All-Plastic Oldham Coupler for Reduced Width and Wear
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Solution Overview
Problem
Oldham couplers used in color electrophotographic printers face issues with banding due to low frequency oscillations, and the combination of metal and plastic materials leads to increased costs and uneven wheel wear, with the current design being bulky and having a higher side load.
Innovation Solution
An Oldham coupler assembly with input and output plates made of a first material and a drive plate made of a second material, featuring gear teeth and orthogonal slots for wheels of equal diameter, and a retractable spline assembly for improved torsional stiffness and reduced width, allowing for equal wheel diameters and reduced wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metal input and output plates with plastic drive plate are used, then torsional stiffness is improved, but manufacturing cost increases
Solution Approach 1:
The patent applies homogeneity by making the input plate, output plate, and drive plate all from the same plastic material (acetal copolymer), eliminating the need for dissimilar metal and plastic materials. This reduces manufacturing complexity and cost while maintaining sufficient torsional stiffness through optimized geometry and material properties.
Solution Approach 2:
The patent uses composite material properties by selecting acetal copolymer plastic that combines strength, stiffness, and self-lubricating characteristics. This single material provides both structural integrity for torsional stiffness and wear resistance, replacing the need for metal components.
2Strength
If dissimilar materials (metal drive plate and plastic wheels) are used, then torsional stiffness is improved, but wheel wear increases due to sliding
Solution Approach 1:
The patent makes both the drive plate and wheels from the same plastic material, creating homogeneous material contact throughout the mechanism. This eliminates the dissimilar material interface that caused sliding and wear, while the self-lubricating properties of the plastic reduce friction and wear across all contact surfaces.
3Length of moving object
If narrower slots and smaller diameter wheels are used due to size constraints, then device width is reduced, but wheel wear increases and side load increases
Solution Approach 1:
The patent changes the material parameters by using plastic instead of metal, allowing for larger wheel diameters and wider slots within the same size constraints. The plastic material's lower density and different mechanical properties enable larger dimensional parameters without exceeding width limits, thereby reducing side loads and wheel wear.
4Reliability
If study or screw attachment of wheels is used, then wheel attachment is secure, but overall width of Oldham coupler increases
Solution Approach 1:
The patent merges the wheel attachment function into the wheel and drive plate structure itself by using integral hub features that snap-fit or press-fit directly onto the drive plate slots. This eliminates separate studs or screws and their associated mounting space, reducing the overall width while maintaining secure attachment through integrated design.
Data Source
AI summary
An Oldham coupler assembly for transferring rotary power between two shafts in an imaging device. The Oldham coupler includes an input plate, an output plate, and a drive plate and two pairs of coupling wheels, and, in one embodiment, made of the same plastic material. The drive plate has a pair of open-ended slots along one axis and a close-ended center slot along a second axis orthogonal to the first axis. The drive plate is mechanically coupled and positioned in between the input plate and the output plate. A plastic retraction spline assembly is slidably retained in the output plate and engages with a drive member in an imaging unit. The input plate includes gear teeth integrally molded into the outer circumference thereof decreasing the overall width of the Oldham coupler. The two pairs of coupling wheels have the same diameter.