All-wheel steering system

• US 5,607,028 A
• Filed: 05/19/1995
• Issued: 03/04/1997
• Est. Priority Date: 11/29/1993
• Status: Expired due to Term

• Current Assignee: Oshkosh Corporation
• Original Assignee: Oshkosh Corporation
• Inventors: Pillar, Duane R., Braun, Eric E., Halgrimson, Curtis
• Primary Examiner(s): Hurley, Kevin
• Application Number:
  US08/445,117
• Time in Patent Office: 655 Days
• Field of Search: 180/408, 180/411, 180/412, 180/413, 180/414, 180/415, 180/24.01, 280/91.1, 280/419, 280/426, 280/442, 280/443, 364/424.01, 364/424.05
• US Class Current: 180/408
• CPC Class Codes: B62D 7/1509 with different steering modes, e.g. crab-steering, or steering specially adapted for reversing of the vehicle

Abstract

A full-time all wheel steering system is provided whereby the rear wheel angle is determined by the front wheel angle and a relational curve, polynomial equation or set of tabulated values. The front wheel angle is measured and the desired rear wheel angle is calculated by a programmable controller. If the desired rear wheel angle is not sufficiently close to the actual rear wheel angle, the controller means sends a signal which results in adjustment of the rear wheel angle. The desired rear wheel angle may be a function of the vehicle speed as well as the front wheel angle. A dead band may be employed which maintains the rear wheels in a straight ahead position when the front wheel angle does not exceed the dead band value. The maximum rear wheel cramp angle may also be controlled as a function of vehicle speed. The system is applicable to passenger cars, trucks and tractor-trailer rigs.

Claims

1. An all wheel steering system for a vehicle having front wheels with a front wheel angle, rear wheels with a rear wheel angle, and a steering wheel, the front wheel angle being determined by an operator positioning the steering wheel, the rear wheel angle being determined by the system, the system comprising:

means for sensing a front wheel angle of at least one front wheel,

means for communicating the front wheel angle to a controller means, the controller means including a memory containing at least one desired rear wheel angle for each front wheel angle, the desired rear wheel angle being dependant upon the front wheel angle, the desired rear wheel angle having an absolute value greater than 0°

when the front wheel angle exceeds a dead band value, the dead band value being a variable ranging from 0°

for slow speeds not exceeding 10 mph to 30°

for high speeds exceeding 35 mph, the desired rear wheel angle is 0°

when the front wheel angle does not exceed the dead band value, the controller means retrieving a desired rear wheel angle based on the front wheel angle from the memory of the controller means,

means for sensing an actual rear wheel angle of at least one rear wheel,

means for communicating the actual rear wheel angle to the controller means,

the controller means comparing the actual rear wheel angle with the desired rear wheel angle, the controller means sending a signal to alter the actual rear wheel angle to a means for controlling the actual rear wheel angle if the actual rear wheel angle differs from the desired rear wheel angle by an amount that is greater than a desired amount.

2. The system of claim 1,

further including a means for locking all rear wheels in a straight-ahead position if an operating component of the system fails.

3. The system of claim 1,

further including a means for locking all rear wheels in their current position if an operating component of the system fails.

4. The system of claim 1,

further including a manual switching means for selecting from a plurality of all-wheel, front-wheel and rear wheel steering modes.

5. The system of claim 4,

wherein the steering modes are further characterized as

a front wheel only steering mode in which the desired rear wheel angle is fixed in a straight-ahead position,

a second all-wheel steering mode in which the desired rear wheel angle is generally opposite in direction to that of the front wheel angle, and

a third all-wheel steering mode in which the desired rear wheel angle is generally of a same direction as that of the front wheel angle.

6. The system of claim 5,

wherein the all-wheel steering modes further include a fourth rear wheel steering mode in which the desired rear wheel angle may be controlled independently of the front wheel angle.

7. The system of claim 1,

wherein the vehicle includes a first rear axle and a second rear axle, a first pair of rear wheels being mounted on opposing sides of the first rear axle, a second pair of rear wheels being mounted on opposing sides of the second rear axle, sensor means for measuring the rear wheel angle of at least one rear wheel of the first pair or rear wheels, sensor means for measuring the rear wheel angle of at least one rear wheel of the second pair of rear wheels,

means for communicating the actual rear wheel angle of the first pair of rear wheels to the controller means, means for communicating the actual rear wheel angle of the second pair of rear wheels to the controller means,

the controller means sending a signal to alter the actual rear wheel angle of the first pair of rear wheels to a means for controlling the actual rear wheel angle of the first pair of rear wheels if the actual rear wheel angle of the first pair of rear wheels differs from the desired rear wheel angle by an amount that is greater than a desired amount,

the controller means sending a signal to alter the actual rear wheel angle of the second pair of rear wheels to a means for controlling the actual rear wheel angle of the second pair of rear wheels if the actual rear wheel angle of the second pair of rear wheels differs from the desired rear wheel angle by an amount that is greater than a desired amount.

8. An all wheel steering system for a vehicle having front wheels with a front wheel angle, rear wheels with a rear wheel angle, and a steering wheel, the front wheel angle being determined by an operator positioning the steering wheel, the rear wheel angle being determined by the system, the system comprising:

means for sensing a front wheel angle of at least one front wheel,

means for communicating the front wheel angle to a controller means, the controller means including a memory containing at least one desired rear wheel angle for each front wheel angle, the desired rear wheel angle being dependant upon the front wheel angle and being limited by a maximum rear wheel angle, the maximum rear wheel angle being a variable and being dependant upon vehicle speed, the maximum rear wheel angle ranging from +/-30°

for slow speeds not exceeding 10 mph to 0°

for high speeds exceeding 40 mph, the controller means retrieving a desired rear wheel angle based on the front wheel angle from the memory of the controller means,

means for sensing an actual rear wheel angle of at least one rear wheel,

means for communicating the actual rear wheel angle to the controller means,

the controller means comparing the actual rear wheel angle with the desired rear wheel angle, the controller means sending a signal to alter the actual rear wheel angle to a means for controlling the actual rear wheel angle if the actual rear wheel angle differs from the desired rear wheel angle by an amount that is greater than a desired amount.

9. The system of claim 8,

further including a means for locking all rear wheels in a straight-ahead position if an operating component of the system fails.

10. The system of claim 8,

further including a means for locking all rear wheels in their current position if an operating component of the system fails.

11. The system of claim 8,

further including a manual switching means for selecting from a plurality of all-wheel, front-wheel and rear wheel steering modes.

12. The system of claim 11,

wherein the steering modes are further characterized as

a front wheel only steering mode in which the desired rear wheel angle is fixed in a straight-ahead position,

a second all-wheel steering mode in which the desired rear wheel angle is generally opposite in direction to that of the front wheel angle, and

a third all-wheel steering mode in which the desired rear wheel angle is generally of a same direction as that of the front wheel angle.

13. The system of claim 12,

wherein the all-wheel steering modes further include a fourth rear wheel steering mode in which the desired rear wheel angle may be controlled independently of the front wheel angle.

14. The system of claim 8,

wherein the vehicle includes a first rear axle and a second rear axle, a first pair of rear wheels being mounted on opposing sides of the first rear axle, a second pair of rear wheels being mounted on opposing sides of the second rear axle, sensor means for measuring the rear wheel angle of at least one rear wheel of the first pair or rear wheels, sensor means for measuring the rear wheel angle of at least one rear wheel of the second pair of rear wheels,

means for communicating the actual rear wheel angle of the first pair of rear wheels to the controller means, means for communicating the actual rear wheel angle of the second pair of rear wheels to the controller means,

the controller means sending a signal to alter the actual rear wheel angle of the first pair of rear wheels to a means for controlling the actual rear wheel angle of the first pair of rear wheels if the actual rear wheel angle of the first pair of rear wheels differs from the desired rear wheel angle by an amount that is greater than a desired amount,

the controller means sending a signal to alter the actual rear wheel angle of the second pair of rear wheels to a means for controlling the actual rear wheel angle of the second pair of rear wheels if the actual rear wheel angle of the second pair of rear wheels differs from the desired rear wheel angle by an amount that is greater than a desired amount.

15. An all wheel steering system for a vehicle having a pair of front wheels and at least one pair of rear wheels, the front and rear wheels being steerable, the system comprising:

means for sensing a front wheel angle of at least one front wheel,

means for communicating the front wheel angle to a controller means, the controller means including a memory,

means for sensing the speed of the vehicle,

means for communicating the speed of the vehicle to the controller,

the memory of the controller means containing at least one desired rear wheel angle for each front wheel angle for each speed of the vehicle, the controller means retrieving a desired rear wheel angle based on the front wheel angle and the speed from the memory of the controller means, the desired rear wheel angles being dependant upon the speed of the vehicle and the front wheel angle when the front wheel angle exceeds a dead band value ranging from 3°

to 15°

, the desired rear wheel angle is 0°

when the front wheel angle does not exceed the dead band value regardless of vehicle speed,

means for sensing an actual rear wheel angle of at least one rear wheel,

means for communicating the actual rear wheel angle to the controller means,

decelerator means for detecting deceleration of the vehicle, the decelerator means sending an alarm signal to the controller means when the vehicle decelerates at a rate greater than a predetermined value, the controller means setting the desired rear wheel angle to 0°

when an alarm signal is received from the decelerator means,

the controller means comparing the actual rear wheel angle with the desired rear wheel angle, the controller means sending a signal to alter the actual rear wheel angle to a means for controlling the actual rear wheel angle if the actual rear wheel angle differs from the desired rear wheel angle by an amount greater than a desired amount.

16. The system of claim 15,

wherein the deceleration means is an anti-lock braking system wheel position sensor.

17. The system of claim 15,

further including a means for locking all rear wheels in a straight-ahead position if an operating component of the system fails.

18. The system of claim 15,

further including a means for locking all rear wheels in their current position if an operating component of the system fails.

19. The system of claim 15,

further including a manual switching means for selecting from a plurality of all-wheel, front-wheel and rear wheel steering modes.

20. The system of claim 19,

wherein the steering modes are further characterized as

a front wheel only steering mode in which the desired rear wheel angle is fixed in a straight-ahead position,

a second all-wheel steering mode in which the desired rear wheel angle is generally opposite in direction to that of the front wheel angle, and

a third all-wheel steering mode in which the desired rear wheel angle is generally of a same direction as that of the front wheel angle.

21. The system of claim 20,

wherein the all-wheel steering modes further include a fourth rear wheel steering mode in which the desired rear wheel angle may be controlled independently of the front wheel angle.

22. The system of claim 15,

wherein the vehicle includes a first rear axle and a second rear axle, a first pair of rear wheels being mounted on opposing sides of the first rear axle, a second pair of rear wheels being mounted on opposing sides of the second rear axle, sensor means for measuring the rear wheel angle of at least one rear wheel of the first pair or rear wheels, sensor means for measuring the rear wheel angle of at least one rear wheel of the second pair of rear wheels,

means for communicating the actual rear wheel angle of the first pair of rear wheels to the controller means, means for communicating the actual rear wheel angle of the second pair of rear wheels to the controller means,

the controller means sending a signal to alter the actual rear wheel angle of the first pair of rear wheels to a means for controlling the actual rear wheel angle of the first pair of rear wheels if the actual rear wheel angle of the first pair of rear wheels differs from the desired rear wheel angle by an amount that is greater than a desired amount,

the controller means sending a signal to alter the actual rear wheel angle of the second pair of rear wheels to a means for controlling the actual rear wheel angle of the second pair of rear wheels if the actual rear wheel angle of the second pair of rear wheels differs from the desired rear wheel angle by an amount that is greater than a desired amount.

23. An all wheel steering system for a tractor-trailer rig, the tractor having at least one pair of front wheels with a front wheel angle, the tractor also including a steering wheel, the trailer having a first and second pairs of rear wheels that are steerable, the first pair of rear wheels having a first rear wheel angle, the second pair of rear wheels having a second rear wheel angle, the front wheel angle of the tractor being determined by an operator positioning the steering wheel, the first and second rear wheel angles being determined by the system, the system comprising:

means for sensing a front wheel angle of at least one front wheel,

means for communicating the front wheel angle to a controller means, the controller means including a memory containing at least one desired first rear wheel angle for each front wheel angle and at least one desired second rear wheel angle for each front wheel angle, the controller means retrieving a desired first rear wheel angle and a desired second rear wheel angle based on the front wheel angle from the memory of the controller means,

means for sensing an actual first rear wheel angle of at least one rear wheel of the first pair of rear wheels,

means for communicating the actual first rear wheel angle to the controller means,

means for sensing an actual second rear wheel angle of at least one rear wheel of the second pair of rear wheels,

means for communicating the actual second rear wheel angle to the controller means,

the controller means comparing the actual first rear wheel angle with the desired first rear wheel angle, the controller means sending a signal to alter the actual first rear wheel angle to a means for controlling the actual first rear wheel angle if the actual first rear wheel angle differs from the desired first rear wheel angle by an amount that is greater than a desired amount,

the controller means comparing the actual second rear wheel angle with the desired second rear wheel angle, the controller means sending a signal to alter the actual second rear wheel angle to a means for controlling the actual second rear wheel angle if the actual second rear wheel angle differs from the desired second rear wheel angle by an amount that is greater than a desired amount.

24. The system of claim 23,

wherein the desired first and second rear wheel angles being dependant upon the front wheel angle when the front wheel angle exceeds a dead band value ranging from 3°

to 15°

, the desired first and second rear wheel angles are both 0°

when the front wheel angle does not exceed the dead band value regardless of vehicle speed.

25. The system of claim 23,

wherein the desired first and second rear wheel angles are dependant upon the front wheel angle, the desired first and second rear wheel angles having an absolute value greater than 0°

when the front wheel angle exceeds a dead band value, the dead band value being a variable ranging from 0°

for slow speeds not exceeding 10 mph to 30°

for high speeds exceeding 40 mph, the desired first and second rear wheel angles are both 0°

when the front wheel angle does not exceed the dead band value.

26. The system of claim 23,

the desired first rear wheel angle being dependant upon the front wheel angle and being limited by a maximum first rear wheel angle, the maximum first rear wheel angle being a variable and being dependant upon vehicle speed, the maximum first rear wheel angle ranging from +/-30°

for slow speeds not exceeding 10 mph to 0°

for high speeds exceeding 40 mph;

the desired second rear wheel angle being dependant upon the front wheel angle and being limited by a maximum second rear wheel angle, the maximum second rear wheel angle being a variable and being dependant upon vehicle speed, the maximum second rear wheel angle ranging from +/-30°

for slow speeds not exceeding 10 mph to 0°

for high speeds exceeding 40 mph.

27. The system of claim 23,

wherein the controller means delays sending a signal to alter the actual first and second rear wheel angles to means for controlling the actual first and second rear wheel angle to accommodate for the length of the trailer.

28. The system of claim 23,

further comprising decelerator means for detecting deceleration of the vehicle, the decelerator means sending an alarm signal to the controller means when the vehicle decelerates at a rate greater than a predetermined value, the controller means setting the desired first and second rear wheel angles to 0°

when an alarm signal is received from the decelerator means.

29. An all wheel steering system for a vehicle having front wheels with a front wheel angle, rear wheels with a rear wheel angle, and a steering wheel, the front wheel angle being determined by an operator positioning the steering wheel, the rear wheel angle being determined by the system, the system comprising:

means for sensing a front wheel angle of at least one front wheel,

means for communicating the front wheel angle to a controller means, the controller means including a memory containing at least one desired rear wheel angle for each front wheel angle, the desired rear wheel angle being dependant upon the front wheel angle, the desired rear wheel angle having an absolute value greater than 0°

when the front wheel angle exceeds a dead band value,

the dead band value ranging from about 45°

to about 5°

for a low speed range,

the dead band value ranging from about 5°

to about 10°

for a moderate speed range which exceeds said low speed range,

the dead band value ranging from about 5°

to about 45°

for a high speed range which exceeds said moderate speed range,

the desired rear wheel angle is 0°

when the front wheel angle does not exceed the dead band value, the controller means retrieving a desired rear wheel angle based on the front wheel angle from the memory of the controller means,

means for sensing an actual rear wheel angle of at least one rear wheel,

means for communicating the actual rear wheel angle to the controller means,

the controller means comparing the actual rear wheel angle with the desired rear wheel angle, the controller means sending a signal to alter the actual rear wheel angle to a means for controlling the actual rear wheel angle if the actual rear wheel angle differs from the desired rear wheel angle by an amount that is greater than a desired amount.

30. The system of claim 29,

wherein the low speed range is further defined as ranging from 0 mph to about 10 mph.

31. The system of claim 30,

wherein the moderate speed range is further defined as ranging from about 3 mph or in excess of the maximum speed of the low speed range, whichever is greater, to about 25 mph.

32. The system of claim 31,

wherein the high speed range is further defined as ranging from about 15 mph or in excess of the maximum speed of the moderate speed range, whichever is greater, to about 40 mph.

33. An all wheel steering system for a vehicle having front wheels with a front wheel angle, rear wheels with a rear wheel angle, and a steering wheel, the front wheel angle being determined by an operator positioning the steering wheel, the rear wheel angle being determined by the system, the system comprising:

means for sensing a front wheel angle of at least one front wheel,

means for communicating the front wheel angle to a controller means, the controller means including a memory containing at least one desired rear wheel angle for each front wheel angle, the desired rear wheel angle being dependant upon the front wheel angle, the desired rear wheel angle having an absolute value greater than 0°

when the front wheel angle exceeds a dead band value,

the dead band value ranging from 0°

to 5°

for slow speeds not exceeding 10 mph, the desired rear wheel angle is 0°

when the front wheel angle does not exceed the dead band value, the controller means retrieving a desired rear wheel angle based on the front wheel angle from the memory of the controller means,

means for sensing an actual rear wheel angle of at least one rear wheel,

means for communicating the actual rear wheel angle to the controller means,

the controller means comparing the actual rear wheel angle with the desired rear wheel angle, the controller means sending a signal to alter the actual rear wheel angle to a means for controlling the actual rear wheel angle if the actual rear wheel angle differs from the desired rear wheel angle by an amount that is greater than a desired amount.

34. An all wheel steering system for a vehicle having front wheels with a front wheel angle, rear wheels with a rear wheel angle, and a steering wheel, the front wheel angle being determined by an operator positioning the steering wheel, the rear wheel angle being determined by the system, the system comprising:

means for sensing a front wheel angle of at least one front wheel,

means for communicating the front wheel angle to a controller means, the controller means including a memory containing at least one desired rear wheel angle for each front wheel angle, the desired rear wheel angle being dependant upon the front wheel angle,

the desired rear wheel angle having an absolute value greater than 0°

when the front wheel angle exceeds a dead band value, the desired rear wheel angle is 0°

when the front wheel angle does not exceed the dead band value,

the controller means retrieving a desired rear wheel angle based on the front wheel angle from the memory of the controller means,

means for sensing an actual rear wheel angle of at least one rear wheel,

means for communicating the actual rear wheel angle to the controller means,

the controller means comparing the actual rear wheel angle with the desired rear wheel angle, the controller means sending a signal to alter the actual rear wheel angle to a means for controlling the actual rear wheel angle if the actual rear wheel angle differs from the desired rear wheel angle by an amount that is greater than a desired amount.