Multi-Fuel Engine Jet Block and Cutoff Valves for Stable Switching
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Solution Overview
Problem
Dual fuel generators face issues with overly rich air-fuel ratios and unstable operating conditions when switching between liquid and gaseous fuels due to the simultaneous delivery of both fuels, leading to hard starting and performance issues.
Innovation Solution
A multi-fuel engine system with a liquid cutoff solenoid, gaseous cutoff solenoids, and a switch that allows on-the-fly fuel source switching, along with a jet block to meter gaseous fuels, preventing simultaneous fuel delivery and ensuring precise fuel control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a dual fuel engine uses a common carburetor with a fuel bowl for both liquid and gaseous fuel delivery, then the engine can operate on either fuel source, but during cross-over switching the engine experiences overly rich air-fuel ratio causing hard starting and unstable operation
Solution Approach 1:
The fuel delivery system is segmented into separate liquid fuel delivery components and gaseous fuel delivery components, each with independent control. The liquid fuel system includes a liquid fuel valve and carburetor, while the gaseous fuel system includes a gaseous fuel valve and separate fuel delivery path. This segmentation allows independent control of each fuel type, preventing the overly rich condition that occurs when both fuels are delivered simultaneously through a shared carburetor.
Solution Approach 2:
The system performs preliminary action by closing the liquid fuel valve before introducing gaseous fuel, and closing the gaseous fuel valve before introducing liquid fuel. This sequential control prevents fuel overlap during transitions. The control system anticipates the need to switch fuels and prepares the appropriate fuel delivery path in advance, ensuring smooth transitions without overly rich air-fuel ratios.
2Adaptability or versatility
If the engine simultaneously receives fuel from both liquid fuel line and gaseous fuel line during fuel source transition, then fuel source switching is enabled, but the engine runs on both fuels causing overly rich fuel mixture and unstable operating conditions
Solution Approach 1:
The system dynamically controls the fuel delivery paths using electrically actuated valves that can quickly open or close to direct fuel flow. The control system dynamically switches between liquid and gaseous fuel delivery configurations based on the selected fuel source. This dynamic control ensures that only the selected fuel is delivered to the engine at any given time, preventing simultaneous delivery and the resulting overly rich conditions.
Solution Approach 2:
Electrically actuated valves serve as intermediaries between the fuel sources and the engine. These valves control the flow paths, allowing only the selected fuel type to reach the engine. The intermediary valves prevent direct simultaneous access of both liquid and gaseous fuels to the combustion chamber, ensuring stable operation during and after fuel source transitions.
3Ease of manufacture
If a carburetor with a fuel bowl is used for liquid fuel delivery, then liquid fuel can be stored and delivered to the engine, but the fuel bowl continues to supply liquid fuel even after the liquid fuel source is cut-off, causing rich air-fuel ratio during switching
Solution Approach 1:
The invention extracts the fuel bowl and its associated float valve mechanism from the fuel delivery system. Instead of using a carburetor with an internal fuel storage bowl that cannot be quickly emptied, the system uses an external liquid fuel valve that can be electrically actuated to immediately stop fuel flow. This extraction eliminates the problem of residual fuel in the bowl continuing to deliver liquid fuel after the fuel source should be cut off.
Solution Approach 2:
The mechanical float valve system inside the carburetor bowl is replaced with an electrically actuated liquid fuel valve. This substitution allows for rapid and precise control of fuel flow termination through electrical signals rather than mechanical float movement. The electric valve can close immediately when signaled, ensuring accurate fuel switching without the delay inherent in mechanical bowl-based systems.
Data Source
AI summary
A multi-fuel engine includes an engine operable on a liquid fuel and first and second gaseous fuels. The multi-fuel engine also includes a liquid cutoff solenoid selectively operable between open and closed positions to allow and inhibit a flow of the liquid fuel to the engine and at least one gaseous cutoff valve selectively operable between open and closed positions to allow and inhibit a flow of the first and second gaseous fuels to the engine. A jet block couples the first gaseous fuel source and the second gaseous fuel source to a carburetor connected to an intake of the engine, with the jet block being located downstream from the at least one gaseous cutoff valve. The jet block includes a first gaseous fuel jet to meter the first gaseous fuel to the carburetor and a second gaseous fuel jet to meter the second gaseous fuel to the carburetor.