Hybrid Steering System
First Claim
1. A steering system for a vehicle, the system including a steering control for an operator to effect mechanical steering of the vehicle, the steering control being mechanically connected via a mechanical steering train, to at least one steerable ground engaging wheel, there being a power assistor apparatus for power assisting the mechanical steering of the vehicle when the operator operates the steering control, and the system including a hydraulic steering actuator which is operated by an electronically controlled hydraulic steering control valve to effect hydraulic power steering of the vehicle independently of the operation of the steering control, the electronically controlled hydraulic steering control valve being operable in response to signals from an electronic controller, the hydraulic steering actuator being supplied in use, with pressurised hydraulic fluid from a supply valve arrangement, there being a sensor device to sense when the steering control is operated and to provide an input to the electronic controller, the controller disabling the hydraulic power steering in response.
1 Assignment
0 Petitions
Accused Products
Abstract
A steering system for a vehicle comprising a steering control to effect mechanical steering of the vehicle, the steering control being mechanically connected via a mechanical steering train, to at least one steerable ground engaging wheel. A power assistor apparatus is present for power assisting the mechanical steering of the vehicle when the operator operates the steering control. The system includes a hydraulic steering actuator which is operable by an electronically controlled hydraulic steering control valve to effect hydraulic power steering of the vehicle independently of the operation of the steering control. The electronically controlled hydraulic steering control valve is operable in response to signals from an electronic controller, the hydraulic steering actuator being supplied with pressurised hydraulic fluid from a supply valve arrangement. A sensor device detects when the steering control is operated and provides input to the electronic controller, the controller disabling the hydraulic power steering in response.
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Citations
13 Claims
- 1. A steering system for a vehicle, the system including a steering control for an operator to effect mechanical steering of the vehicle, the steering control being mechanically connected via a mechanical steering train, to at least one steerable ground engaging wheel, there being a power assistor apparatus for power assisting the mechanical steering of the vehicle when the operator operates the steering control, and the system including a hydraulic steering actuator which is operated by an electronically controlled hydraulic steering control valve to effect hydraulic power steering of the vehicle independently of the operation of the steering control, the electronically controlled hydraulic steering control valve being operable in response to signals from an electronic controller, the hydraulic steering actuator being supplied in use, with pressurised hydraulic fluid from a supply valve arrangement, there being a sensor device to sense when the steering control is operated and to provide an input to the electronic controller, the controller disabling the hydraulic power steering in response.
- 8. A steering system for a vehicle, the system including an axle, the axle including a body connected to a main structure of the vehicle, the axle body carrying at each end a hub for a wheel, each of the hubs being pivotally connected to the axle body to effect steering, there being a mechanical steering train from each of the hubs to a steering control whereby the wheels are mechanically connected to the steering control, and the system including a power assistor apparatus to power assist mechanical steering effected by using the steering control, the power assistor apparatus including an assistor actuator which is pivotally connected at each end to either the pair of hubs, or to one of the hubs and to the axle, and the system further including a hydraulic steering actuator which is connected between either the pair of hubs, or to one of the hubs and to the axle, for effecting hydraulic steering of the vehicle, and the system including a supply valve arrangement to supply pressurised hydraulic fluid to the hydraulic power assistor apparatus during mechanical steering and to the hydraulic steering actuator during hydraulic steering.
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13. A method of operating a steering system, the steering system including a steering control for an operator to effect mechanical steering of the vehicle, the steering control being mechanically connected via a mechanical steering train, to at least one steerable ground engaging wheel, there being a power assistor apparatus for power assisting the mechanical steering of the vehicle when the operator operates the steering control, and the system including a hydraulic steering actuator which is operated by an electronically controlled hydraulic steering control valve to effect hydraulic power steering of the vehicle independently of the operation of the steering control, the electronically controlled hydraulic steering control valve being operable in response to signals from an electronic controller, the hydraulic steering actuator being supplied in use, with pressurised hydraulic fluid from a supply valve arrangement, there being a sensor device to sense when the steering control is operated and to provide an input to the electronic controller, the method including effecting hydraulic power steering of the vehicle by operating the electronically controlled hydraulic steering control valve with the electronic controller, sensing operation of the steering control with the sensor device, and disabling hydraulic power steering in response to the signal from the sensor device which indicates that the steering control has been operated.
Specification