Hovering Aircraft Planetary Transmission With Tiltable Interface
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Solution Overview
Problem
Mechanical transmissions in aircraft, such as helicopters and convertiplanes, face issues with asymmetric stiffness due to geometric misalignment, leading to differential deformations and reduced operating life and performance of planetary gears.
Innovation Solution
The design incorporates a tiltable interface between the satellite carrier and the drive shaft, allowing for elastic deformation and maintaining axis alignment, which compensates for torque transmission misalignment and reduces asymmetrical stiffness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a mechanical transmission with planetary gears is used to transmit torque from the turbine to the rotor, then adequate torque transmission is achieved, but asymmetric stiffness and geometric misalignment cause differential deformations that reduce operating life and performance
Solution Approach 1:
The satellite carrier is designed with dynamic adaptability through tiltable satellites that can adjust their orientation relative to the drive shaft axis. This allows the transmission system to dynamically compensate for misalignment and deformation under varying torque conditions, maintaining reliable operation while transmitting adequate torque to the rotor.
Solution Approach 2:
The invention changes the geometric parameters of the satellite carrier and satellite arrangement to achieve symmetric stiffness. By carefully selecting the number, position, and orientation of satellites, the system compensates for elastic deformations and maintains proper meshing conditions, thereby improving the operating life of planetary gears under high torque transmission.
2Manufacturing precision
If the satellite carrier and drive shaft are rigidly connected to maintain axis alignment, then geometric precision is improved, but the system cannot accommodate elastic deformations under torque, leading to increased contact pressure variability
Solution Approach 1:
The satellite carrier incorporates flexible elements that allow controlled deformation under torque while maintaining proper gear meshing. This flexibility accommodates elastic deformations without creating excessive contact pressures, and the tiltable satellite mechanism ensures that axis alignment is maintained within acceptable tolerances despite the flexible connection.
Solution Approach 2:
The tiltable satellite acts as an intermediary element between the satellite carrier and the drive shaft. It mediates the connection by allowing relative motion and adjustment, absorbing the effects of elastic deformation while maintaining proper alignment and reducing contact pressure variability through its ability to adapt to changing geometric conditions.
3Device complexity
If asymmetric satellite arrangement is used to fit the geometric constraints of the transmission, then device complexity is reduced, but asymmetric stiffness causes differential deformations that harm planetary gear performance
Solution Approach 1:
The invention strategically uses asymmetry in the satellite arrangement to achieve symmetric stiffness characteristics. By carefully positioning satellites with different orientations and angles, the system compensates for the asymmetric geometric constraints of the transmission housing, creating a balanced stiffness distribution that eliminates differential deformations while maintaining a relatively simple structure.
Solution Approach 2:
Different satellites are given different local qualities in terms of their orientation, position, and tilt angles. This localized variation in satellite characteristics allows the system to compensate for asymmetric constraints in different regions of the transmission, achieving overall symmetric stiffness and reliable planetary gear performance without requiring a completely symmetric or complex structure.
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 solution enhances the operational life and performance of planetary gears by maintaining axis alignment and reducing contact pressure variability, resulting in a more efficient and durable transmission system.
Implementation Method 1
allowing for elastic deformation and maintaining axis alignment
Data Source
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AI summary
An aircraft (1) capable of hovering is described, comprising a motor member (10); a rotor (5) connected to the motor member (10); a transmission shaft (11) rotatable around a first axis (B) and adapted to drive the rotor (5); and a transmission (9) interposed between the motor member (10) and the rotor (5) and comprising a planetary gear (21AXES) formed by a sun (7) rotatable around a second axis (D); a crown (17) that is angularly fixed; and two satellites (19) meshing, each, with the crown (17) and the sun (15), and rotatable around respective third axes (I), which are, in turn, rotatable around the second axis (D); and a satellite carrier (30) rotatable around the second axis (D) and comprising two first pins (32) with respect to which the satellites (19) are rotatable around the respective third axes (E); the transmission (9) comprises an interface (50), angularly integral with the satellite carrier (30) around the second axis (D) and said transmission shaft (11) around the first axis (B); the interface (50) being coupled to said satellite carriers (30) and the transmission shaft (11) so as to allow an angular misalignment between the second axis (B) and a portion (55) of the interface (50).