Note: Descriptions are shown in the official language in which they were submitted.
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SHIP
The invention concerns a ship comprising at least one electric motor for
driving the ship and a cooling device for cooling the at least one motor by
means of at least one coolant. The invention further concerns a cooling
device for a ship having at least one electric motor.
Hitherto the proportion of ships was implemented predominantly by means of
internal combustion engines. Electric drives were also quite often used in
relation to smaller ships, for example in the leisure area. In recent times
trials are also being undertaken to drive larger ships such as for example for
cargo ships and container ships by means of electric drives. The climate at
sea represents a problem for those drives which frequently have a
complicated and expensive electronic system. In
particular cooling such
electric drives for cargo ships is a problem which hitherto has been only
inadequately resolved.
The object of the present invention is to make a contribution to resolving
that
problem, giving in particular an electric motor-driven ship with improved
cooling.
In a ship of the kind set forth in the opening part of this specification that
object is attained in that the cooling device has a heat exchanger adapted to
cool the at least one coolant by means of sea water.
Accordingly a ship according to the invention has at least two cooling
circuits
which are coupled together. In a first circuit coolant circulates between the
at
least one electric motor and the heat exchanger. In a second circuit sea
water circulates between the heat exchanger and an outside region of the
ship. The two circuits are separated from each other by the heat exchanger
in such a way that coolant and sea water to not mix. As a result the at least
one electric motor does not come into contact with sea water. Thus according
to the invention corrosion of the at least one electric motor is substantially
reduced and as a result the service life is substantially prolonged. The
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maintenance expenditure and complication is also substantially reduced. The
construction and manufacture of such an electric motor is also simplified as
it
does not have to be designed for direct cooling operation by means of sea
water. A further advantage is also that a ship with a drive designed in that
way is improved in terms of energy consumption and reliability. Sea water
represents a natural and almost unlimited cooling resource. The temperature
of the sea water is in that respect substantially constant in a voyage with
the
ship so that such a cooling device does not require permanent adaptive
adjustment. In addition there is no need for complication apparatuses for
generating cold to be installed on board a ship according to the invention
whereby on the one hand operational reliability and on the other hand the
energy consumption of such a ship are improved.
Preferably the heat
exchanger is in the form of a counter-flow heat exchanger. Alternatively the
heat exchanger is the form of a co-flow heat exchanger. According to the
invention it is also possible to use a plurality of heat exchangers so that
the
coolant can be cooled in a multi-stage heat exchange process.
In a first preferred embodiment the coolant is air and/or fresh water.
According to the invention the term fresh water here does not denote sea
water but for example cooling water, cooling fluid and also water-oil
emulsions and the like. Air refers here to space air and not to salty sea air.
Those two coolants are particularly preferred as they are readily available
and
are already used in many cases for electric motors. In that respect, heat
exchange of sea water to fresh water is easy to implement by virtue of good
thermal conduction. Especially adapted heat exchangers are preferably to be
used for heat exchange from sea water to air.
In a further preferred embodiment the coolant is air and a rotor and/or a
stator of the electric motor can be cooled by means of said air. In particular
air is preferred for cooling a rotor of an electric motor. The cooled air can
be
passed for example through a gap between the rotor and the stator, cooling
ribs can be arranged at the stator, or cooling passages through which the cool
air can be passed are taken through the stator. In addition the air can be
passed into an internal hollow space in the rotor and thus cool it.
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In a further preferred embodiment the at least one electric motor is arranged
in a substantially air-tightly closed engine room of the ship and of the air
for
cooling the electric motor is room air. Thus the at least one electric motor
is
not exposed to salty air whereby corrosion at the motor is substantially
avoided. That provides that on the one hand maintenance of such a motor or
a ship according to the invention having such a motor and such a cooling
device is substantially reduced and the operational reliability of the ship is
improved. In accordance with this preferred embodiment, each motor can be
provided with a dedicated room, or all motors are arranged jointly in a
substantially air-tightly closed room. In addition an energy supply for the
motors can also be arranged in that room. The heat exchanger can also be
arranged in an air-tightly closed room or can be in fluid communication with
that room in some other way.
In accordance with a further preferred embodiment that means for conveying
air are arranged at a cooling air inlet and/or a warm air outlet of the
electric
motor. Thus cool air can be guided in specifically targeted fashion to the
electric motor or can be caused to impinge thereagainst. That air can also be
guided in cooling passages, over cooling ribs, in openings or hollow spaces or
the like to the electric motor. In addition warm air can be carried away from
the electric motor in a specifically targeted fashion. That makes it possible
to
achieve specifically targeted cooling of the motor. In addition a specifically
targeted volume flow or a specifically targeted air speed can be sat over the
motor so that it can be cooled in improved targeted fashion. That makes it
possible to achieve efficient of the motor and the service life of a motor is
prolonged. The maintenance complication and expenditure is also further
reduced.
In a further preferred embodiment means for guiding the air is/are arranged
between a cooling air inlet of an electric motor and a cooling air outlet of
the
heat exchanger and/or between a warm air outlet of the electric motor and a
warm air outlet of the heat exchanger. Such means can include for example
hoses, passages, tubes, shafts and so forth. A specifically targeted air feed
and discharge is thus afforded according to the invention and effective
cooling
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of the motor is improved. Additionally or alternatively the means for guiding
the air can have means for conveying air. In an embodiment the means for
guiding the air are arranged between a cooling air inlet of the electric motor
and a cooling air outlet of the heat exchanger. In this embodiment cooling air
is passed specifically to the motor by means of the means for guiding the air,
the motor is cooled by means of the air supplied thereto, the warm air is then
discharged into the room which is preferably air-tightly closed. The heated
room air is then cooled again by means of the exchange effect. In an
alternative the means for guiding the air are arranged between a warm air
outlet of the electric motor and a warm air inlet of the heat exchanger. In
this embodiment the warm air is carried away from the electric motor, and
towards the heat exchanger, by means of which it is cooled. The cooled air is
then discharged into the room which is preferably air-tightly closed. In a
further embodiment the means for guiding the air are arranged both between
a cooling air outlet of the heat exchanger and a cooling air inlet of the
electric
motor, and also between a warm air outlet of the electric motor and a warm
air inlet of the heat exchanger. Accordingly the cooling air circulates in a
substantially closed system. In this embodiment the room does not have to
be air-tightly closed, but rather it is sufficient for the motors to be
protected
from salty air.
In a further preferred embodiment the at least one electric has cooling
passages at a housing and/or at a stator. The cooling passages can pass
through the housing and/or along a stator winding. Specifically targeted
cooling of a motor is possible by means of such cooling passages. The cooling
passages can be designed using various geometries, for example straight,
curved, in a zig-zag shape or also in a different fashion. Ribs can also be
arranged in the passages to achieve still more effective cooling.
In a further embodiment cooling air can be passed through the cooling
passages and/or a gap between the stator and a rotor. That advantageously
develops effective cooling of the electric motor. Means for guiding the air
and/or means for conveying the air for example can be connected to the
cooling passages.
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In a further preferred embodiment the coolant is fresh water which can be
passed through the cooling passages for cooling the electric motor. That
permits still more effective cooling of an electric motor. In this embodiment
5 the fresh water is cooled by means of the heat exchanger, passed through
tubes, hoses or the like to the passages, passed through the passages and
then passed heated again back to the heat exchanger.
In a further preferred embodiment the cooling device has a second heat
exchanger which can be connected to a first heat exchanger and which is
adapted to cool air by means of fresh water, wherein the fresh water can be
cooled by means of the first heat exchanger by means of sea water. Thus
fresh water and air can be cooled with a heat exchanger. It is for example
possible to cool fresh water by means sea water with a large primary heat
exchanger, and to pass that fresh water to various motors or other items of
equipment in the ship such as for example the diesel-generating assemblies.
The electric motors can accordingly each have a respective dedicated second
small heat exchanger, by means of which air is cooled by the cool fresh water.
The fresh water can then be additionally used to cool for example the stator
of
the motor while the cooled air is used to be passed through a gap between
the rotor and the stator and thus cool the rotor. In a further preferred
embodiment the first heat exchanger can be connected to a stator of the
electric motor and is adapted to cool it by means of the fresh water.
In a further preferred embodiment the energy supply has a converter and the
converter can be cooled by means of fresh water. In particular it is
preferable
for those inverters to be cooled by means of the fresh water as they are
preferably arranged in positional proximity with the electric motors. It is
equally preferable for both the converter cooling or the energy supply cooling
and the electric motor cooling to be arranged on the same cooling circuit of
fresh water. It is however also possible to provide different cooling
circuits.
In a further aspect of the invention, in a cooling device of the kind set
forth in
the opening part of this specification, the object is attained in that a
cooling
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device is of a configuration corresponding to one of the above-mentioned
embodiments. Such a cooling device can be used in a large number of ships,
marine vessels or yachts to cool for example electric motors or also other
devices to be cooled. Such a cooling device contributes to making the ship
low-maintenance and operationally reliable and to reduce energy
consumption. All the above-mentioned advantages are achieved when such a
cooling device is used in a ship.
The invention is described hereinafter by means of embodiments by way of
example with reference to the accompanying drawings in which:
Figure 1 shows a partly broken-away perspective view of a ship
according to the invention,
Figure 2 shows a diagrammatic view of a first embodiment of a cooling
device,
Figure 3 shows a diagrammatic view of a second embodiment of a
cooling device,
Figure 4 shows a diagrammatic view of a third embodiment of a cooling
device,
Figure 5 shows a diagrammatic view of a fourth embodiment of a
cooling device.
The ship 102 shown in Figure 1 has on a deck 114 four Magnus rotors 110 as
propulsion devices. Besides those Magnus rotors 110 the ship also optionally
has a bridge 130 as well as a crane 105 and a crane 103 on the deck 114. As
a further propulsion device the ship additionally has a propeller 150 at the
stern of the ship 102. The propeller 150 can be connected by way of a shaft
111 to two electric motors 108, 109. The electric motors 108, 109 are fed
with electric current by way of two converter cabinets 115, 116. Arranged
above the electric motors 108, 109 and the converter cabinets 115, 116 is a
deck 172 which preferably air-tightly closes the engine room in relation to a
cargo hold. Preferably large-volume electric motors, for example synchronous
machines, involving a low rotary speed, are used as the electric motors 108,
109 so that a transmission does not necessarily have to be provided in the
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overall drive train. The motors can also be operated selectively. For light to
pass into the interior of the ship 102 it has windows 118 at the sides.
Figures 2 to 4 show embodiments by way of example of a cooling device
according to the invention for a ship 102 according to the invention, by means
of which the electric motors 108, 109 can be cooled.
As shown in Figure 2 the cooling device 1 in the first embodiment has a heat
exchanger 2 which can be fed on one side 4 with a flow 16 of sea water. The
flow of sea water is only diagrammatically indicated here by the arrows. In
the case of a ship 102 as shown in Figure 1 the sea water flow 16 can be
passed to and away from the heat exchanger 2 by means of tubes. At a
second side 6 the heat exchanger 2 has an air inlet 24 and an air outlet 26.
Air can thus be cooled by means of this heat exchanger 2.
Figure 2 also shows an electric motor 8. The electric motor 8 has a stator 10
which can have a stator housing. The electric motor 8 also has a rotor which
rotates about an axis of rotation 14 in operation and can be coupled to a
drive
unit of a ship such as for example a shaft 111 and propeller 150 (Figure 1).
The electric motor 8 together with its components is arranged in a room 19
which is substantially air-tightly closed by a wall 18. The heat exchanger 2
together with its components is arranged outside a room 19. The stator or
stator housing 10 of the electric motor 8 also has an air inlet 20 and an air
outlet 22. Arranged thereat as a means for conveying the air is a respective
fan 20a, 22a for conveying the air into and out of the motor 8; alternatively
other pumps such as vane pumps or the like could be used for that purpose.
Preferably the air can be passed through cooling passages in the stator or the
stator housing 10 and/or a gap between the rotor 12 and the stator 10. A
tube 30 is arranged between the air outlet 22 and the air inlet 24 of the heat
exchanger 2. Warm air is carried out of the motor 8 and passed to the heat
exchanger 2 by way of the tube 30. The cool air which issues from the air
outlet 26 of the heat exchanger 2 is passed by means of a second tube 32 to
an air inlet 28 of the room 19 in the wall 18. The air passes out of that air
inlet 28 into the room 19 so that it is overall filled with cool air. The cool
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room air is then sucked in by the fan 20a at the air inlet 20 and is passed
into
the cooling passages of a gap between the rotor 12 and the stator 10. By the
room 19 being filled with cool air, the fan 20a in the inlet 20 can always
suck
in as much air as is just needed to cool the motor 8 to a temperature which is
required for optimum performance. The motor 8 is also cooled by way of air
which is not blown or sucked directly into the motor 8, but flows along the
surface thereof. Preferably the room 19 is air-tightly closed by means of the
wall 18 or decks, doors, hatches and the like so that in the case of a ship
102
(Figure 1) no salty air or as little salty air as possible passes into the
room 19.
Alternatively it is also in accordance with the invention for the room 19 not
to
be air-tightly closed, but for an increased pressure to obtain within the room
19 so that salty air cannot flow from the exterior into the interior of the
room
19. It is also possible for a tube to be arranged between the inlet 28 of the
room 19 and the inlet 20 of the motor and/or for no tube 30 to be arranged
between the outlet 22 of the motor 8 and the inlet 24 of the heat exchanger
2.
In the second embodiment of the cooling device 1 shown in Figure 3 the
cooling device 1 has a first heat exchanger 2 and a second heat exchanger 3.
The two heat exchangers 2, 3 are coupled to a motor 8 and serve to cool it by
means of coolant. The first heat exchanger 2 is arranged in a first cooling
circuit which substantially corresponds to the first embodiment shown in
Figure 2 of the cooling device 1. The second circuit in which the second heat
exchanger 3 is arranged uses fresh water such as for example cooling water
or other cooling fluid as coolant. The second heat exchanger 3 is coupled like
the first heat exchanger 2 to a sea water flow 17, wherein that sea water flow
17 once again in the case of a ship 102 as shown in Figure 1 can be passed
for example by way of tubes from an external region of the ship 102 to the
heat exchanger 3. The heat exchanger 3 is connected at a second side 7 to
two cooling water conduits 34, 36 which each have a respective pump 38, 40.
The pumps 38, 40 are adapted to deliver a corresponding cooling water flow.
The cooling water conduits 34, 36 lead from outside the room where the heat
exchanger 3 is also arranged into the interior 19 of the room and are there
connected to a cooling body 42. For that purpose the cooling body 42 has a
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cooling water inlet 44 and a cooling water outlet 46. As shown in Figure 3 the
cooling body 42 is arranged at an outer portion of the motor housing or the
stator 10 of the electric motor 8. That is only a diagrammatic view. It is
also
possible to provide in a housing or in the stator 10, cooling passages through
which cooling water can be passed. In this embodiment it is possible for
example for the rotor 12 to be substantially cooled with the air which can be
passed through the air inlet 20 into the interior of the motor 8, and for the
stator 10 of the motor 8 to be cooled substantially with water which can be
cooled by way of the heat exchanger 3 by means of the sea water flow 17 and
which circulates by means of the cooling water conduits 34, 36 between the
heat exchanger 3 and the cooling body 42.
Figure 4 shows a further alternative of a cooling device 1. In addition to the
cooling device 1 shown in Figure 3 the cooling device 1 of Figure 4 has a
third
cooling circuit. The third cooling circuit is fed like the second cooling
circuit by
means of the heat exchanger 3 which is adapted to cool cooling water by
means of a sea water flow 17. As shown in Figure 4 two further cooling water
conduits 35, 37 branch from the cooling water conduits 34, 36 and pass
cooling water to and away from a converter cabinet 48. The converter
cabinet 48 is connected to the electric motor 8 by way of a power supply cable
50. Arranged in the converter cabinet 48 is a plurality of converters adapted
to provide electric current at a voltage and a frequency which are required by
the electric motor 8. To ensure optimum operation of a converter cabinet 48
it is preferable for it to be cooled. In
the illustrated embodiment the
converter cabinet 48 or the converters contained therein is cooled with
cooling
water cooled by means of the heat exchanger 3 by means of a sea water flow
17. The cooled cooling water is conveyed on a second side 7 of the heat
exchanger 3 by a pump 40, and flows through a cooling water feed conduit 37
to the converter cabinet 48. A plurality of cooling bodies can be arranged
therein, or plates or the like which transport heat away from the converters.
The heated water is then conveyed away from the converter cabinet 48 by
means of the cooling water conduit 35 and the pump 38 and passes to the
heat exchanger 3 again. The two further cooling circuits are of a
configuration corresponding to the circuits in Figure 3.
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A further alternative of the cooling device 1 is shown as an embodiment in
Figure 5. In this embodiment (Figure 5) the cooling device 1 has substantial
features in common with the embodiment of Figure 3. The circuits used for
5 cooling the electric motor 8 in the embodiment of Figure 5 are in
cascade
relationship. The cooling device has a first heat exchanger 2 and a second
heat exchanger 3. The heat exchanger 3 has a first side 5 and a second side
7, wherein a sea water flow 17 can be passed into the first side 5 and cooling
water conduits 34, 36 are connected to the second side. The first heat
10 exchanger 2 also has a first side 4 and a second side 6, with two
cooling
water conduits 52, 54 being connected to the first side 4 and two air passages
30, 32 to the second side 6. The cooling water conduit 52, 54 lead to the
second side 7 of the second heat exchanger 3. The co-operation of the air
passages 30, 32 with the electric motor 8 and the cooling passages 34, 36
with the cooling element 42 are of a configuration corresponding to the
embodiment of Figure 3. In the present embodiment (Figure 5) a sea water
flow 17 is used to cool cooling water which then is used on the one hand to
cool the electric motor 8 by way of a cooling body 42 and on the other hand is
used in the first heat exchanger 2 to cool air which then in turn is used to
cool
the electric motor 8 and in particular the rotor 12. Thus only one sea water
access is necessary for the overall cooling system and in addition corrosion
in
the first heat exchanger 2 can be very substantially avoided.
If more than one motor 8, 108, 109 is arranged in a ship 102 (Figure 1), a
cooling device can be provided for each motor or a common cooling device
can be provided for a plurality of motors. If a cooling device is designed for
a
plurality of motors as in the embodiment of Figure 5 a first heat exchanger 2
can be arranged for example for each electric motor 8, 108, 109, in which
case that plurality of first heat exchangers 2 co-operative with a single
second
heat exchanger 3.
