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seminar presentation on continuously variable transmission CVT By Pukhraj Palariya

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  1. 1. A SEMINAR PRESENTATION ON ¥CONTINUOUSLY VARIABLE TRANSMISSION¥ (CVT) Submitted from Pukhraj mali Roll no.:-12EELME035 ME Engg. final year Submitted to Mr.Rahul Shrivastav Head of mechanical department
  2. 2.  Today automobiles use either a conventional manual or automatic transmission with multiple planetary gear sets that use clutches to achieve discrete gear ratios .  The continuously variable transmission replaces discrete gear ratios with infinitely adjustable gearing through one of several basic CVT designs  A continuously variable transmission (CVT) is a transmission that can change seamlessly through an infinite number of effective gear ratios between maximum and minimum values  The flexibility of a CVT allows the input shaft to maintain a constant angular velocity. Introductionof CVT
  3. 3. Overviewof aCVT 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
  4. 4. Basicsof transmission  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 to make more effective use of the engine's torque as driving conditions change. There are 3 type of transmission- 1.Manual transmission 2.Automatic transmission 3.Semi automatic(CVT)
  5. 5. PROBLEMS WITH MANUAL & AUTOMATIC TRANSMISSION The traffic condition has become annoying in our big cities so fuel consumption is very high  In such a case will automatic transmission make sense to the Indian customer.  But conventional automatics always consume slightly more fuel than manual transmission and the lack of sophisticated automatics.
  6. 6. Componentsof CVT 1. A variable –input driving pulley 2. An output(driven) pulley 3. A metal belt/rollers 4. Sensors and microprocessors
  7. 7. Workingprinciple  A pair of variable-diameter pulleys, each shaped like a pair of opposing cones, with a metal belt or chain running between them.  One pulley is connected to the engine (input shaft), the other to the drive wheels (output shaft)  As the pulley halves come closer together the belt is forced to ride higher on the pulley, effectively making the pulley's diameter larger.  Changing the diameter of the pulleys varies the transmission's ratio.
  9. 9. Typesof CVT Metal Push Belt CVT. Toroidal Drive CVT. Variable Diameter pulley Belt CVT Hydrostatic CVT  Magnetic CVT
  10. 10. Simulationof CVT Push Belt This belt transmits power between two conical pulleys, or sheaves, one fixed and one movable . A sensor reads the engine output and then electronically increases or decreases the distance between pulleys, and thus the tension of the drive belt
  11. 11. ToroidalTractionDriveCVT: Uses rollers to transmit torque between the input disc and output disc. A viscous fluid transmits torque between rollers and discs. Rollers and discs never touch. The angle of the rollers changes relative to shaft position resulting in a change in gear ratio. The change in angle by a roller must be mirrored by the opposing roller.
  12. 12. Toroidal CVT
  13. 13. ADVANTAGESOF CVT  Decreases engine fatigue  “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%).  Smooth, responsive and quiet to drive
  14. 14. CVTVs. Manual transmission Theoretical comparison under “ideal” conditions 1991 FIAT UNO M=1250 KG,TORQUE=101.2 NM 0-100 KMPH MT-11.9 SEC /CVT-8.8 SEC CVT proved 35% more efficient than the MT. With same car and engine, the CVT takes only 75% of the time to accelerate to 100km/h, compared to the MT.
  15. 15. DRAWBACKS  Limited torque capacity when compared to manual transmissions.  Additional gear train required for reverse condition.  Larger and more costly than manual transmissions.  Unwillingness to discard billions of dollars in development in MT & AT’s.
  16. 16. USESOF CVT  Many small tractors for home and garden use have simple rubber belt CVTs. For example, the John Deere Gator line of small utility vehicles use a belt with a conical pulley system. They can deliver an abundance of power and can reach speeds of 30–32 mph (48–51 km/h), all without need for a clutch or shifting gears. Nearly all snowmobiles, old and new, and motor scooters use CVTs, typically the rubber belt/variable pulley variety.  In various ATV CVT is most widely used due to better fuel economy.
  17. 17. The 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  Costs will be reduced further and performance will continue to increase. Ultimately it will give CVTs a solid foundation in the world’s automotive infrastructure. Future of CVT
  18. 18. THANK YOU