Full hydraulic power steering system
AssigneeNissan Motor Co., Ltd.
InventorTakashi Hosotani
Life of this patent
Estimating the term…
Abstract
A full hydraulic power steering system for a forklift truck or the like is disclosed which employes a hydraulically operated cylinder for turning a steerable wheel of the vehicle with increased power in response to turning of a steering wheel and control means for making a position compensation of the steering wheel in accordance with a change in the relationship between the directional position assumed by the steering wheel and that assumed by the steerable wheel. When the turning speed of the steering wheel is relatively low, the position compensation of the steering wheel is not carried out irrespective of degree of the change in the relationship.
Claims8
A full hydraulic power steering system for a vehicle having a steerable wheel, comprising:
- a hydraulic actuator having a stationary part fixed to the vehicle and a movable part movable relative to said stationary part, said movable part being operatively connected to said wheel;
- a steering wheel mounted on said vehicle;
- a steering unit operated by said steering wheel;
- a hydraulic fluid line operatively connecting said steering unit and said hydraulic actuator;
- drain line means connected to a portion of said hydraulic fluid line for conveying a part of the fluid in the hydraulic line into a drain tank;
- valve means disposed in said drain line means for selectively opening and closing said drain line means;
- first sensor means for sensing a steering wheel angle assumed by said steering wheel and for providing information based thereon;
- second sensor means for sensing an actual value for displacement of said movable part of the hydraulic actuator relative to said stationary part of the same and for providing information based thereon;
- and
- control means for calculating turning speed of the steering wheel and for controlling said valve means in accordance with the information from said first and second sensors in such a manner that when the turning speed of the steering wheel is not higher than a predetermined low level, said valve means keeps said drain line means closed.
A full hydraulic power steering system for a vehicle having a steerable wheel, comprising:
- a hydraulic actuator having a stationary part fixed to the vehicle and a movable part movable relative to said stationary part, said movable part being operatively connected to said wheel;
- a steering wheel mounted on said vehicle;
- a steering unit operated by said steering wheel;
- a hydraulic fluid line operatively connecting said steering unit and said hydraulic actuator;
- drain line means connected to a portion of said hydraulic fluid line for conveying a part of the fluid in the hydraulic line into a drain tank;
- valve means disposed in said drain line means for selective movement between open and closed positions for selectively opening and closing said drain line means;
- first sensor means for sensing a steering wheel angle assumed by said steering wheel and for providing information based thereon;
- second sensor means for sensing an actual value for displacement of said movable part of the hydraulic actuator relative to said stationary part of the same and for providing information based thereon;
- and
- control means for calculating turning speed of the steering wheel and for controlling said valve means in accordance with the information from said first and second sensors in such a manner that when the turning speed of the steering wheel is not higher than a predetermined low level, said valve means keeps said drain line means closed.
Dependencies are inferred from the claim text.