EV Motor Shaft Torque Monitoring for Gearbox Over-Torque Protection
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Solution Overview
Problem
Existing torque security systems in electric vehicles fail to accurately detect over-torque conditions and gearbox damage, leading to potential powertrain damage due to gear latch and gearbox damping, and are unable to quickly respond to prevent such damage.
Innovation Solution
A torque security system that monitors a signal from a sensor coupled to the motor shaft of an electric motor, determines acceleration and internal torque, and reduces power output to the electric motor when internal torque exceeds a threshold, while also diagnosing gearbox damage by analyzing harmonics in the frequency domain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a sensor is installed on a wheel to estimate motor shaft torque, then the system can monitor torque output, but the system cannot accurately estimate motor shaft torque or detect certain oscillations due to gear latch and gearbox damping
Solution Approach 1:
The patent uses motor acceleration as an intermediary measurement to indirectly determine internal torque. Instead of directly measuring torque at the motor shaft (which is obscured by gearbox damping), the system measures acceleration and uses it to calculate torque through the relationship torque = moment of inertia × acceleration. This intermediary approach bypasses the measurement problems caused by gear latch and damping.
Solution Approach 2:
The patent replaces direct mechanical torque measurement with an electrical/accelerometric measurement system. By using acceleration sensors and computational algorithms to derive torque from acceleration data, the system substitutes a direct mechanical measurement approach with an indirect field-based measurement that is not affected by gearbox damping and gear latch phenomena.
2Speed
If the system uses traditional torque estimation methods, then it can operate continuously, but it cannot detect over-torque conditions quickly enough to prevent damage to the powertrain
Solution Approach 1:
The system continuously monitors motor acceleration and calculates internal torque in real-time before damage can occur. By maintaining continuous awareness of the torque state through acceleration monitoring, the system is prepared to detect over-torque conditions immediately when they arise, enabling preventive action before powertrain damage occurs.
Solution Approach 2:
The patent implements a feedback loop where acceleration measurements continuously inform torque calculations, which then trigger protective actions when thresholds are exceeded. The system monitors acceleration, calculates torque, compares it against safe operating limits, and automatically reduces power or shuts off the motor when over-torque conditions are detected, creating a closed-loop protective mechanism.
3Adaptability or versatility
If the system monitors torque using existing methods, then it can operate the electric motor, but it cannot diagnose damage to the gearbox during operation
Solution Approach 1:
The patent makes the acceleration monitoring system serve multiple functions: it simultaneously enables torque estimation for over-torque protection and gearbox damage diagnosis. The same acceleration data used to calculate internal torque for protective shutdowns also provides information about gearbox health through analysis of oscillation patterns and torque fluctuations, eliminating the need for separate diagnostic hardware.
Solution Approach 2:
The system uses its own operational data (acceleration and torque measurements) to diagnose gearbox damage without requiring external diagnostic equipment. By analyzing variations in acceleration patterns and torque characteristics during normal operation, the system self-diagnoses gearbox conditions, turning routine monitoring data into diagnostic information.
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
Effectively prevents powertrain damage by quickly reducing power output during over-torque conditions and accurately diagnosing gearbox issues, ensuring the system can detect and respond to potential damage in real-time.
Implementation Method 1
determines an internal torque between the motor shaft and an input gear coupled to the motor shaft, based on the acceleration of the electric motor and the inertia of the electric motor and a gearbox
Data Source
AI summary
A torque security system for a vehicle is provided. The system receives a signal from a sensor coupled to a motor shaft of an electric motor and determines an acceleration of the electric motor, based on the signal from the sensor that indicates an amount of rotation of the motor shaft. The system determines an internal torque between the motor shaft and an input gear coupled to the motor shaft, based on the acceleration of the electric motor and an inertia of the electric motor and a gearbox. The powertrain of the vehicle comprises the gearbox and the electric motor, and the input gear couples the electric motor to the gearbox. The system determines whether the internal torque exceeds a threshold torque, and in response to determining that the internal torque exceeds the threshold torque, the system reduces power output to the electric motor. The system also diagnoses the health of the gearbox.