Co-ordination method for a regenerative and anti-skid braking system

1. Method for a motor vehicle with a regenerative and an anti-lock conventional brake system (ABS) for coordinating the application of the regenerative and the anti-lock system, wherein the regenerative brake system is switched off upon entry into an ABS control phase, comprising the steps of:

identifying the termination of the ABS control phase;

determining criteria representative of a braking demand and an instantaneous coefficient of friction at the termination of the ABS control phase; and

applying post ABS regenerative braking by the regenerative brake system at the termination of the ABS control phase, a value of the post ABS regenerative braking being based on the determined criteria and being in a modified form compared to a regenerative braking value prior to the entry into the ABS control phase,

wherein the regenerative brake system has a maximum regenerative braking value and the post ABS regenerative braking is limited for a given period to a predetermined limit value which is less than maximum regenerative braking value.

2. Method as claimed in claim 1 ,

wherein prior to the entry into ABS control phase, a demanded braking power is generated by the regenerative brake system until the attainment of a maximum value depending on the regenerative brake system, while the demanded braking power is generated by the conventional brake system after entry into ABS control phase.

3. Method as claimed in claim 1 ,

wherein the step of applying post ABS regenerative braking by the regenerative brake system at the termination of the ABS control phase is delayed until after expiry of a predetermined time period after the termination of the ABS control phase, and the post ABS regenerative braking is limited to a predetermined limit value and a portion of a demanded brake torque exceeding the limit value is generated by the conventional brake system.

4. Method as claimed in claim 3 ,

wherein the predetermined time period is in the order of approximately 1 to 3 seconds.

5. Method as claimed in claim 3 ,

wherein the predetermined limit value is varied in dependence on a braking pressure that prevails in a corresponding wheel brake upon termination of the ABS control phase.

6. Method as claimed in claim 3 ,

wherein the predetermined limit value is raised with a preset gradient until an allowable maximum portion of the demanded braking power is reached and the portion of the demanded brake torque exceeding the limit value is generated by the conventional brake system.

7. Method as claimed in claim 6 ,

wherein following a predetermined waiting time after attainment of the allowable maximum portion of the demanded braking power, a rise of the allowable maximum portion with a predetermined gradient is raised until a maximum output of the regenerative brake system is reached, and the portion of the demanded brake torque exceeding the braking power of the regenerative brake system is generated by the conventional brake system.

8. Method as claimed in claim 1 ,

wherein in a vehicle with only one driven axle, a brake force distribution is shifted in favor of the driven axle when a demanded braking power of the driven axle can be generated by the regenerative brake system.

9. Method as claimed in claim 1 ,

wherein upon a new entry into an ABS control phase after a transition into phases with regenerative braking, a new transition into phases with regenerative braking is prevented.

10. Method as claimed in claim 1 ,

wherein upon a new entry into an ABS control phase after a transition into phases with regenerative braking, a new transition into phases with regenerative braking is delayed.

11. Method as claimed in claim 1 ,

wherein the predetermined limit value is approximately 80% or less than maximum regenerative braking value.