Sealed structure

Abstract

While maintaining sealing performance, excessive temperature increases in the sealing material due to friction are suppressed. [Solution] The sealing device is disposed between adjacent high-pressure and low-pressure spaces in the axial direction of the rod, and seals the gap between the outer circumferential surface of the rod and the inner circumferential surface of the housing through which the rod passes. The sealing device includes an annular member attached to the housing, and a seal member attached to the annular member, protruding toward the outer circumferential surface of the rod and capable of contacting the outer circumferential surface of the rod. The seal member has an outer circumferential portion disposed radially outward and an inner circumferential portion disposed radially inward. The seal member is curved and deformable, and the portion that can contact the outer circumferential surface of the rod is deformable so that it protrudes toward the low-pressure space in the axial direction of the rod.

Description

Technical Field

[0001] The present disclosure relates to a sealing device.

Background Art

[0002] There is a sealing device for sealing a gap between a relatively moving shaft and a housing (see, for example, Patent Document 1). The sealing device includes a metal ring having a cylindrical portion that adheres to the inner peripheral surface of the shaft hole of the housing, and a resin seal composed of a plate-shaped and annular resin member.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the resin seal of the sealing device according to the prior art, the outer peripheral portion is fixed to the metal ring, and the inner peripheral portion is slidably adhered to the outer peripheral surface of the shaft in a deformed state so as to be curved. When the shaft rotates at high speed in the above state, the temperature of the resin seal may rise excessively due to the friction between the resin seal and the shaft. The present disclosure aims to suppress an excessive rise in the temperature of the seal member due to friction while maintaining the seal performance.

Means for Solving the Problems

[0005] The sealing structure of the present disclosure comprises a rotatable rod, a housing having an opening through which the rod is inserted, and a sealing device disposed inside the housing between adjacent high-pressure and low-pressure spaces along the axis of the rod, for sealing the gap between the outer circumferential surface of the rod and the inner circumferential surface of the opening, wherein the sealing device includes an annular member mounted on the housing and an annular sealing member fixed to the annular member, the sealing member having an inner circumferential portion near the rod that curves toward the low-pressure space, and the sealing surface of the curved inner circumferential portion facing the rod is in contact with the outer circumferential surface of the rod.

[0006] The sealing method of the present disclosure is a sealing method utilizing a rotatable rod, a housing having an opening through which the rod is inserted, and a sealing member disposed inside the housing between adjacent high-pressure spaces and low-pressure spaces along the axis of the rod and having an inner circumference close to the rod, wherein when the pressure in the high-pressure space falls below a reference value, the inner circumference of the sealing member close to the rod curves toward the low-pressure space, and the sealing surface of the curved inner circumference facing the rod is maintained in contact with the outer circumference of the rod, thereby sealing the gap between the outer circumference of the rod and the inner circumference of the opening; and when the pressure in the high-pressure space exceeds the reference value, the pressure in the high-pressure space presses against the sealing surface of the inner circumference, thereby separating the sealing surface from the outer circumference of the rod. [Brief explanation of the drawing]

[0007] [Figure 1] This is a partial cross-sectional view showing a sealing device attached to a rod. [Figure 2] This is a partial cross-sectional view showing a sealing device. [Figure 3] This is a front view showing a sealing device. [Figure 4] This is a partial cross-sectional view showing a sealing device attached to a rod, illustrating the state in which a pressure below a standard value is applied and the outer surface of the rod is in contact with the sealing member. [Figure 5]This is a partial cross-sectional view showing a sealing device attached to a rod, illustrating a state where pressure exceeding the standard value is acting on it, causing the sealing member to separate from the outer surface of the rod. [Modes for carrying out the invention]

[0008] Embodiments of this disclosure will be described below with reference to the drawings. Note that the dimensions and scale of the parts in the drawings have been appropriately altered from those of the actual parts. Furthermore, the embodiments described below are preferred examples of this disclosure. For this reason, these embodiments are subject to various technically preferred limitations. However, the scope of this disclosure is not limited to these embodiments unless otherwise specifically stated in the following description.

[0009] Figure 1 is a partial cross-sectional view showing a sealing structure 100 according to an embodiment. The sealing structure 100 is used in various devices, such as compressors for compressing gases. The sealing structure 100 comprises a housing 2, a rod 3, and a sealing device 10. Figure 2 is a partial cross-sectional view showing the sealing device 10. Figure 3 is a front view showing the sealing device 10. In each figure, the axial direction X and radial direction Y are indicated by arrows. Figures 2 and 3 show the sealing device 10 before it is mounted on the rod 3. Figure 3 shows the surface of the sealing device 10 facing the low-pressure space L.

[0010] The sealing device 10 is positioned in the gap between the inner circumferential surface 2b of the opening 2a of the housing 2 and the outer circumferential surface 3a of the rod 3. The housing 2 may be, for example, part of a rotating machine. The opening 2a is a circular opening. The rod 3 is a rotating shaft inserted into the interior of the opening 2a of the housing 2. The rod 3 rotates around its axis. The rod 3 is rotatably supported by bearings (not shown). The housing 2 and the rod 3 are arranged coaxially. The sealing device 10 seals the gap between the inner circumferential surface 2b of the housing 2 and the outer circumferential surface 3a of the rod 3.

[0011] In the operating state of the sealing device 10, one of two adjacent spaces along the axial direction X with respect to the sealing device 10 is a low-pressure space L, and the other space is a high-pressure space H. In Figure 1, the space to the left of the sealing device 10 is the low-pressure space L, and the space to the right of the sealing device 10 is the high-pressure space H. For example, the high-pressure space H may be the internal space of equipment equipped with the sealing structure 100. The low-pressure space L may be the external space of equipment equipped with the sealing structure 100. The low-pressure space L may also be a space within the housing 2 that communicates with the external space. The rotation of the rod 3 compresses the gas inside the high-pressure space H. Specifically, the more the rotational speed of the rod 3 increases, the more the gas inside the high-pressure space H is compressed, and as a result the pressure inside the high-pressure space H increases. The rod 3 rotates at a high speed of, for example, 100 krpm (rotations per minute) or more. In the normal operating state of the sealing device 10, the pressure inside the high-pressure space H is higher than the pressure inside the low-pressure space L. Note that the rotational speed of rod 3 is not limited to the examples given above. For example, the rotational speed of rod 3 may be between 5,000 rpm and 100,000 rpm.

[0012] The sealing device 10 comprises an outer ring 20, an inner ring 30, a sealing member 40, and a leaf spring 50. The outer ring 20 has a cylindrical portion 21, a flange 22, and a crimped portion 23. The cylindrical portion 21 is a portion that extends axially X over a predetermined length. The cylindrical portion 21 includes ends 21a and 21b that are spaced apart in the axial direction X. The flange 22 protrudes inward radially Y from one end 21a of the cylindrical portion 21. That is, the flange 22 protrudes toward the outer circumferential surface 3a of the rod 3. The thickness direction of the flange 22 is along the axial direction X. The crimped portion 23 protrudes inward radially Y from the other end 21b of the cylindrical portion 21. The crimped portion 23 is formed by bending the end 21b of the cylindrical portion 21. The outer circumferential surface 21c of the cylindrical portion 21 includes a surface that contacts the inner circumferential surface 2b of the housing 2. The outer circumferential surface 21c of the cylindrical portion 21 may be in close contact with the inner circumferential surface 2b of the housing 2. The outer ring 20 is made of metal, for example. Stainless steel is one example of a metal used for the outer ring 20. The outer ring 20 may be made of a metal other than stainless steel, or of other materials such as resin. The outer ring 20 is an example of an annular member.

[0013] The inner ring 30 has a cylindrical portion 31 and a flange 32. The inner ring 30 is positioned inside the outer ring 20 in the radial direction Y. The inner ring 30 fits onto the outer ring 20. The outer circumferential surface 31c of the inner ring 30 contacts the inner circumferential surface 21d of the outer ring 20. The cylindrical portion 31 has a predetermined length in the axial direction X. The length of the cylindrical portion 31 in the axial direction X is shorter than the length of the cylindrical portion 21 of the outer ring 20 in the axial direction X. The cylindrical portion 31 includes ends 31a and 31b that are spaced apart in the axial direction X. The flange 32 protrudes inward in the radial direction Y from one end 31a of the cylindrical portion 31. The thickness direction of the flange 32 is along the axial direction X. The flange 32 is positioned close to the flange 22 of the outer ring 20 in the axial direction X. The position of the other end 31b of the cylindrical portion 31 is defined in the axial direction X by the crimped portion 23 of the outer ring 20. In the axial direction X, the end portion 31b of the cylindrical portion 31 is in contact with the crimped portion 23. The outer circumferential surface 31c of the cylindrical portion 31 includes a surface that abuts against the inner circumferential surface 21d of the cylindrical portion 21 of the outer ring 20. The inner ring 30 is a member for fixing the sealing member 40 to the outer ring 20 and is an example of a mounting member.

[0014] The sealing member 40 is an annular plate-shaped member. An opening 40a is formed in the center of the sealing member 40. The rod 3 is inserted through the opening 40a. When the rod 3 is not inserted, the inner diameter of the opening 40a is smaller than the outer diameter of the rod 3. The portion of the sealing member 40 closest to the housing 2 (hereinafter referred to as the "outer peripheral portion") 40b includes the portion attached to the outer ring 20. The outer peripheral portion 40b is the annular portion of the sealing member 40 that includes the outer circumference. The thickness direction of the outer peripheral portion 40b of the sealing member 40 is along the axial direction X. The outer peripheral portion 40b of the sealing member 40 is fixed between the flange 22 of the outer ring 20 and the flange 32 of the inner ring 30 in the axial direction X. The sealing member 40 is sandwiched between the flanges 22 and 32 together with the leaf spring 50.

[0015] The outer periphery 40b of the sealing member 40 is positioned between the flange 22 of the outer ring 20 and the flange 32 of the inner ring 30 in the axial direction X. The flange 22 of the outer ring 20 is positioned closer to the high-pressure space H than the outer periphery 40b of the sealing member 40. The flange 32 of the inner ring 30 is positioned closer to the low-pressure space L than the outer periphery 40b of the sealing member 40.

[0016] The flange 22 of the outer ring 20 protrudes further toward the outer surface 3a of the rod 3 than the flange 32 of the inner ring 30. In other words, the inner surface 22a of the flange 22 is closer to the outer surface 3a of the rod 3 than the inner surface 32a of the flange 32.

[0017] The sealing member 40 has an inner circumference 40c. The inner circumference 40c is the annular portion of the sealing member 40 that is close to the rod 3. That is, the inner circumference 40c is the annular portion of the sealing member 40 that includes the inner circumference. When the sealing device 10 is in use, the inner circumference 40c protrudes toward the low-pressure space L. In the cross-section shown in Figure 1, the inner circumference 40c of the sealing member 40 is curved toward the low-pressure space L. When the rod 3 is inserted through the opening 40a, the inner circumference 40c may be cylindrical. In this state, the inner surface (hereinafter referred to as the "sealing surface") 40e of the inner circumference 40c in the radial direction Y contacts the outer surface 3a of the rod 3. The sealing surface 40e of the inner circumference 40c may be in close contact with the outer surface 3a of the rod 3. The sealing surface 40e is the surface of the inner circumference 40c that is curved toward the low-pressure space L and faces the rod 3. The sealing member 40 is not limited to a disc shape. For example, the sealing member 40 may include a plurality of plate-shaped pieces.

[0018] The sealing member 40 is made of resin, for example. PTFE (polytetrafluoroethylene) is an example of a resin used for the sealing member 40. PTFE has excellent heat resistance, pressure resistance, and chemical resistance. PTFE exhibits low sliding wear. The sealing member 40 is flexible and expandable. The sealing member 40 is not limited to resin and may be formed from other materials such as rubber.

[0019] The leaf spring 50 is disk-shaped. An opening 50a is formed in the central portion of the leaf spring 50. As shown in FIG. 2, in a state where the sealing device 10 is not attached to the rod 3, the inner diameter of the opening 50a is smaller than the inner diameter of the opening 40a of the seal member 40. However, the inner diameter of the opening 50a may be larger than the inner diameter of the opening 40a of the seal member 40, or may be the same.

[0020] The outer peripheral portion 50b of the leaf spring 50 is attached to the outer ring 20. The thickness direction of the outer peripheral portion 50b of the leaf spring 50 is along the axial direction X. The outer peripheral portion 50b of the leaf spring 50 is disposed between the outer peripheral portion 40b of the seal member 40 and the flange 32 of the inner ring 30 in the axial direction X. As described above, the seal member 40 and the leaf spring 50 are sandwiched between the flanges 22 and 33. Thereby, the seal member 40 and the leaf spring 50 are attached to the outer ring 20 and the inner ring 30. The leaf spring 50 is disposed closer to the low-pressure space L than the seal member 40 and contacts the seal member 40.

[0021] As shown in FIG. 3, a plurality of slits 51 extending radially in the radial direction Y from the opening 50a are formed in the leaf spring 50. The slits 51 penetrate the leaf spring 50 in the thickness direction.

[0022] In the state of use of the sealing device 10, a portion (hereinafter referred to as "inner peripheral portion") 50c of the leaf spring 50 close to the rod 3 protrudes toward the low-pressure space L. In the cross section shown in FIG. 1, the inner peripheral portion 50c of the leaf spring 50 is curved toward the low-pressure space L. That is, the leaf spring 50 is curved along the seal member 40. In the state of use of the sealing device 10, the inner peripheral surface 50d of the opening 50a of the leaf spring 50 protrudes toward the low-pressure space L more than the inner peripheral surface 40d of the opening 40a of the seal member 40. The inner peripheral surface 40d is an end surface of the seal member 40 facing the low-pressure space L in the state of use. The inner peripheral surface 50d is an end surface of the leaf spring 50 facing the low-pressure space L in the state of use.

[0023] In the operating state of the sealing device 10, the leaf spring 50 is curved along the sealing member 40 and presses the inner circumference 40c of the sealing member 40 inward in the radial direction Y. The inner circumference 40c of the sealing member 40 is pressed against the outer surface 3a of the rod 3. The sealing surface 40e of the sealing member 40 is in contact with the outer surface 3a of the rod 3. The sealing surface 40e of the sealing member 40 may be in close contact with the outer surface 3a of the rod 3.

[0024] Next, the operation of the sealing device 10 will be described. The rod 3 is inserted into the opening 40a of the sealing member 40 from the space of the sealing device 10 closest to the high-pressure space H. As mentioned above, the outer diameter of the rod 3 exceeds the inner diameter of the sealing member 40. Therefore, the inner circumference 40c is pressed by the rod 3 during the insertion process and curves toward the low-pressure space L. That is, the inner circumference 40c of the sealing member 40 contacts the outer surface 3a of the rod 3 and protrudes toward the low-pressure space L. In the operating state of the sealing device 10, the sealing surface 40e of the inner circumference 40c can function as a lip seal that contacts the outer surface 3a of the rod 3. In the axial direction X of the rod 3, the contact surface between the outer surface 3a of the rod 3 and the sealing surface 40e of the sealing member 40 has a predetermined length.

[0025] The rod 3 is movable relative to the housing 2 in the X-axis direction. The rod 3 rotates around its axis. The inner circumference 40c of the sealing member 40 is pressed against the outer circumference 3a of the rod 3 from the outside in the radial Y direction by the leaf spring 50. The sealing surface 40e of the sealing member 40 is in contact with the outer circumference 3a of the rod 3. The sealing performance is maintained by the elastic restoring force of the sealing member 40 itself and the pressure from the leaf spring 50.

[0026] In this embodiment, the sealing surface 40e is in contact with the outer circumferential surface 3a of the rod 3, and the rod 3 rotates at a high speed of, for example, 100krpm or more. Furthermore, the sealing structure 100 of this embodiment operates in a poor lubrication environment. A poor lubrication environment is an environment in which there is no lubricating oil, or an environment in which there is a sufficiently small amount of lubricating oil. In a configuration in which the rod 3 rotates at high speed under poor lubrication conditions, if the rod 3 and the sealing member 40 are constantly in close contact, the temperature of the sealing member 40 may rise excessively due to friction between the rod 3 and the sealing member 40. Against this backdrop, in this embodiment, as described above, a configuration is adopted in which the inner circumferential portion 40c of the sealing member 40 is curved toward the low-pressure space L. With this configuration, when the pressure in the high-pressure space H rises, the sealing surface 40e of the sealing member 40 separates from the outer circumferential surface 3a of the rod 3. The separation of the sealing surface 40e eliminates friction between the sealing surface 40e and the outer circumferential surface 3a, and as a result, the rise in temperature of the sealing member 40 is suppressed. The above effects will be described in detail.

[0027] First, referring to Figure 4, we will explain the state in which the pressure in the high-pressure space H is below the reference value PB. The pressure inside the high-pressure space H is, for example, a first pressure P1. The first pressure P1 is a pressure below the reference value PB. When the first pressure P1 acts on the seal member 40, the sealing surface 40e of the seal member 40 is in contact with the outer circumferential surface 3a of the rod 3. When the first pressure P1 acts, the inner circumference 40c of the seal member 40 is pushed in a direction away from the outer circumferential surface 3a of the rod 3. However, since the seal member 40 is pressed against the outer circumferential surface 3a of the rod 3 by the leaf spring 50, it does not move away from the outer circumferential surface 3a of the rod 3. The force of the first pressure P1 pushing the seal member 40 upward is overcome by the force of the leaf spring 50 pushing the seal member 40 toward the rod 3. Therefore, the seal member 40 is maintained in a state in which the sealing surface 40e of the inner circumference 40c is in contact with the outer circumferential surface 3a of the rod 3. In this case, leakage of internal gas from the high-pressure space H to the low-pressure space L is less than when the internal pressure of the high-pressure space H exceeds the reference value PB. Leakage from the high-pressure space H to the low-pressure space L may be very small. Even if the sealing member 40 does not separate from the outer surface 3a of the rod 3, the internal pressure of the high-pressure space H acts on the sealing member 40, so a force acts in the direction of pushing up the sealing member 40. In this way, the sliding resistance between the sealing member 40 and the rod 3 is reduced by the amount of the force acting in the direction of pushing up the sealing member 40. The sealing device 10 can reduce sliding resistance while keeping the sealing member 40 and the rod 3 in contact. The sealing device 10 can reduce sliding resistance while suppressing leakage of internal gas from the high-pressure space H to the low-pressure space L.

[0028] As rod 3 rotates at high speed, the gas in the high-pressure space H is compressed, causing the pressure in the high-pressure space H to rise. Referring to Figure 5, the state in which the pressure in the high-pressure space H exceeds the reference value PB is explained. The pressure inside the high-pressure space H is, for example, a second pressure P2. The second pressure P2 is higher than the first pressure P1. The second pressure P2 is a pressure that exceeds the reference value PB.

[0029] When a second pressure P2 exceeding the reference value PB acts on the seal member 40, the sealing surface 40e of the seal member 40 separates from the outer circumferential surface 3a of the rod 3. That is, the force of the second pressure P2 pushing up the seal member 40 exceeds the force of the leaf spring 50 pressing the seal member 40 toward the rod 3. When the second pressure P2 acts from the high-pressure space H on the seal member 40, the inner circumference 40c of the seal member 40 is pushed in a direction that separates it from the outer circumferential surface 3a of the rod 3, causing deformation. As a result, the sealing surface 40e separates from the outer circumferential surface 3a of the rod 3, and internal gas leaks from the high-pressure space H to the low-pressure space L. The internal gas in the high-pressure space H flows out into the low-pressure space L through the gap between the sealing surface 40e of the seal member 40 and the outer circumferential surface 3a of the rod 3. The seal member 40 may temporarily separate from the outer circumferential surface 3a of the rod 3 when a pressure exceeding the reference value PB is acting on it.

[0030] As the gas inside the high-pressure space H flows out into the low-pressure space L, the pressure inside the high-pressure space H decreases. When the pressure inside the high-pressure space H falls below the reference value PB, the sealing member 40 is pushed by the leaf spring 50 and comes into contact with the outer surface 3a of the rod 3.

[0031] In the sealing device 10, when the pressure inside the high-pressure space H rises and exceeds the reference value PB, the sealing member 40 deforms, and the sealing surface 40e of the sealing member 40 separates from the outer surface 3a of the rod 3. Therefore, the pressure in the high-pressure space H can be released into the low-pressure space L. This suppresses an excessive pressure rise in the high-pressure space H.

[0032] As described above, in the sealed structure 100, when the pressure inside the high-pressure space H exceeds the reference value PB, the sealing surface 40e of the sealing member 40 deforms so as to separate from the outer circumferential surface 3a of the rod 3. Therefore, the separation of the sealing surface 40e eliminates friction between the sealing surface 40e and the outer circumferential surface 3a, and as a result, the temperature rise of the sealing member 40 is suppressed. In other words, according to this embodiment, while sufficient sealing performance can be maintained when the pressure inside the high-pressure space H is below the reference value PB, excessive temperature rise of the sealing member 40 can be suppressed when the pressure inside the high-pressure space H exceeds the reference value PB. As mentioned above, in a configuration in which the rod 3 rotates at high speed under poor lubrication conditions, the temperature rise of the sealing member 40 is particularly significant. Therefore, this embodiment, which separates the sealing surface 40e from the rod 3 when the pressure inside the high-pressure space H rises, is particularly effective.

[0033] Furthermore, in the sealing device 10, the sealing surface 40e of the sealing member 40 deforms so that it separates from the outer circumferential surface 3a of the rod 3, thereby reducing the sliding resistance between the sealing member 40 and the rod 3. In the sealing device 10, the sealing member 40 is separated from the outer circumferential surface 3a of the rod 3 so that the sliding resistance between the sealing member 40 and the rod 3 does not exceed a certain value, thereby preventing an increase in sliding resistance. In the sealing device 10, by reducing sliding resistance, heat generation is suppressed and the occurrence of permanent deformation due to creep is suppressed. In the sealing device 10, the pressure in the high-pressure space H is appropriately maintained, so damage to the housing 2 that forms the high-pressure space H can be suppressed.

[0034] When the sealing device 10 is in use, pressure is applied to the high-pressure space H. Equipment equipped with the sealing device 10 may also include a pressure boosting mechanism that increases the pressure in the high-pressure space H. The pressure boosting mechanism can apply pressure to the inside of the high-pressure space H. By increasing the pressure in the high-pressure space H to exceed a reference value PB, the sealing member 40 may be deformed so that the sealing surface 40e of the inner circumference 40c is separated from the outer circumference 3a of the rod 3. This reduces the sliding resistance between the sealing surface 40e of the sealing member 40 and the outer circumference 3a of the rod 3, thereby suppressing wear of the sealing member 40.

[0035] With this type of sealing device 10, the inner circumference 40c of the sealing member 40 protrudes toward the low-pressure space L, so that the outer surface 40f of the inner circumference 40c is subjected to the pressure in the low-pressure space L, not the pressure in the high-pressure space H. This prevents excessive tightening by the inner circumference 40c of the sealing member 40. Therefore, it is possible to suppress sliding heat generation and suppress the increase in torque required to rotate the rod 3. By suppressing sliding heat generation, the occurrence of creep in the inner circumference 40c can be suppressed. In the sealing device 10, by suppressing the occurrence of permanent deformation due to creep, the sealing performance can be maintained and the product life can be extended.

[0036] Furthermore, in the sealing device 10, when the pressure in the high-pressure space H exceeds the reference value PB during use, the sealing member 40 can be deformed to reduce the contact pressure between the sealing surface 40e of the inner circumference 40c of the sealing member 40 and the outer circumference 3a of the rod 3. This suppresses wear on the sealing member 40 and reduces the increase in torque required to rotate the rod 3. In addition, by reducing the frictional resistance between the sealing member 40 and the rod 3, heat generation in the sealing member 40 is suppressed, and permanent deformation due to creep of the sealing member 40 can be suppressed. As a result, the sealing performance of the sealing device 10 can be maintained, and reliability can be improved.

[0037] The sealing device 10 can reduce the torque of the rod 3 by adjusting the biasing force acting on the inner circumference 40c toward the outer surface 3a of the rod 3 and the pressure applied to the high-pressure space H. The sealing device 10 can suppress creep of the inner circumference 40c due to sliding heat generation even under harsh operating conditions of high-speed rotation and poor lubrication, thereby ensuring sealing performance and extending product life.

[0038] In the sealing device 10, the cylindrical portion 21 of the outer ring 20 protrudes further toward the low-pressure space L than the sealing member 40. In the radial direction Y, the sealing member 40 is located inside the outer ring 20. In the sealing device 10, since the sealing member 40 does not protrude from the cylindrical portion 21 in the axial direction X, the risk of the sealing member 40 coming into contact with other objects is reduced. This suppresses mechanical damage to the sealing member 40.

[0039] In the sealing device 10, the flange 22 closer to the high-pressure space H protrudes more toward the outer surface 3a of the rod 3 than the flange 32 closer to the low-pressure space L. This makes it easier for the sealing member 40 to bend toward the low-pressure space L.

[0040] Furthermore, in the sealing device 10, the inner circumference 40c of the sealing member 40 is pressed against the outer surface 3a of the rod 3 by the leaf spring 50. Therefore, even if the inner circumference 40c deforms due to pressure exceeding the reference value PB, the possibility of excessive deformation of the inner circumference 40c is reduced. In other words, the inner circumference 40c is deformed within an appropriate range by being pressed by the leaf spring 50. Also, as described above, the possibility of the sealing surface 40e separating excessively from the outer surface 3a of the rod 3 is reduced. In other words, excessive expansion of the gap between the sealing surface 40e and the outer surface 3a is suppressed. Therefore, the possibility of an excessive amount of gas flowing out from the high-pressure space H into the low-pressure space L can be reduced. Another advantage is that even if the elastic force of the sealing member 40 decreases due to aging, the sealing performance can be maintained by the pressure from the leaf spring 50.

[0041] In the sealing device 10, the degree of deformation of the sealing member 40 can be set by appropriately setting the thickness of the leaf spring 50. Furthermore, the degree of deformation of the sealing member 40 can be changed by changing the number of slits 51 in the leaf spring 50. Additionally, the degree of deformation of the sealing member 40 can be set by appropriately setting the thickness of the sealing member 40.

[0042] Next, a conventional sealing device will be described. In a conventional sealing device, the sealing member is curved so as to protrude toward the high-pressure space H. The portion of the sealing member closer to the rod 3 protrudes toward the high-pressure space H more than the portion of the sealing member further away from the rod 3. In this case, the portion of the sealing member closer to the rod 3 is pressed against the outer circumferential surface 3a of the rod 3 by the pressure inside the high-pressure space H. In a conventional sealing device, when the pressure inside the high-pressure space H increases, the portion of the sealing member closer to the rod 3 is pushed toward the outer circumferential surface 3a of the rod 3. Therefore, when the pressure in the high-pressure space H increases, the sealing member is pressed against the rod 3 with a stronger force, so the sealing member does not separate from the outer circumferential surface 3a of the rod 3.

[0043] On the other hand, in the sealing device 10 according to this embodiment, the sealing member 40 is curved so as to protrude toward the low-pressure space L. The inner circumference 40c of the sealing member 40, which is the part of the sealing member 40 closest to the rod 3, is pushed toward the outer circumference 3a of the rod 3 when the pressure inside the high-pressure space H rises, as shown in Figure 5. That is, in the sealing device 10, when the pressure inside the high-pressure space H rises, unlike the conventional technology, the sealing member 40 deforms so as to move away from the outer circumference 3a of the rod 3. The sealing device 10 allows the gas inside the high-pressure space H to leak out into the low-pressure space L. In the sealing device 10, when the pressure inside the high-pressure space H rises and exceeds the reference value PB, the sealing member 40 moves away from the rod 3, so the friction between the sealing member 40 and the rod 3 is eliminated. Therefore, the temperature rise of the sealing member 40 caused by friction between the sealing member 40 and the rod 3 is suppressed. Furthermore, in the sealing device 10, when the pressure inside the high-pressure space H exceeds the reference value PB, the pressure in the high-pressure space H can be reduced, and the sliding resistance between the sealing member 40 and the rod 3 can be reduced.

[0044] Furthermore, the amount of internal gas leaking from the high-pressure space H to the low-pressure space L is such that it does not interfere with the operation of the equipment equipped with rod 3. The amount of internal gas leaking from the high-pressure space H to the low-pressure space L may be such that it does not significantly affect the environment of the low-pressure space L.

[0045] The embodiments described above are merely representative forms of the present invention, and this disclosure is not limited to the embodiments described above. Various modifications and additions are possible without departing from the spirit of this disclosure.

[0046] (1) In the above embodiment, the sealing device 10 is configured to include a leaf spring 50, but the sealing device 10 may also be configured without a leaf spring 50. In the above embodiment, the sealing member 40 is attached to the outer ring 20 using an inner ring 30, but the sealing member 40 may be attached to the outer ring 20 using other members.

[0047] (2) In the above embodiment, a configuration is shown in which the sealing member 40 separates from the outer surface 3a of the rod 3 when the pressure in the high-pressure space H exceeds the reference value PB. However, even if the pressure in the high-pressure space H exceeds the reference value PB, the sealing member 40 may not separate from the outer surface 3a of the rod 3. For example, even if the pressure in the high-pressure space H exceeds the reference value PB, if the pressure difference between the high-pressure space H and the low-pressure space L is small, the sealing member 40 may remain in contact with the outer surface 3a of the rod 3. Even when the sealing member 40 and the rod 3 are in contact, the pressure in the high-pressure space H acts in a direction that pushes the sealing member 40 upward, so the sliding resistance between the sealing member 40 and the rod 3 decreases.

[0048] (3) In the above embodiment, a configuration in which the high-pressure space H is filled with gas was illustrated, but the fluid filling the high-pressure space H may be a liquid, or a fluid which is a mixture of liquid and gas. However, in the configuration in which the gas filling the high-pressure space H is sealed by the sealing device 10, the rise in temperature of the sealing member 40 when the rod 3 rotates at high speed is particularly significant. Therefore, the present invention is particularly effective in the configuration in which the high-pressure space H is filled with gas (i.e., the configuration in which the sealing device 10 seals the gas).

[0049] (4) In the above embodiment, a poor lubrication environment is assumed, but lubricating oil may be supplied to the sealing device 10. The lubricating oil may be supplied, for example, from the high-pressure space H side or from the low-pressure space L side. The lubricating oil may be present between the inner circumference 40c of the seal member 40 and the outer circumference 3a of the rod 3. The lubricating oil may be present in the gap between the sealing surface 40e of the seal member 40 and the outer circumference 3a of the rod 3. When the sealing surface 40e separates from the outer circumference 3a of the rod 3, the lubricating oil present in the high-pressure space H may enter the gap between the seal member 40 and the rod 3. The sealing device 10 can suppress the increase in frictional resistance and suppress the increase in torque of the rod 3.

[0050] (5) In the above embodiment, the sealing member 40 was supported by the outer ring 20 and the inner ring 30, but the structure for supporting the sealing member 40 is not limited to the above examples. For example, the sealing member 40 may be supported by an annular member in which the outer ring 20 and the inner ring 30 are integrally formed. Alternatively, for example, the sealing member 40 may be supported by an annular member in which the outer circumferential surface of the sealing member 40 is in contact with the inner circumferential surface 2b of the housing 2.

[0051] (6) In the above embodiment, the example is given in which the sealing member 40 does not protrude from the outer ring 20 in the axial direction X, but the sealing device 10 is not limited thereto. The sealing member 40 may protrude from the outer ring 20 in the axial direction X. [Explanation of Symbols]

[0052] 2...Housing, 2a...Opening, 2b...Inner circumferential surface, 3...Rod, 3a...Outer circumferential surface, 10...Sealing device, 20...Outer ring (annular member), 30...Inner ring (mounting member), 40...Sealing member, 40b...Outer circumferential part, 40c...Inner circumferential part, 40e...Sealing surface, H...High pressure space, L...Low pressure space, X...Axial direction, Y...Radial direction.

Claims

1. A rotatable rod, A housing having an opening through which the aforementioned rod is inserted, The housing includes a sealing device positioned between adjacent high-pressure and low-pressure spaces along the axis of the rod, which seals the gap between the outer surface of the rod and the inner surface of the opening. The sealing device is The annular member attached to the housing, An annular sealing member fixed to the annular member, It includes a leaf spring positioned closer to the low-pressure space than the sealing member, The sealing member has an inner circumference close to the rod, The inner circumference is curved toward the low-pressure space, and the sealing surface of the curved inner circumference facing the rod is in contact with the outer surface of the rod. The leaf spring presses the sealing member against the outer surface of the rod, When the sealing surface is in contact with the outer circumferential surface of the rod, the portion of the sealing member that curves toward the low-pressure space is subjected to a force by the pressure inside the high-pressure space that separates it from the outer circumferential surface of the rod. Sealed structure.

2. The rotational speed of the rod is 100 krpm or more. The sealing structure according to claim 1.

3. The sealing member deforms such that the sealing surface separates from the outer surface of the rod when the pressure in the high-pressure space exceeds a reference value. The sealing structure according to claim 1 or claim 2.

4. The outer circumference of the leaf spring is fixed to the annular member. The inner circumference of the leaf spring is curved along the sealing member and is movable relative to the annular member. The sealing structure according to claim 1.

5. The aforementioned leaf spring is a disc-shaped member with an opening formed in its center, and a plurality of slits are formed therein, extending radially outward from the opening. The sealing structure according to claim 1.

6. The aforementioned leaf spring is An annular first portion fixed to the annular member, The first portion includes a plurality of second portions extending radially inward from different circumferential positions in the first portion. The sealing structure according to claim 1.

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