Part of Lesson Plan: **Development of Emissions Controls Devices (updated) by Sergio Marquez
Activity Overview / Details
While lecturing, students will follow along in the text book ( Thomson Delmar Learning, "Automotive Technology: A Systems Approach," 4th edition), pages 786-804.
Start by explaining that in late 1959, California established the first standards for automotive emissions, and in 1967, the Federal Clean Air Act was amended to provide for federal standards that would apply to motor vehicles.
Positive Crankcase Ventilation System (PCV)
The first source of emissions to be brought under control was the blowby in the crankcase, witch was called the Positive Crankcase Ventilation System and designed to route crankcase vapors (blowby) hydrocarbons (HC) and some carbon monoxide (CO) back to the engine's intake manifold. This system was developed and incorporated into the 1961 cars and light trucks sold in California. These systems were installed on all cars nationwide, beginning with the 1963 models. (Show how the system works, locations and parts involved, PCV valve and hoses; refer to fig. 31-9, Page 793.)
Air Injection Reactor (AIR)
The control of unburned hydrocarbons (HC) and carbon monoxide (CO) emissions in the engines exhaust was the next major development. An air injection reactor (AIR) system was built into cars and light trucks sold in California in 1966. (Show how the basic system worked and parts involved, air pump, air manifolds, check valves, air diverter valve and the air bypass valve; see fig. 31-29, page 802.) Other systems, including the controlled combustion system (ignition spark control), were developed and used nationwide in 1968. Further progress in the following years improved combustion to reduce hydrocarbons (HC) and carbon monoxide (CO) emissions.
Evaporation Control System (EVAP)
Fuel vapors from the gasoline tank and the carburator float bowl were brought under control with the introduction of Evaporation Control System (evap) . These systems were first installed in 1970 model cars sold in California and in most cars made domestically, beginning with 1971 models. This system reduced fuel vapors ( hydrocarbons) (HC), to escape into the atmosphere. (Show how the basic system worked and parts involved, a specially designed fuel tank, carbon cannister, vapor tubing and hoses and fuel vapor separator; see fig. 31-3, page 789.)
Exhaust Gas Recirculation (EGR)
Most vehicle manufacturers started to provide emission conrtol systems that reduced oxides of nitrogen (nox) (produced from the high heat in the combustion chamber) as early as 1970. The Exhaust Gas Recirculation (egr) used on some 1972 models was used extensively for 1973 models when the federal standards for oxides of nitrogen (nox) took effect. (Show how the basic systems evolved, worked and parts involved, EGR valve, thermal vacuum control valve and transducer; see fig. 31-19, page 796.)
Catalytic Converter (CAT)
One of the most important developments for lowering emission levels has been the availability and use of unleaded gasoline. Since 1971, engines have been designed to operate on unleaded fuels. This had several benefits: no lead particles and deposits in the exhaust, increase in spark plug life, and the most important, introduction of the catalytic Converter (CAT), beginning with the 1975 model year. Converters dramatically reducing emissions by provided a means of oxidizing the Carbon monoxid (CO) and hydrocarbons (HC). (See figs. 31-26 and 31-27, pages 800 and 801.)
Close the lecture by saying that the most concern to enviromentalists, engineers, and technicians are HC, CO, and NOx. CO2 and O2 are not pollutants, but are monitored because they are indicators of combustion efficiency.
Materials / Resource
- Emission Pict. 001.jpg [ View Image ] [ Download Original ] null
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