DE19837373B4 - Method for anti-lock and / or traction slip control - Google Patents

Abstract

method for anti-lock and / or traction control (ABS and / or ASR), in which the rotational behavior of the vehicle wheels axle and / or individual wheel determined and to form a vehicle reference speed and for generating brake pressure or brake force control signals is evaluated, in the normal case of a forward drive is assumed, characterized in that both the rotational behavior (Speed, speed change etc.) as well as the Direction of rotation of the wheels or direction of travel of the vehicle are determined and that when reversing is switched to a special control mode, in which the control is adapted by redefinition of the axes of the changed direction.

Description

The The invention relates to methods for anti-lock and / or Traction control (ABS and / or ASR), in which the rotational behavior the vehicle wheels determined axle and / or individual wheel and to form a vehicle reference speed and for generating brake pressure or brake force control signals is evaluated, in the normal case of a forward drive is assumed.

From the DE 39 42 547 A1 Among other things, an ABS and / or ASR system emerges, which can also determine the direction of rotation of the wheels in the control with a fiber-optic sensor described in detail. To what extent this principle possibility can also be used for an ABS system remains unmentioned.

The DE 38 29 024 A1 discloses a traction assist device having a rotary sensor which detects a backward movement of the vehicle and as a result of which, in a suitable manner for preventing the rolling back, sets a predetermined braking force into a braking device.

Of the Invention is the object of such a method crucial to improve. It has been found that this is with the appended claim 1 described method succeeds. Advantageous embodiments are in the subclaims described.

conventional (usually passive) sensors provide only an absolute speed signal without direction information. New (active sensors) set Signal over the direction of rotation (forward / backward) to Available.

These additional Information enabled the improvement of various functions in the field of electronic Regulated brake systems, or the solution of existing problems:

1. ABS

Problem:

at reverse braking So far there is a lack of braking power and insufficient stability. causes therefor are that (1.) when driving backwards stronger dynamically loaded rear axle regulated according to the select low principle and thus the maximum possible Braking power is not fully exhausted and (2.) the dynamically relieved front axle is individually controlled which leads to a reduction in lateral force. Because of the excess required for stability at cornering power becomes common controlled at the rear axle to select low, when reversing This condition is reversed. The because of the then back Steering particularly high required cornering force can because of the individual brake pressure optimization can not be provided causing massive instability to lead can.

Solution:

With Help the direction of rotation information can be a "redefinition" of the axes. That the front axle becomes the rear axle and thus to select low regulated to the necessary Build side managers to be able to; the rear axle is regulated to the front axle and wheel-individually, to achieve the maximum braking power.

2.BASR

Problem 1:

At the Starting on a slope occasionally rolls back the vehicle before or despite the BASR intervention. The non-driven Axis then supplies a speed signal because of the missing Direction information can be interpreted as "forward" got to. The derived reference signal from this signal is wrong. Leading to the assumption that that Vehicle accelerates, traction and thus the effectiveness of Regulation is good, which is not the case, and a worse one Control quality, because the set slip is too high.

Solution 1:

• a) With knowledge of the direction of rotation, the reference speed be assigned a direction of rotation information (sign). The Regulation is then always based on a correct reference value, which leads to a significant improvement in traction.
• b) If rewinding is detected (or rolling in the opposite direction to the spinning, driven wheels), it is possible to actively brake in the non-driven wheels. For this purpose, an HCU is required, which can build up individual pressure on all wheels, eg an ESP HCU. This prevents unwanted acceleration of the vehicle in the direction opposite to the desired direction of travel. At the same time, the engine torque is increased in order to obtain sufficient torque for starting. After a corresponding build-up of pressure in the brake of the spinning wheel, then sufficient driving force is on the opposite side Side available to accelerate the vehicle against the downgrade, so that the additional brake pressure on the non-driven axle can be removed again. Rolling back due to slow pressure build-up or low engine torque is thereby effectively avoided.

Problem 2:

Scenario: At e.g. forward downhill rolling vehicle is trying to drive backwards. The drive wheels change their Direction of rotation, which interprets as brake slip when using "old" sensors is because the zero crossing of the speed signal due to the missing sign (direction of rotation) not as acceleration in the desired Direction, but is recognized as a decrease in speed. It comes as a result, to an ABS control intervention, the ASR and BASR function prevented (safety concept: braking has priority over acceleration). Only after crossing the reference speed amount in the other direction the control can become active again.

Solution 2:

at Knowledge of the direction of rotation, the ASR / BASR control already directly be initiated after detecting the reversal of direction and so the traction earlier be increased.

Claims (4)

Method for anti-lock and / or traction slip control (ABS and / or ASR), in which the rotational behavior of the vehicle wheels determined axi- and / or individual wheel and is evaluated to form a vehicle reference speed and for generating brake pressure or brake force control signals, in the normal case of a Forward travel is assumed, characterized in that both the rotational behavior (speed, speed change, etc.) and the direction of rotation of the wheels or direction of travel of the vehicle are determined and that is reversed when reversing in a special control mode in which the control by redefinition of the Axes adapted to the changed direction. Method according to claim 1, characterized in that that in the Normally the front wheels individually and the rear wheels according to the selection principle select-low, on the other hand in the special control mode the front wheels after select-low, the rear wheels be individually regulated. Method according to claim 1 or 2, characterized that the Redefinition of the axes also the formation of the vehicle reference speed affected. Method according to one or more of claims 1 to 3, characterized in that at rolling back of the vehicle of a BASR intervention (BASR = ASR through brake intervention) actively braked is and / or the engine torque is increased.