Method for setting a parking brake in a vehicle

• US 9,744,951 B2
• Filed: 01/13/2015
• Issued: 08/29/2017
• Est. Priority Date: 02/25/2014
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Sussek, Ullrich
• Primary Examiner(s): Badii, Behrang
• Assistant Examiner(s): GREENE, DANIEL LAWSON
• Application Number:
  US14/595,509
• Publication Number:
  US 20150239439A1
• Time in Patent Office: 959 Days
• Field of Search: 701 70
• 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. A method for determining an electromechanical clamping force generated by an electric brake motor of a parking brake of a vehicle, comprising:

measuring current values of a motor current of the electric brake motor using a current sensor;

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

determining the electromechanical clamping force based on motor parameters of the electric brake motor using the control device,

wherein the control device is configured to calculate the motor parameters based on the measured current values when the standard deviation does not exceed a limit value,

wherein the control device is configured to calculate the motor parameters based on a correcting current when the standard deviation exceeds the limit value, the correcting current being a product of (i) a measured current value obtained prior to the standard deviation exceeding the limit value and (ii) a scaling factor.

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

determining the correcting current based on a product of the scaling factor and a difference between the measured current value obtained prior to the standard deviation exceeding the limit value and an idle running current, using equation;

I_cor(t_spr)=I_s(t_spr)+f_cor(t_spr)·

(I_t1−

I_L),

wherein

t_spr is a time at which the standard deviation increases above the limit value

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

I_s(t_spr) is a measured current value obtained 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 measured current value obtained before the standard deviation exceeds the limit value, and

I_L is the idle running current.

3. The method according claim 1, further comprising:

calculating different correcting current values corresponding to different points in time after the standard deviation exceeds the limit value with reference to the scaling factor used with the measured current value obtained prior to the the standard deviation exceeding the limit value.

4. The method according claim 1, further comprising:

determining the scaling factor based on a ratio of a voltage step change obtained at a time when the standard deviation exceeds the limit value to a voltage value obtained prior to the standard deviation exceeding the limit value.

5. The method according claim 1, wherein the measured current values are taken during an application of the parking brake.

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

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

7. The method of claim 1, further comprising:

applying the parking brake based on the determined electromechanical clamping force.

8. The method according to claim 1, wherein the measured current values are taken during switching-on of the brake motor.

9. The method according to claim 8, wherein the measured current values are taken following a peak of a switch-on current.

10. 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.

11. The method according to claim 10, further comprising:

determining the standard deviation from the hypothetical maximal current, the maximal current being based on equation;

12. A closed-loop control device configured to perform a method for determining an electromechanical clamping force generated by an electric brake motor of a parking brake of a vehicle, the closed loop control device comprising:

a control device configured to;

receive current values of a motor current of the electric brake motor from a current sensor of the vehicle;

determine a standard deviation from a current curve of the electric brake motor of the parking brake, the current curve being based on the current values received from the current sensor; and

determine the electromechanical clamping force based on motor parameters of the electric brake motor,

wherein the control device is configured to calculate the motor parameters based on the measured current values when the standard deviation does not exceed a limit value, and

wherein the control device is configured to calculate the motor parameters based on a correcting current when the standard deviation exceeds the limit value, the correcting current being a product of (i) a measured current value obtained prior to the standard deviation exceeding the limit value and (ii) a scaling factor.

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 for determining an electromechanical clamping force generated by an electric brake motor of a parking brake of a vehicle, the open-loop control device comprising:

a control device configured to;

receive current values of a motor current of the electric brake motor from a current sensor of the vehicle;

determine a standard deviation from a current curve of the electric brake motor of the parking brake, the current curve being based on the current values received from the current sensor; and

determine the electromechanical clamping force based on motor parameters of the electric brake motor,

wherein the control device is configured to calculate the motor parameters based on the measured current values when the standard deviation does not exceed a limit value, and

wherein the control device is configured to calculate the motor parameters based on a correcting current when the standard deviation exceeds the limit value, the correcting current being a product of (i) a measured current value obtained prior to the standard deviation exceeding the limit value and (ii) a scaling factor.

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.