How does an engine “suck” in air? Like during the intake stroke it goes down which creates a low pressure area and the air rushes in. But how does all that work? How does the piston going down allow air to be pulled in? LOL please explain it as simple TY!
In: Engineering
If it helps: The engine (or syringe – same concept) is not “sucking” air in. It’s more like air rushing into a newly created space.
Same thing in outer space: It’s not the vacuum of space sucking the air out of a space craft through a hole. It’s the air inside the spacecraft wanting to get out.
One thing people forget is that there is a lot of air surrounding us. We have been here a while so we have grown use to the weight of it pushing on us. On a single small square inch of your skin, there is the equivalent of a 15lb weight on that little square. *(Fun but slightly scary fact; with average skin surface area, the weight of air pushing on you totals around 44,000 lbs!)*
Air loves to fill up lower pressure zones and will fill up spaces pretty damn quick. When I asked my engineering teacher a while back he explained it like a syringe.
The body of the syringe is the cylinder
The little hole at the top is the intake valve
The plunger is the cylinder
When you pull the plunger down it creates that low pressure area, it’s ‘sucking’ the air in by you creating a minor vacuum and the air rushes in to fill it. Same thing in an engine, all the parts link together to open the intake valve when the cylinder starts it’s down/intake-stroke.
These engines are called naturally aspirated, but you can realistically only move SO much air at a time, so when you have these big engines going super fast, the atmosphere can’t keep up so they use a turbocharger or supercharger.
Turbochargers use a fan spool powered by the exhaust gases to suck in even more air and force it into the engine, and superchargers do the same thing but have turbines that are belt powered instead of exhaust powered. Both have their uses and pros/cons.
Technically it doesn’t suck, it creates a low pressure place where air rushes in from the outside.
Like when you “suck” with a straw, you seal your mouth and you are putting in work to make the internal cavity bigger, in turn the pressure in your mouth lowers while the outside stays the same, this pressure difference is equalized by the larger pressure air flowing inside your mouth. It just happens that there is a liquid between the air outside so it goes in first.
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Back to the engine. The first engines that had one cylinder had a huge flywheel that doe momentium it helped the engine “suck” when not stroking. The ignition phase made more energy then needed to drive the vehicle an drive the flywheel.
With multi cylinder engines, usually there is always a cylinder that ignites, helping the other cylinders do the exhausting and sucking air in.
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