17767653 Fuel Injection Presentation
Content
FUEL INJECTION SYSTEM Ag A g en end da
1.Engine Fundamentals 2.Types of Fuel injection injection system 3.Diesel Fuel injection injection system a. Types of Fuel Injectors Injectors b. Performance Characteristic Characteristic of Fuel Injector c. Fuel Injector testing d. Fuel Injector failures failures 4.Spark Ignition system a. GDI b. MPFI 5.Fuel Injection System System Powertrain Control Module a. Diesel b.Gasoline
FUEL INJECTION SYSTEM FOUR STROKE ENGINE
FUEL INJECTION SYSTEM WHY FUEL INJECTION SYSTEM
PREFFERED INJECTION SCHEDULE
FUEL INJECTION SYSTEM DIESEL FUEL REQUIREMENTS
FUEL INJECTION SYSTEM TYPES OF FUEL INJECTION SYSTEM FUEL INJECTION SYSTEM
INDIRECT INJECTION
DIRECT INJECTION
Pump Line nozzle Unit Injector • Mechanical • Hydraulic • Mechanical Common Rail • Solenoid Common Rail • Piezoelectric
Electronic
SPARK INJECTION
FUEL INJECTION SYSTEM
FUEL INJECTION SYSTEM
FUEL INJECTION SYSTEM
FUEL INJECTION SYSTEM THE PUMP-LINE PUMP-LINE-NOZZ -NOZZLE LE SYSTEM SYSTEM
(1927(1927- BOSCH) BOSCH)
Rugged but complicated mechanical devices –Upto devices –Upto 115MPa injection injection Pressure. Injection timing are pre-determined (desi (designed gned in - to the pumping pumping elemen elementt geometry geometry))
FUEL INJECTION SYSTEM MECHANICAL UNIT INJECTOR
Features: Mechanically Actu ated ated Mechanically Rack / Gov. Controlled Timi ng Fixed Timi Higher Volumetric Efficiency Higher Injecti Injecti on Pressures
Drawback •Many rods and levers in the linkage system to synchronize and control each injector. •System governed by complex governor
FUEL INJECTION SYSTEM MECHANICAL ACTUATED ELECTRONIC CONTROLLED UNIT INJECTOR ECM
FUEL INJECTION SYSTEM MEUI SYSTEM OPERATION Features: Mechanica chanic ally Actuate Act uated d lectro nic Control ont rol / 2 Solenoids olenoid s Electronic DOC Nozzle Variable able Tim Timin ing g Vari Flexibl ble e Inj Injectio ection n Rate Rate Shape Shape Flexi Ramp / Square Pilots, ilo ts, Splits, Splits , and and Posts ost s Max Max Inj Pressur ress ure e = 172 172 MPa
FUEL INJECTION SYSTEM HYDRAULIC ACTUATED ELECTRONIC CONTROLLED UNIT INJECTOR
FUEL INJECTION SYSTEM FUEL INJECTION CYCLE-HEUI
•High pressure oil supply is provided by a pump that uses engine oil to actuate the HEUI injector. •The principle is amplifying hydraulic force to produce higher Injection pressure. •Flexible Injection Rate Shape
FUEL INJECTION SYSTEM COMMON COMMON RAIL RAIL SYSTEM SYSTEM – (BOSCH (BOSCH & DELPHI DELPHI))
FUEL INJECTION SYSTEM HIGH-PRESSURE COMMON RAIL
Features: •Electronic Control •Injection Pressure Independen of Engine Speed •Direct Operated Check Nozzle •Variable Timing •Flexible Injection Rate Shape •Boot to Square •Pilots, Splits, and Posts •Max Inj Pressure Pressure = 160 MPa
FUEL INJECTION SYSTEM COMMON RAIL SYSTEM IN DODGE RAM 3500 •Third generation Common Rail injector architecture •Total injection of 130cc •Pilot •Pilot injection injection – Low and mid mid range speed speed noise noise •Gear driven injection pump •160 Mpa of Fuel Fuel Injecti Injection on Pressure Pressure
http://www.dodge.com/en/2008/ram_3500/capability/engines/
FUEL INJECTION SYSTEM DIFFERENCE IN PIEZO AND SOLENOID ACTUATION
FUEL INJECTION SYSTEM PIEZO PIEZO ELECTRIC ELECTRIC COMMON COMMON RAIL RAIL SYSTEM SYSTEM – (BOSCH) (BOSCH)
•Fuel Emission •Better Fuel Consumptions Consumptions •More Engine torque and power •Reduced NVH
Bosch Video File
FUEL INJECTION SYSTEM PIEZO INJECTION SYSTEM IN JEEP 3 LITRE V6 CRD
First use use of Piezo injection injection in a North North American American SUV SUV 30 percent improved fuel economy without sacrificing performance Peak pressure of up to 240 Mpa.
FUEL INJECTION SYSTEM FUEL SYSTEM PERFORMANCE
FUEL INJECTION SYSTEM FUEL SYSTEM PERFORMANCE
FUEL INJECTION SYSTEM FUEL INJECTOR TESTING Performance Tests • • •
Micro performance – hea heavily inst rumented rumented Macro perfor performa mance nce – gain gain curves, c urves, delivery delivery characteristics characteristics Parametric rametric Sensitivity nsiti vity – repea repeatability tability + variability variability
Struct tr uctur ure es Te Tests st s •
Test Tests s @ elevated temp tempera eratu tures res and pressu pr essures res defin e strengt st rength h+ dynamic fatigue factor factors. s.
Endurance Endur ance Te Test •
Tests that combi co mbine ne eleva elevated ted temperatures temperatures and pressu res with wit h specified specif ied fuels and and lubri lu bricants cants to determi determine ne wea wear & life. li fe.
Systems ys tems Integr Integra ation ti on •
Combines Combi nes hardware hardw are and sof tware tw are,, on-e on -eng ngin ine, e, and off -eng -engin ine, e, to develop control strategies
FUEL INJECTION SYSTEM FUEL INJECTOR FAILURES
Plunger wear
Tip splitting
Cavitation Erosion
Tip breakage
Crack
FUEL INJECTION SYSTEM ELECTRONIC CONTROL SYSTEM BUILDING BLOCKS
FUEL INJECTION SYSTEM
Gasoline-Engine Fuel Delivery Systems
FUEL INJECTION SYSTEM Gasoline Engines The power produced by the spark ignition engine is directly proportional to the mass airflow entering it. Control of engine output and the corresponding torque at each engine speed is regulated by governing the amount of air being inducted via the throttle valve. The engine produces maximum power when the throttle valve is fully open (WOT, or wide open throttle). Because maximum maximum possible torque is proportional to fresh-air charge density, it is possible to raise power output by compressing the air before it enters the cylinder.
FUEL INJECTION SYSTEM Air Fuel Ratio The theoretical theoretical ideal for complete complete combustion combustion is a mass mass ratio of 14.7:1, referred to as the stoich stoichiom iometr etric ic ratio. ratio. The air-fuel mixture is a major factor in determining the spark-ignition engine’s rate of specific fuel consumption. Genuine complete combustion and absolutely minimal fuel consumption consumption would be possible only with excess air, but here limits are imposed by such considerations considerations as mixture flammability and the time available for combustion. Certain engine operating operating conditions conditions make mixture mixture adjustments to nonstoichiometric nonstoichiometric ratios essential. With a cold engine for instance, where specific adjustments to the A/F ratio are required.
FUEL INJECTION SYSTEM Excess Air Factor The designation designation l (lambda) (lambda) has been been selected to identify the excess-air excess-air factor (or air ratio) used to quantify the t he spread between the actual current mass A/F ratio and the theoretical optimum (14.7:1): λ
= Ratio of induction induction air mass mass to air requirement requirement for stoichiometric stoichiometric combustion.
λ
= 1: The inducted air mass corresponds to the theoretical requirement.
< 1: Indicates an air deficiency,producing deficiency,producing a corresponding corresponding rich mixture. mixture. Maximum power is derived from λ =0.85...0.95.
λ
> 1: This range is characterized characterized by excess air and lean mixture, leading to lower fuel consumption and reduced power. The potential maximum value for λ – called the “lean-burn limit (LML)”
λ
As can be seen, there is no single excess-air excess-air factor which can can simultaneously simultaneously generate the most favorable levels for all three factors. Air factors of λ = 0.9...1.1 produce “conditio “conditionally nally optimal” optimal” fuel econo economy my with“co with“conditi nditional onally ly optimal” optimal” power power generatio generationin nin actual practice.
FUEL INJECTION SYSTEM Spark-ignition engines with manifold injection produce maximum power at air deficiencies of 5...15 % (λ = 0.95...0.85),but maximum fuel economy comes in at 10...20% excess air (λ = 1.1...1.2). GDI engines can operate with substantially higher excess air factor (λ = 4).
FUEL INJECTION SYSTEM
Optimum A/F ratio and ignition angle
FUEL INJECTION SYSTEM Injection system Operating States Cold s tarting During cold starts the relative relative quantity of fuel in the inducted mixture decreases: decreases: the mixture mixture “goes lean.” This lean-mixture phenomenon stems from inadequate blending of air and fuel, low rates of fuel fuel vaporization, and condensation condensation on the walls walls of the inlet tract, all of of which are promoted by low temperatures. To compensate for these negative factors, and to facilitate cold starting, supplementary fuel must be injected into the engine. Post-start ost -start phase Following low-temperature low-temperature starts, supplementary fuel is required for a brief period, until the combustion chamber chamber heats up and improves the internal mixture formation. This richer mixture also increases torque to furnish a smoother transition to the desired idle speed. Warm-up phase The warm-up phase follows on the heels of the starting and immediate post-start phases. At this point the engine still requires an enriched mixture to offset off set the fuel condensation on the intake-manifold walls. walls. Lower temperatures are synonymous with less efficient fuel processing (owing to factors factors such as poor mixing of air and fuel and reduced fuel vaporization). This promotes fuel precipitation within the intake manifold, with the formation of condensate fuel that will only vaporize later, once temperatures have increased. These factors make it necessary to provide progressive mixture enrichment enrichment in response to decreasing temperatures t emperatures..
FUEL INJECTION SYSTEM Idle and and part-load p art-load Idle is defined as the operating status in which the torque generated by the engine is just sufficient to compensate for friction losses. The engine does not provide power to t he flywheel at idle. Part-load (or part-throttle) operation refers to the range of running conditions between idle and generation of maximum possible possible torque. Today’s standard concepts rely exclusively exclusively on stoichiometric stoichiometric mixtures for the operation operation of engines running running at idle and partthrottle once they have warmed to their normal operating temperatures. Full load lo ad (WOT (WOT)) At WOT (wide-open (wide-open throttle) supplementary supplementary enrichment may be required. This enrichment enrichment furnishes maximum torque and/or power. Ac A c c eler el erat atii o n and an d d ecel ec eler erat atii o n The fuel’s vaporization potential is strongly affected by pressure levels inside the intake manifold. Sudden variations in manifold pressure of the kind encountered in response to rapid changes in throttle valve aperture cause fluctuations in the fuel layer on the walls of the intake tract. Spirited acceleration leads to higher manifold pressures. The fuel responds with lower vaporization vaporization rates and the fuel layer within the manifold runners expands. A portion of the injected fuel is thus lost in wall condensation, and the engine goes lean for a brief period, until the fuel layer restabilizes. In an analogous, but inverted, response pattern, sudden deceleration leads to rich mixtures. A temperature sensitive correction function (transition compensation) compensation) adapts the mixture mixture to maintain optimal operational operational response and and ensure that the engine receives the consistent air/fuel mixture needed for efficient catalytic-converter catalytic-converter performance.
FUEL INJECTION SYSTEM Requirements of Gasoline injection systems
-To supply the engine with with the optimal airfuel mixture for any given operating conditions. -Maintaining air-fuel mixtures within precisely defined limits, which translates into superior performance in the areas of fuel economy, comfort and convenience, and power. -Meet emission norms
FUEL INJECTION SYSTEM Classification of Gasoline injection systems
Injection systems External A/F Mixture formation
SPI
MPFI
Internal A/F Mixture formation
Direct Injection
FUEL INJECTION SYSTEM Gasoline-Engine Fuel Delivery Systems Direct (In-Cylin (In-Cylinder) der) Fuel-Injection ????
1996
Ad A d v anc an c ed Mul Mu l t i -Por -Po r t Fuel-Injection
Multi-Port-Fuel-Injection
1995
1980
2004 Single-Point, Throttle-Body Fuel Fuel Injection Injecti on
1980 Carburetor 1900
1985
2005
1995
FUEL INJECTION SYSTEM External A/F Mixture formation 1. Sing Single le poin pointt inj injec ecti tion on -Injector is located above the throttle plate -Operate at low pressure (0.7 to 1 bar) - The inje injecto ctorr is flush flushed ed continuously by the fuel flowing through it in order to inhibit the formation of air bubble.
1 Fuel tank, 2 Electric Electric fuel fuel pump, pump, 3 Fuel filter, filter, 4 Pressure Pressure regulato regulator, r, 5 Injector, Injector, 6 Air-tempe Air-temperatu rature re sensor, sensor, 7 ECU, 8 Throttle Throttle actuato actuator, r, 9 Throttle Throttle potent potentiome iometer, ter, 10 Canister Canister-purg -purge e valve, valve, 11 Carbon Carbon canister, canister, 12 Lambda Lambda sensor, sensor, 13 CoolantCoolant-tempe temperatu rature re sensor, sensor, 14 Ignition Ignition distribu distributor, tor, 15 Battery, Battery, 16 Ignition Ignition switch switch,, 17 Relay, Relay, 18 Diagnost Diagnostic ic connector connector,, 19 Central Central injectio injection n unit. unit.
- Centrally Centrally located located solenoid solenoid controlled fuel injector
FUEL INJECTION SYSTEM External A/F Mixture formation
-Injector is located above the throttle, in the air intake path -Fuel is sprayed in the orifice between the housing and the throttle plate
central injection unit 1 Pressure Pressure regulato regulator, r, 2 Air-temper Air-temperature ature sensor sensor,, 3 Injector, Injector, 4 Upper Upper part part (hydraul (hydraulics), ics), 5 Fuel supply, supply, 6 Fuel return, return, 7 Insulato Insulatorr plate, plate, 8 Throttle Throttle valve, valve, 9 Lower Lower part. part.
-For cold start –Injection time is extended. Throttle actuator adjusts the throttle position to supply more air. This is sensed by potentiometer and ECU initiates increase in fuel quantity.
FUEL INJECTION SYSTEM External A/F Mixture formation 2. Multi Point fuel Injection -Main control control variables variables – Air flow and engine speed -Pressure differential between fuel and intake manifold is maintained at 3 bar such that injected fuel qty is only dependent on opening period of the valves
1 Fuel Fuel tank, tank, 2 Electr Electric ic fuel fuel pump pump,, 3 Fuel Fuel filte filter, r, 4 ECU, ECU, 5 Inject Injector, or, 6 FuelFuelpressure pressure regulat regulator, or, 7 Intake Intake manifold, manifold, 8 Electric Electric start start valve, 9 Throttle Throttle switch, switch, 10 Air-flow Air-flow sensor, sensor, 11 Lambda Lambda sensor, sensor, 12 Thermo-tim Thermo-time e switch, switch, 13 Coolant-t Coolant-temper emperature ature sensor, sensor, 14 Ignition Ignition distributor distributor,, 15 Auxiliary Auxiliary-air -air valve, valve, 16 Battery, Battery, 17 Ignition Ignition switch switch
-ECU delivers control pulses whose duration depends on engine speed, intake air flow (primarily) and other variables
FUEL INJECTION SYSTEM External A/F Mixture formation Ai A i r f l o w s ens en s o r Intake air flow deflects the flap which is converted by a potentiometer in to voltage ratio and fed to ECU Throttl hro ttle e valve switch swi tch Transmits a control signal to ECU when the throttle valve is either completely closed (Idle) or fully open (WOT) Au A u x i l i ary ar y A i r v alv al v e Supplies engine with additional air during warm-up phase. This T his supplementary air compensates for the cold engines higher frictional losses Electric lectri c sta st art va v alve & Thermo Thermo time ti me switc h During low temp start, the valve injects additional fuel into intake manifold. Thermo time switch activates the electric start valve
FUEL INJECTION SYSTEM Injector -Injector consist of Housing with coil , valve seat with spray orifice disk and a moving valve needle with solenoid armature. -Fuel strainer protects injector against contamination -O ring seals injector in rail and in intake manifold
1 O-rings, O-rings, 2 Filter Filter strainer, strainer, 3 Valve Valve housing housing with with electri electrical cal connecti connection, on, 4 Current Current coil, coil, 5 Spring, Spring, 6 Valve Valve needle needle with with solenoid armature, armature, 7 Valve seat with spray-orifice spray-orifice disk.
-When the coil is de-energized, the spring force and fuel pressure press the valve needle in its seat to seal the fuel supply. -When the coil is energized, the coil generetes magnetic field which attracts armature and lifts the valve needle from its seat and allows the fuel to flow through the injector.
FUEL INJECTION SYSTEM Adjustments for various operating conditions
FUEL INJECTION SYSTEM Disadvantages of Manifold injection -Problems may occur at idling because of incomplete fuel evaporation due to low air flow velocity into cylinder -Distribution of air flow into different inlet pipes may vary -Amount of fuel injected is less accurate at idling because electromagnetic electromagnetic injection valves are time controlled. There There is a large large impact on on amount of fuel injected at small small injection times.
FUEL INJECTION SYSTEM Fuell Sys Fue ystem tem
Carburetor Single-Point, Throttle-Body Fuel Injection Injectio n Multi-PortFuel-Injection A d v an Ad anc c ed Multi-PortFuel-Injection Direct-FuelInjection
Transient
Cold
Mixture
Cost &
Emiss missions ions &
Emiss missions ions &
Preparation
Complexity
Control
Control
Quality
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FUEL INJECTION SYSTEM Internal A/F Mixture formation Gasoline direct Injection
1 Fuel supply supply (high (high pressure pressure), ), 2 Accumulato Accumulatorr (rail), 3 Fuel inject injector, or, 4 Ignition Ignition coil coil with spark spark plug, plug, 5 Phase Phase sensor sensor,, 6 Pressu Pressure re sensor sensor,, 7 Knock Knock sensor, sensor, 8 EngineEngine-spee speed d sensor, sensor, 9 EngineEnginetemperature sensor, sensor, 10 Lambda sensor sensor (LSU), 11 Three-way Three-way catalytic catalytic converter converter,, 12 ExhaustExhaust-gas gas temperature sensor, 13 13 NOX catalytic converter, 14 Lambda Lambda sensor sensor (LSF).
FUEL INJECTION SYSTEM Operating concept and basic feature
Compare to SI engine, Gasoline direct-injection direct-injection system are characterized by : •
Inject Injecting ing the the fuel fuel dire directl ctly y into into the the comb combust ustion ion chambe chamberr with with high high pres pressur sure e.
•
A/FA/F-mi mixt xtur ure e form format atio ion n take takes s plac place e insi inside de the the cyl cylin inde der r
FUEL INJECTION SYSTEM Basic features 1.
Upright straight intake ports :
A strong down flow is generated along the intake intake cylinder during during the intake stroke and tumble motion motion in the flow is generated in the opposite direction of the regular regular four valve valve engines. engines. 2.
High pressure fuel injection pump
A swash type type axial plunger pump pump for high volumetric efficiency efficiency Is used for the high pressure fuel injection which which provides provides high pressure fuel directly injected into the cylinder 3.
High pressure swirl injector
An electronic magnetic magnetic injector was was used to achieve achieve accurate and precise control of injection quantity and timing 4.
Curved top piston
The top land configuration is changed to provide provide a cavity ,right under the spark plug tip which is aimed to strength the air motion
FUEL INJECTION SYSTEM Stra tr atifi ti fie ed Charge Engi Engine ne
During intake stroke air enters the cylinder Near the end of the compression stroke fuel is injected and directed by the piston head bowl towards the spark plug The mixture at the spark plug is “rich” in fuel thus easy to ignite but the amount of fuel injected results in an overall “lean” fuel-air mixture Lowers heat transfer to the walls but increases thermal cyclic load on the spark plug, and standard catalytic converter doesn’t work
FUEL INJECTION SYSTEM Influencing factors •
Temperature In Influence
-
Low Low temp temper erat atur ure e = gaso gasoliline ne cann cannot ot evap evapor orat ate e comp comple lete tely ly
• Fuel droplet-size -
Smaller droplet vaporize quicker
• A/F mixture formation in the homogeneous homogeneous operation operation mode -
Fuel Fuel is inje inject cted ed duri during ng the the indu induct ctio ion n str strok oke e mixture
maximum time for formation of the A/F
-
Inta Intake ke air air can can assi assist st in ach achie ievi ving ng rapi rapid d eva evapo pora rati tion on
•
A/F A/F mix mixtu ture re form format atio ion n in in the the stra strati tifi fied ed-c -cha harg rge e mod mode e
-
Fuel Fuel is inje inject cted ed duri during ng the the com compr pres essi sion on stro stroke ke A/F mixtur mixture e can be transpor transported ted to the vicinity of the spark plug Homogeneous charge (near full load) - Early Early injection injection during during induction induction stroke stroke - Fuel distri distributed buted throu throughou ghoutt the CC Stratified charge (at part load) - Injection Injection during during the compress compression ion stroke stroke - Fuel concen concentrated trated in the the region region of spark plug plug
→
→
FUEL INJECTION SYSTEM Comparison of Manifold injection and GDI
FUEL INJECTION SYSTEM Pros: • Fuel Fuel efficiency effic iency • High po wer wer outp ut • Emission c ontrol • No throttling loss • Engine speed speed contr co ntrol ol by b y EMS EMS • Fuel Fuel requirement
Cons: • Complexity • Cost pressure e • High f uel pressur
1.Engine Fundamentals 2.Types of Fuel injection injection system 3.Diesel Fuel injection injection system a. Types of Fuel Injectors Injectors b. Performance Characteristic Characteristic of Fuel Injector c. Fuel Injector testing d. Fuel Injector failures failures 4.Spark Ignition system a. GDI b. MPFI 5.Fuel Injection System System Powertrain Control Module a. Diesel b.Gasoline
FUEL INJECTION SYSTEM FOUR STROKE ENGINE
FUEL INJECTION SYSTEM WHY FUEL INJECTION SYSTEM
PREFFERED INJECTION SCHEDULE
FUEL INJECTION SYSTEM DIESEL FUEL REQUIREMENTS
FUEL INJECTION SYSTEM TYPES OF FUEL INJECTION SYSTEM FUEL INJECTION SYSTEM
INDIRECT INJECTION
DIRECT INJECTION
Pump Line nozzle Unit Injector • Mechanical • Hydraulic • Mechanical Common Rail • Solenoid Common Rail • Piezoelectric
Electronic
SPARK INJECTION
FUEL INJECTION SYSTEM
FUEL INJECTION SYSTEM
FUEL INJECTION SYSTEM
FUEL INJECTION SYSTEM THE PUMP-LINE PUMP-LINE-NOZZ -NOZZLE LE SYSTEM SYSTEM
(1927(1927- BOSCH) BOSCH)
Rugged but complicated mechanical devices –Upto devices –Upto 115MPa injection injection Pressure. Injection timing are pre-determined (desi (designed gned in - to the pumping pumping elemen elementt geometry geometry))
FUEL INJECTION SYSTEM MECHANICAL UNIT INJECTOR
Features: Mechanically Actu ated ated Mechanically Rack / Gov. Controlled Timi ng Fixed Timi Higher Volumetric Efficiency Higher Injecti Injecti on Pressures
Drawback •Many rods and levers in the linkage system to synchronize and control each injector. •System governed by complex governor
FUEL INJECTION SYSTEM MECHANICAL ACTUATED ELECTRONIC CONTROLLED UNIT INJECTOR ECM
FUEL INJECTION SYSTEM MEUI SYSTEM OPERATION Features: Mechanica chanic ally Actuate Act uated d lectro nic Control ont rol / 2 Solenoids olenoid s Electronic DOC Nozzle Variable able Tim Timin ing g Vari Flexibl ble e Inj Injectio ection n Rate Rate Shape Shape Flexi Ramp / Square Pilots, ilo ts, Splits, Splits , and and Posts ost s Max Max Inj Pressur ress ure e = 172 172 MPa
FUEL INJECTION SYSTEM HYDRAULIC ACTUATED ELECTRONIC CONTROLLED UNIT INJECTOR
FUEL INJECTION SYSTEM FUEL INJECTION CYCLE-HEUI
•High pressure oil supply is provided by a pump that uses engine oil to actuate the HEUI injector. •The principle is amplifying hydraulic force to produce higher Injection pressure. •Flexible Injection Rate Shape
FUEL INJECTION SYSTEM COMMON COMMON RAIL RAIL SYSTEM SYSTEM – (BOSCH (BOSCH & DELPHI DELPHI))
FUEL INJECTION SYSTEM HIGH-PRESSURE COMMON RAIL
Features: •Electronic Control •Injection Pressure Independen of Engine Speed •Direct Operated Check Nozzle •Variable Timing •Flexible Injection Rate Shape •Boot to Square •Pilots, Splits, and Posts •Max Inj Pressure Pressure = 160 MPa
FUEL INJECTION SYSTEM COMMON RAIL SYSTEM IN DODGE RAM 3500 •Third generation Common Rail injector architecture •Total injection of 130cc •Pilot •Pilot injection injection – Low and mid mid range speed speed noise noise •Gear driven injection pump •160 Mpa of Fuel Fuel Injecti Injection on Pressure Pressure
http://www.dodge.com/en/2008/ram_3500/capability/engines/
FUEL INJECTION SYSTEM DIFFERENCE IN PIEZO AND SOLENOID ACTUATION
FUEL INJECTION SYSTEM PIEZO PIEZO ELECTRIC ELECTRIC COMMON COMMON RAIL RAIL SYSTEM SYSTEM – (BOSCH) (BOSCH)
•Fuel Emission •Better Fuel Consumptions Consumptions •More Engine torque and power •Reduced NVH
Bosch Video File
FUEL INJECTION SYSTEM PIEZO INJECTION SYSTEM IN JEEP 3 LITRE V6 CRD
First use use of Piezo injection injection in a North North American American SUV SUV 30 percent improved fuel economy without sacrificing performance Peak pressure of up to 240 Mpa.
FUEL INJECTION SYSTEM FUEL SYSTEM PERFORMANCE
FUEL INJECTION SYSTEM FUEL SYSTEM PERFORMANCE
FUEL INJECTION SYSTEM FUEL INJECTOR TESTING Performance Tests • • •
Micro performance – hea heavily inst rumented rumented Macro perfor performa mance nce – gain gain curves, c urves, delivery delivery characteristics characteristics Parametric rametric Sensitivity nsiti vity – repea repeatability tability + variability variability
Struct tr uctur ure es Te Tests st s •
Test Tests s @ elevated temp tempera eratu tures res and pressu pr essures res defin e strengt st rength h+ dynamic fatigue factor factors. s.
Endurance Endur ance Te Test •
Tests that combi co mbine ne eleva elevated ted temperatures temperatures and pressu res with wit h specified specif ied fuels and and lubri lu bricants cants to determi determine ne wea wear & life. li fe.
Systems ys tems Integr Integra ation ti on •
Combines Combi nes hardware hardw are and sof tware tw are,, on-e on -eng ngin ine, e, and off -eng -engin ine, e, to develop control strategies
FUEL INJECTION SYSTEM FUEL INJECTOR FAILURES
Plunger wear
Tip splitting
Cavitation Erosion
Tip breakage
Crack
FUEL INJECTION SYSTEM ELECTRONIC CONTROL SYSTEM BUILDING BLOCKS
FUEL INJECTION SYSTEM
Gasoline-Engine Fuel Delivery Systems
FUEL INJECTION SYSTEM Gasoline Engines The power produced by the spark ignition engine is directly proportional to the mass airflow entering it. Control of engine output and the corresponding torque at each engine speed is regulated by governing the amount of air being inducted via the throttle valve. The engine produces maximum power when the throttle valve is fully open (WOT, or wide open throttle). Because maximum maximum possible torque is proportional to fresh-air charge density, it is possible to raise power output by compressing the air before it enters the cylinder.
FUEL INJECTION SYSTEM Air Fuel Ratio The theoretical theoretical ideal for complete complete combustion combustion is a mass mass ratio of 14.7:1, referred to as the stoich stoichiom iometr etric ic ratio. ratio. The air-fuel mixture is a major factor in determining the spark-ignition engine’s rate of specific fuel consumption. Genuine complete combustion and absolutely minimal fuel consumption consumption would be possible only with excess air, but here limits are imposed by such considerations considerations as mixture flammability and the time available for combustion. Certain engine operating operating conditions conditions make mixture mixture adjustments to nonstoichiometric nonstoichiometric ratios essential. With a cold engine for instance, where specific adjustments to the A/F ratio are required.
FUEL INJECTION SYSTEM Excess Air Factor The designation designation l (lambda) (lambda) has been been selected to identify the excess-air excess-air factor (or air ratio) used to quantify the t he spread between the actual current mass A/F ratio and the theoretical optimum (14.7:1): λ
= Ratio of induction induction air mass mass to air requirement requirement for stoichiometric stoichiometric combustion.
λ
= 1: The inducted air mass corresponds to the theoretical requirement.
< 1: Indicates an air deficiency,producing deficiency,producing a corresponding corresponding rich mixture. mixture. Maximum power is derived from λ =0.85...0.95.
λ
> 1: This range is characterized characterized by excess air and lean mixture, leading to lower fuel consumption and reduced power. The potential maximum value for λ – called the “lean-burn limit (LML)”
λ
As can be seen, there is no single excess-air excess-air factor which can can simultaneously simultaneously generate the most favorable levels for all three factors. Air factors of λ = 0.9...1.1 produce “conditio “conditionally nally optimal” optimal” fuel econo economy my with“co with“conditi nditional onally ly optimal” optimal” power power generatio generationin nin actual practice.
FUEL INJECTION SYSTEM Spark-ignition engines with manifold injection produce maximum power at air deficiencies of 5...15 % (λ = 0.95...0.85),but maximum fuel economy comes in at 10...20% excess air (λ = 1.1...1.2). GDI engines can operate with substantially higher excess air factor (λ = 4).
FUEL INJECTION SYSTEM
Optimum A/F ratio and ignition angle
FUEL INJECTION SYSTEM Injection system Operating States Cold s tarting During cold starts the relative relative quantity of fuel in the inducted mixture decreases: decreases: the mixture mixture “goes lean.” This lean-mixture phenomenon stems from inadequate blending of air and fuel, low rates of fuel fuel vaporization, and condensation condensation on the walls walls of the inlet tract, all of of which are promoted by low temperatures. To compensate for these negative factors, and to facilitate cold starting, supplementary fuel must be injected into the engine. Post-start ost -start phase Following low-temperature low-temperature starts, supplementary fuel is required for a brief period, until the combustion chamber chamber heats up and improves the internal mixture formation. This richer mixture also increases torque to furnish a smoother transition to the desired idle speed. Warm-up phase The warm-up phase follows on the heels of the starting and immediate post-start phases. At this point the engine still requires an enriched mixture to offset off set the fuel condensation on the intake-manifold walls. walls. Lower temperatures are synonymous with less efficient fuel processing (owing to factors factors such as poor mixing of air and fuel and reduced fuel vaporization). This promotes fuel precipitation within the intake manifold, with the formation of condensate fuel that will only vaporize later, once temperatures have increased. These factors make it necessary to provide progressive mixture enrichment enrichment in response to decreasing temperatures t emperatures..
FUEL INJECTION SYSTEM Idle and and part-load p art-load Idle is defined as the operating status in which the torque generated by the engine is just sufficient to compensate for friction losses. The engine does not provide power to t he flywheel at idle. Part-load (or part-throttle) operation refers to the range of running conditions between idle and generation of maximum possible possible torque. Today’s standard concepts rely exclusively exclusively on stoichiometric stoichiometric mixtures for the operation operation of engines running running at idle and partthrottle once they have warmed to their normal operating temperatures. Full load lo ad (WOT (WOT)) At WOT (wide-open (wide-open throttle) supplementary supplementary enrichment may be required. This enrichment enrichment furnishes maximum torque and/or power. Ac A c c eler el erat atii o n and an d d ecel ec eler erat atii o n The fuel’s vaporization potential is strongly affected by pressure levels inside the intake manifold. Sudden variations in manifold pressure of the kind encountered in response to rapid changes in throttle valve aperture cause fluctuations in the fuel layer on the walls of the intake tract. Spirited acceleration leads to higher manifold pressures. The fuel responds with lower vaporization vaporization rates and the fuel layer within the manifold runners expands. A portion of the injected fuel is thus lost in wall condensation, and the engine goes lean for a brief period, until the fuel layer restabilizes. In an analogous, but inverted, response pattern, sudden deceleration leads to rich mixtures. A temperature sensitive correction function (transition compensation) compensation) adapts the mixture mixture to maintain optimal operational operational response and and ensure that the engine receives the consistent air/fuel mixture needed for efficient catalytic-converter catalytic-converter performance.
FUEL INJECTION SYSTEM Requirements of Gasoline injection systems
-To supply the engine with with the optimal airfuel mixture for any given operating conditions. -Maintaining air-fuel mixtures within precisely defined limits, which translates into superior performance in the areas of fuel economy, comfort and convenience, and power. -Meet emission norms
FUEL INJECTION SYSTEM Classification of Gasoline injection systems
Injection systems External A/F Mixture formation
SPI
MPFI
Internal A/F Mixture formation
Direct Injection
FUEL INJECTION SYSTEM Gasoline-Engine Fuel Delivery Systems Direct (In-Cylin (In-Cylinder) der) Fuel-Injection ????
1996
Ad A d v anc an c ed Mul Mu l t i -Por -Po r t Fuel-Injection
Multi-Port-Fuel-Injection
1995
1980
2004 Single-Point, Throttle-Body Fuel Fuel Injection Injecti on
1980 Carburetor 1900
1985
2005
1995
FUEL INJECTION SYSTEM External A/F Mixture formation 1. Sing Single le poin pointt inj injec ecti tion on -Injector is located above the throttle plate -Operate at low pressure (0.7 to 1 bar) - The inje injecto ctorr is flush flushed ed continuously by the fuel flowing through it in order to inhibit the formation of air bubble.
1 Fuel tank, 2 Electric Electric fuel fuel pump, pump, 3 Fuel filter, filter, 4 Pressure Pressure regulato regulator, r, 5 Injector, Injector, 6 Air-tempe Air-temperatu rature re sensor, sensor, 7 ECU, 8 Throttle Throttle actuato actuator, r, 9 Throttle Throttle potent potentiome iometer, ter, 10 Canister Canister-purg -purge e valve, valve, 11 Carbon Carbon canister, canister, 12 Lambda Lambda sensor, sensor, 13 CoolantCoolant-tempe temperatu rature re sensor, sensor, 14 Ignition Ignition distribu distributor, tor, 15 Battery, Battery, 16 Ignition Ignition switch switch,, 17 Relay, Relay, 18 Diagnost Diagnostic ic connector connector,, 19 Central Central injectio injection n unit. unit.
- Centrally Centrally located located solenoid solenoid controlled fuel injector
FUEL INJECTION SYSTEM External A/F Mixture formation
-Injector is located above the throttle, in the air intake path -Fuel is sprayed in the orifice between the housing and the throttle plate
central injection unit 1 Pressure Pressure regulato regulator, r, 2 Air-temper Air-temperature ature sensor sensor,, 3 Injector, Injector, 4 Upper Upper part part (hydraul (hydraulics), ics), 5 Fuel supply, supply, 6 Fuel return, return, 7 Insulato Insulatorr plate, plate, 8 Throttle Throttle valve, valve, 9 Lower Lower part. part.
-For cold start –Injection time is extended. Throttle actuator adjusts the throttle position to supply more air. This is sensed by potentiometer and ECU initiates increase in fuel quantity.
FUEL INJECTION SYSTEM External A/F Mixture formation 2. Multi Point fuel Injection -Main control control variables variables – Air flow and engine speed -Pressure differential between fuel and intake manifold is maintained at 3 bar such that injected fuel qty is only dependent on opening period of the valves
1 Fuel Fuel tank, tank, 2 Electr Electric ic fuel fuel pump pump,, 3 Fuel Fuel filte filter, r, 4 ECU, ECU, 5 Inject Injector, or, 6 FuelFuelpressure pressure regulat regulator, or, 7 Intake Intake manifold, manifold, 8 Electric Electric start start valve, 9 Throttle Throttle switch, switch, 10 Air-flow Air-flow sensor, sensor, 11 Lambda Lambda sensor, sensor, 12 Thermo-tim Thermo-time e switch, switch, 13 Coolant-t Coolant-temper emperature ature sensor, sensor, 14 Ignition Ignition distributor distributor,, 15 Auxiliary Auxiliary-air -air valve, valve, 16 Battery, Battery, 17 Ignition Ignition switch switch
-ECU delivers control pulses whose duration depends on engine speed, intake air flow (primarily) and other variables
FUEL INJECTION SYSTEM External A/F Mixture formation Ai A i r f l o w s ens en s o r Intake air flow deflects the flap which is converted by a potentiometer in to voltage ratio and fed to ECU Throttl hro ttle e valve switch swi tch Transmits a control signal to ECU when the throttle valve is either completely closed (Idle) or fully open (WOT) Au A u x i l i ary ar y A i r v alv al v e Supplies engine with additional air during warm-up phase. This T his supplementary air compensates for the cold engines higher frictional losses Electric lectri c sta st art va v alve & Thermo Thermo time ti me switc h During low temp start, the valve injects additional fuel into intake manifold. Thermo time switch activates the electric start valve
FUEL INJECTION SYSTEM Injector -Injector consist of Housing with coil , valve seat with spray orifice disk and a moving valve needle with solenoid armature. -Fuel strainer protects injector against contamination -O ring seals injector in rail and in intake manifold
1 O-rings, O-rings, 2 Filter Filter strainer, strainer, 3 Valve Valve housing housing with with electri electrical cal connecti connection, on, 4 Current Current coil, coil, 5 Spring, Spring, 6 Valve Valve needle needle with with solenoid armature, armature, 7 Valve seat with spray-orifice spray-orifice disk.
-When the coil is de-energized, the spring force and fuel pressure press the valve needle in its seat to seal the fuel supply. -When the coil is energized, the coil generetes magnetic field which attracts armature and lifts the valve needle from its seat and allows the fuel to flow through the injector.
FUEL INJECTION SYSTEM Adjustments for various operating conditions
FUEL INJECTION SYSTEM Disadvantages of Manifold injection -Problems may occur at idling because of incomplete fuel evaporation due to low air flow velocity into cylinder -Distribution of air flow into different inlet pipes may vary -Amount of fuel injected is less accurate at idling because electromagnetic electromagnetic injection valves are time controlled. There There is a large large impact on on amount of fuel injected at small small injection times.
FUEL INJECTION SYSTEM Fuell Sys Fue ystem tem
Carburetor Single-Point, Throttle-Body Fuel Injection Injectio n Multi-PortFuel-Injection A d v an Ad anc c ed Multi-PortFuel-Injection Direct-FuelInjection
Transient
Cold
Mixture
Cost &
Emiss missions ions &
Emiss missions ions &
Preparation
Complexity
Control
Control
Quality
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FUEL INJECTION SYSTEM Internal A/F Mixture formation Gasoline direct Injection
1 Fuel supply supply (high (high pressure pressure), ), 2 Accumulato Accumulatorr (rail), 3 Fuel inject injector, or, 4 Ignition Ignition coil coil with spark spark plug, plug, 5 Phase Phase sensor sensor,, 6 Pressu Pressure re sensor sensor,, 7 Knock Knock sensor, sensor, 8 EngineEngine-spee speed d sensor, sensor, 9 EngineEnginetemperature sensor, sensor, 10 Lambda sensor sensor (LSU), 11 Three-way Three-way catalytic catalytic converter converter,, 12 ExhaustExhaust-gas gas temperature sensor, 13 13 NOX catalytic converter, 14 Lambda Lambda sensor sensor (LSF).
FUEL INJECTION SYSTEM Operating concept and basic feature
Compare to SI engine, Gasoline direct-injection direct-injection system are characterized by : •
Inject Injecting ing the the fuel fuel dire directl ctly y into into the the comb combust ustion ion chambe chamberr with with high high pres pressur sure e.
•
A/FA/F-mi mixt xtur ure e form format atio ion n take takes s plac place e insi inside de the the cyl cylin inde der r
FUEL INJECTION SYSTEM Basic features 1.
Upright straight intake ports :
A strong down flow is generated along the intake intake cylinder during during the intake stroke and tumble motion motion in the flow is generated in the opposite direction of the regular regular four valve valve engines. engines. 2.
High pressure fuel injection pump
A swash type type axial plunger pump pump for high volumetric efficiency efficiency Is used for the high pressure fuel injection which which provides provides high pressure fuel directly injected into the cylinder 3.
High pressure swirl injector
An electronic magnetic magnetic injector was was used to achieve achieve accurate and precise control of injection quantity and timing 4.
Curved top piston
The top land configuration is changed to provide provide a cavity ,right under the spark plug tip which is aimed to strength the air motion
FUEL INJECTION SYSTEM Stra tr atifi ti fie ed Charge Engi Engine ne
During intake stroke air enters the cylinder Near the end of the compression stroke fuel is injected and directed by the piston head bowl towards the spark plug The mixture at the spark plug is “rich” in fuel thus easy to ignite but the amount of fuel injected results in an overall “lean” fuel-air mixture Lowers heat transfer to the walls but increases thermal cyclic load on the spark plug, and standard catalytic converter doesn’t work
FUEL INJECTION SYSTEM Influencing factors •
Temperature In Influence
-
Low Low temp temper erat atur ure e = gaso gasoliline ne cann cannot ot evap evapor orat ate e comp comple lete tely ly
• Fuel droplet-size -
Smaller droplet vaporize quicker
• A/F mixture formation in the homogeneous homogeneous operation operation mode -
Fuel Fuel is inje inject cted ed duri during ng the the indu induct ctio ion n str strok oke e mixture
maximum time for formation of the A/F
-
Inta Intake ke air air can can assi assist st in ach achie ievi ving ng rapi rapid d eva evapo pora rati tion on
•
A/F A/F mix mixtu ture re form format atio ion n in in the the stra strati tifi fied ed-c -cha harg rge e mod mode e
-
Fuel Fuel is inje inject cted ed duri during ng the the com compr pres essi sion on stro stroke ke A/F mixtur mixture e can be transpor transported ted to the vicinity of the spark plug Homogeneous charge (near full load) - Early Early injection injection during during induction induction stroke stroke - Fuel distri distributed buted throu throughou ghoutt the CC Stratified charge (at part load) - Injection Injection during during the compress compression ion stroke stroke - Fuel concen concentrated trated in the the region region of spark plug plug
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FUEL INJECTION SYSTEM Comparison of Manifold injection and GDI
FUEL INJECTION SYSTEM Pros: • Fuel Fuel efficiency effic iency • High po wer wer outp ut • Emission c ontrol • No throttling loss • Engine speed speed contr co ntrol ol by b y EMS EMS • Fuel Fuel requirement
Cons: • Complexity • Cost pressure e • High f uel pressur
