JP4618921B2 - Electric corrosion prevention structure of main shaft in underwater rotating machine - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electric corrosion prevention structure for a main shaft in an underwater rotating machine such as an underwater electric pump and an aeration / stirring device.
[0002]
[Prior art and its problems]
In an underwater rotating machine such as a submersible pump, the main shaft is easily corroded by the action of a corrosion battery formed on a metal surface. As a countermeasure, a proposal has been made to avoid electric corrosion of the main shaft by using an impeller as a sacrificial anode. However, if the impeller is made of an anode material such as aluminum or zinc, it will naturally have low wear resistance, and the combination of wear and dissolution will not allow the shape of the impeller to be maintained in a short period of time. It cannot be put into practical use.
[0003]
In addition, there is an example in which a method of passing an anticorrosion current using an external power supply is employed. However, this method requires land facilities to install external power supply equipment, and has many difficult problems that must be cleared, such as securing the site, maintaining power supply, and increasing power energy consumption. When moving from the site where the machine is used to the next site where the machine is used, the entire power supply facility must be moved, which requires a large amount of movement cost.
[0004]
In submersible pumps and other equipment machines used in highly corrosive environments such as chlorine sterilization discharge tanks in purification facilities, anticorrosion measures are particularly important issues. Recently, resin pumps have been widely used, but even for resin pumps, the main shaft is stainless steel, and measures to prevent galvanic corrosion are essential. The resin pump is generally small in terms of strength, and there is a strong demand for being inexpensive in terms of cost. Therefore, the large-scale anticorrosion method using the external power source cannot be applied to the resin pump at all.
[0005]
OBJECT OF THE INVENTION
The object of the present invention can be applied to those using non-conductive impellers such as resin and rubber without the need for external power supply equipment, and is effective even in highly corrosive environments such as chlorine sterilization discharge tanks. An object of the present invention is to provide an electric corrosion prevention structure for a main shaft in an underwater rotating machine.
[0006]
[Structure of the invention]
In the structure for preventing electrolytic corrosion of the main shaft in the submersible rotating machine according to the present invention, a non-conductive impeller is attached to the load-side lead-out portion of the stainless steel main shaft by a fitting such as a tightening nut or a hexagonal bot. A return sacrificial anode made of an iron-based material having a natural potential slightly lower than that of the main shaft was fitted on the outer periphery of the main shaft on the rear surface of the boss portion of the car.
[0007]
【Example】
The case of FIG. 1 and FIG. 2 in which the submersible electric pump is implemented will be described below.
[0008]
Reference numeral 1 denotes a motor main shaft, and a load side lead-out portion of the stainless steel main shaft 1 is led down into a pump casing (not shown), and an impeller 3 is mounted by a mounting tool 2 such as a mounting nut or a hexagon bolt. Is done. The impeller 3 is made of a nonconductive material such as resin or rubber. 4 is an annular sacrificial anode made of an iron-based material whose natural potential is slightly lower than that of the main shaft 1, and is fitted on the outer periphery of the main shaft 1 on the rear surface of the boss portion of the impeller 3. As an aspect, for example, it may be fixed with a set bolt as shown in FIG. 1, or may be fixed with a screwed structure as shown in FIG.
[0009]
[Action]
The sacrificial anode 4 has a slightly lower natural potential than the main shaft 1 in contact with the liquid. Therefore, when the sacrificial anode 4 is rotating, current flows from the sacrificial anode 4 to the main shaft 1 regardless of whether it is stopped or not. Thus, the corrosion prevention of the main shaft 1 in water is realized. Further, since the potential difference with respect to the main shaft 1 is small, the sacrificial anode 4 is consumed in a small amount so that a stable anticorrosive effect can be obtained for a long period of time. be able to.
[0010]
【The invention's effect】
According to the present invention, it can be applied to those using non-conductive impellers such as resin and rubber without requiring an external power supply facility, and can be used for a long time even in a highly corrosive environment such as a chlorine sterilization discharge tank. Therefore, there is an advantage that the electric corrosion prevention effect of the main shaft in the underwater rotating machine is maintained, and the maintainability is excellent.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a main part of a submersible electric pump provided with a structure of the present invention, showing an example in which an annular sacrificial anode is fixed to the outer periphery of a main shaft with a set bolt.
FIG. 2 is a cross-sectional view of a main part of a submersible electric pump having the structure of the present invention, showing an example in which an annular sacrificial anode is fixed to the outer periphery of a main shaft by a screwing structure.
[Explanation of symbols]
1 Spindle 2 Fixture 3 Impeller 4 Ring Sacrificial Anode

Claims (1)

A non-conductive impeller is attached to the load-side lead-out portion of the stainless steel main shaft with a fitting such as a tightening nut or hexagonal bot, and the natural potential is slightly lower than the main shaft on the back surface of the boss portion of the impeller. A structure for preventing electrolytic corrosion of a main shaft in an underwater rotating machine, characterized in that an annular sacrificial anode made of a base iron-based material is fitted to the outer periphery of the main shaft.

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