CAMLESS ENGINES

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CAMLESS ENGINES
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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

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

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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

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Conventional engine valves
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• 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

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Camless engines overview

• Main sensors -
• Engine load sensor Exhaust gas sensor
• Valve position sensor Engine speed sensor

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• Sensors sense parameters send signals to ECU
• ECU contains microprocessors with associated
  software
• This ECU controls the actuators to work according
  to requirements

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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

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• 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

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Detailed view of Hydraulic Pendulum
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Operation of hydraulic pendulum
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• Lift, timing duration of valve opening is
  varied by controlling solenoid valves
• This is done by ECU when signals are sent from
  the sensors

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Modifier Rod

• Used to impart
• Unequal lift to the paired valves
• Zero motion to any valve

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Modifier Rod Operation
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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

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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

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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

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Conclusion

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

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Thanks