Turbomachine Starter Control for Ignition Window Management
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Solution Overview
Problem
Current turbomachine starting systems face challenges in reliably starting aircraft turbine engines due to variable starting torque and ignition window conditions, leading to inefficient ignition and potential engine failure, particularly at low temperatures and high altitudes, and existing solutions are cumbersome and costly.
Innovation Solution
A turbomachine start-up system comprising a DC-DC converter and electronic control computer that regulates the starting torque and speed within a preferential ignition window, using sensors to control switches and manage the DC-DC converter, allowing for efficient and robust ignition by maintaining the gas generator within the ignition window until successful ignition is confirmed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a traditional DC starter is used to accelerate the compressor shaft, then the starting torque is high enough to drive the shaft in rotation, but the speed passes through the ignition window too quickly, causing failed ignition
Solution Approach 1:
The patent applies dynamics by making the starting torque variable rather than constant. The control unit dynamically adjusts the electrical command to the starter motor based on real-time feedback from the rotation speed sensor, allowing the system to adapt the acceleration profile to maintain the shaft within the ignition window for sufficient time, thereby resolving the contradiction between achieving sufficient speed and ensuring reliable ignition.
Solution Approach 2:
The patent implements feedback control by using a rotation speed sensor to continuously monitor the compressor shaft speed and feeding this information back to the control unit. The control unit processes this feedback and adjusts the starter motor command accordingly, enabling closed-loop control that maintains the shaft speed within the optimal ignition window, thus improving ignition reliability while achieving proper acceleration.
2Power
If the starting current is limited by using a starting resistor, then the armature current is controlled, but the starting torque becomes insufficient to accelerate the shaft reliably
Solution Approach 1:
The patent applies dynamics by transitioning from a static resistor-based current limitation to a dynamic control system. The control unit dynamically adjusts the electrical command to the starter motor based on real-time feedback from the rotation speed sensor, allowing the system to adapt the acceleration profile to maintain the shaft within the ignition window for sufficient time, thereby resolving the contradiction between achieving sufficient speed and ensuring reliable ignition.
Solution Approach 2:
The patent replaces the passive mechanical/electrical resistor-based current limitation system with an active electronic control system. Instead of using a starting resistor to passively limit current, the system uses a control unit with feedback to actively regulate the electrical command to the starter motor, enabling precise control of both current and torque to achieve reliable starting without the drawbacks of resistor-based limitation.
3Loss of time
If the gas generator accelerates too quickly through the ignition window, then the starting time is reduced, but the ignition fails due to insufficient time for fuel/air mixture preparation
Solution Approach 1:
The patent applies dynamics by making the acceleration profile adaptive rather than fixed. The control unit dynamically adjusts the electrical command to the starter motor based on real-time feedback from the rotation speed sensor, allowing the system to slow down within the ignition window to provide sufficient time for fuel/air mixture preparation while still achieving timely acceleration overall, thus resolving the contradiction between starting time and ignition reliability.
Solution Approach 2:
The patent implements feedback control by using a rotation speed sensor to continuously monitor the compressor shaft speed and feeding this information back to the control unit. The control unit processes this feedback and adjusts the starter motor command accordingly, enabling closed-loop control that maintains the shaft speed within the optimal ignition window for the required duration, ensuring proper fuel/air mixture preparation while managing overall starting time.
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 reduces the number of failed starts, improves starting robustness across varying conditions, minimizes battery size and weight, and reduces the complexity and cost of the electrical power supply, while maintaining efficient engine acceleration post-ignition.
Implementation Method 1
a DC-DC converter (130) connected in series with a first switch (132)
Implementation Method 2
a direct current starter (120)... regulating the starting torque and speed
Implementation Method 3
the combustion chamber (165) of the turbomachine is ignited
Data Source
Figure 1~3
Figure 4~6
Figure 7~9
AI summary
The starting system comprises a battery of accumulator cells (110), a DC starter (120), an electronic regulator computer (142), a transmission relay (162), starting accessories (168) and a gas generator (160) itself comprising a compressor (164), a combustion chamber (165) and a high-pressure turbine (166) as well as a free turbine (167). First and second circuits are mounted in parallel and interposed between the battery of accumulator cells (110) and the DC starter (120). The first circuit comprises a DC/DC converter (130) mounted in series with a first circuit breaker (132) and the second circuit comprises a second circuit breaker (133). Furthermore, the system comprises at least one sensor (163) sensing the rotational speed of the compressor (164), a sensor (151) sensing the temperature at the inlet of the free turbine (167), and a control circuit (141) controlling the first and second circuit breakers (132, 133) on the basis of the information supplied by the sensor (163) sensing the rotational speed of the compressor (164) and by the sensor (151) sensing the temperature at the inlet to the free turbine (167).