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US 2006/0064973 A1Published application
Power steering apparatus
AssigneeHitachi, Ltd.
InventorsMasakazu Kurata, Tadaharu Yokota
Life of this patent
Estimating the term…
Abstract
A power steering apparatus includes a hydraulic power cylinder, and a reversible pump driven by a motor. A steering assist sensor senses a steering assist force provided to a steering wheel. A controller ascertains a pump discharge quantity of the reversible pump, and a cylinder volume variation of the pressure chambers of the hydraulic power cylinder; and calculates a leak quantity of the reversible pump from a difference between the pump discharge quantity and the cylinder volume variation. The controller controls the motor to cause the motor to produce a desired fluid pressure in accordance with the steering assist force and the leak quantity.
Claims20
A power steering apparatus comprising:
- a hydraulic power cylinder including first and second pressure chambers and a piston separating the first and second pressure chambers to provide a steering force to a steering mechanism connected with a steering wheel;
- a reversible pump including a first outlet connected with the first pressure chamber through a first fluid passage, and a second outlet connected with the second pressure chamber through a second fluid presage to supply a fluid pressure to the first pressure chamber or the second pressure chamber selectively;
- a motor arranged to drive the reversible pump in a forward rotational direction or a reverse rotational direction;
- a steering assist force sensor arranged to sense a steering assist force to be provided to the steering wheel;
- a pump discharge quantity measuring section configured to ascertain a pump discharge quantity of the reversible pump;
- a cylinder volume variation measuring section configured to ascertain a cylinder volume variation of one of the pressure chambers of the hydraulic power cylinder;
- a leak quantity calculating circuit configured to calculate a leak quantity of the reversible pump from a difference between the pump discharge quantity and the cylinder volume variation;
- and
- a motor control circuit configured to deliver a motor drive signal to the motor to cause the motor to produce the fluid pressure in accordance with the steering assist force and the leak quantity.
6 more elements
A power steering apparatus comprising:
- a hydraulic power cylinder including first and second pressure chambers and a piston separating the first and second pressure chambers to provide a steering force to a steering mechanism connected with a steering wheel;
- a reversible pump including a first outlet connected with the first pressure chamber through a first fluid passage, and a second outlet connected with the second pressure chamber through a second fluid presage to supply a fluid pressure to the first pressure chamber or the second pressure chamber selectively;
- a motor arranged to drive the reversible pump in a forward rotational direction or a reverse rotational direction;
- a steering assist force sensor arranged to sense a steering assist force provided to the steering wheel;
- a leak quantity measuring section configured to ascertain a leak quantity of the reversible pump;
- an oil temperature estimating circuit configured to estimate an oil temperature of an operating oil for the hydraulic power cylinder;
- and
- a motor control circuit configured to deliver a motor drive signal to the motor to cause the motor to produce the fluid pressure in accordance with the steering assist force and the oil temperature.
5 more elements
A power steering apparatus comprising:
- a hydraulic power cylinder including first and second pressure chambers and a piston separating the first and second pressure chambers to provide a steering force to a steering mechanism connected with a steering wheel;
- a reversible pump including a first outlet connected with the first pressure chamber through a first fluid passage, and a second outlet connected with the second pressure chamber through a second fluid presage to supply a fluid pressure to the first pressure chamber or the second pressure chamber selectively;
- a motor arranged to drive the reversible pump in a forward rotational direction or a reverse rotational direction;
- a steering torque sensor arranged to sense a steering torque to be provided to the steering wheel;
- a pump discharge quantity calculating circuit configured to calculate a pump discharge quantity of the reversible pump;
- a cylinder volume variation calculating circuit configured to calculate a cylinder volume variation of one of the pressure chambers of the hydraulic power cylinder;
- a leak quantity calculating circuit configured to calculate a leak quantity of the reversible pump from a difference between the pump discharge quantity and the cylinder volume variation;
- an oil temperature estimating circuit configured to estimate an oil temperature from the leak quantity;
- and
- a motor control circuit configured to deliver a motor drive signal to the motor to cause the motor to produce the fluid pressure in accordance with the steering torque and the oil temperature.
7 more elements
Dependencies are inferred from the claim text.