Linear Actuator Self-Locking Drive With Stable Friction Locking
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Solution Overview
Problem
Conventional self-locking mechanisms in electric lifting columns, such as those using worm and worm gear drives or torsion springs, suffer from deteriorating self-locking performance due to decreased friction coefficients under increased loads, leading to instability and reduced effectiveness over time.
Innovation Solution
A self-locking drive mechanism featuring a friction seat and friction ring, secured by a snap-fitting system, which allows for two-way self-locking and includes a lubrication system to maintain friction force stability, along with a pin shaft for secure mounting and snap springs for axial positioning, ensuring stable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional self-locking mechanisms (worm gear or torsion spring) are used, then initial self-locking function is achieved, but self-locking performance deteriorates over time under increased load
Solution Approach 1:
The patent changes the friction parameters by selecting specific materials (PEEK for friction ring, POM100P for friction seat) with optimized friction coefficients. The interference fit design between friction ring and friction seat creates optimal contact pressure, maintaining consistent friction force over time regardless of load increases.
2Force
If increased load is applied to worm gear, then lifting capacity is improved, but friction force decreases leading to self-locking deterioration
Solution Approach 1:
The patent extracts the self-locking function from the worm gear mechanism and implements it independently through the friction ring and friction seat assembly. This separate self-locking mechanism is not affected by worm gear stress, allowing the worm gear to handle increased lifting loads while the friction-based mechanism maintains consistent self-locking performance.
3Reliability
If torsion spring is used for self-locking, then initial locking is achieved, but friction coefficient decreases after operation leading to performance deterioration
Solution Approach 1:
The friction ring and friction seat assembly is designed to maintain its friction characteristics through proper material selection and interference fit design. The system serves itself by maintaining optimal contact pressure between the friction surfaces, ensuring consistent self-locking performance throughout operational life without degradation.
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 mechanism provides stable self-locking performance by maintaining consistent friction force, preventing back rotation and axial displacement, while reducing wear and assembly damage, thus enhancing the reliability and precision of linear actuators.
Implementation Method 1
Relative rotation between the friction seat and the friction ring can create a friction force, the friction force amounting to the self-locking force for the self-locking mechanism
Implementation Method 2
the friction seat being interference-fitted with the friction ring to enable two-way self-locking to the drive shaft
Data Source
AI summary
A self-locking drive, usable in a linear actuator, includes a housing and a drive shaft for outputting a driving force. An endcap is provided at an end portion of the housing. A self-locking mechanism configured to apply a self-locking force to the drive shaft is provided in the endcap. The self-locking mechanism includes a friction seat sleeved over the drive shaft and rotatable synchronously with the drive shaft, and a friction ring mounted in the endcap and secured to the endcap. The friction seat is interference-fitted with the friction ring to enable two-way self-locking to the drive shaft.