Linear Actuator Anti-Rotation D-Shaped Member
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional linear actuators face issues with shaft rotation, leading to inaccuracies and increased maintenance costs due to the need for tight manufacturing tolerances and frequent replacement of sacrificial bearings, while anti-rotation mechanisms often add length to the actuator.
Innovation Solution
A configurable linear actuator design featuring a housing with a bore of varying geometries and an anti-rotation member with a D-shaped geometry, which prevents shaft rotation by limiting contact to specific bearing surfaces, reducing reliance on precise manufacturing dimensions and minimizing wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a sacrificial square bearing is used to guide the shaft, then the shaft positioning accuracy is improved, but the maintenance frequency increases and manufacturing cost increases
Solution Approach 1:
The patent applies the sacrificial bearing principle by using a soft material bearing surface that is intentionally designed to wear preferentially. This disposable bearing layer protects the expensive shaft and housing from wear, requiring only periodic replacement of the bearing surface rather than entire components, thus resolving the contradiction between positioning accuracy and maintenance frequency.
Solution Approach 2:
The patent changes the material parameter of the bearing surface by applying a soft coating or using a material with different hardness properties. This parameter change allows the bearing surface to deform and accommodate manufacturing tolerances while maintaining shaft positioning accuracy, reducing the need for tight tolerances across all components.
2Manufacturing precision
If tight dimensional tolerances are maintained for bearing surfaces, then the shaft positioning accuracy is improved, but the manufacturing cost increases
Solution Approach 1:
The patent applies parameter changes by modifying the material properties of the bearing surface rather than relying solely on tight dimensional tolerances. The soft bearing material compensates for dimensional variations through elastic deformation, allowing relaxed tolerances on shaft and housing dimensions while maintaining positioning accuracy, thereby reducing manufacturing cost.
Solution Approach 2:
The patent uses composite construction by combining a hard shaft material with a soft bearing surface material. This composite approach allows the hard shaft to maintain strength and precision while the soft bearing layer absorbs dimensional variations, enabling cost-effective manufacturing with reduced tolerances on the primary structural components.
3Stability of the object's composition
If an anti-rotation pin is added to prevent shaft rotation, then the shaft rotation is prevented, but the actuator length increases
Solution Approach 1:
The patent merges the anti-rotation function with the existing piston and shaft structure by incorporating asymmetric features directly into these components. The anti-rotation keyway or asymmetric piston shape integrates rotation prevention into the linear motion mechanism itself, eliminating the need for separate anti-rotation pins and reducing overall actuator length.
Solution Approach 2:
The patent applies multi-functionality by designing the piston or shaft with features that simultaneously provide linear motion and prevent rotation. The asymmetric geometry serves dual purposes: driving linear movement while constraining rotational movement, thereby eliminating the need for dedicated anti-rotation components and reducing actuator length.
Data Source
AI summary
A linear actuator is provided having a housing with a bore having at least first and second portions extending therethrough. The second portion has a polygonal geometry with substantially rounded corners having at least one planar bearing surface. A shaft is in sliding engagement with the first portion of the bore, and a piston member is operatively coupled to the shaft. The piston member has a mating geometry to the second portion of the bore, wherein the piston member is in sliding engagement with the second portion of the bore. An anti-rotation member is coupled to the piston member or shaft and has a generally D-shaped geometry with a planar anti-rotation bearing surface. Contact between the anti-rotation member and the housing is limited to a sliding engagement between the anti-rotation bearing surface and one of the at least one bearing surfaces based on an orientation of the anti-rotation member.