JP4683793B2 - Condensation prevention structure for underwater motor - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a dew condensation prevention structure for a submersible motor that is mainly used as a prime mover for a submersible rotary machine such as a submersible pump.
[0002]
[Prior art and its problems]
The submersible motor condenses moisture in the air in the casing due to changes in internal temperature that accompany operation / stop. It is widely known that this dew condensation phenomenon causes an accident such as a decrease in insulation of a charged part, a short circuit, or a leakage. As a countermeasure for preventing condensation, generally, (1) the interior space heater is energized so that the temperature of the inside during the stoppage does not become low. (2) Enclose the dehumidifying agent inside the motor, or enclose the dehumidifying agent in a dew condensation box installed outside the terminal box. (3) Send dry air from the ground into the motor and release the absorbed air to the ground. Etc. are implemented.
[0003]
However, the method using the space heater (1) consumes extra power and increases the running cost. In addition, in the method (2) using the dehumidifying agent, a large space is required to enclose a large amount of dehumidifying agent that can prevent dew condensation. The structure becomes complicated and the manufacturing cost increases, and in each case, since the dehumidifying agent needs to be replaced periodically, the running cost also increases. In addition, the method (3) using dry air requires a permanent installation of an air dryer and air supply equipment, and piping for supply and exhaust, which increases initial cost and running costs, and is used at sites where submersible pumps are used. Therefore, it is not possible to apply it to portable submersible pumps.
[0004]
OBJECT OF THE INVENTION
The object of the present invention is to reduce the initial cost and running cost without increasing the size and complexity of the motor frame, and without consuming excessive power, and to obtain a safe and permanent dew condensation prevention effect. Another object of the present invention is to provide a dew condensation prevention structure for an underwater motor.
[0005]
[Structure of the invention]
In the dew condensation prevention structure for an underwater motor according to the present invention, in an underwater motor having an airtight structure having an airtight hole on the shaft seal chamber side and an airtight test hole on the non-shaft seal chamber side, the air is sucked and exhausted from the airtight hole. The motor frame is filled with a stabilizing gas that is press-fitted from the airtight test hole, and the gas is preferably nitrogen gas.
[0006]
[Action]
The cause of condensation is the moisture in the air present in the motor. However, in the dew condensation prevention structure of the present invention, there is no room for condensation because the motor is filled with the stabilizing gas and there is no air, and sparks may be generated because the atmosphere around the filling part is stable. Absent.
[0007]
【Example】
Hereinafter, description will be made with reference to FIGS.
[0008]
Reference numeral 1 denotes a submersible motor frame, which includes a cylindrical frame body 1a, a shaft seal chamber side frame 1b that closes one end of the slam body 1a, and an anti-shaft seal chamber side frame that closes the other end of the frame body 1a. It is comprised by 1c and the sealing structure. Reference numeral 2 denotes an airtight hole provided in the shaft seal chamber side frame 1b, and is configured to be opened and closed by attaching and detaching the screw plug 3. Reference numeral 4 denotes an airtight test hole configured to be freely opened and closed by attaching and detaching the screw plug 5, and is provided at a position close to the opposite shaft sealing chamber side frame 1c or the frame main body 1a. Reference numeral 6 denotes a motor main shaft, and an impeller 8 in the spiral chamber 7 is fitted to a load side lead-out end that is led through the center of the shaft seal chamber-side frame 1b.
[0009]
The airtight hole 2 is connected to the vacuum pump 9, the air in the motor frame 1 is exhausted by the suction action of the vacuum pump 9, and the gas cylinder 10 is connected to the airtight test hole 4 to supply high-pressure stabilized gas to the motor frame 1. Fill in. For example, nitrogen gas or hexafluoride gas is used as the stabilizing gas. Nitrogen gas is highly safe, the atmosphere inside the motor can be maintained in a suitable state permanently, is inexpensive and easily available, and the motor frame 1 can be easily used at a pressure higher than atmospheric pressure using the gas cylinder 10. Can be filled in. Further, since the specific gravity of nitrogen gas is substantially equal to air, intrusion of outside air into the motor is eliminated even during frame assembly.
[0010]
【The invention's effect】
According to the dew condensation prevention structure of the submersible motor of the present invention, the initial cost and running cost are low-cost without increasing the size and complexity of the motor frame, and without spending extra power. A dew condensation prevention effect can be obtained.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional side view of an essential part of a submersible pump that is an object of implementation of the dew condensation prevention structure of the present invention.
FIG. 2 is an explanatory view schematically showing an embodiment of the present invention.
[Explanation of symbols]
1 Motor frame 2 Airtight hole 4 Airtight test hole

Claims (2)

In an underwater motor having an airtight structure having an airtight hole on the shaft seal chamber side and an airtight test hole on the non-shaft seal chamber side, the motor frame sucked and exhausted from the airtight hole has an airtight test hole. A dew condensation prevention structure for a submersible motor, characterized by being filled with a press-fitted stabilizing gas. 2. The dew condensation prevention structure for a submersible motor according to claim 1, wherein the stabilizing gas in the motor frame is nitrogen gas.

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