Control of ABS threshold without accompanying reduction of brake pressure

US5249850A · kind A · utility

Assignee

• Lucas Industries public limited company · GB

Inventors

• Wolfgang Kampfmann · Moselkern, DE
• Dieter Voges · Vallendar, DE
• Volker Braschel · Neuwied, DE

Key dates

• Filing date: Sep 30, 1991
• Grant date: Oct 5, 1993
• Expiry date: Sep 30, 2011

Classification

• Technology area (CPC B): Performing Operations; Transporting
• CPC primary: B60T8/173
• WIPO field: Transport
• WIPO sector: Mechanical engineering

Abstract

In a method of controlling the brake pressure of a vehicle brake system equipped with anti-lock protection it is provided to measure the slip and/or rotational retardation of a wheel whose brake is applied and to compare each measured value with a given threshold value so as to lower the brake pressure if the threshold value proves to have been surpassed. Undesired pressure reductions can be avoided by increasing the threshold value for given periods of time from a basic value (S.sub.G) and subsequently decreasing it again. At a point in time T.sub.1 at which the rotational retardation of the braked wheel is greater than a value corresponding to a physically feasible slowdown of the vehicle the threshold value is increased abruptly, to be decreased thereafter according to a predetermined function of time. During the lowering of the threshold value the change in speed of the retarded wheel is measured over given intervals of time .DELTA.T and compared with the instantaneous higher threshold value. If the comparison demonstrates that the change in speed in question is greater than the instantaneous raise in threshold value, the threshold value is reduced to the basic value (S.sub. G)…