Method for determining a clearance of an electromechanical brake, brake, and control unit

Patent metadata

Field	Value
Publication number	US-11891033-B2
Application number	US-201917417124-A
Country	US
Kind code	B2
Filing date	Dec 10, 2019
Priority date	Jan 7, 2019
Publication date	Feb 6, 2024
Grant date	Feb 6, 2024

Abstract

A method for determining a clearance of an electromechanical brake involves the following steps: Activating a clearance determination cycle for the brake, moving an electromechanical brake actuator by a drive motor into a first end position, moving the electromechanical brake actuator via the drive motor toward a second end position, continuously determining a rotor position and/or a motor current of the drive motor during the movement of the brake actuator toward the second end position, determining a contact position at which the brake pad comes into contact with the brake disc, on the basis of the rotor position and/or of the motor current, and determining a clearance and/or a degree of pad wear on the basis of the determined contact position. A suitable electomechanical brake and a respective control unit carry out the method.

First claim

The invention claimed is:

1. A method ( 200 ) for determining a clearance (L) of an electromechanical brake ( 100 ), in particular a commercial vehicle brake, comprising the steps of:
activating ( 202 ) a clearance determination cycle for the electromechanical brake ( 100 ),
moving ( 204 ) an electromechanical brake actuator ( 2 ) via a drive motor (A) into a first end position (E 1 ), in which the electromechanical brake ( 100 ) is in a non-applied state,
moving ( 206 ) the electromechanical brake actuator ( 2 ) via the drive motor (A) toward a second end position (E 2 ), wherein the movement of the electromechanical brake actuator ( 2 ) applies at least one brake pad ( 103 ) of the electromechanical brake ( 100 ) toward a brake disc,
continuously determining ( 208 ) at least one of a rotor position (φ) and a motor current (i) of the drive motor (A) during the movement of the electromechanical brake actuator ( 2 ) toward the second end position (E 2 ),
determining ( 210 ) a contact position (K), at which the brake pad ( 103 ) comes into contact with the brake disc, on the basis of at least one of the rotor position (φ) and the motor current (i),
determining ( 212 ) at least one of a clearance (L) and a degree of pad wear (V B ) on the basis of the determined contact position (K).

2. The method ( 200 ) as claimed in claim 1 ,
wherein determining ( 300 ) the contact position (K) on the basis of the rotor position (φ) comprises the steps of:
defining ( 302 ) a maximum current (i max ) for the drive motor (A),
operating ( 304 ) the drive motor (A) with a motor current (i) which is less than or equal to the maximum current (i max ),
determining ( 306 ) a rotor end position (φ max ) of the drive motor (A) for which no further change in the rotor position (φ) of the drive motor (A) of the electromechanical brake actuator ( 2 ) occurs for the given maximum current (i max ),
determining a contact position (K) from the rotor end position (φ max ).

3. The method ( 200 ) as claimed in claim 2 ,
wherein the contact position (K) is determined based on first correlation parameters (K 1 ) comprising at least one of the following parameters:
current amplitude,
last determined degree of pad wear,
transmission ratio of a transmission of the electromechanical brake actuator.

4. The method ( 200 ) as claimed in claim 1 ,
wherein determining ( 400 ) the contact position (K) on the basis of the motor current (i) comprises the steps of:
detecting ( 402 ) a current increase in the motor current (i),
determining ( 404 ) the corresponding rotor position (φ thr ) at which the current increase of the motor current (i thr ) occurs for the first time,
determining ( 406 ) a contact position (K) from the rotor position (φ thr ), in particular on the basis of second correlation parameters (K 2 ).

5. The method ( 200 ) as claimed in claim 1 , further comprising the step of:
storing at least one of the following in a memory ( 12 ):
the determined contact position (K),
the clearance (L),
the degree of pad wear (V B ).

6. A control unit ( 8 ) for determining a clearance (L) of an electromechanical brake ( 100 ), comprising:
an interface ( 10 ) for the signal-conducting connection ( 6 ) of the control unit ( 8 ) to an electromechanical brake actuator ( 2 );
a memory ( 12 ) and a processor ( 14 ),
wherein the control unit ( 8 ) is configured:
to activate a clearance determination cycle ( 202 ) for the electromechanical brake ( 100 ),
to move the electromechanical brake actuator ( 2 ) via a drive motor (A) into a first end position (E 1 ), in which the electromechanical brake ( 100 ) is in a non-applied state,
to move the electromechanical brake actuator ( 2 ) via the drive motor (A) toward a second end position (E 2 ), wherein the movement of the electromechanical brake actuator ( 2 ) applies at least one brake pad ( 103 ) of the electromechanical brake ( 100 ) toward a brake disc,
to continuously determine at least one of a rotor position (φ) and a motor current (i) of the drive motor (A) during the movement of the electromechanical brake actuator ( 2 ) toward the second end position (E 2 ),
to determine a contact position (K), at which the brake pad ( 103 ) comes into contact with the brake disc, on the basis of at least one of the rotor position (φ) and the motor current (i), and
to determine a clearance (L) and a degree of pad wear (V B ) on the basis of the determined contact position (K).

7. The control unit ( 8 ) as claimed in claim 6 ,
wherein the control unit ( 8 ) for determining ( 300 ) the contact position (K) on the basis of the rotor position (φ) is configured
to define ( 302 ) a maximum current (i max ) for the drive motor (A),
to operate ( 304 ) the drive motor (A) with a motor current (i) which is less than or equal to the maximum current (i max ),
to determine ( 306 ) a rotor end position (φ max ) of the drive motor (A) for which no further change in the rotor position (φ) of the electromechanical brake actuator ( 2 ) occurs for the given maximum current (i max ),
to determine a contact position (K) from the rotor end position (φ max ), in particular on the basis of first correlation parameters (K 1 ).

8. The control unit ( 8 ) as claimed in claim 6 ,
wherein the control unit ( 8 ) for determining ( 400 ) the contact position (K) on the basis of the motor current (i) is configured
to detect ( 402 ) a change in the motor current (i), in particular a first increase in the motor current (i thr ),
to determine ( 404 ) a corresponding rotor position (φ thr ) at which the current increase of the motor current (i thr ) occurs for the first time,
to determine ( 406 ) a contact position (K) from the rotor position (φ thr ), in particular on the basis of second correlation parameters (K 2 ).

9. An electromechanical brake ( 100 ) comprising:
the brake disc,
the at least one brake pad ( 103 ) accommodated in a brake caliper ( 107 ),
the electromechanical brake actuator ( 2 ) with the drive motor (A) for applying the at least one brake pad ( 103 ) toward the brake disc, and
the control unit ( 8 ) according to claim 6 .

10. A non-transitory computer memory storing instructions and a processor configured for executing the instructions to perform the method ( 200 ) as claimed in claim 1 .

Assignees

• Zf Cv Systems Europe Bv

Inventors

• Beier Peter
• Reiners Arne

Classifications

• B60T17/221 Primary

  Procedure or apparatus for checking or keeping in a correct functioning condition of brake systems (hydraulic pressure systems in general F15B19/00, F15B21/04; testing structures or apparatus G01M) · CPC title

• B60T13/662 Primary

  characterised by specified functions of the control system components · CPC title

• F16D66/026

  indicating different degrees of lining wear · CPC title

• H02P6/24

  Arrangements for stopping · CPC title

• H02P6/28

  Arrangements for controlling current (H02P6/10 takes precedence) · CPC title