Glow Plug Voltage Switching for Stable Gas Turbine Ignition
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Solution Overview
Problem
Glow plugs in gas turbine engines face reliability issues due to temperature fluctuations and high costs, particularly in extreme cold or hot conditions, and existing solutions do not adequately address these challenges.
Innovation Solution
A glow plug system with a controller that adjusts voltage levels to maintain the glow plug temperature within a specific range by monitoring current, using a series resistance model with temperature-dependent and independent components, and toggling between two voltage levels to control temperature oscillations, thereby ensuring reliable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the glow plug operates in extreme cold or hot conditions, then the engine can be ignited, but the reliability of the glow plug decreases
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the voltage applied to the glow plug based on temperature conditions. The controller monitors the glow plug temperature and switches between different voltage levels (e.g., first voltage level for heating, second voltage level for cooling) to maintain the glow plug temperature within an optimal range, thereby improving reliability under extreme temperature conditions.
Solution Approach 2:
The patent implements feedback control by continuously monitoring the glow plug temperature (or a parameter correlated with temperature) and adjusting the applied voltage accordingly. The controller uses the monitored temperature information to determine when to switch between different voltage levels, creating a closed-loop control system that maintains temperature stability and improves glow plug reliability.
2Reliability
If the glow plug temperature is increased to ensure ignition, then ignition reliability improves, but thermal stresses and risk of overheating increase
Solution Approach 1:
The patent applies periodic action by using pulsed or cyclic voltage application to the glow plug. Instead of continuous high voltage that would cause excessive thermal stress, the controller periodically switches between different voltage levels, allowing the glow plug to heat up for ignition while also providing cooling periods that reduce thermal stress accumulation.
Solution Approach 2:
The patent changes the voltage parameter dynamically based on the glow plug temperature state. By switching between a first voltage level (higher) for heating and a second voltage level (lower) for cooling, the system achieves reliable ignition while preventing excessive temperature rise and associated thermal stresses.
3Reliability
If advanced temperature control systems are implemented, then glow plug reliability improves, but device complexity and cost increase
Solution Approach 1:
The patent applies self-service by enabling the glow plug system to automatically regulate its own temperature without requiring complex external control systems. The glow plug's own electrical characteristics (such as resistance changes with temperature) are utilized as feedback signals, allowing the system to self-adjust the applied voltage and maintain optimal temperature, thereby reducing overall system complexity.
Solution Approach 2:
The patent makes the glow plug serve multiple functions: it not only provides heating for ignition but also acts as its own temperature sensor through its electrical characteristics. This multi-functionality reduces the need for separate sensing and control components, thereby reducing device complexity while maintaining improved reliability.
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 system effectively maintains the glow plug temperature within optimal limits, enhancing reliability and reducing thermal stresses while minimizing electromagnetic interference and operational complexity.
Implementation Method 1
Glow plugs are commonly used to ignite a mixture of air and fuel in a combustor of gas turbine engines
Implementation Method 2
A glow plug system with a controller that adjusts voltage levels to maintain the glow plug temperature within a specific range by monitoring current, using a series resistance model with temperature-dependent and independent components
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A method (600) for operating a glow plug includes controlling (602) a temperature of the glow plug by switching between applying a voltage VH (608) and applying a voltage VN < VH (606) to the glow plug. Applying the voltage VH (608) and applying the voltage VN (606) causes a glow plug current to oscillate about a glow plug current threshold. The glow plug current threshold is associated with one of the voltage VH and the voltage VN. The method (600) includes monitoring (604) the glow plug current at the one of the voltage VH and the voltage VN.