Delphi Direct Injection High Pressure Fuel Pump

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Fito Coulter

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Aug 3, 2024, 5:12:56 PM8/3/24

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With the launch of the Hartridge Excalibur GDi Master, Delphi is now expanding its GDi service program offering in North America to include GDi and multiport gas fuel injector testing equipment. The Excalibur GDi Master is capable of providing up to 250 bar, and powerful flow and injection per minute rates allow it to test coil and piezo injectors of both GDi & PFI technology types.

Delphi is a leading Tier 1 supplier GDi systems to global OEMs, and is committed to supporting the aftermarket with that OE experience and know-how. We offer multiple GDi specific training classes, an on-demand technician support hotline staffed by ASE certified technicians, and a full line of GDi high pressure fuel pumps. Contact us to learn how to sign up.

A unit injector (UI) is a high-pressure integrated direct fuel injection system for diesel engines, combining the injector nozzle and the injection pump in a single component. The plunger pump used is usually driven by a shared camshaft. In a unit injector, the device is typically lubricated and cooled by the fuel itself.

High-pressure injection delivers power and fuel consumption benefits over earlier lower-pressure fuel injection by injecting fuel as a larger number of smaller droplets, giving a much higher ratio of surface area to volume. This provides improved vaporisation from the surface of the fuel droplets and so more efficient combining of atmospheric oxygen with vaporised fuel, delivering more complete and cleaner combustion.

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. Most mid-sized diesel engines used a single pump and separate injectors, but some makers, such as Detroit Diesel[5] and Electro-Motive Diesel became well known for favouring unit injectors, in which the high-pressure pump is contained within the injector itself. E.W. Kettering's 1951 ASME presentation goes into detail about the development of the modern Unit injector.[6]Also Cummins PT (pressure-time) is a form of unit injection where the fuel injectors are on a common rail fed by a low-pressure pump and the injectors are actuated by a third lobe on the camshaft. The pressure determines how much fuel the injectors get and the time is determined by the cam.

In 1994, Robert Bosch GmbH supplied the first electronic unit injector for commercial vehicles, and other manufacturers soon followed. In 1995, Electromotive Diesel converted its 710 diesel engines to electronic fuel injection, using an EUI which replaces the UI.

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. The unit injector system allows accurate injection timing, and amount of control as in the common rail system .[12]

The unit injector is fitted into the engine cylinder head, where the fuel is supplied via integral ducts machined directly into the cylinder head. Each injector has its own pumping element, and in the case of electronic control, a fuel solenoid valve as well. The fuel system is divided into the low-pressure (

A low-pressure fuel delivery pump supplies filtered diesel fuel into the cylinder head fuel ducts, and into each injector fuel port of constant stroke pump plunger injector, which is overhead camshaft operated.

The use of electronic control allows for special functions; such as temperature controlled injection timing, cylinder balancing (smooth idle), switching off individual cylinders under part load for further reduction in emissions and fuel consumption, and multi-pulse injection (more than one injection occurrence during one engine cycle).

Unit injector fuel systems are being used on a wide variety of vehicles and engines; commercial vehicles from manufacturers such as Volvo, Cummins, Detroit Diesel, CAT, Navistar International and passenger vehicles from manufacturers such as Land Rover and Volkswagen Group, among others, and locomotives from Electromotive Diesel.

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.