BRAKE SYSTEM WITH SKID CONTROL

摘要

In the apparatus disclosed a wheel velocity detector detects the velocity of a wheel on a vehicle that is being slowed down by a brake. A control circuit constrains a pressure regulator to decrease the pressure in the brake fluid that applies the braking force when the control circuit determines that skidding becomes likely. In the control circuit the velocity detector charges a capacitor to a reference velocity level just below the wheel velocity level. A first adjusting circuit allows the capacitor to discharge at a maximum first rate. Thus if the wheel velocity decreases beyond that maximum deceleration rate the wheel velocity may become less than the reference level. A comparator responsive to the wheel velocity detector and the capacitor level responds to the reference level exceeding the wheel velocity level by issuing a pressure reducing pulse to the pressure regulator. The pulse actuates a second adjusting circuit that increases the discharge rate of the capacitor for a given period of time. Thereafter the second adjusting circuit is inactivated and the first rate is reestablished. When, as a result of reduced pressure and braking force, the wheel velocity increases beyond the decreasing reference velocity the pressure reducing pulse ends. A third adjusting circuit measures a period of time from the onset of the pulse longer than the beforementioned time period to reestablish the second rate of discharge after the reestablishment of the first rate, in the event that the wheel velocity level does not exceed the reference level by that time. A setting circuit responds to the cessation of the pressure reducing pulse by momentarily discharging the capacitor to reestablish the differences between the wheel velocity level and the reference level.