IMPROVED FUEL EFFICIENCY FOR TRUNK PISTON FOUR-STROKE DIESEL ENGINES

CONSOMMATION DE CARBURANT AMELIOREE POUR MOTEURS DIESEL QUATRE TEMPS A PISTON-FOURREAU

English Abstract

The present invention relates to a system (and corresponding method) for
reducing fuel consumption in a four-stroke trunk piston diesel engine, the
system comprising: a replenishment system (102) connected to receive engine
oil from a four-stroke trunk piston diesel engine (100) and to receive
replenishment oil (HFO), where the replenishment system (102) is configured
for mixing the engine oil and the replenishment oil resulting in a mixed oil
(103) that is introduced into the engine (100). In this way, the typical
degradation process of the engine oil is slowed by replenishing it the adverse
effects associated with the degradation process are reduced or slowed or even
avoided in a very simple way. Thus, the replenishment system provides enhanced
and consistent performance of the initial engine oil resulting in greatly
reduced component wear and equipment lifecycle cost. Even further, a more
environmentally friendly system is provided since less waste in the form of
spent oil is produced as the usability period of time for the engine oil is
prolonged. Thus great economical savings and environmental improvements are
achieved.

French Abstract

La présente invention porte sur un système (et sur un procédé correspondant) visant à réduire la consommation de carburant dans un moteur diesel quatre temps à piston fourreau. Le système comprend: un système de régénération (102) raccordé pour recevoir l'huile d'un moteur diesel quatre temps à piston fourreau (100) et pour recevoir l'huile de régénération (fue-oil lourd). Le système de régénération (102) est configuré pour mélanger l'huile moteur et l'huile de régénération obtenue par un mélange d'huile (103) qui est introduit dans le moteur (100). Le processus de dégradation typique de l'huile moteur est ainsi ralenti par sa régénération, les effets secondaires associés au processus de dégradation sont réduits ou ralentis ou même évités de manière très simple. Ce système de régénération confère à l'huile moteur initiale une performance meilleure et constante, ce qui réduit considérablement l'usure des composants et le coût du cycle de vie de l'équipement. L'invention porte également sur un système plus écologique puisqu'il produit moins de résidus sous forme d'huile usée du fait que la période d'utilisation de l'huile moteur est prolongée.

Claims

Claims:
--------------------
1. A four-stroke trunk piston diesel engine comprising a system for reducing
fuel
consumption, the system comprising:
.cndot. a replenishment system (102) connected to receive oil from the engine
and <IMG>
replenishment oil (120), where the oil replenishment system (102) is
configured for
mixing the engine oil and the replenishment oil (120), the resulting a mixed
oil (103)
being introduced into the engine (100),
characterized in that the replenishment system comprises a mixing unit (114)
receiving the
replenishment oil (120) and the engine oil and mixing them according to a
predetermined
rate resulting in the mixed oil (103).
2. A four-stroke trunk piston diesel engine according to claim 1, wherein the
oil
replenishment system (102) is configured for mixing the engine oil and the
replenishment
oil (120) on a continuous, near-continuous or intermittent basis.
3. A four-stroke trunk piston diesel engine according to claims 1 - 2, wherein
the oil
replenishment system (102) is configured for introducing the mixed oil (103)
to the engine
(100) on a continuous, near-continuous or intermittent basis.
4. A four-stroke trunk piston diesel engine, according to claims 1 - 3,
wherein a rate for
mixing the engine oil and the replenishment oil (120) is dependent on at least
one
measured actual condition of the oil, where the rate of mixing is
automatically adjusted in
response to the at least one actual condition of the oil.
5. A four-stroke trunk piston diesel engine according to claims 1 - 4, wherein
the
replenishment oil (120) comprises one or more additives and/or additive
packages
comprising one or more selected from the group of a Calcium detergent, an
alkali metal
detergent, an alkali-earth metal detergent, an anti-wear additive, a
dispersant, a friction
modifier, and anti-oxidants.
6. A four-stroke trunk piston diesel engine according to claims 1- 5, wherein
said engine
(100) is used in marine or stationary applications.

7. A four-stroke trunk piston diesel engine, according to claims 1 - 6,
wherein said engine
(1C0) is used offshore, on-site or in a land based plant.
8. A four-stroke trunk piston diesel engine according to claims 1 - 7, wherein
the ~~<IMG>
replenishment oil (120) is selected from the group of:
- a heavy fuel oil (HFO),
- bunker oil, and
- residual fuel oil.
9. A method for reducing fuel consumption in a four-stroke trunk piston diesel
engine
(100), the method comprising:
.cndot. receiving engine oil from an engine in an oil replacement system
(102),
.cndot. receiving replenishment oil (120) in the oil replenishment system
(102), and
.cndot. mixing the engine oil and the replenishment oil (120),
.cndot. introducing the mixed oil (103) into the engine (100),
characterised in that
.cndot. the oil replenishment system comprises a mixing unit (114) and mixes
the
replenishment oil (120) and the engine oil according to a predetermined rate
resulting in the mixed oil (103).
10. A method according to claim 9, wherein the oil replenishment system (102)
mixes the
engine oil and the replenishment oil (120) on a continuous, near-continuous or
intermittent
basis.
11. A method according to claims 9 - 10, wherein the oil replenishment system
(102)
introduces the mixed oil (103) to the engine (100) on a continuous, near-
continuous or
intermittent basis.
12. A method according to claims 9 - 11, wherein a rate for mixing the engine
oil and the
replenishment oil (120) is dependent on at least one measured actual condition
of the oil,
where the rate of mixing is automatically adjusted in response to the at least
one actual
condition of the oil.

13. A method according to claims 9 - 12, wherein the replenishment oil (120)
comprises
one or more additives and/or additive packages comprising one or more selected
from the <IMG>
group of a Calcium detergent, an alkali metal detergent, an alkali-earth metal
detergent, an
anti-wear additive, a dispersant, a friction modifier, and anti-oxidants.
14. A method according to claims 9 - 13, wherein said engine (100) is used in
marine or
stationary applications.
15. A method according to claims 9 - 14, wherein said engine (100) is used
offshore, on-
site or in a land based plant.
16. A method according to claims 9 - 15, wherein the replenishment oil (120)
is selected
from the group of:
- a heavy fuel oil (HFO),
- bunker oil, and
- residual fuel oil.

Description

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Improved fuel efficiency for trunk piston four-stroke diesel engines.
FIELD OF THE INVENTION
The invention relates to a system for reducing fuel consumption in a four-
stroke trunk piston diesel engine. Further, the invention relates to a method
of reducing fuel consumption in a four-stroke trunk piston diesel engine.
BACKGROUND OF THE INVENTION
Diesel engines used onboard certain types of vessels and/or used in certain
lo stationary applications are typically of the well known two-stroke type or
of
the well known four-stroke type.
Two-stroke cross-head engines used in marine and/or stationary applications
are equipped with two separate lubricating oil systems. One lubricating
system comprises so-called system oil/system lubricant that normally is used
for lubrication and cooling of the engine's bearings and e.g. oil-cooled
pistons
as well as for activation and/or control of various valves or the like. The
other
lubricating system comprises an all-loss lubricant (cylinder oil/cylinder
lubricant) that normally is used for lubrication of the engine's cylinders,
piston
rings and piston skirt.
Four-stroke trunk piston diesel engines, however, typically use only a single
oil type for lubrication and cooling. Such engines are typically used as
secondary/auxiliary or propulsion engines on ships, or in stationary power
generation or liquid/gas transmission applications. Such oils typically have a
SAE viscosity of about 30 or 40.
Trunk piston engine oils are constantly affected by exposure to the
combustion process whereby the useful properties of the trunk piston engine
oil is degraded over time as the oil become more and more spent until finally
the oil will have to be either replenished or completely changed. This
degradation process cannot be reversed or halted by separators or the like.
Contaminations caused by engine and part wear, particle pollution (e.g. from
combustion by-products), oxidation, hydrolysis, etc. further degrade the
quality of the oil over time in addition to the oil degrading simply from
being
CONFIRMATION COPY

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used, which speeds up the degradation process. The degradation process in
effect increases the viscosity of the engine oil. A diesel engine's frictional
loss
is mainly of a viscose character. An increase in the viscosity of the engine
oil
will therefore result in diminished operating efficiency, increased fuel
consumption, decreased engine efficiency, increased component wear and
increased emissions.
The performance level of the oil is typically measured periodically and may
not go beyond certain limits if the oiled component's condition should not be
jeopardized. When the engine oil is approaching its condemning limit it will
have to be replenished or changed. Changing the oil is usually done by de-
bunkered the oil, which is a costly process, or storing the oil as waste for
later
burning resulting in emissions.
To prolong the usable time of oils used in such engines, suited additives
and/or additive packages are added to the base oil in order to obtain a fully
formulated oil. Such blending is typically done at dedicated land based blend
plants and the fully formulated oil has to the delivered to a ship or an off-
shore plant for use in the engines. The addition of additives or additive
packages increases the cost of the engine oil significantly.
Patent application WO 02/087726 Al discloses an auxiliary filtration system
and filtering method where the auxiliary filtration system consists of an
auxiliary filtration device, an integral oil transfer pump controlled by an
electric motor being controlled by an control unit, an electronic pressure
sensor, and fluid conductors.
Engine oil is pumped from an oil pan of the engine through an auxiliary filter
before it is returned to the oil pan of the engine e.g. through an optional
cooler. An electrostatic agglomeration system may be used to enhance the
ability of a filtering media.
A11IlCAIf1Cl'1 CIJCCT

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The system may also include an additive replenishment system supplying
additives to the filtering media to enhance the quality of the oil.
Alternative
methods of additive replenishment involves applying a special chemical
coating to the filtering media or mounting a replaceable and recyclable
additive releasing cartridge onto a return line.
OBJECT AND SUMMARY OF THE INVENTION
It is an object of the present invention to provide a system for and a
corresponding method of reducing fuel consumption in a trunk piston diesel
engine that solves the above-mentioned (and other) shortcomings. A further
object is to provide this in a cost-effective and simplified way that requires
little modifications of existing systems.
These objects, among others, are achieved by a system for reducing fuel
consumption in a four-stroke trunk piston diesel engine, the system
comprising: a replenishment system connected to receive engine oil from a
four-stroke trunk piston diesel engine and to receive replenishment oil, where
the replenishment system is configured for mixing the engine oil and the
replenishment oil resulting in a mixed oil that is introduced into the engine.
nnnFr\inPn cuPPT

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Since the degradation process of the engine oil effectively is slowed by
replenishing it the above mentioned adverse effects of the degradation
process are reduced or slowed or even avoided in a simple way. Thus, the
replenishment system provides enhanced and consistent performance of the
initial engine oil resulting in greatly reduced component wear and equipment
lifecycle cost. Even further, a more environmentally friendly system is
provided since less waste in the form of spent oil is produced as the
usability
period of time for the engine oil is prolonged.
Further, the normal engine oil need not contain so many additives since it is
replenished whereby cheaper engine oil (since it do not need to contain
additives or additive packages) can be used without compromising the
efficiency of the engine.
The efficiency of the engine is also increased as it in a longer period of
time
uses oil having a lower viscosity.
Thus great economical savings and environmental improvements are
achieved.
Further, the addition of a replenishment system according to the present
invention only requires minor adaptation of existing systems.
In one embodiment, the replenishment system comprises a mixing unit
receiving the replenishment oil and the engine oil and mixing them according
to a predetermined rate resulting in the mixed oil.
In one embodiment, the replenishment system is configured for mixing the
engine oil and the replenishment oil on a continuous, near-continuous or
intermittent basis.
In one embodiment, the replenishment system is configured for introducing
the mixed oil to the engine on a continuous, near-continuous or intermittent
basis.

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In one embodiment, a rate for mixing the engine oil and the replenishment oil
is dependent on at least one measured actual condition of the oil, where the
rate of mixing is automatically adjusted in response to the at least one
actual
condition of the oil.
In one embodiment, the replenishment oil comprises one or more additives
and/or additive packages comprising one or more selected from the group of
a Calcium detergent, an alkali metal detergent, an alkali-earth metal
detergent, an anti-wear additive, a dispersant, a friction modifier, and anti-
1 o oxidants.
In one embodiment, the engine is used in marine or stationary applications.
In one embodiment, the engine is used offshore, on-site or in a land based
plant.
In one embodiment, the replenishment oil is selected from the group of:
- a heavy fuel oil,
- bunker oil, and
- residuat fuel oil.
The present invention also relates to a method reducing fuel consumption in
a four-stroke trunk piston diesel engine, which corresponds to the system of
the present invention.
More specifically, the invention relates to a method of reducing fuel
consumption in a four-stroke trunk piston diesel engine, the method
comprising the steps:
= receiving engine oil from a four-stroke trunk piston diesel engine and
receiving replenishment oil in a replenishment system, and
= mixing the engine oil and the replenishment oil resulting in a mixed oil
that is introduced into the engine.
Advantageous embodiments of the method according to the present
invention are defined in the sub-claims and described in detail in the

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following. The embodiments of the method correspond to the embodiments
of the system and have the same advantages for the same reasons.
BRIEF DESCRIPTION OF THE DRAWINGS
5 These and other aspects of the invention will be apparent from and
elucidated with reference to the illustrative embodiments shown in the
drawing, in which:
Figure 1 illustrates a schematic block diagram of a prior art four-stroke
trunk
piston engine system;
Figure 2 illustrates a schematic block diagram of a four-stroke trunk piston
engine system according to one embodiment of the present invention; and
Figure 3 illustrates a schematic block diagram of a preferred embodiment of
a replenishment system according to one embodiment of the present
invention.
DESCRIPTION OF PREFERRED EMBODIMENTS
Figure 1 illustrates a schematic block diagram of a prior art four-stroke
trunk
piston engine system. Shown is a typical prior art four-stroke trunk piston
engine (100) connected to its oil system responsible for cycling oil through
the engine during use thereby cooling and lubricating the engine (100) and
other parts of the system.
Oil being tapped from the engine (100) is typicaliy passed through a first
filter
(110) by a pump (not shown) or the like where the filter (110) is responsible
for removing small particles, insolubles, wear debris, etc. from the oil.
After
this, the oil is passed to an engine oil container (101) or the like.
Connected
to the oil container (101) is a separator or filter (111) (forth only denoted
separator) that receives some of the oil from the container (101) and
removes dirt, wear debris from engine components, water caused by
hydrolysis, etc. typically by spinning. The separator (111) may also remove
unwanted chemical compounds like CaSo4, etc. The resulting unwanted
materials are removed from the system as waste or sludge.

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Oil is taken from the oil container (101) and passed through another filter
(112) removing small particles, insolubies, debris, etc. and water and other
materials of different density SG e.g. the same or, as preferred, a different
technique (e.g. using a centrifuge mechanism) than the first filter (110)
before
being introduced into the engine (100) for use again.
As mentioned earlier, the oil is degraded by this process causing decreased
engine efficiency, increased fuel consumption, etc. When the oil is
approaching its condemning limit it will have to be replenished or changed
and is discarded as waste and stored for later de-bunkering or burning.
Figure 2 illustrates a schematic block diagram of a four-stroke trunk piston
engine system according to one embodiment of the present invention. The
illustrated system comprises a four-stroke diesel piston engine (100), a first
filter (110), an oil container (101), a separator (111) and another filter
(112)
connected and corresponding to the ones shown and described in
connection with i=igure 1.
Further shown is a replenishment system (102) according to an embodiment
of the present invention. The replenishment system (102) is connected to
receive some of the engine oil after leaving the engine (100) e.g. via a three-
way valve (113) or some other flow and/or rate controlling means.
Preferably, the replenishment system (102) receives engine oil after it has
proceeded through the separator (111) so it is cleaner than if it was tapped
directly from the oil container (101). Alternatively, the replenishment system
(102) could receive engine oil directly from the oil container (101) whereby
the three-way valve (113) is not needed or from another place in the engine
system.
The replenishment system (102) mixes replenishment oil (120) (e.g. heavy
fuel oil (HFO), residual fuel oil, bunker oil or the like) received from an
nnncnmcn cucc~-

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adequate source (like a container, tank or the like) with the received engine
oil thereby creating a mix of oil (103) that effectively is less spent as it
is
mixed with fresh or fresher oil. The mixed oil (103) is then introduced into
the
engine in
Annc~incr~ cuccr

CA 02630171 2008-05-16
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addition to the engine oil being introduced normally as described in
connection with Figure 1 from the oil container (101).
The mixed oil (103) may be supplied to the engine (100) on a continuous,
near-continuous or intermittent basis.
In one embodiment, the replenishment oil (120) (HFO, residual fuel oil,
bunker oil, etc.) also comprises one or more additives and/or additive
packages. The additives may e.g. comprise a Calcium detergent, alkali
metal(s) detergent(s), alkali-earth metal detergent(s), anti-wear additives,
dispersants, friction modifiers, anti-oxidants, etc. improving the
engine/system condition and/or efficiency in some way or another.
The replenishment system (102) may be configured for mixing the engine oil
and the replenishment oil (120) on a continuous, near-continuous or
intermittent basis.
Since the degradation process of the engine oil effectively is slowed by
replenishing it the above mentioned adverse effects of the degradation
process are reduced or slowed or even avoided. Thus, the replenishment
system provides enhanced and consistent performance of the initial engine
oil resulting in greatly reduced component wear and equipment lifecycle cost.
Even further, a more environmentally friendly system is provided since less
waste in the form of spent oil is produced as the usability period of time for
the engine oil is proionged:
Further, the normal engine oil need not contain so many additives since it is
replenished whereby cheaper engine oil (since it do not need to contain
additives or additive packages) can be used without compromising the
efficiency of the engine.
The efficiency of the engine is also increased as it in a longer period of
time
uses oil having a lower viscosity.
nnnC1k1nGn euCC'r

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Further, the addition of a replenishment system according to the present
invention only requires minor adaptation of existing systems.
L1nAr:nIP1C:n cL1cCT

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8
The engine (100) according to the present invention can e.g. be used in
marine or stationary applications, both on-shore and off-shore.
Figure 3 illustrates a schematic block diagram of a preferred embodiment of
a replenishment system according to one embodiment of the present
invention. Shown is an engine system corresponding to the one in Figure 2
with the addition of a more detailed embodiment of the replenishment system
(102). In this embodiment, the replenishment system (102) comprises a
io mixing or blending unit (114) (forth only referred to as mixing unit) or
the like
that receives the engine oil via the three way valve (113) from the separator
(111) (or alternatively directly from the oil container (101) and fresh (or at
least less spent oil than the engine oil) heavy fuel oil (HFO), bunker oil,
residual fuel oil, etc. The mixing unit (114) mixes the HFO and the spent
engine oil resulting in the less spent mixed oil (113) that is introduced into
the
engine (100).
The mixing unit (114) can be any standard mixing unit capable of mixing oils
at the required rates
In a preferred embodiment, the rate of mixing is dependent on at least one
measured actual condition of the oil. The measured condition could e.g. be
the pollution level or condemning level of the engine oil. In a preferred
embodiment, the rate of mixing is automatically adjusted in response to at
least one actual condition of the oil that preferably also is measured
automatically and provided to the mixing unit (114).
A holding tank (104) or the like may be inserted between the mixing (114)
and the rest of the engine system (101/111). This holding tank (104) may act
as a reservoir of engine oil coming from the separator (111). This may be
useful if the rate of introducing the mixed oil (113) into the engine is not
the
same as the rate of engine oil passing through the separator (111). Further,
since additional oil is added to the system thereby increasing the total
volume
of oil it may be necessary to have extra storage capacity if the oil container
(101) is not of an adequate size.

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An additional tank (105) may also be inserted after the mixing unit (114) for
holding the mixed oil (113) before it is introduced into the engine (100). The
additional tank (105) may e.g. be a 'day' or holding tank that is emptied into
the engine whenever operations requires it, which simplifies the process of
introducing the mixed oil (103) into the engine. Other rates of introducing
the
mixed oil (113) into the engine may be just as applicable.
In this way, the typical degradation process of the engine oil is slowed by
replenishing it the adverse effects associated with the degradation process
are reduced or slowed or even avoided in a very simple way. Thus, the
replenishment system provides enhanced and consistent performance of the
initial engine oil resulting in greatly reduced component wear and equipment
lifecycle cost. Even further, a more environmentally friendly system is
provided since less waste in the form of spent oil is produced as the
usability
period of time for the engine oil is prolonged. Additionally, great economical
savings and environmental improvements are achieved.
In the claims, any reference signs placed between parentheses shall not be
constructed as limiting the claim. The word "comprising" does not exclude the
presence of elements or steps other than those listed in a claim. The word
"a" or "an" preceding an element does not exclude the presence of a plurality
of such elements.

Representative Drawing