Steering control system for articulated vehicle
First Claim
1. An improved steering system for an articulated vehicle of the type having first and second frame portions, at least one axle mounted for wagon-wheel steering with respect to one of the frame portions, first power means for pivoting the wagon-wheel axle with respect to its frame portion and second power means for causing articulation of the two frame postions, the improvement comprising:
- axle sensor means for providing a first signal indicative of the degree of wagon-wheel axle pivot relative to its frame portion;
articulation sensor means for providing a second signal indicative of the degree of articulation of the frame portions;
operator controlled steering means for providing a third signal indicative of a desired direction of vehicle travel;
first rate means for providing a fourth signal indicative of the rate of pivoting of the wagon-wheel axle relative to its frame portion;
second rate means for providing a fifth signal indicative of the rate of articulation of the frame portions; and
steering control means for controlling the operation of the first and second power means in response to the first, second, third, fourth and fifth signals.
7 Assignments
0 Petitions
Accused Products
Abstract
The present invention is a steering system for an articulated vehicle which has at least one axle mounted for wagon-wheel steering with respect to the vehicle, a hydraulic actuator for pivoting the axle with respect to the vehicle and a pair of hydraulic actuators for causing articulation of the vehicle. The improved steering system includes sensors for providing signals dependent on the degree of axle pivot relative to the vehicle, the degree of articulation of the vehicle and the desired direction of the vehicle travel. These signals are detected by a controller which in turn controls actuation of the axle and articulation hydraulic actuators. The actuators are operated in a sequential manner so that small directional changes of the vehicle are achieved solely through pivoting of the axle. Operation of the axle and articulation actuators are controlled through manipulation of a hydraulic fluid diverting valve, with the timing and duration of valve actuation being controlled by the controller as a function of various dynamic turning parameters of the vehicle and the response time of the valve.
38 Citations
20 Claims
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1. An improved steering system for an articulated vehicle of the type having first and second frame portions, at least one axle mounted for wagon-wheel steering with respect to one of the frame portions, first power means for pivoting the wagon-wheel axle with respect to its frame portion and second power means for causing articulation of the two frame postions, the improvement comprising:
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axle sensor means for providing a first signal indicative of the degree of wagon-wheel axle pivot relative to its frame portion; articulation sensor means for providing a second signal indicative of the degree of articulation of the frame portions; operator controlled steering means for providing a third signal indicative of a desired direction of vehicle travel; first rate means for providing a fourth signal indicative of the rate of pivoting of the wagon-wheel axle relative to its frame portion; second rate means for providing a fifth signal indicative of the rate of articulation of the frame portions; and steering control means for controlling the operation of the first and second power means in response to the first, second, third, fourth and fifth signals. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A steering system for an articulated vehicle comprising:
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a wagon-wheel axle pivotally mounted on the vehicle thereby enabling the vehicle to be steered in a wagon-wheel steer mode where at least selected small changes to the direction of vehicle travel may be made solely by steering movement of the axle; first hydraulic actuator means connected the axle and vehicle for producing steering movement of the axle relative to the vehicle; axle sensor means for providing a first signal indicative of the degree of wagon-wheel axle pivot relative to the vehicle; second hydraulic actuator means mounted on the vehicle for producing articulation of the vehicle; articulation sensor means for providing a second signal indicative of the degree of articulation of the vehicle; manual steering control means for selectively controlling the direction of vehicle travel through actuation of the first and second hydraulic actuator means, said steering control means including hydraulic steering valve means for providing a third signal indicative of the manually selected direction of vehicle travel, said third signal being pressurized hydraulic fluid flow from the hydraulic steering valve means; and system control means for controlling when the first and second hydraulic actuator means may be operated, the system control means being responsive to at least said first and second signals and including electrically operated hydraulic control valve means disposed between and in hydraulic fluid communication with the manual steering control means and the first and second hydraulic actuator means, for actuating the first and second hydraulic actuator means sequentially, said system control means being arranged so that sufficiently small manually-selected directional changes from a straight-ahead vehicle direction are accomplished solely through steering movement of the wagon-wheel axle by the first hydraulic actuator means, without requiring actuation of the second hydraulic actuator means. - View Dependent Claims (8)
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9. An improved steering control system for an articulated vehicle of the type having an articulation steering mode wherein first and second frame portions of the vehicle are articulated by first hydraulic actuator means to steer the vehicle, and having an axle steering mode wherein at least one axle is mounted to one of the frame portions and pivotable relative thereto by second hydraulic actuator means to steer the vehicle, the improvement comprising:
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valve means for switching from one steering mode to the other steering mode and vice versa by selectively controlling the operation of the first and second hydraulic actuator means; means for detecting the difference between the actual articulation position of the frame portions and a desired articulation position thereof; means for detecting the rate of articulation movement of the first and second frame portions; means for detecting the direction of articulation movement of the first and second frame portions; means for detecting the difference between the actual position of the axle relative to its frame portion and a desired position of the axle relative to its frame portion; means for detecting the rate of pivoting of the axle with respect to its frame portion; means for detecting the direction of the pivoting of the axle with respect to its frame portion; and means for controlling the timing of the operation of the valve means to switch from one steering mode to the other steering mode or vice versa as a function of the detected difference between the actual and desired frame portion articulation positions, the detected rate and direction of articulation movement, the detected difference between the actual and desired axle positions, the detected rate and direction of pivoting of the axle, and the response time characteristics of the valve means. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. An improved steering system for an articulated vehicle of the type having first and second frame portions, at least one axle mounted for pivotable steering with respect to one of the frame portions, first power means for pivoting the axle with respect to one of the frame portions and including at least one hydraulic actuator connected between the axle and its frame portion, and second power means for causing articulation of the two frame portions including at least one hydraulic actuator connected between the two frame portions, the improvement comprising:
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axle sensor means for providing a first signal indicative of the degree of axle pivot relative to its frame portion; articulation sensor means for providing a second signal indicative of the degree of articulation of the frame portions; operator controlled steering means for providing a third signal indicative of a desired direction of vehicle travel, said steering means including electrically operated sensor means for detecting rotation of an operator rotatable steering member of the vehicle and producing the third signal which is also indicative of the rotational position of the steering member; and steering control means for controlling the operation of the first and second power means in response to the first, second and third signals, said steering control means including electrically operated hydraulic valve means disposed between a source of pressurized hydraulic fluid and the hydraulic actuators for directing hydraulic fluid from the source to the hydraulic actuator of the first power means and to the hydraulic actuator of the second power means. - View Dependent Claims (18, 19, 20)
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Specification