FR2476538A1 - Hollow rubber gaiter seals reinforced by internal springs - to sustain seal pressures or enhance mechanical support - Google Patents

Abstract

Arcuate hollow rubber gaiters or bearings for enclosing and/or supporting surfaces having relative rotary or sliding motions are reinforced internally by one or more helical springs. Suitable for sealing linkages between mechanisms associated with drive, control or suspension systems for aircraft etc. The gaiters may be mon- or bi-conic, hyperbolic or other forms of solids of revolution. The internal springs can be deformed for installation of the seals, part of the deformation being maintained to suction contact pressure in radial and/or axial directions relative to the axis of the moulding.

Description

 Improvements to elastomeric devices of conical shape or the like, for connecting parts or assemblies in relative motion.

The invention relates to devices essentially made of elastomer, of conical shape or the like (especially with a curved generator, for example hyperbolic or other), intended to connect at least two parts or assemblies in relative movement. These will in particular be seals to be interposed between a shaft or other flat or other surface in relative displacement relative to a support, more particularly to ensure a seal, but the invention is in no way limited to this application and could relate, in particular , supports to be inserted, for the purpose of mortification or the like, between two assemblies, in particular supported by one another.

 It aims, in particular, to facilitate the operating conditions, and in particular the mounting of the devices in question.

 It mainly consists in essentially constituting these devices by at least one helical spring serving at least partially as a reinforcement for the elastomer which coats it.

A device of this kind has, thanks to the presence of the spring, elastic deformation properties in various directions, in particular in each radial plane, properties which can be taken advantage of, on the one hand, to ensure the mounting of the device in its support, in particular by radial compression with a view to its installation in appropriate housings and, on the other hand, in particular in the application to the seals, to better maintain the contact pressure with the movable surface for which the sealing must be carried out.

 However, the devices according to the invention also act by their flexural and buckling possibilities, which can be taken advantage of, in particular, in applications to supports intended to be interposed between two tracks or movable assemblies. one in relation to the other (1 n serving for example as a base and a support for the other). In particular, by defining the characteristics of these devices such as the diameters and not of the spring, angle of the last supper, thickness of the rubber, etc., it is possible to achieve a rigidity capable of being suitably adjusted. - nes of said applications, such as suspensions of rotating machines or of apparatuses in particular on board of planes or other machines, one could achieve a low rigidity for a certain range of variable forces applied to one of said sets , on either side of a determined normal effort.

 The invention consists, apart from these provisions, in certain others which are preferably used at the same time and which will appear in more detail in the description below.

 It relates more particularly to certain modes of applications as well as certain embodiments of said provisions: and it aims more particularly, and as new industrial products, to devices of the kind in question comprising application of these provisions, as well as the special elements specific to their establishment and the sets comprising them.

It can, in any case be well understood with the aid of the additional description which follows, as well as of the appended drawings, which supplement and drawings are, of course, given above all by way of indication.

Figure 1 of these drawings shows schematically in partial axial section a seal for a rotating shaft, established in accordance with the invention;
Figures 2 and 3 illustrate similarly and partially other embodiments;
Figure 4 illustrates in section the molding of a device according to the invention;
Figures 5 vas10 similarly show, in partial axial section, devices of the kind of those of Figures 1 to 3, according to other variants of one invention
Figure 11 illustrates in axial section a device according to the invention interposed, in particular as a shock absorber, between two parts of an assembly, movable one relative to i'a; trei
FIG. 12 is a flexibility curve illustrating the operation of the device of FIG. 11.

 According to the invention, and more particularly according to those of its modes of application, as well as those of the embodiments, of its parts, to which it seems that there is reason to give preference. proposing, for example, first of all, to obtain elastic elastomer seals, in particular for rotating surfaces, this is done as follows or in a similar manner.

There is shown in Figure 1 a joint of this kind established according to one of the possible embodiments of the invention.

 Such a seal essentially comprises, according to a conventional embodiment, an elastomer element 1, to be mounted around a shaft 2 carried by a bearing 3 or any support similar thereto, this element having substantially the shape of a hollow body of revolution, around an axis XX, generated by a straight line or by a curve, in particular in the form of a parabola or hyperbola, and of suitable thickness. It is known that such a joint must, in principle, on the one hand, be fixed at one end. for example by its large base at 4, at the support 3, and, on the other hand, come to bear by its other end, for example by its small base at 5, against the shaft or other rotating or sliding surface, in particular a shaft 2 established along the axis XX, to ensure sealing.

In conventional solutions, fixing in 4 is ensured by a frame integral with the elastomer and fixed on the support or bearing 3, while the force tending to maintain contact with the shaft 2 in 5 is most often provided by a coil spring mounted externally around the end, suitably formed, of the hollow body 1.

Provision is made, in accordance with the invention, for the prior insertion into the elastomer body 1, of a reinforcement preferably extending all along said body, and constituted by at least one helical spring 6, which is therefore, after molding and vulcanization, coated in the elastomer.

The presence of this spring 6 provides the assembly with good elastic deformability in the various directions, both axial and transverse, that is to say radial.

The possibilities of radial elastic deformation are taken advantage of in the case of a tree such as 2
on the one hand, to easily ensure the positioning of the seal in its support 3,
- and on the other hand, to maintain the elastic contact at 5 on the rotating surface, for example the shaft 2.

 The establishment can be done for example by providing in the support 3 a housing 7 (Figures 1 and 2), in which one can come to introduce a bead of suitable shape 8 formed at the corresponding base of the joint 1. This housing 7 can for example appear at the bottom of a corresponding cavity of the support 3 (Figure 1) or simply consist of a groove (Figure 2) formed on an internal face 9 of the support 3 (groove similar to those intended to receive for example in practice current of fixing rings or circlips).

For said installation, it will therefore suffice to take the seal, to exert on the base considered here the large base - a tightening tending to decrease its diameter, to adapt it to that of the corresponding opening 9 of the support 3 , then introduce it until the bead B arrives at the housing 7 and enters it. It then remains there due to the partial decompression of said bead and the significant reaction which continues to be exerted on the facing surfaces, by the presence of the spring.

 As for maintaining contact between the end 5 and the shaft 2 or the like, it takes place because the diameter of the contact lip 10, adjoining this base 5, is made, during molding, suitably less than that of the shaft 2, the positioning of the latter therefore having the effect of stretching the device 1 outwards and of maintaining this tension under the effect of the spring 6.

It is understood moreover that, in the foregoing and in what follows, the functions of the large base and of the small base can be reversed, and that in addition, the contact of the sealing lips can be made not only on trees or other cylindrical surfaces, but also on flat or other rotating or sliding surfaces.

 Thus, by way of example, FIG. 3, which has been divided into two parts A and B, shows, in part A, the seal obtained between a rotary or sliding flat surface II on which rests a lip 12 provided on the large base of the device 1, while part B shows the contact with a rotary or sliding flat surface 1 3, of a lip 1 4 on the small base, the two solutions possibly being able to coexist in the same assembly .

In this application (FIG. 3), that is to say assemblies for which the seal is produced on surfaces which are radially relative to the axis XX of the device according to the invention, the contact pressure p, on the surface to be sealed, instead of being presented in the radial direction as in FIGS. 1 and 2 (in which case, as we said, it is generated mainly by the possibilities of radial elastic deformation of the body 1 armature by the spring 6), is here mainly generated by the possibilities of elastic deformation of the said body along the direction of its axis yX and arranged parallel to this axis, the said possibilities being mainly due to the deformability of the spring 6 along the said axis and also to the rolling portions of elastomer separating the turns of said spring
it should also be understood that, from the examples described, one can imagine all other applications, in which in particular the mobile elements can be made fixed and vice versa, the invention obviously applying to mobile joints.

The invention would therefore also apply to rotating joints, taking advantage of the fact that the presence of the spring as a frame will tend to oppose the efforts of centrifugal force.

With regard to the manufacture by molding of the seals in accordance with the invention, any known process can be used. In FIG. 4, an embodiment has been illustrated which makes it possible to easily obtain several embodiments from '' a single basic element whose ends are modified after molding by a simple slicing or rEctification operation, depending on the mode of
selected operation.

We see in this figure 4 that in a suitable mold
requested in at least two parts, schematized only by a section along a contour a, b, c, d, e, f, g, h, delimiting the volume to be filled with the elastomer, we realize
by molding, after the spring 6 has been put in place, a body
of revolution in elastomer essentially comprising the
body proper 1, and at its ends two bases
flattened 15 and 16, from which, after demolding,
we can achieve by cutting or grinding, as appropriate, and appropriate profiles such as those shown in point
tillés year 17 and 18, that is, fixing beads such
that those of FIGS. 1 and 2, ie sealing lips,
such as 10, 12, 14 (Figures 1 to 3) according to the epplica-
tion planned.

During the molding operation,
the elastomer in a mold such as that of FIG. 4,
to provide means to temporarily support the res
exit 6 during said molding, in order to avoid its deformation
under pressure or for other reasons. These
means can be constituted for example in small
support elements distributed over the facing surface
of one of the faces of the mold (for example that shown
at e, f,; g, h, in Figure 41. These support elements of the
spring will come out automatically after molding being
driven by the mold when it opens
and / or leave small spaces in the molded part
which will not be annoying. All, other means for
will be provided for the same purpose.

The springs such as 6 may be of section
tight, rectangular, circular, elliptical or other
they may be subjected, during the molding of the elastomer, to tension or compression. They can be
steel or other thermally conductive materials
high mique. But they could also be in matters
plastic, for example polyamide or polyimide.

The thickness of the elastomer of the membrane 1 can
be either substantially constant, as shown, or variable between the two bases, according to any appropriate law.

Figures 5 to 10 illustrate some specific embodiments.

FIG. 5 illustrates a fixing by lug 23 on the support such as 3 in FIG. 1.

 FIG. 6 illustrates the case of double-sealing joints, comprising two supples 1 opposite one another, joined together by their large base, where for example is the bead 8 for fixing on the support 3. One could similarly establish two cones meeting by their small bases, with two sealing lips respectively on the large bases.

 Figure 7 shows that possibly the heeloldal spring 6 could not be continuous, but be limited in two elements respectively near the small base and the large base of the last supper.

It should also be noted that, in the various embodiments, one could use, in place of a single spring, two or more springs suitably combined, of the same diameter or of different diameters.

FIG. 8 shows, in the application to sealing against a movable flat surface such as 11 (case of FIG. 3A or 38), the use for sealing, of a grain of friction, such as 19 suitably supported by the corresponding base of the joint, here the small base. As a variant, it has been assumed, in this figure, that the large base was housed, here, in a housing 7 of the support 3, the end 81 of said base being of a shape suitable for this accommodation. this case also, it is the forces of extension or compression, of the bases of the joint, which ensure the mounting, both of the grain 19 in said joint, and of the latter in the housing 7
FIG. 9 shows that the seal according to the invention can also optionally include a frame 20 like known seals, or even also an external spring as indicated by dotted lines at 21
Finally, FIG. 10 shows that the joints in question can comprise multiple lips such as 101 102 10, for example two of these lips 101 102 cooperating with a movable flat surface such as 11, while another 103 is supposed to cooperate with the inclined face 22 of a shaft 2.

 In the foregoing, the application has been envisaged for seals intended more particularly to ensure a seal with respect to surfaces in relative movement.

However, one can imagine all other applications for which the devices according to the invention are interposed between at least two elements of an assembly, element s one of which is liable to undergo certain displacements, in particular under the effect of vibrations or -other alternative forces, compared to the other, in particular to achieve a damping.

 Thus, in FIG. 11, in order to fix ideas, provision has been made for the insertion of a device according to the invention, of axis XX, between two bodies C1 and C2, one of which C1 is for example fixed while the other, for example still supported by the first with insertion of said device, is subjected to forces F along the axis XX of the latter and possibly to lateral forces F1).

1
Here also, the ends 4 and 5 of the device
will be fixed in appropriate housing 7 and 71 res
pectively provided on the two bodies C1 and C2 (in this
last, with insertion for example of a kind of wedge
23).

Thanks to such a device, we will have the possibility,
by a particular choice of the module and the thickness of
The variable elastomer or not, as well as characteristics
of the spring (s), such as diameter, not variable
or not, cone angle, etc., to get a curve of fle
xibility at very low stiffness for variations in
load to be supported, around a nominal value F to sup
carry. This curve can be obtained thanks to the choice of
characteristics and the possibility of buckling of the e
the lastomer between the spirals of the spring.

The double work of bending and buckling allows
for example to produce a curve such as that of FIG. 12, where the arrows f of the elastic support have been plotted on the abscissa and the loads F on the ordinate, the useful zone being zone ab, corresponding to the portion of curve between a1 and b1.

These conditions can be achieved by properly classifying the various factors. Advantageously, the thickness e of the membrane, at least between the turns of spring 6, will be chosen to be of the order of magnitude of the diameter of said spring, the coating giving rise, as can be seen in FIG. 11, to a surface wavy interior.

 Here is an experimental example corresponding to a load M whose average value F is of the order of 10kg - Diameter Dî at the large base of the shock absorber: 52.0 mm - Diameter D2 at the small base of the shock absorber: 22 , 5 mm - Angle A of the last supper: 400 - Distance between the turns of the spring: 5.5 mm - Thickness of the membrane 1: of the same order of magnitude as the diameter of the turns of the spring.

- Rubber hem near 40.

In this example, it is the middle turns (here 2.5 to 33 which ensure the maintenance of a very low rigidity, in combination with the deformation of the rubber, rigidity which is not very variable in the areas a1 b of the curve. The rigidity can be around 104N / m (Newton per meter) and the frequency
specific to the whole of a value of the order of 5 hertz.

 One thus obtains a certain damping for all the other frequencies.

In general, we can say that the portion of curve a1 b1, corresponding to the zone of low rigidity, is almost comparable to a line of angle K
(the dotted one in figure 12) which would represent
the rigidity of the spring 6 considered by itself. But the presence of rubber. in particular at the ends, makes it possible to obtain the curve 0 a a2 m ensuring the limit of the deformations of the assembly to a determined zone (zone ab).

These results can be transposed in numerous fields of application. In particular, it is possible to envisage obtaining good shock absorber supports for rotating machines or apparatus, in particular on airplanes and other transport vehicles.

It is understood that, in each case, action will be taken on the various factors mentioned above to obtain the low rigidity required: in particular, the thickness of the rubber could be made variable between the small and the large base.

Following which, and whatever the embodiment adopted, it is possible to produce elastic devices whose operation is sufficiently apparent from the above so that it is unnecessary to insist on it, and which have, in relation to those of the genre in question already existing, many advantages, including
- that of simplifying assembly operations, thanks to the possibilities of controlled elastic deformation, due to the shape of the spring,
- to remove, again thanks to the pressure of this spring. the problems of expansion of the elastomer, in particular in the case where silicones are used,
- that, in the case of seals subjected to pressure from the liquid to be sealed, to better resist deformation under the effect of this pressure, the spring opposing it,
- that of allowing easy and always reproducible manufacturing under the same standard conditions,
- it, in the case of rotary joints, to resist ax effects of centrifugal force through the reaction exerted by the spring,
- and that of lending itself to particular applications, such as applications to damping supports.

As it goes without saying, and as it already follows from the foregoing, the invention is in no way limited to those of its modes of application and embodiments which have been especially envisaged: it embraces them, on the contrary, all variants.

Claims (15)

1. Elastomeric device, essentially comprising an elastomeric body of revolution, generated around an axis XX by a straight or curved profile, to be interposed between two parts or assemblies in relative movement, characterized in that the body of revolution is combined with at least one helical spring serving as a reinforcement on at least the major part of the device between its two bases, and coated in the elastomer. 2. Device, more particularly a seal, according to claim 1, characterized in that its relative elastic deformability, conditioned by the presence of the spring, is used to ensure the mounting of one of the bases of said body to the interior of at least one housing comprising a support, said base comprising for this purpose a sort of annular bead capable of being introduced into the corresponding housing by a radial deformation which is then partially released. 3. Device, more particularly a seal, according to claim 1, characterized in that its relative elastic deformability, conditioned by the presence of the spring, is used to ensure the existence and the maintenance of a pressure against a surface in relative movement.  4. Device according to claim 3, characterized in that the seal is made on the surface of an axis shaft substantially coincident with that of the device, the contact pressure being transverse to said axis (Figures 1 and 2). 5, Device according to claim 3, characterized in that the seal is made on a rotary surface or in relative sliding in a direction transverse to the axis of the device, the contact pressure itself being parallel or oblique to this axis (figure 31. 6. Device according to any one of the preceding claims, characterized in that the fixing of one of its ha ses on a corresponding support is done with 1 'a d - said ion of lugs or the like (Figure 5)  7. Device according to any one of the preceding claims, characterized in that it comprises two cones or the like joined by a common base where the connection can be made with a support or bearing (FIG. 6). 8. Device according to any one of claims 1 to 7, more generally according to claim 5, characterized in that the contact pressure is established by means of an intermediate contact grain, the mounting of which at the base corresponding to the device is preferably made thanks to a contact pressure obtained from the spring (figure 83. 9. Device according to any one of claims 1 to 8, characterized in that the spring is separated into at least two parts, for example at the two respective bases of the device.  10. Device according to any one of claims 1 to 8, characterized in that the spring is with fixed pitch or on the contrary at least partially with variable pitch.  11. Device according to any one of claims 1 to 8, characterized in that the thickness of the rubber is variable between the two bases of the device.  12. Device according to any one of the preceding claims, characterized in that this device is molded so as to give rise to a typical element, with at the two bases kinds of crowns which can then be shaped, by slicing or rectification, to give them the forms corresponding to the special uses envisaged (figure 43. 13. Device according to any one of the preceding claims, characterized in that the spring is subjected to a prestress of tension or compression during molding.  1 4. Device according to any of the preceding claims, characterized in that the spring is supported, during molding, by support elements adjoining the corresponding surface of the mold.  15. Device according to claim 1, characterized in that it is interposed between two assemblies connected respectively to its two large and small bases, one of the two assemblies being subjected to variable forces, in particular gravity, and said device being used in particular as a shock absorber, opposing, along its axis X-X, a reaction mainly resulting from the compression and bending of the whole of its elastic body and the spring, as well as from the buckling of the elastomer elements separating the turns of the spring.  16. Device according to claim 15, characterized in that, by an appropriate choice of its characteristics (diameter and pitch of the spring, angle of the last supper, thickness and modulus of the elastomer), it is made so that the rigidity of the '' together, i.e. the ratio between the applied force F and the deflection of the device, remains low for normal values of F, i.e. a variation of F around this normal value causes significant variations in the arrow f. 17. Device according to any one of claims 15 and 16, characterized in that it is applied to the suspension of machines or apparatus, in particular on aircraft or other transport vehicles.