JP7165097B2 - Shaft seal device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shaft seal device installed in rotating equipment such as a boiler feedwater pump, a boiler circulation pump, and a hot oil pump.

As disclosed in Patent Document 1 or Patent Document 2, this type of shaft seal device includes a mechanical seal having a case-side seal ring provided on a seal case and a shaft-side seal ring provided on a rotary shaft. Seals designed to seal fluids are well known.

Such a shaft seal device seals the fluid to be sealed (hereinafter referred to as the "primary seal") at the relatively rotating portions of the sealing end faces, which are the opposing end faces of the two seal rings, by mechanical seals, and properly exhibits this primary sealing function. In order to achieve this, an O-ring is placed between the mechanical seal constituent members that constitute the mechanical seal (for example, between the case-side seal ring and the seal case that holds it, or between the shaft-side seal ring and the sleeve that holds it). is sealed (hereinafter referred to as "secondary seal").

Therefore, in such a shaft sealing device, for example, as disclosed in Patent Document 1, flushing means for flushing the cooling liquid from the liquid supply passage of the seal case is provided, or as disclosed in Patent Document 2, By providing cooling means using cooling liquid, such as providing a cooling jacket that circulates cooling liquid in the hollow chamber formed in the seal case, mechanical seal components such as the seal case and the seal ring are prevented from becoming hotter than necessary. is devised.

JP 2015-081626 A WO2013/187322

However, due to unexpected troubles in such cooling means (for example, cooling liquid cooling equipment or circulation pumps fail, electric circuits that drive and control them stop functioning due to power failure, etc.) Unexpected abnormally high temperature may occur, or the fluid to be sealed may become abnormally hot beyond the assumed range due to unexpected troubles on the rotating equipment side (rotating equipment or its peripheral equipment, etc.) equipped with the shaft seal device. be.

On the other hand, as an O-ring for secondary sealing between mechanical seal constituent members, unless the sealing conditions such as the properties of the sealed fluid are extremely special, General O-rings such as NBR (nitrile rubber) O-rings with a heat resistance temperature of about 100 to 150° C. are used without considering the increase in temperature.

Therefore, if the mechanical seal components and the sealed fluid reach an unexpectedly high temperature as described above, the O-ring will be heated above the heat resistance temperature due to heat transfer from the mechanical seal components and contact with the sealed fluid. and breakage (hereinafter referred to as "heat breakage"), and the specified secondary sealing function is no longer exhibited. As a result, even if the sealed fluid does not leak from the primary seal portion, a large amount of the sealed fluid leaks from the secondary seal portion, and a major accident occurs due to the loss of the shaft sealing function.

The present invention prevents the O-ring, which is a secondary seal between the mechanical seal constituent members, from being damaged by heating even in a situation where the mechanical seal constituent members and the sealed fluid reach an unexpectedly high temperature. It is an object of the present invention to provide a shaft sealing device capable of avoiding occurrence of a serious accident due to loss of shaft sealing function.

The present invention is a shaft seal device configured to seal a sealed fluid in an area inside a machine by a mechanical seal comprising a case-side seal ring provided on a seal case and a shaft-side seal ring provided on a rotating shaft. , in order to achieve the above object, in particular, an emergency seal is disposed on the inboard region side of the mechanical seal, and the emergency seal comprises a stationary seal ring fixed to the rotating shaft; A sealing position where the movable sealing end face of the seal case contacts the fixed sealing end face of the stationary seal ring to seal the sealed fluid, and a non-sealing position where the movable sealing end face is separated from the fixed sealing end face. a movable seal ring held movably in the axial direction, a movable seal ring holding means for holding the movable seal ring at the non-sealing position, and moving the movable seal ring from the non-sealing position to the sealing position. and a low-melting-point member that melts at a predetermined temperature to activate the forced movement function of the movable seal ring moving means. We propose a device.

In a preferred embodiment of such a shaft sealing device, the movable seal ring holding means, the movable seal ring moving means and the low melting point member are constructed as in (1) or (2).

(1) The movable seal ring holding means is a spring loaded between the seal case and the movable seal ring to urge and hold the movable seal ring at the non-sealing position, and the movable seal ring moving means A sealed back pressure chamber formed between the case and the movable seal ring, and a supply to the back pressure chamber to move the movable seal ring from the non-sealing position to the sealing position against the urging force of the spring. a high-pressure fluid to be moved to a position, and a communication passage communicating between a supply source of the high-pressure fluid and the back pressure chamber, wherein the low-melting-point member controls the supply of the high-pressure fluid to the communication passage. It is a plug loaded in the communication passage in a blocking state. In such a configuration, the high-pressure fluid is the fluid to be sealed, the supply source of the high-pressure fluid is the machine interior region, and the communication path communicates the back pressure chamber and the machine interior region with the movable seal ring or the seal case. It is preferable that the plug body is melted by contact with the sealed fluid and/or heat transfer from the mechanical seal constituent member constituting the mechanical seal, or the high pressure fluid is a pressurized gas other than the fluid to be sealed, the supply source of the high pressure fluid is a storage tank for the pressurized gas, and the communication path communicates the back pressure chamber and the storage tank, At least the back pressure chamber side portion is formed in the seal case, and the plug body is loaded in the communicating passage portion formed in the seal case and is melted by heat transfer from the seal case. It is preferable to be

(2) The movable seal ring moving means is a spring loaded between the seal case and the movable seal ring to urge the movable seal ring to the sealing position, and the movable seal ring holding means is movable. A connecting body that connects the movable seal ring and the seal case in a state where the seal ring is held at the non-sealing position against the biasing force of the spring, and at least part of the connecting body communicates with the fluid to be sealed. It is composed of the low-melting-point member that melts due to contact and/or heat transfer from the seal case.

Further, in the above shaft seal device, in any of the configurations of (1) and (2) above, a mechanical seal constituent member constituting the mechanical seal in which the stationary seal ring is fixed to the rotating shaft is provided. and seals between the stationary seal ring and the rotating shaft, between the movable seal ring and the seal case, and between the mechanical seal constituent members that constitute the mechanical seal. It is preferable to seal with an elastic seal ring that is superior in heat resistance to the O-ring.

The shaft seal device of the present invention detects in advance even in a situation where the fluid to be sealed and/or the components of the mechanical seal such as the seal case become abnormally high temperature due to an unexpected trouble that causes the O-ring to be heated above the heat resistance temperature. By activating the emergency seal, it is possible to reliably prevent the O-ring from being damaged by heating, and to avoid the occurrence of a major accident such as a large amount of leakage from the secondary seal portion due to the O-ring. It is.

1 is a sectional view showing an example of a shaft sealing device according to the present invention; FIG. FIG. 2 is a detailed view showing an enlarged main part of FIG. 1; FIG. 3 is a detailed view showing an enlarged main part of FIG. 2; FIG. 3 is a cross-sectional view of a main part corresponding to FIG. 2, showing a modification of the shaft sealing device according to the present invention; FIG. 3 is a cross-sectional view of a main part corresponding to FIG. 2 showing another modification of the shaft sealing device according to the present invention; FIG. 5 is a cross-sectional view showing still another modification of the shaft sealing device according to the present invention; FIG. 7 is a detailed view showing an enlarged main part of FIG. 6; FIG. 3 is a cross-sectional view of a main part corresponding to FIG. 2, showing still another modification of the shaft sealing device according to the present invention;

Hereinafter, the configuration of the shaft sealing device according to the present invention will be specifically described with reference to the drawings.

FIG. 1 is a cross-sectional view showing an example of a shaft sealing device according to the present invention, FIG. 2 is a detail view showing an enlarged main part of FIG. 1, and FIG. FIG. 3(b) shows the operating state of the emergency seal, and FIG. 3 is a detailed view showing an enlarged main part of FIG. 2(b).

The shaft sealing device shown in FIG. 1 (hereinafter referred to as "first shaft sealing device") is a housing (not shown) of a rotating device (boiler feed pump, boiler circulation pump, hot oil pump, etc.) and a housing (not shown) that penetrates and rotates. It is composed of one mechanical seal M incorporated between the rotating shaft of the horizontal rotating equipment protruding outside the equipment.

The mechanical seal M, as shown in FIG. 3 and a shaft-side seal ring 4 provided on the rotary shaft 1, and the seal end faces 3a, 4a, which are the opposite end faces of both the seal rings 3, 4, are in relative rotational sliding contact with each other, so that the inside of the rotary device is It is an end face contact type mechanical seal configured to partition the area A and the outside area B and seal (primary seal) the sealed fluid F (see FIG. 2(b)) in the inside area A. In this example, the sealed fluid F is a liquid, and the external area B is an atmospheric area. In the following description, front and rear refer to left and right in FIGS. 1 and 2 .

The seal case 2 is a metal cylindrical structure attached to the housing of the rotating device in such a manner that the rotating shaft 1 is concentric and penetrates in the left-right direction, and the first case body 21 is attached to the housing. and a second case body 22 and a third case body 23 attached thereto. As shown in FIG. 1, the first case body 21 includes a tip end side holding portion 21a having an inner diameter larger than the outer diameter of the rotating shaft 1, and a leading end side holding portion 21a connected thereto and extending in the direction of the outside area B (forward). An intermediate holding portion 21b that is larger than the tip end side holding portion 21a, a base end side holding portion 21c that extends in the direction of the outer region B and is connected to the intermediate holding portion 21b and that has an inner diameter larger than that of the intermediate holding portion 21b, and an intermediate holding portion 21c that is connected to the intermediate holding portion 21c. A first mounting portion 21d extending in the direction of the outer region B and having an inner diameter larger than that of the proximal end side holding portion 21c and a distal end side holding portion 21a extending in the direction of the in-machine region A (rearward) to support the rotating device. It is a cylindrical integral structure consisting of a housing attachment portion (not shown) attached to the housing. As shown in FIG. 1, the second case body 22 includes a second mounting portion 22a having an inner diameter substantially the same as that of the first mounting portion 21d of the first case body 21, and a second mounting portion 22a extending in the direction of the outside area B in a continuous manner. It is a cylindrical integral structure composed of an outer side holding portion 22b with an inner diameter smaller than that of the second mounting portion 22a. It is connected to the first case body 21 . An O-ring 5a is mounted on the connecting portion between the first case body 21 and the second case body 22 . As shown in FIGS. 1 and 2, the third case body 23 is a spring receiving plate attached to the proximal side holding portion 21c of the first case body 21 in a state facing the intermediate holding portion 21b of the first case body 21. 23a and an elastic seal ring receiving plate 23b having an L-shaped cross section attached to the spring receiving plate 23a so as to form a downwardly opening annular recess between the inner peripheral portion of the spring receiving plate 23a. It is a toroid.

As shown in FIG. 1, the case-side seal ring 3 has a front end face (rear end face) formed on a sealing end face 3a which is a smooth annular plane perpendicular to the axial direction of the rotating shaft 1 (hereinafter simply referred to as the "axial direction"). It is an annular body and is fixed to the inner peripheral portion of the outside holding portion 22b of the second case body 22 via O-rings 5b and 5c.

As shown in FIG. 1, the shaft-side seal ring 4 is an annular body whose tip end surface (front end surface) is formed on a sealing end surface 4a that is a smooth annular plane perpendicular to the axial direction. They are held on the rotating shaft 1 via a metal sleeve 41, a retaining ring 42, a spring receiving body 43 and a spring retaining body 44, respectively, in a state directly opposed to the sealing end face 3a of the ring 3. As shown in FIG. The seal rings 3 and 4 are made of a general seal ring material (for example, carbon, ceramics such as silicon carbide, cemented carbide, etc.).

The sleeve 41 has its front end (rear end) located inside the first mounting portion 21 d of the seal case 2 and its base end (front end) located outside the seal case 2 . It is a cylindrical body fixed to the rotating shaft 1 by detachably attaching it to the rotating shaft 1 with screws 46 and 47 . The retaining ring 42 is an annular body with the shaft-side seal ring 4 fixed to its tip (front end), and is fitted to the sleeve 41 via an O-ring 5d so that the shaft-side seal ring 4 is attached to the sleeve 41, that is, to the sleeve 41. It is held by the rotary shaft 1 so as to be movable in the axial direction. The spring receiver 43 is an annular plate connected to the retaining ring 42 by a drive pin 48 so as not to rotate relative to it. The spring retainer 44 is fixed to the tip of the sleeve 41, and by engaging a drive pin (not shown) provided on the spring receiver 43, the shaft-side seal ring 4 is held between the retainer ring 42 and the spring receiver. The body 43 holds the sleeve 41 , that is, the rotary shaft 1 , so as to allow axial movement within a predetermined range so as not to rotate relative to the rotary shaft 1 .

Thus, the shaft-side seal ring 4 is brought into a state in which the sealing end surface 4a is pressed against the sealing end surface 3a of the case-side seal ring 3 by the spring 6 interposed between the spring receiver 43 and the spring retainer 44. is energized.

Further, the seal case 2 is formed with liquid supply and drain passages 2a and 2b that open toward the seal rings 3 and 4 on the inner peripheral surface of the second mounting portion 22a of the second case body 22, and are shown in the drawing. A hollow cooling chamber (cooling jacket) is formed, and the sealing end surfaces 3a and 4a are in contact with each other and rotate relative to each other by flushing the cooling liquid C from the liquid supply passage 2a and circulating and supplying it to the cooling jacket. Mechanical seal components such as the seal rings 3 and 4 and the seal case 2 that constitute the mechanical seal M are required due to the frictional heat generated by the heat transfer from the sealed fluid F and the heat transfer from the sealed fluid F when the temperature is high. It prevents overheating.

By the way, between the mechanical seal constituent members constituting the mechanical seal M (between the first case body 21 and the second case body 22, between the case side seal ring 3 and the second case body 22, between the rotating shaft 1 and the sleeve 41 and between the sleeve 41 and the retaining ring 42) are loaded with the O-rings 5a to 5d as described above to seal (secondary seal) the seal constituent members. In this example, since the temperature of the mechanical seal constituent members does not become excessively high due to the cooling means such as the above-mentioned flushing means, these O-rings 5a to 5d are made of an elastic material that does not have a high degree of heat resistance. is used. Specifically, as the O-rings 5a to 5d, general rubber O-rings having a heat resistance temperature of about 100 to 150° C. are used as in the shaft sealing device described at the beginning.

In the first shaft sealing device constructed as described above, the following emergency seal m is arranged on the side (rear side) of the mechanical seal M on the machine interior region A side.

That is, as shown in FIGS. 1 and 2, the emergency seal m includes a stationary seal ring 7 fixed to the rotary shaft 1 and a movable sealing end surface 8a of the seal case 2, which is an end surface of the stationary seal ring 7. The sealing position (position shown in FIG. 2(b)) where the sealed fluid F is sealed by coming into contact with the fixed sealing end face 7a which is the end face of the non-sealing position (FIG. 1) where the movable sealing end face 8a is separated from the fixed sealing end face 7a. and the position shown in FIG. 2( a )), and a movable sealing ring 8 which is held movably in the axial direction and which is forcibly moved from the non-sealing position to the sealing position. A ring moving means 9, a movable seal ring holding means 10 for holding the movable seal ring 8 at the non-sealing position, and a low melting point that melts at a predetermined temperature to trigger a forced movement function by the movable seal ring moving means 9. When the movable seal ring 8 is positioned at the sealing position, the movable seal end surface 8a and the fixed seal end surface 7a of the fixed seal ring 7 are brought into relative rotational sliding contact with each other, thereby causing the relative rotation. A mechanical seal side in-machine region (the in-machine region A between the mechanical seal M and the emergency seal m) A1, which is an outer region of the sliding contact portions 7a and 8a, and a rotary device side in-machine region which is an inner circumferential region thereof. (In-machine region A between emergency seal m and rotating equipment) A2 is shielded and sealed. The predetermined temperature at which the low-melting-point member 11 melts is, for example, a temperature close to the heat-resistant temperature of the O-rings 5a to 5d and not higher than the heat-resistant temperature, as will be described later.

As shown in FIGS. 1 and 2, the stationary seal ring 7 is an annular body fixed to the rotating shaft 1, and has a front end surface (rear end surface) on a stationary seal end surface 7a which is a smooth annular plane perpendicular to the axial direction. An elastic seal ring 12a is mounted between the peripheral surfaces facing the rotary shaft 1. As shown in FIG. In this example, the stationary seal ring 7 is also configured with a sleeve 41 which is a member constituting a mechanical seal fixed to the rotating shaft 1 . That is, as shown in FIGS. 1 and 2, the stationary seal ring 7 is composed of a front end (rear end) 71 of the sleeve 41 and a sealing end face forming ring 72 having an L-shaped cross section attached thereto. The front end face (rear end face) of the end face forming ring 72 is formed on the fixed sealing end face 7a which is a smooth annular plane orthogonal to the axial direction. The sealing end face forming ring 72 is made of a metal material (for example, the same metal material as the sleeve 41), and a ceramic layer (not shown) such as chromium oxide is formed on the fixed sealing end face 7a. As will be described later, the elastic seal ring 12a is loaded in a seal ring loading space 13a formed between the opposing circumferential surfaces of the stationary seal ring 7 and the rotary shaft 1. As shown in FIG.

The movable seal ring 8, as shown in FIGS. A sealed end surface forming portion 82 having a smaller diameter than the first held portion 81 and extending in the direction of the external region B (forward) from the first held portion 81, a second held portion 83 extending from the first held portion 81 in the in-machine region A direction (rearward); 83 and a third held portion 84 extending in the direction of the in-machine region A, and has a constant inner diameter. .

That is, as shown in FIG. 2, the movable sealing ring 8 is formed by forming the end face (front end face) of the sealing end face forming portion 82 into a movable sealing end face 8a which is a smooth annular plane orthogonal to the axial direction. 8a is directly opposed to the fixed sealing end face 7a, and the third held portion 84 is brought close to the inner peripheral portion of the tip side holding portion 21a of the first case body 21 of the seal case 2. Then, the sealing end face forming portion 82 is The base end of the first case body 21 of the seal case 2 is held via the elastic seal ring 12c by placing the first held portion 81 on the inner peripheral portion of the third case body 23 of the seal case 2 via the elastic seal ring 12b. By fitting the inner peripheral portion of the portion 21c and the third held portion 84 to the inner peripheral portion of the intermediate holding portion 21b of the first case body 21 via the elastic seal ring 12d, respectively, the seal case 2 is formed. are held by the first and third case bodies 21 and 23 so as to be movable in the axial direction between the sealing position and the non-sealing position. The movable seal ring 8 is made of a metal material (for example, the same metal material as the stationary seal ring 7). ) is formed. As shown in FIG. 1, the movable seal ring 8 is configured by engaging the drive pin 85 attached to the spring receiving plate 23a of the third case body 23 with the concave portion 81a formed in the first held portion 81. It is prevented from rotating relative to the seal case 2 while allowing axial movement between the sealing and non-sealing positions.

By the way, the elastic seal ring 12a that seals between the stationary seal ring 7 and the rotating shaft 1 and the elastic seal rings 12b to 12d that seal between the movable seal ring 8 and the seal case 2 are more likely than the O-rings 5a to 5d. It is a highly heat-resistant sealing member with high heat resistance. That is, as shown in FIG. 3, the elastic seal ring 12a includes an annular main body portion 12e, cylindrical inner and outer peripheral lip portions 12f and 12g projecting axially from the main body portion 12e, main body portion 12e and the inner and outer peripheral lip portions. It is a composite structure having a U-shaped cross section and an annular leaf spring 12i having a U-shaped cross section and filled in an annular groove 12h surrounded by the portions 12f and 12g. It is made of a heat-resistant elastic material (e.g., a fluororesin such as polytetrafluoroethylene or an elastic composite material obtained by blending this with a filler such as glass fiber or carbon fiber) and has high heat resistance. As shown in FIG. 3, the elastic seal ring 12a has an annular concave portion formed in the inner peripheral surface of the connection between the distal end portion 71 of the sleeve 41 constituting the stationary seal ring 7 and the sealing end surface forming ring 72, and The annular seal ring loading space 13a closed by the surface is loaded in such a state that the fluid to be sealed (sealed fluid F) can enter the annular groove 12h. 12e is the bottom surface 7b of the seal ring loading space 13a (the end surface of the annular recess formed in the inner peripheral portion of the stationary seal ring 7 on the outside area B side), and the inner peripheral lip portion 12f is the seal ring loading space 13a. The inner peripheral surface 1a (the outer peripheral surface of the rotary shaft 1), and the outer peripheral lip portion 12g is formed on the outer peripheral surface 7c of the seal ring loading space 13a (the outer peripheral surface of the annular recess formed in the inner peripheral portion of the stationary seal ring 7). , respectively, seal between the stationary seal ring 7 and the rotating shaft 1 by being pressed. Also, the elastic seal rings 12b to 12d other than the elastic seal ring 12a have the same structure and the same function as the elastic seal ring 12a, except that they have different diameters. Similar to the elastic seal ring 12a, as shown in FIGS. 1 and 2, the elastic seal ring 12b is a circle formed between the opposing peripheral surfaces of the sealing end surface forming portion 82 of the movable seal ring 8 and the third case body 23. The elastic seal ring 12 c is loaded in the annular seal ring loading space 13 b to seal between the two members 23 and 82 . The elastic seal ring 12d is loaded in an annular seal ring loading space 13c formed between the opposing peripheral surfaces of the side holding portion 21c and seals between the two members 21c and 81. It is loaded into an annular seal ring loading space 13d formed between the facing peripheral surfaces of the third held portion 84 and the intermediate holding portion 21b of the first case body 21 to seal between the two members 21b and 84. is. In addition, the elastic seal rings 12a to 12d are not limited to the above-described composite structure, as long as they are superior in heat resistance to the O-rings 5a to 5d for secondary sealing between the members constituting the mechanical seal. A heat-resistant O-ring, a metal O-ring, or the like can be used.

As shown in FIG. 2, the movable seal ring moving means 9 includes a closed back pressure chamber 9a formed between the seal case 2 and the movable seal ring 8, and a movable pressure chamber 9a. It comprises a high-pressure fluid for moving the seal ring 8 from the non-sealing position to the sealing position, and a communication passage 9b for communicating the supply source of the high-pressure fluid with the back pressure chamber 9a. By supplying the pressure to 9a, the pressure forces the movable seal ring 8 to move to the sealing position.

As shown in FIG. 2, the back pressure chamber 9a consists of the first held portion 81 and the second held portion 83 of the movable seal ring 8, the intermediate holding portion 21b of the first case body 21 of the seal case 1, and the proximal holding portion. The space surrounded by the portion 21c is a closed space sealed by the elastic seal rings 12c and 12d. 2, the space 10a surrounded by the movable seal ring 8, the proximal side holding portion 21c of the first case body 21, and the spring receiving plate 23a of the third case body 23 is A metal gasket (for example, a spiral gasket using a metal hoop) 12j loaded at the joint between 21c and the spring receiving plate 23a and a closed atmospheric space sealed by the elastic seal rings 12b and 12c. The chamber 9a and the sealed fluid area A are separated.

As shown in FIG. 2, the communicating passage 9b is a through hole radially penetrating the boundary portion between the first held portion 81 and the second held portion 83 of the movable seal ring 8, and is connected to the back pressure chamber 9a. It is configured to communicate with the in-machine region A so that the sealed fluid F in the in-machine region A can be supplied to the back pressure chamber 9a. That is, in this example, the sealed fluid F in the in-machine area A (the rotating equipment side in-machine area A2) is used as the high-pressure fluid to be supplied to the back pressure chamber 9a, and the supply source of the high-pressure fluid F is the in-machine area A (rotating The device-side in-machine area A2) is used.

According to the movable seal ring moving means 9, when the sealed fluid F is supplied from the communication passage 9b to the back pressure chamber 9a, the pressure of the sealed fluid F pushes the movable seal ring 8 to a spring 10, which will be described later. 2(a) from the non-sealing position shown in FIG. 2(a) to the sealing position shown in FIG. 2(b).

The movable seal ring holding means 10 is composed of a spring arranged in the space 10a and loaded between the seal case 2 and the movable seal ring 8, as shown in FIG. The spring 10 is loaded between the spring receiving plate 23a of the third case body 23 of the seal case 2 and the first held portion 81 of the movable seal ring 8, as shown in FIG. The ring 8 is biased toward the unsealed position. In this example, an annular bulging portion 81 b is formed on the inner peripheral side portion of the back surface (rear end surface) of the first held portion 81 of the movable seal ring 8 , so that the movable seal ring 8 receives the biasing force of the spring 10 . As a result, the bulging portion 81b is pressed against the intermediate holding portion 21b of the first case body 21 of the seal case 2, and the movable sealing end face 8a is held at the non-sealing position away from the fixed sealing end face 7a. ing.

As shown in FIG. 2(a), the low-melting-point member 11 is configured as a plug loaded in the communicating passage 9b in a state of closing the communicating passage 9b, and is close to the heat-resistant temperature of the O-rings 5a to 5d. It is a solid member that melts at a temperature that is equal to or lower than the heat resistance temperature (hereinafter referred to as "heat damage prediction temperature"), and is composed of a low-melting material whose melting point is the heat damage prediction temperature.

The plug 11 is entirely made of a low-melting-point member, and under a temperature condition below the thermal damage prediction temperature, the plug 11 blocks the communication passage 9b against the pressure of the high-pressure fluid (sealed fluid) F. It is a solid with sufficient strength, and under a temperature condition equal to or higher than the temperature for predicting thermal damage, the entire portion of the plug 11 melts to open the communication passage 9b, or a portion of the plug 11 melts. The pressure of the high-pressure fluid F is eliminated from the communication passage 9b. When the plug body 11 or a portion thereof melts and the communication passage 9b is opened, the sealed fluid F is supplied from the communication passage 9b to the back pressure chamber 9a, and the movable seal ring 8 resists the biasing force of the spring 10. is forced to the sealing position. That is, the forced movement function by the movable seal ring moving means 9 is activated. As the low-melting-point material constituting the plug body 11, a metal, an alloy, a thermoplastic resin, or the like having a melting point slightly lower than the heat-resistant temperature (thermal damage prediction temperature) is used according to the heat-resistant temperature of the O-rings 5a to 5d. be. In this example, the plug 11 is made of a Bi--Sn or Sn--In lead-free solder having a melting point (thermal damage prediction temperature) of about 110 to 140.degree.

In the first shaft sealing device described above, as shown in FIG. By engaging an appropriate number of set plates 14, the assembled state of the mechanical seal M and the emergency seal m, that is, the assembled state of the first shaft seal device, can be incorporated into and removed from the rotating equipment. devised. Therefore, when the emergency seal m is activated due to trouble with the flushing means, that is, when the plug body 11 melts and the movable seal ring 8 moves to the sealing position, after the trouble is resolved, Remove the mechanical seal M and the emergency seal m from the rotating equipment, restore the emergency seal m to a non-operating state with a new stopper 11 loaded, and then rotate the mechanical seal M and the emergency seal m again. A series of maintenance work such as incorporation into equipment can be performed very easily and efficiently.

By the way, as described at the beginning, if an unexpected trouble occurs in the rotating equipment equipped with the first shaft sealing device, the flushing means due to the cooling liquid C, or the cooling jacket, the sealed fluid F, the seal case 2, etc. When the mechanical seal constituent members reach an unexpectedly high temperature, the O-rings 5a to 5d, which provide a secondary seal between the mechanical seal constituent members, may be damaged by contact with the sealed fluid F or the O-rings 5a to 5d. There is a risk that the mechanical seal will be heated to a heat resistance temperature or higher due to heat transfer from the mechanical seal constituent member with which the mechanical seal is in contact, and will be damaged by heating. On the other hand, mechanical seal constituent members such as the seal rings 3 and 4 made of carbon material, metal material, etc. may be damaged by heating even in an abnormally high temperature condition in which the O-rings 5a to 5d described above are damaged by heating. Therefore, the primary sealing function of the mechanical seal M (sealing function by the relative rotational sliding contact action between the sealing end face 3a of the case-side seal ring 3 and the sealing end face 4a of the shaft-side seal ring 4) is maintained as it is. . However, even if the primary sealing function is maintained in this way, if the O-rings 5a to 5d are damaged by heating, the secondary sealing function of the O-rings 5a to 5d is impaired, resulting in a mechanical seal structure that is a secondary seal portion. A large amount of the sealed fluid F leaks to the outside area B from between the members, causing a serious accident.

However, according to the first shaft sealing device, even in a situation where the O-rings 5a to 5d are in an abnormally high temperature state such that the O-rings 5a to 5d are damaged by heating, the situation is detected in advance and the emergency seal m is activated. It is possible to reliably prevent the O-rings 5a to 5d from being damaged by heating, thereby avoiding the occurrence of a major accident such as a large amount of sealed fluid F leaking from the secondary seal portion of the mechanical seal M to the external area B. .

That is, for example, under a non-high-temperature condition in which the O-rings 5a to 5d are not damaged by heating even if the temperature of the sealed fluid F comes into contact with it, that is, under a condition where the sealed fluid F does not reach the temperature for predicting thermal damage. 2(a), since the plug 11 is not melted, the forced movement function of the movable seal ring moving means 9 is not activated and the emergency seal m is not activated. Also, the O-rings 5a to 5d of the mechanical seal M are not damaged by heating. Therefore, under normal temperature conditions in which the temperature of the sealed fluid F does not reach the thermal damage prediction temperature, the mechanical seal side internal region A1 and the rotating device side internal region A2 communicate with each other, and the sealed fluid F reaches the mechanical seal. Primary sealing is performed by M, and secondary sealing is performed by O-rings 5a to 5d, so that a proper shaft sealing function can be exhibited in the same manner as a shaft sealing device without an emergency seal m. That is, the emergency seal m does not interfere with the normal shaft sealing function.

On the other hand, in a situation where the sealed fluid F reaches an abnormally high temperature (a temperature higher than the heat resistance temperature of the O-rings 5a to 5d) such that the O-rings 5a to 5d are damaged by heating due to contact with the sealed fluid F, the sealed fluid F When the temperature reaches the heating damage prediction temperature, the plug 11 melts and the communication passage 9b is opened, and the sealed fluid F is supplied from the communication passage 9b to the back pressure chamber 9a.

Thus, when the sealed fluid F is supplied to the back pressure chamber 9a, the emergency seal m is actuated by its pressure. That is, as shown in FIG. 2(b), the pressure of the sealed fluid F supplied to the back pressure chamber 9a pushes the movable seal ring 8 toward the fixed seal ring 7 against the biasing force of the spring 10. The movable sealing end face 8a comes into contact with the fixed sealing end face 7a, and the relative rotational sliding action of both sealing end faces 7a, 8a exhibits the same sealing function as a general end face contact type mechanical seal. This prevents the high-temperature sealed fluid F from flowing into the mechanical seal side internal area A1 from the rotary equipment side internal area A2.

Therefore, when the temperature of the sealed fluid F in the rotating device-side internal region A2 reaches the melting point of the plug 11, that is, when the temperature is near the heat-resistant temperature of the O-rings 5a-5d, the O-rings 5a-5d When 5d reaches the temperature at which heat damage has not yet occurred (heat damage prediction temperature), the emergency seal m prevents entry into the mechanical seal side internal region A1, so that the rotary device side internal region A2 is covered. Even when the temperature of the sealed fluid F rises above the heat damage prediction temperature and reaches a temperature higher than the heat resistant temperature of the O-rings 5a to 5d, the temperature of the sealed fluid F in the mechanical seal side machine internal region A1 does not exceed the heat resistant temperature. Since the O-rings 5a to 5d are kept at a lower temperature than the temperature, the O-rings 5a to 5d are not damaged by heating due to contact with the sealed fluid F in the mechanical seal side internal area A1.

By the way, if the temperature of the sealed fluid F continues to rise and exceeds the thermal damage prediction temperature in the rotating equipment side internal region A2, contact with the sealed fluid F causes the temperature of the seal case 2 to drop to the O-ring 5a. There is a risk of being heated above the heat-resistant temperature of ~5d. In such a case, there is a risk that the O-rings 5a to 5d will be heated to a temperature higher than their heat resistance temperature due to heat transfer from the seal case 2 directly or indirectly from the mechanical seal constituent members in contact with the seal case 2. be.

However, the sealed fluid F coming into contact with the O-rings 5a to 5d stays in the mechanical seal side area A1 isolated from the rotating equipment side area A2 by the emergency seal m. , that is, the pressure in the internal region A in a state in which the emergency seal m does not operate. On the other hand, heat damage of the O-rings 5a to 5d is caused by exposure to abnormally high temperatures above the heat resistance temperature under high pressure, and is not caused by exposure to abnormally high temperatures under low pressure. Therefore, the mechanical seal components with which the O-rings 5a-5d come into direct or indirect contact with the sealed fluid F in the rotating equipment-side internal region A2 are heated to a temperature higher than the heat-resistant temperature of the O-rings 5a-5d. Even if this is done, there is a risk that the O-rings 5a to 5d will be thermally damaged and cause a large amount of leakage from the secondary sealing portion until the work to deal with the high temperature of the sealed fluid F is completed. no.

Moreover, even if the temperature of the sealed fluid F does not rise, the mechanical seal constituent members may reach an abnormally high temperature higher than the heat resistance temperature of the O-rings 5a to 5d due to troubles in cooling means such as flushing means (such as power outages). However, in such a case, when the movable seal ring 8 is heated by heat transfer from the seal case 2 and reaches the temperature for predicting thermal damage, the plug closing the communication passage 9b formed in the movable seal ring 8 will As in the above case where the body 11 is melted and the emergency seal m is activated and the temperature of the sealed fluid F is increased, the O-rings 5a to 5d is not damaged by heating, the primary sealing function of the mechanical seal M and the secondary sealing function of the O-rings 5a to 5d are properly exerted, and a large amount of leakage to the outside area B does not occur. This point is the same when the temperature of the sealed fluid F is also increased, that is, when both the temperature of the sealed fluid F and the components of the mechanical seal is increased.

By the way, the elastic seal ring 12a mounted between the stationary seal ring 7 and the rotating shaft 1 and the elastic seal rings 12b to 12d mounted between the movable seal ring 8 and the seal case 2 (and the first case body 21 and the third case body 23, the metal gasket 12j) has a higher heat resistance than the O-rings 5a to 5d of the mechanical seal M, so the sealed fluid F and/or the seal case 2, etc. Even when the temperature of the mechanical seal constituent members rises above the heat resistance temperature of the O-rings 5a to 5d, there is no heat damage due to contact with the sealed fluid F and/or heat transfer from the seal case 2, and both sealing The primary sealing function of the rings 7 and 8 and the sealing function of sealing the back pressure chamber 9a (and the space 10a in which the spring 10 is loaded) are not impaired.

As described above, according to the first shaft sealing device, the temperature of the mechanical seal components such as the sealed fluid F and/or the seal case 2 may rise to a temperature higher than the heat-resistant temperature of the O-rings 5a to 5d due to an unexpected trouble. Under certain circumstances, this situation is detected in advance (when the plug 11 melts at the temperature at which it is predicted to be damaged by heating and the movable seal ring 8 is moved to the sealing position), and the emergency seal m is activated, so that the O-ring By reliably preventing 5a-5d from being damaged by heating, it is possible to avoid the occurrence of a major accident such as a large amount of leakage from the secondary sealing portion by the O-rings 5a-5d.

Incidentally, conventionally, as disclosed in Patent Document 2, for example, there has been proposed a shaft seal device configured to predict an abnormal temperature condition as described above by means of a temperature detection means of the fluid to be sealed. Since the temperature detection means is an electrical means that requires a power supply, it will not function in the event of an electrical trouble such as a power failure, and the cooling means such as the flushing means will not function due to an electrical trouble such as a power failure. It is useless under conditions where mechanical seal constituent members become abnormally high temperature due to However, since the emergency seal m of the first shaft sealing device described above is operated by melting the plug 11 and does not require a power supply, it can be properly operated even in the event of an electrical trouble such as a power failure. Function.

It should be noted that the shaft sealing device according to the present invention is not limited to the above-described embodiment, and can be improved and changed as appropriate without departing from the basic principle of the present invention.

For example, in the first shaft sealing device, the communicating passage 9b for the emergency seal m is formed in the movable seal ring 8, but the communicating passage 9c can also be formed in the seal case 2 as shown in FIG. That is, in the emergency seal m of the shaft sealing device (hereinafter referred to as the "second shaft sealing device") shown in FIG. A through hole passing through the holding portion 21c is formed to allow communication between the back pressure chamber 9a and the rotary device-side internal region A2. A plug 11 is tightly packed. If the communication passage 9c is formed in the seal case 2 in this way, heat is transferred to the plug 11 from both the sealed fluid F and the seal case 2. When the heat damage prediction temperature is reached, the stopper 11 is eluted and the communication passage 9c is opened. Therefore, the emergency seal m operates in both situations in which the fluid to be sealed F becomes abnormally hot due to trouble on the side of the rotating equipment and in the situation where mechanical seal constituent members such as the seal case 2 become abnormally hot due to trouble in the cooling means. do. The configuration and function of the emergency seal m shown in FIG. 4 and the second shaft sealing device having the same are the same as those of the first shaft sealing device shown in FIGS. 1 to 3 except for the above points. In FIG. 4, the same constituent members are denoted by the same reference numerals as in FIGS. 1 to 3, and the details thereof are omitted.

Further, in the movable seal ring moving means 9 of the emergency seal m in the first and second shaft sealing devices described above, the sealed fluid F is used as the high-pressure fluid to be supplied to the back pressure chamber 9a. Although the in-machine area A (the rotating equipment side in-machine area A2) is used as the supply source of the high-pressure fluid, the movable seal ring moving means 9 can also be configured as shown in FIG. That is, in the movable seal ring moving means 9 of the emergency seal m in the shaft sealing device (hereinafter referred to as the "third shaft sealing device") shown in FIG. The supply source of the high-pressure fluid is the storage tank 91 for the pressurized gas G, and the communication path 92 communicates the back pressure chamber 9a and the storage tank 91, and at least the back pressure chamber 9a side A plug body 11, which is a low-melting-point member that closes the communicating passage 92, is mounted in the communicating passage portion 92a formed in the seal case 2, and the seal It is melted by heat transfer from the case 2 . As shown in FIG. 5(a), the communicating passage portion 92a is formed in the boundary portion between the distal end side holding portion 21c and the intermediate holding portion 21b in the first seal case 21 of the seal case 2, and is connected to the back pressure chamber 9. A plug 11, which is a low-melting-point member, is tightly attached to the opening. Therefore, in the case of the emergency seal m shown in FIG. When the seal case 2 reaches the temperature for predicting thermal damage due to trouble with the cooling means such as the flushing means, the plug 11 melts due to heat transfer from the seal case 2, the communication passage 92 is opened, and the back pressure from the storage tank 91 is released. A high-pressure gas G is supplied to the chamber 9a, and the pressure of the high-pressure gas G moves the movable seal ring 8 against the spring 10 from the non-sealing position (shown in FIG. 1(a)) to the non-sealing position (shown in FIG. 1(b)). ), shielding and sealing the mechanical-seal-side internal region A1 and the rotating device-side internal region A2 by the relative rotational sliding contact action between the fixed sealing end face 7a and the movable sealing end face 8a. The configuration and function of the emergency seal m shown in FIG. 5 and the third shaft sealing device including the same are the same as those of the first shaft sealing device shown in FIGS. In FIG. 5, the same constituent members are denoted by the same reference numerals as in FIGS. 1 to 3, and the details thereof are omitted.

Further, when the shaft sealing device is composed of one mechanical seal M, the type and configuration of the mechanical seal M are arbitrary. For example, the shaft sealing device shown in FIG. ), a floating ring-shaped mechanical seal is used as the mechanical seal M. Similar to the above-described first to third shaft devices, the mechanical seal configuration can be changed by providing an emergency seal m. It is possible to prevent an O-ring loaded between members from being damaged by heating.

6 is a cross-sectional view showing the fourth shaft seal device, FIG. 7 is a detailed view of the essential parts thereof, FIG. (b) The figure shows the operating state of the emergency seal m.

In the fourth shaft sealing device, the mechanical seal M comprises, as shown in FIG. The internal region A and the external region (atmospheric region) B are partitioned by the relative rotational sliding action of the sealing end faces 103a and 104a, which are the end faces facing the rotating ring 104, which is the side sealing ring, so that the internal region A is sealed. It is a floating annular mechanical seal configured to seal (primary seal) the liquid that is the fluid F (see FIG. 7(b)). In the following description, front and rear refer to left and right in FIGS. 6 and 7. FIG.

As shown in FIG. 6, the seal case 102 consists of a first case body 102a attached to a housing (not shown) of rotating equipment such as a boiler feed pump, and a second case body attached thereto via an O-ring 105a. a body 102b, a third case body 102c attached to the first case body 102a, a fourth case body 102d attached to the inner peripheral portion of the second case body 102b via an O-ring 105b, and the first case body 102a via an O-ring 105c and a fifth case body 102e mounted via the O-rings 105b to the second and fourth case bodies 102b and 102d. The first case body 102a and the third case body 102c have the same structure as the first case body 21 and the third case body 23 of the seal case 2 shown in FIG. 1, respectively. In FIG. 7, the same reference numerals as in FIG. 1 are used to omit the details of the configuration of these case bodies 102a and 102c.

The floating ring 103 is an annular body having a through hole 103b, as shown in FIG. 114 are connected so as not to rotate relative to each other. The retaining ring 113 is a metal member held by the fourth case body 102d via an O-ring 105e and a drive pin 115 so as to be movable in the axial direction of the rotating shaft 101 (hereinafter simply referred to as the "axial direction") and to be relatively unrotatable. It is an annular body made of metal, and is pressed and energized in the machine interior region A direction (forward) by a spring 106 inserted between it and the second case body 102d. Therefore, the floating ring 103 is held by the seal case 102 so as to be movable in the axial direction while being in pressure contact with the rotating ring 104 to be described later via the holding ring 113 .

As shown in FIG. 6, the rotating ring 104 is an annular body arranged on the in-machine region A side of the floating ring 103 and fixed to a sleeve 141 fitted to the rotating shaft 101 . The sleeve 141 is a metal cylindrical body fixed to the rotary shaft 101 by detachably attaching the base end (front end) located outside the seal case 102 with a fixed ring 145, a set screw 146 and a key 147. be. An outwardly extending annular portion 141a having an L-shaped cross section is integrally formed at the tip (rear end) of the sleeve 141, and the rotary ring 104 is fixed to the annular portion 141a via an O-ring 105f. .

The opposing end faces of the floating ring 103 and the rotary ring 104 are formed as sealing end faces 103a and 104a, which are smooth annular planes perpendicular to the axial direction. Like the seal rings 3 and 4, they are made of the seal ring material described above.

The seal case 102 is provided with supply and discharge passages 102f and 102g for flushing the cooling liquid C and a cooling jacket (not shown) for circulating and supplying the cooling liquid. Mechanical seal constituent members such as the seal rings 103 and 104 and the seal case 102 that constitute the mechanical seal M due to frictional heat generated by this and heat transfer from the sealed fluid F when the temperature of the sealed fluid F is high. prevents the temperature from becoming unnecessarily high. The annular portion 141a of the sleeve 141 is configured as a pumping body in which a plurality of grooves 141b are arranged in parallel in the circumferential direction of the annular portion 141a. C is pumped to drain 102g.

As described above, the O-rings 105a to 105f are mounted between the mechanical seal members forming the mechanical seal M to seal (secondary seal) the seal members. As with the shaft seal device, the above-described flushing means and cooling jacket prevent the mechanical seal components from becoming hotter than necessary. , general rubber O-rings with a heat resistance temperature of about 100 to 150°C are used.

As shown in FIGS. 6 and 7, the fourth shaft sealing device has an emergency seal m disposed on the machine interior region A side (rear side) of the mechanical seal M, and is connected to the first shaft sealing device. Similarly, when an abnormal situation occurs in which the temperature of the mechanical seal constituent members or the sealed fluid F becomes higher than the heat resistance temperature of the O-rings 105a to 105f, the emergency seal m operates and the O-ring 105a It is configured so as to prevent heat damage at 105f and maintain the shaft sealing function of the shaft sealing device in good condition.

In the emergency seal m of the fourth shaft seal device, as shown in FIGS. That is, as shown in FIGS. 6 and 7, the stationary seal ring 7 is attached to an inner peripheral side portion 171 at the front end (rear end) of an annular portion (pumping body) 141a integrally formed with the sleeve 141. A sealing end face forming ring 172 having an L-shaped cross section is formed on the fixed sealing end face 107a, which is a smooth annular plane perpendicular to the axial direction. The sealing end surface forming ring 172 is made of a metal material (for example, the same metal material as the sleeve 141), and a ceramic layer (not shown) such as chromium oxide is formed on the fixed sealing end surface 107a. As in the first shaft sealing device, an elastic seal ring 12a is loaded in a seal ring loading space 13a formed between the opposed circumferential surfaces of the stationary seal ring 107 and the rotating shaft 101. As shown in FIG.

Except for the above points, the emergency seal m of the fourth shaft sealing device has the same structure and functions as the emergency seal m of the first shaft sealing device shown in FIGS. It is intended to demonstrate That is, when a trouble occurs in the rotating equipment equipped with the fourth shaft sealing device or in the cooling means (for example, the rotating shaft 101 stops, the pumping function of the pumping body 141a stops, and the cooling function by flushing stops). ), the sealed fluid F and/or the seal case 102 reaches the temperature for predicting thermal damage (a temperature near the heat resistance temperature of the O-rings 105a to 105f and below the heat resistance temperature). In this case, the emergency seal m is activated to prevent the O-rings 105a-105f from being damaged by heating.

Therefore, the configuration and function of the fourth shaft sealing device including the emergency seal m are the same as those of the first shaft sealing device except for the above points. The same reference numerals as those shown in FIGS. 1 to 3 are given to the same constituent members as those shown in FIGS. 1 to 3, and the details thereof are omitted. Also in the fourth shaft sealing device, as shown in FIG. 6, the annular groove 141c formed in the proximal end of the sleeve 141 and the second case body 102b of the seal case 102 are arranged in the same manner as in the first shaft sealing device. By engaging a suitable number of set plates 116, the mechanical seal M and the emergency seal m are devised so that they can be incorporated into and removed from rotating equipment in an assembled state. Also in the fourth shaft sealing device, the emergency seal m has the same structure as the emergency seal m of the second shaft sealing device 3 shown in FIG. 4 or the emergency seal m shown in FIG. be able to.

Further, in the first to fourth shaft sealing devices, the stationary seal rings 7, 107 are also configured by the mechanical seal constituent members 41, 141 fixed to the rotary shaft 1, 101, and the parts 71, 171 thereof are fixed. The movable seal ring 8 is used as a constituent part of the seal rings 7 and 107, and the pressure of the high-pressure fluid (sealed fluid F or high-pressure gas G) forces the movable seal ring 8 to the sealing position to operate the emergency seal m. However, for example, as shown in FIG. 8, the stationary seal ring 207 is fixed to the rotary shaft 201 as an independent member instead of being used as a mechanical seal component, and the operation of the emergency seal m is controlled by such a high pressure fluid. It is also possible to configure the actuation by mechanical means without using pressure.

That is, in the shaft sealing device shown in FIG. 8 (hereinafter referred to as “fifth shaft sealing device”), the seal case 202 is composed of a first case portion 221 in which the mechanical seal M is provided, and an in-machine area A connected to this. and a third case connected to the second case portion 222 via an O-ring 205a and extending in the direction of the in-machine region A and attached to the housing (not shown) of the rotary device. and a fourth case portion 224 attached to the inner peripheral portion of the third case portion 223 via an elastic seal ring 212a. The emergency seal m is composed of a fixed seal ring 207, a movable seal ring 208, a movable seal ring moving means 209, a movable seal ring holding means 210 and a low melting point member 211 as follows. . The seal case 202 is provided with cooling means (not shown) such as flushing means, like the first or fourth shaft sealing device. In addition, O-rings (not shown) made of the same elastic material as the O-rings 5a to 5d and 105a to 105f, including the O-ring 205a, are mounted between the mechanical seal members constituting the mechanical seal M. ing.

That is, the stationary seal ring 207 is an annular body made of a metal material independent of the mechanical seal components, and consists of a retaining ring 271 fixed to the rotating shaft 201 and a sealing end face forming ring 272 attached thereto. An elastic seal ring 212b is mounted between the opposed peripheral surfaces of the stationary seal ring 207 and the rotating shaft 201. As shown in FIG. The movable seal ring 208 is an annular body made of a metal material (for example, the same metal material as the stationary seal ring 207), and is axially movable in the fourth case portion 224 of the seal case 202 via an elastic seal ring 212c. retained as possible. The opposing end faces of the sealing end face forming ring 272 of the stationary sealing ring 207 and the movable sealing ring 208 are formed into a stationary sealing end face 207a and a movable sealing end face 208a, which are smooth annular planes orthogonal to the axial direction. A ceramic layer (not shown) such as chromium oxide is formed on each of the sealing end faces 207a and 208a in the same manner as the sealing end faces 7a and 8 described above. The elastic seal rings 212a to 212c have the same structure as the elastic seal rings 12a to 12d, and are superior in heat resistance to the O-rings (O-ring 205a, etc.) that seal between the members constituting the mechanical seal.

The movable seal ring moving means 209 is composed of a spring loaded between the fourth case portion 224 of the seal case 202 and the movable seal ring 208, and the movable seal ring 208 is moved as shown in FIG. 8(b). , the biasing force of the spring 209 causes the movable sealing end face 208a to move to the sealing position in contact with the fixed sealing end face 207a.

As shown in FIG. 8(a), the movable seal ring holding means 210 is composed of a connecting body that connects the movable seal ring 208 and the seal case 202, and holds the movable seal ring 8 against the biasing force of the spring 209. is held in the non-sealing position where the movable sealing end face 208a is separated from the fixed sealing end face 207a. In this example, at least a portion of the connecting member 210 is heated to a temperature at which predictive damage by heating (a temperature close to the heat-resistant temperature of an O-ring (O-ring 205a, etc.) that seals between mechanical seal components and not higher than the heat-resistant temperature). It is a rod-shaped body or rod-shaped body composed of a low-melting-point member 211 that melts at a temperature, and both ends are engaged, riveted, or welded to appropriate locations of the second case portion 222 of the seal case 202 and appropriate locations of the movable seal ring 208. The movable seal ring 208 is connected to the seal case 202 by connecting and fixing such as. That is, the movable seal ring 208 is connected to the seal case 202 by the connecting body 210 while being held at the non-sealing position against the biasing force of the spring 209 .

Therefore, in the fifth shaft seal device, the sealed fluid becomes abnormally hot beyond the heat resistance temperature of the O-ring 205a due to trouble on the side of the rotating equipment, and/or mechanical problems such as the seal case 202 due to trouble with the cooling means. When the fluid to be sealed, the seal case 202, or the movable seal ring 208 reaches the temperature for predicting thermal damage under the condition that the seal components become abnormally high temperature, the portion of the connecting body 210 composed of the low-melting-point member 11 melts. As a result, the function of holding the movable seal ring 208 in the non-sealing position by the coupling body 210 disappears (the connection between the movable seal ring 208 and the seale 202 is released), and the movable seal ring 208 is moved by the spring 9 to the non-sealing position. are forcibly moved to the sealing position, and the sealing end surfaces 207a and 208a come into contact with each other to separate and seal the mechanical seal side internal region A1 and the rotating device side internal region A2, as in the first to fourth shaft sealing devices. be. The connecting body 210 may be one that melts to release the connection between the seal case 202 and the movable seal ring 208 (lost the function of holding the movable seal ring 208 in the non-sealing position), and at least a portion thereof is lowered. What is necessary is just to be comprised by the melting|fusing point member 211. FIG. The configuration and function of the fifth shaft sealing device including the emergency seal m are the same as those of the first to fourth shaft sealing devices except for the points described above, so the details thereof will be omitted. .

In addition, the present invention is not limited to a shaft sealing device composed of one end face contact type mechanical seal M like the first to fifth shaft sealing devices, but is not limited to one non-contact type mechanical seal M. It can be applied to a shaft sealing device composed of seals, a double seal, a tandem seal, etc., in which a plurality of mechanical seals are arranged in series in the axial direction in the same manner as the first to fifth shaft sealing devices. and can achieve the same effect. In a shaft sealing device composed of a plurality of mechanical seals arranged in series in the axial direction, an emergency seal m is arranged on the innermost mechanical seal of these mechanical seals. I keep it.

1 Rotating shaft 2 Seal case 3 Case-side seal ring 4 Shaft-side seal ring 5a O-ring 5c O-ring 5d O-ring 7 Fixed seal ring 7a Fixed seal end face 8 Movable seal ring 8a Movable seal end face 9 Movable seal ring moving means 9a Back pressure Chamber 9b Communication path 9c Communication path 10 Movable seal ring retaining means (spring)
11 low melting point member (plug)
12a elastic seal ring 12b elastic seal ring 12c elastic seal ring 12d elastic seal ring 91 storage tank for high pressure gas (supply source of high pressure fluid)
92 Communicating path 92a Communicating path portion formed in seal case 101 Rotating shaft 102 Seal case 103 Case-side seal ring (floating ring)
104 Shaft-side seal ring (rotary ring)
105a O-ring 105b O-ring 105c O-ring 105d O-ring 105e O-ring 105f O-ring 107 Fixed ring 107a Fixed sealing end face 201 Rotating shaft 202 Seal case 205a O-ring 207 Fixed sealing ring 207a Fixed sealing end face 208 Movable sealing ring 208a Movable sealing end face 209 Movable seal ring moving means (spring)
210 Movable seal ring holding means (connector)
211 Low-melting-point member 212a Elastic seal ring 212b Elastic seal ring 212c Elastic seal ring A Internal region A2 Rotating device-side internal region (supply source of high-pressure fluid)
F Sealed fluid (high-pressure fluid)
M Mechanical seal m Emergency seal G High-pressure gas (high-pressure fluid)

Claims (7)

A shaft seal device configured to seal a fluid to be sealed in a machine interior region with a mechanical seal comprising a case-side seal ring provided on a seal case and a shaft-side seal ring provided on a rotating shaft,
An emergency seal is arranged on the inside area side of the mechanical seal,
The emergency seal has a stationary seal ring fixed to the rotary shaft and the seal case, and the movable sealing end face, which is the end face of the seal case, contacts the fixed sealing end face, which is the end face of the stationary seal ring. a movable seal ring held movably in the axial direction between a sealing position where the fluid is sealed and a non-sealing position where the movable sealing end face is separated from the fixed sealing end face; and the movable sealing ring is held at the non-sealing position. movable seal ring holding means; movable seal ring moving means for forcibly moving the movable seal ring from the non-sealing position to the sealing position; and a low melting point member to be activated ,
The movable seal ring holding means is a spring loaded between the seal case and the movable seal ring to bias and hold the movable seal ring at the non-sealing position,
The movable seal ring moving means includes a sealed back pressure chamber formed between the seal case and the movable seal ring, and a movable seal ring that is supplied to the back pressure chamber to resist the urging force of the spring. and a high-pressure fluid that moves from the non-sealing position to the sealing position, and a communication passage that communicates the supply source of the high-pressure fluid and the back pressure chamber,
A shaft sealing device according to claim 1 , wherein said low-melting-point member is a plug mounted in said communicating passage in a state of blocking supply of said high-pressure fluid to said communicating passage . The high-pressure fluid is the fluid to be sealed, the supply source of the high-pressure fluid is the machine interior region, and the communication path is formed in the movable seal ring or the seal case in a state of communicating the back pressure chamber and the machine interior region. 2. The shaft seal according to claim 1, characterized in that said plug is melted by contact with said sealed fluid and/or heat transfer from a mechanical seal constituent member constituting said mechanical seal. Device. The high-pressure fluid is a pressurized gas other than the sealed fluid, the supply source of the high-pressure fluid is a storage tank for the pressurized gas, and the communication path communicates the back pressure chamber and the storage tank. At least the back pressure chamber side portion of the seal case is formed in the seal case, and the plug body is loaded in the communicating passage portion formed in the seal case, and the heat transfer from the seal case 2. The shaft sealing device according to claim 1 , wherein the shaft sealing device is melted by The movable seal ring moving means is a spring loaded between the seal case and the movable seal ring to urge the movable seal ring to the sealing position, and the movable seal ring holding means holds the movable seal ring. A connecting body that connects the movable seal ring and the seal case in a state of being held at the non-sealing position against the urging force of the spring, at least a part of the connecting body being made of the low-melting-point member. The shaft sealing device according to claim 1, characterized by: 5. The method according to claim 4 , wherein the portion of the connecting body made of the low-melting-point member is melted by contact with the fluid to be sealed and/or heat transfer from the seal case . Shaft sealing device. The shaft sealing device according to any one of claims 1 to 5 , wherein said stationary seal ring is also configured by a mechanical seal component constituting said mechanical seal fixed to a rotating shaft . An elastic seal ring that is superior in heat resistance to an O-ring that seals between the stationary seal ring and the rotating shaft and between the movable seal ring and the seal case and between the mechanical seal components that constitute the mechanical seal. The shaft sealing device according to any one of claims 1 to 6 , characterized in that the shaft sealing device is sealed with

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