Brakes – With condition indicator – Electrical
Patent
1998-06-15
2000-06-13
Oberleitner, Robert J.
Brakes
With condition indicator
Electrical
303 3, 303 15, F16D 6600
Patent
active
060737298
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a method of operating a hydraulic brake system for automotive vehicles, which includes an anti-lock system (ABS), a brake force booster which is electrically actuatable independently of the driver's wish, and a pressure or deceleration controller which is used to actuate the brake force booster and to which a pressure or deceleration nominal value signal generated by a superior controller and an actual value signal representative of the hydraulic pressure that prevails in the system or the occurring deceleration are sent as input quantities.
The article "Electronically Controlled Brake Force Booster" published in the Automobile Technology Journal ATZ 97 describes a hydraulic brake system for automotive vehicles wherein there is no exchange of quantities characterizing the ABS control condition (apart from the information about the preset nominal pressure and the wheel speeds) between the electronic ABS controller and the pressure or deceleration controller which actuates the electrically actuatable brake force booster. This causes uncomfortable movements of the brake force booster and noises during ABS control operations which are triggered by the independent activation of the brake force booster. Further, inappropriate ABS control cycles which involve longer stopping distances may occur which are due to pressure variations in the ABS control operations which the pressure controller, in interaction with the electronically controllable brake force booster, tends to compensate by control.
Therefore, an object of the present invention is to virtually eliminate the above mentioned shortcomings and to thereby enhance the quality of the ABS control.
SUMMARY OF THE INVENTION
According to the present invention, this object is achieved because a signal indicative of the ABS control mode is sent to the pressure or deceleration controller, and the instantaneous pressure or deceleration actual value is stored upon commencement of the ABS control and the brake force booster is actuated so that the pressure or deceleration actual value is maintained constant.
Further details, features and advantages of the present invention can be taken from the following description of an embodiment, making reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE INVENTION
In the drawings,
FIG. 1 is a greatly simplified view of a hydraulic brake system for implementing the method of the present invention.
FIGS. 2a to 2c are diagrams showing the pressure variations in the implementation of the method of the present invention in various control situations.
DETAILED DESCRIPTION OF THE INVENTION
The brake system for automotive vehicles shown in FIG. 1 generally includes an actuating unit 1, an electronic controller 8, an anti-lock system including an electronic ABS controller 11 and wheel brakes (not shown) . The actuating unit 1, in turn, has a pneumatic brake force booster, preferably a vacuum brake force booster 2, operable by an actuating pedal 4. Connected downstream of booster 2 is a master brake cylinder 3, preferably a tandem master cylinder 3, having pressure chambers (not shown) which are connected to the wheel brakes by way of hydraulic lines 9, 10. Coupled to the actuating pedal 4 is an actuating rod 5 which is used to mechanically actuate a control valve 6 (illustrated only schematically). Control valve 6 controls the increase and decrease of a pneumatic differential pressure in the housing of the vacuum brake force booster 2. A solenoid 7 permits (independently) activating the control valve 6 irrespective of the actuating rod 5. The solenoid 7 is actuated by actuating signals of an electronic brake pressure controller 12 to which are sent, as input quantities, a signal ABSM produced by the ABS controller 11, a pressure nominal value signal P.sub.soll produced by the controller 8, and a pressure actual value signal P.sub.ist produced by a pressure sensor 13 which senses the hydraulic pressure that prevails in the system. The signal ABSM contains the
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patent: 5778337 (1998-08-01), Eckert
patent: 5816667 (1998-10-01), Jokic
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ITT Manufacturing Enterprises Inc.
Oberleitner Robert J.
Talavera Melanie
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