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Cvt

Cvt

  1. 1. CONTINOUS VARIABLE TRANSMISSIONC V TBY : Ziad Zohdy
  2. 2. Basics of Transmission• The job of the transmission is to change thespeed ratio between the engine and the wheels ofan automobile• The transmission uses a range of gears -- fromlow to high -- to make more effective use of theengines torque as driving conditions change. Thegears can be engaged manually or automatically.
  3. 3. Problems in manual & automatictransmission
  4. 4. Benefits of CVT Provide engine torque in optimum condition (roadloads / drive shaft torque) No shift clonk Transmission ratio can be adjusted continuously Better acceleration Improved fuel efficiency
  5. 5. Behavior of CVT
  6. 6. CVT MAIN TYPES Pulley based CVT Toroidal CVT Hydrostatic CVT
  7. 7. Pulley based CVT The gear ratio is changed by moving the two sheavesof one pulley closer together and the two sheaves ofthe other pulley farther apart. The distance between the pulleys does not change and neither does the length of the belt so changing the gear ratio means both pulleys mustbe adjusted (one bigger, the other smaller)simultaneously in order to maintain the proper amountof tension on the belt.
  8. 8. Pulley based CVT
  9. 9. Toroidal CVT
  10. 10. Toroidal CVT
  11. 11. Hydrostatic CVT Power transmitted by hydraulic fluid variable displacment pump& hydraulic motor• RotationalmotionENGINE• Fluid flowHYDROSTATICPUMP• RotationalmotionHYDROSTATICMOTOR
  12. 12. Hydrostatic CVT often,hydrostatic transmission is combined with aplanetary gearset and clutches to create a hybrid systemknown as a hydromechanical transmission. Hydromechanical transmissions transfer power from theengine to the wheels in three different modes At a low speed power is transmitted hydraulically at a high speed, power is transmitted mechanically Between these extremes, the transmission uses bothhydraulic and mechanical means to transfer power. Hydromechanical transmissions are ideal for heavy-dutyapplications, which is why they are common in agriculturaltractors
  13. 13. CVT Control
  14. 14. Mathematical Model of CVT Ie :engine inertia Is :active cvt pulley inertia Iq :passive cvt pulley inertia Be,Bs,Bq:damping coefficient i : speed ratio of cvt n : transmission efficiency Tr : resistance torque ofcar weight & load convertedto cvt output
  15. 15. ADVANTAGES OF CVT Decreases engine fatigue Maintains the engine for an optimum poweroutput Best acceleration More mechanical efficient than the automatictransmission Improved fuel efficiency
  16. 16. DISADVANTAGES OF CVT Limited torque when compared with manual Larger and more costly than automatic or manualtransmission Slipping in the drive belt or pulleys
  17. 17. REFRENCES http://www.synchrotronic.com/ http://auto.howstuffworks.com/cvt.htm http://www.wipo.int/pctdb/en/wo.jsp?IA=WO2007047352&wo=2007047352&DISPLAY=CLAIMS www.wikipedia.com
  18. 18. BY : ZIAD ZOHDYTHANK YOU 

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