JP6266376B2 - Hydrostatic non-contact mechanical seal - Google Patents

Description

  The present invention relates to a hydrostatic non-contact type mechanical seal used as a shaft sealing means for rotating equipment such as a blower, a compressor, and a stirrer that handles gas.

  This type of non-contact type mechanical seal of static pressure type includes a rotary seal ring fixed to a rotary shaft, and a rotary side seal end face which is held in a seal case so as to be movable in the axial direction and which is a tip face of the rotary seal ring. A stationary sealing ring in which a static pressure generating groove is formed on the stationary sealing end face that is the opposite end face, and a spring that is interposed between the seal case and the stationary sealing ring to press and bias the stationary sealing ring to the rotating sealing ring And a seal gas supply path that passes through the seal case and the stationary seal ring to reach the static pressure generating groove, and supplies the seal gas from the seal gas supply path to the static pressure generating groove through an orifice disposed therein. By doing so, a configuration is known in which the sealed fluid region and the non-sealed fluid region are sealed while the sealing end surfaces of both sealing rings are maintained in a non-contact state (see, for example, Patent Document 1). ).

  In such a non-contact type mechanical seal, an opening force that acts in a direction to open between the sealed end faces by the seal gas introduced between the sealed end faces from the static pressure generating groove (by the seal gas introduced between the sealed end faces). This is due to the static pressure that occurs, and this opening force balances with the closing force acting in the direction of closing between the sealed end faces by the spring, so that an appropriate gap between the sealed end faces (generally 5 to 15 μm, Hereinafter referred to as “appropriate gap”).

  Thus, a stationary side component (seal case and stationary sealing ring held by the sealing case and the like) and a rotating side component (rotating sealing ring and a sleeve for fixing the same to the rotating shaft) constituting a non-contact type mechanical seal. The relative position in the axial direction (hereinafter referred to as “component relative position”) is set so that the opening / closing force is balanced to provide an appropriate gap between the sealed end faces. The component relative position (hereinafter referred to as “appropriate component relative position”) set to 1 is secured.

  By the way, the relative position of the components may change due to vibration of the rotating equipment and the gap between the sealed end faces may not be an appropriate gap. In such a case, an orifice is provided in the seal gas supply path. From the above, the gap between the sealed end faces is automatically adjusted to an appropriate gap by the effect of the orifice (see paragraph number [0022] of Patent Document 1). That is, when the gap between the sealed end faces becomes narrower than the appropriate gap, the amount of seal gas flowing out from the static pressure generating groove to the sealed end face decreases, and the amount of seal gas flowing out is supplied to the static pressure generating groove through the orifice. Less than the amount of seal gas supplied. As described above, the flow rate and the supply amount of the seal gas in the static pressure generating groove are unbalanced, so that the seal gas pressure in the static pressure generating groove (hereinafter referred to as “pocket pressure”) is maintained at an appropriate gap. The opening force due to the seal gas that rises from the current pocket pressure (hereinafter referred to as “appropriate pocket pressure”) and flows out from the static pressure generating groove between the sealed end faces becomes larger than the closing force due to the spring. As a result, the gap between the sealing end faces is changed so as to increase, and the gap is adjusted to an appropriate gap. Also, when the gap between the sealed end faces becomes wider than the appropriate gap, contrary to the above case, the outflow amount of the seal gas from the static pressure generating groove to the sealed end face passes through the orifice to the static pressure generating groove. As the amount of seal gas supplied increases, the pocket pressure falls below the appropriate pocket pressure, and the opening force due to the seal gas flowing out from the static pressure generating groove between the sealed end faces becomes smaller than the closing force due to the spring. As a result, the gap between the sealing end faces is changed to be small, and the gap is adjusted to an appropriate gap.

JP 2007-2111939 A

  However, since a high level of skill is required to assemble the mechanical seal so that the component relative position becomes the proper component relative position, the component relative position may differ from the proper component relative position due to poor assembly accuracy. . In addition, even when assembled at appropriate component relative positions, when the fluid to be sealed is at a high or low temperature, the difference in thermal expansion between the parts can be caused by a large change in temperature conditions during assembly at normal temperature and during operation. In some cases, a gap due to a heat shrinkage difference may occur, and the component relative position may be different from the proper component relative position. When the component relative position deviates from the appropriate component relative position due to such an assembly accuracy defect or a change in temperature condition (hereinafter referred to as “assembly accuracy defect”), when the deviation amount (deviation amount) is very small It is possible to keep the gap between the sealing end faces in an appropriate gap by the automatic adjustment based on the orifice effect described above, but if the amount of deviation is so large that it cannot be covered by such automatic adjustment, the non-contact type mechanical seal The seal function (hereinafter referred to as “non-contact seal function”) is not properly exhibited, leading to major accidents such as mechanical seal breakage and large-scale leakage.

  That is, when the axial position of the rotation side component is biased in the direction of pressing the stationary sealing ring than when the relative position is the proper component, or when the axial direction position of the stationary side component is the proper component relative position. When the rotating seal ring is biased in the direction of pressing, the spring is compressed (the amount of compression of the spring is increased) and the spring load is increased as compared with the case where it is in the proper component relative position. Become. Therefore, the spring load (closing force) is larger than the opening force by the sealing gas supplied between the sealed end faces from the static pressure generating groove, and the sealed end faces are hardly opened or, in extreme cases, the sealed end faces are in contact with each other. Will rotate relative to each other. As a result, the non-contact sealing function is not properly exhibited, and problems such as seizure of the sealed end surface occur.

  Contrary to the above, when the axial direction position of the rotating side component or the stationary side component is biased in the direction in which both sealing rings are separated from the case of the appropriate component relative position, it is in the proper component relative position. As compared with the case, the spring is extended (the amount of compression of the spring is reduced), and the spring load is reduced. Therefore, the spring load (closing force) becomes smaller than the opening force by the seal gas supplied between the sealed end faces from the static pressure generating groove, and the gap between the sealed end faces opens larger than the appropriate gap. As a result, a proper non-contact sealing function is not exhibited, and a large amount of sealing gas flows out between the sealed end faces, or leakage of the sealed fluid occurs.

  The present invention has been made in view of the above points, and is a static pressure type that can exhibit an appropriate non-contact type sealing function even when the relative position of the component is different from the relative position of the proper component due to poor assembly accuracy or the like. The object is to provide a non-contact type mechanical seal.

  The present invention provides a rotating seal ring fixed to a rotating shaft and a stationary side sealing end surface, which is a tip end surface that is held in a seal case so as to be movable in the axial direction and faces the rotating side sealing end surface that is the tip end surface of the rotating seal ring. A stationary sealing ring having a pressure generating groove; a spring interposed between the sealing case and the stationary sealing ring to press and bias the stationary sealing ring to the rotating sealing ring; and the seal case and the stationary sealing ring. A seal gas supply path to the static pressure generating groove, and the seal gas is supplied from the seal gas supply path to the static pressure generating groove through the orifice disposed in the seal gas supply path so that the static seal ring is connected between the sealing end faces. By closing the closing force that pushes the sealing ring in the approaching direction and the opening force that pushes the stationary sealing ring in the direction separating the sealing end faces, the sealed end faces of both sealing rings are kept in a non-contact state while being sealed. Fluid region and unsealed fluid In order to achieve the above object, a static pressure non-contact type mechanical seal configured to seal a region is particularly sealed with a pair of O-rings between opposed peripheral surfaces of a stationary seal ring and a seal case. The pocket pressure introduction space is formed, and a pocket pressure introduction path is formed to connect the portion downstream of the orifice in the seal gas supply path and the pocket pressure introduction space in communication with the stationary sealing ring or seal case, and introduce pocket pressure. A pocket pressure receiving surface is formed that generates axial thrust that pushes the stationary seal ring away from the rotating seal ring by the pressure in the pocket pressure introduction space acting on the stationary seal ring part facing the space. The axis generated by the pocket pressure receiving surface is a first opening force generated by the sealing gas that flows between the sealing end surfaces from the static pressure generating groove. It is to propose that you configured to be obtained by weighting the second opening force is directed thrust.

  In a preferred embodiment of such a static pressure type non-contact type mechanical seal, when the orifice is disposed in a seal gas supply path portion formed in the stationary seal ring, the pocket pressure introducing path is a stationary seal ring. Formed. Alternatively, when the orifice is disposed in a seal gas supply path portion formed in the seal case, a pocket pressure introduction path is formed in the seal case. The seal gas supply path is an annular space formed between the opposed peripheral surfaces of the seal case and the stationary seal ring, and is a communication sealed by the first and second O-rings loaded between the opposed peripheral surfaces. A space, a case side passage formed in the seal case and communicating with the communication space, and a seal ring side passage formed in the stationary seal ring and connecting the static pressure generating groove and the communication space. The pocket pressure introduction space is an annular space formed between the opposed peripheral surfaces of the seal case and the stationary sealing ring, and is sealed by the third and fourth O-rings loaded between the opposed peripheral surfaces. In this case, the communication space and the pocket pressure introduction space are formed between the inner peripheral surface of the seal case and the outer peripheral surface of the stationary sealing ring, and the second O-ring and the third O-ring are combined. Is preferred. In the case where the seal case has a radially opposing portion on the inner peripheral surface of the stationary seal ring, the pocket pressure introduction space includes an inner peripheral surface of the stationary seal ring and an outer peripheral surface of the seal case portion. It can also be formed between. Further, when the pressure of the sealed fluid region fluctuates, a back pressure chamber sealed with an O-ring is formed between the base end portion of the stationary sealing ring and the seal case portion facing the axial direction, and A direction in which a sealed pressure region is brought close to the stationary sealing ring by the pressure of the sealed fluid region introduced into the back pressure chamber by forming a back pressure introduction path that connects the sealed fluid region and the back pressure chamber to the stationary sealing ring. It is preferable that the closing force is generated by generating an axial thrust force that is pressed against the spring so that the axial thrust is applied to the spring force.

  The static pressure type non-contact type mechanical seal of the present invention has the first opening force due to the pressure of the seal gas flowing out between the sealed end faces from the static pressure generating groove and the pressure (pocket pressure) of the seal gas in the static pressure generating groove. The configuration is such that the second opening force generated by acting on the pocket pressure receiving surface acts as an opening force, and when the spring load increases or decreases due to deviation of the relative position of the component from the appropriate component relative position Accordingly, the second opening force is also configured to increase / decrease, so that when the closing force increases / decreases due to the increase / decrease change of the spring load, the opening force and the closing force are the same as in the proper component relative position. Can be balanced, and a non-contact sealing function equivalent to that in a proper component relative position can be exhibited.

  As described above, the static pressure non-contact mechanical seal of the present invention has a proper component relative position even when the component relative position is deviated from the proper component relative position due to poor assembly accuracy or the like. As with the relative position, a good non-contact sealing function can be exhibited, so that even an unskilled person can easily assemble without requiring a high degree of skill. It can be suitably used for applications in which temperature conditions are significantly different between operation and operation, and it has a very high practical value.

FIG. 1 is a sectional view showing an example of a hydrostatic non-contact mechanical seal according to the present invention. FIG. 2 is a detailed cross-sectional view showing an enlarged main part of FIG. FIG. 3 is a sectional view taken along line III-III in FIG. FIG. 4 is a cross-sectional view corresponding to FIG. 1 showing a modification of the hydrostatic non-contact mechanical seal according to the present invention. FIG. 5 is a cross-sectional view corresponding to FIG. 1 showing another modification of the hydrostatic non-contact type mechanical seal according to the present invention. FIG. 6 is a cross-sectional view corresponding to FIG. 1 showing still another modification of the hydrostatic non-contact mechanical seal according to the present invention. FIG. 7 is a cross-sectional view corresponding to FIG. 1 showing still another modification of the hydrostatic non-contact mechanical seal according to the present invention.

  Hereinafter, embodiments for carrying out the present invention will be specifically described with reference to the drawings.

  FIG. 1 is a cross-sectional view showing an example of a hydrostatic non-contact mechanical seal according to the present invention, FIG. 2 is a detailed cross-sectional view showing an enlarged main part of FIG. 1, and FIG. It is sectional drawing which follows an III-III line.

  A static pressure non-contact type mechanical seal M1 shown in FIG. 1 shields and seals an in-machine gas region H that is a sealed fluid region and an out-of-machine gas region (in this example, an atmospheric region) L that is a non-sealed fluid region. A cylindrical seal case 2 attached to a housing (device housing) 1 of the rotating device, and a sleeve 4 inserted and fixed to the rotating shaft 3 of the rotating device concentrically passing through the seal case 2 The stationary seal ring 5 held in the seal case 2 so as to be movable in the axial direction, and the stationary seal ring 5 is positioned on the in-machine gas region H side of the stationary seal ring 5 and fixed to the rotary shaft 3 in a state of being directly opposed to the stationary seal ring 5. A rotary seal ring 6, a spring 7 interposed between the seal case 2 and the stationary seal ring 5 to urge the stationary seal ring 5 against the rotary seal ring 6, and a first opening force Fo1 are generated. One opening force generating means 8 and a second opening force F And a second opening force generating means 9 for generating 2 and opposing the sealing rings 5 and 6 by balancing the closing force Fc (= Fc1) and the opening force Fo (= Fo1 + Fo2) due to the spring load Fc1. An in-machine gas region H as an outer peripheral side region and an out-of-machine region as an inner peripheral side region in the relative rotation portion of both sealed end surfaces 5a and 6a while maintaining the sealed end surfaces 5a and 6a between the end surfaces in a non-contact state. It is configured to seal between the atmosphere region L. In the following description, front and rear mean the left and right in FIGS.

  As shown in FIG. 1, the seal case 2 includes a cylindrical case main body 2a attached horizontally to the outer end (front end) 1a of the equipment housing 1 and a circle attached to the base end (front end). An annular flange body 2b is connected by an appropriate number of mounting bolts 2c, and is attached to the equipment flange 1 by an appropriate number of mounting bolts 2d penetrating both bodies 2a and 2b.

  As shown in FIG. 1, the sleeve 4 is integrally composed of a cylindrical main body portion 4 a inserted through the rotary shaft 3 and an annular receiving portion 4 b formed bulging at the front end portion (rear end portion). The first sleeve portion, the thick cylindrical fixing portion 4c inserted through the rotating shaft 3, and the thin-walled cylindrical shape extending in the axial direction from the tip outer peripheral portion (rear end outer peripheral portion) and fitted to the main body portion 4a. And a second sleeve portion integrally formed with the pressing portion 4d. Thus, as shown in FIG. 1, the sleeve 4 is formed by screwing an appropriate number of connecting bolts 4e inserted through the fixing portion 4c into the main body portion 4a to thereby form the first sleeve portions 4a and 4b and the second sleeve portion 4c. , 4d are integrally connected. Thus, the sleeve 4 is inserted into the rotary shaft 3 by tightening an appropriate number of set screws 4f screwed into the portion protruding from the seal case 2 to the atmosphere region L side in the fixed portion 4c. Fixed removably. The outer diameter of the sleeve 4 is maximum at the receiving portion 4b, and the outer diameter on the atmosphere region L side from the receiving portion 4b is the same (constant).

  The stationary seal ring 5 is held in the seal case 2 so as to be movable in the axial direction (front-rear direction) and non-rotatably relative to the pressing portion 4d of the sleeve 4 in a concentric manner. That is, as shown in FIG. 1, the stationary seal ring 5 includes a pair of front and rear first and second electrodes arranged in parallel at a predetermined interval in the axial direction between the outer peripheral surface thereof and the inner peripheral surface of the case body 2 a of the seal case 2. In a secondary seal state with the two O-rings 10 and 11 interposed, the seal case 2 is held so as to be movable in the axial direction. Further, as shown in FIG. 1, the stationary seal ring 5 is engaged with a drive pin 12 implanted in the flange body 2b of the seal case 2 in an appropriate number of engagement recesses 5b drilled in the base end portion (front end portion). By doing so, relative rotation with respect to the seal case 2 is prevented in a state where movement in the axial direction within a certain range is allowed. In this example, the stationary sealing ring 5 is an annular body made of carbon, and its front end surface (rear end surface) is configured as a sealed end surface (stationary side sealing end surface) 5a which is a smooth annular plane perpendicular to the axis. An annular protrusion 5c is formed on the outer peripheral surface of the stationary seal ring 5 so as to be positioned between the first and second O-rings 10 and 11 and restrict the movement of the O-rings 10 and 11 in the mutual approaching direction. The flange body 2b is formed with a cylindrical protrusion 2e that protrudes between the opposing peripheral surfaces of the case body 2a and the stationary sealing ring 5 and restricts the movement of the first O ring 10 in the direction away from the second O ring 11. In addition, an annular step 2f that restricts the movement of the second O-ring 11 in the direction away from the first O-ring 10 is formed on the inner peripheral surface of the case body 2a. Further, when the seal case 2 is removed from the device housing 1, the annular protrusion 5c abuts against the second O-ring 11 so that the seal case 2 (case body 2a) of the stationary seal ring 5 by the biasing force of the spring 7 is obtained. ) Is prevented from falling off.

  The rotary seal ring 6 is disposed on the in-machine gas region H side (rear side) of the stationary seal ring 5 and is fixed to the rotary shaft 3 via the sleeve 4. That is, as shown in FIG. 1, the rotary seal ring 6 is arranged in the case main body 2a of the seal case 2, and is fitted and connected to the main body portion 4a of the sleeve 4 in a state of being directly opposed to the stationary seal ring 5. The bolt 4e is fastened and clamped between the receiving portion 4b and the pressing portion 4d of the sleeve 4 to be fixed to the sleeve 4. The front end face (front end face) of the rotary seal ring 6 is configured as a seal end face (rotary side seal end face) 6a which is a smooth annular plane perpendicular to the axis. In this example, the rotary seal ring 6 is an annular body made of metal such as stainless steel, and a ceramic layer 6b is formed on the front end surface of the rotary seal ring 6, and the rotary side sealed end surface 6a is constituted by the ceramic layer 6b. ing. Further, the rotary seal ring 6 is rotated by engaging the drive pin 13 implanted in the receiving portion 4b of the sleeve 4 with the engagement concave portion 6c formed in the base end portion (rear end portion) thereof. Relative rotation with respect to the shaft 3 is prevented.

  As shown in FIG. 1, the spring 7 is composed of a plurality of coil springs (only one is shown) interposed between the stationary seal ring 5 and the flange body 2b of the seal case 2 at equal intervals in the circumferential direction. An axial thrust force that presses and urges the stationary seal ring 5 toward the rotary seal ring 6 in a direction in which the sealed end faces 5a and 6a approach each other, that is, a sealed end face. A closing force Fc acting in the direction of closing 5a and 6a is generated.

  As shown in FIG. 1, the first opening force generating means 8 includes a static pressure generating groove 81 formed on the stationary-side sealing end surface 5a, and a seal gas S formed on the sealing case 2 and the stationary sealing ring 5 so that the seal gas S is generated in the static pressure generating groove. 81 is provided with a seal gas supply path 82 to be supplied to 81 and an orifice 83 disposed in the seal gas supply path 82, and is stationary by the seal gas S flowing out from the static pressure generating groove 81 between the sealed end faces 5a and 6a. An axial thrust that presses the sealing ring 5 in a direction in which the sealing end surfaces 5a and 6a are separated from each other, that is, a first opening force Fo1 that acts in a direction in which the sealing end surfaces 5a and 6a are opened is generated.

  As shown in FIGS. 1 to 3, the static pressure generating groove 81 is formed at a central portion or a substantially central portion in the radial direction of the stationary side sealing end surface 5a, and has a concentric annular shape with the stationary side sealing end surface 5a. It is a shallow groove having a triangular cross section that is continuous or intermittent, and the latter is employed in this example. That is, as shown in FIG. 3, the static pressure generating groove 81 is composed of a plurality of arc-shaped concave grooves 81a that are concentrically arranged in parallel with the stationary-side sealed end face 5a.

  As shown in FIG. 1, the seal gas supply path 82 is a series of ones formed in the seal case 2 and the stationary seal ring 5, and the communication formed between the opposed peripheral surfaces of the seal case 2 and the stationary seal ring 5. A space 82a, a case side passage 82b that passes through the case body 2a of the seal case 2 and communicates with the communication space 82a, and a seal ring side passage that passes through the stationary seal ring 5 and extends from the communication space 82a to the static pressure generating groove 81. 82c.

  As shown in FIG. 1, the communication space 82 a is an annular space formed between the inner peripheral surface of the case body 2 a of the seal case 2 and the outer peripheral surface of the stationary sealing ring 5, and is loaded between the peripheral surfaces. The first and second O-rings 10 and 11 are sealed. In addition, the diameters of the contact surfaces (seal surfaces) of the first and second O-rings 10 and 11 on the outer peripheral surface of the stationary seal ring 5 are set to be the same, and the axis of the stationary seal ring 5 due to the pressure in the communication space 82a It is devised not to generate directional thrust.

  The case side passage 82b is connected to a seal gas supply pipe 84 led from a predetermined seal gas supply source (not shown) at the upstream end thereof, and has a higher pressure than the gas in the in-machine gas region H (in-machine gas). The gas S is supplied to the communication space 82a.

  As shown in FIG. 2, the sealing ring side passage 82c has an upstream end opened to the communication space 82a on the outer peripheral surface of the annular projection 5c of the stationary sealing ring 5, and its downstream portion is branched. The branch portion 82 d is connected to each arcuate groove 81 a of the static pressure generating groove 81.

  As shown in FIGS. 1 and 2, the orifice 83 is disposed at an appropriate position in the upstream portion of the sealed ring side passage 82c, that is, in the unsealed sealed ring side passage portion.

  Therefore, according to the first opening force generating means 8, the seal gas S supplied from the case side passage 82b to the communication space 82a passes through the orifice 83 from the sealing ring side passage 82c, and from each branch portion 82d to the static pressure generation groove. 81, the seal gas S is supplied to each arc-shaped concave groove 81a and flows out from the static pressure generating groove 81 between the sealed end surfaces 5a and 6a, and the first pressure due to the static pressure acting in the opening direction between the sealed end surfaces 5a and 6a. One opening force Fo1 is generated.

  As the sealing gas S, a gas that is harmless even if released into the atmosphere and does not adversely affect the in-machine gas is appropriately selected according to the sealing conditions. In this example, clean room temperature nitrogen gas that is inert to various substances and harmless to the human body is used. In general, the pressure of the seal gas S supplied from the seal gas supply pipe 84 (seal gas source pressure) is generally equal to the pressure (pocket pressure) P in the static pressure generating groove 81 is the in-machine gas pressure (the pressure in the in-machine gas region H). ) Is set higher by 1 to 3 bar than the in-machine gas pressure so as to be higher by 0.5 to 1.5 bar. The supply of the seal gas S from the seal gas supply path 82 to the static pressure generating groove 81 is performed during operation of the rotating device (during driving of the rotating shaft 3), and is stopped after the operation is stopped. The operation of the rotating device is started after the supply of the seal gas S is started and after the sealed end surfaces 5a and 6a are maintained in a non-contact state. This is performed after the operation of the apparatus is stopped and after the rotating shaft 3 is completely stopped.

  As shown in FIGS. 1 and 2, the second opening force generating means 9 is formed in the pocket pressure introducing space 91 formed between the opposed peripheral surfaces of the stationary sealing ring 5 and the sealing case 2, and the stationary sealing ring 5. And a pocket pressure receiving surface 93.

  As shown in FIG. 2, the pocket pressure introduction space 91 is located between the outer peripheral surface of the stationary sealing ring 5 and the inner peripheral surface of the case body 2a of the seal case 2 facing the stationary sealing end surface 5a side from the communication space 82a. It is an annular space formed at (rear), and is sealed by third and fourth O-rings 94 and 95 loaded between the opposed peripheral surfaces. In this example, the third O-ring 94 is also used as the second O-ring 11, and the pocket pressure introduction space 91 and the communication space 82 a are axially sandwiched by the second O-ring 11 (third O-ring 94). Adjacent to. Further, the movement of the fourth O-ring 95 in the direction away from the third O-ring 94 is prevented by the annular protrusion 2g formed on the inner peripheral portion of the case body 2a. The diameter of the contact surface (seal surface) of the fourth O-ring 95 on the outer peripheral surface of the stationary seal ring 5 is the diameter of the contact surface (seal surface) of the third O-ring 94 (second O-ring 11) on the outer peripheral surface. The fourth O-ring 95 is prevented from moving in a direction approaching the third O-ring 94 by an annular step portion (a pocket pressure receiving surface described later) 93 that connects both seal surfaces.

  As shown in FIGS. 1 and 2, the pocket pressure introduction path 92 is formed in the stationary seal ring 5 and is one branch portion 82d that is a portion downstream of the orifice 83 in the pocket pressure introduction space 91 and the seal ring side passage 82d. Are connected to each other to introduce a part of the seal gas S supplied to the arc-shaped concave groove 81a from the branch portion 82d into the pocket pressure introduction space 91, that is, the pocket pressure which is the pressure in the static pressure generating groove 81. P is introduced into the pocket pressure introduction space 91. The downstream end of the pocket pressure introduction path 92 prevents the annular step 2f that prevents the third O-ring 94 from moving in the fourth O-ring direction and the movement of the fourth O-ring 95 in the third O-ring direction. A third O-ring 94 (second O-ring 11) is opened to the outer peripheral surface portion of the stationary sealing ring 5 in contact with the annular stepped portion 93.

  As shown in FIGS. 1 and 2, the pocket pressure receiving surface 93 is an annular surface formed in a portion of the stationary sealing ring 5 facing the pocket pressure introducing space 93, and the pressure in the pocket pressure introducing space 91 (pocket pressure). ) P acts to generate an axial thrust force that pushes the stationary seal ring 5 in a direction in which the sealed end faces 5a and 6a are separated from each other, that is, a second opening force Fo2 that opens the sealed end faces 5a and 6a. In this example, the pocket pressure receiving surface 93 connects the large-diameter portion with which the third O-ring 94 contacts with the small-diameter portion with which the fourth O-ring 95 contacts on the outer peripheral surface of the stationary seal ring 5. It is comprised by the annular | circular shaped surface orthogonal to. The area of the pocket pressure receiving surface 93 is set smaller than the area of the sealed end surfaces 5a and 6a so that the second opening force Fo2 is smaller than the first opening force Fo1 regardless of the size of the pocket pressure P. Has been.

  In this example, the mechanical seal M1 is formed in a cartridge type. That is, the rotation side component (the sleeve 4 and the rotary sealing ring 6 fixed thereto) Ma and the stationary side component (the seal case 2 and the stationary sealing ring 5 held by this) Mb are shown in FIG. As shown in the drawing, the set claw 15 attached to the flange body 2b of the seal case 2 with the attachment bolt 14 is engaged with the annular recess 4g formed in the fixing portion 4c of the sleeve 4, so that the assembly state of the mechanical seal M1 is the same. In this connection state, the mounting bolt 2d and the set screw 4f are operated so that the device housing 1 and the rotary shaft 3 can be incorporated or removed.

  In the static pressure non-contact mechanical seal M1 configured as described above, the first opening force Fo1 is generated by the first opening force generating means 8. That is, when the seal gas S is supplied from the case side passage 82b to the static pressure generation groove 81 through the communication space 82a and the sealing ring side passage 82c, the seal that has flowed out from the static pressure generation groove 81 to the sealed end faces 5a and 6a. The gas S generates a first opening force Fo1 that acts between the sealed end faces 5a and 6a in a direction to open the sealed end faces 5a and 6a. The first opening force Fo1 is due to the static pressure generated by the seal gas S that flows out between the sealed end faces 5a and 6a from the static pressure generating groove 81. This static pressure is the seal gas in the static pressure generating groove 81. Although the pressure is smaller than the pocket pressure P, which is the pressure, the pressure is higher than the pressure in both the regions H and L, so the seal gas S flows out from both the sealed end faces 5a and 6a to both the regions H and L.

  Simultaneously with the generation of the first opening force Fo1, the second opening force Fo2 is generated by the second opening force generating means 9. That is, the seal gas S supplied to the static pressure generating groove 81 (arc-shaped concave groove 81a) from the pocket pressure introduction path 92 connected to the downstream portion of the orifice 83 in the seal ring side passage 82c, that is, the branch portion 82d. The portion is introduced into the pocket pressure introduction space 91, and the same pressure (pocket pressure) P as the pressure in the static pressure generating groove 81 acts on the pocket pressure receiving surface 93 in the pocket pressure introduction space 91, and An axial thrust is generated in a direction that separates this from the rotary seal ring 6. This axial thrust is the second opening force Fo2 acting in the direction of opening the sealed end faces 5a, 6a. This second opening force Fo2 is obtained by the product of the pocket pressure P and the area of the pocket pressure receiving surface 91.

  On the other hand, the closing force Fc acting in the direction in which the sealed end faces 5 a and 6 a are brought closer is generated only by the spring 7. That is, in this example, the closing force Fc is obtained by the spring load Fc1.

  Therefore, the appropriate component in which the relative position (component relative position) in the axial direction between the rotary side component Ma such as the rotary seal ring 6 and the stationary side component Mb such as the stationary seal ring 5 is an appropriate component relative position. In the case of the relative position, the spring constant of the spring 7 and the pressure of the seal gas S (seal gas source pressure) supplied from the seal gas supply pipe 84 are set to the opening force Fo (the first opening force Fo1 and the second opening force Fo2). By setting so that the closing force Fc (spring load Fc1) and the closing force Fc (spring load Fc1) are balanced (Fo1 + Fo2 = Fc1), the sealed end faces 5a and 6a have an appropriate gap (generally, 5 to 15 μm) is relatively rotated in a non-contact state, and the regions H and L are well shielded and sealed in the relative rotation portions 5a and 6a. Hereinafter, the spring load Fc1 in the proper component relative position is referred to as “appropriate spring load”, and the pocket pressure P when the appropriate gap is maintained is referred to as “appropriate pocket pressure”.

  Incidentally, when the component relative position is deviated from the proper component relative position due to vibration of the rotating device and the gap between the sealed end faces 5a and 6a is changed from the proper gap, the spring length is hardly changed and the spring load Fc1 is changed. Is substantially the same as or close to the appropriate spring load, as described at the beginning, the clearance is automatically adjusted and restored to the proper clearance by the effect of the orifice 83. That is, when the gap between the sealing end surfaces 5a and 6a is larger than the appropriate gap, the pocket pressure P is lower than the appropriate pocket pressure, so the opening force Fo (= Fo1 + Fo2) is smaller than the closing force Fc (= Fc1). As a result, the gap between the sealed end faces 5a and 6a is changed to be small, and the gap is adjusted to an appropriate gap. On the contrary, when the gap between the sealed end faces 5a and 6a is smaller than the appropriate gap, the pocket pressure P becomes higher than the appropriate pocket pressure, so that the opening force Fo becomes larger than the closing force Fc, and as a result, the sealed end face 5a. , 6a is changed so as to be large, and the gap is adjusted to an appropriate gap. At this time, the pocket pressure P is also restored to the appropriate pocket pressure by adjusting the gap between the sealed end faces 5a and 6a to an appropriate gap.

  Thus, in the non-contact type mechanical seal M1, even when the relative position of the component deviates beyond the range that can be covered by the automatic adjustment by the orifice effect from the relative position of the proper component due to poor assembly accuracy or the like. As in the case where the component relative position is in the proper component relative position, a good non-contact sealing function is exhibited.

  That is, when the axial position of the rotation side component Ma is biased in the direction (forward) of pressing the stationary seal ring 5 than when the relative position of the proper component is relative, or the axial direction position of the stationary side component Mb is an appropriate configuration. When it is biased in the direction (rearward) in which the rotary seal ring 6 is pressed compared to the case of the relative position of the element, the spring 7 is compressed (the amount of compression of the spring 7 is smaller than that of the proper position of the relative position of the component). Increased), the spring load Fc1 will be larger than the appropriate spring load. When the spring load Fc1 (closing force Fc) increases from the appropriate spring load, the closing force Fc becomes larger than the opening force Fo, so the sealing end surfaces 5a and 6a are not opened until the appropriate gap is provided, and the static pressure generation groove 81 is not opened. Pressure (pocket pressure) P becomes higher than the appropriate pocket pressure. Along with this, the pressure (pocket pressure) P acting on the pocket pressure receiving surface 93 also increases, and the second opening force Fo2 increases. Therefore, both the closing force Fc and the opening force Fo are increased as compared with the case where they are in the proper component relative positions.

  Contrary to the above, the axial position of the rotating side component or the stationary side component is biased in the direction in which both sealing rings are separated from the case of the appropriate component relative position (rear side for the rotating side component, or When the stationary side component is biased forward), the spring 7 is expanded (the amount of compression of the spring 7 is reduced) as compared with the case where the stationary component is in the proper component relative position, and the spring load Fc1 is reduced. It will be less than the proper spring load. When the spring load Fc1 (closing force Fc) decreases from the appropriate spring load, the opening force Fo becomes larger than the closing force Fc, so that the gap between the sealed end faces 5a and 6a opens larger than the appropriate gap, and the static pressure generating groove 81 The internal pressure (pocket pressure) P becomes lower than the appropriate pocket pressure. Along with this, the pressure (pocket pressure) P acting on the pocket pressure receiving surface 93 decreases, and the second opening force Fo2 decreases. Therefore, both the closing force Fc and the opening force Fo are reduced as compared with the case where they are at the proper component relative positions.

  Thus, when the spring load Fc1 increases, the second opening force Fo2 increases accordingly, and when the spring load Fc1 decreases, the second opening force Fo2 also decreases accordingly. By appropriately setting the area of the pressure receiving surface 93, the difference between the increase amount of the spring load Fc1 and the increase amount of the second opening force Fo2, the decrease amount of the spring load Fc1 and the decrease amount of the second opening force Fo2, The difference can be made extremely small.

  Therefore, even when the component relative position deviates from the proper component relative position, the spring load Fc1 does not substantially increase or decrease due to the balance between the opening force Fo and the closing force Fc, and the spring load Fc1 increases or decreases. Even if it changes, the amount of change can be covered by automatic adjustment by the effect of the orifice 83. As a result, the gap between the sealing end faces 5a and 6a can be held at an appropriate gap, and a good non-contact sealing function can be exhibited as in the case of being at an appropriate component relative position.

  It should be noted that the present invention is not limited to the above-described embodiment, and can be appropriately improved and changed without departing from the basic principle of the present invention.

  For example, the pocket pressure introduction space 91 and the pocket pressure introduction path 92 can be configured as shown in FIG. 4, FIG. 5, or FIG.

  That is, in the static pressure non-contact type mechanical seal M2 shown in FIG. 4, the cylindrical holding body 2h protruding from the inner peripheral portion to the inner peripheral portion of the stationary seal ring 5 is provided on the flange body 2b of the seal case 2. A pair of front and rear first O-rings 10 and the second O-ring 10 are integrally formed and the stationary seal ring 5 is arranged between the outer peripheral surface and the inner peripheral surface of the case body 2a of the seal case 2 in parallel with a predetermined interval in the axial direction. A secondary seal state in which an O-ring 11 (third O-ring 94) is interposed and a fifth O-ring 16 is interposed between the inner peripheral surface of the stationary seal ring 5 and the outer peripheral surface of the holding body 2h of the seal case 2 By fitting between the case main body 2a and the holding body 2h, the seal case 2 is held so as to be movable in the axial direction, and a fourth O-ring 95 is formed on the inner peripheral portion of the case main body 2a of the seal case 2. Engagement with the annular O-ring groove 2i At the same time, the downstream end of the pocket pressure introduction path 92 connected to the portion (branch portion 82d) downstream of the orifice 83 in the seal ring side passage 82c is the outer peripheral surface of the stationary seal ring 5 and the fourth O-ring 95. Is opened between the pocket pressure receiving surface 93 and the O-ring groove 2i on the surface (seal surface) with which the ring contacts. In addition, the space (space in which the spring 7 and the drive pin 12 are disposed) formed between the axially opposed end surfaces of the stationary seal ring 5 and the flange body 2b of the seal case 2 is sealed with O-rings 10 and 16. However, the said space is open | released by the air | atmosphere area | region L which is an unsealed fluid area | region by the open hole 2k formed in the flange body 2b.

  Further, in the static pressure non-contact type mechanical seal M3 shown in FIG. 5, a cylindrical holding body 2j protruding from the inner peripheral portion to the inner peripheral portion of the stationary sealing ring 5 is provided on the flange body 2b of the seal case 2. A pair of front and rear first and second O-rings 10 are formed integrally, and the stationary seal ring 5 is arranged between the outer peripheral surface thereof and the inner peripheral surface of the case main body 2a of the seal case 2 in parallel with a predetermined interval in the axial direction. , 11 and a pair of front and rear third and fourth O-rings 94 arranged in parallel at a predetermined interval in the axial direction between the inner peripheral surface of the stationary seal ring 5 and the outer peripheral surface of the holding body 2j of the seal case 2. , 95 is fitted between the case body 2a and the holding body 2j in a secondary seal state, with the seal case 2 being held so as to be movable in the axial direction, and the inner peripheral surface of the stationary seal ring 5 is The small diameter surface 5d with which the third O-ring 94 contacts and the fourth O-ring The annular boundary surface between the small-diameter surface 5d and the large-diameter surface 5e is a pocket pressure-receiving surface 93, and the inner peripheral surface of the stationary seal ring 5 and the radial direction thereof. An annular space between the outer peripheral surface of the holding body 2j, which is a seal case portion facing the outer periphery, is formed as a pocket pressure introducing space 91 sealed by the third and fourth O-rings 94 and 95, and an orifice in the sealed-ring side passage 82c. 83, an annular O-ring groove formed on the outer peripheral surface of the pocket pressure receiving surface 93 and the third O-ring 94 at the downstream end of the pocket pressure introduction path 92 connected to the downstream portion (branch portion 82d). Are held in the pocket pressure introduction space 91.

  Further, in the static pressure type non-contact type mechanical seal M4 shown in FIG. 6, the orifice 83 is disposed in the case side passage 82b, and the pocket pressure introduction passage 92 is formed in the seal case 2 (case body 2a). . That is, the upstream end of the pocket pressure introduction path 92 is connected to a portion of the case side passage 82b downstream of the orifice 83, and the downstream end is the inner peripheral surface of the case body 2a and the fourth O-ring 95 contacts. The pocket pressure introduction space 91 that is sealed by the third O-ring 94 (second O-ring 11) and the fourth O-ring 95 is opened. The configuration of the non-contact type mechanical seals M2, M3, M4 shown in FIGS. 4 to 6 is the same as that of the non-contact type mechanical seal M1 shown in FIG. About the part corresponding to the structure of M1, the detailed description is abbreviate | omitted by using the same code | symbol as FIG. 1 in FIGS.

  Further, the static pressure type non-contact type mechanical seal of the present invention can be suitably used even under conditions in which the pressure in the in-machine gas region H fluctuates, but when used under such conditions, as shown in FIG. It is preferable to configure.

  That is, in the static pressure type non-contact type mechanical seal M5 shown in FIG. 7, the first and the second gaps between the base end portion 5f of the stationary seal ring 5 and the flange body 2b which is a seal case portion facing the axial direction thereof. A back pressure chamber 17 sealed by the fifth O-rings 10 and 16 is formed, and a back pressure introduction path 18 that communicates the sealed fluid region (in-machine gas region) H and the back pressure chamber 17 to the stationary seal ring 5. The thrust as the second closing force Fc2 acts on the base end portion 5f of the stationary seal ring 5 by the pressure of the in-machine gas (sealed fluid) introduced into the back pressure chamber 17 from the back pressure introduction passage 18. It is configured. According to this configuration, the closing force Fc is obtained by adding the second closing force Fc2 to the spring load Fc1 and changes according to the pressure fluctuation in the in-machine gas region H. Regardless of this, the opening force Fo (= Fo1 + Fo2) and the closing force Fc (= Fc1 + Fc2) are balanced, and the sealed end surfaces 5a and 6a are held in an appropriate non-contact state. Also in this static pressure type non-contact type mechanical seal M5, when the component relative position is deviated from the proper component relative position due to poor mounting accuracy or the like, and the spring load Fc1 is increased or decreased, as described above, As the second opening force Fo2 increases or decreases according to the increase or decrease of the spring load Fc1, the spring load Fc1 is substantially the same as or close to the appropriate spring load in terms of the balance of the opening and closing forces Fo and Fc. As a result, a non-contact sealing function equivalent to that in the proper component relative position is exhibited. Since the configuration of the non-contact type mechanical seal M4 shown in FIG. 7 is the same as that of the non-contact type mechanical seal M2 shown in FIG. 4 except for the points described above, the part corresponding to the configuration of the non-contact type mechanical seal M2 is shown in FIG. 7, the same reference numerals as those in FIG. 4 are used, and detailed description thereof is omitted.

1 Equipment housing (housing)
1a External end of device housing 2 Seal case 2a Case body 2b Flange body 2c Mounting bolt 2d Mounting bolt 2e Cylindrical protrusion 2f Annular step 2g Annular protrusion 2h Holding body 2i O-ring groove 2j Holding body 2k Opening hole 3 Rotating shaft 4 Sleeve 4a body 4b receiving part 4c fixing part 4d pressing part 4e connecting bolt 4f set screw 4g annular recess 5 stationary sealing ring 5a stationary side sealing end face 5b engaging recess 5c annular projection 5d small diameter surface 5e large diameter surface 5f of stationary sealing ring Base end 6 Rotating sealing ring 6a Rotating side sealing end face 6b Ceramic layer 6c Engaging recess 7 Spring 8 First opening force generating means 9 Second opening force generating means 10 First O ring 11 Second O ring 12 Drive pin 13 Drive Pin 14 Mounting bolt 15 Set claw 16 Fifth O-ring 17 Back pressure chamber 18 Pressure introducing passage 81 Static pressure generating groove 81a Arc-shaped concave groove 82 Seal gas supply passage 82a Communication space 82b Case side passage 82c Sealing ring side passage 82d Branching portion 83 Orifice 84 Seal gas supply pipe 91 Pocket pressure introduction space 92 Pocket pressure introduction passage 93 Pocket pressure receiving surface (annular step)
94 Third O-ring 95 Fourth O-ring H In-machine gas area (sealed fluid area)
L Atmospheric region (non-sealed fluid region)
M1 Hydrostatic non-contact mechanical seal M2 Static non-contact mechanical seal M3 Static non-contact mechanical seal M4 Static non-contact mechanical seal M5 Static non-contact mechanical seal

Ma rotating side component Ma stationary side component S sealing gas

Claims (8)

A rotary seal ring fixed to the rotary shaft, and a static pressure generating groove on the static seal end surface, which is the tip surface of the rotary seal ring that is held in the seal case so as to be movable in the axial direction and that faces the rotary seal end surface of the rotary seal ring. Static pressure generated through the formed stationary sealing ring, a spring interposed between the sealing case and the stationary sealing ring to press and bias the stationary sealing ring to the rotating sealing ring, and through the sealing case and the stationary sealing ring A seal gas supply path leading to the groove, and the seal gas is supplied from the seal gas supply path to the static pressure generating groove through the orifice disposed in the seal gas supply path, so that the stationary seal ring approaches the sealed end face By balancing the closing force that presses against the stationary sealing ring and the opening force that pushes the stationary sealing ring away from the sealed end face, the sealed end face of the both sealed rings is kept in a non-contact state and the non-sealed fluid region is non-contacted. Sealed fluid area and The non-contact type mechanical seal configured static pressure type to Le,
A pocket pressure introduction space sealed with a pair of O-rings is formed between the opposed peripheral surfaces of the stationary seal ring and the seal case, and the portion of the seal gas supply passage downstream from the orifice and the pocket pressure is formed in the stationary seal ring or the seal case. A pocket pressure introduction path that communicates with the introduction space is formed, and the static seal ring is separated from the rotary seal ring by the pressure in the pocket pressure introduction space acting on the stationary seal ring portion facing the pocket pressure introduction space. Forming a pocket pressure receiving surface that generates axial thrust to press in the direction, and the opening force is applied to the first opening force generated by the seal gas that flows between the sealed end surfaces from the static pressure generating groove. A hydrostatic non-contact mechanical seal, wherein the second opening force, which is the axial thrust generated by the surface, is weighted.   2. The static pressure type according to claim 1, wherein the orifice is disposed in a seal gas supply path portion formed in the stationary seal ring, and the pocket pressure introduction path is formed in the stationary seal ring. Non-contact mechanical seal.   2. The static pressure type non-circularity according to claim 1, wherein the orifice is disposed in a seal gas supply path portion formed in the seal case, and a pocket pressure introduction path is formed in the seal case. 3. Contact type mechanical seal.   A sealing gas supply path, which is an annular space formed between the opposed peripheral surfaces of the seal case and the stationary sealing ring, and a communication space sealed by the first and second O-rings loaded between the opposed peripheral surfaces; And a case side passage formed in the seal case and communicating with the communication space, and a seal ring side passage formed in the stationary seal ring and connecting the static pressure generating groove and the communication space. The hydrostatic non-contact mechanical seal according to any one of claims 1 to 3.   The pocket pressure introduction space is an annular space formed between the opposed peripheral surfaces of the seal case and the stationary sealing ring, and is sealed by the third and fourth O-rings loaded between the opposed peripheral surfaces. The hydrostatic non-contact type mechanical seal according to any one of claims 1 to 4, wherein   The communication space and the pocket pressure introduction space are formed between the inner peripheral surface of the seal case and the outer peripheral surface of the stationary sealing ring, and the second O-ring and the third O-ring are combined. The non-contact mechanical seal of the static pressure type according to claim 4 and 5.   6. The pocket pressure introducing space is formed between an inner peripheral surface of a stationary seal ring and an outer peripheral surface of a seal case portion radially opposed thereto. The hydrostatic non-contact mechanical seal to be described. A back pressure chamber sealed with an O-ring is formed between the base end portion of the stationary seal ring and the seal case portion facing the axial direction thereof, and the sealed fluid region and the back pressure chamber are formed in the stationary seal ring. A closed back pressure introduction path is formed, and axial closure thrust is generated by pressing the stationary sealing ring in the direction in which the sealed end faces approach each other by the pressure of the sealed fluid region introduced into the back pressure chamber. The hydrostatic non-contact type mechanical seal according to any one of claims 1 to 7, characterized in that the force is obtained by weighting the axial thrust to a spring.

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