Method for adjusting brake pressures of a vehicle, and brake system for carrying out the method

Patent metadata

Field	Value
Publication number	US-10377356-B2
Application number	US-201616060029-A
Country	US
Kind code	B2
Filing date	Nov 17, 2016
Priority date	Dec 9, 2015
Publication date	Aug 13, 2019
Grant date	Aug 13, 2019

Abstract

A method for adjusting brake pressures at pneumatically actuated wheel brakes of a vehicle includes, after an external braking demand, continuously ascertaining, by a brake control unit, in a pressure control mode, at least one differential slip value from measuring signals supplied by speed sensors of the wheels, as the difference between the slip of two axles of the vehicle before releasing the control signals; evaluating the differential slip value with consideration for a predefined or adjustable setpoint differential slip value; and depending on the evaluation, bringing the differential slip value closer to the setpoint differential slip value by adapting at least one control signal.

First claim

The invention claimed is:

1. A method for adjusting brake pressures at pneumatically actuated wheel brakes of a vehicle, wherein the brake pressures at the wheel brakes are adjusted in a normal braking mode depending on a driver's braking demand determined by a driver of the vehicle, and wherein, when an external braking demand independent of the driver's braking demand is received and/or when certain wheels tend to lock, a brake control unit takes over adjustment of the brake pressures in a pressure control mode, wherein the brake control unit, in the pressure control mode, ascertains control signals for pressure control valves of the particular wheel brakes and changes the brake pressures of the relevant wheel brake by controlling the pressure control valves, the method comprising:
after an external braking demand, continuously ascertaining, by the brake control unit, in the pressure control mode, at least one differential slip value from measuring signals supplied by speed sensors of the wheels, as the difference between the slip of two axles of the vehicle before releasing the control signals;
evaluating the differential slip value with consideration for a predefined or adjustable setpoint differential slip value; and
depending on the evaluation, bringing the differential slip value closer to the setpoint differential slip value by adapting at least one control signal,
wherein the brake control unit evaluates the at least one ascertained differential slip value with consideration for at least one control intervention criterion and, depending on fulfillment of the at least one control intervention criterion, releases the control signals or adapts at least one control signal for readjusting the differential slip value, and
wherein at least one slip threshold value is specified to the brake control unit as a control intervention criterion for evaluation of the differential slip value and, if the slip threshold value is exceeded, an adaptation of the distribution of brake pressure to the axles takes place.

2. The method as claimed in claim 1 , wherein during the readjustment of the differential slip value in order to increase a brake pressure of a wheel brake, a control signal of an inlet valve of a particular pressure control valve, and/or in order to decrease a brake pressure, a control signal of an outlet valve of the particular pressure control valve and/or a control signal of an inlet valve or outlet valve acting on a wheel brake of a particular other axle is changed.

3. The method as claimed in claim 1 , wherein the brake control unit reduces a brake pressure at an axle of a compared pair of axles having a greater slip, with consideration for the evaluation of the differential slip value.

4. A method for adjusting brake pressures at pneumatically actuated wheel brakes of a vehicle, wherein the brake pressures at the wheel brakes are adjusted in a normal braking mode depending on a driver's braking demand determined by a driver of the vehicle, and wherein, when an external braking demand independent of the driver's braking demand is received and/or when certain wheels tend to lock, a brake control unit takes over adjustment of the brake pressures in a pressure control mode, wherein the brake control unit, in the pressure control mode, ascertains control signals for pressure control valves of the particular wheel brakes and changes the brake pressures of the relevant wheel brake by controlling the pressure control valves, the method comprising:
after an external braking demand, continuously ascertaining, by the brake control unit, in the pressure control mode, at least one differential slip value from measuring signals supplied by speed sensors of the wheels, as the difference between the slip of two axles of the vehicle before releasing the control signals;
evaluating the differential slip value with consideration for a predefined or adjustable setpoint differential slip value; and
depending on the evaluation, bringing the differential slip value closer to the setpoint differential slip value by adapting at least one control signal,
wherein the brake control unit evaluates the at least one ascertained differential slip value with consideration for at least one control intervention criterion and, depending on fulfillment of the at least one control intervention criterion, releases the control signals or adapts at least one control signal for readjusting the differential slip value, and
wherein a tolerance range comprising an upper slip threshold value and a lower slip threshold value is specified to the brake control unit as a control intervention criterion for the evaluation of the differential slip value and, if the upper slip threshold value is exceeded or the lower slip threshold value is fallen below, an adaptation of the distribution of brake pressure to the axles takes place.

5. The method as claimed in claim 4 , wherein a first tolerance range having slip threshold values is specified for a braking operation having active retarders and a second tolerance range having slip threshold values is specified for a braking operation without retarders.

6. The method as claimed in claim 1 , wherein differential slip values are determined for multiple axles, in each case based on a reference axle taken into account in all axle pairs.

7. The method as claimed in claim 1 , wherein the differential slip value is controlled with the predefined or adjustable setpoint differential slip value as the guide variable.

8. The method as claimed in claim 1 , wherein the setpoint differential slip value is specified depending on a braking demand resulting from an external braking demand and a driver's braking demand.

9. The method as claimed in claim 1 , wherein the setpoint differential slip value is specified depending on an actual deceleration of the vehicle.

10. A method for adjusting brake pressures at pneumatically actuated wheel brakes of a vehicle combination including a motor vehicle and at least one towed vehicle, wherein the brake pressures at the wheel brakes are adjusted in a normal braking mode depending on a driver's braking demand determined by a driver of the vehicle, and wherein, when an external braking demand independent of the driver's braking demand is received and/or when certain wheels tend to lock, a brake control unit takes over adjustment of the brake pressures in a pressure control mode, wherein the brake control unit, in the pressure control mode, ascertains control signals for pressure control valves of the particular wheel brakes and changes the brake pressures of the relevant wheel brake by controlling the pressure control valves, the method comprising:
after an external braking demand, continuously ascertaining, by the brake control unit, in the pressure control mode, at least one differential slip value from measuring signals supplied by speed sensors of the wheels, as the difference between the slip of two axles of the vehicle before releasing the control signals;
evaluating the differential slip value with consideration for a predefined or adjustable setpoint differential slip value; and
depending on the evaluation, bringing the differential slip value closer to the setpoint differential slip value by adapting at least one control signal,
wherein differential slip values are determined for multiple axles, in each case based on a reference axle taken into account in all axle pairs, and
wherein a trailer axle having a least slip at the moment is continuously determined at a present control axle from measuring signals of speed sensors of wheels of the towed vehicle,
wherein a trailer differential slip value is ascertained for the control axle according to the difference of the slip of the reference

Assignees

• Wabco Gmbh

Inventors

• Eckert Horst

Classifications

• B60T8/172

  Determining control parameters used in the regulation, e.g. by calculations involving measured or detected parameters {(B60T8/17551 takes precedence)} · CPC title

• B60T8/1708

  for lorries or tractor-trailer combinations · CPC title

• B60T8/171

  Detecting parameters used in the regulation; Measuring values used in the regulation · CPC title

• B60T8/17616 Primary

  Microprocessor-based systems · CPC title

• B60T15/043

  controlling service pressure brakes (B60T15/048 takes precedence) · CPC title