03-4
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 other
deterioration which could permit exhaust fumes to seep into the trunk may be an indication of 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 of
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 proper
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 of 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.
03-52420-01
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 of
the purification rate in the condition of
continuous high temperature, it should keep
the temperature range of 400 to 500°C for
normal condition. HC purification rate
becomes better according to the increase of
temperature in the normal range of
temperature. CO purification rate becomes
the best near the temperature of 450°C, and
NOx does so near the temperature of 400 to
500°C.
Purification of Catalytic Converter ▶
Adhesion of soluble organic fraction
(SOF) below 180°C
Purification of soluble organic fraction
(SOF) over 180°C
Chemical reaction formula -
-
SOF(HC)+O2 → CO2+H2O
2CO+O2 → 2CO2
2C2H6+7O2 → 4CO2+6H20
By catalytic action of two primary catalytic
converter, oxidation occurs in order to
decrease HC and CO. -
Oxygen adheres to catalytic
material : below 180°CCatalytic material supplies
each CO and HC with O2 for
their oxidation : above 180°CCatalytic material conversion
process by DOC
03-6
Method for Reduction of NOx ▶
NOx is generated a great deal in case that combustion temperature and excess air factor are
high. EGR valve can decrease NOx (30 to 35% decrease) by making temperature of combustion
chamber fall by means of exhaust gas re-circulation.
EGR valve is installed on the diesel engine of Musso, Korando, Istana and Rexton.
And micro switch is installed together to control EGR valve.
The setting method of micro switch is identical with the existing one. -
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