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PISTON ENGINE PROPULSION

PISTON ENGINE PROPULSION. Chapter 2. The Four Stroke Cycle. 2014 Hyundai Engine. 1933 Alvis Engine. The Four Stroke Cycle. BUT HOW DOES IT WORK EXACTLY?. LET’S LOOK IN MORE DETAIL. The Four Stroke Cycle. Operating Cycle. 1. INDUCTION. Air and fuel mixture is sucked into the cylinder.

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PISTON ENGINE PROPULSION

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  1. PISTON ENGINE PROPULSION Chapter 2 The Four Stroke Cycle 2014 Hyundai Engine 1933 Alvis Engine

  2. The Four Stroke Cycle BUT HOW DOES IT WORK EXACTLY? LET’S LOOK IN MORE DETAIL

  3. The Four Stroke Cycle Operating Cycle 1. INDUCTION Air and fuel mixture is sucked into the cylinder. Known as SUCK 2. COMPRESSION Air and fuel mixture is compressed by the piston. Known as SQUEEZE 3. COMBUSTION Air and fuel mixture is ignited and the piston is pushed down. Known as BANG 4. EXHAUST Burnt gas is pushed out by piston. Known as BLOW SUCK, SQUEEZE, BANG, BLOW Which gives:

  4. The Four Stroke Cycle Operating Cycle

  5. The Four Stroke Cycle Operating Cycle Down Up Up Down Therefore a ‘Four’ Stroke engine is 2 revs of the crankshaft 1 ‘Stroke’ = the piston sliding either up or down the cylinder

  6. The Four Stroke Cycle Operating Cycle PISTON MOVES DOWN CYLINDER AIR/FUEL DRAWN (INDUCED - SUCKED) INTO CYLINDER CRANK ROTATES TDC STROKE 1 BDC

  7. The Four Stroke Cycle Operating Cycle PISTON MOVES BACK UP CYLINDER AIR/FUEL TRAPPED (COMPRESSED - SQUEEZED) IN CYLINDER CRANK CONTINUES TO ROTATE TDC STROKE 2 BDC

  8. The Four Stroke Cycle Operating Cycle PISTON FORCED DOWN CYLINDER AIR/FUEL IGNITED AND BURNS (COMBUSTION - BLOW) IN CYLINDER CRANK STARTS 2ND ROTATION TDC STROKE 3 BDC

  9. The Four Stroke Cycle PISTON MOVES BACK UP CYLINDER AGAIN Operating Cycle BURNT AIR/FUEL PUSHED OUT OF CYLINDER (EXHAUST – BLOW) CRANK CONTINUES 2ND ROTATION TDC STROKE 4 BDC

  10. The Four Stroke Cycle Operating Cycle It is of course the start of the induction stroke When the end of the exhaust stroke is reached And the whole process starts again

  11. The Four Stroke Cycle Operating Cycle But :- Because valves don’t open and close instantly, and The air/fuel mixture doesn’t explode instantly (it’s a rapid burning process) Valve operation and air/fuel ignition are’nt set at the TDC and BDC positions. These events are set to occur at the following positions, designated as angular positions of the crank shaft.

  12. The Four Stroke Cycle Operating Cycle At which point, the Inlet valve begins to open The start of Induction – Stroke 1 TDC We’ll start the process at 30 degrees before TDC BDC

  13. The Four Stroke Cycle Operating Cycle When the Inlet valve closes The start of Compression – Stroke 2 TDC The induction stroke ends at 15 degrees after BDC. Inlet valve opens Trapping the air/fuel mixture in the cylinder 1. Induction Inlet valve closes Called Valve Lag because it is after BDC BDC

  14. The Four Stroke Cycle Operating Cycle At this point, both valves are closed Ignition The start of Power – Stroke 3 Inlet valve opens TDC Ignition occurs at 30 degrees before TDC. 1. Induction 2. Compression And is the start of the Power stroke BDC Inlet valve closes

  15. The Four Stroke Cycle Operating Cycle 15 degrees before BDC, the exhaust valve opens The start of Exhaust – Stroke 4 Burning air/fuel mixture reaches maximum expansion Inlet valve opens TDC And is the end of the Power stroke and start of the Exhaust stroke Ignition 2. Compression 3. Power 1. Induction Called Valve Lead because it is before BDC Exhaust valve opens BDC Inlet valve closes

  16. The Four Stroke Cycle Operating Cycle So as the exhaust valve starts to close, the inlet valve starts to open The end of Exhaust – Stroke 4 TDC This position is towards the end of the Exhaust stroke Ignition Inlet valve opens 2. Compression 3. Power 1. Induction 4. Exhaust And is ALSO the beginning of the Induction stroke Exhaust valve opens BDC Inlet valve closes

  17. The Four Stroke Cycle Operating Cycle Both the inlet and exhaust valves are partially open Valve Overlap - Stroke 4 to 1 Exhaust valve closes Inlet valve opens TDC This is called ‘Valve Overlap’ Ignition 2. Compression 3. Power 1. Induction 4. Exhaust Therefore the Induction stroke starts 45 degreesbefore the end of the Exhaust stroke Exhaust valve opens BDC Inlet valve closes

  18. The Four Stroke Cycle Operating Cycle The exhaust valve is now closed The inlet valve is now open The start of Induction – Stroke 1 Exhaust valve closes Inlet valve opens This position is at the end of the exhaust stroke TDC Ignition 2. Compression 3. Power 1. Induction 4. Exhaust And is 45 degrees into the induction stroke Exhaust valve opens BDC Inlet valve closes

  19. The Four Stroke Cycle Operating Cycle Simple isn’t it! Suck Squeeze Bang Blow

  20. The Four Stroke Cycle Operating Cycle But, this is happening in every cylinder in all 4 stroke engines no matter how many cylinders there are. Lets look at the most typical vehicle engine, the‘Inline 4’

  21. The Four Stroke Cycle Operating Cycle The cylinders are numbered from to the rear the front

  22. The Four Stroke Cycle Operating Cycle 1 – 3 – 4 - 2 And the firing order is:-

  23. The Four Stroke Cycle Operating Cycle

  24. The Four Stroke Cycle Operating Cycle

  25. The Four Stroke Cycle Operating Cycle

  26. The Four Stroke Cycle Operating Cycle

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