Method for Setting a Parking Brake in a Vehicle

• US 20150239439A1
• Filed: 01/13/2015
• Published: 08/27/2015
• Est. Priority Date: 02/25/2014
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Sussek, Ullrich
• Granted Patent: US 9,744,951 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B60T 13/588 both fluid and mechanical assistance or drive
• CPC Class Codes: B60T 13/662 characterised by specified functions of the control system components
• CPC Class Codes: B60T 13/741 acting on an ultimate actuator
• CPC Class Codes: B60T 8/171 Detecting parameters used in the regulation; Measuring values used in the regulation
• CPC Class Codes: B60T 8/172 Determining control parameters used in the regulation, e.g. by calculations involving measured or detected parameters B60T8/17551 takes precedence
• CPC Class Codes: F16D 2121/04 acting on a piston-type actuator, e.g. for liquid pressure
• CPC Class Codes: F16D 2121/14 Mechanical
• CPC Class Codes: F16D 55/226 in which the common actuating member is moved axially , e.g. floating caliper disc brakes
• CPC Class Codes: F16D 65/18 adapted for drawing members together , e.g. for disc brakes

Abstract

A method for setting a parking brake includes determining a standard deviation from a current curve of an electric brake motor. The current curve is based on measured current valued. The method further includes determining an electromechanical clamping force. The electromechanical clamping force can be determined based on a correcting current or the current values of the brake motor. The correcting current is determined if the standard deviation exceeds a limit value and motor parameters of the brake motor being determined using the correcting current. The parking brake includes an electromechanical braking mechanism having the electric brake motor configured to generate an electromechanical clamping force.

Claims

1. The method for setting a parking brake, comprising:

determining a standard deviation from a current curve of an electric brake motor, the current curve being based on measured current values; and

determining an electromechanical clamping force based on;

(i) a correcting current, the correcting current being determined if the standard deviation exceeds a limit value and motor parameters of the electric brake motor being determined using the correcting current;

or

(ii) the current values of the brake motor,

wherein the parking brake includes an electromechanical braking mechanism having the electric brake motor configured to generate the electromechanical clamping force.

2. The method according to claim 1, wherein the determination of the standard deviation further comprises:

determining the standard deviation from a hypothetical maximal current if the brake motor is at a standstill, the maximal current being determined from multiple sequential, measured current values.

3. The method according to claim 1, further comprising:

determining the standard deviation from a hypothetical maximal current if the brake motor is at a standstill, the maximal current based on equation;

4. The method according to claim 1, wherein the determination of the correcting current further comprises:

determining the correcting current based on a first product of a scaling factor and a third current value, the current value obtained sequentially prior to an increase in the standard deviation.

5. The method according to claim 4, wherein the determination of the correcting current further comprises:

determining the correcting current based on a second product of the scaling factor and a difference between the third current value obtained prior to the increase in the standard deviation and an idle running current, using equation;

I_cor(t_spr)=I_s(t_spr)+f_cor(t_spr)·

(I_t1−

I_L),

wherein

I_cor(t_spr) is the corrected current after the increase in the standard deviation at time t_spr,

I_S(t_spr) is a fourth current value after the increase in the standard deviation at the time t_spr,

f_cor(t_spr) is the scaling factor after the increase in the standard deviation at the time t_spr,

I_t1 is the third current value before the increase in the standard deviation, and

I_L is the idle running current.

6. The method according claim 4, further comprising:

calculating different current values at different points in time after the increase in the standard deviation with reference to the scaling factor from the third current value obtained prior to the increase in the standard deviation.

7. The method according claim 4, further comprising:

determining the scaling factor based on a ratio of voltage step change to a voltage value obtained prior to the increase in the standard deviation.

8. The method according claim 1, wherein the determination of the standard deviation is based on a fifth current value during an application of the parking brake.

9. The method according to claim 1, wherein the determination of the standard deviation is based on a sixth current value during switching-on of the brake motor.

10. The method according to claim 9, wherein the determination of the standard deviation is based on the sixth current value following a peak of a switch-on current.

11. The method according to claim 1, further comprising:

repeatedly performing the determination of the standard deviation and the correcting current.

12. A closed-loop control device configured to perform a method, the method comprising:

determining a standard deviation from a current curve of an electric brake motor, the current curve being based on measured current values; and

determining an electromechanical clamping force based on;

(i) a correcting current, the correcting current being determined if the standard deviation exceeds a limit value and motor parameters of the electric brake motor being determined using the correcting current;

or

(ii) the current values of the brake motor,

wherein the parking brake includes an electromechanical braking mechanism having the electric brake motor configured to generate the electromechanical clamping force.

13. The closed-loop control device according to claim 12, wherein the closed-loop control device is included in the parking brake of a vehicle.

14. An open-loop control device configured to perform a method, the method comprising:

determining a standard deviation from a current curve of an electric brake motor, the current curve being based on measured current values; and

determining an electromechanical clamping force based on;

(i) a correcting current, the correcting current being determined if the standard deviation exceeds a limit value and motor parameters of the electric brake motor being determined using the correcting current;

or

(ii) the current values of the brake motor,

wherein the parking brake includes an electromechanical braking mechanism having the electric brake motor configured to generate the electromechanical clamping force.

15. The open-loop control device according to claim 14, wherein the open-loop control device is included in the parking brake of a vehicle.