CCAS%203381%20AUTOMOTIVE%20SKILL%20I

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CCAS 3381 AUTOMOTIVE SKILL I

• INTERNAL COMBUSTION (IC)
• ENGINE

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OBJECTIVES

• To understand the operational principles and
  basic mechanisms of the internal combustion engine

Lecture 1 hour Workshop 1 hour
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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

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

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ENGINE BASICS (4)

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ENGINE BASICS (5)

• Core of engine is cylinder - piston moving up and
  down inside the cylinder (one cylinder)

V
Inline
Boxer
Engine configurations
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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)

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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

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ENGINE BASICS (8)
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ENGINE BASICS (9)
DISPLACEMENT VOLUME
CLEARANCE VOLUME
TDC
BDC
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ENGINE BASICS (10)
Engine Control Unit
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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

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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

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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)

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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)

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ENGINE BASICS (15)
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OTHERS (1)
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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

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THE END
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