JP2008008318A - Annular seal member and mechanical seal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an annular seal member suitable for equipment which can use a commercial O-ring but requires the section diameter (size) of the commercial O-ring to be so large as unavailable. <P>SOLUTION: The annular seal member 12 comprises an annular O-ring holder 15, a first O-ring 16 whose inner peripheral portion 16b is held in engagement with a first O-ring groove 15a formed in an outer peripheral portion of the O-ring holder 15, and a second O-ring 17 whose outer peripheral portion 17b is held in engagement with a second O-ring groove 15b formed in an inner peripheral portion of the O-ring holder 15. Between a first seal face 13 formed circular and a second seal face 14 having a smaller diameter, opposing each other in a concentric form, it is loaded in the state that an outer peripheral portion 16a of the first O-ring 16 has pressure contact with the first seal face 13 and an inner peripheral portion 17a of the second O-ring 17 has pressure contact with the second seal face 14. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention provides a concentric and opposed circular first seal surface and a second seal surface having a smaller diameter (for example, a rotation shaft in a mechanical seal and a rotation seal ring fitted and held between the rotation shaft and the rotation seal ring). The present invention relates to an annular seal member loaded between the peripheral surfaces) and a mechanical seal that uses the annular seal member as a secondary seal means between a rotary shaft and a rotary sealing ring fitted and held on the rotary shaft.

  For example, a relative rotation of a sealing end surface, which is an opposing end surface of both sealing rings, includes a rotating sealing ring held axially movable on a rotating shaft and a stationary sealing ring fixed to a seal case through which the rotating shaft passes. In a mechanical seal configured to shield and seal a sealed fluid region that is an inner diameter side region of the relative rotation portion and an unsealed fluid region that is an outer diameter side region of the relative rotation portion, The O-ring loaded between the opposed peripheral surfaces of the rotary seal ring is configured to provide secondary sealing between the rotary seal ring and the rotary shaft while allowing the axial movement of the rotary seal ring (for example, Patent Document 1). (See FIG. 1).

  In such a mechanical seal, the inner diameter of the sealing end face which is the opposite end face of both sealing rings cannot be made smaller than the outer diameter of the rotating shaft, and is inevitably determined by the outer diameter of the rotating shaft. The outer diameter of the sealing end surface is determined in consideration of the balance ratio derived from the relationship with the pressure receiving area of the back pressure by the sealed fluid acting in the direction of pressing the rotary sealing ring to the stationary sealing ring. The area is determined by the diameter of the contact surface with the O-ring in the rotary seal ring (the inner diameter of the rotary seal ring portion with which the O-ring comes into contact, referred to as the balance diameter). Since the O-ring is loaded between the opposed peripheral surfaces of the rotary seal ring and the rotary shaft, the balance diameter is determined by the outer diameter of the rotary shaft and the cross-sectional diameter of the O-ring (“O” defined in JIS B2401). Is inevitably determined by “the thickness of the ring”. That is, the balance diameter is the outer diameter of the rotating shaft and the cross-sectional diameter of the O-ring (more precisely, the radial width of the O-ring cross-section in the state of being loaded between the opposed peripheral surfaces (width in the direction perpendicular to the rotating shaft)) And the total value.

  Therefore, the O-ring used as the secondary seal has an inner diameter corresponding to the outer diameter of the rotating shaft and needs to have a cross-sectional diameter that can provide a desired balance diameter.

Japanese Patent Laid-Open No. 10-053480 (FIG. 1)

  Thus, the dimensions of the O-ring are defined in JIS (for example, JIS B2401, JIS W1516, JIS W1517, etc.) based on the inner diameter and the cross-sectional diameter (thickness). Is commercially available, but when such a standard product (hereinafter referred to as “commercial O-ring”) is used as an O-ring, the selection procedure is to first determine the inner diameter of the O-ring based on the outer diameter of the rotating shaft. Then, an O-ring having a cross-sectional diameter corresponding to a desired balance diameter (commercial O-ring) is selected from commercially available O-rings having the determined inner diameter.

  However, commercially available O-rings with various inner diameters stipulated in JIS are provided, but there are commercially available O-rings with the same inner diameter, and the outer diameter determined from the cross-sectional diameter (thickness) and this and the inner diameter. Since the selection range for the diameter is small, when a commercially available O-ring is used, the design flexibility of the balance diameter and seal surface width (radial width in the relative rotation region of both sealed end surfaces) is small, and the mechanical that is optimal for sealing conditions Often it is difficult to provide a seal.

  For example, in the above-described mechanical seal, when the fluid to be sealed is at a high pressure, in order to exert a stable mechanical seal function (shaft seal function), the balance diameter is increased and the seal surface width is increased as much as possible. Although it is necessary to design, it cannot respond by using a commercially available O-ring selected according to the outer diameter of the rotating shaft. That is, in the mechanical seal in which the rotary seal ring is held on the rotary shaft through the commercially available O-ring so as to be movable in the axial direction, the balance diameter and the outer diameter of the sealing end face are limited by the cross-sectional diameter of the O-ring. The actual situation is that the width cannot be increased beyond a certain level, making it difficult to apply to rotating equipment where the fluid to be sealed is at a high pressure. You will be restricted.

  On the other hand, the balance diameter and seal surface width can be increased by using a special O-ring that has the same inner diameter as a commercially available O-ring but has a large cross-sectional diameter compared to the case of using the commercially available O-ring. However, a special O-ring having a larger cross-sectional diameter than a commercially available O-ring is inevitably inhomogeneous (partially rough), and as a result, the pressure contact force (sealing force) to the rotating seal ring and the rotating shaft. ) Becomes nonuniform in the circumferential direction, and the secondary seal function by the O-ring and the axial movement of the rotary seal ring, that is, the followability, are lowered, and it is difficult to exhibit a good shaft seal function. Further, such special O-rings are not standard products based on JIS but are custom-made products out of the standard, so that they are difficult to manufacture and obtain, and there are significant problems in terms of cost.

  Such a problem also occurs in a sealing device other than a mechanical seal, between a concentrically opposed circular first seal surface and a second seal surface having a smaller diameter (the rotating shaft and the rotating seal ring in the mechanical seal). This occurs in the same manner when a commercially available O-ring is used as the annular seal member loaded between the opposing peripheral surfaces of the two and the countermeasures are desired.

  The present invention has been made in view of such a point, and can use a commercially available O-ring, but it is a device that requires a large cross-sectional diameter (thickness) that cannot be obtained with a commercially available O-ring. In addition to providing an extremely practical annular seal member that can be suitably used, and using this annular seal member as a secondary seal means, the balance diameter and seal surface width can be reduced when a commercially available O-ring is used. The object of the present invention is to provide a mechanical seal that can be set larger than the above and can exhibit a good shaft sealing function (mechanical sealing function) even under high pressure conditions.

  The present invention is an annular seal member loaded between a concentrically opposed circular first seal surface and a second seal surface having a smaller diameter, and in order to achieve the above object, The O-ring holder, the outer periphery of the O-ring holder, the first O-ring whose inner periphery is engaged and held, and the outer periphery of the O-ring holder are engaged and held by the inner periphery. The second O-ring is loaded with the outer peripheral portion of the first O-ring pressed against the first seal surface and the inner peripheral portion of the second O-ring pressed against the second seal surface between the two seal surfaces. Proposed is an annular sealing member configured as described above.

  In a preferred embodiment of such an annular seal member, the first and second O-rings are both the dimensions (inner diameter, cross-sectional diameter) defined by the commercially available O-ring (JIS (JIS B2401 etc.)) described at the beginning. (Thickness)) O-ring) is used. When a commercially available O-ring is used, the outer diameter (= inner diameter + cross section diameter × 2) determined from the inner diameter and the sectional diameter of the first O ring is a dimension corresponding to the diameter of the first seal surface. The second O-ring is selected such that its inner diameter is a dimension corresponding to the diameter of the second seal surface. In this case, the first and second O-rings may have the same or different cross-sectional diameters.

  The present invention also includes a rotary seal ring held on the rotary shaft so as to be movable in the axial direction, and a stationary seal ring fixed to a seal case through which the rotary shaft penetrates. The mechanical seal configured to shield and seal the sealed fluid region that is the inner diameter side region of the relative rotation portion and the non-sealed fluid region that is the outer diameter side region of the relative rotation portion of the end surface achieves the above object. In particular, the gap between the opposed peripheral surfaces of the rotary shaft and the rotary seal ring is secondarily sealed by the annular seal member described above, and the gap between the opposed peripheral surfaces has the same cross-sectional diameter as the first O-ring or the second O-ring. Compared to the case of secondary sealing with an O-ring (more precisely, a commercially available O-ring having the same cross-sectional diameter as a second O-ring (using a commercially available O-ring) whose dimensions (inner diameter) are specified by the outer diameter of the rotating shaft) The balance diameter and It suggests that you configured may set large Lumpur surface width. Such a mechanical seal is in a preferred embodiment and is configured as a static pressure type non-contact gas seal. That is, this static pressure type non-contact gas seal is generated by a seal gas ejected between the sealed end faces by forming a series of seal gas passages for supplying the seal gas between the sealed end faces in the seal case and the stationary seal ring. The sealed end faces are held in a non-contact state by the applied static pressure.

  According to the annular seal member of the present invention, the commercially available O-rings are used as the first and second O-rings, and they are properly loaded between the first seal surface and the second seal surface having an arbitrary diameter. Therefore, even between a first seal surface and a second seal surface having a large radial interval that cannot be sealed with a single commercially available O-ring, it is equivalent to using a single O-ring. The sealing function can be exhibited. Moreover, commercially available O-rings can be used as the first and second O-rings, and the O-ring holder is also easily and inexpensively manufactured by cutting or the like according to the size and shape of the first and second O-rings. Therefore, it is possible to easily and inexpensively manufacture an annular seal member that satisfactorily seals whatever the radial distance between the first seal surface and the second seal surface is any size. Its practical value is extremely large.

  Further, according to the mechanical seal of the present invention, the above-described annular seal member is used as a secondary seal means between the opposed peripheral surfaces of the rotary seal ring and the rotary shaft, so that the balance diameter and the seal surface width can be freely set. And an optimum shaft sealing function (mechanical sealing function) according to the sealing conditions can be exhibited. In particular, even when the fluid to be sealed is at a high pressure, the balance diameter and the seal surface width can be appropriately sized according to the pressure conditions regardless of the diameter of the rotating shaft, and stable and good shaft sealing can be achieved. The function can be demonstrated.

  The configuration of the present invention will be specifically described below with reference to FIGS. FIG. 1 is a longitudinal side view showing an example of a mechanical seal according to the present invention, FIG. 2 is a detailed view showing an enlarged main part of FIG. 1, and FIG. 3 shows the present invention used for the mechanical seal. It is a vertical side view which shows the annular seal member which concerns.

  The mechanical seal 1 shown in FIG. 1 is used as a shaft sealing means for a small rotating device (rotary valve or the like) that handles gas containing solid foreign matters (powder, sludge, etc.) or liquid foreign matters (water, oil, etc.), for example. A cylindrical seal case 3 that is integrally formed with or attached to the housing of the rotating device in a state where the rotating shaft 2 of the rotating device is concentrically penetrated, and the seal case 3 A stationary seal ring 4 fitted and fixed to the rotary shaft, a rotary seal ring 5 fitted and held so as to be movable in the axial direction on the rotary shaft 2 so as to face the stationary seal ring 4, and a spring fitted and fixed to the rotary shaft 2 Seal gas for injecting seal gas 8 between retainer 6, spring member 7 interposed between rotary seal ring 5 and spring retainer 6, and sealed end faces 4a and 5a as opposed end faces of both seal rings 4 and 5 Through 9 in the relative rotation portion of the sealed end faces 4a and 5a, a sealed fluid region (in-machine region) H which is an inner diameter side region of the relative rotation portion and an unsealed fluid region (atmosphere region) which is an outer diameter side region thereof It is a static pressure type non-contact gas seal constructed so as to shield the outer region L). In the following description, the left and right mean the left and right in FIG.

  As shown in FIG. 1, the stationary seal ring 4 is a circle that is fitted and held on the inner peripheral portion of the seal case 3 via a pair of front and rear O-rings 10 and 10 while being loosely fitted to the rotary shaft 2. It is an annular body, and its front end surface (left end surface) is configured as a sealed end surface 4a that is a smooth annular plane. As shown in FIG. 1, an uneven labyrinth seal or screw seal 11 that is close to the outer peripheral surface of the rotating shaft 2 is formed on the inner peripheral portion on the proximal end side of the stationary seal ring 4. As shown in FIG. 1, the rotary shaft 2 is formed by inserting and fixing a cylindrical sleeve 2b to a shaft body 2a.

  As shown in FIG. 1, the rotary seal ring 5 is an annular body fitted and held on the rotary shaft 2 so as to be movable in the axial direction (left and right direction) via the annular seal member 12 according to the present invention. The surface (right end surface) is configured as a sealed end surface 5a which is a smooth annular plane. The rotary seal ring 5 includes a distal end portion (a portion where the sealed end surface 5a is formed) 5b loosely fitted to the rotary shaft 2 and a base end portion 5c having an inner diameter larger than that of the rotary seal ring 5. And the opposed peripheral surfaces 13 and 14 (between the inner peripheral surface 13 of the base end portion 5c and the outer peripheral surface 14 of the sleeve 2b), the secondary seal state is established between the rotary shaft 2 and the annular seal member 12. It is held so that it can move in the axial direction. The sealed end face 5a of the rotary seal ring 5 has an outer diameter larger than the outer diameter of the sealed end face 4a of the stationary seal ring and an inner diameter smaller than the inner diameter of the sealed end face 4a. , 5a, the seal surface width W1, which is the radial width of the annular region, is given by the inner and outer diameters of the stationary seal ring 4 (more precisely, the inner and outer diameters of the seal end surface 4a) D1 and D2, as shown in FIG. That is, W1 = (D2-D1) / 2.

  As shown in FIG. 1, the spring retainer 6 has a double cylinder structure in which the base ends (left end portions) of the inner and outer cylinders 6a and 6b are connected by an annular wall 6c. The base end portion 5c of the rotary seal ring 5 is fitted between the opposed peripheral surfaces of the inner and outer cylinders 6a and 6b, and the drive pin 18 penetrating the annular wall 6c is screwed to the rotary seal ring 5 By doing so, relative rotation of the rotary seal ring 5 is prevented while allowing the axial movement of the rotary seal ring 5 within a predetermined range. O-rings 19 and 19 for stabilizing the followability of the rotary seal ring 5 are loaded between the outer peripheral surface of the rotary seal ring 5 and the inner peripheral surface of the outer cylinder 6b.

  As shown in FIG. 1, the spring member 7 is composed of a plurality of coil springs (only one is shown) interposed between the annular wall 6 c of the spring retainer 6 and the base end portion 5 c of the rotary seal ring 5. The rotary seal ring 5 is pressed against the stationary seal ring 4 to generate a closing force that acts in a direction to close the sealed end faces 4a and 5a.

  The seal gas passage 9 is a series of passages penetrating the seal case 3 and the stationary seal ring 4, and is a space formed in a fitting portion between the seal case 3 and the stationary seal ring 4 as shown in FIG. 1. The annular communication space 9a sealed by the O-rings 10 and 10, the case side passage 9b that penetrates the seal case 3 in the radial direction and reaches the communication space 9a, and the static pressure generating groove formed in the sealed end face 4a 9c and a seal ring side passage 9d that penetrates the stationary seal ring 4 and reaches the static pressure generating groove 9c from the communication space 9a. The static pressure generating groove 9c is an annular groove or a plurality of arcuate grooves that are concentric with the sealing end surface 4a. The seal gas passage 9 supplies a seal gas 8 higher than the fluid pressure in the in-machine region H to the static pressure generating groove 9c through the case side passage 9b, the communication space 9a, and the sealing ring side passage 9d. A seal gas 8 is jetted between 4a and 5a, and a static pressure is generated between the sealed end faces 4a and 5a to keep it in a non-contact state. As the seal gas 8, a gas (generally nitrogen gas) that is inert and harmless to the fluid to be sealed is used. A restrictor 9e such as an orifice, a capillary tube, or a porous member is disposed at an appropriate position of the seal gas passage 9 (sealed ring side passage 9d) so that the gap between the sealed end faces 4a and 5a is automatically adjusted. It has become. That is, when the clearance between the sealed end surfaces 4a and 5a becomes large due to vibrations of the rotating device, the amount of seal gas flowing out from the static pressure generating groove 9c between the sealed end surfaces 4a and 5a and the static pressure through the restrictor 9e. The amount of seal gas supplied to the generation groove 9c becomes unbalanced, the pressure in the static pressure generation groove 9c decreases, and the opening force becomes smaller than the closing force, so the gap between the sealed end faces 4a and 5a becomes smaller. Thus, the gap is adjusted to an appropriate value. Conversely, when the gap between the sealed end faces 4a and 5a becomes small, the pressure in the static pressure generating groove 9c increases due to the same action as described above, and the opening force becomes larger than the closing force, and the sealed end face 4a. , 5a is changed so as to increase, and the gap is adjusted to an appropriate one. The stationary seal ring 4 is formed with a passage 20 for supplying the seal gas 8 from the communication space 9a to the labyrinth seal (or screw seal) 11. The passage 20 is also provided with a restrictor 20a similar to the restrictor 9e.

  As shown in FIG. 2, the annular seal member 12 includes an inner peripheral surface 13 of a rotary seal ring 5 as a concentric and opposed circular first seal surface and an outer peripheral surface of the rotary shaft 2 as a second seal surface having a smaller diameter. 14 is a composite O-ring member that is loaded to seal (secondary seal) between the O-ring holding member 15 and the outer periphery of the O-ring holding member 15 as shown in FIG. And a second O-ring 17 engaged and held on the inner peripheral portion of the O-ring holding body 15.

  The first O-ring 16 is engaged with an annular first O-ring groove 15 a formed on the outer peripheral portion of the O-ring holding body 15, so that the outer peripheral portion 16 a becomes an outer peripheral portion of the O-ring holding body 15. The O-ring holding body 15 is held in a state protruding from the O-ring. The second O-ring 17 is engaged with an annular second O-ring groove 15 b formed on the inner peripheral portion of the O-ring holding body 15, so that the inner peripheral portion 17 a is in the O-ring holding body 15. It is held by the O-ring holder 15 so as to protrude from the peripheral portion.

  The first and second O-rings 16 and 17 are both commercially available O-rings (commercial standard products defined by JIS B2401, JIS W1516, JIS W1517, etc.) made of NBR, FKM, etc., and the rotary seal ring 5 And the diameter of the opposed peripheral surfaces 13 and 14 of the rotary shaft 2 are selected. That is, as the first O-ring 16, the outer diameter d3 (= d1 + d2 × 2) determined from the inner diameter d1 and the cross-sectional diameter (thickness) d2 is a dimension corresponding to the diameter D3 of the first seal surface 13. In other words, a commercially available O-ring having an outer diameter d3 such that the outer peripheral portion 16a can be brought into pressure contact with the first seal surface 13 with an optimum contact pressure (seal pressure) is used. Further, the second O-ring 17 has an inner diameter d4 having a size corresponding to the diameter D4 of the second seal surface 14, that is, the inner peripheral portion 17a has an optimum contact pressure (seal) on the second seal surface 14. A commercially available O-ring having an inner diameter d4 that can be pressed by pressure) is used. Needless to say, the outer diameter d3 of the first O-ring 16 is larger than the outer diameter of the second O-ring 17, and the inner diameter d4 of the second O-ring 17 is smaller than the inner diameter d1 of the first O-ring 16. The radial thickness d0 (= (d3-d4) / 2) of the annular seal member 12 corresponds to the sectional diameter (thickness) of a single O-ring, and this radial thickness d0 is the first thickness d0. The radial distance D0 (= (D3-D4) / 2) between the seal surface 13 and the second seal surface 14 is set to be an appropriate amount larger than the radial distance D0.

  The O-ring holding body 15 is an inelastic member or a rigid body made of metal or the like that can be easily and inexpensively manufactured by cutting or the like, and has an arcuate cross-section corresponding to the cross-sectional diameter d2 of the first O-ring 16 on the outer peripheral portion. This is an annular body in which a first O-ring groove 15a is formed and a second O-ring groove 15b having an arcuate cross section corresponding to the cross-sectional diameter d5 of the second O-ring 17 is formed on the inner periphery. Needless to say, the O-ring holding body 15 is configured as an annular body having a shape that does not interfere with the seal surfaces 13 and 14 when the annular seal member 12 is loaded between the seal surfaces 13 and 14.

  In the mechanical seal 1 configured as described above, when the seal gas 8 is supplied from the gas passage 9 between the sealed end surfaces 4a and 5a, the opening force acting in the direction of opening the sealed end surfaces 4a and 5a. Will occur. This opening force is due to the static pressure generated by the seal gas 8 supplied to the static pressure generating groove 9c. Therefore, the sealing end faces 4a and 5a are formed by the opening force and the closing force acting in the closing direction between the sealing end faces 4a and 5a (the spring load by the spring member 7 pressing and urging the rotary sealing ring 5 toward the stationary sealing ring 4 and And the non-contact state in which the back pressure by the fluid to be sealed acting on the rotary seal ring 5 is balanced. Since the seal gas 8 is higher than the pressure in the in-machine region H and is ejected from the sealed end surfaces 4a and 5a to both regions H and L, leakage of the sealed fluid from the sealed end surfaces 4a and 5a is completely prevented. As a result, the space between both regions H and L is well shielded.

  At this time, a composite O-ring structure in which the first and second O-rings 16 and 17 having different diameters are combined as a secondary sealing means between the opposed peripheral surfaces 13 and 14 of the rotary seal ring 5 and the rotary shaft 2 is formed. Since the annular seal member 12 is used, the balance diameter can be set freely regardless of the use of commercially available O-rings as the O-rings 16 and 17, and the conditions can be set according to the sealing conditions. The optimum seal surface width W1 (= (D2-D1) / 2) can be ensured.

  That is, the balance diameter, that is, the diameter of the first seal surface 13 with which the first O-ring 16 contacts (the inner diameter of the rotary seal ring portion (base end portion 5c) to be secondary sealed between the rotary shaft 2) D3 is O It can be arbitrarily set by selecting a commercially available O-ring used as the first O-ring 16 to be held on the outer peripheral portion of the ring holder 15. In the case of using a commercially available O-ring, the selection width of the second O-ring 17 is limited by the outer diameter D4 of the rotating shaft 2 (the diameter of the second seal surface 14). There is no limitation, and a commercially available O-ring having an arbitrary size can be selected as the first O-ring 16 by appropriately setting the shape (outer diameter size) of the O-ring holding body 15. Therefore, by appropriately selecting a commercially available O-ring having an outer diameter d3 as the first O-ring 16, and depending on the inner diameter d1 and the cross-sectional diameter d2 of the selected commercially available O-ring (first O-ring 16), an O-ring holder By setting the outer diameter of 14 and the shape of the first O-ring groove 15a, the balance diameter D3 and the seal surface width W1 can be set to be optimal for the sealed fluid pressure (fluid pressure in the in-machine region H). It is possible to exhibit a stable and good shaft sealing function (mechanical sealing function) even under conditions where the in-machine region H is at a high pressure.

  Incidentally, when a single commercially available O-ring 12A is used as the secondary sealing means, the O-ring 12A has an inner diameter (second O 2) corresponding to the outer diameter D4 of the rotary shaft 2 as shown in FIG. A commercially available O-ring (corresponding to the inner diameter d4 of the ring 17) is used. Therefore, even if the O-ring 12A having the largest cross-sectional diameter (thickness) among the commercially available O-rings having such an inner diameter is used, that is, the one having the largest outer diameter is used, FIG. As shown in A), the diameter of the first seal surface 13 set by the outer diameter of the O-ring 12A, that is, the balance diameter D5 is extremely smaller than the balance diameter D3 when the annular seal member 12 of the present invention is used. The seal surface width W2 determined by the balance diameter D5 is also extremely smaller than the seal surface width W1 when the annular seal member 12 is used. Therefore, when a single commercially available O-ring 12A is used, a mechanical seal that can be suitably used under high pressure conditions cannot be provided. For example, when a single O-ring 12A is used due to the mechanical seal design, V. Although it can only be used in a low pressure region of ˜0.2 MPaG, when the annular seal member 12 is used in a mechanical seal having the same structure as this, it can be used in a high pressure region of about 1 MPaG. In addition, when used under any pressure conditions in the high and low pressure regions, it is preferable that the balance ratio is designed to be within a certain range for the sealing function, but if the annular seal member 12 of the present invention is used. As described above, the balance diameter D3 and the seal face width W1 can be freely set depending on the selection of the commercially available O-ring used as the first O-ring 16, so that the low-pressure region using a single commercially available O-ring is used. It is possible to obtain a balance ratio equivalent to that in the mechanical seal, and even in a high pressure range of about 1 MPaG, the same good as when using the mechanical seal for the low pressure range in the low pressure range (FV to 0.2 MPaG). A mechanical seal that can exhibit a sealing function can be provided.

  Further, when a single O-ring is used as the secondary sealing means, as shown in FIG. 4B, the O-ring has a cross-sectional diameter (thickness equal to the radial thickness d0 of the annular seal member 12). It is possible to obtain the same balance diameter D6 (= D3) and seal surface width W3 (= W1) as when the annular seal member 12 is used. However, the use of such a special O-ring 12B is not practical from the viewpoint of the sealing function and cost as described at the beginning. The annular seal member 12 of the present invention can use commercially available O-rings 16 and 17 even when such a special O-ring 12B must be used. In combination with the fact that it can be manufactured inexpensively and easily, there is no problem in terms of sealing function and cost as in the case of using the special O-ring 12B.

  The present invention is not limited to the above-described embodiment, and can be appropriately changed and improved without departing from the basic principle of the present invention. For example, the annular seal member 12 is used as a secondary sealing means of the rotary seal ring 5 in the above-described static pressure type non-contact gas seal 1, and in a dynamic pressure type non-contact type mechanical seal or an end face contact type mechanical seal. As the secondary sealing means of the rotary seal ring, it can be suitably used while ensuring the degree of design freedom as in the case described above, and further, there is a radial interval such that a commercially available O-ring cannot be used. It can be used suitably also for sealing devices other than the mechanical seal which needs to seal a big 1st sealing surface and a 2nd sealing surface statically or dynamically.

It is a vertical side view which shows an example of the mechanical seal which concerns on this invention. FIG. 2 is an enlarged detailed view showing a main part of FIG. 1. It is a vertical side view which takes out and shows the principal part (annular seal member) of the said mechanical seal. It is a vertical side view equivalent to FIG. 2 which shows the usage form of the O-ring in a general mechanical seal, (A) is an example using a commercially available O-ring, (B) is an example using a special O-ring, Each shows.

Explanation of symbols

1 Mechanical seal (static pressure non-contact gas seal)
2 Rotating shaft 3 Seal case 4 Static sealing ring 4a Sealing end face 5 of stationary sealing ring Rotating sealing ring 5a Sealing end face 6 of rotating sealing ring Spring retainer 7 Spring member 8 Seal gas 9 Seal gas passage 12 Annular seal member 13 First seal surface (Inner peripheral surface of rotating seal ring)
14 Second seal surface (outer peripheral surface of rotating shaft)
15 O-ring holder 15a First O-ring groove 15b Second O-ring groove 16 First O-ring 16a Outer portion 16b of first O-ring Inner portion 17 of first O-ring Second O-ring 17a Second O-ring Inner peripheral portion 17b Outer peripheral portion D3 of second O-ring Balance diameter H Sealed fluid region (in-machine region)
L Non-sealed fluid area (outside machine area)
W1 Seal face width

Claims (3)

An annular seal member loaded between a concentrically opposed circular first seal surface and a second seal surface having a smaller diameter than the circular seal member,
An O-ring holder having an annular shape, a first O-ring having an inner peripheral portion engaged and held on the outer peripheral portion of the O-ring holder, and an outer peripheral portion being engaged and held on an inner peripheral portion of the O-ring holder. Loaded with the outer periphery of the first O-ring pressed against the first seal surface and the inner periphery of the second O-ring pressed against the second seal surface. An annular seal member characterized by being configured as described above. In the relative rotation portion of the sealing end face which is the opposite end face of both sealing rings, comprising a rotary sealing ring held axially movable on the rotary shaft and a stationary seal ring fixed to a seal case through which the rotary shaft passes. In the mechanical seal configured to shield and seal the sealed fluid region which is the inner diameter side region of the relative rotation portion and the non-sealed fluid region which is the outer diameter side region thereof,
The space between the opposed peripheral surfaces of the rotating shaft and the rotational seal ring is secondarily sealed by the annular seal member according to claim 1, and the space between the opposed peripheral surfaces is O having the same cross-sectional diameter as the first O-ring or the second O-ring. A mechanical seal characterized in that the balance diameter and the seal surface width can be set larger than in the case of secondary sealing with a ring.   A series of sealing gas passages for supplying sealing gas between the sealing end faces is formed in the sealing case and the stationary sealing ring, and the sealing end faces are not contacted by the static pressure generated by the sealing gas ejected between the sealing end faces. The mechanical seal according to claim 2, wherein the mechanical seal is a static pressure non-contact gas seal configured to be kept in a state.

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