Unit injector

In 1911, a patent was issued in Great Britain for a unit injector resembling those in use today to Frederick Lamplough.

[1] Commercial usage of unit injectors in the U.S. began in early 1930s on Winton engines powering locomotives, boats, even US Navy submarines,[2] and in 1934, Arthur Fielden was granted U.S. patent No.1,981,913[3] on the unit injector design[4] later used for the General Motors two-stroke diesel engines.

In 1994, Robert Bosch GmbH supplied the first electronic unit injector for commercial vehicles, and other manufacturers soon followed.

[11] The design of the unit injector eliminates the need for high-pressure fuel pipes, and with that, their associated failures, as well as allowing for much higher injection pressure to occur.

[citation needed] TDI engines incorporating PD unit injector systems manufactured by the Volkswagen Group were also installed on some cars sold in Europe and other markets where the diesel fuel was conveniently priced, amongst those there were some Chrysler/Dodge cars of the DaimlerChrysler era, e.g. the Dodge Calibre (MY07 BKD, MY08 BMR), Dodge Journey, Jeep Compass, Jeep Patriot.

Volkswagen Group major-interest truck and diesel engine maker Scania AB also uses the unit injector system, which they call “Pumpe-Düse-Einspritzung”, or ”PDE”.

The HEUI system has been replaced by many manufacturers with common rail injection solutions, a newer technology, to meet better fuel economy and new emissions standards being introduced.

Early Lucas electronic diesel unit injector
Napier Deltic opposed-piston two-stroke, sectioned. The unit injectors are low down, below the yellow fuel passages, driven by a camshaft to their left and injecting into the centre of the cylinder liner (pale blue).
Animated cut through diagram of a typical fuel injector (click to see animation)
Delphi E1 UI on the Volvo D13A engine
Delphi E1 unit injector parts
Bosch UI on a Scania R164 V8 engine