10-06-2017, 06:51 AM
PRESENTED BY:
SHIJIL . P . K
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ELECTRO HYDRAULIC CAMLESS ENGINE
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)
Back
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
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
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