Modulator for use in antilock system.

摘要

A modulator for reincreasing brake pressure during antilock control which is small in size, simple in structure and low in cost, and which can prevent kickbacks to the brake peal (2) and the transmission of pump pulsation to the brake pedal (2). This modulator has a flow restriction valve (9) adapted to check fluid flow from a pump (10) toward a master cylinder (1) if the discharge pressure of the pump (10) becomes higher by a predetermined value than the fluid pressure in a wheel brake (3). It further includes a piston (20) adapted to hold the valve body (12a) of the pump discharge valve (12) or the valve body (11a) of the pump intake valve (11) in the open position if the pump discharge pressure exceeds the master cylinder pressure (or the wheel brake pressure) by a predetermined value. With this arrangement, while there is no need to supply brake fluid from the pump (10), or if an excessive brake fluid is supplied from the pump (10), the pump (10) automatically stops discharging brake fluid. This prevents the kickback and reduces the amount of electric power consumed by the pump driving motor.