ILMA Compoundings December 2016 - 18

THE EVOLUTION OF... TRANSMISSIONS

CVT System Design
Ed Post

A

s carbon dioxide (CO2) emissions regulations tighten
the world over, original equipment manufacturers
(OEMs) continue to look for every opportunity to
improve the efficiency of their vehicles. The transmission
system is a key target, and in conventional stepped automatics
we have seen the trend for lightweighting and an increase in the
number of gear steps.
OEMs have also introduced new hardware, including dual clutch
transmissions (DCT) and continuously variable transmissions
(CVT). So far, the uptake of the different transmission types
has varied from region to region. Among other factors, their
popularity is typically a reflection of the driving preferences in
each region.
CVTs offer a number of benefits. One benefit in particular is
the ability to optimize engine operation that provides CVTs

The CVTi-S mimics the
familiar characteristics
of geared automatics by
creating a sense of positive
shift engagement.
with an advantage in overall vehicle fuel efficiency over other
transmission designs. They continuously and seamlessly select
the optimum ratio for the engine as driving conditions change,
without the fixed ratio constraint of step-gear transmissions.
This variable ratio flexibility, within the minimum and maximum
limits of a CVT design, allows the engine to operate at peak
efficiency with uninterrupted torque transfer to the drive
wheels.

CVT Deployment
Automatic transmissions are being deployed at an increasing
rate worldwide, even in regions that had been bastions of
manual transmissions. However, even though there have been
advances in conventional planetary gear transmissions, we
expect their use to plateau. In our view, much of the future
growth will come from the deployment of unconventional CVT
and DCT designs. While OEMs including Volkswagen, Audi and
Hyundai are leading the deployment of DCT systems, CVTs
are currently seeing wider use across a broad range of OEMs,
including Nissan, Honda, Subaru and Toyota.
These OEMs are likely to deploy CVTs across all regions.
However, China and South Asia are forecast to lead the growth
since the lower-torque engines used in these regions present
fertile ground for CVT technology. We could expect to see
more than a 10 percent compound annual growth rate as these
regions shift away from manual transmissions towards this
advanced technology. We also expect to see strong CVT growth
in North America, where technical advancements enable their
use in larger vehicles.

CVT and OEM Activity
Dedicated transmission manufacturer Jatco is expected to
remain the largest global CVT manufacturer and has announced
that its global production volume of CVTs reached 30 million
units at the end of March 2016. The company has introduced
the CVT8 for medium and large vehicles up to 3.5 liters,
which it says combines better environmental performance
and a stronger, sportier drive. The transmission is reported to
improve fuel economy by up to 10 percent compared with a
conventional Jatco CVT.
The company has also launched the "one-motor two-clutch"
CVT8 Hybrid, for medium and large four-wheel drive vehicles.
Jatco says it offers a significant friction reduction and wider ratio
coverage using a built-in motor and a clutch for engaging or
disconnecting the engine within the torque converter housing.
Honda has recently expanded CVT applications in North
America, and future growth is expected to be primarily in China

Vol. 66 No. 12 * 18 * December 2016 Compoundings
ILMA Compoundings December 2016

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