Rotary Lock Assembly for Reliable Linear Actuator Unlocking
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Solution Overview
Problem
Conventional linear actuators face challenges such as indirect locking, increased size and mass, fatigue due to flexing lock elements, low external load carrying capability, and the need for additional mechanical inputs for unlocking, particularly under high mechanical loads.
Innovation Solution
A rotary-to-linear motion conversion device employing a multi-stage planetary gearbox with a rotary lock assembly that includes epicyclic gear assemblies and a lock key system, allowing for automatic torque redirection to overcome binding and facilitate reliable unlocking without additional control or power inputs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional lock mechanisms are used, then locking function is provided, but the locking is indirect and reliability is reduced
Solution Approach 1:
The patent extracts the locking function from the synchronization system and creates a direct locking mechanism on the output ram itself. The lock sleeve and lock keys are directly engaged with the output ram, eliminating the need for indirect synchronization-based locking and providing direct, reliable retention of the output position.
Solution Approach 2:
The patent introduces a lock sleeve as an intermediary component that directly engages with the output ram through lock keys. This intermediary mechanism provides direct locking action between the locking system and the output ram, improving reliability by eliminating the indirect synchronization dependency.
2Reliability
If direct locking mechanisms with multi-piece housing are used, then direct locking is achieved, but size and mass increase
Solution Approach 1:
The patent merges the locking mechanism components (lock sleeve, lock keys, spring) into a compact assembly that integrates with the existing actuator housing. The single-piece housing design combines the structural support and locking function in one integrated unit, reducing overall mass compared to multi-piece constructions while maintaining direct locking capability.
3Device complexity
If flexing lock elements are used, then single-piece housing is enabled, but fatigue occurs due to flexing
Solution Approach 1:
The patent employs a dynamic spring-loaded lock key system where the lock key can flex radially within defined limits to engage and disengage from the output ram. The spring provides the necessary force for engagement while allowing controlled flexing motion, enabling the single-piece housing design without excessive permanent deformation or fatigue failure.
Solution Approach 2:
The patent changes the operational parameters of the lock key by introducing spring-loaded force and controlled flexing range. The lock key is designed to flex within specific dimensional limits under spring force, allowing engagement/disengagement cycles without accumulating damaging stress that would lead to fatigue failure.
4Ease of operation
If ball lock mechanisms are used, then rotary operation is achieved, but external load carrying capability is reduced due to point contact stresses
Solution Approach 1:
The patent uses a rotary lock sleeve with curved engagement surfaces that contact the lock keys and output ram. The spherical/curved geometry of the lock sleeve allows rotary operation while distributing contact stresses over larger surface areas compared to point-contact ball locks, thereby maintaining higher external load carrying capability.
5Ease of operation
If additional mechanical inputs are used for unlocking, then unlocking control is provided, but device complexity and power requirements increase
Solution Approach 1:
The patent employs a spring-loaded lock key system that automatically engages and disengages based on the position and motion of the output ram. The spring force provides the unlocking action automatically when the ram moves to the retracted position, eliminating the need for additional mechanical inputs, solenoids, or external power sources for unlocking control.
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 effectively locks linear actuators against unintended extension, provides reliable unlocking under high mechanical loads, and automatically supplies the necessary torque for unlocking, enhancing the system's reliability and operational efficiency.
Implementation Method 1
a first epicyclic gear assembly having a first sun gear assembly, a first ring gear assembly, and a first planet gear assembly mechanically engaged to the first sun gear assembly and the first ring gear assembly
Implementation Method 2
a screw lead engaged to the first planet gear assembly and responsive to revolution of the first planet gear assembly, and a nut engaged with the screw lead and axially movable along the screw lead in response to rotation of the screw lead
Implementation Method 3
a lock key configured for radial displacement between a first lock key configuration and a second lock key configuration, and a lock rotor configured to be rotated by the second planet gear assembly
Data Source
AI summary
The subject matter of this specification can be embodied in, among other things, a rotary lock assembly that includes a first epicyclic gear assembly having a first sun gear assembly, a first ring gear assembly, and a first planet gear assembly mechanically engaged to the first sun gear assembly and the first ring gear assembly, and a second epicyclic gear assembly having a second sun gear assembly configured to be rotated by the first ring gear assembly, a second ring gear assembly, and a second planet gear assembly mechanically engaged to the second sun gear assembly and the second ring gear assembly.