Fuel Injector Valve Assembly Combustion Gas Backflow Isolation
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Solution Overview
Problem
Fuel injectors for gaseous fuel injection face challenges due to extreme temperature and pressure variations, leading to reduced robustness and lifespan as combustion gases can flow back into the injector, causing rapid temperature changes and applied forces on components.
Innovation Solution
A valve assembly is introduced in the fuel injector, comprising a first valve to control gaseous fuel flow and a second valve to manage combustion gas flow back into the injector, with the second valve being biased to a closed position and opened by gaseous fuel flow through the first valve, reducing exposure to temperature changes and improving robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single valve design is used for both fuel injection and combustion gas isolation, then device complexity is reduced, but reliability deteriorates due to inability to independently control fuel flow and combustion gas backflow
Solution Approach 1:
The patent divides the valve assembly into two separate valves: a first valve (fuel injection valve) positioned at the inlet end to control gaseous fuel flow, and a second valve (combustion gas isolation valve) positioned at the outlet end to prevent combustion gas backflow. This segmentation allows independent control of fuel injection and combustion gas isolation functions, improving reliability by addressing the specific problem of combustion gas exposure to injector components.
2Duration of action of moving object
If the second valve is positioned close to the first valve, then device complexity is reduced, but temperature exposure increases causing rapid temperature changes and reduced operating life
Solution Approach 1:
The patent positions the second valve at the outlet end of the fuel passage, spatially separated from the first valve at the inlet end. This dimensional separation along the fuel passage axis creates a protective barrier that isolates upstream components from combustion gas exposure, reducing thermal stress and extending operating life.
3Reliability
If the second valve remains closed during fuel injection, then temperature exposure is reduced improving operating life, but fuel flow control precision deteriorates
Solution Approach 1:
The second valve acts as an intermediary barrier positioned at the outlet end of the fuel passage. It selectively opens to allow combustion gases to escape while remaining closed during normal fuel injection to prevent backflow. This intermediary positioning protects upstream components from thermal exposure without interfering with precise fuel flow control by the first valve.
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 valve assembly effectively controls both gaseous fuel and combustion gas flows, enhancing the robustness and operating life of the fuel injector by mitigating the impact of temperature and pressure variations.
Implementation Method 1
The second valve is biased to a closed position
Implementation Method 2
the second valve is moved from the closed position to an open position by the gaseous fuel flow through the opened first valve
Data Source
AI summary
A fuel injector for gaseous fuel is provided. The fuel injector includes a valve assembly with a first valve and a second valve. The first valve is actively controlled to permit and prohibit gaseous fuel flow through the first injector. The second valve is spaced from the first valve and passively controlled to open in response to the gaseous fuel flow though the first valve, and to close when the gaseous fuel flow is terminated by closing the first valve.