Fluid-pressure and analogous brake systems – Speed-controlled – Having a valve system responsive to a wheel lock signal
Patent
1997-09-25
2000-02-01
Schwartz, Chris
Fluid-pressure and analogous brake systems
Speed-controlled
Having a valve system responsive to a wheel lock signal
B60T 1358
Patent
active
060194391
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a method of operating an anti-lock automotive vehicle brake system for driving stability control and/or traction slip control which includes a pneumatic brake force booster, that is operable irrespective of the driver's wish, and a master brake cylinder connected downstream of the brake force booster and having its pressure chambers connected to wheel brakes associated with the individual vehicle wheels by way of an ABS hydraulic unit that includes return pumps and low-pressure accumulators.
German patent No. 42 08 496 discloses a brake system, wherein the brake force booster interacts with a solenoid valve to achieve automatically controlled braking operations along with a great deceleration of the vehicle. The solenoid valve permits an enhanced use of the braking pressure upon quick application of the brake pedal. A brake pedal position sensor, a brake light switch and a force sensor which permits detection of the driver's wish for deceleration are provided to achieve the above-mentioned braking pressure control concept. Further, the known brake system includes an anti-lock control system (ABS) which ensures a stable deceleration behavior of the vehicle during braking operations. A disadvantage of the brake system described in the prior art is the comparatively high consumption of vacuum volume during control operations and the fact that the availability of vacuum is not ensured.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to disclose a method of operating an anti-lock automotive vehicle brake system of the previously mentioned type which permits minimizing the vacuum consumption during control operations.
This object is achieved according to the present invention in that, upon commencement of the control, the brake force booster has achieved the maximum attainable boosting force irrespective of the driver's wish, and the desired wheel braking pressures are adjusted by way of the ABS hydraulic unit. At the end of the control, the independent actuation of the brake force booster will not be deactivated until the brake force booster has been reset to its initial position by returning the pressure fluid discharged from the wheel brakes to the low-pressure accumulators. It is thereby achieved that the pressure balance which takes place after the deactivation between the working chamber and the vacuum chamber of the brake force booster causes only a small loss in vacuum volume or actuation energy.
In another feature of the present invention, the operation of the brake system described during a simultaneous actuation by the driver and an independent actuation is rendered possible because the actuation of the brake force booster by the driver is sensed, and the independent assist braking is correspondingly varied. An advantage of this provision results in the superposition of brake actuation by the driver and independent assist braking (irrespective of the driver) is a software arrangement and, therefore, may be configured freely in conformity to vehicle control requirements.
Using the brake force booster as the sole energy source for pressure increase limits the hydraulic structure required in the brake system described to that of a standard ABS brake system.
In another preferred aspect of the present invention, an indirect identification of the driver's wish for deceleration is ensured by determining the actuating travel of a brake pedal which actuates the brake force booster. The brake pedal is not moved when the brake force booster is actuated irrespective of the driver's wish. The established actuating travel is converted into an actuating force or a vehicle deceleration nominal value, preferably by way of a characteristic curve which is predefined or is acquired during normal braking operations. These arrangements permit the use of low-cost sensor means.
According to another preferred feature of the present invention the driver's wish for deceleration is precisely determined by sensing the actuating force which
REFERENCES:
patent: 5044702 (1991-09-01), Beck et al.
patent: 5098170 (1992-03-01), Watanabe
patent: 5181769 (1993-01-01), Schiel et al.
patent: 5350225 (1994-09-01), Steiner et al.
Drumm Stefan
Van Meel Franciscus
ITT Manufacturing Enterprises Inc.
Schwartz Chris
LandOfFree
Method of operating an anti-locking automotive vehicle-brake sys 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 operating an anti-locking automotive vehicle-brake sys, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of operating an anti-locking automotive vehicle-brake sys will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-932011