter begins to fill.

  In a preferred embodiment of the invention, the annular recess has, in axial section, a concave shape which does not

has no sharp angles.

  Thus, during tightening, it avoids folds that could

  contribute to the deterioration of the joint.

  Preferably, the surface of the rigid washer which is in contact with the elastic annular body does not comprise any sharp edge, which also makes it possible to limit the risks of deterioration of the elastic material during tightening. In another embodiment, the rigid washer disposed at the upper part of the annular body is folded on its outer perimeter to the elastic annular body to cover it, the face of the rigid washer which is in contact with the elastic annular body then ends with an annular surface plane substantially perpendicular to the direction of clamping Thus, it avoids any pinching of the elastic body against the rigid washer which does not present

in addition no sharp edges.

  Preferably, the rigid washer is glued to the body

elastic ring.

  It is also possible to overmold the rigid washer on the elastic annular body, or to combine these two modes of connection. In order to make the invention better understood, an embodiment given by way of example and without any limiting character will now be described with reference to the appended schematic drawing in which: FIG. 1 represents an axial sectional view of FIG. An elastic ring seal according to one embodiment of the invention, Figure 2 shows the seal of Figure 1 in the clamping position, Figure 3 shows different steps of tightening the seal of Figure 2, and Figure 4 shows a variant of an overmolding

according to the invention.

  In Figure 1, an elastic annular seal 1 is shown in axial section It is composed of an elastic annular body 2 and a rigid washer 3 disposed at the upper part of the body

elastic 2.

  In this figure, we clearly see the concave shape of the annular recess 4 formed on the outer peripheral wall 5 of the

elastic ring body 2.

  The outer peripheral wall 5 has an annular surface 5a corresponding to the portion of the annular body 2 which is crushed during clamping, an annular shoulder 5b through which the seal 1 bears on the part which receives it, and an annular surface 5 c realizing

  maintaining the position of the seal 1 on this piece.

  According to this embodiment, the recess

  ring 4 is formed on the annular surface 5a of the wall 5.

  The inner wall 6 of the elastic body 2 is divided into three parts. The upper part 6a is frustoconical and open towards the outside, it facilitates the guiding of the rod of a connecting member,

  like for example a screw, when setting it up.

  The central surface 6b is cylindrical and holds the rod of the connecting member in place before tightening.

  lower surface 6 c in the plane of the shoulder 5 b.

  The lower part 6c is frustoconical and open towards the outside, it allows a possible deformation of the surface of

  centering 5c when installing the gasket 1 on a workpiece.

  The elastic annular body 2 molds the rigid washer 3, its inner wall 6 extends over the entire height of the seal 1 and fills

  a circular groove 7 made on the upper face 8 of the washer 3.

  Two circular bosses triangular section 9 protrude from the upper surface 8 Alternatively, the elastic annular seal 1 may have only one boss 9 or on the contrary more than two, which may also have a section of a

other form.

  FIG. 2 represents the seal of FIG. 1 in position

tight.

  In this figure, a housing 10 is clamped against a block

motor 11 by a screw 12.

  A crankcase gasket 13 is used here in combination with the elastic annular seal 1 to isolate on the one hand the housing 10 of the block

  motor 11 and secondly the housing 10 of the screw 12.

  The clamping force imposed by the screw 12 on both the annular gasket 2 and the crankcase gasket 3 is limited by the fact that the screw

  relies on the motor unit 11 by a shoulder 14.

  A radial clearance 15 between the shank of the screw 12 and the through hole of the casing 10 avoids any metal-to-metal contact between these two

  metal members in the region where there is no elastic material.

  The centering of the screw in the through hole of the housing 10

  is provided both by the seal 1 and the seal 13.

  All the clamping force resulting from the screwing of the connecting member 12 on the block 11 is transmitted by the rigid washer 3 which constitutes the armature of the annular seal 1 This force is distributed between the

  annular seal 1 and the seal of the housing 13.

  We see in Figure 3 an axial section of a portion of the seal 1 during its tightening The material of the elastic body 2 flue

laterally.

  The solid line represents the shape of the annular body

elastic 2 before tightening.

  The broken line schematizes the intermediate step in which the outer peripheral wall 5 'of the annular elastic body 2 is substantially parallel to the axis of the seal and the annular recess 4' is

almost filled.

  The mixed line schematizes the tight position of the joint in which the outer peripheral wall 5 "has substantially the shape of an S, which shape results from the competition between the concavity of the recess

  Annular 4 "and lateral creep of the material.

  It can be seen that, thanks to this S-shape, it is possible to substantially reduce the thickness of the annular body 2 without leading to a

  excessive creep of the crushed material.

  In the embodiment shown, it is clearly visible in FIG. 3 that the face of the rigid washer 3 which is in contact with the elastic annular body 2 ends with a surface

  annular plane 3 has substantially perpendicular to the direction of clamping.

  The lower face of the rigid washer 3 and the outer peripheral wall of the elastic annular body 2 meet tangentially, which has

  to accentuate the S-shape of the wall 5.

  FIG. 4 represents a variant of overmoulding of the

  rigid washer 3 on the elastic annular body 2.

  This figure shows an axial section of the

  upper inner part of the elastic annular seal 1.

  According to this variant, the lower surface of the rigid washer 3 which lies under the annular groove 7 has an annular bearing surface 3 b whose main function is to prevent that

  the rigid washer 3 is unmolded from the elastic body 2.

  It is understood that the embodiments which have just been described are not limiting in nature and can receive

  any desirable modification without departing from the scope of the invention.

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Claims (5)

  An elastic annular seal capable of being engaged on the rod of a connecting member of two mutually supporting metal parts comprising an elastic annular body, in particular made of elastomer, and a rigid washer, in particular a metal washer disposed at the upper part of said annular body, characterized in that the annular body (2) has in its outer peripheral wall (5) an annular recess (4) extending   on at least a portion of the height of said annular body (2).   2 annular elastic gasket according to claim 1, characterized in that in axial section, its annular recess (4)   has a concave shape that has no sharp angles.   3 Elastic ring seal according to any one of   preceding claims, characterized in that the face of the   rigid washer (3) which is in contact with the elastic annular body (2) has no sharp edges   4 resilient annular seal according to claim 3 wherein the rigid washer is folded over its outer perimeter to the elastic annular body to cap it, characterized in that the rigid washer (3) which is in contact with the annular body elastic (2) terminates in a flat annular surface (3 a) substantially   perpendicular to the direction of tightening.   Elastic ring seal according to any one of   preceding claims, characterized in that the rigid washer   (3) is adhered to the elastic annular body (2).   6 Elastic ring seal according to any one of   preceding claims, characterized in that the rigid washer   (3) is overmolded on the elastic annular body (2).