cvt mini project presentation
Post on 12-Sep-2014
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A presentation on project on Continuous Variable Transmission.TRANSCRIPT
Harshal Patil T-31Pooja Patil T-33Vijay Patil T-34Priyanka SalveT-43
Third Year, Mechanical Engineering Dept
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
Main types of CVT’s:
Metal Push Belt CVT
Toroidal Drive CVT
Cone CVT
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.
Austin 18 Used a CVT1934
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.
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.
Push Belt CVT Illustrations:
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.
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.
CVT Schematic :Belt Drive
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
Van Doorne Steel Belt (2):Assembled/Disassembled
CVT Vs. Manual TransmissionTheoretical 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=5700rpmCVT MT
8.8 sec. 11.9 sec.
0-100 km/h
CVT Simulation:
Audi A6 Multitronic
Audi A6 3.0 L0-100 kmph Mileage
A6 5-speed manual 8.2 sec9.9 litre/ 100km
A6 5-speed Tiptronic 9.4 sec10.6 litre/
100km
A6 Multitronic CVT 8.1 sec9.7 litre/ 100km
Our Model
(CATIA Model)
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)
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
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.