JPS5576739A - Relief valve mechanism for hydraulic booster - Google Patents

Abstract

PURPOSE: To improve a response property of a power steering, by constituting a mechanism so that a working oil at the upstream side of a throttle valve can also be fed to the power steering through a relief valve which opens when it moves to a pilot chamber.

CONSTITUTION: Where a hydraulic pressure corresponding to a steering load is generated in a passage in the case of steering being performed in a condition that a hydraulic booster 8 is not working as a result of a brake pedal 19 being not stepped on, said hydraulic pressure is fed to a main valve chamber 59. In the meantime, said condition results in a closing a control valve 49 and in opening a return valve 50. As a result of a boosting chamber 45 being connected to a drain circuit, a pilot chamber 60 connected to the boosting chamber 45 via an oil passage 72, an orifice 63, and an oil passage 62, being also connected to the drain circuit. Thus, when an oil pressure, fed to a main valve chamber 59, corresponding to a steering load reaches the value exceeding a set load of a spring 58, said oil pressure moves a main valve 56 against a spring 58 to open a relief valve 55.

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