Electric Vehicle Driving System Torsional Shock Reduction
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Solution Overview
Problem
Electric vehicles experience torsional shock and vibration when parked on slopes due to accumulated torsional energy in the driving system, which is not effectively mitigated by existing hardware improvements, especially since they lack shock reduction apparatuses like torque converters or transmissions.
Innovation Solution
A method involving a motor controller that calculates torsional torque by monitoring motor speed or vehicle acceleration fluctuations, applying reverse torque of the same magnitude to the driving system when releasing the parking gear, thereby reducing shock and vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the parking gear is engaged with the output gear to prevent vehicle movement on a slope, then the vehicle is confined and cannot move, but torsional energy is accumulated at the drive shaft causing shock and vibration when released
Solution Approach 1:
The motor controller detects torsional torque accumulation in the drive shaft before the parking gear is released, and applies reverse torque through the motor to neutralize the torsion. This preliminary action eliminates the harmful torsional energy before it can cause shock and vibration when the parking gear disengages, while maintaining reliable vehicle confinement during parking.
2Manufacturing precision
If hardware improvements are made to remove backlash in the output gear or parking gear, then mechanical precision is improved, but the fundamental cause of shock (torsional energy accumulation) is not addressed
Solution Approach 1:
Instead of relying solely on mechanical solutions like backlash-free gear design, the patent substitutes a control-based approach where the motor controller actively detects and neutralizes torsional torque through reverse torque application. This replaces passive mechanical precision with active torsion compensation, fundamentally addressing the root cause of shock rather than just eliminating backlash.
Solution Approach 2:
The system dynamically changes the torque parameter applied by the motor based on detected torsional conditions. By adjusting motor torque to counteract accumulated torsional energy in the drive shaft, the system adapts to varying slope conditions and vehicle states, effectively neutralizing torsion without requiring mechanical modifications to the gear structure.
3Force
If the vehicle weight and slope grade are increased, then the vehicle can carry more load and operate on steeper slopes, but torsional energy accumulation and resulting shock are increased
Solution Approach 1:
The motor controller continuously monitors motor speed fluctuations to detect torsional torque accumulation caused by gradient load. When torsion is detected, the controller applies reverse torque through the motor to neutralize the accumulation. This feedback mechanism allows the system to handle increased vehicle weight and slope grade without proportionally increasing shock, as the torsion is actively compensated in real-time.
Data Source
AI summary
A method for reducing torsional shock of a driving system of an electric vehicle is provided. In the method, torsional torque of a part of the driving system is calculated by applying motor torque to a motor under the condition that a parking gear is engaged and monitoring a motor speed. Reverse torsional torque having the same magnitude as the calculated torsional torque is applied to the part of the driving system when release of the parking gear is requested, and then the parking gear is released to reduce shock caused by torsion of the part of the driving system when the parking gear is released.