Steering mechanism with toe-in control

• US 5,141,069 A
• Filed: 05/16/1990
• Issued: 08/25/1992
• Est. Priority Date: 09/13/1988
• Status: Expired due to Term

• Current Assignee: Aisin Seiki Co., Ltd. (Aisin Corp.)
• Original Assignee: Aisin Seiki Co., Ltd. (Aisin Corp.)
• Inventors: Yasui, Yoshiyuki
• Primary Examiner(s): HILL, MITCHELL
• Application Number:
  US07/524,073
• Time in Patent Office: 832 Days
• Field of Search: 180/132, 180/140, 180/141, 180/148, 180/79.1, 180/142, 180/143, 280/661, 280/668, 280/675, 280/90, 280/91, 364/424.05
• US Class Current: 180/422
• CPC Class Codes: B60G 2200/10 Independent suspensions
• CPC Class Codes: B60G 2200/462 Toe-in/out
• CPC Class Codes: B60G 2202/40 Type of actuator
• CPC Class Codes: B60G 2204/62 Adjustable continuously, e.g. during driving
• CPC Class Codes: B62D 17/00 Means on vehicles for adjusting camber, castor, or toe-in
• CPC Class Codes: B62D 5/22 for rack-and-pinion type
• CPC Class Codes: B62D 6/04 responsive only to forces disturbing the intended course of the vehicle, e.g. forces acting transversely to the direction of vehicle travel
• CPC Class Codes: B62D 7/159 characterised by computing methods or stabilisation processes or systems, e.g. responding to yaw rate, lateral wind, load, road condition
• CPC Class Codes: B62D 9/00 Steering deflectable wheels not otherwise provided for steering positon indicators B62D15/02

Abstract

The steering stability of a moving vehicle is maintained by measuring an actual yaw rate of the vehicle and determining a desired yaw rate of the vehicle and producing an output signal in response to a comparison of the actual and desired yaw rates. The steering angle of steerable wheels of the vehicle is controlled in response to the output signal in a manner tending to substantially conform the actual yaw rate to the desired yaw rate, thereby maintaining vehicle stability. The steerable wheels are steered by a steering wheel, and are independently steered by a motor in response to the output signal. That motor comprises a fluid motor. A toe-in control mechanism is also disclosed and functions to eliminate toe-in whenever the vehicle is steered through a turn.

Claims

1. A toe-in control mechanism for a vehicle steering apparatus, said apparatus comprising a laterally movable steering rod having ends, the steerable wheels of the vehicle linked to the ends of the steering rod, said toe-in control mechanism comprising:

a housing disposed adjacent to at least one end of the steering rod;

a linking element disposed within said housing and linked at one end to one steerable wheel and at the other end to the steering rod, said linking element movable in the lateral direction relative to the steering rod; and

actuating means for causing said linking element to move towards said steering rod whenever the vehicle is caused to turn by the steering mechanism, the movement of said linking element towards the steering rod eliminating toe-in by causing the steerable wheels to be aligned substantially parallel to each other.

2. The mechanism recited in claim 1, one said housing disposed adjacent and fixedly connected to each end of the steering rod, each said housing associated with a linking element and an actuating means.

3. The mechanism recited in claim 2 further comprising:

a piston fixedly disposed about each said linking element, each said piston defining a fluid chamber on one side thereof within each said housing;

a compressible element disposed between the second side of said piston and an inner wall of each said housing; and

said actuating means comprising fluid pressure source means in fluid communication with said fluid chamber for providing fluid pressure to said chamber;

wherein, the fluid pressure in said chamber is increased when the vehicle is caused to turn by the steering apparatus such that said pistons moves laterally within said housings, compressing the compressible elements and moving said linking elements towards the steering rod.

4. The mechanism recited in claim 3, said compressible element comprising a spring member.

5. The mechanism recited in claim 3, said compressible element comprising an elastic member.

6. The mechanism recited in claim 1 further comprising:

a piston fixedly disposed about said linking element, said piston defining a fluid chamber on one side thereof within said housing;

a compressible element disposed between the second side of said piston and an inner wall of said housing; and

said actuating means comprising fluid pressure source means in fluid communication with said fluid chamber for providing fluid pressure to said chamber;

wherein, the fluid pressure in said chamber is increased when the vehicle is caused to turn by the steering mechanism such that said piston moves laterally, compressing the compressible element and moving said linking element towards a steering rod.

7. The mechanism recited in claim 1, said linking element comprising a linking rod including a portion extending through said housing, said steering rod comprising a slot, extending portion fitting within said slot.

8. The mechanism recited in claim 7, a ball joint fixedly connected to the linking rod at the end opposite said extending portion, said ball joint further linked to the steerable wheel.

9. The mechanism recited in claim 1 further comprising a steering angle sensor means for sensing when the vehicle is caused to turn by the steering apparatus, said actuating means further comprising a central processor receiving an output signal from said steering angle sensor means, said central processor controlling said actuating means to cause said linking element to move.

10. The mechanism recited in claim 1 further comprising a first piston disposed about said linking element, a portion of the steering rod extending into said housing and a second piston disposed about said portion, said first and second pistons defining a first and a second fluid chamber within said housing;

a compressible element disposed between said first and said second pistons; and

said actuating means comprising fluid pressure source means in fluid comunication with said first and second fluid chambers for providing fluid pressure to said chambers;

wherein, the fluid pressure in both said chambers is increased when the vehicle is caused to turn by the steering mechanism such that said pistons move laterally towards each other, compressing said compressible element therebetween and moving said linking element towards the steering rod.

11. The mechanism recited in claim 10, the steering apparatus comprising an outer housing portion, said housing fixedly disposed on end of the outer housing portion.

12. The mechanism recited in claim 10 further comprising a steering angle sensor means for sensing when the vehicle is caused to turn by the steering apparatus, said actuating means further comprising a central processor receiving an output signal from said sensor means, said central processor controlling said fluid pressure source means to pressurise said chambers.

33. The mechanism recited in claim 1 further comprising detecting means for detecting whenever the vehicle is caused to turn by the steering mechanism.

13. The combination of a steering apparatus and a toe-in control mechanism for a vehicle, said steering apparatus comprising a laterally movable steering rod having ends, the steerable wheels of the vehicle linked to the ends of said steering rod, and steering input means for linking said steering rod to a steering wheel and causing said steering rod to move laterally when the steering wheel is rotated to steer the steerable wheels, said toe-in control mechanism comprising:

a housing disposed adjacent to at least one end of said steering rod;

a linking element disposed within said housing and linked at one end to one steerable wheel and at the other end to said steering rod, said linking element movable in the lateral direction relative to said steering rod; and

actuating means for causing said linking element to move towards said steering rod simultaneously with initiation of lateral movement of said steering rod whenever the vehicle is steered through a turn, the movement of said linking element towards said steering rod eliminating toe-in by causing the steerable wheels to be aligned substantially parallel to each other.

14. The combination recited in claim 13, one said housing disposed adjacent and fixedly connected to each end of said steering rod, each said housing associated with a linking element and an actuating means.

15. The combination recited in claim 14 further comprising:

a piston fixedly disposed about said linking elements, said piston defining a fluid chamber on one side thereof within said housing;

a compressible element disposed between the second side of said piston and an inner wall of said housing; and

said actuating means comprising fluid pressure source means in fluid comunication with said fluid chamber for providing fluid pressure to said chamber;

wherein, the fluid pressure in said chamber is increased simultaneously with initiation of lateral movement of said steering rod when the vehicle is steered through a turn, compressing said compressible element and moving said linking means towards said steering rod.

16. The combination recited in claim 13 further comprising:

a piston fixedly disposed about said linking elements, said piston defining a fluid chamber on one side thereof within said housing;

a compressible element disposed between the second side of said piston and an inner wall of said housing; and

said actuating means comprising fluid pressure source means in fluid comunication with said fluid chamber for providing fluid pressure to said chamber;

wherein, the fluid pressure in said chamber is increased simultaneously with initiation of lateral movement of said steering rod when the vehicle is steered through a turn, compressing said compressible element and moving said linking means towards said steering rod.

17. The combination recited in claim 13 further comprising a steering angle sensor means for sensing the initiation of lateral movement of said steering rod, said actuating means further comprising a central processor receiving an output signal from said sensor means, said central processor controlling said actuating means to cause said linking element to move towards said steering rod.

18. The combination recited in claim 13 further comprising a first piston disposed about said linking element, a portion of said steering rod extending into said housing and a second piston disposed about said portion, said first and second pistons defining a first and a second fluid chamber within said housing;

a compressible element disposed between said first and said second piston; and

said actuating means comprising fluid pressure source means in fluid comunication with said first and second fluid chambers for providing fluid pressure to said chambers;

wherein, the fluid pressure in both said chambers is increased simultaneously with initiation of lateral movement of said steering rod such that said pistons move laterally towards each other, compressing said compressible element therebetween and moving said linking element towards said steering rod.

34. The combination recited in claim 13 further comprising detecting means for detecting whenever the vehicle is steered through a turn.

19. A vehicle steering apparatus for providing adaptive steering control and including a toe-in control mechanism, said apparatus comprising:

a movable rack mounted for lateral movement with respect to the vehicle, said rack having a housing fixed at one end;

a steering rod disposed within said rack and laterally movable with and with respect to said rack, one end of said steering rod terminating within said housing;

steering input means for causing said steering rod and said rack to move jointly in the lateral direction during steering control;

a linking element disposed adjacent said one end of said steering rod and within said housing, said linking element further linked to a steerable wheel of the vehicle at the end opposite said steering rod, said linking element and said steering rod movable relative to each other;

actuating means for causing said linking element to move towards said steering rod; and

control means for detecting when the vehicle is turning and for measuring an actual steering condition of the vehicle and for determining a desired steering condition of the vehicle, said control means controlling said actuating means to cause said linking element to move towards said steering rod whenever said control means detects the initiation of a vehicle turn to substantially eliminate toe-in, by causing the steerable wheels to be aligned substantially parallel to each other, said control means also causing said steering rod to move relative to said rack in the lateral direction whenever the actual steering condition differs from the desired steering condition, to maintain steering stability by causing said actual steering condition to become substantially equal to said desired steering condition.

20. The apparatus recited in claim 19 further comprising:

a first piston disposed about said steering rod and a second piston disposed about said linking element, both said first and said second pistons disposed within said housing and jointly defining first and second fluid chambers within said housing;

a compressible element operably disposed between said first and second pistons;

said actuating means comprising fluid pressure source means in fluid comunication with both said first chamber and said second chamber for providing fluid pressure to each said chamber;

wherein,

when said control means detects the vehicle is turning, said control means causes said fluid pressure source means to pressurise both said chambers to a predetermined minimum threshold value so as to cause said pistons to move towards each other and compress said compressible element therebetween, the movement of said pistons causing said linking element to move towards said steering rod, and wherein when said actual steering condition differs from the desired steering condition, said control means causes said fluid pressure source means to futher pressurise one said chamber with respect to the other said chamber thereby causing said steering rod to move relative to said rack to maintain steering stability.

21. The steering apparatus recited in claim 20, said linking element comprising a linking rod having an axial extending portion, said steering rod including an axial slot formed therein, said extending portion disposed within said slot, said compressible element comprising a spring member disposed about said axial extending portion within said slot.

22. The steering apparatus recited in claim 20, said compressible element comprising an elastic member disposed between said pistons.

23. The steering apparatus recited in claim 20, said linking element linked to the steerable wheel by a ball joint fixedly connected to said linking element.

24. The steering apparatus recited in claim 20, said control element measuring the actual yaw rate of the vehicle and determining a desired yaw rate for the vehicle.

25. The steering apparatus recited in claim 24, said control means comprising a steering wheel angle sensor, said sensor detecting both the desired yaw rate and when the vehicle is turning.

26. The steering apparatus recited in claim 19, said control means measuring the actual yaw rate of the vehicle and determining a desired yaw rate for the vehicle.

27. A vehicle steering apparatus for providing adaptive steering control and including a toe-in control mechanism, said apparatus comprising:

a movable rack mounted for lateral movement with respect to the vehicle, said rack including a housing at an intermediate location;

a steering rod disposed within said rack and laterally movable with and with respect to said rack, said steering rod comprising first and second steering rod portions which are moveable relative to each other, one end of each said steering rod portion terminating within said housing, the other end of each said steering rod portion linked to a steerable wheel of the vehicle;

steering input means for causing said steering rod and said rack to move jointly in the lateral direction during steering control;

actuating means for causing said steering rod portions to move towards each other; and

control means for detecting when the vehicle is turning and for measuring an actual steering condition of the vehicle and for determining a desired steering condition of the vehicle, said control means controlling said actuating means to cause said steering rod portions to move towards each other whenever said control means detects the initiation of a vehicle turn to substantially eliminate toe-in, by causing the steerable wheels to be aligned substantially parallel to each other said control means also causing both said steering rod portions to jointly move relative to said rack in the lateral direction whenever the actual steering condition differs from the desired steering condition, to maintain steering stability by causing said actual steering condition to become substantially equal to said desired steering condition.

28. The apparatus recited in claim 27 further comprising:

a first piston disposed about said first steering rod portion and a second piston disposed about said second steering rod portion, both said first and said second pistons disposed within said housing and jointly defining first and second fluid chambers within said housing;

a compressible element operably disposed between said first and second pistons;

said actuating means comprising fluid pressure source means in fluid comunication with both said first chamber and said second chamber for providing fluid pressure to each said chamber;

wherein,

when said control means detects the vehicle is turning, said control means causes said fluid pressure source means to pressurise both said chambers to a predetermined minimum threshold value so as to cause said pistons to move towards each other and compress said compressible element therebetween, the movement of said pistons causing said first steering rod portion to move towards said second steering rod portion, and wherein when said actual steering condition differs from the desired steering condition, said control means causes said fluid pressure source means to further pressurise one said chamber with respect to the other said chamber thereby causing both said steering rod portions to jointly move relative to said rack to maintain steering stability.

29. The steering apparatus recited in claim 28, said control means measuring the actual yaw rate of the vehicle and determining a desired yaw rate for the vehicle.

30. The steering apparatus recited in claim 29, said control means comprising a steering wheel angle sensor, said sensor detecting both the desired yaw rate and when the vehicle is turning.

31. The steering apparatus recited in claim 28, said first steering rod portion including an axial extending portion, said second steering rod portion including an axial slot formed therein, said extending portion disposed within said slot, said compressible element comprising a spring member disposed about said axial extending portion within said slot.

32. The steering apparatus recited in claim 28, said compressible element comprising an elastic member.