Hydro-Mechanically Coupled Electric Power Steering System
AssigneesArvinMeritor Technology, LLC, Techco Corporation
InventorEdward H. Phililips
Life of this patent
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Abstract
A power steering system provides improved steering feel whenever negligible power assist is required is required such as during on-center operation or at very high vehicular speeds. The power steering system includes fluid lines used for directly coupling a motor driven pump to a power cylinder. The fluid lines are coupled to a system reservoir or to one another whenever a primary control signal indicative of steering wheel torque has a value below a selected threshold value thereby substantially decoupling the power cylinder from the pump.
Claims40
A method of operating a hydro-mechanically coupled power steering system having a pump coupled to a power cylinder, the method comprising the steps of:
- a) sensing a steering input from a driver;
- b) at least substantially de-coupling the pump from the power cylinder based upon the sensed steering input decreasing below a first threshold value;
- and
- c) coupling the pump to the power cylinder based upon the sensed steering input increasing above a second threshold value.
A power steering system comprising:
- at least one pump;
- at least one power cylinder;
- and
- at least one valve selectively effectively coupling and decoupling the at least one power cylinder from the at least one pump.
A hydraulically coupled power steering system comprising:
- a pump;
- a power cylinder;
- a first fluid line coupling the pump to a first port of the power cylinder;
- a second fluid line coupling the pump to a second port of the power cylinder;
- a system reservoir;
- and
- a valve assembly including first and second solenoid-controlled two-way valves for selectively fluidly coupling the first fluid line and the second fluid line to the system reservoir.
A valve assembly comprising:
- a valve body having a bore therein;
- a first port, a second port and a relief port extending through the body to the bore;
- a first valve spool having a metering edge, the first valve spool disposed within the bore for selectively fluidly coupling the first port to the relief port;
- a second valve spool having a metering edge, the second valve spool disposed within the bore for selectively fluidly coupling the second port to the relief port;
- a first solenoid operatively coupled to the first valve spool;
- a second solenoid operatively coupled to the second valve spool;
- and
- the valve body having metering edges, wherein the metering edges of the first valve spool and the second valve spool are spaced in a lapped fashion with reference to the metering edges of the valve body such that when either of the first solenoid or the second solenoid is energized while the other is de-energized, the energized one of the first solenoid and the second solenoid urges both the first valve spool and the second valve spool toward a position in which one of the first port and the second port is decoupled from the relief port and the other of the first port and the second port is coupled to the relief port.
Dependencies are inferred from the claim text.