Internal Combustion Engines - Construction and Working (All you need to know, more than what you need to show)

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Sem 4, PCT Presentation, K. J. Somaiya College of Engineering

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  • 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.
  • PowerSquash Exhaust Intake
  • INLINE 4 V6 FLAT 4
  • C: CrankshaftE: Exhaust valve cam shaftI: Scavenge air valve cam shaftP: PistonR: Connecting rodS: Spark plugV: Valves. Red: exhaust, Blue: intakeW: 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 sowide that it skips or misses at high speeds, causing that cylinder to drag,or the engine to begin to rattle.
  • The drivetrain is the mechanical path by which the enginesends power to the wheels (i.e. provides drive). The drivetrain includes a gearbox, a power transmissionor transfer system i.e. chain and sprocket or drive shaft,a differential, axles, CV joints, wheels and tyres and finallythe braking system.
  • Turbochargers are a type of forced induction system which hasits compressor powered by a gas turbine running off the exhaustgases from the engine.The purpose of a turbocharger is to increase the mass of airentering the engine to create more power. The compressor whichdrives the turbocharger is powered by a turbine driven by theengines own exhaust gases.
  • A carburettor is a device that blends air and fuel for aninternal combustion engine. It was invented by Karl Benzbefore 1885 , patented in 1886. It is colloquially called a carb
  • Fuel injection is a system for mixing fuel with air in aninternal combustion engine. It has become the primary systemused in automotive engines, having almost completely replacedcarburettors in the late 1980s.
  • TYPICAL EFI (ELECTRONIC FUEL INJECTION) COMPONENTS Injectors Fuel Pump Fuel Pressure Regulator ECM - Engine Control Module; includes a digital computer and circuitry to communicate with sensors and control outputs. Wiring Harness Various Sensors (Some of the sensors required are listed here.) o Crank/Cam Position: Hall effect sensor o Airflow: MAF sensor, sometimes inferred with a MAP sensor o Exhaust Gas Oxygen: Oxygen sensor, EGO sensor, UEGO sensor
  • An internal combustion engine would not run for even a fewminutes if the moving parts were allowed to make metal-to-metal contact. The heat generated due to the tremendousamounts of friction would melt the metals, leading to thedestruction of the engine. To prevent this, all moving parts rideon a thin film of oil that is pumped between all the moving partsof the engine.Once between the moving parts, the oil serves two purposes.One purpose is to lubricate the bearing surfaces. The otherpurpose is to cool the bearings by absorbing the friction-generated heat. The flow of oil to the moving parts isaccomplished by the engines internal lubricating system.
  • A Rotary Engine is an internal combustion engine, like the enginein your car, but it works in a completely different way than theconventional piston engine.In a piston engine, the same volume of space (the cylinder)alternately does four different jobs: intake, compression,combustion and exhaust.A rotary engine does these same four jobs, but each onehappens in its own part of the housing. Its kind of like having adedicated cylinder for each of the four jobs, with the pistonmoving continually from one to the next.The rotary engine (originally conceived and developed by Dr.Felix Wankel) is sometimes called a Wankel engine, or Wankelrotary engine.
  • One cycle shownSame process occurring for all sides of body A
  • Engines based on the two-stroke cycle use two strokes (oneup, one down) for every power stroke. Since there are nodedicated intake or exhaust strokes, alternative methodsmust be used to scavenge the cylinders. The most commonmethod in spark-ignition two-strokes is to use thedownward motion of the piston to pressurize fresh chargein the crankcase, which is then blown through the cylinderthrough ports in the cylinder walls.
  • Engines based on the five-stroke cycle are a variant of the four-stroke cycle. Normally, the four cycles are intake, compression,combustion, and exhaust. The fifth cycle added by Delautour isrefrigeration. Engines running on a five-stroke cycle are claimed tobe up to 30% more efficient than equivalent four-stroke engines.The six stroke engine captures the wasted heat from the four-stroke Otto cycle and creates steam, which simultaneously coolsthe engine while providing a free power stroke. This removes theneed for a cooling system making the engine lighter while giving40% increased efficiency over the Otto Cycle. Beare HeadTechnology combines a four-stroke engine bottom-end with aported cylinder which closely resembles that of a two-stroke: thus,4+2 equals a six-stroke cycle. It has an opposing piston that acts inunison with auxiliary low pressure reed and rotary valves, whichallows variable compression and a range of tuning options.