Fluid-pressure and analogous brake systems – Speed-controlled – And traction control
Patent
1995-06-30
1996-11-12
Oberleitner, Robert J.
Fluid-pressure and analogous brake systems
Speed-controlled
And traction control
303142, 180197, 36442602, B60T 800
Patent
active
055733158
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a drive slip control system of the type in which brake pressure is fed to the driven wheels on the appearance of drive slip. A system of this type is disclosed in DE 36 34 240, to which U.S. Pat. No. 5,164,902 corresponds.
The variation in brake pressure which is proportional to the drive, as achieved by the invention, avoids an excessive brake pressure which is based on the slip and can stall the engine. Where the invention is applied, it may be possible to dispense with influencing the engine torque .
BRIEF DESCRIPTION OF THE DRAWING
The sole FIGURE is a diagram of the inventive system.
PREFERRED EMBODIMENT
In FIG. 1 of the drawing, the speed sensors 1 and 2 are associated with the non-driven wheels of a vehicle are and the sensors 3 and 4 are associated with the driven wheels. When the driven wheels tend to spin, a control unit 5 generates brake pressure control signals from the signals of the sensors 1 to 4 and these control signals are supplied to the inlet valves 6 and 8 and the outlet valves 7 and 9 associated with the wheel brakes of the driven wheels. If no valve is activated, the pressure is kept constant. If an inlet valve 6 or 8 is activated, a pressure source is connected to a wheel brake and if an inlet valve and an outlet valve are activated, pressure reduction takes place at the wheel brake.
In order to avoid an excessively high brake pressure being fed in and to avoid the engine being stalled by the drive-slip control system, the arrangement now to be described is provided. In computational circuits 10a and 10b, the braking torques M.sub.Br for the two driven wheels are determined from a constant K, which is specific to the vehicle, and the number of pressure build-up and reduction pulses which has been determined according to DE 41 23 783, which corresponds to PCT/DE 92/00503 designating the United States, incorporated herein by reference. A computational circuit 11 correspondingly determines the drive torque M.sub.A from the engine rotational speed, the gearbox transmission ratio, the throttle butterfly angle and mass volumetric efficiency parameters.
The corresponding relationships are
In these relationships, A.sub.w is the effective area, r the effective radius, P the pressure, .theta..sub.ges the moment of inertia of the drive train, w, the angular acceleration and .eta. the efficiency (for example 0.8).
The braking torque must not exceed the drive torque. In consequence, it is possible to determine a maximum braking torque variation M.sub.Br max which permits no braking torque at idling rotational speed and permits an increase in the braking torque as the drive torque increases.
The maximum brake pressure is only achieved at a drive torque which is required to drive away on a slope which has been determined or with a corresponding acceleration. This maximum braking torque M.sub.Br max is defined as follows: ##EQU1##
In this, K.sub.1 and K.sub.2 are constant; K.sub.1 has a value which corresponds to a drive torque typical of drive-slip control systems on slopes and which is intended to ensure that there is more drive torque than braking torque (for example 200 Nm) and which takes on a different value in the case of select-high operation (differential lock function); K.sub.2 determines the degree of increase in the brake pressure, is selected to suit the specific gear and engine and is, for example, 5 Nm.
The empirically determined variation of M.sub.Br max, as explained above, is stored in blocks 12a and 12b, i.e. the blocks 12 provide the maximum braking torque M.sub.Br max applicable to the particular drive torque M.sub.A. The braking torques M.sub.Br determined are compared with the maximum braking torque M.sub.Br max in comparators 13a and 13b and an output signal is generated on one of the lines 14a and 14b whenever M.sub.Br of one of the wheels reaches the value of M.sub.Br max. The corresponding AND gate 15 is therefore shut off and the pressure reached is held.
If the braking torque M.sub.Br exceeds the maximum brakin
REFERENCES:
patent: 4643485 (1987-02-01), Leiber
patent: 4765430 (1988-08-01), Schulze et al.
patent: 4766972 (1988-08-01), Takata et al.
patent: 4939656 (1990-07-01), Hoashi et al.
patent: 4946015 (1990-08-01), Brouslski et al.
patent: 4987966 (1991-01-01), Fujita
patent: 5164902 (1992-11-01), Kopper et al.
patent: 5366282 (1994-11-01), Schmitt et al.
Donath Ralf
Schmitt Johannes
Oberleitner Robert J.
Poon Peter M.
Robert & Bosch GmbH
LandOfFree
System for preventing slip of driven wheels does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with System for preventing slip of driven wheels, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and System for preventing slip of driven wheels will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-557862