So if an internal combustion engine is idling, when we add more gas/air by opening the throttle why does the engine accelerate? Do the explosions in the cylinders increase in velocity? I would have assumed that the explosions occur at the same speed regardless of the amount of fuel/air in the cylinder. So I don’t understand why the engine rpm increases.
thanks
In: Engineering
An engine burns a certain amount of fuel per second. There’s two ways that can be controlled: Fuel allowed per intake, OR the rate of intakes per second.
So, one way is to relax on the fuel line and let more fuel per intake.
The more fuel during intake, the bigger the explosions. The bigger the explosions, the more force. The more force, the more inertia is overcome. The more inertia overcome, the quicker the shaft moves. The quicker the shaft moves, the faster the engine runs.
The engine will have more strokes the faster it gets, which is more fuel volume per second into the engine as mentioned above, which makes the engine run even faster.
This runaway effect is basically only a problem for diesel engines because compressing diesel and air together is all you need for a boom, which can happen in a few ways outside of your control, so they need extra safety measures like blocking the air intake to shut the engine off, or at least making sure the air intake doesn’t take in diesel fumes.
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