MARINE PROPELLER

Abstract

Marine propeller for a propulsion system of a ship, which propeller comprises a plurality of detachable blades, and which propeller is configured to be fixed to a propeller shaft of a propulsion system of a ship, wherein the detachable blades forming the propeller are configured to be fixed to the end surface of the propeller shaft or of a flange formed at the end of the propeller shaft. The invention also relates to a marine propulsion system and to a ship utilizing this kind of marine propeller.

Description

The present invention relates to a marine propeller used in the propulsion system of a ship. More precisely the invention relates to the structure of this kind propeller and to a marine propulsion system utilizing this kind of a propeller.

The propulsion systems of ships typically in general level comprise one or more engines or motors providing rotational movement and torque, one or more propeller shafts for transferring the rotational movement and torque from the one or more engines to one or more marine propellers, and marine propellers for transferring the rotational movement and torque to thrust for the ship.

The marine propellers used in ships comprise typically a propeller hub to which the blades of the propeller are fixed, and via which propeller hub the propeller is fixed to the propeller shaft.

The marine propellers can be manufactured as a single piece, i.e. by casting, wherein the hub and blades of the propeller form a solid propeller. This kind of propellers are also called monobloc propellers. Alternatively, the marine propellers can be manufactured in pieces, typically the hub and the individual blades as separate pieces, wherein the blades are fixed to the hub typically with bolts and studs to form an assembled propeller.

Monobloc propellers are generally used, but the larger ship propellers cannot be cast in a single casting due to the size of the propeller in relation to the size of the available casting equipment, which generally leads to the use of assembled propeller. Further advantage of the assembled propellers is that individual blades can be changed without removing and changing of the whole propeller when the blades get damaged, which makes them preferable for example for ice-going vessels. This makes the repairing process of the propeller easier and can often be carried out without drydocking the ship.

The power of engines used in propulsion systems of ships have been continuously increasing, which have caused the strength requirements of the marine propellers to increase correspondingly. This has caused the weight of marine propellers to increase. The increased weight of propellers causes increased structural demands and restrictions for the rest of the propulsion system, such as for the diameter of the propeller shaft and for the placement of bearings. Further, the increase of material used in the manufacturing of the propellers also increases the manufacturing, installation, and transportation requirements of the propellers, as well as increases the cost of the propellers.

In order to overcome the above problems with the prior art assembled propellers, the present invention provides a novel ship propeller, which propeller does not comprise a hub. This allows significant weight savings for the propeller of the invention in comparison to the prior art propellers, thus deceasing the related structural requirements of the propulsion system of the ship and cost of the propeller itself. Further, the propeller of the invention typically comprises less parts than the prior art assembled propellers, which makes it easier to manufacture.

The marine propeller of the invention for a propulsion system of a ship comprises a plurality of detachable blades, and is configured to be fixed to a propeller shaft of a propulsion system of a ship, wherein the detachable blades forming the propeller are configured to be fixed to the end surface of the propeller shaft or of a flange formed at the end of the propeller shaft.

This allows the hub part of the propeller to be removed from the construction of the propeller of the invention, which provides significant weight, and related cost, savings.

In the present invention the blades of the propeller are connected to the propeller shaft preferably directly, which means that the fixing means, such as bolts and preferably also studs for example, extend to the material of the propeller shaft.

In the context of the present invention a ship preferably means a marine vessel of a suitable size to properly allow the utilization of the advantages obtained with the present invention. In practice this means that the ship typically has a length of 24 m or more.

The propeller of the invention is preferably a large marine propeller in order to properly allow the utilization of the advantages obtained with the present invention. In practice this means that the diameter of the propeller is 2 m or more, preferably 3 m or more. The material of the propeller is preferably metal, such as bronze or stainless steel for example, but other metal materials may also be used.

In an embodiment of a marine propeller of the invention the propeller comprises a cap connected to the detachable blades of the propeller. This cap allows additional structural support for the blades and for the whole propeller at the side away from the propeller shaft.

In an embodiment of a marine propeller of the invention number of detachable blades is three or more. Preferably the number of detachable blades in a propeller is four, but the number of detachable blades may also be three, five or six.

In an embodiment of a marine propeller of the invention the detachable blades are fixed to the shaft with a fixing system comprising bolts and preferably also studs. This allows the separate blades to be replaced and repaired easily when the need arises without drydocking the ship and without disassembling the whole propeller.

The present invention also provides a marine propulsion system for providing propulsion for a ship, which propulsion system comprises at least one engine or motor, a propeller, and a propeller shaft for conveying the rotational power from the at least one engine to the propeller, wherein the propeller is a marine propeller of the invention as defined above.

The engine or motor in the propulsion system of the present invention may be any suitable device, system and/or arrangement providing rotative motion and torque for the propeller via the propeller shaft. Examples of these include combustion engine, electrical engine, and turbine.

In addition to the traditional propulsion systems, wherein the propulsion system is located inside the hull of a ships, with the exception of the propeller and part of the propeller shaft, the propulsion system of the invention may also be implemented as a pod-type construction, wherein the propulsion system is located, completely or partially, in a separate pod that can be rotated in relation to the hull of the ship.

In an embodiment of a marine propulsion system of the invention the system may typically comprises a rope guard.

The present invention also provides a ship that comprises a marine propeller according to the invention and/or a marine propulsion system according to the invention. The ship of the invention is preferably an ice class ship, i.e. ship designed to travel in at least some thickness of ice, such as an icebreaker, a Polar Class ship, or an Arctic Class ship for example, wherein the construction of the propeller allows easy repairing of damaged blades. Alternatively, the ship of the invention may be an open-water ship wherein the construction of the propeller of the invention allows manufacture of very large propellers.

More precisely the features defining a marine propeller in accordance with the present invention are presented in claim 1, the features defining a marine propulsion system in accordance with the present invention are presented in claim 5, and the features defining a ship according to the present invention are presented in claim 7. Dependent claims present advantageous features and embodiments of the invention.

Exemplifying embodiments of the invention and their advantages are explained in greater detail below in the sense of example and with reference to accompanying drawings, where

FIG. 1 shows schematically a prior art marine propeller,

FIGS. 2A and 2B show schematically an embodiment of a marine propeller of the invention,

FIGS. 3A-3D show schematically alternative embodiments of the present invention,

FIG. 4 shows schematically an embodiment of the present invention as exploded view, and

FIG. 5 shows schematically an embodiment of a ship utilizing the present invention.

The prior art marine propeller 1 shown in FIG. 1 as a cross-sectional view comprises a plurality of separate blades 2 comprising a fixing portion 2a via which fixing portion the blades are fixed to a propeller hub 3 with bolts. The propeller 1 is fixed to a propeller shaft 4 in with bolts extending through a flange 5 formed at or attached to the end of the propeller shaft and to the hub 3.

In the embodiment of FIG. 1, the propeller 1 also comprises a propeller cap 6 fixed at the opposite end of the propeller in relation to the attachment to the propeller shaft 4, to cover the hollow portion of the propeller hub 3.

FIGS. 2A and 2B show an embodiment of the propeller 10 of the invention, which comprises a plurality, four in this embodiment as can be seen from FIG. 2B, of separate blades 2 comprising a fixing portion 2a.

In this embodiment the blades 2 forming the propeller 10 are connected directly to a flange 5 formed at the end of the propeller shaft 4 via their fixing portions 2a with bolts. At the opposite end of the propeller 10 in relation to the flange 5 of the propeller shaft 4, to the fixing portions 2a of the blades 2 are fixed a propeller cap 6. The propeller cap 6 in this embodiment provides further structural support for the blades 2 of the propeller 10.

FIG. 2B illustrates the fixing of the fixing portions 2a of the blades 2 to the flange 5 and/or to the propeller cap 6. In this embodiment four blades 2 are fixed via their fixing portions 2a to the flange 5 and to the cap 6 with bolts and studs for forming the propeller 10.

FIGS. 3A-3D show alternative embodiments of the propeller 10 of the invention attached to the propeller shaft 4 as cross-sectional views.

In the embodiment of FIG. 3A the blades 2 of the propeller 10 are formed so that their fixing portions 2a comprise sections extending radially in relation to the center axis of the propeller shaft 4. These sections of the fixing portions 2a of the blades 2 area for the fixing bolts and holes via which the blades can be attached to the end surface of the flange 5 formed at the end of the propeller shaft 4. This formation of propeller 10 from the blades 2 in this embodiment also creates a hollow area 8 inside the propeller, which hollow area is closed with a cap part 6, which also provides structural strength for the propeller and its blades.

In the embodiment of FIG. 3B the blades 2 forming the propeller 10 are fixed via first end of their fixing portions 2a on the end surface of the flange 5 formed at the end of the propeller shaft 4. In the opposite end and at the end surfaces of the fixing portions 2a of the blades 2 in relation to the flange 5 is fixed a cap part 6 closing the hollow area 8 inside the propeller 10. In this embodiment the fixing portions 2a of the blades 2 extend at an angle in the longitudinal direction of the propeller shaft 4 so that the diameter formed by the fixing portions 2a is greater at the flange 5 than at the cap part 6.

The embodiment of FIG. 3C corresponds substantially to the embodiment of FIG. 3B, but in this embodiment the fixing portions 2a of the blades 2 extend at an angle in the longitudinal direction of the propeller shaft 4 so that the diameter formed by the fixing portions 2a is smaller at the flange 5 than at the cap part 6.

FIG. 3D shows an embodiment, there the outer surface of the fixing portions 2a of the blades 2 forming the propeller 10 are formed curved.

FIG. 4, schematically showing an embodiment of the present invention as an exploded view, further illustrates the construction of the propeller 10 of the invention.

In the embodiment of FIG. 4 four blades 2 via their fixing portions 2a are connected to the end surface of the flange 5 formed at the propeller shaft 4 with bolts 11 and studs 14. This embodiment also substantially corresponds to the embodiment shown in FIG. 2A.

At the opposite end of the fixing portions 2 in relation to the flange 5 is fixed a cap part 6 with bolts 12 and studs 13. The cap part 6 gives further support for the blades 2 of the propeller 10 and also encloses the open space 8 inside the propeller.

FIG. 5 shows schematically a ship 20 into which the propeller 10 and propulsion system of the present invention can preferably be applied. The ship 20 is in this embodiment an icebreaker.

In relation of the propeller 10 of the invention it is to be noted that the propeller may be located at the stern of the ship 20, as shown in FIG. 5, or the propeller may be located at the bow of the ship, or in the steering propeller of the ship. Further, the propeller 20 of the invention may be an open propeller, as shown in FIG. 5, or a ducted propeller.

The specific exemplifying embodiments of the invention shown in the figures and discussed above should not be construed as limiting. A person skilled in the art can amend and modify the embodiments described in many evident ways within the scope of the attached claims. Thus, the invention is not limited merely to the embodiments described.

Claims

1. A marine propeller for a propulsion system of a ship, which propeller comprises a plurality of detachable blades, and which propeller is configured to be fixed to a propeller shaft of a propulsion system of a ship, wherein the detachable blades forming the propeller are configured to be fixed to an end surface of the propeller shaft or of a flange formed at the end of the propeller shaft.

2. The marine propeller of claim 1, wherein the propeller comprises a cap connected to the detachable blades of the propeller.

3. The marine propeller of claim 1, wherein the number of detachable blades is three or more.

4. The marine propeller of claim 1, wherein the detachable blades are fixed to the propeller shaft with a fixing system comprising bolts.

5. A marine propulsion system for providing propulsion for a ship, which propulsion system comprises at least one engine or motor, a propeller, and a propeller shaft for conveying rotational power from the at least one engine to the propeller, wherein the propeller is a marine propeller according to claim 1.

6. The marine propulsion system of claim 5, wherein the system comprises a rope guard.

7. A ship comprising a marine ship propeller according to claim 1.

8. A ship comprising a marine propulsion system of claim 5.

9. The marine propeller of claim 4, wherein the fixing system additionally comprises studs.