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OPERATION, MAINTENANCE AND REPAIR OF AUXILIARY GENERATORS Episode 3

Tham khảo tài liệu 'operation, maintenance and repair of auxiliary generators episode 3', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | TM 5-685 NAVFAC MO-912 air at 3 pounds per square inch psi to 6 psi to sweep the cylinder further purging the exhaust gas and providing a fresh clean charge for the next cycle. The piston reaches and passes through BDC. The compression stroke then begins again. b. Four-cycle. The series of events taking place in a four-cycle engine are inlet stroke compression stroke expansion or power stroke and exhaust stroke. Four strokes two revolutions of the crankshaft are necessary to complete the cycle. 1 Inlet stroke. As the piston starts downward from TDC the inlet intake valve opens and allows the piston to suck a charge of fresh air into the cylinder. This air may be supplied at a pressure higher than atmospheric air by a supercharger. 2 Compression stroke. As the piston nears BDC the air inlet valve closes sealing the cylinder. Energy supplied by the crankshaft from a flywheel or power from other cylinders forces the piston upward toward TDC rapidly compressing the air and increasing the temperature and pressure within the cylinder. 3 Power stroke. As the piston approaches TDC an amount of fuel modulated by the governor is injected sprayed and atomized into the cylinder which is ignited by the high temperature and combustion starts. Combustion at a controlled rate further increases the temperature and pressure to accelerate the piston toward BDC. The expansion of the hot gases forces the piston down and turns the crank against the load. Engine efficiency depends on the fuel charge being completely burned during the power stroke. 4 Exhaust stroke. As the piston passes through BDC at the end of the power stroke the exhaust valve opens. The piston using stored energy from the flywheel or from the power stroke of another cylinder forces the burned gases from the cylinder through the exhaust port. As the piston approaches TDC the exhaust valve is closed and the air intake valve opens to begin another cycle. c. Engine timing. Engine timing is critical. Intake and exhaust .