Chapter 12 Lesson 3 Engine Design and Classification

Chapter 12 Lesson 3 Engine Design and Classification

Two-Stroke-Cycle Engine �Not used for automotive applications because of high emission levels and poor fuel efficiency �Requires only one revolution of the crankshaft for a complete powerproducing cycle �Two piston strokes complete the intake, compression, power, and exhaust events

Two-Stroke-Cycle Engine Operation �As the piston moves upward, the air-fuel mixture is compressed �Vacuum is created in the crankcase, which draws fuel and oil into the crankcase �A reed valve or rotary valve controls flow into the crankcase

Two-Stroke-Cycle Engine Operation

Two-Stroke-Cycle Engine Operation �When the piston reaches the top of the cylinder, ignition occurs �Burning gases force the piston downward �The reed valve or rotary valve closes, compressing and pressurizing the fuel mixture in the crankcase

Two-Stroke-Cycle Engine Operation �As the piston moves down in the cylinder, it uncovers the exhaust port �Burned gases leave the cylinder �The piston continues downward, uncovering the transfer port �Pressure in the crankcase causes a fresh fuel charge to flow through the transfer port and into the cylinder

Two-Stroke-Cycle Engine Operation

Two-Stroke-Cycle Engine Lubrication �The crankcase is used as a storage chamber for each successive fuel charge �Lubricating oil is introduced into the crankcase along with the air-fuel charge to provide lubrication �Inside the crankcase, some of the oil separates from the fuel �The oil mist lubricates and protects the moving parts inside the engine

Horizontally Opposed Provides the lowest center of gravity of any piston engine

Overhead Cam V-8 Features four chaindriven camshafts and 32 valves

Inline SOHC This 16 valve, fourcylinder engine has a belt-driven camshaft and a balance shaft

Fuel-Injected V-8 This engine uses many aluminum parts

DOHC V-6 Each cylinder head contains two camshafts

V-8 Engine Note the reciprocating assembly and the valve train

Inline Diesel Six-cylinder engine with a rear drive belt for the injection pump

V-12 Engine Two roller chains drive the overhead camshafts