Fluid-pressure and analogous brake systems – With pump – Pressure control
Patent
1998-02-02
2000-09-26
Oberleitner, Robert J.
Fluid-pressure and analogous brake systems
With pump
Pressure control
3031161, 303155, B60T 1318
Patent
active
061233951
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a method and a device for determining a pressure variable, in particular a differential pressure in a braking system equipped with anti-lock and/or traction control.
BACKGROUND INFORMATION
International Patent Application No. 94/18041 describes a method and a circuit arrangement for determining the force exerted on the pedal as a controlled variable for a braking system equipped with anti-lock control. The braking system includes, inter alia, a hydraulic pump. The hydraulic pump is used to recirculate pressurized media that had been drawn from the wheel brake to reduce pressure. On the other hand, the hydraulic pump is used to supply auxiliary pressure. In the method described in International Patent Application No. 94/18041, during a closed-loop control braking, the drive motor of a hydraulic pump is switched over to generator operation, and the level of the generator voltage and its decay behavior are evaluated. From the generator voltage and the decay behavior, one is able to determine by approximation the initial pressure that is a function of the force exerted on the pedal.
German Patent Application No. 38 19 490 A1 describes a pump system of a hydraulic final controlling element for adjusting a movable member of an object. This object is, for example, a brake of an anti-lock control system of a motor vehicle. The pump system has an electromotor for driving a pump, which is used to exert influence on a hydraulic fluid pressure. In addition, the pump system comprises a testing device for determining the pressure of the hydraulic fluid and, thus, for monitoring the performance reliability of the hydraulic. In this context, the pressure is not measured with the aid of a sensor, but rather using as a baseline the detected engine speed, the detected active current consumption of the electromotor, and the active operating voltage at the electromotor. Using as a baseline the determined pressure value of the hydraulic fluid, the electromotor is driven, i.e., the performance reliability of the hydraulic is monitored. In addition, German Patent Application No. 38 19 490 A1 describes a method of determining the torque of the electromotor using the motor voltage and the motor current as a baseline.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an optimal method and an optimal device which defines a pressure, variable, in particular the differential pressure in a braking system equipped with anti-lock and/or traction control, without any sensors for detecting the pressure.
The device and the method of the present invention enables the differential pressure, in particular in a braking system equipped with anti-lock and/or traction control, to be determined in an inexpensive and uncomplicated manner.
As a result, it would be possible to detect differential pressures without using expensive sensors. The driving of the discharge and, in particular, the intake valves is optimized, which automatically leads to an improvement in the control response, in that the differential pressure is taken into consideration in the driving of the discharge or intake valves.
A further advantage is attained when working with so-called cadence braking. Cadence braking is at hand when the driver causes considerable variations in initial pressure PV. Using the above estimation of the differential pressure, the drop in initial pressure can be simply detected, and the ABS control modified accordingly.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a scheme of the essential elements of a device according to the present invention.
FIG. 2 shows a block diagram for driving a return pump.
FIG. 3 shows a voltage applied to the return pump plotted over time.
FIGS. 4a-4d shows various signals as a function of each other.
DETAILED DESCRIPTION OF THE INVENTION
It is known to use electrically actuated intake and discharge valves to modulate the pressure prevailing in the individual wheel brakes of a vehicle equipped with anti-lock and/or traction control. F
REFERENCES:
patent: 5273348 (1993-12-01), Yagi et al.
patent: 5487593 (1996-01-01), Potts et al.
patent: 5623531 (1997-05-01), Batistic et al.
Eshbach's Handbook of Engineering Fundamentals Fourth Edition, Byron Tapley (editor), pp. 8-98-8-99, Published by John Wiley & Sons, Inc., Dec. 1990.
Binder Jurgen
Wiss Helmut
Wolf Michael
Oberleitner Robert J.
Robert & Bosch GmbH
Siconolfi Robert A.
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