WO2022233810A1 - Marine drive assembly with counterrotating propellers - Google Patents

Marine drive assembly with counterrotating propellers Download PDF

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Publication number
WO2022233810A1
WO2022233810A1 PCT/EP2022/061750 EP2022061750W WO2022233810A1 WO 2022233810 A1 WO2022233810 A1 WO 2022233810A1 EP 2022061750 W EP2022061750 W EP 2022061750W WO 2022233810 A1 WO2022233810 A1 WO 2022233810A1
Authority
WO
WIPO (PCT)
Prior art keywords
propeller
propeller shaft
shaft
drive assembly
marine drive
Prior art date
Application number
PCT/EP2022/061750
Other languages
French (fr)
Inventor
Cristian SACCUMAN
Original Assignee
Zf Friedrichshafen Ag
ZF PADOVA Srl.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Zf Friedrichshafen Ag, ZF PADOVA Srl. filed Critical Zf Friedrichshafen Ag
Publication of WO2022233810A1 publication Critical patent/WO2022233810A1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63H—MARINE PROPULSION OR STEERING
    • B63H5/00—Arrangements on vessels of propulsion elements directly acting on water
    • B63H5/07—Arrangements on vessels of propulsion elements directly acting on water of propellers
    • B63H5/08—Arrangements on vessels of propulsion elements directly acting on water of propellers of more than one propeller
    • B63H5/10—Arrangements on vessels of propulsion elements directly acting on water of propellers of more than one propeller of coaxial type, e.g. of counter-rotative type
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63H—MARINE PROPULSION OR STEERING
    • B63H5/00—Arrangements on vessels of propulsion elements directly acting on water
    • B63H5/07—Arrangements on vessels of propulsion elements directly acting on water of propellers
    • B63H5/08—Arrangements on vessels of propulsion elements directly acting on water of propellers of more than one propeller
    • B63H5/10—Arrangements on vessels of propulsion elements directly acting on water of propellers of more than one propeller of coaxial type, e.g. of counter-rotative type
    • B63H2005/106—Arrangements on vessels of propulsion elements directly acting on water of propellers of more than one propeller of coaxial type, e.g. of counter-rotative type with drive shafts of second or further propellers co-axially passing through hub of first propeller, e.g. counter-rotating tandem propellers with co-axial drive shafts

Definitions

  • the present invention relates to a marine drive assembly with counterrotating propel lers and to a POD drive with such an assembly.
  • the purpose of the present invention is to provide a marine drive assembly with counter-rotating propellers which requires low production effort and costs and still has a long lifetime.
  • the present invention provides a marine drive assembly comprising a housing with a bore.
  • a hollow outer propeller shaft is supported inside said bore, for example by roller bearings or needle bearings.
  • the hollow outer propeller shaft is positioned over an inner propeller shaft.
  • the inner propeller shaft is rotatably mounted inside the hol low outer propeller shaft, preferably by means of roller or needle bearings, as well.
  • the inner propeller shaft supports a first propeller and the hollow outer propeller shaft supports a second propeller. Hence, each one propeller is fixed to a trailing end of the corresponding propeller shaft.
  • the two propellers are arranged coaxially one after the other on a common rotation axis.
  • the inner propeller shaft and the hol low outer propeller shaft are arranged to be driven in opposite rotational directions, which means that the two propellers are rotating also in opposite directions as so- called counterrotating propellers.
  • the hermetic sealing of the hollow outer propeller shaft and the inner propeller shaft allows the use of one-piece propeller shafts.
  • the reason for this is, that the contact with water considerably shortens the lifetime of propeller shafts which are made of non-stainless metals, like carbon steel.
  • ambient water will be trapped between the hub and the propeller shaft and tends to cause corrosion, especially when the water concerned is salt water.
  • the part of a propeller shaft which is in contact with water is made of stainless steel, while the part of the propeller shaft which is not in contact with water is made of carbon steel. Obviously, it is too expen sive to produce the whole propeller shafts with stainless steel material.
  • both propeller shafts are protected against the corrosive influence of the water by simple means.
  • Both propeller shafts can be produced from one single raw part and each of the propeller shafts can be made of only one material which does not need to be stainless material.
  • Advanta geously both propeller shafts can be made completely of carbon steel. Hence the production of such propeller shafts is considerably easier and cheaper than the two- piece propeller shafts which are know from prior art.
  • Said sealing elements may comprise a sealing sleeve which can be arranged to seal a trailing end of the hollow outer propeller shaft off from water.
  • the sealing sleeve can be fixed to the propeller hub of the second propeller and rotate with the second propeller.
  • the sealing sleeve can be formed and arranged to cover the trailing end of the hollow outer propeller shaft.
  • the sealing sleeve can be positioned in a space in side the hub of the first and/or the hub of the second propeller. Such a space is usu ally filled with water when the corresponding boat lies in the water.
  • the hubs of the propellers usually have a streamlined form at the outside and encase the correspond ing parts of the propeller shafts.
  • the sealing sleeve can be encased by a hub of the first or second propeller, thereby the sealing sleeve is protected from strong water currents and collisions with solid particles in the water outside the propeller hub.
  • the sealing sleeve can be made of plastic material. There are plastic materials known which have excellent durability in water and can be easily produced in differ ent forms, as required for different marine drives.
  • the sealing sleeve supports a first contact sealing ring in order to seal off the tubular space between the inner propeller shaft and the hollow outer propeller shaft.
  • a contact surface of the first contact sealing ring can be in con tact with a machined surface of the hollow outer propeller shaft or of a part fixed to the hollow outer propeller shaft.
  • a second contact sealing ring can be positioned adjacent to the first contact sealing ring.
  • the first and the second contact sealing rings can be standard type radial shaft seals, as for example a lip seal.
  • the first and second contact sealing rings provide a watertight and reliable sealing of the tubular space between the inner propeller shaft and the hollow outer propeller shaft.
  • the second contact sealing ring can be mounted with its sealing lip in the opposite direction to the sealing lip of the first contact sealing ring.
  • a contactless sealing assembly can be mounted to the water side of the first and/or second contact sealing ring, to protect the contact sealing ring from debris in the water which otherwise could cause damage to the contact sealing ring.
  • the first propeller can be mounted to the inner propeller shaft by means of a first shaft-hub-connection and the second propeller can be mounted to the hollow outer propeller shaft by means of a second shaft-hub-connection, so that both propellers are rotationally fixed to the corresponding propeller shaft.
  • At least each one flexible sealing ring can be arranged to seal off the first and the second shaft-hub-connection from the ambient water.
  • Preferably each one flexible sealing ring is positioned at each axial end of the corresponding propeller hub to seal off the water from the corre sponding shaft-hub-connection.
  • both shaft-hub-connections can be imple mented in the form of splined shaft connections.
  • a hub cap can be fixed to the trailing end of the inner propeller shaft.
  • the hub cap can be attached re- leasably to the trailing end of the inner propeller shaft.
  • the hub cap can be fixed to the trailing end of the inner propeller shaft by one single fixing screw.
  • a cylin drical surface or a conical surface of the hub cap can fit inside a centering bore in the hub of the first propeller, to provide a reliable waterproof sealing of the whole marine drive assembly.
  • a flexible sealing ring can be positioned between the cylindrical surface and the centering bore.
  • Fig. 1 shows a marine drive assembly according to the present invention in a sectional view.
  • a marine drive assembly 1 as shown in Fig. 1 comprises a hous ing 2 with a bore 3.
  • Said housing 2 is part of an underwater unit of a so-called POD- drive.
  • the underwater unit can be pivoted about a vertical axis to change the steering direction of the marine drive thereby steering the boat.
  • the bore 3 is a stepped bore with several different inner diameters. Inside said bore 3 a hollow outer propeller shaft 6 is positioned over an inner propeller shaft 4.
  • the inner propeller shaft 4 is supported by a first needle bearing 11 which is located inside the outer propeller shaft 6 near the trailing end 12 of the outer propeller shaft 6.
  • the inner propeller shaft 4 supports a first propeller 5.
  • the first propeller 5 is mounted to a trailing end 19 of the inner propeller shaft 4 by means of a first shaft- hub-connection 13 in the form of a splined shaft.
  • the first shaft-hub-connection 13 connects the inner propeller shaft 4 to a propeller hub 24 of the first propeller 5.
  • the hollow outer propeller shaft 6 is supported by a second needle bearing 25 inside the bore 3.
  • the hollow outer propeller shaft 6 supports a second propeller 7.
  • the sec ond propeller 7 is mounted to a trailing end 12 of the hollow outer propeller shaft 6 by means of a second shaft-hub-connection 29 in the form of a splined shaft.
  • the sec ond shaft-hub-connection 29 connects the hollow outer propeller shaft 6 to a propel ler hub 28 of the second propeller 7.
  • the hollow outer propeller shaft 6 and the inner propeller shaft 4 are each produced as a one-piece carbon steel part.
  • the housing 2 can be a part of a multi-part underwater unit of a POD-drive.
  • Such an underwater unit of a POD-drive can be rotated around a vertical axis, in order to change the direction of the thrust caused by the rotating propellers 5, 7 in the water.
  • the inner propeller shaft 4 and the hollow outer propeller shaft 6 are arranged to be driven in opposite rotational directions. Both propeller shafts 4 and 6 can be drivingly connected to an engine of the marine drive.
  • a sealing sleeve 8 is arranged inside a hollow space 30 formed by the propeller hub 24 of the first propeller 5 and the propeller hub 28 of the second propeller 7.
  • the sealing sleeve 8 seals the trailing end 12 of the hollow outer propeller shaft 6 off from water which is trapped inside the hollow space 30. Water is entering the hollow space 30 through a gap 31 between the propeller hub 24 of the first propeller 5 and the propel ler hub 28 of the second propeller 7.
  • sealing sleeve 8 is fixed to the propeller hub 28 of the second pro peller 7 by fixing screws 36.
  • This end of the sealing sleeve 8 comprises a sealing ring 35 which is positioned at a mounting surface of the sealing sleeve 8 which extends in radial direction.
  • the sealing ring 35 ensures the watertight sealing between the seal ing sleeve 8 and the propeller hub 28 of the second propeller 7.
  • the opposite end of the sealing sleeve 8 in axial direction supports a first contact sealing ring 9.
  • a contact surface 14 of the first contact sealing ring 9 is in contact with a machined surface 15 of a first mounting bushing 17 which is fixed to the inner propeller shaft 4.
  • the first contact sealing ring 9 is a typical radial seal ring with an elastic lip containing the con tact surface 14 which is permanently pressed to the machined surface 15.
  • the first mounting bushing 17 is used to axially fix the first needle bearing 11 onto the inner propeller shaft 4.
  • a second mounting bushing 26 is used to axially fix the second needle bearing 25 and a bore sealing assembly 27 inside the bore 3. Additionally, the second mounting bushing 26 provides for a machined surface for two radial shaft seals of the bore sealing assembly 27.
  • Another sealing ring 33 is positioned between the second mounting bushing 26 and the propeller hub 28 of the second propeller 7 to ensure a watertight sealing of this connection. This way the sealing ring 33 serves to avoid any water inside the second shaft-hub-connection 29 between the hollow outer propeller shaft 6 and the propeller hub 28 of the second propeller 7.
  • the disclosed embodiment comprises a contactless sealing assembly 16 positioned beside the first contact sealing ring 9 on its water side.
  • the contactless sealing as sembly 16 allows the water to get in contact and to cool the first contact sealing ring 9 during operation.
  • the contactless sealing assembly 16 protects the first contact sealing ring 9 and especially its elastic sealing lip from debris like solid parti cles in the water, which might damage the sealing lip.
  • a second contact sealing ring 10 is mounted adjacent to the first contact sealing ring 9.
  • the first and the second contact sealing rings 9, 10 are radial shaft seals. They prevent ambient water from entering into the annular clearance between the inner propeller shaft 4 and the hol low outer propeller shaft 6 and also prevent the oil present in said annular clearance from escaping therefrom.
  • a sealing ring 34 is positioned between the first mounting bushing 17 and the propeller hub 24 of the first propeller 5 to ensure a watertight sealing of this con nection. This way the sealing ring 34 serves to avoid any water inside the first splined shaft connection 13 between the inner propeller shaft 4 and the propeller hub 24 of the first propeller 5.
  • the sealing rings 32, 33, 34 and 35 are flexible sealing rings, preferably so-called O-ring seals.
  • a bore sealing assembly 27 is positioned adjacent to the second needle bearing 25 in order to seal the second needle bearing 25 and the inside of the bore 3 off from water.
  • the bore sealing assembly 27 contains two radial shaft seals which seal the annular space between the bore 3 and a second mounting bushing 26.
  • the second mounting bushing 26 is fixed to the hollow outer propeller shaft 6.
  • the second mount ing bushing 26 is used to axially fix the second needle bearing 25 and the bore seal ing assembly 27 inside the bore 3. Additionally, the second mounting bushing 26 pro vides on its outer surface a machined surface for the radial seals of the bore sealing assembly 27.
  • the marine drive assembly comprises a hub cap 18 which is fixed to the trailing end 19 of the inner propeller shaft 4. It seals off the trailing end of the inner propeller shaft 4 from water.
  • the hub cap 18 is fixed to the rear-end, i.e. the trailing end 19 of the in ner propeller shaft 4 by a fixing screw 20.
  • the fixing screw 20 is mounted with a fur ther sealing ring 32, which stops water from entering the annular clearance between the fixing screw 20 and a bore provided for the fixing screw 20 in the hub cap 18.
  • a cylindrical surface 21 of the hub cap 18 fits inside a centering bore 22 in the propeller hub 24 of the first propeller 5. Between the cylindrical surface 21 and the centering bore 22 another flexible sealing ring 23 in the form of an O-ring is positioned.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • Ocean & Marine Engineering (AREA)
  • Sealing Of Bearings (AREA)

Abstract

The present invention relates to a marine drive assembly (1) comprising a housing (2) with a bore (3), an inner propeller shaft (4) to support a first propeller (5) and a hollow outer propeller shaft (6) to support a second propeller (7). The hollow outer propeller shaft (6) is positioned over the inner propeller shaft (4) and supported inside said bore (3). Said inner propeller shaft (4) and the hollow outer propeller shaft (6) are arranged to be driven in opposite rotational directions. Sealing elements (8, 9, 10, 23, 32, 33, 34, 35) are arranged in the marine drive assembly (1) in such a way that the complete hollow outer propeller shaft (6) and the inner propeller shaft (4) are sealed off from water.

Description

Marine drive assembly with counterrotating propellers
The present invention relates to a marine drive assembly with counterrotating propel lers and to a POD drive with such an assembly.
One example of a marine drive with counter-rotating propellers has been disclosed in US 5,249,995 B1. This document describes a marine drive with two counter-rotating surface operating propellers. A first propeller is mounted to an inner propeller shaft and a second propeller is mounted to a hollow outer propeller shaft which is posi tioned over the inner propeller shaft. The inner propeller shaft is arranged to rotate in the opposite rotational direction with respect to the hollow outer propeller shaft. Both propeller shafts are two-piece members, each formed by one carbon steel piece and a stainless steel piece which are welded together.
The purpose of the present invention is to provide a marine drive assembly with counter-rotating propellers which requires low production effort and costs and still has a long lifetime.
This purpose is achieved by a marine drive assembly according to claim 1 . Further embodiments are claimed in dependent claims.
The present invention provides a marine drive assembly comprising a housing with a bore. A hollow outer propeller shaft is supported inside said bore, for example by roller bearings or needle bearings. The hollow outer propeller shaft is positioned over an inner propeller shaft. The inner propeller shaft is rotatably mounted inside the hol low outer propeller shaft, preferably by means of roller or needle bearings, as well.
The inner propeller shaft supports a first propeller and the hollow outer propeller shaft supports a second propeller. Hence, each one propeller is fixed to a trailing end of the corresponding propeller shaft. The two propellers are arranged coaxially one after the other on a common rotation axis. However, the inner propeller shaft and the hol low outer propeller shaft are arranged to be driven in opposite rotational directions, which means that the two propellers are rotating also in opposite directions as so- called counterrotating propellers. According to the current invention there are sealing elements arranged in the marine drive assembly in such a way that the complete hol low outer propeller shaft and the inner propeller shaft are sealed off from water.
The hermetic sealing of the hollow outer propeller shaft and the inner propeller shaft allows the use of one-piece propeller shafts. The reason for this is, that the contact with water considerably shortens the lifetime of propeller shafts which are made of non-stainless metals, like carbon steel. In conventional counterrotating propeller as semblies ambient water will be trapped between the hub and the propeller shaft and tends to cause corrosion, especially when the water concerned is salt water. There fore, in above-mentioned prior art assemblies the part of a propeller shaft which is in contact with water is made of stainless steel, while the part of the propeller shaft which is not in contact with water is made of carbon steel. Obviously, it is too expen sive to produce the whole propeller shafts with stainless steel material. Due to the sealing elements according to the invention, both propeller shafts are protected against the corrosive influence of the water by simple means. Both propeller shafts can be produced from one single raw part and each of the propeller shafts can be made of only one material which does not need to be stainless material. Advanta geously both propeller shafts can be made completely of carbon steel. Hence the production of such propeller shafts is considerably easier and cheaper than the two- piece propeller shafts which are know from prior art.
Said sealing elements may comprise a sealing sleeve which can be arranged to seal a trailing end of the hollow outer propeller shaft off from water. The sealing sleeve can be fixed to the propeller hub of the second propeller and rotate with the second propeller. The sealing sleeve can be formed and arranged to cover the trailing end of the hollow outer propeller shaft. The sealing sleeve can be positioned in a space in side the hub of the first and/or the hub of the second propeller. Such a space is usu ally filled with water when the corresponding boat lies in the water. The hubs of the propellers usually have a streamlined form at the outside and encase the correspond ing parts of the propeller shafts. Hence, the sealing sleeve can be encased by a hub of the first or second propeller, thereby the sealing sleeve is protected from strong water currents and collisions with solid particles in the water outside the propeller hub. The sealing sleeve can be made of plastic material. There are plastic materials known which have excellent durability in water and can be easily produced in differ ent forms, as required for different marine drives.
According to one embodiment the sealing sleeve supports a first contact sealing ring in order to seal off the tubular space between the inner propeller shaft and the hollow outer propeller shaft. A contact surface of the first contact sealing ring can be in con tact with a machined surface of the hollow outer propeller shaft or of a part fixed to the hollow outer propeller shaft. Additionally, a second contact sealing ring can be positioned adjacent to the first contact sealing ring. The first and the second contact sealing rings can be standard type radial shaft seals, as for example a lip seal. The first and second contact sealing rings provide a watertight and reliable sealing of the tubular space between the inner propeller shaft and the hollow outer propeller shaft. The second contact sealing ring can be mounted with its sealing lip in the opposite direction to the sealing lip of the first contact sealing ring. Thus, ensuring a watertight and oil-tight sealing in both directions between the tubular space between the inner and outer propeller shaft and the ambient water, wherein the tubular space can be filled with oil.
In a further embodiment a contactless sealing assembly can be mounted to the water side of the first and/or second contact sealing ring, to protect the contact sealing ring from debris in the water which otherwise could cause damage to the contact sealing ring.
The first propeller can be mounted to the inner propeller shaft by means of a first shaft-hub-connection and the second propeller can be mounted to the hollow outer propeller shaft by means of a second shaft-hub-connection, so that both propellers are rotationally fixed to the corresponding propeller shaft. At least each one flexible sealing ring can be arranged to seal off the first and the second shaft-hub-connection from the ambient water. Preferably each one flexible sealing ring is positioned at each axial end of the corresponding propeller hub to seal off the water from the corre sponding shaft-hub-connection. Preferably both shaft-hub-connections can be imple mented in the form of splined shaft connections. To seal off the trailing end of the inner propeller shaft from water, a hub cap can be fixed to the trailing end of the inner propeller shaft. The hub cap can be attached re- leasably to the trailing end of the inner propeller shaft. Preferably, the hub cap can be fixed to the trailing end of the inner propeller shaft by one single fixing screw. A cylin drical surface or a conical surface of the hub cap can fit inside a centering bore in the hub of the first propeller, to provide a reliable waterproof sealing of the whole marine drive assembly.
Additionally, a flexible sealing ring can be positioned between the cylindrical surface and the centering bore. With such an arrangement the complete hollow outer propel ler shaft and the complete inner propeller shaft are sealed off from water and pro tected from corrosion and mechanical damage.
The invention will be further and more particularly described in the following, by way of example only, and with reference to the accompanying drawing.
Fig. 1 shows a marine drive assembly according to the present invention in a sectional view.
The embodiment of a marine drive assembly 1 as shown in Fig. 1 comprises a hous ing 2 with a bore 3. Said housing 2 is part of an underwater unit of a so-called POD- drive. The underwater unit can be pivoted about a vertical axis to change the steering direction of the marine drive thereby steering the boat. The bore 3 is a stepped bore with several different inner diameters. Inside said bore 3 a hollow outer propeller shaft 6 is positioned over an inner propeller shaft 4.
The inner propeller shaft 4 is supported by a first needle bearing 11 which is located inside the outer propeller shaft 6 near the trailing end 12 of the outer propeller shaft 6. The inner propeller shaft 4 supports a first propeller 5. The first propeller 5 is mounted to a trailing end 19 of the inner propeller shaft 4 by means of a first shaft- hub-connection 13 in the form of a splined shaft. The first shaft-hub-connection 13 connects the inner propeller shaft 4 to a propeller hub 24 of the first propeller 5. The hollow outer propeller shaft 6 is supported by a second needle bearing 25 inside the bore 3. The hollow outer propeller shaft 6 supports a second propeller 7. The sec ond propeller 7 is mounted to a trailing end 12 of the hollow outer propeller shaft 6 by means of a second shaft-hub-connection 29 in the form of a splined shaft. The sec ond shaft-hub-connection 29 connects the hollow outer propeller shaft 6 to a propel ler hub 28 of the second propeller 7. The hollow outer propeller shaft 6 and the inner propeller shaft 4 are each produced as a one-piece carbon steel part.
The housing 2 can be a part of a multi-part underwater unit of a POD-drive. Such an underwater unit of a POD-drive can be rotated around a vertical axis, in order to change the direction of the thrust caused by the rotating propellers 5, 7 in the water.
The inner propeller shaft 4 and the hollow outer propeller shaft 6 are arranged to be driven in opposite rotational directions. Both propeller shafts 4 and 6 can be drivingly connected to an engine of the marine drive.
There are several sealing elements 8, 9, 10, 23, 32, 33, 34, 35 arranged to seal the hollow outer propeller shaft and the inner propeller shaft completely off from water. A sealing sleeve 8 is arranged inside a hollow space 30 formed by the propeller hub 24 of the first propeller 5 and the propeller hub 28 of the second propeller 7. The sealing sleeve 8 seals the trailing end 12 of the hollow outer propeller shaft 6 off from water which is trapped inside the hollow space 30. Water is entering the hollow space 30 through a gap 31 between the propeller hub 24 of the first propeller 5 and the propel ler hub 28 of the second propeller 7.
One end of said sealing sleeve 8 is fixed to the propeller hub 28 of the second pro peller 7 by fixing screws 36. This end of the sealing sleeve 8 comprises a sealing ring 35 which is positioned at a mounting surface of the sealing sleeve 8 which extends in radial direction. The sealing ring 35 ensures the watertight sealing between the seal ing sleeve 8 and the propeller hub 28 of the second propeller 7. The opposite end of the sealing sleeve 8 in axial direction supports a first contact sealing ring 9. A contact surface 14 of the first contact sealing ring 9 is in contact with a machined surface 15 of a first mounting bushing 17 which is fixed to the inner propeller shaft 4. The first contact sealing ring 9 is a typical radial seal ring with an elastic lip containing the con tact surface 14 which is permanently pressed to the machined surface 15. The first mounting bushing 17 is used to axially fix the first needle bearing 11 onto the inner propeller shaft 4.
A second mounting bushing 26 is used to axially fix the second needle bearing 25 and a bore sealing assembly 27 inside the bore 3. Additionally, the second mounting bushing 26 provides for a machined surface for two radial shaft seals of the bore sealing assembly 27. Another sealing ring 33 is positioned between the second mounting bushing 26 and the propeller hub 28 of the second propeller 7 to ensure a watertight sealing of this connection. This way the sealing ring 33 serves to avoid any water inside the second shaft-hub-connection 29 between the hollow outer propeller shaft 6 and the propeller hub 28 of the second propeller 7.
The disclosed embodiment comprises a contactless sealing assembly 16 positioned beside the first contact sealing ring 9 on its water side. The contactless sealing as sembly 16 allows the water to get in contact and to cool the first contact sealing ring 9 during operation. However, the contactless sealing assembly 16 protects the first contact sealing ring 9 and especially its elastic sealing lip from debris like solid parti cles in the water, which might damage the sealing lip. A second contact sealing ring 10 is mounted adjacent to the first contact sealing ring 9. The first and the second contact sealing rings 9, 10 are radial shaft seals. They prevent ambient water from entering into the annular clearance between the inner propeller shaft 4 and the hol low outer propeller shaft 6 and also prevent the oil present in said annular clearance from escaping therefrom.
Yet another sealing ring 34 is positioned between the first mounting bushing 17 and the propeller hub 24 of the first propeller 5 to ensure a watertight sealing of this con nection. This way the sealing ring 34 serves to avoid any water inside the first splined shaft connection 13 between the inner propeller shaft 4 and the propeller hub 24 of the first propeller 5. The sealing rings 32, 33, 34 and 35 are flexible sealing rings, preferably so-called O-ring seals. A bore sealing assembly 27 is positioned adjacent to the second needle bearing 25 in order to seal the second needle bearing 25 and the inside of the bore 3 off from water. The bore sealing assembly 27 contains two radial shaft seals which seal the annular space between the bore 3 and a second mounting bushing 26. The second mounting bushing 26 is fixed to the hollow outer propeller shaft 6. The second mount ing bushing 26 is used to axially fix the second needle bearing 25 and the bore seal ing assembly 27 inside the bore 3. Additionally, the second mounting bushing 26 pro vides on its outer surface a machined surface for the radial seals of the bore sealing assembly 27.
The marine drive assembly comprises a hub cap 18 which is fixed to the trailing end 19 of the inner propeller shaft 4. It seals off the trailing end of the inner propeller shaft 4 from water. The hub cap 18 is fixed to the rear-end, i.e. the trailing end 19 of the in ner propeller shaft 4 by a fixing screw 20. The fixing screw 20 is mounted with a fur ther sealing ring 32, which stops water from entering the annular clearance between the fixing screw 20 and a bore provided for the fixing screw 20 in the hub cap 18. A cylindrical surface 21 of the hub cap 18 fits inside a centering bore 22 in the propeller hub 24 of the first propeller 5. Between the cylindrical surface 21 and the centering bore 22 another flexible sealing ring 23 in the form of an O-ring is positioned.
Referals marine drive assembly housing bore inner propeller shaft first propeller hollow outer propeller shaft second propeller sealing sleeve first contact sealing ring second contact sealing ring first needle bearing trailing end first shaft-hub-connection contact surface machined surface contactless sealing assembly first mounting bushing hub cap trailing end fixing screw cylindrical surface centering bore flexible sealing ring propeller hub second needle bearing second mounting bushing bore sealing assembly propeller hub second shaft-hub-connection hollow space gap sealing ring sealing ring sealing ring sealing ring fixing screw

Claims

Claims
1. Marine drive assembly (1 ) comprising a housing (2) with a bore (3), an inner pro peller shaft (4) to support a first propeller (5) and a hollow outer propeller shaft (6) to support a second propeller (7), wherein the hollow outer propeller shaft (6) is posi tioned over the inner propeller shaft (4) and supported inside said bore (3), and wherein the inner propeller shaft (4) and the hollow outer propeller shaft (6) are ar ranged to be driven in opposite rotational directions, characterized in, that sealing elements (8, 9, 10, 23, 32, 33, 34, 35) are arranged in the marine drive as sembly (1 ) in such a way that the complete hollow outer propeller shaft (6) and the inner propeller shaft (4) are sealed off from water.
2. Marine drive assembly according to claim 1 , wherein a sealing sleeve (8) is ar ranged to seal a trailing end (12) of the hollow outer propeller shaft (6) off from water.
3. Marine drive assembly according to claim 1 or 2, wherein the sealing sleeve (8) is fixed to a propeller hub (28) of the second propeller (7).
4. Marine drive assembly according to claim 3, wherein the sealing sleeve (8) sup ports a first contact sealing ring (9), wherein a contact surface (14) of the first contact sealing ring (9) is in contact with a machined surface (15) of the hollow outer propel ler shaft (6) or of a first mounting bushing (17) arranged on the hollow outer propeller shaft (6).
5. Marine drive assembly according to claim 4, wherein a contactless sealing assem bly (16) is arranged beside the first contact sealing ring (9), in order to protect the first contact sealing ring (9) from debris in the water.
6. Marine drive assembly according to one of the preceding claims, wherein the seal ing sleeve (8) is made of plastic material.
7. Marine drive assembly according to one of the preceding claims, wherein the first propeller (5) is mounted to the inner propeller shaft (4) by means of a first shaft-hub- connection (13), wherein the second propeller (7) is mounted to the hollow outer propeller shaft (6) by means of a second shaft-hub-connection (29), and wherein at least each one flexible sealing ring (23, 33, 34, 35) is arranged to seal off the first and the second shaft-hub-connection (13, 29) from water.
8. Marine drive assembly according to one of the preceding claims, wherein a hub cap (18) is fixed to the trailing end (19) of the inner propeller shaft (4) such as to seal off the inner propeller shaft (4) from water.
9. Marine drive assembly according to claim 8, wherein the hub cap (18) is fixed to the trailing end (19) of the inner propeller shaft (4) by one single fixing screw (20), and wherein a cylindrical surface (21 ) of the hub cap (18) fits inside a centering bore (22) in a propeller hub (24) of the first propeller (5).
10. Marine drive assembly according to one of the preceding claims, wherein the hol low outer propeller shaft (6) and the inner propeller shaft (4) are produced as one- piece carbon steel parts.
PCT/EP2022/061750 2021-05-06 2022-05-03 Marine drive assembly with counterrotating propellers WO2022233810A1 (en)

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DE102021204620.7 2021-05-06

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3580214A (en) * 1969-04-03 1971-05-25 Ernest Muller Marine propeller shafts bearing arrangements
US5249995A (en) 1992-05-27 1993-10-05 Brunswick Corporation Marine drive having two counter-rotating surfacing propellers and dual propeller shaft assembly
WO1995003211A1 (en) * 1993-07-22 1995-02-02 Twin Technology Development B.V. Drive unit for a ship
EP2236408A1 (en) * 2008-01-23 2010-10-06 IHI Marine United Inc. Contra-rotating propeller unit, method for assembly thereof, method for transportation thereof, and method for mounting thereof on mother ship
KR20160008686A (en) * 2014-07-14 2016-01-25 삼성중공업 주식회사 Propulsion apparatus for ship, and ship having the same
EP3715240A1 (en) * 2017-11-20 2020-09-30 Japan Marine United Corporation Shaft sealing device for marine contra-rotating propeller device

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3580214A (en) * 1969-04-03 1971-05-25 Ernest Muller Marine propeller shafts bearing arrangements
US5249995A (en) 1992-05-27 1993-10-05 Brunswick Corporation Marine drive having two counter-rotating surfacing propellers and dual propeller shaft assembly
WO1995003211A1 (en) * 1993-07-22 1995-02-02 Twin Technology Development B.V. Drive unit for a ship
EP2236408A1 (en) * 2008-01-23 2010-10-06 IHI Marine United Inc. Contra-rotating propeller unit, method for assembly thereof, method for transportation thereof, and method for mounting thereof on mother ship
KR20160008686A (en) * 2014-07-14 2016-01-25 삼성중공업 주식회사 Propulsion apparatus for ship, and ship having the same
EP3715240A1 (en) * 2017-11-20 2020-09-30 Japan Marine United Corporation Shaft sealing device for marine contra-rotating propeller device

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