EMB Torque Measurement via External Axial Reaction Sensing
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Solution Overview
Problem
Electromechanical braking (EMB) systems face challenges in accurately controlling braking torque due to high temperatures and limited space, leading to large margins of error in torque estimation and control performance, as existing torque sensors are expensive and prone to errors from production factors and mechanical characteristics.
Innovation Solution
A measurement apparatus is designed to determine braking torque using axial reaction forces generated by a power generating unit, featuring a connection portion with strain gauges that measure deformation, forming a Wheatstone bridge to accurately calculate torque, thereby reducing the need for expensive torque sensors and improving control precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a torque sensor is installed inside the brake caliper to measure inter-axle torque, then torque measurement capability is improved, but the device becomes expensive and space-consuming due to high temperature requirements
Solution Approach 1:
The measurement apparatus is extracted from the high-temperature brake caliper environment and installed externally on the power generating unit. This separates the measurement function from the harsh thermal environment, eliminating the need for expensive high-temperature durable torque sensors while maintaining measurement capability
Solution Approach 2:
The measurement apparatus acts as an intermediary by measuring axial reaction force generated by the power generating unit instead of directly measuring torque inside the caliper. This indirect measurement approach avoids the high-temperature environment while still providing torque information through reaction force measurement
2Device complexity
If torque estimation method is used based on current and voltage applied to electric motor, then device complexity is reduced, but measurement precision deteriorates due to large margins of error in motor parameters
Solution Approach 1:
The electrical-based torque estimation method is replaced with a mechanical measurement system. The measurement apparatus directly measures axial reaction force mechanically through strain gauges on the connection portion, providing accurate torque data without relying on electrical parameter calculations and their associated errors
3Temperature
If measurement apparatus is installed outside the housing unit, then the apparatus is not affected by braking heat, but the connection portion must be designed to transmit axial reaction force accurately
Solution Approach 1:
The measurement is shifted from the radial torque measurement dimension inside the caliper to the axial reaction force dimension at the power generating unit connection. This dimensional change allows measurement outside the high-temperature zone while using the existing structural connection portion
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
The solution provides accurate and precise torque measurement, reducing control errors and improving performance by minimizing the influence of braking heat and space constraints, while being easy to install and cost-effective.
Implementation Method 1
a connection portion (530) connecting the power generating unit (100) and the housing unit (600), and a strain gauge (540) provided in the connection portion (530)
Implementation Method 2
forming a Wheatstone bridge to accurately calculate torque
Data Source
AI summary
An electromechanical braking device includes: a housing unit provided with a braking force generating unit therein; a power generating unit configured for providing driving force for braking force required by the braking force generating unit; and a measurement apparatus including one end portion connected to one side of the housing unit and the other end portion connected to the power generating unit, wherein braking torque is determined using axial reaction force generated by driving force greater than or equal to a rotation limit amount generated from the power generation unit.