sealing structure

Abstract

This invention provides a seal structure that allows for the introduction of purge gas with a simple configuration. [Solution] The seal structure of the present disclosure is a seal structure for sealing between an inner seal surface and an outer seal surface that are radially opposite to each other, and comprises an annular gland packing that is in close contact with the inner seal surface and the outer seal surface, respectively, and an annular labyrinth packing provided on the machine side where the fluid to be sealed is present, and a labyrinth gap is formed between the labyrinth packing and the inner seal surface, wherein the labyrinth packing has a purge channel that opens on the inner circumference side of the labyrinth packing in order to introduce a purge gas between itself and the inner seal surface.

Description

Technical Field

[0001] The present disclosure relates to a seal structure.

Background Art

[0002] Patent Document 1 discloses a shaft seal device that suppresses leakage of a sealed fluid in a fluid device to the atmosphere through a gap between an outer casing and a shaft. This shaft seal device includes a gland packing disposed on the atmospheric side of the gap, a labyrinth packing disposed on the in-machine side of the gap, and a lantern ring disposed between these two packings. The gland packing seals the gap by pressing in the axial direction so that its outer peripheral surface and inner peripheral surface are in close contact with the outer casing and the shaft, respectively.

[0003] The labyrinth packing suppresses the flow of the sealed fluid on the in-machine side toward the gland packing by the concavo-convex portions formed on its inner peripheral side. A communication hole for supplying a purge gas is formed on the inner peripheral side of the lantern ring. The purge gas supplied to the inner peripheral side from the communication hole of the lantern ring flows through the inner peripheral side of the labyrinth packing and into the in-machine side. Thereby, leakage of the sealed fluid on the in-machine side to the atmosphere is suppressed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the above shaft seal device, in addition to the gland packing, a labyrinth packing and a lantern ring for introducing a purge gas to the in-machine side are required, so the number of parts is large and the assembly work is complicated.

[0006] This disclosure aims to provide a seal structure that allows for the introduction of purge gas with a simple configuration. [Means for solving the problem]

[0007] (1) The present disclosure provides a sealing structure for sealing between an inner and outer sealed surface that are radially opposite to each other, comprising: an annular gland packing that is in close contact with the inner and outer sealed surfaces, respectively; and an annular labyrinth packing provided on the machine side where the fluid to be sealed is present, beyond the gland packing, and forming a labyrinth gap between itself and the inner sealed surface, wherein the labyrinth packing has a purge channel that opens on the inner circumference side of the labyrinth packing in order to introduce a purge gas between itself and the inner sealed surface.

[0008] According to the sealing structure of this disclosure, since the labyrinth packing has a purge channel for introducing purge gas between itself and the inner sealed surface, there is no need to provide a lantern ring with a communication hole (purge channel) formed therein, as in the conventional method. This allows for the introduction of purge gas with a simple configuration.

[0009] (2) In the seal structure of (1) above, the purge channel is preferably open on the inner circumference side of the labyrinth packing at the position on the gland packing side, and the labyrinth gap preferably has a first labyrinth gap formed on the machine side and a second labyrinth gap formed on the gland packing side between the labyrinth packing and the inner sealed surface. In this case, in addition to the first labyrinth gap on the machine side, a second labyrinth gap is also formed on the gland packing side (purge flow path side) between the labyrinth packing and the inner sealed surface. This effectively prevents the sealed fluid on the machine side from flowing through the labyrinth gap to the gland packing side.

[0010] (3) In the sealing structure of (1) or (2) above, it is preferable that the labyrinth packing is composed of a plurality of divided parts that are divided in the circumferential direction. When a labyrinth packing is formed in an endless annular shape, it is necessary to insert the labyrinth packing from the axial end of the inner sealed surface and move the labyrinth packing to a predetermined axial position on the inner sealed surface, which requires a considerable amount of time for assembly. In contrast, with the seal structure described in (3) above, the labyrinth packing can be installed by combining multiple divided parts in the circumferential direction at the predetermined position on the inner sealed surface. Therefore, the labyrinth packing can be installed in a shorter time than with an endless annular labyrinth packing.

[0011] (4) In the seal structure of (3) above, it is preferable that the ends of the divided bodies that are adjacent to each other in the circumferential direction are in contact with each other in the axial direction, with a gap between them in the circumferential direction. In this case, the ends of adjacent segments in the circumferential direction are arranged with a gap between them in the circumferential direction. Therefore, even if the radial dimensions of each segment change due to thermal effects, the gap can absorb these dimensional changes. Furthermore, the ends of adjacent segments in the circumferential direction are in contact with each other in the axial direction. These contact points can prevent purge gas that has entered the gap from leaking to the gland packing side.

[0012] (5) In the seal structure of (4) above, one end of the circumferentially adjacent divided body has a first surface that extends axially on one axial side and faces one circumferential side, a second surface that extends from the other axial end of the first surface to the other circumferential side and faces the other axial side, and a third surface that extends from the other circumferential end of the second surface to the other axial side and faces one circumferential side, and the other end of the circumferentially adjacent divided body has a fourth surface that extends axially on one axial side and faces the other circumferential side, a fifth surface that extends from the other axial end of the fourth surface to the other circumferential side and faces one axial side, and a sixth surface that extends from the other circumferential end of the fifth surface to the other axial side and faces the other circumferential side, and it is preferable that the first surface and the fourth surface are arranged with a gap between them in the circumferential direction, and the third surface and the sixth surface are arranged with a gap between them in the circumferential direction, while the second surface and the fifth surface are in contact with each other in the axial direction.

[0013] In this case, the ends of adjacent segments in the circumferential direction have a simple configuration consisting of three surfaces: the first surface (fourth surface), the second surface (fifth surface), and the third surface (sixth surface). This allows for the absorption of radial dimensional changes due to thermal effects and suppression of purge gas leakage to the gland packing side. [Effects of the Invention]

[0014] According to the shaft sealing device of this disclosure, purge gas can be introduced with a simple configuration. [Brief explanation of the drawing]

[0015] [Figure 1] Figure 1 is a cross-sectional view showing a shaft sealing device equipped with a sealing structure according to an embodiment. [Figure 2] Figure 2 is an enlarged cross-sectional view of a labyrinth packing. [Figure 3] Figure 3 shows the labyrinth packing as viewed from the atmospheric side. [Figure 4] Figure 4 is a view taken along arrow I in Figure 3. [Figure 5] Figure 5 is a view from arrow II in Figure 3.

Mode for Carrying Out the Invention

[0016] Next, preferred embodiments of the present disclosure will be described with reference to the accompanying drawings. [Shaft Sealing Device] FIG. 1 is a cross-sectional view showing a shaft sealing device 1 including a seal structure 10 according to an embodiment. The shaft sealing device 1 is provided in a fluid device such as a dryer or a stirrer, and suppresses leakage of a sealed fluid existing inside the fluid device (the left side in FIG. 1) to the atmosphere side (the right side in FIG. 1). The sealed fluid is, for example, a powder. The fluid device includes a shaft 50 that rotates around an axis C or reciprocates in the direction of the axis C.

[0017] The shaft 50 of the present embodiment has a cylindrical shaft body 51 and a cylindrical sleeve member 52 fitted to the outer peripheral surface of the shaft body 51. The shaft 50 may be composed of only the shaft body 51. In the fluid device of the present embodiment, the axis C of the shaft 50 is arranged in the horizontal direction, but the axis C may be arranged in the vertical direction. Hereinafter, in this specification, the direction along the axis C is referred to as the "axial direction", the direction orthogonal to the axis C is referred to as the "radial direction", and the direction around the axis C is referred to as the "circumferential direction".

[0018] The shaft sealing device 1 includes a seal box 2, a tightening mechanism 3, and a seal structure 10. The seal box 2 has a cylindrical box body 21 surrounding the shaft 50 and a pair of annular flanges 22 extending radially outward from both axial ends of the box body 21. The flange 22 on the inside of the machine is fixed to the housing side of the fluid device. A screw hole 23 is formed through the flange 22 on the atmosphere side in the axial direction. A plurality (only one is shown in FIG. 1) of screw holes 23 are formed in the circumferential direction of the flange 22.

[0019] On the inner circumference of the box body 21, an annular stepped surface 21a extending in the radial direction and a circumferential surface 21b extending from the outer peripheral end of the stepped surface 21a to the flange 22 on the atmosphere side are formed. The circumferential surface 21b faces the outer peripheral surface 53 of the shaft 50 (sleeve 52) in the radial direction. An annular space S is formed between the circumferential surface 21b of the box body 21 and the outer peripheral surface 53 of the shaft 50.

[0020] In the box body 21, a pair of introduction holes 24 for introducing purge gases A and B into the annular space S are formed to penetrate in the radial direction. The pair of introduction holes 24 consists of a first introduction hole 24A and a second introduction hole 24B located on the atmosphere side of the first introduction hole 24A. A pipe 61 through which the compressed purge gas A flows is connected to the first introduction hole 24A. A pipe 62 through which the compressed purge gas B flows is connected to the second introduction hole 24B. The purge gas B is at a higher pressure than the purge gas A.

[0021] The seal structure 10 is disposed in the annular space S and seals between the circumferential surface (outer sealed surface) 21b of the seal box 2 and the outer peripheral surface (inner sealed surface) 53 of the shaft 50. The seal structure 10 of the present embodiment includes a plurality of ground packings 11, a plurality of spacers 12, a lantern ring 13, an auxiliary packing 14, and a labyrinth packing 15.

[0022] The labyrinth packing 15 is disposed closer to the inside of the aircraft than the plurality of ground packings 11. The labyrinth packing 15 of the present embodiment is disposed closest to the inside of the aircraft in the annular space S. The labyrinth packing 15 is formed in an annular shape. The end face 15a on the inside of the aircraft of the labyrinth packing 15 abuts against the stepped surface 21a of the box body 21. The outer diameter of the labyrinth packing 15 is smaller than the inner diameter of the circumferential surface 21b of the seal box 2. The outer peripheral surface on the atmosphere side of the labyrinth packing 15 faces the first introduction hole 24A of the seal box 2. Details of the labyrinth packing 15 will be described later.

[0023] The auxiliary packing 14 is positioned adjacent to the atmospheric side of the labyrinth packing 15. The auxiliary packing 14 is formed in an annular shape. The auxiliary packing 14 is located in the annular space S between the first inlet hole 24A and the second inlet hole 24B of the seal box 2. The outer and inner surfaces of the auxiliary packing 14 are in contact with the circumferential surface 21b of the seal box 2 and the outer surface 53 of the shaft 50, respectively. The auxiliary packing 14 complements the sealing performance of the multiple gland packings 11. The auxiliary packing 14 is made of a material that allows purge gas B to pass more easily between it and the outer surface 53 of the shaft 50 than the gland packings 11.

[0024] The lantern ring 13 is positioned adjacent to the atmospheric side of the auxiliary packing 14. The lantern ring 13 is formed in an annular shape. The outer and inner surfaces of the lantern ring 13 are in contact with the circumferential surface 21b of the seal box 2 and the outer surface 53 of the shaft 50, respectively. A flow path hole 13a is formed in the lantern ring 13, extending radially through it. The flow path hole 13a communicates with the second inlet hole 24B of the seal box 2.

[0025] The purge gas B flowing through the piping 62 passes through the second inlet hole 24B and the flow path hole 13a and is introduced to the inner circumference of the lantern ring 13. The purge gas B introduced to the inner circumference of the lantern ring 13 passes through the inner circumference of the auxiliary packing 14 and flows to the inner circumference of the labyrinth packing 15.

[0026] Multiple gland packings 11 and multiple spacers 12 are arranged alternately in the axial direction on the atmospheric side of the lantern ring 13. The number of gland packings 11 and the number of spacers 12 are the same (3 in Figure 1). The number of gland packings 11 and spacers 12 is not limited to this embodiment.

[0027] The gland packing 11 is formed in an annular shape. The gland packing 11 is pressed axially by the tightening mechanism 3. The spacer 12 is made of, for example, an annular plate member of metal. By placing the spacer 12 between adjacent gland packings 11 in the axial direction, each gland packing is pressed evenly.

[0028] The tightening mechanism 3 is a mechanism for pressing multiple gland packings 11 in the axial direction. The tightening mechanism 3 includes a pressing member 4, a screw shaft 5, a spring 6, and a nut 7. The pressing member 4 has a cylindrical portion 4a and an annular flange portion 4b, which are located radially outward from the shaft 50. The inner end of the cylindrical portion 4a is inserted into the annular space S. The cylindrical portion 4a is movable in the axial direction relative to the seal box 2.

[0029] The flange portion 4b extends radially outward from the atmospheric end of the cylindrical portion 4a. Multiple through holes 4c are formed in the flange portion 4b in the circumferential direction (only one is shown in Figure 1), penetrating axially. The number of through holes 4c is the same as the number of screw holes 23 in the seal box 2.

[0030] The screw shaft 5 passes through the through hole 4c of the pressing member 4 and is screwed into the screw hole 23 of the seal box 2. This fixes one end of the screw shaft 5 to the seal box 2. The other end of the screw shaft 5 protrudes outwards from the pressing member 4. The screw shaft 5 guides the axial movement of the pressing member 4.

[0031] A nut 7 is tightened with a spring 6 inserted on the atmospheric side of the screw shaft 5, relative to the pressing member 4. The spring 6 is a compression coil spring. As the nut 7 is tightened, the pressing member 4 moves inward relative to the screw shaft 5 and the seal box 2, pressing the multiple gland packings 11 in the axial direction. When the multiple gland packings 11 are pressed in this way, the outer circumferential surface 11a and inner circumferential surface 11b of each gland packing 11 come into close contact with the radially opposing circumferential surface 21b of the seal box 2 and the outer circumferential surface 53 of the shaft 50, respectively. As a result, each gland packing 11 prevents the sealed fluid and purge gases A and B in the fluid equipment from leaking to the atmosphere.

[0032] [Labyrinth Packing] Figure 2 is an enlarged cross-sectional view of the labyrinth packing 15. In Figures 1 and 2, the labyrinth packing 15 is a packing that forms a labyrinth gap 30 between itself and the outer circumferential surface 53 of the shaft 50. The labyrinth gap 30 in this embodiment is composed of a first labyrinth gap 31 formed on the machine side and a second labyrinth gap 32 formed on the atmospheric side (gland packing 11 side).

[0033] A first labyrinth portion 16 is provided on the machine-side side of the inner circumference of the labyrinth packing 15, forming a first labyrinth gap 31. The first labyrinth portion 16 has a plurality of recesses 161 and a plurality of protrusions 162 that are alternately arranged in the axial direction. The recesses 161 and protrusions 162 are formed in an annular shape over the entire circumferential direction of the labyrinth packing 15.

[0034] In this embodiment, the protrusion 162 is formed in a substantially triangular shape, tapering radially inward in cross-sectional view. The protrusion 162 has an inner surface 163 and an outer surface 164 facing the atmosphere. The inner surface 163 extends straight along the radial direction. The outer surface 164 facing the atmosphere is an inclined surface that widens in diameter from the inner surface to the atmosphere. A first labyrinth gap 31 is formed between the first labyrinth section 16 (a plurality of recesses 161 and a plurality of protrusions 162) and the outer circumferential surface 53 of the shaft 50. The cross-sectional shape of the protrusion 162 is not limited to this embodiment.

[0035] A second labyrinth portion 17 is provided on the atmospheric side of the inner circumference of the labyrinth packing 15, forming a second labyrinth gap 32. The second labyrinth portion 17 has a plurality of recesses 171 and a plurality of protrusions 172 arranged alternately in the axial direction. The protrusions 172 have an inner side surface 173 and an atmospheric side surface 174. The recesses 171 and protrusions 172 (side surfaces 173, 174) have the same configuration as the recesses 161 and protrusions 162 (side surfaces 163, 164) of the first labyrinth portion 16, respectively, so a detailed explanation is omitted. The second labyrinth gap 32 is formed between the second labyrinth portion 17 (a plurality of recesses 171 and a plurality of protrusions 172) and the outer circumferential surface 53 of the shaft 50. The cross-sectional shape of the protrusions 172 is not limited to this embodiment.

[0036] A circumferential surface 18 is formed between the first labyrinth portion 16 and the second labyrinth portion 17 on the inner circumference of the labyrinth packing 15. The diameter of the circumferential surface 18 is approximately the same as the diameter of the bottom surface of the recess 161 (recess 171). An annular gap 33 is formed between the circumferential surface 18 of the labyrinth packing 15 and the outer surface 53 of the shaft 50.

[0037] The first labyrinth portion 16 and the second labyrinth portion 17 may be formed axially continuous on the inner circumference of the labyrinth packing 15. That is, the first labyrinth gap 31 and the second labyrinth gap 32 may be formed axially continuous between the labyrinth packing 15 and the outer circumferential surface 53 of the shaft 50. Also, the second labyrinth portion 17 does not have to be formed on the inner circumference of the labyrinth packing 15. That is, the second labyrinth gap 32 does not have to be formed between the labyrinth packing 15 and the outer circumferential surface 53 of the shaft 50.

[0038] A pair of grooves 19 are formed on the outer circumference of the labyrinth packing 15. The pair of grooves 19 consists of a first groove 19A located on the machine side and a second groove 19B located on the atmospheric side. The first groove 19A and the second groove 19B are each formed in a U shape in cross-section. In this embodiment, the first groove 19A is located radially outward from the first labyrinth portion 16. The second groove 19B is located radially outward from the second labyrinth portion 17 and is positioned opposite the first introduction hole 24A of the seal box 2.

[0039] A garter spring 35 is installed in the first groove 19A and the second groove 19B, respectively. The garter spring 35 is formed in an annular shape. The garter spring 35 constantly presses the labyrinth packing 15 radially inward with its biasing force. The biasing force of the garter spring 35 suppresses the thermal expansion of the labyrinth packing 15 radially outward.

[0040] [Purge channel] Figure 3 shows the labyrinth packing 15 as viewed from the atmospheric side. In Figures 2 and 3, the labyrinth packing 15 has a purge channel 15b that opens on the inner circumference of the labyrinth packing 15 in order to introduce purge gas A between it and the outer circumferential surface 53 of the shaft 50. Multiple purge channels 15b are formed at equal intervals in the circumferential direction of the labyrinth packing 15 (six in Figure 3).

[0041] In this embodiment, the purge channel 15b is formed to open on the inner circumference side of the labyrinth packing 15 at a position on the gland packing 11 side. Specifically, the purge channel 15b is formed to penetrate the labyrinth packing 15 radially from the bottom of the second groove 19B to the second labyrinth portion 17. The purge channel 15b is in communication with the second labyrinth gap 32. The purge channel 15b opens at the bottom surface of the recess 171 in the second labyrinth portion 17. For this reason, the recess 171 into which the purge channel 15b opens is formed to be longer in the axial direction than the other recesses 171.

[0042] The purge channel 15b is not limited to this embodiment, as long as it opens on the atmospheric side of the first labyrinth section 16. For example, the purge channel 15b may be formed to penetrate radially from the outer circumferential surface between the first groove 19A and the second groove 19B in the labyrinth packing 15 to the circumferential surface 18.

[0043] In Figures 1 and 2, the purge gas A flowing through the piping 61 passes through the first inlet hole 24A and the purge channel 15b and is supplied to the second labyrinth gap 32, which is on the inner circumference side of the labyrinth packing 15. The purge gas A supplied to the second labyrinth gap 32 flows into the machine side by passing through the annular gap 33 and the first labyrinth gap 31. At the same time, the purge gas B that flows from the inner circumference side of the lantern ring 13 to the inner circumference side of the labyrinth packing 15 (second labyrinth gap 32), as described above, also flows into the machine side by passing through the annular gap 33 and the first labyrinth gap 31. This prevents the sealed fluid inside the machine from leaking to the atmosphere.

[0044] An annular sealing groove 15c is formed on the machine-side end face 15a of the labyrinth packing 15. The sealing groove 15c is, for example, a dovetail groove in which the groove width narrows radially (vertical direction in Figure 2) from the groove bottom on the atmospheric side toward the opening on the machine side. An O-ring 36 is fitted into the sealing groove 15c. The O-ring 36 seals the space between the end face 15a of the labyrinth packing 15 and the stepped surface 21a of the seal box 2.

[0045] As a result, even if purge gas A flows into the gap between the labyrinth packing 15 and the box body 21 from the first introduction hole 24A of the seal box 2, the O-ring 36 prevents the purge gas A from flowing radially inward from between the end face 15a and the stepped surface 21a. Therefore, it is possible to prevent the purge gas A from flowing into the machine side without passing through the first labyrinth section 16.

[0046] [Divided body] Figure 4 is a view taken along arrow I in Figure 3. Figure 5 is a view taken along arrow II in Figure 3. In Figures 3 to 5, the labyrinth packing 15 is composed of a plurality of divided sections 40 that are divided in the circumferential direction. In this embodiment, the plurality of divided sections 40 consist of a first divided section 40A and a second divided section 40B. Therefore, the end face 15a, seal groove 15c, first labyrinth section 16, second labyrinth section 17, circumferential surface 18, and groove 19 of the labyrinth packing 15 are each divided into two in the circumferential direction. The number of divided sections 40 is not limited to two as in this embodiment, but may be three or more.

[0047] The first segment 40A and the second segment 40B are each formed in a semi-circular shape. The first segment 40A has a first end 41 and a second end 42 on both sides in the circumferential direction. The second segment 40B has a third end 43 and a fourth end 44 on both sides in the circumferential direction.

[0048] In Figures 3 and 4, the first end 41 of the first divided body 40A and the third end 43 of the second divided body 40B are adjacent in the circumferential direction. The first end 41 and the third end 43 are in contact with each other in the axial direction, with gaps 45 and 46 between them in the circumferential direction. Specifically, the first end 41 and the third end 43 are configured as follows.

[0049] The first end portion 41 of the first divided body 40A has a first surface 411, a second surface 412, and a third surface 413. The first surface 411 is formed on one axial side of the first end portion 41. The first surface 411 extends axially from one axial end to the axial center of the first end portion 41 and faces one circumferential side.

[0050] The second surface 412 is formed perpendicular to the first surface 411 at the axial center of the first end portion 41. The second surface 412 extends from the other axial end of the first surface 411 to the other circumferential end and faces the other axial side. The third surface 413 is formed parallel to the first surface 411 and perpendicular to the second surface 412 at the other axial side of the first end portion 41. The third surface 413 extends axially from the other circumferential end of the second surface 412 to the other axial end of the first end portion 41 and faces one circumferential side.

[0051] The third end portion 43 of the second divided body 40B has a fourth surface 434, a fifth surface 435, and a sixth surface 436. The fourth surface 434 is formed on one axial side of the third end portion 43. The fourth surface 434 extends axially from one axial end to the axial center of the third end portion 43 and faces the other circumferential side.

[0052] The fifth surface 435 is formed perpendicular to the fourth surface 434 at the axial center of the third end 43. The fifth surface 435 extends from the other axial end of the fourth surface 434 to the other circumferential end and faces one axial side. The sixth surface 436 is formed parallel to the fourth surface 434 and perpendicular to the fifth surface 435 at the other axial side of the third end 43. The sixth surface 436 extends axially from the other circumferential end of the fifth surface 435 to the other axial end of the third end 43 and faces the other circumferential side.

[0053] The first surface 411 of the first end 41 and the fourth surface 434 of the third end 43 are arranged with a gap 45 between them in the circumferential direction. Similarly, the third surface 413 of the first end 41 and the sixth surface 436 of the third end 43 are arranged with a gap 46 between them in the circumferential direction. The circumferential dimensions of the gap 45 and the gap 46 are approximately the same. With the gaps 45 and 46 formed in this way, a portion of the second surface 412 of the first end 41 and a portion of the fifth surface 435 of the third end 43 are in contact with each other in the axial direction.

[0054] In Figures 3 and 5, the second end 42 of the first divided body 40A and the fourth end 44 of the second divided body 40B are adjacent in the circumferential direction. The second end 42 and the fourth end 44 are in contact with each other in the axial direction, with gaps 47 and 48 between them in the circumferential direction. Specifically, the second end 42 and the fourth end 44 are configured as follows.

[0055] The second end portion 42 of the first segment 40A has a fourth surface 424, a fifth surface 425, and a sixth surface 426. The fourth surface 424, fifth surface 425, and sixth surface 426 of the second end portion 42 have the same configuration as the fourth surface 434, fifth surface 435, and sixth surface 436 of the third end portion 43 (see Figure 4), respectively, so a detailed explanation is omitted.

[0056] The fourth end portion 44 of the second divided body 40B has a first surface 441, a second surface 442, and a third surface 443. The first surface 441, the second surface 442, and the third surface 443 of the fourth end portion 44 have the same configuration as the first surface 411, the second surface 412, and the third surface 413 of the first end portion 41 (see Figure 4), respectively, so a detailed explanation is omitted.

[0057] The first surface 441 of the fourth end 44 and the fourth surface 424 of the second end 42 are arranged with a gap 47 between them in the circumferential direction. Similarly, the third surface 443 of the fourth end 44 and the sixth surface 426 of the second end 42 are arranged with a gap 48 between them in the circumferential direction. The circumferential dimensions of the gap 47 and the gap 48 are approximately the same. With the gaps 47 and 48 formed in this way, a portion of the second surface 442 of the fourth end 44 and a portion of the fifth surface 425 of the second end 42 are in contact with each other in the axial direction.

[0058] [Effects and Effects] According to the seal structure 10 of this embodiment, the labyrinth packing 15 has a purge channel 15b for introducing purge gas A between itself and the outer circumferential surface 53 of the shaft 50. Therefore, it is not necessary to provide a lantern ring with a communication hole (purge channel) formed therein, as in the conventional method, in order to introduce purge gas A. This allows for the introduction of purge gas A with a simple configuration. Furthermore, the assembly of the seal structure 10 can be easily performed.

[0059] Between the labyrinth packing 15 and the outer circumferential surface 53 of the shaft 50, a second labyrinth gap 32 is formed not only on the machine side but also on the gland packing 11 side (purge flow path 15b side). This effectively prevents the sealed fluid on the machine side from flowing through the labyrinth gap 30 to the gland packing 11 side.

[0060] When a labyrinth packing is formed in an endless annular shape, it is necessary to insert the labyrinth packing from the axial end of the shaft and move it to a predetermined position in the axial direction of the shaft, which requires a considerable amount of time for assembly. In contrast, the labyrinth packing 15 of this embodiment is composed of a plurality of divided parts 40 that are divided in the circumferential direction. Therefore, the labyrinth packing 15 can be installed by combining the plurality of divided parts 40 in the circumferential direction at a predetermined position on the outer circumferential surface 53 of the shaft 50. Thus, the labyrinth packing 15 can be installed in a shorter time than an endless annular labyrinth packing.

[0061] The ends 41, 43 (42, 44) of adjacent segments 40 in the circumferential direction are arranged with gaps 45, 46 (47, 48) between them in the circumferential direction. Therefore, even if the radial dimensions of each segment 40 change due to thermal effects, these dimensional changes can be absorbed by the gaps 45, 46 (47, 48). In addition, as the outer circumferential surface 53 of the shaft 50 slides against the respective protrusions 162, 172 of the first labyrinth section 16 and the second labyrinth section 17, even if the radial dimensions of the respective protrusions 162, 172 change due to wear, these dimensional changes can be absorbed by the gaps 45, 46 (47, 48).

[0062] The ends 41, 43 (42, 44) of adjacent segments 40 in the circumferential direction are in contact with each other in the axial direction. Therefore, these contact portions can prevent purge gases A and B that have entered the gaps 45, 46 (47, 48) from leaking to the gland packing 11 side.

[0063] The ends 41, 43 (42, 44) of adjacent circumferentially separated sections 40 each consist of three surfaces: a first surface 411, 441 (fourth surface 434, 424), a second surface 412, 442 (fifth surface 435, 425), and a third surface 413, 443 (sixth surface 436, 426). The combination of these three surfaces causes the ends 41, 43 (42, 44) to abut axially with a gap 45, 46 (47, 48) in the circumferential direction. Therefore, with this simple configuration, radial dimensional changes due to thermal effects or wear can be absorbed, and leakage of purge gases A and B to the gland packing 11 can be suppressed.

[0064] [others] The seal structure 10 may include a labyrinth packing with a purge channel instead of the lantern ring 13 to introduce purge gas B. Furthermore, while the seal structure 10 of this embodiment includes a labyrinth packing 15 and a lantern ring 13 for introducing purge gases A and B respectively, it is sufficient to include at least a labyrinth packing 15 for introducing purge gas A. In other words, the piping 62 through which purge gas B flows, the second introduction hole 24B, and the lantern ring 13 are provided as needed and are not essential components in the seal structure of this disclosure.

[0065] The shapes of the ends 41, 43 (42, 44) of adjacent circumferentially divided bodies 40 are not limited to this embodiment. For example, in this embodiment (see Figures 4 and 5), a gap 45 (47) is formed on one axial side and one circumferential side, and a gap 46 (48) is formed on the other axial side and the other circumferential side. However, the ends 41, 43 (42, 44) may be formed such that a gap 45 (47) is formed on the other axial side and one circumferential side, and a gap 46 (48) is formed on one axial side and the other circumferential side. Alternatively, the shapes of the ends 41, 43 (42, 44) may be made to be a wave shape or a sawtooth shape that is uneven in the circumferential direction over the entire axial direction, so that the ends 41, 43 (42, 44) are in contact with each other in the axial direction with a gap in the circumferential direction.

[0066] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the invention is indicated by the claims, not in the sense described above, and is intended to include all modifications in the sense and scope equivalent to the claims. [Explanation of Symbols]

[0067] 10. Seal structure 11. Gland Packing 15 Labyrinth Packing 15b Purge channel 21b Circumferential surface (outer sealed surface) 30 Labyrinth Gap 31. First Labyrinth Gap 32 Second Labyrinth Gap 40 split body 41 First end (end) 42 Second end (end) 43 Third end (end) 44 4th end (end) 53 Outer surface (inner sealed surface) 411,441 1st page 412,442 2nd page 413,443 3rd page 424,434 4th page 425,435 Page 5 426,436 Page 6

Claims

1. A sealing structure that seals between an inner sealing surface and an outer sealing surface that are radially opposite to each other, An annular gland packing that adheres closely to the inner sealed surface and the outer sealed surface, respectively, The system includes an annular labyrinth packing provided on the machine side where the fluid to be sealed is present, and which forms a labyrinth gap between itself and the inner surface to be sealed, rather than the aforementioned gland packing. The labyrinth packing is a sealing structure having a purge channel that opens on the inner circumference side of the labyrinth packing in order to introduce purge gas between itself and the inner surface to be sealed.

2. The purge channel is open on the inner circumference side of the labyrinth packing at the position on the gland packing side. The sealing structure according to claim 1, wherein the labyrinth gap comprises a first labyrinth gap formed on the machine side and a second labyrinth gap formed on the gland packing side, between the labyrinth packing and the inner sealed surface.

3. The seal structure according to claim 1 or claim 2, wherein the labyrinth packing is composed of a plurality of divided parts that are divided in the circumferential direction.

4. The seal structure according to claim 3, wherein the ends of the circumferentially adjacent divided bodies are in contact with each other in the axial direction, with a gap between them in the circumferential direction.

5. One end of the circumferentially adjacent divided body is A first surface extending axially on one side in the axial direction and facing one side in the circumferential direction, A second surface extends from the other axial end of the first surface to the other circumferential side and faces the other axial side, It has a third surface that extends from the other circumferential end of the second surface toward the other axial direction and faces one side in the circumferential direction, The other end of the circumferentially adjacent divided body is A fourth surface extending axially on one axial side and facing the other circumferential side, A fifth surface extending from the other axial end of the fourth surface to the other circumferential side, and facing one side in the axial direction, The fifth surface has a sixth surface that extends from the other circumferential end of the fifth surface to the other axial side and faces the other circumferential side, The seal structure according to claim 4, wherein the first and fourth surfaces are arranged with a gap between them in the circumferential direction, and the third and sixth surfaces are arranged with a gap between them in the circumferential direction, and the second and fifth surfaces are in contact with each other in the axial direction.

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