How a Diesel Engine Works
In the engines of four-stroke cycle there are four working strokes occupying two complete revolutions of the crankshaft. These four strokes are:
The Intake Stroke. The piston is at the top of the cylinder (top dead centre t.d.c.) being ready to take in a charge of air. The inlet valve is opened, the exhaust valve is closed. The crankshaft is turning. Turning to the right and down, the shaft pulls down the connecting rod and the rod pulls down the piston.
The piston goes down and takes in air into the cylinder through the intake valve. When the piston comes to the bottom of its stroke (bottom dead centre - b.d.c.), the intake valve closes. The cylinder is now full of fresh air.
The Compression Stroke. During this stroke the crankshaft is turning to the left and upward. And the connecting rod pushes the piston upward. The piston moves upward compressing the air charge. Since all valves are closed, the air doesn't escape. The air charge is forced into a smaller space. This increases the pressure of the air and its temperature. When the piston comes to the top center, the air occupies only 1/16 of its original space and its temperature rises to 1,000°F.
The Power Stroke. Now fuel oil is sprayed through the fuel injector into the hot compressed air. The air is so hot that it automatically ignites the oil. The oil burns producing more heat and pressure. This pressure pushes the piston down on the power stroke. The piston goes down. The motion of the piston is transmitted by the connecting rod to the crank. The force on the crank makes the crankshaft turn. Before the piston comes to the bottom center, the exhaust valve is opened. The burnt gases begin to escape through the exhaust valve. This is the end of the power stroke.
The Exhaust Stroke. The cylinder is still full of burnt gases. When the piston rises it pushes out the remaining gases through the exhaust valve. When the piston is at the top center all the burnt gases are exhausted from the cylinder. The exhaust stroke is completed and the engine is ready to begin another cycle.
top dead centre (t.d.c.) верхнее крайнее положение
(верхняя мертвая точка)
bottom dead centre (b.d.c.) нижнее крайнее положение
(нижняя мертвая точка)
working stroke рабочий ход
intake stroke такт впуска
compression stroke такт сжатия
power stroke такт горения-расширения
(рабочий такт, ход)
exhaust stroke такт выпуска
occupy, v занимать
charge, n, v заряд; заряжать
revolution, n оборот
pull, v тянуть, тащить
down = downward, prep вниз
up = upward, prep вверх
reach, v достигать
space, n пространство
rise (rose, risen), v поднимать(ся)
complete, v, adj завершать, (зд.) полный
make, v (зд.) заставлять
heat, n, v тепло; нагревать
remain, v оставаться
increase, v увеличивать
original, adj первоначальный
ignite, v зажигать(ся)
produce, v производить
force, n сила; нагнетать
draw in (drew, drawn), v всасывать
push, v толкать
oil, n (зд.) топливо
still (зд.) все еще