JP4283265B2 - Mechanical seal for slurry fluid - Google Patents

Description

  The present invention relates to various slurry fluids (eg, powder, chemical solution, sludge water, CMP (Chemical Mechanical Polishing) polishing fluid, dust gas, liquid food, etc.) that are liquids or gases containing slurry components such as solid components and coagulation components. In particular, it is related to a mechanical seal for slurry fluids used in rotating equipment such as pumps, and more specifically, can be moved in the axial direction through one of the rotating shaft and the seal case via a secondary seal O-ring. The present invention relates to a mechanical seal for slurry fluid configured so as to shield and seal a slurry fluid region and a non-slurry fluid region at a relative rotation portion between a held movable seal ring and a fixed seal ring fixed to the other side.

  As a mechanical seal for this type of slurry fluid, a movable sealing ring is held in a seal case so as to be movable in the axial direction, and the movable sealing ring is attached to a rotating shaft by a spring interposed between the movable sealing ring and a spring retainer. The sealing fluid seal and the atmospheric region, which is a non-slurry fluid region (external region), are shielded and sealed by pressing against the fixed stationary sealing ring and the relative rotational sliding contact of the sealing end surfaces that are the opposite end surfaces of both sealing rings. An end face contact type configured to do this is well known.

  By the way, in such a mechanical seal, a secondary seal O-ring is loaded between the opposed peripheral surfaces of the seal case and the movable sealing ring held by the seal case, and the opposed peripheral surfaces are relatively aligned in the axial direction. Secondary sealing is performed in a state in which displacement (movement of the movable seal ring in the axial direction) is allowed.

  However, this secondary seal O-ring loading space (the space formed between the opposed peripheral surfaces of the seal case and the movable sealing ring, hereinafter referred to as the “O-ring loading space”) is the slurry fluid region. Because of the opening, the slurry fluid enters from the opening, and in the long-term use, the slurry component (for example, slurry fluid such as powder, chemical solution, sludge water, CMP polishing solution, dust gas) There is a possibility that solid components and solidified components) are deposited and fixed.

  Thus, when the slurry component is deposited and fixed in the space, the relative movement (axial movement) of the movable sealing ring with respect to the seal case via the O-ring is hindered, and the movable sealing ring moves smoothly in the axial direction. This is not performed (operation failure), the followability of the movable sealing ring is lowered, the contact surface pressure of the sealing end face becomes inappropriate, and the mechanical seal function is lowered.

  Therefore, conventionally, the O-ring has a cross-sectional shape corresponding to the O-ring loading space so that the O-ring is closely packed in the O-ring loading space including the opening on the slurry fluid region side. It has been proposed to devise so as to prevent the slurry fluid from entering the space (see, for example, FIG. 1 of Patent Document 1).

  However, since such an O-ring has a very special shape, it is extremely expensive compared to a commercially available O-ring (a cross-section is circular, close to this, or a polygonal shape). Yes, it is a problem in the production economy of mechanical seals. However, since the O-ring is only an auxiliary member for secondary sealing between the seal case and the movable sealing ring, and is not a main member directly connected to the mechanical seal function, such an O-ring is an auxiliary member. However, it is of course not preferable from the viewpoint of manufacturing economy of the mechanical seal.

  Furthermore, when such an O-ring with a special shape is used, the relative movement between the O-ring and the movable sealing ring prevents the slurry component from completely entering, solidifying and accumulating during this period. It was impossible and did not solve the above problems. Moreover, the smooth and good followability of the movable sealing ring is generally ensured by rolling the O-ring loaded between the sealing ring and the seal case in the O-ring loading space. As described above, when a specially shaped O-ring closely packed in the O-ring loading space is used, it does not roll unlike a case where a commercially available O-ring is used. Therefore, when the contact pressure between the O-ring and the movable sealing ring is high, the frictional force increases, and the followability of the sealing ring is impaired. If the contact pressure is lowered (compression margin is reduced) in order to ensure followability, the secondary seal function becomes insufficient, and in any case, a good mechanical seal function is not exhibited.

  In addition, it has also been proposed to prevent (clean) the slurry fluid from depositing in the O-ring loading space by injecting a clean cleaning liquid into the O-ring loading space (see, for example, Patent Document 2). Requires an apparatus for injecting a cleaning liquid, and the mechanical seal structure becomes complicated and large, and there is a problem in terms of running cost.

Therefore, the present inventor first performs secondary sealing between the opposed peripheral surfaces of the seal case and the movable sealing ring with a commercially available O-ring (hereinafter referred to as “secondary sealing O-ring”), and loading the O-ring. An O-ring made of soft rubber such as silicon rubber having a shore hardness of 3 to 30 ° (a shore hardness of a commercially available O-ring is 70 to 90 °) is provided at the opening on the slurry fluid side in the space. Proposed to be loaded as. In this way, if the O-ring for preventing slurry fluid intrusion made of soft rubber is loaded in the opening on the slurry fluid region side in the O-ring loading space, it is possible to enter the O-ring loading space without requiring a cleaning liquid injection device. It is possible to reliably prevent the slurry fluid from entering. In addition, since the O-ring made of soft rubber is a highly deformable O-ring, the O-ring for preventing slurry fluid intrusion moves in the axial direction of the movable sealing ring and the movement (rolling, etc.) of the secondary sealing O-ring. There is no hindrance.
Japanese Patent Laid-Open No. 2003-14136 (FIG. 1) Japanese Utility Model Publication No. 64-57461

  However, such a soft slurry fluid intrusion prevention O-ring is more expensive than a commercially available O-ring, like the special-shaped secondary seal O-ring described above. There is an economic problem. In addition, the O-ring for preventing slurry fluid intrusion made of soft rubber cannot be applied depending on the properties of the slurry fluid due to its material, and its use resistance and usage conditions are greatly limited. For example, since soft rubber does not have excellent corrosion resistance, a soft rubber O-ring cannot be used when the slurry fluid is corrosive.

  The present invention has been made in view of the above points, and without using an O-ring having a special shape or material, and without using an apparatus for injecting a cleaning liquid. It is an object of the present invention to provide a mechanical seal for slurry fluid that can effectively prevent the slurry from entering the O-ring loading space and exhibit a good mechanical seal function.

The present invention provides a slurry fluid in a relative rotating portion of a movable seal ring held on one of a rotating shaft and a seal case via a secondary seal O-ring so as to be movable in the axial direction and a fixed seal ring fixed to the other side. In a mechanical seal for slurry fluid configured to shield and seal a region and a non-slurry fluid region, in particular, in order to achieve the above-described object, in particular, the opposed circumference of the movable seal ring and the rotating shaft or seal case holding the same Slurry fluid into the loading space of the secondary seal O-ring is arranged between the faces and placed on the slurry fluid region side of the secondary seal O-ring and loaded with the slurry fluid intrusion prevention O-ring in a sandwiched state. configured to prevent intrusion, the slurry fluid penetration preventing O-ring, the diameter of the O-ring a kerf ring extending parallel to the axial direction of the movable seal ring in its cross-section It suggests that you configured in comparison with the case of not forming the kerf increases the deformation force to the axial direction by forming a plurality of kerfs in parallel form concentric therewith countercurrent Is. As the secondary seal O-ring, a commercially available general O-ring (shear hardness of 70 to 90 °) is used instead of a special O-ring as shown in FIG.

  In a preferred embodiment, a slurry fluid invasion prevention O-ring having a shear hardness of 70 to 90 ° in a state where no kerf is formed is used. That is, the slurry fluid intrusion prevention O-ring is configured by forming a kerf in a commercially available O-ring (shear hardness: 70 to 90 °) made of a material suitable for the properties of the slurry fluid. The number of kerfs can be arbitrarily set according to use conditions, and a plurality of kerfs can be formed. When a plurality of kerfs are formed, these kerfs are arranged and formed so as to be concentrically arranged in parallel with the radial direction of the slurry fluid intrusion preventing O-ring. The kerf is generally opened on the O-ring peripheral surface on the non-slurry fluid region side and does not open on the O-ring peripheral surface on the slurry fluid region side. Further, in order to further reduce the deformation resistance force of the slurry fluid preventing O-ring in the axial direction of the movable sealing ring (that is, to further improve the O-ring deformability in the axial direction), lubrication is performed in the kerf. It is preferable to apply an agent. Further, the O-ring cross-sectional shape in a natural state that is not pinched (not compressed and deformed) is circular for the secondary seal O-ring, but for the slurry fluid intrusion prevention O-ring, in addition to the circular shape, It may be oval, polygonal, etc., and commercially available O-rings can be used.

  In the slurry fluid mechanical seal of the present invention, the opening on the slurry fluid region side in the loading space of the secondary seal O-ring is closed with the slurry fluid invasion preventing O-ring, and further for preventing slurry fluid intrusion. Since the O-ring has a low deformation resistance in the axial direction of the movable seal ring, the relative movement of the secondary seal O-ring is hindered by the solidification and deposition of slurry components and the presence of the O-ring for preventing slurry fluid intrusion. There is no. Therefore, the slurry fluid can be satisfactorily sealed without impairing the followability of the movable sealing ring.

  In addition, the slurry fluid intrusion prevention O-ring is a commercially available O-ring similar to the secondary seal O-ring because the deformation resistance is reduced by forming a kerf in the O-ring. The material suitable for the properties of the slurry fluid can be appropriately selected. For example, when the slurry fluid is corrosive or chemical, an O-ring made of a material having high corrosion resistance and chemical resistance such as fluorine rubber can be used. Rings can be used arbitrarily. Therefore, as in the case of using an O-ring made of soft rubber, the material of the O-ring is limited, and the applicable usage conditions (such as the properties of the slurry fluid) are not limited thereby.

  In addition to O-rings for secondary seals, commercially available O-rings with special shapes and materials can be used instead of O-rings with special shapes and materials, as well as O-rings with special shapes and materials. The O-ring cost can be reduced as compared with the case where a similar one is used. Moreover, the slurry fluid preventing O-ring can be modified (reduced in deformation resistance) by subjecting a commercially available O-ring to a very simple process such as forming a kerf in the O-ring. The mechanical seal manufacturing cost including the ring cost can be greatly reduced.

  FIG. 1 is a longitudinal side view showing an embodiment of a mechanical seal for slurry fluid according to the present invention, FIG. 2 is a detailed view showing an enlarged main part of FIG. 1, and FIG. 3 is III-III of FIG. FIG. 4 is a longitudinal side view of a main part taken along a line, and FIG. 4 is a vertical side view showing the main part (O-ring for preventing slurry fluid intrusion) in FIG.

  The slurry fluid mechanical seal shown in FIG. 1 is a slurry fluid (a liquid or gas containing a slurry component such as a solid component or a solidified component). For example, powder, chemical solution, sludge water, CMP polishing solution, dust gas, liquid A seal case (seal flange) 2 attached to a shaft seal casing (pump housing, etc.) 1 of a rotating device (slurry pump, etc.) that handles food, etc., and the seal case 2 can move in the axial direction (front-rear direction) , A movable seal ring 3 fitted and held, a fixed seal ring 4 fixed to a rotary shaft (pump shaft or the like) 5 penetrating the seal case 2, and the movable seal ring 3 pressed against the fixed seal ring 4. A spring 6, a seal case 2, a movable seal ring 3, and a secondary seal O-ring 7 and a slurry fluid intrusion-prevention O-ring 8 loaded between the opposed peripheral surfaces. Four End surfaces configured to shield and seal the slurry fluid region A that is the in-machine region and the atmospheric region (non-slurry fluid region) B that is the out-of-machine region by the relative rotational sliding contact action of the sealed end surfaces 31 and 41 as the opposite end surfaces. It is a contact type, and is devised so that it can be attached to and detached from the shaft seal casing 1 and the rotary shaft 5 in a state where the stationary side sealing element and the rotary side sealing element are integrally connected by an appropriate number of set plates 9. Cartridge type.

  As shown in FIG. 1, the stationary side sealing element includes a seal case 2, a movable seal ring 3, a spring 6, a secondary seal O-ring 7, a slurry fluid intrusion-preventing O-ring 8, and a drive pin 10. The rotary shaft side sealing element includes a fixed sealing ring 4, a sleeve 12, and a stopper ring 13, as shown in FIG.

  As shown in FIG. 1, the seal case 2 is a cylindrical structure including an annular plate-shaped flange portion 21 and a cylindrical holding portion 22 protruding rearward from the radial intermediate portion thereof. The flange part 21 is attached to the shaft seal part casing 1 by attaching the flange part 21 to the rear end part of the shaft seal part casing 1 with an appropriate number of bolts 24 in a state of being fitted to the inner peripheral part of the part casing 1.

  As shown in FIG. 1, the movable sealing ring 3 is fitted and held in the holding portion 22 of the seal case 2 via the secondary seal O-ring 7 so as to be movable in the axial direction (front-rear direction). The drive pin 10 provided in the flange portion 21 prevents relative rotation with respect to the seal case 2 while allowing axial movement within a predetermined range.

  As shown in FIG. 1, the spring 6 is interposed between the flange portion 21 of the seal case 2 and the movable sealing ring 3, and presses and urges the movable sealing ring 3 to a fixed sealing ring 4 described later. It is.

  As shown in FIG. 1, the secondary seal O-ring 7 is formed between the opposing peripheral surfaces of the seal case 2 and the movable sealing ring 3 (the inner peripheral surface 23 of the holding portion 22 of the seal case 2 and the outer peripheral surface of the movable sealing ring 3. Between the opposing peripheral surfaces 23 and 32 while allowing the movable seal ring 3 to move in the axial direction. The O-ring 7 has a circular cross-sectional shape in a natural state where it is not pinched (compressed and deformed), and is a commercially available product composed of an incompressible elastic material (for example, natural rubber, synthetic rubber, fluororubber, etc.) (The shear hardness is 70 to 90 °), and the constituent material is appropriately selected according to the use conditions (properties of the slurry fluid, etc.). For example, when the slurry fluid is a corrosive fluid or a liquid food, one made of fluororubber having excellent corrosion resistance and chemical resistance is selected. As shown in FIG. 2, a cylindrical secondary seal surface 23a with which the outer peripheral surface of the secondary seal O-ring 7 is in pressure contact with the inner peripheral surface 23 of the holding portion 22 and its non-slurry fluid region side end (front end). The tapered annular surface 23b and the secondary seal surface 23a are connected from the end (rear end) on the slurry fluid region side and gradually expand in the direction of the slurry fluid region (rear), and the slurry fluid region side thereof. A cylindrical O-ring holding surface 23d extending from the end (rear end) to the end portion (rear end portion) of the holding portion 22 is formed, and the secondary seal O-ring 7 is formed in the non-slurry fluid region direction. It is loaded between the secondary seal surface 23a and the outer peripheral surface 32 of the movable sealing ring 3 in a state where the projection to the surface is regulated by the locking surface 23b.

  As shown in FIG. 1, the slurry fluid intrusion prevention O-ring 8 is disposed between the opposing peripheral surfaces 23 and 32 of the seal case 2 and the movable seal ring 3 on the slurry fluid region side (rear side) of the secondary seal O-ring 7. ) And loaded in a pinched state. That is, the slurry fluid intrusion preventing O-ring 8 includes the tapered surface 23c and the holding surface 23d, which are the rear end portions of the inner peripheral surface 23 of the holding portion 22 of the seal case 2, and the outer periphery of the movable sealing ring 3, as shown in FIG. It is loaded between the surface 32 and prevents the slurry fluid from entering the loading space (O-ring loading space) 11 of the secondary seal O-ring 7.

  The slurry fluid intrusion prevention O-ring 8 has a cross-sectional shape in a natural state that is not pinched (compressed) and has a larger diameter than that of the secondary seal O-ring 7, and is similar to the secondary seal O-ring 7. And a commercially available material (shear hardness of 70 to 90 °) composed of an incompressible elastic material (for example, natural rubber, synthetic rubber, fluororubber, etc.), and the component material is used under conditions of use (property of slurry fluid). Etc.) as appropriate. In this example, an O-ring having the same quality as the secondary seal O-ring 7 is used except that the cross-sectional diameters are different.

  Thus, the slurry fluid intrusion prevention O-ring 8 is formed by subjecting a commercially available O-ring to the following simple processing (grooving), thereby preventing deformation resistance in the axial direction (front-rear direction) of the movable sealing ring 3. The force is reduced, and the elastic deformation in the axial direction can be easily performed.

  That is, as shown in FIGS. 1 to 4, the slurry fluid intrusion prevention O-ring 8 is an annular kerf that extends in parallel with the axial direction of the movable sealing ring 3 in its cross section, and is concentric with the O-ring 8. A plurality of kerfs 81 are formed in parallel. The number N of kerfs 81 is determined by the required degree of deformation resistance reduction (degree of reduction in deformation resistance force in the axial direction (front-rear direction) of the movable seal ring 3), the cross-sectional diameter of the O-ring 8, and the slurry The pressure is appropriately set according to the use conditions such as the pressure in the fluid region A or the differential pressure between the regions A and B. In this example, N = 2 as shown in FIGS. Each kerf 81 is open to an O-ring peripheral surface portion (front surface of the O-ring 8) 82 on the non-slurry fluid region side, and an O-ring peripheral surface portion (rear surface of the O-ring 8) 83 on the slurry fluid side It is not open. The lengths L of the kerfs 81, 81 in the O-ring cross section are the same, and the formation positions of both the kerfs 81, 81 in the O-ring cross section are such that the O-ring 8 is formed by the kerfs 81, 81 as shown in FIG. The thicknesses H1 and H2 of the three portions 84 divided by the kerfs 81 and 81 are set to be the same or substantially the same. The kerf depth is set such that the distance L from the kerf end to the O-ring circumferential surface is smaller than the radius D / 2 of the O-ring cross section.

  The slurry fluid intrusion prevention O-ring 8 formed with such kerfs 81, 81 is in the direction perpendicular to the axial direction of the movable seal ring 3, that is, in the clamping direction between the seal case and the movable seal ring 3. While maintaining the same deformation resistance force (elastic force) as the state in which the kerf 81 is not formed (hereinafter referred to as “the state before kerf formation”), it is divided by the kerf 81, 81 in the direction parallel to the axial direction. When the three portions 84 are deformed with each other, the deformation resistance is significantly reduced as compared with the state before the kerf is formed (which is significantly reduced as compared with the secondary seal O-ring 7). In other words, as the slurry fluid intrusion prevention O-ring 8, regardless of using a commercially available general O-ring (shear hardness: 70 to 90 °) in the same manner as the secondary seal O-ring 7, the axial direction is concerned. A soft O-ring made of soft rubber by forming a kerf 81 in the direction parallel to the direction (for example, silicon rubber, fluorine rubber, nitrile butadiene rubber, chloroprene rubber, ethylene propylene rubber, etc.) And a soft O-ring having a shore hardness of 3 to 30 °). In order to more effectively reduce the deformation resistance, that is, in order to make the deformation of the three divided portions 84 easier, an appropriate lubricant is applied in the kerf 81. It is preferable. That is, the deformation resistance can be further reduced by applying a lubricant to the contact surfaces of the divided portions 84 and 84 to promote slippage on the contact surfaces.

  As shown in FIG. 1, the rotary side sealing element includes a sleeve 12 inserted through the rotary shaft 5, a rotary seal ring 4 fixedly held by the sleeve 12, and a stopper ring 13 for fixing the sleeve 12 to the rotary shaft 5. And first and second set screws 14 and 15.

  As shown in FIG. 1, the fixed sealing ring 4 is fitted and fixed to a cylindrical holding portion 16 formed at the rear end portion of the sleeve 12 via an O-ring 17 and a drive pin 18. The movable seal ring 3 is pressed against the fixed seal ring 4 by a spring 6. The contact surfaces which are the opposing end surfaces of both the sealing rings 3 and 4 are formed on the sealing end surfaces 31 and 41 forming annular smooth surfaces orthogonal to the axis.

  As shown in FIG. 1, the sleeve 12 is inserted into the rotary shaft 5 by the stopper ring 13 and the set screws 14 and 15 with the end (front end) on the non-slurry fluid region side protruding forward from the seal case 2. It is fixed. That is, the stopper ring 13 is fitted and fixed to the front end portion of the sleeve 12 by the first set screw 14, and the second screw 15 screwed to the stopper ring 13 is rotated through the set hole 19 formed in the sleeve 12. By fastening to the shaft 5, the sleeve 12 is fixed to the rotating shaft 5.

  Thus, by engaging an appropriate number of set plates 9 attached to the flange portion 21 of the seal case 2 with the annular recess 20 formed in the sleeve 12, the stationary side sealing element and the rotary side sealing element can be used. Can be assembled into a cartridge structure having the same form. In this assembled form, the sleeve 12 is inserted through the rotary shaft 5, the flange portion 2 of the seal case 2 is attached to the shaft seal casing 1, and the sleeve 12 is rotated by the second set screw 15. By fixing to 5, the incorporation of the slurry fluid mechanical seal into the shaft seal casing 1 and the rotary shaft 5 is completed as shown in FIG. Then, by removing the set plate 9 from the flange portion 21, an appropriate operation of the mechanical seal can be performed. At the time of maintenance, the stationary side sealing element and the rotary side sealing element are integrally connected by the set plate 9, the fixation of the sleeve 12 to the rotary shaft 5 by the second set screw 15 is released, and the seal case 2 is By removing from the shaft seal casing 1, the mechanical seal can be detached from the shaft seal casing 1 and the rotating shaft 5 in the assembled state.

  In the cartridge-type slurry fluid mechanical seal configured as described above, the opening to the slurry fluid region A in the O-ring loading space 11 is closed by the slurry fluid intrusion preventing O-ring 8. The slurry fluid does not enter the O-ring loading space 11. Therefore, the slurry component does not accumulate and adhere to the loading space 11 of the secondary seal O-ring 7, and the movement of the movable seal ring 3 in the axial direction (followability) through the O-ring 7 is not hindered. The secondary sealing function by the O-ring 7 is also exhibited appropriately. Moreover, although the slurry intrusion preventing O-ring 8 uses a commercially available O-ring having a high shear hardness (shear hardness of 70 to 90 °), the moving direction of the movable sealing ring 3 is determined by the grooves 81 and 81. Since the deformation resistance force in the (axial direction) is reduced, the O-ring 8 loaded in a sandwiched state between the seal case 2 and the movable sealing ring 3 does not move the movable sealing ring 3 in the axial direction. There is no hindrance. In addition, the slurry intrusion prevention O-ring 8 is softer than the secondary seal O-ring 7 in the moving direction of the movable seal ring 3 (the deformation resistance is smaller). Even if the O-ring 8 comes into pressure contact with the secondary seal O-ring 7, the movement of the secondary seal O-ring 7 in the axial direction is not hindered by the slurry intrusion prevention O-ring 8. . That is, the secondary seal O-ring 7 does not prevent the movable seal ring 3 from moving in the axial direction. The reduction of the deformation resistance force in the axial direction of the slurry fluid intrusion preventing O-ring 8 is mainly due to the sliding action on the contact surfaces of the portions 84 and 84 divided by the kerfs 81 and 81. Therefore, as described above, by applying a lubricant to the contact surface, the deformation resistance can be reduced more effectively.

  The slurry fluid intrusion prevention O-ring 8 effectively prevents the slurry fluid from entering the O-ring loading space 11 without interfering with the following movement of the movable seal ring 3 and the secondary seal function of the secondary seal O-ring. However, since the commercially available O-ring is merely a simple process (formation of the kerf 81), the economic burden due to the provision of the O-ring 8 is extremely small. . Therefore, compared to the case where a specially shaped secondary seal O-ring is used (see Patent Document 1) or a special soft material slurry fluid intrusion prevention O-ring is provided, the mechanical seal is manufactured. Cost can be greatly reduced. In addition, since no special device (cleaning liquid injection device) as in the case of injecting the cleaning liquid into the O-ring loading space (see Patent Document 2) is required, the manufacturing cost of the mechanical seal is reduced. Of course, the structure of the mechanical seal can be greatly simplified.

It should be noted that the present invention is not limited to the above-described embodiment, and can be appropriately improved and changed without departing from the basic principle of the present invention. For example, the slurry fluid intrusion prevention O-ring 8 can be obtained by forming a kerf 81 in a commercially available general O-ring, but the commercially available O-ring as its constituent material has a circular cross-sectional shape. In addition to the above, ones such as an ellipse and a polygon can be arbitrarily selected. In addition, the number N of kerfs 81 formed in the slurry fluid intrusion prevention O-ring 8 increases as the number of kerfs 81 increases. growing. Thus, addition to the N = 2 as described above, depending on use conditions such as the pressure of the slurry fluid region A, or a如rather N = 3 shown in FIG. 5, further may be an N ≧ 4. Further, when N ≧ 3, for example, as shown in FIG. 5 , it is preferable that the thicknesses H1 and H2 of the divided portions 84 of the O-ring 8 are the same or substantially the same, and the cut depth of the kerfs 81 is The distances L1 and L2 from the end of the kerf to the peripheral surface of the O-ring are preferably set to be the same or substantially the same. The distances L1 and L2 are preferably set to be smaller than the radius D / 2 of the O-ring cross section. Further, in the case of an N ≧ 2, depending on the use conditions of the properties such as the slurry fluid, as shown in FIG. 6 may be reversed cutting direction kerf 81 ....

  The present invention is also applicable to a slurry fluid mechanical seal in which the movable seal ring 3 is provided on the rotary shaft 5 and the fixed seal ring 4 is provided on the seal case 2 contrary to the above-described embodiment. Can do.

It is a vertical side view which shows an example of the mechanical seal for slurry fluids concerning this invention. FIG. 2 is an enlarged detailed view showing a main part of FIG. 1. It is a vertical front view of the principal part which follows the III-III line of FIG. FIG. 3 is an enlarged view showing a main part (O-ring for preventing slurry fluid intrusion) in FIG. 2. FIG. 5 is a view corresponding to FIG. 4 showing a modification of the slurry fluid intrusion prevention O-ring. FIG. 9 is a view corresponding to FIG. 4 and showing another modified example of the slurry fluid intrusion preventing O-ring .

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Shaft sealing part casing 2 Seal case 3 Movable sealing ring 4 Fixed sealing ring 5 Rotating shaft 6 Spring 7 Secondary seal O-ring 8 Slurry fluid intrusion prevention O-ring 23 Seal case inner peripheral surface 31 Sealed end surface 41 Sealed end surface 81 Cut groove 82 O-ring peripheral surface on the non-slurry fluid region side 83 O-ring peripheral surface on the slurry fluid region side 84 Divided portion A Slurry fluid region B Non-slurry fluid region

Claims (4)

Slurry fluid region and non-slurry at relative rotation part of movable seal ring held axially movable on one of rotating shaft and seal case via secondary seal O-ring and fixed seal ring fixed on the other side In a slurry fluid mechanical seal configured to shield and seal a fluid region, a slurry fluid region of an O-ring for secondary seal is provided between opposing circumferential surfaces of a movable sealing ring and a rotary shaft or seal case holding the movable seal ring. The slurry fluid is prevented from entering the loading space of the secondary seal O-ring by loading the O-ring for preventing slurry fluid intrusion in a pinched state. double preventing O-ring, arranged in parallel form a concentric therewith a kerf ring extending parallel to the axial direction of the movable seal ring in the radial direction of the O-ring in its cross-section Mechanical seal slurry fluid, characterized in that by forming a kerf in which is configured to increase the deformation force in comparison with the case of not forming the cut grooves to the axial direction. The mechanical seal for slurry fluid according to claim 1, wherein the O-ring for preventing slurry fluid intrusion has a shear hardness of 70 to 90 ° in a state where no kerf is formed. 3. The slurry according to claim 1 , wherein the kerf opens on an O-ring peripheral surface on the non-slurry fluid region side and does not open on an O-ring peripheral surface on the slurry fluid region side. Mechanical seal for fluid. The mechanical seal for slurry fluid according to claim 1, wherein a lubricant is applied in the kerf .