Method and device for electronically controlling a vehicle deceleration in an ABS braking system

1. A method for controlling a vehicle deceleration in a vehicle comprising an ABS braking system, the method comprising:

detecting a setpoint vehicle deceleration predetermined by a driver;

establishing a maximum deceleration and a minimum deceleration, in each case as a function of the detected setpoint vehicle deceleration;

detecting an actual vehicle deceleration; and

controlling, as a function of the detected actual vehicle deceleration, respective brake pressures at wheel brakes of a vehicle axle by controlling ABS brake valves so as to:

increase the respective brake pressures at the wheel brakes of the vehicle axle when the actual vehicle deceleration is less than the minimum deceleration thereby achieving a minimum braking effect at the vehicle axle, and

limit the respective brake pressures at the wheel brakes of the vehicle axle when the actual vehicle deceleration is greater than the maximum deceleration thereby limiting the braking effect at the vehicle axle.

2. The method as claimed in claim 1 , wherein the maximum deceleration is established based on a maximum deceleration characteristic curve that represents a dependence of the maximum deceleration on the setpoint vehicle deceleration, and

wherein the minimum deceleration is established based on a minimum deceleration characteristic curve that represents a dependence of the minimum deceleration on the setpoint vehicle deceleration.

3. The method as claimed in claim 2 , wherein the maximum deceleration characteristic curve is dependent on a load of the vehicle.

4. The method as claimed in claim 3 , wherein the load of the vehicle is measured with aid of an axle load sensor or is derived from a detected actual differential slip.

5. The method as claimed in claim 3 , wherein a gradient of the maximum deceleration characteristic curve is inversely proportional to the load of the vehicle, and so the respective brake pressures are limited in the case of a low load of the vehicle given higher detected actual vehicle decelerations in contrast to a high load of the vehicle.

6. The method as claimed in claim 2 , wherein the maximum deceleration characteristic curve has a harmonic course without steps, in order to limit the respective brake pressures without jerkily decelerating the vehicle.

7. The method as claimed in claim 1 , wherein the respective brake pressures at the wheel brakes of the vehicle axle are held or reduced when the actual vehicle deceleration is greater than the maximum deceleration.

8. The method as claimed in claim 1 , wherein the respective brake pressures at the wheel brakes of the vehicle axle are controlled as a function of a detected actual differential slip when the actual vehicle deceleration is less than the maximum deceleration and greater than the minimum deceleration, wherein the actual differential slip indicates a difference in a rotational behavior of the vehicle axle with respect to another vehicle axle.

9. The method as claimed in claim 8 , wherein the actual differential slip is calculated from the difference of an ascertained rear axle brake slip minus an ascertained front axle brake slip normalized to the rear axle brake slip, or a difference of an ascertained front axle axle-speed minus an ascertained rear axle axle-speed normalized to the front axle axle-speed, wherein the rear axle is the vehicle axle driven by an engine.

10. The method as claimed in claim 8 , wherein the respective brake pressures are controlled as a function of the actual differential slip in such a way that the actual differential slip corresponds to a setpoint differential slip, wherein the respective brake pressures at the wheel brakes of the vehicle axle are limited for this purpose when the vehicle axle is over-braked relative to the other vehicle axle, and is increased for this purpose when the vehicle axle is under-braked relative to the other vehicle axle.

11. The method as claimed in claim 8 , wherein the respective brake pressures at the wheel brakes of the vehicle axle are reduced as a function of the actual differential slip when the actual vehicle deceleration is greater than the maximum deceleration and the vehicle axle is over-braked relative to the other vehicle axle.

12. The method as claimed in claim 10 , wherein the setpoint differential slip is dependent on the detected actual vehicle deceleration or the setpoint vehicle deceleration, wherein, in the case of an increasing actual vehicle deceleration or an increasing setpoint vehicle deceleration, the setpoint differential slip decreases in the direction of a synchronous wheel rotational behavior of the wheels of the vehicle axle and of the other vehicle axle, and so the respective brake pressures at the vehicle axle are already limited in the event of a lower relative over-braking.

13. The method as claimed in claim 10 , wherein, if the vehicle axle is the rear axle, respective brake pressures at the rear wheel brakes are limited when the actual differential slip is greater than the setpoint differential slip, and are increased when the actual differential slip is less than the setpoint differential slip, and

wherein if the vehicle axle is the front axle, respective brake pressures at the front wheel brakes are limited when the actual differential slip is less than the setpoint differential slip, and are increased when the actual differential slip is greater than the setpoint differential slip.

14. The method as claimed in claim 1 , wherein the vehicle axle is a rear axle of the vehicle or a front axle of the vehicle.

15. The method as claimed in claim 1 , wherein, in the event that the respective brake pressures of the wheel brakes of the vehicle axle are limited, the respective brake pressures are held or reduced and are not increased.

16. A device for electronically controlling a vehicle deceleration in a vehicle comprising an ABS brake system, the device being configured to:

establish a maximum deceleration and a minimum deceleration as a function of a detected setpoint vehicle deceleration, the setpoint vehicle deceleration being predetermined by a driver; and

control, as a function of a detected actual vehicle deceleration, respective brake pressures at wheel brakes of a vehicle axle by controlling ABS brake valves so as to:

increase the respective brake pressures at the wheel brakes of the vehicle axle when the actual vehicle deceleration is less than the minimum deceleration thereby achieving a minimum braking effect at the vehicle axle, and

limit the respective brake pressures at the wheel brakes of the vehicle axle when the actual vehicle deceleration is greater than the maximum deceleration thereby limiting the braking effect at the vehicle axle.

17. The device as claimed in claim 16 , wherein the vehicle axle is a rear axle or a front axle of the vehicle.

18. A vehicle comprising a brake system, the brake system comprising:

a brake valve configured to deliver a brake pressure at wheel brakes of the vehicle;

a brake signal transmitter for detecting a setpoint vehicle deceleration;

a detecting sensor configured to detect an actual vehicle deceleration;

ABS brake valves; and

a device for electronically controlling a vehicle deceleration in a vehicle comprising an ABS brake system, the device being configured to:

establish a maximum deceleration and a minimum deceleration as a function of a detected setpoint vehicle deceleration, the setpoint vehicle deceleration being predetermined by a driver; and

control, as a function of a detected actual vehicle deceleration, respective brake pressures at wheel brakes of a vehicle axle by controlling ABS brake valves so as to:

increase the respective brake pressures at the wheel brakes of the vehicle axle when the actual vehicle deceleration is less than the minimum deceleration thereby achieving a minimum braking effect at the vehicle axle, and

limit the respective brake pressures at the wheel brakes of the vehicle axle when the actual vehicle deceleration is greater than the maximum deceleration thereby limiting the braking effect at the vehicle axle.