Offset Recess Multi-Component Gear Axial Rigidity
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Solution Overview
Problem
Multi-component gears face challenges in achieving high axial rigidity when limited space and gear width are constraints, as thick-walled plastic bodies often result in void formation and surface indentations during injection molding, making it difficult to produce rotationally symmetrical wheel bodies with H-shaped cross-sections.
Innovation Solution
The design features a connecting part with offset pocket-shaped depressions on its two main surfaces, creating a meandering course that maximizes material distribution on the surfaces, ensuring axial rigidity, and uses a plastic outer part and metal inner part with a form-fitting injection molded connection, employing multiple injection points and potential reinforcement for enhanced rigidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If thick-walled plastic bodies are used to increase axial rigidity, then axial rigidity is improved, but void formation and surface indentations occur during injection molding
Solution Approach 1:
The connecting part is segmented into multiple thin-walled sections separated by recesses, rather than using a single thick-walled structure. This segmentation allows the plastic to be properly injected while maintaining overall structural rigidity through the distributed wall sections.
Solution Approach 2:
The design transitions from a two-dimensional thick wall concept to a three-dimensional meandering wall structure with recesses that create a complex path. This dimensional approach allows material distribution that maintains rigidity while enabling proper injection molding flow.
2Strength
If H-shaped cross section is used to maximize material distribution, then axial rigidity is improved, but rotationally symmetrical wheel bodies cannot be produced
Solution Approach 1:
The H-shaped cross-section concept is adapted by introducing asymmetric recesses that break the symmetry in a controlled way. This allows the structure to achieve H-like material distribution for rigidity while remaining compatible with rotationally symmetrical wheel body production through injection molding.
Solution Approach 2:
Instead of applying uniform thickness throughout, the design implements local variations in wall thickness through strategically placed recesses. This local quality approach concentrates material where needed for rigidity while maintaining manufacturability in other regions.
3Volume of moving object
If limited space and gear width are used, then compact design is achieved, but axial rigidity becomes difficult to ensure
Solution Approach 1:
The design uses thin-walled plastic structures with strategic reinforcement through recesses rather than thick walls. This allows the connecting part to achieve adequate rigidity within limited space constraints by optimizing the thin wall configuration rather than increasing overall thickness.
Data Source
AI summary
The invention relates to a multi-component gear with an outer part (20) with a toothed rim (22), an inner part (30), and a connecting part (40) made of plastic for positively interlocking the inner part (30) and the outer part (20). The outer part (20) is arranged on an outer circumferential surface (45) and the inner part (30) on an inner circumferential surface (44) of the connecting part (40). The connecting part (40) is additionally provided with a plurality of recesses (48, 49) on two opposing, outer main surfaces (46, 47) perpendicular to the axis of rotation (12). The invention is characterized in that the recesses (48) in the first main surface (46) of the connecting part (40) are arranged radially and/or circumferentially offset from each other relative to the axis of rotation (12) compared to the recesses (49) in the second main surface (47) of the connecting part (40).