I was wondering how a three piston engine can work.
How do they get the timing to fire at the correct time?
Its an odd number wouldn’t this make the car shake and jumble?
[Link guaranteed to mess up your computer deleted. -manhattan]
Not if it’s an in-line engine. Either Acura or Infiniti (I forget which) makes (made) a 5-cylinder engine.
You are used to an even number of pistons divided in half on either side if the engine. If they are all in one row you won’t get he instability you mentioned.
Well, car engines are 4-cycle engines in the sense that each cylinder goes through a combustion -> exhaust -> injection -> compression cycle. This means that each cylinder is doing work only 25% of the time. So you need 4 cylinders, and 3 is not enough. Is this what you are asking?
I think the answer is that you don’t really need 100% coverage. Sure, the engine won’t run as smoothly, but if the flywheel is big enough, it smoothes out the rotation enough so that the engine keeps running. Put one cylinder on a huge flywheel and it will keep running if the load is small enough - the cylinder adds a bit of energy to the flywheel once every 2 rotations, and the rest of the time the flywheel is just turning by inertia (angular momentum).
And besides, the duty cycle of each cylinder is less than 25% anyway - I don’t think combustion starts when the piston is at the very bottom and continues till the piston reaches the top, and even if it does, when the piston is near the top or bottom it can’t exert much torque.
By the way, one novel I read referred to a one-cylinder diesel engine on a ship. Anybody know if there really is such a thing? As I explained, it should work, but doesn’t sound very practical.
Of course there are plenty of one cylinder engines! Not only on boats but on motorcycles. What is the problem? How many cylinders does your lawnmower or leafblower or portable electric generator have?
My boat has a 3 cylinder Yanmar diesel but they make it in 1 and 2 cylinder versions as well.
I guess the only requirement with the number of cylinders is that it has to be a natural number.
If n is the number of cylinders, then their cycles are spaced 1/n of a cycle apart so it runs more evenly.
Maybe you are thinking that all the pistons have to be in either up or down positions at the same time when the spark is applied.
On a 3 cylinder engine the crank is arranged so that firing occurs every 240 degrees.For some reason this makes for a very torquey engine, even at low revs.
There are notable exceptions. One I can think of right now is the Laverda Jota motorcycle where 2 pistons were up and 1 was down etc.There were balancer shafts but it was a queroulous beast suited to road worker types yet it sold quite well.
Eventually the did fit a more sensibly timed crankshaft but it took them a while to get round to it - very relaxed those Italians.
Geo Metros use 'em. Might be better tech info at howthingswork.com
The most common engines are of the V design with and even number of cylinders like V8, V6, V10, and V12. I forget the angles for all the different V engines. I am not sure what configuration they would use to balance a 3 cylinder’s vibrations.
A few additions. The I5 was a trademark of Saab for a long time, not Infinity or Acura.
The most common angles for a V engine are 60 and 90, with 30, 45, and 180 showing up occassionally, although the 180 would actually be an oppositional engine, not a V.
The Mustang was originally conceived with a V4 engine.
Now back to your regularly scheduled program.
–Tim
The 3 cylinder engines I’ve seen are all parallel pots.
The balance is inherant in the nature of the crankshaft timing.
All except that Laverda Jota engine which vibrated madly till you got well up into the 9ks.This encouraged riding at ten tenths just to keep the feeling in your hands and gained it a reputation as a hooligan machine.