JP2016011704A - mechanical seal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mechanical seal which includes a metal seal case and easily inhibits corrosion of the seal case caused by a material in a sealing area.SOLUTION: A mechanical seal includes: a rotary ring 120 fixed to a rotary shaft 200; a fixed ring 130 which forms a seal surface between itself and the rotary ring 120; an annular metal seal case 140 which holds the fixed ring 130; and an annular protection member 150 wich is formed by a material having corrosion resistance against a material in a housing 300. The protection member 150 is attached to a space between the seal case 140 and the housing 300 so as to close a path through which the material in the housing 300 reaches the seal case 140.

Description

  The present invention relates to a mechanical seal.

  Mechanical seals used in devices such as stirrers and pumps for pharmaceuticals and foods are required to reliably prevent foreign substances from entering the sealed area (inside the machine). Here, if a metal part is exposed inside the machine, when a highly corrosive substance is sealed in the machine, the part may corrode and foreign matter such as oxide may be generated. Therefore, a mechanical seal called a non-metallic structure in which a metal part is not exposed on the inside of the machine is known. Patent Document 1 discloses a mechanical seal in which a coating layer made of a synthetic resin material is formed on a portion of a metal seal case that can be contacted by a fluid sealed inside the apparatus.

JP 2012-31896 A

  According to the mechanical seal disclosed in Patent Document 1, the corrosion of the metal seal case is suppressed, but it is necessary to completely form a coating layer in a portion where the sealing fluid can contact.

  An object of the present invention is to provide a mechanical seal including a metal seal case, which can easily suppress corrosion of the seal case due to a substance in the sealed region.

The present invention employs the following configuration in order to solve the above problems.
That is, the mechanical seal according to the present invention is
A mechanical seal that seals a gap between the rotating shaft and a housing through which the rotating shaft is inserted,
A rotating ring fixed to the rotating shaft;
A stationary ring forming a sealing surface with the rotating ring;
An annular and metal seal case for holding the stationary ring;
An annular protective member made of a material having corrosion resistance to the substance in the housing;
With
The protection member may be attached between the seal case and the housing so as to block a path through which a substance in the housing reaches the seal case.

  According to the present invention, by attaching a protective member composed of parts different from the seal case, the contact between the metal seal case and the substance sealed in the housing is prevented, and the corrosion of the seal case is suppressed. It becomes possible to do. Therefore, according to the present invention, it is not necessary to form a coating layer on the surface of the seal case as in the above prior art, so that corrosion of the metal seal case can be easily suppressed.

Here, the rotating ring and the fixed ring seal a radially inner region of the seal case,
The protective member includes a cylindrical portion that is inserted radially inward of the seal case, and a flange portion that extends radially outward along an end surface on the housing side in the axial direction of the seal case,
The space between the cylindrical portion and the fixed ring may be sealed with an annular seal made of a rubber-like elastic body, and the housing may be fixed on the opposite side of the flange portion from the seal case.

  According to this configuration, the protection member and the annular seal can reliably block the path through which the substance in the housing reaches the seal case.

  ADVANTAGE OF THE INVENTION According to this invention, the mechanical seal provided with a metal seal case provides the mechanical seal which can suppress easily the corrosion of the seal case by the substance in a sealing area.

It is typical sectional drawing of the mechanical seal which concerns on the Example of this invention.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be exemplarily described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified. .

[Example]
<Configuration of mechanical seal>
With reference to FIG. 1, the structure of the mechanical seal which concerns on the Example of this invention is demonstrated. The mechanical seal 100 according to the present embodiment is a mechanical seal that is used to seal a gap between the rotary shaft 200 and the housing 300 through which the rotary shaft 200 is inserted. Used in devices such as pumps. FIG. 1 is a schematic cross-sectional view showing a schematic configuration of the mechanical seal 100 by a plane including the central axis of the rotation shaft 200. For convenience of explanation, the phase of the cutting position is appropriately changed in order to show a characteristic part. Further, the depth is basically omitted, and only the end face is shown.

  The mechanical seal 100 includes a collar 110 fixed to the rotating shaft 200 and a rotating ring 120 fixed to the rotating shaft 200 via the collar 110. The rotating ring 120 is made of SiC (silicon carbide) which is a material having corrosion resistance against a substance (details will be described later) accommodated in the housing 300. An annular step 121 is provided on the outer peripheral side of the rotating ring 120, and the step 121 is sandwiched by an annular and metal fixing member 111 screwed to the collar 110, thereby rotating the rotating ring 120. 120 is fixed to the collar 110. Further, the collar 110 is provided with a knock pin 112 protruding in the axial direction, and the rotation of the rotary ring 120 with respect to the collar 110 is restricted by fitting the knock pin 112 into a notch groove 122 provided in the step portion 121. ing. Further, the O ring 190 is sealed between the inner peripheral surface of the rotating ring 120 and the outer peripheral surface of the rotating shaft 200. The collar 110 is fixed by a sleeve 113 fixed to the rotary shaft 200 in a state where the collar 110 is positioned by a step portion provided on the rotary shaft 200. The collar 110 and the sleeve 113 and the rotary ring 120 and the sleeve 113 and the rotary shaft 200 are sealed with O-rings, respectively.

The mechanical seal 100 includes a stationary ring 130 that forms a sealing surface with the rotary ring 120, and an annular and metal seal case 140 that holds the stationary ring 130. The fixed ring 130 is made of SiC like the rotating ring 120. The seal case 140 is provided with a knock pin 141 projecting in the axial direction. The knock pin 141 is inserted into a pin hole 131 provided on the end surface of the stationary ring 130 on the machine inner side A (the sealing area on the right side in the drawing). By fitting, the rotation of the stationary ring 130 with respect to the seal case 140 is restricted. Further, the seal case 140 is provided with a spring 142 that urges the stationary ring 130 in the direction of the outside B (the air side on the left side in the figure).

  An annular protective member 150 made of a material having corrosion resistance against the substance in the housing 300 is attached to the inside of the seal case 140 in the radial direction. In the present embodiment, the housing 300 contains a strongly acidic liquid such as fuming sulfuric acid or hydrofluoric acid, or a strongly basic fluid such as caustic soda. Therefore, as the material of the protective member 150, SiC having corrosion resistance against these strongly acidic fluids and strongly basic fluids is used. The protection member 150 is manufactured by being subjected to processing such as shaving after being formed by sintering. Note that the material of the protection member 150 may be determined as appropriate according to the substance (fluid, gas, powder, etc.) accommodated in the housing 300. Therefore, the accommodated substance is a particularly corrosive substance such as a strongly acidic substance. If it is not expensive, it may be another ceramic such as alumina, or a material such as resin or carbon. In this case, the material of the rotating ring 120 and the stationary ring 130 may also be other ceramics such as alumina, or a material such as resin or carbon.

  The protective member 150 includes a cylindrical portion 151 that is inserted radially inward of the seal case 140 and a flange portion 152 that extends radially outward along an end surface of the seal case 140 on the in-machine A side. The cylindrical portion 151 extends to the inner diameter side of the stationary ring 130, and the space between the cylindrical portion 151 and the stationary ring 130 is sealed with an O-ring 191 made of a rubber-like elastic body. Further, an annular step portion 153 is provided on the outer peripheral side of the flange portion 152, and this step portion 153 is sandwiched by an annular and metal fixing member 160 screwed to the seal case 140. The protective member 150 is fixed to the seal case 140.

  The mechanical seal 100 configured as described above is fastened to a stud bolt 302 provided on an end surface on the outside B side of the housing 300 together with a case 170 in which a bearing and the like for supporting the rotating shaft 200 are accommodated. The housing 300 is fixed. A gap between the flange portion 152 of the protective member 150 and the end surface on the outside B side of the opening 301 of the housing 300 is sealed with a gasket 192 made of a rubber-like elastic body. By fixing the mechanical seal 100 to the housing 300 in this manner, the protective member 150 is attached between the seal case 140 and the housing 300. As a result, the seal case 140 is not exposed to the in-machine A side by the protective member 150, so that the path through which the substance in the housing 300 reaches the seal case 140 is blocked.

Meanwhile, the seal case 140 is provided with a gas supply hole 143 penetrating in the radial direction. The stationary ring 130 is provided with a passage 133 extending from the outer peripheral surface of the stationary ring 130 to the end surface 132 on the outside B side. As illustrated, the stationary ring 130 is attached to the seal case 140 in a state where the gas supply hole 143 and the passage 133 communicate with each other. The space between the stationary ring 130 and the seal case 140 is sealed by rubber-like elastic O-rings 193 and 194 provided on both sides of the passage 133 in the axial direction. Thereby, the pressure of the gas passing through the gas supply hole 143 and the passage 133 is maintained. A gas supply device (not shown) that supplies nitrogen gas or the like to the gas supply hole 143 when the mechanical seal 100 is used is installed outside the mechanical seal 100. Since the gas supplied from the gas supply device to the gas supply hole 143 is introduced between the end surface 123 on the in-machine A side of the rotating ring 120 and the end surface 132 of the stationary ring 130 through the passage 133, the introduced gas Due to this pressure, a minute gap is generated between the end surface 123 and the end surface 132. Therefore, in this embodiment, the rotating ring 120 rotates in a non-contact state with respect to the stationary ring 130, but is fixed to the rotating ring 120 by the action of the gas introduced between the end face 123 and the end face 132. A sealing surface is formed between the ring 130. As a result, the region on the radially inner side (in-machine A side) of the seal case 140 communicating with the region in the housing 300 is sealed. Here, since the rotating ring 120 rotates in a non-contact state with respect to the stationary ring 130, generation of foreign matters such as dust due to wear is avoided. The end face 123 is formed with a dynamic pressure generating groove 124 for effectively generating a dynamic pressure of gas. Further, the case 170 is provided with a vent 171 penetrating in the radial direction, and the gas that has flowed out to the outside B side after being introduced between both end faces is discharged to the atmosphere through the vent 171. On the other hand, the gas that has flowed into the in-machine A side after being introduced between both end faces is discharged from a vent (not shown) provided in the housing 300.

<Excellent points of mechanical seal according to this embodiment>
According to the mechanical seal 100 configured as described above, the protective member 150 configured with parts different from the seal case 140 is attached between the seal case 140 and the housing 300, so that the inside of the housing 300, which is a sealed region. It is possible to block the path where the substance accommodated in the region reaches the seal case 140. Thereby, corrosion of the seal case 140 can be easily suppressed. Further, according to the mechanical seal 100, the space between the cylindrical portion 151 and the stationary ring 130 of the protection member 150 is sealed by the O-ring 191, and the housing 300 is fixed on the opposite side of the flange portion 152 from the seal case 140. Therefore, it is possible to reliably block the path in which the substance in the housing 300 reaches the radially inner side of the seal case 140.

  In the mechanical seal 100, the rotating ring 120, the stationary ring 130, and the protective member 150, which are not exposed to the metal part on the side A in the machine and can contact the substance in the housing 300, all have corrosion resistance. Consists of materials. Therefore, according to the mechanical seal 100, generation | occurrence | production of the foreign material by corrosion of a component is prevented suitably. Further, according to the mechanical seal 100, since the protective member 150 includes the cylindrical portion 151 and the flange portion 152, the cylindrical member 151 can be easily attached to the seal case 140 by inserting the cylindrical portion 151 from the in-machine A side. Is possible. Further, in the mechanical seal 100, the protection member 150 is screwed via a fixing member 160. Therefore, even if the protective member 150 is made of a material having low toughness such as SiC, it can be easily fixed to the seal case 140 without damaging the protective member 150. Further, according to such a configuration, even if the protection member 150 is made of a material having a large thermal expansion coefficient such as a resin, it can be easily fixed by screwing via the fixing member 160. In addition, when the protection member 150 is made of a material having a certain degree of elasticity such as carbon, it can be directly fixed to the seal case 140. In this embodiment, the rotating ring 120 rotates in a non-contact state with respect to the stationary ring 130, but the present invention is also applied to a mechanical seal having a configuration in which the rotating ring slides with respect to the stationary ring. can do. Even in this case, the generation of foreign matters due to corrosion of the component parts is preferably prevented.

100 Mechanical seal 120 Rotating ring 130 Fixed ring 140 Seal case 150 Protective member 200 Rotating shaft 300 Housing

Claims (2)

A mechanical seal that seals a gap between the rotating shaft and a housing through which the rotating shaft is inserted,
A rotating ring fixed to the rotating shaft;
A stationary ring forming a sealing surface with the rotating ring;
An annular and metal seal case for holding the stationary ring;
An annular protective member made of a material having corrosion resistance to the substance in the housing;
With
The mechanical seal, wherein the protective member is attached between the seal case and the housing so as to block a path through which a substance in the housing reaches the seal case. The rotating ring and the stationary ring seal a radially inner region of the seal case,
The protective member includes a cylindrical portion that is inserted radially inward of the seal case, and a flange portion that extends radially outward along an end surface on the housing side in the axial direction of the seal case,
The space between the cylindrical portion and the fixed ring is sealed with an annular seal made of a rubber-like elastic body, and the housing is fixed on the opposite side of the flange portion from the seal case. Item 2. The mechanical seal according to Item 1.

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