Continuous Variable Transmission Case Study of All Terrain Vehicle

1. C V T
Continuously
variable
transmission GROUP MEMBERS:
1. Mayur Shinde(04)
2. Shantanu Shelke(05)
3.Omkar Karande(06)
4. Jayprakash Umap(11)
5. Satyam Tripathi(41)
CASE STUDY ON :
Submitted to:
Prof. V. P. Kulkarni Prof. Bhavana M. M.

2. 1. BASICS OF TRANSMISSION
2. INTRODUCTION
3. WHAT IS CONTINUOUSLY VARIABLE
TRANSMISSION (CVT)
4. HISTORY OF CVT
5. CVT COMPONENTS & DESIGN
6. WHY USE CVT…..? APPLICATIONS
ADVANTAGES DISADVANTAGES FUTURE SCOPE
CONCLUSION REFERENCES
CONTENTS
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3. INTRODUCTION
• CVT allows for the operation at the lowest possible speed and
highest possible load, partially avoiding the low efficiency region
of the engine map.
• A continuously variable transmission (CVT) transfers power
through a range of speed/torque ratios from engine input to output,
continuously without interruption
• Contrast with either manual or conventional automatic
transmissions that use discrete ratios and normally disengage when
changing ratio
• The CVT category includes infinitely variable transmissions (IVT)
that give a zero output speed within the operating range

4. BASICS OF TRANSMISSION
4
The job of the transmission is to change the speed ratio
between the engine and the wheels of an automobile.
The transmission uses a range of gears -- from low to high --
to make more effective use of the engine's torque as driving
conditions change. The gears can be engaged manually or
automatically.

5. A continuously variable
transmission -CVT,
(also known as single-speed
transmission, gearless
transmission, one-speed
automatic, variable pulley
transmission, or in case of
motorcycles, a twist-and-go) is
a transmission that can
change seamlessly through an
infinite number of effective
gear ratios between
maximum and minimum
values.
WHAT IS CONTINUOUSLY
VARIABLE TRANSMISSION (CVT)
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6. Leonardo da Vinci sketches is the basis for the first
continuously variable transmission in 1490.
First patent for the CVT Transmission was made by Daimler
&
Benz in 1886.
The first workable belt driven CVT was designed and built
by the Dutchman Huub van Doorne in 1958.
In Early 1990's Nissan introduced CVT in their Nissan March
2004 - Ford begins offering a CVT .
HISTORY OF CVT
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7. AUSTIN 18. USED A
CVT
1937
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11. CVT COMPONENTS
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MOTOR
BEARING
SHAFT
THREADING NUT
& BOLT
CHAIN DRIVE
BODY FRAME

12. In this most common CVT system , there are two V-
belt pulleys that are split perpendicular to their axes
of rotation, with a V-belt running between them.
1. PU LLY BASED CVT ’S
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13. 2. BELT DESIGN
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14. Toroidal CVTs are made up of discs and rollers that
transmit power between the discs.
3. TOROIDAL CVT ’S
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15. Hydrostatic transmissions use a variable displacement
pump and a hydraulic motor. All power is
transmitted by hydraulic fluid.
4. HYDR OSTATIC CVT’S
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16. A subset of CVT designs are called infinitely
variable transmissions (IVT or IVTs)
5. INFINITELY VARIABLE
TRANSMISSION (IVT)
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17. A cone CVT varies the effective gear ratio using one or
more conical rollers.
6.CONE CVT
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18. VEHICLE
LAYOUT
b - Input disc
c - Output disc

19. 19
0-100
Km/h
• 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.
CVT MT
8.8 sec. 11.9 sec.

20. SPECIFICATIONS
CVT (Continuously Variable Transmission):
Manufacturer: Gaged Engineering
Centre to Centre Distance: 215mm (recommended)
Gaged CVT GX9: Low Ratio: 0.9
High Ratio: 3.9
CVT Selection:
Primary Pulley: Secondary Pulley:
Diameter: 152.4 mm Diameter: 203.2 mm
FlyWeights:64gm
Torque Ramp Angle: 32-24
Cam Angle: 10-13

21. Belt:
Material: Kevlar Fiber Wedge angle: 28o
Overall Shift Ratio: 4.33
Gaged CVT GX9 Polaris P90 CVTech
Ratio 0.9 3.9 0.7 3.8 0.4 3.1
Weight 5.8 kg 10.11 kg 9 kg
Tuning Options High Low Low
Serviceability Easy Moderate Low

22. CALCULATIONS:
Maximum Resistance:
Rolling Resistance = µmg
= 0.3*9.81*210
= 618.03 N
Air Drag = ½*Cd*A*ρ*V^2
= ½* 0.23*0.838*1.225*229.129
= 27.05 N
Gradient Resistance = mg*sinϴ
= 210*9.81*sin (35)
= 1181.625 N
Total Resistance = Rolling Resistance + Air drag + Gradient Resistance
= 618.03 + 27.05 + 1181.625
= 1826.704 N

23. Radius = 0.2921 m (23” x 7” x 10” in)
Torque = Total Resistance * Radius
= 1826.704 * 0.2921
= 533.739 Nm
The above obtained value is for maximum resistance on loose sand. Hence, the torque
obtained from the above value will be the maximum torque. But in practical
that value is never achieved. Hence, we choose a value (for torque) that nearest to
the above calculated value.
Calculated Gearbox Reduction = 7.36

24. Speed and Acceleration:
Speed = [RPM (engine) * CVT Ratio * Gearbox Reduction] * (2π/60) * Radius
= [3600 * 0.9 * 7.36] * (2π/60) * 0.2921
= 16.60 m/s
= 59.85 km/hr
Acceleration = (Tractive Force-Resistances) / m
= (1798.915 – 645.625) / 210
= 5.49 m/s2

25. Total Tractive Force = T*G /R
Where , T = Torque
G = Gear Ratio
R = Radius
Total Tractive Force = (18.3 * 7.36 *3.9) /0.292
= 1798.9150 N
Maximum Torque = 525.28 Nm
Final Torque at the wheel = 420.22 Nm
Sledge Pull: (Weight of Sledge = 1500 kg)
Rolling Resistance = µmg
= 0.08 * 1710 * 9.81
= 1342

26. Gradeability:
M*a = Tractive Force – (Rolling Resistance + Air Resistance) – Gradient
Resistance = 1974.896 – (618.03 + 27.595) 210*9.81*sinϴ
= 40.184ϴ
Gradeability = tan *100ϴ
= tan (40.184) * 100
= 84.46%

27. HOW CVT WORKS

30. APPLICATIONS :
1.Tractors Golf Carts
2.Ride on Lawn
3.Mowers Motorized
4.Wheelchairs Bicycles
5.Power tools
6.Industrial Equipment
7.Minimachines

31. 1. There is improved acceleration due to the lower power loss
experienced.
2. Step less transmission. Delivers maximum torque.
3. Provides a smoother ride than automatic transmission.
4. Adapts to varying road conditions and power demands to
allows for a better ride.
5. This improves fuel economy and reduce exhaust emissions.
6. There are 25% fewer moving parts to a CVT transmission
ADVANTAGES
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32. 1. Higher cost.
2. Belt-driven CVTs (VDP system) have a limited amount of
torque. Transmitting motion by friction causes greater wear.
3. Require special oil and other materials.
4. Becomes Jerky in automobile applications at slow speeds.
5. New technology so there are limited people that
understand the operations with in a CVT.
DISADVANTAGES
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33. FUTURE SCOPE
1. CVTcan be improved with research on the belt design
2. permitting use in high performance vehicles.
3. Hybrid vehicles will also feature with this type of transmission
4. Electric motors can avoid the low speed/ high torque problems often associated
with CVTs, through an innovative double-motor system.
5. Kia recently tested a system where the CVT allows the engine to run at
constant speed and the motor allows the engine to run at constant torque
independent of driving conditions.
6. In the future a major amount of cars will feature CVT .

34. 1. Today, only a handful of cars worldwide make use of CVTs,
but the applications and benefits of continuously variable
transmissions can only increase based on today’s research and
development.
2. As automakers continue to develop CVTs, more and more
vehicle lines will begin to use them. As development
continues, fuel efficiency and performance benefits will
inevitably increase; this will lead to increased sales of CVT-
equipped vehicles.
3. Increased sales will prompt further development and
implementation, and the cycle will repeat ad infinitum.
CONCLUSION
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35. 1. www.google.com www.wikipedia.com
www.studymafia.org
http://www.synchrotronic.com
2. http://auto.howstuffworks.com/cvt.htm
3. www.autos.aol.com
https://www.subaru.com/engineering/transmission.
html
REFERENCES
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