Aircraft Generator Gear Layout for Emergency Cutoff Protection
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Solution Overview
Problem
Existing electric power generating apparatuses for aircraft face challenges in managing large rotational frequency fluctuations without increasing in size, and ensuring protection during abnormalities, as large speed change ranges require larger continuously variable transmissions and manual transmissions upstream do not effectively cut off power transmission during emergencies.
Innovation Solution
An electric power generating apparatus configuration that includes a manual transmission downstream of the emergency cut-off device, with a housing accommodating both the manual transmission and electric power generator, allowing for compact design and effective protection during abnormalities by cutting off power transmission to all components when an emergency occurs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
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 adjusted to an appropriate range, but the power transmission from the engine to the manual transmission continues even when the emergency cut-off device cuts off power transmission to the electric power generating apparatus
Solution Approach 1:
The manual transmission is positioned downstream of the emergency cut-off device instead of upstream, inverting the conventional arrangement. This ensures that when the emergency cut-off device activates, power transmission to both the electric power generating apparatus and the manual transmission is simultaneously cut off, eliminating the harmful continuous power transmission while maintaining the manual transmission's speed adjustment function during normal operation
2Adaptability or versatility
If the speed change range of the continuously variable transmission is made large to handle large rotational frequency fluctuations, then the rotational frequency can be adjusted appropriately, but the continuously variable transmission needs to be increased in diameter and the entire apparatus increases in size
Solution Approach 1:
The speed change function is segmented into two parts: the continuously variable transmission handles continuous speed adjustment within a limited range, while the manual transmission with multiple gear stages handles large-range speed ratio changes. This segmentation allows the continuously variable transmission to remain compact while still achieving overall large speed change capability through coordination with the manual transmission
Data Source
AI summary
An electric power generating apparatus for use in an aircraft is an electric power generating apparatus connected through an emergency cut-off device to a gear box such that the gear box can transmit power to the electric power generating apparatus, the gear box being configured to decrease speed of rotational power of an aircraft engine. The electric power generating apparatus includes: a manual transmission configured to change the speed of the rotational power transmitted from the emergency cut-off device 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.