FR2634529A1 - Elastic connection sleeve including a sliding mechanism of partially spherical shape - Google Patents

Abstract

This connection sleeve includes an internal sheath 10 having an element with a spherical external intermediate surface 12, an external sheath 14 installed radially outside the internal sheath and including two precompression parts 30, 32 extending horizontally inwards from axially opposite ends, a sliding sheath 16 being applied to the surface 12 and having axial slits 26 and at least one projecting part 20 defining a radial clearance with respect to the external sheath, and two elastic sleeves 28 inserted between the sheaths 16, 14, each elastic sleeve including a part in the form of a sealing bellow 34. Application particularly to the sleeves used in vehicle suspension systems.

Description

 The present invention relates to a connection sleeve using a sliding mechanism of partially spherical shape and relates more particularly to improvements of such a connection sleeve, which has a damping or vibration isolation function.

 For the connection of a shaft element, supported in such a way as to be able to pivot, such as for example a shaft, a connecting rod or a connecting member in a vehicle suspension system, to a hollow support element, it is known to use a connection sleeve, such as for example a suspension sleeve, which comprises a sliding mechanism of partially spherical shape. The connecting sleeve is interposed between the supported shaft member so that it can pivot and the hollow support member, so that the partially spherical sliding mechanism allows the supported shaft member to be able to pivot, to pivot in the circumferential direction of the connecting sleeve and to be inclined relative to the axis of the sleeve (so as to move in a plane parallel to the axis of the sleeve).

 An example of such a connecting sleeve is described in the Japanese utility model application, unexamined, submitted to public inspection N-62-17409 (dated February 2, 1987). The connection sleeve described in this publication includes an inner sleeve, part of which, axially intermediate, on its outer circumferential surface has the shape of a spherical surface element, an outer sleeve disposed radially outside of and coaxially with respect to the inner sleeve, en being spaced apart radially, and a sliding sleeve interposed between the inner and outer sleeves so that the outer circumferential surface of the sliding sleeve is kept in contact with the outer sleeve, while the surface circumferential of the sliding sleeve slides in contact with the spherical surface element-shaped surface of the inner sleeve.

 The connection sleeve indicated above has no damping or vibration isolation function. When this sleeve is used as a suspension sleeve or else in the form of another elastic sleeve suitable for exhibiting a vibration-absorbing capacity, the connection sleeve must be installed in such a way that a suitable elastic element forming padding or having a vibration damping effect is interposed between the outer sleeve and a hollow cylindrical support element located on a structure, on which the sleeve is installed. The use of a separate elastic element tends to increase the overall dimensions of the connection sleeve, as a whole.

 The known connecting sleeve generally uses separate sealing elements, arranged at the opposite axial ends of the sleeve and serving to seal between the inner and outer sockets, in order to thereby protect the surface forming element spherical surface of the inner sleeve and the matching sliding surface of the sliding sleeve, vis-à-vis the entry of foreign substances. These sealing elements are fixed to the outer sleeve, by press fit or matting, after assembly of the connection sleeve. The fact of providing the sealing elements in addition to the elastic element arranged externally, from the radial point of view, with respect to the external sleeve indicated previously leads to an increase in the number of assembly steps and in the cost of manufacturing the sleeve. .

 This is why an object of the present invention is to provide an inexpensive connection sleeve, which has relatively small dimensions, has a partially spherical sliding mechanism, suitably sealed and provides a desired capacity for damping or insulation. vibrations.

 The object indicated above can be achieved in accordance with the principle underlying the present invention, which provides a connection sleeve intended to connect two elements so as to allow their relative displacement, characterized in that it comprises: (a) a inner sleeve having a surface formed by a spherical surface element and formed in an axially intermediate part1 of the outer circumferential surface of the sleeve; (b) an outer sleeve disposed radially outside of and coaxially with respect to. the inner sleeve, being radially spaced therefrom, and comprising two annular precompression parts formed so as to extend radially inwards from opposite axial end parts of the outer sleeve; (c) a sliding bushing mounted on the inner bushing so as to be in contact with and slide over the surface constituted by a spherical surface element, the sliding bushing having a plurality of axial slots arranged so as to extend from one opposite axial ends, and at least one protruding portion formed on an outer circumferential surface, the sliding bushing and the outer bushing cooperating so as to define a predetermined radial clearance between the protruding part and an inner circumferential surface of the outer bushing; and (d) a couple of elastic sleeves disposed between the sliding sleeve and the outer sleeve. One of the elastic sleeves is compressed axially between one of the two precompression parts and the protruding part (s), and the other elastic sleeve. is axially precompressed between the other precompression part and the one or more protruding parts. The elastic sleeves are pre-compressed radially between the inner circumferential surface of the outer sleeve and the outer circumferential surface of the sliding sleeve. The elastic sleeves flex elastically allowing relative radial displacement between the inner and outer sleeves. Each elastic sleeve has a bellows-shaped portion formed integrally so as to extend from an outer axial end of the sleeve and covering, in a fluid-tight manner, a bare portion of the outer circumferential surface of the inner sleeve, which establishes a seal between the inner sleeve and the elastic sleeves thereby sealing the surface formed of a spherical surface element of the inner sleeve and the paired outer circumferential surface of the sliding sleeve. In the connection sleeve according to the present invention, arranged as described above, the surface in the form of a spherical surface element of the inner sleeve, the sliding sleeve and the elastic sleeves cooperate so as to allow relative movement of the sleeves inside and outside with respect to each other both in the axial direction and in the radial direction, as well as in the circumferential direction, and in the plane parallel to the axis of the connecting sleeve which allows obtain effective damping or isolation of an input vibration load. However, the connection sleeve has relatively small dimensions, is compact, and provides sufficient resistance to the applied load.

 The protruding part, provided at least in one copy, may be a single continuous circumferential protruding part formed over the entire circumference of the sliding sleeve.

 The axial slots can be spaced from each other in the circumferential direction of the sliding sleeve. Preferably, the axial slots are formed so as to extend alternately from opposite axial ends of the sliding bushing and have an axial length greater than half the axial length of the sliding bushing.

 The bellows-shaped portions of the elastic sleeves are preferably fixed to the bare outer circumferential surface of the inner sleeve, at an axial end of the latter, distant from the outer axial end of the elastic sleeves.

 The precompression of the elastic sleeves can be such that the latter penetrate, at least partially, into the axial slots formed in the sliding sleeve, so that the elastic sleeves and the sliding sleeve can act more or less in the form of a unitary assembly .

 Each of the elastic sleeves may have a circumferential cut formed in a part of the outer circumferential surface, so as to allow elastic deformation of the elastic sleeves.

 The annular precompression parts of the outer sleeve may be constituted by an inner flange, which extends internally, from a radial point of view, with respect to one of the opposite axial ends of the outer sleeve, and by a retaining ring fixed on the other external axial end so as to extend internally, from the radial point of view, relative to the other axial end.

Other characteristics and advantages of the present invention will emerge from the description given below, taken with reference to the appended drawings, in which:
- Figure 1 shows an elevational view, in axial cross section, of an embodiment of a connection sleeve according to the invention, which comprises a partially spherical sliding mechanism; and
- Figure 2 shows an elevational view, in axial cross section, of a partially spherical sliding bushing, incorporated in the connection sleeve of Figure 1.

 Referring first of all to the elevation view of FIG. 1, which shows an axial cross section of a connection sleeve, the reference 10 designates a metallic inner sleeve, which has a generally cylindrical shape and a wall having a relatively large thickness. The inner sleeve 10 has an intermediate axial portion having a relatively thick wall and having an outer surface 12, which is formed of a spherical surface element and projects radially outward. A metallic outer sleeve 14 is provided on the outside, from a radial point of view, with respect to the inner sleeve 10 so that this outer sleeve 14 is coaxial with and radially spaced from the inner sleeve 10, so as to cover the surface 12, formed of a spherical surface element, of the inner sleeve 10.

 The present connection sleeve is used to flexibly connect two elements (not shown), one of which is a pivot shaft and the other of which is a cylindrical support. The connection sleeve is installed so that the pivot shaft is inserted into the inner bush 10, while the cylindrical support is mounted on the outer surface of the outer bush 14.

 A sliding sleeve 16, which has an inner surface formed of a spherical surface element, is mounted so as to be able to slide on the outer surface 12, formed of a spherical surface element, of the inner sleeve 10. This sliding sleeve 16 has an axial length slightly less than that of the outer surface 12.

 The sliding sleeve 16 is made of a material formed of a suitable resin, preferably an oil-impregnated resin, such as for example oil-impregnated polyacetal, which makes it possible to obtain an improved sliding characteristic.

 As also indicated in FIG. 2, the sliding bush 16 has a central part, from the axial point of view, which has a diameter greater than that of the other axial parts. This central part, from the axial point of view, has an inner circumferential groove 18 formed in its inner surface. The circumferential groove 18 has a U shape when considering an axial cross section of the sliding sleeve 126, as shown in Figures 1 and 2. The central part from the axial point of view has an outer circumferential projection 20 extending over a suitable height from the other axial parts of the sleeve 16. The circumferential inner groove 18 cooperates with the surface 2, formed of a spherical surface element, of the inner sleeve 10 to define a circumferential reservoir of oil 22 used to house a lubricant. On the other hand, the circumferential outer projection 20 has a diameter less than the inner diameter of the outer sleeve 14 and cooperates with the inner circumferential surface of this outer sleeve-14 to define a circumferential gap 24 filled with air.

 This interval 24 is provided so as to allow a certain relative radial displacement between the inner and outer sockets 12, 14. The relative radial displacement of the two sockets 10, 14 is limited by the abutment of the circumferential protruding part 20 of the sliding bush 16 against the inner circumferential surface of the outer bush 14.

Consequently, the value of the radial clearance between the protrusion 20 and the outer bush 14, i.e. the radial dimension of the circumferential gap 24, is appropriately determined according to the required damping property. or vibration isolation, of this connection sleeve.

 The sliding sleeve 16 has a plurality of axial slots 26 formed on the thickness of its wall, so that the slots 26 extend alternately, from one or the other of the axial ends of the sleeve 16, in the- axial direction, over a length slightly greater than half the axial length of the sleeve 16. The axial slots 26 are spaced from one another in the circumferential direction of the sleeve 16. These slots 26 allow the passage of the lubricant used to lubricate the sliding surfaces of the sliding sleeve 16. The slots 26 also act by allowing the sliding sleeve 16 to expand radially outwards, which allows easy mounting of the sleeve on the external surface 12 formed of a spherical surface. The width and number of the axial slots 26 are determined as a function of the dimensions and the required characteristic of support of a load by the connection sleeve. For example, the axial slots 26 have a width lying in a range between 0.5 mm and 3 mm, and the number of slots 26 is generally between 3 and 7.

 Two elastic sleeves 28 are interposed between the sliding sleeve 16 and the outer sleeve 14 so that the two sleeves 28 are arranged on the opposite sides of the circumferential protrusion 20 of the sleeve 16, in the axial direction of the connection sleeve. Consequently, the sliding bush 16 is held in position between the inner and outer bushes 10, 14, by means of the elastic sleeves 28 interposed between these bushings. In other words, the inner and outer sockets 10,14 are elastically connected by the elastic sleeves 28 so that the sockets 10,14 are movable from all sides relative to each other, thanks to the presence of the outer surface 12 formed of a spherical surface element, and of the sliding bush 16.

 More specifically, the elastic sleeves 28 are made of an elastic material such as, for example, urethane rubber and have a partially spherical interior surface which adapts to the exterior surfaces of the sliding sleeve 16, on the opposite sides of the circumferential projection 20. The elastic sleeves 28 have an outer diameter substantially equal to or slightly greater than the inner diameter of the outer sleeve 14, before the sleeves 28 are mounted in the connection sleeve.

 As indicated in FIG. 1, the elastic sleeves 28 are held in abutment under pressure, at their end faces, which are axially internal, against the end faces, axially facing each other. screw, of the circumferential projecting part 20 of the sliding bush 16.

 The outer sleeve 14 has a re-entrant flange 30 formed at one of its opposite axial ends so as to extend in the inner direction from the radial point of view. In addition, the outer sleeve 14 has a retaining ring 32 fixed by matting on the other axial end.

 The re-entrant flange 30 and the retaining ring 32 are held abutting, under pressure, against the outer end faces of the respective elastic sleeves 28, so that the. sleeves 28 are precompressed in the axial direction between the inner flange 30 and the protruding part 20, and between the retaining ring 32 and the protruding part 20. Consequently, the re-entrant flange 30 and the retaining ring 32 constitute parts annular precompression of the outer sleeve 14, making it possible to achieve axial precompression of the elastic sleeves 28.

 In the connecting sleeve arranged as described above, the elastic sleeves 28 are axially precompressed by the inner flange 30, the retaining ring 32 and the circumferential projection 20, and are precompressed radially by the inner circumferential surface of the external sleeve 14 and by the external surfaces of the sliding sleeve 16. Consequently, the sliding sleeve 16 is retained elastically between the internal and external sleeves 10, 14, by means of the elastic sleeves 28.

 The elastic sleeves 28 being axially and radially pre-compressed in the manner described above, certain parts of the sleeves 28 are pushed against the outer surface of the sliding sleeve 16, and penetrate, at least partially, in the axial slots 26 formed in the sliding sleeve 16 , which has the effect that the latter is more or less fixed to the elastic sleeves 28.

 Each of the two elastic sleeves 28 has a circumferential cut 33 formed in the end part, which is axially external, of the external circumferential surface. The circumferential cutouts 33 cooperate with the inner surface of the outer sleeve 14 to define circumferential cavities 35 having an appropriate volume, so that the cavities 35 allow a certain degree of elastic deformation of the elastic sleeves 28.

 Each elastic sleeve 28 has a bellows-shaped portion 34, having a relatively thin wall formed in one piece so as to extend from the axially outer end of the sleeve , in the direction facing outward, from the axial point of view, beyond the axial ends of the outer sleeve 14.

 The sealing bellows portions 34 of the elastic sleeves 28 are fixed, at their axial ends, to the outer circumferential surface of the inner sleeve 10, using respective retaining rings 36, so that the surfaces the internal parts of the bellows 34 are held so as to be in contact, with the possibility of displacement by sliding, with the external surface of the internal sleeve 10.

 The sealing bellows portions 34 serve to protect the connection sleeve against the entry of foreign substances, such as for example dust, dirt and muddy water in the space between the outer surface 12, formed of a spherical surface element, of the inner sleeve 10 and the paired inner surface of the sliding sleeve 16, but thereby guarantee a uniform relative movement between the inner and outer sleeves 10, 14, in the circumferential direction of the connection sleeve and in the plane parallel to the axis of the latter.

 In the connection sleeve having the spherical sliding mechanism arranged as described above, it is possible to have an effective damping or isolation of the vibrations applied to the connection sleeve thanks to the elastic deformation of the elastic sleeves 28 capable of bending elastically and interposed between the inner and outer sockets 10.14.

In accordance with the present arrangement, the connection sleeve can be produced with a compact and simplified constitution, compared to a conventional connection sleeve, in which a vibration damping element is arranged externally, from a radial point of view, with respect to the outer sleeve.

 It will further be noted that the elastic sleeves 28 and the sliding sleeve 16 act, practically, as a unitary element, due to the axial precompression of the elastic sleeves 28 between the circumferential protruding part 20 of the sliding sleeve 16 and the axial ends opposite of the outer sleeve 14, and due to the partial engagement of the elastic sleeves 28 in the axial slots 26 formed in the sliding sleeve 16. In other words, no particular connection is necessary between the sliding sleeve 16 and the elastic sleeves 28 for retaining this sleeve and these sleeves between them according to a mutual contact meshing, during the application, to the connection sleeve, of charges capable of displacing the inner and outer sleeves 10,14 one relative to the other in the circumferential direction and in the plane parallel to the axis of the connecting sleeve (this direction and this p lan to be inclined between them, relative to the axis of the connection sleeve). Furthermore, the elastic sleeves 28 and the sliding sleeve 16 have a sufficiently large contact surface, which gives the inner sleeve 10 increased resistance to an axial load, which is applied to it.

 In addition, the circumferential protrusion 20 formed on the sliding sleeve 16 acts in the manner of a radial stop, which can abut against the internal surface of the external sleeve 14, when applying a radial load to the connecting sleeve, which limits the degree of radial displacement of the inner and outer sleeves 10,14 and, therefore, avoids an excessive degree of elastic deformation of the elastic sleeves 28 in the radial direction. Therefore, the present connection sleeve has improved durability and improved reliability and operating stability.

 It is also important to note that the present connection sleeve does not require any sealing element, nor any sealing procedure between the inner sleeve 10 and the elastic sleeves 28, after the assembly of this connection sleeve. Indeed on the elastic sleeves 28 are formed, in one piece, parts 24 forming sealing bellows, which extend from the inside of the outer sleeve 14 and overlap, in a sealed manner to fluids and with the possibility of sliding, the bare axial parts of the inner sleeve 10. This is why the present connection sleeve requires a comparatively reduced number of manufacturing and assembly steps and is therefore of manufacturing economic.

 Although the presently preferred embodiment of the present invention has been described, by way of illustration only, it will be understood that the invention is not limited to the details of the embodiment shown, but can be arranged in 'another way.

 For example, all the axial slots 26 can be formed in the sliding bush 16 so as to extend from the same axial end of the bush 16. In this case also, the length of the slots 26 is preferably not , not less than half the axial length of the bush 16, in order to facilitate the radial expansion of the bush 16 for easy mounting of the latter on the inner bush 10.

 Although the circumferential groove 18 is formed on the inner surface of the sliding sleeve 16, this groove 18 is not essential for the implementation of the concept of the present invention. In addition, the sliding sleeve 16 may include a plurality of such grooves 18 serving to form the oil tanks.

 In the embodiment shown, the circumferential protrusion 20 is formed continuously over the entire circumference of the sliding sleeve 16, which may have a plurality of protrusions spaced from each other in the circumferential direction, provided that these portions projecting cooperate with the outer sleeve 14 so as to axially compress the elastic sleeves 28 and to serve as a stop to limit the relative radial displacement of the inner and outer bushes 10,14.

 It will also be understood that other changes, modifications and improvements can be made, which can be imagined by those skilled in the art, to the present invention, without going beyond the scope of the latter.

Claims (10)

 1. Connection sleeve intended to connect two elements so as to allow their relative displacement, characterized in that it comprises  an inner sleeve (10) having a surface (12) formed by a spherical surface element and formed in an axially intermediate portion of the outer circumferential surface of the sleeve;  an outer sleeve (14) disposed radially outside of and coaxially with respect to said inner sleeve, being radially spaced therefrom, and comprising two annular precompression parts (30,32) formed so as to extend radially towards the 'interior from opposite axial end portions of said outer sleeve ;;  a sliding sleeve (16) mounted on said inner sleeve so as to be in contact and slide on said surface (12) constituted by a spherical surface element, said sliding sleeve having a plurality of axial slots (26) arranged so as to s extending from one of the opposite axial ends, and at least one protruding part (20) formed on an outer circumferential surface, said sliding sleeve and said external sleeve cooperating so as to define a predetermined radial clearance between said protruding part and a surface inner circumference of said outer sleeve;  a pair of elastic sleeves (28) disposed between said sliding sleeve and said outer sleeve, one of said elastic sleeves being axially precompressed between one of said two precompression parts and said protrusion (s), while the other elastic sleeve is axially precompressed between the other precompression part and said protruding part (s), said elastic sleeves being radially precompressed between the inner circumferential surface of the outer sleeve and the outer circumferential surface of the sliding sleeve, and said elastic sleeves flexing elastically allowing relative radial movement between said inner and outer bushes; and  each sleeve of said pair of elastic sleeves comprising a portion in the form of a sealing bellows (34) formed integrally so as to extend from an external axial end of said sleeve and covering, in a fluid-tight manner, a bare part of the circumferential outer surface of the inner sleeve thereby establishing a seal between said inner sleeve and said elastic sleeves.  2. Connection sleeve according to claim 1, characterized in that the said protrusion (s) (20) consist of a circumferential protrusion formed over the entire circumference of said sliding bush (16).  3. Connection sleeve according to claim 1, characterized in that said set of axial slots (26) are spaced from each other in the circumferential direction of said sliding sleeve (16) and extend alternately from opposite axial ends sliding sleeve.  4. Connection sleeve according to claim 1, characterized in that said set of axial slots (26) have an axial length greater than half an axial length of said sliding sleeve (16).  5. Connection sleeve according to claim 1, characterized in that said part forming a sealing bellows (34) of said elastic bushings (28) is fixed on the circumferential outer surface of said inner bushing (10), at a axial end of this sleeve, which is distant from said outer axial end of said elastic sleeves (28).  6. Connection sleeve according to claim 1, characterized in that said elastic sleeves (28) protrude at least partially in said axial slots (26) formed in said sliding sleeve (16).  7. Connection sleeve according to claim 1, characterized in that each of said elastic sleeves (28) has a circumferential cutout (33) formed in a part of the outer circumferential surface, in order to allow elastic deformation of the elastic sleeves.  8. Connection sleeve according to claim 1, characterized in that said pair of annular precompression parts (30,32) includes an inner flange (30), which extends radially inward from one of the opposite axial ends of said outer sleeve (14), and a retaining ring (32) fixed to the other axial end so as to extend radially inwards from said other axial end.  9. Connection sleeve according to claim 1, characterized in that said sliding sleeve (16) consists of a resin impregnated with oil.  10. Connection sleeve according to claim 1, characterized in that said elastic sleeves (28) are formed of urethane rubber.