GB2109874A

GB2109874A - Wheel bearing unit

Info

Publication number: GB2109874A
Application number: GB08228849A
Authority: GB
Inventors: Horst Manfred Ernst; Heinz Kiener; Rainer Schurger; Gerhard Tilch; Gunter Neder; Otmar Winkler; Egon Pfaller; Jurgen Schwartz; Franco Colanzi
Original assignee: SKF Kugellagerfabriken GmbH
Current assignee: SKF GmbH
Priority date: 1981-10-10
Filing date: 1982-10-08
Publication date: 1983-06-08
Also published as: IT8249261A0; IT8249261A1; IT1189384B; FR2514301A1; JPS5876303A; GB2109874B; DE3140373A1; FR2514301B1

Abstract

A wheel bearing unit (10) is disclosed having an inner race ring (13) with a through bore (14), a flange (21) at one end and a constant velocity joint (25) in the bore at the other end. To centre the wheel (11) or wheel (11) and brake disc (12) precisely and to seal the bore (14) to protect the constant velocity joint (25), a generally cup shaped annular centring element (39) is provided with a portion (40) lying in and hold fast in the bore and forming a seal with the bore. A wall (47) closes the bore of the element (39). A portion (42) of the element lies outside the bore and provides one or more centring surfaces (43,44). The centring surfaces (43,44) and the bore seating surface are co-axial. <IMAGE>

Description

SPECIFICATION Wheel bearing unit This invention is concerned with a wheel bearing unit.

The invention relates to a bearing unit for a driven wheel of a vehicle having a radially inner race ring with a radially outwardly extending flange at one end for connection to a wheel a joint, such as a constant velocity joint, in the bore of the inner race ring at the other end for transmitting drive, a radially outer race ring for connection to the vehicle body, and rolling elements arranged to roll between and on the raceways of the race rings.

A bearing unit of this type is shown in Patent Specification DE (OLS) 27 08 416(saudi). The construction disclosed therein includes an integral wall in the bore of the inner race ring which closes the bore and protects the joint from the exterior.

The blank for the inner race ring must be produced by forging or pressing with relatively high deformation forces. Moreover the race tracks for constant velocity joint and the race tracks for the bearing cannot always be hardened satisfactorily and sometimes hardening cracks will arise at the transition between the wall of the flange and the annular part of the blank.

In some respects therefore, there are advantages in the inner race ring having an axially extending through bore and such a construction is shown in Patent Specification DE (OLS) 25 22 841 (Liihr). In the construction disclosed therein the inner race ring of the bearing and the outer part of the constant velocity joint are friction welded together. To protect the constant velocity joint from the exterior, a dished lid is secured in the bore of the inner race ring adjacent to the constant velocity joint. This lid is separate from any means used to centre the inner periphery of the wheel or the inner peripheries of the wheel and the brake disc when being connected to the flange of the inner race ring.

Figure 3 of Patent Specification DE (OLS) 24 57 949 (SKF) shows a wheel bearing unit of the basic type described with the inner race ring having an axially extending through bore. The construction disclosed therein includes a centring ring which is fastened to the surface of the flange axially facing away from the other end of the bore of the inner race ring and a shoulder provided by the flange. The centring ring and shoulder provide centring surfaces for the inner periphery of the wheel or the inner peripheries of the wheel and the brake disc.

The centring ring can be fastened to the flange by welding or screwing for example. However the centring ring, in use of the unit, is subject to radial impact loads, and loads directed in the plane of the axially facing surface of the flange will tend to shear the means of attachment of the centring ring to the flange. Difficulties also arise in fitting the centring ring so that it is precisely co-axial with the bore of the inner race ring.

The centring surface provided by the shoulder of the flange is strong in shear. However this shoulder can be machined into the face of the flange only by a relatively expensive cutting process.

This unit also requires a means of protecting the joint from the exterior, such as the lid disclosed in DE (OLS) 25 22 841-see above.

Such a lid must provide a seal and be resistant to impacts.

The object of the invention is a construction of the wheel bearing unit of the type given above in which means are provided which is strong and yet enables the wheel or the wheel and the brake disc to be precisely centred with respect to the inner race ring and which provides a strong seal in the bore of the inner race ring to protect the joint from the exterior.

In one aspect, the invention provides a combination of an inner race ring and an annular centring element of wheel bearing unit for securing a driven wheel to a vehicle, the inner race ring having an axially extending through bore, at one end a radially outwardly extending flange and at the other end in the bore an output part of a joint for transmitting drive, the annular centring element having a first portion held fast in the bore of the inner race ring at the end having the flange and forming a seal with the bore of the inner race ring, a second portion lying outside of the bore of the inner race ring and projecting axially beyond the flange, which second portion provides a centring surface or surfaces for the inner periphery of a wheel or the inner peripheries of a wheel and a brake disc, and a wall closing the bore of the annular centring element, the radially outer surfaces of the first and second portions being co-axial.

In another aspect, the invention provides a wheel bearing unit for securing a driven wheel to a vehicle and comprising a radially inner race ring having an axially extending through bore, at one end a radially outwardly extending flange for attachment to the wheel and at the other end in the bore a joint for transmitting drive, which joint can accept a certain amount of misalignment between its input and output members, a radially outer race ring for attachment to the body of the vehicle, rolling elements disposed between and for rolling on the raceways of the race rings, and an annular centring element which is disposed in the bore of the inner race ring at the end having the flange, is held fast in the bore and forms a seal with the bore of the inner race ring, which annular centring element extends axially out of the bore past the flange of the inner race ring and provides a centring surface or surfaces for the inner periphery of a wheel or the inner peripheries of a wheel and a brake disc, the centring surface or surfaces being co-axial with the bore of the inner race ring and the annular centring element having a wall closing its bore.

The bore of the inner race ring is closed by the annular element and its wall so that the joint is protected from dirt penetrating into the joint and is protected from the impact of stones from the exterior.

By having a through bore, the difficulties of hardening that arise with an inner race ring having an integral radial wall in its bore are not experienced-see the discussion of Specification DE (OLS) 27 08 416 above. To produce an annular blank for an inner race ring having a through bore, only relatively low forging or pressing forces are required which means that the risk of cracks arising in the forming stages or in the later machining and hardening stages is much reduced.

The annular blank with the through bore can be kept clamped in the same position in the machine tool as the seating surface for the annular element in the bore and the joint surfaces in the bore of the blank are machined to a finish. This means that the bore seating surface and the joint surfaces are exactly aligned with one another and therefore the inner periphery of the wheel or the inner peripheries of the wheel and the brake disc are aligned with the axis of the joint in the bore of the inner race ring. Accordingly only low off centre masses effect the inner race ring when it is rotating and so therefore the inner race ring is subject only to relatively small unbalancing forces which means that only relatively small additional masses are required to be fitted to the wheel body to balance it.

Preferably the centring surface or surfaces is or are cylindrical and the portion of the annular centring element lying in the bore of the inner race ring is cylindrical; and the wall of the annular centring element is positioned at one end of the element.

With these two features, the annular centring element can be produced with extreme accuracy of shape and economically by rolling reduction or deep drawing from strip material-that is sheet metal such as steel, so that no expensive machine cutting of the annular centring element is required.

Preferably, the annular centring element is held fast by an interference fit or by being welded in the bore of the inner race ring since these are relatively cheap ways of securing the annular centring element.

Embodiments of the invention will now be described by way of example and with reference to the accompanying drawings, of which: Figure 1 is a longitudinal section of one embodiment of a wheel bearing unit according to the invention; and Figures 2 to 6 are each a longitudinal section of different embodiments of the invention, each Figure showing an inner race ring and annular centring element.

Referring to Figure 1 , a wheel bearing unit 10 is attached to the inner periphery 11 of a wheel and the inner periphery 12 of a brake disc.

The wheel bearing unit 10 comprises an inner race ring 13, which has an axially extending through bore 14, an outer race ring 15 and two rows of balls 1 6 arranged between the two race rings to roll on the raceways 17 and 18 of the space rings. The outer race ring 1 5 has a radially outwardly extending flange 1 9 with screwthreaded bores 20 for connection to the suspension of a motor vehicle. At one end the inner race ring 13 has a radially outwardly extending flange 21 with screw threaded bores 22. Screw-threaded members 23 extend through apertures in the inner peripheries 11 and 12 of the wheel and brake disc and into the bores 22 and secure the wheel and brake disc to the inner race ring 13.The inner periphery 12 of the brake disc is secured against the face 24 of the flange 21 facing axially away from the other end of the inner race ring 13 and between the flange and the inner periphery 11 of the wheel.

At the other end of the inner race ring 13 to the flange 21 a constant velocity joint 25 is arranged in the bore 14. The joint 25 comprises a spherical inner input member 26 having longitudinal grooves 27 in its outer surface, longitudinal grooves 28 formed in the spherically curved end surface of the bore 14 of the inner race ring 13, and balls 29 arranged to roll along the grooves and located in a cage 30. The inner race ring 13 forms the output member of the constant velocity joint 25. The input member 26 has a cylindrical central bore with longitudinal splines and a drive shaft 31 from the vehicle, which shaft is also splined at its end, extends into the bore. The constant velocity joint 25 transmits drive from the drive shaft 31 to the inner race ring 13 through the input member 26, the grooves 27, the balls 29 and the grooves 28, and thus drives the wheel.

An annular sheet metal cap 32 is disposed between the flange 21 of the inner race ring 13 and the outer race ring 1 5 and has a portion 33 which extends radially and is spaced from the flange 21. The cap 32 engages over the radially outer circumferential surface of the flange 21 and at its radially inner periphery engages firmiy in a groove in the annular circumferential surface of the inner race ring 13.

An elastic sealing ring 34 is secured in a groove in the outer surface of the end of the outer race ring 1 5 near the flange 21 of the inner race ring 13 and has two sealing lips in sliding contact with the radially extending portion 33 of the annular cap 32. A sheet metal protective sleeve 35 is arranged around the sealing ring 34 and extends axially towards but stops short of the annular cap 32.

An eiastic sealing ring 36 engages in a groove in the bore of the outer race ring 1 5 at the end nearer the constant velocity joint 25 and is in sliding contact with the outer circumferential surface of the inner race ring 13.

A slightly corrugated resilient sleeve seal 37 is fixed at its radially outer end around the end of the inner race ring 1 3 at which the constant velocity joint 25 is disposed by a clamping ring 38, and its radially inner end engages around the drive shaft 31 This sleeve seal 37 prevents dirt from entering the joint 25 and prevents lubricant in the bore 14 of the inner race ring 13 from escaping.

To centre the wheel and the brake disc in the inner race ring 13, an annular centering element 39 is provided of a generally cup shape. The centring element 39 has a portion 40 extending into the bore 14 of the inner race ring 1 3 at the end having the flange 21. This portion 40 lying inside the bore 14 of the inner race ring 13 has an outer cylindrical surface 41 which is a press or interference fit in the bore 14 and forms a seal therewith. The centring element 39 also has a portion 42 extending axially out from the bore 14 of the inner race ring 1 3 and past the axially facing outer surface 24 of the flange 21.This portion 42 lying outside the bore 14 of the inner race ring 1 3 has a stepped cylindrical surface providing an axially outer centring surface 43 for the inner periphery 11 of the wheel and a large diameter axially inner centring surface 44 for the inner periphery 12 of the brake disc. The cylindrical surfaces 41,43 and 44 are all arranged on a common axis.

The centring element 39 also has a radially outwardly extending annular flange 45 which extends into a step 46 in the bore 14 of the inner race ring 1 3 at the end where the flange 21 is disposed. When the screw-threaded members 23 are screwed into the bores 22 in the flange 21, the annular flange 45 of the centring element 39 is trapped in the step 46 and clamped between the opposing faces of the inner periphery 12 of the brake disc and the step. The centring element 39 is thus held fast to the inner race ring 13.

The centring element 39 has at its end innermost in the bore 14 of the inner race ring 13 a radially extending flat wall 47 closing the bore of the annular element 39.

The annular centring element 39 can be produced from steel by hot or cold pressing without cutting.

In the production of the inner race ring 13, a blank having an axially extending through bore is first produced by forging or pressing. The axially facing surface 24 of the flange 21, the race tracks 1 7 for the bearing, the ball grooves 28 for the constant velocity joint 25 and that part of the bore 14 for accommodating the inner portion 40 of the annular centring element 39 are then machined.

Figure 2 shows in longitudinal section an inner race ring 48 and a generally cup shaped annular centring element 49 of a wheel bearing unit and the inner periphery 50 of a brake disc. The inner race ring 48 has a through bore 51 and grooves in the bore at one end for a constant velocity joint.

At the other end, the inner race ring 48 has a radially outwardly exending flange 52 with a surface 53 facing axially away from the end for the constant velocity joint.

The annular centring element 49 has a portion 54 which extends into the bore 51 of the inner race ring 48 and is held fast there. The portion 54 has an outer cylindrical circumferential surface which forms a seal with the bore 51 of the inner race ring 48, which surface includes a smaller diameter surface 55 merging smoothly with a larger diameter surface 56, as does the bore 51.

Part of the larger diameter surface 56 forms part of a portion 57 of the annular centring element 49 extending past the face 53 of the flange 52. The inner periphery 50 of the brake disc is centred pn part of the surface 56 lying outside the bore 51.

The portion 57 includes a smaller diameter cylindrical circumferential surface 58, merging with surface 56, for centring the wheel (not shown). The cylindrical surfaces 55, 56 and 58 are all co-axial.

The annular centring element 49 includes a radially extending wall 59 disposed at the end of the element in the bore 51 of the inner race ring 48 and closing the bore of the element.

The centring element 49 is fixed in the bore 51 of the inner race ring 48 by welding at 60.

Figure 3 shows in longitudinal section an inner race ring 61 and a generall cup shaped annular centring element 62 of a wheel bearing unit and the inner periphery 63 of a brake disc. The inner race ring 61 has a through bore 64, a radially outwardly extending flange 65 at one end with a surface 66 facing axially away from the other end, and grooves in the bore at the other end for a constant velocity joint.

The annular centring element 62 has a constant outer diameter cylindrical circumferential surface. A portion 67 of the element 62 lies in the correspondingly cylindrical portion of the bore 64 and is held fast there. The portion 67 has an outer surface 68 which forms a seal with the bore 64 of the inner race ring. The centring element 62 also includes a portion 69 extending axially past the face 66 of the flange 65 and lying outside of the bore 64. This portion 69 provides a cylindrical centring surface 70 for the inner periphery of a wheel (not shown). The inner periphery 63 of the brake disc is centred on a stepped surface 71 provided by the flange 65.

The centring element 62 also includes a radial wall 72 closing the bore and arranged at the end of the element 62 disposed inside the bore 64 of the inner race ring 61 and abutting a radially inwardly projecting flange 73 in the bore 64.

Figure 4 shows in longitudinal section an inner race ring 74 and a generally cup shaped annular centring element 75 of a wheel bearing unit and the inner periphery 76 of a brake disc. The inner race ring 74 has a through bore 77, a radially outwardly extending flange 78 at one end with a surface 79 facing axially away from the other end, and grooves in the bore at the other end for a constant velocity joint.

The annular centring element 75 is made from spring steel and has a relatively thin wall. A portion 80 of the element 75 lies in the bore 77 of the inner race ring 74, is held fast there by the spring resilience of the element, and has an outer cylindrical circumferential surface 81 forming a seal with the bore 77. A second portion 82 of the element 75 extends axially past the face 79 of the flange 78 and this portion provides an outer circumferential cylindrical centring surface 83 for the inner periphery 76 of the brake disc, which surface is a continuation of surface 81. This portion 82 provides a smaller diameter portion with a cylindrical outer circumferential centring surface 84 for the wheel (not shown).The centring element 75 includes a domed wall 85 closing the bore of the element 75 and disposed at the end of the element inside the bore 77 of the inner race ring 74, this domed wall 85 acting radially outwardly against the bore 77.

Figure 5 shows in longitudinal section an inner race ring 86 and a generally cup shaped annular centring element 87 of a wheel bearing unit and the inner periphery 88 of a brake disc. The inner race ring 86 has a through bore 89, a radially outwardly extending flange 90 at one end with a surface 91 axially facing away from the other end, and grooves in the bore at the other end for a constant velocity joint.

The annular centring element 87 is made from a relatively thin walled material and has a portion 92 extending in the bore 89 of the inner race ring 86 with an outer cylindrical circumferential surface 93 which is an interference or press fit and is in sealing contact with the bore 89.

Projections 94 extend radially outwardly from the free end of the portion 92 and into an annular groove 95 in the bore 89 of the inner race ring 86 and axially fix the centring element 87 to the inner race ring. The centring element 87 also has another portion 96 extending outwardly past the face 91 of the flange 90 and providing an outer cylindrical circumferential centring surface 97 for the inner periphery 88 of the brake disc, which surface is a continuation of surface 93. The portion 97 also has a stepped part providing a smaller diameter outer circumferential cylindrical centring surface 98 for the wheel (not shown), which surface 98 is co-axial with surface 93, 97.

The centring element 87 has a radially extending wall 99 closing its bore and disposed at the free end of the element outside the bore 89 of the inner race ring 86. This stiffens the portion 96 of the element providing the centring surfaces 97 and 98 and allows the use of thinner walled material. The centring element 87 is fitted to the inner race ring 86 by being pushed into the bore 89 from left to right in the drawing with the projections 94 pressed radially inwardly until they reach the groove 95 where they snap out into the groove.

Figure 6 shows in longitudinal section an inner race ring 100 and a generally cup shaped annular centring element 101 of a wheel bearing unit and the inner periphery 102 of a brake disc.

The inner race ring 100 has a through bore 103, a radially outwardly extending flange 104 at one end with a surface 105 facing axially away from the other end, and grooves in the bore at the other end for a constant velocity joint The annular centring element 101 is made from sheet steel with a closed end 106 lying outside the bore 103 and a part of the side wall doubled-over and extending into the bore of the inner race ring 100. The portion 107 of the centring element 101 lying in the bore 103 is composed entirely of the doubled over portion, has an outer circumferential cylindrical surface 108 and is a driving or force fit in the bore 103 securing the centring element firmly in place.The portion 109 of the centring element 101 lying outside of the bore i 03 away from the face 105 of the flange 104 includes a part of the doubledover portion, which latter provides a strong outer circumferential cylindrical centring surface 110 for the inner periphery 102 of the brake disc.

Welds 111 prcvide a bevelled surface from the double thickness portion down to the single wall thickness portion, and the single wall thickness portion provides an outer circumferential cylindrical centring surface 112 for the wheel (not shown) co-axial with cylindrical surface 108, 110. The closed end 106 stiffens the centring surface 112 against impacts from the wheel.

In the bore 103 of the centring element 101 is disposed a lubricant absorbing material 11 3 such as an open cell plastics material. This provides a lubricant reservoir for the constant velocity joint.

Modifications to the illustrated and described embodiments are envisaged. For example, the centring surfaces provided by the centring element need not be cylindrical and may be polygonal, for example rectangular, in crosssection. With a similar cross-sectional shape of the bore for the inner periphery of the wheel or brake disc, shape engagement between the wheel or brake disc and the centring surface is achieved preventing relative rotation.

The centring element can also be held fast in the bore of the inner race ring by the use of adhesive.

Claims

1. A combination of an inner race ring and an annular centring element of a wheel bearing unit for securing a driven wheel to a vehicle, the inner race ring having an axially extending through bore, at one end a radially outwardly extending flange and at the other end in the bore an output part of a joint for transmitting drive, the annular centri element having a first portion held fast in the bore of the inner race ring at the end having the flange and forming a seal with the bore of the inner race ring, a second portion lying outside of the bore of the inner race ring and projecting axially beyond the flange, which second portion provides a centring surface or surfaces for the inner periphery of a wheel or the inner peripheries of a wheel and a brake disc, and a wall closing the bore of the annular centring element, the radially outer surfaces of the first and second portions being co-axial.

2. A wheel bearing unit for securing a driven wheel to a vehicle and comprising a radially inner race ring having an axially extending through bore, at one end a radially outwardly extending flange for attachment to the wheel and at the other end in the bore a joint for transmitting drive, which joint can accept a certain amount of misalignment between its input and output members, a radially outer race ring for attachment to the body of the vehicle, rolling elements disposed between and for rolling on the raceways of the race rings, and an annular centring element which is disposed in the bore of the inner race ring at the end having the flange, is held fast in the bore and forms a seal with the bore of the inner race ring, which annular centring element extends axially out of the bore past the flange of the inner race ring and provides a centring surface or surfaces for the inner periphery of a wheel or the inner peripheries of a wheel and a brake disc, the centring surface or surfaces being co-axial with the bore of the inner race ring and the annular centring element having a wall closing its bore.

3. Apparatus as claimed in claim 1 or 2, wherein the centring surface or surfaces is or are cylindrical and the portion of the annular centring element lying in the bore of the inner race ring is cylindrical.

4. Apparatus as claimed in claims 1,2 or 3, wherein the wail of the annular centring element is positioned at one end of the element.

5. Apparatus as claimed in any preceding claim, wherein the annular centring element is held fast by an interference fit in the bore of the inner race ring.

6. Apparatus as claimed in one of claims 1 to 4, wherein the annular centring element is held fast by being welded in the bore of the inner race ring.

7. A combination of an inner race ring and an annular centring element substantially as herein described with reference to and as shown in Figure 1, or with reference to and as shown in Figure 2, or with reference to and as shown in Figure 3, or with reference to and as shown in Figure 4, or with reference to and as shown in Figure 5, or with reference to and as shown in Figure 6 of the accompanying drawings.

8. A wheel bearing unit substantially as herein described with reference to and as shown in Figure 1, or with reference to and as shown in Figure 2, or with reference to and as shown in Figure 3, or with reference to and as shown in Figure 4, or with reference to and as shown in Figure 5, or with reference to and as shown in Figure 6 of the accompanying drawings.