Automobile antiskid hydraulic braking system

摘要

Antiskid hydraulic braking system comprising a first shutoff valve operable to shutoff hydraulic pressure from a master cylinder to wheel cylinder as the brakes tend to lock the wheels of a vehicle. Wheel cylinders are connected to a reservoir through a second shutoff valve which relieves hydraulic pressure at the wheel cylinders until the tendency toward wheel lock disappears. The system further comprises an intermittently operable high speed hydraulic pump, such as a piezoelectric pump, which serves to pump the brake fluid in the reservoir to the wheel cylinders to restore hydraulic pressure in the wheel cylinders. The piezoelectric pump comprises a pump plunger having a small diameter head defining a pumping chamber and a large diameter base defining a delivery or pressure chamber. The brake fluid under pressure in the delivery chamber acts upon the plunger base to hydraulically preload the piezoelectric elements.