JPH0348208Y2 - - Google Patents

Description

[Detailed explanation of the idea] [Industrial application field] The present invention relates to a propeller corrosion protection device for ships.

[Conventional technology]

When using different metals in seawater, for example,
Due to the inherent potential of each metal in seawater as shown in the figure, a corrosion protection current flows from metals with a large negative potential (base metals) to metals with a small negative potential (noble metals). Corrosion is protected, and the characteristic potential of each metal becomes as shown in the diagram in FIG.

Since the propeller of a ship is made of a copper alloy or stainless steel material and the hull is made of steel, which is a base metal, it is necessary to protect the propeller material from corrosion and prevent electrochemical corrosion (hereinafter referred to as electrolytic corrosion) of the hull material. In order to prevent this, as shown in the vertical cross-sectional side view of the stern portion of FIG. It's flowing.

In such a corrosion protection device, when the ship is at anchor and the propeller 09 is not rotating, the corrosion protection current flows from the zinc plate 06 → propeller blade 010 / propeller cap 03 → propeller boss 011 → propeller, as shown by the solid line arrow in the figure. An anti-corrosion current 017 is formed during berth that flows through the circuit of shaft 012 → stern tube bearing 013 → hull 014 → zinc plate 06, and when the ship is sailing and the propeller 09 is rotating, the propeller shaft 012 and the stern tube bearing 013 are connected to each other. Since a lubricating oil film that acts as an insulator is generated between them, the anti-corrosion current flows from the middle of the solid arrow in the same figure to the chain arrow as shown by the chain arrow: zinc plate 06 → propeller blade 010 / propeller cap 03 → propeller boss 011 → propeller shaft 01
2 → Intermediate shaft 015 → Axis grounding mechanism 016 → Hull 0
14→An anti-corrosion current 018 during navigation is formed which flows through the circuit of the zinc plate 06.

However, such a device has the following drawbacks.

(1) When the propeller 09 is rotating, the shaft grounding mechanism 016 that grounds the rotating intermediate shaft 015 and the hull 014 has a brush contact structure. Accumulation causes a contact failure, and the anti-corrosion current 018 is cut off during navigation. As a result, the propeller blades 010 and the propeller boss 011 were not protected from corrosion and were subjected to electrolytic corrosion, causing pinholes to occur in them.
If this is left untreated, the propeller blade 010 will break and the propeller boss 011 surface will crack.

(2) If the zinc plate 06 dissolves in seawater and wears out during long-term voyages, the ship's hull 0, which is the second most inferior ship after the zinc plate 06, will
The hull 014 corrodes because the steel No. 14 dissolves into seawater and forms a corrosion protection current circuit.

[Problem that the invention attempts to solve]

The present invention was proposed in view of these circumstances, and the propeller members will not be electrolytically corroded even if the anti-corrosion current is cut off due to a defect in the shaft grounding mechanism, and the hull members will be protected even if the zinc plate is worn out. The purpose of the present invention is to provide a corrosion protection device for a propeller for a ship that has reliable corrosion protection performance that prevents electrolytic corrosion.

[Means for solving problems]

To this end, the present invention aims to improve the relationship between the specific potential of the zinc plate and that of the hull material in a propeller corrosion protection system for ships in which a zinc plate is attached to the hull near the propeller and a shaft grounding mechanism is provided in the propeller shaft system. and a corrosion-proofing metal attached to the propeller cap, which is made of a metal with a negative characteristic potential and is described later, and has a negative characteristic potential between the characteristic potential of the corrosion-proofing metal and that of the boss and blades of the propeller. It is characterized by having a propeller cap.

[Effect]

With the above configuration, when the shaft grounding mechanism becomes defective or the zinc plate is worn out, an internal anti-corrosion current circuit is formed between the anti-corrosion → propeller cap → propeller member → anti-corrosion. Therefore, electrolytic corrosion of the propeller member and/or the hull member can be prevented.

In addition, even when the anticorrosive material is consumed, an internal anticorrosive current circuit is formed between the propeller cap → propeller member → propeller cap.
Electrical corrosion of propeller members can be prevented.

〔Example〕

An embodiment of the present invention will be explained with reference to the drawings.
Figure 1 is a longitudinal side view of the stern part, Figure 2 is a longitudinal side view of the stern part showing the circuits of each anti-corrosion current that acts on Figure 1, and Figure 3 is the same as in Figure 2, where the shaft grounding mechanism is defective. The same vertical cross-sectional side view of the stern section shows the circuits of each anticorrosion current that acts when the corrosion occurs.
FIG. 4 is a partial vertical sectional side view of the stern section of FIG. 2, showing the circuit of the anti-corrosion current that is applied when the shaft grounding mechanism becomes defective and the zinc plate is worn out.

In the above figure, the same symbols as in Figs. 5 to 7 indicate the same parts as in the same figure, and 1 is a corrosion-proofing material fixed to the propeller cap 3 via bolt 2, which will be described below, and it has a negative potential. Zinc plate 06 and hull 01
Pure iron, which is between the material of 4 and steel, is used as the material, and the generated current is equal to the surface area of propeller 09.
It is a function of the anti-corrosion current density, the current generated by pure iron, etc. For example, the size of pure iron is 300 mm long x 150 mm wide x 30 mm thick.
In the case of 0.4~0.5A. 3 is a propeller cap made of cast steel whose negative potential is between that of the material of the corrosion protection material 1 and that of the propeller boss 011 and the propeller blades 010, and 4 is an internal corrosion protection current.

In such a device, as shown in FIG. 1, the negative potential of each material of the corrosion protection 1, propeller cap 3, propeller boss 011, and propeller blade 010 is in a relationship that decreases sequentially, so there is no connection between them. As shown by the broken line arrow, an anti-corrosion current flows and an internal anti-corrosion current 4 is formed, and at the same time, the negative potential of the material of the propeller cap 3 becomes equal to that of the material of the anti-corrosion material 1 and the propeller boss 011/propeller blade 010.
Since the material is intermediate to that of the material shown in FIG.

From the above, first, when each anti-corrosion current of the device acts normally, as shown in Fig. 2, the berthing anti-corrosion current 017 and the internal anti-corrosion current 4 flow during berthing, and the cruising anti-corrosion current 018 flows during navigation. and internal corrosion protection current 4
flows.

Next, when the shaft earthing mechanism 016 becomes defective, as shown in FIG. 3, the berthing anti-corrosion current 017 and the internal anti-corrosion current 4 flow during berthing, and the internal anti-corrosion current 4 flows during navigation.

Furthermore, if the shaft grounding mechanism 016 is defective and the zinc plate 06 is worn out, the internal anticorrosion current 4 will flow both at anchor and during navigation, as shown in FIG.

According to such a device, the following effects can be achieved.

(1) Even if the anti-corrosion current is interrupted during navigation, the internal anti-corrosion current of the present invention is formed and no electrolytic corrosion occurs in the propeller members, so the propeller blades will not break or cracks will occur on the surface of the propeller boss.

(2) Even if the zinc plate wears out, the hull will not be electrolytically corroded because there is pure iron, which is less corrosion resistant than the steel in the hull.

(3) Since the propeller cap is made of cast steel, which is baser than the material of the propeller boss and propeller blades,
Even if the corrosion-resistant pure iron wears out, an internal anti-corrosion current is formed between the propeller cap, propeller boss, and propeller blades, preventing electrolytic corrosion from occurring on the propeller components. No cracks will occur.

(4) Reliable anticorrosion performance can be obtained by the synergistic effect of (1) to (3).

[Effect of idea]

In short, according to the present invention, in a propeller corrosion protection system for a ship in which a zinc plate is attached to the hull near the propeller and a shaft grounding mechanism is provided in the propeller shaft system, the inherent potential of the zinc plate and that of the hull material are determined. A corrosion-proofing metal attached to the propeller cap, which is made of a metal and has a negative characteristic potential between the two, and a negative characteristic potential between the characteristic potential of the corrosion-proofing metal and that of the boss and blades of the propeller. With the propeller cap, the propeller parts will not be electrolytically corroded even if the shaft grounding mechanism is defective and the anticorrosive current is cut off, and the hull parts will not be electrolytically corroded even if the zinc plate is worn out. Because you get a reliable ship propeller corrosion protection system,
The present invention is extremely useful industrially.

[Brief explanation of drawings]

Fig. 1 is a partial longitudinal sectional side view of the stern section showing an embodiment of the present invention; Fig. 2 is a longitudinal sectional side view of the stern section showing the circuits of each anti-corrosion current acting on the one shown in Fig. 1;
The figure is a partial longitudinal side view of the stern section showing the circuits of each anti-corrosion current that act when the shaft earthing mechanism becomes defective in FIG. 2, and FIG. FIG. 3 is a partial vertical cross-sectional side view of the stern portion of the ship, showing a circuit of an anti-corrosion current that is applied when the zinc plate is worn out. Fig. 5 is a diagram showing a known measurement procedure for the inherent potential of metallic materials in seawater, Fig. 6 is a diagram showing the known potential of metallic materials in flowing seawater, and Fig. 7 is a known corrosion protection system for a propeller of a ship. FIG. 1... Corrosion protection, 2... Bolt, 3... Propeller cap, 4... Internal corrosion protection current, 06... Zinc plate, 07... Rudder, 08... Stern aggregate, 09... Propeller, 010... ...Propeller blade, 011...
Propeller boss, 012...Propeller shaft, 01
3... Stern tube bearing, 014... Hull, 015...
Intermediate shaft, 016... Shaft earthing mechanism, 017... Corrosion protection current during berthing, 018... Corrosion protection current during navigation.

Claims (1)

[Scope of utility model registration request] In a propeller corrosion protection system for a ship in which a zinc plate is attached to the hull near the propeller and a shaft grounding mechanism is provided in the propeller shaft system, the negative inherent potential between the zinc plate's inherent potential and that of the hull material is A corrosion-proofing metal made of a metal having a potential and attached to a propeller cap, which will be described later, and a propeller cap having a negative characteristic potential between the characteristic potential of the corrosion-proofing metal and that of the boss and blades of the propeller. A ship propeller corrosion protection device characterized by: