7. INTAKE AND EXHAUST SYSTEM
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7. INTAKE AND EXHAUST SYSTEM
7.1 Intake System
Air enters in the intake silencer mounted at the end of
the intake manifold, is fed to the intake manifold and
then on to each cylinder.
Exhaust gas goes into exhaust manifold (in the fresh
water tank) mounted on the cylinder head outlet. After
cooling, the exhaust gas enters the mixing elbow, which
is directly connected with the exhaust manifold, and is
discharged from the ship along with seawater.
When the inside of the intake manifold becomes dirty,
intake air resistance is increased and reduces engine
power. Periodically check the inside of the intake
manifold. In the same way, the intake air silencer should
be checked for dirt periodically and cleaned.
When the intake manifold is being attached to the
cylinder head, the attachment surfaces should checked
for dirt and cleaned. Care should also be taken to
insure there is no air leakage.
Do not operate with the intake air silencer removed.
7.1.1 Breather system (A reductor to
intake air system of blowby gas)
Emitting blowby gas is harmful to natural environment.
Therefore blowby gas reductor is adopted to JH4 series
naturally- aspirated engines as breather system.
Some of the combustion gas passes through the
clearance between cylinder and piston, and flows to the
crankcase. This is said as blowby gas. While it passes
into cylinder head and rocker arm cover, the blowby gas
mixes with splash oil, and becomes oil mist-blowby gas.
The gas passes through the baffle plate inside a rocker
arm cover. And it passes through a diaphragm assy,
and reaches a intake silencer. The gas is reduced in the
combustion chamber.
Pressure inside a crankcase is controlled by the
function of the diaphragm assy, and suitable amount of
blowby gas is reduced in intake air system.
[Disassemble]
When a rocker arm cover is taken off, check whether
oil or the like enter the diaphragm space from a small
hole on the side of a diaphragm cover or not without
disassembling the diaphragm.
Silencer
OPTIONAL Air heater
Rocker arm cover
Breather pipe
Cylinder head
Intake manifold
(Breather system component)
Center plate
Spring
Diaphragm
Diaphragm cover
Rocker arm cover
Breather
baffle
Baffle plate
Intake silencer
Breather pipe
(Blowby gas flow)
Blowby gas flow
Blowby gas flow
to diaphragm
space
Diaphragm part
Baffle plate
Rocker arm
cover
Center plate
Cover
Spring
Diaphragm
