Linear Actuator Backlash Elimination via Asymmetric Thread Engagement
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Solution Overview
Problem
Linear actuators with thread-based components suffer from backlash, which can significantly affect positioning accuracy, especially in applications like microwave resonant cavities, and existing backlash-compensating actuators are complex and expensive.
Innovation Solution
A linear actuator design featuring a drive arm and an extension arm with resiliently deformable fingers that interengage threads, ensuring the ridge of one thread abuts both sides of the groove of the other, eliminating backlash and allowing for precise linear motion without rotational interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If standard thread-based coupling is used between drive arm and extension arm, then the structure is simple and manufacturing is easy, but backlash occurs causing positioning inaccuracy
Solution Approach 1:
The thread profiles of the drive arm and extension arm are designed with asymmetric geometry where the ridge of one thread does not perfectly match the groove of the other. This intentional asymmetry creates continuous contact between the thread surfaces, eliminating backlash while maintaining simple manufacturing processes. The asymmetric design ensures that during rotation in either direction, one surface of the ridge continuously abuts the corresponding surface of the groove, preventing play without requiring complex compensation mechanisms.
2Manufacturing precision
If backlash compensation mechanisms are added to improve positioning accuracy, then positioning precision improves, but device complexity and cost increase significantly
Solution Approach 1:
The invention extracts and eliminates the source of backlash at its origin - the thread interface itself - rather than adding complex compensation mechanisms. By redesigning the thread geometry to inherently prevent backlash through asymmetric ridge-groove engagement, the solution removes the need for optical feedback circuits, electrical sensors, or other complex compensation systems, thereby maintaining simplicity while achieving high positioning accuracy.
Solution Approach 2:
The invention converts the potential harm of thread play into a beneficial continuous contact mechanism. By designing the thread profiles so that the ridge surfaces continuously abut the groove surfaces during rotation, the design transforms what would normally be a source of backlash into a positive feature that ensures constant engagement and eliminates play without requiring additional complexity.
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
The solution provides a simple, cost-effective, and reliable linear actuator that maintains zero backlash even with wear, ensuring accurate positioning and minimal rotational force transfer, suitable for applications where precision is critical.
Implementation Method 1
one of the arms having a plurality of resiliently deformable fingers extending beyond the end of the arm towards the other arm, at least one of the fingers having a thread on its inner face
Data Source
AI summary
A linear actuator includes a drive arm and an extension arm each extending along a common drive axis. One of the arms has a plurality of resiliently deformable fingers extending beyond the end of the arm towards the other arm. At least one of the fingers has a thread on its inner face while the other arm has a threaded portion. At least part of the threaded portion is received between the fingers. The fingers are adapted to urge the threads of the two arms into interengagement such that rotation of the drive arm about the drive axis displaces the extension arm along the drive axis. The two threads are arranged such that when the ridge of one thread is received in the groove of the other thread the two sides of the ridge abut the two edges of the mouth of the groove.