JPH1162888A - Seal structure of axial fan - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a seal structure of an axial fan, capable of preventing the generation of the air flow in a bearing by a relative simple structure, avoidable in the conventional structure, capable of preventing oil leakage to be generating caused by the generation of the air flow in the bearing, and capable of drastically improving reliability of equipment. SOLUTION: In a seal structure of an axial fan, in which a main bearing 3 is arranged in an inner cylinder 4, a seal gas chamber 8 formed of the main bearing 3 and the inner cylinder 4 is extended toward an electric motor side to increase the capacity, an electric motor side seal part 10 for partitioning the seal gas chamber 8 from the atmosphere side is so provided as to be separated from an oil thrower part 11 of the main bearing 3, and the shape of the oil thrower part 11 of the main bearing 3 is so formed as to be symmetric on the right and left sides.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seal structure applied to an axial fan.

[0002]

2. Description of the Related Art In a conventional axial flow fan, a gas seal portion is provided near a bearing box, and the bearing box is sealed by the gas seal portion. However, in such a bearing box, oil leakage was caused by pressure fluctuation caused by the seal gas and the fan gas. Therefore, a seal structure shown in FIGS. 3 and 4 is employed as a seal structure in a conventional axial flow fan. In this sealing structure, the sealing gas (seal air) is filled between the rotating body 53 of the inner cylinder 52 including a part of the main bearing 51 and the sealing gas partition plate 54 on the end face of the main bearing 51 as shown by an arrow A. Then, the gas is introduced into the main bearing 51 through the gas passage 51a, and one of the rotating body side seal portion 55 and the oil drain portion 51b of the main bearing 51 becomes the electric motor side seal portion 56 to be gas-sealed. Is configured. Therefore, the oil drain portion 51b of the main bearing 51
Is asymmetrically formed on both the left and right sides as shown in FIG.

In the drawings, reference numeral 57 denotes a main shaft rotatably supported by the main bearing 51, 58 denotes a coupling connected to the main shaft 57, and 59 denotes a seal gas defined by the inner cylinder 52 and the seal gas partition plate 54 and the like. The chamber 60 is an outer cylinder disposed outside the inner cylinder 52. Arrow B indicates the motor side, and arrow C indicates the gas flow.

[0004]

However, in the conventional seal structure, one of the oil drain portions 51b of the main bearing 51 is a gas seal portion 56, and a pressure difference is generated between the inside and the outside of the main bearing 51. There is a problem in that an airflow is generated due to the uneven sealing gas pressure, and the lubricating oil leaks from the oil drain 51b to the outside accordingly, causing oil leakage. This is because if the pressure applied to each of the oil drain portions 51b of the main bearing 51 is different, a gas flow is generated inside the main bearing 51.

[0005] The oil spill due to this oil leak is several cc per day in a minor case, but several liters per day in a serious case, and several hundred liters per year. As a result, there is a possibility that the oil level of the oil tank of the oil supply device may be reduced and the oil may be depleted. In addition, the leakage of the lubricating oil reduces the amount of oil on the lubricating oil surface, causing poor lubrication, and in the worst case, depleting the lubricating oil and damaging the bearing.

On the other hand, the oil that has flowed out is transported further downstream from the fan outlet by the gas flow inside the fan, so that the inside of the duct, equipment such as an air heater and an electric dust collector, and the like are widely contaminated. Normally, the interval for periodic inspections of thermal power plants, etc. is 1 to 1.5 years, so it is necessary to clean or replace contaminated parts at each periodic inspection. Regular inspections can cost tens of millions of yen and require enormous repair costs.
Moreover, in some cases, it may cause a disaster due to pollution. In addition, high temperature (200 to 300
Oil spills on equipment operating under (° C) can cause fires and significantly reduce equipment reliability.

The present invention has been made in view of such circumstances, and has as its object to prevent the inevitable generation of airflow inside a bearing in a conventional structure with a relatively simple structure.
An object of the present invention is to provide a seal structure for an axial fan which can prevent oil leakage caused by this and can greatly improve the reliability of equipment.

[0008]

According to the present invention, there is provided a seal structure for an axial flow fan in which a main bearing is disposed in an inner cylinder. Along with extending the seal gas chamber defined by and toward the electric motor, its capacity is increased, and a seal portion for separating the seal gas chamber from the atmosphere side is provided apart from the oil drain portion of the main bearing. Further, the shape of the oil drain portion of the main bearing is formed symmetrically on both left and right sides. That is, the seal structure of the axial fan of the present invention eliminates the seal gas partition plate conventionally provided between the inner cylinder and the main bearing, and also serves as a gas seal at the oil drain portion of the main bearing. The seal is provided on the intermediate shaft between the main shaft and the electric motor.

In the seal structure of the axial fan according to the present invention, since the oil drain portion of the main bearing is in a state of being equalized on both left and right sides by the same pressure of the seal gas, the oil drain portion is formed at the oil drain portion. Generation of airflow is eliminated, and leakage of lubricating oil from the main bearing to the outside can be prevented. In addition, the original gas sealing function is not impaired.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on illustrated embodiments. Here, FIG. 1 is a sectional view showing an internal structure of an axial fan for a thermal power plant according to an embodiment of the present invention, and FIG. 2 is an enlarged sectional view thereof.

An axial fan according to an embodiment of the present invention comprises:
A main shaft 2 to which a rotating body 1 is attached at one end, a main bearing 3 for rotatably supporting an intermediate portion of the main shaft 2, an inner cylinder 4 in which the main bearing 3 is housed and arranged, and an inner cylinder 4 And rotating body 1
And an outer cylinder 5 provided on the outer periphery of the outer cylinder. The other end of the main shaft 2 is connected to a drive shaft of an electric motor (not shown) via a coupling 6, and the drive shaft drives the coupling 6, the main shaft 2 and the rotating body 1 to rotate. When the rotating body 1 rotates, the gas flowing in the duct 7 is carried downstream from the fan outlet.

Therefore, both ends of the coupling 6
Flanges 6a and 6b are formed, the main shaft side flange 6a is connected to the flange 2a of the main shaft 2, and the motor side flange 6b is connected to a drive shaft of a motor (not shown). The duct 7 is formed between the inner cylinder 4 and the outer cylinder 5. In the figure, arrow A indicates the flow of seal gas (seal air), arrow B indicates the motor side, and arrow C indicates the flow of gas.

On the other hand, between the main bearing 3 and the inner cylinder 4,
A seal gas chamber 8 defined by these members is provided. The sealing gas chamber 8 is extended toward the electric motor side as compared with the related art, whereby the volume of the sealing gas chamber 8 is increased. Therefore, the seal gas is supplied into the inner cylinder 4 including the main bearing 3, that is, into the seal gas chamber 8, and the gas is supplied to the rotating body side seal portion 9 and the electric motor side seal portion 10 located on both sides of the seal gas chamber 8. It is designed to be sealed.

The rotating body side seal portion 9 is provided at a clearance between the projecting piece 1a of the rotating body 1 and the tip of the protruding strip 4a of the inner cylinder 4. The overhanging piece 1a protrudes from the side end surface of the rotating body 1 toward the seal gas chamber 8, and the protruding strip 4a is
Are protruded from the inner peripheral surface toward the seal gas chamber 8, and both pieces are arranged in a direction crossing each other. Further, the motor-side seal portion 10 is provided at a clearance between the tip of the bent portion 4b of the inner cylinder 4 that covers the vicinity of the motor-side flange 6b of the coupling 6 and the outer peripheral surface of the coupling 6, and The seal gas chamber 8 is separated from the atmosphere by a motor-side seal portion 10. Therefore, the motor-side seal portion 10 is provided at a position away from an oil drain portion of the main bearing 3 described later.

On the left and right sides of the inner peripheral surface of the main bearing 3,
Oil drains 11 are respectively provided facing the outer peripheral surface of the main shaft 2, and these oil drains 11 are formed in a wedge shape that is symmetrical on both the left and right sides along the axial direction of the main shaft 2, and are used to seal gas. The pressure applied to the oil draining section 11 is kept uniform on both the left and right sides. That is, there is no pressure difference between the inside of the main bearing 3 and the outside of the main bearing 3 (the seal gas chamber 8), or the outside of the main bearing 3 is more positive than the inside. A lubricating oil (not shown) is sealed inside the main bearing 3, and the seal gas is supplied between the outer peripheral surface of the main shaft 2 and the oil drain 11 of the main bearing 3 as shown by an arrow A in FIG. It is supplied to the gap.

In the seal structure according to the embodiment of the present invention, the capacity of the seal gas chamber 8 is increased,
The motor-side sealing portion 10 for sealing the air and the atmosphere side is
By separating from the oil drain 11 provided in the
Even if an airflow is generated in the motor-side seal portion 10 due to a pressure difference from the atmosphere, the airflow does not affect the oil drain portion 11 of the main bearing 3. Further, the oil drain portion 11 of the main bearing 3 is formed symmetrically on both the left and right sides, and since the pressure of the seal gas is the same on both the rotating body side and the electric motor side, no air flow is generated, and therefore, the oil flow is not generated. No leakage occurs.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications and changes may be made without departing from the gist of the present invention. What you get.

[0018]

As described above, in the seal structure for an axial fan according to the present invention, the main bearing is disposed in the inner cylinder, and the seal gas chamber defined by the main bearing and the inner cylinder is formed. Along with extending toward the electric motor, the volume is increased, and a seal portion for separating the seal gas chamber and the atmosphere side is provided apart from the oil drain portion of the main bearing, and an oil drain portion of the main bearing is provided. The shape is formed symmetrically on both the left and right sides. Therefore, according to the seal structure of the axial flow fan of the present invention, the following effects can be obtained. (1) With a relatively simple structure, repair costs in the case of contamination caused by oil spill, which were required in the prior art, become completely unnecessary, and costs can be reduced. Further, the reliability of the fan body and other devices can be greatly improved. (2) As a facility for a thermal power plant that requires high reliability, it also prevents user complaints and is of great significance.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a seal structure of an axial fan according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view showing a main part of a seal structure of the axial fan in FIG. 1;

FIG. 3 is a sectional view showing a conventional axial fan sealing structure.

FIG. 4 is an enlarged sectional view showing a main part of a seal structure of the axial fan in FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rotating body 2 Main shaft 3 Main bearing 4 Inner cylinder 5 Outer cylinder 6 Coupling 8 Seal gas chamber 9 Rotating body side seal part 10 Motor side seal part 11 Oil drain part

Claims (1)

[Claims] In a seal structure of an axial fan in which a main bearing is disposed in an inner cylinder, a seal gas chamber defined by the main bearing and the inner cylinder is extended toward an electric motor so as to extend the seal gas chamber. A seal part that separates the seal gas chamber from the atmosphere side is provided apart from the oil drain part of the main bearing, and the shape of the oil drain part of the main bearing is formed symmetrically on both the left and right sides while increasing the volume. An axial flow fan sealing structure characterized by