Gear Train Backlash Elimination Using Composite Sub-Gears
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Solution Overview
Problem
Existing gear trains with multiple gear wheels face challenges in minimizing backlash and maintaining a compact design, as they require multiple composite gear wheels with spring-biased sub-gear wheels, leading to increased width and complexity.
Innovation Solution
A gear train design where only one end gear wheel and at least one intermediate gear wheel are composite, featuring concentric sub-gear wheels that can angularly offset against a spring force, eliminating backlash without the need for spring coupling between all sub-gear wheels, allowing for a more compact and efficient configuration with fewer composite gear wheels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple composite gear wheels with spring-biased sub-gear wheels are used to eliminate backlash, then backlash is reduced, but the width and complexity of the gear train increases
Solution Approach 1:
The gear train is segmented into different functional zones: one end gear wheel is composite with spring-biased sub-gear wheels, intermediate gear wheels are composite but without spring coupling, and the other end gear wheel may be simple or composite. This segmentation allows backlash elimination at critical interfaces while reducing overall complexity.
Solution Approach 2:
Spring bias is applied locally only at the end gear wheels where backlash elimination is most critical, rather than uniformly across all composite gear wheels. The intermediate composite gear wheels provide structural support and tooth engagement without requiring spring mechanisms, optimizing the balance between performance and complexity.
2Reliability
If every second gear wheel is made composite with spring biased sub gear wheels, then backlash is eliminated, but the width of composite gear wheels increases
Solution Approach 1:
The spring coupling mechanism is extracted from intermediate composite gear wheels, retaining only the essential composite structure with multiple sub-gear wheels. This removal of non-essential spring mechanisms reduces the width of intermediate gear wheels while maintaining backlash elimination through the composite tooth engagement geometry.
3Reliability
If composite gear wheels have three sub gear wheels, then backlash is eliminated, but the device becomes wider
Solution Approach 1:
Instead of requiring three sub-gear wheels in all composite gear wheels, the invention uses partial action by implementing composite structures with two sub-gear wheels in intermediate positions. This partial implementation is sufficient to eliminate backlash through proper angular offset and meshing geometry, avoiding the excessive width that would result from universal three-sub-gear-wheel construction.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design effectively eliminates backlash in gear trains with multiple gear wheels, reducing the number of composite gear wheels and their width, while maintaining a tight fit between meshing teeth, even when all intermediate gear wheels are composite, thus enhancing mechanical efficiency and reducing complexity.
Implementation Method 1
one of the at least three gear wheels is a composite gear wheel comprising two concentric sub gear wheels which are disposed in face to face relation, which composite gear wheel further comprises a spring interconnecting both sub gear wheels, such that both sub gear wheels can be turned around their mutual axes over an angle with respect to each other against the spring force
Data Source
Figure 1~3
Figure 4~6
Figure 7~9
AI summary
A gear train (1) comprises three toothed gear wheels (3, 5 and 7) of which two gear wheels (3 and 7) are end gear wheels and one gear wheel (5) is an intermediate gear wheel which meshes with both end gear wheels (3 and 7). Two gear wheels (3 and 5) are composite gear wheels, each comprising two concentric sub gear wheels (3a, 3b and 5a, 5b) which are disposed in face to face relation. Composite gear wheel (3) further comprises an annular torsion spring (7) interconnecting both sub gear wheels (3a and 3b). The sub gear wheels (3a and 3b) function as a single gear wheel and are angularly offset from each other by the spring (7). The offset amounting to a fraction of a gear tooth. The effect is to maintain a tight fit between meshing gear teeth so that all backlash with the adjacent gear wheel (5) is eliminated.