US 5,375,506 AGranted

Hydraulic pressure control apparatus

AssigneeSumitomo Electric Industries, Ltd.

InventorsKoichi Hashida, Masato Yoshino

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Abstract

A hydraulic pressure control apparatus comprising: an introducing valve provided on a supply duct connecting to each other a hydraulic source and a control chamber for controlling a fluid-operated equipment or increasing or decreasing the hydraulic pressure of the fluid-operated equipment; and a discharge valve provided on a discharge duct discharging hydraulic fluid from the fluid-operated equipment or the control chamber. The introducing valve and/or the discharge valve are disposed in series on the supply duct or the discharge duct; at least one of a plurality of the introducing valves and/or the discharge valves consists of a flow rate-variable valve capable of changing the flow rate of the hydraulic fluid continuously according to the intensity of electric current; and the other introducing valves and/or discharge valves consist of electromagnetic change-over valves fully opened or fully closed.

Claims13

Dependent claims

A hydraulic pressure control apparatus comprising:

a hydraulic source with a supply duct;
a fluid introducing valve connected to said supply duct and connecting said hydraulic source with a control member of a fluid-operated device for controlling hydraulic pressure of the fluid-operated device;
and
a discharge valve connected to a discharge duct of said control chamber for discharging hydraulic fluid from the fluid-operated device,
said fluid introducing valve being opened to increase the pressure of the fluid-operated device and said discharge valve being opened to decrease the pressure of the fluid-operated device, said fluid introducing valve and said discharge valve being disposed, respectively, on either side of said discharge duct, at least one of said fluid introducing and discharge valves including a flow rate-variable valve for continuously changing the flow rate of the hydraulic fluid according to the intensity of an electric current supplied thereto, and the other one of said fluid introducing and discharge valves including an electromagnetic change-over valve that is opened and closed based on an electric current supplied thereto.

2 more elements

Dependencies are inferred from the claim text.