Fluid-pressure and analogous brake systems – Speed-controlled – Having a valve system responsive to a wheel lock signal
Patent
1997-12-08
2000-04-11
Graham, Matthew C.
Fluid-pressure and analogous brake systems
Speed-controlled
Having a valve system responsive to a wheel lock signal
3031143, B60T 712
Patent
active
060480394
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a brake system for motor vehicles, with an activating unit which consists of a pneumatic brake booster as well as a master brake cylinder which is connected at the outlet side to the same, and to which the wheel brakes are connected, whereby the control valve of the brake booster can be triggered, independently of the volition of the driver, by means of an electromagnet, by means of the armature of which one of the control valve sealing fitting units can be activated, with a brake pressure controller, to which is conveyed the standard difference between a signal corresponding to the nominal braking pressure and a signal corresponding to the actual braking pressure, which difference is formed in a first adding device and the output quantity of which, which corresponds to a nominal armature travel, is compared in a second adding device with a signal which corresponds to the actual armature travel, whereby the standard difference corresponding to the comparative result is conveyed to a position control unit which influences the position of the control valve, the output quantity of which corresponds to the electrical current which is to be supplied to the electromagnet.
Such a type of brake system is already known from international patent application WO 95/03196. The structure of the previously-known brake pressure controller represents a compromise between the control unit dynamic which is desired and the disturbance behavior of the control unit. If a highly dynamic or very rapidly operating control unit is used, then this has a gradated characteristic curve, which has noises and vibrations in the system, which act in an unpleasant manner, as its consequence.
In the case of a slowly operating control unit, greater imprecisions in changing operations (changes in the operational sign or of the direction) in regard to the nominal value must then be accepted in return.
It is thus the object of the present invention to propose measures which make possible a control with the following characteristics:
a) For the sequence control:
b) For disruption behavior, static control inputs, or final value control:
SUMMARY OF THE INVENTION
This object is achieved, in accordance with the invention, through the fact that the braking pressure control unit is formed by a parallel circuit of a first control unit (sequence control unit), which follows the rapid temporal changes of the signal corresponding to the nominal braking pressure, and a second control unit (final value control unit), which follows signals corresponding to the slow changes or to static final values, whereby the output quantities of both of the control units are conveyed to a situational switching logic unit which, in accordance with a selection criterion, connects the output quantity of the first or of the second control unit through to the position control unit.
Further details, characteristics and advantages of the invention proceed from the following description of two examples of implementation, with reference to the attached diagrams, in which the same reference numerals are used for individual parts which correspond to one another.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings,
FIG. 1 shows one embodiment of the brake system in accordance with the invention, in a schematic representation;
FIG. 2 shows the control group of the pneumatic brake booster in accordance with FIG. 1, in an axial section, partially cut away;
FIG. 3 shows the principle of the design of the braking pressure control unit, in a simplified schematic representation;
FIG. 4 shows a schematic block diagram of a first embodiment of the braking pressure control unit in accordance with FIG. 3; and
FIG. 5 shows a schematic block diagram of a second embodiment of the braking pressure control unit in accordance with FIG. 3.
DETAILED DESCRIPTION OF THE DRAWINGS
The brake system for motor vehicles according to the invention which is depicted in FIG. 1 essentially consists of an activating unit 1, an electronic vehicle control un
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Graham Matthew C.
ITT Manufacturing Enterprises Inc.
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