APU Generator Constant Speed Drive via Differential Gearbox
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Solution Overview
Problem
Existing APU-generator systems face challenges in maintaining constant rotational speed and frequency of alternating current, leading to inefficient fuel usage due to high throttle settings during varying electrical loads, which affects the mechanical load on the auxiliary power unit.
Innovation Solution
An integrated APU-generator constant speed drive system that includes a gearbox with a variable speed input from a variable frequency rotational output and a constant speed output, utilizing a differential and hydraulic output controller to regulate the speed of the gearbox, ensuring a constant angular velocity is maintained despite varying loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the APU operates at a constant high throttle setting to maintain constant rotational speed and frequency, then the frequency stability of alternating current is improved, but fuel consumption increases
Solution Approach 1:
The system dynamically adjusts the APU rotational speed using a variable speed gearbox with differential mechanism and hydraulic controller, allowing the APU to operate at varying speeds while the generator maintains constant speed output, resolving the contradiction between frequency stability and fuel consumption
Solution Approach 2:
A variable speed gearbox acts as an intermediary between the APU and generator, decoupling their speed relationships. The gearbox with differential mechanism and hydraulic controller mediates the speed conversion, allowing independent optimization of APU fuel efficiency and generator frequency stability
2Use of energy by moving object
If the APU throttle setting is varied to optimize fuel efficiency during decreased electrical load, then fuel consumption is reduced, but the frequency of alternating current varies
Solution Approach 1:
The system allows dynamic throttle adjustment of the APU while using a variable speed gearbox with differential mechanism to dynamically adjust the gear ratio, maintaining constant generator speed and frequency despite varying APU throttle settings
Solution Approach 2:
The system changes the operational parameters by allowing APU speed to vary while using the hydraulic controller and differential mechanism to maintain constant generator speed, enabling fuel efficiency optimization without sacrificing frequency stability
3Use of energy by moving object
If a constant speed drive system is implemented to allow APU throttle variation, then fuel efficiency improves, but device complexity increases
Solution Approach 1:
A variable speed gearbox with differential mechanism serves as an intermediary that handles the complexity of speed conversion and control, allowing the APU to operate efficiently at varying throttle settings while the generator maintains constant speed through the mediating action of the gearbox and hydraulic controller
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 system maintains a constant frequency of alternating current generated by the generator, reducing fuel expenditure by allowing the APU to operate efficiently across different electrical loads without varying the throttle setting, thus optimizing energy use.
Implementation Method 1
driving, by the variable frequency rotational output, a differential, and rotating by the differential, a constant speed gearbox output
Implementation Method 2
a hydraulic output controller control shaft. The method may also include sensing the speed of the constant speed gearbox output by a speed sensor
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
An integrated APU-generator constant speed drive system (2) having various features is disclosed. The system (2) may have a gearbox (20) having a differential (23) with a constant speed gearbox output (24) and a hydraulic output controller control shaft (51). The system (2) may have a hydraulic output speed controller (25) that adjusts the angular velocity of the hydraulic output controller control shaft (51) of the differential (23). In response, the differential (23) may adjust the angular velocity of the constant speed gearbox output (24). In this manner, the angular velocity of the constant speed gearbox output (24) may be maintained at a substantially constant angular velocity. A generator (30) may be driven by the constant speed gearbox output (24). By maintaining the constant speed gearbox output (24) at a substantially constant angular velocity, an alternating current generated by the generator (30) may be maintained at a substantially constant frequency.