Sealing device

Abstract

This sealing device comprises an annular sealing ring centered on a sealing axis and a retaining ring for holding the sealing ring. The retaining ring has an annular retaining groove that is radially recessed. The sealing ring has a contact surface that can come into axial contact with a low-pressure side groove surface below surfaces defining the retaining groove. The sealing ring is divided into four or more parts circumferentially with respect to the sealing axis. The axial load center radius is a radial distance between the sealing axis and an axial load center that is an intermediate position between the radially outer end of the contact surface and the position that is most radially inner in the sealing ring. The inner end radius is the radial distance between the sealing axis and the most radially inner end of the contact surface.The ratio of the inner end radius to the axial load center radius is 1.20 or less.

Description

Technical field

[0001] The present invention relates to a sealing device that is mounted around a shaft.

[0002] Priority is claimed for the Japanese patent application No. 2023-083114 filed on May 19, 2023, the contents of which are incorporated herein by reference. State of the art

[0003] For example, a sealing device that is attached around a shaft is disclosed in PTL 1 below.

[0004] This sealing device comprises a sealing ring facing an outer circumferential surface of a shaft and a sealing retainer ring (sealing ring holder) that holds the sealing ring. The sealing ring has an annular shape around a sealing axis on a rotational axis of the shaft. The sealing ring has an annular cylinder and several annular sealing ribs that project from an inner circumferential surface of the cylinder to a radial inner surface with respect to the sealing axis.

[0005] In a technique described in PTL 1, a guide pin is provided which guides movement of the sealing ring in a radial direction with respect to the axis, so that preload of the sealing ring in the radial direction with respect to the axis is suppressed. List of citations from patent literature

[0006] [PTL 1] Japanese Unexamined Patent Application Publication No. 2000-097350 Summary of Invention Technical problem

[0007] In the sealing device described in PTL 1, the sealing ring can absorb an axial load from a high-pressure side with respect to the sealing ring, and a moment can be generated that tends to tilt the sealing axis of the sealing ring with respect to the axis of rotation of the shaft. In this case, if the sealing axis is tilted with respect to the axis of rotation due to this moment, deterioration of sealing performance, damage to a sealing element, such as the sealing rib, or the like may occur.

[0008] Therefore, one objective of the present disclosure is to provide a sealing device capable of suppressing deterioration of sealing performance and damage to a sealing element. Solution to the problem

[0009] A sealing device as an aspect according to the invention for achieving the above objective comprises a sealing ring having an annular shape around a sealing axis, and a sealing retaining ring having an annular shape around the sealing axis and holding the sealing ring from an outer circumferential side of the sealing ring.

[0010] The sealing retaining ring has an annular retaining groove that extends radially in a direction relative to the sealing axis from an inner radial surface and an outer radial surface to a radial outer surface. The sealing ring comprises a sealing cylinder, which has an annular shape around the sealing axis and is partially inserted into the retaining groove of the sealing retaining ring, and several sealing elements, which also have an annular shape around the sealing axis and are arranged on an inner circumferential surface of the sealing cylinder so that they are attached to the sealing cylinder. The sealing cylinder has, in an axial direction in which the sealing axis extends, a high-pressure side surface facing the axial high-pressure side and a low-pressure side surface facing the axial low-pressure side.The retaining groove is defined by a retaining groove bottom surface facing the radial inner side, a high-pressure side retaining groove surface facing a high-pressure side surface of the sealing cylinder in the axial direction, and a low-pressure side retaining groove surface facing a low-pressure side surface of the sealing cylinder in the axial direction. At least a portion of the low-pressure side surface of the sealing cylinder forms a contact surface of the sealing ring, enabling contact with the low-pressure side retaining groove surface of the sealing retaining ring in the axial direction. The sealing ring is divided into four or more parts in one circumferential direction with respect to the sealing axis. The ratio of an inner end radius to an axial load center radius is 1.20 or less.The axial load center radius is a radial distance between the sealing axis and an axial load center that is an intermediate position in the radial direction between a position closest to the radial outer surface under sections of the sealing ring in contact with the sealing retaining ring, and a position of the sealing ring closest to the radial inner surface. The inner end radius is a radial distance between the sealing axis and a position of an end of the contact surface that is closest to the radial inner surface.

[0011] The sealing ring absorbs the axial load from a high-pressure fluid present on the high-pressure side relative to the sealing ring. This axial load can exert a moment on the sealing ring that tends to tilt the sealing axis relative to the shaft's axis of rotation. If the sealing ring is divided into four or more sections circumferentially, such a moment will cause the sealing axis to tilt relative to the shaft's axis of rotation, potentially leading to a deterioration of sealing performance, damage to the sealing element (such as a sealing rib), or similar issues. In this case, the generation of the moment acting on the sealing ring and the tilting of its sealing axis relative to the shaft's axis of rotation can be suppressed. Advantageous effects of the invention

[0012] According to one aspect of the present disclosure, it is possible to suppress deterioration of sealing performance and damage to a sealing element due to an inclination of a sealing axis of a sealing ring with respect to a rotation axis of a shaft. Brief description of the drawings Fig. Figure 1 is a cross-sectional view of a sealing device according to a first embodiment of the present disclosure. Fig. 2 is a cross-sectional view along line II-II in Fig. 1. Fig. Figure 3 is a cross-sectional view of a sealing device in a comparative example. Fig. Figure 4 is a graph showing a relationship between the number of subdivisions of the sealing ring and an upper limit ratio. Fig. Figure 5 is a cross-sectional view of a sealing device in a second embodiment according to the present disclosure. Fig. Figure 6 is a cross-sectional view of a sealing device according to a third embodiment of the present disclosure. Fig. Figure 7 is a cross-sectional view of a sealing device in a fourth embodiment according to the present disclosure. Description of embodiments

[0013] Below, various embodiments and modification examples of a sealing device according to the present disclosure are described with reference to the drawings. [First embodiment]

[0014] A first embodiment of a sealing device is described with reference to Fig. 1 to 3 described.

[0015] As in Fig. As shown in Figure 1, a sealing device S in the present embodiment is a sealing device arranged around a shaft 1, which is rotatable about an axis of rotation Ar. The sealing device S comprises a sealing ring 10, which has an annular shape around a sealing axis As, and a sealing retaining ring 20, which holds the sealing ring 10 in an annular shape around the sealing axis As. The sealing retaining ring 20 has a retaining groove 25 into which a portion of the sealing ring 10 is inserted.

[0016] Here, a direction in which the sealing axis As extends is referred to as an axial direction Da, a radial direction with respect to the sealing axis As is simply referred to as a radial direction Dr, and a circumferential direction with respect to the sealing axis As is simply referred to as a circumferential direction Dc. Furthermore, one side of each side in the axial direction Da is referred to as an axial high-pressure side Dah, and the other side is referred to as an axial low-pressure side Dal. Additionally, a side that is closer to the sealing axis As in the radial direction Dr is referred to as a radial inner side Dri, and a side that is farther from the sealing axis As in the radial direction Dr is referred to as a radial outer side Dro.In the present embodiment, in a state in which the sealing device S is arranged around the shaft 1, the sealing axis As of the sealing device S is basically located on the rotation axis Ar described above.

[0017] The sealing device S serves to prevent a high-pressure fluid (for example, steam) that is present on the axial high-pressure side Dah with respect to the sealing device S from escaping to the axial low-pressure side Dal of the sealing device S along an outer circumferential surface of the shaft 1.

[0018] The sealing ring 10 comprises a sealing cylinder 11 and several sealing pieces 19. The sealing cylinder 11 has an annular shape around the sealing axis As. The several sealing pieces 19 are arranged in an annular shape around the sealing axis As in the axial direction Da. The several sealing pieces 19 are located on an inner circumferential side of the sealing cylinder 11 and are attached to the sealing cylinder 11. The ends of the several sealing pieces 19 on the radial inner side Dri face the outer circumferential surface of the shaft 1 with a small gap between them.

[0019] The sealing cylinder 11 has a cylinder body 12 and a retained section 13 which is inserted into the retaining groove 25. The cylinder body 12 has an inner circumferential surface 12i facing the radial inner side Dri, an outer circumferential surface 12o facing the radial outer side Dro, a high-pressure side surface 12h facing the axial high-pressure side Dah, and a low-pressure side surface 12l facing the axial low-pressure side Dal.

[0020] The held section 13 comprises a held leg section 14 projecting from the outer circumferential surface 12o to the radial outer surface Dro, and a hook section 15 provided at one end of the held leg section 14 on the radial outer surface Dro and projecting from the held leg section 14 towards the axial high-pressure side Dah. The held leg section 14 has a leg high-pressure side surface 14h facing the axial high-pressure side Dah and a leg low-pressure side surface 14l facing the axial low-pressure side Dal. The hook section 15 has a hook outer circumferential surface 15o facing the radial outer side Dro, a hook inner circumferential surface 15i facing the radial inner side Dri, a hook high-pressure side surface 15h facing the axial high-pressure side Dah, and a hook low-pressure side surface 15l facing the axial low-pressure side Dal.The body low-pressure side surface 12l, the leg low-pressure side surface 14l, and the hook low-pressure side surface 15l are flush with each other. The body low-pressure side surface 12l, the leg low-pressure side surface 14l, and the hook low-pressure side surface 15l form a low-pressure side surface 11l of the sealing cylinder 11. The hook outer circumferential surface 15o extends from one end of the hook low-pressure side surface 15l on the radial outer side Dro to the axial high-pressure side Dah. The hook inner circumferential surface 15i extends from one end of the leg high-pressure side surface 14h on the radial outer side Dro to the axial high-pressure side Dah. The leg high-pressure side surface 14h is located on the axial low-pressure side Dal with respect to the body high-pressure side surface 12h.The hook high-pressure side surface 15h is located on the axial low-pressure side Dal with respect to the body high-pressure side surface 12h and on the axial high-pressure side Dah with respect to the leg high-pressure side surface 14h. The hook high-pressure side surface 15h connects one end of the hook outer circumferential surface 15o on the axial high-pressure side Dah and one end of the hook inner circumferential surface 15i on the axial high-pressure side Dah. The body high-pressure side surface 12h, the leg high-pressure side surface 14h, and the hook high-pressure side surface 15h form a high-pressure side surface 11h of the sealing cylinder 11.

[0021] The sealing retaining ring 20 comprises a retaining ring cylinder 22, a high-pressure side wall element 23, and a low-pressure side wall element 24. The retaining ring cylinder 22 has a cylindrical shape around the sealing axis As. The high-pressure side wall element 23 includes a first high-pressure side wall element 23a and a second high-pressure side wall element 23b. The first high-pressure side wall element 23a is located on the axial high-pressure side Dah of the retaining ring cylinder 22 and projects from a section of the retaining ring cylinder 22 on the axial high-pressure side Dah to the radial inner side Dri. The second high-pressure side wall element 23b is located on the radial inner side Dri of the first high-pressure side wall element 23a and projects from a section of the first high-pressure side wall element 23a on the radial inner side Dri to the axial low-pressure side Dal.The low-pressure side wall element 24 is provided on the axial low-pressure side Dal of the retaining ring cylinder 22 and projects from a section of the retaining ring cylinder 22 on the axial low-pressure side Dal to the radial inner side Dri. The retaining groove 25 is formed between the high-pressure side wall element 23 and the low-pressure side wall element 24 in the axial direction Da on the radial inner side Dri of the retaining ring cylinder 22.

[0022] The retaining groove 25 is an annular groove that is recessed towards the radial outer side Dro and centered on the sealing axis As. The retaining groove 25 has a hook insertion groove section 27 and a leg insertion groove section 28.

[0023] The hook insertion groove section 27 is a section into which the hook section 15 of the sealing ring 10 is inserted. The width of the hook insertion groove section 27 in the axial direction Da is greater than the width of the hook section 15 in the axial direction Da. The hook insertion groove section 27 is defined by a retaining groove bottom surface 25b, a radial movement limiting surface 27r, a first high-pressure side retaining groove side surface 27h, and a first low-pressure side retaining groove side surface 27l. The retaining groove bottom surface 25b is formed on a surface of the retaining ring cylinder 22 that faces the radial inner side Dri. The retaining groove bottom surface 25b faces the hook outer circumferential surface 15o in the radial direction Dr. The radial movement limiting surface 27r is formed on a surface of the second high-pressure side wall element 23b, which faces the radial outer side Dro. The radial movement limiting surface 27r faces the retaining groove bottom surface 25b in the radial direction Dr.Furthermore, the radial movement limiting surface 27r of the hook inner circumferential surface 15i faces radially Dr. The first high-pressure side retaining groove surface 27h is formed on a surface of the first high-pressure side wall element 23a that faces the axial low-pressure side Dal. The first high-pressure side retaining groove surface 27h faces the hook high-pressure side surface 15h in the axial direction Da. The second high-pressure side wall element 23b of the sealing retaining ring 20 is in a back-to-back relationship with the radial movement limiting surface 27r and has a high-pressure side inner circumferential surface 29r that faces the radial inner side Dri. The high-pressure side inner circumferential surface 29r faces the outer circumferential surface 12o of the sealing cylinder 11 in the radial direction Dr. The first low-pressure side retaining groove surface 27l is formed on a surface of the low-pressure side wall element 24 that faces the axial high-pressure side Dah.The first low-pressure side retaining groove surface 27l faces the first high-pressure side retaining groove surface 27h in the axial direction Da. Furthermore, the first low-pressure side retaining groove surface 27l faces the hook high-pressure side surface 15h in the axial direction Da.

[0024] The leg insertion groove section 28 is a section into which the retained leg section 14 of the sealing ring 10 is inserted. The width of the leg insertion groove section 28 in the axial direction Da is greater than the width of the retained leg section 14 in the axial direction Da and less than the width of the hook section 15 in the axial direction Da. Furthermore, the leg insertion groove section 28 is located on the radial inner side Dri of the hook insertion groove section 27 and communicates with the hook insertion groove section 27. The leg insertion groove section 28 is defined by a second high-pressure side retaining groove surface 28h and a second low-pressure side retaining groove surface 28l. The second high-pressure side retaining groove surface 28h is formed on a surface of the second high-pressure side wall element 23b that faces the axial low-pressure side Dal. The second high-pressure side retaining groove surface 28h faces the leg high-pressure side surface 14h in the axial direction Da.The second high-pressure side retaining groove surface 28h and the first high-pressure side retaining groove surface 27h form a high-pressure side retaining groove surface 25h of the retaining groove 25. The second low-pressure side retaining groove surface 28l is formed on a surface of the low-pressure side wall element 24 that faces the axial high-pressure side Dah. The second low-pressure side retaining groove surface 28l faces the second high-pressure side retaining groove surface 28h in the axial direction Da. Furthermore, the second low-pressure side retaining groove surface 28l faces the lower low-pressure side surface 14l in the axial direction Da. The second low-pressure side retaining groove surface 28l is flush with the first low-pressure side retaining groove surface 27l. The second low-pressure side retaining groove surface 28l and the first low-pressure side retaining groove surface 27l form a low-pressure side retaining groove surface 25l of the retaining groove 25.

[0025] A gap Ga exists between the first high-pressure side retaining groove surface 27h and the hook high-pressure side surface 15h, which face each other in the axial direction Da. Furthermore, a gap Gr exists between the high-pressure side inner circumferential surface 29r and the body outer circumferential surface 12o, which face each other in the radial direction Dr. Thus, since the gaps Ga and Gr exist between the sealing ring 10 and the sealing retainer ring 20, the sealing ring 10 can be inclined relative to the sealing retainer ring 20.

[0026] A section of the low-pressure side surface 11l of the sealing ring 10, which lies on the radial outer side Dro, forms a contact surface 11C which can come into contact with the low-pressure side retaining groove surface 25l of the retaining groove 25.

[0027] Here, an intermediate position in the radial direction Dr between a position P1o of the sealing ring 10, which is closest to the radial outer surface Dro, under sections of the sealing ring 10 that are in contact with the sealing retainer ring 20, and a position P1i of the sealing ring 10, which is closest to the radial inner surface Dri, is designated as an axial load center P1c. The position P1i of the sealing ring 10, which is closest to the radial inner surface Dri, is one end of the sealing element 19 on the radial inner surface Dri. Furthermore, the position P1o of the sealing ring 10, which is closest to the radial outer surface Dro, under the sections of the sealing ring 10 that are in contact with the sealing retainer ring 20, is one end of the contact surface 11C on the radial outer surface Dro in the present embodiment.The sealing ring 10 absorbs an axial load F directed from the high-pressure fluid present on the axial high-pressure side Dah of the sealing arrangement S towards the axial low-pressure side Dal. The axial load center P1c described above is the center of a region in the radial direction Dr where the axial load F is absorbed by the sealing ring 10.

[0028] Furthermore, a distance in the radial direction Dr between the axial load center P1c and the sealing axis As is referred to as an axial load center radius R1. Additionally, a distance in the radial direction Dr between the sealing axis As and a position P2 of the end of the contact surface 11C that is closer to the radial inner surface Dri is defined as an inner end radius R2.

[0029] In the present embodiment, the ratio (R2 / R1) of the inner end radius R2 to the axial load center radius R1 is 1.0 or less. That is, R2 / R1 ≤ 1.

[0030] As in Fig. As shown in Figure 2, both the sealing ring 10 and the sealing retaining ring 20 are divided into several parts in the circumferential direction Dc in the present embodiment. In particular, for example, the sealing ring 10 is divided into four parts in the circumferential direction Dc, and the sealing retaining ring 20 is divided into two parts in the circumferential direction Dc.

[0031] Next, in order to describe the effects of the sealing device S in the present embodiment, a comparative example will be given with reference to Fig. 3 described.

[0032] A sealing device Sx in the comparative example also includes the sealing ring 10 and a sealing retainer ring 20x, which holds the sealing ring 10, as in the sealing device S in the present embodiment. The sealing ring 10 in the comparative example is completely identical to the sealing ring 10 in the present embodiment. The sealing retainer ring 20x in the comparative example is essentially identical to the sealing retainer ring 20 in the present embodiment. Therefore, the sealing retainer ring 20x in the comparative example also has the retainer ring cylinder 22, the high-pressure side wall element 23, and a low-pressure side wall element 24x, as in the sealing retainer ring 20 in the present embodiment. A retaining groove 25x in the comparative example is also formed between the high-pressure side wall element 23 and the low-pressure side wall element 24x in the axial direction Da on the radial inner side Dri of the retainer ring cylinder 22.In this comparative example as well, a section of the low-pressure side surface 11l of the sealing ring 10, which can come into contact with the low-pressure side retaining groove surface 25l of the retaining groove 25x, forms a contact surface 11Cx. Furthermore, in this comparative example as well, since the gaps Ga and Gr are present between the sealing ring 10 and the retaining ring 20x, the sealing ring 10 can be inclined relative to the retaining ring 20x.

[0033] As with the low-pressure side wall element 24 in the present embodiment, the low-pressure side wall element 24x in the comparative example is also provided on the axial low-pressure side Dal of the retaining ring cylinder 22 and projects from the section of the retaining ring cylinder 22 on the axial low-pressure side Dal to the radial inner side Dri. However, the amount of projection of the low-pressure side wall element 24x to the radial inner side Dri in the comparative example is smaller than the amount of projection of the low-pressure side wall element 24 to the radial inner side Dri in the present embodiment. For this reason, the position P2 of the end of the contact surface 11Cx on the radial inner side Dri in the comparative example is located on the radial outer side Dro, whereas the position P2 of the end of the contact surface 11C on the radial inner side Dri in the present embodiment is located on the radial outer side Dro.Consequently, the ratio (R2 / R1) of the inner end radius R2 to the axial load center radius R1 in the comparison example is larger than the ratio (R2 / R1) of the inner end radius R2 to the axial load center radius R1 in the present embodiment. In particular, the ratio (R2 / R1) in the comparison example is, for instance, approximately 1.25.

[0034] The sealing ring 10 in the comparison example is also divided into four parts in the circumferential direction Dc, as in the sealing ring 10 in the present embodiment.

[0035] In the comparative example described above, when the sealing ring 10 absorbs the axial load F from the high-pressure fluid present on the axial high-pressure side Dah, a moment M acts which displaces a section of the sealing axis As on the axial high-pressure side Dah relative to the axis of rotation Ar by position P2 of the end of the contact surface 11Cx on the radial inner side Dri to the radial outer side Dro. In particular, in the case described in Fig. In the example shown, a counterclockwise moment M acts on a section above the sealing axis As with position P2 of the end of the contact surface 11Cx on the radial inner side Dri as a center, and a counterclockwise moment M acts on a section below the sealing axis As with position P2 of the end of the contact surface 11Cx on the radial inner side Dri as a center.

[0036] In a case where the sealing ring 10 is not divided in the circumferential direction Dc, the counterclockwise moment M acting on the section above the sealing axis As is canceled out by the counterclockwise moment M acting on the section below the sealing axis As. Therefore, the sealing axis As is not inclined with respect to the axis of rotation Ar.

[0037] However, if the number of subdivisions of the sealing ring 10 in the circumferential direction Dc increases, the amount by which a moment M in a cross-section containing the sealing axis As at a predetermined position in the circumferential direction Dc is canceled out by a moment M in a cross-section containing the sealing axis As at a different position in the circumferential direction Dc decreases. For this reason, if the number of subdivisions of the sealing ring 10 in the circumferential direction Dc is large, the sealing axis As is inclined with respect to the axis of rotation Ar, which can cause deterioration of sealing performance, damage to the sealing element 19, or the like.

[0038] As in the comparative example, in a case where the ratio (R2 / R1) is approximately 1.25 and the sealing ring 10 is divided into four parts in the circumferential direction Dc, the sealing axis As is inclined with respect to the axis of rotation Ar due to the axial load F received from the high-pressure fluid.

[0039] In the present embodiment, as in the comparative example, the sealing ring 10 is divided into four parts in the circumferential direction Dc. However, since the ratio (R2 / R1) is at most 1.0 or less, even when the sealing ring 10 absorbs the axial load F from the high-pressure fluid, no moment M acts on the individual parts of the sealing ring 10, which are divided into four parts, that would cause the sealing axis As to be inclined with respect to the axis of rotation Ar. Therefore, in the present embodiment, even when the axial load F from the high-pressure fluid is received, the sealing axis As of the sealing ring 10 is not significantly inclined with respect to the axis of rotation Ar, so that deterioration of sealing performance or damage to the sealing element 19 can be suppressed. [Second embodiment]

[0040] A second embodiment of the sealing device is described with reference to Fig. 4 and Fig. 5 described.

[0041] Fig. Figure 4 is a graph showing a relationship between the number of subdivisions of the sealing ring and an upper limit ratio (R2 / R1) where the sealing axis As is not significantly inclined with respect to the rotation axis Ar, even when the sealing ring absorbs the axial load F from the high-pressure fluid.

[0042] As described above, as the number of subdivisions of the sealing ring in the circumferential direction Dc increases, the amount by which the moment M in the cross-section containing the sealing axis As at the predetermined position in the circumferential direction Dc is canceled out by the moment M in the cross-section containing the sealing axis As at a different position in the circumferential direction Dc decreases. For this reason, as shown in the graph of Fig. Figure 4 shows that an upper bound ratio U (R2 / R1) decreases as the number of subdivisions increases. However, the upper bound ratio U (R2 / R1) does not become less than 1.0.

[0043] In particular, if the number of subdivisions of the sealing ring is 4, the upper limit ratio U (R2 / R1) is 1.2. Therefore, in a case where the number of subdivisions of the sealing ring is four, the ratio (R2 / R1) is set to 1.2 or less, so that even if the sealing ring absorbs the axial load F from the high-pressure fluid, the sealing axis As is not substantially inclined with respect to the axis of rotation Ar. For sealing ring 10 in the comparison example described above, the number of subdivisions is 4 and the ratio (R2 / R1) is 1.25. Therefore, if sealing ring 10 absorbs the axial load F from the high-pressure fluid, the sealing axis As is inclined with respect to the axis of rotation Ar.

[0044] If the number of subdivisions of the sealing ring is 6, the upper limit ratio U (R2 / R1) is 1.1. For this reason, in a case where the number of subdivisions of the sealing ring is 6, the ratio (R2 / R1) is set to 1.1 or less, so that even if the sealing ring absorbs the axial load F from the high-pressure fluid, the sealing axis As is not substantially inclined with respect to the axis of rotation Ar.

[0045] If the number of subdivisions of the sealing ring is 8, the upper limit ratio U (R2 / R1) is 1.06. Therefore, in a case where the number of subdivisions of the sealing ring is 8, the ratio (R2 / R1) is set to 1.06 or less, so that even if the sealing ring absorbs the axial load F from the high-pressure fluid, the sealing axis As is not substantially inclined with respect to the axis of rotation Ar.

[0046] The sealing device in the present embodiment is a sealing device based on the aspect described above. As in Fig. As shown in Figure 5, a sealing device Sa in the present embodiment also includes the sealing ring 10 and a sealing retainer ring 20a, which holds the sealing ring 10, as in the sealing device S in the first embodiment. The sealing ring 10 in the present embodiment has the same number of subdivisions as the sealing ring 10 in the first embodiment, that is, four. The sealing retainer ring 20a in the present embodiment also includes the retainer ring cylinder 22, the high-pressure side wall element 23, and a low-pressure side wall element 24a, as in the sealing retainer ring 20.The amount of projection of a low-pressure side wall element 24a in the present embodiment from the retaining ring cylinder 22 to the radial inner surface Dri is greater than the amount of projection of the low-pressure side wall element 24x in the comparative example described above, from the retaining ring cylinder 22 to the radial inner surface Dri, but less than the amount of projection of the low-pressure side wall element 24 in the first embodiment, from the retaining ring cylinder 22 to the radial inner surface Dri. In this relationship, the ratio (R2 / R1) of the sealing device Sa in the present embodiment is greater than the ratio (R2 / R1) in the first embodiment and amounts to 1.05.

[0047] The ratio (R2 / R1) of the sealing device Sa in the present embodiment is 1.05, which is greater than the ratio (R2 / R1) of the sealing device S in the first embodiment, but equal to or less than the upper limit ratio U (R2 / R1 = 1.2) in a case where the number of subdivisions is 4. Therefore, even in the present embodiment, even when the axial load F is absorbed by the high-pressure fluid, the sealing axis As of the sealing ring 10 is not significantly inclined with respect to the axis of rotation Ar, so that deterioration of sealing performance or damage to the sealing element 19 can be suppressed.

[0048] In the sealing device Sa of the present embodiment, the number of subdivisions of the sealing ring 10 is four. However, in a case where the number of subdivisions of the sealing ring 10 is six, the ratio (R2 / R1) can be equal to or less than the upper limit ratio U (R2 / R1 = 1.1), and in a case where the number of subdivisions of the sealing ring 10 is eight, the ratio (R2 / R1) can be equal to or less than the upper limit ratio U (R2 / R1 = 1.06). [Third embodiment]

[0049] A third embodiment of the sealing device is described with reference to Fig. 6 described.

[0050] As in Fig. As shown in Figure 6, a sealing device Sb in the present embodiment also includes a sealing ring 10b and a sealing retaining ring 20b, which holds the sealing ring 10b, as in the sealing device S in the first embodiment.

[0051] The sealing ring 10b in the present embodiment also comprises a sealing cylinder 11b and the multiple sealing pieces 19, as in the sealing ring 10 of the first embodiment. The sealing cylinder 11b has an annular shape around the sealing axis As. The multiple sealing pieces 19 are arranged in an annular shape around the sealing axis As in the axial direction Da. The multiple sealing pieces 19 are arranged on the inner circumferential side of the sealing cylinder 11b and are attached to the sealing cylinder 11b. As described above, the sealing cylinder 11b of the present embodiment has the cylinder's inner circumferential surface 12i, from which the multiple sealing pieces 19 project towards the radial inner side Dri. The sealing cylinder 11b further comprises a projection section 16 that projects from a section of the cylinder's inner circumferential surface 12i on the axial low-pressure side Dal towards the radial inner side Dri.A surface of the projecting section 16, which faces the axial low-pressure side Dal, is part of the low-pressure side surface 11l of the sealing cylinder 11b. In addition, the sealing ring 10b in the present embodiment, as in the first embodiment, is also divided into four parts in the circumferential direction Dc.

[0052] The sealing retaining ring 20b in the present embodiment also comprises the retaining ring cylinder 22, the high-pressure side wall element 23, and a low-pressure side wall element 24b, as in the sealing retaining ring 20 in the first embodiment. The retaining groove 25 in the present embodiment is also formed between the high-pressure side wall element 23 and the low-pressure side wall element 24b in the axial direction Da on the radial inner surface Dri of the retaining ring cylinder 22. The projection of the low-pressure side wall element 24b from the retaining ring cylinder 22 to the radial inner surface Dri in the present embodiment is greater than the projection of the low-pressure side wall element 24b from the retaining ring cylinder 22 to the radial inner surface Dri in the first embodiment.For this reason, in the present embodiment, one end of the low-pressure side retaining groove surface 25l is located on the radial inner side Dri, whereas in the first embodiment, the end of the low-pressure side retaining groove surface 25l is located on the radial inner side Dri. The low-pressure side retaining groove surface 25l is in contact with the low-pressure side surface 11l of the sealing cylinder 11b. Therefore, in the present embodiment, at least a portion of the low-pressure side surface 11l of the sealing cylinder 11b forms a contact surface 11Cb of the sealing ring 10b.

[0053] In the present embodiment, the position P2 of the end of the contact surface 11Cb on the radial inner side Dri is located on the radial inner side Dri with respect to the inner circumferential surface 12i of the sealing cylinder 11b, and in the first embodiment, it is located on the radial inner side Dri with respect to the position P2 of the end of the contact surface 11C on the radial inner side Dri. For this reason, the inner end radius R2, which is the distance in the radial direction Dr between the sealing axis As and the end of the contact surface 11Cb closest to the radial inner side Dri, is smaller than the inner end radius R2 in the first embodiment.

[0054] As described above, since the inner end radius R2 in the present embodiment is smaller than the inner end radius R2 in the first embodiment, the ratio (R2 / R1) in the present embodiment is smaller than the ratio (R2 / R1) in the first embodiment. Therefore, the ratio (R2 / R1) in the present embodiment, like the ratio (R2 / R1) in the first embodiment, is also 1.0 or less. Therefore, even when the axial load F is absorbed by the high-pressure fluid, the sealing axis As of the sealing ring 10b is not significantly inclined with respect to the axis of rotation Ar in the present embodiment, thus preventing deterioration of sealing performance or damage to the sealing element 19.

[0055] As described above, as the number of subdivisions of the sealing ring increases, the upper limit ratio U (R2 / R1) gradually decreases. Therefore, in a case where the number of subdivisions of the sealing ring is 6 or more, as in the present embodiment, it is effective to provide the projecting section 16 in the sealing cylinder 11b of the sealing ring 10b in order to reduce the inner end radius R2. [Fourth embodiment]

[0056] A fourth embodiment of the sealing device is described with reference to Fig. 7 described.

[0057] As in Fig. As shown in Figure 7, a sealing device Sc in the present embodiment also includes the sealing ring 10 and a sealing retaining ring 20c, which holds the sealing ring 10, as in the sealing device S in the first embodiment.

[0058] The sealing ring 10 in the present embodiment is the same as the sealing ring 10 in the first embodiment.

[0059] The sealing retaining ring 20c in the present embodiment comprises a retaining ring body 21 and a spacer 30. The retaining ring body 21 has the retaining ring cylinder 22, the high-pressure side wall element 23, and a low-pressure side wall element 24c, as in the sealing retaining ring 20 in the first embodiment. An annular groove 26, which is recessed towards the radial outer surface Dro and which is centered about the sealing axis As, is formed between the high-pressure side wall element 23 and the low-pressure side wall element 24c in the axial direction Da on the radial inner surface Dri of the retaining ring cylinder 22.The groove 26 is defined by the retaining groove bottom surface 25b, which faces the radial inner side Dri, the high-pressure side retaining groove side surface 25h, which faces the high-pressure side surface 11h of the sealing cylinder 11 in the axial direction Da, and a low-pressure side groove side surface 26l, which faces the low-pressure side surface 11l of the sealing cylinder 11 in the axial direction Da. The retaining groove bottom surface 25b is formed on a surface of the retaining ring cylinder 22 that faces the radial inner side Dri. The high-pressure side retaining groove side surface 25h is formed on a surface of the high-pressure side wall element 23 that faces the axial low-pressure side Dal. The low-pressure side groove side surface 26l is formed on a surface of the low-pressure side wall element 24c that faces the axial high-pressure side Dah.

[0060] The spacer 30 comprises an annular disk section 31, which has an annular disk shape around the sealing axis As, and a tubular section 32, which has a cylindrical shape around the sealing axis As. The tubular section 32 extends from a section of the annular disk section 31 on the radial outer side Dro to the axial high-pressure side Dah. The inner circumferential surface of the tubular section 32 faces or comes into contact with the outer circumferential surface 15o of the sealing cylinder 11. The annular disk section 31 has a first disk side surface 31a, which faces the axial high-pressure side Dah, and a second disk side surface 31b, which faces the axial low-pressure side Dal. The annular disk section 31 is located between the low-pressure side surface 11l of the sealing cylinder 11 and the low-pressure side groove surface 26l of the groove 26.The first disc side surface 31a of the ring disc section 31 comes into contact with the low-pressure side surface 11l of the sealing cylinder 11. The second disc side surface 31b of the ring disc section 31 comes into contact with the low-pressure side groove side surface 26l of the groove 26. One end of the ring disc section 31 on the radial inner side Dri projects from one end of the low-pressure side wall element 24c of the retaining ring body 21 on the radial inner side Dri to the radial inner side Dri.

[0061] The retaining groove 25c in the present embodiment is formed by the groove 26 of the retaining ring body 21 and the spacer 30. The retaining groove 25c is defined by a surface comprising the retaining groove bottom surface 25b of the groove 26, the high-pressure side retaining groove surface 25h of the groove 26, a portion of the low-pressure side groove surface 26l of the groove 26, and the first disk surface 31a of the spacer 30. A low-pressure side retaining groove surface 25lc of the retaining groove 25c comprises a portion of the low-pressure side groove surface 26l of the groove 26 and the first disk surface 31a of the spacer 30.

[0062] A contact surface 11Cc in the surface of the sealing ring 10, which can come into contact with the sealing retaining ring 20c in the axial direction Da, is a section in the low-pressure side surface 11l of the sealing cylinder 11 that can come into contact with the first disk side surface 31a of the spacer 30, which is a section of the low-pressure side retaining groove side surface 25lc of the retaining groove 25c. In the present embodiment, the position P2 of the end of the contact surface 11Cc on the radial inner side Dri is an end of the first disk side surface 31a of the spacer 30 on the radial inner side Dri. Therefore, the inner end radius R2 in the present embodiment is a distance in the radial direction Dr between the sealing axis As and the end of the first disk side surface 31a of the spacer 30 on the radial inner side Dri.Furthermore, in the present embodiment, the ratio (R2 / R1) of the inner end radius R2 to the axial load center radius R1 is 1.0 or less, as in the first embodiment. Therefore, even in the present embodiment, when the axial load F is absorbed by the high-pressure fluid, the sealing axis As of the sealing ring 10 is not significantly inclined with respect to the axis of rotation Ar, thus preventing deterioration of sealing performance or damage to the sealing element 19.

[0063] In the present embodiment, the position P2 of the end of the contact surface 11Cc on the radial inner side Dri is located on the radial inner side Dri relative to the end of the low-pressure side wall element 24c of the retaining ring body 21 on the radial inner side Dri. Therefore, in a case where, for any reason, the end of the low-pressure side wall element 24c on the radial inner side Dri is located on the radial outer side Dri relative to the end of the low-pressure side wall element 24 or 24a on the radial inner side Dri in the first or second embodiment, and the ratio (R2 / R1) cannot be made equal to or less than the upper limit ratio U (R2 / R1), it is effective to provide the spacer 30 as in the present embodiment. [Modification example]

[0064] The sealing devices S, Sa, Sb and Sc in the embodiments described above are ribbed sealing devices or labyrinth sealing devices, each having more ribs than the multiple sealing pieces 19. However, the sealing devices can also be brush sealing devices, each having more wires than multiple sealing pieces, sheet sealing devices, each having more thin plates than multiple sealing pieces, or the like.

[0065] Furthermore, the present disclosure is not limited to each of the embodiments described above. Various additions, modifications, substitutions, partial deletions, and the like may be made without deviating from the conceptual idea and the core of the present invention, which are derived from the content defined in the claims and their equivalents. [Additional information]

[0066] The sealing devices S, Sa, Sb and Sc in the embodiments and modification examples described above are understood, for example, as follows.

[0067] (1) A sealing device in a first aspect comprises a sealing ring 10 or 10b having an annular shape around a sealing axis As and a sealing retaining ring 20, 20a, 20b or 20c having an annular shape around the sealing axis As and holding the sealing ring 10 or 10b from an outer circumferential side of the sealing ring 10 or 10b.

[0068] The sealing retaining ring 20, 20a, 20b, or 20c has an annular retaining groove 25 or 25c, which extends radially in a direction Dr with respect to the sealing axis As from a radial inner surface Dri and the radial outer surface Dro to a radial outer surface Dro. The sealing ring 10 or 10b has a sealing cylinder 11 or 11b, which has an annular shape around the sealing axis As and which is partially inserted into the retaining groove 25 or 25c of the sealing retaining ring 20, 20a, 20b, or 20c, and several sealing elements 19, which have an annular shape around the sealing axis As and which are arranged on an inner circumferential side of the sealing cylinder 11 or 11b such that they are attached to the sealing cylinder 11 or 11b.The sealing cylinder 11 or 11b comprises an axial high-pressure side Dah and an axial low-pressure side Dal in an axial direction Da in which the sealing axis As extends, and a high-pressure side surface 11h facing the axial high-pressure side Dah, and a low-pressure side surface 11l facing the axial low-pressure side Dal. The retaining groove 25 or 25c is defined by a retaining groove bottom surface 25b facing the radial inner side Dri, a high-pressure side retaining groove side surface 25h facing a high-pressure side surface 11h of the sealing cylinder 11 or 11b in the axial direction Da, and a low-pressure side retaining groove side surface 25l or 25lc facing a low-pressure side surface 11l of the sealing cylinder 11 or 11b in the axial direction Da.At least a portion of the low-pressure side surface 11l of the sealing cylinder 11 or 11b forms a contact surface 11C, 11Cb, or 11Cc of the sealing ring 10 or 10b, which allows contact with the low-pressure side retaining groove surface 25l and 25lc of the sealing retaining ring 20, 20a, 20b, or 20c in the axial direction Da. The sealing ring 10 or 10b is divided into four or more parts in a circumferential direction Dc with respect to the sealing axis As. The ratio (R2 / R1) of the inner end radius R2 to the axial load center radius R1 is 1.20 or less.The axial load center radius R1 is a distance in the radial direction Dr between the sealing axis As and an axial load center P1c, which is an intermediate position in the radial direction Dr between a position P1o, which is closest to the radial outer surface Dro under sections of the sealing ring 10 or 10b that are in contact with the sealing retaining ring 20, 20a, 20b, or 20c, and a position P1i of the sealing ring 10 or 10b, which is closest to the radial inner surface Dri. The inner end radius R2 is a distance in the radial direction Dr between the sealing axis As and a position P2 of an end of the contact surface 11C, 11Cb, or 11Cc, which is closest to the radial inner surface Dri.

[0069] The sealing ring 10 or 10b absorbs the axial load F from the high-pressure fluid present on the axial high-pressure side Dah with respect to the sealing ring 10 or 10b. A moment M, which attempts to tilt the sealing axis As with respect to the axis of rotation Ar of the shaft 1, can act on the sealing ring 10 or 10b due to the axial load F. If the sealing ring 10 or 10b is divided into four or more parts in the circumferential direction Dc, the sealing axis As will be tilted with respect to the axis of rotation Ar of the shaft 1 in the event of such a moment M acting, which can cause deterioration of sealing performance, damage to the sealing element 19, such as a sealing rib, or the like. In the present aspect, the generation of the moment M acting on the sealing ring 10 or 10b can be suppressed, and the inclination of the sealing axis As of the sealing ring 10 or 10b with respect to the axis of rotation Ar of the shaft 1 can be suppressed.

[0070] (2) A sealing device according to a second aspect is the sealing device according to the first aspect, wherein the sealing ring 10 is divided into six parts in the circumferential direction Dc.

[0071] The ratio (R2 / R1) of the inner end radius R2 to the axial load center radius R1 is 1.10 or less.

[0072] In the present aspect, even if the sealing ring 10 is divided into six parts in the circumferential direction Dc, the generation of the moment M acting on the sealing ring 10 can be suppressed, and the inclination of the sealing axis As with respect to the axis of rotation Ar of the shaft 1 can be suppressed.

[0073] (3) A sealing device according to a third aspect is the sealing device according to the first aspect, wherein the sealing ring 10 is divided into eight parts in the circumferential direction Dc.

[0074] The ratio (R2 / R1) of the inner end radius R2 to the axial load center radius R1 is 1.06 or less.

[0075] In the present aspect, even if the sealing ring 10 is divided into eight parts in the circumferential direction Dc, the generation of the moment M acting on the sealing ring 10 can be suppressed, and the inclination of the sealing axis As with respect to the axis of rotation Ar of the shaft 1 can be suppressed.

[0076] (4) A sealing device according to a fourth aspect is the sealing device according to the first aspect, wherein the ratio (R2 / R1) of the inner end radius R2 to the axial load center radius R1 is 1.0 or less.

[0077] In the present aspect, regardless of the number of subdivisions of the sealing ring 10, the generation of the moment M acting on the sealing ring 10 can be suppressed, and the inclination of the sealing axis As with respect to the axis of rotation Ar of the shaft 1 can be suppressed.

[0078] (5) A sealing device according to a fifth aspect is the sealing device according to one of the first to fourth aspects, wherein the sealing cylinder 11b has an inner circumferential surface 12i facing the inner circumferential side and from which the multiple sealing pieces 19 project towards the radial inner side Dri, and a projection section 16 projecting from the axial low-pressure side Dal of the inner circumferential surface 12i towards the radial inner side Dri.

[0079] At least a part of an area of ​​the projection section 16, which faces the axial low-pressure side Dal, forms part of the contact surface 11Cb.

[0080] In the present aspect, the projecting section 16 is provided on the sealing cylinder 11b so that the end of the contact surface 11Cb, which is closest to the radial inner surface Dri, can be brought slightly close to the sealing axis As. Therefore, in the present aspect, the inner end radius R2 can be easily reduced, and the ratio (R2 / R1) of the inner end radius R2 to the axial load center radius R1 can also be easily reduced.

[0081] (6) A sealing device according to a sixth aspect is the sealing device according to any one of the first to fourth aspects, wherein the sealing retaining ring 20c comprises a retaining ring body 21 having an annular shape around the sealing axis As and having an annular groove 26 which is recessed towards the radial outer side Dro, and a spacer 30 which has a section which enters the groove 26.

[0082] The retaining groove 25c is formed by the spacer 30 and the groove 26. The spacer 30 comes into contact with at least a portion of a low-pressure side groove surface 26l, which faces the axial high-pressure side Dah, under surfaces defining the groove 26, and comes into contact with at least a portion of the low-pressure side surface 11l of the sealing cylinder 11. The end of the contact surface 11Cc that is closest to the radial inner surface Dri is an end that lies on a surface of the low-pressure side surface 11l of the sealing cylinder 11 that is in contact with the spacer 30 and is closest to the radial inner surface Dri.

[0083] In this aspect, the spacer 30 is provided so that the end of the contact surface 11Cc, which is closest to the radial inner surface Dri, can be easily brought close to the sealing axis As. Therefore, in this aspect, the inner end radius R2 can be easily reduced, and the ratio (R2 / R1) of the inner end radius R2 to the axial load center radius R1 can also be easily reduced.

[0084] (7) A sealing device according to a seventh aspect is the sealing device according to any one of the first to sixth aspects, wherein the sealing cylinder 11 or 11b comprises a cylinder body 12 and a retained section 13 which is inserted into the retaining groove 25 or 25c.

[0085] The cylinder body 12 has an inner circumferential surface 12i facing the radial inner surface Dri, from which the multiple sealing elements 19 project towards the radial inner surface Dri, and an outer circumferential surface 12o facing the radial outer surface Dro. The retained section 13 has a retained leg section 14 projecting from the outer circumferential surface 12o of the cylinder body 12 towards the radial outer surface Dro, and a hook section 15 provided at one end of the retained leg section 14 on the radial outer surface Dro and projecting from the retained leg section 14 towards the axial high-pressure side Dah. The retaining groove 25 or 25c has a leg insertion groove section 28 and a hook insertion groove section 27.The leg insertion groove section 28 receives the held leg section 14, and the width of the leg insertion groove section 28 in the axial direction Da is greater than the width of the held leg section 14 in the axial direction Da and less than the width of the hook section 15 in the axial direction Da. The hook insertion groove section 27 is located on the radial outer side Dro of the leg insertion groove section 28, communicates with the leg insertion groove section 28, and receives the hook section 15, and the width of the hook insertion groove section 27 in the axial direction Da is greater than the width of the hook section 15 in the axial direction Da. Industrial applicability

[0086] According to one aspect of the present disclosure, it is possible to suppress deterioration of sealing performance and damage to a sealing element due to an inclination of a sealing axis of a sealing ring with respect to a rotation axis of a shaft. Reference symbol list 1 wave S, Sa, Sb, Sc, Sx Sealing device 10, 10b Sealing ring 11, 11b Sealing cylinder 11h High-pressure side surface 11l low-pressure side surface area 11C, 11Cb, 11Cc, 11Cx Contact surface 12 cylinder bodies 12i Cylinder inner circumferential surface 120 Body outer circumference area 12h body hypertension side surface 12l low-pressure side surface area 13th held section 14 held leg section 14h leg hypertension lateral surface 14l leg low-pressure side surface 15 Hook section 15i Hook inner circumferential area 150 Hook outer circumference area 15h Hook high-pressure side surface 15l hook low-pressure side surface 16th lead section 19 Sealing piece 20, 20a, 20b, 20c, 20x sealing ring 21 retaining ring bodies 22 retaining ring cylinders 23 High-pressure side wall element 23a first high-pressure side wall element 23b second high-pressure side wall element 24, 24a, 24b, 24c, 24x wall element low-pressure side- 25, 25c, 25x retaining groove 26 Nut 25h high-pressure side holding groove side surface 25l low-pressure side retaining groove side surface 25b Holding groove floor area 26l low-pressure side groove area 27 Hook insertion groove section 27h first high-pressure side holding groove side surface 27l first low-pressure side retaining groove side surface 27r Radial motion limiting surface 28 Leg insertion groove section 28h second high-pressure side holding groove side surface 28l second low-pressure side retaining groove side surface 29r High-pressure side inner circumferential surface 30 spacers 31 Ring disc section 31a first disk side surface 31b second disk side surface 32 tubular section Ga, Gr Spalt F Axial load M Moment P1i Position of end of sealing ring on radial inner side P1o Position of end of contact surface on radial outer side P1c Axial load center P2 Position of end of contact surface on radial inside R1 Axial load center radius R2 inner end radius Ar axis of rotation As sealing axis Since axial direction Dah axial high pressure side Dal axial low-pressure side DC circumferential direction Dr. Radial direction Dri radial inside Dro radial outer side QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2023-083114

[0002] JP 2000-097350

[0006]

Claims

[1] Sealing device comprising: a sealing ring which has an annular shape around a sealing axis; and a sealing retaining ring which has a ring-shaped form around the sealing axis and which holds the sealing ring from an outer circumferential side of the sealing ring, wherein the sealing retaining ring has an annular retaining groove which is recessed in a radial direction with respect to the sealing axis from a radial inner and radial outer surface to a radial outer surface, the sealing ring comprises a sealing cylinder which has an annular shape around the sealing axis and which is partially inserted into the retaining groove of the sealing retaining ring, and several sealing pieces which have an annular shape around the sealing axis and which are arranged on an inner circumferential side of the sealing cylinder in such a way that they are attached to the sealing cylinder, the sealing cylinder, consisting of an axial high-pressure side and an axial low-pressure side in an axial direction in which the sealing axis extends, has a high-pressure side surface facing the axial high-pressure side and a low-pressure side surface facing the axial low-pressure side, the retaining groove is defined by a retaining groove bottom surface facing the radial inside, a high-pressure side retaining groove side surface facing the high-pressure side surface of the sealing cylinder in the axial direction, and a low-pressure side retaining groove side surface facing the low-pressure side surface of the sealing cylinder in the axial direction. at least a part of the low-pressure side surface of the sealing cylinder forms a contact surface of the sealing ring, which enables contact with the low-pressure side retaining groove surface of the sealing retaining ring in the axial direction, the sealing ring is divided into four or more parts in a circumferential direction with respect to the sealing axis, a ratio of an inner end radius to an axial load center radius is 1.20 or less, the axial load center radius is a distance in the radial direction between the sealing axis and an axial load center that is an intermediate position in the radial direction between a position closest to the radial outer surface under sections of the sealing ring that are in contact with the sealing retaining ring, and a position of the sealing ring closest to the radial inner surface, and The inner end radius is a distance in the radial direction between the sealing axis and a position of one end of the contact surface that is closest to the radial inside. [2] Sealing device according to claim 1, wherein the sealing ring is divided into six parts in the circumferential direction, and the ratio of the inner end radius to the axial load center radius is 1.10 or less. [3] Sealing device according to claim 1, wherein the sealing ring is divided into eight parts in the circumferential direction, and the ratio of the inner end radius to the axial load center radius is 1.06 or less. [4] Sealing device according to claim 1, wherein the ratio of the inner end radius to the axial load center radius is 1.0 or less. [5] Sealing device according to any one of claims 1 to 4, wherein the sealing cylinder has a cylinder inner circumferential surface facing the inner circumferential side and from which the several sealing pieces project towards the radial inner side, and a projecting section projecting from the axial low-pressure side of the cylinder inner circumferential surface towards the radial inner side, and at least a part of an area of ​​the projection section facing the axial low-pressure side forms part of the contact surface. [6] Sealing device according to any one of claims 1 to 4, wherein the sealing retaining ring comprises a retaining ring body having an annular shape around the sealing axis and having an annular groove recessed towards the radial outer surface, and a spacer having a section that enters the groove, the retaining groove is formed by the spacer and the groove, the spacer comes into contact with at least a part of a low-pressure side groove surface facing the axial high-pressure side, under surfaces defining the groove, and comes into contact with at least a part of the low-pressure side surface of the sealing cylinder, and the end of the contact surface that is closest to the radial inside is an end that is closest to the radial inside on a surface of the low-pressure side surface of the sealing cylinder that is in contact with the spacer. [7] Sealing device according to any one of claims 1 to 4, wherein the sealing cylinder has a cylinder body and a held section which is inserted into the holding groove, the cylinder body has an inner circumferential surface facing the radial inside and from which the several sealing pieces project towards the radial inside, and an outer circumferential surface facing the radial outside, the held section comprises a held leg section projecting from the outer circumferential surface of the cylinder body to the radial outer surface, and a hook section provided at one end of the held leg section on the radial outer surface and projecting from the held leg section to the axial high-pressure side, the retaining groove has a leg insertion groove section and a hook insertion groove section, the leg insertion groove section accommodates the held leg section and the width of the leg insertion groove section in the axial direction is greater than the width of the held leg section in the axial direction and less than the width of the hook section in the axial direction, and the hook insertion groove section is located on the radial outside of the leg insertion groove section, communicates with the leg insertion groove section and receives the hook section, and the width of the hook insertion groove section in the axial direction is greater than the width of the hook section in the axial direction.

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