Hello everyone, and welcome
in this video we're going to be talking about
why the rotary engine died
and now hopefully we'll be coming back
with the Mazda RX vision
but nonetheless the engine disappeared
for several years as a result of some of its disadvantages.
So we're going to get into four of those major disadvantages.
Now, if you haven't yet checked out my video on how rotary engines work
you'd want to check that out before watching this.
So the first disadvantage we're going to get into
is that by design wankel engines tend to have a low thermal efficiency.
And part of this is due to the fact that they tend to have lower compression ratios
But it's also because of the shape of the combustion chamber.
So here we're gonna have our two spark plugs
and they're going to be igniting the air-fuel mixture
And so this is going to begin to rotate this direction
as the combustion occurs
So your flame is going to be starting here
and it's going to want to travel out and ignite that air-fuel mixture
So it has to travel a long distance in order to ignite
All of this mixture, and so by the time it gets to over here,
you know you're continually growing that and making it more difficult
to ignite that mixture, and then you get to the end
where it reaches the exhaust port, and some of that air and fuel
is going to be unburnt, and so
you're going to be sending that fuel out the exhaust
And so this is going to tend to be why
you may see rotary engines spitting flames out the exhaust
is because they're not going to be able to burn all of that fuel
within the combustion stroke here
And so, because of that they're going to have a lower thermal efficiency
They're going to get worse fuel economy and they're not going to have good emissions.
Another big challenge for the rotary engine
is how to keep it sealed.
And so you have to remember that you don't want to let any of the gas in this chamber
to get into this chamber or vice versa
and it could pass over this way or it could pass around this way.
And so because of that you have these apex seals
which try and seal it out this direction
and then you've got face seals and side seals
which go along here on the edges to try to prevent gases from coming in this direction
Now the challenge that occurs
results because as you can see,
Combustion is going to be occurring constantly on one side
That's why this area is darker and this area is lighter.
So this is where intake is always going to be occurring
This is where combustion is always going to be occurring
And so because of that you're going to have a huge temperature differential
Where this side is going to be much hotter than this side
and so you are trying to maintain a seal
But the temperature is different
and so you're going to have the metal expending in different ways on different sides of this housing
and doing that makes it very difficult to create a good seal
And because of that you can have mixture of some of the air in one pocket getting over into the pocket of another chamber
Now in order to help insure that there is a seal, you can see here this hole which injects oil into here
so you'll have oil getting injected directly into the combustion chamber
and do that's to help maintain the seal around the edges
and lubricate the edges to you don't have anywhere
Now that leads us to our 3rd disadvantage
Which is the fact that design, this engine is going to be burning oil because you're ejecting oil directly into the combustion chamber
So periodically you are going to have to check the oil levels
and fill that and make sure that you're running a sufficient amount of oil because you are going to be burning that as the oil runs.
Now here we have the oil pump which is going to be actuated with the throttle.