Gaseous Fuel Engine Start-Up with Pilot Ignition Health Checks
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Solution Overview
Problem
Starting gaseous fuel internal combustion engines, such as Otto engines and dual fuel engines, is challenging due to difficulties in controlling ignition systems and gas admission valves during the start-up phase, requiring adaptations to ensure smooth engine operation and proper functionality of these components.
Innovation Solution
A method involving rotating the engine to reach a first speed threshold, followed by initiating pilot fuel combustion and performing ignition and gas admission valve health checks to ensure functionality, then increasing gaseous fuel pressure to accelerate the engine, allowing for efficient start-up and operation by adjusting the number of fired cylinders and air/fuel ratio controls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the engine is started using conventional start procedures, then the engine can be rotated and pilot fuel combustion can be initiated, but the functionality of ignition devices and gas admission valves cannot be reliably determined during start-up
Solution Approach 1:
The patent applies preliminary action by performing ignition health checks and gas admission valve health checks during the start-up phase, before the engine reaches normal operating conditions. The control system activates pilot fuel injection and monitors combustion parameters to verify ignition device functionality early in the start sequence, and subsequently tests gas admission valves by attempting to open them during a predetermined time period. This preliminary verification ensures component reliability before full engine operation begins.
2Reliability
If gas admission valves are tested during engine operation, then valve functionality can be determined, but the engine speed and load conditions become difficult to control
Solution Approach 1:
The patent segments the start-up process into distinct phases with specific control objectives. The gas admission valve health check is performed as a separate, isolated test phase after pilot fuel combustion has been established but before the engine accelerates to full speed. During this test phase, the control system attempts to open gas admission valves for a predetermined time period while monitoring engine response, independent of the speed governor. This segmentation allows valve functionality testing without the complicating factors of full engine load and speed control requirements.
3Ease of operation
If the speed governor controls the gas admission valve opening, then engine speed is regulated, but the gas admission valve health test cannot be performed independently
Solution Approach 1:
The patent introduces an intermediary test mode where the control system temporarily bypasses the speed governor's control of gas admission valves to perform health checks. During this intermediary phase, the control system directly attempts to open gas admission valves for a predetermined time period independent of speed governor signals, while still monitoring engine speed and load parameters. This intermediary approach allows the system to detect valve operability without permanently disrupting the normal speed governor control mechanism.
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 method enables reliable and efficient starting of gaseous fuel internal combustion engines by ensuring the proper functioning of ignition systems and gas admission valves, optimizing engine speed and power distribution, and transitioning to normal operation with improved start-up behavior.
Implementation Method 1
starting a supply of pilot fuel to the plurality of cylinders by a pilot fuel system after reaching the first threshold to initiate combustion of the pilot fuel and intake air
Implementation Method 2
the injected pilot fuel / air mixture being compressed in the cylinder and combusted
Data Source
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AI summary
A method for starting a gaseous fuel internal combustion engine (10) is disclosed. According to the disclosed method, the engine is rotated using a start device until a first speed threshold is reached. After reaching the first speed threshold, pilot fuel is supplied to a plurality of cylinders (26A-26D) of the engine to combust the same. After performing an ignition health check, gaseous fuel is supplied to all or a relatively large number of cylinders (26A-26D) to start accelerating the engine up to a second speed threshold.