Hello everyone and welcome!
So you're thinking to yourself, I want a sports car and so you head to the Toyota dealership.
Well, they don't sell a lot of sports cars so that doesn't make all that much sense, but now you're saying
I want a sports car with a CVT.
I don't really get you but
Toyota has something for you a CVT with a launch gear was it for the performance oriented folks that also like
CVTs. Not exactly so in this video I'm going to be talking about
Toyota's direct-shift CVT which is a CVT and it does have a specific gear just for accelerating from a stop,
but it's not for performance reasons like it may sound Toyota CVT with a launch gear instead it is for efficiency.
So how does this all work?
Well if you look at a CVT
and you look at its gear ratio
versus its efficiency curve so when it's on the extreme ends of that gear ratio when it forces one of the ends of that pulley
to be at a super narrow radius for that belt to go around then it's not super efficient in that range ideally
it's somewhere in the middle where both pulleys
have a nice even large radius for that belt to go around and it's going to be in a happy
efficient range and as you get to the extremes
meaning if you're at a very low speed and you're requesting a very high gear ratio
or if you're at a very high speed and you're requesting a very low gear ratio
then what's going to happen is you're going to be in an inefficient range of that
CVT. While inefficient is bad of course and especially of course when you are
Toyota and so they made an adjustment for this so instead of
previously where they had to have a
CVT range that accommodated high gear ratios with low vehicle speeds and high vehicle speeds with low gear ratios they
instead shift the CVT to operate and arrange for higher vehicle speeds and lower gear ratios and allow a direct gear to take care of
those high gear ratio scenarios where you're accelerating from a stop and a direct gear is of course a very efficient way of transmitting power
because you know there's not losses that are associated like going through a belt
so a very efficient method for low speed range and then switching over when you're driving
you know normal driving conditions at those higher vehicle speeds
you're now operating in a more efficient range whereas before you know you had to sacrifice
kind of somewhere in the middle in order to be efficient in either
end so you've got a launch gear for low speed efficiency and you've got a CVT for high speed transmission efficiency
and there actually is a performance benefit to this so when you're
accelerating from a stop by having that more aggressive direct gear ratio you actually get a better response and better launch
acceleration so just kind of showing a simple curve here acceleration
versus time a little bit greater acceleration
and that response comes a bit sooner by using a direct gear rather than a CVT
some people don't like the kind of spongy response that CVTs have which is kind of eliminated
through the use of this direct gear from starts next we get
into the belt angle used by the pulleys and this is actually narrower
so it's gone down from 11 degrees to 9 degrees
so why were they able to reduce that belt angle well essentially this is because either removing the responsibility of launching the car
from a dead stop and by removing that responsibility where the acceleration load is very high
and the torque transmitted through that CVT is very high from that initial acceleration
you're able to use a smaller CVT and a narrower belt because it's no longer
responsible for that really high torque application where you're initially
accelerating the vehicle so it's smaller it's narrower and as a result of having that narrower angle
you're able to improve the shift speed so 20%
faster shift speed and that's simply because the pulleys don't have to move in and out quite as much in
order for it to change the gear ratio as much so
it's the same amount of movement will change how much the gear ratio has changed more and finally I want to talk about
gear ratios because there's two kind of interesting facts about
CVTs first of all is most people don't like driving CVT's they say they don't like the way it feels
the second thing is most people don't really know what they're driving
you know there's a lot of car enthusiasts out there
but we're not the majority of humans so most humans they get in a car. They don't really care
what's going on underneath, they don't know what's going on underneath the hood
they just know what they like and what they don't like and what humans tend to like is the monotonous dull
excitement that comes from an automatic transmission where it shifts gears
they'd like to have those gear shifts, so
CVT engineers have decided you know what we can make you feel like you're driving a regular old boring
automatic when in fact you're driving a rather exciting CVT
and so what happens is let's say you floor it in this Toyota using this CVT well
it'll start in that launch gear and it'll start your acceleration
going up to your max rpm
then it will drop down a gear ratio, and it will switch over to the CVT belt
and then it will be in it's you know it's its most aggressive gear ratio that that CVT belt allows
so on the low end of that
CVT when you finally reach peak rpm you of course have to switch to a lower gear ratio and instead of just a continuous smooth
you know remain at peak horsepower
which would be ideal for acceleration instead it creates steps
within the CVT so you have set gear ratios that it maintains
so it'll drop down to a lower gear ratio keep accelerating up until peak rpm drop down into a lower gear ratio keep
accelerating up and so on as you continue if you've got your floor
you know if you've got your foot to the floor and you're asking for max acceleration if you don't get it too much throttle
it's just gonna put it in an efficient rpm, and you know you're not going to really have those gearshift sensations
but you're not going to notice it either because you're barely giving it any throttle and in regular automatics
you know if you're giving it extremely light throttle you really aren't going to notice significant. You know feel
from that gear shift so from a CVT it can just put it in an efficient rpm
let it just sit there let the engine sit there and adjust the belt as necessary as your vehicle speed increases and
so this is a silly thing that's done because humans don't like CVTs
they like the sensation of gear shift when in reality the faster thing to do would just put it at peak horsepower
when you floor it and leave the gear ratio
constantly adjusting so that it maintains peak horsepower as you go across whatever RPM is peak horsepower
just keep the the gearing to just constantly to allow for that constant rpm of peak horsepower
but that's not what humans like so engineers put in silly things like this to make you guys happy
not you guys, but you know the folks that drive CVTs, so
ultimately CVTs are cool. I think they're better
transmissions than most of the automatic transmissions that are out there
people don't like it when I say that but I've driven a lot of vehicles, and I think truthfully
automatics a lot of them out there feel terrible there happens to be an 8-speed ZF transmission
that's amazing and it's getting put in everything now, and it's a great transmission
but there are also very good CVTs out there from a you know feel perspective
I think they've gotten a lot better than what they used to be and I think it's cool that Toyota has introduced this launch gear
into one of their transmissions, it'll be interesting to try out so thank you all for watching
and if you have any questions or comments of course feel free to leave those below.