GB2181516A

GB2181516A - Vehicle drive assembly and joint therefor

Info

Publication number: GB2181516A
Application number: GB08623827A
Authority: GB
Inventors: Manfred Goeft; Eckhard Schmied
Original assignee: ZF Friedrichshafen AG
Current assignee: ZF Friedrichshafen AG
Priority date: 1985-10-04
Filing date: 1986-10-03
Publication date: 1987-04-23
Also published as: DE3629297A1; GB8623827D0; DE3629297C2; GB2181516B

Abstract

A single-wheel drive having a driving shaft (3), which is connected by universal joints (5A, D), between a power take-off gear (2) and a wheel gear (4), one of said single joints (5A or 5D) in each case being incorporated close to the centre of the gear. A short intermediate shaft (3A or 3B) in each case extends from these single joints (5A or 5D) to the single joints (5B or 5C) disposed adjacent thereto, said short shafts being permanently and obliquely guided in the axle box or end cap at its permissible angle of deflection ( alpha ). Thus the total angle of deflection ( alpha + beta ) can be doubled with respect to an arrangement with individual joints on each side by means of the further joint (5B or 5C) connected just in front. <IMAGE>

Description

SPECIFICATION Vehicle drive assembly and joint therefor This invention relates two a single-wheel drive assemblyanda jointforusetherewith.

Single-wheel drives are known in which, in spite of a very small spacing owing to the universai joints being incorporated in the respective driving and driven gear units, the driving shafts between the power take-off gear and the wheel gear have both sufficient resilience and a relatively long operative length,sothat only relativelysmall joint angles are required. This provides advantages both as regards the resilience and, in particular, the protection ofthe joints against damage and wear, as the restricted op eratingangleofthejointscan be utilized to a greater advantage.

However unsatisfactory conditions always result from operating angles achieved inthiswayif,for structural reasons, greater degrees of movement of the driving shafts are required than the applicable joints can support, or ifthe spacing between the gears must remain small. This may also be the case, for example, if a fairly largefixed angle also has to be supported by the joint when the vehicle is ata standstill in the case of large wheels with lowcardan shafts, small wheels with high cardan shafts or a considerable lateral misalignment between the power take-off and wheel gears. When having to absorb constantly alternating shocks during travel, the necessity of an even greaterjoint angle becomes crucial.

It is an object of the invention to provide a drive arrangement and joint therefor which allows the lar gestpossiblejointoperating angle, if the fixed angle between the central points of the driving and driven gearunits,which are in engagement via the driving shaft, is relatively large, e.g. as a result of a considerable centre misalignment.

According to one aspect of the invention, there is provided ajointfor use in a vehicletransmission system to connect a drive shaft between a power input and a non axially aligned driven memberwhich is required to move laterally with respect to the power input drive axis, said joint comprising first and second joint parts arranged close to each other, the firstjoint part being connected to the second joint part and being mounted at a fixed angle relativeto the power input drive axis, the second joint part being constructed to allow the drive shaft, when connected thereto, to rotate and swivel with respect to the axis of rotation of the first joint part.

According to another aspect of the invention there is provided a drive arrangementforvehicles comprising a power input connected by a drive shaft to a power output, said drive shaft being connected to the power input and outputs by means of a joint at each end thereof, each joint comprising two single joints arranged close to each other to permitthe shaft to be deflected with uninterrupted torque transmission through at least twice the angle with respect to the drive axis than would be possible with a singlejoint.

In a preferred embodiment, there is provided an arrangement in which joints are disposed on the external shaftends having afixed angle,whiletheinternally disposed joints are in each case allowed to move through afree operating angle. Forthis purpose, the joint which is in each case disposed on the external shaft end has an obliquely mounted intermediate shaft, one end of which is connected to a powertake-offorwheel head gear and the other end of which is guided so asto swivel. The angles on the respective sides can therefore be added together if required.

According to another aspect of the preferred embodiment, out of the joints of the respective external shaft ends which are arranged as close as possible to the centre of the respective gear unit, intermediate shafts, which are quite short, but arranged in a projecting and oblique manner in these external joints and at the largest permissible fixed angle, are guided in the direction ofthe actual driving shaft. The fixed angle is obtained in that this intermediate shaft is already guided obliquely in an intermediate shaft bearing in a casing orcapforthe respectivegearat an angle as large as can be tolerated bythejoint arranged atthe external shaft end during continuous operation without overloading.

The opposite end, on the driving shaft side, of the intermediate shaft which is guided in a corresponding oblique mannerthen leads into an internal single joint integrated in the relevant casing or cap, in the ball guide section of which joint the actual driving shaft is guided so as to swivel in a restricted manner and rotatefreelyand, if required, to move in the longitudinal direction.

The cumulative use oftwo short universal joints of this kind at each end of the driving shaft provides the possibility of allowing a centre misalignment of the two gear units which is practically twice as great as was possible with known arrangements, without this having any significant detrimental effect on the transmissible torques or useful life. The centre mis alignment can be a result of both vertical and lateral differences.

From the manufacturing viewpoint, a particular advantage is found in the fact that the gearbox for steep angle joint arrangements of this kind does not have to have a special design. When the joint conditions are such that there is a slight centre misalignment, the mounted box, or the special box case cap can also easily be fitted at a later date, as long as appropriate attachment points are provided.

A preferred drive arrangement and joints of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which Figure lisa schematic diagram illustrating the invention, Figure 2 shows the joint arrangement in the case of a powertake-offand Figure 3 shows the joint arrangement in the case of a wheel gear.

In Figure 1 there is shown a driving shaft3fora wheel gear4,which is arranged ata spacing Afrom a gear 2 by which it is driven. The powertake-off gear 2 is arranged at a clearance B above road 1.

The drive axis 7 ofthe power take-off gear 2 is misaligned by a distance H with respectto the axis of rotation of the wheel gear 4which, with a given centre-to-centre spacing A, is determined by the size of the respective angles of deflection a, p of joints 5A, B, C, D at the drive or driven gears 6 ofthe respective gear units 2 or4.A particularly large angle of deflec tion a + ss which also permits a large centre misalign- mentdistance AH, is obtained according to the invention inthatthetwo singlejoints 5A and 5B and 5C and 5D are in each case provided as close together as possible and as close as possible to the centre of the respective gear units 2 and 4, said joints being connected together by short intermediate shafts 3A and 3B, respectively. The intermediate shafts 3A and 3B are mounted in respective bearings 9 obliquely mounted with respect to the horizontal axis 7 in cas- ing 8A or cap8B at an angle of deflection which will give the joint the required degree of movement.

Figure 2 shows the joints 5A, 5B, which are arranged on the driving shaft 3 adjacent the powertake-off gear 2 on a short intermediate shaft 3A. Holder 12 of the joint 5A and, via this holder 12, external toothed inner ball race 13A, which is non-rotationally connected to the intermediate shaft3A, in the joint 5A, is driven by the hub 1 OA, which contains the internal toothed outer ball race of the joint 5A, of the driven toothed gear 6, which in this example is a so-called bevel side gear of a differential, and the torque is thereby transmitted.

At its power take-off end, the intermediate shaft 3 is mounted in an intermediate bearing 9 housed in a casing or cap 8A wh ich is directly attached to the gearbox 2, e.g. by a flange. This bearing 9 is obliquely arranged at a fixed angle of deflection a with respect to the axis of rotation of the bevel gear 6 and broadens out at its opposite end to form a hub 1 0B having an internal toothed outer ball race in which the balls 11 of a furtherjoint 5B engage,which balls also rotate in the direction of rotation via the external-toothed inner ball race 13B which is keyed in the driving shaft 3.

As the joint construction is formed with elongated grooves in the ball races, restricted axial movements of the driving shaft 3 can be accommodated, if required.

In Figure3,the driving shaft3 is connected atan angle of deflection a + ss (from the right in the drawing), relative to the horizontal axis 7 to the wheel gear 4 by means of joint 5C so as to be able to swivel freely and, if necessary, carry out a limited movement in the longitudinal direction.

The joint 5C comprises an external toothed inner ball race 13C, mounted on the driving shaft 3 which drives, via balls 11 mounted in holder 12 theshort intermediate shaft3B freely through the angle P in the direction of rotation and in a manner such that it can swivel via the balls 11 .The holder 12 guidesthe balls 11 and the internal-toothed outer ball race in the hub 1 OC. The intermediate shaft 3B is mounted in bearing 9 in the housing 8B, said bearing being obliquely disposed at a fixed angle of deflection a. with respect to the horizontal axis 7 of wheel drive 4 by means of the joint 5D. In the illustrated embodiment a sun gear shaft l4ofthewheel gear4 rotates about this axis 7.This shaft is supported by a sun gear shaft bearing 15 located in an axle box 16, which externally encompasses approximately halfthe joi nt 5D and supportsthe housing 8B, inwhichtheobliquelydis- posed intermediate shaft bearing 9 is secured. In order to move the joint centre points as close as pos sidle to the gear centre, one half of a housing bearing 17, of a corresponding size, is approximately radially supported via thejoint 5D onthe axle casing 16.

The single-wheel drive of the invention can be used to advantage both in the case of a vertical and a lateral centre misalignment and, in particular, permits greater spring deflections than was possible with the singlejoints of the prior art.

It will be appreciated from the foregoing description that the single-wheel drive has a driving shaft3, which is connected by universal joints 5A, D, between a power take-off gear 2 and a wheel gear 4, one ofthe single joints 5Aor5D in each case being incorporated close to the centre.

As a short intermediate shaft 3A or 3B in each case extends from these single joints 5A or 5D to the single joints 5B or 5C disposed next to the latter and these shafts are permanentiy and obliquely guided in the axle box 16 or end cap 8 atits permissible angle of deflection a, the totalangle of deflection α + ss can be practically doubled with respect to an arrangement with individual joints on each side by means of a furtherjoint 5B or 5C connected just in front.

It is thereby possible to arrange the gears so that there is an extremely large centre orvertical misalignment, and, by attaching the additional joints 5B and 5C and adapting the main driving shaft 3 accordingly, to join together gear arrangements of the known type, or subsequently fit them so asto be shorter than is possible with known arrangements.

Claims

1. Ajoint for use in a vehicle transmission system to connect a drive shaft between a power input and a non axially aligned driven memberwhich is required to move laterallywith respect to the power input drive axis, said joint comprising first and second joint parts arranged close to each other, the first joint part being connected to the second joint part and being mounted at a fixed angle relative to the power input drive axis, the second joint part being constructed to allowthe drive shaft, when connected thereto,to rotate and swivel with respect to the axis of rotation of the first joint part.

2. A drive arrangement for vehicles com prising a power input connected by a drive shaft to a power output, said drive shaft being connected to the power input and outputs by means of a joint at each end thereof, each joint comprising two single joints arranged close to each otherto permitthe shaft to be deflected with uninterrupted torque transmission through at least twice the angle with respect to the drive axis than would be possible with a single joint.

3. Asingle-wheel drive arrangement including driving shafts which permit a centre misalignment between driving and driven gears via joints which are arranged so as to rotate and swivel in a power take-off gear atone end and in a wheel gear arranged ataspacing attheotherend,each joint having inner ball races mounted on the end of the driving shaft which are inserted in a hub of a driving or driven toothed gear close to the centre thereof each joint consisting of two single joints arranged close to one another whereby it can be deflected together through at least twice the angle size (a + p) of a single jointwith respect to a horizontal axis with uninterrupted torque transmission.

4. A drive according to claim 3, wherein, for each joint inner ball race is non-rotationally connected to said driving or driven toothed gear and engages, by means ofthe opposite end of a short intermediate shaft so asto be stiffagainsttorsion, in a joint holder at the shaft end disposed closer to the centre of gravity of the driving shaft at a fixed angle (a) another inner ball race also being arranged on thefrontshaft end and being guided by an intermediate shaft bearing which encompasses it and has co-ordinating shaft seals, coaxiallyto the driving or driven toothed gear, the short intermediate shaft being mounted in a housing or case cap on the shaft side, of the respect ive driving or driven gears at the fixed angle (a) div- erging from the axis of rotation of the respective toothed gearwhile, in addition,the main driving shaft which is driven in the direction of rotation by the joints disposed closer to the centre of gravity of the driving shaft can be swivelled freely about a further operating angle (p) diverging from the axes of the intermediate shaft.

5. Ajointfora vehicletransmission system sub- stantially as herein described with reference to the accompanying drawings.

6. A drive arrangement substantial iy as herein described with reference to the accompanying drawings.