Rotary joint

Abstract

The rotary joint is provided with: a cylindrical housing which has an opening on the inner peripheral side and in which an outer flow path through which a fluid to be sealed flows is formed; a shaft body provided so as to be relatively rotatable within the housing, the shaft body having an opening on the outer peripheral side thereof and having formed therein an inner flow path through which the fluid to be sealed flows; and a communication flow path that connects the outer flow path and the inner flow path, the inner flow path having: a plurality of branch path sections that open at different positions in the circumferential direction on the outer circumferential side of the shaft body; and a main path section which extends in the axial direction from an end surface on one side in the axial direction of the shaft body toward the other side in the axial direction, and which has, on the other side in the axial direction, a confluence end section at which the plurality of branch path sections converge.

Description

Technical Field

[0001] This invention relates to a rotary joint. This application claims priority based on Japanese Application No. 2024-124731, filed on July 31, 2024, and incorporates the entire contents of the aforementioned Japanese application. Background Technology

[0002] Rotary joints are used to connect the flow paths of a fixed-side component and a rotating-side component. For example, in a CMP (Chemical Mechanical Polishing) apparatus used for surface grinding of semiconductor wafers, grinding fluid, pressurized air, cleaning water, pure water, purging air, grinding residue fluid, etc., flow as sealed fluid between the rotating-side component (top ring) and the fixed-side component (CMP apparatus body) that supports it. To ensure that such sealed fluids flow between the rotating-side component and the fixed-side component without mixing, multiple independent fluid passages need to be provided at the joint connecting these two components. Therefore, a multi-port rotary joint disclosed in Patent Document 1 is used as such a joint, for example.

[0003] Patent Document 1's rotary joint has a cylindrical housing, a shaft rotatably disposed within the housing, and a plurality of mechanical seals arranged axially between the housing and the shaft. Multiple radially penetrating outer flow paths are formed in the housing. Each outer flow path has an opening at a predetermined circumferential location on the inner circumferential surface of the housing.

[0004] At the shaft, the same number of inner flow paths (flow path holes) as the outer flow paths are formed, opening on the outer circumferential side of the shaft. Each inner flow path is formed in an L-shaped cross-section through a longitudinal hole extending axially inside the shaft and a transverse hole extending radially from the end of the longitudinal hole toward the outer circumferential surface of the shaft. Therefore, each inner flow path opens at a predetermined circumferential location on the outer circumferential surface of the shaft. In the rotary joint, multiple connecting flow paths are formed axially by multiple mechanical seals, which connect the openings of the outer flow paths on the inner circumferential surface of the housing with the openings of the inner flow paths on the outer circumferential surface of the shaft.

[0005] Patent Document 1: Japanese Patent Application Publication No. 2020-106052 Summary of the Invention

[0006] In rotary joints used in CMP (Cyclic MPa) devices, there is a need to reduce the pressure loss of the sealed fluid flowing within them. However, in conventional rotary joints, when the shaft rotates relative to the housing, the circumferential angle between the opening of the inner flow path (transverse orifice) on the outer circumferential surface of the shaft and the opening of the outer flow path on the inner circumferential surface of the housing becomes a maximum of 180°. If this angle becomes 180°, the circumferential distance the sealed fluid travels in the connecting flow path between the two openings increases, resulting in a greater pressure loss. Therefore, conventional rotary joints cannot effectively reduce the pressure loss of the sealed fluid.

[0007] The present invention was made in view of the above circumstances, and its object is to provide a rotary joint that can effectively reduce the pressure loss of the sealed fluid.

[0008] (1) The rotary joint of the present invention comprises: a cylindrical housing having an outer flow path for the flow of a sealed fluid formed by opening an opening on the inner circumferential side; a shaft having a rotatable relative structure within the housing having an inner flow path for the flow of the sealed fluid formed by opening an opening on the outer circumferential side; and a connecting flow path connecting the outer flow path to the inner flow path, the inner flow path having: a plurality of branch sections having openings at different circumferential positions on the outer circumferential side of the shaft; and a main flow section extending axially from an end face on one axial side of the shaft toward the other axial side, having a converging end on the other axial side where the plurality of branch sections converge.

[0009] According to the rotary joint of the present invention, the inner flow path of the shaft has multiple branch sections that open at different circumferential positions on the outer periphery of the shaft. Therefore, when the shaft rotates relative to the housing, the circumferential angle between the opening of the inner flow path (branch section) on the outer periphery of the shaft and the opening of the outer flow path on the inner periphery of the housing is at most less than 180°. Therefore, compared to conventional rotary joints, the circumferential flow distance of the sealed fluid is shortened in the connecting flow path between the inner and outer flow paths, thus reducing the pressure loss of the sealed fluid caused by the relative rotation of the shaft. Furthermore, in the inner flow path, the multiple branch sections converge at the confluence end of the main flow path, thus reducing the flow resistance at this confluence end compared to the flow resistance of the L-shaped bend in the conventional inner flow path. Therefore, the pressure loss of the sealed fluid can be reduced more effectively than with conventional rotary joints.

[0010] (2) In the rotary joint of (1), preferably, the plurality of branch sections include inclined branch sections extending from the confluence end of the main section to the outer periphery of the shaft in a direction at an acute angle relative to the axial direction toward the other side of the axial direction.

[0011] In this case, the inclined branch converges more gently to the confluence end of the main branch than the first branch (second branch) described later in (6). As a result, the flow resistance at the confluence end of the main branch is reduced, and thus, the pressure loss of the sealed fluid can be reduced more effectively.

[0012] (3) In the rotary joint of (2), preferably, the plurality of branch sections include an extended branch section having an extension portion extending along the axial direction from the confluence end of the main section toward the other side of the axial direction.

[0013] In this case, the angle between the inclined branch section and the extended branch section (extended portion) is an acute angle, which is smaller than the angle between the first branch section and the second branch section (180°) described later in (7). As a result, the flow resistance at the confluence end of the main flow section where the inclined branch section and the extended branch section converge is reduced, and thus, the pressure loss of the sealed fluid can be reduced more effectively.

[0014] (4) In the rotary joint of (3), preferably, the extended branch section also has an inclined portion extending from the end of the extended portion on the other side of the axial direction to the outer peripheral side of the shaft body in a direction at an acute angle relative to the axial direction toward the other side of the axial direction.

[0015] In this configuration, the extended branch section bends gently by an inclined portion extending at an acute angle relative to the axial direction from the end of the extended section on the other side of the axial direction. Therefore, compared to a case where the extended section bends radially perpendicularly from the end of the extended section, the flow resistance of the extended branch section is reduced, thus enabling more effective reduction of pressure loss of the sealed fluid.

[0016] (5) In the rotary joint of (3) or (4), preferably, the inclined branch section and the extended branch section are opened at a circumferential interval of 180° from each other on the outer periphery of the shaft.

[0017] In this configuration, the inclined branch section and the extended branch section (inclined portion) have openings spaced 180° apart circumferentially on the outer periphery of the shaft. Therefore, when the shaft rotates relative to the housing, the opening of the inclined branch section and the extended branch section on the outer periphery of the shaft that is closest in the circumferential direction to the opening of the outer flow path on the inner periphery of the housing forms a maximum circumferential angle of 90° with the opening of the outer flow path. Consequently, the circumferential flow distance of the sealed fluid in the connecting flow path between the inner and outer flow paths is further shortened, thus further reducing the pressure loss of the sealed fluid caused by the relative rotation of the shaft.

[0018] (6) In any of the rotary joints in (1) to (5), preferably, the plurality of branch sections include a first branch section and a second branch section extending radially outward from the confluence end of the main section to the outer periphery of the shaft.

[0019] In this case, the first branch section and the second branch section of the inner flow path are formed radially perpendicular to the main flow section extending axially, and thus, the first branch section and the second branch section can be formed more easily than the inclined branch section described in (2).

[0020] (7) In the rotary joint of (6), preferably, the first branch section and the second branch section are opened at a circumferential interval of 180° from each other on the outer periphery of the shaft.

[0021] In this configuration, the first and second branch sections of the inner flow path are opened at 180° intervals along the circumferential direction on the outer periphery of the shaft. Therefore, when the shaft rotates relative to the housing, the opening of the outer flow path, which is closest to the inner periphery of the housing in the circumferential direction among the two openings of the first and second branch sections on the outer periphery of the shaft, forms a maximum circumferential angle of 90° with the opening of the outer flow path. Thus, compared to conventional rotary joints, the circumferential flow distance of the sealed fluid in the connecting flow path between the inner and outer flow paths is shortened, thereby further reducing the pressure loss of the sealed fluid caused by the relative rotation of the shaft.

[0022] The effects of the invention

[0023] The rotary joint according to the present invention can effectively reduce the pressure loss of the sealed fluid. Attached Figure Description

[0024] Figure 1 This is a cross-sectional view showing the rotary joint according to the first embodiment of the present invention.

[0025] Figure 2 This is an enlarged cross-sectional view showing the lower side of the aforementioned rotary joint.

[0026] Figure 3 This is an enlarged cross-sectional view showing the upper side of the aforementioned rotary joint.

[0027] Figure 4 It is along Figure 2 The cross-sectional view observed by arrow II.

[0028] Figure 5 yes Figure 4 An explanatory diagram of the angles of the first inner flow path (second inner flow path) relative to the branch section.

[0029] Figure 6 This is a cross-sectional view showing the rotary joint according to the second embodiment of the present invention.

[0030] Figure 7 It means Figure 6 An enlarged sectional view of the lower side of the rotary joint.

[0031] Figure 8 It is along Figure 7 The cross-sectional view observed by arrow II-II.

[0032] Figure 9 It means Figure 6 An enlarged cross-sectional view of the upper side of the rotary joint.

[0033] Figure 10 This is a cross-sectional view of a rotary joint used as a reference example.

[0034] Figure 11 It means Figure 10 An enlarged sectional view of the lower side of the rotary joint.

[0035] Figure 12 It means Figure 10 An enlarged cross-sectional view of the upper side of the rotary joint. Detailed Implementation

[0036] Next, the preferred embodiments will be described with reference to the accompanying drawings.

[0037] [First Implementation]

[0038] <Overall Structure>

[0039] Figure 1This is a cross-sectional view showing the rotary joint 1 according to the first embodiment. The rotary joint 1 has a cylindrical housing 2 and a cylindrical shaft 3. The housing 2 is mounted on the fixed side component of the rotating device (e.g., the main body of a CMP device). The shaft 3 is mounted on the rotating side component of the rotating device (e.g., the top ring of a CMP device). In this embodiment, the housing 2 and the shaft 3 are arranged axially in the vertical direction.

[0040] Furthermore, in this invention, "axial" refers to the direction along the centerline X of the rotary joint 1 (including directions parallel to the centerline X). Additionally, in this invention, "radial" refers to the direction orthogonal to the centerline X of the rotary joint 1, and "circumferential" refers to the direction surrounding the centerline X of the rotary joint 1. The orientation of the rotary joint 1 can also be... Figure 1 Other postures besides those shown. In this invention, for ease of explanation, [the following will be used]. Figure 1 The lower axial side (one axial side) shown is designated as the "lower side" of rotary joint 1. Figure 1 The upper side of the axis shown (the other side of the axis) is designated as the "upper side" of rotary joint 1.

[0041] <Shell>

[0042] The housing 2 has a plurality of flanges 20 overlapping axially. Each flange 20 has an annular support flange 21 and a plurality of flow path flanges 22. The flow path flanges 22 are arranged in a bottom-up overlapping order: 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. 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 with an opening at the bottom.

[0043] The support flange 21 has an annular protrusion 211 that projects radially inward. Each flow path flange 22 has an annular protrusion 221 that projects radially inward on its upper part. The support flange 21 and the plurality of flow path flanges 22 are overlapped as described above and secured by a plurality of bolts 23 (in... Figure 1 Only one is shown in the diagram. Thus, the housing 2 is integrally formed as a topped cylindrical shape. The upper and lower adjacent flanges 20 are sealed to each other by O-ring gaskets 24.

[0044] <Outer Flow Path>

[0045] The housing 2 has multiple orifices, or outer flow paths 27, for the flow of the sealed fluid. These outer flow paths 27 include multiple first outer flow paths 27A, multiple second outer flow paths 27B, and a third outer flow path 27C. In this embodiment, the housing 2 has a total of eight outer flow paths 27, including four first outer flow paths 27A, three second outer flow paths 27B, and one third outer flow path 27C. The first outer flow paths 27A and second outer flow paths 27B are alternately formed at predetermined intervals along the axial direction. The third outer flow path 27C is formed at the uppermost part of the housing 2.

[0046] The first outer flow path 27A is formed radially through a predetermined circumferential portion at the lower part (excluding the protrusion 221) of each flow path flange 22. The second outer flow path 27B is formed radially through a predetermined circumferential portion at the upper part (protrusion 221) of each flow path flange 22 except for the fourth flow path flange 22D. The third outer flow path 27C is formed radially through a predetermined circumferential portion at the upper part (protrusion 221) of the fourth flow path flange 22D. Examples of fluids to be sealed include grinding fluid, pressurized air, inert gases such as nitrogen, cleaning water, pure water, purging air, and grinding residue fluid.

[0047] The outer flow path 27 has an opening on the inner circumferential side, i.e., the inner circumferential surface, of the flow path flange 22. The opening 271 on the inner circumferential side of the outer flow path 27 (see also...) Figure 2 It is connected to the connecting flow path 70 described later. To reduce the pressure loss of the sealed fluid, the center of the opening 271 of the first outer flow path 27A coincides with the center of the hole of the first outer flow path 27A. In addition, to reduce the pressure loss of the sealed fluid, the diameter of the opening 271 of the first outer flow path 27A is larger than the diameter of the through hole 71b of the first connecting flow path 71. The outer flow path 27 has an opening on the outer peripheral side, i.e., the outer peripheral surface, of the flow path flange 22. The opening 272 on the outer peripheral side of the outer flow path 27 is provided as a connection port for connecting to the multiple pipes of the aforementioned fixed side component respectively.

[0048] <Spindle>

[0049] The shaft body 3 is disposed within the housing 2. The shaft body 3 has a shaft body portion 31 extending in the vertical direction, a large-diameter portion 32 disposed at the lower end of the shaft body portion 31, and a small-diameter portion 33 disposed at the upper end of the shaft body portion 31. The outer diameter of the large-diameter portion 32 is larger than the outer diameter of the shaft body portion 31. The outer diameter of the small-diameter portion 33 is smaller than the outer diameter of the shaft body portion 31.

[0050] A rolling bearing 4 is provided between the large-diameter portion 32 of the shaft 3 and the support flange 21. A rolling bearing 5 is provided between the small-diameter portion 33 of the shaft 3 and the fourth flow path flange 22D. Thus, the shaft 3 is supported in a manner that allows it to rotate about the center line X relative to the housing 2.

[0051] <Inner Flow Path>

[0052] Multiple orifices, or inner flow paths 35, are formed within the shaft body 3 to allow the sealed fluid to flow. Each inner flow path 35 is, for example, circular in cross-section. The multiple inner flow paths 35 are formed circumferentially spaced apart from each other within the shaft body 3. Figure 1 For convenience, multiple inner flow paths 35 are shown together at one circumferential location. One end of each inner flow path 35 is opened at a different circumferential position on the lower end face 3a of the shaft body 3. The other end of each inner flow path 35 is opened at a different axial position on the outer circumference of the shaft body 3.

[0053] 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.

[0054] Each of the multiple first inner flow paths 35A opens at the same axial position as the opening 271 of each of the first outer flow paths 27A on the inner circumference side of the housing 2, i.e., the outer circumferential surface of the shaft 3. Each of the multiple second inner flow paths 35B opens at the same axial position as the opening 271 of each of the second outer flow paths 27B on the inner circumferential side of the housing 2 (refer to...). Figure 2 An opening is made at the same axial position. The third inner flow path 35C is located on the outer peripheral side of the shaft body 3, i.e., on the upper end face 31a of the shaft body 31 (see reference). Figure 3 (Open an opening.)

[0055] Each inner flow path 35 has a main flow section 36 and multiple (in Figure 1 There are two branch sections 37. The main section 36 extends straight along the axial direction from the lower end face 3a of the shaft 3 toward the upper side (the other side of the axial direction). The main section 36 has an opening on the lower end face 3a of the shaft 3. The opening on the lower side of the main section 36 is connected to the piping of the aforementioned rotating side component. The upper end of the main section 36 is provided as a confluence end 36a for the convergence of the multiple branch sections 37. The confluence end 36a of the main section 36 is located slightly lower in the axial direction than the opening 271 of the corresponding outer flow path 27.

[0056] <Branch Road Section>

[0057] Figure 2 This is an enlarged sectional view showing the lower side of rotary joint 1. Figure 2In the inner flow path 35, two branch paths 37 have openings at different circumferential positions on the outer periphery of the shaft 3, converging at the confluence end 36a of the main flow path 36. The two branch paths 37 in this embodiment include an inclined branch path 371 and an extended branch path 372. Both the inclined branch path 371 and the extended branch path 372 have the same flow path cross-sectional area as the main flow path 36. Furthermore, at least one of the inclined branch path 371 and the extended branch path 372 may have a different flow path cross-sectional area than the main flow path 36.

[0058] The inclined branch section 371 extends from the confluence end 36a of the main section 36 to the outer periphery of the shaft 3, in a direction that forms an acute angle with respect to the axial direction upwards (in... Figure 2 The inclined branch section 371 extends obliquely upwards (to the left and slightly upwards). In this embodiment, the inclined branch section 371 extends approximately 50° upwards relative to the axial direction from the confluence end 36a of the main branch section 36. Thus, the inclined branch section 371 differs from that in the second embodiment described later (…). Figure 7 Compared to the first branch road section 376 (second branch road section 377), the flow merges more smoothly into the confluence end 36a of the main road section 36.

[0059] Each inclined branch 371 of the first inner flow path 35A and the second inner flow path 35B has an opening on the outer peripheral side, i.e., the outer peripheral surface, of the shaft body 3. The opening 371a is located at the same axial position as the opening 271 of the corresponding outer flow path 27.

[0060] Each extended branch section 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 axially straight upward from the confluence end 36a of the main flow path 36. Therefore, the angle between the inclined branch section 371 and the extended branch section 372 (extended portion 373) is an acute angle. Thus, in the axial cross-sectional view of the first inner flow path 35A and the second inner flow path 35B of this embodiment ( Figure 2 When formed into an approximate Y shape, the extension portion 373 extends from the lower side to a closer axial position relative to the opening 271 of the corresponding outer flow path 27.

[0061] The inclined portion 374 of the extended branch section 372 extends from the upper end of the extended portion 373 to the outer peripheral surface of the shaft body 3, in a direction forming an acute angle upward relative to the axial direction (in Figure 2 The extension branch 372 extends obliquely upwards (to the right). In this embodiment, the oblique portion 374 is inclined upwards at approximately 45° relative to the axial direction from the aforementioned end of the extension portion 373. As a result, the extension branch portion 372 bends gently from the aforementioned end of the extension portion 373 due to the oblique portion 374, and an opening is formed on the outer peripheral surface of the shaft body 3.

[0062] The 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 path 27. Therefore, the inclined portion 374 has an opening at the same axial position as the inclined branch portion 371 on the outer peripheral surface of the shaft 3. The opening 374a of the inclined portion 374 is connected to the corresponding first connecting flow path 71 (described later) or second connecting flow path 72 (described later).

[0063] Figure 3 This is an enlarged sectional view showing the upper side of rotary joint 1. Figure 3 In the middle, the inclined branch section 371 of the third inner flow path 35C has an opening at the corner of the outer periphery of the shaft body 3, that is, the shaft body 31 and the small diameter section 33. This opening 371b is connected to the third connecting flow path 73 described later.

[0064] The extended branch section 372 of the third inner flow path 35C has only an extended portion 375. The extended portion 375 extends axially straight upwards from the confluence end 36a of the main flow path 36. The angle between the inclined branch section 371 and the extended branch section 372 (extended portion 375) is an acute angle. Therefore, in axial cross-sectional view, the third inner flow path 35C of this embodiment... Figure 3 When formed into an approximate Y shape, the extended portion 375 has an opening on the end face 31a on the outer periphery of the shaft body 3, i.e., on the upper side of the shaft body 31. This opening 375a is connected to the third connecting flow path 73 described later.

[0065] Figure 4 It is along Figure 2 The cross-sectional view observed by arrow II. Figure 2 and Figure 4 In this embodiment, the branch sections 37 of the first inner flow path 35A and the second inner flow path 35B, namely the inclined branch section 371 and the extended branch section 372 (inclined portion 374), have openings spaced apart from each other circumferentially on the outer peripheral surface of the shaft body 3. In this embodiment, the inclined branch section 371 and the extended branch section 372 have openings spaced apart from each other 180° circumferentially.

[0066] Third inner flow path 35C (refer to) Figure 3 The branch sections 37, namely the inclined branch section 371 and the extended branch section 372 (extension portion 375), are provided with openings spaced apart from each other in the circumferential direction on the outer periphery of the shaft body 3. In this embodiment, the inclined branch section 371 and the extended branch section 372 of the third inner flow path 35C are provided with openings spaced apart from each other in the circumferential direction on the outer periphery of the shaft body 3 at intervals of 180°.

[0067] When the shaft 3 rotates relative to the housing 2, the multiple openings 371a, 374a, and 375a of the branch section 37 on the outer peripheral surface of the shaft 3 rotate together with the shaft 3. Therefore, the circumferential angle α1 formed by the opening 371a of the inclined branch section 37 and the opening 271 of the outer flow path 27 on the inner peripheral surface of the housing 2 (refer to...) Figure 5 The angle α2 formed by the opening 374a (opening 375a) of the extended branch section 372 in the branch section 37 and the opening 271 of the outer flow path 27 at the inner circumferential surface of the housing 2 (refer to...) changes with the rotation of the shaft 3. Figure 5 This changes as shaft 3 rotates. The following uses... Figure 4 and Figure 5 The details are explained below.

[0068] Figure 5 Is with Figure 4 Explanation diagram of angles α1 and α2 related to the branch section 37 of the first inner flow path 35A (second inner flow path 35B). And the third inner flow path 35C (see...) Figure 3 The angles α1 and α2 related to the branch road 37 are also the same, therefore, the explanation is omitted.

[0069] like Figure 5 As shown, angle α1 is the circumferential angle formed by the center of the opening 371a of the inclined branch section 371 and the center of the opening 271 of the outer flow path 27, centered on the center line X of the rotary joint 1. Angle α2 is the circumferential angle formed by the center of the opening 374a of the extended branch section 372 and the center of the opening 271 of the outer flow path 27, centered on the center line X of the rotary joint 1.

[0070] The angle α1 changes in the following manner: at the position after the opening 371a of the inclined branch section 371 is rotated 180° relative to the opening 271 of the outer flow path 27 (in... Figure 5 The angle α2 is maximized at the 3 o'clock position. Similarly, the angle α2 changes in the following manner: at the position after the opening 374a of the extended branch 372 is rotated 180° relative to the opening 271 of the outer flow path 27 (at the 3 o'clock position). Figure 5 The angle α1 and α2, which change with the rotation of axis 3, are at their maximum at the 3 o'clock position. Therefore, the maximum value of each angle α1 and α2 is 180°.

[0071] As described above, the openings 371a of the inclined branch section 371 and 374a of the extended branch section 372 are formed at 180° intervals (phase difference) along the circumferential direction on the outer peripheral surface of the shaft body 3. Therefore, when angle α1 is 90°, angle α2 is also 90°. Furthermore, as... Figure 5As shown, if one of the two angles α1 and α2 exceeds 90°, then the other angle is less than 90°. Therefore, during the rotation of shaft 3, either angle α1 or α2 is always less than or equal to 90°.

[0072] As described above, when the shaft 3 rotates relative to the housing 2, the opening among the plurality of openings 371a and 374a of the branch section 37 that is closest in the circumferential direction to the opening 271 of the outer flow path 27 (in) Figure 5 The opening in the middle is 371a), and the angle α formed by the opening 271 of the outer flow path 27 is up to 90°.

[0073] In contrast, as described above, the circumferential angle between the opening of the inner flow path (transverse hole) on the outer circumferential surface of the shaft and the opening of the outer flow path on the inner circumferential surface of the housing is increased to a maximum of 180°.

[0074] Therefore, compared to conventional rotary joints, the maximum value of angle α in this embodiment is smaller. Consequently, in this embodiment, compared to conventional rotary joints, the distance the sealed fluid travels circumferentially in the connecting flow path 70 (described later), which connects the inner flow path 35 and the outer flow path 27, can be shortened.

[0075] <Mechanical Seals>

[0076] exist Figure 1 In this configuration, the rotary joint 1 has multiple (in) arranged between the housing 2 and the shaft 3. Figure 1 There are four mechanical seals 6. Multiple mechanical seals 6 are arranged axially between the housing 2 and the shaft 3. Each mechanical seal 6 is disposed on the inner circumferential side of two adjacent flanges 20 on the upper and lower sides of the housing 2. Hereinafter, the flange 20 disposed on the upper side will be referred to as the "upper flange 20", and the flange 20 disposed on the lower side will be referred to as the "lower flange 20".

[0077] exist Figure 2 In this embodiment, each mechanical seal 6 has a first housing-side sealing ring 61, a second housing-side sealing ring 62, and a shaft-side sealing ring 63. The first housing-side sealing ring 61 and the second housing-side sealing ring 62 are housing-side sealing rings provided on the inner circumferential side of the housing 2. The shaft-side sealing ring 63 is configured on the outer circumferential side of the shaft 3 to be rotatable integrally with the shaft 3. In this embodiment, the housing-side sealing rings 61 and 62 function as stationary sealing rings. In addition, the shaft-side sealing ring 63 functions as a rotating sealing ring that slides relative to the housing-side sealing rings 61 and 62.

[0078] The first housing-side sealing ring 61 and the second housing-side sealing ring 62 are disposed above and below the shaft-side sealing ring 63 in a manner that sandwiches it. The first housing-side sealing ring 61 and the second housing-side sealing ring 62 are respectively arranged axially opposite to the shaft-side sealing ring 63. The first housing-side sealing ring 61 and the second housing-side sealing ring 62 are each formed into annular shape.

[0079] The first housing-side sealing ring 61 is installed on the lower flange 20 (in Figure 2 The middle part is the supporting flange 21). Specifically, the first housing-side sealing ring 61 is embedded in the inner circumference of the protrusion 211 (221) of the lower flange 20. A sealing surface 61a is formed on the upper end face of the first housing-side sealing ring 61.

[0080] The second housing side sealing ring 62 is installed on the upper flange 20 of the upper and lower adjacent flanges 20 of the housing 2. Figure 2 The first flow path flange 22A is shown in the middle. Specifically, the second housing-side sealing ring 62 is embedded in the inner circumferential side of the protrusion 221 of the upper flange 20. A sealing surface 62a is formed on the lower end face of the second housing-side sealing ring 62.

[0081] The radially outer portions of each housing-side sealing ring 61, 62 abut against a pin 25 that is fixed in an axial (vertical) manner at the protrusion 221 of the flange 20. Thus, each housing-side sealing ring 61, 62 is held in place by the housing 2, preventing rotation with the axial-side sealing ring 63. An O-ring 68 seals the space between each housing-side sealing ring 61, 62 and the protrusion 221 of the flange 20.

[0082] The axial sealing ring 63 is formed in an annular shape. The axial sealing ring 63 fits into the outer peripheral surface of the shaft body 3 at the same axial position as the openings 371a and 374a on the outer peripheral side of the first inner flow path 35A. An annular sealing surface 63a is formed on the lower end face of the axial sealing ring 63, contacting the sealing surface 61a of the first housing-side sealing ring 61. An annular sealing surface 63b is formed on the upper end face of the axial sealing ring 63, contacting the sealing surface 62a of the second housing-side sealing ring 62. A pair of upper and lower O-rings 69, sandwiched between the inner peripheral surface of the axial sealing ring 63 and the outer peripheral surface of the shaft body 3, provide a seal.

[0083] Each mechanical seal 6 has a first elastic element 64 and a second elastic element 65. The first elastic element 64 and the second elastic element 65 are, for example, compression coil springs. The first elastic element 64 is mounted on the lower flange 20. The second elastic element 65 is mounted on the upper flange 20. Furthermore, the first elastic element 64 and the second elastic element 65 are not limited to compression coil springs and may be other elastic elements.

[0084] When the first elastic member 64 is in a compressed state, it is inserted into the protrusion 221 of the flange 20 on the lower side, where multiple protrusions are formed circumferentially (in... Figure 2 Only one insertion hole 222 is shown in the figure. The upper end of the first elastic member 64 abuts against the first housing-side sealing ring 61. Through the elastic restoring force of the first elastic member 64, the first housing-side sealing ring 61 is pressed upward (towards the axial-side sealing ring 63). Thus, an axial pressing force is applied between the two sealing surfaces 61a and 63a of the first housing-side sealing ring 61 and the axial-side sealing ring 63.

[0085] In a compressed state, the second elastic member 65 is inserted into the protrusion 221 of the upper flange 20, where multiple protrusions are formed circumferentially (in... Figure 2 Only one insertion hole 223 is shown in the figure. The lower end of the second elastic member 65 abuts against the second housing-side sealing ring 62. Due to the elastic restoring force of the second elastic member 65, the second housing-side sealing ring 62 is pressed downward (towards the axial-side sealing ring 63). Thus, an axial pressing force is applied between the two sealing surfaces 62a and 63b of the second housing-side sealing ring 62 and the axial-side sealing ring 63.

[0086] By rotating the shaft 3 relative to the housing 2, the sealing surfaces 63a and 63b of the shaft-side sealing ring 63 are pressed against the sealing surface 61a of the first housing-side sealing ring 61 and the sealing surface 62a of the second housing-side sealing ring 62, respectively. Therefore, the sealing function of the mechanical seal 6 is achieved through the sliding action between the sealing surfaces 61a and 63a associated with the relative rotation of the first housing-side sealing ring 61 and the shaft-side sealing ring 63, and the sliding action between the sealing surfaces 62a and 63b associated with the relative rotation of the second housing-side sealing ring 62 and the shaft-side sealing ring 63. Hereinafter, the portion where the sealing surfaces 61a and 63a slide against each other will be referred to as the sliding portion 66, and the portion where the sealing surfaces 62a and 63b slide against each other will be referred to as the sliding portion 67.

[0087] <Connected Flow Path>

[0088] like Figure 1 As shown, the rotary joint 1 has multiple connecting flow paths 70 formed between the housing 2 and the shaft 3 by multiple mechanical seals 6. The multiple connecting flow paths 70 include multiple first connecting flow paths 71, multiple second connecting flow paths 72, and a third connecting flow path 73. The rotary joint 1 of this embodiment has a total of eight connecting flow paths 70, including four first connecting flow paths 71, three second connecting flow paths 72, and one third connecting flow path 73.

[0089] The first connecting flow path 71 is a flow path that connects the first outer flow path 27A and the first inner flow path 35A. The second connecting flow path 72 is a flow path that connects the second outer flow path 27B and the second inner flow path 35B. The third connecting flow path 73 is a flow path that connects the third outer flow path 27C and the third inner flow path 35C.

[0090] exist Figure 2 and Figure 4 In this configuration, a first connecting flow path 71 is formed at an axial position corresponding to each mechanical seal 6. The first connecting flow path 71 comprises an outer annular path 71a, an inner annular path 71c, and multiple (in...) Figure 4 It consists of 4 through holes 71b.

[0091] The outer annular path 71a of the first connecting flow path 71 is an annular space formed radially outside the axial sealing rings 63 of each mechanical seal 6, between the protrusions 221, 221(211) of the upper and lower adjacent flanges 20. The outer annular path 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 gasket 24, 68. The outer annular path 71a is connected to the first outer flow path 27A of the corresponding flange 20 at a predetermined position in its circumference.

[0092] Multiple through holes 71b and an inner annular path 71c in the first connecting flow path 71 are formed on the axial sealing ring 63 of each mechanical seal 6. The inner annular path 71c is formed by an annular groove formed on the inner circumference of the axial sealing ring 63 and the outer circumferential surface of the shaft body 3. The inner annular path 71c is sealed by the sealing function of a pair of upper and lower O-rings 69. The inner annular path 71c is connected to the corresponding first inner flow path 35A (inclined branch 371 and extended branch 372) of the shaft body 3 at a predetermined position in its circumference. Each through hole 71b is formed to pass through the radial direction of the axial sealing ring 63 at intervals along the circumference of the axial sealing ring 63. Each through hole 71b connects the outer annular path 71a and the inner annular path 71c.

[0093] As described above, the first connecting flow path 71 connects the first outer flow path 27A of the housing 2 to the first inner flow path 35A of the shaft 3. The first outer flow path 27A, the first connecting flow path 71, and the first inner flow path 35A constitute an independent first fluid passage 11 for the flow of the sealed fluid. Therefore, the rotary joint 1 of this embodiment has multiple (in) axially arranged... Figure 1 There are four independent first fluid passages 11 in this embodiment. In each of the first fluid passages 11, the sealed fluid flows from the first outer flow passage 27A through the first connecting flow passage 71 to the first inner flow passage 35A.

[0094] exist Figure 2In this configuration, the second connecting flow path 72 is formed between the axial sealing rings 63 of two adjacent mechanical seals 6. The second connecting flow path 72 consists of an outer annular path 72a and an inner annular path 72b.

[0095] The outer annular passage 72a of the second connecting flow path 72 is an annular space formed between the second housing-side sealing ring 62 of the lower mechanical seal 6 and the first housing-side sealing ring 61 of the upper mechanical seal 6, which are two adjacent mechanical seals 6. The outer annular passage 72a is sealed by the sealing function of O-rings 68 arranged on its upper and lower sides respectively. The outer annular passage 72a is connected to the second outer flow path 27B of the corresponding flange 20 at a specified circumferential position.

[0096] The inner annular path 72b of the second connecting flow path 72 is an annular gap formed between the two inner circumferential surfaces of the second housing-side sealing ring 62 and the first housing-side sealing ring 61 that form the outer annular path 72a and the outer circumferential surface of the shaft 3. The inner annular path 72b is sealed by the sealing function of O-rings 69 arranged on its upper and lower sides respectively. The inner annular path 72b is connected to the outer annular path 72a. In addition, at a predetermined position in its circumference, the inner annular path 72b is connected to the corresponding second inner flow path 35B (inclined branch section 371 and extended branch section 372) of the shaft 3.

[0097] As described above, the second connecting flow path 72 connects the second outer flow path 27B of the housing 2 to the second inner flow path 35B of the shaft 3. The second outer flow path 27B, the second connecting flow path 72, and the second inner flow path 35B constitute an independent second fluid passage 12 for the flow of the sealed fluid. Therefore, the rotary joint 1 of this embodiment has multiple (in) axially arranged... Figure 1 There are three independent second fluid passages 12. In each of the second fluid passages 12 in this embodiment, the sealed fluid flows from the second outer flow passage 27B through the second connecting flow passage 72 to the second inner flow passage 35B.

[0098] exist Figure 3 In this configuration, the third connecting flow path 73 is positioned higher than the axial sealing ring 63 of the uppermost mechanical seal 6. The third connecting flow path 73 is sealed by the sealing function of O-rings 68 and 69 arranged radially outward and downward, and by the sealing function of the sliding portion 67 of the uppermost mechanical seal 6. The third connecting flow path 73 consists of an outer annular path 73a and an inner annular path 73b.

[0099] The outer annular path 73a of the third connecting flow path 73 is an L-shaped annular space formed between the second housing-side sealing ring 62 of the uppermost mechanical seal 6 and the fourth flow path flange 22D. The outer annular path 73a is connected to the third outer flow path 27C of the fourth flow path flange 22D at a specified circumferential position.

[0100] The inner annular path 73b of the third connecting flow path 73 is a space formed between the upper end face 31a of the shaft body 31 and the lower surface of the central part of the fourth flow path flange 22D. The inner annular path 73b is connected to the outer annular path 73a. In addition, the inner annular path 73b is connected to the third inner flow path 35C (inclined branch path 371 and extended branch path 372) of the shaft body 3 at a predetermined position in its circumference.

[0101] As described above, the third connecting flow path 73 connects the third outer flow path 27C of the housing 2 to the third inner flow path 35C of the shaft 3. The third outer flow path 27C, the third connecting flow path 73, and the third inner flow path 35C constitute a single independent third fluid passage 13 for the flow of the sealed fluid. Therefore, the rotary joint 1 of this embodiment has a single independent third fluid passage 13. In the third fluid passage 13 of this embodiment, the sealed fluid flows from the third outer flow path 27C through the third connecting flow path 73 to the third inner flow path 35C.

[0102] <Effects>

[0103] According to the rotary joint 1 of the first embodiment, the inner flow path 35 of the shaft 3 has multiple branch sections 37 that open at different circumferential positions on the outer periphery of the shaft 3. As a result, when the shaft 3 rotates relative to the housing 2, the opening 371a (371b) and 374a of the inner flow path 35 (branch section 37) on the outer periphery of the shaft 3, which is closest in the circumferential direction to the opening 271 of the outer flow path 27 on the inner periphery of the housing 2, forms a circumferential angle α with the opening 271 of the outer flow path 27, which is at most less than 180°.

[0104] Therefore, compared to conventional rotary joints, the distance the sealed fluid travels in the circumferential direction in the connecting flow path 70 between the inner flow path 35 and the outer flow path 27 is shortened, thereby reducing the pressure loss of the sealed fluid caused by the rotation of the shaft 3. Furthermore, in the inner flow path 35, multiple branch paths 37 converge to the confluence end 36a of the main flow path 36, thus reducing the flow resistance at this confluence end 36a compared to the flow resistance of the L-shaped bend in the conventional inner flow path.

[0105] Based on the above, the rotary joint 1 of this embodiment can effectively reduce the pressure loss of the sealed fluid compared with 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, if the flow path diameter becomes smaller, the flow path resistance of each inner flow path 35 increases. Therefore, in such cases, the rotary joint 1 of the present invention is more effective.

[0106] The branch section 37 of the inner flow path 35 includes an inclined branch section 371 extending from the main flow section 36 to the outer periphery of the shaft 3 at an acute angle to the upper side relative to the axial direction. Therefore, the inclined branch section 371 is more inclined than that in the second embodiment described later. Figure 7 The first branch section 376 (second branch section 377) merges more smoothly into the confluence end 36a of the main section 36. As a result, the flow resistance at the confluence end 36a of the main section 36 can be reduced, and thus, the pressure loss of the sealed fluid can be reduced more effectively.

[0107] The branch section 37 of the inner flow path 35 includes an extended branch section 372, which has extension portions 373 and 375 extending axially from the main flow section 36 toward the upper side. Therefore, the angle between the inclined branch section 371 and the extended branch section 372 (extension portions 373 and 375) is an acute angle, which is greater than that described later in the second embodiment. Figure 7 The angle (180°) between the first branch section 376 and the second branch section 377 is small. As a result, the flow resistance at the confluence end 36a of the main channel 36, where the inclined branch section 371 and the extended branch section 372 converge, is lower, thus reducing the pressure loss of the sealed fluid more effectively. In particular, when the sealed fluid flows from the inclined branch section 371 and the extended branch section 372 toward the main channel 36, the sealed fluid flows smoothly downwards at the confluence end 36a of the main channel 36, thus effectively reducing the flow resistance at the confluence end 36a.

[0108] The extended branch sections 372 of the first inner flow path 35A and the second inner flow path 35B also have an inclined portion 374 extending from the extended portion 373 to the outer peripheral surface of the shaft 3 at an acute angle upward relative to the axial direction. Therefore, the extended branch section 372 bends gently through the inclined portion 374. As a result, compared to the case where it bends radially perpendicularly from the upper end of the extended portion 373, the flow resistance of the extended branch section 372 is reduced, thus enabling more effective reduction of pressure loss of the sealed fluid.

[0109] The inclined branch section 371 and extended branch section 372 of the inner flow path 35 are opened at circumferential intervals of 180° on the outer periphery of the shaft body 3. Therefore, when the shaft body 3 rotates relative to the housing 2, the opening 371a (371b) and 374a of the inclined branch section 371 and extended branch section 372 on the outer periphery of the shaft body 3, which is closest in the circumferential direction to the opening 271 of the outer flow path 27 on the inner periphery of the housing 2, forms a maximum circumferential angle α of 90° with the opening 271 of the outer flow path 27. Therefore, in the connecting flow path 70 between the inner flow path 35 and the outer flow path 27, the circumferential flow distance of the sealed fluid is further shortened, thereby further reducing the pressure loss of the sealed fluid caused by the rotation of the shaft body 3.

[0110] <Variation Example>

[0111] In the rotary joint 1 of the first embodiment, each inner flow path 35 of the shaft 3 has an inclined branch path 371 and an extended branch path 372 as a plurality of branch path sections 37, but all branch path sections 37 may also be set as inclined branch path sections 371.

[0112] [Second Implementation]

[0113] Figure 6 This is a cross-sectional view showing the rotary joint 1 according to the second embodiment of the present invention. Figure 7 This is an enlarged cross-sectional view showing the lower side of the rotary joint 1 in this embodiment. The structure of the inner flow paths 35 of the shaft body 3 of the rotary joint 1 in the second embodiment is different from that in the first embodiment.

[0114] <First inner flow path and second inner flow path>

[0115] exist Figure 6 and Figure 7 In this embodiment, each of the first inner flow paths 35A and each of the second inner flow paths 35B respectively has a main flow portion 36 and multiple (in) Figure 6 There are two branch sections 37. The confluence end 36a of the main flow section 36 extends to the same axial position as the opening 271 of the corresponding outer flow path 27. The multiple branch sections 37 include a first branch section 376 and a second branch section 377. The first branch section 376 and the second branch section 377 have the same flow path cross-sectional area as the main flow section 36. In addition, at least one of the first branch section 376 and the second branch section 377 may have a different flow path cross-sectional area than the main flow section 36.

[0116] Figure 8 It means along Figure 7 The cross-sectional view observed by arrow II-II. Figure 7 and Figure 8In the middle, the first branch section 376 and the second branch section 377 extend radially outward from the confluence end 36a of the main section 36 to the outer periphery of the shaft body 3. The first branch section 376 and the second branch section 377 have openings spaced apart from each other in the circumferential direction on the outer periphery of the shaft body 3.

[0117] In this embodiment, the first branch section 376 and the second branch section 377 have openings spaced 180° apart in the circumferential direction on the outer peripheral side, i.e., the outer peripheral surface, of the shaft body 3. That is, the first branch section 376 and the second branch section 377 extend in opposite directions from the confluence end 36a of the main section 36, as observed in axial cross-sectional view ( Figure 7 The angle between the two is 180°. The first branch section 376 and the second branch section 377 are formed perpendicular to the main section 36. Therefore, in the axial cross-sectional view of this embodiment, the inner flow path 35 ( Figure 7 When formed into a T-shape, the opening 376a of the first branch section 376 and the opening 377a of the second branch section 377 on the outer peripheral surface of the shaft 3 are located at the same axial position as the opening 271 of the corresponding outer flow path 27.

[0118] If the first embodiment (refer to) Figure 5 If the openings 371a and 374a of the branch section 37 of the present embodiment are replaced with the openings 376a and 377a of the branch section 37 of the present embodiment, then the angles α1 and α2 related to the branch section 37 of the first inner flow path 35A (second inner flow path 35B) of the present embodiment are also the same, therefore, the description is omitted.

[0119] <Third inner flow path>

[0120] Figure 9 This is an enlarged cross-sectional view showing the upper side of the rotary joint 1 in this embodiment. Figure 6 and Figure 9 In this embodiment, the third inner flow path 35C only has a main flow section 38. The main flow section 38 extends axially straight from the lower end face 3a of the shaft body 3 toward the upper side.

[0121] One end of the main flow section 38 has an opening on the lower end face 3a of the shaft body 3. The opening on the lower side of the main flow section 38 is connected to the piping of the aforementioned rotating side component. The other end of the main flow section 38 has an opening on the upper end face 31a of the shaft body 31, and this opening 38a is connected to the third connecting flow path 73.

[0122] The other structures of this embodiment are the same as those of the first embodiment, so the same reference numerals are used and the description is omitted.

[0123] <Effects>

[0124] According to the rotary joint 1 of the second embodiment, the inner flow path 35 of the shaft 3 (excluding the third inner flow path 35C) has a plurality of branch paths 37 that open at different circumferential positions on the outer peripheral surface of the shaft 3. Thus, similar to the first embodiment, the pressure loss of the sealed fluid can be reduced more effectively than conventional rotary joints.

[0125] The branch section 37 of the inner flow path 35 includes a first branch section 376 and a second branch section 377 extending radially outward from the main flow section 36 to the outer peripheral surface of the shaft body 3. Thus, the first branch section 376 and the second branch section 377 are formed perpendicular to the axially extending main flow section 36, and therefore, compared with the first embodiment (… Figure 1 Compared to the inclined branch section 371, the first branch section 376 and the second branch section 377 can be formed more easily.

[0126] The first branch section 376 and the second branch section 377 of the inner flow path 35 are opened at circumferential intervals of 180° on the outer peripheral surface of the shaft body 3. Therefore, when the shaft body 3 rotates relative to the housing 2, the circumferential angle α formed between the opening 376a and 377a of the first branch section 376 and the second branch section 377 on the outer peripheral surface of the shaft body 3, which is closest to the opening 271 of the outer flow path 27 on the inner peripheral surface of the housing 2, and the opening 271 of the outer flow path 27 is at most 90°. Therefore, in the connecting flow path 70 between the inner flow path 35 and the outer flow path 27, the circumferential distance of the sealed fluid is shorter than that of a conventional rotary joint, thus further reducing the pressure loss of the sealed fluid caused by the rotation of the shaft body 3.

[0127] [Effect Confirmation Test]

[0128] As an experiment to confirm the effectiveness of the rotary joints in the first and second embodiments, the inventors of this application conducted an analysis using simulations with fluid analysis software. In this experiment, a total of four rotary joints were analyzed: the conventional one, the first embodiment, the aforementioned variation of the first embodiment (a variation in which all branch sections 37 are set as inclined branch sections 371), and the second embodiment.

[0129] Specifically, through simulation, the pressure difference between the sealed fluid at the inlet and outlet (the opening of the inner flow path 35 on the end face 3a of the shaft 3) of the rotary joint 1 is calculated under the condition that the flow rate of the sealed fluid flowing into it from the inlet (the opening 272 on the outer periphery of the outer flow path 27) of each rotary joint is constant. The smaller the aforementioned pressure difference, the smaller the pressure loss of the sealed fluid.

[0130] In this experiment, after calculating the aforementioned pressure difference for each of the four rotary joints, the ratio of the aforementioned pressure difference of the rotary joint in each embodiment (modification) to the aforementioned pressure difference of the conventional rotary joint was calculated. The aforementioned ratio shows how much the pressure loss of the sealed fluid is reduced by the rotary joint in each embodiment (modification) compared to the conventional rotary joint, i.e., the improvement in pressure loss reduction. The larger the aforementioned ratio, the more effectively the pressure loss of the sealed fluid is reduced. Table 1 below shows the analytical results of the simulation in this experiment.

[0131] Table 1

[0132]

[0133] As shown in Table 1, it was confirmed that the pressure loss of the sealed fluid could 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.

[0134] [Reference Example]

[0135] Figure 10 This is a cross-sectional view of rotary joint 1 as a reference example. Figure 11 This is an enlarged sectional view showing the lower side of the rotary joint 1 of this reference example. The structure of the inner flow paths 35 of the shaft 3 of the rotary joint 1 of this reference example differs from that of the first embodiment. Figure 10 and Figure 11 In this reference example, each inner flow path 35 has a single main flow section 41 and a single inclined flow section 42.

[0136] The main flow section 41 extends vertically upward from the lower end face 3a of the shaft body 3. An opening is formed in the lower end face 3a of the main flow section 41. A pipe for the aforementioned rotating side component is connected to the lower opening of the main flow section 41. The upper end face 41a of the main flow section 41 is located slightly lower in the axial direction compared to the opening 271 of the corresponding outer flow path 27.

[0137] The inclined road section 42 extends from the upper end 41a of the main road section 41 to the outer periphery of the shaft body 3, in a direction forming an acute angle with respect to the axial direction upwards (in... Figure 10 The inclined road section 42 extends obliquely upwards (to the left and slightly upwards). In this reference example, the inclined road section 42 is inclined upwards at approximately 50° relative to the axial direction, starting from the road end 41a on the upper side of the main road section 41. The inclined road section 42 has the same flow path cross-sectional area as the main road section 41. Alternatively, the inclined road section 42 may have a different flow path cross-sectional area than the main road section 41.

[0138] Each inclined section 42 of the first inner flow path 35A and the second inner flow path 35B has an opening at a predetermined circumferential position on the outer peripheral side, i.e., the outer peripheral surface, of the shaft body 3. This 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 section 42 is connected to the corresponding first connecting flow path 71 or second connecting flow path 72.

[0139] Figure 12 This is an enlarged sectional view showing the upper side of the rotary joint 1 in this reference example. (e.g.) Figure 12 As shown, the inclined section 42 of the third inner flow path 35C has an opening at the corner of the outer periphery of the shaft body 3, i.e., the shaft body 31 and the small diameter section 33, and this opening 42b is connected to the third connecting flow path 73.

[0140] The other structures of this reference example are the same as those of the first embodiment, so the same reference numerals are used and the description is omitted.

[0141] According to the rotary joint 1 of this reference example, the inclined section 42 of the inner flow path 35 extends from the main flow path 41 to the outer periphery of the shaft 3 at an acute angle upward relative to the axial direction. Therefore, the bend between the main flow path 41 and the inclined section 42 is more gently curved than the L-shaped bend in conventional inner flow paths. As a result, the flow resistance at the bend between the main flow path 41 and the inclined section 42 is reduced, thus effectively reducing the pressure loss of the sealed fluid.

[0142] [other]

[0143] The rotary joint 1 in the above embodiments can be configured vertically or horizontally. Furthermore, besides CMP apparatuses, the rotary joint 1 can be applied to other apparatuses such as sputtering or etching apparatuses. Moreover, the rotary joint 1 is not limited to use in the semiconductor field. Additionally, while the rotary joint 1 forms a flow path 70 via a mechanical seal 6, the flow path 70 can also be formed using other sealing materials (e.g., X-rings or lip seals).

[0144] In the above embodiments, the shaft 3 rotates relative to the housing 2, but the housing 2 may also rotate relative to the fixed shaft 3. In the above embodiments, the sealed fluid flows along the direction from the outer flow path 27 of the housing 2 toward the inner flow path 35 of the shaft 3, but the sealed fluid may also flow in the opposite direction. The inner flow path 35 in the above embodiments may also include three or more branch paths 37.

[0145] The extended branch section 372 of the first embodiment has an inclined section 374 that extends at an acute angle relative to the axial direction from the upper end of the extended section 373, but it may also be formed to extend radially outward from the upper end of the extended section 373 to the outer periphery of the shaft 3.

[0146] In the first embodiment, the inclined branch section 371 and the extended branch section 372 are formed at 180° intervals along the circumference, but this is not a limitation; for example, they may also be formed at acute-angle or 90° intervals along the circumference. Similarly, in the second embodiment, the first branch section 376 and the second branch section 377 are formed at 180° intervals along the circumference, but this is not a limitation; for example, they may also be formed at acute-angle or 90° intervals along the circumference.

[0147] At least a portion of one embodiment of the first and second embodiments can also be arbitrarily combined with at least a portion of the other embodiment. For example, in addition to the inclined branch section 371 and the extended branch section 372, the plurality of branch sections 37 of the first embodiment may also include at least one of the first branch section 376 and the second branch section 377 of the second embodiment. Similarly, in addition to the first branch section 376 and the second branch section 377, the plurality of branch sections 37 of the second embodiment may also include at least one of the inclined branch section 371 and the extended branch section 372 of the first embodiment.

[0148] It should be considered that all the embodiments disclosed herein are merely illustrative and not limiting. The scope of the invention is defined not by the foregoing meaning but by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0149] Explanation of the label

[0150] 1. Rotary joint

[0151] 2. Shell

[0152] 3 shafts

[0153] 27. Outer Flow Path

[0154] 35 Inner Flow Path

[0155] 36 Main Road Section

[0156] 36a Bus terminal

[0157] 37 Branch Road Section

[0158] 70 Connecting Flow Paths

[0159] 371 Inclined branch road section

[0160] 372 Extension of branch road section

[0161] 373, 375 Extended sections

[0162] 374 Inclined section

[0163] 376 First Branch Road Section

[0164] 377 Second Branch Road Section

Claims

1. A rotary joint, comprising: A cylindrical shell with an opening on its inner circumference to form an outer flow path for the sealed fluid to flow through; A shaft, configured to rotate relative to the housing, has an opening on its outer periphery to form an inner flow path for the sealed fluid to flow through; and A connecting flow path that connects the outer flow path to the inner flow path. The inner flow path has: Multiple branch sections, which have openings at different circumferential positions on the outer periphery of the shaft; and The main road section extends axially from one end face of the shaft body toward the other side of the axial direction, and has a confluence end on the other side of the axial direction where a plurality of the branch road sections converge.

2. The rotary joint according to claim 1, wherein, The plurality of said branch sections include inclined branch sections extending from the confluence end of the main section to the outer periphery of the shaft body in a direction at an acute angle relative to the axial direction toward the other side of the axial direction.

3. The rotary joint according to claim 2, wherein, The plurality of branch road sections include extended branch road sections having an extension portion extending along the axial direction from the confluence end of the main road section toward the other side of the axial direction.

4. The rotary joint according to claim 3, wherein, The extended branch section also has an inclined portion extending from the end of the extended portion on the other side of the axial direction to the outer peripheral side of the shaft body, at an acute angle relative to the axial direction toward the other side of the axial direction.

5. The rotary joint according to claim 3 or 4, wherein, The inclined branch section and the extended branch section have openings spaced 180 degrees apart in the circumferential direction on the outer periphery of the shaft.

6. The rotary joint according to any one of claims 1 to 4, wherein, The plurality of branch sections include a first branch section and a second branch section extending radially outward from the confluence end of the main section to the outer periphery of the shaft.

7. The rotary joint according to claim 6, wherein, The first branch section and the second branch section have openings that are spaced 180° apart from each other in the circumferential direction on the outer periphery of the shaft.

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