Supplying supplementary fuel for engine startup
View Patent ↗Supply of supplementary fuel is controlled through a supplementary fuel supply passage in a carburetor to an engine according to a variety of methods and devices.
1. A method of controlling supply of supplementary fuel to a supplementary fuel supply passage in a carburetor for supplying a fuel and air mixture to an engine having a piston connected to a rotary crankshaft, comprising:
providing an electromechanical valve in communication with and normally closing the supplemental fuel supply passage;
providing an electronic control module sensing engine crankshaft rotation and determining the crankshaft rotary speed;
providing a magneto device including a flywheel rotated by the crankshaft and having a magnet group, and a lamstack having at least a first leg carrying a first coil and a second leg carrying a second coil, with the magnet group and the lamstack first leg and first coil configured to produce a current for opening the electromagnetic valve created by the magnet group rotating past the lamstack first leg and the lamstack second leg and second coil configured to produce a current for powering the electronic control unit created by the magnet group rotating past the lamstack second leg; and
the control unit controlling the supply of current to initially open the electromechanical valve only when the engine intake vacuum is at least about 80% of the peak engine intake vacuum, the engine crank angle is about 40° to 60° BTDC of the piston, the engine crankshaft speed is not greater than about 2,000 rpm, and the engine crankshaft has rotated not more than about 20 revolutions from initial cranking of the engine for starting the engine.
2. The method of claim 1 wherein the electromechanical valve is initially powered to open only when the engine intake vacuum is at least about 90% of the peak engine intake volume.
3. The method of claim 1 wherein the electromechanical valve is powered to initially open only if the current supplied by the first coil is at least about 65% of the peak current supplied by the first coil.
4. The method of claim 1 further comprising causing a spark for igniting a fuel-and-air mixture in the combustion chamber of the engine to occur at an engine crank angle of about 30° to 60° after the engine fuel and air mixture intake vacuum begins to peak.
5. The method of claim 1 which further comprises controlling the firing of a spark plug to ignite a fuel and air mixture within the combustion chamber of the engine to occur in the range of about 6° to 24° BTDC of the piston.
6. The method of claim 1 further comprising sensing the temperature of the engine within the first three revolutions of the crankshaft upon initial cranking of the engine and determining whether this engine temperature is greater than a predetermined temperature of not more than 95° F. and if the sensed temperature is greater than the predetermined temperature prohibiting opening of the electromechanical valve.
7. The method of claim 1 which further comprises intermittently opening the electromechanical valve for at least two cycles wherein each cycle includes a period in which the electromechanical valve is closed for at least two revolutions of the crankshaft and the total open time of the electromechanical valve for all of the cycles collectively is not more than about 20 revolutions of the crankshaft.
8. The method of claim 1 further comprising providing a rectifying electrical circuit interposed between the first coil and the electromechanical valve.
9. The method of claim 1 further comprising providing for only manual cranking of the engine for starting the engine.
10. The method of claim 1 wherein the engine is a two-cycle engine.
11. A system for supplying supplemental fuel through a carburetor to a fuel and air mixture intake of an engine with a piston connected to a rotatable crankshaft, the system comprising:
a supplementary fuel supply passage between a carburetor fuel chamber and an air-and-fuel mixing passage of the carburetor;
an electromechanical valve normally closing the passage;
an electronic control unit sensing engine crankshaft rotation and determining the crankshaft rotary speed;
a magneto device including a flywheel rotated by the engine crankshaft and carrying a magnet group, and a lamstack having a first leg carrying a first coil and configured to produce a current to power the electromechanical valve to open the passage by the magnet group rotating past the first leg and a second leg carrying a second coil and configured to produce a current to power the electronic control until when the magnet group rotates past the second leg; and
the electronic control unit controlling the current to power the electromechanical valve to initially open the supplemental fuel supply passage only when the crank angle of the rotating crankshaft is about 40° to 60° BTDC of the piston, the sensed engine crankshaft rotary speed is not greater than about 2,000 rpm and the engine crankshaft has rotated for not more than about 20 revolutions from initial cranking of the engine for starting the engine.
12. The control system of claim 11 wherein the electromechanical valve is initially opened only when the current produced by the lamstack fist leg and first coil is at least about 65% of the peak current produced by the lamstack first leg and first coil.
13. The system of claim 11 further comprising the electronic control unit controlling a spark to ignite a fuel-and-air mixture in a cylinder of the engine to occur in the range of about 6° to 24° BTDC of the engine.
14. The control system of claim 11 wherein the engine control unit further comprises circuitry which within three revolutions of the crankshaft upon initial cranking the engine senses the temperature of the engine and determines whether the sensed engine temperature is greater than a predetermined temperature not greater than about 95° F. and if the sensed engine temperature is greater than the predetermined temperature prohibits powering of the electromechanical valve to open the supplemental fuel passage.
15. The system of claim 11 wherein the electronic control unit intermittently opens the control valve for at least two cycles wherein each cycle includes a period in which the electromechanical valve is closed for at least two revolutions of the crankshaft and the total open time of the electromechanical valve for all the cycles collectively is not more than about 20 revolutions of the crankshaft.
16. The system of claim 11 wherein the power and control module further comprises a rectifying electrical circuit interposed between the first coil and the electromechanical valve.
17. The system of claim 11 for a two-cycle engine.
18. The system of claim 11 for an engine which is only manually cranked for starting the engine.
19. The system of claim 11 for a two-cycle engine which is only manually cranked for starting the engine.