Epicyclic Gearbox Layout for Multi-Engine Aircraft Speed Reduction
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Solution Overview
Problem
Current reduction gearboxes in turboprop aircraft engines are inefficient in reducing rotational speed, leading to suboptimal performance and increased complexity, weight, and maintenance costs due to the high number of moving parts and lubrication requirements.
Innovation Solution
The implementation of a planetary gearbox with a unique configuration where the rotation of the ring gear and carrier in each epicyclic gearbox is blocked, and the gears are designed with specific tooth shapes and markings to facilitate efficient speed reduction, reducing the number of moving parts and optimizing torque distribution, thereby simplifying the gearbox design and reducing weight and maintenance needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a conventional reduction gearbox is used to reduce the rotational speed of the turbine, then the propeller can be driven at the appropriate speed, but the gearbox becomes complex with many moving parts requiring extensive lubrication
Solution Approach 1:
The patent inverts the conventional planetary gearbox design by blocking the ring gear instead of the carrier. This inversion simplifies the design by eliminating the need for a complex carrier structure with multiple planet gears, reducing the number of moving parts and lubrication requirements while maintaining effective speed reduction from the turbine to the propeller
Solution Approach 2:
The patent extracts and eliminates unnecessary components from the conventional planetary gearbox design. By blocking the ring gear and using a simplified carrier structure, the design removes redundant moving parts that would require lubrication, thereby reducing gearbox complexity while preserving the speed reduction function
2Speed
If a conventional reduction gearbox with many moving parts is used, then speed reduction is achieved, but the weight of the gearbox increases
Solution Approach 1:
By inverting the conventional design to block the ring gear rather than the carrier, the patent eliminates the need for a heavy, complex carrier structure with multiple planet gears. This inversion reduces the overall weight of the gearbox while maintaining the necessary speed reduction capability for driving the propeller
Solution Approach 2:
The patent removes unnecessary moving parts from the conventional planetary gearbox design, thereby reducing the overall weight. The simplified structure with fewer components directly reduces gearbox weight while preserving the essential function of reducing turbine rotational speed to appropriate propeller speed
3Speed
If a conventional reduction gearbox is used, then the turbine's high rotational speed is reduced, but the number of moving parts increases leading to higher maintenance costs
Solution Approach 1:
The patent inverts the conventional planetary gearbox design by blocking the ring gear instead of the carrier. This design choice reduces the number of moving parts that require maintenance, such as planet gears and their bearings, thereby lowering maintenance costs and improving ease of repair while maintaining effective speed reduction
Solution Approach 2:
The patent extracts and eliminates unnecessary moving parts from the conventional gearbox design. By removing redundant components that would require regular maintenance, the simplified design reduces maintenance requirements and costs while preserving the essential speed reduction function
Data Source
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AI summary
An aircraft (1) includes first and second engines (10, 10A, 10B), one or more aircraft rotors (12, 12P) associated with the first and second engines (10, 10A, 10B), a first epicyclic gearbox (20) having: a) an output operatively connected at least one of the one or more aircraft rotors (12, 12P), and b) an input defined by a sun gear (32) of the first epicyclic gearbox (20); and a second epicyclic gearbox (58) having: a) an output operatively connected to at least one of the one or more aircraft rotors (12, 12P), and b) an input defined by a sun gear (60) of the second epicyclic gearbox (58). Output of the first epicyclic gearbox (20) is defined by the carrier (40). Output of the second epicyclic gearbox (58) is defined by its ring gear (62). A multi-engine aircraft (1) and a method of operating a multi-engine aircraft (1) are also described.