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  • Hello everyone and welcome.

  • In this video we're going to be talking about

  • Infiniti's new VC-T engine.

  • Variable Compression Turbocharged Engine

  • Now, I personally think they should have

  • called it Variable Compression Ratio

  • and made VCRs great again

  • but that's besides the point and not my decision to make.

  • So the reason why this engine has gotten so much media hype lately

  • is because what it's doing is trying

  • to remove compromise from engines.

  • So traditionally you can have an engine that's really

  • powerful but it won't be very efficient,

  • or you can have an engine that's very efficient but it won't be very powerful.

  • So what Infiniti's trying to do here

  • is allow you to choose between both of those options

  • with the same engine.

  • You're not going to have both at the same time

  • but you can choose to run it efficiently

  • or you can choose to run it with a lot of power

  • depending on where that foot is on that gas pedal.

  • So the way they do this is

  • by incorporating this variable compression ratio.

  • It can be as low as 8:1

  • with lots of boost for high power

  • or it can be as high as 14:1 for a very efficiency operating condition

  • So how does this system work?

  • How does it do this?

  • Well it looks like this complex mess

  • which it kind of is but we're going to break this down,

  • simply so that we can understand what's going on.

  • So the way I want to do this is

  • look at this in two different sections.

  • This top section here

  • which is just going to be like a normal engine

  • and then this lower section here

  • which is going to be used to adjust the compression ratio.

  • So for now, let's just ignore everything below this

  • and look at what we've got going on up top.

  • So here we have our piston, the connecting rod, the cylinder, everything like usual.

  • The difference here is this crankshaft,

  • so you can see there's this rectangular piece called the multilink.

  • and that's going to be linking up these two sections.

  • And so your crankshaft, is going to be right here,

  • the center of rotation, right there.

  • So, to give you an understanding of what this looks like

  • here we have a crankshaft,

  • and so this right here

  • is this right here

  • and then the center, this axis which it rotates about

  • is of course right there, so looking at this

  • this crankshaft right here how this will be oriented

  • would be just like that

  • with the center right here and this will rotate around

  • This piston will come down and up and down and up

  • And rotate this section

  • And now important thing you need to understand is that this multi link right here this rectangular piece

  • maintains this orientation as it goes around the crankshaft it doesn't rotate

  • it maintains that orientation and so that's what we're gonna be using

  • to change the compression ratio is changing the angle of this

  • rectangular piece right here so you can see if you were to tilt it up that would

  • cause this piston to move up increasing the compression ratio and if you were to

  • tilt it down that would decrease the compression ratio pulling the piston

  • down so what we're looking at right here is top dead center the crankshaft

  • oriented like that so you've got the top of it right here and then the center of

  • it right there and it's about to rotate down like that. So how this works on the

  • compression ratio adjustment system basically all you need to know about

  • this side of the system the most important piece is that what you're

  • trying to do is to move this lower link up and down because as you move this

  • lower link up and down you change the orientation of this rectangular piece

  • this multi link and so if you were to pull it down you can see it increase the

  • compression ratio because it pivots about this point pushes the piston up

  • and if you were to push it up you would pull the piston down decreasing the

  • compression ratio at top dead center Okay great so how does it do this?

  • Well, the magic of it really comes down to this central shaft right here but

  • basically we have a harmonic drive right here you can just think of this as a

  • device which rotates clockwise or counterclockwise and then you have this

  • actuator arm which rotates this central shaft. So the central shaft rotates about

  • this pivot point right here so you can see if this central shaft were to rotate

  • downward if it were to rotate down that direction it's going to pull this lower

  • link down and by pulling that lower link down it's pushing the piston up

  • increasing the compression ratio. I f it were to rotate upward if this piece were

  • to rotate up like that it's going to push up on here and then that's going to

  • pull this down and that's going to decrease your compression ratio so it's

  • all dependent on which way you turn this actuator arm it's linked up and it's

  • going to cause this to pivot about this point right here so you can see

  • currently this is the state it's in if you were to rotate it using this linkage

  • you could rotate it down and you would increase your compression ratio to 14:1

  • or you could turn it all the way up and that would push this up pivot this

  • down and that would decrease your compression ratio down to 8:1 so you

  • know once you kind of see all of this work together it's really not that

  • complicated but it is kind of a mess looking at all of it together

  • and so the important thing to just kind of see is that it can rotate

  • this rectangular piece rotates around the crankshaft about this point right

  • here and then these two pieces right here these two links keep this

  • rectangular piece in that orientation as it goes around and you can change that

  • by changing the height of this lower link using that central shaft great

  • that's all clear right? And so you know why do you want to do this? Well as I

  • mentioned you kind of remove that compromise so you can use a low

  • compression ratio you can put in tons of boost and so why do you need a low

  • compression ratio well you want to prevent knock and so you know you can start

  • to get into some tricky scenarios if you have high compression ratio and high

  • boost so to make it safe reliable you decrease the compression ratio and then

  • you eliminate, you know, you reduce your chances of knock and you have a safer-running,

  • more powerful engine well then you can pump it up to that 14:1

  • to get that really high efficiency not only does 14:1 have a higher

  • thermal efficiency but they've used this in combination with the Atkinson cycle

  • so they're using variable valve timing to leave those intake valves open for a

  • short duration during that compression stroke and that improves the efficiency

  • I have a whole nother video explaining how that Atkinson cycle works if you're

  • interested but basically what they're doing is giving you really good

  • efficiency in one operating condition and lots of power in the other operating condition

  • So, is it going to be the most efficient two-liter engine out there?

  • Well no, of course not. And is it going to be the most powerful 2-liter engine out there?

  • No. but what it's doing is its allowing you to choose between both of

  • those so if you're cruising down the highway you can get great fuel economy

  • and then if you're ripping through you know a canyon you can actually have some

  • fun it'll decrease the compression ratio load it up with boost and you've got

  • all kinds of power so it is a very cool option to give you efficiency when you

  • want it and power when you don't so thank you guys for watching and if you

  • have any questions or comments feel free to leave them below

Hello everyone and welcome.

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B2 中高級 美國腔

英菲尼迪驚人的新發動機--可變壓縮和渦輪增壓。 (Infiniti's Amazing New Engine - Variable Compression & Turbocharged)

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    kinhuabin 發佈於 2021 年 01 月 14 日
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