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  • 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.

Hello everyone, and welcome


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B1 中級 美國腔


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    OolongCha 發佈於 2020 年 09 月 09 日