Electromechanical Brake Air Gap Control Without Force Sensors

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Solution Overview

Problem

Conventional electromechanical brakes in vehicles require force sensors for precise brake pressure control, which are space-consuming and expensive, and the initial air gap between friction elements needs to be accurately set for efficient operation.

Innovation Solution

A method for operating electromechanical service brakes without force sensors by determining the brake touch point on one axle during a braking operation and setting the air gap based on current values, using a control unit and rotation speed sensors to adjust the friction elements' position, allowing for precise brake force control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If force sensors are used to measure brake pressure, then measurement precision is improved, but device complexity and cost increase

Engineering Contradiction:

Improvebrake pressure measurementVSAvoidbrake system structure

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces mechanical force sensors with an electrical measurement system. The electric motor's position sensor detects the air gap by measuring the motor's position during actuation, substituting a complex mechanical sensing system with a simpler electrical measurement approach that uses existing motor control infrastructure.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The measurement system uses the motor's own position sensor to measure the air gap, rather than requiring a separate force sensor. The motor serves dual purposes: both actuating the brake and measuring the air gap through its existing position feedback mechanism.

Inventive Principle:

Principle #25Self-service

2Measurement precision

If force sensors are installed on all axles, then measurement precision is improved, but manufacturing cost increases

Engineering Contradiction:

Improvebrake touch point determinationVSAvoidbrake system production cost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent eliminates the need for expensive force sensors on each axle by using the electric motor's position sensor. This substitution dramatically reduces manufacturing costs while maintaining measurement precision, as the position sensor is already integrated into the electromechanical brake system.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The motor's position sensor serves multiple functions: controlling brake actuation and measuring the air gap. This multi-functionality eliminates the need for separate measurement devices on each axle, reducing overall system cost while maintaining precision.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Productivity

If air gap measurement is performed during vehicle motion, then productivity is improved, but measurement precision may be affected by vibration

Engineering Contradiction:

Improveair gap adjustment frequencyVSAvoidbrake touch point detection

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent performs air gap measurements during braking operations when the brake is already being actuated. The measurement is taken during the natural braking cycle rather than requiring separate measurement operations, improving productivity while the braking process itself provides a stable measurement environment.

Inventive Principle:

Principle #10Preliminary action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enables simple, reliable, and cost-effective operation of electromechanical brakes by avoiding the need for force sensors and reducing slip torques, with frequent determination of the brake touch point during vehicle motion to account for wear and temperature changes.

Implementation Method 1

an electromechanical brake has an element, for example a ball screw, which is moved electromotively and which acts on movable friction elements of the brake

Methodology Applied

Scientific EffectElectromagnetic conversion: Electromagnetic Induction

Implementation Method 2

a brake pad is pressed against a brake disc and thus the brake pressure necessary for closing the brake is generated

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentUS12612025B2Method for operating a brake system of a vehicle, and brake system

Publication Date: 2026.04.28 ZF ACTIVE SAFETY GMBH

AI summary

A brake system of a vehicle, with electromechanical service brakes on at least one axle designed without force sensors, having a control unit designed to control a braking operation for meeting a braking demand by activating the electromechanical service brakes of all the axles. An acquisition element on each of the electromechanical service brakes acquires a parameter from which a current brake touch point of the electromechanical service brake in question can be determined. For operating the brake system, the brakes on one of the axles of the vehicle are actuated during a braking operation. A current value of a brake touch point of the electromechanical service brakes on another axle that is currently not being used to provide the brake force of the ongoing braking operation is determined. An air gap of those electromechanical service brakes is set according to the current value of the brake touch point.