Steering device
AssigneeKnorr-Bremse Commercial Vehicle Systems Japan Ltd.
InventorsAtsushi Yoshitake, Shigeru Mochizuki
Life of this patent
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Abstract
A steering device includes a control unit that includes a hydraulic abnormality determiner. The hydraulic abnormality determiner is configured to determine a hydraulic abnormality to be present in a pair of liquid chambers of a power cylinder of the steering device, in response to satisfaction of a condition that a total torque of a steering torque measured by a torque sensor and a motor assist torque provided by an electric motor is greater than a predetermined threshold torque. The control unit is configured to increase the motor assist torque in response to satisfaction of a condition that the hydraulic abnormality determiner determines the hydraulic abnormality to be present.
Claims6
A steering device comprising:
- a steering shaft structured to receive rotation from a steering wheel;
- a transmitting mechanism structured to transmit rotation from the steering shaft to a turning wheel;
- a power cylinder that includes a piston disposed in the transmitting mechanism, and includes a pair of liquid chambers defined by the piston, and is structured to provide hydraulic assist torque for steering the turning wheel;
- a rotary valve structured to supply hydraulic liquid to the pair of liquid chambers selectively depending on rotation of the steering shaft;
- an electric motor structured to provide a motor assist torque for the steering shaft;
- a torque sensor structured to measure a steering torque based on rotation of the steering shaft;
- and
- a control unit configured to:
- determine a hydraulic abnormality to be present in the pair of liquid chambers, in response to satisfaction of a condition that a total torque of the steering torque and the motor assist torque is greater than a predetermined threshold torque;
- increase the motor assist torque of the electric motor in response to a determination that the hydraulic abnormality is present;
- and
- stop increasing the motor assist torque of the electric motor in response to satisfaction of a condition that an absolute value of the total torque is equal to or less than 5 Nm.
A steering device comprising:
- a steering shaft structured to receive rotation from a steering wheel;
- a transmitting mechanism structured to transmit rotation from the steering shaft to a turning wheel;
- a power cylinder that includes a piston disposed in the transmitting mechanism, and includes a pair of liquid chambers defined by the piston, and is structured to provide hydraulic assist torque for steering the turning wheel;
- a rotary valve structured to supply hydraulic liquid to the pair of liquid chambers selectively depending on rotation of the steering shaft;
- an electric motor structured to provide a motor assist torque for the steering shaft;
- a torque sensor structured to measure a steering torque based on rotation of the steering shaft;
- and
- a control unit configured to:
- determine a hydraulic abnormality to be present in the pair of liquid chambers, in response to satisfaction of a condition that a total torque of the steering torque and the motor assist torque is greater than a predetermined threshold torque;
- increase the motor assist torque of the electric motor in response to a determination that the hydraulic abnormality is present;
- and
- after determining that the hydraulic abnormality is present, cancel the determination of the hydraulic abnormality to be present, in response to satisfaction of a condition that:
- an engine speed is greater than 400 rpm;
- a vehicle speed is greater than 20 km/h;
- an absolute value of a steering angle is greater than 30 degrees;
- an absolute value of the steering torque is less than 5 Nm;
- and
- the steering angle and the steering torque coincide with each other in signs of positive or negative.
Dependencies are inferred from the claim text.