Date post: | 11-Sep-2014 |
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CAMLESSCAMLESS ENGINESENGINES
SARATH SARATH PRAKASH.V PRAKASH.V MECHANICALMECHANICALG.P.T.C G.P.T.C KALAMASSERKALAMASSERYY
IntroductiIntroductiononCAMSCAMS
Control the breathing channels (valves) of an IC Control the breathing channels (valves) of an IC engineengine
Connected to camshaft which is operated by Connected to camshaft which is operated by crankshaftcrankshaft
Cams push open valves at proper time & guide Cams push open valves at proper time & guide their closuretheir closure
Engineers could not vary timing, lift & duration of Engineers could not vary timing, lift & duration of valve opening infinitelyvalve opening infinitely
CAMLESS ENGINESCAMLESS ENGINES Eliminated mechanical linkagesEliminated mechanical linkages Could provide infinite variation of valve Could provide infinite variation of valve
parametersparameters It can make engines clean, efficient & It can make engines clean, efficient &
responsiveresponsive
Working of Working of conventional conventional
enginesengines The crankshaft turns camshaft which The crankshaft turns camshaft which operates valves by mechanism as in figureoperates valves by mechanism as in figure
Spring brings back valve to initial positionSpring brings back valve to initial position Timing of engine valves depends on shape Timing of engine valves depends on shape
of camsof cams
Conventional Conventional engine valvesengine valves
Engineers must design cams in the Engineers must design cams in the development stagesdevelopment stages
This design compromises b/n engine power This design compromises b/n engine power & fuel efficiency& fuel efficiency
Considering this compromise automobile Considering this compromise automobile companies brought variable valve timing companies brought variable valve timing mechanisms mechanisms
But is effects were limitedBut is effects were limited
Camless Camless engines engines
overview overview Main sensors -Main sensors -
Engine load sensor Exhaust gas sensorEngine load sensor Exhaust gas sensor
Valve position sensor Engine speed sensorValve position sensor Engine speed sensor
Sensors senseSensors sense parameters & send signals to parameters & send signals to ECU ECU
ECU contains microprocessors with ECU contains microprocessors with associated softwareassociated software
This ECU controls the actuators to work This ECU controls the actuators to work according to requirementsaccording to requirements
ActuatorsActuatorsIt is a electro-hydraulic camless valve train It is a electro-hydraulic camless valve train (ECV) (ECV)
Uses elastic property of compressed Uses elastic property of compressed hydraulic fluid which acts like a liquid hydraulic fluid which acts like a liquid spring, accelerates & decelerates the valvesspring, accelerates & decelerates the valves
Hydraulic pendulumHydraulic pendulum Involves conversion of PE to KE and back Involves conversion of PE to KE and back
to PE with minimum energy lossto PE with minimum energy loss During acceleration of valves PE is During acceleration of valves PE is
converted to KEconverted to KE During deceleration of valve energy of During deceleration of valve energy of
moving valve is returned to fluidmoving valve is returned to fluid
Detailed view Detailed view of Hydraulic of Hydraulic PendulumPendulum
Lift, timing & duration of valve opening is Lift, timing & duration of valve opening is varied by controlling solenoid valves varied by controlling solenoid valves
This is done by ECU when signals are sent This is done by ECU when signals are sent from the sensorsfrom the sensors
Modifier RodModifier RodUsed to impart Used to impart
Unequal lift to the Unequal lift to the paired valves paired valves
Zero motion to any Zero motion to any valvevalve
Modifier Rod Modifier Rod OperationOperation
AdvantagesAdvantagesOffers continuously variable & independent Offers continuously variable & independent control of all aspects of valve motion - lift, control of all aspects of valve motion - lift, operation duration, event of openingoperation duration, event of opening
ECV system can control valve velocity, ECV system can control valve velocity, valve acceleration and decelerationvalve acceleration and deceleration
Resultant Resultant AdvantagesAdvantages
Better fuel economy- 7 to 10 % increaseBetter fuel economy- 7 to 10 % increase
Higher torque & power- 10 to 15 % Higher torque & power- 10 to 15 % increase.increase.
Reduction in size & weightReduction in size & weight
DisadvantageDisadvantagess
Opening & closing of valves requires some power- Opening & closing of valves requires some power-
Electromechanical- alternatorElectromechanical- alternator
Electrohydraulic- accumulatorElectrohydraulic- accumulator
Sophisticated electronic control required for Sophisticated electronic control required for gentle seating of valves gentle seating of valves
Current solenoids cannot run at high rpms;Current solenoids cannot run at high rpms;
Hidden cost of microprocessor & software Hidden cost of microprocessor & software controlscontrols
ConclusionConclusion Even though some disadvantages are Even though some disadvantages are
present, we can expect electrohydraulic & present, we can expect electrohydraulic & electromechanical valves to replace the electromechanical valves to replace the conventional camshaft technology.conventional camshaft technology.
THANX THANX FOR FOR
PATIENT PATIENT LISTENINGLISTENING
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