FEEDBACK ACTUATOR FOR A STEERING DEVICE OF A MOTOR VEHICLE AND STEERING COLUMN FOR A MOTOR VEHICLE

Abstract

A feedback actuator for a steering device of a motor vehicle may include a steering shaft that is mounted so as to be rotatable about a longitudinal axis extending in a longitudinal direction and that, by way of a belt drive, is coupled to a motor shaft of an electric motor so as to be able to be rotatably driven. The belt drive may have at least one pair of belt pulleys having two belt pulleys that are wrapped by a belt. One of the belt pulleys may be operatively connected to the motor shaft and one may be operatively connected to the steering shaft. The two belt pulleys of the pair of belt pulleys may be disposed so as to be mutually coaxial or at a mutual angle.

Claims

1.-11. (canceled)

12. A feedback actuator for a steering device of a motor vehicle, comprising a steering shaft that is mounted so as to be rotatable about a longitudinal axis extending in a longitudinal direction, wherein by way of a belt drive the steering shaft is coupled to a motor shaft of an electric motor so as to be able to be rotatably driven, the belt drive having at least one pair of belt pulleys having two belt pulleys that are wrapped by a belt, wherein a first of the belt pulleys is operatively connected to the motor shaft and a second of the belt pulleys is operatively connected to the steering shaft, wherein the two belt pulleys of the pair of belt pulleys are disposed so as to be mutually coaxial or at a mutual angle.

13. The feedback actuator of claim 12 wherein the belt is parallel to a belt plane that is oblique relative to the longitudinal axis.

14. The feedback actuator of claim 12 wherein the two belt pulleys have in each case a conical basic shape, having belt running surfaces that on external sides of the belt pulleys that axially face away from one another conically converge in a direction of the longitudinal axis.

15. The feedback actuator of claim 12 wherein the belt drive has at least one of a flat belt, a V-belt, or a timing belt.

16. The feedback actuator of claim 12 wherein the belt drive is configured in two or more stages.

17. The feedback actuator of claim 12 comprising a layshaft disposed between the motor shaft and the steering shaft, wherein the layshaft has two coaxial belt pulleys that are connected in a rotationally fixed manner.

18. The feedback actuator of claim 17 wherein the layshaft is coaxial with the steering shaft.

19. The feedback actuator of claim 17 wherein the layshaft is coaxial with the motor shaft.

20. The feedback actuator of claim 17 wherein the layshaft is at an oblique angle relative to the steering shaft.

21. The feedback actuator of claim 17 wherein the layshaft is at an oblique angle relative to the motor shaft.

22. The feedback actuator of claim 12 comprising a tensioner installation for tensioning the belt.

23. The feedback actuator of claim 22 wherein the tensioner installation has a tensioning means that stresses a strand of the belt with a tensioning force transverse to the extent of the belt.

24. A steering column for a motor vehicle, comprising a casing unit that is attachable to a motor vehicle body and in which a steering shaft is mounted so as to be rotatable about a longitudinal axis thereof extending in a longitudinal direction, with a steering wheel being attachable to the steering column, the steering column being connected to the feedback actuator of claim 12 that has the electric motor and the belt drive for generating and coupling a feedback torque into the steering shaft.

25. The feedback actuator of claim 24 wherein the feedback actuator is disposed in an internal casing that in the longitudinal direction is adjustable relative to the casing unit.

Description

DESCRIPTION OF THE DRAWINGS

[0040] Advantageous embodiments of the invention will be explained in more detail hereunder by means of the drawings in which:

[0041] FIG. 1 shows a steering column according to the invention in a schematic perspective view;

[0042] FIG. 2 shows a feedback actuator according to the invention of the steering column according to FIG. 1 in a schematic stand-alone perspective view;

[0043] FIG. 3 shows a longitudinal section through the belt drive according to the invention of the feedback actuator according to FIG. 2; and

[0044] FIG. 4 shows a longitudinal section through a belt drive according to the invention of the feedback actuator in a further variant of embodiment.

EMBODIMENTS OF THE INVENTION

[0045] Identical parts are at all times provided with the same reference signs in the various figures and are therefore typically also in each case referred to or mentioned only once.

[0046] FIG. 1 shows a steering column 1 according to the invention in a perspective view obliquely from the rear in terms of the direction of travel. FIG. 2 shows a partially sectional, or cut-away partial, view of the steering column 1, and FIG. 3 shows a partial longitudinal section.

[0047] The steering column 1 has an actuating unit 2. The actuating unit 2 comprises a casing unit 3 having three casing tubes 31, 32, 33, specifically an external casing tube 31, an intermediate casing tube 32, and an internal casing tube 33. The casing tubes 31, 32 and 33 are disposed coaxially inside one another and telescopically displaceable in the longitudinal direction, the latter corresponding to the direction of a longitudinal axis L, as a result of which a longitudinal adjustment is made possible as indicated by the double arrow. The casing tubes 31, 32, 33 for shortening the steering column 1 can be collapsed, i.e. retracted in the longitudinal direction up to a maximum stowage position, and conversely be deployed from the stowage position in the direction of an operating position.

[0048] Alternatively, a merely two-part telescopic assembly can be formed from an external casing tube 31 and an internal casing tube 33, thus without an intervening intermediate casing tube 32. In another alternative, one or more further intermediate casing tubes 32 may be fitted in order for a multiple telescope to be formed.

[0049] A steering spindle 4, also referred to as a steering shaft 4, is mounted in the casing unit 3 so as to be rotatable about the longitudinal axis L, said steering spindle 4 at the rear end thereof having a connector portion 41 for attaching a steering wheel not illustrated.

[0050] The casing unit 3 is held in a two-part support unit 5 which has fastening means 51 for attaching to a vehicle body not illustrated.

[0051] An adjustment drive 6 is provided for the motorized longitudinal adjustment, said adjustment drive 6 having a spindle drive having a spindle nut 61 and a threaded spindle 62 screwed into the latter, said spindle nut 61 and said threaded spindle 62 being able to be rotatably driven relative to one another by an electric motor 63. An immersion spindle drive is implemented as a result.

[0052] The threaded spindle 62 extends parallel to the longitudinal axis L and is connected to the internal casing tube 33. The spindle nut 61 by way of the adjustment drive 6 is supported in the longitudinal direction on the external casing tube 31. The threaded spindle 62 and the spindle nut 61 are converged or diverged, depending on the direction of rotation, by a relative rotation by means of the motor 63, as a result of which the internal casing tube 33 in the axial direction can either be retracted into the external casing tube 41, or in the opposite direction, a deployment direction, can be deployed from the external casing tube 31. As a result, a steering wheel attached to the connector portion 41 can selectively be moved toward the front to a stowage position in which the internal casing tube 33 and the intermediate casing tube 32 are retracted into the external casing tube 31, i.e. lowered toward the front, or can be moved rearward to an operating position in which the casing tubes 31, 32 and 33 are diverged.

[0053] Alternatively, the spindle nut 61 can be supported on the internal casing tube 33, and the threaded spindle 62 can be supported on the external casing tube 31.

[0054] Alternatively, it is possible for a rotary spindle drive to be configured by a rotating drive of the threaded spindle 62 and a spindle nut 61 that is attached so as to be stationary on a casing tube.

[0055] FIG. 2 shows a perspective partial view of the steering column 1, wherein the internal casing tube 33 is schematically illustrated so as to be translucent or omitted, respectively, such that the view into the interior is unobstructed. A longitudinal section along the longitudinal axis L through the assembly shown in FIG. 2 is shown in FIG. 3.

[0056] Disposed in the internal casing tube 33 is a belt-driven feedback actuator 7 according to the invention, said feedback actuator 7 according to the invention comprising a first belt drive 8 and a second belt drive 9 which are of identical construction and as gear stages of a belt gear are operatively disposed in series. The motor shaft 72 for coupling in the feedback torque is connected to the steering shaft 4 by way of the belt drives 8 and 9, said steering shaft 4 in a bearing assembly 42 in the internal casing tube 33 being mounted so as to be rotatable about the longitudinal axis L.

[0057] The feedback actuator 7 has an electric motor 71 which is fastened in the internal casing tube 33 and has a motor shaft 72 which is coaxial with the longitudinal axis L and is able to be selectively driven in a rotating manner in both directions of rotation. A first belt pulley 81 is fastened on the motor shaft 72, likewise so as to be coaxial with the longitudinal axis L. Said first belt pulley 81 is configured so as to be conical, having an externally encircling belt running surface 810 which proximal to the motor converges conically in the direction of the longitudinal axis L.

[0058] A layshaft 73 is axially spaced apart from the motor shaft 72, i.e. mounted in two bearing supports 74 and 75 attached to the internal casing tube 33 at a spacing in the longitudinal direction defined by the longitudinal axis L, and so as to be coaxial with and rotatable about the longitudinal axis L.

[0059] A second belt pulley 82 is fixed so as to be rotationally fixed on the layshaft 73 and coaxial with the longitudinal axis L, for example as illustrated as a result of an integral configuration with the layshaft 82, for example as a plastic injection-molded part, or made in a subtractive manner or as a casting from metal. This second belt pulley 82 is configured so as to be conical, having an externally encircling belt running surface 820 which proximal to the steering shaft converges conically in the direction of the longitudinal axis L, thus in terms of the conical shape of the belt running surface 810 of the belt pulley 81 being mirror-symmetrical in relation to a transverse plane of the longitudinal axis L.

[0060] The two belt pulleys 81 and 82 for forming the belt drive 8 are wrapped by a belt 83 which ensures a transmission of torque and is configured as a flat belt. The belt 83 bears in a friction-fitting manner on the belt running surfaces 810 and 820. The belt pulley 81 has a smaller diameter than the belt pulley 82, the gear ratio of the belt drive 8 being determined as a result.

[0061] The strands which are formed by the free belt portions between the two belt pulleys 81 and 82 run parallel to a strand plane A of the first belt drive 8, which is plotted using dashed lines in FIG. 3 and is also referred to as the belt plane A. The belt 83 extends in a closed belt loop which encircles the belt pulleys 81 and 82 and is parallel to the strand plane or belt plane A.

[0062] According to the invention, the strand plane A is oblique in relation to the longitudinal axis L, thus at an inclination angle α (alpha) which deviates from a right angle and is less than 90° and more than 0°, preferably is in a range between 20° to 70°, particularly preferably between 30° and 60°.

[0063] The inclination angle α is determined by the axial spacing of the two belt pulleys 81 and 82 as well as by the diameters of said two belt pulleys 81 and 82.

[0064] The belt running surfaces 810 and 820 are inclined so as to be conical in relation to the longitudinal axis L, in accordance with the inclination α of the strand plane A, in such a manner that the belt 83 bears thereon perpendicularly to the strand plane A. Accordingly, the belt running surface 810 is inclined by (α+90°), while the other belt running surface 820 is inclined by (α−90°).

[0065] A third belt pulley 91 is fixed in a rotationally fixed manner on the layshaft 73, so as to be coaxial with the longitudinal axis L and at a spacing from the belt pulley 82, for example as illustrated by an integral configuration conjointly with the layshaft 82 and the second belt pulley 82, for example as a plastic injection-molded part, or made in a subtractive manner or as a casting from metal.

[0066] The third belt pulley 91 is conically configured, having an externally encircling belt running surface 910 which, as with the first belt pulley 81, proximal to the motor converges conically in the direction of the longitudinal axis L.

[0067] A fourth belt pulley 92 is fixed on the layshaft 4 so as to be axially spaced apart from the belt pulley 91, said fourth belt pulley 91 being conically configured having an externally encircling belt running surface 920 which, as with the second belt pulley 92, proximal to the steering shaft converges conically in the direction of the longitudinal axis L, thus in terms of the conical shape of the belt running surface 910 of the belt pulley 91 is mirror-symmetrical to a transverse plane of the longitudinal axis L.

[0068] The two belt pulleys 91 and 92 for forming the belt drive 9 are wrapped by a belt 93 which ensures a transmission of torque and is configured as a flat belt. The belt 93 bears in a friction-fitting manner on the belt running surfaces 910 and 920.

[0069] The belt pulley 91 has a smaller diameter than the belt pulley 92, the gear ratio of the second belt drive 9 being determined as a result.

[0070] The strands formed by the free belt portions between the two belt pulleys 91 and 92 run parallel to a strand plane B of the second belt drive 9, which is plotted using dashed lines in FIG. 3 and is also referred to as the belt plane B. The belt 93 extends in a closed belt loop that encircles the belt pulleys 91 and 92 and is parallel to the strand plane or belt plane B.

[0071] According to the invention, the belt plane B is oblique in relation to the longitudinal axis L, thus at an inclination angle β (beta) which deviates from a right angle and is less than 90° and more than 0°, preferably is in a range between 20° and 70°, particularly preferably between 30° and 60°.

[0072] The inclination angle β is determined by the axial spacing of the two belt pulleys 91 and 92 as well as by the diameters of said two belt pulleys 91 and 92.

[0073] The belt running surfaces 910 and 920 are inclined so as to be conical in relation to the longitudinal axis L, in accordance with the inclination β of the strand plane B, in such a manner that the belt 93 bears thereon perpendicularly to the strand plane B. Accordingly, the belt running surface 910 is inclined by (β+90°), and the other belt running surface 920 is inclined by (β−90°).

[0074] The overall gear ratio of the belt gear between the motor shaft 72 and the steering shaft 4 is derived from the product of the gear ratios of the two belt drives 8 and 9.

[0075] If required, even further layshafts may be provided, which in this instance can likewise be disposed axially between the motor shaft 72, the steering shaft 4 and the further layshafts 73.

[0076] A tensioner installation having in each case at least one tensioning means which exerts a contact pressure force transverse to the extent of the belt 83 or 93 and which loads the two strands against one another or else away from one another such that a belt tension can be generated, can be provided for each of the two belt drives 8 and 9. A tensioner installation can have, for example, a spring-loaded contact pressure roller 76 acting on the belt 83 or 93.

[0077] A longitudinal section through a belt drive of the feedback actuator according to the invention in a further variant of embodiment is illustrated in FIG. 4, wherein this further variant of embodiment has a layshaft 73 which is disposed at an angle φ in relation to the motor shaft 72 and in relation to the steering shaft 4. The belt pulleys 182, 191 are configured integrally with the layshaft 73, wherein the belt pulley 182 conjointly with the belt pulley 81 forms a pair of belt pulleys, and wherein the belt pulley 182 is disposed at an angle in relation to the belt pulley 81, i.e. the rotation axis of the belt pulley 182, which corresponds to the layshaft axis Z, is disposed at an angle to the rotation axis of the belt pulley 81, which corresponds to the longitudinal axis L or the motor shaft axis, respectively.

[0078] The belt pulley 191 conjointly with the belt pulley 92 forms a pair of belt pulleys, wherein the belt pulley 191 is disposed at an angle in relation to the belt pulley 92, i.e. the rotation axis of the belt pulley 191, which corresponds to the layshaft axis Z, is at an angle in relation to the rotation axis of the belt pulley 92, which corresponds to the longitudinal axis L.

[0079] The belt pulley 182 has a belt running surface 820, and the belt pulley 191 has a belt running surface 910, said belt running surfaces 820, 910 operatively engaging in each case with the corresponding belt 83, 93.

[0080] The layshaft 73 is rotatably mounted in the bearing supports 74, 75 and is supported on the respective bearing support 74, 75 so as to be secured in relation to being repositioned in the direction of the layshaft axis Z.

[0081] All explanations pertaining to FIG. 3 can be applied in a substantially analogous manner to FIG. 4 and will therefore not be discussed again.

LIST OF REFERENCE SIGNS

[0082] 1 Steering column [0083] 2 Actuating unit [0084] 3 Casing unit [0085] 31 External casing tube [0086] 32 Intermediate casing tube [0087] 33 Internal casing tube [0088] 4 Steering spindle (steering shaft) [0089] 41 Connector portion [0090] 42 Bearing assembly [0091] 5 Support unit [0092] 51 Fastening means [0093] 6 Adjustment drive [0094] 61 Spindle nut [0095] 62 Threaded spindle [0096] 63 Motor [0097] 7 Feedback actuator [0098] 71 Motor [0099] 72 Motor shaft [0100] 73 Layshaft [0101] 74, 75 Bearing support [0102] 76 Contact pressure roller [0103] 8, 9 Belt drive [0104] 81, 91 Belt pulley [0105] 82, 92 Belt pulley [0106] 810, 820 Belt running surface [0107] 910, 920 Belt running surface [0108] 83, 93 Belt [0109] L Longitudinal axis [0110] A, B Strand plane (belt plane) [0111] α, β Angle of inclination [0112] φ Angle