Fluid-pressure and analogous brake systems – Speed-controlled – Having a valve system responsive to a wheel lock signal
Reexamination Certificate
1999-03-29
2004-06-15
Rodriguez, Pam (Department: 3683)
Fluid-pressure and analogous brake systems
Speed-controlled
Having a valve system responsive to a wheel lock signal
Reexamination Certificate
active
06749270
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a device and a method for controlling at least one operating-dynamics variable of a vehicle in closed loop. In particular, the present invention relates to a driving control of a braking system of the vehicle, and to the device utilized for this purpose.
BACKGROUND INFORMATION
Conventional devices and methods for controlling at least one operating-dynamics variable of a vehicle are known in numerous variations. For example, the publication “FDR—Die Fahrdynamikregelung von Bosch” (FDR—Operating-Dynamics Control of Bosch), on pages 674-689 of the automobile technology periodical (ATZ) 96, 1994, issue 11, describes an exemplary conventional device and method. In this operating-dynamics control, a setpoint value is determined for the vehicle float angle and yaw rate, respectively, on the basis of at least the steering-wheel angle and the vehicular velocity. The setpoint values for the float angle and the yaw rate are supplied, together with the corresponding actual values, to a state controller which determines vehicle setpoint yawing moments from the corresponding system deviations. These vehicle setpoint yawing moments are converted, in view of the prevailing slip values, into setpoint slip changes at the suitable wheels. The setpoint slip changes are implemented by the subordinate ABS (antilock braking system) and ASR (traction control system) wheel-controller units. For example, when, during free rolling, the vehicle is oversteered in a right curve, and the setpoint yaw rate is exceeded, among other things, a setpoint brake slip is preset at the left front wheel, through which a yawing-moment change turning to the left acts on the vehicle, thereby reducing the overly great yaw rate. In the unbraked case, or when the driver initial pressure is not sufficient to adjust the desired setpoint slip, the pressure in the brake circuits is actively increased.
German Patent Application No. 40 35 527 (corresponding to U.S. Pat. No. 5,205,623) describes a hydraulic braking system having antilock braking system (ABS) and traction control system (ASR) for motor vehicles. This hydraulic conventional braking system features a hydraulic aggregate having at least one control valve and a return pump with at least one self-priming pump element which is operative in the brake circuit containing the at least one drive wheel. A valve arrangement, composed in each case of a charging valve and a selector valve, is used to make brake pressure available in ASR. The selector valve is arranged in the connection running from the master brake cylinder to the wheel brake cylinder of the drive wheel, and the charging valve is disposed in a suction line between the pump element and the brake-fluid reservoir. To achieve a hydraulic power requirement in ASR, the valve arrangement is driven in such a way that the selector valve blocks and the charging valve is opened for building up pressure, both valves block for holding pressure, and for reducing pressure, the charging valve blocks and the selector valve is opened.
With the above-described conventional devices and methods for controlling at least one operating-dynamics variable in closed loop (and the braking systems used in this context), in the event of a driver-independent brake-actuation as exists (e.g., during an ASR intervention), because of the driving of the circuit valves (i.e., the selector valve and the charging valve), pressure peaks can occur in a brake circuit while driving these valves due to the braking medium flowing into the brake circuit. These pressure peaks are not problematical in a large-volume design of the hydraulic aggregate. However, should a small-volume hydraulic aggregate be used, then greater pressure peaks can result due to the inflowing braking medium. These pressure peaks are disadvantageous for this hydraulic aggregate because of the great loading resulting from them.
One of the objects of the present invention is to provide a device and a method which make it possible to avoid high pressure peaks in the hydraulic aggregate in response to driver-independent braking interventions, thus reducing the loading of the hydraulic aggregate. Therefore, even small-volume hydraulic aggregates can be used.
SUMMARY OF THE INVENTION
The above-described pressure peaks, developing when carrying out a driver-independent braking intervention, are not problematical in large-volume hydraulic aggregates. However, should small-volume hydraulic aggregates be operated correspondingly, then the hydraulic aggregate must be driven by the appropriate controlling unit so that these pressure peaks do not occur, or occur only in reduced level. However, the full efficiency of the control is retained.
A braking system according to the present invention includes a reservoir for accommodating braking medium, and at least one brake circuit. The brake circuit contains first valve arrangements on the output side, and a second valve arrangement on the incoming side. Wheel brake cylinders allocated to the brake circuit are connected to the first valve arrangements. The reservoir is connected to the second valve arrangement. The first valve arrangement is composed in each case of a first and a second valve. The brake circuit further includes one pump. The second valve arrangement is composed in each case of a first valve, through which, in the flow-through (e.g., open) position, braking medium flows into the brake circuit in response to actuation of the pump, and of a second valve, through which, in the flow-through position, braking medium flows out of the brake circuit in response to actuation of the pump.
The device of the present invention includes means (e.g., an arrangement), with which the wheel brake cylinder exhibiting the greatest brake pressure is determined for the at least one brake circuit. During the time in which a driver-independent brake actuation exists, the first valve of the first valve arrangement is advantageously switched into the flow-through position, and the second valve of the first valve arrangement is switched into the blocking position for the wheel brake cylinder exhibiting the greatest brake pressure. Due to such driving control of the first valve arrangement, the pressure in the brake circuit corresponds to the pressure of the wheel brake cylinder exhibiting the greatest brake pressure. At the same time, the volume of the brake circuit is increased; thus possibly occurring pressure peaks cannot become all too large.
In response to a driver-independent brake actuation, in particular in response to a driver-independent build-up in brake pressure, the brake pressure of the wheel brake cylinder exhibiting the greatest brake pressure is advantageously adjusted by appropriate driving of the second valve arrangement. Due to this procedure, the first valve arrangement allocated to this wheel brake cylinder can remain in the above-described position. To adjust (in each case) the brake pressure of the remaining wheel brake cylinders of the brake circuit, the first valve arrangement allocated to the respective wheel brake cylinder is appropriately driven, in addition to the driving control of the second valve arrangement.
The first and second valve arrangements for the brake circuit are advantageously driven as follows. The respective volumetric requirement for the wheel brake cylinders allocated to the brake circuit is ascertained using appropriate means. In so doing, the respective volumetric requirement is advantageously ascertained at least as a function of the brake pressure which is adjusted in the respective wheel brake cylinder by the controlling unit on the basis of the setpoint selections. The sum of these volumetric requirements is ascertained on the basis of the individual volumetric requirements. By forming this sum, a measure is determined for ascertaining whether braking medium must be supplied to the brake circuit, or whether the braking medium must be removed from the brake circuit because of the driver-independent brake actuation. Since the second valve arrangement is co
Gerdes Manfred
Lutz Albert
Kenyon & Kenyon
Robert & Bosch GmbH
Rodriguez Pam
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