Brake fluid pressure retaining device

摘要

A brake fluid pressure retaining unit (5) is provided which allows a relief pressure to be variable only by use of a low-cost electromagnetic valve without using an expensive relief valve and orifice. The brake fluid pressure retaining unit (5) includes an electromagnetic valve (9) which is provided midway in a brake fluid channel (4) connecting a master cylinder (2) and a wheel cylinder (3) and is capable of freely opening/closing the brake fluid channel (4) by passing current though a solenoid coil (8); and an electromagnetic valve control section which detects a release signal indicative of releasing brake operation detected by a brake operation detecting section and passes current through the solenoid coil (8) while referring to current values corresponding to a target maintaining fluid pressure to maintain a predetermined braking force. The electromagnetic valve control section determines in advance a predetermined opening-side current value required to switch the electromagnetic valve (9) from a closed state to an open state and a predetermined closing-side current value required to switch the electromagnetic valve (9) from an open state to a closed state, for each target maintaining fluid pressure, and performs control so that the value of the current to be passed through the solenoid coil (8) is in a range between the predetermined opening-side current value and predetermined closing-side current value. <IMAGE>