Electromechanical Actuator Brake Force Characterization via Generator Mode
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Solution Overview
Problem
Existing electromechanical actuator units for vehicle brakes face challenges in precisely determining the brake force, which is crucial for avoiding overloading and ensuring reliable braking, as existing methods do not accurately account for manufacturing tolerances and temperature variations.
Innovation Solution
A method that involves switching off the electric motor voltage to determine parameters in generator mode, allowing for precise calculation of the motor constant, which is then used to determine other quantities like axial force, thereby improving the accuracy of brake force determination and avoiding overloading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the brake force is determined indirectly by means of various measured quantities and model sizes, then the determination can be performed without direct measurement, but the precision of brake force determination is insufficient due to manufacturing tolerances and temperature variations
Solution Approach 1:
The patent replaces the indirect mechanical measurement approach (using measured quantities and model sizes) with an electrical measurement approach. By utilizing the generator effect of the electric motor and measuring electrical parameters (voltage, current, speed) during generator mode, the system achieves more precise brake force determination that accounts for manufacturing tolerances and temperature variations without requiring complex mechanical measurement systems.
Solution Approach 2:
The patent introduces the generator mode of the electric motor as an intermediary mechanism. Instead of directly measuring brake force or relying on indirect mechanical models, the system uses the electric motor's generator effect to convert mechanical energy into electrical energy, allowing precise indirect measurement through electrical parameters that are more sensitive and accurate for determining the actual brake force.
2Measurement precision
If the voltage is switched off to determine parameters in generator mode, then the motor constant can be precisely determined, but the braking process is interrupted
Solution Approach 1:
The patent implements periodic switching of the electric motor between motor mode and generator mode. During normal braking, the motor operates in motor mode. At predetermined intervals or under specific conditions, the voltage is switched off to allow the motor to operate in generator mode for parameter measurement. This periodic action allows precise motor constant determination while minimizing interruption to the overall braking process.
Solution Approach 2:
The patent performs parameter determination in generator mode as a preliminary action before or during the braking process. By determining the motor constant and other parameters in advance or during non-critical phases of braking, the system prepares accurate data for brake force calculation, reducing the need for interruptions during critical braking operations.
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
This method enables precise determination of brake force, reducing the risk of overloading and extending the service life of the transmission by accounting for manufacturing tolerances and temperature variations, ensuring reliable braking performance.
Implementation Method 1
determination of at least one parameter while the electric motor is running in generator mode
Data Source
AI summary
A method for characterizing an electromechanical actuator unit for a vehicle brake, the electromechanical actuator unit comprising an electric motor and an actuator coupled to the electric motor. The actuator can be moved over a first area of movement without generation of a brake force and over a second area of movement with modification of a brake force. The method is carried out when the actuator moves within the first area of movement, and comprises the following steps: a) a voltage applied to the electric motor is interrupted, b) at least one parameter is determined while the electric motor runs in the generator mode, and c) at least one value is determined for a motor constant of the electric motor on the basis of the at least one parameter. The invention also relates to a vehicle brake, as well as to a computer program and a control unit for implementing the method.