JPH0139080Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of a shaft sealing device for a submersible electric motor operated underwater.

Since submersible electric motors are generally operated underwater, the shaft penetrating portion of the rotating shaft is sealed with a shaft sealing device to prevent water from entering the motor through the shaft penetrating portion. Since the conventional shaft sealing device has a structure in which only one or two stages of mechanical seals are provided to seal the shaft penetrating portion, it cannot be guaranteed that water intrusion can be completely prevented. Furthermore, submersible electric motors are not necessarily used in clean water, but may also be used for purposes such as stirring and excavating the bottom of the water, and in this case, the area near the submersible electric motor becomes muddy water containing a large amount of sand and dust. Therefore,
If muddy water containing dust enters through the shaft penetrating portion, the sliding portion of the shaft sealing device may be seriously damaged and a large amount of water may enter.
For this reason, conventional shaft sealing devices for submersible motors have been subject to increased inspections, but maintenance is extremely troublesome and time loss during the maintenance is extremely large.

The present invention has been developed in view of this point, and it is an object of the present invention to provide a shaft sealing device for a submersible motor that protects the shaft sealing device from muddy water, etc., has a long life, and has good workability.

An embodiment of the present invention will be described below with reference to the drawings. In the figure, reference numeral 1 denotes a rotating shaft of a submersible electric motor (not shown), which is rotatably supported via a bearing 8 provided in a bearing frame 2. Reference numerals 4 and 5 denote a bearing cover that holds the bearing 3 from the inside and outside of the bearing frame 2, respectively; 6 a draining plate that is attached around the rotating shaft 1 and forming a drain between it and the outer bearing cover 5; and 7 a bearing cover. A support plate 9 is airtightly attached to the support plate 7 and forms a preliminary chamber 8 between it and the bearing frame 2; a seal frame 9 is airtightly attached to the support plate 7 and forms a seal chamber 10 between it and the support plate 7; ,
11a and 12a are first and second mechanical seal fixing rings that are fitted around the shaft through holes of the support frame 7 and the seal frame 9; 11b and 12b are fitted around the ring 13 that is airtightly placed around the rotating shaft 1; First and second mechanical seal rotating rings are provided in a sliding airtight manner with the first and second mechanical seal fixed rings 11a and 12a, and 14 is a bellows holding frame fixed to the seal frame 9 via an auxiliary plate 15. , 16 is a bellows that is airtightly attached to an auxiliary plate 15 in the bellows holding frame 14, and the inside of this bellows 16 communicates with the sealing chamber 10 through a communication hole 17 provided in the sealing frame 9. Reference numeral 18 denotes a bellows holding frame lid that covers the opening of the bellows holding frame 14, and the bellows holding frame cover 18 is provided with a communication hole 19 that communicates the inside of the bellows holding frame 14 with the outside. 20 is a filter that filters dust and the like from water flowing into the bellows holding frame 14 through the communication hole 19; 21 is a pressure spring that is provided between the bellows 16 and the bellows holding frame lid 18; and 22 is a pressure spring that pressurizes the bellows 16; A dust seal 24 is attached to the seal frame 9 via a dust seal mounting plate 23 and seals between the ring 13 and the ring 13. A leakage seal 24 is provided in the preliminary chamber 8 and detects when the water accumulated in the preliminary chamber 8 has reached a predetermined amount. It is a detector. Then, fresh water is sealed inside the seal chamber 10 and bellows 16 of the shaft seal device configured as described above. In this work of filling fresh water, the bellows holding frame lid 18 is removed and the pressure spring pressurizing the bellows is loosened, and then the plug 25 provided at the top of the sealing frame 9 is removed and fresh water is filled.
After filling the fresh water, the stopper 25 is closed, the bellows holding frame lid 18 is attached to the bellows holding frame 14, and pressure is applied to the fresh water in the sealing chamber 10 by the pressure spring 21 and the bellows 16.

That is, in the shaft sealing device of the present invention, the shaft penetrating portion has a double seal structure, fresh water is sealed in the seal chamber 10 between the two, and the fresh water in the seal chamber 10 is pressurized by the pressure spring 21 and the bellows 16. This is what I did. In this way, the fresh water pressure in the seal chamber 10 is set to a higher pressure than the outer peripheral water pressure of the submersible motor, and the second
This prevents water from entering the outer periphery from the sliding portion of the mechanical seal fixed ring 12a and the second mechanical seal rotating ring 12b. Therefore, muddy water containing sand and dust does not enter the sliding portion, so that the sliding portion can be operated for a long time without being damaged. The bellows 16 and the pressure spring 21 absorb expansion and contraction of volume due to temperature changes in the seal chamber 10, thereby preventing intrusion of outside water. Also, since the pressure in the seal chamber 10 is higher than that in the preliminary chamber 8, the first mechanical seal fixed ring 11
Clean water may leak into the preliminary chamber 8 from the sliding portion between the first mechanical seal rotary ring 11b and the first mechanical seal rotating ring 11b. For this reason, the preliminary chamber 8 is provided with a leak detector 24 that sends a signal to the outside when the leaked water reaches a predetermined amount, so that it can be detected externally. Although not shown, it is easy to understand that the water accumulated in the preliminary chamber 8 can be drained in response to a signal from the leakage detector 24. In addition, although the amount of water leaking from the seal chamber 10 to the outside varies depending on various conditions, the amount of water lost due to water leakage is extremely small, and replenishment is only required once every several thousand hours, and the time required for maintenance and inspection is extremely short. . In the above embodiment, pressure is applied to the fresh water in the seal chamber 10 by the bellows 16 and the pressure spring 21, but the invention is not limited to this. It goes without saying that pressure may be applied via, for example.

In this way, in this invention, the shaft penetrating part has a double seal structure to form a seal chamber, and fresh water is always pressurized and sealed in this seal chamber, so that muddy water etc. around the outer circumference of the submersible motor can be removed from the shaft seal part. It does not reach the moving parts, and the life of the sliding parts can be significantly extended. This also reduces the number of inspections and has the effect of significantly extending the working time.

[Brief explanation of the drawing]

The figure is a longitudinal cross-sectional view of a shaft sealing device for an underwater electric motor according to the present invention. DESCRIPTION OF SYMBOLS 1... Rotating shaft, 7... Support plate, 8... Preliminary chamber, 9... Seal frame, 10... Seal chamber, 11a... First mechanical seal fixed ring, 11b... First mechanical seal rotating ring, 12a... Second Mechanical seal fixed ring, 12b...second mechanical seal rotating ring,
16... Bellows, 21... Pressure spring, 24... Leak detector.

Claims (1)

[Claims for Utility Model Registration] Support plate 7 through which the rotating shaft 1 of the submersible electric motor passes and forms a spare chamber 8 between the bearing frame 2 and the outer side of the bearing frame 2.
a seal frame 9 through which the rotating shaft 1 of the underwater electric motor similarly forms a seal chamber 10 between the rotating shaft 1 and the supporting plate 7; and a first mechanical member for sealing between the rotating shaft 1 and the supporting plate 7. Seals 11a and 11b, second mechanical seals 12a and 12b that seal between the rotating shaft 1 and the seal frame 9, fresh water sealed in the seal chamber 10, and pressurization that constantly pressurizes the fresh water. and a leak detector 24 provided in the preliminary chamber 8 to detect when the water accumulated in the preliminary chamber 8 has reached a predetermined amount.
A shaft sealing device for an underwater electric motor, characterized by comprising: