JP2000027795A - Rotary shaft sealing device for centrifugal blower - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotary shaft sealing device for centrifugal blower capable of facilitating the assembling without receiving the influence of the vibration of a casing. SOLUTION: A static part of a rotary shaft sealing device 10a provided between a casing 2 and a rotary shaft 3 of a centrifugal blower is held by a bearing part 6 of the rotary shaft 3, and a displacement between the static part and a rotary part is eliminated so as to facilitate the assembling of the rotary shaft sealing device 10a. A clearance between the static part of the rotary shaft sealing device 10a and the casing 2 is sealed by a flexible plate 43 so as to prevent the transmission of the vibration of the casing 2 to the rotary shaft sealing device 10a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a rotary shaft sealing device for a centrifugal blower for sealing between a casing and a rotary shaft.

[0002]

2. Description of the Related Art FIG. 2 is a side sectional view of a centrifugal blower to which the present invention is applied. In the centrifugal blower 1, the casing 2
An impeller 4 is attached to the front end of the rotating shaft 3 that penetrates the
The rotating shaft 3 is rotatably supported by a bearing 6 on a gantry 5 and is rotationally driven by a motor 7 connected to a rear end. By the rotation of the impeller 4, gas is sucked into the casing 2 from the suction port 8 and discharged from the discharge port 9, and accordingly, a pressure difference is generated inside and outside the casing 2. Therefore, a rotating shaft sealing device 10 is provided between the casing 2 and the rotating shaft 3 to prevent gas from leaking from the casing 2.

The centrifugal blower 1 has many similarities in configuration to a centrifugal pump for transferring a liquid. However, the centrifugal blower 1 for transferring a gas is generally larger than a centrifugal pump, and the pressure of the transferred gas is low. Therefore, the casing 2 is made of a thin steel plate that is bent and welded, or a lightweight member such as an FRP molded product is used almost without machining. The rotary shaft sealing device 10 also has a simpler configuration than a centrifugal pump.

FIGS. 3 to 5 are side sectional views of a rotary shaft sealing device usually used for the centrifugal blower 1. FIG. The rotary shaft sealing device 10b shown in FIG. 3 extends rearward from the impeller 4 and prevents leakage of gas from the casing 2 with one seal plate 12 slidingly contacting the outer surface of a shaft sleeve 11 coaxial with the rotary shaft 3. This is the simplest configuration of the rotary shaft sealing device.

The impeller 4 has a metal boss 13 embedded therein.
It is an RP molded product, a tapered hole 14 is provided at the center of the boss 13, and the shaft sleeve 11 extends rearward integrally with the impeller. Insert the tapered portion 15 of the rotating shaft into the tapered hole 14 of the impeller 4, tighten it with the nut 18 of the screw portion 17 at the tip of the rotating shaft via the washer 16, cover the nut cover 19, and rotate the rotating shaft 4 The power of the rotating shaft 3 is transmitted to the impeller 4 by the key 20.

The seal plate 12 is a synthetic resin plate such as polypropylene, and the inner end surface is machined to have the same diameter as the outer peripheral surface of the shaft sleeve 11. Insert this seal plate 12 into the shaft sleeve 11,
The shaft sleeve 11 is fixed to the outer end surface of the flange 21 of the casing opening via a gasket 22 with a holding plate 23 and bolts 24.
A gas cutting ring 25 is attached to the rear end of the rotary shaft sealing device 10
b is assembled. Initially, the inner end surface of the seal plate 21 is in light contact with the outer peripheral surface of the shaft sleeve 11, but
The inner end surface of the seal plate 12 wears due to sliding during operation, and a narrow gap is formed between the seal plate 12 and the shaft sleeve 11. for that reason,
In this rotary shaft sealing device 10b, gas leakage occurs in proportion to the width of the gap and the pressure difference before and after the gap.

A rotary shaft sealing device 10c shown in FIG. 4 is obtained by forming a labyrinth seal by using a plurality of seal plates 12 of the rotary shaft sealing device 10b of FIG. In the embodiment shown in FIG. 4, three seal plates 12 are provided with a spacer 26 interposed therebetween. In the labyrinth seal, since a plurality of gaps are present at intervals, the pressure difference before and after each gap is small, and the amount of gas leakage is reduced as compared with the rotary shaft sealing device 10b having one gap.

The rotary shaft sealing devices 10b and 10c shown in FIGS.
Is a non-contact type shaft sealing device having a gap between the seal plate 12 and the shaft sleeve 11, and therefore cannot completely prevent gas leakage from the casing 2. Therefore, when a harmful component or a malodorous component is contained in the gas to be transferred and a small amount of leakage occurs, a water seal type rotary shaft sealing device 10d shown in FIG. 5 is used.

A water seal type rotary shaft sealing device 10d shown in FIG. 5 includes a ground box 27 and a ground cover 28 which are stationary members.
Form an annular groove 29, and the disk 31 portion of the rotor 30, which is a rotation-side member, rotates in the annular groove 29. Since there is a gap between the annular groove 29 and the disk 31, the water-sealed rotary shaft sealing device 10d is also a non-contact type shaft sealing device, but water is injected into the annular groove 29, and together with the disk 31 during operation. The rotating water fills the gap between the disc 31 over the entire circumference of the annular groove 29 by its centrifugal force,
With this water, gas leakage from the casing 2 can be completely prevented.

A rotor 30 as a rotating side member is sandwiched between a distance piece 32 and a drain plate 33 on a rotating shaft 3, and these are fastened to the impeller 4 by fastening nuts 34 and fixed to the rotating shaft 3. ing. The ground box 27 and the ground cover 28, which are stationary members, are connected with bolts 35,
The outer peripheral portion of the ground box 27 is fixed to the outer end surface of the flange 21 at the opening of the casing with a bolt nut 36.
A drain catcher 37 for holding water overflowing from the annular groove 29 when the operation is stopped is provided on a rear surface of the ground cover 28, and a lip seal 39 of the drain catcher 37 and the rotor 30 is provided.
Prevents water leakage to the outside. Drain catcher
A water supply / discharge port 38 (only one is shown) is provided at the bottom of 37, and water for sealing is always supplied.

On the front surface of the ground box 27, the three seal plates 12 form a labyrinth seal 40 between the outer peripheral surfaces of the distance pieces 32 so that a large leak from the casing 2 does not occur even without sealing with water. I have to.

In addition to the water-sealed rotary shaft sealing device 10d, contact-type rotary shaft sealing devices generally used in centrifugal pumps such as gland packing seals and mechanical seals are also provided.
All can be used as a rotary shaft sealing device of a centrifugal blower.

[0013]

When the above-mentioned water seal type rotary shaft sealing device or the like is used as the rotary shaft sealing device of the centrifugal blower, the perpendicularity and concentricity of the stationary side member with respect to the rotating side member are considered. Therefore, it is necessary to machine the outer end surface of the casing opening flange using a machine tool. In addition, centering adjustment at the time of assembly is also required. However, the casing of a centrifugal blower uses a thin steel plate that is bent and welded, or a lightweight member such as an FRP molded product with almost no machining. When the casing becomes large, the machining becomes large.

Further, since the casing of the centrifugal blower does not have the rigidity of the casing of the centrifugal pump, if the casing generates vibrations due to pressure fluctuations in the casing due to a change in the flow rate or the like, the above-mentioned water-sealed rotary shaft seal is required. In the device, the gland box and the gland cover fixed to the casing may vibrate together with the casing, and the annular groove may come into contact with the disk. Even in a contact-type rotary shaft sealing device such as a gland packing seal or a mechanical seal, the vibration of the stationary-side member with respect to the rotary-side member affects the sealing performance and life of the rotary shaft sealing device.

In the above-mentioned water-sealed rotary shaft sealing device, the ground box and the ground cover forming the stationary-side annular groove have a configuration in which the rotating-side disc is sandwiched in the axial direction. Since the gland box is held by the casing, the stationary members are suspended in the air until the gland box is fixed to the casing.After the gland box is fixed to the casing, the stationary members are separated from both sides of the casing. Since it needs to be attached, it takes time to assemble.

An object of the present invention is to provide a rotary shaft sealing device of a centrifugal blower which is not affected by the vibration of a casing and can be easily assembled.

[0017]

According to the present invention, there is provided a rotary shaft sealing device for a centrifugal blower, wherein a stationary portion of the rotary shaft sealing device is held at a position separated from a casing, and the rotary shaft sealing device is stationary. The gap between the portion and the casing is sealed with a flexible plate.

According to this structure, the stationary portion of the rotary shaft sealing device is not displaced with respect to the rotary portion, and even if vibration occurs in the casing, the flexible plate absorbs the vibration and affects the rotary shaft sealing device. Absent.

According to the second aspect of the present invention, the stationary portion of the rotary shaft sealing device is held by the bearing portion of the rotary shaft. According to this configuration, since both the rotating part and the stationary part of the rotary shaft sealing device are held by the bearing part of the rotating shaft, the rotating part and the stationary part are not displaced and the assembly is easy.

According to a third aspect of the present invention, the stationary portion of the rotary shaft sealing device is formed by a plurality of ribs having a mounting seat at a distal end and a proximal end fixed to a bearing cover.
It is held by the bearing part.

If the stationary portion of the rotary shaft sealing device is held by the bearing cover via about three ribs, the ribs do not hinder the operation, and the stationary portion can be easily assembled. The rotary shaft sealing device is a water-sealed rotary shaft sealing device.
According to the invention described above, it is easy to assemble the stationary portion forming the annular groove with the rotating-side disk interposed therebetween.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG.

The rotary shaft sealing device 10a of the present invention shown in FIG.
Since the centrifugal blower 1 shown in FIG. 2 incorporates the water-sealed rotary shaft sealing device 10d shown in FIG. 5, the same members as those shown in FIGS. explain.

As shown in FIG. 1, the rotary shaft sealing device of the present invention
10a is that the stationary main member is a ground box 27 and a ground cover 28 forming an annular groove 29, and the rotating main member is a disk 31 rotating in the annular groove 29.
In common with the water-sealed rotary shaft sealing device 10d shown in FIG.

However, in the rotary shaft sealing device 10a of the present invention, a plurality of ribs 41 are provided on the bearing cover 6a of the bearing portion 6 of the rotary shaft 3.
(For example, three pieces) are welded, the stationary portion of the rotary shaft sealing device 10a is held on the mounting seat 42 at the tip of the rib, and the space between the stationary portion and the casing 2 is a flexible material such as rubber or fluororesin. Sealed with a conductive plate 43. As for the rotating part of the rotating shaft sealing device 10a, the draining plate 33, the rotor 30, and the distance piece 32 are sandwiched between the impeller 4 and the tightening nut 34, and the rotating shaft 3
It is fixed to.

At the time of assembling the rotary shaft sealing device 10a, first, the draining ring 33 is inserted from the tip of the rotary shaft 4, and the ground cover 28 is fixed to the mounting seat 42 with bolts or the like. Then rotor 30
And the distance piece 32 are inserted into the rotating shaft 3, and the ground box 27 is fixed to the ground cover 28 with bolts 35.
The labyrinth seal 40 is formed between the seal plate 12 and the distance piece 31 by attaching the seal plate 12 to the ground box 27, and the stationary part of the rotary shaft sealing device 10a is assembled. After the stationary part is assembled, the ground box 28 and the casing 2
Is sealed with a flexible plate 43. And finally,
The impeller 4 is inserted into the tip of the rotating shaft 3 from the inside of the casing 2, and the cap nut 45 is screwed into the threaded portion 44 at the tip of the rotating shaft, so that the assembly of the rotating shaft sealing device 10 a and the mounting of the impeller 4 are completed. .

[0027]

As described above, the rotary shaft sealing device 10 of the present invention
In a, the stationary portion is held via the rib 41 fixed to the bearing cover 6a, and the members on the stationary side and the rotating side can be assembled in order from the bearing side toward the tip of the rotating shaft. The assembly becomes easier and the assembly time is shortened as compared with the water-sealed rotary shaft sealing device 10d.

Since both the stationary part and the rotating part of the rotating shaft sealing device 10a are held by the bearing part 6 of the rotating shaft,
No force is exerted to displace each part. Since the gap between the stationary portion and the casing 2 is sealed by the flexible plate 43, the vibration of the casing 2 is absorbed by the flexible plate 43, and the vibration is not transmitted to the ground box 27. And the disk 31 do not come into contact with each other. Further, it is not necessary to machine the outer end surface of the flange 21 of the casing opening.

This mounting structure can be applied to a case where a rotary shaft sealing device such as a gland packing seal or a mechanical seal is incorporated in a centrifugal blower. Since the vibration of the casing is not transmitted, the function of the rotary shaft sealing device is maintained. As a result, the life can be extended. Note that this mounting configuration is not limited to the above-described centrifugal blower, and can be applied to all rotating machines in which vibrations occur in the penetrating portions of the rotating shaft.

[Brief description of the drawings]

FIG. 1 is a side sectional view of a rotary shaft sealing device of a centrifugal blower according to the present invention.

FIG. 2 is a side sectional view of a centrifugal blower to which the present invention is applied.

FIG. 3 is a sectional view of a rotary shaft sealing device using a seal plate.

FIG. 4 is a sectional view of a labyrinth seal having a plurality of seal plates of the rotary shaft sealing device of FIG. 3;

FIG. 5 is a side sectional view of a water-sealed rotary shaft sealing device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Centrifugal blower 2 ... Casing 3 ... Impeller 4 ... Rotating shaft 6 ... Bearing part 6a ... Bearing cover 10, 10a, 10b, 10c, 10d ... Rotating shaft sealing Device 21 ・ ・ ・ Casing opening flange 27 ・ ・ ・ Ground box 28 ・ ・ ・ Ground cover 29 ・ ・ ・ Circular groove 30 ・ ・ ・ Rotor 31 ・ ・ ・ Disc 41 ・ ・ ・ Rib 42 ・ ・ ・ Mounting seat 43 ・ ・ ・ Flexible plate 44 ・ ・ ・ Screw part 45 ・ ・ ・ Cap nut

Claims (4)

[Claims] 1. A rotary shaft sealing device for sealing between a casing and a rotary shaft of a centrifugal blower, wherein a stationary portion of the rotary shaft sealing device is held at a position separated from the casing, and a stationary portion of the rotary shaft sealing device is provided. A rotary shaft sealing device for a centrifugal blower, wherein a gap between the casing and the casing is sealed with a flexible plate. 2. The rotary shaft sealing device according to claim 1, wherein a stationary portion of the rotary shaft sealing device is held by a bearing portion of the rotary shaft. 3. The shaft sealing device according to claim 2, wherein the stationary portion of the rotary shaft sealing device is held at the bearing portion by a plurality of ribs having a mounting seat at a distal end and a base end fixed to the bearing cover. 4. The shaft sealing device according to claim 1, wherein the rotary shaft sealing device is a water-sealed rotary shaft sealing device.