Work Vehicle Drive Assembly with Biased Clutch Overspeed Protection
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Solution Overview
Problem
Work vehicles face damage due to overspeed conditions, which can occur when the wheel rotates above its mechanical speed limit, leading to backdrive forces that are damaging to the gear train and motor, especially during downhill movements or towing situations.
Innovation Solution
A drive assembly with a clutch that engages during low-speed conditions and disengages during high-speed conditions, featuring a biased clutch member that prevents torque transfer from the driven shaft to the driving shaft in overspeed situations, and an actuator controlled by a processor and sensors to manage clutch engagement and disengagement based on speed conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the wheel is allowed to rotate at high speeds during downhill or towing conditions, then the vehicle can move freely, but the gear train and motor are damaged by backdrive forces
Solution Approach 1:
The clutch member is extracted from the continuous torque path between the driven shaft and driving shaft. When activated, it removes the connection that would otherwise transmit damaging backdrive forces to the motor and gear train, allowing the wheel to spin freely while protecting the drive components.
Solution Approach 2:
The clutch member acts as an intermediary element between the driven shaft and driving shaft. It selectively mediates torque transfer based on operating conditions, allowing torque transmission during normal operation but blocking reverse torque during overspeed conditions through its biased engagement/disengagement mechanism.
2Reliability
If a clutch mechanism is added to prevent overspeed damage, then the drive assembly is protected, but the device complexity increases
Solution Approach 1:
The clutch member is designed to be self-actuating through a spring bias mechanism. It automatically engages and disengages based on the direction of torque flow without requiring external actuators, sensors, or control systems, thereby providing protection while minimizing added complexity.
Solution Approach 2:
The clutch mechanism uses simple, robust mechanical components including a spring-biased clutch member that can fail safely in a disengaged position. The design prioritizes simplicity and reliability over precision, using basic mechanical elements rather than complex electronic or hydraulic control systems.
3Reliability
If the clutch is biased toward disengagement to prevent backdrive, then overspeed protection is provided, but torque transfer efficiency is reduced during normal operation
Solution Approach 1:
The clutch member transitions between two dynamic states: engaged during normal operation for efficient torque transfer, and disengaged during overspeed conditions for protection. The spring bias creates a dynamic system that responds automatically to changing load conditions, optimizing both power transmission and safety.
Solution Approach 2:
The spring bias pre-positions the clutch member in a state ready to block backdrive forces. During normal operation, the forward torque overcomes the spring bias to engage the clutch. The preliminary positioning ensures immediate protection capability while allowing full power transfer when needed.
Data Source
AI summary
A drive assembly for a work vehicle includes an electric motor configured to rotate a driving shaft and a gear train configured to transmit torque between the driving shaft and a driven shaft. The drive assembly also includes a clutch member having an engaged position and a disengaged position. The clutch member is configured to allow torque transfer between the driving shaft and the driven shaft when in the engaged position. The clutch member is configured to prevent torque transfer between the driving shaft and the driven shaft when in the disengaged position. The clutch member is biased toward the disengaged position to prevent torque transfer in a direction from the driven shaft toward the driving shaft in an overspeed condition of the drive assembly.