Fuel injection
This article focuses on fuel injection in reciprocating piston and Wankel rotary engines.
The term fuel injection is vague and comprises various distinct systems with fundamentally different functional principles.
The injector is located in the combustion chamber, inlet manifold or – less commonly – the throttle body.
Typically, hydraulic direct injection systems spray fuel into the air inside the cylinder or combustion chamber.
[5] Third-generation common-rail diesels use piezoelectric injectors for increased precision, with fuel pressures up to 300 MPa or 44,000 psi.
As in a carburetted induction system, the fuel is mixed with the air before entering the intake manifold.
[15] Single-point injection was a relatively low-cost way for automakers to reduce exhaust emissions to comply with tightening regulations while providing better "driveability" (easy starting, smooth running, no engine stuttering) than could be obtained with a carburettor.
Many of the carburettor's supporting components—such as the air filter, intake manifold, and fuel line routing—could be used with few or no changes.
[23]: 415 In the meantime, the first manifold injection system was designed by Johannes Spiel in 1884, while working at Hallesche Maschinenfabrik in Germany.
[25][26] This design, called a hot-bulb engine used a 'jerk pump' to dispense fuel oil at high pressure to an injector.
Another development in early diesel engines was the pre-combustion chamber, which was invented in 1919 by Prosper l'Orange[27] to avoid the drawbacks of air-blast injection systems.
In 1898, German company Deutz AG started producing four-stroke petrol stationary engines[28] with manifold injection.
[30][31] This engine could run on a variety of fuels (such as oil, kerosene, petrol or diesel oil)[32] and used a stratified charge principle whereby fuel is injected towards the end of the compression stroke, then ignited with a spark plug.
[34] During World War II, several petrol engines for aircraft used direct-injection systems, such as the European Junkers Jumo 210, Daimler-Benz DB 601, BMW 801, and the Shvetsov ASh-82FN (M-82FN).
In 1943, a low-pressure fuel injection system was added to the Nakajima Homare Model 23 radial engine.
This mechanically-controlled system was essentially a specially lubricated high-pressure diesel direct-injection pump of the type that is governed by the vacuum behind an intake throttle valve.
[37] A Bosch mechanical direct-injection system was also used in the straight-eight used in the 1954 Mercedes-Benz W196 Formula One racing car.
Lucas Industries had begun developing a fuel injection system in 1941 and by 1956 it was used in the Jaguar racing cars.
[41] At the 1957 24 Hours of Le Mans, the 1st to 4th placed cars were Jaguar D-Type entries using a Lucas fuel injection system.
[42] Also in 1957, General Motors introduced the Rochester Ramjet option, consisting of a fuel injection system for the V8 engine in the Chevrolet Corvette.
The Electrojector was intended to be available for the Rambler Rebel mid-size car, however reliability problems meant that the fuel injection option was not offered.
K-Jetronic was a mechanical injection system, using a plunger actuated by the intake manifold pressure which then controlled the fuel flow to the injectors.
Since the 2010s, many petrol engines have switched to direct-injection (sometimes in combination with separate manifold injectors for each cylinder).
