| 摘要 |
PURPOSE: A smart booster brake device is provided to obtain stable fluid pressure control, performance improvement, and a safe fail-safe function against different failure modes. CONSTITUTION: A smart booster brake device comprises a reducing valve (RV), a fail-safe valve (FV), and two solenoid valves (620) in a normally open type. The reducing valve is connected to a sub master cylinder (300) through a first fluid pressure line. The reducing valve reduces the fluid pressure delivered from the sub master cylinder through the first fluid pressure line to be lower than a predetermined spring force. The fail-safe valve is supplied with the fluid pressure through a plurality of fluid pressure lines (4 to 7) and utilizes the fluid pressure as control pressure to control the left and right movements of a spool. The solenoid valve controls the opening and closing operation of two fluid pressure lines among a plurality of fluid pressure lines. [Reference numerals] (AA) A-d: each land part area of a spool(a<b=c=d); (BB) P*a=P(b-a)+Fs > P*d (Fs = spring force) |
