ReciprocatingEngine Review

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Reciprocating Engines

Mechanical SystemCylinder

Known as the engine’s combustion chamber

Where the power is developed

Mechanical SystemPiston

Fits snugly in the hollow cylinder allowing up-and-down linear

(straight) motion

Fit will not allow air or fluid in the cylinder

Mechanical System Crankshaft

• The crankshaft and connecting rod allow for the movement of the propeller.

Mechanical System Connecting Rod

• Attached to the throws

• With the crankshaft, they change the direction of the pistons into a circular motion

Mechanical SystemValves

• A rocker arm regulates the opening and closing of

each valve.

• Lobes or rings on a camshaft push the rocker arm

Spark Plug

• Internal combustion engines are– spark-ignition engines, which

require spark plugs to begin combustion, and

– compression-ignition engines (diesel engines), which compress the air and then inject diesel fuel into the heated compressed air mixture where it auto-ignites.

Mechanical System Cylinder

Piston

Crankshaft

Connecting Rod

Valves

Spark plug

Mechanical System

Four-Stroke Cycle • Occurs at the same time in all

cylinders, but not on the same step

• Ignition sequence of the cylinders called the firing order

Four-Stroke Cycle

Types of Reciprocating Engines

How to get more horsepower from an engine?

(1) Increase the number of cylinders or (2) Increase the size of each cylinder

Attention focused on designs

Types of Reciprocating Engines

In-line Engines

• Cylinders are located in a row, one behind the other

• Two classifications:

• Upright

• Inverted

Types of Reciprocating Engines

Opposed Engines

Two rows or banks of cylinders on each side of the crankshaft

Rows directly opposite each other called horizontal opposed

Types of Reciprocating Engines

V and X Engine

• “V” engine features two rows of cylinders set at an angle of about 45°

• The “X” engine is essentially an opposed “V” engine

Types of Reciprocating Engines

Radial Engine

• Crankshaft with only one throw• Odd number of cylinders in each bank or row • Maximum number of cylinders in each bank is nine

Radial Engine

Construction of Reciprocating Engines

Cylinder andhead of thecylinder

Made of high-grade steel; allow machining to very closespecifications.

Cylinder barrel(body of thecylinder)

Made of cast or forged aluminum alloy and is shrunk onto thecylinder barrel.

Valves Made of tungsten steel or chromium steel which providesstrength at high temperatures.

Pistons Made of forged or cast aluminum.

Crankshaft Made of chromium steel.

Fuels Used in Reciprocating Engines

• Most common form of fuels is hydrocarbons derived from petroleum

• Gasoline and kerosene offer several advantages•Mix easy with air•Low flash point•High heat content - power