JPH0672386A - Shaft grounding device of ship - Google Patents

Abstract

PURPOSE:To preclude a propulsive vane shaft system from corrosion effectively by installing a conductive and anti-corrosive coating layer along the periphery of a propelling shaft, providing a slip ring consisting of a metal sheet on the layer part of this coating layer, and contacting a brush with the slip ring. CONSTITUTION:A conductive and anti-corrosive coating layer 3 is installed along the periphery of a propelling shaft 1, and a slip ring 2 consisting of a metal sheet is installed on the over-layer part of this coating layer 3. The two ends of this slip ring 2 are fastened by a stainless steel band 5 of screw drive type, and a buffer plate 4 is interposed between them. The slip ring 2 is contacted with a brush 6 in the normally contact condition, and the brush 6 is held by a brush holder 7. Thereby increase of the electric contact resistance is suppressed not only between the slip ring 2 and brush 6 but also between the slip ring 2 and the propelling shaft 1, and thereby continuity of the hull and propelling shaft 1 is secured good for a long period of time. Accordingly the propulsive vane shaft system can be precluded from corrosion effectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shaft grounding device between a hull and a propulsion shaft of a ship.

[0002]

2. Description of the Related Art While a propulsion shaft is stopped, a hull outer plate and a propulsion blade are connected to each other through an intermediate shaft bearing and the like with a very small resistance. However, when the propulsion shaft is rotating, a lubricating oil film is formed on the bearings such as the intermediate bearings, and a large resistance is generated between the propulsion shaft and the hull. It becomes non-corrosive.

When a stray current flows into the propulsion shaft in such a state, electrolytic corrosion occurs in the propulsion blade shaft system from which this current flows out. In order to prevent such corrosion, a grounding circuit is provided between the propulsion shaft and the hull to allow the stray current flowing into the propulsion shaft to escape to the hull.

In addition, when applying cathodic protection to the propulsion wing,
In the galvanic anode method, the anticorrosion current generated from the anode attached to the stern flows into the propulsion wing through the seawater (electrolyte), and returns to the anode via the propulsion shaft and the hull to form the anticorrosion circuit, which forms the ground circuit Has been adopted. Similarly, in the external power supply system, the corrosion protection circuit is formed by connecting the propulsion shaft and the negative electrode of the power supply device.

Generally, at a place where such a shaft grounding device is provided, oil, water containing salt, dust or the like easily enters and adheres between the propulsion shaft and the slip ring and between the slip ring and the brush. If it is used over a period of time, the electrical contact resistance between the propulsion shaft and the hull will increase, resulting in incomplete electrical conduction. As a result, electric discharge corrosion or electrolytic corrosion occurs in the propulsion blade shaft system.

As a means for solving such a problem, conventionally, a method has been proposed in which a flexible thin plate is inserted between the propulsion shaft and the slip ring so as to enhance the close contact between them and to wash the brush. It is (actual public Sho 53-3999)
No. 6).

Further, it is known to seal the boundary between both side edges of the slip ring and the propulsion shaft and to use a silver alloy as the material of the slip ring and the brush (Japanese Utility Model Publication No. 63-19326).

However, although the above-mentioned problem between the slip ring and the brush can be solved by selecting the material of the slip ring and the brush, the increase in the electrical contact resistance between the slip ring and the propulsion shaft has not been solved yet. Is the current situation.

That is, since the seam of the ring cannot be processed and a perfect seal cannot be obtained, the surface of the propulsion shaft is corroded by water containing salt that has entered from the seam of the slip ring or the seam of the flexible thin plate. However, it was found that the slip ring and the like float due to the presence of corrosion products such as rust, which causes a sudden increase in resistance.

[0010]

SUMMARY OF THE INVENTION The present invention is intended to prevent an increase in electrical contact resistance, ensure electrical continuity between a hull and a propulsion shaft for a long time, and effectively prevent corrosion of a propulsion wing shaft system. The purpose is to provide a grounding device.

[0011]

The above objects of the present invention are achieved by providing a conductive and corrosion resistant coating layer between the propulsion shaft and the slip ring.

That is, according to the present invention, a conductive and corrosion-resistant paint layer is provided along the outer periphery of the propulsion shaft, a slip ring made of a thin metal plate is attached to the upper layer, and a brush is brought into contact with the slip ring. A shaft grounding device in a ship.

The present invention will be specifically described below with reference to the drawings. FIG. 1 is a simplified sectional view showing an example of a shaft grounding device in a ship of the present invention. In the figure, 1 is a propulsion shaft,
2 is a slip ring, 3 is a conductive and corrosion resistant paint layer,
4 is a buffer plate, 5 is a stainless band (screw tightening type),
Reference numeral 6 is a brush, and 7 is a brush holder.

In the present invention, the paint layer 3 is provided along the outer periphery of the propulsion shaft 1. The propulsion shaft 1 mentioned here includes an intermediate shaft, a thrust shaft, a crank shaft, and the like.

Further, the paint layer 3 provided along the outer periphery of the propulsion shaft needs to have electrical conductivity and corrosion resistance. As the pigment used in this paint, silver, copper, carbon, nickel, zinc or the like, or a compound or mixture thereof in combination can be used. However, when using a silver-based material for the slip ring 2 and the brush 6, it is desirable to use the same silver-based pigment. As the vehicle, vinyl chloride resin, acrylic resin, epoxy resin, urethane resin, alkyd resin, etc. can be used.

The thickness of the paint layer 3 is preferably 20 μm or more. If the thickness is less than 20 μm, uneven coating is possible and stable resistance cannot be obtained. The means for providing the paint layer 3 may be spray coating, brush coating or the like.

In the shaft grounding device of the present invention, the slip ring 2 made of a thin metal plate is attached to the upper layer of the paint layer 3. The material of the metal thin plate forming the slip ring 2 is
If it is a conductive metal, it is not particularly limited, for example, lead,
Examples are copper, silver or alloys thereof.

The thickness of this slip ring is 0.2.
It is desirable to be 0.5 mm. This thickness is 0.5
If it exceeds mm, it will be hard and difficult to wind, resulting in reduced workability.
If this thickness is less than 0.2 mm, swelling is likely to occur when wound, resulting in poor adhesion.

The slip ring 2 is usually fixed at both ends with a screw tightening type stainless band 5.
It is desirable to insert a cushioning plate 4 between them to increase the area for preventing slippage and holding down and prevent the tightening portion of the stainless band 5 from rising. The buffer plate 4 is preferably made of polyethylene resin, polypropylene resin, or various rubbers.

The slip ring 2 thus fixed is brought into contact with the brush 6, and the two are always in contact with each other. The brush 6 is held by the brush holder 7. The brush 6 is preferably made of a silver alloy or a silver-carbon material.

The shaft grounding device for a ship according to the present invention thus obtained can prevent an increase in the electrical contact resistance between the slip ring and the propulsion shaft as well as between the slip ring and the brush. The continuity of the propulsion shaft is secured for a long time. As a result, the thrust blade shaft system can be effectively protected against corrosion.

[0022]

EXAMPLES The present invention will be specifically described below based on Examples and the like.

Example 1 A conductive and corrosion-resistant paint layer of about 25 μm was applied to the outer circumference of a propelling shaft having a diameter of 300 mm over a width of 100 mm. The pigment of this conductive paint was silver, and the vehicle was vinyl chloride resin.

A slip ring made of a silver-copper alloy plate (width 80 mm, thickness 0.4 mm) was attached to the outer layer portion of the paint layer, and polyethylene polyethylene buffer plates (2
After pressing with 5mm width x 3t, screw tightening type stainless band (width 12.5mm, thickness 0.8m)
It fixed by m).

Further, a silver-copper brush was brought into contact with the slip ring by using a brush holder short-circuited to the hull side to form a shaft grounding device.

Comparative Example 1 A shaft grounding device was manufactured in the same manner as in Example 1 except that the conductive and corrosion resistant paint layer used in Example 1 was not used.

Comparative Example 2 A shaft grounding device was manufactured in the same manner as in Example 1 except that a lead plate (width 80 mm, thickness 0.4 mm) was used in place of the conductive and corrosion-resistant paint layer used in Example 1. .

Seawater was dripped onto the three types of shaft grounding devices thus obtained, and 180 rpm / min. The propulsion shaft was rotated at, the contact resistance was measured periodically, the two were compared during the test period of 1000 hours, and the results are shown in FIG. The contact resistance was measured by the constant current voltage drop method.

As shown in FIG. 2, the contact resistances of Comparative Examples 1 and 2 started to increase after about 20 hours, and 10
The value was about 100 times after 00 hours. On the other hand, in Example 1, the increase in contact resistance was not so remarkable.

After the test was completed, black rust was generated on the outer periphery of the propulsion shaft after the slip ring was removed in Comparative Examples 1 and 2, whereas the conductive and corrosion-resistant paint layer in Example 1 was used. Almost no change was observed on the surface of.

[0031]

In the shaft grounding device of the present invention as described above, an increase in electrical contact resistance is prevented, and electrical continuity between the hull and the propulsion shaft can be secured for a long period of time. Therefore, the propulsion blade shaft system can be effectively protected against corrosion.

[Brief description of drawings]

FIG. 1 is a simplified cross-sectional view showing an example of a shaft grounding device in a ship of the present invention.

FIG. 2 is a graph showing the relationship between contact resistance and elapsed time in Examples and Comparative Examples.

[Explanation of symbols]

1: Propulsion shaft, 2: Slip ring, 3: Conductive and corrosion resistant paint layer, 4: Buffer plate, 5: Stainless band (screw tightening type), 6: Brush, 7: Brush holder.

Claims (1)

[Claims] 1. A conductive and corrosion-resistant paint layer is provided along the outer periphery of a propulsion shaft, a slip ring made of a thin metal plate is attached to the upper layer, and a brush is brought into contact with the slip ring. Axle grounding device for ships.