Linear Actuator Anti-Backdrive Mechanism With One-Way Bearing
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Solution Overview
Problem
Existing electric linear actuators face challenges in preventing back-drive of the motor when an external load is applied to the actuator, especially when the motor is not powered.
Innovation Solution
The implementation of a one-way bearing configured to prevent back-drive of the motor by allowing free rotation in the high-efficiency direction and locking in the low-efficiency direction, combined with a thrust bearing to reduce friction and enhance efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a one-way bearing is added to prevent motor back-drive, then motor back-drive prevention is improved, but device complexity increases
Solution Approach 1:
A one-way bearing is introduced as an intermediary component between the motor and the external load. This bearing allows the motor to rotate freely in the forward direction while preventing reverse rotation that would cause back-drive. The one-way bearing acts as a selective mediator that permits motion in one direction while blocking motion in the opposite direction, thereby solving the back-drive prevention problem without requiring complex control systems or additional actuation mechanisms.
2Loss of energy
If friction is reduced to enhance efficiency, then energy efficiency is improved, but motor back-drive prevention becomes more difficult
Solution Approach 1:
The actuator system is segmented into distinct functional components: a thrust bearing that handles axial loads and reduces friction for efficient operation, and a one-way bearing that specifically addresses back-drive prevention. By separating these functions into different bearing components, the system achieves low friction through the thrust bearing while maintaining back-drive protection through the one-way bearing's mechanical locking mechanism. This segmentation allows each component to be optimized for its specific function without compromising the other.
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 solution effectively prevents motor back-drive when external loads are applied, while maintaining high efficiency during operation, thus ensuring reliable and efficient actuation even without continuous motor power.
Implementation Method 1
A one-way bearing is configured to prevent back-drive of the motor when the spindle is subject to an external load via the rod
Implementation Method 2
a thrust bearing provided coaxially on the spindle. The thrust bearing is located between the proximal end of the spindle and the rod
Data Source
Figure 1
Figure 2
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AI summary
The present invention relates to an electric linear actuator (110) comprising: - a housing (112) extending along a longitudinal axis (L); - a spindle (114) provided in the housing and extending along the longitudinal axis from a proximal end (136) to a distal end (138); - a motor (122) coupled to the proximal end of the spindle and configured to rotate the spindle; - a rod (116) coaxially coupled to the spindle and movable with respect to the housing along the longitudinal axis in response to rotation of the spindle; and - a one-way bearing (146) configured to prevent back-drive of the motor when the spindle is subject to an external load via the rod.