variable valve timing
DESCRIPTION
fundamentals of i.c. engineTRANSCRIPT
L.D. COLLEGE OF ENGINEERING
L.D. COLLEGE OF ENGINEERING
SUBJECT : FUNDAMENTALS OF I.C. ENGINE & AUTOMOBILE
VARIABLE VALVE TIMING
PREPARED BY : VIVEK DHAMELIYA
140280711005
WHAT IS VVT ?
Variable Valve Timing technology is used in engine to vary the valve opening, closing and sparking or injection timing at different speed.
VVT allows the lift or duration or timing (some or all) of the intake or exhaust valves (or both) to be changed while the engine is in operation.
VARIABLE VALVE TYPES AND COMMON MANUFACTURERS
VALVETRONIC BMW
VVT-I TOYOTA
VTEC - HONDA
CAMELESS ENGINE - SIEMENS
VALVETRONIC (BMW)
Valvetronic varies valve lift by adjusting the
fulcrum point of the rocker arm.
The eccentric shaft is turned by an electric
stepper motor which is controlled by the
engine control unit.
This will influence how much the cam can
push down on the valve
VVT-I (TOYOTA)
Utilizes Oil actuated cam sprocket and follower.
Angle is adjusted using oil pressure
Oil pressure controlled with electronic solenoid Typically
VTEC (HONDA)
VTEC means Variable valve Timing and lift Electronic Control
They have used two different type of cam
- high speed cam
- low speed cam
Synchroniser pin is operates by linear servo motor and used to active the high speed cam
This system will start to work after 5000 RPM
CAMLESS VALVE ENGINE
Current flows through the armature and a magnetic
field forms by the coil.
According to Lenzs law magnetic field exert a force
on current carrying conductor.
As the armature moves downward, the spring
collapses and the valve opens.
When current stops flowing to the armature, the
magnetic field collapses and the spring expands
and shuts the valve.
THANK YOU
Advantages of Variable Valve Engine
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Engine Speed (rpm)
Brake Torque (N*m)
Convential Engine
Varable Valve Engine