GB2217663A

GB2217663A - Suspension thrust bearings

Info

Publication number: GB2217663A
Application number: GB8908480A
Authority: GB
Inventors: Fabrice Caron
Original assignee: SKF France SAS
Current assignee: SKF France SAS
Priority date: 1988-04-21
Filing date: 1989-04-14
Publication date: 1989-11-01
Also published as: GB2217663B; DE8904871U1; FR2630375B1; IT1233211B; FR2630375A1; IT8967289A0; GB8908480D0

Abstract

A suspension thrust bearing 9 comprises an upper ring 12, a lower ring 13, balls 14, a housing 25 for the balls, and a sleeve 15 for fixing the two rings together axially, characterised in that the sleeve 15 is substantially cylindrical and has a first annular bead 16 of a size allowing force-fitting past the inner edge of the upper ring 12 to ensure the retention of the latter, a second annular bead 18 of a size allowing force-fitting past the inner edge of the lower ring 13 and ensuring the retention of the latter, and a third annular bead 20 of a size allowing force-fitting past the inner edge of a lower annular member 11 and ensuring the retention of the latter with play, the lower annular member 11 forming part of a shock-absorber assembly for a vehicle with which the suspension thrust bearing 9 is to be utilised. The sleeve 15 has a dip 22 for engagement with the surface of the member 11 to act as a seal against ingress of water and dirt. The housing 25 has a similar lip 26 for engagement with upper ring 12. <IMAGE>

Description

Suspension Thrust Brings The invention relates to suspension thrust bearings.

This type of bearing currently used in the suspension devices for the guiding wheels of motor vehicles is usually accommodated between two dishes: - a stationary upper dish fixed to the vehicle body by means of a shock-absorbing rubber block, - a rotationally movable lower dish, on which the upper end of the suspension spring surrounding the shock absorber also comes to bear, the lower end of the spring bearing on another dish fixed to the shock-absorber cylinder.

This suspension thrust bearing, which will be referred to hereinafter as a suspension bearing, therefore performs the functions of: - transmitting the axial and radial forces arising as a result of the compression of the spring, and - at the same time allowing a virtually frictionless rotation between the spring and the vehicle body, this rotary movement of the spring occurring during the deflection of the guiding wheels and, to a lesser extent, during the variations in compression of the spring as a result of a winding effect of the spring turns.

The type of bearing generally employed for this use is a bearing comprising two sheet-metal rings, balls, a housing, a means of axial connection between the rings, and sealing means for protecting the interior of the bearing against the frequent splashes of water in this region of the vehicle.

The document FR-A-2,389,036 has already made known a bearing of the McPherson type with sheet-metal rings, the housing of which performs a threefold function, namely: .- the separation of the balls, - sealing, and - the axial retention of the rings in order to obtain an assembly which is unremovable during the manipulation of the bearing.

The main disadvantage of this type of bearing is that nothing is provided on the bearing for connecting it axially to the lower dish. On the other hand, it uses a type of one-piece snap-on housing which presupposes relatively simple ring forms with edges which are substantially plane and parallel on the snapping side.

Such a type of snap-on housing consequently cannot be used when there is a partial axial overlap of one of the rings in relation to the other.

Now in order to make the rings more rigid and protect the interior of the bearing against trickling water, McPherson sheet-metal suspension bearings very often adopt a radial interlocking and an axial overlapping of the lower ring by a turned-down rim of the upper ring.

Furthermore, the document FR-A-2,591,177 makes known a bearing with a double row of rolling elements and with a double inner ring, which comprises a cylindrical housing common to these rolling elements and a cylindrical sleeve for fixing the two inner rings together and in which the housing and the sleeve are produced in one piece and joined by means of connecting parts having weakened zones for the purpose of breaking them, thus making it possible to reduce the number of components and make the assembly manipulations easier, these zones being broken and the ring separated from the sleeve automatically during assembly as a result of an axial push exerted on the inner rings as a result of an asymmetry of the unit as a whole and a high resistance of the two cylindrical elements to axial compression.In contrast, such a technique cannot be used with a substantially plane housing which therefore exhibits high elasticity in the axial direction.

The object of the invention is to eliminate the abovementioned disadvantages by providing a suspension thrust bearing which at the same time ensures: - axial connection both between the rings of the bearing and between the assembled bearing and the lower dish, to make it easier to manipulate the unit as a whole at the manufacturer's during the operations of mounting the suspension system on the vehicle body, and -- reinforced protection of the bearing against water splashes, this being achieved in an especially economical way which can apply to bearings having an axial overlap of the lower ring by the upper ring.

For this purpose, the invention first of all uses a substantially cylindrical assembly sleeve intended to be introduced into the central passage within the assembly consisting of the two rings, this sleeve having a first annular bead for the retention of the upper ring, a second annular bead for the retention of the lower ring and a third annular bead or rim for the retention of the unit as a whole on the lower dish.

This sleeve preferably has an upper edge coming to bear on the inside of the upper dish, to provide additional protection against the infiltration of water.

The sleeve also preferably possesses, between the second and third boss, a thin lip coming to bear on the inside of the lower dish in order to prevent water from rising towards the seat of the bearing.

The bearing possesses, furthermore, a housing of substantially plane initial form, preferably having on its periphery a thin lip bearing against the upper ring in order likewise to ensure protection against the rising of water at the periphery The upper ring preferably has a form interlocking radially with and axially overlapping the lower ring, at least on the inside.

The initially substantially plane housing and the substantially cylindrical connecting sleeve are made of plastic molded in one piece, being joined by means of connecting parts located between the inside of the housing and the outside of the second boss and having weakened zones for the purpose of breaking them.This breakage causing the separation of the housing and the sleeve is obtained automatically, during the assembly of the bearing, as a result of shearing between the inner edge of the upper ring seated between the first bead and the base of the second bead and the inner edge of the lower ring at the moment when it crosses the apex of the second bead, this shearing at the same time causing the catching of the lower ring above the second bead and the conical elastic deformation of the initially substantially plane housing, contributing to the elastic bearing of the outer lip of the housing against the outer edge of the upper ring.

Other particular features of the invention will emerge from the following description of an embodiment taken as an example and illustrated in the accompanying drawing in which: Figure 1 is an axial section through the suspension head as a whole; Figure 2 is a top view of the sleeve/housing assembly; Figure 3 is a partial axial section of this assembly in its initial form on a larger scale; Figures 4, 5, 6 and 7 show, in partial axial section, the successive phases of the assembling of the bearing; Figures 8, 9 and 10 show, likewise in partial axial section, the successive phases of the mounting of the bearing on the lower dish and on the upper dish; Figure 11 is an external elevation view of an alternative embodiment.

Figure 1 shows the shock-absorber cylinder 1, the rod 2 of which is fastened to the vehicle body 3 by means of an outer piece 4 welded to the body 3, an inner piece 5 onto which the end of the rod 2 is mounted by means of a nut 6, and a rubber block 7 adhesively bonded between the two concentric pieces 4 and 5. Furthermore, also embedded in this rubber block is the upper end of the upper dish 8 serving as a support for the thrust bearing 9, the details of which will be seen later.

The suspension spring 10 is also shown, its upper end bearing on the lower dish 11 which in turn also bears on the thrust bearing 9.

The unit 4-5-7-8 is thus fastened to the vehicle in advance, and the rest of the suspension is introduced subsequently via the lower part and assembled by means of the nut 6 at the moment when the suspension is installed.

The actual suspension bearing 9 comprises an upper ring 12 and a lower ring 13 which are made of sheet metal and between which balls 14 are seated. The assembly consisting of the two rings 12 and 13 is joined by means of a connecting sleeve 15 which can be seen in more detail in Figure 3.

This sleeve 15, preferably made of molded plastic, is of general cylindrical form and is intended to be introduced into the central orifice of the assembly consisting of the two rings 12 and 13. In particular, it has a first bead 16 of an outside diameter larger than the inside diameter of the upper ring 12, to allow the force-fitting of the inner edge 17 of the upper ring 12 as a result of the radial compression of the sleeve 15 (see especially Figures 4 and 8). This sleeve 15 possesses, on the other hand, a second annular bead 18 of an outside diameter larger than the inside diameter of the lower ring 13, likewise to allow the force-fitting of the inner edge 19 of the lower ring 13 and subsequently ensure the retention of this edge (see especially Figures 6, 7 and 8). At the same time, the base of the second bead 18 serves as an abutment for the inner edge 17 of the upper ring 12.

Finally, the sleeve 15 also has a third bead or inner edge 20 of an outside diameter larger than the inside diameter of the lower dish 11, as shown especially in Figures 8, 9 and 10, so as to ensure the force-fitting and retention with play of the inner edge 21 of the lower dish 11.

Between the beads 18 and 20 there is preferably a thin lip 22 coming to bear on the inside diameter of the edge 21, to provide additional protection against the rising of water. At the same time, the upper edge 23 of the sleeve likewise comes to bear, without play, on the inner edge of the upper dish 8, as can be seen in Figure 10, in order likewise to provide additional protection against water and dirt inside the seat of the bearing.

The various bearing balls 14 are, of course, mounted in the cells 24 of a housing 25 which is likewise made of molded plastic and the initial form of which is substantially plane, as shown in Figure 3, this housing advantageously likewise having, on its periphery, a thin lip 26 coming to bear on the edge of the upper ring, as shown especially in Figures 8, 9 and 10, so as likewise to provide protection against the rising of water at the periphery.

As can be seen in the Figures, the upper ring 12 preferably has an enveloping form interlocking radially and projecting axially below the edges of the lower ring 13, so as to protect the interior of the bearing against trickling water. It is clear that this overlap in no way impedes the mounting and functioning of the sleeve 15 which performs its three retaining functions and its additional sealing functions.

Furthermore, this arrangement can be utilized according to the invention, in order to produce the housing 25 and the sleeve 15 in a single molded piece, the two parts being joined, as shown in Figure 2, by means of uniformly distributed connecting studs 27 which each connect the inner edge of the housing 25 to the outer edge of the second annular bead 18 by means of a part especially thinned in this region to form a predetermined breaking point.

In fact, despite the high axial elasticity of the housing 25, the initial form of which is substantially plane and which can easily be deformed elastically into the form of a cone, nonetheless this breakage of the connecting studs 27 after assembly can be obtained, according to the invention, as a result of a shearing effect between the edge 17 of the upper ring and the edge 19 of the lower ring.

Moreover, it has been seen that all the assemblies act as a result of the radial compression of the sleeve 15, -and where appropriate this can be made easier, if required, by providing axial slits 28, as shown in Figure 11.

To carry out the assembly of the bearing at the bearing manufacturer's and then its mounting on the suspension and the installation of this suspension on the vehicle by the car manufacturer, the following procedure can advantageously be adopted.

In a first stage illustrated in Figure 4, the upper dish 12 is placed in the upturned position and the sleeve 15, likewise in the upturned position, is introduced there by force-fitting from the top. It will be seen that, in this phase, the housing 25 experiences elastic deformation and loses its initial plane form to assume a slightly conical form, without this having the effect of breaking the studs 27 for the reason mentioned above.

In a second stage, the balls 14 are placed in the various cells 24, as shown in Figure 5.

Subsequently, as illustrated in Figure 6, the lower ring 13, likewise in the upturned. position, is placed on the assembly and an axial push is exerted on the rings 12 and 13 to bring them closer to one another.

In this movement, the base of the bead 18 comes to bear on the top of the edge 17 of the upturned upper ring 12, whilst the inner edge 19 of the other ring slides on the slope of the second bead 18.

This leads simultaneously to two effects illustrated in Figure 7, the first being the breakage by shearing of the inner end of the studs 27, and the second being the engagement of the edge 19 underneath the second bead 18, henceforward ensuring the retention of all the components in the form of an unremovable subassembly, whilst at the same time the housing 25 increases its movement of conical elastic deformation, pressing the peripheral lip 26 elastically on the inside of the outer edge 29 of the upper ring 12.

The bearing 9 is supplied in this state to the manufacturer who carries out the following assembly phases.

First of all, the bearing 9 as a whole, now placed in the normal position, is arranged above the lower dish 11, as illustrated in Figure 8, and then fixed in position as a result of axial compression, as shown in Figure 9, the effect of this being to ensure the deflection of the sealing lip 22, but above all to ensure the retention of the bearing 9 as a whole on the lower dish 11 by means of the third bead 20, despite the functional play existing between these components.

The suspension as a whole, comprising the cylinder 1, its rod 2, the spring 10 and the dish 11, can then be handled without any special precaution and without the risk of losing the bearing 9, in order to introduce it via the lower part of the vehicle body, until it passes through the inner piece 5, in order to screw the nut 6. In this last operation, the upper ring 12 of the bearing fits into the upper dish 8, and the upper edge 23 of the sleeve 15 comes to bear on this dish in order to perform its sealing function.

It will therefore be seen that the suspension bearing according to the invention makes it possible simultaneously to ensure triple retention and triple sealing, whilst using only a minimum number of components and assembly manipulations.

Claims

1. Suspension thrust bearing comprising an upper ring, a lower ring, balls, a housing for the balls and a sleeve for fixing the two rings together axially, the sleeve being substantially cylindrical and having a first annular bead of a size allowing it to have been force-fitted past the inner edge of the upper ring to ensure the retention of the latter, a second annular bead of a size allowing it to have been force-fitted past the inner edge of the lower ring to ensure the retention of the latter, and a third annular bead of a size for allowing force-fitting past the inner edge of a lower annular member for ensuring the retention of the latter with play, the lower annular member forming part of an assembly with which the suspension thrust bearing is capable of being utilised.

Suspension thrust bearing according to claim 1, in which the sleeve also possesses a thin resilient lip located between the second annular bead and the third annular thread and intended for coming to bear cn the inner edge cf the lower annular member in order to ensure additional sealing.

3. Suspension thrust bearing according to claim 1 or claim 2, in which the upper edge of the sleeve is resilient and is intended for coming to bear on the inner edge of an upper annular member, also forming part of the assembly with which the suspension thrust bearing is capable of being utilised, in order to ensure additional sealing.

4. Suspension thrust bearing according to any preceding claim, in which the housing has a substantially plane initial form and possesses on its outer periphery a sealing lip bearing resiliently on the outer edge of the upper ring as a result cf a conical deormtio so as to improve the sealing at that location.

5. Suspension thrust bearing according to any preceding claim, in which the sleeve has slits increasing its radial compressibility.

6. Suspension thrust bearing according to any preceding claim, in which the edges of the upper ring envelop radially and project axially below the edges of the lower ring, at least on the inside.

7. Suspension thrust bearing according to any preceding claim, in which the housing has a substantially plane initial form joined to the substantially cylindrical sleeve by means of connecting studs located between the inner edge of the housing and the periphery of the second annular bead and having a weakened zone in the region of that bead, the housing and the sleeve having been moulded in one piece and Installed in this form and the bringing of the twe rings closer to one another during assembly having ensured the breakage of the connecting studs as a result of shearing, between the inner edge of the upper ring and the inner edge of the lower ring, whilst the inner edge of the lower ring is force-fitted past the second annular bead.

8. Suspension thrust bearing substantially as hereinbefore described with reference to Figures 1 to 10, or the modification of Figure 11, of the accompanying drawings.

9. Suspension thrust bearing according to any preceding claim, when placed between a stationary upper dish and a rotationally movable lower dish, which constitutes the lower annular member and serves as a support for a suspension spring surrounding a shock-absorber cylinder, the rod of which is fastened at its upper end to the body of a vehicle.

10. Process for assembling and installing the suspension thrust bearing according to claim 9, in which the upper ring is placed in the upturned position, the sleeve is secured thereto via the upper part by force-fitting past the first annular bead, the balls are placed in the housing in the upper ring, the lower ring is placed in the upturned position above the assembly so as to bear on the second annular bead, the rings are then brought closer together as a result of an axial push exerted on them, in order to ensure simultaneously the breakage of the housing from the sleeve if previously connected, the catching of the inner edge of the lower ring beyond the second annular bead and the conical deformation of the housing, the bearing then being mounted in the position of use on the lower dish as a result of locating the bearing in place on the inner edge of the lower dish by means of the third annular bead, before the entire unit is introduced in position in the upper dish.