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US 2009/0211835 A1Published application
Inherently failsafe electric power steering system
OwnerEdward H. Phillipsinventor
Life of this patent
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Abstract
An electronically controlled hydro-mechanically coupled power steering system includes a double-acting power cylinder having a directional control under-lapped four-way open center valve and a motor driven pump. A controller selectively provides pressurized fluid to the double-acting power cylinder to function in the manner of an inherently failsafe EPS system.
Claims18
A hydro-mechanically coupled EPS system for a vehicle comprising:
- at least one power cylinder;
- a directional control valve operatively connected to the at least one power cylinder and having a first output port and a second output port for controlling a steering direction;
- a pump having an output port fluidly connected to an input port of the directional control valve;
- and
- a controller controlling the pump based upon a steering wheel input signal.
2 more elements
A method for operating a power steering system comprising
- a) measuring applied torque on a steering wheel;
- b) determining a desired pressure value to be applied to an input port of a directional control valve as a function of the applied torque;
- c) measuring an actual pressure value present at the input port of the directional control valve;
- d) comparing the actual pressure value to the desired pressure value;
- e) controlling a pump supplying fluid to the input port of the directional control valve based upon said step d) in order to provide the desired pressure value to the input port of the directional control valve.
2 more elements
A power steering system for a vehicle comprising:
- a pump;
- a steering wheel;
- a four-way valve for controlling a steering direction, the four-way valve mechanically coupled to the steering wheel, the four-way valve selectively fluidly connecting an input port to a left output port or a right output port for controlling steering direction;
- and
- a controller controlling the pump to control an amount of power steering assist.
2 more elements
Dependencies are inferred from the claim text.