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1 Emission Controls Emission Controls 2 emission control system Purpose: control emissions and exhaust from vehicle Purpose: control emissions and exhaust.

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Presentation on theme: "1 Emission Controls Emission Controls 2 emission control system Purpose: control emissions and exhaust from vehicle Purpose: control emissions and exhaust."— Presentation transcript:

1

2 1 Emission Controls Emission Controls

3 2 emission control system Purpose: control emissions and exhaust from vehicle Purpose: control emissions and exhaust from vehicle Turn the harmful gases the car manufactures into harmless ones that don't ruin the environment Turn the harmful gases the car manufactures into harmless ones that don't ruin the environment Problem gases : Problem gases : –hydrocarbons (unburned) HC –carbon monoxide CO –nitrogen oxides NOx –sulfur dioxide SO2 –phosphorus P –lead and other metals Pb

4 3 Three (major) Pollutants –Hydrocarbons (HC) »Un-burnt Gasoline –Carbon Monoxide(CO) »CO results from the incomplete combustion Fuel –Oxides of Nitrogen (NOx) »NOx results from air being overheated.

5 4 HC HC results from gasoline that is not burned in the engine. This can be due from misfires, burning rich, open loop operation, or excessive cranking. HC results from gasoline that is not burned in the engine. This can be due from misfires, burning rich, open loop operation, or excessive cranking.

6 5 CO CO results from the incomplete combustion of organic materials. gasoline, kerosene, natural gas, propane, coal, wood, charcoal, diesel fuel, heating oil and almost any other combustible material, such as tobacco and paper. gasoline, kerosene, natural gas, propane, coal, wood, charcoal, diesel fuel, heating oil and almost any other combustible material, such as tobacco and paper.

7 6NOx Nitrogen oxides (NOx) are reactive gases Nitrogen oxides (NOx) are reactive gases Cause a host of environmental concerns impacting adversely on human health and welfare. Cause a host of environmental concerns impacting adversely on human health and welfare. Nitrogen dioxide (NO2), in particular, is a brownish gas that has been linked with higher susceptibility to respiratory infection, increased airway resistance in asthmatics, and decreased pulmonary function. Nitrogen dioxide (NO2), in particular, is a brownish gas that has been linked with higher susceptibility to respiratory infection, increased airway resistance in asthmatics, and decreased pulmonary function. Other effects: Other effects: Principle cause of ground-level ozone formation Principle cause of ground-level ozone formation Contribute to acid deposition, which can damage trees at high elevations and increases the acidity of lakes and streams, which can severely damage aquatic life Contribute to acid deposition, which can damage trees at high elevations and increases the acidity of lakes and streams, which can severely damage aquatic life Contribute to increased levels of particulate matter by changing into nitric acid in the atmosphere and forming particulate nitrate Contribute to increased levels of particulate matter by changing into nitric acid in the atmosphere and forming particulate nitrate combustion temperature gets above 2,500 degrees F combustion temperature gets above 2,500 degrees F

8 7 Evaporation from the fuel tank. 5% Evaporation from the fuel tank. 5% Blow-by gases which escape from the crankcase. 20-25% Blow-by gases which escape from the crankcase. 20-25% Tail pipe emissions. 60-75% Tail pipe emissions. 60-75% Carburetor evaporation from the float bowl on old cars. Carburetor evaporation from the float bowl on old cars.

9 8 POLUTION 20 % Crankcase vapors 20% Fuel Vaporization 60% Exhaust

10 9 Three Ways to Control Pollution 1 – Improve combustion 1 – Improve combustion 2 – Capture the vapors and re-burn them. 2 – Capture the vapors and re-burn them. 3 – Treat the exhaust. 3 – Treat the exhaust.

11 10 Ways to Combat Pollution Capture the vapors and burn them Capture the vapors and burn them –EGR –Charcoal Canister Improve the combustion Improve the combustion –Monitor mixture –Less Power Treat the exhaust Treat the exhaust –Fewer Emission

12 11 WHY 14.7:1

13 12 Road Draft Tubes Pre-PCV Pre-PCV Crankcase vapors vented into atmosphere Crankcase vapors vented into atmosphere

14 13 Vapor Recovery Type Systems Positive Crankcase Ventilation (PCV) Positive Crankcase Ventilation (PCV) Fuel Tank Vapor Recovery (VVR) Fuel Tank Vapor Recovery (VVR)

15 14 Positive Crankcase Ventilation Uses manifold vacuum to clean blow-by gases from crankcase. Needs a breather tube for fresh air. Needs a PCV valve to regulate the amount of gases entering the intake manifold.

16 15 PCV Operation The PCV valve has two functions: 1. To regulate the amount of vapor entering the intake manifold at various engine speeds. 2. Prevent damage from backfire.

17 16 Regulating the PCV Vapor Flow AmountConditionManifoldVacuumBlow-byGases IdleHighVacuumSmallVolume High Speed Low Vacuum LargeVolume

18 17 PCV Service Replace PCV valve every 3 years/30,000 miles. Replace PCV valve every 3 years/30,000 miles. Clean the breather filter if applicable. The valve can be cleaned also if you dont want to replace it. Clean the breather filter if applicable. The valve can be cleaned also if you dont want to replace it. Inspect hoses for proper routing and deterioration. Inspect hoses for proper routing and deterioration. Check the air cleaner housing for oil build up. Check the air cleaner housing for oil build up. Check PCV system function. Check PCV system function. 1) Use the PCV vacuum tester. 1) Use the PCV vacuum tester. 2) Use the tachometer and look for RPM 2) Use the tachometer and look for RPM drop. drop.

19 18 PCV Trouble-Shooting Notes Defective PCV system can cause big time vacuum leaks. This can lead to a very fast idle speed or stalling. Defective PCV system can cause big time vacuum leaks. This can lead to a very fast idle speed or stalling. If the valve or hoses get clogged the vapors back-up into the air cleaner clogging it too and puts oil in the air cleaner housing. If the valve or hoses get clogged the vapors back-up into the air cleaner clogging it too and puts oil in the air cleaner housing. A strange problem is if a valve cover gasket starts leaking oil winds up in the air cleaner also. A strange problem is if a valve cover gasket starts leaking oil winds up in the air cleaner also.

20 19 Fuel Tank Vapor Recovery Does not allow gasoline to evaporate from the gas tank to the atmosphere. Does not allow gasoline to evaporate from the gas tank to the atmosphere. Gas tank is sealed and vapors travel to a charcoal canister. Gas tank is sealed and vapors travel to a charcoal canister. The canister is purged of vapors by the intake manifold and burned in the engine. The canister is purged of vapors by the intake manifold and burned in the engine.

21 20 Older Style Evap 1) Fresh air enters here 3) Fresh enters here mixes w/fuel vapor 2) Fuel vapor moves to canister 4) Intake vacuum draws vapor to manifold 5) PCM controls flow to manifold 6) Vapor burns in cylinders

22 21 OBDII Evap 1 Fresh air vent controlled by the PCM. Closed when engine is off. Open while engine is running. Vapor management valve. Closed when engine is off. Pulsed when engine is running. PCM monitors pressure in fuel tank. Can cause DTC.

23 22 Heated Air Intake Systems Warms-up inlet air around exhaust manifold. Warms-up inlet air around exhaust manifold. Enhances fuel evaporation for better combustion. Enhances fuel evaporation for better combustion. Maintains a 120˚F air temp. Maintains a 120˚F air temp.

24 23 Heated air intake

25 24 Heated Intake Helps vaporize gasoline in a cold engine.vaporizegasoline Thermostat in the air cleaner horn is connected to the outside of the exhaust manifold.hermostatexhaust manifold engine is cold, the thermostat closes a damper in the air cleaner hornthermostatdamperair cleaner horn air going to the carburetor does not come through the open end of the horn.carburetor Instead the air comes from above the hot exhaust manifold.exhaust manifold Engine warms up, the thermostat opens the damper air is taken in from the end of the horn.thermostat

26 25 Early Fuel Evaporation (EFE) Helps engine warm-up faster. Uses exhaust gas to warm intake manifold. Uses a special passageway under the intake manifold called a crossover. Use mostly on carbureted and throttle body Vee engines. A control valve forces the exhaust gas from one bank to the other. Only operates during the first 5 minutes or so of operation.

27 26 heat crossover: A passage from one exhaust manifold up, over, and under the carburetor and on to the other manifold. Usually found on V-8 or V-6 engines. This crossover provides heat to the carburetor during engine warmup. A passage from one exhaust manifold up, over, and under the carburetor and on to the other manifold. Usually found on V-8 or V-6 engines. This crossover provides heat to the carburetor during engine warmup.exhaust manifoldcarburetor exhaust manifoldcarburetor

28 27 Heat Riser (EFE) An area, surrounding a portion of the intake manifold, through which exhaust gases can pass to heat the fuel mixture during warmup. intake manifold exhaust gases

29 28 heat-control valve: Controlled by temperature changes. ambient temperature is cold or the engine has not warmed up, closed so that some of the hot exhaust gases passes by the intake manifold to pre-heat the fuel mixture going to the cylinders. As the engine warms up, the valve opens up and no exhaust gases pass by the intake manifold. exhaust gases intake manifold cylindersintake manifold If valve does not operate properly, the engine has difficulty in start up or the fuel may cause vapor locking.vapor locking

30 29 Manifold Heat Control improves vaporization improves vaporization improves mixture distribution improves mixture distribution As engine warms up, the thermostatic spring is heated and loses tension As engine warms up, the thermostatic spring is heated and loses tension allows counterweight to change position of heat control valve gradually so that, at higher driving speeds with a thoroughly warmed engine, exhaust gases pass directly to the exhaust pipe and muffler allows counterweight to change position of heat control valve gradually so that, at higher driving speeds with a thoroughly warmed engine, exhaust gases pass directly to the exhaust pipe and muffler

31 30 Exhaust Gas Recirculation (EGR) Used to send some of the exhaust gas back into the cylinders Used to send some of the exhaust gas back into the cylinders Reduce combustion temperatures Reduce combustion temperatures Reduces NOx gases Reduces NOx gases

32 31 AIR INJECTION SYSTEMS Pump air –Exhaust manifold –Catalytic converter Air Pump Air Pump Diverter Valve Diverter Valve One-way Valves One-way Valves Air Switching Valve Air Switching Valve Hoses & Tubing Hoses & Tubing

33 32 Catalytic Converter Contains precious metals Contains precious metals Down Stream O2 Down Stream O2 Re-burner Re-burner 2 way 2 way 3 way 3 way 3 way w/air 3 way w/air aluminum oxide, platinum and palladium carbon monoxide and hydrocarbons to change into water vapor and carbon dioxide

34 33 2 way Two Way Catalyst: Two Way Catalyst: oxidize CO and HC to CO2 and H2O. oxidize CO and HC to CO2 and H2O. Temperature of 200°C for catalyst to "light off". Temperature of 200°C for catalyst to "light off". Above 450°C, oxidation of SO2 to SO3 occurs, combines with water to form sulfuric acid. Above 450°C, oxidation of SO2 to SO3 occurs, combines with water to form sulfuric acid. Leads to the formation of sulfates. (acid rain) Leads to the formation of sulfates. (acid rain) 2-way catalyst may reduce NOx by 10-20 %. 2-way catalyst may reduce NOx by 10-20 %.

35 34 3 way Reactions between CO, HC, and NOx result in the removal of all three major exhaust pollutants. Reactions between CO, HC, and NOx result in the removal of all three major exhaust pollutants. In order to get high conversions of CO and NOx, the air-to-fuel mixture should be held close to the stoichiometric requirement. In order to get high conversions of CO and NOx, the air-to-fuel mixture should be held close to the stoichiometric requirement. If not, conversion of either NOx or CO will deteriorate. If not, conversion of either NOx or CO will deteriorate. Requires monitoring the oxygen in the exhaust gas and using it in a feedback loop to adjust the fuel to air ratio. Requires monitoring the oxygen in the exhaust gas and using it in a feedback loop to adjust the fuel to air ratio. Makes the 3-way closed loop system more expensive than an open loop 2-way, or an open loop 3-way system. Makes the 3-way closed loop system more expensive than an open loop 2-way, or an open loop 3-way system. Some latest catalysts have a NOx reduction of 70-75%. Some latest catalysts have a NOx reduction of 70-75%.

36 35 3 way with air Uses air tube after Rhodium sub straight Uses air tube after Rhodium sub straight Air helps reduce HC & CO Air helps reduce HC & CO

37 36 Test Exhaust Emissions Shop tests: The exhaust is sampled and checked for the following gases. Shop tests: The exhaust is sampled and checked for the following gases. –1 – Hydrocarbons (HC) –2 - Carbon Monoxide (CO) –3 – Carbon Dioxide (CO2) –4 – Oxygen (O2) State Emission Testing: Vehicle run on a dynamometer (IM240 Test) Measures HC, CO, CO2, O2 State Emission Testing: Vehicle run on a dynamometer (IM240 Test) Measures HC, CO, CO2, O2

38 37 Oxygen Sensors

39 38 BAD O2 sensors

40 39 Enhanced Evap. System OP

41 40 EPA EMISSION STANDARDS 1968-1971HC 900 ppmCO 9.0% 1968-1971HC 900 ppmCO 9.0% 1972-1974HC 800 ppmCO 8.0% 1972-1974HC 800 ppmCO 8.0% 1975-1979HC 700 ppmCO 7.0% 1975-1979HC 700 ppmCO 7.0% 1980HC 300 ppmCO 3.0% 1980HC 300 ppmCO 3.0% 1981- onHC 220 ppmCO 1.2% 1981- onHC 220 ppmCO 1.2% I.M. 240 Test I.M. 240 Test

42 41 IM 240 replaced the idle test replaced the idle test measures emissions as the vehicle is driven on a dynamometer measures emissions as the vehicle is driven on a dynamometer taking up to four minutes taking up to four minutes simulates actual urban driving simulates actual urban driving consists of various accelerations, decelerations and cruise speeds up to 57 miles per hour consists of various accelerations, decelerations and cruise speeds up to 57 miles per hour pass/fail standards are more lenient for older vehicles pass/fail standards are more lenient for older vehicles

43 42 OBD2 Testing Uses a scan tool Uses a scan tool Plug in and go Plug in and go Check for codes Check for codes Check sensor operation Check sensor operation Gas cap Gas cap Cayt in place w/ mirror Cayt in place w/ mirror

44 43 OBD III Cell/Satellites? Cell/Satellites?

45 44 GOOD NEWS Emission controls have reduced carbon monoxide and hydrocarbon emissions by about ninety-six percent from pre-control vehicles. Emission controls have reduced carbon monoxide and hydrocarbon emissions by about ninety-six percent from pre-control vehicles. That's almost a hundred percent! That's almost a hundred percent!

46 45 Exhaust Pipe The exhaust pipe is the bent-up or convoluted pipes you will notice underneath your car. The exhaust pipe is the bent-up or convoluted pipes you will notice underneath your car. Some are shaped to go over the rear axle, allowing the rear axle to move up and down without bumping into the exhaust pipe; Some are shaped to go over the rear axle, allowing the rear axle to move up and down without bumping into the exhaust pipe; some are shaped to bend around under the floor of the car, connecting the catalytic converter with the muffler. some are shaped to bend around under the floor of the car, connecting the catalytic converter with the muffler. Exhaust pipes are usually made out of stainless steel, since the high heat conditions involved with the muffler system will cause rust Exhaust pipes are usually made out of stainless steel, since the high heat conditions involved with the muffler system will cause rust

47 46 Reverse-flow Muffler The reverse-flow muffler is oval-shaped and has multiple pipes. The reverse-flow muffler is oval-shaped and has multiple pipes. Four chambers and a double jacket are used to accomplish muffling of the exhaust noise. Four chambers and a double jacket are used to accomplish muffling of the exhaust noise. Exhaust gases are directed to the third chamber, forced forward to the first chamber, from where they travel the length of the muffler and are exhausted into the tail pipe. Exhaust gases are directed to the third chamber, forced forward to the first chamber, from where they travel the length of the muffler and are exhausted into the tail pipe.

48 47 Straight Through Muffler The straight through muffler has a central tube, The straight through muffler has a central tube, perforated with several openings which lead into an outside chamber packed with a sound absorbing (or insulating) material. perforated with several openings which lead into an outside chamber packed with a sound absorbing (or insulating) material. As the exhaust gases expand from the perforated inner pipe into the outer chamber, they come in contact with the insulator and escape to the atmosphere under constant pressure. As the exhaust gases expand from the perforated inner pipe into the outer chamber, they come in contact with the insulator and escape to the atmosphere under constant pressure. Because of this, the expanding chamber tends to equalize or spread the pressure peaks throughout the exhaust from each individual cylinder of the engine. Because of this, the expanding chamber tends to equalize or spread the pressure peaks throughout the exhaust from each individual cylinder of the engine. A V-8 engine requires two exhaust manifolds and either one or two mufflers and often accompanying resonators. A V-8 engine requires two exhaust manifolds and either one or two mufflers and often accompanying resonators. If one muffler is used, the exhaust pipe from one manifold meets the other one in the form of a "Y". If one muffler is used, the exhaust pipe from one manifold meets the other one in the form of a "Y".

49 48 Dual Exhaust System The advantage of a dual exhaust system is that the engine exhausts more freely, The advantage of a dual exhaust system is that the engine exhausts more freely, thereby lowering the back pressure which is inherent in an exhaust system. thereby lowering the back pressure which is inherent in an exhaust system. With a dual exhaust system, a sizable increase in engine horsepower can be obtained With a dual exhaust system, a sizable increase in engine horsepower can be obtained because the "breathing" capacity of the engine is improved, because the "breathing" capacity of the engine is improved, leaving less exhaust gases in the engine at the end of each exhaust stroke. leaving less exhaust gases in the engine at the end of each exhaust stroke. This, in turn, leaves more room for an extra intake of the air-fuel mixture. This, in turn, leaves more room for an extra intake of the air-fuel mixture.


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