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2420-01
ENGINE EXHAUST SYSTEM
OVERVIEW AND OPERATION PROCESS
1. DESCRIPTION AND OPERATION
1) Exhaust System
When you are inspecting or replacing exhaust system components, make sure there is
adequate clearance from all points on the underbody to avoid possible
overheating of the floor panel and possible damage to the passenger compartment insulation
and trim materials.
Check the complete exhaust system and the nearby body areas and trunk lid for broken,
damaged, missing or mispositioned parts, open seams, holes, loose connections, or othe
r
deterioration which could permit exhaust fumes to seep into the trunk may be an indication o
f
a problem in one of these areas. Any defects should be corrected immediately.
2) Catalytic Converter (Gasoline Engine)
When jacking or lifting the vehicle from the body side rails, be certain that the lift pads do not
contact the catalytic converter, as this could damage the catalytic converter.
Use of anything other than unleaded fuel will damage the catalyst in the catalytic converter. 1.
2.
Catalytic Converter Structure
The Catalytic converter of monolith type consists
of 2 walled metal bodies which is made o
f
Cordierite. The principal element of converter
consists of the materials like Alumina or oxidized
Serume in order to apply to Ceramic Monolith.
Washer coat operates first, and catalytic metal
elements (Pt, Pd, Rh) operates to washer coat
next.
Monolith type is lighter than other types, easy to
manufacture and quickly approaches to prope
r
temperature. Washer coat is used to make a
contact surface with exhaust gas bigger by
adhering closely to small holes
of inner layer. If a lead compound or phosphorus
adheres to the surface and the temperature
rises, its surface is decreased. The total area o
f
general monolith converter is about 45,
000~500,000ft3. (10 times of a football field)
Generally Alumina (AL2 O3) is used as a raw
materialand its 7 phases of gamma, delta, theta
have big areas and high stability for the
temperature, and nowadays gamma Alumina is
used usually.
ENGINE EXHAUST SYSTEM
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2420-01
Catalytic Converter and Temperature
Catalytic converter has the normal function
of purification at a range of the temperature.
Because it has a weak point of decreasing o
f
the purification rate in the condition o
f
continuous high temperature, it should keep
the temperature range of 400 to
for
normal condition. HC purification rate
becomes better according to the increase o
f
temperature in the normal range o
f
temperature. CO purification rate becomes
the best near the temperature of
and NOx does so near the temperature of
400 to
Purification of Catalytic Converter
Adhesion of soluble organic fraction
Purification of soluble organic fraction
Chemical reaction formula -
-
By catalytic action of two primary catalytic
converter, oxidation occurs in order to
decrease HC and CO. -
Oxygen adheres to catalytic Catalytic material supplies
each CO and HC with O2 for Catalytic material conversion
process by DOC
