Fluid-pressure and analogous brake systems – Speed-controlled – Having a valve system responsive to a wheel lock signal
Patent
1997-02-27
1998-10-06
Butler, Douglas C.
Fluid-pressure and analogous brake systems
Speed-controlled
Having a valve system responsive to a wheel lock signal
303155, 303166, 303 3, 3031143, B60T 834, B60T 832, B60T 712, B60T 1366
Patent
active
058166670
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a method of controlling the braking pressure of an automotive vehicle brake system as a function of the rate of pedal actuation, by way of a braking pressure generator which is driven by an independent force when an actuation threshold is exceeded.
German patent No. 40 28 290 discloses a method of shortening the stopping distance in critical driving situations. In this method, an independent force causes an increase in braking pressure as soon as the rate of pedal actuation exceeds a threshold value. Cases are likely where the driver depresses the pedal at a high rate during panic braking or emergency stopping, but exerts only insufficient force on the pedal. Therefore, the driver is assisted by the independent force in this situation, whereby a brake force is caused which is in excess of the brake force that would correspond to the pedal force during normal pedal actuation.
It must be ensured for obvious reasons that the independent force does not occur inadvertently because an undesirably great deceleration of the vehicle involving a risk of rear-end collision for the following vehicle would be caused.
On the one hand, the actuation threshold of the independent force should be so low that the threshold is exceeded with certainty in an emergency situation, even by a rather weak driver. On the other hand, the threshold should be so high as to prevent inadvertent actuation of the independent force. These contrary requirements are difficult to satisfy especially because the pedal actuation characteristics of a vehicle depends on manufacturing tolerances of the individual components and, also, on the condition of the brake system and the brake fluid.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide a method permitting a maximum precise adjustment of and adherence to the actuation threshold.
It has been found that this object may be achieved by the method described in claim 1. The special features of the method of the present invention involve that the actuation threshold is defined by a basic value which is responsive to pedal speed, and by factors which are responsive to the vehicle speed and the pedal travel, that the actual values of the pedal travel and/or the vehicle deceleration and/or the braking pressure are determined in partial braking operations, that the actual values are compared with nominal values, such as preset standards, series mean values, etc., that correction factors are determined from the respective difference between the actual values and the nominal values, that an adaptation factor is calculated in a learning process over successive partial braking operations, and that the basic value is additionally multiplied by the adaptation factor to determine the actuation threshold.
Thus, the pedal actuation characteristics is set to a predefined behavior or a series mean value in a learning process according to the present invention. The decisive factors which previously influenced the pedal characteristics, such as
It is possible to adjust the actuation threshold relatively exactly to the above-mentioned compromise value which satisfies drivers with different habits of pedal actuation.
In a preferred aspect of the present invention, the actual values of the pedal travel and the acceleration are measured during the individual partial braking operations, the actual value of pedal travel is compared with the nominal value of the vehicle deceleration or the nominal value of the braking pressure, and a correction factor is derived from the nominal and actual values.
Further, in an aspect of the method of the present invention, the adaptation factor is determined by calculating a mean value over successive partial braking operations where the pedal travel and/or the vehicle deceleration exceed a predetermined minimum value.
It is expedient to determine the correction factors by comparison of the actual values with nominal values stored in tables, for example, in the read-only memory of a microcontr
REFERENCES:
patent: 4678243 (1987-07-01), Leiber
patent: 4826255 (1989-05-01), Volz
patent: 5146408 (1992-09-01), Valentic
patent: 5158343 (1992-10-01), Reichelt et al.
patent: 5401084 (1995-03-01), Volz
patent: 5441335 (1995-08-01), Stumpe et al.
patent: 5445444 (1995-08-01), Rump et al.
patent: 5505526 (1996-04-01), Michels
patent: 5513906 (1996-05-01), Steiner
patent: 5535123 (1996-07-01), Rump et al.
patent: 5584542 (1996-12-01), Karer et al.
patent: 5660448 (1997-08-01), Kiesewetter et al.
patent: 5669676 (1997-09-01), Rump et al.
patent: 5719769 (1998-02-01), Brugger et al.
English Translation of the International Preliminary Examination Report for Application No. PCT/EP95/02997 filed Jul. 28, 1995.
Search Report of the German Patent Office for Application P4430461.7.
Butler Douglas C.
ITT Manufacturing Enterprises Inc.
Lewis J. Gordon
Twomey Thomas N.
LandOfFree
Method of controlling the braking pressure as a function of the does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of controlling the braking pressure as a function of the , we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of controlling the braking pressure as a function of the will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-71029