107
5
1
2
3
4
(WHEN ENGINE LOAD IS LOW)
(WHEN ENGINE LOAD IS HIGH)
1
2
3
4
1. BREATHER HOSE
2. PCV VALVE
3. INTAKE MANIFOLD
4. EXHAUST MANIFOLD
5. THROTTLE VALVE
Blow–by Gas Recovery Device
The blow–by gas recovery device is provided in order to
return unconsumed gas (consisting mainly of HC) that
has escaped into the crank case from gaps between the
pistons and cylinders to the combustion chamber,
where it undergoes combustion, and uses a closed type
consisting of a cylinder head cover, PCV valve, breather
hose, and throttle valve.
[Under low engine load]
Since the opening of the throttle valve is slight, air that
has been drawn in from the air cleaner passes through
the breather hose and is sent to the cylinder head cover.
At the same time, since large negative pressure is pro-
duced in the intake manifold, the PCV valve is opened.
Thus, blow–by gas that has passed through the oil trap
and collected in the cylinder head cover is swept into the
combustion chamber by the air passing through the
breather hose.
[Under high engine load]
Since the opening of the throttle valve is large, the pres-
sure in the upstream and downstream of the throttle
valve is roughly equal, but the downstream side of the
air cleaner assumes a negative pressure to the extent
of the resistance of the air cleaner.
Thus, the blow–by gas is swept into the combustion
chamber from both the breather hose and PCV valve.
Ternary Catalyst Device
The ternary catalyst is provided in order to oxidize and
lower the amount of CO and HC, which are the harmful
constituents of exhaust gas, and uses a monolith type
having an integrated structure.
In order to make the catalyst function at an efficiency
closest to the theoretical air–fuel ratio, the air–fuel
ratio is adjusted by the ECM.
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