Transcript Camless Engine - Mechanical Engineering Online

CAMLESS ENGINES
What Is Cam???

Cam is a rotating machine element which gives
reciprocating motion to the follower.

The motion of the follower is pre-determined
and accordingly the Cam is designed.

The cams are normally placed on a fixed
camshaft which is then geared to the
crankshaft.
Working Of Conventional Four
Stroke IC Engine

Has four strokes.

Movement of inlet and exhaust
valves with the help of Cam.
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Conventional Valve train


The valvetrain consists of
valves, rocker arms,
pushrods, lifters, and
camshafts.
It involves many moving
parts.
CAMSHAFT
 Rocker arm is a
reciprocating lever that
conveys radial
movement from the cam
lobe into linear
movement at the poppet
valve to open it.
 It provides a reasonable
balance of strength,
weight and economical
cost.
ROCKER ARM
Disadvantages Of Conventional
Valvetrain
I.
II.
III.
Increased frictional losses
Cam profile is fixed
Noise
Overview Of Camless Engine
SENSORS
ELECTRONIC
CONTROL
UNIT
ACTUATO
RS
Mainly Five Sensors are present,which senses;
I.
Speed of the engine.
II.
Load on the engine.
III. Exhaust gas Sensor.
IV. Valve position Sensor.
V.
Current Sensor.
Microprocessors are present in ECU to issue
signals and control the Actuators.
Types Of Camless Mechanisms
I.
Electromechanical Poppet Valves.
II.
Electromechanical Ball Valves.
III.
Electrohydraulic Poppet Valves.
Electromechanical Poppet Valves

Early systems magnetic
attraction/repulsion
was used on an iron or
ferromagnetic armature

Varying Air Gaps which
lead to high energy
losses and High Seating
Velocities which made
varying of the lift
difficult.




It is replaced with a current-carrying armature
coil.
A magnetic field is generated by a magnetic
field generator and is directed across the fixed
air gap.
The force generated on the armature coil drives
the armature coil linearly in the air gap in a
direction parallel with the valve stem.
Depending on the direction of the current
supplied to the armature coil, the valve will be
driven toward an open or closed position.
Camless Valvetrain Types

Electromechanical Poppet Valves
Electromechanical Ball Valves

It consists of a ball
through which there
is a passage.

If the ball is rotated
such that the passage
lines up with other
openings in the valve
assembly, gas can
pass through it.

Electromechanical Ball Valves
Electro-hydraulic Poppet Valves

A source of
pressurized hydraulic
fluid and a hydraulic
actuator coupled to
the poppet valve is
used.

The use of engine oil
as the hydraulic fluid
simplifies and lowers
the cost of the
design.

Electro-hydraulic Poppet Valves
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.




Increases engine
performance.
Decreases fuel
consumption
Decreases harmful
emissions
Valeo estimates
that the efficiency
of a camless engine
would be 20%
greater than a
comparable
camshaft-operated
engine
Limitations Of Camless Engines
1.
Relatively high cost
2.
Packaging
3.
Power consumption
4.
Noise and vibration
Current Applications Of Camless
Engines



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.
Thank You