Reciprocating Engine Operating Principles

Reciprocating Engine Operating Principles

1. The relationships between pressure, volume, and temperature of gases are the basic principles of engine operation.

   • Gasoline is vaporized and mixed with air, forced or drawn into a cylinder, compressed by a piston, and then ignited by an electric spark.
     • It requires four strokes of the piston or plunger (two complete turns but of the crankshaft) to complete the thermodynamic cycle of combustion.
       • admission
         • in this phase the descent of the piston sucks the fuel-air mixture in provoked-ignition engines
           • The exhaust valve remains closed, while the intake valve is open.
             • In the first stage the crankshaft rotates 180 ° and the camshaft rotates 90 °.
               • The intake valve is open and the piston stroke is downward.
       • compression
         • upon reaching the end of the lower stroke, the intake valve closes
           • compressing the gas contained in the chamber by the rise of the piston.
             • In the second stage, the crankshaft gives 180 ° and the camshaft gives 90 °
               • and also both valves are closed and their stroke is upward.
       • expansion
         • the end of the upper stroke the gas has reached the maximum pressure.
           • In Induced ignition or Otto cycle engines, the spark jumps in the spark plug.
             • causing the mixture to ignite, while in diesel engines, highly pulverized fuel is injected through the injector
               • the crankshaft rotates 180 ° while the camshaft rotates 90 °
       • exhaust
         • the piston pushes, in its upward movement, the combustion gases
           • that come out through the exhaust valve that remains open.
             • this time the crankshaft rotates 180 ° and the camshaft rotates 90 °
               • the exhaust valve closes and the intake valve opens

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