Vehicle brake system

摘要

In a brake-by-wire vehicle brake system that uses a solenoid shut-off valve (24a, 24b), the electric power supplied to the solenoid (33) of the solenoid shut-off valve is controlled so as to decelerate a movement of a plunger (31, 32) of the valve as the plunger reaches a point immediately adjacent to a terminal point thereof. Thereby, a highly responsive property can be achieved while the noises that are generated by the plunger striking a stopper (36) or a valve seat (34) can be minimized. When actuating the plunger in the valve closing direction, the solenoid may receive electric power at a first level, a second level lower than the first level and a third level intermediate between the first and second levels in that order.

主权项

1. A method of reducing noise from closing a solenoid controlled ON-OFF valve in a brake-by-wire system, said method including the steps of:
a) receiving a signal from a brake pedal; b) based on the signal from the brake pedal, determining a desired speed for closing an ON-OFF valve in the brake-by-wire system; c) based on the desired speed for closing the ON-OFF valve, supplying electric power at a first level to the solenoid; d) after a first time period slightly shorter than the time required for a plunger in the ON-OFF valve to reach the fully closed position, supplying electric power at a second level to the solenoid, the second level lower than the first level; e) after a second time period, supplying electric power at a third level to the solenoid, the third level intermediate between the first level and the second level; wherein a plunger of the solenoid is opposed by a spring, and wherein motive force supplied by the second level of power is substantially equal to a force of the spring, whereby movement of the plunger is temporarily suspended until electric power is supplied at the third level.