Maybe i dont understand how spark plug works but from what i gather, spark plugs are the spark that starts the combustion process in the engine...So when i pull the cord on my lawnmower it essentially creates electricty to start that "FIRST" spark by the spark plug starting the combustion...What i dont get is how the Spark Plug continues to "spark" and keep the engine running after my first cord pull?
2007-04-27 16:04:44 · 4 answers · asked by Anonymous in Home & Garden ➔ Do It Yourself (DIY)
Just a little bit further for clarity...
There is a magnet in the flywheel of the engine, there is also a coil of wire mounted very close to the magnet's path as the flywheel spins. When you pull the rope, flywheel spins around, and the magnet in it passes by the coil, which generates a high voltage in the coil, which is carried to the spark plug.
Timing of the spark is set upon positioning of the coil of wire, and the flywheel is not allowed to change its angular position on the crankshaft through the use of a key. At Top Dead Center (TDC) of the compression stoke, the magnet charges the coil, and a few degrees rotation of the flywheel later, as the magnet moves past the coil, the spark plug is fired just as the piston starts its power stroke. At the bottom of the of the power stroke, the magnet is on the other side of the flywheel. Piston starts to come back up (Exhaust Stroke), and at Top Dead Center again, the magnet passes by the coil and makes the spark plug fire again. But, because the piston is at the end of the exhaust stroke, and the beginning of the intake stroke, the spark is wasted since there is not anything in the cylinder to burn. As piston hits the bottom of the intake stroke, the magnet is once again on the other side of the rotating flywheel. When piston comes up during the compression stroke, the magnet energizes the coil of wire again, spark plug fires, and now ignites the compressed fuel/air mixture. This engine is known as a 4 stroke (aka cycle), the spark plug fires on every revolution of the engine, but you only get 1 power stroke (bang!) every 2 revolutions.
2007-04-27 16:40:30 · answer #1 · answered by Anonymous · 0⤊ 0⤋
They use a magneto. An electrical device that generates electricity and fires the plugs. There is a magnet in the flywheel that forms a transformer by passing the other side of a coil.
2007-04-27 19:48:05 · answer #2 · answered by Fordman 7 · 0⤊ 0⤋
the magneto is like a little generator so to speak. as the engine spins, each time it reaches a certain point, it lets loose the charge to the spark plug at just the right moment!
2007-04-27 16:19:17 · answer #3 · answered by robert s 5 · 0⤊ 0⤋
It has a magneto which generates electricity . As long as the engine turns the magneto gives it off.
2007-04-27 16:07:21 · answer #4 · answered by Jerry G 4 · 1⤊ 0⤋