Rotary joint

Abstract

To provide a rotary joint capable of effectively reducing pressure loss of a sealed fluid.SOLUTION: A cylindrical case body in which an outer flow path through which a sealed fluid flows is formed to be open to an inner peripheral side; A shaft body in which an inner flow path through which the sealed fluid flows is formed to be open to an outer peripheral side, and a communication flow path connecting the outer flow path and the inner flow path, in which the inner flow path includes a plurality of branch passage portions that are open at different positions in a circumferential direction on the outer peripheral side of the shaft body, and a main passage portion that extends in an axial direction from an end surface of the shaft body on one side in the axial direction toward the other side in the axial direction and has a merging end portion at which the plurality of branch passage portions merge on the other side in the axial direction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to rotary joints. [Background technology]

[0002] Rotary joints are used to connect a fluid passage in a fixed member and a fluid passage in a rotating member. For example, in a CMP (Chemical Mechanical Polishing) apparatus used to polish the surface of semiconductor wafers, sealed fluids such as polishing liquid, pressurizing air, cleaning water, pure water, air blowing air, and polishing residue liquid flow between the rotating member (top ring) and the fixed member (CMP apparatus main body) that supports it. To ensure that these sealed fluids flow between the rotating member and the fixed member without mixing, the joint connecting these two members must be provided with multiple independent fluid passages. Therefore, a multi-port rotary joint, as disclosed in Patent Document 1, for example, is used as such a joint.

[0003] The rotary joint of Patent Document 1 includes a cylindrical case body, a shaft body rotatably provided within the case body, and multiple mechanical seals arranged in the axial direction between the case body and the shaft body. Multiple outer flow passages are formed in the case body, penetrating it in the radial direction. Each outer flow passage opens at a predetermined circumferential position on the inner peripheral surface of the case body.

[0004] The shaft body is formed with inner flow paths (flow path holes), the same number as the outer flow paths, which open on the outer circumferential side of the shaft body. Each inner flow path is formed with an L-shaped cross section, consisting of a vertical hole portion extending axially inside the shaft body and a horizontal hole portion extending radially from the end of the vertical hole toward the outer circumferential surface of the shaft body. Therefore, each inner flow path opens at a predetermined circumferential position on the outer circumferential surface of the shaft body. The rotary joint is formed with a plurality of communicating flow paths in the axial direction, which connect the openings of each outer flow path on the inner circumferential surface of the case body with the openings of each inner flow path on the outer circumferential surface of the shaft body, and are formed by a plurality of mechanical seals. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-106052 Summary of the Invention [Problem to be solved by the invention]

[0006] Rotary joints used in CMP apparatuses are required to reduce the pressure loss of the sealed fluid flowing therein. However, in conventional rotary joints, when the shaft rotates relative to the case, the circumferential angle between the opening of the inner flow passage (lateral hole) on the outer peripheral surface of the shaft and the opening of the outer flow passage on the inner peripheral surface of the case reaches a maximum of 180°. When this angle reaches 180°, the distance the sealed fluid flows circumferentially in the communicating flow passage between the two openings becomes long, resulting in increased pressure loss of the sealed fluid. For this reason, conventional rotary joints are unable to effectively reduce the pressure loss of the sealed fluid.

[0007] The present disclosure has been made in view of the above circumstances, and has an object to provide a rotary joint that can effectively reduce pressure loss of a sealed fluid. [Means for solving the problem]

[0008] (1) A rotary joint of the present disclosure comprises a cylindrical case body in which an outer flow path through which a sealed fluid flows is formed and opens on the inner peripheral side; a shaft body that is rotatable relative to the case body and in which an inner flow path through which the sealed fluid flows is formed and opens on the outer peripheral side; and a communicating flow path that connects the outer flow path and the inner flow path, wherein the inner flow path has a plurality of branch path sections that open at different circumferential positions on the outer peripheral side of the shaft body, and a main path section that extends axially from an end face on one axial side of the shaft body toward the other axial side and has a junction end on the other axial side where the plurality of branch path sections join.

[0009] According to the rotary joint of the present disclosure, the inner flow passage of the shaft has a plurality of branch passage portions that open at different circumferential positions on the outer circumferential side of the shaft. As a result, when the shaft rotates relative to the case body, the maximum circumferential angle between the opening of the outer flow passage and the opening of the inner flow passage (branch passage portion) on the outer circumferential side of the shaft that is closest in the circumferential direction to the opening of the outer flow passage on the inner circumferential side of the case body is less than 180°. Therefore, the circumferential flow distance of the sealed fluid in the communication passage between the inner flow passage and the outer flow passage is shorter than in conventional rotary joints, thereby reducing pressure loss of the sealed fluid due to relative rotation of the shaft body. Furthermore, since the plurality of branch passage portions in the inner flow passage merge at the junction end of the main passage portion, the flow resistance at the junction end can be reduced compared to the flow resistance of the L-shaped cross-section bend portion of a conventional inner flow passage. As a result, pressure loss of the sealed fluid can be reduced more effectively than in conventional rotary joints.

[0010] (2) In the rotary joint of (1), it is preferable that the plurality of branch path sections include an inclined branch path section extending from the confluence end of the main path section to the outer periphery of the shaft body in a direction forming an acute angle with respect to the axial direction toward the other side in the axial direction. In this case, the inclined branch path portion merges more gently into the joining end of the main path portion than the first branch path portion (second branch path portion) described later in (6). This reduces the flow path resistance at the joining end of the main path portion, thereby more effectively reducing the pressure loss of the sealed fluid.

[0011] (3) In the rotary joint of (2), it is preferable that the plurality of branch path sections include an extended branch path section having an extension portion extending in the axial direction from the junction end of the main path section toward the other axial side. In this case, the angle between the inclined branch path portion and the extended branch path portion (extension portion) becomes an acute angle, which is smaller than the angle (180°) between the first branch path portion and the second branch path portion (7) described later. This reduces the flow path resistance at the junction end of the main path portion where the inclined branch path portion and the extended branch path portion join, thereby making it possible to more effectively reduce the pressure loss of the sealed fluid.

[0012] (4) In the rotary joint of (3), it is preferable that the extension branch path portion further has an inclined portion extending from the end of the extension portion on the other axial side to the outer periphery of the shaft body in a direction forming an acute angle with respect to the axial direction toward the other axial side. In this case, the extension branch path portion is gently bent from the other axial end of the extension part by an inclined portion extending in a direction at an acute angle to the axial direction, which reduces the flow resistance of the extension branch path portion compared to when the extension branch path portion is bent perpendicularly to the radial direction from the end of the extension part, thereby more effectively reducing the pressure loss of the sealed fluid.

[0013] (5) In the rotary joint of (3) or (4), it is preferable that the inclined branch path portion and the extended branch path portion are open at an interval of 180° from each other in the circumferential direction on the outer periphery side of the shaft body. In this case, the inclined branch path portion and the extended branch path portion (inclined portion) are open on the outer circumferential side of the shaft at an interval of 180° in the circumferential direction. As a result, when the shaft rotates relative to the case body, the angle in the circumferential direction between the opening of the outer flow path and the opening of the inclined branch path portion and the extended branch path portion on the outer circumferential side of the shaft, which is closest in the circumferential direction to the opening of the outer flow path on the inner circumferential side of the case body, is a maximum of 90°. Therefore, the distance over which the sealed fluid flows in the circumferential direction in the communication flow path between the inner flow path and the outer flow path is further shortened, thereby further reducing the pressure loss of the sealed fluid caused by the relative rotation of the shaft body.

[0014] (6) In any of the rotary joints (1) to (5), it is preferable that the plurality of branch path sections include a first branch path section and a second branch path section extending radially outward from the junction end of the main path section to the outer periphery of the shaft. In this case, the first branch path portion and the second branch path portion of the inner flow path are formed radially perpendicular to the main path portion extending in the axial direction, so that the first branch path portion and the second branch path portion can be formed more easily than the inclined branch path portion of (2) above.

[0015] (7) In the rotary joint of (6) above, it is preferable that the first branch path portion and the second branch path portion are open on the outer circumferential side of the shaft body at an interval of 180° from each other in the circumferential direction. In this case, the first branch path portion and the second branch path portion of the inner flow path are open on the outer circumferential side of the shaft, spaced 180° apart in the circumferential direction. As a result, when the shaft rotates relative to the case body, the angle between the opening of the outer flow path and the opening of the first branch path portion and the second branch path portion on the outer circumferential side of the shaft that is closest in the circumferential direction to the opening of the outer flow path on the inner circumferential side of the case body is at most 90° in the circumferential direction. Therefore, the distance that the sealed fluid flows in the circumferential direction in the communication flow path between the inner flow path and the outer flow path is shorter than in conventional rotary joints, thereby further reducing pressure loss of the sealed fluid caused by relative rotation of the shaft body. [Effects of the Invention]

[0016] According to the rotary joint of the present disclosure, the pressure loss of the sealed fluid can be effectively reduced. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a cross-sectional view showing a rotary joint according to a first embodiment of the present disclosure. [Figure 2] FIG. 3 is an enlarged cross-sectional view showing the lower side of the rotary joint. [Figure 3] FIG. 2 is an enlarged cross-sectional view showing the upper side of the rotary joint. [Figure 4] FIG. 3 is a cross-sectional view taken along the arrow II in FIG. 2. [Figure 5] 5 is an explanatory diagram of an angle relating to a branched channel portion of the first inner flow channel (second inner flow channel) in FIG. 4. FIG. [Figure 6] FIG. 4 is a cross-sectional view showing a rotary joint according to a second embodiment of the present disclosure. [Figure 7] FIG. 7 is an enlarged cross-sectional view showing the lower side of the rotary joint of FIG. 6. [Figure 8] FIG. 8 is a cross-sectional view taken along the line II-II in FIG. 7. [Figure 9] FIG. 7 is an enlarged cross-sectional view showing the upper side of the rotary joint of FIG. 6. [Figure 10] FIG. 10 is a cross-sectional view showing a rotary joint as a reference example. [Figure 11] FIG. 11 is an enlarged cross-sectional view showing the lower side of the rotary joint of FIG. [Figure 12] FIG. 11 is an enlarged cross-sectional view showing the upper side of the rotary joint of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0018] Next, preferred embodiments will be described with reference to the accompanying drawings. [First embodiment] <Overall structure> FIG. 1 is a cross-sectional view showing a rotary joint 1 according to a first embodiment. This rotary joint 1 includes a cylindrical case body 2 and a columnar shaft body 3. The case body 2 is attached to a stationary member of a rotating device (for example, the main body of a CMP device). The shaft body 3 is attached to a rotating member of the rotating device (for example, a top ring of a CMP device). In this embodiment, the case body 2 and the shaft body 3 are arranged with their axial directions aligned vertically.

[0019] In this disclosure, the "axial direction" refers to a direction along the center line X of the rotary joint 1 (including a direction parallel to this center line X). In this disclosure, the "radial direction" refers to a direction perpendicular to the center line X of the rotary joint 1, and the "circumferential direction" refers to a direction around the center line X of the rotary joint 1. The orientation of the rotary joint 1 may be an orientation other than that shown in FIG. 1. In this disclosure, for convenience of explanation, the lower axial side (one axial side) shown in FIG. 1 will be referred to as the "lower side" of the rotary joint 1, and the upper axial side (the other axial side) shown in FIG. 1 will be referred to as the "upper side" of the rotary joint 1.

[0020] <Case body> The case body 2 includes a plurality of flanges 20 stacked in the axial direction. The plurality of flanges 20 includes an annular support flange 21 and a plurality of flow path flanges 22. The plurality of flow path flanges 22 are configured by stacking a first flow path flange 22A, a second flow path flange 22B, a third flow path flange 22C, and a fourth flow path flange 22D in this order from below. The first flow path flange 22A, the second flow path flange 22B, and the third flow path flange 22C are formed in an annular shape. The fourth flow path flange 22D is formed in a concave annular shape that opens downward.

[0021] The support flange 21 has an annular protrusion 211 that protrudes radially inward. Each flow path flange 22 has an annular protrusion 221 that protrudes radially inward at its upper part. The support flange 21 and the plurality of flow path flanges 22 are stacked as described above and fixed with several bolts 23 (only one is shown in FIG. 1). As a result, the case body 2 is formed into a cylindrical shape with a top as a whole. The gap between adjacent flanges 20 in the vertical direction is sealed with an O-ring 24.

[0022] <Outer channel> The case body 2 is formed with a plurality of outer flow passages 27, which are holes through which the sealed fluid flows. The plurality of outer flow passages 27 include a plurality of first outer flow passages 27A, a plurality of second outer flow passages 27B, and a third outer flow passage 27C. The case body 2 of this embodiment has a total of eight outer flow passages 27, including four first outer flow passages 27A, three second outer flow passages 27B, and one third outer flow passage 27C. The first outer flow passages 27A and the second outer flow passages 27B are formed alternately at predetermined intervals in the axial direction. The third outer flow passage 27C is formed at the top of the case body 2.

[0023] The first outer flow passage 27A is formed to penetrate radially at a predetermined circumferential position in the lower part of each flow passage flange 22 (part other than the protruding part 221). The second outer flow passage 27B is formed to penetrate radially at a predetermined circumferential position in the upper part (protruding part 221) of each flow passage flange 22 except the fourth flow passage flange 22D. The third outer flow passage 27C is formed to penetrate radially at a predetermined circumferential position in the upper part (protruding part 221) of the fourth flow passage flange 22D. Examples of the sealed fluid include polishing liquid, pressurizing air, inert gas such as nitrogen, cleaning water, pure water, air for air blowing, polishing residue liquid, etc.

[0024] The outer flow passage 27 opens to the inner circumferential surface, which is the inner circumferential side of the flow passage flange 22. An opening 271 (see also FIG. 2) on the inner circumferential side of the outer flow passage 27 communicates with a communication flow passage 70, which will be described later. The center of the opening 271 of the first outer flow passage 27A coincides with the hole center of the first outer flow passage 27A in order to reduce pressure loss of the sealed fluid. Furthermore, the diameter of the opening 271 of the first outer flow passage 27A is larger than the hole diameter of a through hole 71b of a first communication flow passage 71, which will be described later, in order to reduce pressure loss of the sealed fluid. The outer flow passage 27 opens to the outer circumferential surface, which is the outer circumferential side of the flow passage flange 22. An opening 272 on the outer circumferential side of the outer flow passage 27 serves as a connection port to which a plurality of pipes of the fixed-side member are respectively connected.

[0025] <Shaft> Shaft body 3 is provided within case body 2. Shaft body 3 comprises shaft main body 31 extending in the vertical direction, large diameter section 32 provided at the lower end of shaft main body 31, and small diameter section 33 provided at the upper end of shaft main body 31. The outer diameter of large diameter section 32 is larger than the outer diameter of shaft main body 31. The outer diameter of small diameter section 33 is smaller than the outer diameter of shaft main body 31.

[0026] A rolling bearing 4 is provided between the large diameter portion 32 of the shaft body 3 and the support flange 21. A rolling bearing 5 is provided between the small diameter portion 33 of the shaft body 3 and the fourth flow path flange 22D. This allows the shaft body 3 to be supported rotatably around the center line X with respect to the case body 2.

[0027] <Inner flow path> A plurality of inner flow passages 35, which are holes through which the sealed fluid flows, are formed within the shaft body 3. Each inner flow passage 35 is formed, for example, with a circular cross section. The plurality of inner flow passages 35 are formed at intervals from one another in the circumferential direction within the shaft body 3. For convenience, FIG. 1 shows the plurality of inner flow passages 35 together in one location in the circumferential direction. One end of each of the plurality of inner flow passages 35 opens at a different circumferential position on the lower end face 3a of the shaft body 3. The other end of each of the plurality of inner flow passages 35 opens at a different axial position from one another on the outer circumferential side of the shaft body 3.

[0028] The multiple inner flow paths 35 include multiple first inner flow paths 35A, multiple second inner flow paths 35B, and a third inner flow path 35C. The shaft 3 of this embodiment has a total of eight inner flow paths 35 including four first inner flow paths 35A, three second inner flow paths 35B, and one third inner flow path 35C.

[0029] Each of the plurality of first inner flow paths 35A opens on the outer peripheral surface, which is the outer peripheral side of shaft body 3, at the same axial position as openings 271 of each of the first outer flow paths 27A on the inner peripheral side of case body 2. Each of the plurality of second inner flow paths 35B opens on the outer peripheral surface, which is the outer peripheral side of shaft body 3, at the same axial position as openings 271 (see FIG. 2) of each of the second outer flow paths 27B on the inner peripheral side of case body 2. Third inner flow path 35C opens on an upper end face 31a (see FIG. 3) of shaft main body portion 31, which is on the outer peripheral side of shaft body 3.

[0030] Each inner flow path 35 has a main path portion 36 and a plurality of (two in FIG. 1 ) branch path portions 37. The main path portion 36 extends straight in the axial direction from the lower end face 3a (one axial side) of the shaft 3 to the upper side (the other axial side). The main path portion 36 opens at the lower end face 3a of the shaft 3. The lower opening of the main path portion 36 is connected to the piping of the rotating-side member. The upper path end portion of the main path portion 36 is a junction end portion 36a where the plurality of branch path portions 37 join together. The junction end portion 36a of the main path portion 36 is located slightly axially lower than the opening 271 of the corresponding outer flow path 27.

[0031] <Branch section> 2 is an enlarged cross-sectional view showing the lower side of the rotary joint 1. In FIG. 2, two branch path portions 37 in the inner flow path 35 open at different circumferential positions on the outer circumferential side of the shaft body 3 and merge into a merging end portion 36a of the main path portion 36. In this embodiment, the two branch path portions 37 include an inclined branch path portion 371 and an extended branch path portion 372. The inclined branch path portion 371 and the extended branch path portion 372 each have the same flow path cross-sectional area as the main path portion 36. Note that at least one of the inclined branch path portion 371 and the extended branch path portion 372 may have a flow path cross-sectional area different from that of the main path portion 36.

[0032] The inclined branch path portion 371 extends obliquely from the joining end 36a of the main path portion 36 to the outer periphery of the shaft body 3 in a direction forming an acute angle upward with respect to the axial direction (diagonally upward to the left in FIG. 2). The inclined branch path portion 371 of this embodiment is inclined upward at about 50° with respect to the axial direction from the joining end 36a of the main path portion 36. As a result, the inclined branch path portion 371 merges more gently with the joining end 36a of the main path portion 36 than the first branch path portion 376 (second branch path portion 377) of the second embodiment (FIG. 7) described later.

[0033] Each inclined branch passage portion 371 of the first inner flow passage 35A and the second inner flow passage 35B opens on the outer peripheral surface on the outer peripheral side of the shaft body 3, and the opening 371a is located at the same axial position as the opening 271 of the corresponding outer flow passage 27.

[0034] Each of the extended branch path portions 372 of the first inner flow path 35A and the second inner flow path 35B has an extended portion 373 and an inclined portion 374. The extended portion 373 is a portion that extends straight in the axial direction upward from the junction end 36a of the main path portion 36. Therefore, the angle between the inclined branch path portion 371 and the extended branch path portion 372 (extended portion 373) is an acute angle. As a result, the first inner flow path 35A and the second inner flow path 35B of this embodiment are formed in a substantially Y-shape in axial cross section ( FIG. 2 ). The extended portion 373 extends from below to an axial position closer to the opening 271 of the corresponding outer flow path 27.

[0035] The inclined portion 374 of the extension branch path portion 372 extends obliquely upward at an acute angle with respect to the axial direction (diagonally upward to the right in FIG. 2 ) from the upper end of the extension portion 373 to the outer peripheral surface of the shaft 3. In this embodiment, the inclined portion 374 is inclined upward at an angle of approximately 45° with respect to the axial direction from the end of the extension portion 373. As a result, the extension branch path portion 372 is gently bent by the inclined portion 374 from the end of the extension portion 373 and opens at the outer peripheral surface of the shaft 3.

[0036] An opening 374a of the inclined portion 374 on the outer peripheral surface of the shaft 3 is located at the same axial position as the opening 271 of the corresponding outer flow passage 27. Therefore, on the outer peripheral surface of the shaft 3, the inclined portion 374 opens at the same axial position as the inclined branch path portion 371. The opening 374a of the inclined portion 374 communicates with the corresponding first communication flow passage 71 (described below) or second communication flow passage 72 (described below).

[0037] Fig. 3 is an enlarged cross-sectional view showing the upper side of rotary joint 1. In Fig. 3, inclined branch path portion 371 of third inner flow path 35C opens at a corner between shaft main body portion 31 and small diameter portion 33 on the outer circumferential side of shaft 3, and opening 371b thereof communicates with third communication path 73, which will be described later.

[0038] The extended branch path portion 372 of the third inner flow path 35C has only an extended portion 375. The extended portion 375 extends straight in the axial direction upward from the junction end 36a of the main path portion 36. The angle between the inclined branch path portion 371 and the extended branch path portion 372 (extended portion 375) is an acute angle. As a result, the third inner flow path 35C of this embodiment is formed in a substantially Y-shape in axial cross section ( FIG. 3 ). The extended portion 375 opens at the upper end face 31a of the shaft main body portion 31, which is on the outer circumferential side of the shaft body 3, and the opening 375a communicates with a third communication flow path 73, which will be described later.

[0039] Fig. 4 is a cross-sectional view taken along the line II in Fig. 2. In Fig. 2 and Fig. 4, the inclined branch path portion 371 and the extended branch path portion 372 (inclined portion 374), which are the branch path portions 37 of the first inner flow path 35A and the second inner flow path 35B, open at intervals from each other in the circumferential direction on the outer circumferential surface of the shaft body 3. In this embodiment, the inclined branch path portion 371 and the extended branch path portion 372 open at intervals of 180° from each other in the circumferential direction.

[0040] The inclined branch path portion 371 and the extended branch path portion 372 (extension portion 375), which are the branch path portion 37 of the third inner flow path 35C (see FIG. 3), open at intervals from each other in the circumferential direction on the outer circumferential side of the shaft body 3. The inclined branch path portion 371 and the extended branch path portion 372 of the third inner flow path 35C in this embodiment open at intervals of 180° from each other in the circumferential direction on the outer circumferential side of the shaft body 3.

[0041] When the shaft body 3 rotates relative to the case body 2, the multiple openings 371a, 374a, 375a of the branch path section 37 on the outer peripheral surface of the shaft body 3 rotate together with the shaft body 3. Therefore, a circumferential angle α1 (see FIG. 5) between the opening 371a of the inclined branch path section 371 in the branch path section 37 and the opening 271 of the outer flow path 27 on the inner peripheral surface of the case body 2 changes with the rotation of the shaft body 3. Similarly, a circumferential angle α2 (see FIG. 5) between the opening 374a (opening 375a) of the extended branch path section 372 in the branch path section 37 and the opening 271 of the outer flow path 27 on the inner peripheral surface of the case body 2 changes with the rotation of the shaft body 3. Details thereof will be described below with reference to FIGS. 4 and 5.

[0042] Fig. 5 is an explanatory diagram of angles α1 and α2 related to the branched path portion 37 of the first inner flow path 35A (second inner flow path 35B) in Fig. 4. The angles α1 and α2 related to the branched path portion 37 of the third inner flow path 35C (see Fig. 3) are similar, and therefore description thereof will be omitted.

[0043] 5, angle α1 is the circumferential angle between the center of the opening 371a of the inclined branch path portion 371 and the center of the opening 271 of the outer flow path 27, with the center being centered on the center line X of the rotary joint 1. Angle α2 is the circumferential angle between the center of the opening 374a of the extended branch path portion 372 and the center of the opening 271 of the outer flow path 27, with the center being centered on the center line X of the rotary joint 1.

[0044] Angle α1 changes so as to be maximum when opening 371a of inclined branch path portion 371 is rotated 180° relative to opening 271 of outer flow path 27 (3 o'clock position in FIG. 5). Similarly, angle α2 changes so as to be maximum when opening 374a of extended branch path portion 372 is rotated 180° relative to opening 271 of outer flow path 27 (3 o'clock position in FIG. 5). Therefore, angles α1 and α2 that change with rotation of shaft 3 are each 180° at most.

[0045] As described above, the opening 371a of the inclined branch path portion 371 and the opening 374a of the extended branch path portion 372 are formed at an interval (phase difference) of 180° in the circumferential direction on the outer peripheral surface of the shaft body 3. Therefore, when the angle α1 is 90°, the angle α2 is also 90°. As shown in FIG. 5, when one of the angles α1 and α2 exceeds 90°, the other angle is less than 90°. Therefore, during rotation of the shaft body 3, one of the angles α1 and α2 is always less than 90°.

[0046] As a result of the above, when the shaft body 3 rotates relative to the case body 2, the angle α between the opening 271 of the outer flow path 27 and the opening (opening 371a in Figure 5) that is closest circumferentially to the opening 271 of the outer flow path 27 among the multiple openings 371a, 374a of the branch path section 37 is a maximum of 90°. In contrast, in conventional rotary joints, as described above, the circumferential angle between the opening of the inner flow path (lateral hole) on the outer peripheral surface of the shaft and the opening of the outer flow path on the inner peripheral surface of the case body is up to 180°.

[0047] Therefore, the maximum value of the angle α in this embodiment is smaller than that in the conventional rotary joint, which allows the distance over which the sealed fluid flows in the circumferential direction in the communication passage 70 (described later) that connects the inner passage 35 and the outer passage 27 to be shorter than that in the conventional rotary joint.

[0048] <Mechanical seal> In Figure 1, the rotary joint 1 is equipped with a plurality of (four in Figure 1) mechanical seals 6 arranged between the case body 2 and the shaft body 3. The plurality of mechanical seals 6 are arranged side by side in the axial direction between the case body 2 and the shaft body 3. Each mechanical seal 6 is arranged on the inner circumferential side of two flanges 20 that are adjacent to each other above and below the case body 2. Hereinafter, of these two flanges 20, the flange 20 arranged on the upper side will be referred to as the "upper flange 20," and the flange 20 arranged on the lower side will be referred to as the "lower flange 20."

[0049] 2, each mechanical seal 6 has a first case-side seal ring 61, a second case-side seal ring 62, and a shaft-side seal ring 63. The first case-side seal ring 61 and the second case-side seal ring 62 are case-side seal rings provided on the inner peripheral side of the case body 2. The shaft-side seal ring 63 is provided on the outer peripheral side of the shaft body 3 so as to be rotatable integrally with the shaft body 3. In this embodiment, the case-side seal rings 61, 62 function as stationary seal rings. Furthermore, the shaft-side seal ring 63 functions as a rotating seal ring that slides relative to the case-side seal rings 61, 62.

[0050] The first case side seal ring 61 and the second case side seal ring 62 are arranged above and below the shaft side seal ring 63. The first case side seal ring 61 and the second case side seal ring 62 are each arranged axially opposite the shaft side seal ring 63. The first case side seal ring 61 and the second case side seal ring 62 are each formed in an annular shape.

[0051] The first case side seal ring 61 is attached to the lower flange 20 (support flange 21 in FIG. 2). Specifically, the first case side seal ring 61 is fitted onto the inner circumferential side of the protrusion 211 (221) of the lower flange 20. A seal surface 61a is formed on the upper end face of the first case side seal ring 61.

[0052] The second case side seal ring 62 is attached to the upper flange 20 (first flow path flange 22A in FIG. 2) of the flanges 20 adjacent to each other in the vertical direction of the case body 2. Specifically, the second case side seal ring 62 is fitted onto the inner peripheral side of the protruding portion 221 of the upper flange 20. A sealing surface 62a is formed on the lower end face of the second case side seal ring 62.

[0053] The radially outer portion of each case-side seal ring 61, 62 abuts against a pin 25 that protrudes in the axial direction (up and down direction) and is fixed to the protruding portion 221 of the flange 20. This prevents each case-side seal ring 61, 62 from rotating relative to the case body 2, and restricts co-rotation with the shaft-side seal ring 63. An O-ring 68 seals the gap between each case-side seal ring 61, 62 and the protruding portion 221 of the flange 20.

[0054] The shaft-side seal ring 63 is formed in an annular shape. The shaft-side seal ring 63 is fitted to the outer peripheral surface of the shaft 3 at the same axial position as the openings 371a, 374a on the outer peripheral side of the first inner flow path 35A. An annular seal surface 63a that comes into contact with the seal surface 61a of the first case-side seal ring 61 is formed on the lower end face of the shaft-side seal ring 63. An annular seal surface 63b that comes into contact with the seal surface 62a of the second case-side seal ring 62 is formed on the upper end face of the shaft-side seal ring 63. A seal is formed between the inner peripheral surface of the shaft-side seal ring 63 and the outer peripheral surface of the shaft 3 by a pair of upper and lower O-rings 69 arranged across an inner annular passage 71c (described later).

[0055] Each mechanical seal 6 has a first elastic member 64 and a second elastic member 65. The first elastic member 64 and the second elastic member 65 are, for example, compression coil springs. The first elastic member 64 is attached to the lower flange 20. The second elastic member 65 is attached to the upper flange 20. Note that the first elastic member 64 and the second elastic member 65 are not limited to compression coil springs and may be other elastic members.

[0056] The first elastic member 64 is inserted in a compressed state into a plurality of insertion holes 222 (only one of which is shown in FIG. 2 ) formed in the circumferential direction in the protruding portion 221 of the lower flange 20. The upper end of the first elastic member 64 abuts against the first case side seal ring 61. The first case side seal ring 61 is pressed upward (towards the shaft side seal ring 63) by the elastic restoring force of the first elastic member 64. As a result, an axial pressing force acts between the seal surfaces 61 a, 63 a of the first case side seal ring 61 and the shaft side seal ring 63.

[0057] The second elastic member 65 is inserted in a compressed state into a plurality of insertion holes 223 (only one of which is shown in FIG. 2 ) formed in the circumferential direction in the protruding portion 221 of the upper flange 20. The lower end of the second elastic member 65 abuts against the second case side seal ring 62. The second case side seal ring 62 is pressed downward (towards the shaft side seal ring 63) by the elastic restoring force of the second elastic member 65. As a result, an axial pressing force acts between both seal surfaces 62a, 63b of the second case side seal ring 62 and the shaft side seal ring 63.

[0058] As the shaft body 3 rotates relative to the case body 2, the seal surfaces 63a, 63b of the shaft-side seal ring 63 slide against the seal surface 61a of the first case-side seal ring 61 and the seal surface 62a of the second case-side seal ring 62 while being pressed against them, respectively. Therefore, the sealing function of the mechanical seal 6 is exerted by the sliding action between the seal surfaces 61a, 63a caused by the relative rotation of the first case-side seal ring 61 and the shaft-side seal ring 63, and the sliding action between the seal surfaces 62a, 63b caused by the relative rotation of the second case-side seal ring 62 and the shaft-side seal ring 63. Hereinafter, the portion where the seal surfaces 61a, 63a slide against each other will be referred to as a sliding portion 66, and the portion where the seal surfaces 62a, 63b slide against each other will be referred to as a sliding portion 67.

[0059] <Communicating flow path> 1 , the rotary joint 1 has a plurality of communication passages 70 formed between the case body 2 and the shaft body 3 by a plurality of mechanical seals 6. The plurality of communication passages 70 include a plurality of first communication passages 71, a plurality of second communication passages 72, and a third communication passage 73. The rotary joint 1 of this embodiment has a total of eight communication passages 70, including four first communication passages 71, three second communication passages 72, and one third communication passage 73.

[0060] The first communication flow path 71 is a flow path that connects the first outer flow path 27A and the first inner flow path 35A. The second communication flow path 72 is a flow path that connects the second outer flow path 27B and the second inner flow path 35B. The third communication flow path 73 is a flow path that connects the third outer flow path 27C and the third inner flow path 35C.

[0061] 2 and 4, the first communication passage 71 is formed at an axial position corresponding to each mechanical seal 6. The first communication passage 71 is composed of an outer annular passage 71a, a plurality of (four in FIG. 4) through holes 71b, and an inner annular passage 71c.

[0062] The outer annular passage 71a of the first communication passage 71 is an annular space formed between the protruding portions 221, 221 (211) of the flanges 20 adjacent to each other in the vertical direction, radially outward of the shaft-side seal ring 63 of each mechanical seal 6. The outer annular passage 71a is sealed by the sealing function of the sliding portions 66, 67 of each mechanical seal 6 and the sealing function of each O-ring 24, 68. The outer annular passage 71a communicates with the first outer passage 27A of the corresponding flange 20 at a predetermined location in the circumferential direction.

[0063] The plurality of through holes 71b and inner annular passage 71c in the first communication passage 71 are formed in the shaft-side seal ring 63 of each mechanical seal 6. The inner annular passage 71c is formed by an annular groove formed in the inner circumference of the shaft-side seal ring 63 and the outer peripheral surface of the shaft body 3. The inner annular passage 71c is sealed by the sealing function of a pair of upper and lower O-rings 69. The inner annular passage 71c communicates with the corresponding first inner passage 35A (the inclined branch passage portion 371 and the extended branch passage portion 372) of the shaft body 3 at predetermined locations in the circumferential direction. The through holes 71b are spaced apart circumferentially of the shaft-side seal ring 63 and are formed to penetrate the shaft-side seal ring 63 in the radial direction. Each through hole 71b connects the outer annular passage 71a and the inner annular passage 71c.

[0064] As described above, the first communication passage 71 connects the first outer passage 27A of the case body 2 and the first inner passage 35A of the shaft body 3. The first outer passage 27A, the first communication passage 71, and the first inner passage 35A form one independent first fluid passage 11 through which the sealed fluid flows. Therefore, the rotary joint 1 of this embodiment has a plurality of (four in FIG. 1 ) independent first fluid passages 11 in the axial direction. In each first fluid passage 11 of this embodiment, the sealed fluid flows from the first outer passage 27A through the first communication passage 71 to the first inner passage 35A.

[0065] 2, the second communication passage 72 is formed between the shaft-side seal rings 63 of two vertically adjacent mechanical seals 6. The second communication passage 72 is made up of an outer annular passage 72a and an inner annular passage 72b.

[0066] The outer annular passage 72a of the second communication passage 72 is an annular space formed between the second case side seal ring 62 of the lower mechanical seal 6 and the first case side seal ring 61 of the upper mechanical seal 6 of two vertically adjacent mechanical seals 6. The outer annular passage 72a is sealed by the sealing function of O-rings 68 arranged on both the top and bottom sides thereof. The outer annular passage 72a communicates with the second outer passage 27B of the corresponding flange 20 at a predetermined location in the circumferential direction.

[0067] The inner annular passage 72b of the second communication flow passage 72 is an annular gap formed between the inner circumferential surfaces of the second case side seal ring 62 and the first case side seal ring 61, which form the outer annular passage 72a, and the outer circumferential surface of the shaft 3. The inner annular passage 72b is sealed by the sealing function of O-rings 69, which are disposed on both the top and bottom sides of the inner annular passage 72b. The inner annular passage 72b communicates with the outer annular passage 72a. The inner annular passage 72b also communicates with the corresponding second inner flow passage 35B (the inclined branch path portion 371 and the extended branch path portion 372) of the shaft 3 at predetermined circumferential locations.

[0068] As described above, the second communication passage 72 connects the second outer passage 27B of the case body 2 and the second inner passage 35B of the shaft body 3. The second outer passage 27B, the second communication passage 72, and the second inner passage 35B form one independent second fluid passage 12 through which the sealed fluid flows. Therefore, the rotary joint 1 of this embodiment is provided with a plurality of (three in FIG. 1 ) independent second fluid passages 12 in the axial direction. In each second fluid passage 12 of this embodiment, the sealed fluid flows from the second outer passage 27B through the second communication passage 72 to the second inner passage 35B.

[0069] 3, the third communication passage 73 is formed above the shaft-side seal ring 63 of the uppermost mechanical seal 6. The third communication passage 73 is sealed by the sealing functions of O-rings 68, 69 arranged radially outside and below the third communication passage 73, and by the sealing function of the sliding portion 67 of the uppermost mechanical seal 6. The third communication passage 73 is made up of an outer annular passage 73a and an inner annular passage 73b.

[0070] The outer annular passage 73a of the third communication passage 73 is an annular space with an L-shaped cross section formed between the second case-side sealing ring 62 of the uppermost mechanical seal 6 and the fourth passage flange 22D. The outer annular passage 73a communicates with the third outer passage 27C of the fourth passage flange 22D at a predetermined location in the circumferential direction.

[0071] The inner annular passage 73b of the third communication passage 73 is a space formed between the upper end face 31a of the shaft body portion 31 and the lower surface of the central portion of the fourth passage flange 22D. The inner annular passage 73b communicates with the outer annular passage 73a. The inner annular passage 73b also communicates with the third inner passage 35C of the shaft body 3 (the inclined branch passage portion 371 and the extended branch passage portion 372) at predetermined circumferential positions.

[0072] As described above, the third communication passage 73 connects the third outer passage 27C of the case body 2 and the third inner passage 35C of the shaft body 3. The third outer passage 27C, the third communication passage 73, and the third inner passage 35C form a single independent third fluid passage 13 through which the sealed fluid flows. Therefore, the rotary joint 1 of this embodiment is provided with a single independent third fluid passage 13. In the third fluid passage 13 of this embodiment, the sealed fluid flows from the third outer passage 27C through the third communication passage 73 to the third inner passage 35C.

[0073] <Action and effect> According to the rotary joint 1 of the first embodiment, the inner flow path 35 of the shaft body 3 has a plurality of branch path portions 37 that open at different circumferential positions on the outer peripheral side of the shaft body 3. As a result, when the shaft body 3 rotates with respect to the case body 2, the circumferential angle α between the opening 271 of the outer flow path 27, and the opening 271 of the outer flow path 27 on the inner peripheral side of the case body 2, among the plurality of openings 371a (371b), 374a of the inner flow path 35 (branch path portion 37) on the outer peripheral side of the shaft body 3, that is closest in the circumferential direction to the opening 271 of the outer flow path 27, is at most less than 180°.

[0074] As a result, the distance over which the sealed fluid flows in the circumferential direction in the communicating flow path 70 between the inner flow path 35 and the outer flow path 27 is shorter than in conventional rotary joints, thereby reducing pressure loss of the sealed fluid due to rotation of the shaft 3. Furthermore, in the inner flow path 35, the multiple branch path portions 37 merge into the merged end portion 36a of the main path portion 36, so that the flow path resistance at the merged end portion 36a can be reduced compared to the flow path resistance of the bent portion with an L-shaped cross section in a conventional inner flow path.

[0075] As described above, the rotary joint 1 of this embodiment can reduce the pressure loss of the sealed fluid more effectively than conventional rotary joints. In particular, when increasing the number of inner flow paths 35 without changing the outer diameter of the shaft 3, it is necessary to reduce the flow path diameter of each inner flow path 35. However, reducing the flow path diameter increases the flow path resistance of each inner flow path 35, so in such cases it is more effective to apply the rotary joint 1 of the present disclosure.

[0076] The branch path portion 37 of the inner flow path 35 includes an inclined branch path portion 371 extending upward from the main path portion 36 to the outer periphery of the shaft body 3 in a direction forming an acute angle with respect to the axial direction. Therefore, the inclined branch path portion 371 merges more gently with the joining end portion 36a of the main path portion 36 than the first branch path portion 376 (second branch path portion 377) of the second embodiment (FIG. 7) described later. This reduces the flow path resistance at the joining end portion 36a of the main path portion 36, thereby making it possible to more effectively reduce the pressure loss of the sealed fluid.

[0077] The branch path portion 37 of the inner flow path 35 includes an extended branch path portion 372 having extension portions 373, 375 extending axially upward from the main path portion 36. Therefore, the angle between the inclined branch path portion 371 and the extended branch path portion 372 (extension portions 373, 375) is an acute angle, which is smaller than the angle (180°) between the first branch path portion 376 and the second branch path portion 377 in the second embodiment (FIG. 7) described below. This reduces flow path resistance at the junction end 36a of the main path portion 36 where the inclined branch path portion 371 and the extended branch path portion 372 join, thereby more effectively reducing pressure loss of the sealed fluid. In particular, when the sealed fluid flows from each of the inclined branch path portion 371 and the extended branch path portion 372 toward the main path portion 36, the sealed fluid flows smoothly downward at the junction end 36a of the main path portion 36, thereby effectively reducing flow path resistance at the junction end 36a.

[0078] The extended branch path portions 372 of the first inner flow path 35A and the second inner flow path 35B further have inclined portions 374 extending upward from the extended portions 373 to the outer circumferential surface of the shaft body 3 in a direction forming an acute angle with respect to the axial direction. Therefore, the extended branch path portions 372 are gently bent by the inclined portions 374. This reduces the flow path resistance of the extended branch path portions 372 compared to when the extended branch path portions 372 are bent perpendicularly to the radial direction from the upper ends of the extended portions 373, thereby making it possible to more effectively reduce the pressure loss of the sealed fluid.

[0079] The inclined branch path portion 371 and the extended branch path portion 372 of the inner flow path 35 are open at an interval of 180° in the circumferential direction on the outer circumferential side of the shaft body 3. As a result, when the shaft body 3 rotates with respect to the case body 2, the angle α in the circumferential direction between the opening 271 of the outer flow path 27 and the opening 271a (371b), 374a of the inclined branch path portion 371 and the extended branch path portion 372 on the outer circumferential side of the shaft body 3 that is closest in the circumferential direction to the opening 271 of the outer flow path 27 on the inner circumferential side of the case body 2 is a maximum of 90°. Therefore, the distance over which the sealed fluid flows in the circumferential direction in the communication flow path 70 between the inner flow path 35 and the outer flow path 27 is further shortened, thereby further reducing the pressure loss of the sealed fluid caused by the rotation of the shaft body 3.

[0080] <Modification> In the rotary joint 1 of the first embodiment, each inner flow path 35 of the shaft body 3 has multiple branch path sections 37, including inclined branch path sections 371 and extended branch path sections 372, but all of the branch path sections 37 may be inclined branch path sections 371.

[0081] [Second embodiment] Fig. 6 is a cross-sectional view showing a rotary joint 1 according to a second embodiment of the present disclosure. Fig. 7 is an enlarged cross-sectional view showing the underside of rotary joint 1 according to the present embodiment. Rotary joint 1 according to the second embodiment differs from that according to the first embodiment in the configuration of each inner flow path 35 of shaft 3.

[0082] <First inner flow path and second inner flow path> 6 and 7, each of the first inner flow paths 35A and each of the second inner flow paths 35B of this embodiment has a main path portion 36 and a plurality of (two in FIG. 6) branch path portions 37. The junction end portion 36a of the main path portion 36 extends to the same axial position as the opening 271 of the corresponding outer flow path 27. The plurality of branch path portions 37 include a first branch path portion 376 and a second branch path portion 377. The first branch path portion 376 and the second branch path portion 377 have the same flow path cross-sectional area as the main path portion 36. Note that at least one of the first branch path portion 376 and the second branch path portion 377 may have a flow path cross-sectional area different from that of the main path portion 36.

[0083] Figure 8 is a cross-sectional view taken along the line II-II in Figure 7. In Figures 7 and 8, the first branched path portion 376 and the second branched path portion 377 extend radially outward from the joining end 36a of the main path portion 36 to the outer periphery of the shaft 3. The first branched path portion 376 and the second branched path portion 377 open at an interval from each other in the circumferential direction on the outer periphery of the shaft 3.

[0084] In this embodiment, the first branch path portion 376 and the second branch path portion 377 are open on the outer peripheral surface of the shaft 3, at an interval of 180° from each other in the circumferential direction. That is, the first branch path portion 376 and the second branch path portion 377 extend in opposite directions from the joining end 36a of the main path portion 36, and the angle between them is 180° in an axial cross-sectional view (FIG. 7). The first branch path portion 376 and the second branch path portion 377 are formed perpendicular to the main path portion 36. Therefore, the inner flow path 35 of this embodiment is formed in a T-shape in an axial cross-sectional view (FIG. 7). The opening 376a of the first branch path portion 376 and the opening 377a of the second branch path portion 377 on the outer peripheral surface of the shaft 3 are located at the same axial positions as the corresponding openings 271 of the outer flow path 27.

[0085] The angles α1, α2 of the first inner flow path 35A (second inner flow path 35B) in this embodiment with respect to the branch path portion 37 are the same when the openings 371a, 374a of the branch path portion 37 in the first embodiment (see Figure 5) are replaced with the openings 376a, 377a of the branch path portion 37 in this embodiment, and therefore will not be explained here.

[0086] <Third inner flow path> Fig. 9 is an enlarged cross-sectional view showing the upper side of the rotary joint 1 of this embodiment. In Fig. 6 and Fig. 9, the third inner flow path 35C of this embodiment has only a main path portion 38. The main path portion 38 extends straight in the axial direction from the lower end face 3a of the shaft 3 toward the upper side.

[0087] One end of main path portion 38 opens at the lower end face 3a of shaft body 3. The piping of the rotation-side member is connected to the lower opening of main path portion 38. The other end of main path portion 38 opens at the upper end face 31a of shaft body portion 31, and opening 38a communicates with third communication flow path 73. Other configurations of this embodiment are the same as those of the first embodiment, so the same reference numerals are used and the description will be omitted.

[0088] <Action and effect> According to the rotary joint 1 of the second embodiment, the inner flow passage 35 (excluding the third inner flow passage 35C) of the shaft body 3 has a plurality of branched passage portions 37 that open at different circumferential positions on the outer circumferential surface of the shaft body 3. As a result, similar to the first embodiment, the pressure loss of the sealed fluid can be reduced more effectively than in conventional rotary joints.

[0089] The branch path portion 37 of the inner flow path 35 includes a first branch path portion 376 and a second branch path portion 377 that extend radially outward from the main path portion 36 to the outer circumferential surface of the shaft 3. As a result, the first branch path portion 376 and the second branch path portion 377 are formed perpendicular to the main path portion 36 that extends in the axial direction, and therefore the first branch path portion 376 and the second branch path portion 377 can be formed more easily than the inclined branch path portion 371 of the first embodiment (FIG. 1).

[0090] The first branch path portion 376 and the second branch path portion 377 of the inner flow path 35 are open at an interval of 180° in the circumferential direction on the outer peripheral surface of the shaft body 3. As a result, when the shaft body 3 rotates with respect to the case body 2, the angle α in the circumferential direction between the opening 271 of the outer flow path 27 and the opening 271 of the outer flow path 27, of the two openings 376a, 377a of the first branch path portion 376 and the second branch path portion 377 on the outer peripheral surface of the shaft body 3 that is closest in the circumferential direction to the opening 271 of the outer flow path 27 on the inner peripheral surface of the case body 2, is at most 90°. Therefore, the circumferential distance of the sealed fluid in the communication flow path 70 between the inner flow path 35 and the outer flow path 27 is shorter than in conventional rotary joints, and therefore the pressure loss of the sealed fluid caused by the rotation of the shaft body 3 can be further reduced.

[0091] [Effectiveness verification test] The inventors of the present application conducted simulation analysis using fluid analysis software as a test to confirm the effects of the rotary joints of the first and second embodiments. In this test, analysis was performed on a total of four types of rotary joints: the conventional rotary joint, the first embodiment, the above-described modified version of the first embodiment (a modified version in which all of the branch path portions 37 are inclined branch path portions 371), and the second embodiment.

[0092] Specifically, the pressure difference of the sealed fluid at the inlet and outlet (opening of the inner flow passage 35 on the end face 3a of the shaft 3) of the rotary joint 1 was calculated by simulation, with the flow rate of the sealed fluid flowing in from the inlet (opening 272 on the outer peripheral side of the outer flow passage 27) of each rotary joint kept constant. The smaller the pressure difference, the smaller the pressure loss of the sealed fluid.

[0093] In this test, the pressure difference was calculated for each of the four types, and then the ratio of the pressure difference for the rotary joint of each embodiment (variant) to the pressure difference for the conventional rotary joint was calculated. This ratio indicates how much the pressure loss of the sealed fluid was reduced in the rotary joint of each embodiment (variant) compared to the conventional rotary joint, that is, the degree of improvement in pressure loss reduction. The larger the ratio, the more effectively the pressure loss of the sealed fluid is reduced. Table 1 below shows the analysis results of the simulation in this test.

[0094] [Table 1]

[0095] As shown in Table 1, it was confirmed that the pressure loss of the sealed fluid can be reduced in the order of the rotary joint of the first embodiment, the rotary joint of the modified example of the first embodiment, and the rotary joint of the second embodiment.

[0096] [Reference example] Fig. 10 is a cross-sectional view showing a rotary joint 1 as a reference example. Fig. 11 is an enlarged cross-sectional view showing the underside of the rotary joint 1 of this reference example. The rotary joint 1 of this reference example differs from the first embodiment in the configuration of each inner flow path 35 of the shaft 3. In Figs. 10 and 11, each inner flow path 35 of this reference example has a single main path portion 41 and a single inclined path portion 42.

[0097] The main path portion 41 extends straight in the axial direction from the lower end face 3a of the shaft 3 toward the upper side. The main path portion 41 opens at the lower end face 3a of the shaft 3. The piping of the rotating-side member is connected to the lower opening of the main path portion 41. The upper path end portion 41a of the main path portion 41 is located slightly lower in the axial direction than the corresponding opening 271 of the outer flow path 27.

[0098] The inclined path portion 42 extends obliquely from the upper path end portion 41a of the main path portion 41 to the outer periphery of the shaft body 3 in a direction forming an acute angle (diagonally upward to the left in FIG. 10) toward the upper side with respect to the axial direction. The inclined path portion 42 of this reference example is inclined upward at an angle of approximately 50° with respect to the axial direction from the upper path end portion 41a of the main path portion 41. The inclined path portion 42 has the same flow path cross-sectional area as the main path portion 41. Note that the inclined path portion 42 may have a flow path cross-sectional area different from that of the main path portion 41.

[0099] Each of the inclined path portions 42 of the first inner flow path 35A and the second inner flow path 35B opens at a predetermined circumferential position on the outer peripheral surface on the outer circumferential side of the shaft body 3, and the opening 42a is located at the same axial position as the opening 271 of the corresponding outer flow path 27. The opening 42a of each inclined path portion 42 communicates with the corresponding first communication flow path 71 or second communication flow path 72.

[0100] 12 is an enlarged cross-sectional view showing the upper side of rotary joint 1 of this reference example. As shown in Fig. 12, inclined path portion 42 of third inner flow path 35C opens at the corner between shaft main body portion 31 and small diameter portion 33, which is on the outer circumferential side of shaft 3, and opening 42b thereof communicates with third communication flow path 73. Other configurations of this reference example are similar to those of the first embodiment, so the same reference numerals are used and the description will be omitted.

[0101] According to the rotary joint 1 of this reference example, the inclined path portion 42 of the inner flow path 35 extends upward from the main path portion 41 to the outer periphery of the shaft body 3 in a direction forming an acute angle with respect to the axial direction. As a result, the bent portion between the main path portion 41 and the inclined path portion 42 bends more gently than the bent portion with an L-shaped cross section in a conventional inner flow path. As a result, the flow path resistance at the bent portion between the main path portion 41 and the inclined path portion 42 is reduced, and the pressure loss of the sealed fluid can be effectively reduced.

[0102] [others] The rotary joint 1 in each of the above embodiments may be disposed upside down in the axial direction, or may be disposed so that the axial direction is horizontal. Furthermore, the rotary joint 1 can be applied to other devices, such as sputtering devices and etching devices, in addition to CMP devices. Furthermore, the rotary joint 1 is not limited to use in the semiconductor field. Furthermore, although the rotary joint 1 forms the communicating flow path 70 using the mechanical seal 6, the communicating flow path 70 may also be formed using other sealing materials (for example, an X-ring or a lip seal).

[0103] In each of the above embodiments, the shaft body 3 rotates relative to the case body 2, but the case body 2 may also rotate relative to a fixed shaft body 3. In each of the above embodiments, the sealed fluid flows in a direction from the outer flow path 27 of the case body 2 toward the inner flow path 35 of the shaft body 3, but the sealed fluid may also flow in the opposite direction. The inner flow path 35 in each of the above embodiments may include three or more branch path portions 37.

[0104] The extension branch path portion 372 of the first embodiment has an inclined portion 374 that extends obliquely from the upper end of the extension portion 373 in a direction that forms an acute angle with the axial direction, but it may also be formed to extend vertically radially outward from the upper end of the extension portion 373 to the outer periphery of the shaft body 3.

[0105] The inclined branch path portion 371 and the extended branch path portion 372 in the first embodiment are formed at 180° intervals in the circumferential direction, but are not limited to this and may be formed at an acute angle or at 90° intervals in the circumferential direction, for example. Similarly, the first branch path portion 376 and the second branch path portion 377 in the second embodiment are formed at 180° intervals in the circumferential direction, but are not limited to this and may be formed at an acute angle or at 90° intervals in the circumferential direction, for example.

[0106] Of the first and second embodiments, at least a part of one embodiment may be combined with at least a part of the other embodiment. For example, the plurality of branch path portions 37 of the first embodiment may include at least one of the first branch path portion 376 and the second branch path portion 377 of the second embodiment in addition to the inclined branch path portion 371 and the extended branch path portion 372. Similarly, the plurality of branch path portions 37 of the second embodiment may include at least one of the inclined branch path portion 371 and the extended branch path portion 372 of the first embodiment in addition to the first branch path portion 376 and the second branch path portion 377.

[0107] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. 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 and meaning equivalent to the claims. [Explanation of symbols]

[0108] 1 rotary joint 2 Case body 3-axis body 27 Outer channel 35 Inner flow channel 36 Main Road Section 36a Confluence end 37 Branching section 70 Connecting flow path 371 Inclined Branch Section 372 Extension Branch Section 373.375 Extension part 374 Slope section 376 First branch road section 377 Second Branch Section

Claims

1. a cylindrical case body having an outer flow passage through which a sealed fluid flows, the outer flow passage opening to an inner peripheral side; a shaft body that is rotatably provided within the case body and has an inner flow passage through which the sealed fluid flows, the inner flow passage being open to an outer circumferential side; a communication flow path connecting the outer flow path and the inner flow path, The inner flow path is a plurality of branch path portions that open at different positions in the circumferential direction on an outer circumferential side of the shaft; a main path portion that extends in the axial direction from an end face on one axial side of the shaft body toward the other axial side, and has a junction end portion on the other axial side where the plurality of branch path portions join; A rotary joint having

2. 2. The rotary joint according to claim 1, wherein the plurality of branch path sections include an inclined branch path section that extends from the junction end of the main path section to the outer circumferential side of the shaft body in a direction that forms an acute angle with respect to the axial direction toward the other axial side.

3. 3. The rotary joint according to claim 2, wherein the plurality of branch path portions include an extended branch path portion having an extension portion that extends in the axial direction from the junction end of the main path portion toward the other axial side.

4. 4. The rotary joint according to claim 3, wherein the extension branch path portion further has an inclined portion extending from the end portion on the other axial side of the extension portion to the outer periphery of the shaft body in a direction forming an acute angle with respect to the axial direction toward the other axial side.

5. 5. The rotary joint according to claim 3, wherein the inclined branch path portion and the extended branch path portion are open at an interval of 180 degrees from each other in the circumferential direction on the outer periphery side of the shaft body.

6. 5. The rotary joint according to claim 1, wherein the plurality of branch path portions include a first branch path portion and a second branch path portion that extend radially outward from the junction end of the main path portion to an outer circumferential side of the shaft body.

7. The rotary joint according to claim 6 , wherein the first branched path portion and the second branched path portion are open on the outer circumferential side of the shaft body at an interval of 180° from each other in the circumferential direction.

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