(cars zooming) - How does a Koenigsegg Regera, a car without a transmission, get to over 250 miles an hour? With a torque converter. - [Driver] Just move. - Who's that-- what now? How'd that car stop without stalling out? Doesn't even have a clutch! That's un-possible! Well I'm gonna give you zero guesses how. That's right, it's a torque converter. The basic function of a transmission, whether it's manual or automatic, is to transfer power to the
drive shaft and drive wheels of a vehicle. It also makes sure that
the speed and torque of the drive wheels sync
with the speed of the engine so that everything's copasetic. In order to shift gears or come to a stop, something has to interrupt the connection between the constantly spinning engine and the sometimes moving drive shaft. If you stop the drive wheels
and there's no clutch, the engine dies. In a manual transmission,
you can engage the clutch and that disconnects the engine
shaft from the drive shaft so the engine can spin independently. An automatic transmission
doesn't have a clutch. It has a torque converter. Okay, real quick, let's hit
on the Koenigsegg Regera. You know, only one of the
sweetest cars on the planet. Maybe you heard of it? The Regera is a hybrid super car that has 15,000 horsepower. - What? - That has 1,500 horsepower
and can hit 250 miles an hour. It's got a twin turbo V8 combustion engine and three electric motors
but no transmission, so there's a combustion engine going directly to the rear wheels. Each output shaft of the rear wheels gets their own electric motor, and there's one more electric
motor on the crank shaft uses a starter, a
generator, a torque adder, a power adder, and it can be
used to charge the battery. You wanna take a guess as to what sits between
the combustion engine and the drive unit? Yup! It's a torque converter. Koenigsegg likes to call
it a hydraulic coupling, but we know what it is. It's a torque converter. A torque converter is a
fluid coupling system. That's a hydrodynamic device used to transmit rotating
mechanical power. Letting the car come to a stop while keeping the engine running isn't all that a torque converter can do. It's also got a secret function that not a lot of people know about. - [Male Voice] Spooky spooky. - It also converts torque. I know, right? (applause) Torque converter. Torque converters multiply
engine torque output, transferring the power from the engine to the transmission input shaft, and they drive the pump
of the transmission. That's all pretty important stuff. All right, so let's take a
look at one of these suckers. I know what you're thinking. Looks like a UFO. But most UFOs are bluish. (crash) This is the torque converter housing. It's bolted to the flywheel, so it turns at whatever
speed the engine's turning. Inside this torque converter
are four main components. We have the impeller, the
stator, and the turbine, and on newer cars, we also
find a torque converter clutch. Okay, let's start with the impeller. It's named after the first
vampire, Vlad the Impeller. It's got fins all over it, see? The impeller is welded onto the inside of the
torque converter housing, so the impeller spins with the engine. There's transmission fluid in here, and while the impeller is spinning, these fins catch the liquid
and throw it outward. The impeller essentially
acts like a centrifuge. I'm sure you know how fins
can fling a liquid out. You think of a blender. A little blade spins at the bottom, but it spins so fast, it
can shoot your smoothie all the way up the sides and out. And that's centrifugal force. And that's centrifugal force. Cen-centrifugguh vuss? Now imagine that blender
turned horizontally, and the whole thing's spinning. That's how the fins in
the torque converter work. Or, maybe it's more like a salad spinner where the whole thing spins. Well, whatever. The next component's the turbine. The turbine in a torque
converter is loosely mounted because it's gotta be driven. The impeller is the driver,
and the turbine gets drove. And the turbine is splined to the input shaft of the transmission, so insie the torque converter, the impeller is sending fluid out, and that is driving the turbine, which is then sending that
liquid down to the impeller, which sends it back to the turbine, and so on and so on and
so on and so on and so on and so on and so on and
so on and so on and s... (wormhole sound effect) Well anyways. Let's say I've got two fans, and not just because I wanna show you that I can afford two fans, but because we're gonna
do a demonstration. This fan is gonna be
powered by electricity. Nolan. That's really getting going. But look what's going on here. The unplugged fan with
no power is also moving. All right, now I'm gonna do another trick. I'm gonna stop this fan
with my bare bart hands. Thee? So, the nonpowered one is stopped. Now I'm gonna let it go. (applause) And it's moving again. This is what happens when
a car comes to a stop. The impeller always has power, because it is connected to the engine. The impeller's supplying
power to the turbine, which is connected to the transmission, which controls the drive shaft. When you brake, all that
stops is the turbine. So we don't have to cut
off power to the engine. And then, when you're ready to go again, you let off the turbine by
taking your foot off the brake, and you let it receive all
that sweet sweet power. And also, keep in mind
that I can afford two fans. That was fantastic. Now if this was all the
torque converter did, and don't get me wrong, that's a lot! But if it's all we did, we'd
just call it a fluid coupling. We'd also lose lots of energy because of all that churning loss. But we don't do that and
we don't call it that. The reason we call it a torque converter is because that other little
contraption we mentioned, the stator. The stator sits between the
impeller and the turbine, and that minimizes the churning loss. You know what else it does? It converts torque. The stator actually
increases torque output by redirecting the fluid. The stator blades have
aggressively sharp angles. You see how aggressive
and sharp those angles are on the blades of the stator? You can think of the liquid
being sent out of the impeller like it's water coming out a garden hose hitting the turbine. But when the stator's
in there and spinning, it acts like your thumb being placed over part of
the end of that garden hose. Now, the liquid being
sent off the impeller is shooting off those sharp angled blades, and the stator can only
move in one direction. It's actually now making
the turbine spin faster than the impeller. You got any idea what that's doing? It's increasing torque! It's a torque converter! It's all about using viscous force, which was also my nickname in high school. The stator's also got
this nifty one-way clutch, so when you're at a dead stop and the engine's turning the impeller, it's not moving. It only gets going when
the liquid hits it, and when the impeller and turbine are going around the same speed, it's now moving too, creating
less resistance to liquid because less torque is needed. Now let's look at the
torque converter clutch. This is basically a lockup clutch. It's the equivalent of
popping it into fifth in a five-speed manual. It fits around the turbine inside the torque converter housing. Remember those two fans that I can afford? (somber music) The one with power blew
the one without the power, but we lost some power in the process. That happens because the
impeller drives fluid to drive the turbine. You're always gonna lose a
bit of energy to that fluid. But at a certain point, the
fluid pressure builds up enough and the speed of the impeller
and turbine are close enough, and that causes this clutch
to lock the turbine into place making it a part of the
torque converter housing along with the impeller. Now you're at cruising speed, And these springs help
to dampen that shift, just like the springs we
saw on the clutch plate in a traditional clutch. Christian Koenigsegg said he approached torque
converter manufacturers and nobody was interested
in producing what he wanted at a low volume, and some of them couldn't even understand
what he was trying to do. - What is this? - So he built his own hydraulic
coupling to the extreme! It's got crazy fins all over it. It's super lightweight, made entirely out of machined aluminum. It can be opened or closed
or locked up completely. It's not needed for the
vehicle to function, but it is necessary to attain that mindblowing acceleration. The Regera's basically in
seventh gear all the time. When you're at a dead stop
and you start to accelerate, the electric motors are driving
the rear wheels directly. Then, between 20 and 30 miles an hour, the combustion engine takes over. The hydraulic coupling steps in, and it begins that
torque converter effect. While the torque converter's
increasing the torque from the combustion engine,
thanks to the turbine, the electric motor of the crank shaft, well, that's increasing torque as well, and that allows the Koenigsegg Regera to go from zero to 250
in 20 goldarn seconds. Koenigsegg says, if you just
had the combustion engine on this car, it'd go zero
to 60 in seven seconds. Just leaving the rear
wheel electric motors, you'd to zero to 60 in four. But the combination with
the torque converter is what allows it to go from
zero to 60 in 2.8 seconds, or as much as the wheel grip allows. He reinvented the hybrid electric and reimagined the old
tech of the fluid coupling, torque converter, to help do it. Now if you'll excuse me, I
gotta go buy a third fan. Torque converters! Thanks for watching this
episode of Science Garage, guys. We can't do this without you. Subscribe to Donut. Hit this beautiful globe. Check out this Up to Speed on Koenigsegg. Check out this Wheel House on cop cars. Follow Donut on Twitter
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I did with the fans.
