Camless Engines

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Since the invention of internal combustion engines, camshafts have been used to operate the valves on the cylinder head to bring in air and fuel and expel exhaust gases. The conventional valve train has its limitations: the single lobed cam is designed to operate the valves at only specific periods of the Otto cycle, thus preventing the engine from achieving maximum torque at higher rpms. The opening and closing of the valves is constrained by the geometry of the cam profile. The concept of camless engines allows for greater optimization of overall engine performance during different phases of running.

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Camless Engines

  1. 1. Camless Engines Visit www.seminarlinks.blogspot.in to Download
  2. 2. Introduction Thenew emerging technology for automotivetechnology arethe Camlessenginewhich theenginedoesnot havecamshaft to lift theboth intakeand exhaust valve.
  3. 3. CAMS • Control thebreathing channels(valves) of an IC engine • Connected to camshaft which isoperated by crankshaft • Camspush open valvesat proper time& guidetheir closure • But they areinflexibleexcept VTEC & VVT-I • Engineerscould not vary timing, lift & duration of valveopening infinitely
  4. 4. CAMLESS ENGINES • Eliminated mechanical linkages • Could provideinfinitevariation of valveparameters • It can makeenginesclean, efficient & responsive
  5. 5. Working Of Conventional Engines • Thecrankshaft turnscamshaft which operatesvalvesby mechanism • Spring bringsback valveto initial position • Timing of enginevalvesdependson shapeof cams
  6. 6. Conventional Engine Valves
  7. 7. • Engineersmust design camsin thedevelopment stages • Thisdesign compromisesb/n enginepower & fuel efficiency • Considering thiscompromiseautomobilecompaniesbrought variable valvetiming mechanisms • But iseffectswerelimited
  8. 8. Camless engines overview • Main sensors-  Engineload sensor Exhaust gassensor  Valveposition sensor Enginespeed sensor ELECTRONIC CONTROL UNIT SENSORS ACTUATORS
  9. 9. • Sensorssenseparameters& send signalsto ECU • ECU containsmicroprocessorswith associated software • ThisECU controlstheactuatorsto work according to requirements
  10. 10. Actuators • It isaelectro-hydraulic camlessvalvetrain (ECV) Useselastic property of compressed hydraulic fluid which actslikea liquid spring, accelerates& deceleratesthevalves
  11. 11. Hydraulic pendulum • Involvesconversion of PE to KE and back to PE with minimum energy loss • During acceleration of valvesPE isconverted to KE • During deceleration of valveenergy of moving valveisreturned to fluid
  12. 12. Detailed view of Hydraulic Pendulum
  13. 13. Operation of hydraulic pendulum
  14. 14. • Lift, timing & duration of valveopening isvaried by controlling solenoid valves • Thisisdoneby ECU when signalsaresent from thesensors
  15. 15. Modifier Rod • Used to impart  Unequal lift to thepaired valves  Zero motion to any valve
  16. 16. Modifier Rod Operation
  17. 17. Advantages • Enablesthedevelopment of higher torquethroughout theentirerev range which in turn improvesfuel economy • Cylinder Deactivation can beachieved during theidling phase • Exhaust gasrecirculation isimproved • Reducesfriction losses • Reducestheinertiaof moving parts
  18. 18. Resultant Advantages • Better fuel economy- 7 to 10 % increase • Higher torque& power- 10 to 15 % increase • Lower exhaust emissions- EGR system iseliminated sinceEGR effect occurson itsown & thusreducesNOx emissions • Reduction in size& weight
  19. 19. Disadvantages • High Cost • Increased power consumption • Air gap between thesolenoidsmay demand ahigher magnitudeof current during certain periods • Thecontrol strategy for valveseating velocity needsto bemodified
  20. 20. Conclusion Even though somedisadvantagesarepresent, wecan expect electrohydraulic & electromechanical valvesto replacethe conventional camshaft technology.
  21. 21. References • http://www.cvel.clemson.edu/auto/AuE835_Projects_2011/Shroff_project.h • http://en.wikipedia.org/wiki/Camless • http://www.autospeed.com/cms/article.html?&A=0910
  22. 22. Thanks Visit www.seminarlinks.blogspot.in to Download

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