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Emission Controls

Emission Controls

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Emission Controls

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  1. Emission Controls

  2. Before beginning to understand emission controls you should know the reason why emission controls were installed into the automobile. 1. To reduce the amount of pollutants entering the atmosphere . Emission Controls

  3. Smog is a term developed from smoke and fog Smog is form when airborne pollutants is formed with oxygen and other atmospheric gasses to produce a grayish yellow smoke. The resulting smoke is called photochemical smog. Emission Controls

  4. Smog • Smog is can be a major problem in larger cities (New York and LA) • Smog can be harmful to • A. Humans • B. Plants • C. Animals and even effect paint rubber and other materials.

  5. Smog • One of largest producer of photochemical smog is the automotive internal combustion engine. • The EPA (environmental protection agency) begin putting restriction on automotive manufactories in the mid 60.

  6. Motor Vehicle Emissions • Motor vehicle emission are emission produce by motor vehicles. They include • A. Hydrocarbons (HC) • Carbon monoxide (CO) • Oxides of nitrogen (NOx)

  7. Hydrocarbons (HC) are emission of unburned petroleum products being released into the atmosphere. All petroleum products and made of hydrocarbons (hydrogen and carbon compounds) this includes: Gasoline LP-gas. Diesel motor oil. Exhaust Gasses

  8. Hydrocarbons are produced because of incomplete fuel combustion or fuel evaporation. Hydrocarbons emission is considered a hazardous form of air pollution because of. Eye. Throat. Lung irritation. And possibility cancer. Exhaust Gasses

  9. Exhaust Gasses • In north Carolina a vehicle must not exceed 220 ppm of hydrocarbons emissions. • High hydrocarbon emission are the results of a: • cylinder misfire. • Improper ignition timing • Worn cylinder rings (pumping oil into the combustion chamber

  10. Exhaust Gasses • Carbon monoxide emission are exhaust emission that is the result of partially burned fuel. • A high carbon monoxide emission can be caused by a: • Restricted or dirty air cleaner. • Advance ignition timing. • Clogged fuel injectors.

  11. Exhaust Gasses • Oxides of nitrogen, (NOx) are emission produced by extreme heat. • Air consist of approximately 79% nitrogen and 21% oxygen • When combustion chamber temperature reaches 2500 degrees F or 1370 degrees C nitrogen and oxygen combine to produce oxide of nitrogen (NOx)

  12. In North Carolina the standard for Carbon Monoxide is 1.2 % of the total exhaust output. Muffler HC 220 ppm CO 1.2% Exhaust output

  13. Exhaust Gasses • Oxides of nitrogen is responsible for the dirty brown color is SMOG. • NOx is a eye and respiratory irritant. • Newer high compression, learn air fuel mixture and hotter running engine produces more NOx than earlier engine.

  14. Exhaust Gasses • The same factors that increases NOx will tend to improve fuel mileage and lower HC and CO2 production. • This means that to increase fuel economy and lower HC and CO2 production NOx will increase. • For this reason emission controls have beedn added to lower all form of emissions

  15. Exhaust Gasses NOx increases HC increases Richer Leaner 14.7 – 1 AFR Hc and Co decreases NOx decreases

  16. Exhaust Gasses • Before understanding emission controls we need to first understand where they come from. • Particulates: are solid particle of carbon soot and fuel additives that blow out the tail pipe. • Engine crank case blow by. Caused by heating of oil and unburned fuel vapors that blow past the engine rings.

  17. Exhaust Gasses • Fuel vapors: different chemicals that enter the atmosphere as fuel evaporates. • Engine exhaust gasses: are harmful chemical that are produced inside the combustion chamber and are blow out the tail pipe.

  18. HC CO Solid particulate Catalytic Converter Exhaust manifold Fuel Tank Air Fuel Pump Fuel Fuel Vapors Fuel

  19. Exhaust Gasses • Automotive manufactures agree the best way to lower exhaust emission is to burn all the fuel entering the combustion chamber. • Modern engine have introduced several modification to ensure all fuel entering the combustion chamber is burned.

  20. Exhaust Gasses • Some engine modification are: • Lower compression ratio, by lowering compression ratio vehicle can burn unleaded fuel. The use of unleaded fuel allows for catalytic converters that help reduce HC and CO emissions. • Lower compression ratio also lower combustion temperature reducing NOx emission.

  21. Exhaust Gasses • Smaller combustion chambers, allows for more heat to remain inside the combustion chamber that can aid in the burning of fuel. • Reduce quench areas, the areas between the piston and the cylinder head is the quench area. If this areas is to close fuel will not burn completely increasing HC and CO emissions. Modern engine are design to reduce high quench areas.

  22. Exhaust Gasses Quench area

  23. Exhaust Gasses • Decrease valve overlap, is used to decrease exhaust emission. A larger valve overlap increases power but dilutes incoming fuel mixture and requires a richer air fuel mixture at lower engine speed therefore increasing HC and CO emissions.

  24. Exhaust Gasses Overlap Intake Exhaust

  25. Exhaust Gasses • Higher combustion chamber temperature, are used to reduce HC and CO emissions. • Today vehicles used hot thermostats than earlier model helping to increase combustion chamber temperature. • Leaner air-fuel mixtures help fuel burn better lower HC and CO emissions. • Wider spark plug gaps, are used to burn the leaner fuel mixture and helps prevent spark plug fouling.

  26. Exhaust Gasses Thermostats are now 190 degrees Wider spark plug gap Some are .080 thousands

  27. Learning Quiz • 1. When is photochemical smog formed? • A. when airborne pollutants is formed with oxygen and other atmospheric gasses • B. When Oxygen is mixed water inside the catalytic converter. • C. When exhaust gasses is heated to over 2500 degrees • D. All the above

  28. Learning Quiz • 2. Smog can be harmful to: • A. Humans • B. Plants • C. Rubber and medals • All the above

  29. Learning Quiz • 3.Technician A says CO is a hazardous exhaust emission. Technician B says HC is a hazardous exhaust emission. Who is correct? • A. Technician A only • B. Technician B only • C. Both technician A and B • D. Neither technician A nor B

  30. Learning Quiz • 4. Oxides of Nitrogen is produced when: • A. Combustion chamber temperature is to cold. • B. Combustion chamber temperature is too hot. • C. Atmospheric condition is humid. • D. all the above

  31. Learning Quiz • 5. High hydrocarbon are caused by: • A. Cylinder misfire • B. Dirty air filter • C. Low fuel pressure • D. Defective air filter.

  32. Learning Quiz • 6. A rich fuel mixture will cause and increase in: • A. Hydrocarbons • B. Oxides of Nitrogen's NOx • C. Both a and B • D. Neither A nor B

  33. Learning Quiz • 7. In North Carolina the maximum amount of Hydrocarbon emission allowed by a vehicle is: • A. 1000 ppm • B. 1.2% by exhaust volume • C. 220 ppm • D. 1% by exhaust volume

  34. Learning Quiz • 8.Technician A says Oxides of Nitrogen emission increases when combustion chamber temperature decreases. Technician B says Hydrocarbon emission is the result of a cylinder misfire. Who is correct? • A Technician A only B. Technician B only • C. A and B D. Neither A nor B

  35. Learning Quiz • 9. The best way to decrease exhaust emission is to: • A. Increase valve overlap. • B. Increase compression Ratios. • C. Increase combustion chamber size. • D. Burn all fuel enter the combustion chamber.

  36. Learning Quiz • 10.Technician A says crankcase blowby is not a source of vehicle emission. Technician B says modern vehicle use unleaded fuel to increase emissions and allow for the use of catlic converters. Who is correct? • A. Technician A only B. Technician B only • C. A and B D. Neither A nor B

  37. Vehicle Emission Control Systems • There are several different types of emission control system used on modern vehicles. • Positive crankcase ventilation system (PCV) is used to recalculate engine crankcase fumes back into the combustion chamber.

  38. Vehicle Emission Control • A PCV valve uses manifold vacuum to draw blow-by gasses from the engine into the intake manifold for reburying by the engine. • In earlier years automotive manufactories uses road draft tubes to remove crankcase blowby gasses.

  39. Vehicle Emission Control • The uses of road drift tube allowed for blowby gasses containing HC, CO, particulates, sulfur and small amounts of water to be vented in the atmosphere. • At idle when there is high engine vacuum the PCV value is pulled open to remove blow-by gasses from inside the engine.

  40. Vehicle Emission Control • At part throttle when vacuum is lower a spring inside the PCV valve forces the valve partially closed. But still allows for some blowby gasses to be vented back into the intake manifold for burning by the engine.

  41. Vehicle Emission Control When engine Vacuum is High PCV valve plunger is nearly closed When engine vacuum is low plunger Opens. Allowing exhaust gasses into Engine. PCV Plunger

  42. Typical PCV valve

  43. Evaporative Emissions Control SystemsEVAP The EVAP system prevents Hydrocarbons in the form of fuel vapors from entering the atmosphere even when the vehicle is not running. An EVAP system is considered a closed system. Fuel vapor are stored in a charcoal canister when the engine is off.

  44. Evaporative Emissions Control SystemsEVAP • When the engine is started vacuum pulls fuel vapors into the engine for burning. • EVAP system different from per emission vehicle because no fuel or vapor is vented into the atmosphere.

  45. Unvented Fuel Cap Rollover Valve Intake Manifold Vacuum Charcoal Canister Fuel Tank

  46. A rollover valve is uses to prevent fuel spillage in case of a rollover. • A liquid-vapor separator is sometime used to prevent liquid fuel from entering the charcoal canister. • A charcoal canister is used to store fuel vapor when the engine is not operating.

  47. Most modern vehicles electrically control the EVAP system to ensure a cleaner burning engine. • The EVAP system uses purge lines to connect the fuel tank to the charcoal canister and the intake manifold.

  48. 12 Volts with engine on PCM EVAP Solenoid Rollover Valve Fuel Tank Charcoal Canister

  49. Enhanced EVAP system • An enhanced EVAP system has the following additional components. • Fuel tank pressure sensor: This sensor monitor internal fuel tank pressure • Canister Vent Solenoid: An electrically operated solenoid that replaces the Fresh air valve on earlier systems • Service Port: is a test point located in the engine compartment and is used for testing the EVAP system

  50. Enhanced EVAP system • A normally open purge solenoid allows fresh air to enter the charcoal when in purge mode. • An enhanced EVAP system requires the uses of a bi-directional scan tool for several diagnostic procedures.