Controlling an electrically actuable parking brake in the event of failure of a speed signal

1. A method of controlling an electrically actuable parking brake of a motor vehicle comprising the steps of:

determining an absence of a first signal indicating a speed of the motor vehicle;

closing continuously the parking brake as long as a second signal indicating a driver request to close the parking brake is detected; and

opening the parking brake if an absence of the second signal is detected, provided that the parking brake is in a partially open state;

wherein the parking brake upon detecting the second signal is continuously closed until a closing force reaches a maximum closing force;

wherein the parking brake is maintained in the fully closed state, provided that the parking brake in the absence of the second signal is in the fully closed state; and

wherein the absence of the first signal is determined if no first signal is available or the first signal is implausible or undefined.

2. The method according to claim 1 , further comprising fully opening the parking brake if the second signal is not detected during the opening.

3. The method according to claim 1 , wherein the continuous closing comprises a continuous closing at a limited closing speed.

4. The method according to claim 3 , wherein the closing speed is substantially constant.

5. The method according to claim 3 , wherein the closing speed varies substantially linearly.

6. The method according to claim 1 , further comprising opening the parking brake situated in a fully closed state if the presence of a third signal indicating a driver request to open the parking brake is given.

7. The method according to claim 1 , wherein the parking brake comprises a plurality of groups of actuators, wherein the closing of the parking brake comprises increasing the brake force of the actuators of at least a first group and maintaining the brake force of the actuators of at least a second group.

8. The method according to claim 1 , further comprising determining a state of motion of the motor vehicle on the basis of the first signal.

9. The method according to claim 8 , wherein the motor vehicle is in a stationary state, and further comprising fully closing the parking brake if at least temporarily the second signal is detected.

10. A computer program product having program code means for executing a method according to claim 1 when the computer program product is running at a processing module.

11. The computer program product according to claim 10 , when it is stored on a computer-readable data carrier.

12. A device for controlling an electrically actuable parking brake of a motor vehicle in the event of an absence of a first signal indicating a speed of the motor vehicle, comprising:

a first determination device for determining an absence of a first signal indicating a speed of the motor vehicle;

a detection device for detecting a second signal indicating a driver request to close the parking brake;

a second determination device for determining a partially open state of the parking brake;

a closing device for continuously closing the parking brake as long as the second signal is detected; and

an opening device for opening the parking brake if the second signal is absent, provided that the parking brake is in a partially open state;

wherein the closing device is adapted upon detection of the second signal to continuously close the parking brake until a closing force reaches a maximum closing force; and to maintain the parking brake in the fully closed state, provided that the parking brake in the absence of the second signal is in the fully closed state; and

wherein the absence of the first signal is determined if no first signal is available or the first signal is implausible or undefined.

13. The device according to claim 12 , further comprising a third determination device for determining a state of motion of the motor vehicle.

14. The device according to claim 12 , wherein the parking brake comprises a plurality of groups of actuators and the opening and closing devices are configured to actuate the actuators of at least two groups independently of one another.

15. A method of controlling an electrically actuable parking brake of a motor vehicle comprising the steps of:

closing continuously the parking brake as long as a signal indicating a driver request to close the parking brake is detected; and

opening the parking brake if an absence of the signal is detected, provided that the parking brake is in a partially open state; wherein

the parking brake upon detecting the signal is continuously closed until a closing force reaches a maximum closing force; wherein

the parking brake is maintained in the fully closed state, provided that the parking brake in the absence of the signal is in the fully closed state; and wherein

the continuous closing comprises a continuous closing at a limited closing speed.

16. A method of controlling an electrically actuable parking brake of a motor vehicle comprising the steps of:

closing continuously the parking brake as long as a signal indicating a driver request to close the parking brake is detected; and

opening the parking brake if an absence of the signal is detected, provided that the parking brake is in a partially open state; wherein

the parking brake upon detecting the signal is continuously closed until a closing force reaches a maximum closing force; wherein

the parking brake is maintained in the fully closed state, provided that the parking brake in the absence of the signal is in the fully closed state; and wherein

the parking brake comprises a plurality of groups of actuators, wherein the closing of the parking brake comprises increasing the brake force of the actuators of at least a first group and maintaining the brake force of the actuators of at least a second group.