Steering system, azimuthing propulsion system, and method for absorbing heat

Abstract

According to an example 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.

Claims

1. 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, and 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, 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.

2. The steering system according to claim 1, wherein the steering system is configured to allow the propulsion unit to turn along with a colliding object.

3. The steering system according to claim 1, wherein turning of the propulsion unit is caused by a critical torque caused by an external force.

4. The steering system according to claim 1, wherein the turning of the propulsion unit caused by an external force represents an over torque situation of the steering system.

5. The steering system according to claim 1, wherein at least a part of the heat management unit is arranged in series with the pressure relief unit.

6. The steering system according to claim 1, wherein the heat storage comprises a pipeline or a temperature balance tank or both.

7. The steering system according to claim 6, 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.

8. The steering system according to claim 6, wherein the temperature balance tank is configured to increase a rotation volume of the fluid cycle.

9. The steering system according to claim 6, wherein the temperature balance tank is configured to increase a heat capacity of the fluid cycle.

10. The steering system according to claim 1, wherein a temperature of a temperature balance tank fluid outlet flow is less than the temperature of a pressure relief fluid outlet flow.

11. The steering system according to claim 1, wherein the steering system further comprises hydraulic interconnections between the at least one hydraulic motor and the overload protection unit.

12. The steering system according to claim 11, wherein the hydraulic interconnection, the at least one hydraulic motor and the overload protection unit are configured to circulate a fluid.

13. The steering system according to claim 1, wherein the fluid cycle comprises a boost pressure fluid system coupled to the overload protection unit.

14. The steering system according to claim 1, wherein a gear is arranged between the at least one hydraulic motor and a steering gear of the propulsion system.

15. The steering system according to claim 1, wherein the heat management unit is separated from the pressure relief unit or the heat management unit and the pressure relief unit are integrated.

16. 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, and 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, 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.

17. The azimuthing propulsion system according to claim 16, wherein the azimuthing propulsion system is configured to allow the propulsion unit to turn along with a colliding object.

18. The azimuthing propulsion system according to claim 16, wherein turning of the propulsion unit is caused by a critical torque caused by an external force.

19. (canceled)

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22. (canceled)

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30. 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.

31. The method according to claim 30, further comprising: receiving a heated outlet fluid flow of the pressure relief valve, and providing a filling fluid flow to a hydraulic volume where a hydraulic motor inlet is connected to.

32. (canceled)

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Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0059] 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:

[0060] FIG. 1 illustrates a schematic view of an azimuthing propulsion system in accordance with at least some embodiments of the present invention,

[0061] FIG. 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,

[0062] FIG. 3 illustrates a schematic view of an azimuthing propulsion system comprising a gear in accordance with at least some embodiments of the present invention,

[0063] FIG. 4 illustrates a schematic view of an fluid cycle diagram in accordance with at least some embodiments of the present invention,

[0064] FIG. 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,

[0065] FIG. 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

[0066] FIG. 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

[0067] 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.

[0068] In FIG. 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.

[0069] 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 FIG. 1 only one hydraulic motor 2 is shown.

[0070] 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.

[0071] 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 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.

[0072] 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 [l] and 20 [l], for example at least 10 [l] or at least 15 [l]. 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.

[0073] 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.

[0074] 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.

[0075] In FIG. 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 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.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] In FIG. 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 further additionally includes a heat storage, e.g. a temperature balance tank comprising a heat sink 10.

[0081] 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.

[0082] In FIG. 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.

[0083] In FIG. 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.

[0084] 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.

[0085] 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 FIG. 5. Additionally, motor module 15 comprises a valve connection 26 which may be a shut-off valve or proportional valve, for instance.

[0086] 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.

[0087] In FIG. 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.

[0088] 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.

[0089] 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 FIG. 6.

[0090] 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.

[0091] 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 pressure line. The valve connection 26 may be a shut-off valve or proportional valve, for instance.

[0092] In FIG. 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.

[0093] 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.

[0094] 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 relevant arts. It should also be understood that terminology employed herein is used for the purpose of describing particular embodiments only and is not intended to be limiting.

[0095] 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.

[0096] 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.

[0097] 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.

[0098] 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 principles and concepts of the invention. Accordingly, it is not intended that the invention be limited, except as by the claims set forth below.

[0099] 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

[0100] At least some embodiments of the present invention find industrial application in propulsion of arctic vessels and ice breakers.

REFERENCE SIGNS LIST

[0101] 1 propulsion system [0102] 2 hydraulic motor [0103] 3 propulsion unit [0104] 4 fluid cycle [0105] 5 pressure relief valve [0106] 6 temperature balance tank [0107] 7 pressure relief valve fluid outlet flow [0108] 8 temperature balance tank fluid outlet flow [0109] 9 piping [0110] 10 heat sink [0111] 11 gear [0112] 12 hull [0113] 13 hydraulic motor fluid outlet flow [0114] 14 object [0115] 15 motor module [0116] 16 pump module [0117] 17 electric motor [0118] 18 hydraulic pump [0119] 19 booster pump [0120] 20 filling functions [0121] 21 flushing functions [0122] 22 first pressure relief valve [0123] 23 second pressure relief valve [0124] 24 first filling check valve [0125] 25 second filling check valve [0126] 26 valve connection [0127] 27 booster line inlet check valve [0128] 28 flushing flow metering orifice [0129] 29 pinion [0130] 30 steering system [0131] 31 computing device [0132] 32 overload protection unit [0133] 33 heat management unit [0134] 34 pressure relief unit

CITATION LIST

[0135] Patent Literature [0136] WO 2000/15495 A1 [0137] Non Patent Literature