Mechanical seal

Abstract

To provide a mechanical seal capable of maintaining sealability of fluid to be sealed.SOLUTION: In a mechanical seal 1A, a spring 14 is arranged between a case 13 and a stationary sealing ring 12 that is in sliding contact with a rotating sealing ring 11 that rotates together with a rotational shaft 3 that is pivotally supported by a bearing 4, and an O-ring 15 that seals between the case 13 and the stationary sealing ring 12 is provided on a fluid to be sealed side F with respect to the spring 14.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a mechanical seal used for shaft seals of rotating machines.

Background Art

[0002] In various fields, seals are used to prevent leakage of fluids. As an example of such a seal, in the field of sealing a fluid to be sealed with low torque and without wear damage to the shaft, a mechanical seal is used. The mechanical seal prevents leakage of the fluid to be sealed by closely sliding the sliding surfaces of a rotating seal ring that rotates with the rotating shaft and a stationary seal ring.

[0003] For example, in the mechanical seal described in Patent Document 1, the stationary seal ring and the rotating seal ring are arranged such that their sliding surfaces face each other, and the stationary seal ring is pressed toward the rotating seal ring by the biasing force of a spring arranged on the back side of the stationary seal ring. Also, on the inner diameter side, which is the side where leakage occurs from the spring, an O-ring is arranged as a secondary seal for sealing between the stationary seal ring and the case.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the mechanical seal described in Patent Document 1 above, the O-ring is positioned on the inner diameter side of the stationary sealing ring, so that the force from the fluid to be sealed introduced to the back side of the stationary sealing ring is added to the biasing force of the spring, thereby maintaining a good tight seal between the stationary sealing ring and the rotating sealing ring. On the other hand, if the fluid to be sealed enters the back side of the stationary sealing ring, corrosion of the spring by the fluid to be sealed, contamination mixed in the fluid to be sealed, and jamming of the spring by foreign matter such as dust may occur, causing malfunctions in the biasing force of the spring and potentially making it impossible to maintain the sealing performance of the fluid to be sealed.

[0006] This invention was made in view of these problems, and aims to provide a mechanical seal that can maintain the sealing performance of the fluid to be sealed. [Means for solving the problem]

[0007] To solve the aforementioned problems, the mechanical seal of the present invention is: A mechanical seal comprising a rotating sealing ring that rotates with a rotating shaft supported on the device, a stationary sealing ring that slides against the rotating sealing ring, a case that is attached to the housing of the device, and a biasing member disposed between the stationary sealing ring and the case, wherein leakage of the sealed fluid from one sealed fluid space to the other leak space, which is separated by the rotating sealing ring and the stationary sealing ring, is suppressed. A secondary seal is provided on the side of the biasing member that is to be sealed, which seals the space between the stationary sealing ring and the case. According to this, by providing a secondary seal on the side of the biasing member that is being sealed to the fluid space, corrosion of the biasing member by the sealed fluid, contamination of the sealed fluid, and foreign matter such as dust can cause the biasing member to become jammed, which can lead to malfunctions in the biasing force of the biasing member, thus maintaining the sealing performance of the sealed fluid.

[0008] The secondary seal may be located on the outer diameter side of the stationary sealing ring. According to this, the rotating sealing ring that slides against the stationary sealing ring can be positioned near the rotating shaft, thereby reducing sliding torque.

[0009] The case may have a secondary seal housing recess that opens in the inner diameter direction. This prevents the secondary seal from moving axially in accordance with the axial movement of the stationary sealing ring.

[0010] The outer circumferential surface of the stationary sealing ring may be a circumferential surface that is flat in the axial direction. This method makes it possible to further reduce the effect of axial load on the stationary sealing ring due to the secondary seal.

[0011] The case may have a recess for accommodating a biasing member that opens in the axial direction. According to this, the biasing member can be guided to expand and contract in the axial direction, thereby enabling stable biasing of the stationary sealing ring.

[0012] The biasing member housing recess may be formed on the inside of the housing mounting portion that protrudes in the axial direction. According to this design, the case can be easily attached to the housing simply by fitting the housing mounting portion into the housing. Furthermore, since the portion of the case other than the recess for housing the biasing member is in contact with the fluid being sealed, the stationary sealing ring and biasing member can be effectively cooled.

[0013] The rotating sealing ring has a fixing member that fixes it to the rotating shaft, The fixing member may be positioned so that its outer circumferential surface faces the stationary sealing ring and the inner circumferential surface of the case. According to this, a narrow axial gap extends between the fixing member and the case, making it difficult for external fluids, contaminants, dust, and other foreign matter to enter the biasing member.

[0014] A mechanical seal includes a rotating seal ring that rotates together with a rotating shaft pivotally supported by a machine, a stationary seal ring that slidably contacts the rotating seal ring, and a biasing member disposed between the stationary seal ring and the housing of the machine, and suppresses leakage of a sealed fluid from one sealed fluid space separated by the rotating seal ring and the stationary seal ring to the other leakage space. A secondary seal for sealing between the stationary seal ring and the housing of the machine is provided on the side of the sealed fluid space from the biasing member. According to this, since the secondary seal is provided on the side of the sealed fluid space from the biasing member, corrosion of the biasing member by the sealed fluid, contamination mixed in the sealed fluid, and biting of foreign matters such as dust into the biasing member are prevented, and it is possible to prevent a problem from occurring in the biasing force of the biasing member, so that the sealing performance of the sealed fluid can be maintained.

Brief Description of the Drawings

[0015] [Figure 1] It is a cross-sectional view showing a rotating machine including the mechanical seal as Example 1 according to the present invention. [Figure 2] It is an enlarged cross-sectional view of the main part of FIG. 1. [Figure 3] It is a cross-sectional view showing a means for preventing rotation. [Figure 4] It is a cross-sectional view showing the mechanical seal as Example 2 according to the present invention. [Figure 5] It is a cross-sectional view showing the mechanical seal as Example 3 according to the present invention. [Figure 6] It is a cross-sectional view showing the mechanical seal as Example 4 according to the present invention. [Figure 7] It is a cross-sectional view showing the mechanical seal as Example 5 according to the present invention. [Figure 8] It is a cross-sectional view showing the mechanical seal as Modification 1 of the present invention. [Figure 9] It is a cross-sectional view showing the mechanical seal as Modification 2 of the present invention.

Modes for Carrying Out the Invention

[0016] A mode for implementing the mechanical seal according to the present invention will be described below based on examples.

Example

[0017] The mechanical seal as Example 1 will be described based on FIGS. 1 to 3. Hereinafter, looking at FIG. 1 from the front side, the left and right sides will be described as the left and right sides of the mechanical seal.

[0018] As shown in FIGS. 1 and 2, for example, the mechanical seal of this embodiment includes a sealed fluid side F (sealed fluid space) including the space S1 outside the rotating machine as a device, and the spaces S2, S3, S4, S5, S6 inside the rotating machine. It consists of two mechanical seals 1A and 1B that isolate the leakage side R (leakage space) including.

[0019] The mechanical seals 1A and 1B are of an inside type that seals the sealed liquid that tends to leak from the sealed fluid side F, which is the outer diameter side of the sliding surface, toward the leakage side R, which is the inner diameter side. The mechanical seals 1A and 1B are arranged symmetrically on the left and right sides in the axial direction, but since their configurations are substantially the same, hereinafter, the mechanical seal 1A will be described, and the description of the mechanical seal 1B will be omitted.

[0020] The rotating machine includes a housing 2, a rotating shaft 3 provided rotatably in the circumferential direction around an axis facing the left and right directions with respect to the housing 2, and a plurality of bearings 4 as bearing portions. The bearing 4 consists of an inner ring 4a fixed to the outer periphery of the rotating shaft 3, an outer ring 4b fixed to the housing 2, and rolling elements 4c.

[0021] The housing 2 is composed of a housing main body 2A and a cover 2B. A space S1 is formed on the left side, and coolant (that is, cutting oil) as a sealed fluid can enter from a gap 5 (see FIG. 2) formed between the space S1 and the rotating shaft 3. That is, the space S1 is a part of the sealed fluid side F.

[0022] As shown in Figure 2, the mechanical seal 1A comprises a rotating sealing ring 11, a stationary sealing ring 12 that slides against the rotating sealing ring 11, a case 13 that covers the outer diameter side of the stationary sealing ring 12, and a spring 14 and an O-ring 15 provided between the stationary sealing ring 12 and the case 13.

[0023] The rotating sealing ring 11 and the stationary sealing ring 12 are in close contact at their respective sliding surfaces 11a and 12a due to the axial biasing force of the spring 14. The rotating sealing ring 11 and the stationary sealing ring 12 are annular sliding members, with the rotating sealing ring 11 being made of a hard material called SiC and the stationary sealing ring 12 being made of bearing steel.

[0024] Furthermore, although the rotating sealing ring 11 and the stationary sealing ring 12 were composed of SiC and bearing steel, both the rotating sealing ring 11 and the stationary sealing ring 12 may be composed of either SiC or bearing steel. In addition, the material of the sliding member can be any material used as a sliding material for mechanical seals, other than those mentioned above, such as ceramics other than SiC, metal materials other than bearing steel, resin materials, composite materials, etc.

[0025] The rotating sealing ring 11 is fitted onto the rotating shaft 3 and is circumferentially rotatable with the rotating shaft 3. More specifically, a notch 3c is formed at the left end of the outer circumferential surface of the rotating shaft 3, opening to the outer diameter side and to the left in the axial direction, and the rotating sealing ring 11 is inserted into the notch 3c from the left end in the axial direction.

[0026] Furthermore, a nut 6 is screwed into the male threaded portion formed on the outer circumferential surface of the notch 3c. By tightening this nut 6, the rotating sealing ring 11 is sandwiched between the nut 6 and the vertical wall portion 3d extending outward from the right end of the notch 3c, thereby restricting the axial movement and relative rotation of the rotating sealing ring 11 with respect to the rotation axis 3.

[0027] Furthermore, an O-ring housing recess 7 is provided on the vertical wall portion 3d side of the notch portion 3c. The O-ring housing recess 7 is formed in the shape of a groove that opens towards the rotating sealing ring 11 side, or in other words, in the shape of a U where the bends form an angle, and an O-ring 8 made of, for example, an annular fluororubber material is housed inside.

[0028] The stationary sealing ring 12 is positioned to the right of the rotating sealing ring 11 such that its sliding surface 12a is in close contact with the sliding surface 11a of the rotating sealing ring 11. Meanwhile, a space S2 is formed between the stationary sealing ring 12 and the outer circumferential surface of the rotating shaft 3, and the stationary sealing ring 12 is attached to the housing 2 side via the case 13 so as not to rotate together with the rotating shaft 3.

[0029] The case 13 is formed in an annular shape from a metal material such as stainless steel. The case 13 has a housing mounting portion 20A and a projection portion 21A that protrudes outward from the housing mounting portion 20A. The inside of the housing mounting portion 20A is a spring housing recess 20 for housing the spring 14, and the inside of the projection portion 21A is an O-ring housing recess 21 for housing the O-ring 15.

[0030] The housing mounting portion 20A is composed of an inner cylinder portion 20a located on the rotating shaft 3 side, an annular and plate-shaped ring portion 20b extending outward from the right end of the inner cylinder portion 20a, and an outer cylinder portion 20c extending to the left from the outer end of the ring portion 20b.

[0031] The protruding portion 21A is composed of an annular and plate-shaped ring portion 21a extending outward from the left end of the outer cylinder portion 20c, an outer cylinder portion 21b extending to the left from the outer diameter end of the ring portion 21a, and an annular and plate-shaped ring portion 21c extending inward from the left end of the outer cylinder portion 21b.

[0032] The stationary sealing ring 12 is provided on the left side of the spring 14 in the axial direction and on the inner diameter side of the O-ring 15, so as to be axially movable relative to the case 13. The stationary sealing ring 12 is positioned on the outer diameter side of the case 13, separated by a predetermined space.

[0033] The spring housing recess 20 is a space partitioned by the housing mounting portion 20A, and is formed in the shape of a groove that opens towards the stationary sealing ring 12, or in other words, a U-shape where the bends form an angle.

[0034] The spring housing recess 20 is formed on the right side of the stationary sealing ring 12 in the case 13, that is, on the back side of the sliding surface 12a. In addition, a space S3 is formed between the inner cylinder portion 20a and the outer circumferential surface of the rotating shaft 3, so that the case 13 does not come into contact with the rotating shaft 3.

[0035] A spring 14 is housed in the spring housing recess 20, extending circumferentially. The spring 14 is, for example, a coiled wave spring and applies an axial biasing force to the stationary sealing ring 12 toward the rotating sealing ring 11. The spring 14 is also guided to expand and contract in the axial direction by an inner cylinder portion 20a and an outer cylinder portion 20c that extend in the axial direction.

[0036] The O-ring housing recess 21 is a space partitioned by the protrusion 21A, and is formed in the shape of a groove that opens in the inner diameter direction, or in other words, a U-shape where the bends form an angle. The O-ring housing recess 21 is formed on the outer diameter side and to the left of the spring housing recess 20 in the case 13, that is, on the outer diameter side of the stationary sealing ring 12.

[0037] The O-ring housing recess 21 houses, for example, an O-ring 15 made of an annular fluororubber material. The O-ring 15 is elastically deformable and functions as a secondary seal that seals the space between the stationary sealing ring 12 and the outer cylindrical portion 21b of the case 13. Furthermore, radially extending annular portions 21a and 21c are positioned on the left and right sides of the O-ring 15 so as to be able to contact them, thereby restricting the axial movement of the O-ring 15.

[0038] In case 13, the housing mounting portion 20A protrudes to the right in the axial direction and is fitted into the axial hole 2a formed in the housing 2 to secure it in a sealed manner. Specifically, the inner portion of the housing mounting portion 20A functions as a spring housing recess, and the outer portion of the housing mounting portion 20A functions as a mounting portion that can be fitted into the axial hole 2a of the housing 2.

[0039] On the other hand, the protrusion 21A in case 13 protrudes outward. Specifically, the O-ring receiving recess 21 inside the protrusion 21A functions as an O-ring receiving recess, and the outer portion of the protrusion 21A is located within the space S1 outside the housing 2.

[0040] Thus, in the case 13, one of the housing mounting portion 20A and the protruding portion 21A protrudes relative to the other. Therefore, when the housing mounting portion 20A is fitted into the axial hole 2a of the housing 2 and mounted, the protruding portion 21A of the case 13 is positioned on the side F of the sealed fluid relative to the housing mounting portion 20A.

[0041] The leakage side R, which is the space on the inner diameter side of the sliding surfaces 11a and 12a, includes spaces S2 and S3, space S4 between the housing 2 and the rotating shaft 3, space S5 inside the bearing 4, and space S6 inside the case 13. Space S6 inside the case 13 is not in communication with the sealed fluid side F on the outer diameter side of the stationary sealing ring 12 by the O-ring 15.

[0042] The O-ring 15 is positioned on the fluid-sealed side F from the spring 14 to seal the stationary sealing ring 12 and the case 13. As a result, even if the fluid to be sealed enters the case 13 through the space between the annular portion 21c of the case 13 and the stationary sealing ring 12, the O-ring 15 prevents it from entering the leak side R. Thus, the fluid-sealed side F and the leak side R are sealed by the sliding surfaces 11a and 12a and the O-ring 15 as a secondary seal. As mentioned above, the case 13 is sealed and mounted in the housing 2.

[0043] Furthermore, the radial length dimension L1 in the axial hole 2a of the housing 2 is approximately the same as the sum of the radial length dimension L2 at the sliding surfaces 11a and 12a and the length dimension L3 in the thickness direction of the case 13 (L1 ≈ L2 + L3). The length dimension L3 in the thickness direction of the case 13 is smaller than the diameter, which is the radial dimension of the O-ring 15.

[0044] In other words, by placing the O-ring 15 on the outer diameter side of the stationary sealing ring 12, the stationary sealing ring 12 and the spring 14 can be positioned near the rotating shaft 3, and the rotating sealing ring 11 can be positioned near the rotating shaft 3 in accordance with the stationary sealing ring 12. As a result, the sliding surfaces 11a and 12a are closer to the rotating shaft 3, and the sliding torque on the sliding surfaces 11a and 12a can be reduced. Furthermore, even if the radial length dimension L2 of the sliding surfaces 11a and 12a is longer than the radial length dimension L1 of the shaft hole 2a, the mechanical seal 1A can still be installed.

[0045] Furthermore, because the protruding portion 21A protrudes radially more than the housing mounting portion 20A, a stationary sealing ring 12 having a sliding surface 12a that is relatively longer than the radial length dimension L1 in the shaft hole 2a can be attached.

[0046] Furthermore, when the housing mounting portion 20A is fitted into the shaft hole 2a of the housing 2, the outer surface of the annular portion 21a abuts the bottom surface of the shaft hole 2a in the axial direction, determining its axial position. As a result, the shape of the protruding portion 21A is accurately maintained without the protruding portion 21A contacting the housing 2 and deforming, thus ensuring that the sealing performance of the O-ring 15 is favorably maintained.

[0047] As shown in Figure 3, the mechanical seal 1A includes an anti-rotation means 30 that restricts the circumferential rotation of the stationary sealing ring 12 relative to the case 13.

[0048] More specifically, on the inner circumferential surface of the stationary sealing ring 12, on the spring 14 side, there are multiple notches 31 that open to the inner diameter side and to the right in the axial direction, located at various points in the circumferential direction. On the other hand, the inner cylindrical portion 20a of the case 13 has multiple notches 32 that open to the left in the radial direction and to the left in the axial direction, with convex restricting portions 20d between each of the notches 32.

[0049] Each notch 31 formed in the stationary sealing ring 12 has a restricting portion 20d of the inner cylinder portion 20a positioned so as to overlap with the stationary sealing ring 12 in the circumferential direction. Therefore, when the stationary sealing ring 12 rotates in the circumferential direction, the rotation is restricted by the circumferential end of the notch 31 coming into contact with the circumferential end of the restricting portion 20d.

[0050] In other words, the anti-rotation means 30 is composed of the notch 31 of the stationary sealing ring 12 and the restricting portion 20d of the case 13. However, the anti-rotation means is not limited to the anti-rotation means 30 described above; for example, it may be composed of a hole provided in one of the stationary sealing ring 12 or the case 13, and a protruding member such as a pin provided in the other and insertable into the hole.

[0051] As described above, in the mechanical seals 1A and 1B of this embodiment 1, a spring 14 is positioned between the stationary sealing ring 12, which slides against the rotating sealing ring 11 that rotates together with the rotating shaft 3 supported by the bearing 4, and the case 13. An O-ring 15 is provided on the fluid-to-be-sealed side F from the spring 14 to seal the space between the case 13 and the stationary sealing ring 12.

[0052] As described above, the O-ring 15 is provided on the side F of the sealed fluid relative to the spring 14, preventing the sealed fluid from entering the space S6 inside the case 13 from the O-ring 15 towards the spring 14. Therefore, corrosion of the spring 14 and bearing 4 by the sealed fluid, contamination of the sealed fluid, and the inclusion of foreign matter such as dust can occur, preventing malfunctions in the biasing force of the spring 14 and the rotational operation of the bearing 4. As a result, the sealing performance of the sealed fluid can be maintained over a long period of time.

[0053] Furthermore, since the O-ring 15 is positioned on the outer diameter side of the stationary sealing ring 12, the rotating sealing ring 11 can be positioned near the rotation axis 3 together with the stationary sealing ring 12 and the spring 14. As a result, the sliding surfaces 11a and 12a are closer to the rotation axis 3, thereby reducing the sliding torque. In addition, the pressing force of the O-ring 15 acts radially on the stationary sealing ring 12, reducing the axial load influence of the O-ring 15 on the stationary sealing ring 12, and making the load influence of the spring 14 greater. Therefore, it becomes easier to set the load control for the stationary sealing ring 12.

[0054] Furthermore, the case 13 has an O-ring housing recess 21 that opens in the inner diameter direction, which prevents the O-ring 15 from moving axially in accordance with the axial movement of the stationary sealing ring 12.

[0055] Furthermore, since the outer circumferential surface 12s of the stationary sealing ring 12 is flat in the axial direction, the influence of the axial load on the stationary sealing ring 12 by the O-ring 15 can be further reduced.

[0056] Furthermore, since the case 13 has a spring housing recess 20 that opens in the axial direction, the spring 14 can be guided to expand and contract in the axial direction, thereby stably biasing the stationary sealing ring 12.

[0057] Furthermore, the case 13 can be easily attached to the housing 2 simply by fitting the housing mounting portion 20A into the shaft hole 2a of the housing 2.

[0058] Furthermore, the housing mounting portion 20A of the case 13, in which the spring housing recess 20 is formed on the inside, is fitted into the shaft hole 2a, while the protruding portion 21A, in which the O-ring housing recess 21 is formed on the inside, is positioned on the side F of the fluid to be sealed.

[0059] Therefore, even with a structure that prevents the sealed fluid from entering the leakage side R beyond the O-ring 15 in the space S6 inside the case 13, the protruding portion 21A of the case 13 is shaped to enter the space S1 and come into contact with the coolant over a wide area, thereby allowing the stationary sealing ring 12 and spring 14 to be suitably cooled via the case 13.

[0060] Furthermore, since the sealed fluid does not enter the leakage side R from the O-ring 15 in the space S6 inside the case 13, there is no axial load influence on the stationary sealing ring 12 due to the sealed fluid. Therefore, since the load of the spring 14 is dominant, it becomes easy to set the load control on the stationary sealing ring 12. [Examples]

[0061] Next, a mechanical seal as Embodiment 2 of the present invention will be described with reference to Figure 4. Note that descriptions of components that are identical to those in Embodiment 1 and therefore redundant will be omitted.

[0062] As shown in Figure 4, in this embodiment 2 of the rotating machine, the rotating shaft 3 does not have a notch 3c formed on the left end of its outer circumferential surface, and the rotating sealing ring 11 of the mechanical seal 101A is fixed to the outer circumferential surface of the rotating shaft 3 by fitting.

[0063] Furthermore, the case 60 in this embodiment 2 is composed of a case body 61 and a case cover 62. The case body 61 and the case cover 62 are formed in an annular shape from a metal material such as stainless steel.

[0064] More specifically, the case body 61 lacks a wall portion corresponding to the annular portion 21c of the case 13 in Embodiment 1, and the axial left side of the O-ring housing recess 21 is open, with this open portion covered by the case cover 62.

[0065] The case cover 62 consists of an annular portion 62a extending outward in the left direction on the left side of the O-ring housing recess 21, and an outer cylindrical portion 62b extending axially to the right from the outer diameter end of the annular portion 62a.

[0066] By fitting the case cover 62 onto the case body 61 from the side of the rotating sealing ring 11, the outer cylinder portion 62b is positioned on the outer diameter side of the outer cylinder portion 21b of the case body 61, and the annular portion 62a is positioned to cover the axial left opening of the O-ring housing recess 21.

[0067] Furthermore, a notch 12b is formed at the left end of the outer peripheral surface 12s of the stationary sealing ring 12, opening to the outer diameter side and to the left in the axial direction, and the inner diameter side end of the annular portion 62a is close to the outer peripheral surface of the notch 12b. Therefore, the vertical wall portion 12c extending from the right side of the notch 12b toward the outer diameter side abuts against the annular portion 62a, thereby restricting the movement of the stationary sealing ring 12 toward the rotating sealing ring 11, and preventing the stationary sealing ring 12 from disengaging from the case 60.

[0068] Thus, as in the mechanical seal 101A of this embodiment 2, the case 60 may consist of a case body 61 and a case cover 62 that can be fitted to the outer diameter side of the case body 61. With this, the stationary sealing ring 12, spring 14, O-ring 15 and case 60 that constitute the stationary sealing element of the mechanical seal 101A can be unitized, resulting in excellent transport and assembly workability for the mechanical seal 101A. [Examples]

[0069] Next, a mechanical seal as Embodiment 3 of the present invention will be described with reference to Figure 5. Note that descriptions of configurations that are identical to those of Embodiments 1 and 2 will be omitted.

[0070] As shown in Figure 5, in this embodiment 3 of the rotating machine, the rotating shaft 3 does not have a notch 3c formed on the left end side of its outer circumferential surface, and the rotating sealing ring 11 of the mechanical seal 111A is fixed to the outer circumferential surface of the rotating shaft 3 by fitting.

[0071] Furthermore, the case 70 in this embodiment 3 is composed of a case body 71 and a case cover 72. The case body 71 and the case cover 72 are formed in an annular shape from a metal material such as stainless steel.

[0072] The case cover 72 is positioned on the inner diameter side of the stationary sealing ring 12 and consists of an annular portion 72a extending in the inner diameter direction and an inner cylindrical portion 72b extending axially to the right from the inner diameter end of the annular portion 72a. A notch 12d is formed at the left end of the inner circumferential surface of the stationary sealing ring 12, opening to the inner diameter side and to the left in the axial direction, and the outer diameter end of the annular portion 72a is close to the inner circumferential surface of the notch 12d.

[0073] By fitting the case cover 72 onto the case body 71 from the side of the rotating sealing ring 11, the inner cylinder portion 72b is positioned on the inner diameter side of the stationary sealing ring 12, and the annular portion 72a is positioned opposite the vertical wall portion 12e that extends from the right side of the notch portion 12d toward the inner diameter. Therefore, the vertical wall portion 12e of the notch portion 12d abuts against the annular portion 72a, restricting the movement of the stationary sealing ring 12 toward the rotating sealing ring 11, thereby preventing the stationary sealing ring 12 from dislodging from the case 70.

[0074] Thus, as in the mechanical seal 111A of this embodiment 3, the case 70 may consist of a case body 71 and a case cover 72 that can be fitted to the inner diameter side of the case body 71. With this, the stationary sealing ring 12, spring 14, O-ring 15 and case 70 that constitute the stationary sealing element of the mechanical seal 111A can be unitized, resulting in excellent transport and assembly workability for the mechanical seal 111A.

[0075] Furthermore, replacement work due to deterioration of the static sealing ring 12 can be easily carried out. In addition, by fitting the case cover 72 onto the case body 71 during transportation, the detachment of the static sealing ring 12 can be prevented. [Examples]

[0076] Next, a mechanical seal as Embodiment 4 of the present invention will be described based on Figure 6. Note that descriptions of configurations that are identical to those of Embodiments 1 to 3 and therefore overlap will be omitted.

[0077] In the above embodiment 1, the mechanical seals 1A and 1B arranged symmetrically on the left and right sides in the axial direction of the rotating machine were exemplified in which the rotating sealing ring 11 is positioned axially towards the end of the stationary sealing ring 12 and the spring 14 is positioned axially towards the center of the stationary sealing ring 12. However, the present invention is not limited to this.

[0078] For example, a mechanical seal may be configured such as the mechanical seal 151A shown in Figure 6 as Embodiment 4, in which the rotating sealing ring 11 is positioned axially towards the center of the stationary sealing ring 12, and the spring 14 is positioned axially towards the end of the stationary sealing ring 12.

[0079] Although not specifically shown in the figures, the mechanical seals 151A are arranged symmetrically on the left and right sides in the axial direction of the rotating machine, similar to the examples in 1 to 3 above, and the spaces S4 and S5 between the left and right mechanical seals contain the fluid to be sealed, which is lubricating oil.

[0080] In other words, the mechanical seal 151A separates the sealed fluid side F, which includes the space S4 between the housing 2 and the rotating shaft 3 and the space S5 inside the bearing 4, from the leak side R, which includes spaces S10 and S11 that communicate with the outside of the rotating machine. The housing 2 consists of the housing body 2C and the cover 2D.

[0081] Furthermore, the rotating sealing ring 11 is fixed to the rotating shaft 3 by a fixing member 155. More specifically, it is fixed to the rotating shaft 3 by being sandwiched axially between the vertical wall portion 3d extending outward from the outer surface of the rotating shaft 3 and the fixing member 155. Note that the fixing method is not limited to press-fitting the fixing member 155 onto the rotating shaft 3, but may also be welding or screwing.

[0082] Furthermore, the stationary sealing ring 12 and the case 13 are positioned on the outer diameter side of the fixing member 155. The case 13 is press-fitted and fixed into a recess 2r formed in the cover 2D. Specifically, the housing mounting portion 20A of the case 13 protrudes to the left in the axial direction and is attached in a sealed manner to the recess 2r formed in the cover 2D. The inner portion of the housing mounting portion 20A functions as a spring-retaining recess, and the outer portion of the housing mounting portion 20A functions as a mounting portion that can be attached to the recess 2r of the cover 2B.

[0083] Space S10 is the space formed between the fixing member 155 and the stationary sealing ring 12, and space S11 is the space formed between the fixing member 155 and the case 13.

[0084] Although external fluid can enter the leak-side spaces S10 and S11 through the gap 5, the O-ring 15 and sliding surfaces 11a and 12a prevent the external fluid from entering the sealed fluid side F.

[0085] Thus, in the mechanical seal 151A as Example 4, the O-ring 15 is provided on the side F of the sealed fluid relative to the spring 14, preventing the sealed fluid from entering the space inside the case 13 from the O-ring 15 towards the spring 14. Therefore, corrosion of the spring 14 and bearing 4 by the sealed fluid, contamination, and the intrusion of foreign matter such as dust can be prevented, which can cause malfunctions in the biasing force of the spring 14.

[0086] Furthermore, since the fixing member 155 is positioned opposite the inner circumferential surfaces of the stationary sealing ring 12 and the case 13, a narrow space S11 extends axially between the fixing member 155 and the inner circumferential surface of the case 13, making it difficult for external fluids, contaminants, dust, and other foreign matter to enter the spring 14. Also, since a narrow space S10 extends axially between the fixing member 155 and the inner circumferential surface of the stationary sealing ring 12, it is difficult for external fluids, contaminants, dust, and other foreign matter to enter the sliding surfaces 11a and 12a. [Examples]

[0087] Next, a mechanical seal as Embodiment 5 of the present invention will be described with reference to Figure 7. Note that descriptions of configurations that are identical to those of Embodiments 1 to 4 and therefore overlap will be omitted.

[0088] Furthermore, while embodiments 1 to 4 illustrate configurations in which the spring 14 and O-ring 15 are provided between the stationary sealing ring 12 and the case 13, the spring 14 and O-ring 15 may be provided between the stationary sealing ring 12 and the housing 2 without going through the case 13, for example, as shown in the mechanical seal 141A of embodiment 5 in Figure 7.

[0089] Furthermore, the housing 2 consists of a housing body 2E and a cover 2F. The housing body 2E has a projection 2G with a roughly L-shaped cross-section that extends toward the axial end, and an O-ring receiving recess 21 is formed on the inner diameter side of the projection 2G that opens toward the other axial end.

[0090] Thus, in the mechanical seal 141A as Example 5, the O-ring 15 is provided on the side F of the sealed fluid relative to the spring 14. As a result, the sealed fluid cannot enter the internal space formed by the protrusion 2G and shaft hole 2a of the housing 2 from the O-ring 15 towards the spring 14. Therefore, corrosion of the spring 14 and bearing 4 by the sealed fluid, contamination, and the intrusion of foreign matter such as dust can be prevented, which can cause malfunctions in the biasing force of the spring 14.

[0091] Furthermore, the protruding portion 2G may be formed on the cover 2F. Also, although not shown in the figures, either the spring 14 or the O-ring 15 may be provided between the case 13 and the cover, and the other between the cover and the housing 2.

[0092] 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 gist of the present invention are also included. In the following modifications, descriptions of configurations that are identical to those in Embodiments 1 to 5 and therefore overlap will be omitted.

[0093] For example, in the above embodiments 1 to 5, the O-ring 15 is positioned on the outermost diameter side of the stationary sealing ring 12, that is, on the outer surface of the largest diameter portion on the outer surface 12s of the stationary sealing ring 12. However, the present invention is not limited to this, and the O-ring 15 does not have to be positioned on the outermost diameter side of the stationary sealing ring 12, as shown in the mechanical seal 121A, which is a modified example 1 in Figure 8.

[0094] Specifically, a notch 12f is formed on the right side of the outer peripheral surface 12s of the stationary sealing ring 12, opening to the outer diameter side and to the right in the axial direction, and the O-ring 15 is positioned on the portion of the outer peripheral surface 12s of the stationary sealing ring 12 that corresponds to the notch 12f. In other words, the O-ring 15 may be positioned on the outer peripheral surface of the notch 12f that is formed on the inner diameter side of the outer peripheral surface that does not correspond to the notch 12f.

[0095] Furthermore, while embodiments 1 to 4 illustrate an O-ring receiving recess 21 being formed in the case 13 and embodiment 5 in the housing 2, the present invention is not limited thereto. As shown in the mechanical seal 131A, which is a modified example 2 in Figure 9, the O-ring receiving recess 21 may be formed in the stationary sealing ring 12. For example, a groove 12g formed circumferentially on the outer peripheral surface 12s of the stationary sealing ring 12 may function as the O-ring receiving recess.

[0096] Furthermore, in the above embodiments 1 to 5, the spring 14 was positioned on the inner diameter side of the O-ring 15, but as long as it is positioned on the leakage side R of the O-ring 15, it may be positioned at approximately the same radial position as the O-ring 15, as in the mechanical seal 131A, which is modified example 2 shown in Figure 9. Also, although not specifically shown, the spring 14 may be positioned on the outer diameter side of the O-ring 15.

[0097] Furthermore, in the above-described embodiments 1 to 5 and modifications 1 and 2, the mechanical seals 1A, 1B, 101A, 111A, 121A, 131A, 141A, and 151A are exemplified as a static type in which the spring 14 biases the stationary sealing ring 12 toward the rotating sealing ring 11. However, the present invention is not limited thereto, and may also be a rotary type in which the rotating sealing ring 11 biases toward the stationary sealing ring 12.

[0098] Furthermore, although an example of applying the present invention to an inside-type mechanical seal where the leakage direction of the sealed fluid is from the outer diameter side to the inner diameter side on the sliding surfaces 11a and 12a has been illustrated, the present invention can also be applied to an outside-type mechanical seal. In the case of an outside-type seal, the secondary seal may be located on the inner diameter side of the stationary sealing ring 12.

[0099] Furthermore, while embodiments 1 to 4 and modifications 1 and 2 illustrate a configuration in which the spring housing recess 20 and the O-ring housing recess 21 are formed in the case 13, the present invention is not limited thereto. As long as the spring 14 and the O-ring 15 are provided between the stationary sealing ring 12 and the case 13, the spring housing recess 20 and the O-ring housing recess 21 do not necessarily have to be formed.

[0100] Furthermore, while the above-described embodiments 1 to 4 and modifications 1 and 2 illustrate a configuration in which the plate thickness dimensions of each part of case 13, 60, and 70 are substantially the same, the present invention is not limited thereto, and at least a part may be formed in a block shape rather than a plate shape.

[0101] Furthermore, while the first embodiment described an example in which two mechanical seals 1A and 1B are provided between the fluid side F to be sealed and the leak side R, the present invention is not limited to this, and three or more mechanical seals may be provided, or even just one mechanical seal may be provided.

[0102] Furthermore, while embodiments 1 to 5 and modifications 1 and 2 illustrate an example of a secondary seal using an O-ring 15, the present invention is not limited thereto, and other contact-type sealing members with different cross-sectional shapes from the O-ring 15 may be used.

[0103] Furthermore, while embodiments 1 to 5 and modifications 1 and 2 illustrate a configuration in which the rotating sealing ring 11 is directly fixed to the rotating shaft 3, the present invention is not limited thereto, and the rotating sealing ring 11 may be indirectly fixed to the rotating shaft 3 via a sleeve or the like.

[0104] Furthermore, while embodiments 1 to 5 and modifications 1 and 2 illustrate an example of a biasing member in which an annular coiled wave spring inserted around the outer circumference of the rotating shaft 3 is used, the present invention is not limited to this, and other springs such as compression coil springs or leaf springs may be used. Also, instead of an annular spring inserted around the outer circumference of the rotating shaft 3, multiple springs may be arranged in the circumferential direction of the rotating shaft 3. [Explanation of Symbols]

[0105] 1A, 1B Mechanical Seal 2 Housing 2a shaft hole 3 rotation axes 4 bearings 11 Rotating sealing ring 11a,12a Sliding surface 12 Stationary sealing ring 12s outer surface 13 cases 14. Spring (biasing member) 15 O-ring (secondary seal) 20 Spring housing recess 20A Housing mounting section 20a Inner cylinder section (housing mounting section) 21A Circular section (housing mounting section) 20c Outer cylinder section (housing mounting section) 21 O-ring housing recess (secondary seal housing recess) 21B Protrusion 21a Annular section 21b Outer cylinder 21c Circular section 30 Anti-rotation mechanism 60, 70 cases 61,71 Case body 62,72 Case Cover 101A, 111A Mechanical Seals 121A, 131A Mechanical Seal 151A Mechanical Seal 155 Fixing member F Sealed fluid side (sealed fluid space side) R Leak side (leak space side)

Claims

1. A mechanical seal comprising a rotating sealing ring that rotates with a rotating shaft supported on the device, a stationary sealing ring that slides against the rotating sealing ring, a case that is attached to the housing of the device, and a biasing member disposed between the stationary sealing ring and the case, wherein leakage of the sealed fluid from one sealed fluid space to the other leak space, which is separated by the rotating sealing ring and the stationary sealing ring, is suppressed. A secondary seal is provided on the side of the biasing member toward the sealed fluid space, sealing the space between the stationary sealing ring and the case, and the space in which the biasing member is located is sealed from the sealed fluid space by the secondary seal and is in communication with the leak space. The case is a mechanical seal having a housing mounting portion that is attached to the housing of the equipment and houses the biasing member, and a secondary seal housing portion that is connected to the housing mounting portion, is located in the sealed fluid space, protrudes radially from the housing mounting portion and houses the secondary seal.

2. The mechanical seal according to claim 1, wherein the secondary seal is located on the outer diameter side of the stationary sealing ring.

3. The mechanical seal according to claim 2, wherein the secondary seal housing portion has a secondary seal housing recess that opens in the inward direction.

4. The mechanical seal according to claim 3, wherein the outer circumferential surface of the stationary sealing ring is a circumferential surface that is flat in the axial direction.

5. The mechanical seal according to any one of claims 1 to 4, wherein the housing mounting portion has a biasing member housing recess that opens in the axial direction.

6. The mechanical seal according to claim 5, wherein the biasing member housing recess is formed on the inside of the housing mounting portion that protrudes in the axial direction.

7. The rotating sealing ring has a fixing member that fixes it to the rotating shaft, The mechanical seal according to claim 1, wherein the fixing member is positioned such that its outer circumferential surface faces the stationary sealing ring and the inner circumferential surface of the case.

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