Trailer and steerable wheels therefor

• US 5,244,226 A
• Filed: 09/23/1991
• Issued: 09/14/1993
• Est. Priority Date: 09/23/1991
• Status: Expired due to Fees

• Current Assignee: Bergh C. John
• Original Assignee: Bergh C. John
• Inventors: Bergh, C. John
• Primary Examiner(s): Focarino, Margaret A.
• Assistant Examiner(s): ZEENDER, FLORIAN M
• Application Number:
  US07/763,608
• Time in Patent Office: 722 Days
• Field of Search: 280/426, 280/442, 280/443, 280/444, 280/445, 280/432, 180/132, 180/141, 180/142
• US Class Current: 280/442
• CPC Class Codes: B62D 13/04 for individually-pivoted wheels

Abstract

A two wheeled trailer is provided with steerable wheels which are hydraulically actuatable according to the articulation angle between the trailer and a towing vehicle and to the forward and reverse mode of travel of these vehicles. In one embodiment, the angle to which the wheels are steered in response to the detected articulation angle may be less for forward travel than for reverse. Also, the wheels may be caused to assume a substantially straight ahead, non-steering configuration at forward speeds above a particular set point, with the steering automatically resumable upon lowering of the speed below another set point. Still another embodiment provides for steering of the wheels, whenever there is a transition between forward and reverse and an articulation angle exists, in a manner that prevents "crabbing" of the trailer relative to the towing vehicle.

Claims

1. A method of steering the wheels of a two wheel trailer, and comprising the steps of:

monitoring an angle of articulation in magnitude and sense between said trailer and a towing vehicle and generating articulation angle signals in response thereto;

monitoring an angle of wheel steering in magnitude and sense relative to an axle of said trailer and generating wheel steering angle signals in response thereto;

computing values of said articulation angle as a percentage of a range of articulation to either side of 0°

, in response to said articulation angle signals;

computing values of said wheel steering angle as a percentage of a range of steering to either side of 0°

in response to said wheel steering angle signals;

comparing said articulation percentage values with said wheel steering percentage values and generating a correction signal whenever said articulation and steering percentage values are not of equal magnitude; and

turning said wheels in response to said correction signal to adjust said wheel steering angle, whenever said articulation percentage value and said wheel steering percentage value are not equal in magnitude, in order to make said percentage values equal.

2. The method as in claim 1, and further comprising the steps of:

sensing transitions between forward and reverse modes of travel of said trailer and generating transition signals in response thereto; and

for each of said transitions, changing said wheel steering angle, in response to said transition signals, from a pretransition angle other than 0°

to a post-transition angle which is equal to said pretransition angle in magnitude and opposite to said pretransition angle in sense.

3. A method of steering the wheels of a two wheel trailer, and comprising the steps of:

detecting an articulation angle between said trailer and a towing vehicle;

steering said wheels by changing a wheel steering angle automatically according to changes in said articulation angle;

identifying forward and rearward directions of travel of said trailer;

providing a fluid circuit having a motive fluid for effecting said steering in response to said detecting and for interconnecting said angle detecting and said steering via said circuit;

providing a valve for controlling a direction of flow of said motive fluid; and

controlling routing of said motive fluid through said circuit via said directional control valve and automatically according to each of said directions of travel so as to provide a particular sense of said wheel steering angle according to said direction of travel.

4. A method as in claim 3, and further comprising the steps of:

providing that said wheel steering angle has the same sense as said articulation angle when said direction of travel is forward and is opposite in sense when said direction of travel is rearward.

5. A method as in claim 3, and further comprising the steps of:

providing that a ratio of wheel steering angle to articulation angle is greater in magnitude for said rearward travel than for said forward travel.

6. A method as in claim 3, and further comprising the steps of:

detecting speeds of travel of said trailer;

setting a high set point speed of travel; and

altering routing of said fluid via said valve when said direction of travel is forward and said high set point is detected so as to retain said wheels in a neutral mode of straight-away orientation at speeds above said high set point.

7. A method as in claim 6, and further comprising the steps of:

setting a low set point speed of travel; and

realtering routing of said fluid via said valve when said speed decreases and said low set point is detected so as to release said wheels from retention in said neutral mode at speeds below said low set point.

8. A method as in claim 7, and further comprising the steps of:

providing that said high and low set points are set to speeds which are sufficiently different as to avoid constant cycling in and out of said neutral mode during a generally constant speed of travel of the trailer near either of said set points.

9. An apparatus for steering the wheels of a two wheel trailer, and comprising:

means for monitoring an angle of articulation in magnitude and sense between said trailer and a towing vehicle and generating articulation angle signals in response thereto;

means for monitoring an angle of wheel steering in magnitude and sense relative to an axle of said trailer and generating wheel steering angle signals in response thereto;

means for receiving said articulation angle signals and computing values of said articulation angle as a percentage of a range of articulation to either side of 0°

;

means for receiving said wheel steering angle signals and computing values of said wheel steering angle as a percentage of a range of steering to either side of 0°

;

means for comparing said articulation percentage values with said wheel steering percentage values and generating a correction signal whenever said articulation and wheel steering percentage values are not of equal magnitude; and

means, responsive to said correction signal, for turning said wheels to adjust said wheel steering angle, whenever said articulation percentage value and said wheel steering percentage value are not equal in magnitude, in order to make said percentage values equal.

10. An apparatus as in claim 9, and further comprising:

means for sensing transitions between forward and reverse modes of travel of said trailer;

means for generating transition signals in response to said sensing; and

for each of said transitions, means for changing said wheel steering angle, in response to said transition signals, from a pretransition angle other than 0°

to a post-transition angle which is equal to said pretransition angle in magnitude and opposite to said pretransition angle in sense.

11. An apparatus for steering the wheels of a two wheel trailer, and comprising:

means for detecting an articulation angle between said trailer and a towing vehicle;

means for steering said wheels by changing a wheel steering angle automatically according to changes in said articulation angle;

means for identifying forward and rearward directions of travel of said trailer;

a fluid circuit having a motive fluid for effecting said steering in response to said detecting and for interconnecting said angle detecting and said steering via said circuit;

valve means for controlling a direction of flow of said motive fluid; and

means for controlling routing of said motive fluid through said circuit via said valve means and automatically according to each of said directions of travel so as to provide a particular sense of said wheel steering angle according to said direction of travel.

12. An apparatus as in claim 11, and further comprising:

means for providing that said wheel steering angle has the same sense as said articulation angle when said direction of travel is forward and is opposite in sense when said direction of travel is rearward.

13. An apparatus as in claim 11, and further comprising:

means for providing that a ratio of wheel steering angle to articulation angle is greater in magnitude for said rearward travel than for said forward travel.

14. An apparatus as in claim 11, and further comprising:

means for detecting speeds of travel of said trailer;

means for setting a high set point speed of travel; and

means for altering routing of said fluid via said valve means when said direction of travel is forward and said high set point is detected so as to retain said wheels in a neutral mode of straight-away orientation at speeds above said high set point.

15. An apparatus as in claim 14, and further comprising:

means for setting a low set point speed of travel; and

means for realtering routing of said fluid via said valve means when said speed decreases and said low set point is detected so as to release said wheels from retention in said neutral mode at speeds below said low set point.

16. An apparatus as in claim 15, and further comprising:

means for setting said high and low set points to speeds which are sufficiently different as to avoid constant cycling in and out of said neutral mode during a generally constant speed of travel of the trailer near either of said set points.

17. An apparatus for steering the wheels of a two wheel trailer and comprising:

means for attaching said trailer to a towing vehicle such that said trailer is pivotal above yaw, pitch, and roll axes; and

means for converting movement of said trailer about said yaw axis into a motive force for said steering, said motive force being transmitted via a fluid; and

means for controlling said steering in response to and according to forward and reverse directions for travel of said trailer in order to accomplish said steering in forward and reverse directions of travel.

18. An apparatus as in claim 17, wherein said attaching means comprises:

a generally standard draw bar and hitch ball on said towing vehicle having a nonpivotal yoke attached laterally and perpendicularly to said draw bar, said yoke having pins situated on each side of said ball and on said pitch axis which passes through a center of said ball;

a tow bar attached at one end thereof to said trailer such that said trailer is rotatable about a longitudinal axis of said tow bar, said tow bar having a generally standard socket and latch at said other end for connection of said trailer to said hitch ball of said towing vehicle such that said longitudinal axis is coincident with said roll axis which passes through said center of said ball and said trailer is pivotal about said roll axis relative to said tow bar; and

a first bar affixed to said tow bar near said one end and extending laterally of said tow bar, and a second bar attached to said socket and being pivotal about said yaw axis which passes through said center of said ball, said second bar having means engagable with said pins of said yoke such that said second bar pivots about said yaw axis in concert with said yoke and about said pitch axis relative to said yoke.

19. An apparatus as in claim 18, wherein said converting means comprises:

actuator means attached to and extending between corresponding ends of said first and second bars and being pivotal relative to said second bar;

steering means operatively attached to said wheels and interactive with said actuator means such that pivoting of said second bar is transferred to said wheels via said steering means.

20. An apparatus as in claim 19, and further comprising:

a hydraulic circuit interconnecting said actuator means and said steering means, wherein said actuator means comprises hydraulic cylinders which expand and contract according to articulation of said trailer about said yaw axis and displace fluid of said hydraulic circuit to and from an hydraulic cylinder as part of said steering means.

21. An apparatus as in claim 17, wherein said controlling means comprises:

flow control valve means for routing flow of said fluid according to said forward and reverse directions for travel of said trailer; and

means for detecting and differentiating between forward and reverse directions of travel for said trailer and controlling said flow control valve means accordingly.