Dual fuel method and system
First Claim
Patent Images
1. A method for operating a dual fuel system, comprising the steps of:
- pumping a first fuel to a fuel feeding device;
feeding the first fuel from the fuel feeding device to an engine;
operating the engine with the first fuel in a first fuel mode;
changing the mode of operation of the engine to operate on a second fuel by stopping the flow of the first fuel to the fuel feeding device;
waiting until the first fuel substantially empties from the fuel feeding device;
preventing the flow of the first fuel from the fuel feeding device to the engine;
thereafter opening a valve for feeding the second fuel;
passing the second fuel to the engine; and
operating the engine on the second fuel in a second fuel mode.
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Abstract
A special dual fuel method and system is provided to enhance vehicle performance and fuel consumption as well as to accommodate a smooth transition when operating the engine on different fuels, such as gasoline or liquified petroleum gas (LPG). When the engine is operated on a different fuel, a filtered oxygen (O2) signal is transmitted to an engine control unit (ECU) which can regulate operation of the gasoline shutoff valve and an LPG valve and responds to the filtered O2 signal and the type of fuel, i.e. mode of operation, selected for the dual fuel engine.
40 Citations
28 Claims
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1. A method for operating a dual fuel system, comprising the steps of:
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pumping a first fuel to a fuel feeding device;
feeding the first fuel from the fuel feeding device to an engine;
operating the engine with the first fuel in a first fuel mode;
changing the mode of operation of the engine to operate on a second fuel by stopping the flow of the first fuel to the fuel feeding device;
waiting until the first fuel substantially empties from the fuel feeding device;
preventing the flow of the first fuel from the fuel feeding device to the engine;
thereafteropening a valve for feeding the second fuel;
passing the second fuel to the engine; and
operating the engine on the second fuel in a second fuel mode. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method for operating a dual fuel system, comprising the steps of:
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pumping gasoline to a carburetor with a fuel pump;
feeding gasoline from the carburetor to an engine;
operating the engine on gasoline in a gasoline mode;
detecting and monitoring the oxygen content of exhaust gases emitted from the engine;
generating a signal based upon the detected oxygen content of the exhaust gases;
determining a mean or average value of the signal for a preselected period of time;
filtering the signal to produce a filtered signal corresponding to the means or average value of the signal, the filtering occurring in association with an engine control unit (ECU);
controlling operation of an LPG valve with the ECU;
changing the mode of operation of the engine from gasoline to liquified petroleum gas (LPG);
establishing a reference filtered signal when the mode of operation of the engine is changed from gasoline to LPG;
closing a gasoline valve to stop the flow of gasoline to the carburetor;
waiting until the gasoline substantially empties from a float bowl of the carburetor;
thereafteropening the LPG valve to access the liquified petroleum gas (LPG);
vaporizing the liquified petroleum gas (LPG);
feeding the vaporized LPG to the engine; and
operating the engine on vaporized LPG in the LPG mode. - View Dependent Claims (12, 13, 14, 15, 16, 18, 19, 20, 21, 22, 23, 25, 26, 27, 28)
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17. A method for operating a dual fuel system, comprising the steps of:
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pumping a first fuel to an electronic fuel injector (EFI) system comprising one or more electronic fuel injectors (EFI) with a fuel feeding device comprising a fuel line and a rail, and a fuel pump operatively associated with a gasoline tank;
injecting the first fuel from the EFI system to the engine;
operating the engine with the first fuel in a first fuel mode;
sensing and monitoring the oxygen content of exhaust gases emitted from the engine;
generating a signal based upon the sensed oxygen content of the exhaust gases;
determining a mean or average value of the signal for a preselected period of time;
filtering the signal to produce a filtered signal corresponding to the mean or average value of the signal, the filtering occurring in association with an engine control unit (ECU);
controlling operation of a second fuel valve with the ECU;
changing the mode of operation of the engine from the first fuel to the second fuel;
establishing a reference filtered signal when the mode of operation of the engine is changed from the first fuel to the second fuel;
closing a first fuel valve to stop the flow of the first fuel to the EFI;
waiting until the first fuel substantially empties from the fuel feeding device of the EFI system;
thereafteropening the second fuel valve to access the second fuel; and
operating the engine with the second fuel in the second fuel mode.
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24. A dual fuel system, comprising:
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a dual fuel engine powered by two different fuels including a first fuel comprising gasoline and a second fuel, and said engine being operable in a gasoline mode and in a second fuel mode;
an intake manifold connected to said engine for passing fuel to said engine;
a carburetor having a float bowl and a valve communicating with said intake manifold for feeding gasoline to said engine when said engine is operating in the gasoline mode;
a gasoline tank for storing and containing gasoline;
a fuel pump for pumping gasoline from said gasoline tank to said carburetor when said engine is operating in the gasoline mode;
a gasoline valve for controlling the flow of gasoline to said carburetor;
a control valve communicating with said air filter and said intake manifold for passing filtered air from said filter to said gasoline flowing into said intake manifold at an air fuel ratio regulated by said valve of said carburetor;
a one-way valve for permitting flow and passage of filtered air from said air filter to said air valve but preventing the flow of the second fuel to said air filter;
a second fuel tank for storing and containing the second fuel;
a second fuel valve for controlling the flow of the second fuel from the second fuel tank to said control valve;
said control valve being operable to permit flow and passing of the second fuel to said intake manifold when said engine is operating in the second fuel mode;
an engine control unit (ECU) operatively associated with said engine, control valve, and second fuel valve for controlling the performance of said engine, control valve, and second fuel valve; and
a mode selection switch connected to said ECU to select when the engine is operated in the gasoline mode or the second fuel mode.
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Specification