MAN B&W Low Speed

Small Bore Engines

Now with Electronic Control

MAN Diesel
 Contents

Introduction.................................................................................................. 5
Engine data............................................................................................. 7
Engine comparison.................................................................................. 8
ME-B fuel injection control system............................................................... 10
Injection performance............................................................................ 10
Engine control system............................................................................ 10
Engine Design S35/40/50ME-B................................................................... 11
Bedplate, framebox and cylinder frame.................................................. 12
Crankshaft............................................................................................. 13
Connecting rod...................................................................................... 14
Bearings................................................................................................ 14
Combustion chamber............................................................................ 15
Cylinder liner.......................................................................................... 15
Piston.................................................................................................... 15
Exhaust valve........................................................................................ 16
Fuel injection equipment........................................................................ 17
Thrust bearing....................................................................................... 18
Engine control system............................................................................ 18
Turbocharger and air cooler arrangement............................................... 19
Concluding Remarks................................................................................... 19

MAN B&W Diesel

MAN B&W Low Speed Small Bore Engines - Now with Electronic Control 3
 MAN B&W Low Speed Small Bore Engines
Now with Electronic Control

Introduction Since the delivery of the first L35MC in ways moving, and requirements for
The MAN B&W 35MC engine was 1982, a total of ~1,000 L35MC, ~500 more competitive engines, i.e. the low-
launched in 1982 as the L35MC with S35MC, ~200 L42MC and ~250 S42MC est possible propeller speed, lower fuel
500 kW/cylinder and a mean effective engines are on order or have been de- consumption, lower lube oil consump-
pressure of 14.8 bar at 200 rpm. Sev- livered. More than 1,000 S50MC-C has tion and more flexibility regarding emis-
eral design updates, often combined been delivered since 1997. sion and easy adjustment of the engine
with a power up, have been introduced parameters, call for a re-evaluation of
since then, and with today’s Mark 6 rat- The above-mentioned small bore two- the design parameters, engine control
ing, the power per cylinder is 650 kW/ stroke engines have been the world and layout.
cylinder with a mean pressure of 18.4 leaders in their market segment for
bar at 210 rpm. decades. However, the market is al-

To meet the market demand for lower

propeller speed, and thereby higher
propulsion efficiency, the long-stroke
S35MC (see Fig. 1) was launched in
1993 with 170 rpm and a mean pres-
sure of 18.4 bar, resulting in 700 kW/
cylinder.

Since then, the S35MC engine has

been extensively used in the propulsion
of a wide variety of vessels ranking in
sizes from 5,000 to 25,000 dwt.

To cater for the increasing market de-

mand for higher power, an uprated ver-
sion of the S35MC was introduced in
1998 with a mean effective pressure
of 19.1 bar at 173 rpm, thus providing
740 kW/cylinder.

The market also required direct coupled

two-stroke engines in the 5-10,000 kW
output area. The S42MC was therefore
introduced with 136 rpm with a cylinder
power of 995 kW/cylinder at a mean ef-
fective pressure of 18.5 bar.

Based on an increasing market demand

for higher-powered super long-stroke
small bore engines, the S42MC was up-
rated in 1999. The mean effective pres-
sure was increased to 19.5 bar at 136
rpm, thus providing 1,060 kW/cylinder. Fig. 1: MAN B&W S35MC cross section
MAN B&W Diesel
MAN B&W Low Speed Small Bore Engines - Now with Electronic Control 5
Our marketing investigation into this
Required SMCR power
segment, including scrutinising the
kW
power against propeller speed for tank- 20,000 Containers
Tankers
ers, containers and bulkers, has shown Bulkers
that a 35 cm bore engine with a slightly S50ME-B9
reduced speed and a higher engine 9 cyls. S50ME-B8
power will suit well. In the segment for 15,000 9 cyls.
8 cyls.
the S42MC type, a 40 cm bore engine 8 cyls.
with 146 rpm will, together with an up- 7 cyls.
7 cyls.
dated 35 cm bore engine, cover the
6 cyls.
required output area between the S35 10,000 6 cyls. S40ME-B9
5 cyls. 8 cyls.
and the S46MC-C very well, 5 cyls. 7 cyls. S35ME-B9
6 cyls. 8 cyls.
The continuous development of mer- 7 cyls.
117 5 cyls.
5,000 6 cyls.
chant ships to be even more efficient 127 5 cyls.
is never ending. The aft body of the 99 146
ships for example may be designed to 108 167
124 142
fit even larger propellers, which again
have a higher propeller efficiency, but a 0 r/min
90 100 110 120 130 140 150 160 170
lower optimum propeller speed. SMCR speed

Average power and speed demand ME-B types:

As the two-stroke main engine is nor- curves for container vessels,
mally coupled directly to the propeller, tankers and bulk carriers: S50ME-B7/8 (19.0/20.0 bar)
Stroke = 2,000 mm (S/D = 4.00)
thereby avoiding the reduction gear NMCR = 1,580/1,660 kW/cyl x 127 r/min
and its loss of efficiency, the design of
S50ME-B9 (21.0 bar)
modern main engines has to be based Stroke = 2,214 mm (S/D = 4.43)
on a continuously lower engine speed NMCR = 1,780 kW/cyl x 117 r/min

(r/min). S40ME-B9 (21.0 bar)

Stroke = 1,770 mm (S/D = 4.43)
NMCR = 1,135 kW/cyl x 146 r/min
With the new S50ME-B, which will be
S35ME-B9 (21.0 bar)
designated Mk 9, we have introduced Stroke = 1,550 mm (S/D = 4.43)
a competitive engine designed for new NMCR = 870 kW/cyl x 167 r/min

modern hull designs, based on more

efficient propellers with a lower opti- Fig. 2: Power against propeller speed

mum propeller speed. The engine will

adopt the design features introduced
on the smaller ME-B engines, and will
be introduced with a mep of 21 bar at
117 rpm. ing S50 Mk 7/8 range. This will make it The S50ME-B7/8 will have the same
possible to benefit from this technology performance and installation data as
However, as the ME-B technology has also in existing ship designs if applica- the S50MC-C/ME-C7/8. Main data for
clear cost benefits for engines in the tion of the advanced S50ME-C type is the two series appear in the table.
lower power bracket, we have decided not considered feasible.
to make this available also for the exist-

6 MAN B&W Low Speed Small Bore Engines - Now with Electronic Control
 Both types will also be available in con-
ventional turbocharger versions with
+2g/kWh higher SFOC, respectively.

The layout diagram of the ME-B9 en-

gine types, superimposed on the ex-
pected combination of speed and
power of the target ship groups; con-
tainer ships, tankers and bulk carriers,
are shown in the enclosure.

The S50ME-B7/8 and 9 engines will be

available in configurations of five to nine
cylinders.

In addition, the market acceptance of

electronically controlled engines is now
turning into a market demand. There-
fore, the new engine with a future elec-
tronic fuel system control will be desig-
nated ME-B, i.e. S35ME-B, S40ME-B
and S50ME-B respectively.

Engine data
The new 35, 40 and 50 ME-B9 engines
will have a stroke bore ratio of 4.4:1
(the same as that of our research en-
gine 4T50ME-X) to facilitate low propel-
ler speed; 167 rpm for the S35ME-B.
The S50 ME-B8 has a stroke bore ratio
of 4:1 (the same as the S50MC-C) 146
rpm for the S40ME-B, and 117 rpm for
the S50ME-B.

Cross section S40ME-B

MAN B&W Diesel

MAN B&W Low Speed Small Bore Engines - Now with Electronic Control 7
The new engines will be introduced Engine comparison A comparison of 8S50ME-B9 and
with a mean effective pressure of 21 A comparison between a 6-cylinder of 9S50MC-C7 shows that the S50ME-
bar offering the following engine data, the new MAN B&W S35ME-B and a B has 20 kW more power than a
see Table 3. 7-cylinder of the existing S35MC has 9S50MC-C7, and a more efficient r/min
resulted in 40 kW more power, 0.42 m of 117 r/min instead of the 127 r/min
The specific fuel consumption for the shorter engine length, 3 ton lower en- making it possible to use a propeller of
Mk 9 versions has been reduced by 2 gine mass and 2 g/kWh lower SFOC, larger diameter which is more efficient.
g/kWh by using a higher firing pressure. Table 4.
Furthermore, the new 8S50ME-B7 is
A comparison between a 6S40ME-B 0.37 m shorter and 22 tonnes lighter.
and the existing 6S42MC shows that
the 6S40ME-B can supply 5% more All of the ME-B engines have a 2 g/kWh
power and is 0.42 m shorter. lower SFOC.

The engine weight is 16 tonnes less As mentioned earlier, electronically

(11% lighter). controlled fuel injection has been cho-
sen for the new engines.

Engine Data

L1 Unit 5-8S35ME-B9 5-8S40ME-B9 5-9S50ME-B9 5-9S50ME-B7/8

Bore mm 350 400 500 500
Stroke mm 1,550 1,770 2,214 2,000
MEP bar 21 21 21 19/20
Speed r/min 167 146 117 127
Mean piston speed m/s 8.6 8.6 8.6 8.47
Power kW/cyl. 870 1135 1780 1580/1660
SFOC g/kWh 171-176 170-175 162-169 159-170

Table 3

8 MAN B&W Low Speed Small Bore Engines - Now with Electronic Control
 6S35ME-B against 7S35MC

Engine Type 6S35ME-B9 7S35MC Deviation

Power 5,220 5,180 + 40 kW
Speed 167 173 - 6 r/min
Length 4,990 5,409 - 419 mm
Mass 81 84 - 3 ton
Specific weight 15.5 16.2 - 0.7 kg/kW
SFOC 176 178 - 2 g/kWh

Table 4

6S40ME-B against 6S42MC

Engine Type 6S40ME-B9 6S42MC Deviation

Power 6,810 6,480 + 330 kW
Speed 146 136 10 r/min
Length 5,700 6,117 - 417 mm
Mass 127 143 - 16 ton (11%)
Specific weight 18.6 22.1 - 3.5 kg/kW
SFOC 175 177 - 2 g/kWh

Table 5

8S50ME-B7 against 9S50MC-C7

Engine Type 8S50ME-B9 9S50MC-C7 Deviation

Power 14,240 14,220 20kW
Speed 117 127 -10 r/min
Length 8,950 9,324 -374 mm
Mass 289 311 -22 tom
Specific weight 20.3 20.8 -0.5 kg/kW
SFOC 169 171 -2 g/kWh

Table 6

MAN B&W Diesel

MAN B&W Low Speed Small Bore Engines - Now with Electronic Control 9
ME-B fuel injection control system
The ME-B system is shown in Figs. 7
Dual cylinder HCU
and 8.

While a light camshaft operates the ex-

haust valves in the conventional man-
Cam activated
ner, fuel injection is performed by one exhaust valves

fuel booster per cylinder, similar to the

present ME engine. The boosters are
Hydraulic oil line in
mounted on hydraulic cylinder units containment

(HCU), two boosters on each unit. The

Bearings only near
hydraulic oil is supplied to the HCUs via cams
a single oil pipe enclosed in the cam- Reduced camshaft
diameter
shaft housing. The hydraulic system
pressure is 300 bar.
Fig. 7: ME-B engine

Two electrically driven pumps provide

the hydraulic power for the injection
system. In case of failure of one pump,
more than 50% engine power will be
available, enabling around 80% ship
speed.

Injection performance
The ME-B system will have the same
possibility of rate shaping as the present
ME engines. The injection is controlled
by a proportional valve enabling contin-
uous change of the injection pressure.
Typically, a gradual pressure increase
during the injection is desired.

The injection profile influences the

SFOC as well as emissions. One profile
is often favourable for SFOC, however
at a cost of high NOX emissions, while Fig 8: HCU for two cylinders

the opposite applies for a different in-

jection profile. The injection profile re-
flects a compromise between SFOC
and NOX. Thus, the freedom to choose
the injection profile is a tool that can
be used to minimise the SFOC, while
keeping emissions within given limits.

10 MAN B&W Low Speed Small Bore Engines - Now with Electronic Control
 Engine control system On Bridge
Bridge Panel
Several factors serve to reduce the
necessary extent of the Engine Control In Engine Control Room

System (ECS). MOP B MOP A ECR PANEL

„„ A number of features included in the

present ME system can be omitted as
EICU
these may be provided from the en-
gine surroundings as for MC engines In Engine Room / On Engine
ESC

„„ Capacity for control of exhaust valve

movement is no more required CCU1 CCU ½n

„„ Starting air control

Booster
Pressure
Booster
Pressure
„„ Auxiliary blower control

ALS ALS
ELFI ELFI
„„ Pump control simplified
HCU (cyl1+2)
HCU

Fig. 9 shows the layout of the engine

control system for the ME-B. The sys- HPS
tem will utilise the same MPCs as the
traditional ME control system.
One Multi Purpose Controller (MPC)
can control the injection on two cylin- MPC - Multi Purpose Controller
EICU - Engine Interface Control Unit (MPC )
ders. The EICU placed in the engine CCU - Cylinder Control Unit (MPC)
MOP - Main Operating Panel CRANKSHAFT
HPS - Hydraulic Power Supply
control room will control the hydraulic CPS - Crankshaft Position Sensors POSITION
SENSORS - CPS
ESC - Engine Side Console
pressure and is also connected to the ALS - Alpha Lubricator System

Bridge control system.

It should be noted that a 6-cylinder Fig. 9: Engine Control System for ME-B

ME-C engine requires 13 MPCs where-

as the corresponding small bore ME-B
may require four MPCs only.

MAN B&W Diesel

MAN B&W Low Speed Small Bore Engines - Now with Electronic Control 11
Engine Design S35/40/50ME-B
Bedplate, framebox and cylinder S35ME-B
frame
The structural parts have been de-

1270
signed with respect to rigidity and
strength to accommodate the higher
output for these engines. See Fig. 10.

980
The bedplate is of the welded design.
For the new engines, the normally cast
part for the main bearing girders is
made from rolled steel plates. This se-

1210
cures homogeneity of the material used
for the main bearing area with no risk of

7376
casting imperfections occurring during
3710

the final machining.

3200

2500
The framebox is of the well-proven tri-
angular guide plane design with twin
staybolts giving excellent support for
the guide shoe forces. This framebox
is now standard on all our updated en-
460

gine types.
1405
950
410

2580 700

Fig. 10: Cross section S35ME-B

For the cylinder frame, two possibilities It has been decided to use nodular cast
are available, see Fig. 12. iron due to its high strength and high E-
modulus for this material to counteract
„„ Nodular cast iron the high ignition force. Compared with
C3Cu material, the weight of a 6S35ME-
„„ Welded design with integrated scav- B cylinder frame can be reduced by 3
enge air receiver. ton, corresponding to a 12% cost down
Fig. 11: Existing and new main bearing designs for the cylinder frame.

12 MAN B&W Low Speed Small Bore Engines - Now with Electronic Control
 OMD and PCO sensors mounted on the manouvering side
Triangular staybolt tube design

Fig. 12: Frame box

The stiffness and stress level have been

carefully evaluated for the main structure Contour (analysis system)
with FEM calculations (see Fig. 13), and Cycle-Amp-Cycle-Amp (scalar valur, max.)
all deformations and stresses are lower
or equal to the level used for our existing
engines, i.e. the reliability of the engine 4.000E+01
structure will be at least at the same 3.556E+01
3.111E+01
level as the existing engines, which have
2.667E+01
proven very good performance. 2.222E+01
1.778E+01
1.333E+01
8.889E+00
4.444E+00
0.000E+00
No result

Max. = 8.632E+01
Min. = 0.000E+00

Fig. 13: Stress calculation

MAN B&W Diesel

MAN B&W Low Speed Small Bore Engines - Now with Electronic Control 13
Crankshaft
The crankshaft is of the semi-built de-
sign, in one piece, and made in material
S34CrNi or S42Cr1, Fig. 14.

Even though the stroke/bore ratio has

been increased for the new engines,
the cylinder distance has been only
slightly increased, (only Mk 9).

Comprehensive FEM calculations were

performed to ensure that the geometry
(incl. journal diameters) of the shaft had
been optimised keeping the rigidity,
shrink fit and stresses on the same level Fig. 14: Semi-built crankshaft for ME-B

as for our MC-C engines.

Connecting rod
The connecting rod is based on the
well-known design used for our entire
small bore engine programme initially
introduced for the L35MC.

To reduce the production cost and os-

cillating forces, the new design is made
of slim design of the crosshead end see
Fig. 15.

Also a new crosshead bearing without New slim type MC Design

oil groove in the loaded area has been

introduced. See Fig 16. Fig. 15: Connecting rod

MC Design
ME-B Slim Design

Fig. 16: Connecting rod, new crosshead bearing Fig. 16: New crosshead design

14 MAN B&W Low Speed Small Bore Engines - Now with Electronic Control
 Bearing Pressure design limit 100% Bearings
The bearings used for the new engines
are of the same design as the one used
100
with very good results on our other
90
small bore engines for now more than
80 15 years. The bearing is of the thin-shell
70 design, and the bearing metal on all the
Main bearing
60 large bearings is of Sn40Al. The rela-
% Crankpin bearing
50 tive loads on the large bearings are in
Crosshead bearing
40 all cases well below our design targets,
30 Fig. 17.
20
Crosshead bearing
10 Combustion chamber
Crankpin bearing
0 With the increased power of the new
Main bearing
S35MC ME-B engines, the combustion cham-
S42MC
S35ME-B, ber has been carefully investigated
S40ME-B to compensate for the higher igni-
tion pressure and higher thermal load
Fig. 17: Bearing load – but also to increase the reliability of
the components and further increase
the TBOs. The combustion chamber is
„„ Slide Fuel valves shown in Fig. 18.
„„ Alpha ACC
„„ High Piston Topland Cylinder liner
„„ Slim cylinder liner A slim cylinder liner which is also used
„„ PC ring on our other small bore MC-C/ME en-
„„ Piston rings with gines is possible for both engine types,
Alu-coat but the material for the cylinder liner
„„ Piston skirt with has been upgraded to Tarkalloy A to
bronze band counteract the higher ignition pressure.
„„ Known to give excel- The PC ring has been introduced to
lent cylinder condition prevent bore polish.
and long TBO

Fig. 18: Combustion chamber

MAN B&W Diesel

MAN B&W Low Speed Small Bore Engines - Now with Electronic Control 15
Piston ring pack with hard coating on the run- oil consumption and still keeping very
The piston is bore-cooled and with a ning surface for piston rings No. 1 can good cylinder condition.
semi-high top land (see Fig. 20). The be supplied as an option.
shape of the piston crown against the The calculated temperature level for the
combustion chamber has been care- As for the larger bore ME engines, the combustion parts is well inside our de-
fully investigated to cope with the in- Alpha Lubricator is standard on the sign value as shown in Fig. 22.
creased power of the new engine. new small bore engines. The ACC lu-
Comprehensive FEM calculations have brication mode is, therefore, now also
been made to develop the piston crown available for our small bore engines
geometry to make it able to withstand with the benefit of a very low total lube
the high firing pressure and high mean
pressure, Fig. 21.

The piston ring pack will be similar to

the rings used for the existing small
bore engines, i.e. No.1 piston ring, high
CPR, Nos. 2 to 4, piston rings with an-
gle cut. All rings are with Alu-coat on
the running surface for safe running-in
of the piston ring. If prolonged time be-
tween overhauls is requested, a special

Fig. 21: FEM investigation of stresses in new piston crown

470°C

550°C
300°C
320°C
310°C
320°C 230°C
370°C 170°C

Fig. 20: Piston Fig. 22: Temperature level in combustion parts

16 MAN B&W Low Speed Small Bore Engines - Now with Electronic Control
 Exhaust valve To have common spare parts for all Fuel injection equipment
The exhaust valve is activated by a light four engines, the exhaust valve used As mentioned earlier, the fuel injection
camshaft (smaller shaft diameter and for the S35 and S45ME-B is the same is electronically controlled via a pres-
smaller size exhaust cam), driven by a as the one used for the S35MC and sure booster like the one used for the
chain drive placed in the aft end of the S42MC, respectively. The exhaust large ME-C engines. There is one Hy-
engine. The size of the chain is reduced valve is of the DuraSpindle type with a draulic Cylinder Unit (HCU) per two cyl-
compared to the MC type. W-seat bottom piece, Fig. 24. inders. The HCU is equipped with two
pressure boosters, two ELFI valves and
two Alpha Lubricators and one accu-
mulator. Thereby, one HCU is operating
two cylinders. Fig. 25.

DuraSpindle

W-seat

Fig. 24: Exhaust valve

Pressure booster

Alpha Lubricator

ELFI valve
Distributor block

Fig. 25: Hydraulic Cylinder Unit (HCU)

MAN B&W Diesel
MAN B&W Low Speed Small Bore Engines - Now with Electronic Control 17
The Hydraulic Power Supply (HPS) of the engine power, approximately Thrust bearing
used for the new small bore engine is 80% speed. In case of malfunction of The thrust bearing design is based on
installed together with 6 mm filters in one of the pumps, it is still possible to the very compact design introduced
the front end of the engine. The HPS is operate the engine with 55% engine with our MC-C engine. As the propel-
electrically driven and consists of two power. ler thrust is increasing due to the higher
electric motors each driving a hydraulic engine power, a flexible thrust cam
pump, see Fig. 26. The same fuel valve type as used on has been introduced to obtain a more
the MC/MC-C will also be used for even force distribution on the pads.
The pressure for the hydraulic oil for the the new ME-B engines. The fuel noz- The overall dimension of the parts can
new system has been increased from zles are of the well-proven slide type therefore be smaller than with the old
the 250 bar used for the normal ME -C already introduced as standard on all design. See Fig. 27.
system to 300 bar. Each of the pumps small bore engines.
has a capacity corresponding to 55%

EL-motor Boll filter

Fig. 26: Hydraulic Power Supply (HPS)

Flex edge

Fig. 27: Thrust cam with flex edge

18 MAN B&W Low Speed Small Bore Engines - Now with Electronic Control
 Engine control system Turbocharger and air cooler ar- Fig. 29. The latest type of water mist
For a 6-cylinder engine, the engine rangement catcher and water drain arrangement
control system consists of four to five Three turbocharger makes are available will be introduced in the new design.
MPCs (Multi Purpose Controller) com- for the new ME-B engines, i.e. MAN,
pared to 13 MPCs necessary for the ABB and Mitsubishi. As an option, we can supply TCA T/C’s
standard ME systems, Fig. 28. with variable nozzle. Hereby better
The position of the turbocharger is, as partload SFOC can be offered due to
for the existing engine, aft mounted, the possibility to control the ratio be-
but will for the new ME-B also be of- tween pmax, pcomp and MEP.
fered as exhaust side mounted. See
The auxiliary blower design will be of
the new integrated type recently intro-

Bridge
Bridge duced on the S50MC-C version. Main-
panel
tenance is also reduced as the belt
drive is omitted for the integrated blow-
Main Main Engine control room ers, see Fig. 30.
operating Control room panel EICU operating
panel panel

Engine room/on engine

Engine
side
console HPS

MPC MPC MPC

MPC

Fig. 28: Engine Control System

Aux. blower housing integrated

in the air cooler housing

Fig. 29: Exhaust side mounted TC Fig. 30: Integrated blower design
MAN B&W Diesel
MAN B&W Low Speed Small Bore Engines - Now with Electronic Control 19
Concluding Remarks
The introduction of the ME-B engine
range marks a future step towards
strengthening our small bore two-stroke
engine position in the market, enabling
the owner to select modern, future-
oriented, electronically controlled, two-
stroke engines as direct coupled prime
movers, also in this segment.

Thanks to the design rationalisations

introduced, an ME-B engine is expect-
ed to be sellable at roughly the same
price per kW as a corresponding MC-C
engine.

Cross section S50ME-B

20 MAN B&W Low Speed Small Bore Engines - Now with Electronic Control
 Copyright © MAN Diesel · Subject to modification in the interest of technical progress. · 5510-0025-02ppr Aug09 Printed in Denmark

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Phone +45 33 85 11 00
Fax +45 33 85 10 30
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