字幕表 動画を再生する 英語字幕をプリント 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.