Linear Actuator Anti-Backdrive Groove Lock for Unpowered Rod Stability
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Solution Overview
Problem
Existing linear actuators with thrust bearings are prone to inadvertent extension or retraction of the rod when unpowered, leading to motor back-drive, which is not effectively addressed by conventional spring-loaded or wrap-spring brakes, and they often result in efficiency loss, noise, and complex components.
Innovation Solution
Incorporation of a resilient member received in a groove on the rod to prevent back-drive, allowing full travel with no efficiency loss and minimal components, using a spindle to axially move the rod and flex the resilient member out of the groove when a load is applied.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional spring-loaded or wrap-spring brakes are used to prevent back-drive, then motor back-drive is addressed, but efficiency loss, noise, and complex components result
Solution Approach 1:
The invention extracts the back-drive prevention function from complex brake mechanisms and implements it through a simple resilient member (such as a spring clip or elastomeric element) that engages with a groove in the rod. This resilient member is axially fixed to the housing and radially engages the groove to prevent inadvertent rod movement and motor back-drive, eliminating the need for spring-loaded brakes or wrap-spring mechanisms.
Solution Approach 2:
The resilient member automatically engages and disengages from the groove based on rod position and load conditions. When the rod moves axially, the resilient member flexes radially to allow movement, then returns to engage the groove to prevent back-drive. This self-actuating mechanism eliminates the need for external control systems or additional components.
2Ease of operation
If thrust bearings are used in linear actuators, then rod movement is enabled, but inadvertent extension or retraction occurs when unpowered
Solution Approach 1:
The resilient member is pre-positioned to engage the groove and prevent inadvertent rod movement. Before back-drive can occur, the resilient member is already in place to counteract any forces that might cause inadvertent extension or retraction. The resilient member creates a preliminary restraining force that opposes potential back-drive movements.
3Reliability
If a resilient member is received in a groove to prevent back-drive, then motor back-drive is prevented, but full travel with no efficiency loss is maintained
Solution Approach 1:
The resilient member dynamically flexes radially in response to axial rod movement. During powered operation, the resilient member flexes outward to allow full rod travel without restriction. During unpowered conditions, the resilient member returns to engage the groove to prevent back-drive. This dynamic behavior allows the system to maintain energy efficiency during operation while providing back-drive prevention 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
Prevents inadvertent rod movement and motor back-drive, maintaining efficiency and reducing complexity while avoiding noise and additional components.
Implementation Method 1
A resilient member is configured to be received in the groove to prevent back-drive of the motor when the rod is subject to a load. The spindle moves the rod in a first axial direction such that the rod radially outwardly flexes the resilient member.
Data Source
AI summary
An electric linear actuator comprises a housing extending along an axis, a spindle in the housing and extending along the axis, a motor coupled to and configured to rotate the spindle, and a rod coaxially coupled to the spindle and axially movable with respect to the housing in response to rotation of the spindle, the rod comprising a groove. A resilient member is configured to be received in the groove to prevent back-drive of the motor when the rod is subject to a load.