Advanced Fuel Inj Technology Future Diesel Powertrain

Advanced Fuel Injection Equipment - Technology serving Future Diesel Powertrains

Prof. Dr.-Ing. Jürgen Hammer, Diesel Systems Business Unit PC,

Robert Bosch GmbH, Stuttgart

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1. SummarySince introduction of the Common Rail Diesel injection system on the PC/LDV mar-ket in the year 1997, BOSCH production plants output is bigger than 70 millions sys-tems ‘til today.

Anyway since launch date markets were strong changing. Facing this also require-ments on modern diesel engines did change dramatically. Core market for Diesel PC and LDV is mainly driven out of emission legislation EU6 ff and in parallel fulfilling benchmark targets in fuel consumption. Diesel powertrains are the key enablers to reach the given CO2 targets for carmakers fleets in Western Europe. Due to Diesels cost attractiveness in the competition of powertrains against gasoline, alternative fuels and at least electrification aiming the target of 95 g/km in 2020, the Diesel share in al-most all vehicle segments will be pushed. To reach in parallel stringend NOx emis-sions also under real driving conditions, beside exhaust gas treatment, the FIE tech-nology plays a key role to reduce raw emissions and optimize the combustion towards highest power output at lowest fuel consumption on gasoline like comfort level.

Looking to the strong growing markets in India and China, Diesel powertrain technol-ogy is serving basic mobility and transportation needs at lowest fuel consumption and therefore costs. “High value for money” also on the injection technology side is re-quired together with robustness needs and wide range of fuel quality acceptance for use in also very big range of vehicles for transportation and off-highway applications.

This broad project landscape from robust cost innovation up to benchmark perfor-mance levels BOSCH is serving with a modular product strategy in FIE. This paper gives an overview on those systems which equips from dedicated products families 1-cylinder load carriers up to premium luxury vehicles also foreseen with hybridization.

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2. Market and Drivers

ATZ_Standard für Grundschrifttexte

Fig.1: Market forecast shares of different powertrains worldwide

Fig.1 shows overall prognosis worldwide of powertrain shares. Since Diesel is stable slightly growing towards 2020 around 24 % overall market share the main regions serving that trend is WEU all time high with around 50 %. US is expected to ignite in Diesel share in the LDT and SUV segment but also coming in the sedan area e.g. known from the VW Jetta and announced Cruze from GM other will follow. Last but not least luxury limousines from german carmakers are already successful lauchend. Stable growth in IN due to the immense transport need of all people suffering on cost attractive vehicles beside 2 wheelers. In addition CN market is seen to be growing in the off road and light commercial area.

Out of thermodynamic reasons Diesel is and will stay as the most efficient ICE con-cepts. In addition at least CO2 target in WEU of 2020 of 95 g/km Diesel will be also the most cost effective solution gaining the overall fleet value, Fig2. Both leads to an attractiveness of the Diesel powertrain in almost all segments to the TCO for end con-sumer in addition to an overall powertrain portfolio for the carmakers gaining their CO2 fleet targets.

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Fig.2: cost comparison fuel price and consumption Diesel vs. Gasoline

Fig.3: CO2 Emissions versus Costs: Tank-to-Wheel, 2015, Compact Class CC

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Source: KBA J ahresbericht 2010

0

40

80

120

160

200

CO2 E

miss

ionen

[g/km

]

Gasoline-Technology Diesel-Technology

7,7 l/100 km

5,5

4,7

vehic

le

2,9 l/100 km

2,6

vehic

le

4,4l/100km

3,8Po

wertr

ain

5,4 l/100 km

3,6

3,2

G0

Powe

rtrain

130

95*

146

70*

G2

G2H

D0

D3D3H-51%

-52%

-29%

-39%

-33%

-41%

EU27 fleet value 2009: 146 g/km

vehicle technology rolling friction: -30%weight: -10%specific air resistance : -14%

Vehicle weight: 1400kg, 100 kW, NEFZG0-G2,D0-D3: manual switch G2H,D3H: automatic transmission

* targets proposed by European Commission

CO2-reduction by vehicle technology

80

90

100

110

120

130

140

150

160

170

5

5,5

6

6,5

7

7,5

8

8,5

2001 2003 2005 2007 2009 2011

fuel

pric

e [

€ce

nt /

l]

feul

con

sum

ption

of n

ew p

assa

enge

r ca

rs in

Ger

man

y[l/

100k

m]

cost comparsion fuel price and consomption Diesel vs. Gasoline

diesel engine [l/100km] gasoline engine [l/100km]

diesel price [ € cent/l] gasoline price [€ cent /l]

020406080

1001201401601802002200 50% 100% 150% 200% 250% 300% 350% 400%

Gasoline Diesel

Add-on System Costs for OEM [%]

CO2[

g/km]

Internal combustion engine: Gasoline (PFI / DI)CNG Compressed Natural GasDiesel

SmallElectric Vehicle

DI =1

PFI

Diesel

HEV strong

HEV mild

2025

Benefit W-EU:

???CNG

95 CO2[g/km]


Fig.4: Diesel technology modules gaining WEU Emission Legislation

Fig.5: Diesel technology modules gaining IN Emission Legislation

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LuxuryEntry (A/B) Standard (C/D) Light-DutyDiesel SystemProposal EU 20202020 2020

Engine

Displacem.Spec. Power

CO2

FIE

I3or I4 1.2 – 1.6 l40 kW/l 60 kW/l

1600/1800

I4 1.6 l – I4 2.2 l55… 60 kW/l (TC²: 70…80 kW/l)

I4 1.8 – I6/V6 3-0 l60…70 kW/l (TC²: 80…95 kW/l)

2000 upto 2500

20001600/1800/2000 2500

2020

Major or newrequirements

95 g CO2/kmin 2020

WLTP forCO2 in 2015 ?

WLTP foremiss. in ̀ 17 ?

RDE docustarting 2015

RDEcompliance ̀ 17

EGTEU6+RDE

NSCcDPF SCR

DPF DOC

CuC

(SCR

)

AdBlue-DM

Strong Hybrid (HEV)Plug-In HEV

Strong HybridBoost Recup. Sys.

E-Drive

PC (B/C)SUV

EGTBS5

E-Drive

Mainstream

Entry (A)

Engine

Displacem.Spec. Power

CO2

FIE

Diesel SystemProposal IN

DOC cDPF

Major or newrequirements

BS4 3-WheelIn 2015

BS5 LPV & PCin 2016

LowestCost

I3 1.0l - I4 2.5 l30… 60kW/l

1400/1600I2 NA 0.7 – 1.0l

25 kW/l

1400I2 TCIC 0.7–1.2 l

35 - 45 kW/l

1400

Boost Recup.


Looking at the overall technology key stones for a Diesel PT one can state some basic findings for FIE besides Diesel engine technology and exhaust gas treatment equip-ment:

Overall main requirements on FIE Technology:

full flexible injection pressure

maximum pressure depending on combustion, air and EGR system and rated power target

full flexible multiple injection capability

application specific no of injections, dwell time, minimum quantity and tolerances

nozzle technology with robust compromise coking vs. holeefficiency, optimized sac hole volume

These so-called CR standard requirements [1-8] to be specifically quantified for each application, have to be extended segment- and market-wise. For example looking into Diesel powertrains for luxury cars even combined with hybrid technology extends this basic requirements towards ultimate efficiency of the hydraulic system, comfort issues and last but not least towards best class fuel metering capabilities like special injection rate shapes for partial and full load, lowest tolerances using 8 injection events per stroke by having smallest injection quantities up to rated pressure. Due to benchmark maximum torque demands and rated power outputs similar to gasoline engines, high-est injection pressures like 2500 bar and in future gaining still more is demanded, Fig. 4. Addressing future hybridization in this segment which is short term foreseen, FIE has to be qualified in terms of additional needs like higher numbers of start events, very fast speed up to the high pressure pump, stand by pressure during stop phases, long sleeping modes of the ICE etc. ,Fig. 6

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On the other hand the emerging market is addressing completely different add-ons like cost down first and robustness resp. simplification for application and oil lubrica-tion of the high pressure pump is mandatory. Load carrier applications combining very low engine displacements with relatively high good loads and total vehicle weights lead to very high duration times at full load operation and strong load collec-tives on the components. This addresses robustness measures on the components those have to be included into the modular FIE components system, Fig. 8.

Fig.7: Special view WEU and US luxury applications on FIE requirements

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Fuel Economy/ Downsizing Injection Pattern: Flat NOx-map Digital Rate-Shaping

t_diff< 200µs

Min. Mechanical Losses Hydraulic Efficiency:

Start-Stop InjectorRelease Pr.:100.. 120 bar

Injection Precision closed loop controlfor best metering performance over life time

HC/CO vs. NOx Reduced HC-Volume"nano" or "i-midi" nozzle

HighPeak Power System Pressure2500bar - 3000 bar1)

Reduced system and Simplified fuel circuit,e.g. CP4i, no returnlineto tankand calibration costs Cal. effort e.g. Zero Fuel Cal. ≠ f(drivetrain)

1) e.g. for TOP-Segment, 2020


Fig8: Special view India applications on FIE requirements

Since maximum injection pressure is always a key topic in Diesel due to the fact that mixing time is pretty short, spray momentum and spray formation are key enablers for lowest raw emissions and fuel consumption and finally nozzle flow rate have to be optimized in the balance of maximum rated power and spray quality [1-8] some words to upcoming trends in high pressure requirements all over the world, Fig. 9.

Fig.9: RB CR Systems by pressure and region

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Lifetime requirement 200.000 km, 1.0 bn. Injections Fuel consumption Hydraulic Efficiency:

FPC (Feed Pump Control) Soot/NOx Strategy for Low Cost Injector

Pilot quantity: 1.5 – 2.4 mm³, pRail +200bar DPF Regeneration 3 Post Injections Noise Injector Pattern: Double Pilot (-3dB) Power Demand System Pressure 1450 bar

/ Full Load Legislation Full Load Tolerances +/- 1.6 mm³/str @ 24 mm³/strw/ IQA 1) +/- 3 mm³/str @ 45 mm³/str

Fuel Quality Robustness against ParticlesISO22 with Filter Class C

38%43%

45%35%

18%

1%

1%100%

2018

5%

40%

34%

1%

2014

6%

41%

18%

2013

5%

40%

10%

2012

4%

46%

7%

2011

5%

52%

5%

1300 bar1400 bar1600 bar

1800 bar2000 bar

2200 bar2500 bar

9% 76%

2200 bar 100%

2500 bar 100%

1%

15%

48%

2000 bar

52%

1800 bar 51%

48%1600 bar

100%

100%

1400 bar

EURNAMAPA LAM

Year 2018 by Regions

Source: VPZ2012-1 ID1012


All in a nut shell, western world standard and high end applications are front runners in maximum pressures of todays 2200 bar and foreseen 2500 bar in 2014. Require-ments are already on the table gaining the magic 3000 bars. In the average 2000 bar is establishing as a standard in WEU-applications. Looking to India and China we have 1400 bar and 1600 bar as next step. Additionally development is addressing 1800 bar for upcoming emission legislation e.g., CN5 and applications in the LD and MD seg-ments using full load EGR.

3. BOSCH Modular Common Rail System TechnologyThe overall road map of BOSCH Common Rail System Technology for PC and LDV shows 3 Generations which basically are built up on specific components technolo-gies, Fig. 10.

Fig.10: Roadmap CRS generations for PC/LD

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PlatformStudy


While on the injector technology CRS 1 and CRS2 uses top head solenoid valves to control the servo driven Diesel fuel injectors is CRS 3 based on the so – called Piezo – inline injector technology. High pressure pumps are divided in oil lubricatedunit pumps for different flow rates used in Gen 1, fuel lubricated pumps from 1600 up to 2500 bar pressure ranges in all Generations, while the 1 – and 2 plunger CP4 – family is exlusively used in the Gens 2 und 3. A derivate of a engine intergrated oil lubricated version of the CP4.1, the so – called CP4i is under development to serve also car makers who want to built engilnes for world wide use and combine 2nd Gen CRS with oil lubricated high pressure pumps, a system architecture example will be given later.

Fig.11: Common Rail Pump CP4 Modularity

Looking on the system architecture of the so – called CRS1-14 UP one can see the fo-cus what is really needed for the dedicated market. In generell 1 upt to 3 cylinders are equipped with the CRS-14 UP. Performing up to 25 resp. 50 kW/L with naturally as-pirated resp. turbo charged engines. Max. system pressure is 1450 bar, max. 3 no of injections per stroke, dwell time min of 800 microseconds fulfilling lifetime require-ments of 200 000 km and targeting emission levels BS3/4.[9]

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CP4-18

1800bar

CP4-20

2000bar

CP4-22

2200bar

cylinder headcylinder headcam drive

cylinder headcam drivebearings

CP4-25

2500bar

bearings/hsg.cylinder headcam drivebearings/hsg.lp circuitCP4 2nd Gen

1600bar

Performance

Value

fuel

lubr

icat

edoi

l lub

ricat

ed

CP4i 1)

1800bar w/ st

d. h

sg.

w/o h

sg.

CP4i Key feature fluid separation Optional reduced complexity by

standard housing

CP4-16-55

1600bar


Fig.12: System architecture CRS1-14 UP

As an example a 2 cylinder system is shown. Starting from the tank with electrical lift pump as pre – supply modul the fuel runs over the main filter to the Fuel Control Unit (FCU) which is separately placed in front of the Unit Pump (UP). The FCU provides a controlled amount of fuel on a constant pressure to be filled in the UP. Using this de-vice only the demanded fuel flow to keep the rail pressure on its target value is pres-surized. In comparison to maximum pumping all the time, consumption benefits on the engine of up to 8 % can be realized. Doing so the standard UP former used in stan-dard cam-driven injection systems can be carried over w/o any changes on the engine, staying oil lubricated and with only minor changes for example at the I/O valves and cam slopes at the pump drive. For the OEM which uses normally a engine family for decades gives this a lot of commercial benefits.After pressurizing the fuel runs to the Rail Pressure Sensor Block (RPS-Block) which has the main functions to distribute the fuel to the injectors and carries the rail pressure sensor for pressure metering. Skipping the rail and using RPS-block saves money, mounting space and reduces the weight of the high pressure storage. Last but not least used CRI1-14 injectors are spe-cial inventions for IN market needs in terms simplified components for attractive prices. Based on the well – known top head solenoid injectors of BOSCH launched in 1997 the CRI1-14 was designed with a simplified solenoid group with a non-guided one part armature, extended tolerances and de-contending measures like skipping the C-coating on the nozzle needle. The system has already entered successfully different PC and LDV applications in the Indian market.

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Looking on the WEU all time high Diesel market we have to address both focus points like attractive cost at high performance simultaneously. Fig. 13 shows a new approach consisting already established components with brand new ones in a innova-tive high intergrated FIE on the engine.

Fig.13: System architecture CRS2-20 with CP4i

While rail configuration with pressure control valve and sensor stays well know as al-ways first big change shows the pump. The so – called CP4i is an engine intergrated oil lubricated high pressure pump which is driven directly via roller tapet and cam slope from the engine cam shaft. Therefore no lubrication flow to the pump dieselwise is needed which gives the opportunity to skip the backflow line and reduces the power and delivery capacity of the pre-supply pump drastically. Challenge in this concept is the sealing system of the pump drive which has to tighten the oil chamber of the en -gine to the fuel element of the high pressure pump. Both pathes fuel in oil and oil in fuel requires very low leackege rates to avoid oil dilution on the engine and to prevent oil contamination in the fuel which leads to nozzle cocking and particulate trap blog-ging due to oil ashes. The CP4i itself is quantity controlled by a electrical suction

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valve which shows benefits in dynamics and damping low pressue pulses in compari-son to an suction control via throttling.

The CR2-20 as the benchmark common rail injector technology of top head solenoids is shown in Fig. 14. Using unique pressure balanced valve technology introduced in 2007 [11] with the CRI 2-18, was successfully tranfered to the CRI2-20 concept. Very fast switching armature with only 25 µm stroke gives the chance to control the long needle for the sake of very small quantities and dwell times lower than 200 mircosec-onds. Capability of up to 8 injection events per stroke at lowest control and leackage quantities. Since the needle is also pressure balanced there is no leckeage to the low pressure back flow.

Fig.14: CRI2-20 with closed loop control

Special design of the CRI2-20 allows to locate a pre -rail volume in the injector to feed fuel after opening the needle very fast and damping the pressure waves coming from a previous injection to the next leading to accurate multiple injection quantities lowest hydraulic dwell times. Due to the fact that the control chamber topside of the needle is closed by the armature bolt each and every pressure change in the chamber leads to a force change on the lower side of the armature bolt. This force change now can be used to detect the needle opening and closing behavior and in the end to calcu -late via model the hydraulic open time of the needle. The force is guided via amature bolt to a piezo element which measures the signal and put this via wiring harness to

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CRS2-20

Engine cylinders 3...8Max. system pressure 2,000 barMax. number of injections

8

Min. injection separation time

200 µs

Operating voltage 12 VEmission target corresponding to...

Euro 5/6

Service life PC/LD 300,000/400,000 kmApplication PC/LD

1200

1400

1600

1800

2000

2200

0,0 0,4 0,8 1,2 1,6 2,00,0

0,2

0,4

0,6

0,8

1,0

p_valve_chamber [bar]p_control_chamber [bar]

nozzle needle lift [mm]


the ECU. No additional cable is needed. Fig. 14 shows typical signals out of the injec-tor during injection events. Having this signal one is able to control injection quanti-ties over life time via closed loop control in the CRI2-20. [12]

Since 2003 with the very impressive lauch for the Audi A8 V6 TDI fulfilling EU4 legislation w/o additional exhaust gas treatment first time Piezo inline injection tech-nology from BOSCH, the so called 3rd generation was used. Based on this we de-velop the ultimative piezo injection technology with 2500 bar maximum system pres-sure for premium segment vehicle classes.

Fig.15: System architecture CRS3-25 6. cylinder

Al high pressure components are qualified to the 2500 bar pressure level in a opti -mized hydraulic efficiency, package and of course weight an life time manner.

By qualifying the CRI3-25 on the high pressure level we did change the control valve design to a force reduced approach in comparison to the previous generations [11]. Leaving the piezo actor – coupler “actor chain” as very successful in the market with benchmark quality figures in the CRI3-20, we adjust the load on the servo valve by placing a bold guided in a sleeve to the low pressure side of the throttle plate. His al-lows to switch the 2500 bar pressure level with lower actor forces like we have on the CRI3.20 using 2000 bar injector. With sophisticated hydraulic layout tools we were able to create a injector performance fulfilling requirements of the engine like smallest pilot quantities at highest pressure, 8 injections per stroke, lowest dwell times and ex-tended life time, Fig. 16.

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Backflow Pressure High Pressure

Tank

Main filter (incl. Water separator)

RIT

PRT

Return Line Pressure el. Presupply Pump Pressure

EFP

EDC17CPCP4-25/2

DHV3-25FRL3-25

CRI3-25

PCV3-25HFR-25RPS4-25

PCV: pressure control valveFRL: fuel return lineRPS: rail pressure sensorHFR: hot forged rail RIT: Rail w/ throttles


Fig.16: CRI3-25 functional sketch

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CRS3-25

Engine cylinders 3...8Max. systempressure 2,500 barMax. number of injections

8

Min. injection separation time

< 200 µs

Operating voltage 12 VEmission target corresponding to...

Euro 5/6

Service life PC/LD 300,000/400,000 kmApplication PC/LD


Literature

[1] Dohle, U., Dürnholz, M., Hammer. J., Kampmann, S., Hinrichsen, C., Ziegler, G.:

4th Generation Common Rail Injection System for Future Emission Legislation, FISITA Barcelona 2004

[2] Dohle, U., Dürnholz, M., Hammer, J.: Evolution on Advanced Common Rail In-jection Systems for Diesel, ATA International Diesel Conference - Low PM and NOx Technology, Bari 2004

[3] Dohle, U., Dürnholz, M., Hammer. J., Kampmann, S., Hinrichsen, C., Wintrich, T.: Die 4. Generation Common Rail Dieseleinspritzung – Neue Ansätze zur Erfüllung höchster Kundenerwartung und gesetzlicher Anforderungen, 4. Tagung Diesel – und Benzindirektreinspritzung, Haus der Technik, Berlin 2004

[4] Kampmann, S., Hammer, J., Mattes, P.: Weiterentwicklung von Common Rail Einspritzsystemen zur Erreichung künftiger Emissionsgrenzen, 7. Tagung Motorische Verbrennung – Aktuelle Probleme und moderne Lösungsansätze, Haus der Technik, München März 2005.

[5] Dohle, U., Kampmann, S., Hammer, J., Böcking, F.: Potenzial moderner Diesel - Common Rail Einsritzsysteme zur Erreichung künftiger Emissionsgrenzen, 26. Inter-nationales Wiener Motorensymposium, Wien April 2005

[6] Böcking, F., Dohle, U., Hammer, J., Kampmann, S.: Pkw – Common Rail Sys-teme für künftige Emissionsanforderungen, MTZ, 66. Jahrgang, Juli/August 2005, S. 552 – 557

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[7] Hammer, J.: Evolution of the Common Rail Technology, Ingegneria dell’ AU-TOVEICOLO, Giornale ed atti della “Associazoone technical della’Automobile”, Vol. 58 – N.7/8 Luglio/Augosto 2005, p. 24 – 28

[8] Dohle, U., Dürnholz, M., Kampmann S., Naber, D., Hammer, J., Lehle, W.: Com-mon Rail Einspritzsysteme – Kernbaustein künftiger Pkw – Dieseltechnologie, 10. Symposium Dieselmotorentechnik, Stuttgart März 2006

[9] Kremer A,: Besondere Anforderungen und FIE Lösungen für aufstrebende Diesel – Märkte, Diesel- und Benzindirekteinspritzung, 8. Tagung, Haus der Technik, Berlin 28th November 2012

[10] Maier R. : The next genaration BOSCH Common Rail Injectors with digital rate shaping – akey factor for meeting future requirements, 33rd International Vienna Mo-tor Symposium Wien 2012

[11] Leonhard R., Warga J. Pauer T., Boecking F., Straub D.: Bosch 200bar Common Rail System for Passenger Cars and Light Duty vehicles

[12] Meyer S., Krauss, J.; Präzise Zumessung über Lebensdauer in einem Common-Rail-System, Diesel- und Benzindirekteinspritzung, 8. Tagung, Haus der Technik, Berlin 28th November 2012

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Advanced Fuel Inj Technology Future Diesel Powertrain

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