Method for determining an operating variable of a drum brake, drum brake assembly

A drum brake assembly, comprising:

• at least one brake shoe and one further brake shoe;
• at least one supporting bearing for the brake shoe and one further supporting bearing for the further brake shoe;
• at least one force sensor at the supporting bearing which measures a bearing force produced in the supporting bearing by the brake shoe;
• at least one further force sensor at the further supporting bearing which measures a further bearing force produced in the further supporting bearing by the further brake shoe, and
• an evaluation device which executes a method for determining an operating variable of a drum brake comprising:
• actuating the brake with an electromechanical actuator in at least one of:
• a first wheel speed range and a second wheel speed range, wherein wheel speeds of the first wheel speed range are higher than wheel speeds of the second wheel speed range;
• determining at least one bearing force of a leading brake shoe and a further bearing force of a trailing brake shoe of the drum brake when in the first wheel speed range;
• calculating the operating variable when in the first wheel speed range based on the bearing force and the further bearing force;
• determining at least one current actuator position when in the second wheel speed range;
• and
• calculating the operating variable when in the second wheel speed range based on the actuator position and an actuator contact position, in which brake shoes of the drum brake come into engagement with a drum of the drum brake, wherein the operating variable is a product of a first multiplier and a function in the second wheel speed range, and wherein a difference between the actuator position and the actuator contact position is an input variable of the function, and wherein the first multiplier as a quotient with a dividend and a divisor, the dividend is an average of a difference between a bearing force and a further bearing force over a predetermined period of time, and the divisor is an average of the function over a predetermined value range.

A method for determining an operating variable of a drum brake comprising:

• actuating the brake with an electromechanical actuator in at least one of:
• a first wheel speed range and a second wheel speed range, wherein wheel speeds of the first wheel speed range are higher than wheel speeds of the second wheel speed range;
• determining at least one bearing force of a leading brake shoe and a further bearing force of a trailing brake shoe of the drum brake when in the first wheel speed range;
• calculating the operating variable when in the first wheel speed range based on the bearing force and the further bearing force;
• determining at least one current actuator position when in the second wheel speed range;
• and
• calculating the operating variable when in the second wheel speed range based on the actuator position and an actuator contact position, in which brake shoes of the drum brake come into engagement with a drum of the drum brake, wherein calculating the operating variable further comprises calculating a product of a first multiplier and a function in the second wheel speed range, and wherein a difference between the actuator position and the actuator contact position is an input variable of the function, wherein the function rises exponentially.