Note: Descriptions are shown in the official language in which they were submitted.
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STEERING SYSTEM, AZIMUTHING PROPULSION SYSTEM, AND METHOD FOR
ABSORBING HEAT
FIELD
[0001] The present invention relates to a steering system of an
azimuthing
propulsion system. Further, the present invention relates to an azimuthing
propulsion
system. In particular, aspects of the invention relate to a steering system of
an azimuthing
propulsion system comprising a shock absorption system. Additionally, the
invention
relates to a method for absorbing heat generated during an over torque
situation of a
steering system of an azimuthing propulsion system. Furthermore, the present
invention
relates to a method for operating a steering system of an azimuthing
propulsion system.
Yet further, the present invention relates to a computer readable memory.
BAC KGRO UN D
[0002] Document WO 2000/15495 Al describes common propeller
propulsion
systems of vessels such as passenger ships, ferries, cargo vessels, lighters,
oil tankers, ice-
breakers, off-shore vessels, etc. and propeller units in which the equipment
creating the
propulsion power for the propeller shaft and any gearing are positioned
outside the hull of
the vessel within a special chamber, pod, or propulsion unit supported for
rotating in
relation to the hull. The propeller unit can be also used for steering the
vessel instead of
separate rudder gear. Generally, these units are referred to as azimuthing
propulsion
systems or rudder propeller devices, and, e.g., the applicant in the present
application
provides azimuthing units of this kind under the trademark "AZIPOD".
Presently,
azimuthing propulsion systems with a power of more than 20 MW are being
designed.
[0003] An azimuthing propulsion system includes one or several
propulsion
propellers mounted on a shaft journalled in the propulsion unit, which is
substantially
turnable around a vertical axis. The propulsion unit is attached to the lower
end of a shaft
structure which is turnably journalled in the hull of the ship and is normally
a straight
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tubular member. By turning the so called turning shaft it is possible to
direct the propulsion
unit and thus also the propeller flow in any desired direction.
[0004] The azimuthing propulsion system's steering arrangement has
generally been
implemented so that a geared tiller ring or the like tiller rim has been
attached to the
tubular shaft which forms the system's swivelling axis, which tiller is
rotated with the aid
of hydraulic or electric motors adapted to cooperate with it.
[0005] In a case that a hydraulic turning system has been employed,
the operating
machinery which creates the hydraulic pressure required in the motors
comprises of one or
more hydraulic pumps and of one or more electric motors. In order to enhance
the service
reliability of the steering gear and for meeting the redundancy level
required, the hydraulic
motors can be arranged in two or more separate hydraulic circuits, each of
which can be
separated from the system and put to idling in a case of malfunction.
[0006] In case of electric steering, the corresponding redundancy
level and idling
functions are gained by either direct connection of electric motors to the
tiller rim, or
preferably via a reduction gear.
[0007] Normally, in operation the torque required for the turning of
the propulsion
unit is dependent on the distance of the propeller plane from the so called
turning axis or
swivelling axis of the propulsion unit. Typically, the propeller is located at
the end of the
propulsion unit, and hence, is relatively far from the propulsion unit's
turning axis.
Consequently, a relatively high torque is required for turning the propulsion
unit. The
steerability of a vessel equipped with an azimuthing propulsion system is
excellent, but the
torque required for turning the propulsion unit can be high and increases as a
function of
the propulsion power. The high torque causes problems in particular in slow
moving ships
with high propeller thrust such as tugs and ice breakers. The torque required
for turning the
propulsion unit can reach high values and thus requires a very strong steering
machinery.
Further, over torque situations may, for example, occur due to collisions of
at least a part
of the system with blocks of ice or other objects when the propulsion unit is
forced to turn
along the colliding object in order to avoid damage.
[0008] A hydraulic turning system has been employed, because
hydraulics readily
allow the relatively high torque required for turning an azimuthing propulsion
unit to be
obtained at a relatively low speed of rotation. At the same time, the turning
and steering of
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the vessel by means of the hydraulics can be readily and relatively precisely
controlled
with the aid of the traditional pumps and valve gears and corresponding
hydraulic
components. Further, the shock-absorption- and torque limitation features that
are
protecting the mechanical parts of the power transmission of the steering
system have most
suitably been implemented with hydraulics due to an excellent response time
and accuracy
of the hydraulic pressure relief valves. Hence, the hydraulic power
transmission system has
been considered as the most suitable solution for steering systems that are
frequently
exposed for high external loads that are causing over torque situations.
[0009] The propulsion unit has to be able to turn along with a
colliding object so that
no damage is caused to the steering system. The amount of absorbed heat
corresponds to
the loss energy that is created at the pressure relief valves when the
propulsion unit is
forced to turn by a colliding object. Traditionally, the azimuthing propulsion
systems with
hydraulic steering have four very large hydraulic motors directly connected to
the steering
gear including pinions. The pressure relief valves are preferably integrated
to the same
package with the motors, to gain a standard solution with highly predictable
dynamic
properties. The large motors are containing a sufficient oil volume to absorb
the heat
generated in an over torque situation. An over torque situation may, for
example, occur in
arctic environments when the propulsion system is frequently exposed to
collisions with
blocks of ice during operation.
[0010] Over-dimensioning of parts of the steering system should be avoided.
However, use of smaller hydraulic motors operating at an increased rotation
speed
compared to a system comprising the large hydraulic motors can create a
heating problem
during an over torque movement due to the small motor volume, the high
rotation speed
and small volumes in the working lines between the pressure relief valves and
the motor
ports.
[0011] In view of the foregoing, it would be beneficial to provide an
azimuthing
propulsion system or a steering system which comprises a shock absorption
system that
can absorb the heat generated during an over torque situation of a steering
system of the
propulsion system in order to utilize small motors without running into
heating problems.
4
[0012]
According to a first aspect of the present invention, there is provided a
steering
system of an azimuthing propulsion system, the steering system comprising at
least one
hydraulic motor configured to operate an azimuthing system of a propulsion
unit the
propulsion unit being arranged outside a vessel, a fluid cycle from the at
least one
hydraulic motor via a separate hydraulic overload protection unit and back to
the motor,
the overload protection unit comprises a pressure relief unit and a heat
management unit
and wherein the pressure relief unit comprises a pressure relief valve and the
heat
management unit comprises a heat storage, a heat exchanger, or a combination
of both,
and wherein the fluid cycle comprising the overload protection unit is
configured to at
least partially absorb heat generated during turning of the propulsion unit.
[0013]
Various embodiments of the first aspect may comprise at least one feature from
the following bulleted list:
= the steering system is configured to allow the propulsion unit to turn
along with a
colliding object, as a certain predefined load pressure level has been
exceeded
= turning of the propulsion unit is caused by a critical torque caused by
an external force
= the turning of the propulsion unit caused by an external force represents
an over torque
situation of the steering system
= the heat storage comprises a pipeline or a temperature balance tank or
both
= at least a part of the heat management unit is arranged in series with the
pressure relief
unit
= the temperature balance tank is configured to receive a heated outlet
fluid flow of the
pressure relief valve and to provide a filling fluid flow to a hydraulic
volume where a
hydraulic motor inlet is connected to
= a temperature of a temperature balance tank fluid outlet flow is less than
the
temperature of a pressure relief fluid outlet flow
= the temperature balance tank is configured to increase a rotation volume
of the fluid
cycle
= the temperature balance tank is configured to increase a heat capacity of
the fluid cycle
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5
= the steering system comprises hydraulic interconnections between the at
least one
hydraulic motor and the overload protection unit
= the hydraulic interconnection, the at least one hydraulic motor and the
overload
protection unit are configured to circulate a fluid
= the fluid
cycle is configured to decrease a temperature of a fluid in the fluid cycle by
means of a heat sink or cooler
= the temperature balance tank is configured to decrease a temperature of a
fluid in the
fluid cycle by means of a heat sink or cooler
= the fluid cycle comprises a boost pressure fluid system coupled to the
overload
protection unit
= a gear is arranged between the at least one hydraulic motor and a
steering gear of the
propulsion system
= the heat management unit is separated from the pressure relief unit
= the heat management unit and the pressure relief unit are integrated
= the temperature of the temperature balance tank fluid outlet flow is less
than 10 [T],
less than 15 [T], less than 20 [ C], or less than 35 [ C] than the temperature
of the
pressure relief fluid outlet flow
= a volume of the temperature balance tank is adapted to hold at least 5
[1], at least 10
[1], at least 15 [1], or at least 20 [1] of fluid
= the steering system is implemented in or coupled to an azimuthing propulsion
system
100141
According to a second aspect of the present invention, there is provided an
azimuthing propulsion system comprising at least one hydraulic motor
configured to
operate a azimuthing system of a propulsion unit, the propulsion unit being
arranged
outside a vessel, a fluid cycle from the at least one hydraulic motor via a
separate hydraulic
overload protection unit and back to the motor, the overload protection unit
comprises a
pressure relief unit and a heat management unit, and wherein the pressure
relief unit
comprises a pressure relief valve, and the heat management unit comprises a
heat storage,
a heat exchanger, or a combination of both, and wherein the fluid cycle
comprising the
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overload protection unit is configured to at least partially absorb heat
generated during
turning of the propulsion unit.
100151 Various embodiments of the second aspect may comprise at least
one feature
from the following bulleted list:
= the azimuthing propulsion system is configured to allow the propulsion
unit to turn
along with a colliding object, as a certain predefined load pressure level has
been
exceeded
= turning of the propulsion unit is caused by a critical torque caused by
an external force
= the turning of the propulsion unit caused by an external force represents
an over torque
situation of a steering system
= at least a part of the heat management unit is arranged in series with
the pressure relief
unit
= the heat storage comprises a pipeline or a temperature balance tank or
both
= the temperature balance tank is configured to receive a heated outlet
fluid flow of the
pressure relief valve and to provide a filling fluid flow to a hydraulic
volume where a
hydraulic motor inlet is connected to
= the temperature balance tank is configured to increase a rotation volume
of the fluid
cycle
= the temperature balance tank is configured to increase a heat capacity of
the fluid cycle
= a temperature of a temperature balance tank fluid outlet flow is less than
the
temperature of a pressure relief fluid outlet flow
= the system comprises hydraulic interconnections between the at least one
hydraulic
motor and the overload protection unit
= the hydraulic interconnection, the at least one hydraulic motor and the
overload
protection unit are configured to circulate a fluid
= the fluid cycle comprises a boost pressure fluid system coupled to the
overload
protection unit
= a gear is arranged between the at least one hydraulic motor and a
steering gear of the
propulsion system
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7
[0016] According to a third aspect of the present invention, there is
provided a method
for absorbing heat generated during an over torque situation of a steering
system of an
azimuthing propulsion system, the method comprising allowing a propulsion unit
to turn
along with a colliding object, the propulsion unit being arranged outside a
vessel,
circulating fluid from a hydraulic motor via a separate hydraulic overload
protection unit
and back to the motor, and wherein the overload protection unit comprises a
pressure
relief unit and a heat management unit, and wherein the pressure relief unit
comprises a
pressure relief valve, and the heat management unit comprises a heat storage,
a heat
exchanger, or a combination of both, and absorbing at least a part of the
generated heat
by means of the overload protection unit.
[0017] Various embodiments of the third aspect may comprise at least
one feature
from the following bulleted list:
= the method further comprising receiving a heated outlet fluid flow of the
pressure relief
valve, and providing a filling fluid flow to a hydraulic motor inlet volume
= the method yet further comprising transferring heat away from the fluid
present in the
overload protection unit by means of a heat sink which is coupled to the heat
storage
or integrated in the heat storage
[0018] According to a fourth aspect of the present invention, there is
provided a
method for operating an azimuthing propulsion system, the method comprising
allowing
a propulsion unit to turn, the propulsion unit being arranged outside a
vessel, circulating
fluid from a hydraulic motor via a pressure relief valve to a temperature
balance tank and
back to the motor, and absorbing at least a part of heat generated during an
over torque
situation of a steering system of the propulsion system due to a collision of
at least a part
of the system with ice or any other object by means of the temperature balance
tank.
[0019] According to a fifth aspect of the present invention, there is
provided a
computer readable memory having stored thereon a set of computer implementable
instructions capable of causing a computing device, in connection with an
azimuthing
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8
propulsion system or in connection with a steering system 30 of an azimuthing
propulsion
system, to couple a heat exchanger to a fluid cycle based on a fluid
temperature
measurement in a part of an overload protection unit, or to control a fluid
flow of a coolant
of the heat exchanger coupled to the fluid cycle, based on a fluid temperature
measurement in a part of the overload protection unit, or to directly exchange
fluid present
in the overload protection unit by means of an actively controllable valve
connection from
a fluid volume of a heat storage to a tank line or corresponding lower
pressure line.
100201
According to another aspect of the present invention, there is provided a
steering system of an azimuthing propulsion system, the steering system
comprising:
- at least one hydraulic motor configured to operate an azimuthing system of a
propulsion unit, the propulsion unit configured to being arranged outside a
vessel,
- a fluid cycle from the at least one hydraulic motor via a separate
hydraulic
overload protection unit and back to the motor,
- wherein the overload protection unit comprises a pressure relief unit and
a heat
management unit, and wherein
- the pressure relief unit comprises a pressure relief valve, and
- the heat management unit comprises a heat storage comprising temperature
balance tank, wherein the temperature balance tank is configured to receive a
heated outlet fluid flow of the pressure relief valve and to provide a filling
fluid
flow to a hydraulic motor inlet volume so that the fluid cycle comprising the
overload protection unit is configured to at least partially absorb heat
generated
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8a
during turning of the propulsion unit caused by a critical torque caused by an
external force, wherein the steering system is configured to allow the
propulsion
unit to turn along with a colliding object, and
- wherein the steering system comprises a further tank, a booster line inlet
check
valve connecting the temperature balance tank to the further tank, and a
booster
pump connected to the temperature balance tank via said booster line inlet
check
valve so that the temperature balance tank can be flushed with the fluid by
means
of the booster pump.
According to another aspect of the present invention, there is provided an
azimuthing propulsion system comprising:
¨ at least one hydraulic motor configured to operate an azimuthing system
of a
propulsion unit, the propulsion unit configured to being arranged outside a
vessel,
¨ a fluid cycle from the at least one hydraulic motor via a separate
hydraulic
overload protection unit and back to the motor,
¨ the overload protection unit comprises a pressure relief unit and a heat
management unit, and wherein
¨ the pressure relief unit comprises a pressure relief valve, and
¨ the heat management unit comprises a heat storage comprising a
temperature
balance tank, wherein the temperature balance tank is configured to receive a
heated outlet fluid flow of the pressure relief valve and to provide a filling
fluid
flow to a hydraulic motor inlet volume so that the fluid cycle comprising the
overload protection unit is configured to at least partially absorb heat
generated
during turning of the propulsion unit caused by a critical torque caused by an
external force, wherein the steering system is configured to allow the
propulsion
unit to turn along with a colliding object, and
¨ wherein the steering system comprises a further tank, a booster line
inlet check
valve connecting the temperature balance tank to the further tank, and a
booster
pump connected to the temperature balance tank via said booster line inlet
check
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8b
valve so that the temperature balance tank can be flushed with the fluid by
means
of the booster pump.
According to another aspect of the present invention, there is provided a
method
for absorbing heat generated during an over torque situation of a steering
system of an
azimuthing propulsion system, the method comprising:
¨ allowing a propulsion unit to turn along with a colliding object, the
propulsion unit
being arranged outside a vessel,
¨ circulating fluid from a hydraulic motor via a separate hydraulic
overload
protection unit and back to the motor, and wherein
o the overload protection unit comprises a pressure relief unit and a heat
management unit, and wherein
= the pressure relief unit comprises a pressure relief valve, and
= the heat management unit comprises a heat storage comprising a
temperature balance tank, and
¨ receiving by the temperature balance tank a heated outlet fluid flow of the
pressure
relief valve and providing by the temperature balance tank a filling fluid
flow to a
hydraulic motor inlet volume in order to absorb at least a part of the
generated heat
by means of the overload protection unit, wherein the steering system
comprises
a further tank connected to the temperature balance tank via a booster line
inlet
check valve, and
¨ flushing the temperature balance tank by a booster pump.
[0021]
Considerable advantages are obtained by means of certain embodiments of the
present invention. Certain embodiments of the present invention provide an
azimuthing
propulsion system. Certain other embodiments of the present invention provide
a method
for absorbing heat generated during an over torque situation of a steering
system of an
azimuthing propulsion system. Additionally, certain other embodiments of the
present
invention provide a method for operating an azimuthing propulsion system.
[0022]
According to certain embodiments of the present invention, heat generated
during an over torque situation of a steering system of an azimuthing
propulsion system
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8c
can be absorbed. Therefore, significantly smaller hydraulic motors can be used
in the
system. Certain embodiments of the present invention enable the use of
relatively small
hydraulic motors on arctic vessels or ice breakers, for instance.
[0023] The small hydraulic motors are more compact than the motors
currently used,
thus reducing weight, dimensions and costs of the propulsion system. The
availability and
diversity of smaller motors is further much better than of large ones on the
market. The
propulsion unit can be built by using standard components without making any
further
changes to the system. Additionally, the system can be manufactured in
industrial scale.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] For a more complete understanding of particular embodiments of
the present
invention and their advantages, reference is now made to the following
descriptions, taken
in conjunction with the accompanying drawings. In the drawings:
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[0025] FIGURE 1 illustrates a schematic view of an azimuthing
propulsion system
in accordance with at least some embodiments of the present invention,
[0026] FIGURE 2 illustrates a schematic view of an azimuthing
propulsion system
comprising a heat sink in accordance with at least some embodiments of the
present
invention,
[0027] FIGURE 3 illustrates a schematic view of an azimuthing
propulsion system
comprising a gear in accordance with at least some embodiments of the present
invention,
[0028] FIGURE 4 illustrates a schematic view of an fluid cycle
diagram in
accordance with at least some embodiments of the present invention,
[0029] FIGURE 5 illustrates a schematic view of a fluid cycle diagram of a
steering
system of an azimuthing propulsion system in accordance with at least some
embodiments
of the present invention during an over torque situation of the steering
system,
[0030] FIGURE 6 illustrates a schematic view of a fluid cycle diagram
of a steering
system of an azimuthing propulsion system in accordance with at least some
embodiments
of the present invention during an over torque situation of the steering
system, and
[0031] FIGURE 7 illustrates a schematic view of a fluid cycle diagram
of a steering
system of an azimuthing propulsion system comprising an overload protection
unit in
accordance with at least some embodiments of the present invention.
EMBODIMENTS
[0032] Certain embodiments of the present invention relate to an
azimuthing
propulsion system comprising a shock absorption system. The shock absorption
system is
designed to absorb heat generated during an over torque situation of a
steering system of
the propulsion system. Such an over torque situation may, for example, take
place when at
least a part of the propulsion system is exposed to collisions with blocks of
ice or any other
objects. The system is capable of absorbing such shocks by allowing the
propulsion unit to
turn along with the colliding object in a suitable direction and absorbing the
generated
heat.
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[0033] In FIGURE 1 a schematic view of an azimuthing propulsion
system 1 in
accordance with at least some embodiments of the present invention is
illustrated. The
propulsion system 1 includes equipment for creating the propulsion power for
the propeller
shaft and gearing positioned outside the hull 12 of a vessel within a special
propulsion unit
3 supported for rotating in relation to the hull 12.
[0034] The azimuthing propulsion system 1 comprises a plurality of
hydraulic
motors 2 configured to operate the steering system of the propulsion unit 3
which is
arranged outside the vessel. The term "operate" means that the propulsion unit
3 of the
propulsion system 1 can be turned relative to the hull 12 around a vertical
axis of rotation.
Typically, the propulsion unit 3 can be turned unlimitedly in both directions
relative to the
hull 12. The propulsion system may, for example, include four or six hydraulic
motors
coupled to the steering gear of the propulsion system 1. In FIGURE 1 only one
hydraulic
motor 2 is shown.
[0035] The system 1 further includes a shock absorption system
comprising a fluid
cycle from the hydraulic motor 2 via a pressure relief valve 5 to a
temperature balance tank
6 and back to the motor 2. Typically, oil is used as fluid in the fluid cycle.
The temperature
balance tank 6 is configured to at least partially absorb heat generated
during an over
torque situation of the steering system of the propulsion system 1. The
temperature balance
tank 6 may be also called fluid warren or temperature stabilization reservoir,
for instance.
The hydraulic motor 2, the pressure relief valve 5 and the temperature balance
tank 6 of
each fluid cycle are arranged inside the vessel.
[0036] For example, in case that at least a part of the propulsion
system 1 is exposed
to collisions with blocks of ice or any other object 14 during operation, the
propulsion unit
3 is able to turn along with the colliding object 14 so that no damage is
caused to the
steering system. Therefore, the pressure in the hydraulic motor 2 increases.
At a certain
pressure level the pressure relief valve 5 is opened as the work pressure
exceeds the set
pressure of the pressure relief valve. Such a turning of the propulsion unit 3
caused by an
external force represents an over torque situation of the steering system,
where the fluid of
the hydraulic system is heated. A hydraulic motor fluid outlet flow 13 flows
from the
hydraulic motor 2 to the pressure relief valve 5. Subsequently, the pressure
relief valve
fluid outlet flow 7 flows in the direction of a heat storage such as the
temperature balance
tank 6 and/or a heat exchanger via piping 9. The temperature balance tank 6
represents a
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substitute for a long pipeline and can act as a buffer volume for the hot
pressure relief fluid
outlet flow 7. The temperature balance tank 6 may, for example, comprise a
piping
labyrinth in order to provide a substitute for a long pipeline. Additionally,
in the
temperature balance tank 6 the temperature of the fluid may be reduced, for
instance. In
other words, the temperature balance tank 6 may be configured to decrease a
temperature
of the heated incoming pressure relief valve fluid outlet flow 7. The amount
of absorbed
heat corresponds to the loss energy that is created when the fluid is forced
to flow through
the pressure relief valve by the motor 2 that is acting as a pump as the
propulsion unit is
forced to turn by the colliding object 14. Next, the temperature balance tank
fluid outlet
flow 8 can flow back to the hydraulic motor 2. The temperature of the
temperature balance
tank fluid outlet flow 8 returning to the hydraulic motor 2 is less than the
temperature of
the pressure relief valve fluid outlet flow 7.
[0037] The temperature balance tank 6 increases the rotation volume
of the fluid
cycle. According to certain embodiments, the volume of the temperature balance
tank 6 is
adapted to hold fluid in the range between 5 [1] and 20 [1] , for example at
least 10 [1] or at
least 15 [1] . The temperature of the temperature balance tank fluid outlet
flow 8 is
relatively cool as long as the total capacity of the temperature balance tank
6 has not been
significantly exceeded by the pressure relief valve fluid outlet flow 7.
[0038] It is noted, that instead of including a temperature balance
tank 6 between the
pressure relief valve 5 and the hydraulic motor 2, only a straight or bended
piping may be
arranged between the pressure relief valve 5 and the hydraulic motor 2 in
order to form a
fluid circle. The piping may have a suitable cross-sectional area and/or
length in order to
provide a sufficient fluid volume in the fluid cycle.
[0039] The system 1 is able to avoid a heating problem in the work
line between the
pressure relief valve 5 and the motor port during an over torque situation of
the steering
system. The fluid present in the fluid cycle can circulate multiple times
through the same
loop from the hydraulic motor 2, via the pressure relief valve 5, and via the
temperature
balance tank 6.
[0040] In FIGURE 2 a schematic view of an azimuthing propulsion
system 1
comprising a heat sink 10 in accordance with at least some embodiments of the
present
invention is illustrated. For example, a heat storage may include a heat sink
10 comprising
a piping system for guiding a working fluid through the piping system, i.e. a
gas or liquid
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can flow through the piping system of the heat sink 10 in order to transfer
heat away from
the fluid present in the heat storage, e.g. the temperature balance tank 6.
Typically, a liquid
such as oil, water, or water-glycol mixture is used as a working fluid.
100411 According to other embodiments, the heat sink 10 may comprise
cooling fins
or other objects protruding away from the temperature balance tank 6 in order
to increase
the effective area of heat transfer. Such cooling fins or objects protruding
away from the
temperature balance tank 6 may be arranged instead of or in addition to a heat
sink 10
comprising a piping system for guiding a working fluid through the piping
system. The
cooling fins or objects protruding away from the temperature balance tank 6
may be, for
example, made of copper, aluminium or any other material having a suitable
thermal
conductivity.
[0042] According to another embodiment, a boost pressure fluid can
flow through
the temperature balance tank 6 so that it flushes the temperature balance tank
6 constantly.
Of course, also such an active cooling system may further comprise cooling
fins or objects
protruding away from the temperature balance tank 6.
[0043] The time period allowed in between successive ice collisions
or collisions
with other objects 14 without overheating of the hydraulic system can be very
short due to
cooling the fluid present in the temperature balance tank 6. Therefore, arctic
vessels and
ice breakers including an azimuthing propulsion system 1 for propulsion of the
vessel may
comprise such a system for (actively) cooling the fluid present in the
temperature balance
tank 6, for instance.
[0044] The system 1 is able to avoid a heating problem in the work
line between the
pressure relief valve 5 and the motor port during an over torque situation of
the steering
system. The fluid present in the fluid cycle can circulate multiple times
through the same
loop from the hydraulic motor 2, via the pressure relief valve 5, and via the
temperature
balance tank 6.
[0045] In FIGURE 3 a schematic view of an azimuthing propulsion
system 1
comprising a gear 11 in accordance with at least some embodiments of the
present
invention is illustrated. The hydraulic motor 2 is coupled to the steering
gear of the
propulsion system via a gear 11, for example a planetary gear. The propulsion
system 1
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further additionally includes a heat storage, e.g. a temperature balance tank
comprising a
heat sink 10.
[0046] By means of placing the gear 11 between the hydraulic motor 2
and the
pinions of the steering gear of the system 1, torque capacity demands can be
met while
simultaneously using a smaller hydraulic motor. The system 1 is also able to
avoid a
heating problem in the work line between the pressure relief valve 5 and the
motor port
during an over torque situation of the steering system. The fluid present in
the fluid cycle
can circulate multiple times through the same loop from the hydraulic motor 2,
via the
pressure relief valve 5, and via the temperature balance tank 6.
[0047] In FIGURE 4 a schematic view of a fluid cycle diagram in accordance
with at
least some embodiments of the present invention is illustrated. A fluid cycle
4 from the
hydraulic motor to the pressure relief valve to the heat storage and back to
the hydraulic
motor is shown. The heat storage may be a temperature balance tank 6, for
instance.
[0048] In FIGURE 5 a schematic view of a fluid cycle diagram of a
steering system
30 of an azimuthing propulsion system 1 in accordance with at least some
embodiments of
the present invention during an over torque situation of the steering system
30 is
illustrated. The steering system 30 includes a pump module 16 and a motor
module 15.
[0049] The pump module 16 comprises an electric motor 17 which
rotates a
hydraulic pump 18. The pump module 16 may further comprise a booster pump 19,
filling
.. functions 20, and flushing functions 21.
[0050] The motor module 15 comprises a hydraulic motor 2, which is
coupled to
pinions 29 via a gear 11. The motor module 15 further comprises a fluid cycle
4 from the
hydraulic motor 2 via the second pressure relief valve 23 to a heat storage,
for example a
temperature balance tank 6, via the first filling check valve 24 and back to
the motor 2. The
motor module 15 further comprises a first pressure relief valve 22 and a
second filling
check valve 25. The first pressure relief valve 22 and the second filling
check valve 25 are
not a part of the fluid cycle 4 during over torque situation with counter-
clockwise
movement of the pinion 29 as shown in FIGURE 5. Additionally, motor module 15
comprises a valve connection 26 which may be a shut-off valve or proportional
valve, for
instance.
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[0051] The booster pump 19 may be connected to the temperature
balance tank 6 via
a booster line inlet check valve 27. The temperature balance tank 6 can be
constantly
flushed with the fluid by means of the booster pump 19.
[0052] In FIGURE 6 a schematic view of a fluid cycle diagram of a
steering system
30 of an azimuthing propulsion system 1 in accordance with at least some
embodiments of
the present invention during an over torque situation of the steering system
30 is
illustrated. The steering system includes a pump module 16 and a motor module
15.
[0053] The pump module 16 comprises an electric motor 17 and a
hydraulic pump
18, and it may also comprise a booster pump 19, filling functions 20, and
flushing
functions 21.
[0054] The motor module 15 comprises a hydraulic motor 2, which is
coupled to
pinions 29 via a gear 11. The motor module 15 further comprises a fluid cycle
4 from the
hydraulic motor 2 via the first pressure relief valve 22 to a heat storage,
for example a
temperature balance tank 6, via the second filling check valve 25 and back to
the motor 2.
The motor module 15 further comprises a second pressure relief valve 23 and a
first filling
check valve 24. The second pressure relief valve 23 and the first filling
check valve 24 are
not a part of the fluid cycle 4 during clockwise movement of the pinion 29 as
shown in
FIGURE 6.
[0055] The booster pump 19 may be connected to the temperature
balance tank 6 via
a booster line inlet check valve 27. The temperature balance tank 6 can be
constantly
flushed with the fluid by means of the booster pump 19.
[0056] The steering system 30 further comprises a computing device
31. There is
provided a computer readable memory having stored thereon a set of computer
implementable instructions capable of causing a computing device 31, in
connection with
an azimuthing propulsion system 1 or in connection with a steering system 30
of an
azimuthing propulsion system 1, to couple a heat exchanger to a fluid cycle 4
based on a
fluid temperature measurement in a part of an overload protection unit, or to
control a fluid
flow of the coolant of the heat exchanger, coupled to the fluid cycle, based
on a fluid
temperature measurement in a part of the overload protection unit, or to
directly exchange
.. fluid present in the overload protection unit by means of an actively
controllable valve
connection 26 from a fluid volume of the heat storage to a tank line or
corresponding lower
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pressure line. The valve connection 26 may be a shut-off valve or proportional
valve, for
instance.
[0057] In FIGURE 7 a schematic view of a fluid cycle diagram of a
steering system
30 of an azimuthing propulsion system 1 comprising an overload protection unit
32 in
.. accordance with at least some embodiments of the present invention. The
steering system
30 comprises at least one hydraulic motor 2 configured to operate an
azimuthing system of
a propulsion unit 3 which is arranged outside a vessel. The steering system 30
further
includes a fluid cycle 4 from the at least one hydraulic motor 2 via a
separate hydraulic
overload protection unit 32 and back to the motor 2. The overload protection
unit (32) is a
.. part of the fluid cycle (4). In other words, the fluid cycle (4) comprises
the overload
protection unit (32). The overload protection unit 32 comprises a pressure
relief unit 34
and a heat management unit 33. The pressure relief unit 34 comprises a
pressure relief
valve 5, and the heat management unit 33 comprises a heat storage, a heat
exchanger, or a
combination of both. The fluid cycle 4 is configured to at least partially
absorb heat
generated during turning of the propulsion unit 3.
[0058] The steering system 30 is configured to allow the propulsion
unit 3 to turn
along with a colliding object. The turning of the propulsion unit 3 is caused
by a critical
external force. The turning of the propulsion unit 3 caused by the external
force represents
an over torque situation of the steering system 30. At least a part of the
heat management
.. unit is arranged in series with the pressure relief unit. The heat storage
may comprise a
pipeline or a temperature balance tank 6 or both, for instance. The
temperature balance
tank 6 is configured to receive a heated outlet fluid flow of the pressure
relief valve 5 and
to provide a filling fluid flow to a hydraulic volume where a hydraulic motor
inlet is
connected to. A temperature of a temperature balance tank fluid outlet flow 8
is less than
the temperature of a pressure relief fluid outlet flow 7. The steering system
30 comprises
hydraulic interconnections between the at least one hydraulic motor 2 and the
overload
protection unit 32. The hydraulic interconnection, the at least one hydraulic
motor 2 and
the overload protection unit 32 are configured to circulate a fluid.
[0059] It is to be understood that the embodiments of the invention
disclosed are
.. not limited to the particular structures, process steps, or materials
disclosed herein, but are
extended to equivalents thereof as would be recognized by those ordinarily
skilled in the
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relevant arts. It should also be understood that teuninology employed herein
is used for
the purpose of describing particular embodiments only and is not intended to
be limiting.
[0060] Reference throughout this specification to one embodiment or
an
embodiment means that a particular feature, structure, or characteristic
described in
connection with the embodiment is included in at least one embodiment of the
present
invention. Thus, appearances of the phrases "in one embodiment" or "in an
embodiment"
in various places throughout this specification are not necessarily all
referring to the same
embodiment. Where reference is made to a numerical value using a term such as,
for
example, about or substantially, the exact numerical value is also disclosed.
[0061] As used herein, a plurality of items, structural elements,
compositional
elements, and/or materials may be presented in a common list for convenience.
However,
these lists should be construed as though each member of the list is
individually identified
as a separate and unique member. Thus, no individual member of such list
should be
construed as a de facto equivalent of any other member of the same list solely
based on
their presentation in a common group without indications to the contrary. In
addition,
various embodiments and example of the present invention may be referred to
herein along
with alternatives for the various components thereof. It is understood that
such
embodiments, examples, and alternatives are not to be construed as de facto
equivalents of
one another, but are to be considered as separate and autonomous
representations of the
present invention.
[0062] Furthermore, the described features, structures, or
characteristics may be
combined in any suitable manner in one or more embodiments. In this
description,
numerous specific details are provided, such as examples of lengths, widths,
shapes, etc.,
to provide a thorough understanding of embodiments of the invention. One
skilled in the
relevant art will recognize, however, that the invention can be practiced
without one or
more of the specific details, or with other methods, components, materials,
etc. In other
instances, well-known structures, materials, or operations are not shown or
described in
detail to avoid obscuring aspects of the invention.
[0063] While the forgoing examples are illustrative of the principles
of the present
invention in one or more particular applications, it will be apparent to those
of ordinary
skill in the art that numerous modifications in form, usage and details of
implementation
can be made without the exercise of inventive faculty, and without departing
from the
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principles and concepts of the invention. Accordingly, it is not intended that
the invention
be limited, except as by the claims set forth below.
[0064] The verbs "to comprise" and -to include" are used in this
document as open
limitations that neither exclude nor require the existence of also un-recited
features. The
features recited in depending claims are mutually freely combinable unless
otherwise
explicitly stated. Furthermore, it is to be understood that the use of "a" or
"an", that is, a
singular form, throughout this document does not exclude a plurality.
INDUSTRIAL APPLICABILITY
[0065] At least some embodiments of the present invention find industrial
application in propulsion of arctic vessels and ice breakers.
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REFERENCE SIGNS LIST
1 propulsion system
2 hydraulic motor
3 propulsion unit
4 fluid cycle
5 pressure relief valve
6 temperature balance tank
7 pressure relief valve fluid outlet flow
8 temperature balance tank fluid outlet flow
9 piping
10 heat sink
11 gear
12 hull
13 hydraulic motor fluid outlet flow
14 object
15 motor module
16 pump module
17 electric motor
18 hydraulic pump
19 booster pump
20 filling functions
21 flushing functions
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22 first pressure relief valve
23 second pressure relief valve
24 first filling check valve
25 second filling check valve
26 valve connection
27 booster line inlet check valve
28 flushing flow metering orifice
29 pinion
30 steering system
31 computing device
32 overload protection unit
33 heat management unit
34 pressure relief unit
CITATION LIST
Patent Literature
WO 2000/15495 Al
Non Patent Literature
