CA1119650A

CA1119650A - Center bearing bracket

Info

Publication number: CA1119650A
Application number: CA000347008A
Authority: CA
Inventors: James T. Reynolds
Original assignee: Dana Inc
Current assignee: Dana Inc
Priority date: 1979-03-05
Filing date: 1980-03-05
Publication date: 1982-03-09
Also published as: PH20270A; IN152941B; ES8103294A1; JPS56500390A; ES489165A0; DE3036771T1; MX148816A; AR220966A1; FR2450974A1; JPH0159928B2; FR2450974B1; GB2057069B; AU532192B2; GB2057069A; WO1980001939A1; DE3036771C2; BR8007525A; AU5581680A

Abstract

ABSTRACT
An improved bearing assembly is disclosed for supporting a split drive shaft of vehicle An inner, rotatable race of a bearing engages the drive shaft and an outer, non-rotatable race of the bearing is mounted in a resilient rubber block. The rubber block, which is connected through a bracket to the vehicle frame, permits limited radial and axial movement of the bearing. The bracket has a flange spaced from the rubber block to the rear of the bearing which limits axial movement of the bearing to prevent the drive shaft from pulling the bearing from the rubber block.

Description

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This inventi~n relates to bearings i~nd more particularly to an improved resillently mounted center bearing for supporting a split drive shaft of a-vehicle.
In vehicles such as automobiles and trucks, a front mounted engine is generally coupled through a drive shaft, a differential gear i~nd rear axles to drive the rear ~heels of the vehicle. Depending upon seYera,l factors including the aistance between the transmiss~on i~nd the differential gear and the iangular mlsalignment between the output of the transmission and the input to ehe differential gear, ~he .. . , . ....... - ...................... -._ I
drive shaft may be a sihgle piece or it may be in the form of a split sbaft having two or more shaft sectionsi with adjacent sections coupled together through a universal joint. For exi~mple, the outp~t from the vehicle Lransmission may be coupled through a universal ~oint to a coupling shaft ~hich is in turn coupled through a second universal joint to a drive shaft wh~ch is coupled throùgh a third universal joint to the tlfferential jgear. One or more slip joints iare provided in the drive shaft with, typically, one slip joint between the coupling shaft and the transmission and a second slip joint between the coupling shaft and drive shaft. The slip joints perm$t variat$ons in the sparing between the ~ransmlssion and the differPntial gear due to manufacturing tolerances and also permit limited changes in the spacing when the diffPrential gear moves with the rear suspension system for the vehicle. In order to provide stability for the system, it is necessary to support the coupling shaft adjiacent the second universal ~oint. The rotating shaft is engaged with a bearing which ls embedded in a resilient rubber bushing which in turn ls attached through a bracket to the vehicle chassis, frame ; or body.
.In a vehicle drive as the type described above; one problem occurs when the slip ~olnt ad~acene to th~

IL~ 6S61 second universal joint is prevented from slipping. This could be caused by a lack oE lubican~ or by contaminants in the slip joint. This in turn forces axial movement to take place at the slip joint between the coupling shaft and the transmission. When this occurs, the axial movement of the coupling shaft sometimes pulls either the bearing from its resilient rubber bushing or pulls the rubber bushing from the bracket or housing which connects the bushing to the vehicle frame. Due to ve~icle geometry, the axial movement of the coupling shaft is generally to the rear of the vehicle.
Various attempts have been made in the past to eliminate this condition. United States Patent 3,306,679, for example shows a resilient mounting for a center bearing on a vehicle drive shaft which is designed to withstand considerable axial movement beore failure. In another variation of the resilient mounting for a center bearing shown in United States Patent 3,309,154, the resilient mounting is permitted to roll axially a considerable distanct to either side of i~s supporting frame prior to failure. Although the prior art has attempted to solve this potential center bearing problem for a vehicle coupling shaft, there is still an incidence of this occuring.
According to one aspect of the present invention, an improved center bearing assembly is provided for supporting a split drive shaft which connects a vehicle transmission to a differential gear. The center bearing assembly also may be used in coupling shafts for other applications and is particularly suitable for applicationswherein the coupling shaft may be subject to limited axial forces which tend to pull a supporting bearing from its mounting.
According to one aspect of the present invention, an inner, rotatable race o~ a bearing engages the coupling shaft and an outerr non-ro~atable race of the bearing is mounted in a resilient rubber block or bushing. The

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rubber block, which is connected through a bracket to the vehicle frame, chassis or other rigid member, permits limited radial and axial movement of the bearing. The bracket has a flange which is normally spaced from the rubber block to the rear of the bearing. When the coupling shaft attempts to move in a rearward direction by a distance greater than the spacing, axial movement of the coupling shaft is restrained by the rubber block engaging the flange. This prevents axial movement of the coupling shaft from pulling the bearing from the rubber block or from pulling the rubber block from the mounting bracket.
Since the rubber block does not normally engage the flange, noise and vibrations from the vehicle drive train normally are not transmitted through the rubber block and the flange on the mounting bracket to the vehicle.
Thus, the invention consists of a center bearing assembly for resiliently supporting from a rigid support a driven shaft which may be subjected to radial forces and to axial forces in at least one predetermined direction comprising a bearing having a rotatable inner race engaging said shaft, a non-rotatable outer race and a plurality of bearing elements between said inner and outer races, a resilient bushing mounting said outer race, said bushing having first and second sides and an outer edge, a bracket engaging at least a portion of said outer edge and having integral lips engaging said sides adjacent said outer edge, said integral lips retaining said bushing in said bracket, means for mounting said bracket on said rigid support, said bracket further having a flange on the side of said bushing of said predetermined direction, said flange~having a predetermined small spacing ~rom said bushing, said spacing limiting axial movement of said bearing in said predetermined direction.
The objects and advantages of the invention will become apparent from the following detailed description, with reference being made to the accompanying drawings.

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Fig. 1 is a perspective illustration of a vehicle showing the location and use of the center bearing assembly of the present invention for supporting a split drive shaft;
Fig. 2 is a side elevational view of a split drive shaft in a vehicle supported by the center bearing assembly of the present invention;
Fig. 3 is an enlarged fragmentary cross sectional side elevational view of the center bearing assembly of the present ` invention;

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Fig. 4 is a perspective view showing the center bearing assembly of ~he present invention with the rubber block separated fr~m i~
\ moun~ing bracket; and i Fig. 5 is a perspective view of a modified embodiment of the mounting bracket for the rubber block of the center bearlng assembly of ~he present invention.
Turning now to the drawings and particularly to Figs. 1 and 2, a vehicle 10 is illustrated in Fig. 1 which includes a coupling - -- shaft 20 and 8 drive shaft 11 connected between a transmlssion 12 and 1~ a differeneial gear 13 ~for `driving a pair of rear wheels 14. The , transmission 12 is provided with a~ output shafe (not shown) of conventional design and having a plurality ~f splines formed around its periphery and extending in a direction parallel with its ¦
axis. A slip yoke 15 has an internally splined tubular end portion 16 which slidably engages the transmission output sba~t and is rotated by such output shaft. ~The slip yoke 15 also has a yoke end 17 which forms one slde of a universal joint 18. The other side of the universal ~oint 18 is fon~ed by a yoke 19. The coupiing shaft 20 has an opposite end terminating in a splined ~haft portion 21. A center bearing assembly 22 in accordance with the present invention supports the coupling shaft 20 adjacent the splined shaft portion 21. The center bearing sssembly 22 includes a rigid frame or bracket 23 which is rigidly attached with bolts to a vehicle frame, chassis or body 25.

, The splined shaft portion 21 at the end of the coupling shaft 20 is recei~ed by an internally splined end portion 26 of a slip yoke 27 on the drive shaft 11. The splined shaft portion 21 and the splined end portion 26 move in an axial tirection with respect to one another while rota~ing together. The slip yoke 27 has a yo~e end 28 which forms a por~ion of a universal ~oint 290 A yoke 30 on drive shaft 11 ~orms a second portion of the uniYersal ~oint 29. The drive shaft 11 has a second end terminating at a yoke 32 which forms a portion of a .: ~ - - - .

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universal ~int 33. A yoke 34 on e shaft 35 for~s a second portion of the universal joint 33. The shaft 35 is connected to the \ differential gear 13 which is driveably connected through rear axl~ 36 . .
t to the rear wheels l~ of the vehicle lO.
During nor~al operation of the vehicle lO, the coupling shaft 20 rotates and ~s not subjected to s~bstantlal axial forces. As the differential gear 13 moves with the suspension system for the rear wheels 14~ forward and rearward movement of the eoupling-shaft 20 takes place at the spliDed joint between the splined shaft portion 2i of the coupling shaft 20 and the - - -- ~
internally splined portion 26 of the slip yoke 27 on the drive shaft ll.
~owever, due to lack of lubricant or excessive contamination, thl~
~oint may eventually bind up or freeze and no longer ~unction ~n lts in~ended manner. When this happens, ;here is a tendency for the coupling shafe 20 to move in an axial direction and ~ for siip to teke place at the splined ~oint between the slip yoke 15 and the output from the transmission 12. The center bearing assembly 22 of the present invention is designed to wnthstand the stronger axial forcès on the coupling shaft 20 and, thereby, to cause slip to occur at the joint bet~een the splined shaft portion 2l o~ the coupling shaft 2D and the internally splined end portlon 26 of the slip yoke 27.
Turning now to Figs. 3 and 4, deta11s are shown for the ce~ter bearing assembly 22 of the present invention. The center bearing asse~bly 22 includes a conventional bearing 40 having a plurality of balls 41 disposed between an inner, rotatable race 42 and an outer, non-rotatable race 43. The bearing 40 ~ay be of any conYentional design and iDcludes seals 44 for holdlng a lubricant within a chamber 45 surrounding the balls 41. The inner bearing race 42 defines an interior opening 46 whlch engages a portion 47 of the coupling shaft 20 ad~acent the splined shaft portion 21. Annular dir~ ~hields 48 are pos~tioned on either side of the outer bParing race 43. The dirt shlelds 48 are slightly sp~ced from the se~ls 44 and :
extend concentric with and nearly to the coupling 6haft 20 for p~otecting the \ bearing 40 fr~m dirt and other road conta~inants.
The dirt shields 48 and the outer race 43 are e~bedded within B
resilient rubber member or bushing 49 which in turn either is mount~d within the bracket 23 or is molded directly in the bracket 23 . .
so as to bond the rubber member 49 to the bracket 23. A forward edge of the rubber member 4g defines a lip 50 which extends into an I _ anDular region defined by a shield 51 mounted on the coupling shaft 20 .. - : ........... .. I
~or further reducing th~e possibility of road contam~nants reaching the bearing 40. ~ lip 52 formed at a rear face of the rubber member 49 is ~olded inwardly over the rear one oE the dirt shields 48. An additional shield in the form of a slinger 56 is mounted on ~he shaft portion 47 to the rear of the bearing 40. The slinger 56 has a flange 57 which pro~ects radially from the coupling shaft 20 to the `~~ rear of the bracket 23. The slinger 56 prevents water, mud~ dirt and the like from flowing along the end of he coupling shaft 20 into the center bearing assembly 22.
The rubber member or bushing 49 is shown as having two circular rows of arcuate slots spaced coaxially about the bearing 40 and arr~nged in an inner row 53 and an outer row 54. Preferably, the rows of slots 53 and 54 are stagg~red3 except at a bottom region 55 of the rubber member 4g, wherein no slots are present. The slots 53 and 54 permit a limlted degree of radial move~ent o the bearing 40 within the rubber member 49 agalnst a low resllient force. When the eoupling shaft 20 applies a force to the bearing member 40 to move the bearinB member 40 radially a distance gre~ter th~n the thickness of the slots 53 or-54, the rubber member 49 is compressed ~nd exerts a greater resilient Eorce opposing such movement of the bearing 40. The s~ots 53 and 54 are omltted from the bottom region 55 of the rubber member 49 slnce the weight of the coupling shaft 20 and the drive shaft 11 are normally supported by this portion~of the rubber member 49.

6~ 1 The rubber ~mber or bushing 49 is supported wlthin the bracket 23 which is in turn m~lded or otherwise attached to the `~ vehicle frame, chassis or body 25. The bracket 23 is stamped from a t single sheet of steel and includes a ~-shaped outer region 60 which conforms ~th an outer surface 61 of the rubber ~ember 49. Each end of the U-shaped region 60 is terminated by an outwardly directed flange 52 which is proYided with an opening 63 which rec:eives the bolt 24 for attaching the bracket 23 to the vehicle fra~e, chassis or body 25. An inwardly directed lip 6~ is provided at the front of the bracket 23 to extend arouDd tbe . ~
U-shaped outer region 60 aDd a similar inwardly directed lip 65 is provided at the rear of the bracke; 23 to extend around the surface 60. The lips 64 and 65 engage forward and rear sldes 66 and 67, resp~ctively, of the rubber member 49 adjacent the outer surface 61 for retaining the rubber member 49 within the bracket 23.
In accordance with the present invention, a rear flange 70 is formed to extend radially inwardly from the rear lip 65 on the bracket 23. The rear flange 70 is located so as to malntain a predetermined small spacing from the rear lip 52 of the rubber member 49. The spacing is sufficiently large that under nor~al operation of the vehicle 10, the rear lip 52 on the rubber bushi~g or member 49 does not contac~ and transmit drive train vibrations to ~he rear flan~e 70 on the bracket 23. The spaclng between the lip 52 and ehe flange 70 may, for exa~ple, be on the order of from 0.06 inch to 0.2 inch or more, depending ~pon the permissible axial ~ovement of the coupling shaft 20. In any event, ehis spacin~ is maintained suffici2ntly small as to prevent rearward axial movement of the coupling shaft 20 from pulling the bearing 40 from the rubber member 49 or from pulling the rubber member 49 from lts bracket 23. In the event that the slip ~oint formed between the slip yoke 27 and ~he splined sha~t portion 21 of the coupling shaft 20 becomes cont~minated and tends to bind, the .
coupling shaft 20 will tend to move in a rearwardly direction as the rear wheels 14, the d~fferential gear 13 and the rear suspens~on for the vehicle 10 move due to rs2d irregularities. In this event, the 9~5~ ~

lip 52 on the rubber member 49 will contact the flange 70 and limit axial movement of the roupl~ng shaft 20. This in turn will tend \ to force axlal slip to occur at the ~oint betweeD the slip yoke 27 and the splined shaft portion 21, thereby freeing up this ~oint and preventing this joint from freezing up entirely. This momentary contact of the rubber lip 52 with the flange 70 on the bracket or frame 23 shoult not be felt by occupants in the vehicle because the suspension system for the vehic1e 10 is also moving at this time. This differs from pri~or-art center beàring asse~blies in which 8 ma~or portion of the ru~ber member is in permanent contact wlth a mounting bracket in order to retain the bearing. Center bearing assembli~s of this type trsnsmit significant ~ibrations from the vehicle drive tra~n to the vehicle fr~me.
, Turning now to Fig. 5, a modified bracket 71 is shown for attaching the previously described rubber member or bushing 49 and the . _ bearing 40 mounted therein to a Yehicle frame, chassis or body, such as is illustrated by the referenc2 number 25 in Fig. 2. The bracket 71 is stamped from a single sheet of metal to define sn outer U-shaped region 72 which is shaped to engage the outer surface 61 of the rubber member 49. The ends of the U-shaped region 7~ terminate at outwa}dly flared flanges 73. Boles or openings 74 are provided in the flanges 73 for at~aching the ; bracket 71 to the vehicle with bolts, rivets, or other suitable means. A
forward lip 75 is folded inwardly from the front of the U-shaped reglon 72 and a rear l~p 76 is folded inwardly from the rear of the U-shaped region 72 to define a channel for receiving the rubber member 49. The forward lip 75 engages the forward side 66 and the rear lip 76 engages the rear side 67 of the rubber me~ber 49 for retaining such member ln the bracket 71. A flat flange surface 77 defining ~n opening 78 is connected to and spaced to the rear of the rear lip 76. The opeDing 78 is located concentric with the opening 46 ~ n the bearing race 42 so as to pass the splined shaf t portion 21 -- -- -- ~
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or couplinz shaft ~0. When the rubber m~mber or bushing 49 is mounted within the ~racket 71, the rear lip 52 on the rubber member 49 i6 spaced a slight distance from the flat flange 77. Durln~ normal operation of the vehicle in which the center bearing assembly is mounted, the rubber lip 52 does no~ contact the flange 77. In the event that the slip ~oint formed betveen the slip yoke 27 and the splined shaft portion 21 of the coupling shaft 20 becoDes contaminated and tends to bind, the coupling shaft 20 will tend to move in a rearwardly direction as the rear wheels 14, the differential gear 13 and the rear suspension for the .... ..
~ehicle 10 ~ove due to ~o~d irrè~ularities. ID th~s event, the l~p 52 on the . _ .
rubber member 49 will contact the flange 7~ and limit axial ~ovement of thP
coupling shaft 20. This in turn will tend to force axial slip to occur at the ~oint between the slip yoke 27 and the splined shaft portion 21, thereby freeing up this joint and preventin~ this joint from freezing up entirely.
Vehiele geometry normally causes the bearing in prior art center bearing assemblies to ~eparate from its resilient mounting in a direction to the rear of the Yehicle in which it is mounted. However, lf the veh~cle geometry is changed such that the bearing and resilient bushing or the resilient bushing and tbe rigid mounting bracket tend to separate in a forward direction, the bearing assembly of the preseDt invention can be oriented in a reverse direction to prevent such separation. If the center bearing asse~bly is subjected to axial forces in both dir,ectlons, then the mounting bracket can be provided with flanges spaced both to the front and to the rear of the rubber bushing to limit axial movement of the drive shaft in both directions. Various other changes and modifications may be made in the sbove-described preferred embodiment of the lnvention without departing from the spirit and scope of the follo~ing claim~.

For example~ other known conf~gurations for rubber bushing or member b9 may be used in the center bearing assembly of the present invention. The rubber bushing 49 may be bonded to the _ 9 -: . . :

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bracket 23 by ldlng the bushing 49 into the bracket 23 ~
-~ or the bushing 49 may be a separate ele~ent which ~lide~ into the bracket 49.

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Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A center bearing assembly for resiliently supporting from a rigid support a driven shaft which may be subjected to radial forces and to axial forces in at least one predetermined direction comprising a bearing having a rotatable inner race engaging said shaft, a non-rotatable outer race and a plurality of bearing elements between said inner and outer races, a resilient bushing mounting said outer race, said bushing having first and second sides and an outer edge, a bracket en aging at least a portion of said outer edge and having integral lips engaging said sides adjacent said outer edge, said integral lips retaining said bushing in said bracket, means for mounting said bracket on said rigid support, said bracket further having a flange on the side of said bushing of said predetermined direction, said flange having a predetermined small spacing from said bushing, said spacing limiting axial movement of said bearing in said predetermined direction.

2. The center bearing assembly of claim 1, and further including two dirt shields mounted between said outer bearing race and said bushing, each dirt shield having a generally radially inwardly directed flange shielding a different side of said bearing with one of said shields extending between slid bearing and said flange on said bracket, and wherein said bushing has a lip extending over said one shield and forming one side of said predetermined small spacing between said bushing and said flange on said bracket.

3. The center bearing assembly of claim 2, wherein said flange on said bracket is spaced from and completely surrounds said outer bearing race in said predetermined direction.

4. The center bearing assembly of claim 1, wherein said resilient bushing outer edge is bonded to said bracket.