Propeller of pod-type propeller of ship and pod-type propeller including the same

Abstract

The present invention relates to the field of shipbuilding, and more particularly to a propeller for a pod-type propulsion system of a ship, especially an ice-navigating ship, which provides forward and backward movement under icy conditions where ice can be traversed, and also provides steering for the ship, and to a pod-type propulsion system comprising the propeller. In order to reduce the weight of the pod-type propulsion system and thereby reduce its cost, the propeller comprises a propeller hub and propeller blades mounted on the propeller hub, the propeller hub being manufactured so that it can be rigidly attached to a conical tail piece of a propeller shaft, each propeller blade comprising a blade blade and a blade flange made in one piece. The blade blade enters the blade flange via a fillet joint, and the fillet joint forms the weakest part of the blade that may be damaged in the cross section of the blade blade adjacent to the fillet joint. The outer surface of the blade flange has a profile that is bent inwardly toward the propeller axis in its radial cross section to reduce the distance from the cross section of the blade blade to the propeller axis.

Description

Technical Field

[0001] The present invention relates to the field of shipbuilding, and more particularly to a propeller of a ship (especially an ice-navigating ship), which provides forward and backward movement under icy conditions where ice can be traversed, while also providing steering for the ship, and to a pod-type propeller comprising the propeller. Background Art

[0002] A podded propulsion system consists of a movable part (a cabin comprising a pod attached to streamlined legs) located outside the main hull of the vessel and in which a propulsion engine (usually electric) is mounted on bearings. The engine shaft runs directly or through a corresponding gear transmission to serve as a drive shaft for a propulsion propeller (also called a propeller shaft or shaft drive). The propeller is attached to a propeller shaft outside the cabin, usually on the conical tailpiece of the shaft, which serves to convert the engine power into a current that moves the vessel and, during advancement in icing conditions, to break up large blocks of ice (in dual-acting vessels). The above movable part of the podded propulsion system is mounted on the hull of the vessel using a swivel bearing that allows the podded propulsion system to rotate around an axis of rotation, its orientation usually close to vertical, and is combined with a swivel mechanism that provides the necessary torsional force to rotate the movable part of the podded propulsion system around the axis of rotation by the desired angle.

[0003] One of the most famous examples of devices of this type is the pod thruster produced by the Swiss-Swedish ABB Group under the trade name Azipod. This pod thruster is particularly suitable for tourist passenger ships (such as Oasis class), icebreakers (such as Yuri Topchev), dual-acting icebreakers (such as liquefied gas ship Christophe de Margerie), etc.

[0004] When a vessel fitted with a podded propulsion system is used in icing conditions, the movable parts of the podded propulsion system and the propeller are subject to significant ice and hydrodynamic loads which, under normal operating conditions, must not lead to failure or malfunction of the propeller itself or of the podded propulsion system as a whole, whereas if the propeller is subject to extremely high ice loads, any damage to the propeller blades must prevent any failure of other components of the podded propulsion system.

[0005] There is a known sea vessel designed to operate in icy water, comprising a podded propeller (azimuth propeller) with a propeller and a bushing for the propeller (Patent RF 2584038 C2 of May 20, 2016). The bushing is made in the form of a cutter and extends beyond the boundaries of the plane of rotation of the propeller in such a way that if the bushing hits an ice block, it breaks the ice block before the rest of the propeller hits said ice block. Thus, in this technical solution, the effect of ice load on the propeller is reduced when the propeller interacts axially with ice blocks immersed in the horizontal plane of the hull or deeper.

[0006] The main disadvantage of this solution is that it is ineffective when the propeller interacts with the ice laterally and when the blades encounter ice fragments that are outside the action zone of the cutters of the propeller bushing.

[0007] There is a known propeller for an ice-going vessel, which is the closest prior art to the claimed invention, comprising a propeller hub and a blade flange removably attached to the hub, on each blade flange at least one integrally formed blade is placed, at least two integrally formed blades are positioned on at least one blade flange (EP 2993120 A1 of March 9, 2016). Thus, the propeller has six blades instead of four, each blade being made narrower and thinner; that is, the maximum force required to damage a blade is reduced while maintaining the required strength characteristics of the propeller as a whole.

[0008] The disadvantages of this known propeller are that its design is rather complicated, it is difficult to manufacture two blades and it increases the maintenance costs, because when only one blade is damaged, it is necessary to replace two blades with a common flange. Due to these considerations, the above-mentioned known propeller is not included in any podded propeller design that has been implemented.

[0009] A necessary condition to ensure the operability of the movable parts and propellers of the podded propulsion system is that the so-called "pyramid strength" principle should be taken into account in the design, according to which any damage to the propeller blades must not cause any significant damage to the podded propulsion system or other parts of the vessel. In practice, the application of this principle means that all the parts of the design that form part of the power train (starting from the propeller and ending with the components for attaching the rotating mechanism to the hull of the vessel) must remain able to operate when the "blade failure load" (BFL) (the maximum force that causes blade damage) acts on the propeller. "Propeller blade damage" means that the blade bends unacceptably due to plastic deformation of the material, or the blade breaks into separate pieces (destruction of the blade).

[0010] Blade damage is usually caused by its interaction with ice and the corresponding procedures for calculating blade failure loads are governed by regulations of classification societies and other classification organizations (DNV-GL, IACS).

[0011] In the design of podded propulsion, the thickness, strength and stiffness of the components of the "pyramid strength" powertrain must provide the necessary strength reserve and provide a minimum gap between the rotating surface and the fixed surface to ensure that no damage is caused to the podded propulsion components in the event of a blade failure, and to ensure the normal operation of the podded propulsion after the damaged blade is replaced. Increasing the blade failure load in the design of the podded propulsion will lead to an unreasonable increase in the thickness and stiffness of the power components, and a corresponding increase in the manufacturing cost of production. Summary of the invention

[0012] The technical problem faced by the present invention is to reduce the design value of the blade failure load while meeting all the requirements of the classification society on the propeller strength.

[0013] The technical result achieved by the invention is a reduction in weight and thus in cost of the podded propulsion system.

[0014] The reason for achieving this technical result is that a propeller for a pod-type propulsion device of a ship adapted to a propeller shaft comprises: a propeller hub, which is manufactured so that it can be rigidly attached to a conical tail piece of a propeller shaft; and a propeller blade mounted on the propeller hub, each propeller blade comprising a blade and a blade flange made as an integral piece, the blade entering the blade flange via a fillet joint, the fillet joint forming the weakest part of the blade that may be damaged in the cross section of the blade adjacent to the fillet joint, and the outer surface of the blade flange has a profile that is bent inwardly toward the propeller axis in its radial cross section to reduce the distance from the cross section of the blade to the propeller axis.

[0015] It is known that the value of the blade failure load depends on the thickness of the cross section of the blade blade where the fillet begins to transition into the flange, the distance from said cross section to the propeller axis and the mechanical properties of the blade material.

[0016] The minimum thickness of the blade cross section and the radius of the fillet joint are determined according to the current rules of the classification societies, as is the relative radius at which the load on the propeller is applied when calculating the value of the blade failure load. The blades of propellers for ice-going ships are usually made of a limited range of special stainless die steels with special mechanical properties.

[0017] By making the outer surface of the blade flange have a profile that is curved inwardly toward the propeller axis in the meridional cross section to reduce the distance from the blade cross section to the propeller axis, this increases the moment arm of the blade failure load compared to the conventional conical profile and the correspondingly shorter moment arm of the load, which in turn leads to a reduction in the design value of the blade failure load while meeting all the requirements of the classification society for the strength of the propeller. Therefore, the load acting on other components of the podded propeller when the propeller blade is plastically bent and / or damaged is reduced, thereby making it possible to reduce the weight of the podded propeller and thus reduce its cost.

[0018] In particular, the cross section of the transition from the blade to the flange is located at a smaller distance from the propeller axis than the distance from the intersection with the propeller axis to a straight line which is located in the meridional cross section of the propeller and connects the extreme outer radii of the propeller blade flange, thereby providing the above-mentioned reduction in the distance from the smallest cross section of the profile to the propeller axis compared to a conventional conical profile.

[0019] According to the invention, the propeller blade flange has in its meridional cross section a hydrodynamic profile formed by curves and / or smoothly connected conical portions, which curve inwards towards the propeller axis, resulting in the above-mentioned reduction in distance from the transition cross section to the propeller axis.

[0020] The propeller is usually constructed in a composite manner with removable blades, which are attached to the hub using a detachable joint, so that a single blade can be relatively easily replaced if damaged, while maintaining the operability of all other components of the podded propulsion system. However, it can also be provided that all propeller blades are made in one piece with the hub, forming an integrally cast propeller. In the case of an integrally cast propeller, the above-mentioned changes to the shape of the blade flange in order to reduce the value of the blade failure load also apply to changes in the shape of the hub.

[0021] The present invention also relates to a podded propeller for a ship, comprising a podded propeller pod and the above-mentioned propeller, and having a propeller hub housing and a spacer housing located between the propeller and the podded propeller pod. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The invention is explained with the aid of the accompanying drawings, in which:

[0023] exist Figure 1 Center: podded thrusters are shown;

[0024] exist Figure 2 Middle: shows a meridional cross section through the bushing of the propeller;

[0025] exist Figure 3 Middle: A cross section through a composite propeller is shown.

[0026] The same reference numerals are used in different drawings to denote the same structural components. DETAILED DESCRIPTION

[0027] Figure 1 A podded propulsor 1 is shown attached to the hull of a vessel 2 by means of an attachment assembly 10 and a rotary bearing 11, the podded propulsor taking the form of a cabin comprising a pod 13 attached to a leg 12, in which is placed an electric propulsion engine 15 and a propeller shaft 20. The propeller shaft 20 has a conical tail piece 21 to which a drive propeller 22 is attached outside the pod.

[0028] Two bearings 41 , 42 are positioned on the propeller shaft 20 , which bearings are used to support the shaft 20 of the electric propulsion engine 15 and to transfer the thrust (traction) from the propeller 22 to the housing of the podded propulsor.

[0029] The propeller 22 comprises a propeller hub 33 manufactured so that it can be rigidly attached to the conical tail piece 21 of the propeller shaft 20, propeller blades 30 each comprising a blade blade 31 and a blade flange 32 made in one piece, the propeller blades being mounted on the propeller hub 33, and a housing 34 of a propeller bushing.

[0030] The pod 13 and the propeller 22 of the pod propulsor are connected to each other via a spacer housing 14 .

[0031] Figure 2 A meridional cross section through a propeller hub is shown, along with a diagram showing the calculation of propeller strength as a function of the blade failure load or BFL.

[0032] The outer surface of the blade flange 32 has, in its radial cross section, a profile that curves inwardly toward the axis 50 of the propeller and is denoted by reference numeral 52 .

[0033] According to shipbuilding and classification regulations, the BFL 71 is applied at a distance 72 from the propeller axis (also called radius), which corresponds to R_BFL=0.8R in the direction of the weakest failure load of the blade. The load-bearing capacity of the blade is calculated based on the effect of the BFL 71 on the bending moment in the cross section 62 in the transition from the blade blade 31 to the flange 32, which is the weakest cross section outside the fillet transition boundary from the blade blade 31 to the blade flange 32. This cross section is usually located in the contact area between the fillet 64 and the blade profile 61. The fillet with the other relative axis 51 of the propeller blade on the blade profile 61 side is denoted by the reference numeral 65. The difference between the radius of application of the BFL and the radius of the location of the weakest cross section outside the fillet transition determines the moment arm 73 of the BFL M_64 and the corresponding bending moment value in the calculated cross section, which is the product of the BFL 71 and the moment arm 73 of the force M_64.

[0034] According to the standard, the blade failure load F is calculated by the following formula: ex , in kN:

[0035]

[0036] ,in

[0037]

[0038] Among them, σ u and σ 0.2 is the specific maximum value of the ultimate strength and yield point of the blade material;

[0039] D, c, t and r are respectively the propeller diameter, the actual length of the fillet, the thickness and radius of the cylindrical root section of the blade at the weakest point outside the fillet transition boundary, which are determined by the propeller design; this section is usually located in the area where the fillet is attached to the blade profile.

[0040] It can be seen from the strength calculation formula that, for the selected material and specific shape (geometry) of the blade 30, the value of the blade failure load applied at a radius of 0.8R is mainly determined by the radius of the weakest cross-sectional position outside the fillet transition boundary from the blade blade 31 to the blade flange 32, or in other words, by the moment arm 73 of the BFL action.

[0041] Figure 2 It is also shown that the calculated cross-section 62 of the transition from the blade 31 to the flange 32 is located at a distance R from the propeller axis 50, which is less than the distance R_53 from the intersection with the propeller axis 50 to the straight line 53, which is located in the meridional cross-section of the propeller 22 and connects the extreme outer radii R1 and R2 of the propeller blade flange 32.

[0042] By using an inwardly curved profile 52, the moment arm 73 of the BFL can be increased compared to a conventional conical generatrix of the hub, and thus compared to a shorter moment arm 74. The fillets of the blade flange 32 connecting the blade 31 to the conical hub are indicated with reference numerals 66 and 67. Thus, when using an inwardly curved profile 52, the bending moment leading to the failure of the blade 31 reaches its maximum calculated value at a smaller value of the blade failure load 71 than when using a rectilinear conical shape.

[0043] This makes it possible to reduce the design value of the blade failure load while meeting all the classification society's requirements for propeller strength. Therefore, when the propeller blade 30 undergoes plastic bending (or damage), it works according to the pyramid strength principle by reducing the load on other parts of the podded propulsion system.

[0044] Figure 3 The design of a composite propeller of a pod propeller commonly used for ice-going vessels is shown. The composite propeller generally comprises blades 30, each of which is formed by a blade blade 31 and a blade flange 32. The blades 30 are coupled to a propeller hub 33 by bolts 81 fitted in the shafts 69 of the blade flanges 32, the depth of these shafts being determined by the requirement to avoid the locking parts of the propeller blade attachment bolts 81 protruding beyond the flanges 32.

[0045] The diameter of the propeller shaft 20 and the length of the conical portion 21 of the shaft are generally determined by the requirement to transmit the maximum torque from the electric propulsion engine to the propeller of the podded propeller. The hub 33 is attached to the portion 21 of the shaft by an interference fit, and the thickness of the hub 33 is determined by the requirement to provide the necessary degree of strength and interference fit in the hub including the threaded receptacles for the blade attachment bolts 81.

[0046] The minimum thickness of the propeller blade flange 32 is determined based on the requirement to provide sufficient material under the head of the bolt 81 to securely attach the blade 30 to the hub 33 and the minimum depth of the shaft 69 required to achieve the condition that ensures that the protruding locking portion of the propeller blade attachment bolt 81 sinks into the blade flange 32.

[0047] When the above design constraints are met, the position of the weakest cross section on the outside of the fillet transition from the blade 31 to the blade flange 32 will be determined according to the shape of the generatrix of the propeller flange (bushing), such as Figure 2 As shown. Figure 2 As shown, for a given radius value R1 of the leading edge of the bushing, the use of an inwardly curved profile 52 enables the weakest cross section to be located at a smaller radius than a conventional conical profile.

[0048] This makes it possible to reduce the design value of the blade failure load compared to the traditional shape of the blade flange of a composite propeller, so that, during operation in icing conditions, when the blade 30 of the propeller is damaged to a value that avoids damage to the components of the podded propulsion system, it works according to the pyramid strength principle by reducing the loads acting on other components of the podded propulsion system.

Claims

1. A propeller (22) for a pod-type propulsion device (1) for a ship (2), adapted to be fitted on a propeller shaft (20), comprising: a propeller hub (33) manufactured so as to be rigidly attached to the conical tail piece (21) of the propeller shaft (20), and A propeller blade (30), each of the propeller blades (30) comprising a blade blade (31) and a blade flange (32) made in one piece, the propeller blade (30) being mounted on the propeller hub (33), the propeller blade (31) entering the blade flange (32) via a fillet joint (64, 65), the fillet joint (64, 65) forming the weakest part of the blade that may be damaged in the cross section of the blade blade adjacent to the fillet joint, The outer surface of the blade flange (32) has a profile that curves inwardly toward the axis (50) of the propeller in its radial cross section, so as to reduce the distance from the cross section of the blade (31) to the propeller axis (50). Characterized in that the cross section (62) of the transition from the impeller blade (31) to the impeller flange (32) is located at a distance (R) from the propeller axis (50), and the distance (R) is less than the distance (R_53) from the intersection with the propeller axis (50) to a straight line (53), which is located in the meridian cross section of the propeller (22) and connects the extreme outer radii (R1, R2) of the impeller flange (32).

2. The propeller (22) according to claim 1, characterized in that The blade flange (32) has a hydrodynamic profile in its radial cross section formed by smoothly combined conical sections.

3. The propeller (22) according to claim 1 or 2, characterized in that: The propeller (22) is made in the form of a composite propeller having removable blades (30) attached to a hub (33) using a detachable joint.

4. The propeller (22) according to claim 1 or 2, characterized in that: All the blades (30) of the propeller are made into an integral piece with the hub (33), forming an integrally cast propeller.

5. A podded propulsion device (1) for a ship (2), comprising a podded propulsion device pod, a propeller according to any one of claims 1 to 4, a spacer housing (14) and a propeller housing (34) located therebetween.

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