Ribbed Gear Structure for Axial Rigidity and Low Weight
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Solution Overview
Problem
Existing gear designs face challenges in achieving high axial rigidity and radial load capacity while minimizing weight and installation space, especially under high axial forces encountered in helical gearing, where known rib designs either compromise on material homogeneity or limit radial load capacity.
Innovation Solution
A gear design featuring ribs that extend along tangents, with a tangent circle diameter defined by the torque-transmitting diameter plus a maximum of six times the rib thickness, allowing for high torsional rigidity and axial stiffness without excessive material usage, and enabling various manufacturing processes including injection molding for plastic components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the width of the gear is increased to counteract deformations under axial loads, then axial rigidity is improved, but weight and installation space increase
Solution Approach 1:
The patent applies local quality by strategically positioning ribs at specific locations within the gear structure rather than uniformly increasing the entire gear width. The ribs are arranged to provide localized reinforcement exactly where axial loads create deformations, allowing the gear to achieve necessary axial rigidity without adding material throughout the entire gear body, thus avoiding unnecessary weight increase.
Solution Approach 2:
The gear structure is segmented into functional zones: the rib-reinforced regions that provide axial stiffness and the reduced-material regions that minimize weight. This segmentation allows different parts of the gear to have different structural characteristics - reinforced where needed, lightweight where not required - resolving the contradiction between rigidity and weight.
2Strength
If the width of the gear is increased to counteract deformations under axial loads, then axial rigidity is improved, but installation space increases
Solution Approach 1:
By applying local quality through strategically positioned ribs, the gear achieves the required axial rigidity without increasing its overall width or external dimensions. The reinforcement is concentrated in specific internal regions, allowing the gear to maintain a compact footprint suitable for limited installation spaces while still providing adequate structural stiffness under axial loads.
3Strength
If meandering ribs are used to increase axial rigidity, then axial deformations are reduced, but material homogeneity deteriorates due to unfavorable flow paths in injection molding
Solution Approach 1:
Instead of using conventional meandering rib patterns that create complex flow paths, the patent inverts the approach by using straight, radially oriented ribs. This inverted design simplifies the injection molding flow paths, allowing molten plastic to flow more uniformly through the mold cavity, thereby improving material homogeneity while still achieving the desired axial rigidity through the strategic positioning and dimensional characteristics of the ribs.
Solution Approach 2:
The patent changes the geometric parameters of the ribs - specifically using straight rather than curved paths, and controlling rib thickness and spacing - to optimize both structural performance and manufacturability. These parameter changes create favorable flow characteristics for injection molding while maintaining the axial rigidity needed to reduce deformations under load.
4Strength
If ribs with convex and concave sections are used, then axial rigidity is improved, but radial load capacity is limited due to bending moments within the ribs
Solution Approach 1:
The patent applies local quality by using straight ribs with optimized thickness and spacing that create compressive stress distributions favorable for resisting radial loads. Rather than using convex-concave profiles that induce bending moments, the straight rib configuration with controlled dimensions provides localized reinforcement that simultaneously addresses both axial rigidity and radial load capacity by creating a stress distribution that minimizes bending while maintaining stiffness.
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
The present invention relates to a gear comprising an outer part (12) with a toothed rim (14), an insert part (16) having an insert part outer diameter (dEa) and a receiving section (32) with an insert part inner diameter (dEi) for forming a shaft-hub connection, and a connecting part (18) arranged between the insert part (16) and the outer part (12), which connects the insert part (16) and the outer part (12) in a form-fit and/or material-fit and/or friction-fit manner, wherein the connecting part (18) has a number of ribs (27) or the connecting part (18) is formed by a number of ribs (27), wherein the ribs (27) each extend along a tangent (T) which abuts a tangent circle (CT), wherein the tangent circle (CT) has a tangent circle diameter (dCT).which is larger than or equal to the insert's inner diameter (dEi) and smaller than or equal to the insert's outer diameter (dEa).