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CCAS 3381 AUTOMOTIVE SKILL I

CCAS 3381 AUTOMOTIVE SKILL I. INTERNAL COMBUSTION (IC) ENGINE. OBJECTIVES. To understand the operational principles and basic mechanisms of the internal combustion engine. Lecture – 1 hour Workshop – 1 hour. ENGINE BASICS (1). Purpose of an IC engine

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CCAS 3381 AUTOMOTIVE SKILL I

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  1. CCAS 3381 AUTOMOTIVE SKILL I INTERNAL COMBUSTION (IC) ENGINE

  2. OBJECTIVES • To understand the operational principles and basic mechanisms of the internal combustion engine Lecture – 1 hour Workshop – 1 hour

  3. ENGINE BASICS (1) • Purpose of an IC engine • to convert fuel (petrol, diesel, NGV) into motion to move your car by burning the fuel inside an engine (internal combustion engine) • There are different kinds of IC engines • Spark ignition (SI) or petrol engine • Compression ignition (CI) or diesel engines • Rotary engines • Two-stroke engines (motorbikes) • Each has its own advantages and disadvantages

  4. ENGINE BASICS (2) Rotary engine (Mazda R7) Combustion is key!!!

  5. ENGINE BASICS (3) • Most cars use a four-stroke combustion cycle which consists of: • Intake stroke - piston starts at top, intake valve opens & piston moves down to let the engine take in a cylinder-full of air and fuel (A/F) • Compression stroke - the piston moves back up to compress this A/F. Compression makes the explosion more powerful • Combustion stroke - the piston reaches the top of its stroke, spark plug emits a spark to ignite A/F & explodes driving piston down • Exhaust stroke - the piston hits the bottom of its stroke, exhaust valve opens & exhaust leaves cylinder to go out tail pipe

  6. ENGINE BASICS (4)

  7. ENGINE BASICS (5) • Core of engine is cylinder - piston moving up and down inside the cylinder (one cylinder) V Inline Boxer Engine configurations

  8. ENGINE BASICS (6) • Combustion chamber - area where compression & combustion take place (size of combustion chamber changes) • Difference between max. & min. is called the displacement (measured in liters or CCs) • In a 4-cylinder engine, each cylinder displaces half a liter, then the entire engine is a "2.0 liter engine" • A 2.0 liter engine is roughly half as powerful as a 4.0 liter engine • Displacement (& power) can be increased by increasing no. of cylinders or by making the combustion chambers of all the cylinders bigger (or both)

  9. ENGINE BASICS (7) • Movement of piston from top to bottom - stroke • Top position – top dead center (TDC) • Bottom position – bottom dead center (BDC) • IC engine requires four sub-systems in order to sustain its operations (details are covered in engine sub-systems) • Cooling system • Lubrication system • Fuel (& exhaust) system • Ignition system

  10. ENGINE BASICS (8)

  11. ENGINE BASICS (9) DISPLACEMENT VOLUME CLEARANCE VOLUME TDC BDC

  12. ENGINE BASICS (10) Engine Control Unit

  13. ENGINE BASICS (11) • What Can Go Wrong? • Three fundamentals: • Bad fuel mix • Lack of compression • Lack of spark (Beyond these, thousands of minor things can create problems) • Bad fuel mix • No petrol • Air intake clogged (petrol but no air) • Fuel system supplies too much or too little fuel to the mix • Impurity (water) in the fuel

  14. ENGINE BASICS (12) • What Can Go Wrong? • Lack of compression • Your piston rings are worn (A/F leak) • Intake or exhaust valves leak • Hole in the cylinder (gasket leaks) • Lack of spark (nonexistent or weak) • Spark plug or the wire leading to it is worn out • Ignition system not working properly • Ignition timing is off or bad

  15. ENGINE BASICS (13) • What Can Go Wrong? • Others…. • Battery dead (engine not turning) • Crankshaft bearing jammed • Valves do not open at right time or at all • Exhaust pipe blocked • Engine seized (no oil)

  16. ENGINE BASICS (14) • Overhead camshaft (OHC) • Engines having camshaft mounted above • Overhead valve (OHV) • Valves are mounted in the cylinder head above the combustion chamber (opened and closed by push rods) • Multi-valve engines • Engines having more than one exhaust or intake valve per cylinder • Timing • Delivery of ignition spark, or opening/ closing of engine valves, depending on the piston's position, for the power stroke (timing chain or timing belt)

  17. ENGINE BASICS (15)

  18. OTHERS (1)

  19. OTHERS (2) • Producing More Power • Increase displacement • Increase the compression ratio (requires higher-octane gasoline) • Use turbochargers and superchargers pressurize the incoming air to effectively cram more air into a cylinder • Use intercooler • Put more intake valves (polished intake manifold, bigger air filters) • Put more exhaust valves (dual exhaust pipes, free-flow manifold) • Everything lighter! • Inject fuel

  20. THE END IQ + EQ + SQ = TQ*

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