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Chapter 3 Engine Operation

Engine Components • Four-Stroke Cycle Engines • Two-Stroke Cycle Engines • Valving Systems • Diesel Engines • Rotary Engines • Engine Output

Chapter 3 — Engine Operation

Competencies

     List the components of an engine block.

Describe a cylinder head.

Explain the operation and components of a crankshaft.

Describe pistons and piston rings.

Explain the function of connecting rods and bearings.

Chapter 3 — Engine Operation

Competencies

     Describe the flywheel and valve train.

Compare the operation of four-stroke cycle and two stroke cycle engines.

Describe valving systems.

Explain important features of diesel engines.

Explain measurement of engine output.

Chapter 3 — Engine Operation

Engine Blocks

 cylinder block  cylinder bore  cooling fins  valve train components  crankcase

Chapter 3 — Engine Operation

Cylinder Heads

 engine component fastened to the end of the cylinder block farthest from the crankshaft  head gasket is filler material

Chapter 3 — Engine Operation

Crankshafts

     convert linear motion of pistons to rotary motion crankpin journal bearing journal counterweight crankgear

Chapter 3 — Engine Operation

Pistons

 slide back and forth in the cylinder bore     piston pin skirt ring groove piston ring

Chapter 3 — Engine Operation

Connecting Rods and Bearings

 connecting rod transfers motion from piston to crankshaft  bearings reduce friction, maintain clearance

Chapter 3 — Engine Operation

Flywheels and Valve Trains

 a flywheel is a disk mounted at one end of a crankshaft  provides inertia for the engine  maintains crankshaft rotation between combustion intervals  a valve train controls the flow of gases into and out of the combustion chamber

Chapter 3 — Engine Operation

Engine Operation

 intake event  introduces air and fuel (or just air in a diesel engine) to the combustion chamber  piston moves from TCD to BDC  compression event  air and fuel (or just air in a diesel engine) in combustion chamber is compressed in the cylinder

Chapter 3 — Engine Operation

Engine Operation

 ignition (combustion) event  charge is ignited and rapidly oxidized to release energy  power event  expanding gases force the piston head away from the cylinder head

Chapter 3 — Engine Operation

Engine Operation

 exhaust event  spent gases are removed from the chamber and released to atmosphere  valve overlap is the point when both intake and exhaust valves are open

Chapter 3 — Engine Operation

Valving Systems

 seal the combustion chamber to control flow of air-fuel mixture into the cylinder and exhaust gases out of the cylinder  commonly two valves per system, intake and exhaust  location of valve determines type of head design

Chapter 3 — Engine Operation

Diesel Engines

 injector is hydraulically activated by pressurized fuel delivered by the injection pump  heat in glow plug is created by resistance to current in a heating coil

Chapter 3 — Engine Operation

Diesel Engines

 five events in operation  intake   compression ignition  power  exhaust  turbocharging uses a compressor

Chapter 3 — Engine Operation

Engine Output

  measured by torque and horsepower units of measurement of horsepower  brake, friction, and indicated horsepower  dynamometer measures torque, load, speed, and horsepower

Chapter 3 — Engine Operation

Engine Output

 factors affecting engine output   displacement volumetric efficiency   thermal efficiency air density

Chapter 3 — Engine Operation

Chapter 3 Review

What is the function of a crankshaft?

 A crankshaft is an engine component that converts the linear (reciprocating) motion of the piston into rotary motion.

What are the five events of four-stroke cycle engines?

 The five events of four-stroke cycle engines are intake, compression, ignition, power, and exhaust.