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Engine Classification. Power & Energy 3201. Outline. Basic Engine Parts Terminology Displacement Compression Ratio Crankshaft Operating Positions Cylinder Arrangements Number of Pistons Fuel Type. Basic Engine Parts. Basic Terminology. Top Dead Centre (TDC)
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Engine Classification Power & Energy 3201
Outline • Basic Engine Parts • Terminology • Displacement • Compression Ratio • Crankshaft Operating Positions • Cylinder Arrangements • Number of Pistons • Fuel Type
Basic Terminology • Top Dead Centre (TDC) • When the piston is at its highest position in the cylinder. • Bottom Dead Centre (BDC) • When the piston is at its lowest position in the cylinder.
Displacement • Engine displacement • Is the volume of space that the piston moves as it moves from TDC to BDC.
Displacement is measured in cubic inches. • Displacement = (3.14)(d2)(s)(n) ÷ 4
Compression Ratio • When the piston is at BDC, the cylinder volume is at its largest. • When the piston is at TDC, the cylinder volume is at its smallest. • Compression Ratio • Is the ratio of the largest cylinder volume to the smallest cylinder volume.
Compression Ratio • Example: If the cylinder volume measures 6 cu. in. when the piston is at BDC, and 1 cu. in. when at TDC, the compression ratio of the engine is 6 to 1 (6:1).
Number of Cylinders/Pistons • Single-cylinder engines • Contain one cylinder and one piston.
Number of Cylinders/Pistons • Multi-cylinder engines • Contain two, four or even more pistons and cylinders.
Cylinder Arrangements • There are 3 types of cylinder arrangements: • Straight or in-line – type • V – type • Opposed type
Cylinder Arrangements • In the straight or in-line arrangement • All the cylinders are positioned in a row. • The most common
Cylinder Arrangements • In the V-type arrangement • The cylinders are angled to create a V shape.
Cylinder Arrangements • In the opposed arrangement • A pair of cylinders is positioned with one directly opposite the other.
Crankshaft Operating Positions • 2 different operating positions for the crankshaft: • Horizontal • Vertical
Crankshaft Operating Positions • In a horizontal crankshaft engine • The crankshaft is positioned horizontally (side-to-side) inside the engine. • Ex: • Snowblower • Chainsaw
Crankshaft Operating Positions • In a Vertical crankshaft engine • The crankshaft is positioned vertically (straight up-and-down) inside the engine. • Ex: • Lawn mower • Ice auger
Fuel Type • Small engines can operate on • Gasoline • Liquefied Petroleum Gas (LP-gas) • Natural Gas • Diesel Fuel
Gasoline • Gasoline is the most popular of all small engine fuels. • Provides more horsepower • Readily Available • Easily transported
LP-Gas • LP-Gas may be propane, butane or a mixture of both. • Burns cleanly. • Emits fewer harmful fumes.
LP-Gas • Requires a different fuel system. • Often used in warehouses (Fork lifts, generators, compressors).
Natural Gas • Burns cleanly • Causes a horsepower loss of around 20% when compared with gasoline. • Requires a different fuel system.
Diesel Fuels • Diesel fuel is injected into the cylinder where it is ignited by the heat of compression. • Diesel engines are much stronger than small gasoline engines. • Small Diesel engines are not as popular as gasoline engines.