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Common rail
Common rail
direct fuel injection is a direct fuel injection system for diesel engines. On diesel engines, it features a high-pressure (over 100 bar or 10 MPa or 1,500 psi) fuel rail feeding individual solenoid valves, as opposed to a low-pressure fuel pump feeding unit injectors (or pump nozzles). Third-generation common rail diesels now feature piezoelectric injectors for increased precision, with fuel pressures up to 2,500 bar (250 MPa; 36,000 psi).[1] In petrol engines, it is used in Gasoline direct injection
Gasoline direct injection
(GDI) engine technology.

Contents

1 History 2 Applications 3 Acronyms and branding used 4 Principles 5 See also 6 References 7 External links

History[edit]

Common rail
Common rail
fuel system on a Volvo
Volvo
truck engine

The common rail system prototype was developed in the late 1960s by Robert Huber of Switzerland
Switzerland
and the technology further developed by Dr. Marco Ganser at the Swiss Federal Institute of Technology in Zurich, later of Ganser-Hydromag AG (est.1995) in Oberägeri. The first successful usage in a production vehicle began in Japan
Japan
by the mid-1990s. Dr. Shohei Itoh and Masahiko Miyaki of the Denso Corporation, a Japanese automotive parts manufacturer, developed the common rail fuel system for heavy duty vehicles and turned it into practical use on their ECD-U2 common-rail system mounted on the Hino Ranger truck and sold for general use in 1995.[2] Denso
Denso
claims the first commercial high pressure common rail system in 1995.[3] Modern common rail systems, whilst working on the same principle, are governed by an engine control unit (ECU) which opens each injector electrically rather than mechanically. This was extensively prototyped in the 1990s with collaboration between Magneti Marelli, Centro Ricerche Fiat
Fiat
and Elasis. After research and development by the Fiat Group, the design was acquired by the German company Robert Bosch GmbH for completion of development and refinement for mass-production. In hindsight, the sale appeared to be a strategic error for Fiat, as the new technology proved to be highly profitable. The company had little choice but to sell Bosch a licence, as it was in a poor financial state at the time and lacked the resources to complete development on its own.[4] In 1997 they extended its use for passenger cars. The first passenger car that used the common rail system was the 1997 model Alfa Romeo 156
Alfa Romeo 156
2.4 JTD,[5] and later on that same year Mercedes-Benz
Mercedes-Benz
introduced it in their W202 model. Common rail
Common rail
engines have been used in marine and locomotive applications for some time. The Cooper-Bessemer GN-8 (circa 1942) is an example of a hydraulically operated common rail diesel engine, also known as a modified common rail. Vickers
Vickers
pioneered the use of common rail injection in submarine engines. Vickers
Vickers
engines with the common rail fuel system were first used in 1916 in the G-class submarines. It used four plunger pumps to deliver a pressure of up to 3,000 pounds per square inch (210 bar; 21 MPa) every 90 degrees of rotation to keep the fuel pressure adequately constant in the rail. Fuel delivery to individual cylinders could be shut off via valves in the injector lines.[6] Doxford Engines used a common rail system in their opposed-piston marine engines from 1921 to 1980, where a multi-cylinder reciprocating fuel pump generated a pressure of approximately 600 bars (60 MPa; 8,700 psi), with the fuel being stored in accumulator bottles.[7] Pressure
Pressure
control was achieved by means of 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 were fitted with four injectors per cylinder. This system was used for the injection of both diesel oil and heavy fuel oil (600cSt heated to a temperature of approximately 130 °C). Applications[edit] The common rail system is suitable for all types of road cars with diesel engines, ranging from city cars (such as the Fiat
Fiat
Panda) to executive cars (such as the Audi
Audi
A8). The main suppliers of modern common rail systems are Robert Bosch GmbH, Delphi, Denso, and Siemens VDO (now owned by Continental AG).[8] Acronyms and branding used[edit]

Bosch common rail diesel fuel injector from a Volvo
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) BMW Group
BMW Group
( BMW
BMW
and Mini): d (also used in the Land Rover Freelander
Land Rover Freelander
as TD4 and the Rover 75
Rover 75
and MG ZT
MG ZT
as CDT and CDTi), D and SD Chevrolet
Chevrolet
(owned by GM): VCDi (licensed from VM Motori) Chrysler
Chrysler
CRD Citroën: HDi, e-HDi and BlueHDi Cummins
Cummins
and Scania: XPI (developed under joint venture) Cummins: CCR ( Cummins
Cummins
pump with Bosch injectors) Daimler: CDI Fiat
Fiat
Group (Fiat, Alfa Romeo
Alfa Romeo
and Lancia): JTD (also branded as MultiJet, JTDm, and by supplied manufacturers as TDi, CDTi, TCDi, TiD, TTiD, DDiS and QuadraJet) Ford
Ford
Motor Company: TDCi ( Duratorq
Duratorq
and Powerstroke) Honda: CTDI and i-DTEC Hyundai and Kia: CRDi IKCO: EFD Isuzu: iTEQ Jaguar d Jeep: CRD Komatsu: Tier3, Tier4, 4D95 and higher HPCR-series Land Rover: TD4, eD4, SD4, TD6, TDV6, SDV6, TDV8, SDV8 Mahindra: CRDe, m2DiCR, mEagle,mHawk,mFalcon and mPower (Trucks) Maserati: Diesel Mazda: MZR-CD and Skyactiv-D (are manufactured by the Ford
Ford
and PSA Peugeot Citroen
Citroen
joint venture) and earlier DiTD Mercedes-Benz: CDI and d Mitsubishi: DI-D (mainly on the recently developed 4N1 engine family) Opel: CDTI Porsche: Diesel Proton: SCDi PSA (Peugeot, Citroën and DS): HDi, e-HDi or BlueHDi (developed under joint venture with Ford) – See PSA HDi engine Renault, Dacia
Dacia
and Nissan: dCi (Infiniti uses some dCi engines as part of the Renault-Nissan Alliance, branded d) SsangYong: XDi, eXDI, XVT or D Subaru: TD or D (as of Jan 2008) Suzuki: DDiS Tata: 2.2 VTT DiCOR (used in large SUV-class such as Safari and Aria) and CR4 Toyota: D-4D and D-CAT Volkswagen Group
Volkswagen Group
(Volkswagen, Audi, SEAT
SEAT
and Škoda): TDI (more recent models use common rail, as opposed to the earlier unit injector engines). Bentley term their Bentayga diesel simply Diesel Volvo: D, D2, D3, D4 and D5 engines (some are manufactured by Ford
Ford
and PSA Peugeot Citroen), Volvo
Volvo
Penta D-series engines

Principles[edit]

Diagram of the common rail system

Solenoid or piezoelectric valves make possible fine electronic control over the fuel injection time and quantity, and the higher pressure that the common rail technology makes available provides better fuel atomisation. To lower engine 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.[9] Common rail
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.[10] Diesel engines have historically used various forms of fuel injection. Two common types include the unit injection system and the 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, and 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 pre-determined pressure (often referred to as: pop pressure) and ends at a pre-determined 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 pre-determined 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 2,000 bars (200 MPa; 29,000 psi). The term "common rail" refers to the fact that all of the fuel injectors 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 ECU-controlled. 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. See also[edit]

Unit pump Turbocharged Direct Injection Water sensor

References[edit]

^ "DENSO Develops a New Diesel Common Rail System With the World's Highest Injection Pressure
Pressure
News DENSO Global Website". DENSO Global Website. Retrieved 2017-12-14.  ^ "240 Landmarks of Japanese Automotive Technology - Common rail ECD-U2". Jsae.or.jp. Retrieved 2009-04-29.  ^ "Diesel Fuel Injection". DENSO Global. Retrieved 2011-08-03.  ^ " Fiat
Fiat
Rebirth of a carmaker". economist.com. 2008-04-24. Retrieved 2008-05-01.  ^ "New Powertrain Technologies Conference". autonews.com. Retrieved 2008-04-08.  ^ Cummins, C. Lyle (2007). Diesels for the First Stealth Weapon. Carnot Press. pp. 196–198. ISBN 978-0-917308-06-2.  ^ "Doxford Engine Reference".  ^ http://europe.autonews.com/article/20051017/ANE/510170842/denso-targets-french-us-automakers ^ (multistroke injection) See BMW
BMW
2009 Brochure for 3 series ^ http://www.carservicesalisbury.com/go/common-rail-diesel-service

External links[edit]

Wikimedia Commons has media related to Common rail
Common rail
fuel injection.

Brief Summary about working of CRDI Engine Animation explaining common rail functioning

v t e

Automotive engine

Part of the Automobile series

Basic terminology

Bore Compression ratio Crank Cylinder Dead centre Diesel engine Dry sump Engine balance Engine configuration Engine displacement Engine knocking Firing order Hydrolock Petrol
Petrol
engine Power band Redline Spark-ignition engine Stroke Stroke ratio Wet sump

Main components

Connecting rod Crankcase Crankpin Crankshaft Crossplane Cylinder bank Cylinder block Cylinder head
Cylinder head
(crossflow, reverse-flow) Flywheel Head gasket Hypereutectic piston Main bearing Piston Piston
Piston
ring Starter ring gear Sump

Valvetrain

Cam Cam
Cam
follower Camshaft Desmodromic valve Hydraulic tappet Multi-valve Overhead camshaft Overhead valve Pneumatic valve springs Poppet valve Pushrod Rocker arm Sleeve valve Tappet Timing belt Timing mark Valve float Variable valve timing

Aspiration

Air filter Blowoff valve Boost controller Butterfly valve Centrifugal-type supercharger Cold air intake Dump valve Electronic throttle control Forced induction Inlet manifold Intake Intercooler Manifold vacuum Naturally aspirated engine Ram-air intake Scroll-type supercharger Short ram air intake Supercharger Throttle Throttle
Throttle
body Turbocharger Twin-turbo Variable-geometry turbocharger Variable-length intake manifold Warm air intake

Fuel system

Carburetor Common rail Direct injection Fuel filter Fuel injection Fuel pump Fuel tank Gasoline direct injection Indirect injection Injection pump Lean-burn Stratified charge engine Turbo fuel stratified injection Unit injector

Ignition

Contact breaker Magneto Distributor Electrical ballast High tension leads Ignition coil Spark plug Wasted spark

Electrics and engine management

Air–fuel ratio meter Alternator Automatic Performance Control Car
Car
battery (lead–acid battery) Crankshaft
Crankshaft
position sensor Dynamo Drive by wire Electronic control unit Engine control unit Engine coolant temperature sensor Glow plug Idle air control actuator MAP sensor Mass flow sensor Oxygen sensor Starter motor Throttle
Throttle
position sensor

Exhaust system

Automobile emissions control Catalytic converter Diesel particulate filter Exhaust manifold Glasspack Muffler

Engine cooling

Air cooling Antifreeze
Antifreeze
(ethylene glycol) Core plug Electric fan Fan belt Radiator Thermostat Water cooling Viscous fan (fan clutch)

Other components

Balance shaft Block heater Combustion chamber Cylinder head
Cylinder head
porting Gasket Motor oil Oil filter Oil pump Oil sludge PCV valve Seal Synthetic oil Underdrive pulleys

Portal Category

v t e

Reciprocating engines and configurations

Type

Bourke Orbital (Sarich) Piston Pistonless (Wankel) Radial Axial Rotary Split cycle Stelzer Tschudi

Stroke cycles

Two-stroke Four-stroke Five-stroke Six-stroke Two-and four-stroke

Configurations & number of cylinders

Single cylinder

Single

Two cylinders

Split-single I2 V2 F2

Inline / straight

I2 I3 I4 I5 I6 I7 I8 I9 I10 I12 I14

Flat

F2 F4 F6 F8 F10 F12 F16

V / Vee

V2 V3 V4 V5 V6 V8 V10 V12 V14 V16 V18 V20 V24

W

W8 W12 W16 W18

Other inline

H U Square four VR Opposed X X24 Junkers Jumo 222

Components

Valves

Cylinder head
Cylinder head
porting Corliss Intake Exhaust Multi Overhead Piston Poppet Side Sleeve Slide Rotary valve Variable valve timing Camless Desmodromic Hydraulic tappet

Fuel supplies

Carburetor Gasoline direct injection Common rail

Mechanisms

Cam Camshaft Overhead camshaft Connecting rod Crank Crankshaft Scotch yoke Swashplate Rhombic drive

Linkages

Peaucellier–Lipkin Watt's (parallel)

Other

Hemi Recuperator Turbo

.