kristina25l

13.03.2023 04:49 •  Английский язык

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(английский язык)

The two primary categories of engines are the spark ignition (Otto-cycle) and the compression ignition (Diesel-cycle). In the spark ignition engine, the fuel is metered and introduced into the engine by either a carburetor or an injection system, When a carburetor is used, the fuel is metered by jets and orifices in the carburetor and added to the air as it flows through the venturi of the carburetor. Mixing occurs as the fuel–air mixture moves through the intake system and into the cylinder. A spark plug ignites the fuel–air mixture at the proper time. Fuel injection systems improve the fuel efficiency of a gasoline engine because the multiple sensors and computer can better match the fuel needs of the engine. Historically the additional cost of the system over a carburetor fuel system has limited its use to larger, multicylinder engines, but rising fuel costs and emission standards have been the impetus for increasing the use of fuel injection systems on smaller engines. An engine that uses injection does not have a carburetor; the fuel

is usually injected into the air stream at the throttle body or intake port. In some engines, a single injector is located at the throttle body (throttle body injection) that replaces the carburetor. This single injector meters the fuel for all of the cylinders. In the port injection system, an injector is positioned just outside the intake valve (port) leading into each cylinder.