POWER ASSISTANCE DRIVE FOR A STEERING COLUMN, AND STEERING COLUMN FOR A MOTOR VEHICLE

Abstract

A power assistance drive for a steering column of a motor vehicle may include a belt drive arranged in a housing, with an input pulley that is coupled to the motor shaft of a motor so as to be rotationally drivable about an input axis and which is drivingly connected by means of a drive belt to an output pulley that is mounted in the housing so as to be rotatable about an output axis. To enable a repair-friendly design and easier replacement of the motor, the motor may be releasably attached to the housing and the motor shaft may be connected to the input pulley by means of a releasable coupling.

Claims

1-10. (canceled)

11. A power assistance drive for a steering column of a motor vehicle, the power assistance drive comprising a belt drive disposed in a housing, with an input pulley that is coupled to a motor shaft of a motor so as to be rotationally drivable about an input axis, wherein the input pulley is drivingly connected by a drive belt to an output pulley that is mounted in the housing so as to be rotatable about an output axis, wherein the motor is releasably attached to the housing and the motor shaft is connected to the input pulley by way of a releasable coupling.

12. The power assistance drive of claim 11 wherein the releasable coupling includes coupling elements that are connected to the motor shaft and the input pulley, wherein the coupling elements are engageable with one another in an axial direction with respect to the input axis.

13. The power assistance drive of claim 11 wherein the input pulley is disposed on a drive shaft that is rotatably mounted in the housing.

14. The power assistance drive of claim 11 wherein the input pulley is mounted movably in the housing transversely to the input axis.

15. The power assistance drive of claim 11 wherein the input pulley is mounted on a bearing carrier that is positionable relative to the housing.

16. The power assistance drive of claim 15 wherein the bearing carrier includes a bearing slide that is displaceably mounted in the housing.

17. The power assistance drive of claim 11 wherein the input pulley is mounted in the housing so as to be tiltable transversely to the input axis.

18. The power assistance drive of claim 11 comprising a positioning device that is connected to the housing for adjustably positioning and fixing the motor transversely to the output axis.

19. The power assistance drive of claim 11 wherein the input pulley is coaxially connected to a spindle nut in which a threaded spindle engages, with the threaded spindle being longitudinally displaceable in a direction of the output axis.

20. The power assistance drive of claim 19 wherein the threaded spindle is connected to a toothed rack in which a steering pinion engages, with the steering pinion being rotatably mounted in the housing and connected to a steering shaft.

Description

DESCRIPTION OF THE DRAWINGS

[0028] Advantageous embodiments of the invention are explained in more detail below with reference to the drawings. The drawings show:

[0029] FIG. 1 a schematic depiction of a motor vehicle steering system with a power assistance drive according to the invention,

[0030] FIG. 2 a power assistance drive according to the invention in a first embodiment, in a schematic exploded depiction,

[0031] FIG. 3 a power assistance drive according to the invention in a second embodiment, in a schematic exploded depiction,

[0032] FIG. 4 the power assistance drive from FIG. 3 in a further view,

[0033] FIG. 5 a partially sectional view of the power assistance drive from FIG. 2 along the input and output axes,

[0034] FIG. 5a a detail view of FIG. 5 in a further embodiment,

[0035] FIG. 5b a detail view, as in FIG. 5a, of a further embodiment,

[0036] FIG. 6 a partially sectional view of the power assistance drive from FIG. 3 along the input and output axes,

[0037] FIG. 7 a power assistance drive according to the invention in a third embodiment, in a schematic exploded depiction,

[0038] FIG. 8 the power assistance drive from FIG. 7 in a further view, in the partially mounted state,

[0039] FIG. 9 the power assistance drive from FIG. 8 in a further view, in the mounted state,

[0040] FIG. 10 the power assistance drive from FIG. 9 in a further view, in the mounted state,

[0041] FIG. 11 a power assistance drive according to the invention in a fourth embodiment, in a schematic exploded depiction, zo FIG. 12 a power assistance drive according to FIG. 11 in the mounted state.

EMBODIMENTS OF THE INVENTION

[0042] In the various figures, the same parts always carry the same reference signs and are therefore usually only mentioned or described once.

[0043] FIG. 1 schematically shows a motor vehicle steering system 1 with a steering shaft 2 on which a steering wheel 11 is arranged for introduction of a steering torque (steering moment). For adaptation to the structural circumstances in the motor vehicle and to compensate for angular offset, universal joints 21 are inserted in the course of the steering shaft 2.

[0044] The motor vehicle steering 1 may be attached to a body of a vehicle (not shown) by means of a carrier unit 22 in which the steering shaft 2 is rotatably mounted.

[0045] A steering gear mechanism 3 has a housing 31 in which the steering shaft 2 is rotatably mounted. A steering pinion (pinion), arranged inside the housing 31 at the end of the steering shaft 2, intermeshes with the toothing of the toothed rack which is mounted in the housing 31 so as to be longitudinally displaceable in the direction of the spindle axis S, which is identical to an output axis, as indicated by the double arrow in FIG. 1. At both ends protruding from the housing 31, the toothed rack is connected to respective track rods 4 which in the known fashion are each connected to a steering knuckle of a steered wheel 5.

[0046] To support the steering movement of the toothed rack, caused by manual rotation of the steering shaft 2, a motorized power assistance drive 6 is arranged on the steering gear 3, as shown in different exploded depictions of a first embodiment in FIGS. 2 and 5, and in a second embodiment in FIGS. 3, 4 and 6, wherein the same reference signs are used for identical parts. A third embodiment is shown in FIGS. 7 to 10, and a fourth embodiment in FIGS. 11 and 12.

[0047] The power assistance drive 6 has an electric motor 61, preferably a servo motor, with a motor shaft 62.

[0048] The housing 31 is divided transversely to the spindle axis S, as evident in FIG. 2. As a power assistance gear, a belt drive, namely a toothed belt drive, is arranged in the housing 31 and comprises an input pulley 63 formed as a toothed belt pulley, an output pulley 64 also formed as a toothed belt pulley, and a circulating drive belt 65 formed as a toothed belt. The output pulley 64 is mounted in the housing 31 so as to be rotatable about the output or spindle axis S. The input pulley 63 is arranged on a drive shaft 66, which is mounted in the housing 31 in a bearing 67, preferably configured as a roller bearing, so as to be rotatable about an input axis A. The bearing 67 is attached to the housing 31 from the outside, and is retained by a bearing cover 32 flanged from the outside onto the housing 31.

[0049] The motor 61 is connected to the housing 31 by means of releasable connecting elements 68 which comprise for example bolts or screws, wherein the motor shaft 62 is oriented to the input axis A.

[0050] The input axis A and the spindle axis S lie substantially parallel to one another with an axial spacing b.

[0051] A releasable coupling 7 is arranged between the motor shaft 62 and the input pulley 63. The coupling 7 has a first coupling element 71 connected fixedly to the motor shaft 62, a second coupling element 72 arranged fixedly on the motor-side end of the drive shaft 66, and a transmission element 73 which, in the mounted operating state of the motor 61, couples the coupling elements 71 and 72 together in a torque-transmissive fashion.

[0052] The coupling elements 71 and 72 can be separated from one another axially in the direction of the input axis A. In this way, the motor 61 may be removed from the housing 31, wherein the coupling 7 is physically separated and the drive connection to the input pulley 63 is interrupted.

[0053] At its end remote from the motor, the drive shaft 66 is mounted unilaterally in the bearing 67 in the housing 31. On the motor side, it is mounted via the motor shaft 62 in the motor bearings of the motor 61.

[0054] The power assistance drive 6 is shown in the mounted state, enlarged, in FIG. 5. It is clearly evident how the drive shaft 66 is connected torque-transmissively to the motor shaft 62 via the coupling elements 71 and 72 and the interposed transmission element 73. It is also clearly evident that, at its end remote from the motor, the drive shaft 66 is mounted so as to be rotatable relative to the housing 31, in the bearing 67 which is received in the bearing cover 32.

[0055] FIGS. 5 and 5a show a first variant of how the two housing parts of the housing 31 can be connected to one another and to the motor 61 by means of releasable connecting elements 68. The connecting elements 68 may be configured as screws or bolts, and alternatively or additionally comprise form-fit elements 681 which, as shown as an example in FIG. 5b, may be molded as pins onto one of the halves of the housing 31 so as to position and/or fix the other half and/or the motor 61.

[0056] It is clear from FIG. 5 that a threaded spindle 8 extends coaxially to the spindle axis S, is configured as a ball screw spindle and engages in a spindle nut 81 which is coaxially connected to the output pulley 64 and is configured as a corresponding ball nut. The threaded spindle 8 is connected to the toothed rack 88 and together with the spindle nut 81 forms a spindle drive. The spindle nut 81 can be driven rotatably via the belt drive of the motor and is supported axially on the housing 31. Thus by rotation of the spindle nut 81, the threaded spindle 8 can be moved by the motor relative to the housing 31 in the zo direction of the spindle axis S, in order to support the steering force introduced manually into the steering rack 88 via the steering pinion 30.

[0057] FIGS. 3, 4 and 6 show a second embodiment in which the input pulley 63 is mounted in a bearing slide 69. The bearing slide 69 is mounted in the housing 31 so as to be displaceable transversely to the spindle axis S (output axis). Displacement of the bearing slide 69 causes a change in the axial spacing b, so that the belt tension of the drive belt 65 can be adjusted.

[0058] FIGS. 7 to 10 show a power assistance drive 6 which may be constructed as explained above with reference to FIGS. 1 to 6. A positioning device 9 is provided which comprises adjustment screws 91 guided through bores 92, formed in the housing 31 transversely to the spindle axis S, wherein they are oriented substantially parallel to the axial spacing b. The adjustment screws 91 rest in the screwing-in direction against a holder 93 which is connected to the motor 61. Between the holder 93 and the housing 31, adjustment nuts 94 are screwed onto the adjustment screws 91 and rest on the housing in the region of the bores 92. By screwing the adjustment nuts 94 onto the adjustment screws 91, the motor 61 can be moved in the direction away from the housing 31, as indicated by the arrow in FIG. 9. As a result, the input pulley 63 connected to the motor shaft 62 via the coupling 7 is moved in the direction away from the output pulley 64. In this way, the axial spacing b may be enlarged in order to increase the belt tension, or accordingly reduced in order to decrease the tension.

[0059] FIGS. 10, 11 and 12 show a derived positioning device 9. This has threaded bores 95 in the holder 94, into which the adjustment screws 91 of the motor 61 may be screwed and rest in the screwing-in direction on the housing 31 against protruding supporting brackets 33. By screwing the adjustment screws 91 into the threaded bores 95, the motor 61 may thus be moved in the direction away from the housing 31, whereby the axial spacing b may be changed in order to adjust the belt tension.

LIST OF REFERENCE SIGNS

[0060] 1 Motor vehicle steering system

[0061] 11 Steering wheel

[0062] 2 Steering shaft

[0063] 21 Universal joint

[0064] 22 Carrier unit

[0065] 3 Steering gear mechanism

[0066] 31 Housing

[0067] 32 Bearing cover

[0068] 33 Supporting bracket

[0069] 4 Track rods

[0070] 5 Wheel

[0071] 6 Power assistance drive

[0072] 61 Motor

[0073] 62 Motor shaft

[0074] 63 Input pulley

[0075] 64 Output pulley

[0076] 65 Drive belt

[0077] 66 Drive shaft

[0078] 67 Bearing

[0079] 68 Connecting element

[0080] 681 Form-fit element

[0081] 69 Bearing slide

[0082] 7 Coupling

[0083] 71, 72 Coupling elements

[0084] 73 Transmission element

[0085] 8 Spindle

[0086] 81 Spindle nut

[0087] 9 Positioning device

[0088] 91 Adjustment screw

[0089] 92 Bore

[0090] 93 Holder

[0091] 94 Adjustment nut

[0092] 95 Threaded bore

[0093] A Input axis

[0094] S Spindle axis (output axis)

[0095] b Axial spacing