JP3016766B1 - Shaft sealing device - Google Patents

Abstract

Kind Code: A1 A gap between a stationary shaft and a rotating body driven to rotate about the stationary shaft is reliably sealed with low dust generation regardless of the rotational speed of the rotating body. The present invention provides a shaft sealing device that can be used. An externally pressurized non-contact seal is interposed between a stationary shaft and a rotating body. A second gas supply path 5 is provided inside the stationary shaft 1, and the rotary seal ring of the non-contact seal 4 is passed through the second gas supply path 5 and the first gas supply path 44 of the non-contact seal 4. The sealing gas is supplied to the minute gap S between the stationary sealing ring 42 and the stationary sealing ring 42.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for rotating a rotary shaft about a stationary shaft, such as a conical dryer, a dryer, a stirrer, and a centrifugal separator. The present invention relates to a shaft sealing device for sealing a gap between them.

[0002]

2. Description of the Related Art Conventionally, a contact type mechanical seal or a gland packing has been mainly used for sealing a gap between the stationary shaft and the rotating body. However, it is difficult to reliably prevent leakage of a processing object such as a powder or a fluid contained in the rotating body over a long period of time by sealing with these sealing devices. In addition, these seal devices generate a large amount of abrasion powder due to the sliding of the seal part, and require cleaning of the device for each batch, removal of dust attached to the product, and low dust generation. However, there is a problem that the method cannot be applied to sealing of a device for handling medicines, foods and the like.

[0003] Such a problem is caused by preventing the heat generation of both sealed end faces while preventing the slurry component and dust from staying near the respective sealed end faces of the rotating seal ring and the stationary seal ring opposed to each other. And a contact type mechanical seal of a type in which slurry components and dust are removed from near the sealing end face by a pumping action of a screw seal (for example, Japanese Utility Model Publication No. 63-32).
461) can be solved. However, when this mechanical seal is applied to a device that is operated at a low rotation speed of less than 500 rpm, a lubricating effect due to the pumping action of the sealing fluid cannot be expected on the sealing end face, which is a sliding face, so that the sealing end face is not applicable. In addition to the possibility of increased wear and seizure of the slurry, the pumping action of the screw seal cannot be expected, so that the discharge of the slurry fluid becomes impossible, which requires low dust generation and operates at a low rotational speed. It could not be applied to seal the device. The present invention has been made in view of the above-described problems, and has a structure in which the shaft side is stationary and the rotating body is 500 rpm.
It is an object of the present invention to provide a shaft sealing device that can reliably seal with low dust generation even if the device is operated at a low rotational speed less than that.

[0004]

According to the present invention, there is provided a shaft sealing device for sealing a gap between a stationary shaft and a rotating body driven to rotate about the stationary shaft. In the apparatus, a rotary sealing ring attached to the rotating body so as to be integrally rotatable, a stationary sealing ring attached to the stationary shaft and opposed to the rotating sealing ring with a small gap, provided on the stationary shaft side An externally pressurized non-contact seal having a first gas supply passage communicating with the minute gap, and a second supplying a seal gas to the first gas supply passage through the inside of the stationary shaft. (Claim 1). According to this shaft sealing device, the sealing gas can be supplied to the minute gaps between the sealing rings through the second gas supply path and the first gas supply path. Therefore, the space between the stationary shaft and the rotating body can be sealed without any trouble by the externally pressurized non-contact seal regardless of the rotation speed of the rotating body.

In the shaft sealing device, the externally pressurized non-contact seal includes a retainer for holding the stationary sealing ring movably in the axial direction, and forms a sealed space between the inner periphery of the retainer and the stationary shaft. Then, the first gas supply path and the second gas supply path may be communicated via the sealed space (claim 2). According to this shaft sealing device, the first gas supply path and the second gas supply path can be easily communicated.

According to a second aspect of the present invention, the sealed space is preferably formed between an annular groove provided along the inner periphery of the retainer and the stationary shaft. In this case, the sealed space can be formed without performing special processing on the stationary shaft side, and the sealed space and the first space can be formed.
It is not necessary to align the gas supply path and the second gas supply path in the circumferential direction. The shaft sealing device according to claim 2,
The first gas supply path may be formed inside a retainer and a stationary sealing ring (claim 4). In this case,
A piping member for the first gas supply path becomes unnecessary.

[0007]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 2 is a sectional view showing a case where the shaft sealing device A according to one embodiment of the present invention is applied to a conical dryer B. The conical dryer B includes an exhaust pipe 1 as a stationary shaft, and a tumbler 2 as a rotating body that is driven to rotate around the exhaust pipe 1.
And a bearing device 3 for rotatably supporting the exhaust tube 1 and the tumbler 2. A clearance between the exhaust tube 1 and the tumbler 2 is sealed by a shaft sealing device A.

The exhaust pipe 1 has a circular cross section, and one end thereof is introduced into the tumbler 2.
The intermediate portion is rotatably supported by the bearing device 3. This exhaust pipe 1 is for discharging the air inside the tumbler 2 to the atmosphere. The tumbler 2 is a conical hollow container for accommodating a processed material such as a powder. One end of the tumbler 2 is supported through a hollow support shaft 21 inserted into the outer periphery of the exhaust pipe 1 with a gap. The other end is rotatably supported by a bearing device (not shown). The hollow support shaft 21 has flanges 21a and 21b provided at both ends. One flange 21a is provided outside the tumbler 2 and the other flange 2a is provided.
1b are arranged inside the tumbler 2, respectively.
The tumbler 2 is normally driven to rotate at a rotation speed lower than 500 rpm. However, there is also a case where the motor is driven to rotate at a rotation speed exceeding 500 rpm.

The bearing device 3 has a bearing unit 31 fitted on the outer periphery of the exhaust pipe 1, a floating shaft 32 fitted on the outer periphery of the bearing unit 31, and a rotatable support for the floating shaft 32. And a plummer block bearing 33. The bearing unit 31 fits a pair of ball bearings 31b into the sleeve 31a fitted on the outer periphery of the exhaust pipe 1 with a predetermined distance between them. This is one in which an interval regulating member 31c is interposed.
The relative rotation between the sleeve 31a and the exhaust pipe 1 is restricted by a set screw 31d. The outer ring of each ball bearing 31b is fitted to the inner periphery of the floating shaft 32 so as to be integrally rotatable, and is prevented from being removed by a pair of locking rings 31e fitted to the inner periphery of the floating shaft 32. ing.

The floating shaft 32 is provided with a flange 32b for mounting the flange 21a of the hollow support shaft 21 at one end of a cylindrical body 32a. The cylindrical body 32a is provided inside a plummer block bearing 33. It is rotatably supported by the housing 33b of the plummer block bearing 33 via the self-aligning bearing 33a provided. A floating shaft 32 is provided at the boundary between the cylindrical body 32a and the flange 32b.
A drain hole 32c is formed on the inner and outer peripheries.

Referring also to FIG. 1, the shaft sealing device A includes an externally pressurized non-contact seal 4 and a second
And a gas supply path 5. The non-contact seal 4
Is a rotary sealing ring 41 that rotates integrally with the tumbler 2.
In a state in which the rotary seal ring 41 is opposed to the rotary seal ring 41 with a small gap S, and is supplied through a stationary seal ring 42 attached to the exhaust pipe 1 via a retainer 43 and the second gas supply path 5. First, the sealing gas to be introduced into the minute gap S
And a gas supply path 44. These rotary seal rings 4
1. The stationary sealing ring 42 and the retainer 43 are arranged concentrically with the exhaust pipe 1.

The rotary seal ring 41 is made of stainless steel (S
US304, SUS316) or the like, and is attached to the flange 21b of the hollow support shaft 21 via the flange 41a. A ceramic coating portion 41b for improving abrasion resistance is formed on a sealing end surface (seal surface) of the rotary sealing ring 41. O-rings P1 and P2 are provided between the rotary seal ring 41 and the flange 41a and between the flange 41a and the hollow support shaft 21.
Each is sealed. The stationary sealing ring 42
The retainer 43 is movably held in the axial direction, and is constantly elastically pressed toward the rotary seal ring 41 by a spring 45 interposed between the back surface of the retainer 43 and the retainer 43.

The retainer 43 is attached to the exhaust tube 1 via a sleeve 11 fitted around the end of the exhaust tube 1. The retainer 43 includes a cylindrical base 43a fitted on the outer periphery of the sleeve 11, a flange 43b protruding from the outer periphery of the base 43a, and a flange 43b.
b, and an annular seal case 43c attached to the ring seal case 43b. An annular groove 43d is formed on the inner periphery of the base 43a, and O-rings P for sealing between the sleeve 11 and both sides of the groove 43d.
The space surrounded by the concave groove 43d and the sleeve 11 is formed as an annular sealed space 6. The seal case 43c surrounds the outer periphery of the stationary sealing ring 42, and an annular space 48 sealed by a pair of O-rings P4 is provided between the inner periphery and the outer periphery of the stationary sealing ring 42. Have been.

The first gas supply path 44 has one end opening 44a.
And the other end opening 44b faces the inner bottom of the concave groove 43d of the retainer 43.
a, 44b, between the internal passages 44c of the stationary sealing ring 42,
Annular space 48, internal passage 44d of seal case 43c,
Inverted U-shaped metal tube 44e and internal passage 4 of base 44a
4f. The retainer 43 is connected to the exhaust pipe 1 by a set screw 44g.
Relative rotation of the stationary sealing ring 42 is restricted by the pin 42a.

The second gas supply path 5 is formed of a long metal pipe, and is introduced into the exhaust pipe 1 from the vicinity of the end of the exhaust pipe 1 on the atmospheric side. , Extends along the axis of the exhaust pipe 1 and is bent at a position inside the retainer 43 of the non-contact seal 4 so as to penetrate the exhaust pipe 1 in an airtight manner. It faces the sealed space 6. A sealing gas such as nitrogen gas is supplied from the tank T to the second gas supply path 5.

With the above structure, the seal gas supplied from the tank T to the second gas supply path 5 is supplied to the small gap between the rotary seal ring 41 and the stationary seal ring 42 through the first gas supply path 44. S, and the sealing gas is constantly released from the minute gap S to prevent the processing material such as powder inside the tumbler 2 from entering the sealing end face. Can be sealed. Therefore, the gap between the exhaust pipe 1 and the tumbler 2 can be reliably sealed for a long period of time. In addition, since the sealing end face is non-contact, low dust generation can be ensured regardless of the rotation speed of the tumbler 2, so that the inside of the tumbler 2 can be cleaned for each batch, and dust adhered to the processed material can be removed. In addition to the necessity of the operation of removing, it is possible to dry medicines and foods that require low dust generation without any trouble.

The shaft sealing device A includes a first gas supply passage 44.
And the second gas supply path 5 are communicated with each other via the sealed space 6 between the retainer 43 and the exhaust pipe 1, so that both can be easily communicated without using a piping connector or the like. In addition, since the sealed space 6 is formed between the concave groove 43d provided along the inner circumference of the retainer 43 and the sleeve 11 of the exhaust cylinder 1, special processing is performed on the exhaust cylinder 1 side. Without forming a sealed space 6. Therefore, the shaft sealing device A can be easily applied to the existing conical dryer B. Moreover, the concave groove 43d
Is annular, and the sealed space 6 can be formed over the entire circumference of the exhaust pipe 1. Therefore, there is no need to align the sealed space 6 with the first gas supply path 44 and the second gas supply path 5 in the circumferential direction. . For this reason, assembling of the shaft sealing device A becomes easy.

In the above-described embodiment, a part of the first gas supply passage 44 is formed by the metal tube 44e, but instead of the metal tube 44e, the retainer 43 is connected to the annular space 48 by the retainer 43. An internal passage 44h may be formed (see FIG. 3), and in this case, a piping member such as the metal tube 44e is not required, so that the structure can be simplified. In this case, in this case, the internal passage 44h at the boundary between the flange 43b and the seal case 43c.
Is secured by interposing an O-ring P5 at the boundary. The shaft sealing device of the present invention is not limited to the above embodiment. For example, in the embodiment shown in FIG. 1, the metal pipe 44 e is directly connected to the second gas supply path 5, Various design changes can be made, such as forming a sealed space 6 by providing a concave groove on one side. Further, the shaft sealing device of the present invention can be applied as a shaft sealing device for various devices such as a dryer, a stirrer, and a centrifugal separator having a rotating body driven to rotate about a stationary shaft.

[0019]

As described above, according to the shaft sealing device of the first aspect, since the seal gas can be supplied through the interior of the stationary shaft, the gap between the stationary shaft and the rotating body can be reduced by the external pressure type. It can be sealed by a non-contact seal. For this reason,
The gap can be reliably sealed for a long period of time. Further, since the sealing end face of the seal is kept in a non-contact state, it is possible to secure low dust generation without depending on the number of rotations of the rotating body, so that the inside of the rotating body can be cleaned for each batch. In addition, it is not necessary to remove dust adhering to the processed material, and the present invention can be applied to a device for handling a medicine, a food, or the like, which requires low dust generation.

According to the shaft sealing device of the second aspect, the first gas supply passage and the second gas supply passage communicate with each other through the sealed space formed between the inner periphery of the retainer and the stationary shaft. ,
Each gas supply path can be easily communicated without using a piping connector or the like.

According to the third aspect of the present invention, since the sealed space is formed between the annular groove provided along the inner periphery of the retainer and the stationary shaft, a special space is provided on the stationary shaft side. A sealed space can be formed without processing. For this reason, the shaft sealing device can be easily applied to existing devices. In addition, since the sealed space has an annular shape, it is not necessary to align the sealed space with the first gas supply path and the second gas supply path in the circumferential direction, so that the shaft sealing device can be easily assembled.

According to the shaft sealing device of the fourth aspect, since the first gas supply path is formed inside the retainer and the stationary sealing ring, a piping member for the first gas supply path becomes unnecessary. The structure can be simplified.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a principal part showing one embodiment of a shaft sealing device of the present invention.

FIG. 2 is a sectional view of a main part showing a conical dryer to which the shaft sealing device is applied.

FIG. 3 is a cross-sectional view of a main part showing another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Exhaust cylinder (stationary shaft) 2 Tumbler (rotating body) 4 Non-contact seal 41 Rotational seal ring 42 Stationary seal ring 43 Retainer 43d Groove (annular groove) 44 First gas supply path 5 Second gas supply path 6 Sealing Space A Shaft sealing device B Conical dryer

Claims (4)

(57) [Claims] 1. A shaft sealing device for sealing a gap between a stationary shaft and a rotating body driven to rotate about the stationary shaft, comprising: a rotating sealing ring attached to the rotating body so as to be integrally rotatable; An external seal having a stationary sealing ring attached to the stationary shaft and opposed to the rotary sealing ring with a small gap; and a first gas supply path provided on the stationary shaft side and communicating with the small gap. A shaft sealing device comprising: a pressure-type non-contact seal; and a second gas supply passage that passes through the inside of the stationary shaft and supplies a seal gas to the first gas supply passage. 2. An externally pressurized non-contact seal includes a retainer for holding a stationary sealing ring movably in an axial direction, and forms a sealed space between an inner periphery of the retainer and a stationary shaft. The shaft sealing device according to claim 1, wherein the first gas supply path and the second gas supply path communicate with each other via a sealed space. 3. The shaft sealing device according to claim 2, wherein the sealed space is formed between an annular groove provided along an inner periphery of the retainer and a stationary shaft. 4. The shaft sealing device according to claim 2, wherein said first gas supply path is formed inside a retainer and a stationary sealing ring.