Method for determining the temperature of a wheel-braking device of a brake system

1. A method for determining temperature of a wheel-braking device of a brake system in a vehicle, which braking device includes a brake disc and a brake caliper, said method comprising:

determining current disc temperature (T disc, current ) of the brake disc as a function of a last-determined disc temperature (T disc, old ), energy (E friction, disc ) supplied to the brake disc since determination of the last-determined disc temperature, and energy (E disc, dis ) discharged by the brake disc since determination of said last-determined disc temperature; and

determining current caliper temperature (T caliper, current ) of the brake caliper of the wheel-braking device as a function of the current disc temperature (T disc, current ) of the brake disc.

2. The method according to claim 1 , wherein the energy (E friction, disc ) supplied to the brake disc is determined as a function of a set brake pressure (p) at the wheel-braking device.

3. The method according to claim 1 , wherein the energy (E friction, disc ) supplied to the brake disc is determined as a function of wheel speed (V wheel ) of an assigned vehicle wheel or of vehicle speed (V veh ).

4. The method according to claim 1 , wherein the energy (E friction, disc ) supplied to the brake disc is determined as a function of a first factor (k disc, 1 ) which is in turn dependent on currently set brake pressure (p) at the wheel-braking device.

5. The method according to claim 4 , wherein the first factor (k disc, 1 ) depends on at least one of a last-determined disc temperature (T disc, old ) and a last-determined caliper temperature (T caliper, old ).

6. The method according to claim 1 , wherein energy (E disc, dis ) discharged by the brake disc is determined from a sum of energy (E disc-vicinity ) discharged to ambient environment by the brake disc and energy (E disc-caliper ) discharged from the brake disc to the brake caliper.

7. The method according to claim 6 , wherein only energy discharged by convection is taken into account in determining the energy (E disc, dis ) discharged by the brake disc.

8. The method according to claim 1 , wherein current caliper temperature (T caliper, current ) is determined as a function of energy (E caliper-vicinity ) discharged to ambient environment by the brake caliper and one of energy (E disc-caliper ) supplied to the brake caliper by the brake disc and energy (E caliper-disc ) discharged from the brake caliper to the brake disc.

9. The method according to claim 8 , wherein one of the energy (E disc-caliper ) discharged from the brake disc to the brake caliper and the energy (E caliper-disc ) discharged from the brake caliper to the brake disc is determined as a function of a temperature difference between last-determined disc temperature (T disc, old ) and last-determined caliper temperature (T caliper, old ).

10. The method according to claim 1 , wherein a warning signal is transmitted to a driver of the vehicle when current disc temperature (T disc, current ) exceeds a predeterminable maximum value (T disc, max ), without interruption, for a predeterminable time duration (T D ).

11. The method according to claim 1 , wherein a warning signal is transmitted to a driver of the vehicle when current caliper temperature (T caliper, current ) exceeds a predeterminable maximum value (T caliper, max ).

12. The method according to claim 1 , wherein when an ignition of the vehicle is switched off, a disc switch-off temperature (T disc, off ) and a switch-off temperature (T HA, off ) of a hydraulic assembly of the brake system are stored.

13. The method according to claim 12 , wherein when the ignition of the vehicle is switched on, a disc switch-on temperature (T disc, on ) is determined, which corresponds to ambient temperature if, when the ignition is switched on, a switch-on temperature (T HA, on ) of the hydraulic assembly is lower than the stored switch-off temperature (T HA, off ) of the hydraulic assembly and if the switch-on temperature (T HA, on ) of the hydraulic assembly is lower than a predeterminable maximum switch-on value (T HA, on, max ).

14. The method according to claim 12 , wherein when the ignition of the vehicle is switched on, a disc switch-on temperature (T disc, on ) is determined as a function of the disc switch-off temperature (T disc, off ) if, when the ignition is switched on, a switch-on temperature (T HA, on ) of the hydraulic assembly is not lower than the stored switch-off temperature (T HA, off ) of the hydraulic assembly or if the switch-on temperature (T HA, on ) of the hydraulic assembly is not lower than a predeterminable maximum switch-on value (T HA, on, max ).