13-06-2012, 04:21 PM
CAMLESS ENGINES
camless-engines.ppt (Size: 5.23 MB / Downloads: 313)
Introduction
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
CAMLESS ENGINES
Eliminated mechanical linkages
Could provide infinite variation of valve parameters
It can make engines clean, efficient & responsive
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
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
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
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