Industry
insiders are awaiting the next stage in the development of the NuVinci
continuously variable planetary (CVP) transmission developed by Fallbrook Technologies
Inc. of Cedar Park, Texas.
Developed originally for cycles, the company claims the
transmission has applications in passenger cars, light commercial vehicles and certain
off-highway duties.
Fallbrook Technologies Inc.
last month created new management positions in Europe in a bid to expand its level of interest
still further beyond cycles into other areas of application.
In December last, Dana Holding
Corporation based in Maumee, Ohio, announced plans to open its sixteenth global
technology centre in Cedar Park, adjacent to Fallbrook Technologies Inc. with
which it has a licence agreement.
According to Dana, established 110 years ago, the company was formed ”with a game changing innovation that
helped to commercialize motorised transportation and our new technology centre
in Cedar Park will propel the development of the next generation of
fuel-efficient transmission technology.”
Dana notes that in September
2012 it secured an “exclusive licence from Fallbrook Technologies Inc. to
engineer and produce continuously variable planetary (CVP) technology for use
in light-vehicle and certain off-highway transmissions in the end markets that
Dana serves.”
Dana plans to market the
technology under the VariGlide brand name.
Significantly, also that
same month, Fallbrook Technologies Inc. announced that Allison Transmission
Holdings Inc. and Dana Holding Corporation had formed a strategic alliance with
Fallbrook Technologies Inc. to “develop, manufacture and commercialize
high-efficiency transmissions for passenger vehicles, commercial vehicles, and
off-highway equipment.”
That alliance is
interesting as Allison Transmission also has an exclusive licence agreement
with Torotrak plc in the UK, again for infinitely variable transmissions (IVTs).
Presumably the three
companies are not embarking on conflicting vehicle products and markets.
The two transmissions have
common elements. Both rely on friction to transmit torque using rolling
elements and elastohydrodynamic traction fluids of the type manufactured by
Shell. Shell and Torotrak have worked closely for many years in the development
of such fluids for traction drive continuously variable transmissions (CVTs).
According to Lawrence E. Dewey,
chairman, president and chief executive officer of Allison Transmissions: “Ours
is an ideal collaboration for developing new technology optimized for the next-generation
of commercial-duty vehicles.”
Fallbrook Technologies Inc.
claims the story of the CVT can be traced to 1490 when Leonardo da Vinci
developed a drawing describing what many believe represents how a CVT would work.
In reality, the practical development
work lies much closer in time and is associated with the Hayes transmission developed
pre-World War 2 for passenger cars. Frank Anderson Hayes of Middleton,
Monmouth, New Jersey developed a method of transmitting power at a variable
speed but at maximum torque.
Hayes took out various
patents in the US and the UK in the late 1920s and early 1930s. During his
travels to the UK, Hayes met Herbert Austin through J. L. Cloudsley who had an
engineering company in the form of Cloudsley Engineering Ltd. Herbert Austin’s
company manufactured Austin cars.
This collaboration led to
F.A. Hayes and Cloudsley Engineering Co. Ltd. signing an agreement to supply continuously
variable transmissions (CVTs) to the Austin Motor Company for installation in its
Westminster and York models. This took place in the 1930s.
After World War 2, the
outcome of this development led in the 1950s and 1960s to the creation by
Forbes Perry of the Perbury transmission. Most, if not all, the patents for the
Perbury transmission were acquired by a UK Government body, the National Research
Development Corporation (now British Technology Group – BTG).
The present Torotrak plc
was spun out BTG and is based in Leyland, Lancashire where the company is
undertaking development work on IVTs with Allison Transmission, among others.
Leyland Vehicles, formerly
based in Leyland, Lancashire, embarked on development of the Perbury
transmission for buses and explains the reason why Torotrak is based at the
same location.
Torotrak expects to make a
major announcement this year regarding its association with Allison
Transmission.
Gears into spheres
Fallbrook Technologies Inc. describes its system as “transforming
gears into spheres”. And it is here the system differs from the Perbury arrangement,
although the concept is similar.
The Fallbrook CVT is based
on a set of rotating, tilting balls arranged between two rings. In the case of
the Torotrak system, variable ratio is achieved by means of rollers running in
conjunction with a toroid.
Fallbrook notes that “torque
from an engine is transferred through the input disc to the balls using a thin
layer of traction fluid. The torque is then transmitted through the balls to
the output disc through another layer of traction fluid.”
“The input disc and output
disc are “clamped” onto the balls tightly so that the requisite amount of clamping
force is provided for the amount of torque being transmitted,” claims
Fallbrook.
“The speed of the output
disc compared to the speed of the input disc, or speed ratio, is controlled by
the angle of the ball axes relative to the axis of the transmission,” the
company adds.
Both overdrive and
underdrive are possible with the arrangement; as with the Torotrak system.
Significantly, Fallbrook
claims its system is scalable across various applications, though most of the
applications thus far are with bicycles.
The Torotrak system is also a scalable technology that has been applied
to grass-cutting machines, passenger cars and heavy commercial trucks and
buses.
More significantly, perhaps,
the US company claims the NuVinci arrangement can be “manufactured at low cost
globally with standard industrial materials and processes, and has been
commercialised.”
It will be interesting to
see how this development matures; and if the claims can be achieved.
As far back as 1981, Peter
Stubbs of BL Technology Ltd, part of British Leyland in the UK and based at Gaydon, produced a technical
paper for the American Society of Mechanical Engineers (ASME) on the
development of the Perbury traction transmission for cars.
Even at that point, work
had been under way for over a decade in developing the Perbury transmission. One
system was installed in a Hillman Minx passenger car. So, a great deal of
development work has been acquired by various sources, most notably Torotrak
plc. It is understood that even now, development of the Perbury system is by no
means dead.
If there is one thing that
can be said about CVTs and IVTs, both technologies have found many large
companies wanting in their attempts to ‘crack’ the problems, including Ford
Motor Company and General Motors.
The link between Fallbrook
Technologies Inc. and Allison Transmissions and the more mature link between
Torotrak plc and Allison Transmissions implies there could be a transfer of highly complex technical information from
one source to another.
Among the areas of technology
most likely to be affected by such information flow are: traction fluid
dynamics, traction fluid composition, surface friction characteristics, internal
system forces, computerised transmission control, the effect of computer
control on transmission instability, materials selection for balls and rings,
and the required level of machining tolerances required to achieve the extended
levels of durability demanded by modern vehicle use.
Fallbrook Technologies Inc.
claims that “various problems, such as cost, scalability, efficiency and weight
have kept CVTs from widespread adoption and limited their practical
applications.”
This statement might be
seen by some to imply that Fallbrook Technologies Inc. of Cedar Park, Texas, has
solved all these relevant ‘problem’ areas and produced the ideal solution for a
wide range of applications.
No doubt the introduction
of the new Dana Technology Centre will go some way in helping to further
develop and iron out any faults the NuVinci traction drive transmission might
have.
Fallbrook Technologies Inc.
had not replied to our request for further information at the time of publication.
No comments:
Post a Comment