NO343739B1 - Propulsion system with integrated on-shaft electric machine and a method of mounting a second propeller - Google Patents

Propulsion system with integrated on-shaft electric machine and a method of mounting a second propeller Download PDF

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Publication number
NO343739B1
NO343739B1 NO20170368A NO20170368A NO343739B1 NO 343739 B1 NO343739 B1 NO 343739B1 NO 20170368 A NO20170368 A NO 20170368A NO 20170368 A NO20170368 A NO 20170368A NO 343739 B1 NO343739 B1 NO 343739B1
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Norway
Prior art keywords
propeller
central shaft
electric machine
shaft
driven
Prior art date
Application number
NO20170368A
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Norwegian (no)
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NO20170368A1 (en
Inventor
Alexey Matveev
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Rolls Royce Marine As
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Filing date
Publication date
Application filed by Rolls Royce Marine As filed Critical Rolls Royce Marine As
Priority to NO20170368A priority Critical patent/NO343739B1/en
Publication of NO20170368A1 publication Critical patent/NO20170368A1/en
Publication of NO343739B1 publication Critical patent/NO343739B1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63H—MARINE PROPULSION OR STEERING
    • B63H23/00—Transmitting power from propulsion power plant to propulsive elements
    • B63H23/02—Transmitting power from propulsion power plant to propulsive elements with mechanical gearing
    • B63H23/10—Transmitting power from propulsion power plant to propulsive elements with mechanical gearing for transmitting drive from more than one propulsion power unit
    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63H—MARINE PROPULSION OR STEERING
    • B63H23/00—Transmitting power from propulsion power plant to propulsive elements
    • B63H23/02—Transmitting power from propulsion power plant to propulsive elements with mechanical gearing
    • B63H23/06—Transmitting power from propulsion power plant to propulsive elements with mechanical gearing for transmitting drive from a single propulsion power unit
    • B63H2023/062—Transmitting power from propulsion power plant to propulsive elements with mechanical gearing for transmitting drive from a single propulsion power unit comprising means for simultaneously driving two or more main transmitting elements, e.g. drive shafts
    • B63H2023/067—Transmitting power from propulsion power plant to propulsive elements with mechanical gearing for transmitting drive from a single propulsion power unit comprising means for simultaneously driving two or more main transmitting elements, e.g. drive shafts the elements being formed by two or more coaxial shafts, e.g. counter-rotating shafts
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63H—MARINE PROPULSION OR STEERING
    • B63H23/00—Transmitting power from propulsion power plant to propulsive elements
    • B63H23/22—Transmitting power from propulsion power plant to propulsive elements with non-mechanical gearing
    • B63H23/24—Transmitting power from propulsion power plant to propulsive elements with non-mechanical gearing electric
    • B63H2023/245—Transmitting power from propulsion power plant to propulsive elements with non-mechanical gearing electric with two or more electric motors directly acting on a single drive shaft, e.g. plurality of electric rotors mounted on one common shaft, or plurality of electric motors arranged coaxially one behind the other with rotor shafts coupled together

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • Ocean & Marine Engineering (AREA)
  • Motor Power Transmission Devices (AREA)
  • Connection Of Motors, Electrical Generators, Mechanical Devices, And The Like (AREA)
  • Shafts, Cranks, Connecting Bars, And Related Bearings (AREA)

Description

The present invention is related to a propulsion system of a vessel comprising a first and a second propeller arranged axially one after another on a central shaft, wherein the first propeller is fixed to the central shaft and the second propeller is driven by an electric machine mounted on the central shaft.
BACKGROUND ART
The propulsion system of a marine vessel is normally located in after part of the vessel. The propeller is often equipped with a hubcap or cone, which is normally covering the propeller fastening bolt arranged at the end of the propeller shaft. The circulation of water around each forward propeller blade forms a vortex near the hub before they joint to one hub vortex. This hub vortex cavitation can be harmful to the propulsion unit or the rudder behind the main propeller.
Propulsion of ships has traditionally been accomplished by using one or several rotating propellers and steering by making use of rudders in connection with a propeller. Contra rotating propellers (CRP) are known to offer some benefits over conventional single propeller. The load distributed into the blade area of two propellers instead of one, and the rotational energy of the vortex of the first propeller may be more efficiently recovered. It is well known that two propellers arranged on the same shaft can generate propulsive force in the same axial direction while rotating in opposite directions. Propellers can both help each other, or one can collect energy from the other; the second propeller captures spiral motion of the flow after the first propeller and turn it into axial thrust.
It is known that the propeller and the rudder can be integrated into a single system to optimize hydrodynamic efficiency. A special hubcap is fitted to the propeller which streamlines the flow into a bulb that is added to the rudder. This arrangement effectively reduces the flow separation immediately after the propeller. The result is an increase in propeller thrust as previously wasted energy is recovered from the flow. The addition of the bulb on the rudder also streamlines the flow aft of the rudder, further reducing drag.
Rolls Royce has developed a propeller system called Promas. The Promas offers increased propulsive efficiency and improved maneuverability by adapting the propeller and rudder into one propulsive unit. A tapered hubcap fitted into the propeller hub leads the water flow onto a bulb, which forms part of the rudder blade. The rudder has a twisted leading edge, optimized for the flow from the propeller, which converts the swirl energy in the slipstreams (which is normally lost), into additional forward thrust. The result is an increase in propulsive efficiency, leading to reduced fuel consumption and emissions. Still, the Promas has the opportunity for modification and for utilizing of the benefits of contra-rotating propellers (CRP), with increased propulsion efficiency.
The most common solution of providing a CRP system is making use of two concentric shafts, hollow outer shaft and inner shaft inside the outer shaft. The front propeller is connected to the outer shaft and the second rear propeller is connected to the inner shaft, which extends through the first propeller hub. This arrangement requires substantially complicated shafting and gear device, including problems with arranging the sealing’s which would reduce system reliability and increase cost.
Publication WO 2008/147146 A2, discloses a CRP system installed between a rudder horn of a ship and a shaft support at an engine-output side. The system includes a central propeller shaft rotatable supported by the rudder horn and the shaft support, respectively. A front propeller fixed to the propeller shaft, a counter rotating gear set installed on the rudder horn and connected with the propeller shaft, and a rear propeller connected to the counter rotating gear set and disposed between the rudder horn and the front propeller. This arrangement requires substantially complicated shafting and gear device and is not easy transferrable to other existing propulsion systems.
The publication DE 102009030112 A1, discloses a propulsion system for a vessel comprising a first propeller mounted on a central shaft and a second propeller arranged outside the vessel and driven by an electric motor. The electric motor is configured as an external rotor motor with an annular stator and an annular rotor.
The publication US 2014/0127035 A1 discloses a propulsion system with propellers being mounted to two mutually independent drive systems. A hollow outer shaft or cylinder and an inner central shaft inside the outer shaft. Wherein the front propeller is connected to the outer shaft and the rear propeller is connected to the inner shaft.
Thus, there is a need for a CRP propulsion system with increased efficiency and which overcomes the problems mentioned in the prior art. There is also a need for a propulsion system that can reduce fuel consumption and is easy to adapt.
It is an object of the invention to provide a CRP propulsion system for new built and retrofits that have increased propulsive efficiency, with reduced fuel consumption and emissions.
It is also an object of the present invention to provide a CRP propulsion system that can easily adapt to existing propulsion systems in form of retrofit.
It is another object of the present invention to provide a CRP propulsion system that require less complicated mechanical arrangements and are easy to install and remove.
It is another object of the present invention to provide a CRP propulsion system that is reliable and less expensive than traditional CRP systems.
It is yet another object of the present invention to provide a CRP propulsion system that are easy interchangeable and allowing easy access for service and repair.
SUMMARY OF THE INVENTION
The present invention is related to a propulsion system for a water-borne vessel, comprising a first propeller and a second propeller. Which propellers are arranged axially one after another on a central shaft, and which first propeller is driven by the central shaft, and wherein the second propeller is driven by an electric machine mounted on the central shaft.
In the following, the term first propeller is referred to a main propeller of a propulsion system, and the term second propeller is referred to the auxiliary propeller. These terms will be used interchangeably throughout the entire application.
According to the present invention, the central shaft is driven by a motor or an engine situated within the hull of the vessel. Preferably, the main motor for driving the central shaft is a diesel motor or an electric motor or a combination thereof. Most preferably, the main motor is an electric motor.
Further, and within the scope of the invention, the main electric motor can be located outboard of the vessel, in a propulsion body, such as a POD.
According to a preferred embodiment of the present invention, the electric machine of the second propeller comprises a stator mounted on the central shaft and a rotor arranged radially outside the stator. Wherein the second propeller comprises propeller blades mounted on the rotor.
In a preferred embodiment of the present invention, the electric machine of the second propeller is supplied by current through the central shaft. This means that the rotating central shaft may be hollow, allowing power lines from within the vessel hull or a POD, to be passed through to both first and second propellers. For example, the first propeller with power line to pitching, and the second propeller with power lines to the integrated electric machine.
Further, slip rings, bearings and converters for operating the elect ric machine of the second propeller may be placed within the vessel hull or in a body of a POD, allowing easy access for service and repair. The slip rings are attached to and rotates with the central shaft, passing electric current to a circuit via fixed brushes pressing against them.
According to a preferred embodiment of the present invention, the electric machine of the second propeller is an on-shaft permanent magnet (PM) motor with outer rotor.
In another preferred embodiment of the present invention, the first and the second propeller are contra rotating propellers (CRPs). Preferably, the first propeller has a larger propeller diameter than the diameter of the second propeller. Nevertheless, within the scope of the invention, any dimensional-ratio between the propellers are possible
In an embodiment of the present invention, the second propeller is a Vane wheel (Grim vane wheel) situated downstream of the first propeller. According to an embodiment of the invention, the Vane Wheel propeller can run freely without torque on the shaft or be driven by an electric machine mounted on the central shaft.
From background art, we know that two propellers arranged on the same shaft can generate propulsive force in the same axial direction while rotating in opposite directions. The propellers can both help each other, or one can collect energy from the other; the second propeller captures spiral motion of the flow after the first propeller and turns it into axial thrust.
According to the invention, the second propeller with integrated electric machine is a smaller propeller and contribute less than the main propeller.
In certain operational modes, the second propeller can recover energy from the flow and work in braking mode so that the electric machine is operating in generator mode and energy is recuperated to the vessels electric grid.
If both propellers are electrically driven also the first propeller can be used to recuperate energy back to the vessels electric grid.
The propulsion system of the present invention is more redundant than conventional systems. If the main motor fails, the second propeller can still provide, though reduced, thrust.
According to the invention, the second propeller can be retrofitted to existing propeller systems. The second propeller being arranged to be mounted relative to the first propeller, such that the first and second propeller are arranged axially one after another on a central shaft. This flexible arrangement allows single propeller systems to be converted into twin propeller systems with significant improvement in efficiency and increase of thrust force. This appropriate solution according to the present invention enables the second propeller to be removed for replacement with another propeller or removed for service and repair.
According to yet another embodiment of the present invention, the second (auxiliary) propeller can be used for optimizing efficiency of the diesel engine and its fuel consumption by tuning/adjusting rotational speed of the propeller. This is especially promising if the first (main) propeller is a constant-speed propeller, e.g. diesel motor driven.
The second (auxiliary) propeller can also be used for boost in certain operational modes of the vessel. It can also be used for maneuvers if operated coordinated with the rudder.
The present invention is also related to a method of mounting a second propeller to a first propeller on a central shaft, such that the first propeller and the second propeller are arranged axially one after another. Wherein the first propeller is driven by the central shaft.
Which method comprises the steps of:
a) if present, removing a hubcap or cone of the first propeller,
b) if required, adding a shaft extension at the extension of the central shaft, c) adding an integrated electric machine with a stator mounted on the central shaft or to the shaft extension, and a rotor arranged radially outside of the stator,
d) adding a second propeller with propeller blades fixed to the outer rotor of the electric machine,
e) adding electric line in the shaft for supplying current to the on-shaft electric machine.
According to the invention, and depending on the layout of the propulsion system, a hubcap, cone or cover has to be removed (or its length reduced) at the end of the central shaft. In some cases, a shaft extension has to be mounted at the extension of the central shaft, providing necessary space for mounting of a second propeller. The central shaft and the shaft extension has a hollow body allowing cables to be pulled through and allowing power to be supplied to at least one of the propellers.
Preferably, the electric machine of the second propeller is supplied by current through the central shaft, and wherein slip rings, bearings and converter for operating the second electric machine is arranged within the vessels hull or in a body of a POD.
According to the invention, the central shaft is driven by a first (main) diesel or gas engine, electric motor or a combination thereof.
Further, the second propeller is a contra-rotating propeller (CRP).
This expedient embodiment of the present invention, allows a second propeller to be retrofitted to a main propeller, to achieve the benefits of CR propellers. In addition, the second propeller can easily be replaced or removed for maintenance or repair.
BRIEF DESCRIPTION OF THE DRAWINGS
The description above, as well as further objects, features and advantages of the present invention will be more fully appreciated by reference to the following detailed description of the preferred embodiment, which should be read in conjunction with the accompanying drawings in which:
Figure 1 shows a propeller and a rudder integrated into a single system to optimize hydrodynamic efficiency.
Figure 2 shows an embodiment according to the present invention where a second propeller is mounted on a common central shaft as the main propeller.
Figure 3 shows another embodiment according to the present invention, where the second propeller is mounted on the central shaft in line with the main propeller, and wherein an electric motor is the main motor for driving the central shaft.
Figure 4 shows another embodiment according to the present invention, where the second propeller is mounted on the central shaft in line with the main propeller and wherein a diesel or gas engine or motor drives the central shaft.
DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS
Figure 1 shows a first or main propeller 11 and a rudder 13 integrated into a single system to optimize hydrodynamic efficiency. The propulsion system comprising a propeller 11 and a rudder 13. A hubcap 15 is fitted to the aft of the main propeller 11, which streamlines the flow onto a bulb 14 that is added to the rudder 13. The special shape of the hubcap 15 reduces effectively the flow separation immediately after the propeller 11. The result is an increase in propeller 11 thrust and previously wasted energy is recovered from the flow. The addition of the bulb 14 on the rudder 13 also streamlines the flow aft of the rudder 13, further reducing the drag. Further, the main propeller 11 of figure 1 is operated by a central shaft 16. The central shaft 16 is operated by a main motor 32 (shown in figure 3 and 4) situated within the vessel 10 hull. The motor 32 can be a diesel or an electric motor, or a combination thereof, such as “hybrid” system.
Figure 2 shows a preferred embodiment according to the present invention where a second propeller 21 is mounted to the rear end of the central shaft 16. The hubcap 15 (shown in figure 1) is removed and a shaft extension can be mounted at the extension of the central shaft if required. In both figure 1 and figure 2, the central shaft 16 extends beyond the first (main) propeller 11 providing space for mounting the second propeller 21. An integrated electric machine 22 with external rotor 23 is mounted on the central shaft 16. Preferably, the electric machine 22 is a Permanent Magnet (PM) machine. The on-shaft PM machine 22 is supplied by current through the central shaft 16, which has a hollow body for allowing power cables 31 to run through. Slip rings 29 (shown in figure 3 and 4) and converter for operating the PM machine 22 is arranged within the vessel 10. This arrangement is appropriate in terms of service and repair allowing easy access to the different components. The slip ring device 29 allows the transmission of power and electrical signals from a stationary to the rotating center shaft structure.
After mounting the second propeller 21 to the central shaft 16, a special shorter hubcap 15 can be fitted to the end of the central shaft 16 and aft of second propeller 21 for streamlining the flow onto the bulb 14. The second propeller 21 is fixed to the outer rotor 23 of the PM machine 22.
Figure 3 shows a traditional main propeller 11 arranged at the aft part of a vessel 10. A second CR propeller 21 is mounted to the aft part of the first (main) propeller 11 such that the propellers 11, 21 are arranged axially one after another. According to the invention, the second propeller 21 can be retrofitted to the exciting propulsion system. The first propeller 11 is operated by the central shaft 16, which is driven by an electric motor 32 situated within the vessel 10 (inside the vessel hull). The first propeller 11 is fixed-mounted on the central shaft 16 with blade pitching (optional). The interchangeable second propeller 21 is mounted on an integrated electric machine 22, and the propeller blades of the second propeller 21 are mounted on the external rotor 23 of the electric machine 22.
The second propeller 21 is supplied by current through the hollow central shaft 16. This preferable embodiment allows slip rings 29 and converter for operating the electric machine 22 to be located within the vessel (inside the vessel hull) 10 or a POD body. This CRP propulsion system has the benefits using a compact electric machine 22 inside the propeller, and that only part of the propulsion systems power is transferred through slip rings 29. Further advantages are that the slip rings 29 and bearings are inside the hull allows the easy access for service and repair. The figure 3 also shows a first frequency converter 40 driving the main electric motor and a second frequency converter 41 for driving the on-shaft electric machine 22.
Figure 4 shows a propulsion system according to another embodiment of the present invention. The main motor 32 is a diesel motor 32 located in within the vessel 10. The power to the integrated electric machine 22 of the second propeller 21 is supplied through slip rings 29 mounted on the central shaft 16. A frequency converter 41 is arranged for electric supply for driving the on-shaft electric machine 22.
Although preferred embodiments of the invention have been illustrated in the accompanying drawings and in the foregoing detailed description, it will be understood that the invention is not limited to the embodiments disclosed, but is capable of numerous arrangements, modifications, and substitutions of parts and elements.

Claims (10)

1. A propulsion system for a water-borne vessel (10), comprising a first propeller (11) and a second propeller (21), which propellers (11, 21) are arranged axially one after another on a central shaft (16), which first propeller (11) is driven by the central shaft (16),
characterised in that the second propeller (21) is mounted on the central shaft and driven by an electric machine (22), wherein the electric machine (22) comprises a stator (24) mounted on the central shaft (16) and a rotor (23) arranged radially outside of the stator (24), and in that the second propeller (21) comprises propeller blades mounted on the rotor (23).
2. The system according to claim 1,
characterized in that the electric machine (22) is supplied by current through the central shaft (16), and wherein slip rings (29), bearings and converter for operating the electric machine (22) are arranged within the water-borne vessels (10) hull or in a body of a POD.
3. The system according to any one of the preceding claims,
characterized in that the electric machine (22) is an on-shaft Permanent Magnet (PM) machine with outer rotor (23).
4. The system according to any one of the preceding claims,
characterized in that the central shaft (16) in driven by a main electric motor (32).
5. The system according to any one of the preceding claims,
characterized in that the first (11) and the second (21) propeller are contrarotating (CRP) propellers.
6. The system according to any one of the preceding claims,
characterized in that the second propeller (21) can recover energy from a flow created by the first propeller (11), and wherein the second propeller (21) is working in backing mode so that the electric machine (22) is operating in generator mode and energy is recuperated to an electric grid of the vessel (10).
7. The system according to any one of the preceding claims,
characterized in that the second propeller (21) is adapted to be retrofitted on the central shaft 16 on either side of the first propeller (11).
8. A method of mounting a second propeller (21) to a first propeller (11) on a central shaft (16), such that the first and second propeller (11,21) are arranged axially one after another, wherein the first propeller (11) is driven by the central shaft (16), which method comprises the steps of:
- if present, removing a hubcap (15) or cone of the first propeller (11), - if required, adding a shaft extension to the central shaft (16),
- adding an integrated electric machine (22) with a stator (24) mounted on the shaft extension or on the central shaft (16), and a rotor (23) arranged radially outside of the stator (24),
- adding a second propeller (21) with propeller blades fixed to the outer rotor (23) of the electric machine (22),
- if required, adding the hubcap (15) or cover to the second propeller (21), - adding an electrical line (31) for supplying current to the on-shaft electric machine (22).
9. The method according to claim 8, wherein the electric machine (22) is supplied by current through the central shaft (16), and wherein slip rings, bearings and converter for operating the second electric machine (22) is arranged within the vessels (10) hull allowing easy access for service and repair.
10. The method according to claim 8 or 9, wherein the electric machine (22) driving the second propeller (21) is an on-shaft Permanent Magnet (PM) machine (22) with outer rotor (23).
NO20170368A 2017-03-13 2017-03-13 Propulsion system with integrated on-shaft electric machine and a method of mounting a second propeller NO343739B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
NO20170368A NO343739B1 (en) 2017-03-13 2017-03-13 Propulsion system with integrated on-shaft electric machine and a method of mounting a second propeller

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NO20170368A NO343739B1 (en) 2017-03-13 2017-03-13 Propulsion system with integrated on-shaft electric machine and a method of mounting a second propeller

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NO20170368A1 NO20170368A1 (en) 2018-09-14
NO343739B1 true NO343739B1 (en) 2019-05-27

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102009030112A1 (en) * 2009-06-22 2010-12-23 Siemens Aktiengesellschaft Ship with two propellers arranged one behind the other
US20140127035A1 (en) * 2011-03-31 2014-05-08 Samsung Heavy Ind. Co., Ltd. Propulsion device for vessel and vessel having same

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102009030112A1 (en) * 2009-06-22 2010-12-23 Siemens Aktiengesellschaft Ship with two propellers arranged one behind the other
US20140127035A1 (en) * 2011-03-31 2014-05-08 Samsung Heavy Ind. Co., Ltd. Propulsion device for vessel and vessel having same

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Owner name: KONGSBERG MARITIME CM AS, NO

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Owner name: KONGSBERG MARITIME AS, NO