Sealing unit for a marine propulsion unit

Abstract

Embodiments of the present disclosure relate to a sealing unit for a marine propulsion unit. The propulsion unit comprises a rotatable inner shaft and a rotatable outer shaft, wherein the inner shaft runs at least partially within the outer shaft and wherein the outer shaft runs at least partially within a sealing housing of a marine vessel. The sealing unit comprises: a plurality of chamber systems, wherein each chamber system comprises an inner shaft seal chamber, an outer shaft seal chamber and a passage through the outer shaft fluidly connecting the inner chamber and the outer shaft seal chamber; an inner shaft sealing between the inner shaft and the outer shaft, wherein the inner shaft sealing seals the inner shaft seal chambers of the plurality of chamber systems; and an outer shaft sealing between the outer shaft and the sealing housing, wherein the outer shaft sealing seals the outer shaft seal chambers of the plurality of chamber systems. Further embodiments relate to a method for servicing a sealing unit in a marine propulsion unit.

Description

SEALING UNIT FOR A MARINE PROPULSION UNITTECHNICAL FIELD

[0001] Embodiments of the present disclosure relate to a sealing unit for a marine propulsion unit, particularly for an azimuthing propulsion unit. Further embodiments relate to a method for servicing a sealing unit in a marine propulsion unit, particularly in an azimuthing propulsion unit.BACKGROUND

[0002] To propel marine vessels, marine propulsion units with a high efficiency and maneuverability are desired. Azimuthing propulsion units may generally provide marine propulsion units with a high efficiency and maneuverability. In azimuthing propulsion units, at least one marine propeller attached to a rotatable pod provides thrust. A direction of the thrust may be controlled via a rotation of the rotatable pod. In typical azimuthing propulsion units, at least one electric motor driving the at least one marine propeller is integrated in the pod. In some marine vessels, a shaft-line configuration of propulsion units may be preferred. In particular, the thrust may be provided by a motor arranged within the hull of the marine vessel and a propeller connected to the motor via a shaft-line.

[0003] For an efficient marine propulsion unit, contra rotating propellers may be employed. For driving a contra rotating propeller, a contra rotating electric motor can be suitable. An efficient, durable and maintainable sealing unit to seal an outside of the marine vessel, particularly the pod, from an inside of the marine vessel, particularly the pod, can be required. Embodiments of the present disclosure relate to such sealing units. Typically, embodiments of the present disclosure can fluidly connect an inner shaft sealing and an outer shaft sealing. Particularly, fluid can be transferred between the inner shaft sealing inside the outer shaft and the outer shaft sealing outside the outer shaft.DISCLOSURE OF THE INVENTION

[0004] In the view of the foregoing, the present disclosure is directed to a sealing unit for a marine propulsion unit, particularly an azimuthing propulsion unit, and a method for servicing a sealing unit in a marine propulsion unit, particularly an azimuthing propulsion unit.

[0005] According to an aspect of the present disclosure, a sealing unit for a marine propulsion unit, particularly for an azimuthing propulsion unit, is provided.

[0006] According to another aspect of the present disclosure, a method for servicing of a sealing unit in a marine propulsion unit, particularly in an azimuthing propulsion unit, according to any of the embodiments described herein is provided.

[0007] According to some embodiments, the marine propulsion unit is configured to propel a marine vessel. In some embodiments, the marine propulsion unit comprises an azimuthing propulsion unit. In some embodiments, the marine propulsion unit may comprise a shaft-line marine propulsion unit. In particular, the marine vessel may comprise at least one marine propulsion unit according to embodiments described herein. The marine vessel as described herein comprises seagoing or inland marine vessels. In particular, the marine vessel comprises ships and boats. In some embodiments, the marine vessel comprises merchant ships, in particular for transporting goods. In particular, the marine vessel may comprise a container vessel, a Ro-Ro or car carrier, a tanker or shuttle tanker, a liquid natural gas (LNG) carrier or a floating storage and regasification unit. In some embodiments, the marine vessel comprises ferries, in particular single- and double-ended ferries, cruise ships, water buses, yachts. In some embodiments, the marine vessel comprises offshore energy vessels, in particular service operation vessels (SOVs), cable laying vessels (CLVs), foundation installation vessels (FIVs), offshore construction (OCVs) and support vessels (OSVs), platform supply vessels (PSVs), and anchor-handling tug supply vessels (AHTS). In some embodiments, the marine vessel comprises research and survey vessels or other special purpose vessels, such as dredgers, heavy lift vessels or towboats. In some embodiments, the marine vessel comprises ice-going marine vessels, in particular icebreakers or marine vessels having an ice-class assigned by a classification society. In some embodiments, the marine vessel may comprise navy or coast guard vessels. In someembodiments, the marine vessel may comprise submarine vessels or unmanned remotely operated underwater vehicles (ROVs).

[0008] The marine vessel typically comprises a hull. In some embodiments, a pod of the marine propulsion unit, and particularly of the azimuthing propulsion unit, is attached to the hull of the marine vessel, in particular at the bottom of the hull. Typically, the hull defines a vessel interior and a vessel exterior. Space confined by the hull and configured to be isolated from sea water may be defined as the vessel interior. Space outside the hull, and in particular the sea, may be defined as the vessel exterior. Typically, the vessel interior is substantially free of sea water and substantially dry.

[0009] In some embodiments, the marine vessel may comprise a plurality of marine propulsion units. In particular, the marine vessel may comprise 2, 3, 4, or more marine propulsion units. Typically, each of the plurality of marine propulsion units may be controlled separately. In some embodiments, the marine vessel may comprise a single azimuthing propulsion unit with a single pod. In some embodiments, at least one azimuthing propulsion unit may be combined with one or more further marine propulsion unit on a single marine vessel. In other words, an azimuthing propulsion unit according to embodiments described herein may be combined with one or more non-azimuthing marine propulsion units. The one or more non-azimuthing marine propulsion units may be built according to embodiments described herein.

[0010] Typically, the marine propulsion unit comprises a propeller unit. Typically, the marine propulsion unit, and particularly the azimuthing propulsion unit, comprises a pod with a pod hull. The pod is configured to be rotatably attached to the hull of the marine vessel, particularly at the bottom of the hull of the marine vessel. The pod may be rotated about a substantially vertical rotation axis of the marine propulsion unit. In particular, the pod may be rotated by at least 270°, at least 315° or at least 360° about the substantially vertical rotation axis of the azimuthing propulsion unit. In typical embodiments, the rotation of the pod about the substantially vertical rotation axis of the azimuthing propulsion unit is not restricted, in particular not mechanically restricted.

[0011] Typically, the pod comprises a hull cap at a first end of the pod and the propeller unit, in particular a pushing or pulling propeller unit, attached to a second end of the pod.The first end of the pod may also be described as non-driving end, NDE, and the second end of the pod may also be described as driving end, DE, of the pod. The propeller unit typically rotates about a rotation axis of the propeller unit. The rotation axis of the propeller unit may be substantially perpendicular to the vertical rotation axis of the azimuthing propulsion unit.

[0012] In some embodiments, the marine propulsion unit comprises at least one shaft-line marine propulsion unit. Typically, in the shaft-line marine propulsion unit, the electric motor, particularly the contra-rotating electric motor, is arranged within the hull of the marine vessel. The electric motor is connected to the propeller unit via a shaft-line. The propeller unit is typically arranged at a stem of the marine vessel. Particularly, the propeller unit is typically arranged at a skeg of the marine vessel. Typically, for a shaft-line marine propulsion unit, a stern-facing side of the marine propulsion unit may be described as driving end, DE, side of the marine propulsion unit. Typically, for a shaft-line marine propulsion unit, a vessel-center facing side of the marine propulsion unit may be described as nondriving end, NDE, side of the marine propulsion unit.

[0013] In typical embodiments, the propeller unit comprises an outer shaft propeller and an inner shaft propeller. Typically, the outer shaft propeller is arranged closer to the hull than the inner shaft propeller. In a pushing propeller unit, the outer shaft propeller may also be described as front propeller and the inner shaft propeller may be described as the rear propeller; and vice versa for a pulling propeller unit. In particular, for the azimuthing propulsion unit, the outer shaft propeller is arranged closer to the vertical rotation axis than the inner shaft propeller. Typically, the outer shaft propeller and the inner shaft propeller are arranged adjacent to each other. The outer shaft propeller and the inner shaft propeller rotate about the rotation axis of the propeller unit.

[0014] Typically, the propeller unit comprises a contra rotating propeller unit. In particular, the outer shaft propeller may be configured to rotate in a first direction, particularly about the rotation axis of the propeller unit, and the inner shaft propeller may be configured to rotate in a second direction opposite to the first direction, particularly about the rotation axis of the propeller unit. In other words, the outer shaft propeller may rotate clockwise and the inner shaft propeller may rotate counterclockwise, or vice versa, about the same rotation axis. A contra rotating propeller unit may advantageously allow for a higherhydrodynamic efficiency than other propeller concepts, in particular with respect to single propellers.

[0015] In some embodiments, the outer shaft propeller has a first diameter and the inner shaft propeller has a second diameter with the second diameter being different from the first diameter, particularly the first diameter being larger than the second diameter. Typically, the outer shaft propeller comprises a first number of first blades and the inner shaft propeller comprises a second number of second blades. Typically, the second number may be different from the first number. The outer shaft propeller may comprise 3, 4, 5, 6 or 8 first blades. The inner shaft propeller may comprise 3, 4, 5, 6 or 8 second blades. In some embodiments, the outer shaft propeller comprises one more first blade than the inner shaft propeller comprises second blades. Exemplarily, the outer shaft propeller comprises 6 first blades and the inner shaft propeller comprises 5 second blades. In some embodiments, the outer shaft propeller and the inner shaft propeller may comprise the same number of blades, in particular 3, 4, 5, 6 or 8 first and second blades, respectively. The outer shaft propeller and / or the inner shaft propeller may each be manufactured as a monoblock or in components, as a built-up propeller.

[0016] Typically, the propeller unit is driven by an electric motor. Typically, the electric motor has a power of at least 100 kW, at least 1 MW, at least 2 MW, at least 5 MW, at least 10 MW or at least 15 MW. The electric motor is typically arranged within the pod or within the hull of the marine vessel. Particularly, the electric motor is mechanically connected to the propeller gearlessly and / or without a clutch. Typically, a rotation axis of the electric motor is identical to a rotation axis of the propeller unit. In particular, an output shaft of the electric motor may be identical to the drive shaft of the propeller unit or may be gearlessly connected to a drive shaft of the propeller unit. The output shaft of the electric motor typically is coaxial to the drive shaft of the propeller unit. In typical embodiments, for a propeller unit comprising an outer shaft propeller and an inner shaft propeller, in particular for the contra rotating propeller unit, the outer shaft propeller and the inner shaft propeller may be driven by the same electric motor.

[0017] The electric motor typically comprises a contra rotating electric motor. In particular, the contra rotating electric motor comprises a dual rotor electric motor with anouter rotor and an inner rotor configured to rotate in opposite directions about a rotation axis of the electric motor. Typically, the rotation axis of the electric motor may be coaxially with the rotation axis of the propeller unit. Typically, the electric motor is a synchronous electric motor. Typically, the outer rotor comprises windings to be supplied with an electric current for the operation of the electric motor. The inner rotor may be a permanent magnet rotor or an externally excited synchronous rotor.

[0018] In some embodiments, the drive shaft of the propeller comprises an outer shaft and an inner shaft. Outer shaft and inner shaft are typically coaxially arranged. Typically, the outer rotor drives the outer shaft. The outer shaft is typically mechanically connected to the outer shaft propeller gearlessly. In some embodiments, the outer shaft and / or the inner shaft may comprise at least one shaft coupling. In particular, the outer shaft and / or the inner shaft comprising at least one shaft coupling advantageously allows to modularly adapt the marine propulsion unit to the marine vessel. Exemplarily a length of the shaft may be adapted dependent on a size of the marine vessel. Typically, the inner rotor drives the inner shaft. The inner shaft is typically mechanically connected to the inner shaft propeller gearlessly. Typically, the inner shaft is arranged inside the outer shaft; in other words, an inside radius of the outer shaft exceeds an outside radius of the inner shaft. The inner shaft and the outer shaft rotate about the same rotation axis, and in particular about the rotation axis of the electric motor.

[0019] Typically, the inner shaft is supported in the pod by a drive end, DE, inner bearing and a non-drive end, NDE, inner bearing. Typically, the outer shaft is supported in the pod by a drive end, DE, outer bearing and a non-drive end, NDE, outer bearing. The NDE inner bearing and / or the NDE outer bearing may each comprise an axial bearing and a radial bearing, particularly within the same bearing housing. Employing a contra rotating electric motor may advantageously allow to drive the contra rotating propeller with a single electric motor gearlessly. Thereby, a more compact and efficient drive train may be provided.

[0020] In some embodiments, a marine propulsion unit, particularly an azimuthing propulsion unit, comprises a rotatable inner shaft and a rotatable outer shaft. The inner shaft runs at least partially within the outer shaft. The outer shaft runs at least partially within a sealing housing of a marine vessel, particularly a pod. A sealing unit for such a marinepropulsion unit, particularly an azimuthing propulsion unit, comprises a plurality of chamber systems, an inner shaft sealing and an outer shaft sealing. Each chamber system of the plurality of chamber systems comprises an inner shaft seal chamber, an outer shaft seal chamber and a passage through the outer shaft fluidly connecting the inner shaft seal chamber and the outer shaft seal chamber. The inner shaft sealing seals the inner shaft seal chambers of the plurality of chamber systems. The outer shaft sealing seals the outer shaft seal chambers of the plurality of chamber systems.

[0021] Typically, a plurality can be understood as at least one, particularly one or more. For example, a plurality of chamber systems can be understood as at least one chamber system, particularly one or more chamber systems.

[0022] In some embodiments, the outer shaft can be a DE outer shaft and the inner shaft can be a DE inner shaft.

[0023] Typically, the fluid connection of the inner chamber and the outer chamber of a chamber system enables fluid transportation between the inner chamber and the outer chamber. Particularly, fluid can be transported through the outer shaft to the inner chamber of each chamber system.

[0024] In some embodiments, the inner shaft sealing can seal an inside of the outer shaft from an outside of the marine vessel, particularly the pod. The outer shaft sealing can seal an inside of the marine vessel, particularly the pod from the outside of the marine vessel, particularly the pod. Particularly, outside of the marine vessel can be understood as outside the exterior of the marine vessel, outside the exterior of the pod, particularly outside the pod hull, outside the hull of the vessel and / or the vessel exterior. Particularly, inside of the outer shaft can be understood as the space inside the outer shaft and / or the space between the outer shaft and the inner shaft.

[0025] In some embodiments, the inner shaft sealing can comprise an inner composure, an outer composure and a plurality of inner sealing elements. Typically, the inner composure, the outer composure and the inner sealing elements can be serviced and / or replaced separately from each other.

[0026] In some embodiments, the inner composure of the inner shaft sealing can be a seal liner and the outer composure of the inner shaft sealing can be a seal housing. The seal liner can rotate with the inner shaft. An inner static sealing between the seal liner and the inner shaft can seal the inside of the outer shaft from the outside of the marine vessel, particularly the pod. The seal housing can rotate with the outer shaft. An outer static sealing between the seal housing and the outer shaft can seal the inside of the outer shaft from the outside of the marine vessel, particularly the pod.

[0027] In some embodiments, the outer composure of the inner shaft sealing can be a seal liner and the inner composure of the inner shaft sealing can be a seal housing. The seal liner can rotate with the outer shaft. An outer static sealing between the seal liner and the outer shaft can seal the inside of the outer shaft from the outside of the marine vessel, particularly the pod. The seal housing can rotate with the inner shaft. An inner static sealing between the seal housing and the inner shaft can seal the inside of the outer shaft from the outside of the marine vessel, particularly the pod.

[0028] Typically, the inner composure of the inner shaft sealing and the outer composure of the inner shaft sealing and / or the inner sealing elements can be serviced individually, e.g. replaced individually. For example, the inner sealing elements and / or the seal liner may experience larger wear in comparison to the seal housing.

[0029] In some embodiments, the outer shaft sealing can comprise an inner composure, an outer composure and a plurality of outer sealing elements. Typically, the inner composure, the outer composure and the outer sealing elements can be serviced and / or replaced separately from each other.

[0030] In some embodiments, the inner composure of the outer shaft sealing can be a seal liner and the outer composure of the outer shaft sealing can be a seal housing. The seal liner can rotate with the outer shaft. An inner static sealing between the seal liner and the outer shaft can seal the inside of the marine vessel, particularly the pod from the outside of the marine vessel, particularly the pod. The seal housing can be comprised by the sealing housing. An outer static sealing between the seal housing and the sealing housing can seal the inside of the marine vessel, particularly the pod from the outside of the marine vessel, particularly the pod.

[0031] In some embodiments, the outer composure of the outer shaft sealing can be a seal liner and the inner composure of the outer shaft sealing can be a seal housing. The seal liner can be comprised by the sealing housing. An outer static sealing between the seal liner and the sealing housing can seal the inside of the marine vessel, particularly the pod from the outside of the marine vessel, particularly the pod. The seal housing can rotate with the outer shaft. An inner static sealing between the seal housing and the outer shaft can seal the inside of the marine vessel, particularly the pod from the outside of the marine vessel, particularly the pod.

[0032] Typically, the inner composure of the outer shaft sealing and the outer composure of the outer shaft sealing and / or the outer sealing elements can be serviced individually, e.g. replaced individually. For example, the outer sealing elements and / or the seal liner may experience larger wear in comparison to the seal housing.

[0033] Typically, the plurality of inner sealing elements seals the plurality of inner shaft seal chambers and the plurality of outer sealing elements seals the plurality of outer shaft seal chambers. The inner sealing elements and / or the outer sealing elements can be sealing lips.

[0034] In some embodiments, a least one passage, particularly each passage, through the outer shaft can comprise an inner groove. The inner groove can be in at least one of: the inside of the outer shaft; and / or the inner shaft sealing. Particularly, the inner groove can be in an outer composure of the inner shaft sealing.

[0035] Typically, the inner groove of a chamber system provides a constant fluid connection between the inner shaft seal chamber of the chamber system and the outer shaft seal chamber of the chamber system. Particularly, the inner groove of the chamber system provides a constant fluid connection between the inner shaft seal chamber of the chamber system and the channels of the chamber system through the outer shaft.

[0036] In some embodiments, an inner groove can be sealed by at least one inner groove sealing element. The inner groove sealing element(s) can typically prevent leakage between the inner grooves. Particularly, each inner groove sealing element can be a static ring and / or a sealing ring.

[0037] In some embodiments, at least one passage, particularly each passage, through the outer shaft can comprise an outer groove. The outer groove can be in at least one of: the outside of the outer shaft; and / or the outer shaft sealing. Particularly, the outer groove can be in the inner composure of the outer shaft sealing.

[0038] Typically, the outer groove of a chamber system provides a constant fluid connection between the inner shaft seal chamber of the chamber system and the outer shaft seal chamber of the chamber system. Particularly, the outer groove of the chamber system provides a constant fluid connection between the outer shaft seal chamber of the chamber system and the channels of the chamber system through the outer shaft.

[0039] In some embodiments, an outer groove can be sealed by at least one outer groove sealing element. The outer groove sealing element(s) can typically prevent leakage between the outer grooves. Particularly, each outer groove sealing element can be a static ring and / or a sealing ring.

[0040] In some embodiments, at least one passage, particularly each passage, through the outer shaft can comprise a plurality of channels through the outer shaft fluidly connecting the inner shaft seal chamber and the outer shaft seal chamber, particularly the inner shaft seal chamber and the outer shaft seal chamber of one chamber system.

[0041] In some embodiments, at least one passage, particularly each passage, through the outer shaft can comprise a plurality of channels through the outer shaft fluidly connecting the inner groove and the outer groove.

[0042] In some embodiments, a plurality of channels through the outer shaft can typically provide an improved fluid connection between the inner shaft seal chamber of a chamber system and the outer shaft seal chamber of the chamber system. Particularly, a plurality of channels through the outer shaft can typically provide an improved fluid connection between the inner groove of a chamber system and the outer groove of the chamber system.

[0043] In some embodiments, at least one passage, particularly each passage, through the outer shaft can comprise at least one hole, drilled through the outer shaft. Particularly, each channel of the plurality of channels of each passage through the outer shaft can comprise a hole, drilled through the outer shaft.

[0044] In some embodiments, drilling a hole through the outer shaft provides a simple method to create a channel, a plurality of channels and / or a passage through the outer shaft of an appropriate size and / or at an appropriate location.

[0045] In some embodiments, the plurality of chamber systems can comprise a proximate chamber system. The proximate chamber system can be fluidly connected to an oil reservoir. Particularly, oil can be transferred from the oil reservoir to the proximate chamber system.

[0046] Typically, oil can be transferred from the oil reservoir to the inner shaft seal chamber through the outer shaft seal chamber and the passage through the outer shaft. Particularly, oil can be transferred from the proximate chamber system to the oil reservoir. Typically, oil can be transferred from the inner shaft seal chamber to the oil reservoir through the outer shaft seal chamber and / or the passage through the outer shaft.

[0047] Typically, the pressure inside the proximate chamber system is adjustable. Particularly the pressure inside the proximate chamber system is adjustable by adjusting the pressure inside the oil reservoir. Particularly, the sealing properties of the sealing unit can be improved by optimizing the pressure inside the proximate chamber system.

[0048] In some embodiments, the plurality of chamber systems can comprise a distant chamber system. Particularly, the distant chamber system can be free from oil. Typically, oil contamination of water leaking in the distant chamber system can be avoided.

[0049] In some embodiments, the plurality of chamber systems can comprise an intermediate chamber system. The intermediate chamber system can be fluidly connected to an air reservoir, particularly to a pressurized air reservoir.

[0050] Particularly, air can be transferred from the air reservoir, particularly the pressurized air reservoir, to the intermediate chamber system. Typically, air can be transferred from the air reservoir, particularly the pressurized air reservoir, to the inner shaft seal chamber through the outer shaft seal chamber and the passage through the outer shaft.

[0051] Particularly, air, leakage oil and / or leakage water can be transferred from the intermediate chamber system to the air reservoir, particularly the pressurized air reservoir. Typically, air, leakage oil and / or leakage water can be transferred from the inner shaft sealchamber to the air reservoir, particularly the pressurized air reservoir, through the outer shaft seal chamber and / or the passage through the outer shaft. Typically, air, leakage oil and / or leakage water can be transferred from the inner shaft seal chamber to an outlet reservoir, particularly an outlet reservoir of the air reservoir, particularly of the pressurized air reservoir, through the outer shaft seal chamber and / or the passage through the outer shaft.

[0052] Typically, the pressure inside the intermediate chamber system is adjustable. Particularly the pressure inside the intermediate chamber system is adjustable by adjusting the pressure inside the air reservoir, particularly the pressurized air reservoir. Typically, the sealing properties of the sealing unit can be improved by adjusting the pressure inside the intermediate chamber system.

[0053] Typically, leakage oil and / or leakage water can be removed from the intermediate chamber system. Typically, oil contamination of the distant chamber system can be avoided and / or water contamination of the proximate chamber system can be avoided. Particularly, the intermediate chamber system can seal the proximate chamber system from the distant chamber system.

[0054] In some embodiments, the air reservoir, particularly the pressurized air reservoir, can be fluidly connected to a compressor. In some embodiments, the air reservoir, particularly the pressurized air reservoir, can be a compressor. In some embodiments, the air reservoir, particularly the pressurized air reservoir, can be a pressurized air network, particularly a pressurized air network of a vessel.

[0055] In some embodiments, the proximate chamber system can be the chamber system of the plurality of chamber systems closest to a motor. The motor can be configured to drive the inner shaft and / or the outer shaft. The motor can be a dual rotor electric motor. The distant chamber system can be the chamber system of the plurality of chamber systems farthest from the motor. The intermediate chamber system can be a chamber system of the plurality of chamber systems between the proximate chamber system and the distant chamber system.

[0056] In some embodiments, the plurality of chamber systems can comprise a proximate chamber system, a distant chamber system and an intermediate chamber system. Theproximate chamber system can be fluidly connected to an oil reservoir and the intermediate chamber system can be fluidly connected to an air reservoir, particularly a pressurized air reservoir.

[0057] Particularly, water from outside of the marine vessel, particularly the pod may leak inside the distant chamber system. The intermediate chamber system may seal the distant chamber system from the proximate chamber system. Typically, contamination of the distant chamber system with oil can be avoided. Typically, contamination of the proximate chamber system with water can be avoided.

[0058] In some embodiments, the plurality of chamber systems can comprise at least four chamber systems. At least two chamber systems of the plurality of chamber systems can be fluidly connected to an oil reservoir and / or at least one chamber system of the plurality of chamber systems can be fluidly connected to an air reservoir, particularly a pressurized air reservoir.

[0059] In some embodiments, each chamber system of the plurality of chamber systems can contain at least one of: (a) oil; (b) air; and / or (c) leakage fluid. Typically, the air can be pressurized air. Typically, the leakage fluid can be oil leaked from a neighboring chamber system and / or water leaked from outside the marine vessel, particularly the pod.

[0060] In some embodiments, each fluid connection of a chamber system of the plurality of chamber systems with a reservoir can comprise a supply groove. The supply groove can be in at least one of: the sealing housing; and / or the outer shaft sealing.

[0061] In some embodiments, each fluid connection of a chamber system of the plurality of chamber systems with a reservoir can comprise at least one supply channel. Each supply channel can fluidly connect the chamber system with the reservoir. Typically, at least one supply channel can be an inlet supply channel and at least one supply channel can be an outlet supply channel. Typically, fluid can be transferred from the reservoir to the chamber system through the inlet supply channel. Typically, fluid can be transferred from the chamber system to the reservoir through the outlet supply channel.

[0062] In some embodiments, a reservoir can comprise an inlet reservoir. Typically, fluid can be transferred from the inlet reservoir to a chamber system of the plurality of chambersystems through at least one inlet supply channel. Typically, the inlet reservoir can provide fresh / ready-to-use fluid to a chamber system.

[0063] In some embodiments, a reservoir can comprise an outlet reservoir. Typically, fluid can be transferred from a chamber system of the plurality of chamber systems to the outlet reservoir through at least one outlet supply channel. Typically, the outlet reservoir can receive used fluid, e.g. contaminated fluid such as oil-contaminated water, water-contaminated oil, oil-contaminated air and / or water-contaminated air.

[0064] In some embodiments, a supply groove can be sealed by at least one supply groove sealing element. Particularly, each outer groove sealing element can be a static ring and / or a sealing ring. Typically, the supply groove(s) provide(s) a constant fluid connection between the outer shaft seal chamber(s) and the supply channel(s).

[0065] In some embodiments, the propulsion unit can further comprise an inner bearing and an outer bearing. The inner bearing can be inside an inner bearing chamber between the inner shaft and the outer shaft. The outer bearing can be inside an outer bearing chamber between the outer shaft and the bearing housing. The sealing unit can further comprise an inner bearing sealing and an outer bearing sealing. The inner bearing sealing can seal the inside of the marine vessel, particularly the pod from the inner bearing chamber. The outer bearing sealing can seal the inside of the marine vessel, particularly the pod from the outer bearing chamber.

[0066] In some embodiments, the inner bearing can be a DE inner bearing and the outer bearing can be a DE outer bearing.

[0067] In some embodiments, the inner bearing chamber and / or the outer bearing chamber can be filled with oil.

[0068] In some embodiments, the bearing housing and the sealing housing can be connected. Particularly, the bearing housing and the sealing housing can be provided in a combined bearing and sealing housing.

[0069] Typically, oil from inside the inner bearing chamber can be prevented from leaking inside the marine vessel, particularly the pod by the inner bearing sealing. Typically, oil frominside the outer bearing chamber can be prevented from leaking inside the marine vessel, particularly the pod by the outer bearing sealing.

[0070] In some embodiments, the inner bearing chamber and the outer bearing chamber can be fluidly connected. Typically, oil can be supplied from an oil reservoir to the inner bearing chamber through the outer bearing chamber.

[0071] In some embodiments, the inner shaft sealing can seal the outside of the marine vessel, particularly the pod from the inner bearing chamber. The outer shaft sealing can seal the outside of the marine vessel, particularly the pod from the outer bearing chamber. Typically, oil from inside the inner bearing chamber and / or from inside the outer bearing chamber can be prevented from leaking to the outside of the marine vessel, particularly the pod. Typically, water from the outside of the marine vessel, particularly the pod can be prevented from leaking inside the inner bearing chamber and / or the outer bearing chamber.

[0072] An embodiment describes a method for servicing a sealing unit in a marine propulsion unit, particularly an azimuthing propulsion unit. The propulsion unit comprises a rotatable inner shaft and a rotatable outer shaft, wherein the inner shaft runs at least partially within the outer shaft and wherein the outer shaft runs at least partially within a sealing housing of a marine vessel, particularly the pod. The sealing unit is a sealing unit according to any embodiment described herein. The method for servicing the sealing unit comprises: providing a service sealing arrangement, wherein the service sealing arrangement seals the inner shaft sealing from the outside of the marine vessel, particularly the pod; dismounting, at least partially, through a hatch provided in the outer shaft, an inner bearing between the inner shaft and the outer shaft; dismounting, at least partially, the inner shaft sealing through the hatch; servicing the inner shaft sealing; mounting the serviced inner shaft sealing through the hatch; and mounting the inner bearing through the hatch.

[0073] In some embodiments, the service sealing arrangement can be a pneumostop sealing arrangement.

[0074] In some embodiments, dismounting, at least partially, the inner bearing can comprise moving, at least partially, the inner bearing along a rotation axis of the inner shaft to provide access to the inner shaft sealing through the hatch.

[0075] In some embodiments, servicing the inner shaft sealing can comprise: replacing at least one inner sealing element of the inner shaft sealing; and bonding the new inner sealing element(s). Typically, bonding the new inner sealing element can provide a continuous sealing element around the entire circumference of the inner shaft.

[0076] Typically, the inner shaft sealing of the sealing unit in the marine propulsion unit, particularly the azimuthing propulsion unit, can be serviced without removing the marine propulsion unit, particularly the azimuthing propulsion unit, from the water. Particularly, the inner shaft sealing of the sealing unit in the marine propulsion unit, particularly the azimuthing propulsion unit, can be serviced without the use of a dry dock and / or without removing the vessel from the water.

[0077] In some embodiments, the service sealing arrangement can seal the outer shaft sealing from the outside of the marine vessel, particularly the pod. The method can further comprise: dismounting, at least partially, an outer bearing between the outer shaft and the bearing housing; dismounting, at least partially, the outer shaft sealing; servicing the outer shaft sealing; mounting the serviced outer shaft sealing; and mounting the outer bearing.

[0078] In some embodiments, the service sealing arrangement can comprise a service sealing to seal the inner shaft sealing and the outer shaft sealing from the outside of the marine vessel, particularly the pod. In some embodiment, the service sealing arrangement can comprise an inner service sealing to seal the inner shaft sealing from the outside of the marine vessel, particularly the pod. In some embodiments, the service sealing arrangement can comprise an outer service sealing to seal the outer shaft sealing from the outside of the marine vessel, particularly the pod. In some embodiments, the service sealing arrangement can comprise the inner service sealing and the outer service sealing. Typically, the inner service sealing and the outer service sealing may be activated and / or deactivated at the same time, particularly through the same mechanism.

[0079] In some embodiments, servicing the outer shaft sealing can comprise: replacing at least one outer sealing element of the outer shaft sealing; and bonding the new outer sealing element(s). Typically, bonding the new outer sealing element can provide a continuous sealing element around the entire circumference of the outer shaft.

[0080] In some embodiments, the method can further comprise: dismounting, at least partially, an outer bearing sealing, wherein the outer bearing sealing seals the inside of the marine vessel, particularly the pod, from the outer bearing chamber; and mounting the outer bearing sealing. Typically, dismounting the outer bearing sealing provides access to the outer bearing.

[0081] Typically, the outer shaft sealing of the sealing unit in the marine propulsion unit, particularly the azimuthing propulsion unit, can be serviced without removing the marine propulsion unit, particularly the azimuthing propulsion unit, from the water. Particularly, the outer shaft sealing of the sealing unit in the marine propulsion unit, particularly the azimuthing propulsion unit, can be serviced without the use of a dry dock and / or without removing the vessel from the water.

[0082] In some embodiments, the method can further comprise: mounting an inner spacer ring arrangement between the inner shaft and the outer shaft. The inner spacer ring arrangement can define the location of the inner shaft sealing, particularly of the inner sealing elements, the outer composure of the inner shaft sealing and / or the inner composure of the inner shaft sealing, along the rotation axis of the inner shaft.

[0083] The inner spacer ring arrangement can comprise a first inner spacer ring and / or a second inner spacer ring. The first inner spacer ring can engage with the inner shaft, particularly with a shaft shoulder of the inner shaft, and the inner shaft sealing, particularly the inner composure of the inner shaft sealing. The second inner spacer ring can engage with the outer shaft, particularly with a shaft shoulder of the outer shaft, and the inner shaft sealing, particularly the outer composure of the inner shaft sealing.

[0084] Typically, the location of the inner shaft sealing, the inner composure of the inner shaft sealing, the outer composure of the inner shaft sealing and / or the inner sealing elements along the rotation axis of the inner shaft can be changed be replacing a mounted inner spacer ring arrangement with a replacement inner spacer ring arrangement. The mounted inner spacer ring arrangement, particularly the first inner spacer ring and / or the second inner spacer ring of the mounted inner spacer ring arrangement, can have a different thickness, particularly a thickness in the direction of the rotation axis of the inner shaft and the outer shaft, compared to the thickness, particularly a thickness in the direction of the rotation axisof the inner shaft and the outer shaft, of the replacement inner spacer ring arrangement, particularly the first inner spacer ring and / or the second inner spacer ring of the replacement inner spacer ring arrangement.

[0085] Typically, by changing the location of the inner shaft sealing, of the inner composure of the inner shaft sealing, of the outer composure of the inner shaft sealing and / or of the inner sealing elements along the rotation axis of the inner shaft, the inner shaft sealing, the inner composure of the inner shaft sealing, the outer composure of the inner shaft sealing and / or the inner sealing elements can be relocated to a location on the inner shaft with less wear. Typically, by changing the location of the inner composure of the inner shaft sealing and / or the location of the outer composure of the inner shaft sealing the inner composure of the inner shaft sealing can be relocated compared to the outer composure of the inner shaft sealing (or vice versa). Particularly, the inner sealing elements can be relocated relative to the inner composure of the inner shaft sealing or the outer composure of the inner shaft sealing to a location with less wear on the inner composure of the inner shaft sealing or the outer composure of the inner shaft sealing.

[0086] In some embodiments, the method can further comprise: mounting an outer spacer ring arrangement between the outer shaft and the sealing housing. The outer spacer ring arrangement can define the location of the outer shaft sealing, particularly of the outer sealing elements, the outer composure of the outer shaft sealing and / or the inner composure of the outer shaft sealing, along the rotation axis of the outer shaft.

[0087] The outer spacer ring arrangement can comprise a first outer spacer ring and / or a second outer spacer ring. The first outer spacer ring can engage with the outer shaft, particularly with a shaft shoulder of the outer shaft, and the outer shaft sealing, particularly the inner composure of the outer shaft sealing. The second outer spacer ring can engage with the sealing housing, particularly with a shoulder of the sealing housing, and the outer shaft sealing, particularly the outer composure of the outer shaft sealing.

[0088] Typically, the location of the outer shaft sealing, of the inner composure of the outer shaft sealing, of the outer composure of the outer shaft sealing and / or of the outer sealing elements on the outer shaft can be changed be replacing a mounted outer spacer ring arrangement with a replacement outer spacer ring arrangement. The mounted outer spacerring arrangement, particularly the first outer spacer ring and / or the second outer spacer ring of the mounted outer spacer ring arrangement, can have a different thickness, particularly a thickness in the direction of the rotation axis of the inner shaft and the outer shaft, compared to the thickness, particularly a thickness in the direction of the rotation axis of the inner shaft and the outer shaft, of the replacement outer spacer ring arrangement, particularly the first outer spacer ring and / or the second outer spacer ring of the replacement outer spacer ring arrangement.

[0089] Typically, by changing the location of the outer shaft sealing, of the inner composure of the outer shaft sealing, of the outer composure of the outer shaft sealing and / or of the outer sealing elements along the rotation axis of the outer shaft, the outer shaft sealing, the inner composure of the outer shaft sealing, the outer composure of the outer shaft sealing and / or the outer sealing elements can be relocated to a location on the outer shaft with less wear. Typically, by changing the location of the inner composure of the outer shaft sealing and / or the outer composure of the outer shaft sealing the inner composure of the outer shaft sealing can be relocated compared to the outer composure of the outer shaft sealing (or vice versa). Particularly, the outer sealing elements can be relocated relative to the inner composure of the outer shaft sealing or the outer composure of the outer shaft sealing to a location with less wear on the inner composure of the outer shaft sealing or the outer composure of the outer shaft sealing.BRIEF DESCRIPTION OF THE DRAWINGS

[0090] The accompanying drawings relate to embodiments of the disclosure and are described in the following:FIG la schematically illustrates a marine propulsion unit according to the embodiments described herein;FIG lb schematically illustrates a marine propulsion unit according to the embodiments described herein;FIG 1c schematically illustrates a marine propulsion unit according to the embodiments described herein;FIG Id schematically illustrates a marine propulsion unit according to the embodiments described herein;FIG le schematically illustrates a marine propulsion unit according to the embodiments described herein;FIG If schematically illustrates a marine propulsion unit according to the embodiments described herein;FIG 2 schematically illustrates a sealing unit inside a marine propulsion unit according to the embodiments described herein;FIG 3 schematically illustrates a sealing unit inside a marine propulsion unit according to the embodiments described hereinFIG 4 schematically illustrates a method for servicing a sealing unit inside a marine propulsion unit according to the embodiments described herein.DETAILED DESCRIPTION OF EMBODIMENTS

[0091] Reference will now be made in detail to the various embodiments of the disclosure, one or more examples of which are illustrated in the figures. Generally, only the differences with respect to individual embodiments are described. Each example is provided by way of explanation of the disclosure and is not meant as a limitation of the disclosure. Further, features illustrated or described as part of one embodiment can be used on or in conjunction with other embodiments to yield a further embodiment. It is intended that the description includes such modifications and variations. In the figures, elements may be depicted with exaggerated dimensions to improve the comprehensibility of the detailed description of embodiments. In particular, relations of lengths and widths of components shown may be distorted. Further, some elements may be depicted with enlarged dimensions while other elements in the same figure are depicted, relatively, with reduced dimensions.

[0092] Fig. la schematically illustrates a marine propulsion unit, particularly in the embodiments of Fig. la - 1c an azimuthing propulsion unit, 1000 according to typical embodiments described herein. In Fig. Id - If, a shaft-line marine propulsion unit 2000 is schematically illustrated. The azimuthing propulsion unit 1000 of Fig. la comprises a dual rotor electric motor 1. The dual rotor electric motor 1 may also be described as contra rotating electric motor. The dual rotor electric motor 1 is typically arranged substantially horizontally centrally within the azimuthing propulsion unit 1000. Particularly, the dual rotor electric motor 1 is arranged within a pod of the azimuthing propulsion unit 1000.

[0093] The dual rotor electric motor 1 comprises an inner rotor 2 and an outer rotor 3. The inner rotor 2 is arranged within the outer rotor 3. Inner rotor 2 and outer rotor 3 are arranged coaxially with respect to each other. The inner rotor 2 and the outer rotor 3 are configured to rotate about a rotation axis 50. The rotation axis 50 is a longitudinal axis of the azimuthing propulsion unit 1000. The inner rotor 2 drives an inner shaft propeller 10 and the outer rotor 3 drives an outer shaft propeller 9. The outer shaft propeller 9 and the inner shaft propeller 10 are arranged coaxially and rotate about the rotation axis 50. The outer shaft propeller 9 and the inner shaft propeller 10 form a contra rotating propeller unit. In the embodiment of Fig. la, the outer shaft propeller 9 and the inner shaft propeller 10 substantially have the same diameter. In embodiments not shown in Fig. la the outer shaft propeller 9 may have a diameter different from the diameter of the inner shaft propeller 10. Exemplarily, the outer shaft propeller 9 may have a diameter of at least 6 m, exemplarily of 6.1 m, and the inner shaft propeller 10 may have a diameter of at most 6 m, exemplarily of 5.575 m.

[0094] The outer rotor 3 of the dual rotor electric motor 1 typically comprises a perforated tube 4, as shown in the typical embodiment of Fig. la. The perforated tube 4 mechanically supports the outer rotor winding and comprises a plurality of openings. The plurality of openings of the perforated tube 4 are configured to pass air from an exterior of the dual rotor electric motor 1 into an interior of the dual rotor electric motor 1, and vice versa. Warm air, particularly heated by the dual rotor electric motor 1, may pass from an air gap 23 between the inner rotor 2 and the outer rotor 3 through the perforated tube to an annular air channel 14.

[0095] The perforated tube 4 transmits a torque of the outer rotor 3 to outer rotor end flanges 5, 6. A non-drive end, NDE, outer rotor end flange 5 connects the perforated tube 4 to an NDE outer shaft 47. A drive end, DE, outer rotor end flange 6 connects the perforated tube 4 to a DE outer shaft 7. The DE outer shaft 7 transmits the torque of the outer rotor 3 to the outer shaft propeller 9. The outer shaft propeller 9 comprises a plurality of first blades 21, of which two are visible in Fig. la. The inner rotor 2 is connected to an NDE inner shaft 48 and to a DE inner shaft 8. The DE inner 8 shaft transmits the torque of the inner rotor 2 to the inner shaft propeller 10. The inner shaft propeller 10 comprises a plurality of second blades 22, of which two are visible in Fig. la. In the embodiment of Fig. la, the outer shaft propeller 9 and the inner shaft propeller 10 are arranged in a pulling configuration. In particular, the first blades 21 and the second blades 22 are configured to operate in a pulling mode.

[0096] The NDE inner shaft 48 is supported in the pod 30 by an NDE inner bearing 42. The NDE outer shaft 47 is supported in the pod 30 by an NDE outer bearing 41. The NDE outer bearing 41 and the NDE inner bearing 42 typically comprise an oil seal, respectively. The DE outer shaft 7 is supported in the pod 30 by a DE outer bearing 11. The DE inner shaft 7 is supported in the DE outer shaft 8 by a DE inner bearing 12. The DE outer bearing 11 and the DE inner bearing 12 typically comprise an oil and water seal, respectively.

[0097] The dual rotor electric motor 1 is provided with electric energy via a slip ring unit 19. The slip ring unit 19 is typically arranged on the non-drive end side of the dual rotor electric motor 1 and particularly to contact the NDE outer shaft 47 as shown in Fig. la. The NDE outer shaft 47 and the NDE outer rotor end flange 5 are configured to electrically connect the slip ring unit 19 to the dual rotor electric motor 1. The slip ring unit 19 comprises at least one sliding contact to transmit electricity from power supply cables 20 to the dual rotor electric motor 1 and particularly to the outer rotor 3 of the dual rotor electric motor 1. From the outer rotor 3, electricity is provided to windings of the dual rotor electric motor 1. The power supply cables 20 provide electrical power from a marine vessel, and particular from a power supply of the marine vessel to the dual rotor electric motor 1 via the slip ring unit 19. The slip ring unit 19 comprises a slip ring unit housing 39. The slip ring unit housing 39 separates the slip ring unit 19 from a further interior of the pod 30 and particularly isconfigured to prevent dust generated inside the slip ring unit 19, particularly generated by the at least one sliding contact of the slip ring unit 19, to escape to the interior of the pod 30.

[0098] Inside the pod 30 of the azimuthing propulsion unit 1000, air is circulated. The azimuthing propulsion unit 1000 comprises a cooling air unit 16. In the embodiment of Fig. la, the cooling air unit 16 is arranged within a hull of a marine vessel. In the typical embodiment shown in Fig. la, the cooling air unit 16 comprises an air fan 17 to circulate air. The cooling air unit 16 typically comprises a heat exchanger 18. By the heat exchanger 18, warm air entering the heat exchanger 18 from the pod 30 is cooled with heat being at least partially transferred to a cooling agent of the heat exchanger 18. The cooling air unit 16 provides cool air to the dual rotor electric motor 1 via a DE ingoing air channel 31 and an NDE ingoing air channel 32 in the pod 30. The DE ingoing air channel 31 is physically separated from an outgoing air channel 33 by an DE air channel separating wall 34 in Fig. la. The NDE ingoing air channel 32 is physically separated from the outgoing air channel 33 by an NDE air channel separating wall 35 in Fig. la. Typically, the outgoing air channel 33 substantially extends in the center of the pod 30 and particularly along a vertical central axis of the pod 30. Air passing through the DE ingoing air channel 31 and / or the NDE ingoing air channel 32 passes through openings of the perforated tube 4 and / or the outer rotor end flanges 5, 6 into an interior of the dual rotor electric motor 1. Within the dual rotor electric motor 1, the air may be heated by the dual rotor electric motor 1, in particular when in operation. The air may exit the dual rotor electric motor 1 via radial openings of the perforated tube 4 towards the annular air channel 14. The annular air channel 14 is connected to the outgoing air channel 33.

[0099] In Fig. lb, the azimuthing propulsion unit 1000 is configured to operate in a pushing mode. In particular, the first blades 21 and the second blades 22 are configured to operate in a pushing mode. In Fig. 1c, a side view of the azimuthing propulsion unit 1000 of the embodiment of Fig. lb is schematically shown.

[0100] In Fig. Id and Fig. le, a marine propulsion unit 2000 is schematically illustrated. The marine propulsion unit 2000 is arranged within the hull 2100 of the marine vessel. Particularly, the marine propulsion unit 2000 is arranged in a shaft-line configuration with the dual rotor electric motor 1 being arranged within the hull 2100 of the marine vessel.Similar to the azimuthing propulsion unit 1000, as shown in Fig. la - 1c, the marine propulsion unit 2000 comprises the dual rotor electric motor 1, a drive shaft connecting the dual rotor electric motor 1 to the propeller unit with the outer shaft propeller 9 and the inner shaft propeller 10. The outer shaft propeller 9 and the inner shaft propeller 10 are arranged at a skeg of the hull 2100 of the vessel. Generally, the drive shaft, the dual rotor electric motor 1, the outer shaft propeller 9 and the inner shaft propeller 10, the DE and NDE bearings 41, 42 and the slip ring unit 19 of the marine propulsion unit 2000 can be arranged similar or substantially identical to the azimuthing propulsion unit as shown in Fig. la - 1c.

[0101] In Fig. Id, the marine propulsion unit 2000 comprises a motor block 2050. Within the motor block 2050, the drive shaft, the dual rotor electric motor 1, the DE and NDE bearings 41, 42 and the slip ring unit 19 of the marine propulsion unit 2000 are arranged. The motor block 2050 comprises an outgoing air channel 33 and, typically, a DE ingoing air channel and an NDE ingoing air channel (not explicitly shown in Fig. Id). In embodiments not shown in the Figures, the marine propulsion unit may comprise an axial air cooling. Particularly, for the axial air cooling, air may enter the dual rotor electric motor 1 from a DE side and exit the dual rotor electric motor 1 from an NDE side or vice versa. The outgoing air channel 33 and the ingoing air channels are connected to the cooling air unit 16. Typically, the cooling air unit 16 is arranged outside the motor block 2050. In some embodiments (not shown in the Figures), particularly for a large motor block 2050, the cooling air unit 16 may be arranged inside the motor block 2050. The motor block 2050 follows a contour of the hull 2100 of the vessel. Particularly, the motor block 2050 forms a skeg of the hull 2100 of the vessel. The motor block 2050 is typically welded to the hull 2100 at a welding area 61.

[0102] In Fig. le, the marine propulsion unit 2000 comprises a marine propulsion unit housing 2010. Within the marine propulsion unit housing 2010, the drive shaft, the dual rotor electric motor 1, the slip ring unit 19 and the NDE bearings 41,42 are arranged. The marine propulsion unit housing 2010 is configured to be inserted in the hull 2100 via the skeg of the hull 2100.

[0103] In Fig. If, the dual motor electric motor 1, the slip ring unit 19 and the NDE bearings 41,42 are arranged within the hull of the marine vessel. The dual rotor electric motor1 is connected to the contra rotating propeller 9, 10 via the drive shaft. In Fig. If, the drive shaft is longer that in the embodiments shown in Fig. Id and le. Particularly, the drive shaft may have a length of at least 5 times a length of the dual rotor electric motor 1. In part, the drive shaft extends outside the hull of the marine vessel as an exposed shaft. The drive shaft is supported by support bearings 45, 46. In the hull, the dual motor electric motor 1, the slip ring unit 19 and the DE and NDE bearings 41, 42 are accessible for maintenance.

[0104] FIG 2 schematically illustrates an exemplary sealing unit inside a marine propulsion unit, particularly an azimuthing propulsion unit. The sealing unit comprises a plurality of chamber systems, an inner shaft sealing 810 and an outer shaft sealing 820. Each chamber system of the plurality of chamber systems comprises an inner chamber 817a, 817b, 817c, an outer chamber 827a, 827b, 827c and a passage through the outer shaft 7 fluidly connecting the inner chamber 817a, 817b, 817c and the outer chamber 827a, 827b, 827c. The inner shaft sealing 810 is arranged between the inner shaft 8 and the outer shaft 7. The inner shaft sealing 810 can seal the inner chambers 817a, 817b, 817c of the plurality of chamber systems. The outer shaft sealing 820 is arranged between the outer shaft 7 and the sealing housing 801. The outer shaft sealing 820 seals the outer chambers 827a, 827b, 827c of the plurality of chamber systems.

[0105] The sealing unit is typically arranged along the rotation axis of the propeller unit between the inner shaft propeller and the motor. In some embodiments that may be combined with other embodiments, the sealing unit, particularly the inner shaft sealing and the outer shaft sealing, may be arranged along the rotation axis of the propeller unit between the outer shaft propeller and the motor, particularly the inner rotor and the outer rotor. In some embodiments that may be combined with other embodiments, the sealing unit, particularly the inner shaft sealing and the outer shaft sealing, may be arranged inside the marine vessel, particularly the pod.

[0106] The inner shaft sealing 810 typically comprises an inner composure 811, an outer composure 813 and a plurality of inner sealing elements 815. For example, each inner sealing element 815 of the plurality of inner sealing elements 815 composed by the inner shaft sealing 810 is a sealing lip.

[0107] The outer shaft sealing 820 typically comprises an inner composure 821, an outer composure 823 and a plurality of outer sealing elements 825. For example, each outer sealing element 825 of the plurality of outer sealing elements 825 composed by the outer shaft sealing 820 is a sealing lip.

[0108] Each passage through the outer shaft 7 typically comprises an inner groove 835a, 835b, 835c. The inner groove 835a, 835b, 835c is in the inside of the outer shaft 7. Alternatively, the inner groove 835a, 835b, 835c can be in the inner shaft sealing 810 and / or the inner groove 835a, 835b, 835c can be in the outer composure 813 of the inner shaft sealing 810. Typically, the inner groove 835a, 835b, 835c can be in the inside of the outer shaft 7 and in the inner shaft sealing 810.

[0109] Each passage through the outer shaft 7 typically comprises an outer groove 833a, 833b, 833c. The outer groove 833a, 833b, 833c is in the outside of the outer shaft 7. Alternatively, the outer groove 833a, 833b, 833c can be in the outer shaft sealing 820 and / or the outer groove 833a, 833b, 833c can be in the inner composure 821 of the outer shaft sealing 820. Typically, the outer groove 833a, 833b, 833c can be in the outside of the outer shaft 7 and in the outer shaft sealing 820.

[0110] Each passage through the outer shaft 7 comprises a plurality of channels 831a, 83 lb, 831c through the outer shaft 7 fluidly connecting one of the inner shaft seal chambers 817a, 817b, 817c and one of the outer grooves 827a, 827b, 827c.

[0111] A proximate chamber system comprises the outer shaft seal chamber 827a, the inner shaft seal chamber 817a, the outer groove 833a, the inner groove 835a and the channel 831a.

[0112] An intermediate chamber system comprises the outer shaft seal chamber 827b, the inner shaft seal chamber 817b, the outer groove 833b, the inner groove 835b and the channel 831b.

[0113] A distant chamber system comprises the outer shaft seal chamber 827c, the inner shaft seal chamber 817c, the outer groove 833c, the inner groove 835c and the channel 831c.

[0114] Each chamber system of the plurality of chamber systems can be fluidly connected to a reservoir. Each fluid connection comprises a supply groove 843 in the sealing housing 801 and / or each fluid connection comprises a supply groove 843 in the outer shaft sealing 820 and / or each fluid connection comprises a supply groove 843 in the outer composure 823 of the outer shaft sealing 820. At least two (only one is shown) supply channels 841 fluidly connect the chamber system and the reservoir. Particularly, each supply channel 841 fluidly connects the supply groove 843 and the reservoir.

[0115] In FIG 2 the proximate chamber system is connected to an oil reservoir (not shown) by the supply groove 843 and at least two (only one is shown) supply channels 841.

[0116] The intermediate chamber system can be connected to an air reservoir, particularly a pressurized air reservoir, by a supply groove and at least one supply channels (not shown). The distant chamber system can be connected to a reservoir by a supply groove and at least one supply channels (not shown).

[0117] The inner shaft sealing 810 typically seals further inner shaft seal chambers 817d, 817e. The outer shaft sealing 820 typically seals further outer shaft seal chambers 827d, 827e. In some embodiments, the further inner shaft seal chambers 817d, 817e and the further outer shaft seal chambers 827d, 827e are not fluidly connected.

[0118] In some embodiments, the inner shaft sealing can seal at least one further inner shaft seal chamber. In some embodiments, the outer shaft sealing can seal at least one further outer shaft seal chamber. In some embodiments, the inner shaft sealing can seal X further inner shaft seal chamber(s). X may be any number equal to or larger than 1. In some embodiments, the outer shaft sealing can seal Y further outer shaft seal chamber(s). Y may be any number equal to or larger than 1. In some embodiments, X may equal Y. In some embodiments, X may be different than Y.

[0119] FIG 3 schematically illustrates an exemplary sealing unit inside a marine propulsion unit, particularly an azimuthing propulsion unit. The sealing unit comprises a plurality of chamber systems, an inner shaft sealing 810 and an outer shaft sealing 820. Each chamber system of the plurality of chamber systems comprises an inner chamber 817a, 817b, 817c, an outer chamber 827a, 827b, 827c and a passage through the outer shaft 7 fluidlyconnecting the inner chamber 817a, 817b, 817c and the outer chamber 827a, 827b, 827c. The inner shaft sealing 810 is arranged between the inner shaft 8 and the outer shaft 7. The inner shaft sealing 810 can seal the inner chambers 817a, 817b, 817c of the plurality of chamber systems. The outer shaft sealing 820 is arranged between the outer shaft 7 and the sealing housing 801. The outer shaft sealing 820 seals the outer chambers 827a, 827b, 827c of the plurality of chamber systems.

[0120] The inner shaft sealing 810 typically comprises an inner composure 811, an outer composure 813 and a plurality of inner sealing elements 815. For example, each inner sealing element 815 of the plurality of inner sealing elements 815 composed by the inner shaft sealing 810 is a sealing lip.

[0121] The outer shaft sealing 820 typically comprises an inner composure 821, an outer composure 823 and a plurality of outer sealing elements 825. For example, each outer sealing element 825 of the plurality of outer sealing elements 825 composed by the outer shaft sealing 820 is a sealing lip.

[0122] Each passage through the outer shaft 7 typically comprises an inner groove 835a, 835b, 835c. The inner groove 835a, 835b, 835c is in the inside of the outer shaft 7. Alternatively, the inner groove 835a, 835b, 835c can be in the inner shaft sealing 810 and / or the inner groove 835a, 835b, 835c can be in the outer composure 813 of the inner shaft sealing 810. Typically, the inner groove 835a, 835b, 835c can be in the inside of the outer shaft 7 and in the inner shaft sealing 810.

[0123] Each passage through the outer shaft 7 typically comprises an outer groove 833a, 833b, 833c. The outer groove 833a, 833b, 833c is in the outside of the outer shaft 7. Alternatively, the outer groove 833a, 833b, 833c can be in the outer shaft sealing 820 and / or the outer groove 833a, 833b, 833c can be in the inner composure 821 of the outer shaft sealing 820. Typically, the outer groove 833a, 833b, 833c can be in the outside of the outer shaft 7 and in the outer shaft sealing 820.

[0124] Each passage through the outer shaft 7 comprises a plurality of channels 831a, 83 lb, 831c through the outer shaft 7 fluidly connecting one of the inner shaft seal chambers 817a, 817b, 817c and one of the outer shaft seal chambers 827a, 827b, 827c.

[0125] A proximate chamber system comprises the outer shaft seal chamber 827a, the inner shaft seal chamber 817a, the outer groove 833a, the inner groove 835a and the channel 831a.

[0126] An intermediate chamber system comprises the outer shaft seal chamber 827b, the inner shaft seal chamber 817b, the outer groove 833b, the inner groove 835b and the channel 831b.

[0127] A distant chamber system comprises the outer shaft seal chamber 827c, the inner shaft seal chamber 817c, the outer groove 833c, the inner groove 835c and the channel 831c.

[0128] Each chamber system of the plurality of chamber systems can be fluidly connected to a reservoir. Each fluid connection comprises a supply groove 843 in the sealing housing 801 and / or each fluid connection comprises a supply groove 843 in the outer shaft sealing 820 and / or each fluid connection comprises a supply groove 843 in the outer composure 823 of the outer shaft sealing 820. At least two (only one is shown) supply channels 841 fluidly connect the chamber system and the reservoir. Particularly, each supply channel 841 fluidly connects the supply groove 843 and the reservoir.

[0129] In FIG 3 the proximate chamber system is connected to an oil reservoir (not shown) by the supply groove 843 and at least two (only one is shown) supply channels 841.

[0130] The intermediate chamber system can be connected to an air reservoir, particularly a pressurized air reservoir, by a supply groove and at least one supply channels (not shown).

[0131] The inner shaft sealing 810 typically seals further inner shaft seal chambers 817d, 817e. The outer shaft sealing 820 typically seals further outer shaft seal chambers 827d, 827e. In some embodiments, the further inner shaft seal chambers 817d, 817e and the further outer shaft seal chambers 827d, 827e are not fluidly connected.

[0132] The marine propulsion unit, particularly the azimuthing propulsion unit, comprises an inner bearing 12 and an outer bearing 11. The inner bearing 12 can be a DE inner bearing 12. The outer bearing 11 can be a DE outer bearing 12. The inner bearing 12 is arrange inside an inner bearing chamber 851 between the inner shaft 8 and the outer shaft 7. The outer bearing 11 is arranged inside an outer bearing chamber 853 between the outershaft 7 and the bearing housing 803. The inner bearing chamber 851 and the outer bearing chamber 853 are fluidly connected by a bearing channel 859.

[0133] A hatch 860 is provided inside the outer shaft 7. The hatch 860 can provide access to the inside of the outer shaft 7.

[0134] FIG 4 schematically illustrates a method for servicing a sealing unit inside a marine propulsion unit, particularly an azimuthing propulsion unit. The method comprises: providing 891 a service sealing; dismounting 892, at least partially, an inner bearing 12; dismounting 893, at least partially, an inner shaft sealing 810; servicing 894 the inner shaft sealing 810; mounting 895 the serviced inner shaft sealing 810; and mounting 896 the inner bearing 12. The service sealing can seal the inner shaft sealing 810 and the outer shaft sealing 820 from the outside of the marine vessel, particularly the pod 30. The inner bearing 12 between the inner shaft 8 and the outer shaft 7 can be dismounted 891 through a hatch 860 provided in the outer shaft 7. The inner shaft sealing 810 can be dismounted 893, at least partially, through the hatch 860. The serviced inner shaft sealing 810 can be mounted 895 through the hatch 860. The inner bearing 12 can be mounted 896 through the hatch 860.

Claims

CLAIMS1. A sealing unit for a marine propulsion unit, the marine propulsion unit comprising a rotatable inner shaft (8) and a rotatable outer shaft (7), wherein the inner shaft (8) runs at least partially within the outer shaft (7) and wherein the outer shaft (7) runs at least partially within a sealing housing (801) of a marine vessel,the sealing unit comprising:- a plurality of chamber systems, wherein each chamber system comprises an inner shaft seal chamber (817a, 817b, 817c), an outer shaft seal chamber (827a, 827b, 827c) and a passage through the outer shaft fluidly connecting the inner shaft seal chamber (817a, 817b, 817c) and the outer shaft seal chamber (827a, 827b, 827c); - an inner shaft sealing (810) between the inner shaft (8) and the outer shaft (7), wherein the inner shaft sealing (810) seals the inner shaft seal chambers (817a, 817b, 817c) of the plurality of chamber systems; and- an outer shaft sealing (820) between the outer shaft (7) and the sealing housing (801), wherein the outer shaft sealing (820) seals the outer shaft seal chambers (827a, 827b, 827c) of the plurality of chamber systems.

2. A sealing unit according to claim 1, wherein the inner shaft sealing (810) seals an inside of the outer shaft (7) from an outside of the marine vessel; and / or wherein the outer shaft sealing (820) seals an inside of the marine vessel from the outside of the marine vessel.

3. A sealing unit according to any previous claim,- wherein the inner shaft sealing (810) comprises an inner composure (811), an outer composure (813) and a plurality of inner sealing elements (815); and / or- wherein the outer shaft sealing (820) comprises an inner composure (821), an outer composure (823) and a plurality of outer sealing elements (825).

4. A sealing unit according to any previous claim, wherein at least one passage through the outer shaft (7) comprises an inner groove (835a, 835b, 835c), and wherein the inner groove (835a, 835b, 835c) typically is in at least one of: the inside of the outer shaft (7); and / or the inner shaft sealing (810).

5. A sealing unit according to any previous claim, wherein at least one passage through the outer shaft (7) comprises an outer groove (833a, 833b, 833c), and wherein the outer groove (833 a, 833b, 833 c) typically is in at least one of: the outside of the outer shaft (7); and / or the outer shaft sealing (820).

6. A sealing unit according to any previous claim, wherein at least one passage through the outer shaft (7) comprises a plurality of channels (831a, 83 lb, 831c) through the outer shaft (7) fluidly connecting the inner shaft seal chamber (817a, 817b, 817c) and the outer shaft seal chamber (827a, 827b, 827c).

7. A sealing unit according any previous claim, wherein the plurality of chamber systems comprises:- a proximate chamber system, wherein the proximate chamber system is fluidly connected to an oil reservoir;- a distant chamber system; and- an intermediate chamber system, wherein the intermediate chamber system is fluidly connected to an air reservoir.

8. A sealing unit according to any previous claim, wherein each chamber system of the plurality of chamber systems contains at least one of:- oil;- air; and / or- leakage fluid.

9. A sealing unit according to any previous claim, wherein each fluid connection of a chamber system of the plurality of chamber systems to a reservoir comprises:- a supply groove (843) in at least one of: the sealing housing (801); and the outer shaft sealing (820).

10. A sealing unit according to any previous claim, wherein each fluid connection of a chamber system of the plurality of chamber systems to a reservoir comprises:- at least one supply channels (841) fluidly connecting the chamber system and the reservoir.

11. A sealing unit according to any previous claim, the propulsion unit further comprising:- an inner bearing (12) inside an inner bearing chamber (851) between the inner shaft (8) and the outer shaft (7); and- an outer bearing (11) inside an outer bearing (853) chamber between the outer shaft (7) and a bearing housing (803);the sealing unit further comprising:- an inner bearing sealing (855), wherein the inner bearing sealing (855) seals the inside of the marine vessel from the inner bearing chamber (851);- an outer bearing sealing (857), wherein the outer bearing sealing (857) seals the inside of the marine vessel from the outer bearing chamber (853).

12. A sealing unit according to the previous claim, wherein the inner bearing chamber (851) and the outer bearing chamber (853) are fluidly connected.

13. A sealing unit according to any of the two previous claims,- wherein the inner shaft sealing (810) seals the outside of the marine vessel from the inner bearing chamber (851); and / or- wherein the outer shaft sealing (820) seals the outside of the marine vessel from the outer bearing chamber (853).

14. A method for servicing a sealing unit, typically for servicing a sealing unit according to any of claims 1 to 13, in a marine propulsion unit, the propulsion unit comprising a rotatable inner shaft (8) and a rotatable outer shaft (7), wherein the inner shaft (8) runs at least partially within the outer shaft (7) and wherein the outer shaft (7) runs at least partially within a sealing housing (801) of a marine vessel, the method comprising:- providing (891) a service sealing arrangement, wherein the service sealing arrangement seals the inner shaft sealing (810) from the outside of the marine vessel;dismounting (892), at least partially, through a hatch (860) provided in the outer shaft (7), an inner bearing (12) between the inner shaft (8) and the outer shaft (7); dismounting (893), at least partially, the inner shaft sealing (810) through the hatch(860);- servicing (894) the inner shaft sealing (810);- mounting (895) the serviced inner shaft sealing (810) through the hatch (860); and - mounting (896) the inner bearing (12) through the hatch (860).

15. A method according to the previous claim, wherein the service sealing arrangement seals the outer shaft sealing (820) from the outside of the marine vessel;the method further comprising:- dismounting, at least partially, an outer bearing (11) between the outer shaft (7) and a bearing housing (803);- dismounting, at least partially, the outer shaft sealing (820);- servicing the outer shaft sealing (820);- mounting the serviced outer shaft sealing (820); and- mounting the outer bearing (11).

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