Water seal mechanism and maintenance method for bearings using the water seal mechanism

Abstract

To provide a water-sealing device that allows maintenance of bearings without draining the liquid from the tank. [Solution] The water seal device comprises an inflatable seal 2 having an axial hole 20 through which a rotating shaft 16 passes and which expands when air enters the interior; an inner contact plate 4 that abuts the inflatable seal 2 from the inside in the radial direction of the rotating shaft 16; an outer contact portion that abuts the inflatable seal 2 from the outside in the radial direction; an inflatable seal holder 3 that abuts the inflatable seal 2 from one axial direction of the rotating shaft 16 to suppress the expansion of the inflatable seal 2 in one axial direction; and a seal contact portion 6 that is spaced apart from the inflatable seal 2 in the other axial direction and can abut the inflatable seal 2 when air enters the inflatable seal 2 and it expands.

Description

Technical Field

[0001] The present invention relates to a water seal mechanism and a method for maintaining a bearing using the water seal mechanism.

Background Art

[0002] Conventionally, separation equipment for waste plastics containing metals that separates precise types of waste plastics by specific gravity difference for treating waste plastics has been known (Patent Document 1). In the waste plastic separation equipment, a washing and pulverizing machine that washes and pulverizes metal-containing waste plastics with a rotating blade and a water injection device, and a vortex-type cylindrical separation water tank that sinks and discharges metal pulverized matter by a vortex in water, floats floating plastics to the center of the water surface and sucks and recovers them, and collects plastics with an intermediate specific gravity on the inner wall by centrifugal force and discharges them, and a flowing water type specific gravity sorter that separates intermediate specific gravity plastics into light plastics and heavy plastics, and a vibration separator that separates heavy plastics into granular good products and powdered defective products. In the flowing water type specific gravity sorter, heavy PET, PVC, and metals with a high specific gravity settle to the bottom and are transported to the next process by a screw conveyor. The shaft of the screw conveyor is sealed with a mechanical seal or the like to prevent water leakage.

[0003] Also, a spindle seal device that can suppress changes in the gap of the seal part has been known (Patent Document 2). In the spindle seal device, a hydrostatic gas bearing is arranged in the spindle bearing, and the inside of the spindle device and the atmosphere side are sealed by the pressure and flow of compressed air blown out from the gas bearing. Since a metal ring having the same or an approximate coefficient of thermal expansion as the shaft is provided on the outer peripheral side of the gas bearing, it is possible to suppress changes in the gap due to thermal expansion of the seal part and enhance the sealing performance.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

[0005] However, in the flow-type gravity separator described in Patent Document 1, maintenance of bearings such as the mechanical seal of the screw conveyor located at the bottom of the tank was performed according to the flow shown in Figure 15. Specifically, the process involved draining all the water from the tank (S101), manually cleaning the inside of the tank (S102), removing the motor (S103), performing maintenance or replacing the shaft seals such as the mechanical seal (S104), reinstalling the motor (S105), and filling the tank with water (S106) to complete the work. In particular, in large-scale gravity separators, the amount of water in the tank can be around 200 tons, and the draining and cleaning work in S10 alone takes more than a day, and it takes about three days to complete all the work. Since such waste plastic processing equipment often operates 24 hours a day, the fact that the machine is shut down for several days for mechanical seal maintenance, reducing the operating rate, is a problem, and there was a need to shorten the maintenance period. Furthermore, this problem was not limited to flow-type gravity separators, but also occurred in devices with bearing seal structures in tanks filled with liquid.

[0006] In the spindle seal device described in Patent Document 2, the pressure and flow of compressed air blown from a gas bearing seal the inside of the spindle device and the atmosphere. However, it is difficult to apply such a seal structure to the flow-type specific gravity separator described above. Furthermore, even if the mechanical seal is replaced with a spindle seal device, it is still necessary to drain the water from the tank as described above, and this does not lead to a reduction in the maintenance period.

[0007] Therefore, the present invention aims to provide a water-sealing device that allows maintenance of bearings without draining the liquid from the water tank. [Means for solving the problem]

[0008] To solve the above problems, an inflatable seal is provided, having a shaft hole formed in the center through which a rotating shaft passes, and which expands when air enters the interior; an internal contact portion that abuts the inflatable seal from the inside in the radial direction of the rotating shaft to suppress the inward expansion of the inflatable seal; an external contact portion that abuts the inflatable seal from the outside in the radial direction to suppress the outward expansion of the inflatable seal; an axial contact portion that abuts the inflatable seal from one axial direction of the rotating shaft to suppress the expansion of the inflatable seal in one axial direction; and a part provided spaced apart from the inflatable seal in the other axial direction. It is possible to switch between a fixed state, where it is fixed to the rotation axis, and an unfixed state. The present invention provides a water seal mechanism comprising: a contact portion that can come into contact with the inflatable seal when air enters and expands the inflatable seal; a passage for air supplied to the inflatable seal is formed in the shaft contact portion; and an air chamber wider than the passage, accessible from the outside, is formed in the middle of the passage.

[0010] Furthermore, the inflatable seal has a contact portion facing the contact portion, a first contact portion that contacts the inner contact portion, a second contact portion that contacts the outer contact portion, and a third contact portion that contacts the shaft contact portion, and it is preferable that the thickness of the contact portion is thinner than at least one of the first contact portion, the second contact portion, and the third contact portion.

[0011] In another aspect of the present invention, an inflatable seal having a axial hole formed in its center through which a rotating shaft passes, which expands when air enters the interior; an internal contact portion that abuts the inflatable seal from the inside in the radial direction of the rotating shaft to suppress the inward expansion of the inflatable seal; an external contact portion that abuts the inflatable seal from the outside in the radial direction to suppress the outward expansion of the inflatable seal; an axial contact portion that abuts the inflatable seal from one axial direction of the rotating shaft to suppress the expansion of the inflatable seal in one axial direction; and a portion provided spaced apart from the inflatable seal in the other axial direction. It is possible to switch between a fixed state, where it is fixed to the rotation axis, and an unfixed state. A method for maintaining a bearing of a rotating shaft is provided, comprising: a step of introducing air into the inflatable seal and bringing the inflatable seal into contact with the contact plate; a step of maintaining the bearing; and a step of releasing air from the inflatable seal and separating the inflatable seal and the contact plate. The bearing is provided with a water seal mechanism having a contact portion that can come into contact with the inflatable seal when air enters and expands the inflatable seal, and a flow path for air supplied to the inflatable seal formed in the middle of the flow path, which is accessible from the outside and has an air chamber wider than the flow path. The method for maintaining a bearing is characterized by comprising: a step of introducing air into the inflatable seal and bringing the inflatable seal into contact with the contact plate; a step of maintaining the bearing; and a step of releasing air from the inflatable seal and separating the inflatable seal and the contact plate. [Effects of the Invention]

[0012] With this configuration, the inflatable seal expands in the other axial direction and comes into contact with the contact point, thereby suppressing water leakage from the rotating shaft. Furthermore, air can be injected into the inflatable seal only when necessary, such as during maintenance, to create a water seal on the rotating shaft. In addition, because the inflatable seal and the contact point are spaced apart in the axial direction, smooth operation is possible without interference between them during normal operation of the rotating shaft.

[0013] With this configuration, the expansion of the inflatable seal inward and outward is suppressed by the inner and outer contact portions, thereby increasing the amount of expansion of the inflatable seal in the other axial direction. This allows for improved accuracy of the seal on the rotating shaft.

[0014] With this configuration, an air chamber is formed in the airflow path, allowing maintenance of the path to be performed through the air chamber. Furthermore, since the air chamber is located between the first and second airflow paths, maintenance of both paths becomes possible.

[0015] With this configuration, the thickness of the contact portion is thinner than at least one of the first, second, and third contact portions, which allows for an increase in the amount of axial expansion of the inflatable seal on the other side. This improves the accuracy of the seal on the rotating shaft.

[0016] With this configuration, bearing maintenance can be performed by inflating the inflatable seal to seal the rotating shaft. Conventionally, as shown in Figure 15, it was necessary to drain all the water from the tank and clean it, which took about three days for bearing maintenance. In contrast, with this bearing maintenance method, the work of draining the tank and cleaning can be omitted, so the work time can be reduced to about three hours, resulting in a significant reduction. [Brief explanation of the drawing]

[0017] [Figure 1] An overall perspective view of a flotation separator according to the first embodiment of the present invention. [Figure 2] A cross-sectional perspective view of the vicinity of the water seal mechanism according to the first embodiment of the present invention. [Figure 3] An exploded cross-sectional view of a water seal mechanism according to the first embodiment of the present invention. [Figure 4] A perspective view of an inflatable seal of a water seal mechanism according to a first embodiment of the present invention. [Figure 5] Cross-sectional view of the inlet of the inflatable seal of the water seal mechanism according to the first embodiment of the present invention. [Figure 6] Perspective view of the inflatable seal holder of the water seal mechanism according to the first embodiment of the present invention. [Figure 7] Perspective view of the inner contact plate of the water seal mechanism according to the first embodiment of the present invention. [Figure 8] Perspective view of the outer contact plate of the water seal mechanism according to the first embodiment of the present invention. [Figure 9] Perspective view of the seal contact plate of the water seal mechanism according to the first embodiment of the present invention. [Figure 10] Cross-sectional view of the fixing groove of the seal contact plate of the water seal mechanism according to the first embodiment of the present invention. [Figure 11] Partial cross-sectional view of region R of FIG. 2 in the state where the water seal mechanism according to the first embodiment of the present invention is assembled. [Figure 12] Partial cross-sectional view of region R of FIG. 2 when air flows into the inflatable seal in the state where the water seal mechanism according to the first embodiment of the present invention is assembled. [Figure 13] Flow chart of the bearing maintenance of the water seal mechanism according to the first embodiment of the present invention. [Figure 14] Cross-sectional view of the water seal mechanism according to the second embodiment of the present invention. [Figure 15] Flow chart of the conventional bearing maintenance.

Embodiments for Carrying Out the Invention

[0018] The water seal device 1 according to the first embodiment of the present invention will be described based on FIGS. 1 to 12. As shown in the figures, the front-rear, up-down, and left-right directions are defined.

[0019] The water seal device 1 is a mechanism capable of temporarily sealing water leakage from the rotating shaft 16, and is used, for example, in the flotation separator 10 shown in Figure 1. The flotation separator 10 separates the target materials, which are resins such as PE, PP, PET, and nylon, and metals such as aluminum, by the difference in specific gravity using water filled in a water tank 11 with a roughly triangular cross-section. The liquid filled in the water tank 11 is not limited to water, and a liquid with a specific gravity other than 1 may be used. This makes it possible to separate resins and metals into even finer particles.

[0020] In the flotation separator 10, when the material to be separated is introduced through the inlet 12, it is transported into the water tank 11 by two parallel-arranged input screws 13. In the water tank 11, the material to be separated, such as PP and PE, which floats on the water, is transported forward and collected by multiple transport rollers 14 located at the top. Transport screws 15, as shown in Figure 2, are provided in the center and lower part of the water tank 11 in the vertical direction. The transport screws 15 transport the material to be separated that has sunk into the water tank 11 forward. The water seal device 1 is provided at the front-rear ends of the portion of the transport screw 15 that is exposed to the outside. Note that the water seal device 1 is not limited to the flotation separator 10, but can be applied to any mechanism having a rotating shaft in a liquid, such as a mixer, agitator, sedimentation separator, rotary float separator, dewatering separator, and rotary agitator.

[0021] As shown in Figure 2, the rotating shaft 16 of the conveying screw 15 is equipped with a water seal device 1, a shaft seal 17, a coupling 18, and a motor 19. The coupling 18 is connected to the output shaft of the motor 19, and the driving force is transmitted to the conveying screw 15. The shaft seal 17 is an example of a bearing of the present invention.

[0022] As shown in Figure 3, the water seal device 1 consists of an inflatable seal 2, an inflatable seal holder 3, an inner backing plate 4, an outer backing plate 5, and a seal backing plate 6. The inflatable seal holder 3 is an example of the axial contact portion of the present invention, the inner backing plate 4 is an example of the inner contact portion of the present invention, the outer backing plate 5 is an example of the outer contact portion of the present invention, and the seal backing plate 6 is an example of the contact portion of the present invention.

[0023] As shown in Figure 4, the inflatable seal 2 has a substantially annular shape with an axial hole 20 through which a rotating shaft 16 passes in its center, and is made of a flexible material that allows air A (Figure 12) to flow into it. The inflatable seal 2 has a shape that protrudes to the rear and is provided with an inlet 21 through which air A flows in. The inlet 21 is equipped with a sealing material 22 to prevent leakage. The inflatable seal 2 has a cross-sectional shape as shown in Figure 5, with a space 23 formed inside through which air A flows in, an expansion portion 24 that forms the periphery of the space 23, and a holding portion 25 that is inserted into the inflatable seal holder 3.

[0024] Space 23 is formed around the entire circumference of the inflatable seal 2 and has a substantially circular cross-sectional shape. However, the cross-sectional shape of space 23 is not limited to this and may be elliptical or other shapes. The expansion portion 24 covers the periphery of space 23, and its thickness is substantially the same above, below, and in front of space 23. In order to control the expansion direction of the expansion portion 24, its thickness may be varied depending on the direction of space 23. The retained portion 25 protrudes rearward from the expansion portion 24 and is provided with a tapered portion 26 that slopes upward and downward toward the rear. In other words, in the inflatable seal 2, the thickness of the expansion portion 24 is thinner than the thickness of the retained portion 25 in the front-rear direction. The retained portion 25 suppresses the expansion portion 24 from expanding rearward when air A flows into the inflatable seal 2. The expansion portion 24 is an example of the first and second contact portions of the present invention, and the retained portion 25 is an example of the third contact portion of the present invention.

[0025] As shown in Figure 6, the inflatable seal holder 3 has a retaining groove 31 for holding the retained portion 25 of the inflatable seal 2, a shaft hole 32 into which the rotating shaft 16 is inserted, an air chamber 33, and an air hole 34. As shown in Figure 11, the retaining groove 31 into which the retained portion 25 is inserted is fixed to the other by a tapered portion 26. At this time, the inlet 21 is inserted into the air chamber 33 and leakage of air A is suppressed by the sealing material 22. There is a small gap between the shaft hole 32 and the rotating shaft 16, and no special sealing is provided. The water in the water tank 11 is sealed by the shaft seal 17 located behind the inflatable seal holder 3. The inflatable seal holder 3 is fixed to the frame of the water tank 11 by a plurality of bolts.

[0026] As shown in Figure 11, the air chamber 33 is located in the middle of the flow path through which air A is introduced into the inflatable seal 2, and has a predetermined volume. The air chamber 33 is sealed by a lid 35, and an air passage 36 is formed connecting the air chamber 33 to the outside. One end of the air passage 36 opens into the air chamber 33, and the other end becomes an air hole 34. The formation of the air chamber 33 makes it easy to check for air leaks from the inlet 21 and the air passage 36, etc., improving maintainability. The inlet 21 is an example of the first flow path of the present invention, and the air passage 36 is an example of the second flow path of the present invention.

[0027] As shown in Figure 7, the inner backing plate 4 is substantially annular in shape, with an inner shaft hole 41 formed approximately in the center into which the rotating shaft 16 is inserted, and is slightly thinner in the front-to-back direction than the expansion portion 24. The outer diameter of the inner backing plate 4 is approximately the same as the inner diameter of the expansion portion 24 of the inflatable seal 2. As shown in Figure 11, the outer diameter of the inner backing plate 4 abuts against the inner diameter side of the expansion portion 24 when the water seal device 1 is assembled. This prevents the expansion portion 24 from bulging inward when air A flows into the inflatable seal 2 and the expansion portion 24 expands. The inner backing plate 4 is fixed to the inflatable seal holder 3 by a plurality of bolts (not shown).

[0028] As shown in Figure 8, the outer backing plate 5 is substantially annular in shape with an outer shaft hole 51 formed approximately in the center into which the rotating shaft 16 is inserted. It has a wider ring width in the vertical direction than the inner backing plate 4 and is slightly thinner in the front-to-back direction than the expansion portion 24. The front-to-back thickness of the outer backing plate 5 is approximately the same as the thickness of the inner backing plate 4. The inner diameter of the outer backing plate 5 is approximately the same as the outer diameter of the expansion portion 24 of the inflatable seal 2. Therefore, as shown in Figure 11, when the water seal device 1 is assembled, it abuts against the outer diameter side of the expansion portion 24. This prevents the expansion portion 24 from bulging outward when air A flows into the inflatable seal 2 and the expansion portion 24 expands. The outer backing plate 5 is fixed to the inflatable seal holder 3 by a plurality of bolts (not shown).

[0029] As shown in Figure 9, the seal plate 6 has a contact shaft hole 61 formed approximately in the center and is equipped with a shaft fixing portion 62. The shaft fixing portion 62 protrudes forward, and two fixing grooves 63 are formed facing each other radially outward from the contact shaft hole 61. As shown in Figure 10, the fixing grooves 63 have a predetermined depth and a rounded bottom surface. This suppresses stress concentration on the bottom surface and reduces cracking. The seal plate 6 is fixed to the rotating shaft 16 and rotates together with the rotating shaft 16. When fixing the seal plate 6 to the rotating shaft 16, the rear end of the fixing groove 63 is narrowed by tightening the bolt at the end of the shaft fixing portion 62, as shown by the dotted line in Figure 10. This fixes the seal plate 6 to the rotating shaft 16. With this fixing method, the seal plate 6 can be fixed to the rotating shaft 16 without drilling screw holes or the like.

[0030] As shown in Figure 11, the seal backing plate 6 is positioned at a distance from the expansion portion 24 of the inflatable seal 2 in the front-rear direction. The distance between the seal backing plate 6 and the inflatable seal 2 is set to a distance such that the expansion portion 24 contacts the seal backing plate 6 when it expands. The distance can be arbitrarily set depending on the thickness of the expansion portion 24, the shape and material of the inflatable seal 2, etc. Because the seal backing plate 6, the inflatable seal 2 and the inflatable seal holder 3 are spaced apart, the rotation of the conveying screw 15 and the seal backing plate 6 is not transmitted to the inflatable seal holder 3. In other words, in the operating state when the conveying screw 15 is rotating, the seal backing plate 6 rotates together with the rotating shaft 16, but the inflatable seal holder 3 is fixed to the frame of the water tank 11.

[0031] Next, the assembly method of the water seal device 1 will be described with reference to Figures 2 and 11. The inflatable seal 2 is inserted into the retaining groove 31 and fixed to the retaining groove 31 by the tapered portion 26, while also connecting the inlet 21 and the air chamber 33. The air chamber 33 is closed with the lid 35 using multiple bolts. The inner backing plate 4 and the outer backing plate 5 are fixed to the inflatable seal holder 3 with multiple bolts. In this state, the inflatable seal holder 3 is fixed to the frame of the water tank 11. The seal backing plate 6 is fixed to the rotating shaft 16 of the transport screw 15 by tightening the shaft fixing portion 62 with bolts and closing the fixing groove 63. As a result, as shown in Figures 2 and 11, the tapered portion 26 of the inflatable seal 2 is fixed to the inflatable seal holder 3, the inside of the expansion portion 24 is in contact with the inner backing plate 4, the outside of the expansion portion 24 is in contact with the outer backing plate 5, and the front end of the expansion portion 24 is spaced apart from the seal backing plate 6 in the front-rear direction.

[0032] Next, the state when air A is introduced into the inflatable seal 2 will be explained with reference to Figure 12. Air A enters the space 23 of the inflatable seal 2 through the air hole 34, air passage 36, air chamber 33, and inlet 21. The expansion portion 24 abuts against the outer backing plate 5 on its radially outer side and against the inner backing plate 4 on its radially inner side, and its expansion is restricted because the held portion 25 is located at the rear, allowing it to expand only forward. As a result, the expansion portion 24, which has expanded only forward, abuts against the seal backing plate 6, and the water in the water tank 11 is sealed by the expansion portion 24. In other words, the contact of the inflatable seal 2 with the seal backing plate 6 seals the water leakage from the shaft hole 32.

[0033] Next, a maintenance method for the shaft seal 17 of the conveying screw 15 of the flotation separator 10 using the water seal device 1 will be explained with reference to Figure 13.

[0034] After stopping the flotation separator 10, air A is sent from the air vent 34 to the water seal device 1 (S1). As a result, as shown in Figure 12, the rotating shaft 16 is sealed by the water seal device 1, preventing water from leaking from the water tank 11. In this state, the motor 19 is removed (S2), and maintenance of the shaft seal 17 is performed (S3). Maintenance here refers to a concept that includes repair and replacement. In this embodiment, a cinch seal is used as the shaft seal 17, so the silicone elastomer that rotates integrally with the rotating shaft 16 is replaced as needed. This reduces maintenance costs. After that, the motor 19 is installed, and the maintenance of the shaft seal 17 is completed (S4). By using the water seal device 1 of this embodiment, maintenance of the shaft seal 17 can be completed in a few hours. This is a significant reduction in time compared to the conventional maintenance method shown in Figure 15, which took about three days.

[0035] With this configuration, the inflatable seal 2 expands forward and comes into contact with the seal plate 6, thereby suppressing water leakage from the rotating shaft 16. In addition, air A can be injected into the inflatable seal 2 only when necessary, such as during maintenance, to water-seal the rotating shaft 16. Furthermore, because the inflatable seal 2 and the seal plate 6 are spaced apart in the front-rear direction, smooth operation is possible without interference between them during the normal operation of the rotating shaft 16.

[0036] With this configuration, the radial inward and outward expansion of the inflatable seal 2 is suppressed by the inner backing plate 4 and the outer backing plate 5, thereby increasing the amount of forward expansion of the inflatable seal 2. This makes it possible to further improve the accuracy of the seal on the rotating shaft 16.

[0037] With this configuration, since an air chamber 33 is formed in the air passage A, maintenance of the passage can be performed through the air chamber 33. Furthermore, since the air chamber 33 is located between the inlet 21 and the air passage 36, maintenance of both passages becomes possible.

[0038] With this configuration, the thickness of the expansion portion 24 is thinner than that of the retained portion 25, which increases the amount of forward expansion of the inflatable seal 2. This allows for a higher accuracy in sealing the rotating shaft 16.

[0039] With this configuration, the shaft seal 17 can be maintained by filling the inflatable seal 2 with air A to seal the rotating shaft 16. Conventionally, as shown in Figure 15, it was necessary to drain all the water from the tank 11 and clean it, so maintenance of the bearing took about 3 days. In contrast, with the bearing maintenance method according to this embodiment, the work of draining the water from the tank 11 and cleaning can be omitted, so the work time can be reduced to about 3 hours, which is a significant reduction.

[0040] Next, a second embodiment of the present invention will be described with reference to Figure 14. Components identical to those in the first embodiment are denoted by the same reference numerals and their descriptions are omitted.

[0041] In the first embodiment, the inflatable portion 24 was held around by separate components: an inflatable seal holder 3, an inner backing plate 4, and an outer backing plate 5. In the second embodiment, the inflatable portion 24 is held around by an inflatable seal holder 203.

[0042] The inflatable seal holder 203 integrally comprises the inflatable seal holder 3 of the first embodiment, the inner contact plate 4, and the outer contact plate 5. This reduces the number of parts and lowers manufacturing costs. The inflatable seal holder 203 is an example of the inner contact portion, outer contact portion, and shaft contact portion of the present invention.

[0043] The water seal mechanism and bearing maintenance method using the water seal mechanism according to the present invention are not limited to the embodiments described above, and various modifications are possible within the scope of the gist of the invention as described in the claims.

[0044] In the above-described embodiment, the shape of the inflatable seal holder 3 is approximately annular, but it is not limited to this. For example, any shape such as a roughly rectangular or polygonal shape can be adopted.

[0045] In the above-described embodiment, an air chamber 33 is provided in the inflatable seal holder 3, but the invention is not limited to this. The inflatable seal holder may not have an air chamber, and the inlet 21 may be directly exposed to the outside. [Explanation of symbols]

[0046] 1 Water sealing device 2 Inflatable seals 3,203 Inflatable Seal Holder 4. Inner backing plate 5. Outer backing plate 6. Seal backing plate 16 Rotation axis 20 shaft holes 21 Inlet 24 Expansion section 25 Holding part 26 Tapered section 32 shaft holes 41 Shaft hole 51 Shaft hole

Claims

1. An inflatable seal is formed in the center, through which a rotating shaft passes, and which expands when air enters the interior. An internal contact portion that abuts against the inflatable seal from the inside in the radial direction of the rotation axis to suppress the inward expansion of the inflatable seal, An outer contact portion that abuts against the inflatable seal from the outside in the radial direction to suppress the outward expansion of the inflatable seal, A shaft contact portion that contacts the inflatable seal from one axial direction of the rotating shaft to suppress the expansion of one side of the inflatable seal in the axial direction, It has a contact portion that is spaced apart from the inflatable seal in the axial direction on the other side, and is switchable between a fixed state fixed to the rotation axis and an unfixed state, and which can come into contact with the inflatable seal when air enters and inflates the inflatable seal, The shaft contact portion has a passage for air supplied to the inflatable seal. A water seal mechanism characterized in that an air chamber wider than the flow path and accessible from the outside is formed in the middle of the flow path.

2. Inflatable seals are The aforementioned contact portion and the contact portion facing it, The first contact portion that contacts the aforementioned internal contact portion, A second contact portion that contacts the aforementioned outer contact portion, It has a third contact portion that contacts the aforementioned shaft contact portion, The water seal mechanism according to claim 1, characterized in that the thickness of the contact portion is thinner than at least one of the first contact portion, the second contact portion, and the third contact portion.

3. A maintenance method for the bearing of a rotating shaft, comprising: an inflatable seal having a shaft hole formed in the center through which a rotating shaft passes, which expands when air enters the interior; an internal contact portion that abuts the inflatable seal from the inside in the radial direction of the rotating shaft to suppress the inward expansion of the inflatable seal; an external contact portion that abuts the inflatable seal from the outside in the radial direction to suppress the outward expansion of the inflatable seal; an axial contact portion that abuts the inflatable seal from one axial direction of the rotating shaft to suppress the expansion of the inflatable seal in one axial direction; and a contact portion provided spaced apart from the inflatable seal in the other axial direction, which is switchable between a fixed state fixed to the rotating shaft and an unfixed state, and which can abut the inflatable seal when air enters the inflatable seal and expands, wherein a water seal mechanism is provided in the axial contact portion, an air passage for supplying air to the inflatable seal is formed in the middle of the air passage, which is accessible from the outside and has an air chamber wider than the air passage, The steps include: inflating the inflatable seal with air and bringing the inflatable seal into contact with the contact portion; The steps include: maintaining the aforementioned bearing, A method for maintaining a bearing, characterized by comprising the step of releasing air from the inflatable seal and separating the inflatable seal from the contact portion.

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