Dual-Screw Linear Actuator Nested Design
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Solution Overview
Problem
Conventional linear actuators have limited stroke extension or contraction due to single screw design, leading to increased size and reduced stability when trying to increase stroke, making them unsuitable for space-limited applications and compromising supporting force.
Innovation Solution
A dual-screw linear actuator design featuring an inner and outer push tube with interlocking nut parts and screws, allowing synchronous extension or contraction without increasing axial length, and improving stability by varying external diameters for reduced load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single screw is used to extend or contract the linear actuator, then the structure is simple, but the stroke is limited by the length of the single screw
Solution Approach 1:
The patent employs a nested dual-screw structure where the inner screw is positioned inside the outer screw. The inner screw drives the inner push tube while the outer screw drives the outer push tube, allowing both screws to work simultaneously within a compact arrangement. This nesting enables doubled stroke without increasing the overall actuator length, resolving the contradiction between structural simplicity and extended stroke capability.
2Length of moving object
If the length of the screw is increased to increase the stroke, then the stroke increases, but the axial length or size for installation must be increased
Solution Approach 1:
The inner screw and outer screw are arranged in a nested configuration where the inner screw is housed within the outer screw. This allows both screws to contribute to the stroke simultaneously without increasing the axial length of the actuator. The nested arrangement enables the stroke to be doubled while maintaining a compact size suitable for space-limited applications.
3Length of moving object
If dual screws are arranged in parallel to increase the stroke, then the stroke increases, but the width and size for installation increase and supporting force decreases
Solution Approach 1:
The patent uses a nested arrangement where the inner screw is positioned inside the outer screw rather than parallel placement. This nested configuration maintains a compact width and size while enabling doubled stroke through coordinated operation of both screws. The concentric arrangement preserves structural stability and supporting force by keeping the center of gravity aligned and minimizing the moment arm, unlike parallel arrangements that increase width and reduce stability.
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 dual-screw design doubles the stroke of extension or contraction without increasing the actuator's size, enhancing stability and supporting force, making it suitable for space-limited applications with longer adjusting intervals.
Implementation Method 1
the inner screw rotates, the outer screw is driven to rotate, such that first and second nut parts on the inner and outer screws are capable of pushing the inner and outer push tubes synchronously for an extension or a contraction
Data Source
AI summary
A dual-screw linear actuator includes an inner push tube, an outer push tube, a first nut part, and a second nut part. The outer push tube is sheathed on the inner push tube and axially movable on the inner push tube; the first nut part is coupled to the outer push tube and screwed to an inner screw which has a coupling disposed at a front end of the inner screw; the second nut part is coupled to the inner push tube and screwed to an outer screw, and the outer screw is hollow, and the coupling is sleeved into the outer screw for an axial movement. The inner screw drives the outer screw to rotate, such that the first and second nut parts can synchronously push the inner and outer push tubes to extend or contract, so as to improve the stroke of extension or contraction.