Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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TATRAN
TRANSVERSE
AUTOMATIC TRANSMISSION
INTENDED FOR 4, or 6 SPEED
AUTOMATIC, or
CVT TRANSMISSIONS
February 24, 2004
Nicholas lVt. Ottly
7 Aylesbury Rr.
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CA 02458368 2004-02-25
TATItAN
INTRODUCTION
Automotive history teaches us, that virtually all motor cars produced since
their inception
in the 19th century, transmit the engine's power to the wheels in the same
sequence:
the power generated by the motor goes first to a torque converter, (or lately
to a spool
of a CVT) and then to the gearbox. From there, it travels to the "final
drive", or
differential, where a speed reduction, consisting of a pinion and crown gear
takes place.
Only now will the driving wheels turn at the desired road speed.
Attain Technology advocates significant changes to the above sequence and in
the re-
distribution of power within the power train served by automatic transmissions
and
CVT's.
What Is "Tatran" - And How Dmes It Work?
The name Tatran is an abbreviation for a Transyerse A,utomatie Transmission',
because the proposed device is located transversely in the chassis, connecting
two wheels
of the same axle. It can be used in FWD, RWD, as well as in AWD
configurations.
Tatran brings with it three sign cant innovations: 1. a change to the sequence
in which
the engine power is transmitted to the wheels, 2. "speed reduction at source"
and 3. the
eliminations of the final drive - or differential housing - in all automatic
transmissions.
The power from the engine goes first to a speed-reduction gear set, and then
to an
automatic transmission. from where it is directly applied. to the wheels.
Consequently,
there is both a change in the seguence in which the power is applied - as well
as a
speed reduction at the source,.
Apart from the two above changes, whose main purpose is to save the
transmissions
from unnecessary strain and to extend its service life- the third objective is
to
completely eliminate the differential assembly. its gears, and the housing -
with the
final drive - while retaining all the functional features of a "differential",
so
essential in the safe operation of a modern vehicle.
Therefore. TATRAN is suited for all passenger, SUVss light trucks, or similar
all-
terrain- vehicles, using the current automatic transmissions as well as new
CVT
gearboxes.
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In addition to that, TATRAhI's innovations are emine~ntly suited for today's
hi~h-
nerformance autos on account of the ever-increasing horsepower and torque. -
Their
augmented rower and revolutions are first reduced in RPM's before they are
applied to the transmission, and then split into two, evenly divided ener~y
streams
- left and right sides of the TATRAN transmission, thus greatly extending the
life of
the power train.
*****
CONTINUOUSLY VARIABLE TRANSMISSIONS - or CVT
At present, the popularity of the CVT is on the increase; some automobiles, or
SUV's
offer them as an option, such as GM's Saturn, Honda, Toyota and Audi, etc.,
while
Nissan's SUV, the Murano, comes only with a CVT transmission. Since the CVT is
relatively, new some details are included.
Essentially it consists of two spools, about 10 to 14, incl-~es apart; which
are connected
by a special belt, but held apart by supporting columns - as shown in Figure
OI. The
internal mechanisms of the shaft mounted pools can change their diameters
simultaneously. While the diameter of one spool increases - the diameter of
the opposite
spool decreases, and vice versa. The driving spool is driven by the engine,
while the
driven spool connects to the final drive, the differential housing - and then
the wheels.
In all the current CVT's there is only one belt and two ;stools.. Attain
Technology Inc.
advocates changes to this set up - which is detailed below. Please see
illustrations of
CVT transmissions on Figure 01 and Figure 02. .
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A. TATRAN & C'VT
GENERAL DESCRIPTION
In a FWD Vehicle the front of a longitudinally placedl engine terminates in a
small
flywheel, a fluid coupling and a supported worm-gear, vvhich drives a matching
worm
wheel above it at a ratio of around 1:4 The assembly at the flywheel also has
a
provision for a reverse gear
The large worm-wheel is integral, or fastened to 2 two) driving spools of the
CVT,
supported by side beams which provide the driving cones and spools with
stability
and room to move sideways. It also allows them to keep the same distance from
the
driven spools above, connected by the driving chains. Located in the center of
the
same shaft, the engine driven worm-wheel turns at exactly the same speed as
the
driving spools.
Positioned ahead of the two (left & riQ;ht drivin spools are the two
corresponding
~r~ven spools. Tosether with the belts and their cone-sliding mechanisms -
they
constitute the entire CVT Transmission.
Each driven spool leads first into a wheel hub with water-cooled (~tiona~ -
inboard
disc brakes - and then to an internal U joint - a half-shaft, and a wheel. The
same
assembly on the other side - c~nstitutes a complete Front iWheel give Train.
Since the driven spools are not in-line with the en~ine''s crankshaft - the
TATRAN-
CVT transmission cannot use the "lock-out" feature in which all the years and
hydraulics are bypassed. FIowever, this is also one of tlhe great advantages
of this new
CVT!
The above TATRAN-CVT application can be easily duplicated in a Rear Wheel
Drive
vehicle, or in AWD 4x4 SUV.
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FIGURE S
FIGURE 10
TATRAN - CVT - TOP VIEW
1. a longitudinally placed engine has an extension to its crankshaft that
supports a
worm-gear, that engages a suitable worm wheel. The ratio of the worm gear and
wheel is about 4: I, but it may vary Behind the worm gear is a starting
clutch, a
provision for reverse rotation and a fluid coupling
2. the large worm wheel is on the same axis as the h~o driving spools are
attached
to it, one for the left. The other for the right wheel. They are solidly
connected to
the main shat and contain mechanisms that expand and contract their diameters
3. placed some 10 to 14 inches ahead but mounted separately are the left-and-
right
driven spools; these are then connected to the driving spools through the two
chains, and supported by the sides of the transmission box. The driven spools
meet in the center of the CVT but are allowed to rotate at different speeds
from
each other; while the spools are allowed to contract &. expand, their centers
are
firmly attached to their shafts in order transmit their rotation
4. the shafts of the left and right spools extend further out - first, they
form bearings
for the internally mounted disc brakes - and reaching out they form wheel hubs
that support internal a joints of the axle's half shafts
5. since the axles - or the pair of driven wheels - has two belts each wheel
can
be driven at different velocities which will come into play when the vehicle
negotiates a turn. - The computerized CVT control will have two modules: one
for the left and one for the right wheel. - The inputs will come from the ABS
wheel-rev counter, vehicle speed, lateral C~-forces - and other factors -
currently
available in most vehicles
6. transmission-case, enclosing all Tatran-CVT components. Please note, that
there
is no differential casing, nor a 'final drive' - this is all that is needed.
FIGURE 11
TATRAN - CVT - SIDE VIEW
1. Engine - FWD, or AWD
2. crank-case of engine with: small fluid coupling, clutch, provision for
reverse gear
and "nose", to support the bearing of the worm-gear
3. worm-gear engaging worm-wheel (above) - with front bearing support
4. worm-wheel, reducing engine's RPM to about 30% to 25%
5. one of the two driving spools (left and right)
6. one of the two driven spools
7. one of the two 'driving belts"
8. transmission case
9. disc brake of the front wheel
10. front wheel
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SUMMARY OF BENEFITS REALIZED
THROUGH THE APPLICATION
OF TATRAN-CVT
With the Speed reduction At Source the CVT traalsmission rotates only at about
25% of the original engine speed - prolonging i:he life of the With the
'split'
CVT function - torque applied equally to each wheel - and yet each wheel will
be
independent. The current maximum torque ratings for the belts - by various
manufacturers in 2004 are about 250 to 300 lbs. Two belts - rather than one,
will
increase the torque rating substantially, if not doubling it
~ During turns, Tatran-CVT's will take care of the speed differences through
an
algorithm based on: 1 ) the position of the steering wheel - or the front
wheels
proper, 2) by vehicle speed, brake application, if any, 4) slippage, and so
on. -
These calculations are routinely executed today ~by ABS, stabilitr~ and
traction
controls - mostly with the help of brake application, rather than the 'limited
slip'
differentials.
THE RESULTS
The TATRAN-CVT transmission will also deliver increased life ex ep CtanCy and
reliability While the original CVT carried the entire load with one sin lg a
belt, the
TATRAN - CVT transmission will run about 75% slower and will share the
power load with two belts.
In the TATRAN-CVT application - the differential housing, its gears. etc. are
completely eliminated, which in spite of a dual-type gearbox with two belts
will
result in a much lighter vehicle that is more economical to produce. The
weight savings
in a passenger - or SUV vehicle - could range from 7S to 125 lbs. and would
senerate
substantial savinES in the production.
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B. TATRAN - WITI~ A 4 &, 6 SPEED
AUTOMATIC TRANSMISSION
GENERAL DESCRIPTION
The application potential of a TATRAN Transmission - v~rith a 4, or 6 speed
gear-box is
similar to the CVT's which is, almost universal. It can used in FWD, or RWD
vehicles
and the engine, power can be transmitted to it by gears ~- or by chains, or a
long shaft.
Engines can be placed longitudinally - or laterally, as per present practice. -
For the sake
of simplicity, a FWD installation using gears, or a chain, will be used to
describe its
functioning below. - Further explanations accompany the Figures.
The prime example introduced below uses a north-south positioned engine of a
FWD
vehicle; placed behind the front axle - and slightly off center. The front of
the
crankcase with its flywheel, has a fluid coupling with a 2-speed reduction
gear set and a
provision for a reverse gear.
The functioning of the TATRAN' transmission with a Gearbox is as follow:
~ Outside of the crankcase is the main power transmission gear set (or
chains),
consisting of a small diameter pinion gear - and engaging
~ the large crown gear at 90°. The outside gears remain. in permanent
contact and
their ratio doesn't change, while the internal speed reduction set is used to
switch
during the gear selection. It is understood, that these two gear sets will
have to
"harmonized" together to achieve balanced results.
The large "crown gear" is flanked by two smaller diameters torque converters -
and on the outside of these - by two set of gear boxes; if the transmission
calls for
4 speeds, then each gear box will have only 2 gears; on the other hand if it
has 6 -
then 3 speeds will be needed
~ TATRAN uses the centrally located 2-speed gear set as a pre-selection
device, so
that the 2,m or 3 gears are multiplied - so they become 4, or 6 but going to
the left
and right sides of the vehicle. The computerized transmission module will
simultaneously shift the gears in both the sides
~ TATRAN encloses/supports two half shafts, for tine left and right wheels;
they
terminate in its center - but are not connected, so they can rotate at
different
speeds; each half shaft extends to an inboard disc-brake, then a a joint to
form a
complete axle.
Since there is no "direct drive" in the TATRAN - all gear ratios are indirect
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~ As each wheel is driven through a separate torque converter. Full power is
applied
to each wheel at all times, which means, that in turns in wheel will be able
to
rotate at different speeds - but with a full power application
FIGURE 20
TATRAN - AUTOMAT_I(:
~4, or 6 Speeds - Gear Drive)
TOP VIEW
1. The front of the engine
2. Fluid coupling with a reduction gear - which multiplies the ratios in the
main
gearboxes and a provision for reverse rotation
3. Small pinion gear - drives the TATRAN transmission
4. Large gear, acts as a speed reduction gear - and is installed between the
left and
right converters
5. & 5 - left and right converters - with impellers mounted back-to-back(and
supplemented with stators, turbines, clutches, etc - which are not shown)
6. & 6 - right and left gear boxes - each with 3 gears - shifting
simultaneously on
both sides of the TATRAN
7. Two outside bearings and partitions supporting the gearbox, torque
converter and
the half shaft; the same is repeated on the opposite side, for a total of 4
8. Two inside bearings and main partitions of TATRAN, with the left and right
bearings, supporting the torque converters and the main driving wheel. In
total,
there are 6 (six) supporting partitions with bearings.
9. Left half axle, terminating in the center - and exiting the transmission
case
for mounting of the inboards disc-brakes and a joints
10. Right half axle going in the opposite direction - but completely
'independent of
the left half axle
Note: this figure shows a dual 3 + 3 speed gearbox; should only 4 speed by
needed, this
will require only 2 + 2 speeds which will make the gearbox shorter and the
whole
transmission narrower.
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FIGURE 21
TATRAN - AUTOMATIC
(4, OR 6 Gears - Chain Drive)
FRONT VIEW
This Figure shows also a 4 , or 6 gear TATRAN Automatic gearbox but the power
transmitted from the engine is accomplished by a chain - and the engine is
parallel to the
front axle, as it is quite common in today's vehicles. The size of the main
power
transmission gear can also be easily adjusted to the requirements on hand.
1. the central speed reduction wheel, driven by a chain - engine's driving is
not
shown. The wheel is attached to both the right and left converters
2. two central bearings - only the left one is shown
3. outside housing of the left torque converter
4. internal components of the left torque converter. It shows, how its front
forms
the left central TATRA,N bearing supporting the Left half shaft, and part of
the
entire assembly
5. left half shaft
6. right half shaft - each of them can turn at different speeds in turns, as
they are
driven by two separate torque converters
FIGURE 22
TATRAN - AUTOMATIC
~,4, or 6 Gears - Chain, or Gear Drive)
FRONT VIEW
This figure shows the TATRAN Automatic, with 4 or 6 speeds, that could be
driven
either by a chain - or gears. If used in FWD vehicle, the engine would like be
parallel to
the transmission.
Of note is a massive, central. single cross-shaft that extends almost across
75% of the
entire width of the transmission and acts as structural component. for the
entire TATRAN
assembly The "cross-shaft" could likely be either cast, or machined from a
single piece
of steel; its center supports the large reduction wheel, which is flanked by
two, back-to-
back impellers of the torque-converter.. These act a stabilizer, adding
further rigidity to
this central component.
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1. center reduction wheel and chain, leading to the engine
2. the left side of the torque-converter exposes the shape of the left
impeller that
strengthens the shaft
3. right-hand half of the central shaft - illustrates the support of the
impeller, and
shows the length of the shaft, which extends all the way to the center
supports of
TATRAN
4. outside case of TATRAN
5. left-hand side of the "center support", showing the vertical wall with a
bearing
that supports the left turbine and the entire torque-converter assembly
6. left-hand side of the vertical wall that goes down to meet the tubular
extension of
the turbine and the solid end of the central shaft; it forms a three-in-one
bearing
7. the right-hand support wall of TATRAN - duplicating the left one
8. & 8 the left and right gearboxes, enclosing the clutches and 3 forward
gears ,
transmitting the power to the wheels
9. & 9 - right-and-left half shafts, inserted into the central cross shaft -
where they
rotate freely. The power to the half shafts is delivered through the gearboxes
in 8.
THE RESULTS
By-and-large, in general terms, the TATRAN-Automatic transmissions meet the
objectives staked out by Attain Technology: the delivered designs are
substantially
smaller, lighter and I will save the producer a great deal of money. The only
features
missing are 1 ) a direct drive, which locks all hydraulics from the power
train and 2 a
limited-slip differential. However, the latter one is being more-and-more
replaced by
stability and traction control features, which rely guite heavily on vehicle's
dynamic
sensors and a momentary application of brakes.
SUMMARY
Even before the turn of the millennium the automatic transmissions were
subjected to
new pressures - and called to overcome a variety of new challenges. Namely:
1. the units should be smaller and lighter - and work well in confined spaces
2. they should be produced at lower costs
3. they should be able to sustain an ever- higher BHP and torque
4. they should work well - with no maintenance- for at least 150,000 km, or
longer.
Vis-a-vis all these big challenges, Attain Technolo~v Inc. has developed the
TATRAN
transmissions, suited for the new CVT's and gear-type automatics -capable to
reduce
engine revolutions before they enter into the transmission - and then re-
distributing
them to the left-and-right driying heels, so that its life-expectancy is
~reatly
increased. On top of that, the heave differential with its final drive has
been
eliminated and replaced with new components uerformin~ the same function.
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