ELECTROHYDRAULIC CAMLESS ENGINE Presented by SHIJIL . P . K M7 A , 7352

WORKING OF CAM ENGINES Crank shaft turn the cam shaft Cam lobe pushes down the pushrod and it opens the valve Return motion is carried out due to spring action on push rod This results in closing of the valve (Animation)

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WHY camless engines ? Infinitely variable valve timing. More torque is made available throughout the rev-range. Increases durability and engine life . Valve train weight which limits the rotational speed at which the engine can operate is reduced

Overview 3 vital components – Sensors, Electronic Control Unit and Actuator Five sensors are used Sensing the speed of the engine Sensing the load on the engine Exhaust gas sensor Valve position sensor Current sensor. Sensors send signals to the ECU. Electronic Control Unit Consists of a microprocessor provided with a software algorithm. Issues signals to the solid-state circuitry This signals controls the actuator

Associated Concepts Hydraulic pendulum Hydraulic pendulum involves conversion of potential energy into kinetic energy and back into potential energy with minimal energy loss

2. Valve opening and closing

3. Valve motion control Valve lift can be controlled by varying the duration of the solenoid voltage pulse

Components Engine valve Solenoid Valve Lift Modifier Low Pressure Pump High Pressure Pump Cool Down Accumulator Sketches

ENGINE VALVE SOLENOID VALVE Back

advantages Independent control of all aspects of valve motion, valve lift, valve open duration etc Freedom to optimize all parameters of valve motion based on driving condition Reduced engine size and weight Better fuel economy (almost by 7-10%) Higher torque and power Improved idle stability Lower exhaust emissions (NO x emission reduced by 30%) Better breathing at low engine speeds

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 rpm Hidden cost of microprocessor & software controls

Current applications Camless valve trains using solenoids or magnetic systems are being investigated by BMW and Fiat. They are being prototyped by Valeo and Ricardo. Used in the new Fiat 500

conclusion Employs the hydraulic pendulum principle, which contributes to low hydraulic energy consumption. The electro hydraulic valve train is integral with the cylinder head, which lowers the head height and improves the engine packaging. Substantial improvements in performance, fuel economy, and emissions over and above what is achievable in engines with camshaft-based valve trains. Further research and development are needed to take full advantage of this system

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