Editing Common rail

{{Short description|Engine fuel delivery method}}
{{Other uses|Common rail (disambiguation)}}
[[File:Cutaway of a MAN V8 Diesel engine.jpg|thumb|300px|Diesel fuel injector as installed in a MAN V8 Diesel engine]]
'''Common rail direct fuel injection''' is a direct [[fuel injection]] system built around a high-[[pressure]] (over {{convert|2000|bar|MPa psi|abbr=on|lk=on|disp=or}}) fuel rail feeding [[solenoid valve]]s, as opposed to a low-pressure [[Fuel pump (engine)|fuel pump]] feeding [[Unit Injector|unit injectors]] (or pump nozzles). High-pressure injection delivers power and fuel consumption benefits over earlier lower pressure fuel injection,{{Citation needed|date=October 2020}} by injecting fuel as a larger number of smaller droplets, giving a much higher ratio of surface area to volume. This provides improved vaporization from the surface of the fuel droplets, and so more efficient combining of atmospheric oxygen with vaporized fuel delivering more complete [[combustion]].

Common rail injection is widely used in [[diesel engine]]s. It is also the basis of [[gasoline direct injection]] systems used on [[petrol engine]]s.

==History==
[[File:Common rail D7E.jpg|thumb|Common rail fuel system on a Volvo truck engine]]
In 1916 [[Vickers]] pioneered the use of mechanical common rail systems in [[British G-class submarine|G-class submarine]] engines. For every 90° of rotation, four plunger pumps allowed a constant injection pressure of {{convert|3000|psi|bar MPa}}, with fuel delivery to individual cylinders being shut off by valves in the injector lines.<ref>{{cite book |last=Cummins |first=C. Lyle |date=2007 |title=Diesels for the First Stealth Weapon |publisher=Carnot Press |pages=196–198 |isbn=978-0-917308-06-2}}</ref> From 1921 to 1980 [[William Doxford & Sons|Doxford Engines]] used a common rail system in their [[opposed-piston engine|opposed-piston marine engines]], where a multicylinder reciprocating fuel pump generated a pressure around {{convert|600|bar|MPa psi}}, with fuel stored in accumulator bottles.<ref>{{cite web|title=Doxford Engine Reference|url=http://www.doxford-engine.com/engines.htm|url-status=live|archive-url=https://web.archive.org/web/20071220213443/http://doxford-engine.com/engines.htm|archive-date=2007-12-20}}</ref> Pressure control was achieved by an adjustable pump discharge stroke and a "spill valve". Camshaft-operated mechanical timing valves were used to supply the spring-loaded Brice/CAV/Lucas injectors, which injected through the side of the cylinder into the chamber formed between the pistons. Early engines had a pair of timing cams, one for ahead running and one for astern. Later engines had two injectors per cylinder, and the final series of constant-pressure turbocharged engines was fitted with four. This system was used for the injection of both diesel and heavy fuel oil (600cSt heated to a temperature near 130&nbsp;°C).

Common rail engines have been used in marine and [[locomotive]] applications for some time. The [[Cooper Bessemer|Cooper-Bessemer]] GN-8 (''circa'' 1942) is an example of a hydraulically operated common rail diesel engine, also known as a modified common rail.

The common rail system prototype for automotive engines was developed in the late 1960s by [[Robert Huber (engineer)|Robert Huber]] of Switzerland, and the technology was further developed by Dr. Marco [[GANSER CRS AG|Ganser]] at the [[ETH Zurich|Swiss Federal Institute of Technology]] in Zurich, later of [[Ganser CRS AG|Ganser-Hydromag AG]] (est. 1995) in Oberägeri.

The first common-rail-Diesel-engine used in a road vehicle was the MN 106-engine by East German ''[[Volkseigener Betrieb|VEB]] IFA Motorenwerke Nordhausen''. It was built into a single [[IFA W 50|IFA W50]] in 1985. Due to a lack of funding, the development was cancelled and mass production was never achieved.<ref>{{cite web |url=https://meinanzeiger.de/nordhausen/nordhaeuser-an-entwicklung-des-weltweit-ersten-common-rail-diesels-beteiligt-ifa-museum-oeffnet-zur-nordhaeuser-museumsnacht/ |title=Nordhäuser an Entwicklung des weltweit ersten Common-Rail-Diesels beteiligt – IFA-Museum öffnet zur Nordhäuser Museumsnacht |date=25 March 2015 |publisher=meinanzeiger.de |access-date=2022-03-03 |archive-date=2020-10-28 |archive-url=https://web.archive.org/web/20201028135442/https://meinanzeiger.de/nordhausen/nordhaeuser-an-entwicklung-des-weltweit-ersten-common-rail-diesels-beteiligt-ifa-museum-oeffnet-zur-nordhaeuser-museumsnacht/ |url-status=dead }}</ref>

The first successful mass production vehicle with common rail, was sold in Japan in 1995. Dr. Shohei Itoh and Masahiko Miyaki of the [[Denso Corporation]] developed the ECD-U2 common rail system, mounted on the [[Hino Ranger#3rd Generation .281989-2002.29|Hino Ranger]] truck.<ref>{{cite web |url=http://www.jsae.or.jp/autotech/data_e/10-8e.html |title=240 Landmarks of Japanese Automotive Technology - Common rail ECD-U2 |publisher=Jsae.or.jp |access-date=2009-04-29 |url-status=dead |archive-url=https://web.archive.org/web/20090908165507/http://www.jsae.or.jp/autotech/data_e/10-8e.html |archive-date=2009-09-08 }}</ref> Denso claims the first commercial high-pressure common rail system in 1995.<ref>{{cite web
 |title       = Diesel Fuel Injection
 |work        = DENSO Global
 |access-date  = 2011-08-03
 |url         = http://www.globaldensoproducts.com/em/dem/crs/index.html
 |url-status     = live
 |archive-url  = https://web.archive.org/web/20110807070253/http://www.globaldensoproducts.com/em/dem/crs/index.html
 |archive-date = 2011-08-07
}}</ref>

Modern common rail systems are governed by an [[engine control unit]], which controls injectors electrically rather than mechanically. Prototyped in the 1990s by [[Magneti Marelli]], Centro Ricerche Fiat in [[Bari]], and Elasis, with further development by physicist Mario Ricco [[Fiat|Fiat Group]]. Unfortunately Fiat were in a poor financial state at this time, so the design was acquired by [[Robert Bosch GmbH]] for refinement and mass production. <ref name="economist.com">{{cite news|url=http://www.economist.com/opinion/displaystory.cfm?story_id=11090197|title=Fiat Rebirth of a carmaker|access-date=2008-05-01|work=economist.com|date=2008-04-24|url-status=live|archive-url=https://web.archive.org/web/20090908034030/http://www.economist.com/opinion/displaystory.cfm?story_id=11090197|archive-date=2009-09-08}}</ref> The first passenger car to use this system was the 1997 [[Alfa Romeo 156]] with a 2.4-L [[JTD engine]],<ref name="autonews.com">{{cite web|url=http://www.autonews.com/files/07_ane_ptc/speakers.html|title=New Powertrain Technologies Conference|access-date=2008-04-08|work=autonews.com|url-status=dead|archive-url=https://web.archive.org/web/20130703105445/http://www.autonews.com/files/07_ane_ptc/speakers.html|archive-date=2013-07-03}}</ref> and later that same year, [[Mercedes-Benz]] introduced it in their [[Mercedes-Benz C-Class (W202)|W202]] model. In 2001, common rail injection made its way into pickup trucks with the introduction of the 6.6 liter Duramax LB7 V8 used in the Chevrolet Silverado HD and GMC Sierra HD. In 2003 Dodge and Cummins launched common rail engines, and Ford followed in 2008 with the 6.4L Powerstroke. Today almost all non-commercial diesel vehicles use common rail systems.

== Applications ==
The common rail system is suitable for all types of road cars with diesel engines, ranging from [[city car]]s (such as the [[Fiat Panda#Second generation (169; 2003)|Fiat Panda]]) to [[executive car]]s (such as the [[Audi A8]]). The main suppliers of modern common rail systems are [[Robert Bosch GmbH|Bosch]], [[Delphi Technologies]], [[Denso]], and [[Siemens VDO]] (now owned by [[Continental AG]]).<ref>{{cite web|url=http://europe.autonews.com/article/20051017/ANE/510170842/denso-targets-french-us-automakers|title=Denso targets French, US automakers : World's No. 4 supplier will grow organically, not by acquisitions|website=Europe.autonews.com|access-date=16 May 2018|date=2005-10-17}}</ref>

==Acronyms and branding used==
[[File:Bosch common rail injector.JPG|thumb|Bosch common rail diesel fuel injector from a Volvo truck engine]]
The automotive manufacturers refer to their common rail engines by their own [[brand]] names:
* [[Ashok Leyland]]: '''CRS''' (used in U Truck and E4 Busses)
* [[Audi]]: '''[[TDI (engine)|TDI]]''', '''BiTDi''' The "Bi" stands for [[Twin-turbo|BiTurbo]]
* [[BMW Group]] ([[BMW]] and [[Mini]]): '''d''' (also used in the [[Land Rover Freelander]] as TD4 and the [[Rover 75]] and [[MG ZT]] as CDT and CDTi), '''D''' and '''SD'''
* [[Chrysler]] '''CRD'''
* [[Citroën]]: '''[[HDi]]''', '''e-HDi''' and '''BlueHDi'''
* [[Cummins]] and [[Scania (company)|Scania]]: '''XPI''' (developed under joint venture)
* [[Cummins]]: '''CCR''' ([[Cummins]] pump with [[Robert Bosch GmbH|Bosch]] injectors)
* [[Daimler AG|Daimler]]: '''CDI''' 
* [[Fiat|Fiat Group]] ([[Fiat]], [[Alfa Romeo]] and [[Lancia]]): '''[[JTD engine|JTD]]''' (also branded as '''MultiJet''', '''JTDm''', and by supplied manufacturers as '''TDi''', '''CDTi''', '''TCDi''', '''TiD''', '''TTiD''', '''DDiS''' and '''QuadraJet''')
* [[Ford Motor Company]]: '''TDCi''' ([[Duratorq]] and [[Powerstroke]]) and '''EcoBlue Diesel'''
* [[General Motors|GM]]: '''VCDi''' (licensed from [[VM Motori]]) '''Duramax Diesel''', '''Diesel''' and '''CTDI'''
* [[Honda]]: '''i-CTDI''' and '''i-DTEC'''
* [[Hyundai Motor Company|Hyundai]], [[Kia Motors|Kia]] and [[Genesis Motor|Genesis]]: '''CRDi'''
* [[IKCO]]: '''[[IKCO EF engines|EFD]]'''
* [[Isuzu]]: '''iTEQ''', '''Ddi''' and '''DI TURBO'''
* [[Jaguar Cars|Jaguar]]: '''d'''
* [[Jeep]]: '''CRD''' and '''[[EcoDiesel]]'''
* [[Komatsu Limited|Komatsu]]: '''Tier3''', '''Tier4''', '''4D95''' and higher '''''HPCR'''''-series
* [[Land Rover]]: '''TD4''', eD4, SD4, TD6, TDV6, SDV6, TDV8, SDV8
* [[Lexus]]: '''d''' (e.g. 450d and 220d)
* [[Mahindra & Mahindra|Mahindra]]: '''CRDe''', '''m2DiCR''', {{proper name|'''mEagle'''}}, {{proper name|'''mHawk'''}}, {{proper name|'''mFalcon'''}} and {{proper name|'''mPower (Trucks)'''}}
* [[Maserati]]: '''Diesel'''
* [[Mazda]]: '''MZR-CD''' and '''Skyactiv-D''' (some MZR-CD engines are manufactured by the [[Ford Motor Company|Ford]] and [[PSA Peugeot Citroën]] joint venture) and earlier '''DiTD'''
* [[Mercedes-Benz]]: '''CDI''' and '''d'''
* [[Mitsubishi Motors|Mitsubishi]]: '''Di-D''' 
* [[Nissan]]: '''DDTi'''
* [[Opel]]/[[Vauxhall Motors|Vauxhall]]: '''DTI''', '''CDTI''', '''BiTurbo CDTI''', '''CRI''', '''Turbo D''' and '''BiTurbo D'''
* [[Porsche]]: '''Diesel'''
* [[Proton (carmaker)|Proton]]: '''SCDi'''
* [[Groupe PSA|Groupe PSA (Peugeot, Citroën and DS)]]: '''HDi''', '''e-HDi''' or '''BlueHDi''' (developed under joint venture with [[Ford Motor Company|Ford]]) – See [[PSA HDi engine]]
* [[Renault]], [[Automobile Dacia|Dacia]] and [[Nissan Motor Company|Nissan]]: '''dCi''' and '''BLUEdCi''' (Infiniti uses some dCi engines as part of the [[Renault–Nissan–Mitsubishi Alliance|Renault-Nissan Alliance]], branded '''d''')
* [[Saab Automobile|Saab]]: '''TiD''' (The 2.2 turbo diesel engine was also called "TiD", but it didn't have Common rail) and '''TTiD''' The double "T" stands for [[Twin-turbo|Twin-Turbo]]
* [[SsangYong Motor Company|SsangYong]]: '''XDi''', eXDI, '''XVT''' or '''D'''
* [[Subaru]]: '''TD''', '''D''' or '''BOXER DIESEL''' (as of Jan 2008)
* [[Suzuki]]: '''DDiS'''
* [[Tata Motors|Tata]]: '''2.2 VTT DiCOR''' (used in large SUV-class such as [[Tata Safari|Safari]]), '''VARICOR''' (used in large SUV-class such as [[Tata Safari Storme|Safari Storme]], [[Tata Aria|Aria]] and [[Tata Hexa|Hexa]]),'''1.05 Revotorq CR3''' (used in [[Tata Tiago|Tiago]] and [[Tata Tigor|Tigor]]) '''1.5 Revotorq CR05''' (used in [[Tata Nexon|Nexon]] and [[Tata Altroz|Altroz]]), '''1.4 CR4''' (used in [[Tata Indica|Indica]], [[Tata Indigo|Indigo]]), '''3.0 CR4''' (used in [[Tata Sumo|Sumo gold]]''') 1.3 Quadrajet''' (supplied by [[Fiat]] and used in [[Indica Vista]], [[Tata Indigo Manza|Indigo Manza]] and [[Tata Zest|Zest]]), and '''2.0 Kryotec''' (also supplied by Fiat and used in SUV [[Tata Harrier|Harrier]] and All new [[Tata Safari|Safari]]),'''3.3 L Turbotronn''' and '''5L Turbotronn''' ( used in M&HCV Trucks). 
* [[Toyota]]: '''D4-D'''
* [[Volkswagen Group]] ([[Volkswagen]], [[Audi]], [[SEAT]] and [[Škoda Auto|Škoda]]): '''[[Turbocharged Direct Injection|TDI]]''' (more recent models use common rail, as opposed to the earlier [[Unit Injector|unit injector]] engines). Bentley term their Bentayga diesel simply '''Diesel'''
* [[Volvo]]: '''D''', '''D2''', '''D3''', '''D4''' and '''D5''' engines (some are manufactured by [[Ford Motor Company|Ford]] and [[PSA Peugeot Citroën]]), [[Volvo Penta]] D-series engines

==Principles==
[[File:Common Rail Scheme.svg|350px|right|thumbnail|Diagram of the common rail system]]
Solenoid or [[piezoelectric]] valves make possible fine [[electronic control unit|electronic control]] over the fuel-injection time and quantity, and the higher pressure that the common rail technology makes available provides better fuel [[aerosol|atomisation]]. To lower engine [[noise (environmental)|noise]], the engine's electronic control unit can inject a small amount of diesel just before the main injection event ("pilot" injection), thus reducing its explosiveness and vibration, as well as optimising injection timing and quantity for variations in fuel quality, cold starting, and so on. Some advanced common rail fuel systems perform as many as five injections per stroke.<ref>(multistroke injection) See BMW 2009 Brochure for 3 series</ref>

Common rail engines require a very short to no heating-up time, depending on the ambient temperature, and produce lower engine noise and emissions than older systems.<ref>{{cite web |url=http://www.carservicesalisbury.com/go/common-rail-diesel-service%7D |website=www.carservicesalisbury.com |access-date=15 January 2022 |title=Archived copy |archive-date=14 May 2018 |archive-url=https://web.archive.org/web/20180514134251/http://www.carservicesalisbury.com/go/common-rail-diesel-service%7D |url-status=dead }}</ref>

Diesel engines have historically used various forms of fuel injection. Two common types include the [[Unit injector|unit-injection]] system and the [[Injection pump|distributor/inline-pump systems]]. While these older systems provide accurate fuel quantity and injection timing control, they are limited by several factors:

*They are cam driven, and injection pressure is proportional to engine speed. This typically means that the highest injection pressure can only be achieved at the highest engine speed and the maximum achievable injection pressure decreases as engine speed decreases. This relationship is true with all pumps, even those used on common rail systems. With unit or distributor systems, the injection pressure is tied to the instantaneous pressure of a single pumping event with no accumulator, thus the relationship is more prominent and troublesome.
*They are limited in the number and timing of injection events that can be commanded during a single combustion event. While multiple injection events are possible with these older systems, it is much more difficult and costly to achieve.
*For the typical distributor/inline system, the start of injection occurs at a predetermined pressure (often referred to as pop pressure) and ends at a predetermined pressure. This characteristic results from "dumb" injectors in the cylinder head which open and close at pressures determined by the spring preload applied to the plunger in the injector. Once the pressure in the injector reaches a predetermined level, the plunger lifts and injection starts.

In common rail systems, a high-pressure pump stores a reservoir of fuel at high pressure — up to and above {{convert|2000|bar|MPa psi}}. The term "common rail" refers to the fact that all of the [[fuel injector]]s are supplied by a common fuel rail which is nothing more than a pressure accumulator where the fuel is stored at high pressure. This accumulator supplies multiple fuel injectors with high-pressure fuel. This simplifies the purpose of the high-pressure pump in that it only needs to maintain a target pressure (either mechanically or electronically controlled). The fuel injectors are typically controlled by the [[engine control unit]] (ECU). When the fuel injectors are electrically activated, a hydraulic valve (consisting of a nozzle and plunger) is mechanically or hydraulically opened and fuel is sprayed into the cylinders at the desired pressure. Since the fuel pressure energy is stored remotely and the injectors are electrically actuated, the injection pressure at the start and end of injection is very near the pressure in the accumulator (rail), thus producing a square injection rate. If the accumulator, pump, and plumbing are sized properly, the injection pressure and rate will be the same for each of the multiple injection events.

Third-generation{{vague|date=October 2020}} common rail diesels now feature [[piezoelectric]] injectors for increased precision, with fuel pressures up to {{convert|2500|bar|MPa psi|abbr=on}}.<ref>{{Cite news|url=http://www.globaldenso.com/en/newsreleases/130626-01.html|title=DENSO Develops a New Diesel Common Rail System With the World's Highest Injection Pressure{{!}} News {{!}} DENSO Global Website|work=DENSO Global Website|date=2013-06-26|language=en-US|url-status=live|archive-url=https://web.archive.org/web/20171013221631/http://www.globaldenso.com/en/newsreleases/130626-01.html|archive-date=2017-10-13}}</ref>

==See also==
* [[Unit injector|Hydraulically actuated electronic unit injection]]
* [[Unit pump]]
* [[Water sensor]]

==References==
{{Reflist}}

== External links ==
{{Commons category|Common rail fuel injection}}
*[https://www.enggstudy.com/common-rail-direct-injection-system Common Rail Direct Injection System or CRDI System working and advantages]
*[https://crankit.in/common-rail-direct-injection-crdi/ Brief Summary about working of CRDI Engine]
*[https://www.youtube.com/watch?v=aGwV9ueHcz4 Animation explaining common rail functioning]

{{Automotive engine}}
{{Piston engine configurations}}
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[[Category:Diesel engine technology]]
[[Category:Engine fuel system technology]]

[[ja:噴射ポンプ#コモンレール式]]