Aircraft Generator Transmission Using Planetary Speed Change
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electric power generating apparatuses for aircraft face challenges in managing large rotational frequency fluctuations without increasing the size of the apparatus, as widening the speed change range of continuously variable transmissions requires larger diameters, and adding a manual transmission to mitigate this issue results in a larger overall size.
Innovation Solution
Incorporating a compact two-stage manual transmission with a planetary gear mechanism, one-way clutch, and brake, allowing for speed changes while maintaining a compact design by switching the brake's operating state to achieve equal speed and speed increase, and integrating this with a continuously variable transmission and electric power generator to reduce overall size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the speed change range of a continuously variable transmission is made large to handle large rotational frequency fluctuations, then the rotational frequency can be adjusted to an appropriate range, but the continuously variable transmission needs to be increased in diameter and the entire apparatus increases in size
Solution Approach 1:
The transmission system is divided into two functional segments: a continuously variable transmission (CVT) for continuous speed adjustment and a manual transmission with planetary gear mechanism for discrete speed ratio changes. This segmentation allows the CVT to operate within a limited range while the manual transmission provides additional speed ratios, achieving wide overall adaptability without requiring the CVT to be oversized.
Solution Approach 2:
The manual transmission uses a dynamically controllable planetary gear mechanism with a one-way clutch and brake that can switch between different operating states (engaged/disengaged). This dynamic control enables the system to change speed ratios based on rotational frequency requirements, providing adaptability without permanently increasing the apparatus size.
2Adaptability or versatility
If a manual transmission is provided upstream of the electric power generating apparatus to narrow the rotational frequency fluctuation range, then the rotational frequency can be controlled, but the entire apparatus increases in size
Solution Approach 1:
The manual transmission is merged with the continuously variable transmission to form an integrated power transmission system. The manual transmission's planetary gear mechanism is positioned upstream of the CVT, and both components work together in a coordinated manner. This merging eliminates the need for separate standalone transmissions, reducing overall apparatus size while maintaining rotational frequency control capability.
Solution Approach 2:
The manual transmission components, particularly the planetary gear mechanism, are arranged in a nested configuration where the sun gear, planetary gears, and ring gear are concentrically positioned. This nested arrangement minimizes the radial space required, allowing the manual transmission to be compact and not increase the overall apparatus size significantly.
3Speed
If the brake is operated to fix the ring gear in the planetary gear mechanism, then the rotational power is increased in speed, but the system requires additional control mechanisms
Solution Approach 1:
The one-way clutch automatically engages or disengages based on the rotational direction and speed relationships between the input and output shafts, without requiring active control. When the brake fixes the ring gear, the one-way clutch allows the planetary gears to rotate in the forward direction while preventing reverse rotation. This self-service mechanism simplifies control by eliminating the need for additional actuators or control systems.
4Volume of moving object
If the one-way clutch is arranged at a radially inner side of the ring gear, then the size of the manual transmission is reduced in the axial direction, but the space for component arrangement becomes more constrained
Solution Approach 1:
The one-way clutch is positioned in the radial direction (inner side of the ring gear) rather than extending axially, effectively utilizing the radial space within the planetary gear mechanism. This dimensional repositioning reduces the axial length of the manual transmission while the component arrangement complexity is managed through the inherent concentric layout of the planetary gear system, where all components naturally align along the same axis.
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 solution enables a compact electric power generating apparatus that effectively manages rotational frequency fluctuations, reduces the size of the manual transmission, and minimizes the occupied space upstream of the continuously variable transmission, resulting in a more compact and efficient power transmission system.
Implementation Method 1
a one-way clutch which is sandwiched between the input shaft and the output shaft and by which the rotational power of the input shaft is transmitted to the output shaft
Implementation Method 2
a brake connected to a ring gear of the planetary gear mechanism. When the brake is operated, the ring gear is fixed
Implementation Method 3
The manual transmission includes a planetary gear mechanism, an input shaft connected to a carrier holding a planetary gear of the planetary gear mechanism
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
An electric power generating apparatus for use in an aircraft includes: a manual transmission configured to change speed of rotational power of an aircraft engine and including a plurality of gear stages; and an electric power generator to which the rotational power which has been changed in speed by the manual transmission is transmitted. The manual transmission includes: a planetary gear mechanism; an input shaft connected to a carrier holding a planetary gear of the planetary gear mechanism; an output shaft connected to a sun gear of the planetary gear mechanism; a one-way clutch which is sandwiched between the input shaft and the output shaft and by which the rotational power of the input shaft is transmitted to the output shaft; and a brake connected to a ring gear of the planetary gear mechanism.