Polymeric Anti-Backlash Gear with Elastic Protrusions
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Solution Overview
Problem
Conventional gear systems experience noise, vibration, and harshness (NVH) due to backlash issues, which are addressed by introducing clearance between meshing teeth, but this can lead to gear rattle and reduced strength, especially in metal gears.
Innovation Solution
The development of an anti-backlash gear with polymeric gear teeth that feature varying thickness along their flanks, allowing for elastic deformation to absorb backlash, thereby reducing the need for conventional backlash mechanisms and minimizing jamming and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If backlash is introduced to prevent gear teeth binding, then manufacturing tolerances and thermal expansion are accommodated, but gear rattle and noise increase
Solution Approach 1:
The invention changes the physical state of the gear tooth material from rigid (metal) to elastomeric, allowing the material itself to deform and absorb backlash. This parameter change enables the gear to accommodate manufacturing tolerances and thermal expansion while eliminating gear rattle, as the elastomeric material conforms to the mating gear teeth without creating harmful impacts.
Solution Approach 2:
The gear teeth are formed from elastomeric material that acts as a flexible element, replacing the rigid metal structure. This flexible material allows the gear to adapt to manufacturing variations and thermal changes while maintaining continuous contact with mating teeth, thereby preventing backlash-related noise and vibration without requiring additional compliance mechanisms.
2Object-generated harmful factors
If spring-loaded anti-backlash gears are used to eliminate backlash, then gear rattle is reduced, but gear strength is reduced due to material thinning
Solution Approach 1:
The invention fundamentally changes the material parameter from rigid metal to elastomeric polymer, which inherently provides both the compliance needed to eliminate gear rattle and the structural integrity to maintain gear strength. The elastomeric material's viscoelastic properties allow it to deform under load and return to its original shape, providing anti-backlash functionality without requiring material removal or thinning.
Solution Approach 2:
The gear is made from elastomeric material that combines the properties of flexibility and structural strength in a single homogeneous material. This composite approach eliminates the need for separate spring elements and thin gear sections, as the elastomeric material itself provides both the compliance for backlash absorption and the overall structural strength needed for power transmission.
3Manufacturing precision
If metal gears with spring-loaded anti-backlash mechanisms are used, then backlash is controlled, but manufacturing complexity and cost increase
Solution Approach 1:
The invention changes the material parameter to elastomeric, which inherently provides backlash control through its deformable nature. This eliminates the need for complex spring-loaded mechanisms, multi-component assemblies, and precision adjustment systems, simplifying the overall gear structure while maintaining precise backlash control through the material's elastic deformation.
Solution Approach 2:
The elastomeric gear teeth automatically accommodate backlash through their inherent elastic properties, without requiring external spring mechanisms or active control systems. The material self-adjusts to maintain optimal contact with mating teeth under varying loads and temperatures, providing self-regulating backlash control that simplifies the gear design and reduces manufacturing complexity.
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
The polymeric gear teeth effectively absorb backlash, reducing noise and vibration, maintaining strength, and preventing gear jamming, while being easier to manufacture and less prone to wear compared to traditional spring-loaded systems.
Implementation Method 1
each flank comprises two or more surfaces arranged to form a single protrusion extending along the at least one said flank such that a tooth thickness of each gear tooth varies between the top face and the bottom face of said gear tooth... wherein the single protrusion, in use, is elastically deformable so as to absorb backlash
Data Source
AI summary
This anti-backlash gear includes a gear wheel and gear teeth. Each gear tooth comprises first and second flanks, a top face and a bottom face, wherein for each gear tooth each flank extends from the top face to the bottom face, wherein the gear teeth comprise a polymeric material which comprises a repeat unit of form I wherein t1, and w1 independently represent 0 or 1 and v1 represents 0, 1 or 2. For each gear tooth, at least one of said flanks comprises two or more surfaces arranged to form a single protrusion extending along the at least one said flank such that a tooth thickness of each gear tooth varies between the top face and the bottom face of said gear tooth in a direction parallel to an axis of rotation of the gearwheel in operation. In use, the single protrusion is elastically deformable so as to absorb backlash.