Mechanical seal

Abstract

The present invention provides a mechanical seal that is capable of stabilizing surface pressure.　One sealing ring 10 and a case 20 abut on each other in the axial direction. A gasket 30 has a radially extending portion 32 that is positioned between the one sealing ring 10 and the case 20 in the axial direction. The radially extending portion 32 is disposed in a recess 14 that is formed so as to be recessed in the axial direction from at least one of the one sealing ring 10 and the case 20. An axial clearance A1 is formed between the radially extending portion 32 and at least one of the one sealing ring 10 and the case 20.

Description

Mechanical seal

[0001] The present invention relates to a mechanical seal, for example, a mechanical seal for sealing a rotating shaft.

[0002] Mechanical seals are used by being installed between the housing of a fluid equipment and a rotating shaft that passes through the housing. Specifically, mechanical seals have the function of preventing leakage of the sealed fluid by bringing the sliding surface of a stationary seal ring attached to the housing into sliding contact with the sliding surface of a rotating seal ring that is attached to the rotating shaft and rotates.

[0003] For example, the mechanical seal shown in Patent Document 1 is mainly composed of a seal ring, a floating seat, a sleeve, and a cushioning rubber. The sleeve is formed with a roughly C-shaped cross section. A floating seat with a cushioning rubber fitted on the outside is fitted inside the sleeve. The cushioning rubber is formed with a roughly L-shaped cross section, a so-called cup gasket. The axial extension of the cushioning rubber is positioned radially between the sleeve and the floating seat to seal the gap between them.

[0004] Microfilm of Utility Model Application No. 58-186981 (Unexamined Utility Model Application No. 60-095269) (pages 5 and 6, Figure 3)

[0005] In the mechanical seal of Patent Document 1, a radial extension portion of the buffer rubber that extends in the radial direction of the rotating shaft is disposed between the sleeve and the floating seat in the axial direction. The radial extension portion of the buffer rubber abuts against the back surface of the floating seat. This prevents the buffer rubber from coming out even if a force is applied in the direction of coming out.

[0006] However, in the mechanical seal of Patent Document 1, not only the fluid pressure of the sealed fluid but also the elastic force of the radially extending portion of the cushioning rubber acts on the floating seat, which may result in excessive surface pressure.

[0007] The present invention has been made in view of these problems, and has as its object to provide a mechanical seal capable of stabilizing surface pressure.

[0008] To solve the above problem, the present invention provides a mechanical seal comprising: a stationary seal ring attached to a housing; a rotary seal ring attached to a rotating shaft inserted into the housing; a case for holding one of the seal rings; and a gasket disposed between the one seal ring and the case, wherein the sliding surfaces of the seal rings, which rotate relative to each other, slide against each other to separate a sealed fluid space and a leakage space, wherein the one seal ring and the case abut in the axial direction, and the gasket has a radially extending portion located between the one seal ring and the case in the axial direction, the radially extending portion being disposed in a recess formed by being recessed axially from at least one of the one seal ring and the case, and an axial gap being formed between the radially extending portion and at least one of the one seal ring and the case. This minimizes the elastic force of the radially extending portion acting on the one seal ring, thereby stabilizing the surface pressure of the mechanical seal.

[0009] The axial gap may be continuous in both the circumferential and radial directions, which prevents the radially extending portion from elastically deforming in the axial direction along the circumferential direction, thereby preventing the elastic force of the radially extending portion from acting on one of the seal rings.

[0010] The radially extending portion may be in axial contact with either the one seal ring or the case, thereby more reliably forming an axial gap.

[0011] A radial gap may be formed between the radially extending portion and at least one of the one seal ring and the case, thereby making it possible to more reliably form an axial gap.

[0012] The gasket may have an axially extending portion located radially between the one seal ring and the case, and the case may have a reverse tapered portion that extends at an angle toward the axially extending portion toward the other seal ring. In this way, the gap between the case and one seal ring becomes narrower as it approaches the other seal ring, thereby reliably preventing the gasket from slipping out.

[0013]

[0023] Figure 1 is a cross-sectional view showing a mechanical seal according to a first embodiment of the present invention, where (a) is an overall cross-sectional view and (b) is an enlarged cross-sectional view of a main portion.

[0024] Figure 2 is a cross-sectional view showing a mechanical seal according to a second embodiment of the present invention, where (a) is an overall cross-sectional view and (b) is an enlarged cross-sectional view of a main portion.

[0025] Figure 3 is a cross-sectional view showing a mechanical seal according to a third embodiment of the present invention, where (a) is an overall cross-sectional view and (b) is an enlarged cross-sectional view of a main portion.

[0026] Figure 4 is a cross-sectional view showing a mechanical seal according to a fourth embodiment of the present invention, where (a) is an overall cross-sectional view and (b) is an enlarged cross-sectional view of a main portion.

[0027] Figure 5 is a cross-sectional view showing a mechanical seal according to a fifth embodiment of the present invention, where (a) is an overall cross-sectional view and (b) is an enlarged cross-sectional view of a main portion.

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A mechanical seal according to the present invention will be described below with reference to the following examples.

[0015] A mechanical seal according to a first embodiment will be described with reference to Fig. 1. In the following description, the left side of Fig. 1 will be referred to as the left side, and the right side of Fig. 1 will be referred to as the right side.

[0016] As shown in Figure 1, the mechanical seal 1 of this embodiment is used to seal between a rotating shaft 2 and a housing 3 in a fluid device. The mechanical seal 1 is an inside type in which sliding surfaces 11, 41 seal between an inner space S1 and an outer space S2. The inner space S1 is a leakage space that communicates with the atmosphere A. The outer space S2 is a sealed fluid space into which a sealed fluid F flows. In this embodiment, the sealed fluid F is a high-pressure liquid, and the atmosphere A is at a lower pressure than the sealed fluid F.

[0017] The mechanical seal 1 is mainly composed of a rotating element 4 and a stationary element 5 .

[0018] The rotating element 4 is mainly composed of a rotary seal ring 10 as one seal ring, a sleeve 20 as a case, and a cup gasket 30 as a gasket.

[0019] The rotary seal ring 10 is provided in a state that it can rotate together with the rotary shaft 2 via a sleeve 20 and a cup gasket 30 .

[0020] The stationary element 5 is mainly composed of a stationary seal ring 40 as the other seal ring, a seal cover 50, a biasing member 60, a bellows 70, a band 80, and a retainer 90. In other words, the mechanical seal 1 of this embodiment is of the stationary type.

[0021] The stationary seal ring 40 is attached to the seal cover 50 via a bellows 70, a band 80, and a retainer 90. As a result, the stationary seal ring 40 is provided so as to be movable in the axial direction relative to the seal cover 50, which is fixed to the housing 3, while being restricted from rotating. The space between the stationary seal ring 40 and the seal cover 50 is sealed by the bellows 70.

[0022] The stationary seal ring 40 is biased in the axial direction by a biasing member 60. As a result, the sliding surface 41 of the stationary seal ring 40 and the sliding surface 11 of the rotary seal ring 10 are allowed to slide closely against each other.

[0023] The following will describe in detail the configuration of the rotating element 4. The rotary seal ring 10 is formed in a cylindrical shape with an inner diameter side step, including a base portion 12 on the sliding surface 11 side and an annular protrusion 13 protruding from the back surface side.

[0024] The base 12 is a cylindrical portion having a substantially rectangular cross section. The base 12 is provided with a sliding surface 11. A back surface 12a (see FIG. 1(b)) of the base 12 extends linearly in the radial direction.

[0025] The annular protrusion 13 is a cylindrical portion with a generally rectangular cross section, whose inner diameter is longer than the inner diameter of the base 12. The outer peripheral surface of the annular protrusion 13 is flush with the outer peripheral surface of the base 12. A back surface 13a of the annular protrusion 13 extends linearly in the radial direction and is the back surface end face of the seal ring.

[0026] The back surface end face of the seal ring is the end face of the seal ring that is located axially opposite the sliding surface, i.e., the end face that is located on the back surface side of the seal ring when the sliding surface side is defined as the front side of the seal ring.

[0027] As shown in FIG. 1B, an inner diameter surface 13b of the annular protrusion 13 is continuous with the back surface 12a of the base 12 and the back surface 13a of the annular protrusion 13, and is substantially perpendicular to these surfaces.

[0028] More specifically, the inner diameter surface 13b curves in a quarter-circular arc shape from the outer diameter end of the back surface 12a of the base 12 toward the outer diameter side and the left axial direction, extends linearly toward the left axial direction, slopes toward the outer diameter side, and extends leftward, continuing to the inner diameter end of the back surface 13a of the annular convex portion 13.

[0029] The rotary seal ring 10 has an annular recess 14 formed by a back surface 12a of the base portion 12 and an inner diameter surface 13b of the annular protrusion 13. The annular recess 14 is open to the left in the axial direction and toward the inner diameter side.

[0030] As shown in FIG. 1( a ), the sleeve 20 includes an inner cylinder 21 , an annular wall 22 , and an outer cylinder 23 .

[0031] The inner cylinder 21 has a cylindrical shape that extends in the axial direction.

[0032] The annular wall 22 is flat and annular and extends radially outward from the left end of the inner cylinder 21 .

[0033] The outer cylinder 23 is cylindrical and extends axially rightward from the outer diameter end of the annular wall 22. The outer cylinder 23 has a larger diameter than the inner cylinder 21.

[0034] The sleeve 20 defines an accommodation space by the outer peripheral surface of the inner cylinder 21, the inner diameter side curved surface of the annular wall 22, the inner side surface 22a, the outer diameter side curved surface, and the inner peripheral surface of the outer cylinder 23. The rotary seal ring 10 and the cup gasket 30 are disposed within this accommodation space.

[0035] The inner diameter side curved surface of the annular wall 22 curves in a quarter arc shape from the left end of the outer diameter surface of the inner cylinder 21 toward the outer diameter side and to the left in the axial direction. The inner surface 22a of the annular wall 22 extends linearly in the radial direction from the outer diameter end of the inner diameter side curved surface and is the front end face of the case. The outer diameter side curved surface of the annular wall 22 curves in a quarter arc shape from the outer diameter end of the inner surface 22a toward the outer diameter side and to the right in the axial direction, and continues to the left end of the inner peripheral surface of the outer cylinder 23.

[0036] The front end face of the case is the end face that is arranged opposite the back end face of the seal ring, that is, the end face that is located on the front side when the seal ring is used as the reference.

[0037] The cup gasket 30 is made of elastomer and has an axially extending portion 31 and a radially extending portion 32 that is radially outwardly of the axially extending portion 31, and has a generally L-shaped cross section. Note that the cup gasket 30 is not limited to being made of elastomer, and may be made of any suitable material that is more easily elastically deformable than the rotary seal ring 10 or the sleeve 20.

[0038] The axially extending portion 31 is a cylindrical portion extending in the axial direction, and a back surface 31a of the axially extending portion 31 extends linearly in the radial direction (see FIG. 1(b)).

[0039] 1B, the axially extending portion 31 has a portion on the right side of the axial center that bulges outward in the radial direction. The outer peripheral surface that extends linearly to the left of this bulging portion is referred to as the outer peripheral surface 31b of the axially extending portion 31.

[0040] The axially extending portion 31 has a bulging portion 31c consisting of a portion bulging outward from the axial center to the right and a portion bulging inward from the axial center. The shape of the bulging portion 31c may be only the portion bulging outward from the axial center to the right, or only the portion bulging inward from the axial center, or may be changed as appropriate.

[0041] The radially extending portion 32 is a flat, annular portion that extends radially outward from the left end of the axially extending portion 31, in other words, it is located radially outward and axially left of the outer circumferential surface 31b.

[0042] A back surface 32a of the radially extending portion 32 is flush with the back surface 31a of the axially extending portion 31 and extends linearly in the radial direction.

[0043] The outer diameter surface 32b of the radially extending portion 32 extends axially rightward from the outer diameter end of the back surface 32a, curves in a quarter-circular arc shape toward the inner diameter side and toward the axial rightward, and continues to the outer diameter end of the front surface 32c of the radially extending portion 32. The front surface 32c of the radially extending portion 32 extends linearly in the radial direction.

[0044] Next, a description will be given of an assembly method for the rotating element 4. First, the cup gasket 30 is fitted into the rotary seal ring 10.

[0045] The tip end of the axially extending portion 31 of the cup gasket 30 is fitted into the base portion 12 of the rotary seal ring 10. The axis of the cup gasket 30 and the axis of the rotary seal ring 10 are arranged substantially on the same straight line.

[0046] 1A, the inner diameter D1 of the annular recess 14 in the rotary seal ring 10 is longer than the outer diameter D2 of the radially extending portion 32 in the cup gasket 30 (D1 > D2). This prevents the radially extending portion 32 from coming into contact with the annular protrusion 13 when the cup gasket 30 is fitted into the rotary seal ring 10.

[0047] To clearly show the radial gap R1, the inner diameter D1 of the rotary seal ring 10 is taken as the axially extending portion of the inner diameter surface 13b of the rotary seal ring 10. Similarly, the outer diameter D2 of the radially extending portion 32 is taken as the axially extending portion of the outer diameter surface 32b of the radially extending portion 32.

[0048] 1(b), when the cup gasket 30 is fitted into the rotary seal ring 10, the front surface 32c of the radially extending portion 32 of the cup gasket 30 comes into contact with the back surface 12a of the base portion 12. This positions the cup gasket 30 in the axial direction relative to the rotary seal ring 10.

[0049] Furthermore, a radial gap R1 is formed between the inner diameter surface 13b of the annular protrusion 13 of the rotary seal ring 10 and the outer diameter surface 32b of the radially extending portion 32 of the cup gasket 30. The radial gap R1 is continuous over the circumferential and axial directions of the outer diameter surface 32b of the radially extending portion 32. In other words, the entire inner diameter surface 13b of the rotary seal ring 10 and the entire outer diameter surface 32b of the cup gasket 30 are in a non-contact state, i.e., the outer diameter surface 32b is in a non-contact state with the inner diameter surface 13b over the circumferential and axial directions.

[0050] Next, the rotary seal ring 10 together with the cup gasket 30 is fitted onto the inner cylinder 21 of the sleeve 20 .

[0051] Although not shown directly, in the assembly method of the rotating element 4, the right axial end 21 a of the inner cylinder 21 is not curved toward the outer diameter side as shown in Fig. 1(a) but simply extends in the axial direction. The bending of the right axial end 21 a of the inner cylinder 21 is performed after the rotating element 4 and the stationary element 5 are assembled.

[0052] The axially extending portion 31 of the cup gasket 30 is fitted onto the outer surface of the inner cylinder 21 of the sleeve 20. The axis of the cup gasket 30 and the axis of the sleeve 20 are arranged on approximately the same straight line.

[0053] The bulging portion 31c (see FIG. 1(b)) of the axially extending portion 31 is pressed against the outer peripheral surface of the inner cylinder 21 and the inner peripheral surface of the base portion 12 of the rotary seal ring 10. This provides a seal between the rotary seal ring 10 and the sleeve 20.

[0054] Note that, as in a third embodiment described below, the bulging portion 31c does not have to be provided as long as it is possible to seal the gap between the rotary seal ring 10 and the sleeve 20. In other words, the shape of the axially extending portion 31 may be changed as appropriate as long as it is possible to seal the gap between the rotary seal ring 10 and the sleeve 20.

[0055] As described above, the radially extending portion 32 of the cup gasket 30 abuts against the base portion 12. Therefore, when the rotary seal ring 10 is moved toward the annular wall 22 of the sleeve 20, the cup gasket 30 is restricted from moving axially to the right relative to the rotary seal ring 10, i.e., in the removal direction.

[0056] The back surface 13a of the annular protrusion 13 of the rotary seal ring 10 comes into axial contact with the inner surface 22a of the annular wall 22. This positions the rotary seal ring 10 in the axial direction relative to the sleeve 20, completing the assembly method of the rotating element 4.

[0057] In the present invention, "contact in the axial direction" means that the direction of contact includes at least an axial component. Furthermore, "contact" in the present invention is not limited to a state of contact without gaps, but also includes a state in which, viewed microscopically, true contact areas are scattered and fluid flows between the members due to capillary action or the like, in other words, a state in which the members are in contact from a macroscopic perspective.

[0058] The assembly method of the rotating element 4 may be such that the cup gasket 30 is first fitted onto the sleeve 20, and then the rotary seal ring 10 is assembled to the sleeve 20, as in Example 2 described below, or may be modified as appropriate.

[0059] In the rotating element 4 assembled as described above, as shown in FIG. 1( b ), an axial space S11 is formed between the base 12 of the rotary seal ring 10 and the annular wall 22 of the sleeve 20 in the axial direction.

[0060] The axial space S11 is defined by the back surface 12a of the base portion 12, the inner diameter surface 13b of the annular protrusion 13 of the rotary seal ring 10, and the inner surface 22a of the annular wall 22. In other words, the axial space S11 is a space sandwiched between the back surface 12a of the base portion 12 and the inner surface 22a of the annular wall 22, which are opposed to each other in the axial direction.

[0061] The axial dimension L1 of the axial space S11, in other words, the axial dimension of the annular protrusion 13 in the rotary seal ring 10, and the axial dimension of the annular recess 14 is longer than the axial dimension L2 of the radial extension portion 32 in the cup gasket 30 (L1 > L2).

[0062] As a result, with the simple configuration of disposing the radially extending portion 32 of the cup gasket 30 in the annular recess 14 of the rotary seal ring 10, an axial gap A1 can be formed between the inner surface 22a of the annular wall 22 of the sleeve 20 and the back surfaces 31a, 32a of the cup gasket 30. The axial dimension L3 of the axial gap A1 is the difference between the axial dimension L1 and the axial dimension L2 (L3 = L1 - L2).

[0063] By forming the axial gap A1, the radially extending portion 32 is sandwiched between the base portion 12 of the rotary seal ring 10 and the sleeve 20, making it less likely to be elastically deformed. In other words, it is possible to reduce as much as possible the elastic force of the radially extending portion 32 acting on the rotary seal ring 10. As a result, the surface pressure of the mechanical seal 1 is stable.

[0064] Furthermore, the mechanical seal 1 can maintain a state in which the back surface 13a of the annular protrusion 13 of the rotary seal ring 10 is in face-to-face contact with the inner surface 22a of the annular wall 22 of the sleeve 20. This allows the seal width W1 of each mechanical seal 1 in the assembly, i.e., the axial dimension from the sliding surface 11 of the rotary seal ring 10 to the outer surface 22b of the annular wall 22, to be uniform.

[0065] The back surface 13a of the annular protrusion 13 and the inner surface 22a of the sleeve 20 are the back surface end surface of the seal ring of the present invention and the front surface end surface of the case of the present invention, which abut in the axial direction, but these may be changed as appropriate. For example, the outer diameter side back surface of the base 12, which protrudes outward from the annular protrusion 13, may be the back surface end surface of the seal ring of the present invention, or the outer diameter side inner surface formed axially to the right of the inner surface 22a of the sleeve 20 may be the front surface of the case of the present invention, which abuts against the back surface end surface in the axial direction. In other words, the back surface end surface of the seal ring of the present invention and the front surface end surface of the case of the present invention may be configured to abut in the axial direction, and their positions, number, and shapes may be changed as appropriate.

[0066] In addition, in the mechanical seal 1, the elastic restoring force of the biasing member 60 acts on the rotary seal ring 10 via the stationary seal ring 40 (see FIG. 1(a)). Therefore, the back surface 13a of the annular protrusion 13 of the rotary seal ring 10 can be more reliably maintained in contact with the inner surface 22a of the annular wall 22.

[0067] As a result, the sealed fluid F is less likely to suddenly flow into the axial space S11 through a gap between the back surface 13a of the annular protrusion 13 and the inner surface 22a of the annular wall 22. This prevents any change in the fluid pressure of the sealed fluid F from immediately affecting the cup gasket 30.

[0068] In addition, since the back surface 13a of the annular convex portion 13 is in face contact with the inner surface 22a of the annular wall 22, heat dissipation properties against sliding heat generation are improved, and contaminants and impurities are less likely to enter the axial space S11.

[0069] 1(a), the radial dimension T1 from the inner circumferential surface to the outer circumferential surface of the base portion 12 of the rotary seal ring 10 is approximately twice the radial dimension T2 of the back surface 13a of the annular protrusion 13 (T1 > T2). This ensures a sufficient contact area between the rotary seal ring 10 and the sleeve 20. This prevents relative tilting between the rotary seal ring 10 and the sleeve 20, making it easier to maintain the assembled state.

[0070] In other words, the annular recess 14 is formed while ensuring a sufficient contact area between the rotary seal ring 10 and the sleeve 20. This also applies to the case where an annular recess 224 is formed in the sleeve 220, as in Example 3 described below.

[0071] In this embodiment, the annular protrusion 13 is in face contact with the sleeve 20 to enhance heat dissipation, but this is not limited to this and the annular protrusion 13 may have a rivet-like protrusion or a wavy protrusion, i.e., it may be in point or line contact rather than face contact. Even with this configuration, the seal width W1 of each mechanical seal 1 in the assembly can be made uniform.

[0072] Furthermore, although the rotary seal ring 10 is configured to directly abut against the sleeve 20, this is not limiting and the rotary seal ring 10 and sleeve 20 may also abut indirectly. More specifically, a third member such as a spacer or washer that is separate from one of the seal rings and the case and is made of a material that is more rigid than the cup gasket, in other words, that is less susceptible to elastic deformation, may be provided between these. Even with this configuration, the seal width W1 of each mechanical seal 1 in the assembly can be made uniform.

[0073] Furthermore, the axial space in which the radially extending portion of the cup gasket is disposed is not limited to a configuration defined only by one of the seal rings and the case, but may be defined by one of the seal rings, the case, and a third member, or may be modified as appropriate. In other words, the axial dimension of the axial space does not have to be the same as the axial dimension of the annular recess.

[0074] Furthermore, in the mechanical seal 1 of this embodiment, the axial gap A1 is formed over the radial and circumferential directions of the back surfaces 31 a, 32 a of the cup gasket 30. In other words, the entire inner surface 22 a of the sleeve 20 and the entire back surfaces 31 a, 32 a of the cup gasket 30 are in a non-contact state, i.e., the back surfaces 31 a, 32 a are in a non-contact state with the inner surface 22 a over the circumferential and radial directions. This prevents the radial extension 32 from being compressed in the axial direction, and the resulting elastic force from acting on the rotary seal ring 10.

[0075] The axial dimension L3 of the axial gap A1 is approximately one-tenth of the axial dimension L1 of the axial space S11. This makes it difficult for the cup gasket 30 to slip out from between the rotary seal ring 10 and the sleeve 20.

[0076] The axial dimension L3 of the axial gap A1 may be changed as appropriate. From the viewpoint of preventing the cup gasket 30 from slipping out from between the rotary seal ring 10 and the sleeve 20, it is preferable that the axial dimension L3 of the axial gap A1 be one-third or less of the axial dimension L1 of the axial space S11.

[0077] Furthermore, in the mechanical seal 1 of this embodiment, since an axial gap A1 is formed, even if the cup gasket 30 expands due to thermal expansion or absorbing the sealed fluid F, the radial extension portion 32 is less likely to come into contact with the annular wall 22.

[0078] Furthermore, the back surfaces 31 a, 32 a of the cup gasket 30 are disposed approximately parallel to the inner surface 22 a of the sleeve 20. Therefore, the axial gap A1 can be formed in the radial and circumferential directions of the back surface 32 a of the radially extending portion 32, while the seal width W1 can be shortened.

[0079] Note that back surfaces 31 a, 32 a of cup gasket 30 may be inclined relative to inner surface 22 a of sleeve 20. That is, at least one of back surfaces 31 a, 32 a and inner surface 22 a may be an inclined surface or a curved surface inclined with respect to the axial direction, may have stud-like or wavy convex portions formed thereon, may be textured, and the shape may be changed as appropriate as long as axial gap A1 can be formed.

[0080] Furthermore, in the mechanical seal 1 of this embodiment, by arranging the radially extending portion 32 of the cup gasket 30 in the annular recess 14 of the rotary seal ring 10, it is possible to increase the axial dimension L4 from the sliding surface 11 of the rotary seal ring 10 to the back surface 13a of the annular protrusion 13, assuming the same seal width W1, compared to a configuration in which the radially extending portion 232 is arranged axially outward of the rotary seal ring 210 as in Example 3 described below. This makes it easier to form the sliding surface 11 flat.

[0081] Furthermore, the axial dimension of the annular recess 14 in the rotary seal ring 10, i.e., the axial dimension L1 of the axial space S11, is approximately one-third of the axial dimension L4 of the rotary seal ring 10. This ensures sufficient rigidity in the rotary seal ring 10, while making it easier to form the sliding surface 11 flat.

[0082] The axial dimension of the annular recess 14 may be changed as appropriate. From the viewpoint of forming the sliding surface 11 flat while ensuring the rigidity of the rotary seal ring 10, the axial dimension of the annular recess 14 is preferably one-half or less, and more preferably one-third or less, of the axial dimension L4 of the rotary seal ring 10.

[0083] Furthermore, in the mechanical seal 1 of this embodiment, the radially extending portion 32 abuts against the base portion 12 of the rotary seal ring 10 in the axial direction. This restricts axial movement of the cup gasket 30, thereby more reliably forming the axial gap A1.

[0084] Furthermore, the mechanical seal 1 is an inside type. The fluid pressure of the sealed fluid F acts on the radially extending portion 32 of the cup gasket 30, which pushes the cup gasket 30 toward the base portion 12 of the rotary seal ring 10. Meanwhile, the radially extending portion 32 is already in contact with the base portion 12. This more reliably restricts the axial movement of the cup gasket 30.

[0085] While the cup gasket 30 has been described as having the front surface 32c of the radially extending portion 32 in face-to-face contact with the back surface 12a of the base 12, the invention is not limited to this, and the back surface 12a of the base 12 may be an inclined surface or a curved surface that extends at an angle from the inner diameter end of the back surface 13a of the annular convex portion 13 toward the inner peripheral surface of the base 12, a stud-like or wavy convex portion may be formed on the back surface 12a, or the back surface 12a may be textured. Any suitable modification may be made as long as the configuration is capable of restricting axial movement of the cup gasket 30. In other words, the cross-sectional shape of the annular recess 14 may also be suitable as long as the configuration is capable of restricting axial movement of the cup gasket 30.

[0086] Similarly, the radial extension portion 32 may be modified as appropriate as long as it has a configuration that can regulate the axial movement of the cup gasket 30, and may have an inclined surface or curved surface that is inclined with respect to the axial direction, may have a rivet-shaped or wavy convex portion, may be embossed, or may have a shape that follows the shape of the concave portion.

[0087] Furthermore, in the mechanical seal 1 of this embodiment, the radially extending portion 32 is arranged so as to leave a radial gap R1 between it and the annular protrusion 13 of the rotary seal ring 10. As a result, even if the cup gasket 30 expands, the radially extending portion 32 comes into contact with the annular protrusion 13 and elastically deforms, preventing it from coming into contact with the annular wall 22. This makes it possible to more reliably leave the axial gap A1.

[0088] The back surfaces 31 a, 32 a of the cup gasket 30 may be in partial contact with the inner surface 22 a of the sleeve 20. In other words, the axial gap A1 does not have to be continuous in both the circumferential and radial directions. Even with this configuration, the elastic restoring force generated in the radially extending portion 32 can be reduced.

[0089] The rotating element 4 of this embodiment may also be applied to an outside-type mechanical seal in which the sealed fluid F flows into the inner space S1 and the outer space S2 is open to the atmosphere A. When applied to the outside-type mechanical seal, it is preferable that the cup gasket 30 be configured to abut against the annular wall 22 of the sleeve 20, as in Example 3 described below. This is to restrict axial movement of the cup gasket 30.

[0090] Furthermore, as in Example 2 described later, the inner tube 21 of the sleeve 20 may be formed in an inverse tapered shape, so that the axially extending portion 31 of the cup gasket 30 located on the inner diameter side can be prevented from slipping out.

[0091] Next, a mechanical seal according to a second embodiment will be described with reference to Fig. 2. Note that the description of the same configuration as in the first embodiment will be omitted.

[0092] As shown in FIG. 2, the mechanical seal 101 of this embodiment is mainly composed of a rotating element 104 and a stationary element 5 .

[0093] As shown in FIG. 2B , the back surface 112 a of the base portion 112 is located on the outer diameter side of the annular protrusion 113 .

[0094] The annular recess 114 of the rotary seal ring 110 is defined by a back surface 112a of the base portion 112 and an outer diameter surface 113b of the annular protrusion 113. The annular recess 114 is open to the left in the axial direction and toward the outer diameter side.

[0095] The radially extending portion 132 of the cup gasket 130 is a portion located radially inward of the inner peripheral surface 131 b of the axially extending portion 131 .

[0096] Next, a description will be given of an assembly method for the rotating element 104. First, the cup gasket 130 is fitted into the outer cylinder 123 of the sleeve 120.

[0097] The axially extending portion 131 of the cup gasket 130 is fitted into the outer cylinder 123 of the sleeve 120 .

[0098] Furthermore, the back surfaces 131a and 132a of the cup gasket 130 come into face-to-face contact with the inner surface 122a of the annular wall 122 of the sleeve 120. This positions the cup gasket 130 relative to the sleeve 120.

[0099] Next, the rotary seal ring 110 is fitted into the cup gasket 130 .

[0100] The base portion 112 of the rotary seal ring 110 is fitted into the axially extending portion 131 of the cup gasket 130 .

[0101] Furthermore, a back surface 113a of the annular protrusion 113 of the rotary seal ring 110 comes into face contact with an inner surface 122a of the sleeve 120. This positions the rotary seal ring 110 relative to the sleeve 120 and the cup gasket .

[0102] In the rotating element 104 assembled as described above, the bulging portion 131c (see FIG. 2B) of the axially extending portion 131 is pressed against the inner circumferential surface 123a of the outer cylinder 123 and the outer circumferential surface of the base portion 112 of the rotary seal ring 110. This creates a seal between the rotary seal ring 110 and the sleeve 120.

[0103] In addition, in the assembled rotating element 104 , an axial space S12 is formed between the base portion 112 of the rotary seal ring 110 and the annular wall 122 of the sleeve 120 .

[0104] Additionally, an axial gap A2 is formed between the back surface 112a of the base portion 112 of the rotary seal ring 110 and the front surface 132c of the radially extending portion 132 of the cup gasket 130. This reduces as much as possible the elastic force that acts on the rotary seal ring 110 when the radially extending portion 132 is compressed in the axial direction. This stabilizes the surface pressure of the mechanical seal 101.

[0105] Furthermore, the mechanical seal 101 is an inside type. Fluid pressure of the sealed fluid F acts on the axially extending portion 131 facing the outer space S2, pressing the cup gasket 130 toward the annular wall 122 of the sleeve 120. Meanwhile, the radially extending portion 132 abuts against the annular wall 122. This more reliably restricts axial movement of the cup gasket 130.

[0106] Additionally, a radial gap R2 is formed between the outer diameter surface 113b of the annular protrusion 113 of the rotary seal ring 110 and the inner diameter surface 132b of the radial extension 132 of the cup gasket 130. This makes it possible to more reliably leave the axial gap A2.

[0107] Additionally, the outer cylinder 123 of the sleeve 120 has a reverse tapered portion. More specifically, the inner peripheral surface 123a of the outer cylinder 123 extends at an inclination toward the inner diameter side toward the right in the axial direction, i.e., toward the axially extending portion 131 of the cup gasket 130. As a result, the gap between the sleeve 120 and the rotary seal ring 110 narrows as it approaches the stationary element 5, thereby reliably preventing the cup gasket 130 from slipping out.

[0108] The rotating element 104 of this embodiment may also be applied to an outside-type mechanical seal. When applied to an outside-type mechanical seal, the cup gasket 130 may be configured to abut against the annular wall 122 of the sleeve 120 as in this embodiment, or the radially extending portion 132 of the cup gasket 130 may be configured to abut against the base portion 112 of the rotating seal ring 110 as in the first embodiment.

[0109] Next, a mechanical seal according to a third embodiment will be described with reference to Fig. 3. Note that the description of the same configuration as in the first embodiment will be omitted.

[0110] As shown in FIG. 3, the mechanical seal 201 of this embodiment is mainly composed of a rotating element 204 and a stationary element 5 .

[0111] The rotary seal ring 210 has a substantially rectangular cross section.

[0112] The sleeve 220 has an annular recess 224 (see FIG. 3B) formed on the inner diameter side of the annular wall 222, which is recessed axially leftward from the inner surface 222a and opens axially rightward.

[0113] As shown in FIG. 3B, the annular recess 224 is composed of the outer circumferential surface of the inner cylinder 221, an inner diameter side curved surface, a flat surface 224a, and an inner diameter surface 224b.

[0114] The flat surface 224a extends linearly in the radial direction. The inner diameter surface 224b extends linearly to the right in the axial direction, intersecting approximately perpendicularly with the outer diameter end of the flat surface 224a, and intersecting approximately perpendicularly with the inner diameter end of the inner side surface 222a.

[0115] Next, a description will be given of an assembly method for the rotating element 204. First, the cup gasket 230 is fitted onto the inner cylinder 221 of the sleeve 220.

[0116] Further, the radially extending portion 232 of the cup gasket 230 is disposed within the annular recess 224 of the sleeve 220. Further, the back surfaces 231a and 232a of the cup gasket 230 are in face-to-face contact with the flat surface 224a of the sleeve 220.

[0117] Next, the rotary seal ring 210 is fitted onto the cup gasket 230 .

[0118] Additionally, a back surface 210a of the rotary seal ring 210 abuts against an inner surface 222a of the sleeve 220. The back surface 210a of the rotary seal ring 210 is the back surface end face of the seal ring, and the inner surface 222a of the sleeve 220 is the front surface end face of the case.

[0119] In the rotating element 204 assembled as described above, the bulging portion 231c (see FIG. 3B) of the axially extending portion 231 is pressed against the outer peripheral surface of the inner cylinder 221 and the inner peripheral surface of the rotary seal ring 210. This creates a seal between the rotary seal ring 210 and the sleeve 220.

[0120] In addition, in the assembled rotating element 204, an axial space S13 is formed between the back surface 210a of the rotary seal ring 210 and the flat surface 224a of the sleeve 220 in the axial direction.

[0121] Additionally, an axial gap A3 is formed between the back surface 210a of the rotary seal ring 210 and the front surface 232c of the radially extending portion 232 of the cup gasket 230. This reduces as much as possible the elastic force that acts on the rotary seal ring 210 when the radially extending portion 232 is compressed in the axial direction. Therefore, the surface pressure of the mechanical seal 201 is stable.

[0122] Furthermore, the mechanical seal 201 is an inside type. The fluid pressure of the sealed fluid F acts on the radially extending portion 232 of the cup gasket 230, which presses the cup gasket 230 toward the flat surface 224a of the sleeve 220. Meanwhile, the radially extending portion 232 abuts against the flat surface 224a. This more reliably restricts the axial movement of the cup gasket 230.

[0123] Furthermore, a radial gap R3 is formed between the inner diameter surface 224b of the sleeve 220 and the outer diameter surface 232b of the radially extending portion 232 of the cup gasket 230. This makes it possible to more reliably leave the axial gap A3.

[0124] Furthermore, by forming the annular recess 224 in the sleeve 220, in which the radially extending portion 232 is disposed, the seal ring is easier to manufacture than when the annular recess 14 is formed in the rotary seal ring 10 as in Example 1. More specifically, when molding the seal ring, pressure is more easily transmitted uniformly to the seal ring, making it less likely that variations in density will occur.

[0125] The recess in the present invention may be formed in the case as in this embodiment, or may be formed in the seal ring as in the first and second embodiments, or may be formed in both the case and the seal ring. If the annular recess in the present invention is formed in both the case and the seal ring, the seal width can be made shorter than in a configuration in which the recess is formed only in the case as in this embodiment, and manufacturing of the seal ring is easier than in the first and second embodiments.

[0126] The rotating element 204 of this embodiment may also be applied to an outside-type mechanical seal in which the sealed fluid F flows into the inner space S1 and the outer space S2 is open to the atmosphere A. Even when applied to an outside-type mechanical seal, the radially extending portion 232 abutting against the flat surface 224 a can restrict the cup gasket 230 from moving in the axial direction.

[0127] Next, a mechanical seal according to a fourth embodiment will be described with reference to Fig. 4. Note that the description of the same configuration as in the first embodiment will be omitted.

[0128] As shown in FIG. 4, the mechanical seal 301 of this embodiment is mainly composed of a rotating element 304 and a stationary element 5 .

[0129] 4(b), the sleeve 320 has an annular recess 324 formed on the outer diameter side of the annular wall 322. The annular recess 324 is composed of an inner circumferential surface of the outer cylinder 323, an outer diameter side curved surface, a flat surface 324a, and an outer diameter surface 324b.

[0130] The left end of the axially extending portion 331 of the cup gasket 330 protrudes further left than the radially extending portion 332. A back surface 331a of the axially extending portion 331 is located axially left of a back surface 332a of the radially extending portion 332.

[0131] Furthermore, the back surface 331a of the axially extending portion 331 is provided on the outer diameter side of the outer peripheral surface of the rotary seal ring 310. In other words, the back surface 331a of the axially extending portion 331 does not overlap with the rotary seal ring 310 in the axial direction but is separated from it in the radial direction.

[0132] Next, a description will be given of an assembly method for the rotary element 304. First, the cup gasket 330 is fitted onto the rotary seal ring 310.

[0133] An axially extending portion 331 of the cup gasket 330 is fitted onto the rotary seal ring 310. A front surface 332c of the radially extending portion 332 of the cup gasket 330 abuts against a back surface 310a of the rotary seal ring 310.

[0134] Next, the rotary seal ring 310 is fitted into the outer cylinder 323 of the sleeve 320 .

[0135] The axially extending portion 331 of the cup gasket 330 is fitted into the outer cylinder 323 of the sleeve 320 .

[0136] Furthermore, the back surface 310 a of the rotary seal ring 310 comes into contact with the inner surface 322 a of the sleeve 320 .

[0137] The rotating element 304 assembled as described above is pressed against the inner circumferential surface of the outer cylinder 323 and the outer circumferential surface of the rotary seal ring 310 with the axial extension 331 in face-to-face contact with the inner circumferential surface of the outer cylinder 323 and the outer circumferential surface of the rotary seal ring 310. This provides a seal between the rotary seal ring 310 and the sleeve 320. Note that the axial extension 331 may be provided with a bulge as in the first embodiment.

[0138] In addition, in the assembled rotating element 304, an axial space S14 is formed between the back surface 310a of the rotary seal ring 310 and the flat surface 324a of the sleeve 320 in the axial direction.

[0139] Additionally, an axial gap A4 is formed between the flat surface 324a of the sleeve 320 and the back surface 332a of the radially extending portion 332 of the cup gasket 330. This reduces as much as possible the elastic force of the radially extending portion 332 being compressed in the axial direction and acting on the rotary seal ring 310. This stabilizes the surface pressure of the mechanical seal 301.

[0140] Axial gap A4 is formed in the radial and circumferential directions of back surface 332a of cup gasket 330. This prevents radial extension 332 from being compressed in the axial direction, and the resulting elastic force from acting on rotary seal ring 310.

[0141] Furthermore, a back surface 331a of the axially extending portion 331 is pressed against the flat surface 324a of the sleeve 320. The right end of the axially extending portion 331, which is located axially opposite to the back surface 331a, faces the external space S2. Furthermore, the back surface 331a of the axially extending portion 331 does not overlap with the rotary seal ring 310 in the axial direction, but is separated from it in the radial direction. As a result, even if the left end of the axially extending portion 331 elastically deforms, the elastic restoring force is less likely to act on the rotary seal ring 310.

[0142] In this way, as long as the radial extension portion 332 is arranged so as to leave an axial gap A4 between the rotary seal ring 310 and the sleeve 320, the axial extension portion 331 may be configured to abut against the sleeve 320.

[0143] In addition, axially extending portion 331 of cup gasket 330 protrudes further to the left than radially extending portion 332. Therefore, cup gasket 330 can more reliably form axial gap A4.

[0144] Furthermore, the mechanical seal 301 is an inside type. Fluid pressure of the sealed fluid F acts on the axially extending portion 331 facing the outer space S2, pressing the cup gasket 330 toward the annular wall 322 of the sleeve 320. Meanwhile, the back surface 331a of the axially extending portion 331 abuts against the annular wall 322. This more reliably restricts axial movement of the cup gasket 330.

[0145] Furthermore, a radial gap R4 is formed between the outer diameter surface 324b of the sleeve 320 and the inner diameter surface 332b of the radial extension portion 332 of the cup gasket 330. This prevents the radial extension portion 332 from abutting against the sleeve 320 and elastically deforming, and from abutting against the rotary seal ring 310. This makes it possible to more reliably leave the axial gap A4.

[0146] The rotating element 304 of this embodiment may be applied to an outside-type mechanical seal. When applied to an outside-type mechanical seal, the cup gasket 330 may be configured to abut against the annular wall 322 of the sleeve 320 as in this embodiment, or the radially extending portion 332 of the cup gasket 330 may be configured to abut against the rotary seal ring 310 as in the first embodiment.

[0147] Next, a mechanical seal according to a fifth embodiment will be described with reference to Fig. 5. Note that the description of the same configuration as in the first embodiment will be omitted.

[0148] As shown in FIG. 5, the mechanical seal 401 of this embodiment is mainly composed of a rotating element 404 and a stationary element 405 .

[0149] The rotating element 404 is mainly composed of a rotating seal ring 410 as the other seal ring, a sleeve 450, a coil spring 460 as a biasing member, a rubber bellows 470, a drive ring 480, and a collar 490. In other words, the mechanical seal 401 of this embodiment is of a rotating type.

[0150] The rotary seal ring 410 is attached to the rotary shaft 2 via a sleeve 450 and a rubber bellows 470. The sleeve 450 and the rubber bellows 470 are prevented from rotating relative to the rotary shaft 2 by a drive ring 480.

[0151] As a result, the rotary seal ring 410 is provided in a non-rotating state but movable in the axial direction relative to the rotary shaft 2. Furthermore, rubber bellows 470 seal the spaces between the rotary seal ring 410 and the rotary shaft 2 and between the rotary seal ring 410 and the sleeve 450.

[0152] Furthermore, the rotary seal ring 410 is biased in the axial direction by a coil spring 460 disposed between the sleeve 450 and the collar 490. This allows the sliding surface 411 of the rotary seal ring 410 and the sliding surface 441 of the stationary seal ring 440 to slide closely against each other.

[0153] The stationary element 405 is mainly composed of a stationary seal ring 440 as one of the seal rings, a seal case 420 as a case, and a cup gasket 430 .

[0154] The assembly method of the stationary element 405 is substantially the same as the assembly method of the rotating element 4 in the first embodiment, and therefore a description thereof will be omitted.

[0155] 5(b), the assembled stationary side element 405 is pressed in a state in which the axially extending portion 431 is in face-to-face contact with the outer peripheral surface of the inner cylinder 421 and the inner peripheral surface of the base portion 442 of the stationary seal ring 440. This creates a seal between the stationary seal ring 440 and the seal case 420.

[0156] In addition, in the assembled stationary element 405, the back surface 443a of the annular protrusion 443 of the stationary seal ring 440 and the inner surface 422a of the annular wall 422 are in face-to-face contact.

[0157] In addition, in the assembled stationary element 405, an axial space S15 is formed between the base portion 442 of the stationary seal ring 440 and the annular wall 422 of the seal case 420 in the axial direction.

[0158] The radially extending portion 432 of the cup gasket 430 is disposed in the annular recess 444 of the stationary seal ring 440 .

[0159] An axial gap A5 is formed between the inner surface 422a of the annular wall 422 and the back surfaces 431a, 432a of the cup gasket 430. This reduces as much as possible the elastic force that would otherwise be exerted on the stationary seal ring 440 when the radially extending portion 432 is compressed in the axial direction. This stabilizes the surface pressure of the mechanical seal 401.

[0160] Furthermore, a radial gap R5 is formed between the inner diameter surface 443b of the annular protrusion 443 of the stationary seal ring 440 and the outer diameter surface 432b of the radially extending portion 432 of the cup gasket 430. This makes it possible to more reliably leave the axial gap A5.

[0161] As explained above, even in a rotary mechanical seal in which a biasing member is installed on the rotary seal ring side, by applying the cup gasket structure of the present invention to the stationary sealing element, i.e., a structure in which an axial gap is formed between at least one of the stationary seal ring and the case and the radially extending portion, it is possible to achieve the same effect as a static mechanical seal.

[0162] The stationary element 405 of this embodiment may be applied to an outside-type mechanical seal in which the sealed fluid F flows into the inner space S1 and the outer space S2 is open to the atmosphere A. When applied to the outside-type mechanical seal, it is preferable that the cup gasket 430 be configured to abut against the annular wall 422 of the seal case 420, as in the third embodiment. This is to restrict axial movement of the cup gasket 430.

[0163] Although the embodiments of the present invention have been described above with reference to the drawings, the specific configuration is not limited to these embodiments, and the present invention also includes modifications and additions that do not deviate from the gist of the present invention.

[0164] For example, in the above-mentioned Examples 1 to 5, the axial gap is exemplified as being formed between one of the seal rings and the radially extending portion, or between the case and the radially extending portion, but this is not limited to this, and the axial gap may be formed between one of the seal rings and the radially extending portion, and between the case and the radially extending portion, respectively.

[0165] In addition, in the above-described first to fifth embodiments, the sealed fluid is described as a high-pressure liquid, but it is not limited to this and may be a gas or a low-pressure liquid, or a mist-like mixture of liquid and gas.

[0166] Furthermore, in the above-described Examples 1 to 5, the fluid on the leakage space side was described as being atmospheric air, which is a low-pressure gas, but this is not limited to this and it may be a liquid or a high-pressure gas, or a mist-like mixture of liquid and gas.

[0167] In addition, in the above-described first to fifth embodiments, the sealed fluid space side has been described as the high-pressure side and the leakage space side as the low-pressure side, but the sealed fluid space side may be the low-pressure side and the leakage space side may be the high-pressure side, or the sealed fluid space side and the leakage space side may be at approximately the same pressure.

[0168] REFERENCE SIGNS LIST 1 Mechanical seal 2 Rotating shaft 3 Housing 10 Rotating seal ring (one seal ring) 14 Annular recess (recess) 20 Sleeve (case) 30 Cup gasket (gasket) 31 Axial extension portion 32 Radial extension portion 40 Stationary seal ring (other seal ring) 50 Seal cover 60 Biasing member 70 Bellows 80 Band 90 Retainer 101 Mechanical seal 110 Rotating seal ring (one seal ring) 114 Annular recess (recess) 120 Sleeve (case) 123 Outer cylinder (reverse tapered portion) 130 Cup gasket (gasket) 131 Axial extension portion 132 Radial extension portion 201, 301 Mechanical seal 210, 310 Rotating seal ring (one seal ring) 220, 320 Sleeve (case) 224, 324 Annular recess (recess) 230, 330 Cup gasket (gasket) 231, 331 Axial extension portion 232, 332 Radial extension portion 401 Mechanical seal 410 Rotating seal ring (other seal ring) 420 Seal case (case) 430 Cup gasket (gasket) 431 Axial extension portion 432 Radial extension portion 440 Stationary seal ring (one seal ring) 444 Annular recess (recess) 450 Seal cover 460 Coil spring 470 Rubber bellows 480 Drive ring 490 Collar A1 to A5 Axial clearance R1 to R5 Radial clearance S11 to S15 Axial space W1 Seal width

Claims

1. A mechanical seal comprising: a stationary seal ring attached to a housing side, a rotating seal ring attached to a rotating shaft side inserted into the housing, a case holding one of the seal rings, and a gasket arranged between the one seal ring and the case, wherein the sliding surfaces of the seal rings which rotate relative to one another slide against each other to partition a sealed fluid space and a leakage space, wherein the one seal ring and the case abut in the axial direction, the gasket has a radially extending portion located between the one seal ring and the case in the axial direction, the radially extending portion being arranged in a recess formed by being recessed axially from at least one of the one seal ring and the case, and an axial gap being formed between the radially extending portion and at least one of the one seal ring and the case.

2. A mechanical seal as set forth in claim 1, wherein the axial gap is continuous in both the circumferential and radial directions.

3. A mechanical seal as set forth in claim 1, wherein said radially extending portion abuts against either said one seal ring or said case in the axial direction.

4. A mechanical seal according to any one of claims 1 to 3, wherein a radial gap is formed between at least one of said one seal ring and said case and said radial extension portion.

5. A mechanical seal as described in claim 1, wherein the gasket has an axially extending portion located radially between the one of the seal rings and the case, and the case has a reverse tapered portion that extends at an angle towards the axially extending portion towards the other seal ring.

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