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Early Lucas electronic diesel unit injector
Delphi E1 Diesel Electronic Unit Injector
Unit Injector (abbrev. UI) is an integrated direct fuel injection system for diesel engines; combining the injector nozzle and the injection pump in a single component, the pump of which is (usually) driven by the engine camshaft.
History
Unit Injector systems were commonly associated as Detroit Diesel Allison fuel systems, however in 1911, a patent was issued in Great Britain for an unit injector resembling those in use today to Frederick Lamplough.
Commercial usage of unit injectors in the U.S. began in early 1930s on Winton engines powering the locomotives, boats even US Navy submarines,, and in 1934, Arthur Fielden was granted U.S. patent No.1,981,913 on the unit injector design later used for the General Motors two stroke diesel engines.
In 1994, Robert Bosch GmbH supplied first electronic Unit Injector for commercial vehicles, and other manufacturers soon followed.
Today, major manufacturers include Robert Bosch GmbH, CAT, Cummins, Delphi Corp., Detroit Diesel Allison and the Delphi Corp. acquired Lucas Automotive.
Design and technology
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 control as in the common rail system .
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 (<500 kPa) fuel supply system, and the high pressure injection system (<2000 bar).
Operation principle
Delphi E1 UI on the Volvo D13A engine
Delphi E1 UI parts
The basic operation can be described as a sequence of four separate phases: the filling phase, the spill phase, the injection phase, and the pressure reduction phase.
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.
Fill phase
The constant stroke pump element on the way up draws fuel from the supply duct in to the chamber, and as long as electric solenoid valve remains de-energized fuel line is open.
Spill phase
The pump element is on the way down, and as long as solenoid valve remains de-energized the fuel line is open and fuel flows in through into the return duct.
Injection phase
The pump element is still on the way down, the solenoid is now energized and fuel line is now closed. The fuel can not pass back into return duct, and is now compressed by the plunger until pressure exceeds specific "opening" pressure, and the injector nozzle needle lifts, allowing fuel to be injected into the combustion chamber.
Pressure reduction phase
The plunger is still on its way down, the engine ECU de-energizes the solenoid when required quantity of fuel is delivered, the fuel valve opens, fuel can flow back into return duct, causing pressure drop, which in turn causes the injector nozzle needle to shut, hence no more fuel is injected.
Summary
The start of an injection is controlled by the solenoid closing point, and the injected fuel quantity is determined by the closing time, which is the length of time the solenoid remains closed. The solenoid operation is fully controlled by the engine ECU.
Additional functions
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).
Further development and applications
In 1993, CAT introduced "Hydraulically-actuated Electronic Unit Injection" (HEUI), where the injectors are no longer camshaft operated. First available on Navistar's 7.3 litres (445.5 cu in), V8 diesel engine. HEUI uses engine oil pressure to power high pressure fuel injection, where usual method of unit injector operation is the engine camshaft.
Unit injector fuel systems are being used on wide variety of vehicles and engines from various manufacturers, e.g. Volvo, Cummins, Detroit, CAT for commercial vehicles, and as well as for passenger vehicles e.g. Land Rover, Volkswagen Group (Volkswagen AG), among others.
Bosch UI on Scania R164 V8
The Volkswagen Group mainstream marques use unit injector systems (branded "Pumpe Dse", commonly appreviated to "PD") in their Suction Diesel Injection (SDI) and Turbocharged Direct Injection (TDI) diesel engines.
In North America, the Volkswagen Jetta, Golf, and New Beetle TDI 2004-2006 are Mk4 Pumpe Dse (newer models use Mk5 BEW engines and older models use ALH engines).[citation needed]
Volkswagen Group major-interest truck and diesel engine maker Scania AB also use the unit injector system, which they call "Pumpe-Dse-Einspritzung", or "PDE".
See also
unit pump
References
Diesel Fuel Injection published by Robert Bosch GmbH, 1994 ISBN 1-56091-542-0
Diesel Engines and Fuel Systems by A. Asmus & B. Wellington, 1988 ISBN 0-7299-0013-4
^ Asmus, A; Wellington B. Diesel Engines and Fuel System. ISBN 1-56091-542-0.
^ "History of fuel injection" (PDF). by Frank DeLuca, Chief Fuel Injection Engineer, of American Bosch Arma Corporation. http://www.disa.it/pdf/01HystoryOfDieselFuelInj.pdf. Retrieved 28 November 2009.
^ "The Winton 201A Diesel Engine". http://www.rypn.org/RyPN/articles/viewarticles.asp?filename=061130231209.txt. Retrieved 28 November 2009.
^ "United States Patent 1981913". http://www.freepatentsonline.com/1981913.html. Retrieved 28 November 2009.
^ "A. Fielden Fuel Pump" (PDF). http://www.freepatentsonline.com/1981913.pdf. Retrieved 28 November 2009.
^ "HEUI Fuel Systems" (PDF). Caterpillar Inc.. Cat.com. 1999. http://www.cat.com/cda/files/87775/7/pehp9526.pdf. Retrieved 4 November 2009.
^ Pressure Injection (HPI) Systems "Fuel Systems - High Pressure Injection (HPI) Systems". Cummins Inc.. Cummins.com. http://www.cummins.com/cmi/content.jsp?menuIndex=6&siteId=1&overviewId=409&langId=1033&menuId=81&#High Pressure Injection (HPI) Systems. Retrieved 4 November 2009.
^ "Injection Systems and Components - Delphi E1 Diesel Electronic Unit Injector". Delphi Automotive LLP. - Manufacturer Products : Commercial Vehicle Industry. Delphi.com. http://delphi.com/manufacturers/cv/powertrain/injection-systems-and-components/e1-diesel-electronic-unit-injector/. Retrieved 4 November 2009.
^ "Injection Systems and Components - Delphi E3 Diesel Electronic Unit Injector". Delphi Automotive LLP. - Manufacturer Products : Commercial Vehicle Industry. Delphi.com. http://delphi.com/manufacturers/cv/powertrain/injection-systems-and-components/e3-diesel-electronic-unit-injector/. Retrieved 4 November 2009.
^ "Pumpe Dse Einspritzung (PDE - UIS)" (in German). kfztech.de. http://www.kfztech.de/kfztechnik/motor/diesel/pumpeduese.htm. Retrieved 15 September 2009.
^ "The efficient pump injector unit". Robert Bosch GmbH - Automotive. BoschAutoParts.co.uk. http://www.boschautoparts.co.uk/pcDies6.asp?c=2&d=1. Retrieved 2008-09-30.
^ "Auto Tech: Pumpe Duse". CanadianDriver Communications Inc.,. CanadianDriver.com. 29 September 2004. http://www.canadiandriver.com/articles/jk/040929.htm. Retrieved 4 November 2009.
^ a b (PDF) 1.9 litre TDI engine with Pump Dse, Volkswagen of America, Inc, October 2003, Self-Study Program - Course Number 841303, http://www.myarchive.us/richc/VW_TDI_with_PumpeDuse.pdf, retrieved 4 November 2009
^ [http://rb-k.bosch.de//en/powerconsumptionemissions/dieselsysteme/dieselsystem/passenger-car/injection_systems/uis/index.html "Passenger-car systems - Unit Injector System (UIS)"]. Robert Bosch GmbH - Automotive Technology - Diesel systems. Bosch.de. http://rb-k.bosch.de//en/powerconsumptionemissions/dieselsysteme/dieselsystem/passenger-car/injection_systems/uis/index.html. Retrieved 4 November 2009.
^ Volkswagen Mk4 turbodiesel "how to" index, for 2004-2005 Jettas and 2004-2006 New Beetles and Golfs
^ "Commercial vehicle systems - Unit Injector System (UIS)". Robert Bosch GmbH - Automotive Technology - Diesel systems. Bosch.de. http://rb-k.bosch.de//en/powerconsumptionemissions/dieselsysteme/dieselsystem/commercialvehiclesystems/injectionsystems/uis/index.html. Retrieved 4 November 2009.
Categories: Engine technology Engine fuel system technology Diesel engines Volkswagen enginesHidden categories: All articles with unsourced statements Articles with unsourced statements from June 2008 I am China Manufacturers writer, reports some information about graco snugride infant car seats , safeguard car seat.
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