JPS5821322Y2 - Shaft sealing device for internal pressure explosion-proof electric motor - Google Patents

Description

[Detailed description of the invention] The present invention relates to a shaft seal for the shaft penetrating part of an electric motor with an internal pressure explosion-proof structure.A shaft sealing device for an electric motor with an internal pressure explosion-proof structure that aims to reduce the consumption of protective gas and facilitate air scavenging. Regarding.

This type of internal pressure explosion-proof electric motor, that is, the ventilation type internal pressure explosion-proof structure specified by the factory electrical equipment explosion-proof guideline (hereinafter referred to as the branch guideline) issued by the Ministry of Labor's Industrial Safety Research Institute, and the enclosed type internal pressure explosion-proof structure electric motor, The necessary and sufficient wind pressure and air volume of the protective gas must be determined to ensure its internal pressure explosion-proof properties.

In this case, when starting the motor and during operation, the pressure at any point inside the motor will be 5f in the water column lower than the pressure around the equipment.
The electric motor must be held at a higher height than ltm, and a structure that allows easy cleaning of all parts inside the electric motor is required.

Nowadays, there is a strong demand to suppress the consumption of the protective gas used to maintain internal pressure from the viewpoint of energy saving and the like.

For this purpose, sealing of the joints of each part and shaft sealing of the shaft penetration part,
Although important, each of these five joints can be solved relatively easily by using packing or the like.

-The shaft seal of the thick shaft penetration part is complicated due to its structure.

Conventional electric motors with ventilation type internal pressure explosion-proof structure and enclosed type internal pressure explosion-proof structure have either a shaft sealing device in which a side plate 3 is provided between the motor shaft 1 and a gap A as shown in FIG. 1, or a shaft sealing device as shown in FIG. 2. There is a so-called labyrinth seal shaft sealing device in which a motor shaft 1 is alternately provided with a gap C1, a battery case 2, and a labyrinth 4.

According to the above method, in the method shown in Figure 1, the protective gas inside the electric motor (pressurized to 5 mm or more of water column from the external pressure) specified in the branch guidelines is transferred from the gap A to the arrow B. leaks to the outside.

It is clear that the amount of protective gas consumed will therefore increase.

On the other hand, in this method, scavenging before starting the motor can be easily performed because the protective gas flows out from the gap A.

In addition, in the method shown in Figure 2, the pressurized internal protective gas is 1
It is possible to considerably suppress the amount of leakage by a so-called labyrinth method in which the gas leaks from the gap C and is depressurized by the air tank 2, and this process is repeated alternately.

This means that it is quite difficult to scavenge the inside of the motor.

In other words, there is a regulation that requires the motor to be started only after the inside of the motor and the ventilation pipes connected to it have been purged with a protective gas of at least five times its internal volume. Therefore, it takes a long time to scavenge to satisfy this regulation.

Furthermore, in the method shown in FIGS. 1 and 2, if the electric motor uses a sliding bearing, the gaps A and C are
In consideration of bearing wear, it is necessary to increase the values of gaps A and C accordingly, which increases the consumption of protective gas.

As described above, the conventional method suffers from drawbacks in the amount and control of the protective gas consumption of the internal pressure explosion-proof motor and in the ease of scavenging.

The present invention was developed in view of these circumstances, and is intended to suppress the consumption of protective gas from the shaft penetration part of one motor in ventilated and sealed internal pressure explosion-proof motors, and to do so without impairing the ease of scavenging. It is an object of the present invention to provide an improved shaft sealing device that does not have the above-mentioned drawbacks by applying the function of the internal pressure explosion-proof structure to a liquid tank.

The present invention will be explained below based on an embodiment shown in FIGS. 3 and 4.

That is, a collar 12 is fitted into the motor shaft 1.

This collar 12 is installed in a liquid sealing box 13, and this liquid sealing box 13 is formed in a cylindrical shape with both ends closed, and is installed to maintain an appropriate gap E with the motor shaft 1 passing through it.

The inside of the liquid sealing box 13, that is, the space between it and the collar 12, is filled with an appropriate amount of sealing liquid 14.

The liquid sealing box 13 is provided inside a cylindrical liquid tank 6 with both ends closed, and the space between the liquid tank 6 and the liquid sealing box 13 is filled with cooling liquid 5.

A liquid level type 10 and a liquid injection port 11 are attached to the liquid tank 6.

The motor shaft 1 rotatably passes through the liquid tank 6, and the peripheral edge of one end is attached to the motor main body 9.

A separator plate 15 is provided between the outer surface of the liquid sealing box 13 and the inner surface of the liquid tank 6 to divide the inside into two in the axial direction, dividing the interior into two air chambers A and A, which are airtightly isolated. It is made into a structure.

At the lower part of the separator 15, where it is submerged in the cooling liquid 5,
Several circulation holes 24 are provided.

In addition, the liquid sealing box 13 has an outlet 1 related to the liquid level A1 and the liquid level B, as shown in FIG. 4 showing the X" mark in FIG.
and an inlet 8 are provided.

Next, the operation of the present invention will be explained.

That is, when the electric motor is operated now, the electric motor shaft 1 and the collar 12 fitted thereto rotate.

Then, the liquid filled in the liquid sealing box 13 is pushed outward by centrifugal force, that is, against the inner surface of the liquid sealing box 13.

On the other hand, the pressure difference between the inside and outside of the electric motor is expressed by the following formula (% formula %) (where P: pressure difference between inside and outside - Aq) rl, r2
is the distance (m) from the axis center to the liquid surface, J is the rotational angular velocity of the liquid g = 9.8m/5ec2, and B is assumed to be 1/2 of the rotational angular velocity ω of the normal collar.

Here, ΔP is the value stipulated in the above-mentioned branch guidelines (the pressure inside the motor is 5 mins or more higher than the outside) in the case of ventilated-type and enclosed-type internally pressured explosion-proof motors as mentioned above. Assuming a pressure difference that satisfies (pressure), determine %r and r.

These r' and r2 correspond to positions within liquid level A and liquid level B, respectively.

Further, the liquid sealing box 13, the liquid tank 6, and the space are sealed by the separating plate 15 and the cooling liquid 5.

As a result, leakage of the protective gas supplied into the motor from the protective gas supply device 22 (not shown) can be completely eliminated.

Furthermore, if the same sealing liquid 14 is rotated for a long period of time, the temperature of the liquid will rise due to frictional heat.

Therefore, in the present invention, in order to reduce the temperature rise of this liquid, the sealing liquid 14 is cooled by the following structural action without impairing the shaft sealing function of the shaft penetrating portion.

First, the distance r1 from the axis center to the liquid level A and the distance r2 from the axis center to the water surface B, calculated and determined from the above l (formula), can be assumed by calculation in advance.

Based on these rl and r2 dimensions, the liquid sealing box 13
Then, as shown in FIG. 4, the inlet 8 for one liquid is processed as follows.

That is, the N outlet T is provided by drilling several holes above the water level C of the cooling liquid 5 at a position slightly apart from the axial center than the liquid level A of the sealing liquid.

The inflow ports 8 are provided by drilling several holes below the liquid level of the cooling liquid 5 at a position slightly axially centered from the liquid level B of the sealing liquid 14 and below the liquid level C of the cooling liquid 5.

By doing so, the coolant 5 flows into the liquid sealing box 13 from the inlet 8 provided below the coolant level C.

On the other hand, the inflowing liquid naturally flows out from the outflow lower and returns to the cooling liquid 5 for circulation.

Through this circulation of the sealing liquid 14 and the cooling liquid 5, it is possible to cool the sealing liquid 14 whose temperature has increased due to the frictional heat of the collar 12.

Here, a sufficient amount of the cooling liquid 5 is required for cooling the frictional heat between the sealing liquid 14 and the collar 12, and the dimensions of the liquid tank 6 are determined to satisfy this requirement.

This liquid tank 6 is provided with cooling fins 23, which are designed to promote natural heat radiation to the outside and further improve the cooling effect of the cooling liquid 5.

When the electric motor stops operating, the centrifugal force exerted by the collar 12 disappears, and the sealing liquid 14 flows into the liquid sealing box 13.
It accumulates at the bottom of the.

The upper half or more of the liquid sealing box 13 is now empty.

On the other hand, according to the transformer guidelines, before starting the motor, scavenging (clean air or other protective gas is introduced into the motor)
It is currently determined that the electric motor can be started at 1 vJ after the explosive gas in the container and the ventilation pipes has been sufficiently exhausted.

This scavenging is performed in the present invention as follows.

First, the protective gas supplied from the protective gas supply device 22 (not shown) scavenges the inside of the motor body 9, passes through the gap E, passes through the inside of the liquid sealing box 13, and passes through the other gap E. Scavenges air by flowing outside.

At this time, the gap E has nothing to do with the function of the shaft seal, so a large gap can be overcome.

Therefore, scavenging can be performed in a short period of time. As described above, according to the present invention, during operation of the electric motor, the collar (rotating collar) is rotated inside the liquid sealing box, and the pressure of the centrifugal force of the liquid sealed inside the collar is used to release the protective gas inside the electric motor. leakage can be prevented.

Further, while the electric motor is not in operation, scavenging can be performed completely by taking advantage of the above-mentioned loss of centrifugal force.

Furthermore, the temperature rise due to frictional heat of the sealing liquid is controlled by adjusting the position of each liquid level of the cooling liquid and sealing liquid filled in the liquid tank provided at the bottom of the liquid sealing box, and the pressure difference between the inside and outside of the motor. By using this system, cooling fluid and sealing fluid can be circulated and automatically and continuously cooled.

It is possible to provide a shaft sealing device for a shaft penetrating portion of an electric motor having an internal pressure explosion-proof structure, which has various effects such as the following.

[Brief explanation of the drawing]

FIGS. 1N and 2 are vertical cross-sectional views showing a conventional shaft sealing device for a shaft penetrating portion. FIG. 3 is a vertical cross-sectional view of a shaft sealing device for a shaft penetrating portion showing an embodiment of the present invention. The figure is a sectional view taken along the line XX shown in FIG. 3. 1... Electric motor shaft, 2... Air tank, 3...
...Side plate, 4...Lahirinth, 5...
... Cooling liquid, 6 ... Liquid tank, 1 ... Outlet, 8 ... Inlet, 9 ... Motor body, 10 ... ...Liquid level gauge, 11...Liquid inlet,
12...Color, 13...Liquid sealed box,
14... Sealing liquid, 15... To the separator plate 2
2...Protective gas supply device, 23...Cooling fins, 24...Excessive curved flow.

Claims (1)

[Scope of utility model registration request] A cylindrical liquid tank with a motor shaft rotatably passing through both closed ends, the peripheral edge of one end being attached to the motor body, and a groove with an appropriate amount of cooling liquid in the lower half; A liquid injection port provided near the other end of the upper half, and a cooling liquid flow port provided in the inner periphery of the liquid tank to divide the upper half into two air chambers and the lower half. The motor shaft passes through the separator formed by the separator and both closed end portions of the cylindrical shape with a gap in between, and the cylindrical portion is supported by the separator plate, and the coolant is applied to the lower half of the end on the motor main body side. A plurality of inlets are provided at positions slightly closer to the center of the motor shaft than the liquid level, and a plurality of outlets are provided at positions slightly closer to the center of the motor shaft than the inlets at the upper part of the other end. A liquid sealing box consisting of a liquid sealing box, an appropriate amount of cooling liquid sealed inside the liquid sealing box by flowing in from the inlet and flowing out from the outlet; A shaft sealing device for an electric motor with an internal pressure explosion-proof structure, consisting of a collar that forces the coolant contained inside a liquid sealing box.