2.7.2 Description and Operation
2.7.2.1 Exhaust Manifold
Exhaust manifold used in this engine is a monolithic four-port manifold, which can be dismantled
from the rear. The function of exhaust manifold is to exhaust gases after combustion with the
minimum back-pressure. Front oxygen (HO2S)was installed on the exhaust manifold pipe。
2.7.2.2 Three-way Catalytic Converter Assembly
Three-Way catalytic converter is similar to the appearance of the muffler, however, inside the
stainless steel shell there is honeycomb-like ceramic substrate in the direction of the exhaust gas.
Ceramic liner carriers have been surrounded by the liner, which is used to retain the ceramic
carrier and prevent any contact or collision. Each end of the converter has a mesh seals to prevent
air pollution and the pad corrosion.
2.7.3 System operating principle
2.7.3.1 System operating Principle
Inside the three-way catalytic converter, the ceramic substrate exposed to emissions is coated with
a catalyst. Catalysts contain platinum, palladium and rhodium, three kinds of precious metals.
These catalysts promote chemical reactions.
Catalyst is to accelerate the chemical reaction while remain unchanged itself. Engine exhaust
contains carbon monoxide (CO), hydrocarbons (HC) and nitrogen oxides (NOx). When the
exhaust gas flows through the ceramic substrate, the chemical reactions in the three-way catalytic
converter occur. carbon monoxide and hydrocarbon was transformed into CO2 and H20 by gas.
Oxides of nitrogen carried out reduction reaction with CO to transform N2. This three-way
catalytic converter is called three-way type, because it turns the three components (CO, HC and
NOX) into harmless neutral gas at the same time.
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