Mechanical seal

Abstract

To provide a mechanical seal that can maintain sealing performance between an elastic sealing body and a case.SOLUTION: A mechanical seal comprises: a housing 3 surrounding a rotating shaft of a rotary device; a stationary side case 10 that has a radial wall 10b extending in a radial direction and is attached to the housing 3; a stationary seal ring 11 held on the stationary side case 10 via a spring 13; a rotary seal ring 21 that faces the stationary seal ring 11 and is attached to the rotating shaft 2; a bellows 12 sealing between the stationary seal ring 11 and the stationary side case 10; and a band 60 pressing the bellows 12 in the radial direction toward the stationary side case 10. The bellows 12 has a contact surface 157 that is in contact with the radial wall 10b. In the radial direction, a position on a side farthest from sealed fluid (an inner diameter side) (for example, a position of an outer circumferential surface 56d), where the band 60 and the bellows 12 are in contact with each other, is located on a side farther from the seal fluid (an inner diameter side) than a position on a side farthest from the sealed fluid of the contact surface 157 (a position of a boundary portion 158).SELECTED DRAWING: Figure 4

Description

[[Technical Field]]

[0001] The present invention relates to a mechanical seal that shaft-seals a rotating shaft. [[Background Art]]

[0002] A mechanical seal is used by being installed between a housing of a fluid device and a rotating shaft arranged to penetrate through the housing. The sliding surface of a stationary sealing ring fixed to a stationary side case mounted on the housing and the sliding surface of a rotating sealing ring that is fixed to a rotating side case mounted on the rotating shaft and rotates are brought into sliding contact in the circumferential direction, so that it has the function of reducing friction generated on the sliding surfaces and preventing leakage of the sealed fluid.

[0003] This type of mechanical seal uses a secondary seal such as an O-ring or a bellows to prevent leakage from the installation position of the sealing ring. By using a bellows that has elasticity in the longitudinal direction, the axial movement of the sealing ring can be smoothly performed. For example, the mechanical seal disclosed in Patent Document 1 includes a case having an axial wall extending axially along the inner peripheral surface of the stationary sealing ring and a radial wall extending radially along the back surface of the stationary sealing ring at a position away from the stationary sealing ring; a pressing portion at one axial end is attached to the stationary sealing ring from the outer diameter side, and a pressing portion at the other axial end is pressed toward the axial wall of the case, so that the bellows seals between the case and the stationary sealing ring; and a fixing member that presses the pressing portion of the bellows from the outer diameter side. Specifically, the pressing portion of the bellows has an axial portion extending along the axial wall of the case and a radial portion extending along the radial wall of the case, and the axial portion of the pressing portion of the bellows is pressed toward the inner diameter direction against the case by the fixing member. [[Prior Art Literature]] [[Patent Literature]]

[0004] [[Patent Document 1]] Utility Model Registration No. 3210688 (pages 7-8, Figure 2) [[Summary of the Invention]] [Problems that the invention aims to solve]

[0005] In the mechanical seal described in Patent Document 1 above, the axial portion of the bellows' pressing part is pressed inward by a fixing member. However, the high pressure of the fluid to be sealed pulls the radial portion away from the radial wall of the case, making it easier for the fluid to be sealed to enter the gap created between the radial portion and the radial wall. This results in a problem where the sealing performance between the radial portion and the radial wall of the case is reduced.

[0006] This invention was made in view of these problems, and aims to provide a mechanical seal that can maintain airtightness between the bellows and the case. [Means for solving the problem]

[0007] To solve the aforementioned problems, the mechanical seal of the present invention is A housing that surrounds the rotating shaft of a rotating machine, A case having radially extending radial walls and attached to the housing, One sealing ring is held in the case via a biasing means, The other sealing ring is attached to the rotating shaft and contacts the other sealing ring to seal the fluid to be sealed, An elastic member that seals the space between the one sealing ring and the case, A mechanical seal comprising a fixing member that presses the elastic member radially toward the case, The elastic member has a contact portion that contacts the radial wall, In the radial direction, the position on the side furthest from the sealed fluid where the fixing member and the elastic member come into contact is located on a side further from the sealed fluid than the position on the side furthest from the sealed fluid at the contact portion. According to this, when pressure from the sealed fluid is applied, a force acts toward the case side at the contact point of the elastic member, thus maintaining airtightness between the elastic member and the case.

[0008] The fixing member may be positioned on the side of the elastic member that is to be sealed with fluid. According to this, deformation of the elastic member away from the case can be restricted.

[0009] The fixing member may have a first portion extending along the axial direction and a second portion extending along the radial direction. According to this, the elastic member can be pressed in both the radial and axial directions.

[0010] The elastic member side at the corner between the first portion and the second portion may be formed in a curved shape. According to this, the fixing member can be brought into smooth contact with the elastic member.

[0011] The elastic member may have a tapered shape formed from the radially pressed portion to the contact portion. According to this, a uniform stress can be applied to the bent portion of the bellows, from the axial portion to the radial portion.

[0012] The aforementioned tapered shape may consist of multiple tapered surfaces. According to this, the gap between the case and the elastic member is reduced, while the elastic member can efficiently undergo elastic deformation within that gap.

[0013] The elastic member may have a protrusion that restricts the axial movement of the fixing member. According to this, the axial movement of the fixed member is restricted, allowing the radial portion of the elastic member to be stably brought into contact with the radial wall of the case, thereby ensuring airtightness. [Brief explanation of the drawing]

[0014] [Figure 1] This is a cross-sectional view showing a mechanical seal according to an embodiment of the present invention. [Figure 2] This is a cross-sectional view showing the main part of Figure 1. [Figure 3](a) is a cross-sectional view showing a bellows, and (b) is a cross-sectional view showing a main part of (a). [Figure 4] (a) is a cross-sectional view of a main part showing a state where the pressure of a fluid to be sealed is not applied in an assembled state of a mechanical seal, and (b) is a cross-sectional view showing a band. [Figure 5] This is a cross-sectional view of a main part showing a state where the pressure of the fluid to be sealed is applied in the assembled state of the mechanical seal. [Figure 6] This is a schematic diagram for explaining deformation of the bellows. [Figure 7] This is a cross-sectional view showing a bellows as a modified example of the present invention. [Figure 8] This is a cross-sectional view showing a bellows as another modified example of the present invention. MODE FOR CARRYING OUT THE INVENTION

[0015] An embodiment for carrying out the mechanical seal according to the present invention will be described below based on examples. EXAMPLE

[0016] A mechanical seal provided between a rotary shaft of a rotating device and a housing surrounding the rotary shaft according to Example 1 will be described with reference to FIGS. 1 to 6. Hereinafter, the description will be given with the left side of the drawing sheet of FIG. 1 being defined as the left side and the right side of the drawing sheet being defined as the right side.

[0017] As shown in FIG. 1, a mechanical seal 1 is an inside-type mechanical seal that seals a fluid to be sealed F that tends to leak from an outer diameter side toward an inner diameter side. In the following description, a space on an inner diameter side between a stationary seal ring 11 and a rotary seal ring 21 is defined as the atmosphere A side, and a space on an outer diameter side between the stationary seal ring 11 and the rotary seal ring 21 is defined as the fluid to be sealed F side.

[0018] The mechanical seal 1 of the present example includes a rotary-side element R and a stationary-side element S, and suppresses leakage of the fluid to be sealed from one of the fluid to be sealed F side, which is isolated by the rotary seal ring 21 and the stationary seal ring 11 that are in sliding contact with each other, to the other atmosphere A side.

[0019] The rotating element R mainly consists of a rotating case 20 fixed to the rotating shaft 2, a rotating sealing ring 21 positioned and held within the rotating case 20, and a cup gasket 22 positioned in a compressed state between the rotating case 20 and the rotating sealing ring 21.

[0020] The rotating side case 20 is an annular member with a roughly J-shaped cross-section that opens toward the right side, and is formed from a thin metal sheet by pressing and bending. The material and manufacturing method of the rotating side case 20 are not limited; for example, it may be made of a resin molded product.

[0021] The rotating case 20 comprises a cylindrical axial wall 20a extending in the axial direction, an annular radial wall 20b extending in the radial direction from the left end of the axial wall 20a, and a cylindrical axial wall 20c extending to the right along the rotation axis 2 from the inner end of the radial wall 20b. In this embodiment, the axial wall 20a and the radial wall 20b are at approximately a 90-degree angle.

[0022] The rotating sealing ring 21 has a rectangular cross-section, and its right side, i.e., the front surface of the rotating sealing ring 21, is a flat sliding surface 21a. Hereafter, the right side of the rotating sealing ring 21 may be referred to as the front side, and the left side as the back side.

[0023] The stationary element S mainly consists of a stationary case 10 attached to and fixed to the housing 3, an annular stationary sealing ring 11 provided on the stationary case 10 in a non-rotating state, facing the rotating sealing ring 21, rotatable relative to it, and movable in the axial direction, a bellows 12 as an elastic member that seals the space between the stationary case 10 and the stationary sealing ring 11, a spring 13 held by the stationary case 10 and acting as a biasing means that biases the stationary sealing ring 11 toward the rotating sealing ring 21, a band 60 as a fixing member that presses and fixes the bellows 12 to the stationary case 10 radially, or radially and axially, and an inner case 70 disposed inside the stationary case 10.

[0024] Here, the stationary case 10 and the stationary sealing ring 11 are key-fitted, allowing relative movement in the axial direction but restricting movement in the rotational direction. Note that other methods, such as the use of an engagement pin, may be used to restrict movement in the rotational direction.

[0025] The stationary case 10 is an annular member with a roughly U-shaped cross-section that opens to the left, and the inner case 70 is an annular member that opens to both the left and right sides, and is formed from a thin metal sheet by pressing and bending. The stationary case 10 and the inner case 70 are not limited in terms of material or processing method, and may be made of resin, for example.

[0026] The stationary case 10 mainly comprises a cylindrical axial wall 10a extending axially along the inner circumferential surface of the housing 3, an annular radial wall 10b extending inward from the front end of the axial wall 10a, and a cylindrical axial wall 10c extending to the left from the inner diameter end of the radial wall 10b.

[0027] The stationary sealing ring 11 comprises a base portion 11a and an annular projection 11b that protrudes axially from the inner diameter side and left side of the base portion 11a. The left side of the projection 11b, which is the surface facing the rotating sealing ring 21, is the sliding surface 11d.

[0028] As shown in Figures 2 and 3(a), the bellows 12 is an annular member made of an elastically deformable synthetic resin or rubber material, and has a pressing portion 51 that is spaced apart in the axial direction on the back side of the stationary sealing ring 11, a mounting portion 52 that is positioned on the outer diameter side of the stationary sealing ring 11, and a connecting portion 53 that connects the pressing portion 51 and the mounting portion 52.

[0029] Furthermore, the bellows 12 shown in Figure 3 is in its natural state (i.e., non-deformed state) before being assembled to the stationary case 10. The bellows 12 is a substantially cylindrical sealing member with openings at both axial ends.

[0030] The mounting portion 52 has an axially extending portion 52A and a radially extending portion 52B, and is formed in a substantially L-shape in cross-section. The mounting portion 52 has a mounting area 55 that abuts against the outer circumferential surface or back surface of the stationary sealing ring 11 when assembled. The mounting area 55 has a projection 55a that protrudes inward from the axially extending portion 52A, and an inner wall 55b of the radially extending portion 52B. The projection 55a is pressed against the outer circumferential surface 11c of the stationary sealing ring 11 from the outer diameter side.

[0031] The pressing portion 51 has an axial portion 56A and a radial portion 56B, and is formed in a substantially L-shape in cross-section. The axial portion 56A extends axially along the axial wall 10c of the stationary case 10, and the radial portion 56B extends radially from the right end of the axial portion 56A along the radial wall 10b of the stationary case 10. The pressing portion 51 is externally fitted to the axial wall 10c of the stationary case 10.

[0032] An annular inward projection 56c is formed on the inner circumference of the axial portion 56A, projecting inward from the inner end 53c of the left connecting portion 53 (see Figure 3). In the assembled state shown in Figure 2, it is in contact with the outer circumferential surface 10d of the axial wall 10c of the stationary case 10. The axial portion 56A is fixed to the axial wall 10c of the stationary case 10 by a band 60 acting as a fixing member. As a result, the axial portion 56A is pressed inward, causing the inward projection 56c of the axial portion 56A to elastically deform and be pressed against the outer circumferential surface 10d from the outer diameter side.

[0033] A tapered portion 156 is formed at the inner diameter corner between the axial portion 56A and the radial portion 56B, tapering toward the right in the axial direction. However, tapering is not mandatory. This tapered portion 156 consists of a first inclined surface 156a, which is a flat tapered surface extending to the right from the inward protrusion 56c of the axial portion 56A, and a second inclined surface 156b, which is a flat tapered surface extending from the right end of the first inclined surface 156a toward the contact surface 157, which will be described later.

[0034] Referring to Figure 3(b), the boundary between the second inclined surface 156b and the radially extending flat contact surface 157 in the radial portion 56B is called the boundary portion 158. This boundary portion 158 is located on the outer diameter side of the outer peripheral surface 56d of the axial portion 56A (see the dashed line).

[0035] Furthermore, as shown in Figure 4(a), the second inclined surface 156b extends to a position where it overlaps axially with the curved surface 62a formed on the right inner diameter corner 62 of the band 60 in the assembled state.

[0036] As shown in Figure 3(a), an annular rib 57 protruding in the radial direction is formed on the left side of the outer peripheral surface 56d of the axial portion 56A of the pressing portion 51. As a result, as shown in Figure 4(a), the movement of the band 60 in the axial direction to the left is restricted.

[0037] The connecting portion 53 is formed in a circular arc shape in cross-section, more specifically, by a radially extending portion and a quarter-circular arc portion connected to this portion. The outer diameter end connected to the mounting portion 52 is thinner than the radially extending portion 52B, and the inner diameter end connected to the pressing portion 51 is connected to the portion where the rib 57 of the axial portion 56A is formed. The connecting portion 53 is the main flexible portion of the bellows 12, and in the operating state of the mechanical seal 1, the mounting portion 52 can move axially relative to the pressing portion 51.

[0038] Next, I will explain Band 60.

[0039] As shown in Figure 4(b), the band 60 is formed in an annular shape from a metal material, for example, and has a first portion 61a extending along the axial portion 56A of the bellows 12, a second portion 61b extending from the right end of the first portion 61a along the radial portion 56B, and a third portion 61c formed so as to fold back on the outer diameter side from the left end of the first portion 61a, and is formed in a substantially L-shape in cross-section.

[0040] At the right inner diameter corner 62 between the first portion 61a and the second portion 61b, a roughly quadrant-shaped curved surface 62a is formed, which curves from the inner circumferential surface 63 of the first portion 61a to the right side surface 64 of the second portion 61b. This curved surface 62a is made to be almost identical in shape to the curved surface of the left outer diameter corner 159 between the axial portion 56A and the radial portion 56B of the bellows 12.

[0041] The assembly of the stationary element S will now be described. The band 60 and inner case 70 are attached to the bellows 12. In this state, the bellows 12 is moved axially and fitted onto the stationary case 10, while moving the band 60 axially until the contact surface 157 of the pressing portion 51 contacts the radial wall 10b. After that, the stationary sealing ring 11 is moved axially and attached between the stationary case 10 and the mounting portion 52 of the bellows 12. Note that the assembly procedure is not limited to this order.

[0042] Next, the operating conditions of the mechanical seal 1 will be explained based on Figures 4 to 6. Figure 4(a) shows the state in which no pressure is applied to the sealed fluid (hereinafter also referred to as the unpressurized state), and Figure 5 shows the state in which pressure is applied to the sealed fluid (hereinafter also referred to as the pressurized state).

[0043] As shown in Figure 4(a), the mounting portion 52 of the bellows 12 is attached by being sandwiched between the inner circumferential surface of the inner case 70 and the outer circumferential surface 11c of the stationary sealing ring 11. This seals the space between the mounting portion 52 and the stationary sealing ring 11.

[0044] On the other hand, the pressing portion 51 of the bellows 12 has its axial portion 56A strongly clamped between the inner circumferential surface 63 of the first portion 61a of the band 60 and the outer circumferential surface 10d of the axial wall 10c of the stationary case 10. The axial portion 56A is pressed inward by the band 60. As a result, the space between the axial portion 56A and the stationary case 10 is sealed.

[0045] Furthermore, the radial portion 56B of the bellows 12 is held by a weak clamping force between the right side surface 64 of the second portion 61b of the band 60 and the left side surface 10e of the radial wall 10b of the stationary case 10. Specifically, the contact surface 157 is pressed against and in contact with the left side surface 10e of the radial wall 10b of the stationary case 10. This seals the space between the radial portion 56B and the stationary case 10. The second portion 61b of the band 60 also functions as a so-called backup ring, restricting the deformation of the radial portion 56B of the bellows 12 toward the stationary sealing ring 11.

[0046] In this state, a gap S1 is formed between the corner between the radial wall 10b and the axial wall 10c of the stationary case 10 and the tapered portion 156 of the bellows 12.

[0047] As shown in Figure 5, under pressurized conditions, a force F1 due to the pressure of the sealed fluid F is applied to the connecting portion 53 of the bellows 12 in the leftward inward direction, and a force F2 due to the pressure of the sealed fluid F is applied to the mounting portion 52 in the rightward inward direction.

[0048] Thus, due to force F1, the connecting portion 53 receives a force to the left and deforms so as to bulge slightly to the left and inward. Due to force F2, the pressing portion 51 receives a force to the right and deforms so as to bulge slightly to the right and inward.

[0049] To illustrate schematically with reference to Figure 6, the boundary portion 158 is located on the outer diameter side of the inner circumferential surface 63 of the first portion 61a of the band 60, the portion where the second inclined surface 156b of the radial portion 56B is formed is thinner than the portion where the inward protrusion 56c is formed on the axial portion 56A, and the radial portion 56B and the axial portion 56A are bent at approximately 90 degrees. Therefore, under pressure, the boundary portion 158 becomes the starting point O, and the radial portion 56B is easily deformed.

[0050] Furthermore, the force Fr (=F1r+F2r) (F1r is not shown), which is the inner diameter component of forces F1 and F2, presses the axial portion 56A of the bellows 12 against the axial wall 10c of the stationary case 10, increasing the mounting force of the axial portion 56A to the axial wall 10c. The axial components of forces F1 and F2 result in a force Fa, which acts on the bellows 12 as a force directed axially to the left.

[0051] Here, since the axial components of forces F1 and F2 are directed in opposite directions, the axial force Fa (=F1a-F2a) (F1a is not shown) is small. Also, the pressing force of the axial portion 56A against the axial wall 10c is increased by the amount of force Fr. From these points, even under pressurized conditions, the axial position of the bellows 12, especially the axial portion 56A, remains unchanged, and the sealing performance of the inward protrusion 56c and the contact surface 157 can be maintained.

[0052] Thus, since the force F2 has a component directed to the right in the axial direction, the axial portion 56A is pulled to the left in the axial direction and becomes difficult to move. Therefore, the contact surface 157 becomes difficult to separate from the radial wall 10b of the stationary case 10.

[0053] Furthermore, the radial portion 56B is subjected to a force directed toward the radial wall 10b by the sealed fluid, and the radial portion 56B and the axial portion 56A are bent and connected, and this bent portion is thin-walled and easily deformed by bending, so the contact surface 157 is less likely to separate from the radial wall 10b of the stationary case 10.

[0054] As described above, in the mechanical seal 1 as an embodiment of the present invention, the stationary case 10 has an axial wall 10c that extends axially along the circumferential surface of the stationary sealing ring 11, and a radial wall 10b that extends radially along the right side surface of the stationary sealing ring 11.

[0055] Furthermore, the bellows 12 has a mounting portion 52 attached to the stationary sealing ring 11, an axial portion 56A extending along the axial wall 10c of the stationary case 10, and a radial portion 56B extending along the radial wall 10b of the stationary case 10, the axial portion 56A being pressed inward radially toward the stationary case 10 by the band 60.

[0056] Furthermore, the radial portion 56B of the bellows 12 has a contact surface 157 that abuts against the radial wall 10b of the stationary case 10, and the contact surface 157 is located radially towards the band 60, that is, towards the outer diameter, compared to the axial wall 10c of the stationary case 10.

[0057] In other words, the mechanical seal 1 comprises a housing 3 surrounding the rotating shaft of a rotating machine, a stationary case 10 having a radially extending radial wall 10b and attached to the housing 3, a stationary sealing ring 11 held by the stationary case 10 via a spring 13, a rotating sealing ring 21 facing the stationary sealing ring 11 and attached to the rotating shaft 2, a bellows 12 sealing the space between the stationary sealing ring 11 and the stationary case 11, and a band 60 pressing the bellows 12 radially toward the stationary case 11. The bellows 12 has a contact surface 157 (corresponding to the contact portion of the present invention) that abuts against the radial wall 10b, and in the radial direction, the position furthest from the sealed fluid side (i.e., the inner diameter side) where the band 60 and the bellows 12 make contact (i.e., the position of the outer peripheral surface 56d) is located further from the sealed fluid side (i.e., the inner diameter side) than the position furthest from the sealed fluid side of the contact surface 157 (i.e., the position of the boundary portion 158).

[0058] According to this, the contact surface 157 of the radial portion 56B of the bellows 12 is located on the radial band 60 side of the radial wall 10b of the stationary case 10, that is, on the outer diameter side of the outer circumferential surface 56d of the axial portion 56A. As a result, when the pressure of the sealed fluid acts on it, a force acts on the contact surface 157 of the bellows 12 toward the radial wall 10b, thus maintaining the airtight seal between the bellows 12 and the stationary case 10.

[0059] Furthermore, since the second portion 61b of the band 60 is positioned on the side of the radial portion 56B where the sealed fluid F is located, that is, on the left side opposite to the contact surface 157, the second portion 61b of the band 60 comes into contact with the radial portion 56B, thereby restricting deformation of the radial portion 56B away from the radial wall 10b of the stationary case 10.

[0060] Furthermore, the band 60 has a first portion 61a extending along the axial portion 56A and a second portion 61b extending along the radial portion 56B, so that it can not only press the axial portion 56A of the bellows 12 against the axial wall 10c of the stationary case 10, but also press the radial portion 56B against the radial wall 10b.

[0061] Furthermore, a curved surface 62a is formed on the inner diameter side of the corner 62 between the first portion 61a and the second portion 61b, which allows the band 60 to come into smooth contact with the bellows 12.

[0062] Furthermore, the bellows 12 has a tapered section 156 formed from the inward convex ridge 56c of the axial section 56A that is pressed radially to the contact surface 157, which allows a uniform stress to be applied to the bent section of the bellows 12 from the axial section 56A to the radial section 56B.

[0063] Furthermore, since the starting point of the tapered portion 156 is on the opposite side from the band 60, the contact surface 157 can be positioned on the outer diameter side of the axial wall 10c of the stationary case 10 with a simple structure.

[0064] Furthermore, since the tapered portion 156 consists of multiple tapered surfaces (a first inclined surface 156a and a second inclined surface 156b), the gap S1 between the stationary case 10 and the bellows 12 is reduced, while the bellows 12 can efficiently undergo elastic deformation within the gap S1.

[0065] Furthermore, the bellows 12 has ribs 57 formed as protrusions that restrict the axial movement of the band 60, thereby restricting the axial movement of the band 60 and allowing the radial portion 56B of the bellows 12 to stably contact the radial wall 10b of the stationary case 10, thus ensuring airtightness.

[0066] Although embodiments of the present invention have been described above with reference to the drawings, the specific configurations are not limited to these embodiments, and any changes or additions that do not depart from the spirit of the present invention are also included.

[0067] For example, in the above embodiment, the inward protrusion 56c of the axial portion 56A is shown to be formed in a flat shape, but it may also be formed in a curved cross-sectional shape, as shown in Figure 7.

[0068] Although an example was given in which the bellows 12 is assembled to the stationary case 10, the bellows 12 may also be assembled to the rotating case 20.

[0069] Furthermore, in the above embodiment, the contact surface 157 of the bellows 12 is shown to be located on the outer diameter side of the outer circumferential surface 56d of the axial portion 56A, but the contact surface 157 may also be located on the outer diameter side of the inner circumferential surface 63 of the first portion 61a of the band 60.

[0070] Furthermore, although the above embodiment described an inside-type mechanical seal as an example, it is not limited to this, and an outside-type mechanical seal may also be used. In this case, the sealing ring is installed on the outer diameter side of the bellows 12, and the contact portion is located on the radial pressing member side of the axial wall of the case, that is, it is located on the inner diameter side of the inner circumferential surface of the axial portion.

[0071] Furthermore, although the above embodiment illustrates a configuration in which the tapered portion 156 is composed of two first inclined surfaces 156a and a second inclined surface 156b, it may also be composed of only the second inclined surface 156b, or of three or more inclined surfaces.

[0072] Furthermore, although the tapered portion 156 is shown as having a flat surface in the above embodiment, it may also have a stepped shape, or it may be formed in a curved cross-section, as shown in Figure 8, for example, for the tapered portion 156c.

[0073] Furthermore, in the above embodiment, an example was given in which a band 60 composed of a first portion 61a, a second portion 61b, and a third portion 61c was applied as a fixing member. However, as long as there is a portion that can press the axial portion 56A in the radial direction, it is not necessary to have the second portion 61b and the third portion 61c.

[0074] Furthermore, the sealed fluid F may be a gas, a liquid, or a mixture of gas and liquid. Also, the leaking fluid is not limited to the atmosphere A, but may be a gas, a liquid, or a mixture of gas and liquid.

[0075] Furthermore, while the above embodiment illustrates a configuration in which a spring is used as an example of a biasing means, the type of spring can be changed in various ways, for example, a compression coil spring or a leaf spring may be used. Also, instead of an annular spring inserted around the outer circumference of the rotating shaft 2, multiple springs may be arranged in the circumferential direction of the rotating shaft 2. [Explanation of symbols]

[0076] 1 Mechanical seal 2 rotation axes 3 Housing 10. Stationary side case (case) 10a axial wall 10b Radial wall (radial wall) 10c Axial wall (Axial wall) 10d Outer surface 10e Left side 11 Stationary sealing ring (sealing ring) 11d Sliding surface 12. Bellows (elastic member) 13. Spring (biasing means) 20 Rotating side case 21. Rotating sealing ring (sealing ring) 21a Sliding surface 51 Pressing part 52 Mounting part 52A Axial extension 52B Radial extension 53 Connecting part 55 Mounting location 56A Axial part 56B Radial location 56c Inner protrusion 56d Outer surface 57 Rib (protruding part) 60 Bands (fixing components) 61a Part 1 (Part 1) 61b 2nd part (2nd part) 61c 3rd part 62 corners 62a curved surface 70 inner cases 156 Tapered section (tapered shape) 156a First inclined surface (tapered surface) 156b Second inclined surface (tapered surface) 157 Contact surface (contact part) 158 Boundary part (contact part) A atmosphere F Sealed fluid O starting point R Rotational element S Stationary side element S1 Gap

Claims

1. A housing that surrounds the rotating shaft of a rotating machine, A case having radially extending radial walls and attached to the housing, One sealing ring is held in the case via a biasing means positioned radially different from the radial wall, The other sealing ring is attached to the rotating shaft and contacts the other sealing ring to seal the fluid to be sealed, An elastic member that seals the space between the one sealing ring and the case, A mechanical seal comprising a fixing member that presses the elastic member radially toward the case, At the clamped portion closest to the fluid being sealed, the elastic member is clamped between the circumferential surfaces of the case and the fixing member, thereby sealing the space between the elastic member and the case. The elastic member has a contact portion that contacts the radial wall, In the radial direction, the position on the side furthest from the sealed fluid where the fixing member and the elastic member come into contact is located on the side furthest from the sealed fluid than the position on the side furthest from the sealed fluid at the contact portion. A mechanical seal in which the case and the elastic member are spaced apart between the contact portion of the elastic member and the clamped portion.

2. The mechanical seal according to claim 1, wherein the fixing member is arranged on the side of the elastic member that is to be sealed.

3. The mechanical seal according to claim 2, wherein the fixing member has a first portion extending along the axial direction and a second portion extending along the radial direction.

4. The mechanical seal according to claim 3, wherein the elastic member side at the corner between the first portion and the second portion is formed in a curved shape.

5. The mechanical seal according to any one of claims 1 to 4, wherein the elastic member has a tapered shape formed from the radially pressed portion to the contact portion.

6. The mechanical seal according to claim 5, wherein the tapered shape comprises a first tapered surface extending radially from the radially pressed portion and a second tapered surface connected to the first tapered surface and extending axially toward the contact portion.

7. The mechanical seal according to claim 1, wherein the elastic member has a protrusion formed thereon that restricts the axial movement of the fixing member.

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