bp's science: how a car engine works (v.1)

Yesterday we went to the playground. There are a lot of good playgrounds around here and Oliver has his favorite thing at each one, whether it be the race car, the bus, or the train (hmm, I see a theme here). While his joy with the pictured toy below is not a favorite, I've always liked it.


And the reason why is because it's a perfect subject for bp's science. You see, it's much like a model of an engine and it shows one how the engine works.

The green and red pieces together make up the pistons.
The blue pieces represent the connecting rods.
The yellow center piece represents the crankshaft.



First, the plastic tube surrounding the piston fills with gasoline (step 1.) as the piston goes down. Then the gasoline is ignited by a spark plug going off (step 2.) and creating a source of heat, which ignites the gasoline causing it to explode (step 3.). This explosion pushes the piston down strongly releasing energy that goes into the connecting rods. The connecting rods change the up and down motion of the pistons into the circular motion that goes into the crankshaft and thereby turns the wheels. The piston then pushes back up to release the exhaust (step4.).

So the action of the piston is down (gas in), up (mixture volume decreased, spark plug goes off), down (mixture explodes), up (exhaust out). So an engine piston action is up, down, up, down, up, down, up, down. That's why you need oil (and need to get it changed every so often). See this video of the toy in action. Many thanks to my science assistant.

And a quick note: keep in mind that engines are usually in a V shape, in a line, or even in a boxer shape. Never are the pistons arranged like a star as seen in the toy. Still, there is such a thing as a rotary engine, but that is a whole other post.