POWER STEERING DEVICE AND ITS CONTROLLING METHOD

摘要

PROBLEM TO BE SOLVED: To provide a power steering device capable of generating a sufficient assist force using a backup mechanism when an oil pressure feeding mechanism goes in failure.

SOLUTION: The power steering device is equipped with a hydraulic power cylinder 5 to assist the steering force of a rack-pinion mechanism 4 and a first oil pressure feeding mechanism 8 consisting of a first trochoid pump 23 and a first electric motor 24 for feeding the oil pressure selectively via a first 6 and a second passage 7. When the first oil pressure feeding mechanism has gone in failure, a second oil pressure feeding mechanism 11 feeds the working oil pressure to the two oil pressure chambers selectively from a third 9 and a fourth passage 10 in conformity to the command signal given by a control unit 14.

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