Linear Actuator Shaft Overlap for Compact Packaging
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Solution Overview
Problem
Conventional linear actuators require a significant increase in length or height due to the need for separate sections for anti-rotation and actuation, often necessitating a shaft that extends at least twice or three times the stroke length, which increases packaging size and space occupation.
Innovation Solution
The design allows various sections along the shaft to axially overlap, enabling the same functionality while reducing the actuator's length by at least the distance of a stroke, achieved through a rotor assembly with a lead screw and stator assembly that selectively rotates the rotor, and a body assembly with a shaft and shaft tube, where the shaft is keyed to prevent rotation with the rotor, allowing axial displacement between extended and retracted positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate sections for anti-rotation and actuation are used in conventional linear actuators, then the actuator can perform both functions reliably, but the length or height of the actuator increases significantly
Solution Approach 1:
The patent combines the anti-rotation function and actuation function into a single integrated shaft structure. The shaft simultaneously serves as the actuation element that moves linearly and as the anti-rotation element that prevents rotational movement, eliminating the need for separate sections and reducing overall actuator length.
Solution Approach 2:
The shaft is designed as a multi-functional component that performs both actuation and anti-rotation functions. By making the shaft universal in its functionality, the patent reduces the number of separate components needed, thereby reducing the actuator's length while maintaining reliable performance of both functions.
2Reliability
If the shaft extends at least twice or three times the stroke length to accommodate separate anti-rotation and actuation sections, then both functions can be performed, but the packaging size and space occupation increase
Solution Approach 1:
The patent merges the anti-rotation section and actuation section into a single shaft structure, allowing both functions to occur within the same spatial envelope. This eliminates the need for the shaft to extend multiple times the stroke length, significantly reducing packaging size while maintaining full functional capability.
Solution Approach 2:
The anti-rotation functionality is nested within the actuation shaft structure. The shaft contains both the actuation features (threaded portions for linear motion) and anti-rotation features (keyways or splines) in a nested arrangement, allowing compact packaging while maintaining both functions.
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 design significantly reduces the packaging size by allowing the actuator to occupy less space while maintaining the functionality of conventional actuators, achieving displacement between extended and retracted positions without the need for excessive length, thus reducing the height by at least the stroke length.
Implementation Method 1
The stator may generate a magnetic field that forces the rotor to rotate relative to the stator
Implementation Method 2
The rotation of the rotor may be converted into linear motion by a lead screw or shaft
Data Source
AI summary
A linear actuator is provided. The linear actuator includes a rotor assembly including a rotor and a lead screw. The lead screw is rotationally coupled to the rotor for rotation therewith. The linear actuator further includes a stator assembly configured to selectively rotate the rotor in a desired direction, and a body assembly having a shaft and a shaft tube. The shaft is keyed to the shaft tube and prevented from rotating with the rotor. The shaft includes an inner bore configured to threadably receive the lead screw therein. Selective rotation is configured to displace the shaft between an extended position and a retracted position.