Presentation on theme: "SMALL ENGINES ENGINE OPERATION FOR A FOUR STROKE ENGINE."— Presentation transcript:
1 SMALL ENGINESENGINEOPERATION FORA FOUR STROKEENGINE
2 SMALL ENGINESAn engine is a device which converts energy into mechanical motion to do work.Small engines are described as internal combustion engines rated up to 25 horsepower.A small engine has either a spark ignition or a compression ignition based on how the fuel is ignited.Small engines are classified as either four-stroke cycle engines or two-stroke cycle engines.
3 PARTS OF THE ENGINE CYLINDER BLOCK Engine component which consists of the cylinder bore, cooling fins, and valve train components. Made of cast aluminum alloy that are lightweight and dissipate heat rapidly.CYLINDER HEADEngine component made out of cast aluminum alloy fastened to the end of the cylinder block farthest from the crankshaft.COOLING FINSAn integral thin cast strip designed to provide efficient air circulation and dissipation of heat away from the engine cylinder block into the air stream.HEAD GASKETA filler material placed between the cylinder block and cylinder head to seal the combustion chamber. Made of soft metals and graphite layered together.SPARK PLUGComponent that isolates the electricity and produces the spark for the engine
4 PARTS OF THE ENGINE PISTON A cylindrical engine component that slides back and forth in the cylinder bore by forces produced during the combustion process.CONNECTING RODEngine component that transfers motion from the piston to the crankshaft and functions as a lever arm.CRANKSHAFTAn engine component that converts linear (reciprocating) motion of the piston into rotary motion.FLYWHEELA cast iron disk that is mounted at one end of the crankshaft to provide inertia for the engine.COUNTERWEIGHTSA protruding mass cast into the crankshaft which partially balances the forces of a reciprocating piston.
5 PISTON PARTS OF THE ENGINE A cylindrical engine component that slides back and forth in the cylinder bore by forces produced during the combustion process.
6 PISTON PARTS OF THE ENGINE DIFFERENT PISTON TYPES: FLAT DOMED IRREGULARDISHED
7 PISTON PARTS OF THE ENGINE PISTON RINGS:An expandable split ring used to provide a seal between the piston and the cylinder wallThree types:COMPRESSION RINGWIPER RINGOIL RING123
8 VALVE TRAIN PARTS OF THE ENGINE VALVE HEAD MARGIN VALVE FACE VALVE SEATVALVE NECKVALVE GUIDEVALVE SPRINGVALVE ROTATORVALVE SPRING RETAINER
9 INTAKE STROKE COMPRESSION STROKE POWER STROKE EXHAUST STROKE FOUR STROKE CYCLE ENGINEINTAKE STROKECOMPRESSION STROKEPOWER STROKEEXHAUST STROKE
10 INTAKE STROKE Occurs from TDC to BDC Intake valve opens Air-Fuel that was previously mixed in the carburetor is now sucked into the combustion chamber due to the low pressure created inside.
11 COMPRESSION STROKE Compresses the Air-Fuel mixture By compressing the Air-Fuel mixture:Allows for more energy to be released.Increases fuel vaporizationAllows for more complete burning
12 POWER STROKE Spark occurs igniting compressed air-fuel mixture Spark occurs 20 degrees before TDC so the flame front can spread throughout combustion chamberGases ignite pushing piston away from the cylinder headLinear motion from the piston is transferred into a rotary motion on the crankshaft
13 EXHAUST STROKE Exhaust valve opens Inertia from the flywheel and other parts push the piston back up toward TDC, pushing the spent gases out of the combustion chamber.