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CAMLESS ENGINES

CAMLESS ENGINES. Introduction. CAMS Control the breathing channels (valves) of an IC engine Connected to camshaft which is operated by crankshaft Cams push open valves at proper time & guide their closure But they are inflexible except VTEC & VVT-I

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CAMLESS ENGINES

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  1. CAMLESSENGINES

  2. Introduction • CAMS • Control the breathing channels (valves) of an IC engine • Connected to camshaft which is operated by crankshaft • Cams push open valves at proper time & guide their closure • But they are inflexible except VTEC & VVT-I • Engineers could not vary timing, lift & duration of valve opening infinitely

  3. CAMLESS ENGINES • Eliminated mechanical linkages • Could provide infinite variation of valve parameters • It can make engines clean, efficient & responsive

  4. Working of conventional engines • The crankshaft turns camshaft which operates valves by mechanism as in figure • Spring brings back valve to initial position • Timing of engine valves depends on shape of cams

  5. Conventional engine valves

  6. Engineers must design cams in the development stages • This design compromises b/n engine power & fuel efficiency • Considering this compromise automobile companies brought variable valve timing mechanisms • But is effects were limited

  7. ELECTRONIC CONTROL UNIT ACTUATORS SENSORS Camless engines overview • Main sensors - • Engine load sensor Exhaust gas sensor • Valve position sensor Engine speed sensor

  8. Sensors senseparameters & send signals to ECU • ECU contains microprocessors with associated software • This ECU controls the actuators to work according to requirements

  9. Actuators • It is a electro-hydraulic camless valve train (ECV) • Uses elastic property of compressed hydraulic fluid which acts like a liquid spring, accelerates & decelerates the valves

  10. Hydraulic pendulum • Involves conversion of PE to KE and back to PE with minimum energy loss • During acceleration of valves PE is converted to KE • During deceleration of valve energy of moving valve is returned to fluid

  11. Detailed view of Hydraulic Pendulum

  12. Operation of hydraulic pendulum

  13. Lift, timing & duration of valve opening is varied by controlling solenoid valves • This is done by ECU when signals are sent from the sensors

  14. Modifier Rod • Used to impart • Unequal lift to the paired valves • Zero motion to any valve

  15. Modifier Rod Operation

  16. Advantages • Offers continuously variable & independent control of all aspects of valve motion - lift, operation duration, event of opening • ECV system can control valve velocity, valve acceleration and deceleration

  17. Resultant Advantages • Better fuel economy- 7 to 10 % increase • Higher torque & power- 10 to 15 % increase • Lower exhaust emissions- EGR system is eliminated since EGR effect occurs on its own & thus reduces NOx emissions • Reduction in size & weight

  18. Disadvantages • Opening & closing of valves requires some power- • Electromechanical- alternator • Electrohydraulic- accumulator • Sophisticated electronic control required for gentle seating of valves • Current solenoids cannot run at high rpms; • Hidden cost of microprocessor & software controls

  19. Conclusion Even though some disadvantages are present, we can expect electrohydraulic & electromechanical valves to replace the conventional camshaft technology.

  20. Thanks

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