Woodyard D. (ed.) Pounders Marine diesel engines and Gas Turbines
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546 Deutz
The gas-exchange valves are therefore arranged directly in the head, with the
advantage of providing better cooling of the seat rings.
Engines for marine applications were equipped with single-circuit mixed
cooling, with a coolant pump mounted and return cooling system for engine,
lube oil and charge air-cooling. A raw water pump could be attached.
TBD 645 SERIES
Introduced in 1993, the Deutz 645 engine was a 330 mm bore/450 mm stroke
design produced in six-, eight- and nine-cylinder in-line versions to serve
propulsion plant and genset drive requirements from 2550 kW to 4140 kW at
600/650 rev/min (Figures 20.1 and 20.2).
FIguRE 20.1 Cross-section of Deutz 645 engine. Note how the main bearing caps
are bolted in the lower part to both sides of the crankcase, imparting high crankcase
stiness
The monobloc crankcase is made of ductile cast iron, the side walls extend-
ing far down below the crankshaft centreline. It is provided with suspended
crankshaft bearings, large service access openings and continuous mounting
rails. The main bearing caps are bolted in the lower part to either side of the
crankcase to ensure high crankcase stiffness. The crankshaft is of heat-treated
forged steel and machined on all surfaces. The main and big end bearings are
designed as grooved bearings. The die-forged diagonally split connecting rods
feature a toothed joint and a stepped small end. The shank cross-section is of
double-T configuration, with cooling oil supplied to the piston through a bore.
A forged steel crown and a forged aluminium body form the composite pis-
ton. Three compression rings are carried in hardened grooves in the crown, and
one oil control ring in the body section. All the piston rings have a chromium-
plated working surface.
The thick-walled centrifugally cast cylinder liner is salt bath nitrided to
minimize wear. A separate water guide ring with four passages to the cylinder
head ensures intensive cooling of the upper liner section.
The ductile cast iron cylinder head is of double-bottom configuration and
arranged to accommodate two inlet and two exhaust valves, each fitted with
Rotocaps. The exhaust valves are installed in easily removable cages and can
TBD 645 series 547
FIguRE 20.2 Deutz 645F engine installed in a Dutch trawler
548 Deutz
be exchanged without draining the cooling water. The water-cooled seat insert
is armoured with Stellite F; the valve cones are armoured with Stellite 12 or,
optionally, with Colmonoy 56 for heavy fuel operation.
Valve timing is actuated by a one-piece camshaft with hydraulically pressed-
on individual cams, roller tappets, hollow pushrods and forked rocker arms. The
camshaft can be removed from the side to simplify servicing procedures.
A L’Orange fuel injection system comprises individual fuel injection
pumps, very short injection lines ducted through the lower part of the cylin-
der head, and injectors which are cooled by the engine lube oil system. The
injection pump element and roller tappet are separated by a lip seal. The com-
mencement of delivery is adjusted according to the load applied.
Single-stage pulse turbocharging based on ABB turbochargers is associated
with a two-stage charge air cooler allowing preheating of the air under low
load conditions.
549
C h a p t e r | t w e n t y o n e
MaK (Caterpillar Marine
Power Systems)
The German designer and enginebuilder MaK, formerly a member of the Krupp
group, came under the umbrella of Caterpillar Inc. in 1997 as MaK Motoren,
adding a valuable medium-speed portfolio to the US-based high-speed engine
specialist’s programme. The company was renamed Caterpillar Motoren in the
year 2000, its Kiel and Rostock production facilities eventually becoming part
of Hamburg-based Caterpillar Marine Power Systems. Some MaK models are
also produced at a Caterpillar-owned plant in Guangdong, China.
At the time of the takeover, the MaK range embraced five designs with bore
sizes from 200 mm to 580 mm offering outputs up to 10 000 kW: the ‘new gen-
eration’ M20, M25 and M32 and the longer-established M552C and M601C
models. The latter pair of designs has since been phased out and a fourth new
generation series, the M43, added in 1998. V-cylinder versions of this 430 mm
bore design were launched in 2002, extending the power range of the MaK
portfolio to 16 000 kW.
The new generation of long-stroke medium-speed engines was headed
in 1992 by the 200 mm bore/300 mm stroke M20 design for small ship pro-
pulsion and genset drive duties. A power range from 1020 kW to 1710 kW at
900/1000 rev/min is covered by six-, eight- and nine-cylinder models. The M20
was joined in 1994 by the 320 mm bore/480 mm stroke M32 (detailed from
p. 551). The power gap between the M20 and M32 models was bridged in 1996
by a 255 mm bore/400 mm stroke M25 derivative (Figure 21.1) which covers
an output band from 1800 kW to 2700 kW with six-, eight- and nine-cylinder
models running at 720/750 rev/min. All three engines shared common devel-
opment goals: robustness, high reliability, low overall operating costs, simple
maintenance and extended intervals between overhauls.
Operational reliability was sought by avoiding corrosion, reducing mechani-
cal wear and tear, increasing component strengths and reducing the number of
interfaces. Low operating costs were addressed by low fuel and lube oil consump-
tions, and low-grade heavy fuel-burning capability. Modest maintenance costs
were sought from a reduced number of components, a long service life from com-
ponents, simple regulation and adjustment procedures, and plug-in connections.
550 MaK (Caterpillar Marine Power Systems)
Reduced installation work was achieved by providing simple and easily
accessible interfaces for the shipbuilder. All connection points for fuel, lube oil
and cooling water systems are arranged for convenient access at the free end of
the engine; and the fuel and lube oil filters are already mounted on the engine.
The turbocharger mounting arrangement is variable, either at the flywheel end
or free end of the engine.
High functional integration of components achieved engines with 40 per
cent fewer components than their predecessors. A reduced amount of piping
work in particular (and hence fewer connection points) yielded benefits in
Figure 21.1 The M25 design typied the new generation of engines from MaK
(contrast with Figure 21.8)
assembly, installation and maintenance. The remaining connections, where
possible, are simple plug-in arrangements. Air, water, lube oil and fuel are
guided through bores and plug-in connections inside the individual compo-
nents, leaving minimal external piping in evidence. The charge air duct, for
example, is integrated in the crankcase. The air flows through channels in the
crankcase and water guide ring into the cylinder head to the inlet valves. Thus,
when maintenance work on the head is necessary, no charge air pipe has to be
removed and any danger of leakage or working loose is eliminated. The cam-
shaft is also integrated into the crankcase. Another example is the integration
of a slide valve gear into the fuel-injection pump, eliminating starting air dis-
tributor and control air pipes.
Summarizing the common design features, MaK highlights:
l Underslung crankshaft.
l Stiff engine block with integrated charge air and lubricating oil ducts.
l Dry cylinder block; cooling water only where necessary.
l Long stroke (stroke/bore ratio of 1.5 in the case of the M32 in-line
cylinder engine).
l Up to 40 per cent fewer components than earlier designs.
A high stroke/bore ratio fosters good fuel injection and combustion in a
large combustion space; additionally, the high compression ratio underwrites
low fuel consumption and emission figures.
M32 engine
The M32 engine (Figure 21.2) superseded the well-established M453C series
(Figure 21.8), a 320mm bore/420mm stroke design which had been offered as, a 320 mm bore/420 mm stroke design which had been offered as
an in-line engine with six, eight and nine cylinders or as V12 and V16 versions
with an output of 370 kW/cylinder. A substantial increase in power was yielded
by the 320 mm bore M32 design whose modular construction also achieved an
engine with 40 per cent fewer parts than its predecessor.
The in-line six-, eight- and nine-cylinder M32 models have a 480 mm stroke
and originally yielded an output of 440 kW/cylinder at 600 rev/min, covering
an output band from 2400 kW to 3960 kW at the economic continuous rating
(ECR). The rating was raised to 480 kW/cylinder in 1998 to meet market require-
ments. V-configuration models (12 and 16 cylinders) introduced in 1997 retained
the 420 mm stroke of the M453C design and offered up to 480 kW/cylinder at
750 rev/min. The ECR outputs of the V-versions range from 4800 kW to 7700 kW.
The designer highlighted the following key features of the in-line cylinder
M32 models which mainly targeted marine applications:
l Optimum thermodynamic conditions: A stroke/bore ratio of 1.5 pro-
motes a favourable air/fuel mixture and combustion in a spacious com-
bustion chamber. Simultaneously, a high compression ratio (14.5:1)
fosters low fuel consumption—around 180 g/kW h at full load—and low
noxious exhaust emission values.
M32 engine 551
552 MaK (Caterpillar Marine Power Systems)
l Integral construction: Advanced machining centres allow components
to be fashioned to serve several functions. The engine frame, for exam-
ple, embodies cast-on boxes for the camshaft drive on the flywheel end,
and the vibration damper and secondary pinion gear for auxiliaries on
the free end. The frame also conveys the charge air to the cylinders via a
cast-in duct. The camshaft runs directly in the frame.
l Stiff backbone: The integral engine frame permits the firing and mass
forces to flow through the frame, matching the flux of the lines of force
and with low deformation. Girder-like cross-sections run through the
engine housing in a longitudinal direction yielding, together with stiff
walls, a system with high bending and torsional rigidity. Rigid as well as
resilient foundation work is easily effected, and structure- and air-borne
sound emissions are kept at a low level.
The ‘supporting’ and ‘cooling’ functions are clearly separated in the engine
frame which is immune from any corrosion damage because no cooling water
flows within it. The cylinder liner, however, is cooled where it is most impor-
tant: in the upper region outside the engine frame.
Figure 21.2 upper part of M32 engine
l Robust running gear: The train from piston to crankshaft is designed
for a high load-carrying capacity to secure operational reliability and
provide reserves for future development in line with market demands.
The integral construction ensures a safe bedding for the crankshaft,
camshaft, camshaft drive and cam followers, fostering long service life
values (Figure 21.3).
l Modular system: The integrated sub-assemblies, such as the cylinder
head and engine frame, are complemented by support system modules
designed with a reduced number of components for easy pre-assembly
and flexibility of application. An example is provided by the modular
turbocharging package whose charge air cooler is housed drawer-like in
a console screwed onto the frame (Figure 21.4).
l Functional groupings: Arranged to facilitate operation and maintenance
procedures. The camshaft side of the engine is easily accessible because
there are no obstructions from charge air ducts and other mountings.
The exhaust gas pipes are arranged on the opposite side. An optimized
flow in the cylinder head ensures low flow coefficients in the tandem
conduits for the inlet air and the exhaust gas. Simplified maintenance
was addressed by specifying plug-in type connections throughout, with
special tools only required where conventional tools could not guarantee
an adequate degree of mounting security.
A six-element hydraulic tool is used to release simultaneously the six
nuts securing the cylinder head studs (Figure 21.5). A single bolt tightens the
M32 engine 553
Figure 21.3 M32 crankshaft installation
554 MaK (Caterpillar Marine Power Systems)
Figure 21.4 The M32 engine’s charge air cooler is housed drawer-like in a console
screwed onto the frame
Figure 21.5 A six-element hydraulic tool is used to secure or release the M32 cylin-
der head nuts
clamped joint between the cylinder head and the exhaust gas pipe. The fuel-
injection pump and nozzle can be disconnected by releasing just one screwed
connection.
The connecting rod (Figure 21.6) is split just below the lower edge of the
piston, promoting a low removal height for the running gear. The bearings do
not have to be opened when a piston is drawn.
l Tough materials: Essential castings, such as the engine frame and cylin-
der head, derive stiffness and security against fracture from high-tensile
nodular cast iron structures. The material inhibits elastic movement of
the frame when subjected to firing forces. The circularity of the liners
and the bedding of the plain bearings thus remain virtually unaffected
and the axes of the gearwheels are maintained in parallel.
The material stiffness and stable design of the cylinder head secure a firm
seating for the valves (Figure 21.7). The high Young’s modulus of the nodular
cast iron, the thick combustion chamber bottom and the adjacent cooling bores
combine to foster operational reliability from the chamber and valves. The pis-
ton skirt is also of nodular cast iron, while the steel crown is served by numer-
ous cooling bores.
l Low thermal load: The measured exhaust valve temperature of 390°C
means that the Colmonoy armouring of the valves is highly resistant to
inter-metallic corrosion attacks. A temperature of below 300°C meas-
ured on the outside of the piston crown permits only soft deposits.
M32 engine 555
Figure 21.6 The connecting rod of the M32 engine is split just below the lower
edge of the piston