14. Emission Control System
14-1
Emission Control System
Mechanism································· 14-1
Function of Mechanism in the
Emission Control System········· 14-1
Fuel Evaporative Emission Control
System (E.E.C.)·························· 14-2
Catalytic Converting System (CATA)
···················································· 14-4
Secondary Air Introduction System
···················································· 14-5
Positive Crankcase Ventilation
System (P.C.V.)·························· 14-8
Inspection Items························ 14-9
Countermeasure for Emission
Pollutants Not Within Standard in
Idle Speed ·································· 14-10
Emission Control System Mechanism
Four-Stroke Engine Model
1. Catalyst converter (CATA.)
2. Evaporative Emission Control System (E.E.C.)
3. Air Injection System (A.I.)
4. Positive Crankcase Ventilation System (P.C.V.)
Function of Mechanism in the Emission Control System
General
The emission control strategy of this model was formulated basing on a four-stroke SOHC carburetor
single cylinder engine. It adopts secondary air introducing device to purify the exhaust, in addition, it also
adopts a charcoal canister to absorb the fuel vapor generated through evaporation in the fuel system.
※ Engine refinements－
Two Valves designed combustion chamber, together with optimum compression ratio, ignition timing,
intake and exhaust timing, have all contributed to maximize the intake/exhaust efficiency and
combustion efficiency.
※ Secondary air introducing system－
It is used to introduce secondary air into exhaust manifold so that incomplete burned exhausts, CO &
HC, may be burned again and to be harmless gases.
System Device Components Purpose & function
Combustion
chamber
Combustion
chamber
2-valve combustion
chamber
The semi-circular combustion chamber is
designed to balancing the air stream to achieve
the combustion stability.
Exhaust
system
Post-treatment
device
Catalytic converter
Installed a three-way catalytic converter in the
middle of exhaust pipe to oxidize the CO, HC in
the exhaust gas.
E.E.C. system
Evaporative
emission control
system
Charcoal canister
Purge control valve
canister is used to absorb vapor from fuel tank
and to introduce it into carburetor at an
opportune timing.
A.I. system
Secondary
air-injection system
Air inject cut-valve
Secondary air filter
To introduce flesh air into exhaust manifold
controlled by an air cut-valve to burn the
exhaust again.
P.C.V. system
Crankcase blow-by
introducing device
Vapor separator
To introduce blow-by into combustion chamber
via a vapor separator for burning then
discharging.
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