US 4,225,195 A · Process and device for the regulation of braking pressure in lock-up protection systems

Abstract

A process and apparatus for regulating the operator-controlled brake pressure of a vehicle wheel to prevent wheel lock-up by sensing a lock-up tendency and independently varying the operator-controlled brake pressure at the skidding wheel during successive cycles of wheel skid control. The sensed wheel behavior is monitored by an evaluation circuit which measures the duration of brake pressure reapplication with constant gradient during an initial cycle, provides a time period during a subsequent cycle that is a predetermined time duration less than the time duration of reapplication pressure in the initial cycle, and following expiration of the reduced time duration, establishes reapplication of pressure with a pressure gradient lower than the gradient during the initial cycle, whereby the reapplication pressure during control cycles subsequent to the initial control cycle is with a stepped gradient.

Claims15

Dependent claims

A process for the regulation of vehicle brake pressure in a wheel skid control system consisting of the steps of:

measuring the rotational velocity of a vehicle wheel;
differentiating said measured wheel velocity to obtain wheel acceleration and deceleration rates;
comparing said wheel acceleration and deceleration rates with different threshold values to obtain wheel acceleration, deceleration, and slip control signals;
regulating the wheel brake pressure during an initial cycle of wheel skid control in accordance with said acceleration, deceleration, and slip control signals, so that the reapplication of said brake pressure is with a constant gradient;
measuring the duration of said brake pressure reapplication during said initial wheel skid control cycle to establish a time period T1;
reducing said time period T1 to establish a time period T2 that is shorter in duration than said time period T1;
and reapplying said brake pressure during at least one subsequent cycle of wheel skid control, so that, upon expiration of said time period T2, the gradient of said brake pressure is reduced relative to the gradient during said time period T2 to obtain a stepped reapplication pressure gradient.

4 more elements

A wheel skid control system for regulating vehicle brake pressure having a wheel sensor to detect the rotational velocity of a vehicle wheel;

a differentiator to detect a rate of change of wheel velocity;
means for providing acceleration, deceleration, and slip control signals when said rate of change of wheel velocity exceeds different predetermined threshold values;
valve means for controlling brake pressure;
evaluation circuit means for operating said valve means in accordance with said control signals;
whereby the reapplication of brake pressure during an initial cycle of wheel skid control follows a constant pressure gradient;
time control means for measuring a time period T1 between initiation and termination of said reapplication of brake pressure during said initial wheel skid control cycle and further providing a time period T2 during a subsequent wheel skid control cycle that is shorter in duration than said time period T1;
control means operative independently of said evaluation means for reducing said gradient of said reapplication brake pressure;
and said time control means including means for preventing operation of said control means during said time period T2 and effecting operation of said control means thereafter until expiration of said time period T1 to provide a brake pressure reapplication gradient during at least one subsequent wheel skid control cycle having a high pressure gradient initially and thereafter a low pressure gradient.

5 more elements

Dependencies are inferred from the claim text.

Process and device for the regulation of braking pressure in lock-up protection systems

Life of this patent

Process and device for the regulation of braking pressure in lock-up protection systems

Life of this patent

Abstract

Claims15