Primer on Automobile Fuel Efficiency and Emissions - Pollution Probe

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% % % % How an Internal Combustion Engine Works: Conventional automobiles are powered by an internal combustion engine, a piston-and-crank device that converts fuel energy (i.e., chemical potential energy) into rotational motion (i.e., kinetic energy). The operating principle is quite simple and has been employed in various types of engines for hundreds of years. Basically, what happens is this: Air is drawn into the engine where it combusts fuel inside closed cylinders. The fuel combustion process produces heat (i.e., the chemical potential energy of the fuel is converted into heat energy). Combustion also produces a collection of gases that comprise the combustion products (as explained in chapter one). The heat causes the gases to expand inside the cylinder, building pressure. Inside each cylinder is a moving piston that is forced downward due to increased pressure from the expanding gases. As the cycle repeats, the piston moves up-and-down inside the cylinder. The piston is also connected to a crank shaft beneath the cylinder by a connecting rod, and for each up-and-down motion of the piston the crank shaft rotates once. This is exactly the same as a bicycle crank, which rotates as you force each pedal downwards – your legs perform the same function on a bicycle as do pistons in an engine (see Figure 2-1). For each cycle, the second downward stroke of the piston is called the power stroke, since this is when the piston delivers power to the crankshaft. The rotating crankshaft is the primary source of mechanical, rotating energy that drives all other systems in the automobile. The energy to turn the wheels, charge the battery, drive the pumps and provide power for all electrical components is supplied by the crankshaft. 4-stroke engine combustion chamber spark plug 1. Intake Stroke: The intake valve is open, the exhaust valve closed. The piston descends from the top of the cylinder drawing in a mixture of fuel and air through the intake valve. intake valve cylinder exhaust valve 2. Compression Stroke: The intake valve closes, the piston rises in the cylinder, squeezing the air-fuel mixture into an area around the spark plug, called the combustion chamber. piston 3. Power Stroke: The air-fuel mixture is then ignited by the spark plug. The resulting pressure from the expansion of burning gases drives the piston down. Intake Compression Power crankshaft Exhaust 1 2 3 4 4. Exhaust Stroke: The exhaust valve opens and the piston rises to push the products of combustion from the cylinder through the valve. The intake valve opens again, the exhaust valve closes, and the cycle starts over. 33 Chapter 2 | Automobile Energy Use, Efficiency and Emissions Explained
The combustion products then exit the engine and enter the exhaust system. The exhaust system is connected to the engine and channels the flow of combustion gases through emission and noise control devices (e.g., catalytic converter and resonator/muffler systems) before exiting the tailpipe as emissions. As it leaves the engine, the temperature of combustion gases can reach 2,000˚C or more, but are much lower by the time they exit the exhaust pipe. Reviewing the process by which air is drawn into the engine, it can be seen that the engine essentially acts as an elaborate, self-powered pumping system; air is mixed with fuel and burned, then forced out through the exhaust system, essentially converting some of the energy potential of the fuel into rotational energy at the crankshaft. The rate at which fuel is combusted determines the power. Power is the rate at which energy is supplied (i.e., converted into useful work). Adding more cylinders to the engine means that more pistons can deliver power to the crankshaft (i.e., more pistons are like more legs, each pumping the crank of a bicycle). The timing of the pistons’ strokes can be engineered to ensure that the crankshaft delivers a smooth, consistent supply of power to the automobile. Another important factor that determines the power output is the compression ratio (see Figure 2-2). The ratio of the volumes occupied by the gases inside a cylinder at the beginning and end positions of a piston’s stroke is called the compression ratio. FIGURE 2-1 How the crankshaft works 2 3 4 1 piston crankshaft connecting rod flywheel The crankshaft converts reciprocating motion to rotary motion. Cyclists demonstrate how a bike’s pedals and crank convert the up-and-down motion of the rider’s legs into the rotary motion of the sprocket wheels. Similarly, the connecting rods and crankshaft, the two pistons at the top of their strokes (2 and 3) are balanced by two at the bottom of their strokes (1 and 4). <strong>Primer</strong> on Automobile Fuel Efficiency & Emissions 34
Page 1 and 2: PRIMER ON AUTOMOBILE FUEL EFFICIENC
Page 3 and 4: POLLUTION PROBE’S PRIMER SERIES P
Page 5 and 6: JUNE 2009 Pollution Probe is please
Page 7 and 8: D R A F T C O P Y D R A F T C O P Y
Page 9 and 10: Chapter 5 BACKGROUND ON FUEL EFFICI
Page 11 and 12: CHAPTER 1 | EMISSIONS FROM AUTOMOBI
Page 13 and 14: ways to power automobiles, such as
Page 15 and 16: In the real world, however, combust
Page 17 and 18: TABLE 1-1, CONTINUED OXIDES OF NITR
Page 19 and 20: TABLE 1-1, CONTINUED OXIDES OF SULP
Page 21 and 22: This “enhanced greenhouse effect
Page 24 and 25: CHAPTER Chapter 2 TWO D R A F T C O
Page 26 and 27: BOX 2-1 Fuel economy improvements v
Page 28 and 29: Five Automobile Subsystems, continu
Page 30 and 31: Five Automobile Subsystems, continu
Page 32 and 33: % Energy Flow Within A Vehicle (val
Page 36 and 37: The higher the compression ratio of
Page 38 and 39: Major forces on an automobile in mo
Page 40 and 41: Inertia To increase speed, the engi
Page 42 and 43: CHAPTER THREE INCREASING Chapter 3
Page 44 and 45: Vehicle Weight, Safety and Fuel Eff
Page 46 and 47: FIGURE 3-1 Engine Size: Power versu
Page 48 and 49: Turbocharging and Supercharging Mos
Page 50 and 51: Table 3-2: Engine Technology and Fu
Page 52 and 53: Gasoline versus Diesel engines: Gas
Page 54 and 55: Reducing Drivetrain losses The Tran
Page 56 and 57: call parasitic loads on the cranksh
Page 58: Hybrid Electric Vehicles Today, the
Page 61 and 62: Parallel Architecture Internal Comb
Page 63 and 64: these battery options is expected t
Page 65 and 66: CHAPTER 4 | WHAT YOU CAN DO TO MAXI
Page 67 and 68: A poorly operating Emission Control
Page 69 and 70: Table 4-2: Aerodynamics and Roof Ra
Page 71 and 72: Plan trips wisely. When doing erran
Page 73 and 74: Consider your fuel options. Unless
Page 76 and 77: Purchasing a Vehicle When it comes
Page 78 and 79: A fuel consumption gauge is an inst
Page 80 and 81: CHAPTER FIVE BACKGROUND ON FUEL EFF
Page 82 and 83: and heavy. On average, the 1974 mod
Page 84 and 85:
Fuel Efficiency Trends As discussed
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Table 5-1: CAFC Targets CAFC Standa
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egulations have been implemented wi
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U.S Federal Tier 1 Emissions Standa
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Table 5-3: California LEV II Emissi
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CHAPTER 6 | WHAT IS BEING DONE BY G
Page 97 and 98:
Table 6-1: Green Levy Tax Rates Com
Page 99 and 100:
ONTARIO Sales Tax Rebate — People
Page 101 and 102:
sideration that will force automake
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of about €5,000 (CA$8,400) for th
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CHAPTER 7 | WHAT NEEDS TO BE DONE E
Page 107 and 108:
EcoMobility for a Cleaner Environme
Page 109 and 110:
This should also benefit automakers
Page 112:
TORONTO OFFICE: 625 Church Street S
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