Transcript Repair and Replace Emission Control Systems

AURT3046666A
REPAIR AND
REPLACE EMISSION
CONTROL
SYSTEMS
AUR30405
CERTIFICATE
III IN AUTOMOTIVE
MECHANICAL
TECHNOLOGY
1
AURT304666A
Repair and replace
emission control
systems
© Commonwealth of Australia 2011
AURT3046666A Repair and replace emission control systems
AURT3046666A REPAIR AND REPLACE EMISSION CONTROL SYSTEMS
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Personal safety
• Use personal protective equipment
(PPE).
• Use wheel chocks & guard covers.
• Keep clear of hot or moving
components on engines.
• Lift vehicles correctly and safely.
• Plenty of ventilation when working
on running engines.
© Commonwealth of Australia 2011
AURT3046666A Repair and replace emission control systems
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Forms of pollution
Pollution from evaporation
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Pollution from combustion
AURT3046666A Repair and replace emission control systems
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Producing exhaust gases
Fuel is injected into the engine
Air enters the engine
Combustion
Exhaust gas exits
the engine
Blow by
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AURT3046666A Repair and replace emission control systems
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Sources of emissions
Fuel tanks and carburettors
10% by evaporation
Exhaust
60% from combustion
Crankcase
30% from combustion and blow by
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Emissions from petrol engines
Hydrocarbons (HC) come
from:
• unburnt fuel
• evaporating fuel
• crankcase vapours or
blow by gases
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Emissions from petrol engines
Carbon monoxide (CO) comes from:
• incomplete combustion due to a
lack of oxygen(air) during
combustion
• excessively rich fuel/air mixtures
• very lean fuel/air mixtures
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AURT3046666A Repair and replace emission control systems
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Emissions from petrol engines
Oxides of nitrogen (NOx) come from:
• overheating engine conditions
• increased compression ratios
• incorrect ignition timing
• lean fuel mixtures.
© Commonwealth of Australia 2011
AURT3046666A Repair and replace emission control systems
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Government legislation
Guidelines for 6 tests:
1.
Exhaust emissions after a cold start.
2.
Carbon monoxide emission test at idling
speed.
3.
Emissions of crankcase gases.
4.
Evaporative emissions from vehicles with
positive-ignition engines.
5.
Endurance test for durability of pollution
control devices.
6.
Average exhaust emissions of carbon
monoxide and hydrocarbons after a cold
start at low ambient temperature.
© Commonwealth of Australia 2011
http://www.comlaw.gov.au/
AURT3046666A Repair and replace emission control systems
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Emissions from diesel engines
Particulates
• carbon particles in the exhaust gas
• formed due to:
– incomplete combustion
– slow and cold engine operation
– high engine oil consumption.
Oxides of nitrogen (NOX)
• formed due to high combustion
temperatures in diesel engines.
© Commonwealth of Australia 2011
AURT3046666A Repair and replace emission control systems
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Government legislation
National Environment Protection
Measure (Diesel Vehicle Emissions)
2001, amended in 2009
www.nepc.gov.au
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Types of emission control systems
1. Evaporative control
Prevents fuel vapour escaping to the atmosphere
2. Crankcase ventilation
Prevents crankcase emissions escaping to the
atmosphere
3. Exhaust emission control
Controls the products of combustion before they enter the
atmosphere
© Commonwealth of Australia 2011
AURT3046666A Repair and replace emission control systems
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Evaporative emission control system
Vapour line to canister
Charcoal canister
Liquid/valve separator
Fuel tank
Carburettor
Petrol cap relief valve
Vapour vent
Air vent solenoid
valve
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Purge line
Fuel line
AURT3046666A Repair and replace emission control systems
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Evaporative emission control system
Stops fuel vapour escaping into
the atmosphere:
• Seals the fuel tank and
carburettor.
• Temporarily stores the
fuel vapour.
• Regularly flushes out the
stored fuel vapour.
© Commonwealth of Australia 2011
AURT3046666A Repair and replace emission control systems
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Charcoal Canister
Fuel vapour line
from carburettor
Throttle ported vacuum
Line to intake manifold
Fuel vapour line
from tank
• Stores the evaporating fuel
from the tank and carburettor
(if fitted).
Filter
• When the engine starts the
stored fuel vapour is sent to
the engine.
Charcoal
Filter
Air vent
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AURT3046666A Repair and replace emission control systems
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Fuel tank and cap
Stores the fuel.
Fuel tank
Prevents the fuel vapour from
escaping to the atmosphere.
Fuel filler cap
Liquid vapour separator
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Crankcase ventilation system
PCV - Positive Crankcase Ventilation valve
Valve spring
Air filter
• Prevents excessive
pressure build up in the
crankcase.
• Prevents unburnt fuel
vapour from escaping to
the atmosphere.
Shuttle valve
Fresh air
inlet
Valve seat
Intake manifold
PVC valve
Retaining spring
Blowby
gases
Valve housing
© Commonwealth of Australia 2011
Valve face
Hose connection to
inlet manifold
Crankcase vapours
& blowby gases
AURT3046666A Repair and replace emission control systems
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Exhaust emission control systems
Exhaust gases = more than 1/2 total emissions from vehicles.
Three ways to reduce or control exhaust emissions:
1. Engine design
2. Exhaust Gas Recirculating system (EGR)
3. Catalytic converter.
© Commonwealth of Australia 2011
AURT3046666A Repair and replace emission control systems
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Engine design
Wedge shaped combustion chamber
• large quench area
• increased hydrocarbon emissions
© Commonwealth of Australia 2011
Hemispherical combustion chamber
• minimal quench area
• less hydrocarbon emissions
AURT3046666A Repair and replace emission control systems
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Exhaust Gas Recirculating system (EGR)
• Returns some exhaust
gas to intake manifold.
• Lowers combustion
temperature.
• Reduces oxides of
nitrogen (NOx) in
exhaust gas.
Vacuum port
Exhaust gas
port
ERG valve
Thermo valve
Exhaust gas
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AURT3046666A Repair and replace emission control systems
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Catalytic Converter
Fitted to the vehicle exhaust system
as close as possible to the engine.
Tailpipe
Engine pipe
Muffler to tailpipe
Muffler
Pipe to muffler
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Catalytic convertor
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Catalytic Converter
Chemicals react with pollutants in exhaust gas
To exhaust
H2O - Water
CO2 - Carbon dioxide
O2 - Oxygen
N - Nitrogen
Pollutants
from engine
© Commonwealth of Australia 2011
HC - Hydrocarbons
CO - Carbon monoxide
NOx - Oxides of
nitrogen
AURT3046666A Repair and replace emission control systems
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Diesel particulate filter
Clean
exhaust
out
Exhaust in
Soot and ash particles
• Exhaust carrying particulate matter (PM) enters open channels.
• Ends of channels are blocked forces exhaust through walls.
• Pm is captured on the walls over time, pm burns away.
© Commonwealth of Australia 2011
AURT3046666A Repair and replace emission control systems
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Emission Control Information label
• 2005 ADR) 79/02 emission control regulations.
• Must be in a visible position in the vehicle engine compartment.
• Must state a range of engine specifications and adjustments.
© Commonwealth of Australia 2011
AURT3046666A Repair and replace emission control systems
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Testing exhaust emissions
Measure pollutants in exhaust gases with an exhaust gas analyser
Good ventilation is critical when testing
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AURT3046666A Repair and replace emission control systems
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© Commonwealth of Australia 2011
ISBN: 978-1-876838-51-5
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AURT3046666A Repair and replace emission control systems