Power-assisted steering assembly

Patent metadata

Field	Value
Publication number	US-10948060-B2
Application number	US-201816205467-A
Country	US
Kind code	B2
Filing date	Nov 30, 2018
Priority date	Nov 30, 2017
Publication date	Mar 16, 2021
Grant date	Mar 16, 2021

Abstract

A power-assisted steering assembly for a vehicle comprises: a motor shaft for transmitting torque from a motor; a steering rack; a primary transmission mechanism; a secondary transmission mechanism; a motor coupling; and a rack coupling. The primary transmission mechanism is configured to transmit power from the motor shaft to the steering rack and includes a drive belt. The secondary transmission mechanism is configured to transmit power from the motor shaft to the steering rack upon a failure of the primary transmission mechanism. The motor coupling is configured to transmit power from the motor shaft to the primary transmission mechanism and the secondary transmission mechanism. The rack coupling is configured to transmit power from the primary transmission mechanism and the secondary transmission mechanism to the steering rack. Prior to the failure of the primary transmission mechanism, the motor coupling and rack coupling are configured to transmit a greater amount of power to the primary transmission mechanism than to the secondary transmission mechanism.

First claim

What is claimed is:

1. A power-assisted steering assembly for a vehicle, the power-assisted steering assembly comprising:
a motor shaft for transmitting torque from a motor;
a steering rack;
a primary transmission mechanism configured to transmit power from the motor shaft to the steering rack, the primary transmission mechanism including a drive belt;
a secondary transmission mechanism configured to transmit power from the motor shaft to the steering rack upon a failure of the primary transmission mechanism;
a motor coupling configured to transmit power from the motor shaft to the primary transmission mechanism and the secondary transmission mechanism; and
a rack coupling configured to transmit power from the primary transmission mechanism and the secondary transmission mechanism to the steering rack;
wherein, prior to the failure of the primary transmission mechanism, the motor coupling and rack coupling are configured to transmit a greater amount of power to the primary transmission mechanism than to the secondary transmission mechanism.

2. The power-assisted steering assembly according to claim 1 , wherein one of the motor coupling and rack coupling comprises a first couple part in communication with the primary transmission mechanism, a second couple part in communication with the secondary transmission mechanism, and a lost-motion mechanism connecting the first couple part to the second couple part, the lost-motion mechanism allowing relative rotation of the first couple part and second couple part by an amount limited by the function of the lost-motion mechanism.

3. The power-assisted steering assembly according to claim 2 , wherein the lost-motion mechanism comprises a tooth and a detent engageable by the tooth, movement of the first couple part causing relative movement of the tooth and detent as the motor shaft rotates.

4. The power-assisted steering assembly according to claim 3 , wherein the lost-motion mechanism further comprises a compressible element that is compressed by movement of the tooth relative to the detent.

5. The power-assisted steering assembly according to claim 2 , wherein the lost-motion mechanism includes a spring-pin coupling.

6. The power-assisted steering assembly according to claim 2 , wherein the other of the motor coupling and rack coupling fixedly couples the primary transmission mechanism and the secondary transmission mechanism.

7. The power-assisted steering assembly according to claim 6 , wherein the motor coupling includes the first couple part and second couple part and the rack coupling fixedly couples the primary transmission mechanism and the secondary transmission mechanism.

8. The power-assisted steering assembly according to claim 6 , wherein the rack coupling includes the first couple part and second couple part and the motor coupling fixedly couples the primary transmission mechanism and the second transmission mechanism.

9. The power-assisted steering assembly according to claim 1 , further comprising a housing configured to separate the primary transmission mechanism from the secondary transmission mechanism over at least a part of a path of the drive belt.

10. The power-assisted steering assembly according to claim 1 , wherein the secondary transmission mechanism comprises an additional drive belt.

11. The power-assisted steering assembly according to claim 1 , wherein the secondary transmission mechanism comprises an idler gear.

12. The power-assisted steering assembly according to claim 11 , wherein the idler gear is sized such that it remains in mesh over a full range of adjustment of the primary transmission mechanism.

Assignees

• Trw Ltd
• Zf Automotive Uk Ltd

Inventors

• Boksenberg Jonathan Paul
• Kudanowski Maciej

Classifications

• B62D5/0424 Primary

  the axes of motor and final driven element of steering gear, e.g. rack, being parallel · CPC title

• B62D5/0427 Primary

  the axes being coaxial · CPC title

• B62D15/029

  Steering assistants using warnings or proposing actions to the driver without influencing the steering system · CPC title

• F16H7/02

  with belts; with V-belts · CPC title

• F16H37/065 Primary

  with a plurality of driving or driven shafts (F16H37/0806 takes precedence) · CPC title