A presentation on project on Continuous Variable Transmission.

1. Harshal Patil T-31
Pooja Patil T-33
Vijay Patil T-34
Priyanka Salve T-43
Third Year, Mechanical Engineering Dept

2. Overview of a CVT:
 Varies the transmission ratio continuously
 Shifts automatically with an infinite number of
ratios.
 Seamless power delivery
 Constantly changes its gear ratio to optimize
engine efficiency
 Allows the engine to rev almost immediately to
deliver maximum torque

3. Main types of CVT’s:
Metal Push Belt CVT
Toroidal Drive CVT
Cone CVT

4. History of CVT’S:
 1490: Leonardo da Vinci drew sketches of his
ideas for a CVT.
 1886:The first CVT was built by Daimler and
Benz.
 1930’s: GM developed a toroidal CVT.
 1958: Daf (Netherlands) developed and
produced a belt driven CVT for a 0.6L
engine.

5. Austin 18 Used a CVT
1934

6. The good and the bad of CVT’s:
 ADVANTAGES
 Decreases engine fatigue
 Allows for an “infinite” number
of gear ratios, maintaining the
engine in its optimum power
range
 More mechanically efficient
than Automatic transmissions.
 Greater fuel efficiency than
both manual and automatic
transmissions.(Fuel savings of
more than 17% have been
achieved)
 Cheaper and lighter than
Automatic trans.
 Smooth, responsive and quiet
to drive.
 DISADVANTAGES
 Limited torque capacity when
compared with manual
transmissions.
 Larger and more costly than
manual transmissions.
 Slipping in the drive belt or
pulleys.(NO LONGER AN ISSUE
DUE TO NEW ADVANCES).
 The automobile industry is
unwilling to discard billions of
dollars already invested in
development of MT & AT’s.

7. Metal Push Belt CVT:
 Uses a pair of axially adjustable sets
of pulley halves(Variators)
 Both pulleys have one fixed and one
adjustable pulley halve.
 The transmission ratio is varied by
adjusting the spacing between the
pulleys in line with the
circumference of the tapered pulley
halves.
 A “belt” is used to transfers the
engine's power from one shaft to
another.
 The variators are adjusted
hydraulically.

8. Push Belt CVT Illustrations:

9. Variator
The variator is a disc
containing weighted rollers
disposed radially in a cage
and fixed to the sliding front
pulley.
As it spins faster, the
weights climb ramps, forcing
the front pulley halves
together, and raising the
effective gearing.

10. Centrifugal Clutch
It operates in much the same
way as the variator, being of a
centrifugal design.
As you twist the throttle, the
engine increases its speed and
the belt drive spins the clutch.
As the rotational speed
increases, centrifugal force
causes the clutch inner to expand,
and begin driving the clutch outer,
which is connected to the rear
wheel.

11. CVT Schematic :Belt Drive

12. Van Doorne Steel Belt (1):
oAlmost all of today’s
belt driven CVT’s use
this design invented by
Dutch CVT specialist
Van Doorne.
o Maximum torque it
can withstand is
around 150 lb-ft
(190hp).
Used in:
• Honda Civic HX
• Nissan Primera
• Toyota Prius
• Honda Insight
• BMW Minicooper

13. Van Doorne Steel Belt (2):
Assembled/Disassembled

14. CVT Vs. Manual Transmission
Theoretical comparison under “ideal” conditions.
 The Continuously Variable
Transmission (CVT)
proved 35% more
efficient than the Manual
Transmission (MT).
 With same car and engine,
the CVT takes only 75% of
the time to accelerate to
100km/h, compared to
the MT.
1991 FIAT UNO: M=1250kg
Torque=101.2 N-m
n=5700rpm
CVT MT
8.8 sec. 11.9 sec.
0-100 km/h

15. CVT Simulation:
 Audi A6 Multitronic
Audi A6 3.0 L
0-100 kmph Mileage
A6 5-speed manual 8.2 sec
9.9 litre/
100km
A6 5-speed Tiptronic 9.4 sec
10.6 litre/
100km
A6 Multitronic CVT 8.1 sec
9.7 litre/
100km

16. Our Model
(CATIA Model)

17. Component used
 2- Conical pulleys
 12V Gear motor
 12V DC Battery
 Copper Wires and Switch
 Threading nut and bolt
 Wooden body frame
 Rubber belt(flat belt)

18. Calculations:
 Motor RPM, N=110 rpm, D2=10 cm, D1= 5 cm
 1st gear Ratio obtained, G1= D2/D1
= 2
 Final gear Ratio obtained, Gf= D1/D2
= 0.5
Therefore,
 Output speed at start, N1= N/G1
= 55 rpm
 Output speed at end, N2= N/Gf
= 220 rpm

19. Future of CVT’s:
 The internal combustion (IC) engine is nearing both perfection
and obsolescence; advancements in fuel economy and emissions
have effectively stalled.
 CVTs could potentially allow IC vehicles to meet the first wave of
new fuel regulations
 As CVT development continues, costs will be reduced further
and performance will continue to increase.
 This cycle of improvement will ultimately give CVTs a solid
foundation in the world’s automotive infrastructure.