- [Narrator] Toyota helped start
the electrification revolution in 1997
when it introduced the hybrid powertrain
and proved its viability for use in passenger vehicles.
Since then, Toyota has expanded its hybrid range
to include multiple vehicles
that have sold millions worldwide.
Today, the Toyota Hybrid System or THS, is an evolution
of that original "series-parallel" hybrid design
where the wheels can be driven by the gas engine
or the electric motor, or both, and it's been further
refined to provide better performance and efficiency.
Above all, THS never needs to be plugged in
since it completely charges the hybrid battery
via engine power or regenerative braking.
Plus its components, including the hybrid battery
have been designed with longevity, durability
and reliability in mind.
To really appreciate what's happening under the hood
of these vehicles
and understand what makes them so efficient
you need to take a closer look at the entire process.
From the moment the start button is pressed.
(upbeat music)
Unlike a traditional gas powered vehicle that cranks
a starter motor to get things going, a hybrid start button
first powers up the system's onboard computers
the Electronic Control Units.
Like virtually all automotive systems
these ECUs operate on the 12 volt battery circuit,
which also powers vehicle lighting, windows, door locks
and similar features.
This explains why you'll find a typical 12 volt
automotive battery on every Toyota Hybrid.
Once online, these ECUs check things
like the hybrid battery status, engine temperature
and ambient temperature.
They also manage some of the most crucial components
in the vehicle, the system main relays.
These relays are next in line
and do the heavy lifting of sending hybrid battery power
to the components that utilize high voltage
and ensuring the battery power is switched on
in a safe manner when the vehicle starts
to avoid spiking any element of the system.
For safety if any fault or collision is detected
these relays are designed to immediately power down,
isolating the hybrid battery while shutting off
the high voltage cables,
which are color coded in bright orange.
(upbeat music)
Once the ECUs are up and running
the hybrid battery power is sent to the inverter converter.
This device controls the high voltage flow
to and from the motor generators
and the high voltage battery and maintains the charge
on the 12 volt battery anytime the vehicle is running.
The motor generators, as the name implies
works as both a motor, providing power when needed
or a generator to charge the hybrid battery.
Each plays a critical role in how THS works.
Motor generator one or MG1 is located directly
behind the engine, and when used as a motor
starts the engine on demand anytime it's needed.
Because MG1 is much more powerful
than a traditional starter motor,
it doesn't require a gear drive
and is able to start the engine silently.
This is the reason you never hear the typical starter sound
on a Toyota Hybrid.
Once the engine is running, MG1 is used as a generator
and charges the hybrid battery.
A major key to how THS works is a planetary gear
set that acts as a power split device.
This is used like a continuously variable transmission
to manage the output between the engine
and the motor generator two.
Parallel power output from the engine
and MG2 work together or separately
to power the wheels when accelerating and cruising.
MG2 also acts as a generator when the brakes are applied
or when coasting to capture the energy
from the vehicle's forward momentum
and charge the hybrid battery
anytime the vehicle slows down.
This two-motor hybrid design also takes advantage
of Atkinson-cycle cam timing, which essentially
means the intake valves stay open slightly longer
and create less pressure in the cylinders.
This design makes
for exceptional efficiency and low tailpipe emissions,
but the trade-off is a relative lack of power.
That's why it works alongside motor generator two
to produce a combined pool of power
helping provide both exceptional efficiency
and good power response, the best of both worlds.
(upbeat music)
So, what if you wanna make a front-wheel-drive hybrid
an all-wheel-drive vehicle?
It's surprisingly simple.
Unlike traditional all-wheel-drive vehicles
that use a mechanical drive shaft to distribute the power
from the engine
out to all four wheels, Toyota engineers simply
add an additional third motor generator directly
to the rear, right in between the wheels.
This explains why it's called Motor Generator Rear.
This standalone unit has no mechanical connection
to the rest of the drivetrain,
but still helps add extra traction, capability
and power at the rear when it's needed.
And like MG2 generates power
for the hybrid battery when coasting or breaking.
So that's a quick look
at the THS that's found within so many Toyota vehicles
and it's only one part of Toyota's electrification story.
Be sure to check out other videos in this series
to learn more about Toyota's electrified powertrains.
To explore the full electrified lineup from Toyota,
visit toyota.com/electrified.