camless engines ayushi

7/27/2019 Camless Engines Ayushi

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Presented by:-

Ayushi Srivastava

III Yr

Mechanical Engineering

Under The Guidance of:-

Mr. Devendra Singh

Associate Professor

Deptt. of Mechanical Engg.

AKGEC , GHaziabad


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CAMS Controls the breathing channels (valves) ofan IC engine Connected to camshaft which is operated bycrankshaft Cams push open valves at proper time &guide their closure Engineers could not vary timing, lift &duration of valve opening infinitely


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Engineers must design cams in thedevelopment stages

This design compromises b/n engine power& fuel efficiency

Considering this compromise automobilecompanies brought variable valve timingmechanisms .

This lead to the development of camlessengines.


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PROBLEMS IN USING CAMSHAFTI. Major power wastage in accelerating andde-accelerating the components of the

valve train.II. Friction of camshafts, springs, cam belts

etc., also robs us of precious power andworsens fuel economy and alsocontributes to wear and tear


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In normal engines lobes on the camshaftoperates cam followers which in turn opensthe poppet valves , while in CAMLESS engineselectromagnetic, hydraulic or pneumaticactuators opens poppet valves.

Eliminated mechanical linkages Could provide infinite variation of valve

parameters It can make engines clean, efficient &

responsive


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The crankshaft turnscamshaft whichoperates valves bymechanism Spring brings backvalve to initialposition Timing of enginevalves depends on

shape of cams The figure showsworking of a 4stroke engine


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The valve train consists ofvalves, rocker arms, pushrods,lifters and camshafts

It involves many moving parts.Rocker arm is a reciprocating leverthat conveys radial movement fromthe cam lobe into linear movement atthe poppet valve to open it.


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Increased Friction losses Fixed Cam Profile Increased noise More moving parts and mechanisms and

hence more power losses


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Mainly five sensors are present which senses 1. Speed of the engine2. Load on the engine3. Exhaust Gas Sensor4. Valve position Sensor5. Current Sensor

ELECTRONIC

CONTROL

UNIT

SENSORS ACTUATORS


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These sensors send signals to the ECU The electronic control unit consists of a

microprocessor, which is provided with asoftware algorithm.

The microprocessor issues signals to thesolid-state circuitry based on this algorithm.

These signals control the actuator, tofunction according to the requirements.


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1. Electromechanical Poppet Valves2. Electromechanical Ball Valves3. Electrohydraulic Poppet Valves


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Early systems magneticattraction/repulsion wasused on an iron orferromagnetic armature Varying Air Gaps whichlead to high energy lossesand High SeatingVelocities which made

varying of the lift difficult.


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It is replaced with a current-carryingarmature coil. A magnetic field is generated by a magneticfield generator and is directed across thefixed air gap. The force generated on the armature coil

drives the armature coil linearly in the air gapin a direction parallel with the valve stem. Depending on the direction of the currentsupplied to the armature coil, the valve will

be driven toward an open or closed position.


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It consists of a ballthrough which there isa passage. If the ball is rotatedsuch that the passagelines up with otheropenings in the valveassembly, gas can

pass through it.


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A source ofpressurizedhydraulic fluid and ahydraulic actuatorcoupled to thepoppet valve is used. The use of engine oilas the hydraulic fluid

simplifies and lowersthe cost of thedesign


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COMPONENTS A double acting piston Solenoids(Two for each valve i.e., one high

pressure solenoid valve(HPSV) and one low pressuresolenoid valve (LPSV)):4

Reservoirs(Two for each valve i.e., one highpressure reservoir and one low pressure reservoir):4

Check valves: (Two for each valve i.e., one highpressure check vale and one low pressure check valve):

4


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Works on differential pressure b/n input &output of the fluid.

The flow of the fluid is controlled by solenoidvalve. Thus controlling the valve opening andclosing.

When solenoid gets activated, then thearmature pin goes up and the fluid inchamber slowly enters the output side.

Hence a pressure difference is created aboveand below the diaphragm and because of thisthe diaphragm rises, hence opening the mainvalve, so the fluid flows through the outputside.


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Infinitely variable valvetiming. More torque is madeavailable throughout

there v-range. Increases durability andengine life. Valve train weight whichlimits the rotational

speed at which theengine can operate isreduced.


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Increases engine performance. Decreases fuel consumption Decreases harmful emissions Valeo estimates that the efficiency of acamless engine would be 20% greater than a

comparable camshaft-operated engine Better fuel economy- 7 to 10 % increase Higher torque & power- 10 to 15 % increase


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Sophisticated electronic control required forgentle seating of valvesCurrent solenoids cannot run at high rpms;High cost of microprocessor & software

controls


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Camless valve trains using solenoids ormagnetic systems are being investigated byBMW and Fiat.

They are being prototyped by Valeo andRicardo.

Also used in Fiat 500.


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Fiat, BMW and TATA motors are doingresearch to develop this technology. Research and development are needed to

take full advantage of this systemsexceptional flexibility.

This concept has to be developed withutmost case with the real time engine.

Valve timing and performance has to beanalyzed with real time working engine.


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Even though some disadvantages arepresent, we can expect electro-hydraulic &electromechanical valves to replace theconventional camshaft technology.


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camless engines ayushi

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