AND THEIR APPLICATIONS - BU Shoubra/Mechanical... · Spark plug gapping: The centre electrode (dark rod) is a cylindrical rod, and the top ground electrode (a hook) has square edges.

AND THEIR

A P P L I C A T I O N S

A PRESENTATION

SEPTEMBER 2016

An Introduction

The internal combustion (IC) engine converts chemical energy into useful mechanical energy by burning fuel.

Chemical energy is released when the fuel-air mixture is ignited by the spark in the combustion chamber.

The gas produced in this reaction rapidly expands forcing the piston down the cylinder on the power stroke.

Power

Exhaust

Intake

Squash

INLINE 4 V6

FLAT 4

EXHAUST SYSTEM

C: Crankshaft E: Exhaust valve cam shaft I: Scavenge air valve cam shaft P: Piston R: Connecting rod S: Spark plug V: Valves. Red: exhaust, Blue: intake W: Cooling water ducts

•The crankshaft, sometimes casually abbreviated to crank, is the part of an engine which translates reciprocating linear piston motion into rotation. •To convert the reciprocating motion into rotation, the crankshaft has "crank throws" or "crankpins"

•In a reciprocating piston engine, the connecting rod or conrod connects the piston to the crank or crankshaft. •The connecting rod was invented sometime between 1174 and 1200

•The camshaft is an apparatus often used in piston engines to operate poppet valves. •It consists of a cylindrical rod running the length of the cylinder bank with a number of oblong lobes or cams protruding from it, one for each valve.

• A spark plug is an electrical device that fits into the cylinder head of internal combustion engines and ignites compressed aerosol gasoline by means of an electric spark. • Internal combustion engines can be divided into 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.

Spark plug gapping: The centre electrode (dark rod) is a cylindrical rod, and the top ground electrode (a hook) has square edges. When regapping, the hook is raised or lowered to adjust the gap, often to 0.035 to 0.050 inches.

The main issues with spark plug gaps are: · Narrow-Gap risk: spark might be too weak/small to ignite fuel; · Narrow-Gap benefit: plug always fires on each cycle; · Wide-Gap risk: plug might not fire, or miss at high speeds; · Wide-Gap benefit: spark is strong for a clean burn.

A properly gapped plug will be wide enough to burn hot, but not so wide that it skips or misses at high speeds, causing that cylinder to drag, or the engine to begin to rattle.