Aircraft Engine APU Mode Actuation and Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing systems for aircraft auxiliary power units (APUs) increase weight and complexity, as they require a dedicated APU to provide power and drive accessories, which is not necessary when the aircraft is on the ground.
Innovation Solution
A system comprising a first and second engine, with an actuator and processing unit that adjusts engine speed to zero torque when on the ground, allowing the APU engine to disengage from the gearbox and only drive accessories, eliminating the need for a dedicated APU by using a dual-engine configuration with a clutch and APU actuator system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dedicated APU is used to provide back-up power and drive accessories, then reliability is improved, but weight and device complexity increase
Solution Approach 1:
The patent makes one of the main engines capable of performing both its primary propulsion function and the auxiliary power function traditionally reserved for a dedicated APU. The engine can operate in a second operational mode where it drives only the accessory drive train while disengaged from the gearbox, providing electrical power and pneumatic air for aircraft systems during ground operations or in-flight emergencies.
Solution Approach 2:
The patent combines the functions of the main engine and the dedicated APU into a single integrated system. The first engine is equipped with an actuator that enables it to selectively engage or disengage from the gearbox, allowing it to serve dual purposes: driving the propulsor through the gearbox and driving accessories independently when operating in APU mode.
2Power
If a dedicated APU is installed to provide independent power drive, then power availability is improved, but aircraft weight increases
Solution Approach 1:
The patent enables one of the existing main engines to perform the auxiliary power function traditionally requiring a separate APU installation. By configuring the first engine to operate in two modes - a first mode for driving the propulsor and a second mode for driving only accessories - the system eliminates the need for additional weight of a dedicated APU while maintaining independent power drive capability.
Solution Approach 2:
The patent extracts the auxiliary power function from the dedicated APU and transfers it to one of the main engines. This allows the removal of the separate APU system and its associated weight, while the engine's accessory drive train continues to provide the necessary independent power for aircraft systems.
3Device complexity
If the engine operates in APU mode to drive only accessories, then device complexity is reduced, but torque management and speed synchronization become more difficult
Solution Approach 1:
The patent employs a processing unit that receives feedback regarding the present position of the actuator, the governing state and speed of the first and second engines. Based on this feedback, the processing unit outputs control signals to adjust engine speed and manage torque, ensuring smooth transitions between operational modes and preventing adverse effects during mode changes.
Solution Approach 2:
The patent implements dynamic control of the engine's operational mode through an actuator that can move between a first position (engaging the gearbox) and a second position (disengaged from the gearbox). The processing unit dynamically adjusts engine parameters such as speed and torque based on real-time operating conditions, enabling seamless transitions between propulsion mode and APU mode.
Data Source
AI summary
At least a selected one of a first and second engine are connected to a drive train for driving an aircraft accessory. A gearbox is connected to a primer mover propulsor and an actuator operatively associated with the selected engine is moveable between a position in which the selected engine drivingly engages the gearbox for driving the propulsor and a position in which the selected engine disengages from the gearbox. A position signal, a status signal, and a request signal respectively indicative of a present position of the actuator, a governing state and present speed of each engine, and a request for movement of the actuator from the present position to the other position are received. If the selected engine's speed differs from a predetermined threshold, a control signal is output for causing the engine's speed to be adjusted towards the threshold. A control signal indicating that movement of the actuator is permitted is then output.