DE9214051U1 - Traction control system - Google Patents

Description

R.25581

29.9.1992 Ka/Kl/Si

ROBERT BOSCH GMBH, 7000 STUTTGART 30

Traction control system
State of the art

A traction control system with the features of the preamble of claim 1 is known from DE 39 32 567 A1. There, the gradient of the pulsed pressure build-up is also dependent on the vehicle deceleration. According to one embodiment, the gradient change is carried out by continuously changing the pause times of the pulsed pressure build-up as a function of /\ v.

Advantages of the invention

The innovative solution allows for very long pressure holding phases to occur by dimensioning the width of the bands, which significantly reduces the valve switching frequency. Due to the low pressure pulsation, the steering wheel reaction is very low in front-wheel drive vehicles.

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Character description

An example of the innovation is described with the help of the drawing. Figure 1 shows a block diagram, Figure 2 a diagram.

Figure 1 of the drawing shows a block diagram of an ASR of the new design. Wheel speed sensors assigned to the driven wheels are designated l and 2. Their signals are compared in a comparator 3. This emits a signal /\ v that corresponds to the amount of the difference between the sensor signals. This signal is fed to blocks 4a to 4h, which only use the supplied signal if it lies between the predetermined limit values of the bands assigned to blocks 4. For example, block 4a only uses the Δ v signal if it is equal to or greater than an initial threshold La of, for example, 1 km/h and less than 4 km/h. Block 4b uses the signal if 4 < Δ v <. 8, etc. Finally, block 4h uses the signal δ v if Δ v >. 32 km/h. Block 4, which evaluates the signal Δν that is currently present, sends a signal to a pulse generator and uses its signal to determine the length of the pause times of the pressure build-up pulse series emitted by the pulse generator. The pulse width itself is constant and, for example, 10 ms wide. The pause times assigned to the individual bands or blocks 4 can be seen in Figure 2, where an assumed course of ^Jν is drawn. It can be seen that control only begins after an initial threshold La has been exceeded and that only the pause times listed in the drawn bands are effective.

The sign of Ji v supplied by the comparator 3 via a line 6 informs the pulse generator which wheel is faster

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It then sends its pulse build-up series to one of the valves 7a or 7b, which is assigned to the faster wheel and is thus braked. '

The pressure build-up is terminated when Δν moves from a slip band with a larger La + xn to a slip band with a smaller La + x(nl). The pause is then extended until the slip band La + xn is reached again (pressure build-up is continued) or until the pressure reduction condition ( Δν < La) is met.

When finally \ J^ v| < La, a block 8 switches off the pressure build-up. The pressure reduction can be carried out as shown in DE 39 32 567 A1.

Claims (3)

R. 25581 29.9.1992 Ka/Kl/Si ROBERT BOSCH GMBH, 7000 STUTTGART 30 Claims 1. Traction control system in which the wheel rotation speeds of the driven wheels of an axle are compared with one another and the deviation ^J v is used to vary the gradient of the pulsed pressure build-up, with a larger gradient of the pressure build-up being set as ^f v increases, characterized in that above a predetermined minimum threshold of the deviation Δ v, successive bands for the control deviation are predetermined, and that gradient values are assigned to these bands. 2. Traction control system according to claim 1, characterized in that the gradient is varied by changing the pause times at constant pulse times, with predetermined pause times being assigned to the bands. 3. Traction control system according to one of claims 1 or 2, characterized in that the pressure build-up is terminated when /1 ν passes from a band with a shorter pause time into the subsequent band with a longer pause time.