Gearbox Non-Integer Speed Ratios for Vibration Reduction
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Solution Overview
Problem
Conventional gearboxes in rotating machinery, such as gas turbine engines, experience significant vibrations due to imbalances and external forces, leading to resonance and reduced lifespan, with existing damping systems often ineffective in managing cross-shaft vibrations and weight-intensive designs.
Innovation Solution
Designing gearboxes with non-integer speed ratios and maintaining minimum distances from integer ratios, using irrational numbers to minimize vibrations, and ensuring that all gear pairs have coprime tooth numbers to reduce resonance and wear, thereby extending the gearbox's lifespan and maintenance intervals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If damping systems are added to reduce vibrations, then vibration reduction is achieved, but weight increases
Solution Approach 1:
The invention changes the speed ratio parameter from an integer to a non-integer value, specifically using irrational numbers. This parameter change fundamentally alters the vibration characteristics of the gearbox, eliminating resonances that occur at integer speed ratios without requiring additional damping components, thus reducing weight while maintaining vibration control
Solution Approach 2:
Instead of adding damping systems to suppress vibrations after they occur, the invention inverts the approach by designing the speed ratio to prevent resonance conditions from occurring in the first place. By using non-integer speed ratios, the system avoids the harmful resonant vibrations that would otherwise require damping elements to control
2Object-affected harmful factors
If damping systems are added to reduce vibrations, then vibration reduction is achieved, but device complexity increases
Solution Approach 1:
The invention simplifies the device by changing the speed ratio parameter to a non-integer value, which inherently prevents resonance conditions. This eliminates the need for complex damping systems, bearing arrangements, or other vibration reduction components, thereby reducing device complexity while maintaining effective vibration control
3Ease of manufacture
If integer speed ratios are used, then manufacturing is simplified, but vibrations and resonances increase
Solution Approach 1:
The invention changes the speed ratio parameter from an integer to a non-integer (irrational) value. This parameter change eliminates resonant vibrations caused by integer speed ratios while maintaining manufacturing feasibility through precise but achievable non-integer ratio design
4Object-affected harmful factors
If damping systems are designed for nominal conditions, then vibration reduction works at design points, but vibration increases at operational points outside design conditions
Solution Approach 1:
By changing the speed ratio to a non-integer value, the invention creates a vibration reduction solution that is effective across all operational conditions rather than just at nominal design points. The non-integer speed ratio prevents resonance conditions universally, making the system adaptable to varying operational requirements without requiring redesign
Data Source
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AI summary
Embodiments of the invention are shown in the figures, where a method for manufacturing a gearbox (30; 130; 230), the method comprising: providing (S101) a predefined interval (I) around an integer (Ri); providing (S102) a gearbox setup; determining (S103) a speed ratio (R) of at least two components (28, 32, 34, 38, O) of the gearbox setup; comparing (S104) the speed ratio (R) with the predefined interval (I) around the integer (Ri); and manufacturing (S105) a gearbox (30; 130; 230) in accordance with the gearbox setup in dependence on the comparison.