JP2006103615A - Ship corrosion/underwater electric field generation preventive device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ship corrosion/underwater electric field generation preventive device capable of reliably preventing corrosion of a ship and reliably preventing generation of underwater electric field from the ship. <P>SOLUTION: The ship corrosion/underwater electric field generation preventive device comprises a hull 1, a propeller 2 with the specific electric potential different from that of the hull 1, an outboard shaft 3 with the propeller 2 mounted thereon, an inboard shaft 4 connected to the outboard shaft 3 to transmit the driving force to drive the propeller 2 to the outboard shaft 3, and insulation means 11, 17, 25, 26, 30 and 31 which are provided on at least one of the outboard shaft 3 and a connection part of the outboard shaft 3 and the inboard shaft 4, and shuts off the direct or indirect electric conduction from the propeller 2 to the hull 1 through the outboard shaft 3 via the inboard shaft 4 or water or the like. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an apparatus for preventing corrosion of a hull or the like of a ship and preventing generation of an underwater electric field from the ship.

  As shown in FIG. 7, the ship is connected to the hull 51, the propeller 52, the outboard shaft 53 to which the propeller 52 is attached, and the outboard shaft 53, and the driving force for driving the propeller 52 is supplied to the outboard shaft. And an inboard shaft 54 for transmission to 53. The hull 51 and the propeller 52 are in metal contact via an outboard shaft 53, an inboard shaft 54, and the like, and are in electrical contact via seawater or the like. In general, the hull 51 is made of a metal material such as iron, and the propeller 52 that is required to have high corrosion resistance against seawater and high strength against high-speed rotation is made of a metal material such as a copper alloy.

  By the way, metal materials such as iron and copper alloys each have an intrinsic potential in an electrolyte solution such as seawater. For example, the intrinsic potential of the copper alloy constituting the propeller 52 is higher than the intrinsic potential of iron constituting the hull 51. Therefore, in the ship shown in FIG. 7, current flows from the propeller 52 having a high specific potential to the hull 51 having a low specific potential through the outboard shaft 53, the inboard shaft 54, and the like. As a result, an electric circuit having the hull 51 as an anode and the propeller 52 as a cathode is formed. Then, iron constituting the hull 51 is ionized and eluted into seawater, and the ions move to the propeller 52. As a result, a current (corrosion current) 55 flows from the hull 51 through the seawater to the propeller 52. At this time, the hull 51 is corroded (dissimilar metal contact corrosion) due to elution of ions.

  Conventionally, various methods have been employed to prevent corrosion of the hull.

  For example, a paint film was formed on the hull surface. By doing in this way, the insulation resistance with respect to the seawater etc. of a hull was made high, and the corrosion of the hull was reduced.

  In addition, a paint film was formed on the propeller surface. By doing so, the corrosion of the hull has been reduced by preventing the presence of a metal (noble metal) having a higher intrinsic potential than iron in seawater.

  Further, as shown in FIG. 7, a protective anode 56 made of a metal (base metal) having a lower intrinsic potential than iron is provided on the hull. The protective anode 56 is made of a metal material such as zinc. In this way, the current (corrosion protection current) 57 flows from the protective anode 56 through the seawater to the hull or propeller, and the protective anode is actively corroded instead of the hull, thereby preventing the hull from being corroded. It was.

  In addition, a power supply anode for applying a forced potential was provided on the hull. The power source anode is made of a metal material such as platinum titanium. In this way, the current (corrosion protection current) flows from the power source anode through the seawater to the hull or propeller, thereby preventing corrosion of the hull.

JP 2001-30986 A

  However, when the hull is immersed in seawater or the like for a long period of time, oxygen, water molecules, chlorine molecules and the like penetrate into the coating film on the hull surface due to aging. As a result, oxygen, water molecules, chlorine molecules, etc. that have penetrated into the coating film touch the hull surface, causing blistering and rusting on the hull surface. If blistering or rusting occurs on the hull surface, the insulation resistance of the paint film will rapidly decrease. Therefore, the paint film on the hull surface had to be periodically repainted. Furthermore, when the coating film is damaged and the damage reaches the hull surface, the hull surface is partially exposed. When this happens, current may flow intensively from the exposed hull surface, causing local corrosion.

  In addition, when the propeller is immersed in seawater or the like for a long period of time, the coating film on the surface of the propeller will deteriorate over time. Therefore, the coating film on the propeller surface also has to be periodically repainted.

  Furthermore, corrosion of the protective anode proceeds with time. For this reason, the protective anode has to be periodically replaced.

  In addition, the power source anode needs to control the forced potential applied to the power source anode in accordance with environmental changes. Therefore, balance management of the hull current (corrosion protection current) was necessary. Furthermore, since the external power supply anticorrosion device having the power supply anode is very expensive, it is expensive to introduce.

  By the way, an electric field (underwater electric field) is generated in water by a current (corrosion current) that is a cause of corrosion of the ship. Therefore, preventing the generation of an underwater electric field from a ship is closely related to preventing corrosion due to the generation of a corrosion current. Conventionally, there has been an apparatus or method for preventing fluctuations in the underwater electric field, but there has been no apparatus or method for preventing the occurrence of the underwater electric field itself.

  Accordingly, an object of the present invention is to provide a ship corrosion / underwater electric field generation prevention device that can reliably prevent corrosion of a ship and can reliably prevent generation of an underwater electric field from the ship. is there.

  In order to achieve the above object, the invention of claim 1 is directed to a hull, a propeller having a specific potential different from that of the hull, an outboard shaft to which the propeller is attached, and the propeller connected to the outboard shaft to drive the propeller. Provided to at least one of the inboard shaft for transmitting the driving force for the outboard shaft to the outboard shaft, the outboard shaft, the outboard shaft and the connecting portion of the inboard shaft, and from the propeller through the outboard shaft, An apparatus for preventing corrosion / underwater electric field generation of a ship, comprising an insulating means for interrupting direct or indirect electrical conduction to the hull via an inboard shaft or water.

  According to a second aspect of the present invention, the outboard shaft and the inboard shaft each include a flange for connecting to each other, and the insulating means includes an insulating plate disposed between the flanges, and the flanges The apparatus for preventing corrosion / underwater electric field generation of a ship according to claim 1, further comprising an insulating connecting member for insulating and connecting the two.

  A third aspect of the present invention is the ship corrosion / underwater electric field generation preventing apparatus according to the first or second aspect, wherein the insulating means has a first insulating coating member coated on a surface of the outboard shaft.

  The invention according to claim 4 is a second insulation covering member in which the outboard shaft is divided and a joint portion for connecting the divided portions is provided, and the insulating means covers the entire joint portion. The ship corrosion / underwater electric field generation prevention device according to any one of claims 1 to 3.

  The invention of claim 5 includes a bearing for supporting the outboard shaft, and a shaft sleeve mounted on a portion of the outboard shaft supported by the bearing, wherein the insulating means includes the outboard shaft. 5. The ship corrosion / underwater electric field generation prevention device according to claim 1, further comprising an insulating coating layer interposed between the shaft sleeve and the shaft sleeve.

  ADVANTAGE OF THE INVENTION According to this invention, while exhibiting the outstanding effect that corrosion of a ship can be prevented reliably and generation | occurrence | production of the underwater electric field from a ship can be prevented reliably.

  Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  The ship corrosion / underwater electric field generation preventing device according to the present embodiment is applied to a ship including a hull and a propeller having a specific potential different from that of the hull. Further, the corrosion / underwater electric field generation preventing device of the present embodiment is a large-sized ship, and is mainly applied to a ship that navigates at sea.

  FIG. 1 is a schematic view of a ship to which a corrosion / underwater electric field generation preventing apparatus according to an embodiment of the present invention is applied. FIG. 2 is a cross-sectional view of part A in FIG. 3 is a cross-sectional view of part B of FIG. 4 is a cross-sectional view taken along the line CC of FIG. FIG. 5 is a cross-sectional view of a portion D in FIG. FIG. 6 is a cross-sectional view of a portion E in FIG.

  In the figure, 1 is a ship hull, 2 is a propeller, 3 is an outboard shaft to which the propeller 2 is attached, and 4 is connected to the outboard shaft 3 to provide a driving force for driving the propeller 2. An inboard shaft that transmits to the outer shaft 3, and 5 is a sealing device for preventing seawater from entering the ship. The propeller 2 side (left side in FIG. 1) from the sealing device 5 is outboard, and the inboard shaft 4 side (right side in FIG. 1) from the sealing device 5 is inboard.

  The hull 1 and the propeller 2 are made of different kinds of metal materials according to their respective uses. The hull 1 is made of iron, and the propeller 2 requiring high corrosion resistance against seawater and high strength against high-speed rotation is made of a copper alloy. As described in the section of the prior art, the intrinsic potential of the copper alloy constituting the propeller 2 is higher than the intrinsic potential of iron constituting the hull 1.

  A coating film 6 having corrosion resistance against seawater is formed on the surface of the hull 1. That is, the surface of the hull 1 is painted with the paint. It is preferable that the paint to be painted on the surface of the hull 1 does not contain a metallic pigment in order to increase the insulation resistance with seawater in the hull 1.

  The outboard shaft 3 is divided into a propeller shaft 7 to which the propeller 2 is attached and a stern shaft 8 connected to the inboard shaft 4. The propeller shaft 7 and the stern shaft 8 that require high strength against high-speed rotation and thrust force are made of carbon steel (for example, SF440). The propeller shaft 7 is supported by a shaft bracket bearing 9 provided at the bottom of the hull 1. The stern shaft 8 is supported by a stern tube bearing 10 provided at the bottom of the hull 1.

  As shown in FIGS. 2, 3 and 5, the surface (outer peripheral surface) of the propeller shaft 7 is covered with a first insulating covering member 11 made of an insulating material. The first insulating covering member 11 is made of FRP (for example, GFRP). The first insulating covering member 11 is formed by a sheet winding method or the like.

  Thus, in this embodiment, the surface of the propeller shaft 7 is covered with the first insulating coating member 11 to electrically insulate the propeller shaft 7 from seawater. Therefore, indirect electrical conduction from the propeller 2 through the propeller shaft 7 to the hull 1 via seawater can be interrupted.

  As shown in FIG. 2, the propeller shaft 7 includes a flange 12 for connection to the propeller 2. The propeller 2 is fixed to the flange 12 of the propeller shaft 7 with bolts 13. The entire connecting portion between the propeller 2 and the propeller shaft 7 is covered with a cover member 14. The cover member 14 is filled with a filler 15.

  As shown in FIGS. 1, 3, and 4, a shaft sleeve 16 is sheathed from above the first insulating covering member 11 at a portion of the propeller shaft 7 that is supported by the shaft bracket bearing 9. The shaft sleeve 16 is made of a copper alloy (for example, CAC402 + 0.5% Ni). In this way, the insulating coating layer 17 made of the first insulating coating member 11 is interposed between the propeller shaft 7 and the shaft sleeve 16.

  The shaft bracket bearing 9 includes a bearing body 18 formed in a cylindrical shape, and a rubber pad 19 fixed to the inner peripheral surface of the bearing body 18. The bearing body 18 is made of a copper alloy. The rubber pad 19 is made of a fluorine resin. The rubber pad 19 is provided with a plurality of water channels 20 through which seawater flows in the axial direction at predetermined intervals in the circumferential direction. The shaft sleeve 16 has a smaller diameter than the rubber pad 19, and a bearing gap 21 through which seawater can flow is formed between the outer peripheral surface of the shaft sleeve 16 and the inner peripheral surface of the rubber pad 19.

  By the way, when the insulating coating layer 11 does not exist between the propeller shaft 7 and the shaft sleeve 16, current (corrosion current) flows through the shaft sleeve 16 to the bearing body 18 of the shaft bracket bearing 9 through seawater. Sometimes. As a result, the shaft sleeve 16 is corroded. Therefore, in the conventional corrosion prevention device, it is necessary to provide a shaft ground so that a current flows from the outboard shaft to the hull. On the other hand, in this embodiment, by providing the insulating coating layer 11 between the propeller shaft 7 and the shaft sleeve 16, the propeller shaft 7 and the shaft sleeve 16 are electrically insulated. Yes. Therefore, electrical conduction from the propeller 2 through the shaft sleeve 16 of the propeller shaft 7 to the hull 1 through seawater can be interrupted. Therefore, corrosion of the shaft sleeve 16 can be prevented without providing the shaft ground.

  Between the propeller shaft 7 and the stern shaft 8, a joint portion that connects the divided portions of the propeller shaft 7 and the stern shaft 8 is provided. As shown in FIGS. 1 and 5, the propeller shaft 7 and the stern shaft 8 are connected by a joint member 22 in a state in which the end surface of the propeller shaft 7 and the end surface of the stern shaft 8 are abutted. The joint member 22 has an outer peripheral surface that is tapered and is divided in the circumferential direction, and an inner sleeve 23 that sandwiches the propeller shaft 7 and the stern shaft 8, and an inner peripheral surface that is formed in a tapered shape. And an outer sleeve 24 fitted to the outer peripheral surface of the outer sleeve.

  A second insulating covering member 25 made of an insulating material is covered so as to cover the entire joint portion including the joint member 22 and the outer peripheral surfaces of the propeller shaft 7 and the stern shaft 8. The second insulating coating member 25 is made of FRP (for example, GFRP). The second insulating coating member 25 is formed by a sheet winding method or the like.

  Thus, in this embodiment, the joint part of the propeller shaft 7 and the stern shaft 8 is covered with the second insulating coating member 25 so that the joint part of the propeller shaft 7 and the stern shaft 8 is seawater. It is electrically insulated from. Therefore, indirect electrical continuity from the propeller 2 to the hull 1 through seawater through the joint portion between the propeller shaft 7 and the stern shaft 8 can be interrupted.

  As shown in FIG. 5, the surface (outer peripheral surface) of the stern shaft 8 is covered with a first insulating covering member 26 made of an insulating material. The first insulating covering member 26 is made of FRP (for example, GFRP). The first insulating covering member 26 is formed by a sheet winding method or the like.

  Thus, in this embodiment, the stern shaft 8 is electrically insulated from seawater by providing the first insulating coating member 26 on the surface of the stern shaft 8. Therefore, indirect electrical conduction from the propeller 2 through the stern shaft 8 to the hull 1 through seawater can be interrupted.

  As shown in FIG. 1, a shaft sleeve 27 is externally mounted on a portion of the stern shaft 8 that is supported by the stern tube bearing 10 from above the first insulating coating member 26. The shaft sleeve 27 is made of a copper alloy (for example, CAC402 + 0.5% Ni). In this way, an insulating coating layer (see reference numeral 17 in FIG. 3) of the first insulating coating member 26 is provided between the stern shaft 8 and the shaft sleeve 27. Since the stern tube bearing 10 is configured in the same manner as the shaft bracket bearing 9 described above, the description thereof is omitted.

  A connecting portion that connects the stern shaft 8 and the inboard shaft 4 is provided between the stern shaft 8 and the inboard shaft 4. As shown in FIGS. 1 and 6, the stern shaft 8 and the inboard shaft 4 are provided with flanges 28 and 29 for connection to each other, respectively. The stern shaft 8 and the inboard shaft 4 insulate the flanges 28 and 29 in a state where the end faces of the flanges 28 and 29 abut each other and an insulating plate 30 made of an insulating material is sandwiched between the flanges 28 and 29. However, they are connected by an insulating connecting member 31 for connection. That is, the insulating plate 30 is disposed between the flanges 28 and 29. The insulating connecting member 31 is composed of a bolt 32 and a nut 33 whose surfaces are subjected to an insulating process. The outer peripheral surface of the non-threaded portion 32a of the bolt 32 is covered with an insulating member 32b made of an insulating material. The bolt 32 is inserted into the mounting holes 34, 35, and 36 provided in the flanges 28 and 29 and the insulating plate 30. An insulating washer 37 made of an insulating material is provided between the neck portion of the bolt 32 and the flange 28 and between the nut 33 and the flange 29, and the bolt 32 and the nut 33 are respectively connected to the flanges 28 and 29. To avoid contact.

  Thus, in the present embodiment, the insulating plate 30 is disposed between the flanges 28 and 29 of the stern shaft 8 and the inboard shaft 4, and both the flanges 28 and 29 are connected by the insulating connecting member 31. The stern shaft 8 and the inboard shaft 4 are insulated metallically. Therefore, direct electrical conduction from the propeller 2 through the stern shaft 8 through the inboard shaft 4 to the hull 1 can be interrupted.

  The first insulating coating member 11, the insulating coating layer 17, the second insulating coating member 25, the first insulating coating member 26, the insulating plate 30, and the insulating connecting member 31 of the present embodiment are defined in the claims. Make insulation means.

  As described above, according to the present embodiment, direct or indirect electric power from the propeller through the outboard shaft to the hull through the inboard shaft or seawater is connected to the outboard shaft and the connecting portion of the outboard shaft and the inboard shaft. Since the insulating means for interrupting the electrical continuity is provided, the formation of an electric circuit that connects the hull and the propeller can be suppressed. Therefore, current (corrosion current) that causes corrosion is not generated, and corrosion of the ship can be surely prevented and generation of an underwater electric field from the ship can be reliably prevented.

  By the way, the current (anticorrosion current) that flows to the ship for the purpose of preventing corrosion also causes the generation of an underwater electric field, like the corrosion current. However, according to the present embodiment, since no corrosion current is generated as described above, it is not necessary to flow a corrosion prevention current to the ship in order to prevent corrosion due to the corrosion current. Therefore, generation of an underwater electric field from the ship can be reliably prevented.

  The present invention is not limited to the embodiment described above.

  For example, the propeller's intrinsic potential may be higher than the hull's intrinsic potential.

  Further, the ship to which the present invention is applied is not limited to a large ship, and may be a small ship.

  Furthermore, the ship to which the present invention is applied is not limited to navigating on the sea, but may be navigating on the water such as a river.

1 is a schematic view of a ship to which a corrosion / underwater electric field generation preventing device according to an embodiment of the present invention is applied. It is A section sectional drawing of FIG. It is a B section sectional view of Drawing 1. It is CC sectional view taken on the line of FIG. FIG. 2 is a cross-sectional view of a D part in FIG. 1. It is E section sectional drawing of FIG. It is the schematic of the ship to which the conventional corrosion prevention apparatus is applied.

Explanation of symbols

1 Hull 2 Propeller 3 Outboard shaft 4 Inboard shaft 7 Propeller shaft (outboard shaft)
8 Stern shaft (outboard shaft)
9-axis bracket bearing (bearing)
10 Stern tube bearing (bearing)
DESCRIPTION OF SYMBOLS 11 1st coating member 16 shaft sleeve 17 insulation coating layer 22 joint member 25 2nd coating member 26 1st coating member 27 shaft sleeve 28 flange 29 flange 30 insulation board 31 insulation connection member

Claims (5)

  A hull, a propeller having a specific potential different from that of the hull, an outboard shaft to which the propeller is attached, and an inboard shaft connected to the outboard shaft and transmitting a driving force for driving the propeller to the outboard shaft; Provided on at least one of the outboard shaft and the connecting portion of the outboard shaft and the inboard shaft, directly from the propeller through the outboard shaft to the hull through the inboard shaft or water. An apparatus for preventing corrosion / underwater electric field generation of a ship, comprising an insulating means for interrupting indirect electrical conduction.   The outboard shaft and the inboard shaft are each provided with a flange for mutual connection, and the insulating means connects the insulating plate disposed between the two flanges while insulating the two flanges from each other. The apparatus for preventing corrosion / underwater electric field generation of a ship according to claim 1, comprising: an insulating connecting member.   3. The ship corrosion / underwater electric field generation preventing apparatus according to claim 1, wherein the insulating means includes a first insulating covering member coated on a surface of the outboard shaft.   The said outboard shaft is divided | segmented, The joint part which connects the division | segmentation parts is provided, The said insulation means has a 2nd insulation coating | coated member which coat | covers so that the said whole joint part may be covered. One of the ship corrosion / underwater electric field generation prevention devices. A bearing for supporting the outboard shaft; and a shaft sleeve mounted on a portion of the outboard shaft supported by the bearing, wherein the insulating means is provided between the outboard shaft and the shaft sleeve. The ship corrosion / underwater electric field generation prevention device according to any one of claims 1 to 4, further comprising an insulating coating layer interposed therebetween.

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