Method for setting a parking brake in a vehicle

Abstract

In a method for setting a parking brake that has an electromechanical brake device having an electrical brake motor, the release time duration for displacing the electrical brake motor in the release direction is determined from the closing time duration in which the brake motor was previously displaced in the closing direction.

Claims

1. A method for setting a parking brake that has an electromechanical brake device having an electrical brake motor for producing an electromechanical clamping force, the method comprising: determining a release time duration for displacing the electrical brake motor in a release direction from a closing time duration in which the electrical brake motor was previously displaced in a closing direction.

2. The method as recited in claim 1, wherein the closing time duration of an immediately preceding closing process is used in the determining of the release time duration.

3. The method as recited in claim 1, wherein the release time duration is determined by multiplying the closing time duration by an adaptation factor determined from electromotoric parameters:
t.sub.Lt.sub.S.Math.F wherein t.sub.L is the release time duration, t.sub.S is the closing time duration, and F is the adaptation factor.

4. The method as recited in claim 3, wherein the adaptation factor is determined from a ratio of a motor voltage during the closing process to a motor voltage at a beginning of the release process: $F=\frac{{\stackrel{\_}{U}}_S}{{\stackrel{\_}{U}}_L}$ wherein .sub.S is the motor voltage during the closing process, and U.sub.L is the motor voltage at the beginning of the release process.

5. The method as recited in claim 4, wherein an average motor voltage of the electrical brake motor is taken into account during closing process.

6. The method as recited in claim 1, wherein the release time duration corresponds at least to the closing time duration.

7. The method as recited in claim 1, wherein the method is performed in cases of an interruption of a closing process.

8. The method as recited in claim 1, wherein the method is performed in cases in which a desired startup is recognized during a closing process.

9. A regulating or control device for setting a parking brake that has an electromechanical brake device having an electrical brake motor for producing an electromechanical clamping force, the device configured to determine a release time duration for displacing the electrical brake motor in a release direction from a closing time duration in which the electrical brake motor was previously displaced in a closing direction.

10. A parking brake in a vehicle having a regulating or control device, the device for setting a parking brake that has an electromechanical brake device having an electrical brake motor for producing an electromechanical clamping force, the device configured to determine a release time duration for displacing the electrical brake motor in a release direction from a closing time duration in which the electrical brake motor was previously displaced in a closing direction.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) The FIGURE shows a section through an electromechanical vehicle parking brake in which the clamping force is produced by an electrical brake motor.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

(2) The FIGURE shows an electromechanical parking brake 1 for holding a vehicle at a standstill. Parking brake 1 has a brake caliper 2 having a binding piece 9 that overlaps a brake disk 10. As an actuating element, parking brake 1 has an electric motor as brake motor 3 that rotationally drives a spindle 4 on which a spindle component 5 is rotatably mounted. When there is rotation of spindle 4, spindle component 5 is axially displaced. Spindle component 5 moves inside a brake piston 6, bearing a brake lining 7, that is pressed against brake disk 10 by brake piston 6. On the opposite side of brake disk 10 there is situated a further brake lining 8 that is held stationary on binding piece 9.

(3) Inside brake piston 6, spindle component 5 can move axially forward in the direction toward brake disk 10 when there is a rotational movement of spindle 4, or, when there is a rotational movement of spindle 4 in the opposite direction, spindle component 5 can move axially backward until it reaches a stop 11. In order to produce a clamping force, spindle component 5 acts on the inner end surface of brake piston 6, causing brake piston 6, mounted displaceably in parking brake 1, to be pressed with brake lining 7 against the facing end surface of brake disk 10.

(4) If necessary, the parking brake can be supported by a hydraulic vehicle brake so that the clamping force is composed of an electromotoric portion and a hydraulic portion. When there is hydraulic support, the rear side, facing the brake motor, of brake piston 6 is acted on by hydraulic fluid under pressure.

(5) The release of the parking brake is carried out as a function of time. For this purpose, release time duration t.sub.L is determined during which the electric brake motor is displaced in the release direction, in particular with a constant displacement speed. Release time duration t.sub.L is determined as a function of closing time duration t.sub.s from an immediately preceding closing process of the parking brake. According to the equation:
t.sub.L=t.sub.S.Math.F
release time duration t.sub.S is a function of an adaptation factor F and the closing time duration t.sub.S of the preceding closing process, adaptation factor F designating the ratio of average motor voltage .sub.S during the closing process to motor voltage U.sub.L at the beginning of the release process:

(6) $F=\frac{{\stackrel{\_}{U}}_S}{{\stackrel{\_}{U}}_L}$
Release time duration t.sub.L determined in this way is determined in particular in cases of disturbance, for example after an interruption of the closing process or if a desired startup is recognized during the closing process.

(7) It can be useful for the release time duration to correspond at least to the closing time duration. This can be achieved according to the above relationship if adaptation factor F assumes a value of at least 1.