2011 ICPC SCR Liebherr Stage IIIB Tier 4i Pfeifer .pdf



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ICPC 2011 – 3.5

New Generation of the Liebherr Diesel Engines
D934 / D936, Fulfilling Stage IIIB / Tier4i Emission
Norms with SCR Technology
Dipl.-Ing. Dr.techn. Andreas Pfeifer
Liebherr Machines Bulle, CH

Dipl.-Ing. Oswald Holz
EMITEC Gesellschaft für Emissionstechnologie mbH

Dipl.-Ing. Gernot Graf
AVL List GmbH
Copyright © 2011 AVL List GmbH and SAE International

Highway Machinery, with either particulate filters or
SCR systems applied to cope with tailpipe emission
requirements. Based on market investigations and a
collaborative approach with the respective Liebherr
sister plants, Liebherr Machines Bulle SA has
selected DPF as the main technology path for all
Liebherr engines in its earth moving machinery,
whilst SCR systems will be applied on the engines
powering mobile cranes, crawler cranes, harbour
and maritime cranes.

ABSTRACT
Liebherr Machines Bulle SA has developed together
with AVL and EMITEC a new family of inline diesel
engines for its crane applications to comply with
Stage IIIB / Tier4i emission requirements, using
SCR technology. Based on technology carried over
from the actual Stage IIIA, but using a Common Rail
Injection system and sophisticated software
functionality, engine performance and engine-out
emission levels could be improved significantly.

Key driving factor for the EGR / DPF approach for
earth moving machinery is the uncertain availability
of Diesel emission fluid DEF on each construction
site and the compulsory requirement of a particulate
filter, if the machinery operates within local emission
sensitive areas. On the other hand, SCR technology
was chosen for the crane engines,
since mobile cranes will be able to use
the DEF infrastructure already in place
in Europe and the US for On-Highway
trucks.

Development and application of an urea-based SCR
system was performed to comply well with the new
emission requirements as well as offering a
competitive fuel economy of the engines.

Crawler and harbour cranes see
worldwide operation and therefore will
be faced with diesel fuels with
undoubtedly too high fuel sulfur levels
to allow particle filters and EGR
systems to survive, Figure 1.

Figure 1

COMBUSTION
DEVELOPMENT FOR SCR
APPLICATION

Diesel Fuel Sulfur Levels 2011 [1]

INTRODUCTION

The Strategy
For the reasons explained above it was decided to
apply SCR as the only exhaust after treatment
technology for all Liebherr crane engines for all
markets requiring EU Stage IIIB or US-EPA Tier4
Interim non-road emission standards, see Figure 2.

Since the beginning of 2011, new Diesel engines for
mobile machinery in the power range of 130 – 560
kW have to comply with Stage IIIB / Tier4i emission
requirements. It is the first time, that aftertreatment
devices will see wide range application in Off1

Product

EAS

Engine

Power [kW]

D 834

85 - 120

D 934

129 - 175

7.0

EGR - DPF D 936
D 946

190 - 270

10.5

Earth Movement

D 9508
Cranes
SCR

Figure 2

different waste gate setting), and intake throttle for
thermal exhaust temperature management as well
as Common Rail Fuel Injection Equipment (CR FIE)
specification had to be maintained, see Figures 4
and 5.

Cylinder
Displacment [L]
4.6

300 - 390

11.9

345 - 450

16.2

D 934

129 - 180

7.0

D 936

250 - 300

10.5

D 856

350 - 390

12.4

D 9508

450 - 505

16.2

Stage IIIB EGR/DPF:
Cor e engine

Liebherr Stage IIIB / T4i engines and
applications

Stage IIIA:
Coolant / Oil Sys tem

Com bus tion Sy ste m

Br ea ther s ys tem

Com mon Ra il FIE

Ex haust s ys tem

Thr ottle va lve

Turboc ha rge r

ECU

An additional boundary for the emission reduction
concept was to utilize a modular SCR system using
the same key components for all SCR engines. As
shown by Figure 3 in applying SCR for meeting the
required NOx and PM standards it is the main
challenge of the combustion system to achieve
lowest engine-out soot emissions at a NOx target
below 8,5 g/kWh in order to prevent an additional
diesel particulate filter.

Figure 4

Engine parts commonality with Stage IIIA
engine and with Stage IIIB EGR / DPF
engine: right engine side

0,25

PM in g/kW h

0,20

Stage IIIB EGR/DPF:

Stage IIIA

Cor e engine

ge
al Sta
Actu

0,15

0,10

Com bus tion Sy ste m

Br ea ther s ys tem

Com mon Ra il FIE

Ex haust s ys tem

Thr ottle va lve
CR
+1
AT
L

Stage IIIA:
Coolant / Oil Sys tem

Turboc ha rge r

ECU

0,05
Stage IV
Stage III B

0,00
0

1

SCR

2

3

4

5

6

7

8

9

NO X in g/kW h

Figure 3

Figure 5

Emission reduction Strategy with SCR

In doing so, the use of a new common rail fuel
injection system with high pressure capability was
one of the key elements to be introduced.
Furthermore, quite a number of additional boundary
conditions had to be followed in defining hardware
specifications of the D93x CR SCR Base Engine.
These refer primarily to parts commonality with
Stage IIIA production engine parts as well as with
requirements of parallel Stage IIIB/Tier4i DPF
engine projects.

Engine parts commonality with Stage IIIA
engine and with Stage IIIB EGR / DPF
engine: left engine side

Engine Hardware Specifications and
Combustion Achievements
Figure 6 presents a more detailed comparison of
the final hardware specifications of Liebherr
D934/D936 engines for the Stage IIIA and the new
Stage IIIB/ Tier4i engines. It is important to note, that
the Stage IIIA engines use a PLD UP20 system with
1800 bar injection pressure capability, whereas the
Stage 3B engines use a Solenoid CR system with
2000 bar capability.

Thus, piston and combustion bowl, cylinder head
intake swirl, camshafts, turbo-charger (only with

2

D936 Engine HW specification
Power
Turbocharger
FIE
Nozzle specification
Combustion bowl
Compression ratio
Cylinder head swirl
Cam shaft
EGR system
SCR after treatment type

Stage 3A
270 kW @ 2000 rpm
K29/3571/14.90
Bosch PLD UP20 1800 bar
8 x 145° x 840 ml/30 sec
Serial bowl
17,5:1
1,2
Standard
External EGR
No SCR

Stage 3B / TIER4i
300 kW @ 2000 rpm
K29/3571/14.90
LMB CR 2000 bar
8 x 138° x 650 ml/30 sec
Serial bowl
17,5:1
1,2
Standard
No EGR
V2O5 SCR cat

D934 Engine HW specification
Power
Turbocharger
FIE
Nozzle specification
Combustion bowl
Compression ratio
Cylinder head swirl
Cam shaft
EGR system
SCR after treatment type

Stage 3A
180 kW @ 2000 rpm
K26/2871/6.81
Bosch PLD UP20 1800 bar
8 x 145° x 840 ml/30 sec
Serial bowl
17,5:1
1,2
Standard
Internal EGR
No SCR

Stage 3B / TIER4i
180 kW @ 2000 rpm
B2UG/2871/8.81
LMB CR 2000 bar
8 x 138° x 650 ml/30 sec
Serial bowl
17,5:1
1,2
Standard
No EGR
V2O5 SCR cat

Figure 6

Hardware specification of Liebherr D934 and D936 Stage IIIB / T4i SCR engines vs. predecessor
engine Stage IIIA

A comparison of PM and NOx emissions achievable
with the D936 SCR Tier4i engines (at different
power levels) with different FIE, i.e. PLD vs. CR, is

shown in Figure 7 (Non Road Steady State Cycle,
NRSC) and Figure 8 (Non Road Transient Cycle,
NRTC).

D936 PLD / CR SCRT IER4i
NRSC em issions
0,06 0
D93 6 PLD 2 70k W
0,05 5

D93 6 CR 27 0kW
D93 6 CR 30 0kW

0,04 5

Using P LD FI E the NRSC PM emission i s wi thin
l egi sl ation l imi t b ut i s 49% higher compared to CR FIE

0,04 0
0,03 5
0,03 0

Legal il m it PM: 0,0 25 g/kWh

0,02 5

Using PLD FIE the NRS C NOx emi ssion is above
8,5 g/kWh engi neeri ng target and is 13%
higher com pared to CR FIE

0,02 0

P M_ Tota l

PM_ NV F

D9 36 PLD / CR SC R TIER 4i
NRS C em is sions

0, 002 7

0,0 035

0, 004 8

0,00 0

0 ,0 092

0,0 086

0, 01 32

0,00 5

0,0 119

0,01 0

0, 012 1

0,01 5
0 ,01 80

PM_Tota l, N VF, V OF [g/kWh]

0,05 0

1 0, 0
D 936 P LD 270 kW

PM _ VOF

D 936 C R 2 70k W
D 936 C R 3 00k W

8, 0

7, 0

5, 0

4, 0

NO x Engine-Out

Figure 7

PM and NOx emissions in NRSC, advantage of CR injection system vs. PLD

7, 99

6, 0

7,9 3

8,94

NOx Engine-Out [g/k Wh]

9, 0

D936 PLD / CR SCR TIER4i
NRTC - Hot emission s
0,06 0
D9 36 CR 27 0k W

0,05 0

D9 36 CR 30 0k W

0,04 5

Us in g PL D F IE t he NRT C PM em is sio n i s a bo ve le gi slat io n
lim it be in g 97% h ig h er co m pa re d to CR F IE

0,04 0
0,03 5
0,03 0

Le ga l limitPM: 0 0
, 25 g/kWh

Usin g PLD FI E th e NRT C e ng in e- ou t NOx em is sio n i s
w ell ab ov e 8 ,5 g/k Wh en gin ee ri ng t ar ge t a nd is
4 8% h ig he r c om p ar ed t o CR FI E

0,02 5
0,02 0

D9 36 PLD / CR SCR TIER4 i
NR TC - Hot em is s ion

0,0 023

0,0 035

0, 001 9

0 ,02 49

0, 012 5

0,00 5

0, 014

0, 0144

0,01 0

0 ,0 117

0,01 5

0, 028

PM_ Tota ,l NV F, VO F [g/k Wh]

D9 36 PLD2 70 k W
0,05 5

11, 0
D 936 P LD 27 0 kW

0,00 0
PM _Tota l

PM _N VF

PM _ VOF

D 936 C R 2 70 kW
10, 0

NOx Engine-Out [g/kWh]

D 936 C R 3 00 kW

9, 0

10,2 0

8, 0

7, 0

6, 806

6,89 2

6, 0

5, 0

4, 0

NOx Engine O
- ut

Figure 8

PM and NOx emissions in NRTC, advantage of CR injection system vs. PLD

It is obvious, that at the target NOx-level (8,5 g/kWh
in NRSC and NRTC) significantly lower PM
emissions are achievable with the CR system in
both test cycles. In the NRTC the PLD system yields
significantly higher NOx emissions, and PM
emissions above the limit. As shown by the injection
pressure maps in Figure 9, the reason for the higher
dynamic soot emissions of the PLD FIE engine is its
specific injection pressure characteristic of too low
HP Line Pressure

injection pressure at low load over the entire engine
speed range. The optimized injection pressure map
of the Common Rail FIE (see lower part of Fig. 9)
achieves 97 % PM reduction and 48 % NOx
reduction in the NRTC compared to the PLD engine.
This achievement is of course also a result of the
dynamic operation calibration strategy applied to the
Liebherr CR system.

I_SP0 4 [kPa]

26
24

D936 PLD SCR

The reason for the higher dynamic Soot
emissions of the PLD FIE engine is its
specific injection pressure characteristic
having too low injection pressure at low
load over entire engine speed range.

22
20
18
15
13

14

12

12
90

10
8

00

00
00

11

00

00

00
0

0

16

00

00
00

17

00

00

00
0

00

10

14
00

00

B MEP [ba r]

16

0

0

80 000

6

70 000

Rail Pressure

60 00
0

4
2
0
6 00

24

4000 0
30000

7 00

80 0

900

1 000

1 100

ECU5 [b ar]

26

50 000

12 00 1300 14 00
Engine Spe e d [r pm ]

D936 CR SCR

22
150 0

1600

170 0

1800

1900

2 000
20
15

0

00

B MEP [ba r]

50

00

13

12

50

00

50

00

11

0

50

11

00

10

10

0

85

90

0

0

75

80

8

95

10

0

0
65

6

0

4
60
0

45

0
6 00

700

0

50 0

55

800

0

900

10 00

11 00

12 00 1300 14 00
Engine Spe e d [rpm ]

15 00

1 600

1700

1 800

Injection pressure maps of Stage IIIB engine (Common Rail) vs. Stage IIIA engine (PLD)
4

50

00

00

14
5
13

12

12

2

Figure 9

16

14

14

70

The optimized Common Rail FIE injection
pressure engine map achieves 97% PM
reduction and 48% NOx reduction in NRTC
compared to the PLD engine

50

00

16

15

16

17

18

1 900

2000

on load and engine speed, in order to
compensate the higher dynamic operation NOx
emission due to the dynamic rail pressure
increase

Calibration strategy for lowest possible PM
emission
Besides optimized steady state injection pressure
map calibration, following additional dynamic
operation strategies were used for achieving the
best transient operation NOx / PM trade-off and
invisible smoke in vehicle dynamic operation:


Dynamic operation rail pressure increase –
during highly dynamic operation, the rail
pressure at part load is raised to full load level,
so that even at an air excess ratio as low as
1,05 combustion is without visible smoke thus
allowing very fast dynamic torque increase



Dynamic operation timing retard –
during highly dynamic operation, the start of
main injection is retarded up to 3°CA depending



Smoke puff limiter over intake manifold
pressure signal was selected due to its
flexibility and high effectiveness

It is interesting to note, that due to the dynamic
injection pressure and injection timing flexibility of
the Common Rail system nearly invisible smoke
(less than 6% Opacity) at full load acceleration can
be achieved at dynamic air excess ratios as low as
1,05. As a result, the same vehicle acceleration
performance is achieved with the Stage 3B engine
as with the earlier Stage 3A engine, see Figure 10.

Figure 10 Vehicle acceleration performance and transient smoke emission: Stage IIIB SCR engine vs.
predecessor
The dynamic response of the Stage 3B Crane Drive
engine (D934 CR SCR TIER4i) is significantly
improved compared to the Stage 3A engine, see
Figure 11.

The latter shows the available engine torque
improvement 1 second after dip-in of the Stage 3B
engine compared to that of the Stage 3A engine.
 Available max torque (1 second after dip in) of
Stage 3B engine increases significantly compared to
the Stage 3A engine

Maxi mal Dynamic Perf ormance
1200

S teady S tate Full Load Curve

1000 rpm: Available max. Torque of Stage 3B
increasing by 25% fulfilling the same target engine
speed deviation as Stage 3A engine

1100

Torqu e (N. m )

1000

Stage 3B

900

800

1100 rpm: Available max. Torque of Stage 3B
increasing by 50% fulfilling the same target engine
speed deviation as Stage 3A engine

Sta ge 3A

700

 Similar engine speed deviation performance as
with Stage 3A engine in the whole engine speed
range, without visible smoke

600

500
800

1000

1200

14 0 0

16 0 0

18 0 0

20 0 0

Eng ine s pe e d (r pm )

Figure 11 Dynamic behavior of Crane Drive engine: Comparison of Stage IIIB SCR engine vs. predecessor

The most effective measure to immediately increase
exhaust temperatures is to throttle the air flow.

Exhaust Temperature Management

T _41 , T_ 51, T _61

2400
2100
1800
1500
1200
9 00

LM B-D936CR_TB107.102
LM B-D936CR_TB107.058

Figure 12 demonstrates the influence of throttling on
exhaust temperatures upstream and downstream of
the SCR catalyst during the first time phase of the
Cold Start NRTC. By use of the intake throttle valve
the exhaust gas and SCR catalyst average
temperature are reached and maintained above the
target 280°C being required for efficient NOx
Commercial up
Powertra
System
s
conversion from the 260th second
to inthe
end
of
the Cold NRTC.

With Throttle valve - Cold test
Without Throttle valve - Cold tes t

250 0
225 0
200 0
175 0
150 0
125 0
100 0
750
500
250
0

4 00
3 75
3 50
3 25
3 00
2 75
2 50
2 25
2 00
1 75
1 50
1 25
1 00
75
50

T_ 51 - te mp be f or e SCR cat
T_ 61 - te mp aft e r SCR cat

T_61

T _5 1

Eng n
i e T orq ue

Engi ne Speed

Once Stage 3B/Tier4i engine-out emission targets
have been achieved and successfully demonstrated
(see previous Figures 8 and 9) as a prerequisite for
the application of SCR systems, it is important to
manage dynamic exhaust temperatures to the levels
required by the SCR system for sufficient NOx
conversion, especially after the engine start at cold
engine conditions and at low load conditions, as they
typically occur during the last third of the NRTC.

T he us e o f a n i nta ke Th r ot tle va lve is a llo wing t o r ea ch and ke e p t he ex hau st ga s an d
SCR ca t av er ag e tem pe r atu r e o ve r 280°C r e qu ir ed fo r h ig h NO x c on ve r sion e ffi cie ncy
f ro m 26 0 se c t ill e nd of Co ld NRT C cycle

10 0

200

30 0

40 0

50 0

6 00

700

80 0

90 0

10 00

11 00

12 00

Figure 12 Effect of intake throttling on exhaust system temperatures during cold NRTC

Figure 13 compares the influence of air throttling for
the same engine during Cold NRTC and Hot NRTC.
It can be seen that by throttling the target 280°C
exhaust temperature level is achieved approx. 100

seconds earlier during the hot start test cycle than
during the cold start NRTC test.

6

Commercial Powertrai n System s

LMB-D936CR_TB107.102
LMB-D936CR_TB107.103

Wit h Throttle valve - Cold test
Wit h Throttle valve - Hot test

2 100
1 800
1 500
1 200
90 0

250 0
225 0
200 0
175 0
150 0
125 0
100 0
750
500
250
0

T_ 41, T_5 1, T _61

40 0
37 5
35 0
32 5
30 0

T_ 51 - te mp be fo r e SCR cat
T_ 61 - te mp aft e r SCRc at

T _61

T _51

Eng n
i e To rq ue

Engin e Speed

2 400

27 5
25 0
22 5
20 0
17 5
15 0
12 5
10 0

Th e us e o f an in ta ke T h r ott le va lve is al low ing to r eac h and ke ep th e e x hau st g as and
SC R cat av er ag e t em pe r atu re o ve r 280°C r eq ui r ed fo r h ig h NO x c on ve r sion ef fi cien cy
c a. 1 00 se c ear lie r du rin g th e Ho t N RT C cycl e

75
50
10 0

2 00

30 0

40 0

50 0

6 00

7 00

80 0

90 0

100 0

110 0

120 0

Figure 13 Influence of air throttling in cold and hot NRTC on exhaust system temperatures
A
self-diagnostic
procedure
is
included,
communicating with the ECU via the CAN bus. The
system is connected to the engine coolant for
defrosting.

SCR AFTERTREATMENT SYSTEM
Components of the Exhaust Aftertreatment
System
As described before, a common approach for all
Liebherr Stage III-B engines intended to be
equipped with a SCR system should be used. A
modular system could be achieved using the same
urea dosing unit and the same urea injector for all
four engines from four to eight cylinders. Two
catalyst systems - using an existing canning from
the Stage III-B DPF systems - reduce the variety of
parts for Liebherr.
UREA DOSING UNIT
It was decided to use an airless dosing system, as
the engines will be used in applications where
pressurized air is not available. The Emitec NoNOx
urea dosing system, Figure 14, is designed to
deliver a precise amount of urea in form of a
volumetric flow rate into the diesel exhaust systems.
The required quantity is calculated by an algorithm
in the integrated controller, considering the used
catalyst performance under varying conditions like
exhaust gas mass flow, temperature and NOx
concentration.

Figure 14 Emitec NoNOx Urea Dosing Unit
REDUCTANT DELIVERY UNIT (UREA INJECTOR)
The injector used, Figure 15, is based on a robust
gasoline injector which is in high volume production
for gasoline engines. This gives advantages in
respect of robustness, cost and flexibility in adaption
for different requirements. To meet the demanding
off road requirements an injector cooling system was
added, which is connected to the engine coolant.

7

Extensive simulation and testing was performed to
optimize the system layout in order to avoid
deposits. Unacceptable urea deposit can occur (see
Figure 17) if the injector position and spray is not
well adapted to the exhaust gas flow and
temperature.

Figure 15 Reductant Delivery Unit with water
cooling
Figure 17 Unacceptable urea deposit (left with HCat; right without H-Cat)

CATALYST SYSTEM
To fulfil the emission requirements of 4 engines in
more than 45 installations from 129 kW up to 505
kW power, two system sizes have been defined:


For the reduction catalysts also structured metallic
foils are used: LS- and LS/PE structure. This results
in higher catalyst efficiency due to the generated
„turbulence like flow“ in the channels compared to a
catalyst with „laminar“ channels at the same catalyst
dimensions.

Low Power System (LPS) up to 300 kW,



High Power system (HPS) for the power range
above.
The catalyst volume was adapted to the higher
exhaust mass flow for the HPS by increasing the
diameter.

MX

LS/PE

Slip Cat
R-Cat

R-Cat

Figure 18 Structured foils used for H-Cat (MX) and
R-Cat (LS/PE and LS)

H-Cat

H-Cat

R-Cat

To avoid ammonia slip under all conditions a slip
catalyst was added using a 50.8 mm short metallic
substrate with adapted coating.

Figure 16 Catalyst system (sketch)

SYSTEM VALIDATION
Besides meeting the emission targets, avoiding of
urea deposit - as described above - is a major
challenge in application of an airless SCR system.
The goal was achieved by optimizing all relevant
parameters such as

The catalyst system, Figure 16, consists of a mixing
pipe with hydrolyses catalysts and a reduction
catalyst assembly with a slip catalyst incorporated.
The goal of the hydrolyses catalyst (H-Cat) is to
ensure the evaporation of the injected urea and
enhance the ammonia formation, as the tubing
between the mixing pipe and the reduction catalyst
assembly can vary for different applications. For the
H-Cat a metallic catalyst support with MX structured
foil design (see Figure 18) is used with an adequate
coating. Ammonia distribution measurements
confirm an enhanced NH3 and also HNCO formation
- showing an improved urea conversion - compared
to a system without the H-Cat.



injector spray and orientation,



injector position

 position and design of the H-Cat.
As a result a system without any deposit at different
load points could be demonstrated while meeting the
emission requirements with a safety margin,
Figure 19.
8

FINAL EMISSION RESULTS OF D936 CR
SCR STAGE 3B/TIER4I ENGINE
Figure 20 demonstrates emission results over the
NRSC and the NRTC, respectively. Thanks to the
layout of the combustion system, the SCR system
and the exhaust temperature management applied a
SCR NOx conversion efficiency of 79% could be
achieved to meet the Stage IIIB / Tier4i emission
standards with sufficient margin against catalyst
ageing.

Figure 19 H-Cat: no deposit after 10 h @ A 25 load
point

D936 CR SCR TIER4i
NRSC PM and NOx EO & TP emissions
0,050

9, 0
D936 CR 300kW - PM em issi on
D936 CR 300kW - NOx emi ssi on

8, 0

0,035
0,030
0,025

Legal PM lim it: 0,025
/

79, 4% NOx reduction
with S CR

7, 0

8,290

PM_Total [g/kWh]

0,040

6, 0
5, 0
4, 0

0,020

N Ox [g/kWh]

0,045

3, 0
L egal NOx l imi t: 2 g/ kWh

0,005

0, 0090

0,010

2, 0
1, 710

0,015

1, 0
0, 0

PM_Tot al

NOx Engine-Out

NOx Tail-Pipe

D936 CR SCR TIER4i
NRTC PM and NOx EO & TP emissions
0,050

9, 0
D936 CR 300kW - PM em ission
D936 CR 300kW - NOx em issi on

8, 0

0,035
0,030
0,025

Legal PM li mit: 0,025
/

78, 5% NOx reduction
with S CR

7, 0

7, 54

PM_Total [g/kWh]

0,040

6, 0
5, 0
4, 0

0,020

3, 0
Leg al NOx l im it: 2 g/kWh

1, 62

0,010

2, 0
0, 0133

0,015

0,005

1, 0
0, 0

PM_Tota l

N Ox Engine-Out

NOx Tail-Pipe

Figure 20 NRSC (top) and NRTC engine-out and tailpipe emissions of D936 Stage IIIB SCR engine
9

NOx [g/kWh]

0,045

CONCLUSION
To comply with the specific requirements of Stage
IIIB / Tier4i engines in crane applications, an airless
SCR approach was chosen in favor of the
mainstream technology EGR / DPF.
First investigations based on the Stage IIIA engine
configuration pointed out, that applying the Stage
IIIA PLD injection system, falls short of meeting the
soot emission limits especially under transient
conditions. The additional degrees of flexibility of the
Common Rail system were favorably used to
achieve lowest dynamic soot emission, low
combustion noise and a significantly improved cold
start performance of the engine even with the high
drive resistance of the hydraulic pump drive
engaged. The application of an intake throttle valve
allowed to increase the exhaust temperature level at
engine part load significantly to improve – or even
enable – sustainable NOx conversion ratios with the
SCR system without causing deposits of the injected
ammonia.
As outlined in this paper, a robust engine and
aftertreatment system configuration could be
established, satisfying both, emission, transient
performance and fuel consumption requirements.

REFERENCES
[1]

UNEP: Diesel Fuel Sulfur Levels Global
Status, January 2011, www.unep.org/pcfv

DEFINITIONS, ACRONYMS,
ABBREVIATIONS
CR
DEF
DPF
EGR
FIE
H-Cat
HPS
LPS
PLD
NRSC
NRTC

Common Rail Injection System
Diesel emission fluid
Diesel Particle Filter
Exhaust Gas Recirculation
Fuel Injection Equipment
Hydrolyses Catalyst
High Power System
Low Power System
Pump-Line-Nozzle Injection System
Non-Road Stationary Cycle
NON-Road Transient Cycle

10


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