JP2010101361A - Rotary joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotary joint capable of completely eliminating the foreign matters generated due to the wear of the seal surfaces from a supplied fluid by a simple configuration. <P>SOLUTION: This rotary joint 1 includes a cylindrical shaft part 7 coaxially extending from a rotor 4 to a floating seat 8 side. A cylindrical gap S closed at the position apart from a surface seal part 10 to a fixed part side is formed between the outer peripheral surface of the cylindrical shaft part 7 and the inner peripheral surface of a fixed flow passage 8f while the surface seal part 10 is included within a gap forming range. The rotary joint further includes a flow suppressing means for suppressing the flow of the fluid in the cylindrical gap S by generating a pressure loss in the cylindrical gap S. The balance ratio of the surface seal part 10 is set so that the fluid leaks from the surface seal part to the outside at a predetermined leak rate. Consequently, the foreign matters generated at the surface seal part 10 due to the wear of the seal surfaces can be discharged together with the fluid leaking from the surface seal part 10. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a rotary joint used for feeding fluid to a rotating part.

  In a fluid feeding mechanism that feeds fluid to a rotating part that is in a rotating state during operation, a rotary joint is used as a fluid coupling that connects a fixed fluid feeding pipe to a flow path of the rotating part. The rotary joint is a seal of a rotary seal mounted on each facing end face, with a rotating shaft coupled to the rotating part and a fixed shaft connected to the fluid supply pipe arranged coaxially and facing each other in the axial direction. A mechanical seal mechanism that prevents fluid leakage by bringing the surfaces into close contact with each other is employed (see Patent Document 1).

  In the mechanical seal, the seal surfaces are pressed against each other and slide, so that fine foreign matter may be generated due to wear of the seal surface. If such a fluid containing foreign matter is supplied as it is to the device to which the fluid is supplied, problems such as biting of foreign matter into the movable part of the device to be supplied and contamination of the workpiece may occur. In particular, when it is incorporated in an apparatus used in the food processing field, semiconductor manufacturing field, etc., a high cleanliness is required for the fluid to be fed, and therefore countermeasures against foreign matters mixed in the fluid are required.

As such foreign matter countermeasures, those related to mechanical seals used for pumps and the like have been known (see Patent Document 2). Here, a slit-shaped groove is formed on the sealing surface of a sliding ring made of ceramics such as alumina used as a sealing member, and foreign matters generated by sliding are collected and discharged by the groove. .
JP 2004-205037 A JP 2000-161501 A

  However, the prior art disclosed in Patent Document 2 has the following problems. First, the foreign matter discharge mechanism in the mechanical seal shown in the prior art example has a complicated structure, so that it is difficult to apply to a fluid device with a simple structure such as a rotary joint, and to a ceramic used for a sliding ring. Therefore, it is difficult to avoid an increase in manufacturing cost. Furthermore, since the foreign matter once collected may return to the flow path again, there is a functional difficulty that it is difficult to say that a complete foreign matter removing function is ensured. As described above, the conventional rotary joint has a problem that it is difficult to completely remove foreign matters generated due to wear of the seal surface from the fluid supplied with a simple configuration.

  This invention is made in view of such a subject, and it aims at providing the rotary joint which can exclude completely the foreign material which generate | occur | produces by abrasion of a seal surface from the fluid supplied by simple structure. .

  The rotary joint of the present invention is formed by coaxially arranging a rotating portion provided with an axial rotation flow path and attached to the rotation shaft and a fixed portion provided with an axial fixed flow path and attached to a casing member. A rotary joint that feeds fluid supplied from a supply source to a rotating flow path of the rotating unit that rotates about an axis through the fixed channel, and is provided at the rotating unit with a first end face on a side end surface A rotating seal portion having a sealing surface, and a fixed shaft that fits in a state in which the fixed passage is formed so as to penetrate in the axial direction and is allowed to move in the axial direction in a fitting hole provided in the casing member And a fixed seal portion having a second seal surface with the fixed flow path opened on one side end surface thereof, and supplying the fluid from the fluid supply source into the fitting hole to thereby fix the fixed shaft Apply fluid pressure to the side end face of the other side The surface formed by bringing the first seal surface and the second seal surface into close contact with each other by pressing the fixed seal portion against the rotary seal portion with a surface pressure corresponding to the fluid pressure. A cylindrical shaft portion that is provided coaxially extending from the rotary seal portion to the fixed seal portion side, communicates with the rotary flow path, and has a tip opening communicated with the fixed flow path; and the cylindrical shaft The surface seal portion is formed between the outer peripheral surface of the portion and the inner peripheral surface of the fixed flow path so as to include a gap forming range in the axial direction, and communicates with the fixed flow path from the surface seal portion to the rotating portion side. A cylindrical gap closed at a separated position, and a flow suppression means for suppressing the flow of the fluid in the cylindrical gap by generating a pressure loss in the cylindrical gap, and the surface pressure with respect to the fluid pressure is reduced. The surface defined by the ratio Balance ratio Le portion is set to 0.6 or less, wherein the fluid is leaking to the outside by a predetermined leakage amount corresponding to the balance ratio from the face seal portion.

  Further, the rotary joint of the present invention is formed by coaxially arranging a rotating part provided with an axial rotational flow path and attached to a rotary shaft and a fixed part provided with an axial fixed flow path and attached to a casing member. A rotary joint that feeds fluid supplied from a fluid supply source to a rotating flow path of the rotating unit that rotates about an axis through the fixed channel, and is provided on the rotating unit and rotates on a side end surface. Movement in the axial direction is allowed in a rotary seal portion having a first seal surface with an open flow path, and a fitting hole formed in the casing member through which the fixed flow path penetrates in the axial direction. And a fixed seal portion having a second seal surface on one side end surface thereof, and the fixed seal portion is urged toward the rotary seal portion by an urging means. The fixed seal part is the rotary seal part. On the other hand, by pressing with a predetermined surface pressure, the first seal surface and the second seal surface are brought into close contact with each other, and from the fixed seal portion to the rotary seal portion side A cylindrical shaft portion that extends coaxially and communicates with the fixed flow channel and has a tip opening communicated with the rotary flow channel, and an outer peripheral surface of the cylindrical shaft portion and an inner peripheral surface of the rotary flow channel. A cylindrical gap formed between the face seal portion and the fixed portion side, the cylindrical gap formed between the face seal portion and the rotary flow path. And a flow suppressing portion that suppresses the flow of the fluid in the cylindrical gap by generating a pressure loss, and the balance ratio of the face seal portion defined by the ratio of the surface pressure to the fluid pressure is 0. Is set to 6 or less, Body leaking to the outside by a predetermined leakage amount corresponding to the balance ratio from the face seal portion.

  According to the present invention, the cylindrical shaft portion that extends coaxially from the rotary seal portion to the fixed seal portion side or from the fixed seal portion to the rotary seal portion side is provided, and the outer peripheral surface of the cylindrical shaft portion is fixed to the fixed flow path or the rotary flow. A cylindrical gap with one side closed between the inner peripheral surface of the passage is formed by including a face seal portion in the axial gap forming range, and pressure loss is generated in the cylindrical gap to thereby form a cylindrical gap in the cylindrical gap. A flow suppressing means for suppressing fluid flow, and further setting the balance ratio of the face seal portion so that the fluid leaks from the face seal portion to the outside with a predetermined leakage amount. Foreign matters generated by wear are discharged together with the fluid leaking from the face seal portion, and these foreign matters can be completely excluded from the supplied fluid by a simple configuration.

(Embodiment 1)
1 and 2 are sectional views of a rotary joint according to Embodiment 1 of the present invention, FIG. 3 is a partial sectional view of a rotary joint according to Embodiment 1 of the present invention, and FIG. 4 is a rotary according to Embodiment 1 of the present invention. It is operation | movement explanatory drawing of a joint.

  First, the overall configuration of the rotary joint 1 will be described with reference to FIGS. 1 and 2. In FIG. 1, a rotary joint 1 is used for a fluid supply mechanism that feeds fluid to a rotating shaft such as a cleaning nozzle or a rotary table used in clean applications where cleanliness is required such as in the food processing field and semiconductor manufacturing field. The rotating part 1a provided with the axial rotation flow path and the fixed part 1b provided with the axial fixed flow path are arranged coaxially. FIG. 2 shows a state where the rotating part 1a and the fixed part 1b are separated in the axial direction for convenience of explanation.

  The rotating portion 1a is fastened to a flow passage hole 2a of a spindle shaft 2 that is a rotating shaft, and the spindle shaft 2 is rotated around an axis A by being driven to rotate by a motor built in the spindle. When used in a machine tool or the like, the spindle shaft 2 rotates and advances and retracts in the axial direction by a clamp / unclamp cylinder (not shown). The fixing portion 1b is fitted and mounted in a fitting hole 3a provided in the cylindrical block-shaped casing member 3, and the casing (not shown) is inserted into a casing (not shown) through which the spindle shaft 2 is inserted by a fastening means such as a bolt. By fastening the member 3 detachably, the fixed portion 1b is arranged coaxially with the rotating portion 1a. A gas such as a cleaning liquid or cooling air is selectively fed to the fitting hole 3a from a fluid supply unit (not shown) (arrow a).

  Next, the detailed structure of the rotary joint 1 will be described. 1 and 2, the rotating portion 1 a mainly includes a rotor 4 mounted on the spindle shaft 2 and a cylindrical shaft portion 7 that passes through the rotor 4 coaxially. The rotor 4 has a configuration in which a flange portion 4b having an outer diameter larger than that of the rotary shaft portion 4a is provided at one end of the rotary shaft portion 4a, and a male screw portion 4d is provided on the outer surface of the rotary shaft portion 4a. It has been. A female threaded portion 2b is provided on the inner surface of the opening end of the flow path hole 2a. By screwing the male threaded portion 4d with the female threaded portion 2b, the rotor 4 is screwed to the spindle shaft 2 and is fastened by an O-ring 6. The contact portion between the outer peripheral surface of the rotor 4 and the inner peripheral surface of the flow path hole 2a is sealed.

  As shown in FIG. 2, a circular concave portion 4c is formed on the side end surface of the rotor 4 on the right side (the side facing the fixed portion 1b), and the first seal ring 5 is fixed to the concave portion 4c. ing. The first seal ring 5 is formed by molding a hard material rich in wear resistance such as ceramic into an annular shape having an opening 5a in the center, and the first seal surface 5b finished to be a smooth surface. It fixes to the recessed part 4c in the state made into the outer surface side. That is, the rotor 4 to which the first seal ring 5 is fixed is a rotary seal portion provided in the rotary portion 1a and having the first seal surface 5b on the side end surface.

  The cylindrical shaft portion 7 is a cylindrical shaft member in which a boss portion 7 b is provided at one end on the downstream side (left side in FIGS. 1 and 2), and the boss portion 7 b is inserted into the mounting hole 4 e provided in the rotor 4. The through-shaft portion 7a that is fixedly mounted by being press-fitted and extends from the boss portion 7b passes through the rotor 4. In this mounted state, the cylindrical shaft portion 7 is inserted through the opening 5 a and extends coaxially from the rotor 4 to the upstream side, and the inner hole of the cylindrical shaft portion 7 is provided through the shaft center portion of the rotor 4. It is a rotating flow path 4f.

  Next, the structure of the fixing portion 1b attached to the casing member 3 will be described. In FIG. 2, the fixing portion 1 b mainly includes the floating sheet 8 fitted and fitted in the fitting hole 3 a of the casing member 3. The floating sheet 8 is provided with a disk-shaped flange portion 8b on one side (the side facing the rotating portion 1a in the figure), and a fixed shaft portion formed with a fixed flow path 8f penetrating in the axial direction on the other side. The shape has 8a. The fixed shaft portion 8a is fitted in the fitting hole 3a in a state where movement in the axial direction is allowed. An O-ring groove 3b is provided on the inner surface of the fitting hole 3a, and the fitting portion of the fixed shaft portion 8a is sealed by the O-ring 11 attached to the O-ring groove 3b. The casing member 3 is provided with an anti-rotation member 12 in the axial direction. When the floating sheet 8 is mounted on the casing member 3, the anti-rotation member 12 has an anti-rotation hole 8c provided in the flange portion 8b. It is inserted in the direction.

  The convex portion 8d provided on the left side of the flange portion 8b (the end surface facing the rotating portion 1a) is provided with a circular concave portion 8e so as to surround the opening surface of the fixed flow path 8f, and the concave portion 8e. A second seal ring 9 is fixed to the. The second seal ring 9 is formed by molding a hard material similar to that of the first seal ring 5 into an annular shape having an opening 9a in the center, and the second seal surface 9b finished to be a smooth surface. It fixes to the recessed part 8e in the state made into the outer surface side. In this state, the fixed flow path 8f communicates with the opening 9a and opens to the second seal surface 9b. That is, the floating sheet 8 to which the second seal ring 9 is fixed is formed so that the fixed flow path 8f penetrates in the axial direction, and the axial movement is allowed in the fitting hole 3a provided in the casing member 3. The fixed seal portion has a fixed shaft portion 8a fitted in a state, and has a second seal surface 9b having a fixed flow path 8f opened on a side end surface.

  In the use state of the rotary joint 1, as shown in FIG. 1, the cylindrical shaft portion 7 is inserted into the fixed flow path 8f, and the rotating portion 1a and the fixed portion 1b are brought close to each other. Thereby, the 1st seal surface 5b and the 2nd seal surface 9b contact | abut, and the surface seal part 10 is formed. In this state, the tip opening 7c of the cylindrical shaft portion 7 opens into the fixed flow path 8f, whereby the rotating flow path 4f communicates with the fixed flow path 8f via the tip opening 7c. A cylindrical gap S is formed between the outer peripheral surface of the cylindrical shaft portion 7 and the inner peripheral surface of the fixed flow path 8f. The cylindrical gap S communicates with the fixed flow path 8f, is formed so as to include the face seal portion 10 in the gap formation range in the axial direction, and the width dimension of the first seal ring 5 from the face seal portion 10 to the rotating portion 1a side. In a position separated only by the concave portion 4c, the dead end is closed and closed.

  That is, the cylindrical shaft portion 7 is provided so as to communicate with the rotary flow path 4f and extend coaxially from the rotary seal portion to the fixed seal portion side, and the tip opening 7c communicates with the fixed flow path 8f. The cylindrical gap S is formed between the outer peripheral surface of the cylindrical shaft portion 7 and the inner peripheral surface of the fixed flow path 8f so as to include the surface seal portion 10 in the axial gap forming range, and communicates with the fixed flow path 8f. It has a form closed at a position separated from the surface seal portion 10 toward the rotating portion 1a. By adopting such a configuration, the fluid supplied from the upstream side into the fitting hole 3a and flowing into the fixed flow path 8f can be guided to the rotary flow path 4f via the cylindrical shaft portion 7.

  At this time, since the cylindrical gap S is closed at a position separated from the face seal portion 10 toward the rotating portion 1a, the flow of fluid in the cylindrical gap S toward the rotating portion 1a is inhibited, but the fluid pressure Acts in the cylindrical gap S. Thereby, as will be described later, the balance ratio in the face seal portion 10 can be stably maintained. In FIG. 1, the cylindrical shaft portion 7 is provided so that the tip opening portion 7c is positioned in front of the upstream end of the fixed shaft portion 8a. However, the tip opening portion 7c extends from the fixed flow path 8f to the fitting hole 3a. The tip opening 7c may be positioned upstream of the face seal portion 10 and communicated with the fixed flow path 8f.

  FIG. 3 shows details of the portion B in FIG. 1, that is, the cylindrical gap S. As described above, the fluid flow from the fixed portion 1b to the rotating portion 1a is performed through the cylindrical shaft portion 7, and the cylindrical gap S has a main function of applying fluid pressure to the face seal portion 10. Therefore, it is desirable that the configuration of the cylindrical gap S as the flow path is such that the fluid flow is suppressed as much as possible. For this reason, in this Embodiment, the flow suppression means which suppresses the flow of the fluid in the cylindrical clearance S is provided in the cylindrical clearance S.

  FIG. 3A shows an example in which a convex portion 8g that protrudes into the cylindrical gap S is provided on the inner surface of the fixed flow path 8f, and the gap distance d between the outer peripheral surface of the cylindrical shaft portion 7 is partially narrowed. Show. Thereby, when the fluid flows in the cylindrical gap S, a pressure loss due to the gap sealing effect occurs, and the flow of the fluid in the cylindrical gap S is suppressed. FIG. 3B shows an example in which a plurality of convex portions 8h and concave portions 8i are alternately provided on the inner surface of the fixed flow path 8f. As a result, pressure loss occurs due to the labyrinth effect caused by the presence of the plurality of convex portions 8h and concave portions 8i in the cylindrical gap S, and the flow of fluid in the cylindrical gap S is similarly suppressed.

  In the present embodiment, either one of FIGS. 3A and 3B may be adopted, or the cylindrical gap S may be set narrow over the entire range in order to ensure the necessary pressure loss. May be. That is, the rotary joint 1 shown in the present embodiment includes a flow suppressing means that suppresses the flow of fluid in the cylindrical gap S by generating a pressure loss in the cylindrical gap S.

  Next, the operation of the rotary joint 1 will be described with reference to FIG. When the rotary joint 1 is used in a machine tool or the like and is accompanied by an advance / retreat operation of the spindle shaft 2, the surface seal portion 10 is moved by the advancement of the floating sheet 8 due to the pressure of the supplied fluid and the advance / retreat operation of the spindle shaft 2. The seal surface is contacted and separated. That is, when the floating sheet 8 is retracted and the first seal surface 5b and the second seal surface 9b are separated from each other, the fluid is fed into the fitting hole 3a, so that the floating sheet 8 moves forward ( Then, the first seal surface 5b comes into contact with the second seal surface 9b to form the surface seal portion 10. When the spindle shaft 2 moves forward (arrow e direction) relative to the fixed portion 1b, the floating seat 8 moves backward (arrow c direction), and the flange portion 8b returns to a position close to the casing member 3. . Then, by relatively retreating the spindle shaft 2 from this state (in the direction of the arrow d), the first seal surface 5b and the second seal surface 9b are returned to a separated state. Further, when the rotary joint 1 is used for an application that does not involve the forward / backward movement of the spindle shaft 2, the seal surface of the face seal portion 10 is not contacted / separated, and the first seal surface 5b and the second seal surface 9b. Is always in contact.

  Next, the sealing function by the face seal portion 10 in the rotary joint 1 will be described. When the fluid to be supplied is fed into the fitting hole 3a (arrow a), the fluid flows into the tip opening 7c of the cylindrical shaft portion 7 through the fixed flow path 8f (arrow f), and further It flows into the rotating flow path 4 f of the rotor 4 through the internal hole of the cylindrical shaft portion 7. At this time, the fluid pressure of the fluid supplied into the fitting hole 3a acts on the side end face 8j on the other side (opposite side of the second seal ring 8) of the fixed shaft portion 8a. As a result, the fixed shaft portion 8a slides toward the rotating portion 1a in the fitting hole 3a, and the second seal ring 9 applies fluid pressure to the projected area A1 of the side end surface 8j with respect to the first seal ring 5. It is pressed with a pressing force F of the multiplied size. In the sliding of the floating sheet 8, the non-rotating hole 8 c provided in the flange portion 8 b slides along the non-rotating member 12 to guide the movement of the floating sheet 8 in the axial direction and A detent is made.

  The pressing force F causes the second seal surface 9b and the first seal surface 5b to be in close contact with each other, whereby the fitting hole 3a passes through the cylindrical shaft portion 7 to the rotating flow path 4f that rotates around the axis. A face seal portion 10 (FIG. 1) that prevents leakage of fluid to be fed is formed. That is, a fluid is supplied from the fluid supply source into the fitting hole 3a and fluid pressure is applied to the other side end face 8j of the fixed shaft portion 8a, so that the floating seat 8 which is a fixed seal portion is a rotary seal portion. By pressing against the rotor 4, the first seal surface 5b and the second seal surface 9b are brought into close contact with each other to form the surface seal portion 10.

  At this time, the fluid pressure of the fluid supplied into the fitting hole 3a acts on the face seal portion 10 via the cylindrical gap S, and plays an important role in stabilizing the balance ratio described below. In the mechanical seal structure employed in the rotary joint 1, as shown in FIG. 4, the seal is obtained by applying a pressing force F due to the fluid pressure acting on the side end face 8j in the fitting hole 3a to the face seal portion 10. Plays a function. And by keeping the balance ratio defined by the relative ratio of the surface pressure generated in the surface seal portion 10 by the pressing force F to the fluid pressure inside the surface seal portion 10 at a ratio set in advance according to the use conditions, The stable sealing performance is maintained.

  That is, in the present embodiment, the fluid pressure acting on the face seal portion 10 is the pressure of the fluid in the cylindrical gap S in which one side is closed and the flow of fluid in the inside is restricted. Is approximately equal to the fluid pressure at. Therefore, even when the flow rate of the fluid flowing through the cylindrical shaft portion 7 varies, the fluid pressure acting on the face seal portion 10 is always substantially equal to the fluid pressure of the fluid supplied to the fitting hole 3a. The balance ratio of the face seal portion 10 is kept substantially constant without greatly fluctuating.

  In the example shown here, the pressing force F is generated only by the fluid force acting on the side end face 8j in the fitting hole 3a. In addition to such fluid force, the floating sheet 8 is urged. The pressing force F may be obtained by adding the surface pressure by urging the rotor 4 side by means (see the compression spring member 113 shown in FIG. 5 in the second embodiment). That is, in this case, the surface pressure generated in the surface seal portion 10 is obtained by adding the surface pressure by the urging means for urging the fixed seal portion toward the rotary seal portion to the surface pressure due to the fluid pressure.

  In the mechanical seal, the smaller the balance ratio, the more likely the fluid leaks from the seal surface. Under conditions where the balance ratio is 0.6 or less, the fluid leaks from the seal surface with a high probability. It has been empirically found that the amount of fluid leakage increases as the balance ratio value decreases. Based on such empirical knowledge, in the rotary joint 1 shown in the present embodiment, the dimensions of each part are set so that the balance ratio is 0.6 or less. That is, by setting the balance ratio to 0.6 or less, the fluid can be leaked from the face seal portion 10 by a predetermined leakage amount corresponding to the value of the balance ratio.

  Here, the leakage amount is required to be equal to or less than a predetermined leakage amount that is allowed within a range that does not affect the sealing performance of the rotary joint 1. The predetermined leak rate allowed is individually set depending on the application and use conditions, but generally 5 ml / min. The following is desirable. In other words, by determining the allowable leakage amount, the balance ratio corresponding to this leakage amount can be estimated, and the actual leakage amount of the rotary joint manufactured based on this balance ratio should be confirmed by trial. Thus, the relationship between the balance ratio and the leakage amount is specified.

  By setting the balance ratio in this way, in the operating state of the rotary joint 1, as shown in FIG. 4, the fluid (arrow g) that has entered the cylindrical gap S from the upstream side always has a predetermined value corresponding to the balance ratio. This amount leaks to the outside through the sliding surface between the first seal surface 5b and the second seal surface 9b (arrow h). Thus, by always leaking a fluid having a predetermined leakage amount that is allowed within a range that does not affect the sealing performance from the face seal portion 10, the following effects are obtained. That is, in the operating state of the rotary joint 1, the first seal surface 5 b and the second seal surface 9 b are always pressed against each other and slide due to the rotation of the rotating portion 1 a, so that the fineness due to wear of the slide surface. Foreign matter is generated.

  Even in such a state, as described above, the fluid in the cylindrical gap S is passed through the sliding surface between the first seal surface 5b and the second seal surface 9b by a predetermined amount corresponding to the balance ratio. By letting it leak to the outside, fine foreign matter generated on the sliding surface is discharged to the outside together with the leaking fluid. Further, since the flow suppression means as shown in FIG. 3 is provided in the cylindrical gap S, the fluid containing the foreign matter generated in the face seal portion 10 does not easily flow back to the fixed flow path 8f through the cylindrical gap S. It has become. For this reason, the foreign matter which generate | occur | produced in the face seal part 10 approachs into the rotation flow path 4f, and the situation which pollutes the fluid supplied downstream is not generated. Therefore, when the rotary joint 1 is incorporated in an apparatus used for clean applications such as the food field and the semiconductor manufacturing field, it is possible to keep the fluid supplied to a high cleanliness.

(Embodiment 2)
5 and 6 are sectional views of the rotary joint according to the second embodiment of the present invention, and FIG. 7 is an operation explanatory view of the rotary joint according to the second embodiment of the present invention. In the second embodiment, the cylindrical shaft portion that extends from the rotary seal portion to the fixed seal portion side in the first embodiment is configured to extend from the fixed seal portion to the rotary seal portion side. It is.

  First, the overall configuration of the rotary joint 101 will be described with reference to FIGS. 5 and 6. In FIG. 1, a rotary joint 101 is used for a fluid supply mechanism that feeds a cooling fluid to a rotary shaft such as a spindle shaft of a machine tool, similarly to the rotary joint 1 shown in the first embodiment. The rotating part 101a provided with the axial rotation flow path and the fixed part 101b provided with the axial fixed flow path are coaxially arranged. FIG. 6 shows a state in which the rotating part 101a and the fixed part 101b are separated in the axial direction for convenience of explanation.

  The rotating portion 101a is fastened to a flow passage hole 102a of a spindle shaft 102, which is a rotating shaft. The spindle shaft 102 is driven to rotate by a motor built in the spindle and rotates around an axis A, and is also clamped / unfastened. A forward and backward movement in the axial direction is performed by a clamp cylinder (not shown). The fixed portion 101b is fitted and fitted in a fitting hole 103a provided in the cylindrical block-shaped casing member 103, and the casing (not shown) is inserted into a frame (not shown) through which the spindle shaft 102 is inserted by a fastening means such as a bolt. By fastening the member 103 detachably, the fixed portion 101b is arranged coaxially with the rotating portion 101a. A gas such as a liquid coolant or cooling air is selectively fed to the fixed portion 101b from a fluid supply portion (not shown) (arrow a).

  Next, the detailed structure of the rotary joint 101 will be described. 5 and 6, the rotating unit 101 a mainly includes a rotor 104 mounted on the spindle shaft 102. The rotor 104 is provided with a flange portion 104b having an outer diameter larger than that of the rotation shaft portion 104a at one end portion of the rotation shaft portion 104a, and rotational channels 104f and 104g that penetrate the shaft center portion in the axial direction and communicate with each other. It is the provided structure. Here, the rotating flow path 104g close to the fixed portion 101b is provided with an inner diameter larger than that of the rotating flow path 104f so as to allow insertion of an insertion portion 107a of a cylindrical shaft portion 107 described later. A male screw portion 104d is provided on the outer surface of the rotating shaft portion 104a, and a female screw portion 102b is provided on the inner surface of the opening end of the flow path hole 102a. By screwing the male screw portion 104d with the female screw portion 102b, the rotor 104 is screwed to the spindle shaft 102, and the contact portion between the outer peripheral surface of the rotor 104 and the inner peripheral surface of the flow passage hole 102a is sealed by the O-ring 106. Is done.

  As shown in FIG. 6, a circular concave portion 104c is formed on the side end surface of the rotor 104 on the right side (the side facing the fixed portion 101b). The concave portion 104c has a first recess shown in the first embodiment. A first seal ring 105 similar to the seal ring 5 is fixed. The first seal ring 105 is fixed to the recess 104c with the first seal surface 105b facing the outer surface, and a rotating flow path 104g is opened in the first seal surface 105b. That is, the rotor 104 to which the first seal ring 105 is fixed is a rotary seal portion having a first seal surface 105b provided in the rotary portion 101a and having a rotary flow path 104g opened on the side end surface.

  Next, the structure of the fixing portion 101b attached to the casing member 103 will be described. In FIG. 6, the fixing portion 101 b mainly includes a floating sheet 108 fitted and fitted in the fitting hole 103 a of the casing member 103 and a cylindrical shaft portion 107 penetrating the floating sheet 108. The floating sheet 108 has a disk-shaped flange portion 108b on one side (the side facing the rotating portion 101a in the drawing) and a shape having a fixed shaft portion 108a on the other side. The fixed shaft portion 108a is fitted in the fitting hole 103a in a state in which movement in the axial direction is allowed.

  An internal hole 108f is formed in the fixed shaft portion 108a so as to penetrate in the axial direction, and the cylindrical shaft portion 107 is fitted and inserted into the internal hole 108f in a state where relative movement in the axial direction is allowed. . The cylindrical shaft portion 107 is a cylindrical shaft member having an internal flow passage 107c penetrating in the axial direction, and the downstream side (rotating portion 101a side) becomes an insertion portion 107a having a reduced outer diameter via a stepped portion 107f. ing. In the operating state of the rotary joint 101, the insertion portion 107a is inserted into the rotating flow path 104g of the rotor 104 (see FIG. 5).

  On the upstream side of the cylindrical shaft portion 107, a boss portion 107b for being fixedly attached to the casing member 103 is provided. A mounting hole 103c is provided in the mounting convex portion 103b provided on the upstream side of the casing member 103, and a boss portion 107b is press-fitted into the mounting hole 103c. The boss portion 107b is fixedly attached to the attachment convex portion 103b by screw fastening by a fastening nut member 114 provided with a fluid supply hole 114a. The fluid supplied from the fluid supply source is supplied into the internal flow path 107c through the fluid supply hole 114a (arrow a). Therefore, the internal flow path 107c is a fixed flow path provided in the fixed portion 101b in the axial direction, and will be described as a fixed flow path 107c in the following description.

  In this fluid supply, the contact surface between the fastening nut member 114 and the boss 107b is sealed by the O-ring 115, thereby preventing the fluid from leaking to the outside. An O-ring groove 103b is provided on the inner surface of the fitting hole 103a, and the fitting part of the fixed shaft portion 108a is sealed by the O-ring 111 attached to the O-ring groove 103b. As a result, leakage of the fluid flowing through the fixed flow path 107c and entering the fitting hole 103a through a minute gap between the inner surface of the internal hole 108f and the outer peripheral surface 107d of the cylindrical shaft portion 107 is prevented. Is done.

  A non-rotating member 112 is planted in the casing member 103 in the axial direction. When the floating sheet 108 is mounted on the casing member 103, the non-rotating member 112 has a non-rotating hole 108c provided in the flange portion 108b. It is inserted in the direction. A coil-like compression spring member 113 as an urging means is attached to the rotation stop member 112, and the compression spring member 113 urges the flange portion 108b toward the rotating portion 101a with a predetermined urging force. In the operating state of the rotary joint 101, a second seal ring 109 described below is pressed against the first seal ring 105 by this urging force, thereby preventing fluid leakage.

  The convex portion 108d provided on the left side of the flange portion 108b (the end surface facing the rotating portion 101a) is formed with a circular concave portion 108e so as to surround the opening surface of the internal hole 108f. A second seal ring 109 similar to the second seal ring 9 in the first embodiment is fixed. The second seal ring 109 is fixed to the recess 108e with the second seal surface 109b facing the outer surface. In this state, the internal hole 108f communicates with the opening 109a and opens in the second seal surface 109b. That is, the floating sheet 108 to which the second seal ring 109 is fixed is in a state in which the fixed flow path 107f is formed so as to penetrate in the axial direction and axial movement is permitted in the fitting hole 103a provided in the casing member 103. The fixed seal portion 108a has a fixed shaft portion 108a to be fitted with the second seal surface 109b on one side end surface. The cylindrical shaft portion 107 fitted and inserted into the internal hole 108f is mounted in a state where the stepped portion 107f is positioned on the upstream side (fixed portion 101b side) of the second seal ring 109, thereby opening 109a. A gap is secured between the insertion portion 107 a and the inner surface of the second seal ring 109.

  In the use state of the rotary joint 101, as shown in FIG. 5, the insertion portion 107a is inserted into the rotation flow path 104g, and the rotation portion 101a and the fixing portion 101b are brought close to each other. As a result, the first seal surface 105b and the second seal surface 109b come into contact with each other to form the surface seal portion 110. In this state, the tip opening 107e of the cylindrical shaft portion 107 is inserted through the opening 105a and opens into the rotating flow path 104g. Thereby, the rotation flow path 104g communicates with the fixed flow path 107c through the tip opening 107e. A cylindrical gap S is formed between the outer peripheral surface of the cylindrical shaft portion 107 and the inner peripheral surface of the rotating flow path 104g. The cylindrical gap S communicates with the rotary flow path 104g, and is formed so as to include the face seal portion 110 in the axial gap forming range. Then, at a position separated from the face seal portion 110 toward the fixed portion 101b side, the stepped portion 107f serves as a dead end and is closed.

  That is, the cylindrical shaft portion 107 is provided so as to extend coaxially from the fixed seal portion to the rotary seal side, communicates with the fixed flow channel 107c, and has a form in which the tip opening 107e communicates with the rotary flow channel 104g. . The cylindrical gap S is formed between the outer peripheral surface of the cylindrical shaft portion 107 and the inner peripheral surface of the rotating flow path 104g so as to include the face seal portion 110 in the axial gap forming range, and communicates with the rotating flow path 104g. It is in a closed form at a position separated from the surface seal part 110 toward the fixed part 101b. By adopting such a configuration, the fluid supplied from the upstream side to the fluid supply hole 114a and flowing into the fixed flow path 107c can be guided to the rotary flow path 104g via the cylindrical shaft portion 107.

  At this time, since the cylindrical gap S is closed at a position separated from the face seal portion 110 toward the fixed portion 101b, the flow of fluid in the cylindrical gap S toward the fixed portion 101b is inhibited, but the fluid pressure Acts in the cylindrical gap S. Thereby, as will be described later, the balance ratio in the face seal portion 110 can be stably maintained. In FIG. 5, the position at which the tip opening 107e of the cylindrical shaft 107 opens may be on the downstream side of the face seal portion 110, and the length dimension of the insertion portion 107a may be arbitrarily determined. The portion B in FIG. 5 is provided with a flow suppressing means as shown in FIG. 3 in the first embodiment, so that the fluid in the cylindrical gap S does not easily flow into the rotating flow path 104g.

  Next, the operation of the rotary joint 101 will be described with reference to FIG. In the operating state of the rotary joint 101, unlike the rotary joint 1 shown in the first embodiment, since the inelastic force of the compression spring member 113 is always acting on the floating seat 108, the spindle shaft 102 is moved forward and backward. The seal surface of the face seal part 110 is brought into and out of contact. In other words, in a state where the spindle shaft 102 is retracted relative to the fixed portion 101 b, the floating sheet 108 moves forward (in the direction of arrow b) due to the ineffective force of the compression spring member 113. In this state, when the spindle shaft 102 moves forward (in the direction of arrow e) relative to the fixed portion 101b, the floating sheet 8 is pushed in and moves backward (in the direction of arrow c), and the first seal surface 105b moves to the first position. The surface seal portion 110 is formed in contact with the second seal surface 109b. Then, by relatively retreating the spindle shaft 102 (in the direction of the arrow d) from this state, the first seal surface 105b and the second seal surface 109b are returned to a separated state.

  Next, the sealing function by the face seal part 110 in the rotary joint 101 will be described. When the fluid to be supplied is fed into the fluid supply hole 114a (arrow a), the fluid flows into the fixed flow path 107c of the cylindrical shaft portion 107 (arrow f), and further, the tip is passed through the insertion portion 107a. It flows from the opening 107e into the rotary flow path 104g of the rotor 104 and further into the rotary flow path 104f. At this time, due to the biasing force that the compression spring member 113 applies to the flange portion 108 b, the fixed shaft portion 108 a slides toward the rotating portion 101 a in the fitting hole 103 a, and the second seal ring 109 is moved to the first seal ring 105. On the other hand, the compression spring member 113 is pressed with a pressing force F corresponding to the urging force. In the sliding of the floating sheet 108, the anti-rotation hole 108c provided in the flange portion 108b slides along the anti-rotation member 112 to guide the movement of the floating sheet 108 in the axial direction and A detent is made.

  The pressing force F causes the second seal surface 109b and the first seal surface 105b to be in close contact with each other, whereby the rotation flow path 104g in a rotating state around the shaft from the fitting hole 103a via the cylindrical shaft portion 107, A face seal portion 110 (FIG. 5) that prevents leakage of the fluid fed to 104f is formed. That is, by urging the fixed seal portion to the rotation seal portion side by the compression spring member 113 that is an urging means and pressing the floating sheet 108 that is the fixed seal portion against the rotor 104 that is the rotation seal portion, The first seal surface 105b and the second seal surface 109b are brought into close contact with each other to form the surface seal portion 110.

  At this time, the fluid pressure of the fluid supplied into the fixed flow path 107c acts on the face seal portion 110 via the cylindrical gap S, and plays an important role in stabilizing the balance ratio described below. In the mechanical seal structure employed in the rotary joint 101, as shown in FIG. 7, the pressing force F generated by urging the fixed seal portion toward the rotary seal portion by the compression spring member 113 as the urging means is applied to the face seal portion. By acting on 110, a sealing function is achieved. By maintaining the balance ratio defined by the relative ratio of the surface pressure generated in the surface seal portion 110 by the pressing force F to the fluid pressure inside the surface seal portion 110 at a ratio set in advance according to the use conditions. In order to maintain stable sealing performance.

  That is, in the second embodiment, the fluid pressure acting on the face seal portion 110 is the pressure of the fluid in the cylindrical gap S in which one side is closed and the flow of fluid in the inside is restricted. Is approximately equal to the fluid pressure at. Therefore, even when the flow rate of the fluid flowing through the fixed flow path 107c and the rotary flow paths 104g and 104f varies, the fluid pressure acting on the face seal portion 110 is always the fluid pressure of the fluid in the rotary flow path 104g. In other words, the balance ratio of the face seal portion 110 is kept substantially constant without greatly fluctuating.

  Also in the rotary joint 101 shown in the second embodiment, the balance ratio is set to 0.6 or less as in the first embodiment. This balance ratio is set so that the fluid in the cylindrical gap S leaks from the face seal portion 110 to the outside with a predetermined leakage amount that is allowed in a range that does not affect the sealing performance of the rotary joint 101. ing. The relationship between the predetermined leakage amount and the balance ratio is as described in the first embodiment.

  By setting the balance ratio in this way, in the operating state of the rotary joint 101, as shown in FIG. 7, the fluid (arrow g) that has entered the cylindrical gap S from the rotary flow path 104g always corresponds to the balance ratio. In addition, a predetermined amount of leakage leaks to the outside through the sliding surfaces of the first seal surface 105b and the second seal surface 109b (arrow h). Thus, by always leaking a predetermined amount of fluid that is allowed from the face seal portion 110 within a range that does not affect the sealing performance, the same effect as in the first embodiment is obtained.

  The rotary joint of the present invention has a feature that foreign matters generated due to wear of the seal surface can be completely excluded from a fluid supplied by a simple configuration, and is a device used in the field of food or semiconductor manufacturing. This is useful for applications such as supplying cleaning fluid or air to the rotating part.

Sectional drawing of the rotary joint in Embodiment 1 of this invention Sectional drawing of the rotary joint in Embodiment 1 of this invention The fragmentary sectional view of the rotary joint in Embodiment 1 of this invention Operational explanatory diagram of the rotary joint in the first embodiment of the present invention Sectional drawing of the rotary joint in Embodiment 2 of this invention Sectional drawing of the rotary joint in Embodiment 2 of this invention Operational explanatory diagram of the rotary joint in the second embodiment of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,101 Rotary joint 1a, 101a Rotating part 1b, 101b Fixed part 2, 102 Spindle shaft 3, 103 Casing member 4, 104 Rotor 4f, 104f, 104g Rotating flow path 5, 105 First seal ring 5b, 105b First Sealing surface 7, 107 Cylindrical shaft portion 8, 108 Floating sheet 8a, 108a Fixed shaft portion 8f, 107c Fixed flow path 9, 109 Second seal ring 9b Second seal surface 10, 110 Surface seal portion 113 Compression spring member

Claims (3)

A fluid supplied from a fluid supply source is formed by coaxially arranging a rotating portion provided with an axial rotation flow path and attached to the rotation shaft and a fixed portion provided with an axial fixed flow path and attached to a casing member. A rotary joint that feeds through the fixed flow path to the rotary flow path of the rotating part that rotates around the axis,
A rotary seal portion provided in the rotary portion and having a first seal surface on a side end surface;
The fixed flow path has a fixed shaft portion that is formed so as to penetrate in the axial direction and is fitted in a fitting hole provided in the casing member in a state in which the movement in the axial direction is allowed, and is on one side A fixed seal portion having a second seal surface in which the fixed flow path is opened at an end surface;
The fluid is supplied from the fluid supply source into the fitting hole and fluid pressure is applied to the other side end surface of the fixed shaft portion, and the fixed seal portion is moved to the rotary seal portion with the fluid pressure. A surface seal portion formed by bringing the first seal surface and the second seal surface into close contact with each other by pressing with a surface pressure according to
A cylindrical shaft portion provided coaxially extending from the rotating seal portion to the fixed seal portion side, communicating with the rotating flow path and having a tip opening communicating with the fixed flow path;
The surface seal portion is formed between the outer peripheral surface of the cylindrical shaft portion and the inner peripheral surface of the fixed flow path so as to be included in a gap forming range in the axial direction, and communicates with the fixed flow path from the surface seal portion. A cylindrical gap closed at a position separated to the rotating part side;
Flow suppression means for suppressing the flow of the fluid in the cylindrical gap by generating a pressure loss in the cylindrical gap,
The balance ratio of the face seal portion defined by the ratio of the surface pressure to the fluid pressure is set to 0.6 or less, and the fluid leaks from the face seal portion with a predetermined leakage amount according to the balance ratio. A rotary joint that leaks to the outside.   2. The rotary joint according to claim 1, wherein the surface pressure is obtained by adding a surface pressure by an urging means for urging the fixed seal portion toward the rotary seal portion to the surface pressure due to the fluid pressure. A fluid supplied from a fluid supply source is formed by coaxially arranging a rotating portion provided with an axial rotation flow path and attached to the rotation shaft and a fixed portion provided with an axial fixed flow path and attached to a casing member. A rotary joint that feeds through the fixed flow path to the rotary flow path of the rotating part that rotates around the axis,
A rotary seal portion having a first seal surface provided in the rotary portion and having the rotary flow channel open on a side end surface;
The fixed flow path has a fixed shaft portion that is formed so as to penetrate in the axial direction and is fitted in a fitting hole provided in the casing member in a state in which the movement in the axial direction is allowed, and is on one side A fixed seal portion having a second seal surface on the end surface;
By urging the fixed seal portion toward the rotary seal portion by an urging means and pressing the fixed seal portion against the rotary seal portion with a predetermined surface pressure, the first seal surface and the second seal surface are pressed. A surface seal part formed by closely adhering a seal surface;
A cylindrical shaft portion provided coaxially extending from the fixed seal portion to the rotary seal portion side, communicating with the fixed flow channel and having a tip opening communicating with the rotary flow channel;
The surface seal portion is formed between the outer peripheral surface of the cylindrical shaft portion and the inner peripheral surface of the rotary flow path so as to be included in a gap forming range in the axial direction, and communicates with the rotary flow path from the face seal portion. A cylindrical gap closed at a position separated to the fixed part side;
Flow suppression means for suppressing the flow of the fluid in the cylindrical gap by generating a pressure loss in the cylindrical gap,
The balance ratio of the face seal portion defined by the ratio of the surface pressure to the fluid pressure is set to 0.6 or less, and the fluid leaks from the face seal portion with a predetermined leakage amount according to the balance ratio. A rotary joint that leaks to the outside.

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