Electro-hydraulic steering system for an articulated vehicle

Abstract

The present invention provides an electro-hydraulic steering system for an articulated vehicle having a front frame and a rear frame. The system includes a controller and a hydraulic steering system having a pump for providing hydraulic pressure. A steering input control, typically a steering wheel, transmits mechanical steering inputs to the hydraulic steering system. A pair of articulation cylinders rotate the front frame with respect to the rear frame in response to hydraulic pressure to steer the vehicle. Position sensors transmit input signals to the controller indicating the position of the steering input control and each of the articulation cylinders. An electro-hydraulic valve receives electrical control signals from the controller to control the hydraulic pressure to each articulation cylinder. In this manner, the present invention can perform steering performance enhancements, such as snubbing, steering jerk limit control, and electronic steering adjustment.

I claim: 
     
       1. An electro-hydraulic steering system for an articulated vehicle having a front frame and a rear frame, the system comprising: a controller;   a hydraulic steering system including a pump for providing hydraulic pressure;   a steering input control for transmitting mechanical steering inputs to said steering system;   at least one articulation cylinder for rotating the front frame with respect to the rear frame in response to hydraulic pressure to steer the vehicle;   position sensors for transmitting input signals to said controller indicating the position of said steering input control and each of said articulation cylinders; and   an electro-hydraulic valve for receiving electrical control signals from said controller to control the hydraulic pressure to each articulation cylinder.   
     
     
       2. The steering system as set forth in claim 1, wherein said at least one articulation cylinder has an extended end position and a retracted end position and wherein said controller detects movement of said at least one articulation cylinder approaching one of said end positions and transmits electrical control signals to said electro-hydraulic valve to prevent an abrupt halt in the movement of said at least one articulation cylinder. 
     
     
       3. The steering system as set forth in claim 1, wherein said controller detects an abrupt change in the position of said steering input control and transmits electrical control signals to said electro-hydraulic valve to prevent an abrupt change in the control of hydraulic pressure to said at least one articulation cylinder. 
     
     
       4. The steering system as set forth in claim 1, wherein said controller monitors the position of said steering input control and transmits electrical control signals to said electro-hydraulic valve to match the position of said at least one articulation cylinder with the position of said steering input control. 
     
     
       5. A steering enhancing system for a vehicle, said system comprising: a operator controlled steering input control for changing the direction of said vehicle;   a steering mechanism responsive to said steering input control for changing the direction of said vehicle, said steering mechanism including at least one hydraulic cylinder operatively connected to said steering input control;   sensors operatively connected to said steering input control and said at least one hydraulic cylinder; and   a computer control interconnected to said sensors and said hydraulic cylinder, said sensor sending signals to said computer control from said steering input control and said hydraulic cylinder; said computer control evaluating said signals and controlling said hydraulic cylinder based upon said signals to enhance the steering of said vehicle.   
     
     
       6. The steering enhancement system as set forth in claim 5, wherein at least one hydraulic cylinder extends to fully extended and fully retracted positions and wherein said computer control receives said signals from said sensor as said hydraulic cylinder approaches either of said fully extended or retracted positions, said computer control preventing an abrupt extension to either of said fully extended or fully retracted positions. 
     
     
       7. The steering enhancement system as set forth in claim 5, further including an electro-hydraulic unit interconnected between said computer control and said at least one hydraulic cylinder, said electro-hydraulic unit controlling said at least one hydraulic cylinder in response to said computer control. 
     
     
       8. The steering enhancement system as set forth in claim 6, further including an electro-hydraulic unit interconnected between said computer control and said at least one hydraulic cylinder, said electro-hydraulic unit controlling said at least one hydraulic cylinder in response to said computer control. 
     
     
       9. The steering enhancement system as set forth in claim 5, wherein said sensor detects abrupt changes at said steering input control and signals said computer control to override said steering mechanism and prevent any abrupt change of said at least one hydraulic cylinder. 
     
     
       10. The steering enhancement system as set forth in claim 9, further including an electro-hydraulic unit interconnected between said computer control and said at least one hydraulic cylinder, said electro-hydraulic unit controlling said at least one hydraulic cylinder in response to said computer control. 
     
     
       11. The steering enhancement system as set forth in claim 7, wherein said computer control monitors the position of said steering input control and transmits electrical control signals to said electro-hydraulic unit to match the position of said at least one hydraulic cylinder with the position of said steering input control. 
     
     
       12. An electro-hydraulic steering system for an articulated vehicle having a front frame and a rear frame, the system comprising: a controller;   a hydraulic steering system including a pump;   a steering input control;   at least one articulation cylinder;   position sensors that transmit input signals to said controller; and   an electro-hydraulic valve that receives electrical control signals from said controller and controls pressure to said at least one articulation cylinder.   
     
     
       13. A steering enhancing system for a vehicle, said system comprising: a operator-controlled steering input control;   a steering mechanism responsive to said steering input control, said steering mechanism including at least one hydraulic cylinder operatively connected to said steering input control;   sensors operatively connected to said steering input control and said at least one hydraulic cylinder; and   a computer control interconnected to said sensors and said hydraulic cylinder.   
     
     
       14. A computer-controlled method of electro-hydraulic steering for an articulated vehicle having a front frame and a rear frame, the method comprising the steps of: providing hydraulic pressure for a hydraulic steering system;   transmitting mechanical steering inputs from a steering input control to said steering system;   rotating said front frame with respect to said rear frame with at least one hydraulic articulation cylinder to steer said vehicle;   transmitting input signals from position sensors to a computer-implemented controller for indicating the position of said steering input control and said at least one hydraulic articulation cylinder;   processing said input signals with said computer-implemented controller; and   transmitting electrical control signals from said computer-implemented controller to an electro-hydraulic valve for controlling hydraulic pressure to said at least one hydraulic articulation cylinder.   
     
     
       15. The computer-controlled electro-hydraulic steering method as set forth in claim 14, further comprising the steps of detecting movement of said at least one hydraulic articulation cylinder approaching one of either a fully extended position or a fully retracted position and transmitting electrical control signals to said electro-hydraulic valve to prevent an abrupt halt in the movement of said at least one hydraulic articulation cylinder. 
     
     
       16. The computer-controlled electro-hydraulic steering method as set forth in claim 14, further comprising the steps of detecting an abrupt change in the position of said steering input control and transmitting electrical control signals to said electro-hydraulic valve to prevent an abrupt change in the hydraulic pressure to said at least one hydraulic articulation cylinder. 
     
     
       17. The computer-controlled electro-hydraulic steering method as set forth in claim 14, further comprising the steps of monitoring the position of said steering input control and transmitting electrical control signals to said electro-hydraulic valve to match the position of said at least one hydraulic articulation cylinder with the position of said steering input control. 
     
     
       18. A computer-controlled method for enhancing the steering of a vehicle, comprising the steps of: inputting steering control for changing the direction of said vehicle;   responding to said input steering control to change direction of said vehicle with a steering mechanism;   sending first signals from sensors responsive to said input steering control;   sending second signals from sensors operatively connected to at least one hydraulic cylinder;   receiving said first and second signals at a computer-implemented controller;   evaluating said first and second signals by said computer-implemented controller; and   controlling said at least one hydraulic cylinder based upon said first and second signals to enhance the steering of said vehicle.   
     
     
       19. The computer-controlled enhanced steering method as set forth in claim 18, further comprising the steps of receiving at a computer-implemented controller said second signals from said sensors as said at least one hydraulic cylinder approaches either a fully extended or a fully retracted position and preventing an abrupt extension or retraction of said at least one hydraulic cylinder to either of said fully extended or fully retracted position, respectively. 
     
     
       20. The computer-controlled enhanced steering method as set forth in claim 18, further comprising the step of controlling, in response to said computer-implemented controller, said at least one hydraulic cylinder with an electro-hydraulic unit interconnected between said computer-implemented controller and said at least one hydraulic cylinder. 
     
     
       21. The computer-controlled enhanced steering method as set forth in claim 19, further comprising the step of controlling, in response to said computer-implemented controller, said at least one hydraulic cylinder with an electro-hydraulic unit interconnected between said computer-implemented controller and said at least one hydraulic cylinder. 
     
     
       22. The computer-controlled enhanced steering method as set forth in claim 18, further comprising the steps of detecting abrupt changes of said input steering control and signaling said computer-implemented controller to override said steering mechanism to prevent any abrupt change of said at least one hydraulic cylinder. 
     
     
       23. The computer-controlled enhanced steering method as set forth in claim 22, further comprising the step of controlling, in response to said computer-implemented controller, said at least one hydraulic cylinder with an electro-hydraulic unit interconnected between said computer-implemented controller and said at least one hydraulic cylinder. 
     
     
       24. The computer-controlled enhanced steering method as set forth in claim 20, further comprising the steps of monitoring said input steering control and transmitting electrical control signals to said electro-hydraulic unit to match the position of said at least one hydraulic cylinder with said input steering control.