Boots – shoes – and leggings
Patent
1992-07-22
1993-08-03
Chin, Gary
Boots, shoes, and leggings
303 95, 303103, B60T 866
Patent
active
052335291
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an automatic anti-skid brake control system for a motor vehicle. More particularly, the present invention relates to an anti-skid brake control system which includes wheel sensors for determining the speed of each individual vehicle wheel, an evaluation circuit to which the wheel speed sensor signals are applied and which generates brake pressure control signals as a function of the wheel speeds, and brake pressure control valves, responsive to the brake pressure control signals, for varying the brake pressure at the vehicle wheels. In the evaluation circuit, the wheel speed signals are used to obtain at least one reference speed value that approximates the vehicle speed characteristics so as to determine the slippage of any wheel. Such slippage, together with the wheel speed signals and the vehicle deceleration, is used to control the brake pressure.
2. Prior Art
The German patent publication No. 2,313,763 to which U.S. Pat. No. 3,907,378 corresponds discloses an automatic anti-skid brake control system of the aforementioned type. This automatic anti-skid brake control system, which also generates slippage signals and therefore requires a reference speed, is provided with a vehicle deceleration sensor which is used to determine, in short repeated intervals, whether the braking effect of the vehicle is more efficient with or without the anti-skid control. In this case, the vehicle deceleration sensor consequently serves to monitor the anti-skid control.
It is also known from the German patent publication No. 2,558,712, to which U.S. Pat. No. 4,053,188 corresponds to formulate the reference speed which is required for slippage control by referring to the speed signals of two or more wheels included in the control system and to select for reference speed formulation the most rapidly turning wheel. The wheel speed signals V.sub.R trigger the possibly necessary slope of the reference speed signals either without modification or with at least one prescribed slope. To decrease the reference speed V.sub.Ref in case of instability (V.sub.R <V.sub.Ref), there are several slopes which can be activated as a function of the determined rotational behavior of the wheel slope according to a prescribed algorithm.
SUMMARY OF THE INVENTION
It is an object of the invention to obtain a reference speed value for an Anti-skid brake control system with more simple means than in conventional systems while improving the match correlation to the actual vehicle speed characteristics.
This object, as well as other objects which will become apparent from the discussion that follows, are achieved, according to the present invention, by determining the vehicle deceleration from the average slope of the reference speed value and by using this vehicle deceleration, so determined, to determine the slope of the reference speed value during periods of braking instability.
It is of importance in the invention that the vehicle deceleration derived from the reference speed, in turn, affects the (negative) slope of this reference speed in case of instability (V.sub.R <V.sub.Ref). A particularly favorable reference speed value formulation is achieved if the negative slope of the reference speed is selected during instability phases so as to be slightly higher (by a certain value or percentage of e.g. 10-20%) than the vehicle deceleration; i.e., the reference speed is reduced slightly more than is the vehicle speed. The effects which vehicle deceleration and slope of the reference speed have on each other result in a progressive change for both values. In particular, a higher deceleration causes a greater slope of the reference speed and vice versa. Here, the reference speed can hardly surpass the vehicle speed. The value by which the negative slope of the reference speed is selected to be greater than the calculated deceleration can be made a function of the pressure increase period, e.g. the number of the pressure increase pulses after a pressure dro
REFERENCES:
patent: 4718013 (1988-01-01), Kubo
patent: 4736994 (1988-04-01), Fennel et al.
patent: 4818037 (1989-04-01), McEnnan
patent: 4848850 (1989-07-01), Yoshino
patent: 4859002 (1989-08-01), Yoshino
Braschel Volker
Seitz Dieter
Chin Gary
Robert & Bosch GmbH
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