Support structure of propeller duct

Abstract

To provide a support structure capable of adjusting the natural frequency of a propeller duct without increasing connecting points between a hull and the propeller duct.SOLUTION: A support structure of a propeller duct 3 according to one embodiment includes: a main support body 4 configured to suspend the propeller duct 3 from a hull 1; and at least one sub-support body 5 provided on the side of the main support body 4 and configured to connect the propeller duct 3 to the main support body 4. The sub-support body 5 is plate-shaped in parallel with the axial direction of the propeller duct 3. For example, each sub-support body 5 comprises: a first reinforcement plate 51 protruding radially outward from the propeller duct 3; and a second reinforcement plate 52 bent from the first reinforcement plate 51 and connected to the side surface of the main support body 4.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a support structure for a propeller duct that surrounds a propeller for propelling a ship.

Background Art

[0002] In ships, a propeller duct that surrounds a propeller for propulsion may be provided in order to improve propulsion efficiency. For example, FIGS. 4 and 5 of Patent Document 1 describe a support structure in which a propeller duct is suspended from a hull by a columnar support.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, a vibration force that attempts to periodically vibrate the propeller duct accompanies the rotation of the propeller and acts on the propeller duct. For this reason, it is desirable to make the natural frequency of the propeller duct different from the frequency of the vibration force.

[0005] However, with the support structure as described in FIGS. 4 and 5 of Patent Document 1, it is difficult to significantly change the natural frequency of the propeller duct. In this regard, it is also conceivable to provide a pair of connecting plates on both sides of the support and connect the propeller duct to the hull with the pair of connecting plates. However, since the amount of deformation of the hull due to external forces varies depending on the location, when the propeller duct is connected to the hull with a pair of connecting plates in addition to the support, a large load resulting from the deformation of the hull may act on the joints between the propeller duct and the support and the connecting plates, and the joints between the support and the connecting plates and the hull.

[0006] Therefore, an object of the present disclosure is to provide a support structure capable of adjusting the natural frequency of a propeller duct without increasing the connection points between the hull and the propeller duct.

Means for Solving the Problems

[0007] The present disclosure provides a support structure for a propeller duct, including a main support body that suspends the propeller duct from the hull, and at least one plate-shaped sub-support body that connects the propeller duct to the main support body on the side of the main support body and is parallel to the axial direction of the propeller duct.

Effects of the Invention

[0008] According to the present disclosure, a support structure capable of adjusting the natural frequency of the propeller duct without increasing the connection points between the hull and the propeller duct is provided.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0010] FIGS. 1A and 1B show the support structure of the propeller duct 3 according to an embodiment. The hull 1 includes a propeller upper part 11 located above the propulsion propeller 2 and a propeller upstream part 12 located in front of the propeller 2 at the stern.

[0011] The propeller duct 3 surrounds the propeller 2. That is, the axial direction of the propeller duct 3 is the ship length direction, and the horizontal direction orthogonal to the axial direction of the propeller duct 3 is the ship width direction.

[0012] The propeller 2 disposed within the propeller duct 3 includes a hub 21 fixed to a propeller shaft protruding from the propeller upstream portion 12 of the hull 1, and a plurality of blades 22 joined to the hub 21. The propeller duct 3 has a reduced diameter in a direction away from the propeller upstream portion 12, that is, rearward. Generally, the inner diameter of the rear end of the propeller duct 3 is larger than the diameter D of the propeller 2, but the inner diameter of the rear end of the propeller duct 3 may be smaller than the diameter D of the propeller 2.

[0013] The support structure includes a main support 4 that suspends the propeller duct 3 from the propeller upper portion 11 of the hull 1, and at least one sub - support 5 that connects the propeller duct 3 to the main support 4 on the side of the main support 4. In the present embodiment, a pair of sub - supports 5 are disposed on both sides of the main support 4.

[0014] The main support 4 is interposed between the top of the propeller duct 3 and the propeller upper portion 11 of the hull 1. In the present embodiment, the main support 4 has a shape in which the width in the ship - width direction becomes narrower downward. For example, the width of the upper end of the main support 4 is 10% or more and 150% or less of the diameter D of the propeller 2, and the width of the lower end of the main support 4 is 5% or more and 100% or less of the diameter D of the propeller 2.

[0015] For example, the main support 4 includes a pair of side plates that form both side surfaces of the main support 4, and a plurality of vertical plates perpendicular to the propeller upper portion 11 of the hull 1 disposed between the pair of side plates. The vertical plates may include a horizontal plate that connects the side plates and is orthogonal to the axial direction of the propeller duct 3, and a vertical plate that intersects the horizontal plate and is parallel to the axial direction of the propeller duct 3.

[0016] Each sub - support 5 is plate - shaped and parallel to the axial direction of the propeller duct 3. Each sub - support 5 does not need to be completely parallel to the axial direction of the propeller duct 3 and may be slightly inclined (for example, within 10 degrees) with respect to the axial direction of the propeller duct 3.

[0017] In this embodiment, each sub-support 5 has an L-shaped cross-sectional shape. More specifically, each sub-support 5 includes a first reinforcing plate 51 that protrudes radially outward from the propeller duct 3, and a second reinforcing plate 52 that bends from the first reinforcing plate 51 and is connected to the side surface of the main support 4. For example, the first reinforcing plate 51 is joined to the outer peripheral surface of the propeller duct 3 by welding, and the second reinforcing plate 52 is joined to the side surface of the main support 4 by welding.

[0018] The plate thicknesses of the first reinforcing plate 51 and the second reinforcing plate 52 may be the same or different. For example, the plate thicknesses of the first reinforcing plate 51 and the second reinforcing plate 52 are 3.2 mm or more and 50 mm or less.

[0019] The angular position θ of the first reinforcing plate 51 from the center of the main support 4 on the outer peripheral surface of the propeller duct 3 is desirably 50 degrees or more and 80 degrees or less. If the angular position θ of the first reinforcing plate 51 is 50 degrees or more, the natural frequency of the propeller duct 3 can be effectively adjusted according to the angular position θ of the first reinforcing plate 51. If the angular position θ of the first reinforcing plate 51 is 80 degrees or less, the length of the second reinforcing plate 52 can be suppressed and the fluid resistance by the sub-support 5 can be suppressed.

[0020] The protruding length L of the first reinforcing plate 51 from the propeller duct 3 is desirably 1% or more and 10% or less of the diameter D of the propeller 2. This is because the natural frequency of the propeller duct 3 can be effectively adjusted according to the protruding length L of the first reinforcing plate 51.

[0021] As described above, in the support structure of this embodiment, since the sub-support 5 connects the propeller duct 3 to the main support 4, the natural frequency of the propeller duct 3 can be adjusted without increasing the connection points between the hull 1 and the propeller duct 3. Moreover, since the sub-support 5 is plate-shaped and parallel to the axial direction of the propeller duct 3, it is difficult for the sub-support 5 to become fluid resistance.

[0022] In addition, in the present embodiment, since each sub-support 5 includes the first reinforcing plate 51 and the second reinforcing plate 52, the natural frequency of the propeller duct 3 can be adjusted by the protruding length L of the first reinforcing plate 51 from the propeller duct 3, the plate thickness of the first reinforcing plate 51, and the like. Moreover, since the first reinforcing plate 51 protrudes radially outward from the propeller duct 3, the first reinforcing plate 51 can be satisfactorily welded to the propeller duct 3.

[0023] <Modification example> The present disclosure is not limited to the above-described embodiments, and various modifications are possible without departing from the gist of the present disclosure.

[0024] For example, as shown in FIG. 2, the width of the main support 4 in the ship width direction may be constant. In this case, depending on the angular position of the first reinforcing plate 51, the second reinforcing plate 52 of each sub-support 5 may be curved along the outer peripheral surface of the propeller duct 3.

[0025] However, if the width of the main support 4 becomes narrower downward as in the above-described embodiment, the cross-sectional shape of the main support 4 becomes an inverted trapezoid, so that the second reinforcing plate 52 can be made flat, and the cost can be reduced. Further, if the cross-sectional shape of the main support 4 is an inverted trapezoid, the fluid resistance can also be minimized.

[0026] The sub-supports 5 do not necessarily have to be arranged on both sides of the main support 4, and one sub-support 5 may be arranged on one side of the main support 4. The support structure of the propeller duct 3 with only one sub-support 5 is applicable to a twin-screw ship, and the support structure of the propeller duct 3 with a pair of sub-supports 5 is applicable to a single-screw ship. In a twin-screw ship, the support structures on both sides are opposite to each other arbitrarily.

[0027] <Summary> As a first aspect, the present disclosure provides a support structure for a propeller duct, including a main support that suspends the propeller duct from a hull, and at least one plate-shaped sub-support that is laterally disposed of the main support and connects the propeller duct to the main support and is parallel to the axial direction of the propeller duct.

[0028] According to the above configuration, since the auxiliary support connects the propeller duct to the main support, the natural frequency of the propeller duct can be adjusted without increasing the connection points between the hull and the propeller duct. Moreover, since the auxiliary support is in the form of a plate parallel to the axial direction of the propeller duct, it is difficult for the auxiliary support to become a fluid resistance.

[0029] As a second aspect, in the first aspect, the at least one auxiliary support may include a first reinforcing plate protruding radially outward from the propeller duct and a second reinforcing plate bent from the first reinforcing plate and connected to the side surface of the main support. According to this configuration, the natural frequency of the propeller duct can be adjusted by the protruding length of the first reinforcing plate from the propeller duct, the plate thickness of the first reinforcing plate, etc. Moreover, since the first reinforcing plate protrudes radially outward from the propeller duct, the first reinforcing plate can be welded to the propeller duct well.

[0030] As a third aspect, in the second aspect, the protruding length of the first reinforcing plate from the propeller duct may be 1% or more and 10% or less of the diameter of the propeller disposed in the propeller duct. According to this configuration, the natural frequency of the propeller duct can be effectively adjusted according to the protruding length of the first reinforcing plate from the propeller duct.

[0031] As a fourth aspect, in the second or third aspect, the angular position of the first reinforcing plate from the center of the main support on the outer peripheral surface of the propeller duct may be 50 degrees or more and 80 degrees or less. According to this configuration, since the angular position of the first reinforcing plate is 50 degrees or more, the natural frequency of the propeller duct can be effectively adjusted according to the angular position of the first reinforcing plate. On the other hand, since the angular position of the first reinforcing plate is 80 degrees or less, the fluid resistance by the auxiliary support can be suppressed.

[0032] As a fifth aspect, in any of the first to fourth aspects, the main support may have a shape in which the width becomes narrower toward the bottom. According to this configuration, since the cross-sectional shape of the main support is trapezoidal in reverse, it is possible to flatten the second reinforcing plate, and the cost can be reduced.

[0033] As a sixth aspect, in any of the first to fifth aspects, the at least one sub-support may include a pair of sub-supports arranged on both sides of the main support. The support structure of a propeller duct with only one sub-support is applicable to a twin-screw ship, and the support structure of a propeller duct with a pair of sub-supports is applicable to a single-screw ship.

Explanation of reference numerals

[0034] 1 Hull 2 Propeller 3 Propeller duct 4 Main support 5 Sub-support 51 First reinforcing plate 52 Second reinforcing plate

Claims

1. A main support for suspending a propeller duct from a hull, and at least one plate-shaped sub-support that is disposed laterally of the main support and connects the propeller duct to the main support, the sub-support being parallel to the axial direction of the propeller duct. A support structure for a propeller duct, comprising the above.

2. The support structure for a propeller duct according to claim 1, wherein the at least one sub-support includes a first reinforcing plate that protrudes radially outward from the propeller duct and a second reinforcing plate that bends from the first reinforcing plate and connects to a side surface of the main support.

3. The support structure for a propeller duct according to claim 2, wherein a protruding length of the first reinforcing plate from the propeller duct is 1% or more and 10% or less of a diameter of a propeller disposed within the propeller duct.

4. The support structure for a propeller duct according to claim 2 or 3, wherein an angular position of the first reinforcing plate from a center of the main support on an outer peripheral surface of the propeller duct is 50 degrees or more and 80 degrees or less.

5. The support structure for a propeller duct according to any one of claims 1 to 3, wherein the main support has a shape that narrows in width downward.

6. The support structure for a propeller duct according to any one of claims 1 to 3, wherein the at least one sub-support includes a pair of sub-supports disposed on both sides of the main support.

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