Non-Backdrivable Clutch Module for Actuator Impact Isolation
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Solution Overview
Problem
Existing bi-directional actuators face challenges in preventing backdriving torque transfer, protecting the system from large torque inputs, and decoupling output shaft vibrations and impact loads from the input drive, while also requiring mechanical solutions for position return without electrical sensors.
Innovation Solution
A non-backdrivable clutched module with a housing containing an input shaft cog and a clutched output shaft, featuring a clutch cog with both resilient and detent connections, which locks the clutch cog to prevent backdriving and disengages under excessive forces, diverting torque backdriving forces to the housing and allowing decoupling of the output shaft during impacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a clutch device is used to prevent backdriving torque transfer, then the actuator is protected from backdriving forces, but the device complexity increases due to additional clutch mechanisms
Solution Approach 1:
The clutch mechanism is segmented into modular components: clutch cogs, bearing members, detent features, and resilient members. Each component performs a specific function (torque transfer, locking, positioning, or springing), allowing the complex backdriving protection system to be built from simple, interchangeable parts that can be manufactured and assembled independently.
Solution Approach 2:
The clutch cog acts as an intermediary element between the input shaft cog and the output shaft. It selectively engages with both components through toothed interfaces, transferring torque when needed while allowing the bearing members and detent features to mediate the locking and positioning functions, thereby protecting the actuator without requiring direct complex coupling.
2Reliability
If the clutch cog locks to prevent backdriving, then torque transfer is blocked, but the ease of operation decreases due to additional locking mechanisms
Solution Approach 1:
The clutch mechanism is designed to automatically engage and disengage based on the direction of torque application. When backdriving torque is applied to the output shaft, the clutch cog automatically shifts to engage the bearing members and lock, preventing torque transfer to the input shaft. When forward torque is applied, the clutch cog naturally disengages from the locking position, allowing smooth operation without requiring external control signals or complex actuation mechanisms.
Solution Approach 2:
The clutch cog and bearing members are positioned asymmetrically within the housing such that the clutch cog can only engage the bearing members in one direction (when backdriving torque is applied). The detent features on the clutch cog align with corresponding recesses in the housing only in the locked position, creating a mechanical asymmetry that automatically prevents backdriving while allowing free forward operation.
3Reliability
If the output shaft decouples during impact, then the actuator is protected from impact loads, but the stability of the connection deteriorates
Solution Approach 1:
The resilient members (springs) are pre-loaded and positioned to engage the clutch cog and bearing members before any impact occurs. These springs maintain a constant force that keeps the clutch mechanism in a ready state, allowing the clutch cog to quickly shift into the locked position with bearing members upon impact. The springs absorb and dissipate impact energy, cushioning the actuator from sudden loads while maintaining connection stability during normal operation through their pre-compressed state.
Solution Approach 2:
The clutch mechanism transitions dynamically between two stable states: engaged (normal operation) and disengaged (impact protection). During normal operation, the clutch cog maintains a stable connection through detent features and pre-compressed resilient members. Upon impact, the system dynamically shifts to a protected state where the clutch cog engages with bearing members to decouple the output shaft, absorbing impact energy. After impact, the system dynamically returns to the engaged state, maintaining connection stability when needed.
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 backdriving forces from reaching the input drive, protects the actuator from damage, and enables mechanical decoupling and position return without electrical sensors, ensuring safe operation and reliability in bi-directional actuator systems.
Implementation Method 1
The clutch cog has both a resilient connection and a detent connection to the clutch cog portion of the clutched output shaft
Implementation Method 2
The clutch cog has both a resilient connection and a detent connection to the clutch cog portion of the clutched output shaft
Data Source
AI summary
A non-backdrivable clutched module for a bi-directional actuator such as actuators used for active aerodynamics on vehicles. The module has both a stopper mode and a clutch mode. During the stopper mode a back-driving force gets diverted away from the actuator using a locking bearing member. If the force is too great a clutch mode will disengage the back-driving force completely from the shaft connected to the actuator, thereby preventing damage to the actuator.