Intermediate Shaft Assembly for Steer-by-Wire Steering System

• US 20180072341A1
• Filed: 09/12/2016
• Published: 03/15/2018
• Est. Priority Date: 09/12/2016
• Status: Active Grant

• Current Assignee: Steering Solutions IP Holding Corporation (Nexteer Automotive Group Ltd.)
• Original Assignee: Steering Solutions IP Holding Corporation (Nexteer Automotive Group Ltd.)
• Inventors: Schulz, John F., Riefe, Richard K.
• Granted Patent: US 10,384,708 B2
• Time in Patent Office: Days
• CPC Class Codes: B62D 1/16 Steering columns
• CPC Class Codes: B62D 1/20 Connecting steering column to steering gear
• CPC Class Codes: B62D 5/001 Mechanical components or aspects of steer-by-wire systems, not otherwise provided for in this maingroup
• CPC Class Codes: B62D 5/003 Backup systems, e.g. for manual steering B62D5/30 takes precedence
• CPC Class Codes: F16D 3/06 specially adapted to allow axial displacement
• CPC Class Codes: F16D 3/10 Couplings with means for varying the angular relationship of two coaxial shafts during motion
• CPC Class Codes: F16D 3/38 with a single intermediate member with trunnions or bearings arranged on two axes perpendicular to one another F16D3/36 takes precedence

Abstract

A steer-by-wire steering system includes a steering wheel. Also included is a steering shaft operatively coupled to the steering wheel and rotatable therewith. Further included is a steering gear input shaft operatively coupled to an electric power assist steering gear. Yet further included is an electric actuator operatively coupled to the electric power assist steering gear. Also included is a controller in operative communication with the steering shaft and the electric actuator for steering in a primary mode. Further included is an intermediate shaft assembly mechanically coupling the steering shaft to a rack and pinion assembly to steer in a redundant mode when communication between the steering shaft and the steering gear input shaft is not available.

Claims

1. A steer-by-wire steering system comprising:

a steering wheel;

a steering shaft operatively coupled to the steering wheel and rotatable therewith;

a steering gear input shaft operatively coupled to an electric power assist steering gear;

an electric actuator operatively coupled to the electric power assist steering gear;

a controller in operative communication with the steering shaft and the electric actuator for steering in a primary mode; and

an intermediate shaft assembly mechanically coupling the steering shaft to a rack and pinion assembly to steer in a redundant mode when electrical communication between the steering shaft and the steering gear input shaft is not available.

2. The steer-by-wire steering system of claim 1, wherein the intermediate shaft assembly comprises:

an outer shaft operatively coupled to a first joint; and

an inner shaft operatively coupled to a second joint, a portion of the inner shaft disposed within an interior of the outer shaft to form an overlapped region of the inner shaft and the outer shaft that is engageable when communication between the steering shaft and the steering gear input shaft is not available.

3. The steer-by-wire steering system of claim 2, further comprising:

a first plurality of splines disposed on an inner surface of the outer shaft; and

a second plurality of splines disposed on an outer surface of the inner shaft, the first plurality of splines and the second plurality of splines having a clearance therebetween, the first and second plurality of splines engageable when communication between the steering shaft and the steering gear input shaft is not available.

4. The steer-by-wire steering system of claim 2, the intermediate shaft assembly further comprising a plurality of frictionless bearings disposed between the inner shaft and the outer shaft within the overlapped region.

5. The steer-by-wire steering system of claim 1, wherein the redundant mode is continuously available in the event of a loss of communication between the steering shaft and the steering gear input shaft.

6. The steer-by-wire steering system of claim 2, further comprising a coating disposed on at least a portion of an inner surface of the outer shaft and an outer surface of the inner shaft within the overlapped region to reduce contact noise.

7. The steer-by-wire steering system of claim 6, wherein the coating comprises plastic.

8. The steer-by-wire steering system of claim 1, wherein the outer shaft and the inner shaft are not engaged until rotation of a predetermined angular displacement of the outer shaft is made.

9. The steer-by-wire steering system of claim 8, wherein the predetermined angular displacement ranges from 2 degrees to 10 degrees.

10. An intermediate shaft assembly of a steer-by-wire steering system comprising:

an outer shaft operatively coupled to a first joint;

an inner shaft operatively coupled to a second joint, a portion of the inner shaft disposed within an interior of the outer shaft to form an overlapped region of the inner shaft and the outer shaft, the inner shaft and the outer shaft mechanically coupling a steering shaft to a steering gear input shaft;

a first plurality of splines disposed on an inner surface of the outer shaft; and

a second plurality of splines disposed on an outer surface of the inner shaft, the first plurality of splines and the second plurality of splines having a clearance therebetween, the first and second plurality of splines engageable when communication between the steering shaft and the steering gear input shaft is not available.

11. The intermediate shaft assembly of claim 10, further comprising a plurality of frictionless bearings disposed between the inner shaft and the outer shaft within the overlapped region.

12. The intermediate shaft assembly of claim 10, wherein the redundant mode is continuously available in the event of a loss of communication between the steering shaft and the steering gear input shaft.

13. The intermediate shaft assembly of claim 10, further comprising a coating disposed on at least a portion of an inner surface of the outer shaft and an outer surface of the inner shaft within the overlapped region to reduce contact noise.

14. The intermediate shaft assembly of claim 13, wherein the coating comprises plastic.

15. The intermediate shaft assembly of claim 10, wherein the outer shaft and the inner shaft are not engaged until rotation of a predetermined angular displacement of the outer shaft is made.

16. The intermediate shaft assembly of claim 15, wherein the predetermined angular displacement ranges from 2 degrees to 10 degrees.