This seminar report describes the working of an Infinitely Variable Transmission (IVT).

1. SEMINAR REPORT
ON
“Study of Infinitely
Variable Transmission”
Submitted by:
Moanungsang Jamir
S7M1 Roll No:67
1

2. CONTENTS
 Introduction
 What is CVT?
 Infinitely Variable Transmission(IVT)
 Study of Infinitely Variable Transmission
 Conclusion
 Advantages of IVT
 Drawbacks of IVT
 Applications of IVT
 References

3.  INTRODUCTION
 There are different types of transmission systems
◦ Manual transmission
◦ Automatic transmission
◦ Continuously variable transmission
 IVT is a subset of Continuously Variable Transmission(CVT).
 The IVT dates back to before the 1930s.

4. Continuously variable transmission
system
 This unique transmission does not have several
set of gears like most transmissions, but rather
have an infinite number of gear ratios.
 CVT does not strictly require the presence of a
clutch, allowing the dismissal thereof.
 Seamless acceleration with a “direct” drive feel
for enhanced driving pleasure.
 With fewer moving parts, CVT is simpler than AT
in principle.
 CVT is emerging as a keystone technology that
enables other innovations.

5. Working
 On low gear
situation the radius
of drive pulley is
smaller than the
driven pulley.
 In low gear
situation the Torque
is high while the
RPMs of driven
pulley are low.

6.  On high gear situation the
radius of drive pulley is
larger than the driven
pulley.
 In high gear situation the
Torque is low while the
RPMs of driven pulley are
high.

7. CROSS SECTION OF THE BELT

8. How do sheave move?

9. INFINITELY VARIABLE TRANSMISSION
 A specific type of Continuously Variable
Transmission(CVT).
 The range of ratios of outer shaft speed to inner
shaft speed includes a zero output speed.
 It can be continuously approached from a
definite higher ratio.
 It consists of a combination of Planetary Gear
System(PGS) and CVT.
 The CVT acts as a Continuously Variable
Regulator or Variator.

10. KEY ELEMENTS OF IVT
 The Input Gear set: It transmits power from the engine to
the Planetary Gear Set and the Variator.
 The Variator: It is a means by which the IVT can deliver an
infinite range of ratios. It affects the speed of rotation of
sun gears and smooth variation of ratios.
 The Planetary Gear set: The central gear (sun gear) is
driven by fixed engine rpm

11. Input Gear Set
 The input gear set splits the input power
from the engine to the Planetary Gear set
and the Variator
 It can consists of either belt or gear.

12. Variator
 The Variator is the heart of the IVT and is the means by
which the IVT can deliver an infinite range of ratios.
 It can be explained as
◦ Toroidal CVT
 For this type a belt drive because the toroidal CVT itself will
reverse the direction.
 This kind of CVT is called Toro Trak IVT.

13.  Planetary Gear Set
• A gear set in which all of
the gears are in one plane,
grouped around each other
like the planets around the
sun.
• The central gear is called
the "sun gear". In mesh
with it is a circular grouping
of gears, called "planet
gears", mounted on a
rotating carrier.
• The planet gears also
engage teeth on the inner
periphery of the "ring
gear".
• By holding any one of the
three gear elements
motionless, different ratios
can be produced between
the other two. Planetary
gear sets are common in
automatic transmissions

14. Toroidal CVT
 The toroidal CVT is at the heart of the IVT
 It consists of two toroidal shaped input discs and a toroidal
output disc in the middle.
 Roller discs are connected in between the input and output discs.
The roller discs are in contact with the disc by special oil called
traction fluid.

16. Working
 The gear ratio can be varied
by changing angle of
inclination of roller discs.
 Case 1.
◦ Roller disc connected to
lower radial position of input
and higher radial positon of
output disc
◦ This is similar to a smaller
gear coupled to a bigger
gear through an idler
◦ So higher gear ratio is
obtained
◦ Gear ratio=R2/R1
R2R1

17. • Case 2.
• Roller disc connected to
higher radial position of
input and lower radial
positon of output disc.
• This is similar to a bigger
gear coupled to a smaller
gear through an idler
• So lower gear ratio is
obtained
• By varying the angle of
inclination of the roller discs,
any gear ratio in between
these two can be obtained
• The input and output shafts
will be rotating in opposite
direction because of the idler.

18. Toro Trak IVT
 Toro Trak IVT consists of
Toroidal CVT and a
Planetary Gear set.
 The input from engine is
connected to the ring gear
of the planetary gear
system.
 The input is also connected
to the toroidal CVT.
 Output of toroidal CVT is
connected to the sun gear
of planetary gear system.
 The output is taken from
the planet carrier.

19.  Working
◦ Case 1.
 Suppose the gear ratio
of CVT is 1:1,both the
sun gear and ring gear
will rotate in the same
speed but in opposite
direction. Then the
planetary carrier will
remain stationary.
 Hence the output speed
will be zero and output
torque will be high.
𝝎 𝟏
𝝎 𝟐
𝝎 𝟐 = 𝝎 𝟏
𝝎 𝟐
𝝎 𝟏

20. ◦ Case 2.
 When the gear ratio of
CVT is greater than 1,then
the sun gear will rotate at
a lower speed than the
ring gear but in opposite
direction.
 Hence there will be net
output speed i.e the
planet carrier will rotate at
a direction of ring gear
with a velocity
◦ 𝜔 𝑑 =
𝜔1(𝑟1− 𝑟2 𝐺)
𝑟1+𝑟2
 The output will be in
opposite direction of input
 Output speed can be
varied by changing the
gear ratio of CVT.
𝝎 𝟏
𝝎 𝟐
𝝎 𝟐 < 𝝎 𝟏

21.  Case 3
 When the gear ratio of CVT
is less than 1,then the sun
gear will rotate at a higher
speed than the ring gear
but in opposite direction.
 Hence there will be net
output speed i.e the planet
carrier will rotate at a
direction of sun gear with a
velocity
◦ 𝜔 𝑑 =
𝜔1( 𝑟2 𝐺−𝑟1)
𝑟1+𝑟2
 The output will be in
opposite direction of input
 Output speed can be varied
by changing the gear ratio
of CVT. 𝝎 𝟐 > 𝝎 𝟏
𝝎 𝟐
𝝎 𝟏
𝝎 𝟐
𝝎 𝟏

23. Conclusion
 This is show the time period for which engine runs at optimum speed for
a Manual Transmission and an Infinitely Variable Transmission.
 Initially increase in speed is due to change of engine speed only then once
engine reaches optimum speed gear ratios change to give increase in
velocity while engine constantly runs at optimum speed.

25. Advantages of IVT
 IVT is a positive drive system and thus no frictional and slip
losses occurs.
 It can run the engine at optimum conditions at all times for
fuel economy and emissions.
 As planetary gear system is used in IVT, engine is in
continuous contact with gear even at zero output thus
eliminating wastage of fuel during shifting of gears as in
manual transmission.
 IVT provides a better acceleration due to change of gear ratio
rather than fixed ratio in Manual Transmission.
 IVT provides a quieter and smoother operation as compared
to conventional drives.
 IVT has 50% lesser number of components than other
transmission so reducing maintenance.

26. Drawbacks of IVT
 Many drivers believe that they feel
unnatural because the IVTs lack the shift
feel.
 A slight misalignment causes a large
amount of stress on gear train which
reduces the service life of the system.
 Only finite number of gear ratios are
obtained.

27. Applications of IVT
 Toro Trak Full toroidal Variator is used in a
concept car called ‘PIXEL’ developed by TATA and
inspired from NANO.
 IVT has been used in earth movers and Farm movers

28. References
 Zero-Max Adjustable speed.
 Dr Ben McCarty, Report on ENGINEERING
ASSESSMENT OF IVT CONCEPT,
 Terry Lester, ”Solving the Gearbox Reliability
Problem ”, LESTRAN ENGINEERING.
 Case study of TOYOTA Prius Hybrid Synergy
Drive, www.toyotacars.com
 Gilmore, D.B., (1988) Fuel economy goals for
future powertrain and engine options.
International Journal of Vehicle Design, Vol. 9,
no. 6, pp. 616-631. UK.
 Bosch (2004) Bosch Automotive Handbook, 6th
ed., Plochingen, Germany.
 Theory of Machines by RS Khurmi

29. THANK YOU