Helical Plastic Gear Structure for Low-Noise Compact Drives
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Solution Overview
Problem
Existing plastic gears with straight toothing in motor vehicle auxiliary drives face challenges with noise development, running issues, and meeting strength and space-saving requirements.
Innovation Solution
A plastic gear design featuring oblique toothing with a specific opening angle, reinforcement structures, and sack-shaped openings arranged on circular rings, optimized for reduced noise and increased strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If spur gearing with straight toothing is used, then the gear is simple to manufacture, but noise generation increases and smooth running deteriorates
Solution Approach 1:
The patent changes the toothing geometry parameter from straight (spur) gearing to helical gearing with a specific helix angle. This parameter change transforms the engagement pattern of teeth, allowing gradual contact between mating teeth rather than sudden impact, thereby reducing noise generation and improving smooth running while maintaining manufacturability through injection molding
2Volume of moving object
If the gear is made compact with small installation space, then space requirements are met, but strength requirements may be compromised
Solution Approach 1:
The patent segments the intermediate section by introducing multiple openings arranged on circular rings, creating a lattice-like structure. This segmentation reduces material usage and installation space while the strategic placement of reinforcing ribs between openings compensates for strength, achieving both compactness and required strength for auxiliary drive applications
Solution Approach 2:
The patent adds a dimensional aspect by arranging openings and reinforcing ribs in a three-dimensional configuration with multiple circular rings at different radial positions. This spatial arrangement allows the gear to maintain strength through distributed reinforcement while minimizing overall volume and installation space
3Weight of moving object
If openings are added to the intermediate section, then weight is reduced and space is saved, but structural strength may be compromised
Solution Approach 1:
The patent applies local quality by placing reinforcing ribs in specific locations between the openings, particularly concentrating reinforcement where stresses are highest. The openings are strategically positioned and sized to reduce weight while the local reinforcement ensures structural integrity is maintained in critical areas
Solution Approach 2:
The patent creates a composite-like structure within the monolithic plastic gear by combining opening regions (voids) with reinforcing rib regions (solid material). This internal composite architecture optimizes the strength-to-weight ratio, achieving weight reduction through openings while maintaining structural strength through the reinforced lattice pattern
Data Source
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AI summary
The invention relates to a gear (1) formed in one piece from plastic, comprising: - an axis of rotation (R), - external teeth (10) arranged about an axis of rotation, - a centrally arranged receiving opening (40), - an intermediate section (30) arranged between the external teeth (10) and the receiving opening (40), - a reinforcing structure arranged in the intermediate section (30) with a plurality of openings (32, 33) and reinforcing ribs (34, 35) located between the openings, characterized by the following further features: - the external teeth (10) are designed as helical teeth with a helix angle (W) to the axis of rotation (R), - at least a portion of the openings (32, 33) follow at least approximately the helix angle (W) of the helical teeth with an opening angle (V). The invention also relates to a method for manufacturing such a gear.