JP2009275900A - Rotary joint for strongly corrosive liquid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotary joint capable of surely preventing contamination and leakage when streaming a strongly corrosive liquid such as hydrofluoric acid. <P>SOLUTION: One first sealed space 7 and each pair of second and third sealed spaces 8 and 9 are formed between a case body 2 and a rotary shaft body 3 by partitioning with first to third mechanical seals 4, 5 and 6, and passages 15 and 16 formed in both the case body 2 and rotary shaft body 3 are communicated with each other through the first sealed space 7 to form a flow passage 10 for a strong corrosive liquid 1. A first sealed liquid 11 having the pressure lower than that of the strong corrosive liquid 1 is supplied to the second sealed space 8, and a second sealed liquid 12 having the pressure higher than that of the first sealed liquid 11 is supplied to the third sealed space 9. The first mechanical seal 4 is formed into a non-contact type mechanical seal which allows fine leakage of the strong corrosive liquid 1 from the first sealed space 7 to the second sealed space 8, and the second mechanical seal 5 and the third mechanical seal 6 are respectively structured to an end surface contact type mechanical seal. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a rotary for strong corrosive liquid used when a strong corrosive liquid (strong acid, strong alkali) such as hydrofluoric acid flows between relative rotating members in a semiconductor substrate cleaning apparatus (for example, RCA cleaning apparatus). It relates to joints.

  For example, as a rotary joint for flowing a liquid fluid between relative rotation members of a semiconductor substrate cleaning apparatus (between a fixed side member such as an apparatus main body and a rotation side member such as a cleaning table), a case body has been conventionally used. A mechanical comprising a case-side passage formed and a shaft-side passage formed in a rotary shaft body rotatably connected to the case body, with a stationary seal ring provided in the case body and a rotary seal ring provided in the rotary shaft body One end face contact type mechanical system has been proposed in which a seal space sealed by a seal is connected to be connected in a relatively rotatable manner. The seal space is disposed between opposing end faces of a case body and a rotary shaft body. A pair of end-face contact type mechanisms in which a seal is provided with a seal (see, for example, FIG. 1 of Patent Document 1) and a seal space is disposed between opposing circumferential surfaces of the case body and the rotary shaft body. Those to be sealed with Lucille (e.g., see Figure 1 of Patent Document 2) are known.

JP 2001-141149 A JP 11-141771 A

  However, in these conventional rotary joints, as a mechanical seal that seals the seal space that is a relative rotational connection part of the flow path, an end face contact type that makes a stationary sealing ring and a rotational sealing ring make a relative rotational sliding contact is used. Since it is used, there is a possibility that particles such as abrasion powder due to sliding contact between both sealing rings may be mixed into the liquid fluid flowing in the flow path, and contamination countermeasures are not sufficient. In addition, because of the structure of the mechanical seal, it is impossible to completely prevent leakage of the liquid fluid to the outside of the rotary joint. Therefore, if the liquid fluid flowing through the flow path is a strong corrosive liquid such as hydrofluoric acid, If even a little corrosive liquid leaks out of the rotary joint, problems such as corrosion of peripheral devices around the rotary joint and burns of the operator may occur.

  The present invention has been made in view of such points, and in the case of flowing a strong corrosive liquid such as hydrofluoric acid, the rotary joint for strong corrosive liquid that can reliably prevent contamination and leakage. Is intended to provide.

  In order to achieve the above object, the present invention provides a pair of first to third pairs arranged in parallel in the axial direction between opposed circumferential surfaces of a cylindrical case body and a rotary shaft body rotatably connected thereto. By the mechanical seal, five seal spaces comprising a first seal space, a pair of third seal spaces located on both sides of the first seal space, and a pair of second seal spaces located between the first seal space and each third seal space are provided. A series of flow paths for flowing strongly corrosive liquid is formed by continuously connecting the case side passage formed in the case body and the shaft side passage formed in the rotating shaft body through the first seal space. The first sealing liquid having a pressure lower than that of the strong corrosive liquid is supplied to the second seal space and the second sealing liquid having a pressure higher than that of the first sealing liquid is supplied to the third seal space. A first mechanical seal that seals between two seal spaces, From the first seal space of the highly corrosive liquid to the second seal space, the sealed end face, which is the opposite end face between the stationary seal ring provided on the casing body and the rotary seal ring provided on the rotary shaft body, is maintained in a non-contact state. A non-contact type mechanical seal that allows slight leakage of the second seal and the third seal space that seals between the second seal space and the third seal space in cooperation with the second mechanical seal. Each of the third mechanical seals is configured as an end-face contact type mechanical seal in which a sealing end surface, which is an opposing end surface of a stationary sealing ring provided on the case body and a rotary sealing ring provided on the rotary shaft body, is in relative rotational sliding contact. We propose a rotary joint for highly corrosive liquids.

  According to the present invention, the first seal space constituting the relative rotation portion of the flow path is sealed by the first mechanical seal that is a non-contact type mechanical seal, and is partitioned from the first seal space by the first mechanical seal. Since the second seal space is held at a lower pressure than the first seal space, the strong corrosive liquid always leaks from between the sealing end faces of the first mechanical seal to the second seal space. Even if particles such as abrasion powder are generated between the sealed end faces, they do not enter the first seal space due to the leakage liquid, and this is the occurrence of contamination in the strong corrosive liquid flowing in the flow path. It is surely prevented. Further, the strong corrosive liquid leaking into the second seal space is diluted with the second seal liquid, and the second seal space is formed between the first seal space having a higher pressure and the third seal spaces on both sides thereof. The strong corrosive liquid leaked from the first seal space does not leak out of the second seal space, so that the strong corrosive liquid does not leak out of the rotary joint without being diluted. Occurrence of the above-described problem due to liquid leakage is reliably prevented. Therefore, the rotary joint of the present invention can flow the strong corrosive liquid between the relative rotating members safely and surely without causing the contamination and leakage. Strict contamination countermeasures and leakage prevention measures This is a very practical value that can be suitably used for a rotating device such as a semiconductor substrate cleaning apparatus that needs to be protected.

  FIG. 1 is a longitudinal sectional front view showing an example of a rotary joint according to the present invention, and FIG. 2 is an enlarged detailed view showing a main part of FIG. 3 to 5 are cross-sectional bottom views of essential parts taken along line III-III in FIG. 2, respectively, illustrating dynamic pressure generating grooves. In the following description, “upper and lower” refers to the upper and lower sides in FIGS.

  The rotary joint shown in FIG. 1 is for causing the strong corrosive liquid 1 to flow between a stationary member and a rotary member in a semiconductor cleaning apparatus or the like that uses a strong corrosive liquid such as hydrofluoric acid as a wafer cleaning liquid. A pair of first mechanical seals 4 and 4 arranged in parallel in the axial direction (vertical direction) between opposed circumferential surfaces of a cylindrical case body 2 and a rotary shaft body 3 rotatably connected thereto. The second mechanical seals 5, 5 and the third mechanical seals 6, 6 make the first seal space 7, the pair of third seal spaces 9, 9 and the first seal space 7 located on both sides thereof, and the respective third seal spaces. A five seal space consisting of a pair of second seal spaces 8 and 8 located between the two bodies 2 and 3 is defined by a series of flow passages 10 communicating with each other via the first seal space 7. Contamination of strong corrosive liquid 1 It is devised so that it can flow well without being generated, and liquid leakage from the flow path 10 is surely prevented by supplying the sealing liquids 11 and 12 of different pressures to the second and third seal spaces 8 and 9. It has been devised.

  The case body 2 is a cylindrical structure whose inner peripheral surface has a circular cross section, and is attached to a stationary member such as a semiconductor cleaning device with an axis extending in the vertical direction. On the inner peripheral surface of the case body 2, a first annular support wall 2a and a pair of second annular support walls 2b and 2b located on both upper and lower sides thereof are formed to project. The case body 2 has a structure that is divided into a plurality of parts in the axial direction, and the plurality of divided parts are interconnected with bolts or the like (not shown), thereby forming a cylindrical integrated structure. Is assembled.

  As shown in FIG. 1, the rotary shaft body 3 includes a cylindrical shaft main body 3a attached to a rotary side member such as a semiconductor cleaning device in a state where the axis extends in the vertical direction, and a predetermined interval in the axial direction between the shaft main body 3a. It is composed of four cylindrical holding cylinders 3b that are fitted and fixed in parallel and spaced apart from each other, and a bearing receiver 3c that is fixed to one end (upper end) of the shaft body 3a. A pair of upper and lower bearings 13, 13 disposed on both upper and lower sides of 2 b are concentrically supported and connected to the inner peripheral portion of the case body 2 so as to be rotatable and non-movable in the axial direction. The holding cylinder 3b located at the uppermost end constitutes a peripheral wall of the bottomed cylindrical bearing receiver 3c. The upper bearing 13 is loaded between the opposed peripheral surfaces of the bearing receiver 3c and the upper end of the case body 2, and the lower bearing 13 includes a lower end side portion of the shaft body 3a and a lower end portion of the case body 2. It is loaded between the opposed peripheral surfaces.

  An annular space formed between the opposing peripheral surfaces of the two bodies 2 and 3 (between the inner peripheral surface of the case body 2 and the outer peripheral surface of the rotating shaft body 3) is parallel to the axial direction as shown in FIG. 5 by a pair of mechanical seals (a pair of first mechanical seals 4 and 4, a pair of second mechanical seals 5 and 5 disposed on both upper and lower sides thereof, and a pair of third mechanical seals 6 and 6 disposed on both upper and lower sides thereof). One seal space (a first seal space 7, a pair of third seal spaces 9, 9 positioned on both upper and lower sides thereof, and a pair of second seal spaces positioned between the first seal space 7 and each third seal space 9) 8 and 8) and a pair of bearing storage spaces (spaces in which the respective bearings 13 are arranged) 14 and 14 positioned on both upper and lower sides of these seal space groups. That is, the space between the first seal space 7 and each second seal space 8 is partitioned and sealed by the first mechanical seal 4, and the space between each second seal space 8 and the third seal space 9 adjacent thereto is between. A partition seal is provided by the second mechanical seal 5, and a partition seal is provided by the third mechanical seal 6 between each third seal space 9 and the bearing storage space 14 adjacent thereto.

  Thus, as shown in FIG. 1, the flow path 10 is formed in the case body 2 and communicated with the first seal space 7 formed in the case body 2 and sealed by the pair of first mechanical seals 4, 4. The case-side passage 15 and the shaft-side passage 16 that is formed in the rotary shaft body 3 and communicates with the first seal space 7.

  As shown in FIG. 1, the case-side passage 15 penetrates the first annular support wall 2 a in the radial direction, opens one end portion thereof into the first seal space 7, and has the other end portion as an outer peripheral portion of the case body 2. In FIG. 5, the fixed side member is connected to a fixed side flow path. As shown in FIG. 1, the shaft-side passage 16 passes through the central portion of the shaft main body 3a, and opens one end of the shaft main body 3a through the holding cylinder 3b to the first seal space 7 and the other end as the shaft. An end portion (lower end portion) of the main body 3a is connected to a rotation-side channel formed in the rotation-side member.

  As shown in FIG. 1, each first mechanical seal 4 that seals the first seal space 7 includes a stationary sealing ring 17 provided on the case body 2, a first rotating sealing ring 18 provided on the rotating shaft body 3, and a stationary sealing ring. And a spring 19 that presses and urges 17 against the rotary sealing ring 18, and the sealing end face 20 is formed by a dynamic pressure generating groove 22 formed on one of the sealing end faces 20, 21 that are opposite end faces of the sealing rings 17, 18. 21 is a non-contact type mechanical seal of a dynamic pressure type configured to generate a dynamic pressure by the strong corrosive liquid 1 in the first seal space 7 between 21. That is, each first mechanical seal 4 is connected to the sealed end face 21 and the first stationary seal ring 17 by a dynamic pressure generating groove 22 formed in the sealed end face (rotary side sealed end face) 21 of the rotary seal ring 18 as shown in FIG. By generating a dynamic pressure between the sealing end surface (stationary side sealing end surface) 20 and the sealing end surface 20, the first sealing end surface 20, 21 is maintained in a non-contact state in which the lubricating film of the strong corrosive liquid 1 is interposed. It is configured to seal between the seal space 7 and the second seal space 8 adjacent to the seal space 7, and the strong corrosive liquid 1 in the first seal space 7 passes from between the sealed end surfaces 20 and 21 to the second seal space. It is allowed to leak to 8 within a minute predetermined range. In addition, as shown in FIG. 1, both the first mechanical seals 4 and 4 are double-arranged in the axial direction so that both stationary sealing rings 17 and 17 are positioned between the rotary sealing rings 18 and 18. It is in the form of a seal.

  As shown in FIGS. 1 and 2, each stationary sealing ring 17 is fitted and held on the inner peripheral surface of the first annular support wall 2a via an O-ring 23 so as to be movable in the axial direction. Is a concentric smooth surface orthogonal to the axis (the axis of rotation of both bodies 2 and 3, hereinafter simply referred to as “axis”). Both stationary sealing rings 17 and 17 are held by the first annular support wall 2a with their rear surfaces (axial end surfaces opposite to the sealing end surfaces 20 and 20) facing each other. The recess 24 formed in the above is engaged with a common drive pin 25 that is axially supported by the first annular support wall 2a, thereby allowing relative rotation with respect to the case body 2 while allowing movement in the axial direction within a predetermined range. Is blocked. The insertion location of the drive pin 25 in the first annular support wall 2 a is set at a position where it does not interfere with the case side passage 15.

  As shown in FIG. 1, each rotary seal ring 18 is inserted into the shaft body 3 a while being clamped by the adjacent holding cylinders 3 b, 3 b, so that each rotary seal ring 18 is arranged at a position facing each stationary seal ring 17. It is fixed to the outer peripheral surface of the main body 3a. In addition, between each rotation sealing ring 18 and the shaft main body 3a, it seals with the O-ring 26 with which it loaded between the shaft main body 3a and each holding cylinder 3b.

  The end face of each rotary seal ring 18 (excluding the inner diameter side portion with which the holding cylinder 3b is abutted) is configured as a seal end face 21 that forms a concentric smooth surface perpendicular to the axis, as with the stationary-side seal end face 20. Has been. The outer diameter of each rotation-side sealing end face 21 is set to be the same as or slightly larger than the outer diameter of the stationary-side sealing end face 20, and the inner diameter (corresponding to the outer diameter of the holding cylinder 3 b) is the configuration of the first mechanical seal 4. In addition, the holding cylinder 3b is inevitably smaller than the inner diameter of the stationary sealing end face 20 (the inner diameter of the stationary sealing ring 17 is such that the inner peripheral portion of the sealing ring 17 does not interfere with the outer peripheral portion of the holding cylinder 3b. Is set to be larger than the outer diameter). Therefore, the radial direction of the annular region (the annular region where both sealed end surfaces 20 and 21 are superposed, hereinafter referred to as “seal region”) W in which the lubricating film of the strong corrosive liquid 1 is formed in each first mechanical seal 4 The width (seal surface width) corresponds to the radial width of the stationary-side sealed end surface 20.

  The spring 19 is for pressing and urging the stationary seal ring 17 to the rotary seal ring 18 in each first mechanical seal 4, and is formed by arranging a plurality of coil springs (only one is shown) in the circumferential direction. However, in this example, as shown in FIG. 1, both first stationary sealings held by the annular support wall 2a in a state where the coil springs are inserted and held in the through holes 27 formed in the first annular support wall 2a. By mounting between the rings 17 and 17, the first mechanical seals 4 and 4 are devised to function as a common urging means. Each through hole 27 is formed at a position where it does not interfere with the case side passage 15.

  As shown in FIG. 3, a plurality of arc-shaped dynamic pressure generating grooves 22 are formed in each rotary-side sealed end face 21 so as to be arranged in a helical shape in the circumferential direction. Each dynamic pressure generating groove 22 is a shallow groove that extends in an arc shape from the high-pressure fluid region side (inner diameter side) to the low-pressure fluid region side (outer diameter side) in the relative rotation direction (A direction) of the rotation-side sealing end surface 21. , Except for the end portion 22a on the high-pressure fluid region side, it is formed so as to be located in the seal region W between the sealed end surfaces 20, 21. The end portion 22a on the high pressure region side protrudes from the seal region W to the inner diameter side of the rotary side sealing end surface 21, and is opened to the first seal space 7 which is a high pressure fluid region. In addition, the dynamic pressure generating grooves 22 and 22 of both the rotation-side sealed end faces 21 and 21 are symmetrical with respect to a plane orthogonal to the axis. Thus, in each first mechanical seal 4, the sealed end surface (rotation-side sealed end surface 21) on which the dynamic pressure generating groove 22 is formed is a sealed end surface (stationary-side sealed end surface 20) on which the dynamic pressure generating groove 22 is not formed. ), The strongly corrosive liquid 1 in the first seal space 7 is introduced from the end 22a that opens outside the seal region W, and the seal region between the sealed end surfaces 20 and 21 is rotated. In W, dynamic pressure is generated by the strong corrosive liquid 1. The dynamic pressure is balanced with the back pressure by the strong corrosive liquid 1 acting on the first stationary seal ring 17 and the urging force by the spring 19, so that the space between the sealed end surfaces 20 and 21 is caused by the strong corrosive liquid 1. The fluid film is held in a non-contact state. Therefore, in the flow path 4 in which the case side passage 15 and the shaft side passage 16 are connected to each other through the first seal space 7 so as to be relatively rotatable, the strong corrosive liquid 1 flows between the sealed end surfaces 20 and 21. The fluid flows while causing a predetermined small amount of leakage to the outside of the one seal space 7 (that is, to the second seal space 8).

  The shape of the dynamic pressure generating groove 22 is the dynamic pressure employed in a well-known dynamic pressure type non-contact type mechanical seal (see, for example, JP-A-7-260009 and JP-A-6-174107). Similar to the generation groove, sealing conditions (relative rotation speed of the sealing end surfaces 20 and 21 (rotation speed of the rotating shaft 3), pressure of the strong corrosive liquid 1 in the first seal space 7 and between the sealing end surfaces 20 and 21. Can be set as appropriate according to the allowable leakage amount from the For example, the dynamic pressure generating groove 22 may have a shape illustrated in FIG. 4 or 5 in addition to the shape illustrated in FIG. That is, in the one shown in FIG. 4, a plurality of dynamic pressure generating grooves 22 extending linearly in the radial direction of the rotation-side sealing end surface 21 are arranged in a radial pattern. Similar to the dynamic pressure generation groove 22 shown in FIG. 3, each dynamic pressure generation groove 22 is positioned in the seal region W between the sealed end surfaces 20 and 21 except for the end portion 22 a on the high pressure fluid region side (inner diameter side). The end portion 22 a on the high pressure region side protrudes from the seal region W and is opened to the first seal space 7. When the dynamic pressure generating groove 22 shown in FIG. 4 is employed, dynamic pressure can be generated both when the rotation-side sealing end surface 21 rotates forward in the A direction and when it rotates in the opposite direction to the A direction. Even when the body 3 is driven forward and backward, it can be used as an appropriate rotary joint. In this way, in the rotary joint used for the purpose of driving the rotating shaft 3 forward and backward, the dynamic pressure generating groove 22 can be shaped as shown in FIG. That is, FIG. 5 is the same as the dynamic pressure generating groove disclosed in Japanese Patent Laid-Open No. 7-260009, and the first and second dynamic pressure grooves are symmetrical with respect to the diameter line of the rotation-side sealing end surface 21. When the groups 22A and 22B are alternately arranged in parallel in the circumferential direction, as in the case shown in FIG. 4, when the rotation-side sealing end face 21 is rotated forward in the A direction and when reversed in the opposite direction of A. In either case, dynamic pressure can be generated. The first dynamic pressure groove group 22A has an L-shaped motion composed of a straight line portion extending from the high pressure side end portion 22a outside the seal region W in the radial direction of the rotary side sealing end surface 21 and an arc portion extending from the end portion in the A direction. The second dynamic pressure groove group 22B is composed of a group of pressure generating grooves 22, and the second dynamic pressure groove group 22B extends from the high pressure side end portion 22a outside the seal region W in the radial direction of the rotary side sealing end surface 21 and from the end portion to the opposite A. It consists of a group of L-shaped dynamic pressure generating grooves 22 composed of arc portions extending in the direction.

  As shown in FIG. 1, the second mechanical seal 5 that seals each second seal space 8 includes a stationary sealing ring 28 provided on the case body 2, a rotary sealing ring 29 and a stationary sealing ring 28 provided on the rotary shaft body 3. A relative rotation of the sealing end faces 31 and 32, which are opposing end faces of the sealing rings 28 and 29, is provided with a spring (consisting of a plurality of coil springs similar to the spring 19) 30 that presses and urges the rotating sealing ring 29. It is an end surface contact type mechanical seal configured to shield and seal the second seal space 8 and the third seal space 9 by a sliding contact action. Further, as shown in FIG. 1, the third mechanical seal 6 that seals each third seal space 9 is provided in the stationary seal ring 33 provided in the case body 2 and the rotary shaft body 3, as in the second mechanical seal 5. The rotary seal ring 34 and the spring 35 (which comprises a plurality of coil springs as in the case of the spring 19) 35 for pressing and urging the stationary seal ring 33 to the rotary seal ring 34 are provided. It is an end face contact type mechanical seal configured to shield and seal the third seal space 9 and the bearing storage space 14 by the relative rotational sliding contact action of the sealing end faces 36 and 37 as opposed end faces.

  As shown in FIG. 1, the stationary seal rings 28 and 33 of the mechanical seals 5 and 6 are fitted and held on the inner peripheral surface of the second annular support wall 2b so as to be movable in the axial direction via O-rings 38 and 39. The recesses 40, 41 formed on the outer peripheral portions of the stationary sealing rings 28, 33 are engaged with the drive pins 42, 43 fixed to the second annular support wall 2b, so that the axial movement within a predetermined range is achieved. Relative rotation with respect to the case body 2 is prevented in an allowable state. In this example, each end portion of the drive pin 25 that is penetrated and supported by the first annular support wall 2a is extended, and this extended portion is also used as a drive pin 42 that prevents relative rotation of the stationary seal ring 28. ing.

  As shown in FIG. 1, each rotary seal ring 29, 34 is clamped between adjacent holding cylinders 3b, 3b or in a pressed condition between the holding cylinder 3b and a step formed on the shaft body 3a. By being fitted into the shaft main body 3a, the shaft main body 3a is fixed to the outer peripheral surface of the shaft main body 3a in a position facing the stationary sealing rings 28 and 33. The rotary seal rings 29, 34 and the shaft main body 3a are sealed by an O-ring 26 loaded between the shaft main body 3a and each holding cylinder 3b.

  The end surfaces of the rotary sealing rings 29 and 34 (except for the inner diameter side portion where the holding cylinder 3b is abutted) are aligned with the axis (the rotational axis of the two bodies 2 and 3) in the same manner as the stationary sealing end surfaces 28 and 34. Although the sealing end surfaces 32 and 37 which make the orthogonal concentric circular smooth surface are comprised, the rotation sealing ring 29 of each 2nd mechanical seal 5 makes the both end surfaces of the said rotation sealing ring 18 the sealing end surfaces 21 and 32. As shown in FIG. Thus, the rotary seal ring 18 is also used. By using the rotary seal rings 18 and 29 together, the number of members is reduced and the rotary joint is shortened (length in the axial direction is shortened).

  Thus, the first sealing liquid 11 is circulated and supplied to both the second seal chambers 8 and 8 through the supply and discharge liquid passages 44 and 45 formed in the case body 2. That is, in this example, since the second seal chambers 8 and 8 are communicated with each other through the spring insertion hole 27, the supply to communicate with the case body 2 to one of the second seal chambers 8 as shown in FIG. A liquid passage 44 is formed and a drainage passage 45 communicating with the other second seal chamber 8 is formed so that the first sealing liquid 11 is supplied from the liquid supply passage 44 to both the second seal chambers 8 and 8. It has become. The first sealing liquid 11 supplied to both the second seal chambers 8 and 8 is discharged from the drainage path 45 to the outside of the rotary joint, and is circulated to the liquid supply path 44 through an appropriate circulation path. Yes. As the first sealing liquid 11, room temperature water or cooling water having a pressure lower than that of the strong corrosive liquid 1 flowing in the flow path 10 is used, and the second seal chamber 8 is held at a lower pressure than the first seal chamber 7. The pressure of the first sealing liquid 11 is set so that, for example, the second seal chamber 8 is about 0.1 MPa lower than the first seal chamber 7.

  Further, the second sealing liquid 12 is circulated and supplied to both the third seal chambers 9 and 9 through supply and discharge liquid passages 46 and 47 formed in the case body 2. That is, as shown in FIG. 1, a pair of liquid supply passages 46 and 46 and drainage passages 47 and 47 communicating with each second seal chamber 8 are formed in the case body 2, and the second sealing liquid 12 is supplied to each liquid supply. The third seal chamber 9 is supplied from the passage 46. The second sealing liquid 12 supplied to each third seal chamber 9 is discharged out of the rotary joint from each drainage passage 47 and circulated to each liquid supply passage 46 through an appropriate circulation passage. Yes. As the second sealing liquid 12, normal temperature water or cooling water having a pressure higher than that of the first sealing liquid 11 is used, and both the third seal chambers 9 and 9 are held at a higher pressure than the second seal chambers 8 and 8. The pressure of the second sealing liquid 12 is set so that, for example, the third seal chamber 9 is about 0.1 MPa higher than the second seal chamber 8. In addition, although the circulation path between one supply / drain liquid path 46 and 47 and the circulation path between the other supply / drain liquid path 46, 47 can be used together, both the third seal chambers 9, It is preferable to keep 9 at the same pressure. The case body 2 is formed with drain passages 48 and 48 that open to a portion (drain space) between the bearing 13 and the third rotary seal ring 34 in each bearing storage space 14.

  By the way, members (both bodies 2 and 3 and seal rings 17 and 18 etc.) in contact with the strong corrosive liquid 1 flowing through the flow path 10 or contact surfaces of the strong corrosive liquid 1 (inner circumferences of the passages 15 and 16). As the constituent material of the surface and the sealing end surfaces 20, 21, etc., materials having high corrosion resistance (chemical resistance) are used. In particular, the strong corrosive liquid 1 should be used for semiconductor cleaning and the like to avoid metal contamination. In the case of the ones used in the above, non-metallic materials having excellent corrosion resistance (for example, corrosion-resistant plastics such as PTFE, PFE, and PEEK, corrosion-resistant rubbers such as fluorine rubber, and ceramics such as SiC) are used. . In addition, if necessary, the member that may be contacted by the strong corrosive liquid 1 leaked from the first mechanical seal 4 or its contact surface may be made of the above-described material having high corrosion resistance. preferable. In addition, when it is difficult to construct the entire member with a corrosion resistant material in terms of strength and the like, the corrosion resistant material is applied to the surface of the member (contact surface of the strong corrosive liquid 1). Keep it coated. In this example, all the sealing rings 17, 18, 28, 29, 36, and 37 are made of SiC, and members that are difficult to make of corrosion-resistant plastic or rubber in terms of strength or the like are made of steel or the like. The surface (contact surface of the strong corrosive liquid 1) is coated with a corrosion-resistant plastic.

  In the rotary joint configured as described above, the first mechanical seal 4 that seals the first seal space 7 is a non-contact type mechanical seal. The strong corrosive liquid 1 can be favorably flowed between the relative rotating members 2 and 3 without causing seizure. The first mechanical seal 4 allows the strong corrosive liquid 1 flowing in the first seal space 7 to leak from between the sealed end surfaces 20 and 21, and the first mechanical seal 4 allows the first seal space 7 to be leaked. Since the pressure in the second seal spaces 8 and 8 partitioned is maintained at a lower pressure than the first seal space 7, the strong corrosive liquid 1 in the first seal space 7 is sealed from the sealed end surfaces 20 and 21 to the second seal. A small amount of leakage always continues to the spaces 8 and 8. Therefore, even if particles such as abrasion powder are generated between the sealing end surfaces 20 and 21, these particles are discharged together with the leaked liquid into the second seal space 8 and enter the first seal space 7. In other words, mixing of particles into the strongly corrosive liquid 1 flowing through the flow path 10 is reliably avoided.

  Further, the strong corrosive liquid 1 leaked from the first seal space 7 to the second seal spaces 8, 8 is diluted by the first sealing liquid (water) 11 circulated and supplied to the second seal spaces 8, 8. The second mechanical seal 5 that partitions each second seal space 8 and the third seal space 9 is an end surface contact type mechanical seal that does not allow leakage, and each third seal space 9 includes the second seal space 8. Since the higher-pressure second sealing liquid (water) 12 is circulated and supplied, the strong corrosive liquid 1 leaking into the second seal spaces 8 and 8 should leak into the third seal spaces 9 and 9 by any chance. There is nothing to do. Therefore, the presence of the second and third seal spaces 8 and 9 prevents the strong corrosive liquid 1 from leaking out of the rotary joint as it is from the first seal space 7, and the problem due to leakage of the strong corrosive liquid 1 ( This does not occur at all in the case of problems such as corrosion of rotary joint peripheral equipment and burns of workers. In addition, in the circulation path of the first sealing liquid 11, if necessary, the strong corrosive liquid 1 mixed in the first sealing liquid 11 discharged from the drainage path 45 is further diluted or removed (neutralized). Etc.) is disposed.

  Each of the second and third mechanical seals 5 and 6 is an end surface contact type mechanical seal. However, the sealed end surfaces 31, 32, 36, and 37, which are the relative rotational sliding contact portions thereof, are lubricated with the second sealing liquid 12 ( Therefore, the relative rotational sliding contact portion will not be abnormally worn or seized. Then, along with lubrication by the second sealing liquid 12, there is a possibility that liquid leakage may occur between the sealed end faces 31, 32. In such a case, a high pressure from the sealed end faces 31, 32 of the second mechanical seal 5. Since liquid leakage (leakage of the second sealing liquid 12) occurs from the seal chamber 9 to the low-pressure second seal chamber 8, the strong corrosive liquid 1 leaking into the second seal chamber 8 is in the third seal chamber 9. The problem of leakage of the strong corrosive liquid 1 does not occur. Further, there is a possibility that liquid leakage may occur from the sealing end faces 36 and 37 of the third mechanical seal 6 along with the lubrication by the second sealing liquid 12, and the second sealing liquid 12 flows from the third seal chamber 9 in the atmospheric pressure region. Even in such a case, the third seal chamber 9 may leak into the third seal chamber 9 from the first seal chamber 7 to the second seal chamber 8 as described above (strongly corrosive liquid). Since 1) does not enter, only the second sealing liquid (water) 12 that does not contain the strong corrosive liquid 1 leaks into the bearing storage space 14. Therefore, even when each of the second and third mechanical seals 5 and 6 is an end-face contact type mechanical seal and liquid leakage due to lubrication occurs from the relative rotational sliding contact portion, there is a problem due to leakage of the strong corrosive liquid 1. Does not occur at all. The second sealing liquid 12 leaking into each bearing storage space 14 is discharged from the drain passage 48, but the draining liquid 12 does not contain the strong corrosive liquid 1 as described above.

  By the way, even when the rotation of the rotary shaft 3 becomes low speed and a dynamic pressure sufficient to hold the sealed end surfaces 20 and 21 in a non-contact state cannot be obtained, the dynamic pressure generating groove 22 is also obtained. Troubles such as abnormal wear of the sealing end surfaces 20 and 21 due to the presence of can be avoided. For example, when the rotary joint 3 is started or stopped, the rotary shaft 3 rotates at a low speed so that sufficient dynamic pressure is not generated to keep the sealed end surfaces 20 and 21 in a non-contact state. Although there is a possibility of being worn by contact, such a fear can be avoided by starting or stopping the operation in a state where the first seal space 7 is filled with the strong corrosive liquid 1. That is, when the first seal space 7 is filled with the strong corrosive liquid 1 in the completely stopped state of the rotating shaft 3 before the operation is started, the end 22a of the dynamic pressure generating groove 22 is opened to the first seal space 7. Therefore, the strongly corrosive liquid 1 enters and stays in the dynamic pressure generating groove 22 from the end 22a. Therefore, when the operation is started from this state, the dynamic pressure generating groove 22 stays in the seal region W even when the rotating shaft 3 is not rotating at a speed sufficient to generate the dynamic pressure. Since lubrication with the highly corrosive liquid 1 (liquid lubrication) is performed, the sealed end faces 20 and 21 do not come into dry contact until reaching a speed sufficient to generate dynamic pressure, and wear powder No generation or seizure occurs. The same applies to the case where the rotational speed of the rotary shaft 3 drops below a speed sufficient to generate dynamic pressure when the operation is stopped. Thus, even when the rotary shaft 3 does not rotate at a speed sufficient to generate dynamic pressure, the sealed end surfaces 20 and 21 are lubricated by the strong corrosive liquid 1, so that the operation is started or the operation is started. Contamination can be avoided even when the rotating shaft 3 rotates at a low speed as in the stop. Therefore, contamination is generated in the flow path 4 even when the operation is started and stopped frequently or when the rotating shaft 3 is unexpectedly reduced in speed and stopped. There is no. Of course, even if particles are generated on the sealed end surfaces 20 and 21, the first seal chamber 7 is at a higher pressure than the second seal chamber 8, so that the strong corrosion resistance in the first seal chamber 7 as described above. The liquid 1 is not contaminated, and contamination does not occur.

It is a vertical front view which shows an example of the rotary joint which concerns on this invention. FIG. 2 is an enlarged detailed view showing a main part of FIG. 1. FIG. 3 is a transverse bottom view (a cross section is taken along line III-III in FIG. 2) of a main part showing an example of a dynamic pressure generating groove. It is a cross-sectional bottom view equivalent to FIG. 3 which shows the modification of a dynamic pressure generating groove. It is a cross-sectional bottom view equivalent to FIG. 3 which shows the other modification of a dynamic pressure generating groove.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Strong corrosive liquid 2 Case body 3 Rotating shaft body 4 1st mechanical seal 5 2nd mechanical seal 6 3rd mechanical seal 7 1st seal space 8 2nd seal space 9 3rd seal space 10 Flow path 11 1st sealing liquid 12 Second Seal 14 Bearing Housing Space 15 Case Side Passage 16 Shaft Side Passage 17 Static Seal Ring 18 Rotating Seal Ring 19 Spring 20 Sealing End Face of Static Seal Ring 21 Sealing End Face of Rotary Seal Ring 22 Dynamic Pressure Generating Groove 28 Static Seal Ring 29 Rotating sealing ring 30 Spring 31 Sealing end face of stationary sealing ring 32 Sealing end face of rotating sealing ring 33 Stationary sealing ring 34 Rotating sealing ring 35 Spring 36 Sealing end face of stationary sealing ring 37 Sealing end face of rotating sealing ring

Claims (1)

A pair of first to third mechanical seals arranged in parallel in the axial direction between the opposed peripheral surfaces of the cylindrical case body and the rotary shaft body rotatably connected thereto, the first seal space, on both sides thereof Partitioning and forming five seal spaces including a pair of third seal spaces and a pair of second seal spaces located between the first seal space and each third seal space;
By connecting the case side passage formed in the case body and the shaft side passage formed in the rotary shaft body through the first seal space, a series of flow paths for flowing the strong corrosive liquid is formed,
Supplying a second sealing liquid having a pressure lower than that of the strong corrosive liquid to the second sealing space, and supplying a second sealing liquid having a pressure higher than that of the first sealing liquid to the third sealing space;
The first mechanical seal that seals between the first seal space and the second seal space is not in contact with the sealing end surface that is the opposing end surface of the stationary sealing ring provided on the case body and the rotary sealing ring provided on the rotating shaft body. A non-contact type mechanical seal that is kept in a state and allows a slight leakage of strong corrosive liquid from the first seal space to the second seal space,
A stationary body provided with a second mechanical seal for sealing between the second seal space and the third seal space and a third mechanical seal for sealing the third seal space in cooperation with the second mechanical seal, respectively, in the case body A rotary joint for a strong corrosive liquid, characterized in that the sealing end surface, which is the opposite end surface between the sealing ring and the rotating sealing ring provided on the rotating shaft body, is configured as an end surface contact type mechanical seal in which the sealing member makes a relative rotational sliding contact.

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