AU2004204143B2 - Power divider assembly - Google Patents

Description

WO 2004/063599 PCT/AU2004/000044 POWER DIVIDER ASSEMBLY Field of the Invention The present invention relates to a power divider assembly particularly, but not exclusively, for driving axles of a vehicle. 5 Background of the Invention It is known to provide an open differential between a mid and rear axle of a multi-axle vehicle so that a drive system can deliver the same drive torque to each of the axles, whilst allowing the axles to rotate independently. An open differential is ideal for driving on roads but when driving conditions become more difficult, such as in an off-road 10 environment, the open differential needs to be locked so that the axles are effectively coupled together. The differential, in a locked condition, causes torque from the drive system to be transmitted equally to the inputs of the mid (first) and rear (second) axles. As such, the locked differential acts as a power divider, insofar as power, or torque, is divided equally 15 between the axles, independent of associated wheel traction, whereas the open differential directs torque to the axle with least resistive load. Placing the differential in a locked condition involves actuation of a locking mechanism such as by manually engaging a lever. A disadvantage of such a mechanism is that the vehicle needs to be stopped, before the locking mechanism is engaged. A further 20 disadvantage is that the locking mechanism may be inadvertently left in the engaged condition after the vehicle transits from an off-road to a sealed road environment. Object of the Invention The present invention seeks to address the above disadvantages. Summary of the Invention 25 In accordance with the invention, there is provided a power divider assembly including: WO 2004/063599 PCT/AU2004/000044 -2 a drive input; a first and second output arranged to be coupled to associated first and second axles of a vehicle, which are spaced apart in a lengthwise direction of the vehicle; and a differential including first and second couplers for transmitting torque to the first 5 and second outputs, respectively, the couplers being driven in unison and each coupler being adapted to be individually moved out of driving engagement when the couplers rotate at different speeds. Preferably, the differential includes a housing, within which the couplers are arranged, and the drive input forms a component of the housing. 10 Preferably, the couplers rotatably drive concentrically arranged elements which are in turn coupled to and drive a respective one of the outputs. Preferably, the assembly includes a clutch device to dampen backlash between the elements when the associated couplers move back into driving engagement. More preferably, the device includes a pre-loaded tapered cone on one of the elements, arranged 15 in biased relation to a complementary surface on the other element. Preferably, the outputs extend from a side of the differential, opposite the drive input. Preferably, the drive input includes a drive wheel, extending radially inwardly of the housing, the drive wheel being provided between the couplers and having teeth arranged to interfit with corresponding teeth of each coupler, for driving the respective outputs. 20 Brief Description of the Drawings The invention is described in more detail, with reference to the accompanying drawings, in which: Figure 1 is a plan view of a power divider assembly; Figure 2 is a diagramnatic side view of a vehicle; WO 2004/063599 PCT/AU2004/000044 -3 Figure 3 is a diagrammatic plan view of part of a vehicle chassis; and Figure 4 is a cross-section view of the power divider assembly. Detailed Description Referring firstly to Figure 1, a power divider assembly 1 is shown as including an 5 assembly casing 2 formed of a main housing 3, a bearing housing 4 and a chain housing 5. The assembly also includes a drive input 6 and first and second outputs 7, 8. In Figures 2 and 3, the assembly 1 is shown mounted to a chassis 9 of a vehicle 10. The drive input 6 is coupled to an engine tail shaft 13 and the first and second outputs 7, 8 are connected to respective first and second axles 11, 12, which are spaced apart in a 10 lengthwise direction of the vehicle 10. Power is transferred from the input 6, through the assembly 1, to first and second axles 11, 12 by intermediate linkages 14, 15 and respective differentials 16, 17, in order to drive associated wheels 18, 19 mounted to the axles 11, 12. The power or torque delivered to the axles 11, 12 is divided by the assembly 1, in order to 15 ensure equal torque is applied to wheels 18, 19. For that purpose, the assembly 1 is provided with a positive-acting differential 20 (see Figure 4), which locks the outputs 7, 8 together in normal operation and selectively releases one of the outputs from driving engagement in a situation where one output is rotating at a different rate relative to the other. 20 The differential 20 is formed of two housing components 21, 22 which define a cavity 23 for receipt of the couplers 24, 25. The first component 21 is formed of the drive input 6 itself and carries a drive wheel 26 which extends radially inwardly, between each of the couplers 24, 25, while the second component 22 is rotatably mounted on bearings 27 in the housing 3. Springs 30 are provided in the cavity 23 to bias the couplers 24, 25 toward the 25 drive wheel 26, to cause corresponding teeth (not shown) on each of the couplers 24, 25 and the drive wheel 26 to intermesh for driving engagement. The couplers 24, 25 are mounted, with limited axial movement, to respective co-axial WO 2004/063599 PCT/AU2004/000044 -4 elements 28, 29 which connect the couplers 24 , 25 to associated outputs 7, 8. More specifically, the first element 28 connects through a connecting gear 46 to the first coupler 24 of the differential 20 and the first output 7. The second element 29 extends from the second coupler 25, partway along the length of the first element 22, and has a cog wheel 30 5 which drives an endless chain 31 through the chain housing 5, in order to rotate an associated cog wheel 32 in the housing 4. The wheel 32 is integrally formed with a rotatable shaft 33 which is mounted on bearings 34 and which is directly coupled to the second output 8. The shaft 33 can, of course, instead be used to direct torque forward to an alternative second output or, indeed, be used for torque transmission both forwardly and 10 rearwardly. As such, rotation of the couplers 24, 25 in unison results in the outputs 7, 8 also rotating in unison. If, however, one of the couplers 24, 25 is caused to rotate at a different rate relative to the other, it will be forced away from the drive wheel 26 by reactive forces between the teeth, against the relevant spring bias and that will in turn disengage the 15 associated element 28, 29 from driving engagement until the rotational speeds of the couplers are again matched. When the couplers 24,25 are again re-engaged, or in a situation between drive on and drive off, a degree of backlash may occur and a clutch device 40 is installed to dampen that affect. The device 40 is in the form of a tapered cone 41, provided on the element 28. The 20 cone 41 has a multistart thread 42 on its external surface 43, for lubrication, and is held in preloaded relation with a complementary surface 44 formed internally of the concentrically arranged element 29. The preloading is effected by bias force exerted by spring or belleville washers 45, which force the clutch device 40 into engagement with the element 29, to maintain a resistive force between the outputs, so as to provide the required 25 dampening affect. Accordingly, the assembly 1 allows for power to be divided equally between both outputs 7, 8, as required, whilst the application of power or torque to one of the axles 11, 12 may be automatically interrupted if that axle starts spinning at a different rate relative to the other axle. The torque can then be relatively smoothly reapplied when the couplers 24,25 -5 re-engage, by virtue of clutch device 40. Another advantage of the assembly 1 is that the drive input 6 actually forms part of the differential housing and that reduces component parts and simplifies the overall construction of the differential 20. A further advantage associated with the construction of 5 the assembly 1 is that both the first and second co-axial elements 28, 29 extend away from the input 6, and that positions both outputs 7, 8 on a side of the differential 20 opposite the drive input 7. Such an arrangement allows the differential 20 to be readily installed and accessed for maintenance. The invention has been described by way of example only and many modifications and 10 variations may be made thereto without departing from the spirit and scope of the invention described. The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates. Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

Claims (8)

1. A power divider assembly including: a drive input; a first and second output arranged to be coupled to associated first and second axles of 5 a vehicle, which are spaced apart in a lengthwise direction of the vehicle; and a differential including first and second couplers for transmitting torque to the first and second outputs, respectively, the couplers being driven in unison and each coupler being adapted to be individually moved out of driving engagement when the couplers rotate at different speeds. 10

2. A power divider assembly as claimed in claim 1, wherein the differential includes a housing, within which the couplers are arranged, and the drive input forms a component of the housing.

3. A power divider assembly as claimed in claim 1 or 2, wherein the couplers rotatably drive concentrically arranged elements which are in turn coupled to and drive a 15 respective one of the outputs.

4. A power divider assembly as claimed in any one of claims 1 to 3, wherein the assembly includes a clutch device to dampen backlash between the elements when the associated couplers move back into driving engagement.

5. A power divider assembly as claimed in claim 4, wherein the device includes a pre 20 loaded tapered cone on one of the elements, arranged in biased relation to a complementary surface on the other element.

6. A power divider assembly as claimed in any one of claims 1 to 5, wherein the outputs extend from a side of the differential, opposite the drive input.

7. A power divider assembly as claimed in claim 2, wherein the drive input includes a 25 drive wheel, extending radially inwardly of the housing, the drive wheel being provided between the couplers and having teeth arranged to interfit with corresponding teeth of each coupler, for driving the respective outputs. C:WRPortbl\DCC\EJL\2S9192I 1DC-21/04/2010 -7

8. A power divider assembly substantially as hereinbefore described with reference to the drawings and/or Examples.