Seal structure

Abstract

To provide a seal structure that can introduce purge gas with simple constitution.SOLUTION: A seal structure according to the present disclosure seals a gap between an inside sealed surface and an outside sealed surface opposed to each other in a radial direction, and comprises: annular gland packing in close contact with each of the inside sealed surface and the outside sealed surface; and annular labyrinth packing provided closer to the inside of a machine in which sealed fluid exists, than the gland packing, and in which a labyrinth gap is formed between itself and the inside sealed surface. The labyrinth packing comprises a purge flow passage opened on the side of an inner periphery of the labyrinth packing in order to introduce purge gas between itself and the inside sealed surface.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Patent Document 1 discloses a shaft seal device that prevents a sealed fluid in a fluid device from leaking to the atmosphere through a gap between an outer casing and a shaft. This shaft seal device includes a gland packing arranged on the atmosphere side of the gap, a labyrinth packing arranged on the machine interior side of the gap, and a lantern ring arranged between these two packings. When pressed in the axial direction, the gland packing's outer and inner circumferential surfaces come into close contact with the outer casing and the shaft, respectively, to seal the gap.

[0003] The labyrinth packing has an uneven portion formed on its inner periphery to prevent the sealed fluid inside the machine from flowing to the gland packing side. The lantern ring has a communication hole formed on its inner periphery to supply purge gas. The purge gas supplied to the inner periphery from the communication hole of the lantern ring passes through the inner periphery of the labyrinth packing and flows to the inside of the machine. This prevents the sealed fluid inside the machine from leaking to the atmosphere. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Utility Model Application Publication No. 59-97277 Summary of the Invention [Problem to be solved by the invention]

[0005] The above shaft seal device requires a labyrinth packing and a lantern ring for introducing purge gas into the inside of the machine in addition to the gland packing, which results in a large number of parts and complicated assembly work.

[0006] An object of the present disclosure is to provide a seal structure capable of introducing a purge gas with a simple configuration. [Means for solving the problem]

[0007] (1) The present disclosure relates to a seal structure for sealing between an inner sealed surface and an outer sealed surface that are radially opposed to each other, the seal structure comprising: an annular gland packing that is in close contact with the inner sealed surface and the outer sealed surface, respectively; and an annular labyrinth packing that is provided on an inner side of the gland packing where a sealed fluid is present and that forms a labyrinth gap between the labyrinth packing and the inner sealed surface, the labyrinth packing having a purge flow path that opens on an inner side of the labyrinth packing to introduce a purge gas between the labyrinth packing and the inner sealed surface.

[0008] According to the seal structure of the present disclosure, the labyrinth packing has a purge flow passage for introducing a purge gas between the labyrinth packing and the inner sealed surface, so there is no need to provide a lantern ring with a communication hole (purge flow passage) as in the conventional case. This makes it possible to introduce the purge gas with a simple structure.

[0009] (2) In the sealing structure of (1) above, it is preferable that the purge flow path opens at a position on the inner periphery side of the labyrinth packing, on the side of the gland packing, and the labyrinth gap has, between the labyrinth packing and the inner sealed surface, a first labyrinth gap formed on the inside side of the machine and a second labyrinth gap formed on the side of the gland packing. In this case, in addition to the first labyrinth gap on the inside of the machine, 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, which effectively prevents the sealed fluid on the inside of the machine from passing through the labyrinth gap and flowing to the gland packing side.

[0010] (3) In the seal structure of (1) or (2) above, it is preferable that the labyrinth packing is composed of a plurality of divided bodies divided in the circumferential direction. When the labyrinth packing is formed in an endless ring 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 lot of time for assembly. In contrast, in the seal structure of (3) above, the labyrinth packing can be attached by combining multiple divided bodies in the circumferential direction at the predetermined position on the inner sealed surface. Therefore, the labyrinth packing can be attached in a shorter time than with an endless ring-shaped labyrinth packing.

[0011] (4) In the seal structure of (3) above, it is preferable that the ends of the circumferentially adjacent segments abut against each other in the axial direction while being arranged with a gap between them in the circumferential direction. In this case, the ends of the circumferentially adjacent segments are arranged with a gap between them in the circumferential direction, so that even if the radial dimensions of each segment change due to thermal effects, the gap can absorb the dimensional change. Also, the ends of the circumferentially adjacent segments abut against each other in the axial direction, so that these abutting portions can prevent the purge gas that has entered the gap from leaking toward the gland packing.

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

[0013] In this case, the ends of the circumferentially adjacent segments each have a simple structure consisting of three surfaces: a first surface (fourth surface), a second surface (fifth surface), and a third surface (sixth surface), which makes it possible to absorb radial dimensional changes caused by thermal effects and to prevent purge gas from leaking toward the gland packing. Effect of the Invention

[0014] According to the shaft sealing device of the present disclosure, purge gas can be introduced with a simple configuration. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a cross-sectional view showing a shaft sealing device having a seal structure according to an embodiment. [Diagram 2] FIG. 2 is an enlarged cross-sectional view of the labyrinth packing. [Diagram 3] FIG. 3 is a view of the labyrinth packing as seen from the atmosphere side. [Figure 4] FIG. 4 is a view taken along the arrow I in FIG. [Diagram 5] FIG. 5 is a view taken along the line II in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[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 equipped with a seal structure 10 according to an embodiment. The shaft sealing device 1 is provided in fluid equipment such as a dryer or a mixer, and prevents a sealed fluid present on the inside side of the fluid equipment (left side in Fig. 1) from leaking to the atmosphere side (right side in Fig. 1). The sealed fluid is, for example, powder. The fluid equipment is equipped with a shaft 50 that rotates around an axis C and reciprocates in the direction of the axis C.

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

[0018] The shaft seal device 1 comprises 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 machine interior side is fixed to the housing side of the fluid equipment. A screw hole 23 is formed in the atmosphere side flange 22, penetrating it in the axial direction. A plurality of screw holes 23 (only one is shown in FIG. 1) are formed in the circumferential direction of the flange 22.

[0019] The inner periphery of the box body 21 is formed with an annular stepped surface 21a extending in the radial direction, and a circumferential surface 21b extending from the outer circumferential end of the stepped surface 21a to the atmosphere-side flange 22. The circumferential surface 21b faces an outer circumferential 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 circumferential surface 53 of the shaft 50.

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

[0021] The seal structure 10 is disposed in the annular space S, and provides a seal between the circumferential surface (outer sealed surface) 21b of the seal box 2 and the outer circumferential surface (inner sealed surface) 53 of the shaft 50. The seal structure 10 of the present embodiment includes a plurality of gland 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 on the inside of the machine than the multiple gland packings 11. The labyrinth packing 15 of this embodiment is disposed on the insidemost side of the machine in the annular space S. The labyrinth packing 15 is formed in an annular shape. An end face 15a on the inside side of the labyrinth packing 15 abuts against a step face 21a of the box body 21. The outer diameter of the labyrinth packing 15 is smaller than the inner diameter of the circumferential face 21b of the seal box 2. The outer peripheral surface of the labyrinth packing 15 on the atmosphere side faces the first introduction hole 24A of the seal box 2. The details of the labyrinth packing 15 will be described later.

[0023] The auxiliary packing 14 is disposed adjacent to the atmosphere side of the labyrinth packing 15. The auxiliary packing 14 is formed in an annular shape. The auxiliary packing 14 is located between the first introduction hole 24A and the second introduction hole 24B of the seal box 2 in the annular space S. The outer peripheral surface and the inner peripheral surface of the auxiliary packing 14 abut against the circumferential surface 21b of the seal box 2 and the outer peripheral 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 the purge gas B to pass between the auxiliary packing 14 and the outer peripheral surface 53 of the shaft 50 more easily than the gland packing 11.

[0024] The lantern ring 13 is disposed adjacent to the atmospheric side of the auxiliary packing 14. The lantern ring 13 is formed in an annular shape. The outer peripheral surface and inner peripheral surface of the lantern ring 13 abut against the circumferential surface 21b of the seal box 2 and the outer peripheral surface 53 of the shaft 50, respectively. A flow passage hole 13a is formed in the lantern ring 13 so as to penetrate therethrough in the radial direction. The flow passage hole 13a is connected to the second introduction hole 24B of the seal box 2.

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

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

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

[0028] The fastening mechanism 3 is a mechanism that presses a plurality of gland packings 11 in the axial direction. The fastening mechanism 3 has a pressing member 4, a screw shaft 5, a spring 6, and a nut 7. The pressing member 4 has a cylindrical portion 4a disposed radially outward of the shaft 50, and an annular flange portion 4b. An end of the cylindrical portion 4a on the machine inner side 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 end of the cylindrical portion 4a on the atmospheric side. The flange portion 4b has a plurality of through holes 4c (only one is shown in FIG. 1) formed in the circumferential direction and axially penetrating the flange portion 4b. The number of through holes 4c is the same as the number of screw holes 23 of 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. As a result, one end of the screw shaft 5 is fixed to the seal box 2. The other end of the screw shaft 5 protrudes toward the atmosphere beyond the pressing member 4. The screw shaft 5 guides the movement of the pressing member 4 in the axial direction.

[0031] A nut 7 is fastened with a spring 6 inserted on the screw shaft 5 closer to the atmosphere than the pressing member 4. The spring 6 is a compression coil spring. When the nut 7 is fastened, the pressing member 4 moves toward the inside of the machine relative to the screw shaft 5 and the seal box 2, and presses the gland packings 11 in the axial direction. When the gland packings 11 are pressed in this manner, the outer peripheral surface 11a and the inner peripheral surface 11b of each gland packing 11 are brought into close contact with the circumferential surface 21b of the seal box 2 and the outer peripheral surface 53 of the shaft 50, which are radially opposed to each other. As a result, each gland packing 11 suppresses leakage of the sealed fluid and each purge gas A and B in the fluid equipment to the atmosphere.

[0032] [Labyrinth packing] Fig. 2 is an enlarged cross-sectional view of the labyrinth packing 15. In Fig. 1 and Fig. 2, the labyrinth packing 15 is a packing that forms a labyrinth gap 30 between itself and the outer peripheral 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 inner side and a second labyrinth gap 32 formed on the atmosphere side (the gland packing 11 side).

[0033] A first labyrinth portion 16 that forms the first labyrinth gap 31 is provided on the inner side of the inner circumference of the labyrinth packing 15. 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 the 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 a cross-sectional view. The protrusion 162 has an inner side 163 and an atmosphere side 164. The inner side 163 extends straight along the radial direction. The atmosphere side 164 is an inclined surface whose diameter increases from the inner side toward the atmosphere side. A first labyrinth gap 31 is formed between the first labyrinth portion 16 (the multiple recesses 161 and the multiple 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] The second labyrinth portion 17 that forms the second labyrinth gap 32 is provided on the atmosphere side of the inner circumference of the labyrinth packing 15. The second labyrinth portion 17 has a plurality of recesses 171 and a plurality of protrusions 172 that are alternately arranged in the axial direction. The protrusions 172 have an inner side 173 and an atmosphere side 174. The recesses 171 and the protrusions 172 (sides 173, 174) have the same configuration as the recesses 161 and the protrusions 162 (sides 163, 164) of the first labyrinth portion 16, respectively, and therefore detailed description thereof will be omitted. The second labyrinth gap 32 is formed between the second labyrinth portion 17 (the plurality of recesses 171 and the 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 that of 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 circumferential surface 53 of the shaft 50.

[0037] The first labyrinth portion 16 and the second labyrinth portion 17 may be formed continuously in the axial direction on the inner circumference of the labyrinth packing 15. In other words, the first labyrinth gap 31 and the second labyrinth gap 32 may be formed continuously in the axial direction between the labyrinth packing 15 and the outer peripheral 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. In other words, the second labyrinth gap 32 does not have to be formed between the labyrinth packing 15 and the outer peripheral surface 53 of the shaft 50.

[0038] A pair of grooves 19 are formed on the outer periphery of the labyrinth packing 15. The pair of grooves 19 includes a first groove 19A located on the machine interior side and a second groove 19B located on the atmosphere 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 of the first labyrinth portion 16. The second groove 19B is located radially outward of the second labyrinth portion 17 and is disposed opposite the first introduction hole 24A of the seal box 2.

[0039] A garter spring 35 is attached to each of the first groove 19A and the second groove 19B. 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 can suppress thermal expansion of the labyrinth packing 15 radially outward.

[0040] [Purge passage] Fig. 3 is a view of the labyrinth packing 15 as seen from the atmosphere side. In Fig. 2 and Fig. 3, the labyrinth packing 15 has purge passages 15b that open on the inner peripheral side of the labyrinth packing 15 in order to introduce purge gas A between the labyrinth packing 15 and the outer peripheral surface 53 of the shaft 50. A plurality of purge passages 15b (six in Fig. 3) are formed at equal intervals in the circumferential direction of the labyrinth packing 15.

[0041] The purge flow passage 15b in this embodiment is formed so as to open at a position on the gland packing 11 side on the inner circumferential side of the labyrinth packing 15. Specifically, the purge flow passage 15b is formed penetrating the labyrinth packing 15 in the radial direction from the bottom of the second groove 19B to the second labyrinth portion 17. The purge flow passage 15b communicates with the second labyrinth gap 32. The purge flow passage 15b opens at the bottom surface of the recess 171 in the second labyrinth portion 17. Therefore, the recess 171 to which the purge flow passage 15b opens is formed longer in the axial direction than the other recesses 171.

[0042] The purge flow passage 15b is not limited to this embodiment as long as it opens to the atmosphere side of the first labyrinth portion 16. For example, the purge flow passage 15b may be formed to penetrate in the radial direction 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] 1 and 2, the purge gas A flowing through the piping 61 passes through the first introduction hole 24A and the purge flow path 15b and is supplied to the second labyrinth gap 32 on the inner circumferential side of the labyrinth packing 15. The purge gas A supplied to the second labyrinth gap 32 passes through the annular gap 33 and the first labyrinth gap 31 and flows into the interior side of the machine. At that time, the purge gas B flowing from the inner circumferential side of the lantern ring 13 to the inner circumferential side (second labyrinth gap 32) of the labyrinth packing 15 as described above also passes through the annular gap 33 and the first labyrinth gap 31 and flows into the interior side of the machine. This makes it possible to suppress leakage of the sealed fluid on the interior side of the machine to the atmosphere side.

[0044] An annular seal groove 15c is formed on the end surface 15a of the labyrinth packing 15 on the machine interior side. The seal groove 15c is, for example, a dovetail groove whose groove width in the radial direction (vertical direction in FIG. 2) narrows from the bottom of the groove on the atmosphere side toward the opening on the machine interior side. An O-ring 36 is fitted in the seal groove 15c. The O-ring 36 provides a seal between the end surface 15a of the labyrinth packing 15 and the step surface 21a of the seal box 2.

[0045] As a result, even if the 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 purge gas A can be prevented from flowing radially inward from between the end face 15a and the step face 21a by the O-ring 36. Therefore, the purge gas A can be prevented from flowing into the machine interior without passing through the first labyrinth portion 16.

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

[0047] The first divided body 40A and the second divided body 40B are each formed in a semicircular arc shape. The first divided body 40A has a first end portion 41 and a second end portion 42 on both sides in the circumferential direction. The second divided body 40B has a third end portion 43 and a fourth end portion 44 on both sides in the circumferential direction.

[0048] 3 and 4, the first end 41 of the first division body 40A and the third end 43 of the second division body 40B are adjacent to each other in the circumferential direction. The first end 41 and the third end 43 are in contact with each other in the axial direction while being arranged with gaps 45, 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 in the axial direction from one axial end of the first end portion 41 to the axial center portion, and faces one circumferential side.

[0050] The second surface 412 is formed at a right angle to the first surface 411 in the axial center of the first end 41. The second surface 412 extends from the other axial end of the first surface 411 to the other circumferential side and faces the other axial side. The third surface 413 is formed at the other axial side of the first end 41, parallel to the first surface 411 and at a right angle to the second surface 412. The third surface 413 extends in the axial direction from the other circumferential end of the second surface 412 to the other axial end of the first end 41 and faces one circumferential side.

[0051] The third end portion 43 of the second split 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 in the axial direction from one axial end of the third end portion 43 to the axial center portion and faces the other circumferential side.

[0052] The fifth surface 435 is formed at a right angle to the fourth surface 434 in 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 side and faces the one axial side. The sixth surface 436 is formed at the other axial side of the third end 43, parallel to the fourth surface 434 and at a right angle to the fifth surface 435. The sixth surface 436 extends in the axial direction 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 disposed 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 disposed with a gap 46 between them in the circumferential direction. The circumferential dimension of the gap 45 and the circumferential dimension of the gap 46 are substantially the same. With the gaps 45 and 46 thus formed, 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 abut against each other in the axial direction.

[0054] 3 and 5, the second end 42 of the first division body 40A and the fourth end 44 of the second division body 40B are adjacent to each other in the circumferential direction. The second end 42 and the fourth end 44 are in contact with each other in the axial direction while being disposed with gaps 47, 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 42 of the first divided body 40A has a fourth surface 424, a fifth surface 425, and a sixth surface 426. The fourth surface 424, the fifth surface 425, and the sixth surface 426 of the second end 42 have the same configurations as the fourth surface 434, the fifth surface 435, and the sixth surface 436 of the third end 43 (see FIG. 4), respectively, and therefore detailed description thereof will be 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 configurations as the first surface 411, the second surface 412, and the third surface 413 of the first end portion 41 (see FIG. 4), respectively, and therefore detailed description thereof will be omitted.

[0057] The first surface 441 of the fourth end 44 and the fourth surface 424 of the second end 42 are disposed 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 disposed with a gap 48 between them in the circumferential direction. The circumferential dimension of the gap 47 and the circumferential dimension of the gap 48 are substantially the same. With the gaps 47 and 48 thus formed, 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 abut against each other in the axial direction.

[0058] [Effects] According to the seal structure 10 of this embodiment, the labyrinth packing 15 has a purge flow passage 15b for introducing the purge gas A between the labyrinth packing 15 and the outer circumferential surface 53 of the shaft 50. Therefore, in order to introduce the purge gas A, it is not necessary to provide a lantern ring having a communication hole (purge flow passage) as in the conventional case. This makes it possible to introduce the purge gas A with a simple configuration. Also, the assembly work of the seal structure 10 can be easily performed.

[0059] In addition to the first labyrinth gap 31 on the inside of the machine, a second labyrinth gap 32 is also formed on the gland packing 11 side (purge flow passage 15b side) between the labyrinth packing 15 and the outer circumferential surface 53 of the shaft 50. This makes it possible to effectively prevent the sealed fluid on the inside of the machine from passing through the labyrinth gap 30 and flowing toward the gland packing 11 side.

[0060] When the labyrinth packing is formed in an endless ring shape, it is necessary to insert the labyrinth packing from the axial end of the shaft and move the labyrinth packing to a predetermined axial position of the shaft, which requires a lot of time for assembly. In contrast, the labyrinth packing 15 of this embodiment is composed of multiple divided bodies 40 divided in the circumferential direction. Therefore, the labyrinth packing 15 can be attached by combining the multiple divided bodies 40 in the circumferential direction at a predetermined position on the outer circumferential surface 53 of the shaft 50. Therefore, the labyrinth packing 15 can be attached in a shorter time than an endless ring-shaped labyrinth packing.

[0061] The ends 41, 43 (42, 44) of the segments 40 adjacent to each other in the circumferential direction are arranged with gaps 45, 46 (47, 48) between them in the circumferential direction. Therefore, even if the radial dimension of each segment 40 changes due to thermal influence, the gaps 45, 46 (47, 48) can absorb the dimensional change. Furthermore, because the outer peripheral surface 53 of the shaft 50 slides against the respective convex portions 162, 172 of the first labyrinth portion 16 and the second labyrinth portion 17, even if the radial dimension of each convex portion 162, 172 changes due to wear, the gaps 45, 46 (47, 48) can absorb the dimensional change.

[0062] The ends 41, 43 (42, 44) of the segments 40 adjacent to each other in the circumferential direction are in contact with each other in the axial direction. Therefore, these contact portions can prevent the 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 the segments 40 adjacent to each other in the circumferential direction each have 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). By combining these three surfaces, the ends 41, 43 (42, 44) abut against each other in the axial direction with gaps 45, 46 (47, 48) in the circumferential direction. Therefore, with a simple configuration, it is possible to absorb radial dimensional changes due to thermal effects or wear, and to suppress leakage of the purge gases A and B to the gland packing 11 side.

[0064] [others] The seal structure 10 may include a labyrinth packing having a purge flow path instead of the lantern ring 13 in order to introduce the purge gas B. The seal structure 10 of the present embodiment includes the labyrinth packing 15 and the lantern ring 13 for respectively introducing the purge gases A and B, but it is sufficient to include at least the labyrinth packing 15 for introducing the purge gas A. In other words, the pipe 62 through which the purge gas B flows, the second introduction hole 24B, and the lantern ring 13 are provided as necessary and are not essential components in the seal structure of the present disclosure.

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

[0066] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not by the above meaning, and is intended to include all modifications within the scope of the claims and the meaning equivalent thereto. [Explanation of symbols]

[0067] 10. Seal structure 11 Gland packing 15 Labyrinth packing 15b Purge flow path 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 seal structure for sealing between an inner sealed surface and an outer sealed surface which are opposed to each other in a radial direction, annular gland packings in close contact with the inner sealed surface and the outer sealed surface, an annular labyrinth packing provided on an inner side of the engine where the sealed fluid is present, the labyrinth gap being formed between the annular labyrinth packing and the inner sealed surface; a sealing structure, wherein the labyrinth packing has a purge flow passage that opens on an inner peripheral side of the labyrinth packing for introducing a purge gas between the labyrinth packing and the inner sealed surface.

2. The purge flow path opens at a position on the inner circumferential side of the labyrinth packing, the position being on the gland packing side, 2. The seal structure according to claim 1, wherein the labyrinth gap includes a first labyrinth gap formed on the interior side of the engine between the labyrinth packing and the inner sealed surface, and a second labyrinth gap formed on the gland packing side.

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

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

5. One end of the divided bodies adjacent in the circumferential direction is a first surface extending in the axial direction on one axial side and facing one circumferential side; a second surface extending from the other axial end of the first surface to the other circumferential side and facing the other axial side; a third surface extending from the other circumferential end of the second surface to the other axial direction side and facing the one circumferential direction side, The other end of the divided bodies adjacent in the circumferential direction is a fourth surface extending in the axial direction 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 the one axial side; a sixth surface extending from the other circumferential end of the fifth surface to the other axial direction side and facing the other circumferential side; 5. The seal structure according to claim 4, wherein 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, and the second surface and the fifth surface abut against each other in the axial direction.

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