Electric Motor Backup Bearing via Shear Pin Decoupling
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Solution Overview
Problem
Existing electric motor systems for rotorcraft face challenges in accommodating failures such as bearing jam or degradation without increasing cost, weight, and space, as traditional clutch mechanisms are costly and inefficient.
Innovation Solution
An electric motor design featuring a primary bearing, an auxiliary bearing, an annular shear adapter, and a shear pin that decouples the primary bearing from the drive shaft when a predetermined torque threshold is exceeded, allowing the auxiliary bearing to support the drive shaft and maintain rotation in case of failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a clutch mechanism is integrated into each motor to accommodate bearing failure, then the motor system can continue operating after bearing failure, but the cost, weight, and space requirements increase significantly
Solution Approach 1:
The invention extracts the clutch mechanism from each individual motor and replaces it with a simple shear pin located in the drive shaft. This single shear pin serves the function of disconnecting failed motors from the drive shaft, allowing the remaining motors to continue operating. This extraction eliminates the need for complex clutch mechanisms in each motor while maintaining the same failure accommodation capability.
Solution Approach 2:
The shear pin acts as an intermediary element between the drive shaft and the motors. When a bearing fails, the shear pin breaks, serving as a mediator that disconnects the failed motor from the drive shaft without requiring complex clutch mechanisms. This intermediary approach simplifies the overall system while achieving the desired reliability.
2Reliability
If traditional clutch mechanisms are used to handle bearing failures, then motor system reliability is improved, but the weight of the motor system increases
Solution Approach 1:
The heavy clutch mechanisms are extracted from each motor and replaced with a lightweight shear pin in the drive shaft. This extraction dramatically reduces the overall weight of the motor system while maintaining the ability to accommodate bearing failures and continue operation.
3Reliability
If clutch mechanisms are integrated into each motor for failure accommodation, then bearing failure can be handled, but valuable space within the motor system is consumed
Solution Approach 1:
The space-consuming clutch mechanisms are extracted from each motor and replaced with a compact shear pin located in the drive shaft. This extraction frees up valuable space within the motor system while preserving the failure accommodation capability.
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 design enables failure-resistant operation of electric motor systems while minimizing cost, weight, and space constraints, allowing the drive shaft to continue rotating despite primary bearing failures without the need for costly clutch systems.
Implementation Method 1
a shear pin interoperably coupled to the primary bearing via the annular shear adapter and configured to break responsive to torque between the annular shear adapter and the drive shaft exceeding a predetermined torque threshold
Data Source
AI summary
An electric motor adapted to apply torque to a drive shaft rotatable about an axis, the electric motor includes a stator, a rotor adapted to rotate relative to the stator, a primary bearing interoperably coupled to the stator and adapted to provide bearing support between the stator and the rotor, an auxiliary bearing interoperably coupled to the drive shaft, an annular shear adapter connected to the primary bearing and the auxiliary bearing, and a shear pin interoperably coupled to the primary bearing via the annular shear adapter and configured to break responsive to torque between the annular shear adapter and the drive shaft exceeding a predetermined torque threshold.