Cvt mini project presentation
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The document discusses continuously variable transmissions (CVTs). It provides an overview of CVTs, noting they vary the transmission ratio continuously and allow the engine to operate in its optimal power range. The main types of CVTs are described as metal push belt, toroidal drive, and cone designs. A brief history of CVTs is given, along with illustrations of how metal push belt CVTs work. Advantages like fuel efficiency and disadvantages like limited torque capacity are outlined. An example compares the acceleration of a car with a CVT versus manual transmission. A CATIA model of a CVT is shown along with component details.
Cvt mini project presentation
- 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
- 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.