Electric Drive Decoupler for Torque Transient Management
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Solution Overview
Problem
Conventional electric drive modules in electric and hybrid electric vehicles face challenges with excessive torque loads during braking and severe road conditions, leading to increased mass and cost due to oversized components and the need for adaptive motor control algorithms to manage torque transients.
Innovation Solution
Incorporating a disconnect mechanism, such as a clutch with a power-operated actuator and control module, to selectively couple and decouple the geared reduction unit from the final drive assembly, allowing for adaptive torque management and reduced peak loading conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electric drive module components are sized to accommodate excessive peak loading conditions during braking and severe road conditions, then the reliability is improved, but the mass increases
Solution Approach 1:
The patent applies the dynamics principle by introducing a disconnect mechanism that can dynamically change the coupling state between the geared reduction unit and final drive assembly. This mechanism allows the system to transition between coupled and decoupled states based on operating conditions, enabling components to be sized for normal operation rather than peak transient loads, thereby reducing mass while maintaining reliability during critical events.
Solution Approach 2:
The disconnect mechanism extracts the final drive assembly from the continuous torque path by providing a decoupling capability. During braking events and severe road conditions, the disconnect mechanism can separate the geared reduction unit from the final drive assembly, removing the source of excessive peak loading and allowing smaller, lighter components to be used throughout the drive module.
2Reliability
If the electric drive module components are sized to accommodate excessive peak loading conditions during braking and severe road conditions, then the reliability is improved, but the cost increases
Solution Approach 1:
The disconnect mechanism provides dynamic control over torque transmission, allowing the system to adapt to varying operating conditions. This enables cost-effective component sizing based on continuous operational requirements rather than designing for rare peak transient events, reducing overall system cost while maintaining reliability through active management of torque loads.
Solution Approach 2:
By extracting the final drive assembly from the torque path during peak loading conditions, the disconnect mechanism prevents excessive loads from propagating through the entire drive module. This allows for the use of smaller, less expensive components that would otherwise need to be oversized to handle peak transient loads, thereby reducing manufacturing cost while preserving reliability.
3Adaptability or versatility
If adaptive motor control algorithms are implemented to counteract torque load mismatches, then the operational functionality is improved, but the device complexity increases
Solution Approach 1:
The disconnect mechanism acts as an intermediary between the geared reduction unit and final drive assembly, providing a physical means to manage torque load mismatches. This mechanical intermediary simplifies the control system by providing a direct method to decouple the drivetrain during problematic conditions, reducing the need for complex adaptive motor control algorithms while improving operational functionality.
4Weight of moving object
If a disconnect mechanism is added to selectively decouple the geared reduction unit from the final drive assembly, then the mass is reduced, but the device complexity increases
Solution Approach 1:
The disconnect mechanism introduces dynamic reconfigurability to the drive module, allowing the system to switch between coupled and decoupled states. This dynamic capability enables mass reduction by allowing smaller components to be used, while the added complexity is offset by the benefits of adaptive torque management and the ability to operate efficiently across a wider range of conditions.
Data Source
AI summary
An electric drive module for use in electric vehicles includes an electric traction motor, a geared reduction unit driven by the electric motor, a differential unit interconnecting a pair of axleshafts to a pair of wheels, and a disconnect mechanism for selectively coupling and uncoupling the geared reduction unit and the differential unit. The disconnect mechanism is configured to normally couple the geared reduction unit to the differential unit. The disconnect mechanism uncouples the geared reduction unit from the differential unit to prevent peak torque transients and torque reversals between the electric motor and the wheels.