JP2007232001A - Sealing structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively prevent abrasion of a slide contact part of a rubber end lip caused by increase in a pressure of sealed fluid in an early stage. <P>SOLUTION: A high pressure side pressure P<SB>1</SB>in a sealed fluid chamber 21 is introduced into an intermediate empty chamber 15 between a first seal part 51 and a second seal part 52 by a pressurizing means Y while reducing the pressure. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a sealing structure, and more particularly to a sealing structure used for sealing a high-pressure fluid such as a gas.

Conventionally, a sealing structure using a rotary shaft seal 31 as shown in FIG. 8 is used (see, for example, Patent Document 1), and the shape of the rubber lip 33 that contacts the surface of the rotary shaft 32 is different from that of the outer case 34. It was a cross-sectional shape extending in a substantially L shape toward the sealed fluid side C. That is, in FIG. 8 showing the conventional example, this rotary shaft seal 31 interposed between the rotary shaft 32 and the casing 35 is an outer member having an inner flange 36 at the end of the sealing fluid side (high pressure side) C. A case 34 is provided, and a rubber member 37 is integrated by adhesion or baking so as to surround the inner flange 36 of the outer case 34 and cover the outer peripheral surface of the outer case 34. A support fitting 38 having a substantially L-shaped cross section holds the rubber lip 33 from the low-pressure side E and the inner peripheral surface side (from the rear), and the lip tip 33a is formed in the outer case 34. It was at a position in the axial direction that was larger than the axial center orthogonal plane P ₀ including the flange 36 and away from the sealed fluid side (high pressure side) C. That is, the slidable contact portion S ₀ where the lip tip 33a contacts the rotating shaft 32 exists at a position in the axial direction far away from the axis orthogonal plane P ₀ including the inner flange 36, and the rubber lip 33 is It was a shape having a cylindrical extending portion 33c held by the cylindrical portion 38a of the metal fitting 38.

In a high pressure state where high pressure is applied to the sealed fluid chamber 39, the cylindrical extending portion 33c of the rubber lip 33 is compressed and deformed. However, since the support fitting 38 is present, the rubber loses the escape place and flows (moves) in the direction of arrow F. teeth), rubber lip end portion 33a is for receiving even pressure from the sealed fluid side C, the internal stress of the rubber is concentrated directly above the sliding portion S ₀ rubber loses flexibility. Contact pressure via the rubber of the area internal stress is concentrated, to generate pressed against the rotary shaft 32, a large contact pressure (pressure) P is generated in the sliding portion S _0. Then, it becomes difficult for the sealing fluid (the lubricating oil therein) to enter the interface between the rotating shaft 32 and the sliding contact portion S _{0 due} to the large pressure P, and the sliding contact portion S of the lip tip 33a. The wear of ₀ is promoted, and the wear advances (in a concave shape) so as to be removed in an extreme case, and external leakage of the fluid occurs.

Therefore, in order to solve such a problem, the present applicant has proposed a sealing structure as illustrated in FIG. 9 (see Patent Document 2). That is, as shown in FIG. 9, the rubber seal portion 40 having the sliding contact portion S ₀ that contacts the surface of the rotating shaft 32 and the metal outer case 34 are integrated, and the high pressure side C of the outer case 34 is obtained. Although the inner flange portion 36 of which is coated on the rubber sealing portion 40, on the axis-orthogonal face P ₀ including the inner brim portion 36, the sliding portion S ₀ of the sealing portion 40, a configuration which is disposed is there. In other words, in FIG. 9, the seal portion 40 has the axial center orthogonal wall portion 41, the axial center orthogonal wall portion 41 is formed along the axial center orthogonal surface P ₀ , and the sliding contact portion S ₀ is It is provided on the inner peripheral end face of this axial center orthogonal wall 41 to solve the problem of wear of the conventional structure of FIG. 8 due to the pressure of the sealed fluid chamber 39.
JP 2003-097723 A JP 2004-353765 A

Recently, there is a desire to further increase the pressure of the sealed fluid chamber 39, and even with the conventional sealing structure shown in FIG. 9, excessive contact surface pressure is applied to the sliding contact portion S ₀ with the rotating shaft 32. As a result, the lubricating oil does not enter the sliding contact portion S ₀ and premature wear occurs.
Therefore, the present invention solves such a problem, withstands higher pressure, reduces wear of the sliding contact portion with the rotating shaft, has a long life, and is particularly suitable for sealing high-pressure gas. The purpose is to provide.

  Therefore, the present invention provides a first seal portion having a first sliding contact portion disposed on the sealing fluid side so as to seal a fluid having a predetermined high-pressure side pressure and contacting the rotating shaft, and a low-pressure side having a predetermined low-pressure side pressure. And a second seal portion having a second sliding contact portion that contacts the rotating shaft so as to form an intermediate space between the first seal portion and the back surface of the first seal portion. In this case, there is provided pressurizing means for increasing the pressure in the intermediate chamber to an intermediate pressure higher than the low pressure side pressure and lower than the high pressure side pressure.

The pressurizing means has a communication passage that introduces the high-pressure side pressure of the sealed fluid chamber while reducing the pressure in the intermediate vacant chamber.
Further, a rotary shaft seal interposed between the housing and the rotary shaft is provided, the rotary shaft seal has an outer case integrated with the first seal portion, and is integrally formed on the outer peripheral surface of the outer case. And the axially communicating portion formed between the outer peripheral surface of the cylindrical portion covering portion in close contact with the housing and the housing, and the shaft penetrating the outer case and the cylindrical portion covering portion in the radial direction. The communication path is configured with a small hole that connects the central communication portion and the intermediate vacancy.
The pressurizing means includes a flow path that connects and connects the sealed fluid chamber and the intermediate empty chamber, and a pressure reducing valve interposed in the flow path, and reduces the high pressure side pressure while reducing the intermediate pressure. It is configured to be introduced into the room.

In addition, the cross-sectional shape of the tip lip including the first sliding contact portion of the first seal portion protrudes from the back so as to be lifted radially outward so as to receive the intermediate pressure and reduce the rotating shaft contact surface pressure. Has a part.
Further, the cross-sectional shape of the tip lip including the first sliding contact portion of the first seal portion receives the intermediate pressure and the high pressure side pressure, respectively, and radially outwards so as to reduce the rotating shaft contact surface pressure. It is a cross-sectional Ginkgo biloba type that has a rear protrusion and a high-pressure protrusion to lift.
Furthermore, the first seal portion has a shape having a notch at the root portion of the tip lip.

  Even under severe operating conditions where the pressure of the sealing fluid (high pressure side) is high, abnormal (early) wear does not occur in the sliding contact portion with the rotating shaft, and stable and excellent sealing performance is exhibited. In particular, it is suitable for sealing high-pressure gas, and even if the pressure (high-pressure side) of the sealing fluid increases, the intermediate pressure acting on the back surface of the first seal portion correspondingly increases the excessive deformation of the first seal portion. Can be prevented and good sealing performance (sealing performance) can be exhibited over a long period of time.

Hereinafter, the present invention will be described in detail based on the illustrated embodiment.
1 and 2 show an embodiment of the present invention. FIG. 1 is a cross-sectional view of the main part, and FIG. 2 is an enlarged cross-sectional view of the main part of FIG. The sealing structure shown in FIGS. 1 and 2 seals, for example, the fluid of the high-pressure refrigerant on the sealed fluid chamber 21 side. In FIG. 1, only the upper half of the cross section is shown, and the solid line indicates the rotation. The shaft seal 16 is shown in a free state (non-mounted state), and the rotary shaft seal 16 is interposed between the rotary shaft 20 and the housing 22 indicated by a two-dot chain line to constitute a sealing structure. When the rotary shaft seal 16 is interposed between the housing 22 and the rotary shaft 20, each part is elastically deformed.

  In FIG. 1, reference numeral 1 denotes a metal outer case having inner flange portions 2 and 3, and the outer peripheral surface of the cylindrical wall portion 4 of the outer case 1 and the sealing fluid side C (sealing fluid chamber 21 side). A rubber seal member 5 is integrally fixed and held on both the front and rear surfaces of the inner collar portion 2 by adhesion, welding, baking, or the like. This seal member 5 has an axial center orthogonal wall portion 5b provided in a direction orthogonal to the axis L, and the spiral groove 6 is located closer to the anti-sealing fluid side (low pressure side) E than the axis orthogonal wall portion 5b. A sealing element 7 is provided. The material of the seal element 7 is preferably a fluororesin such as PTFE. Reference numeral 9 denotes a first inner case, which has an L-shaped cross section and includes a cylindrical portion 9a and an axial center orthogonal portion 9b. The cylindrical portion 9a is fitted so as to be in contact with the inner peripheral surface of the outer case 1, and the shaft The orthogonal center portion 9b serves as a support fitting that supports the axial center orthogonal wall portion 5b in contact with the back surface. The first inner case 9, the second inner case 10, the seal element 7, and the third inner case 11 are sequentially held and fixed between the inner flange portions 2 and 3.

The rubber seal member 5 that is integrally fixed to the outer case 1 has an outer peripheral surface in a corrugated shape for elastically contacting the inner peripheral surface 22a of the housing 22 to form a sealing action (in a free state). The inner cover portion having a U-shaped cross section that covers both the front and rear surfaces of the inner cover portion 2 and the inner cover portion 2 is located near the outer periphery and extends in the inner diameter direction, and the first sliding contact portion 23 is formed on the inner peripheral edge. And the axial center orthogonal wall portion 5b.
In other words, the first slidable contact portion 23 in which the inner peripheral edge of the axis-center orthogonal wall portion 5b orthogonal to the axis L of the rotation shaft 20 (rotation shaft seal 16) has a roundness (the rounded portion) is formed. The orthogonal shaft center orthogonal portion 9b supports the shaft center orthogonal wall portion 5b from the low pressure side E --- the anti-sealing fluid side--. Moreover, the rubber axial center orthogonal wall portion 5b has an annular concave groove-like cutout recess 59 on the back side corresponding to the axial center orthogonal portion 9b (made of a metal plate).

Then, it will be described from another point of view the structure of FIG. 1 (structure), the contacts are arranged at the sealed fluid side C to seal a predetermined high side pressure P ₁ (sealed) fluid to the rotary shaft 20 A first seal portion 51 having one sliding contact portion 23 and a second seal portion 52 having a second sliding contact portion 25 disposed on the low pressure side E of the predetermined low pressure side pressure P ₃ and contacting the rotary shaft 20. The latter (second seal portion 52) corresponds to the seal element 7 described above. A spiral groove 6 is formed in the second slidable contact portion 25, and fluid is returned to the intermediate vacant space 15 by a pumping action by sliding contact with the rotating shaft 20 during rotation.
Thus, the intermediate vacant space 15 is formed (partition) between the back surface of the first seal portion 51 and the second seal portion 52.

In the present invention, the pressurizing means Y for increasing the pressure P ₂ in the intermediate empty space 15 to the intermediate pressure P ₂ higher than the low pressure side pressure P ₃ and lower than the high pressure side pressure P ₁ is provided. Have. That is, the pressure P ₂ in the intermediate vacant space 15 is increased (pressurized) by the pressurizing means Y so that the relational expression P ₃ <P ₂ <P ₁ is satisfied.

1 and 2, the pressurizing means Y is constituted by a communication passage 12 that introduces the high pressure side pressure P ₁ of the sealed fluid chamber 21 while reducing the pressure to the intermediate empty chamber 15. 1 and 2, a communication passage 12 is formed in the rotary shaft seal 16 itself. More specifically, in the rotary shaft seal 16, the cylindrical portion covering portion 5a is integrally formed on the outer peripheral surface of the outer case 1 integrated with the first seal portion 51 and is in close contact with the inner peripheral surface 22a of the housing 22. An axial communication portion 13 is formed between the outer peripheral surface 5 c and the inner peripheral surface 22 a of the housing 22. That is, in FIGS. 1 and 2, in the direction parallel to the axis L, one (or two or more) narrow grooves 17 are provided in the outer peripheral surface 5 c of the cylindrical portion covering portion 5 a so as to form a housing 22. The axial direction communication portion 13 is formed in a state where it is mounted on. Although not shown in the figure, it is also possible to form one axially narrow groove (or two or more) in the axial direction on the inner peripheral surface 22a of the housing 22 to form the axial communication part 13. (Not shown).

Furthermore, the cylindrical wall portion 4 of the outer case 1, the cylindrical portion covering portion 5 a, and the cylindrical portion 9 a of the first inner case 9 are penetrated in the radial direction so that the axial communication portion 13 and the intermediate vacant space 15 are penetrated. Are formed so as to communicate with each other.
The communication passage 12 as the pressurizing means Y is constituted by such an axial communication portion 13 and a small hole 18 in the radial direction. Of course, the axial direction communication portion 13 is provided in a range from the intermediate position in the axial direction of the cylindrical portion covering portion 5a to the high pressure side C.

Next, in another embodiment shown in FIG. 3, in the range between the small hole 18 and the low pressure side (anti-sealing fluid side) E (see FIG. 1), the outer periphery of the corrugated corrugated portion of the cylindrical portion covering portion 5a. The outer diameter dimension of the surface 5c is set to be larger than the inner diameter dimension of the inner peripheral surface 22a of the housing 22, and in the mounted state, the cylindrical portion covering portion 5a is elastically compressed and elastically applied to the inner peripheral surface 22a. In the range between the small hole 18 and the high pressure side (sealing fluid side) C, the outer diameter of the outer peripheral surface 5c of the cylindrical portion covering portion 5a is set to the housing. set the inner peripheral surface 22a inner diameter and the same or slightly large, but if high-pressure side pressure P ₁ is low is a closed shape, if higher than the predetermined value, in response to the pressure P ₁ housing A cylindrical thin passage (gap) is formed between the inner peripheral surface 22a and the high pressure side pressure P ₁ is introduced into the intermediate vacant space 15 while being reduced. Entered.
Thus, in FIG. 3, the pressurizing means Y is connected in the axial direction consisting of a thin cylindrical passage (gap) that introduces the high pressure side pressure P ₁ of the sealed fluid chamber 21 while reducing the pressure to the intermediate vacant chamber 15. The communication path 12 includes a portion 13 and a small hole 18 in the radial direction (similar to FIG. 2).

Next, in another embodiment shown in FIG. 4, in the range between the small hole 18 and the low pressure side E (see FIG. 1), the outer peripheral surface 5c of the cylindrical portion covering portion 5a is the housing inner peripheral surface 22a. 1, 2, and 3 are the same as in FIGS. 1, 2, and 3, but on the other hand, in the range between the small hole 18 and the high pressure side C, there is one (Or a plurality of) protruding ridges 14 that act as a valve are formed in a protruding shape on the outer peripheral surface 5c of the cylindrical portion covering portion 5a so that the protruding ridges 14 can be elastically pressed against the inner peripheral surface 22a of the housing. . The portions other than the ridges 14 are formed to have an outer diameter slightly smaller than the inner diameter of the housing inner peripheral surface 22a, so that the high pressure side pressure P ₁ acts on the ridges 14 and the high pressure side pressure P ₁ is low. In this case, the top portion (outer peripheral edge) of the protrusion 14 is elastically pressed against the inner peripheral surface 22a of the housing to close the fluid, but the high pressure side pressure P ₁ rises above a predetermined value. In response to the pressure P ₁ , the fluid flows between the housing inner peripheral surface 22a as shown by the arrow B in FIG. The communication path 12 is configured such that the high pressure side pressure P ₁ is introduced from the sealed fluid chamber 21 into the intermediate vacant space 15 (through the small hole 18) while being reduced.
Although not shown in the figure, it is also preferable to adopt a configuration in which FIGS. 2 and 4 are combined. That is, one or a plurality of grooves are provided in the axial direction on the outer peripheral surface 5c of the cylindrical covering portion 5a, and in the middle of the grooves, swing in the direction of arrow B as illustrated in FIG. It is also possible to arrange a protrusion (projection piece) 14 as a valve that can be opened.

Next, FIG. 5 shows still another embodiment. That is, as the pressurizing means Y, the communication passage 12 as shown in FIGS. 1 to 4 is omitted, and instead, in the mounted state in which the rotating shaft seal 16 is mounted between the housing 22 and the rotating shaft 20, In this configuration, pressurized fluid is introduced from the low pressure side E through the seal element 7 (second seal portion 52) as indicated by an arrow.
However, the intermediate pressure P ₂ is equal to or lower than the pressure resistance of the seal element 7 (second seal portion 52).

In still another embodiment shown in FIG. 7, the pressurizing means Y includes a flow path 19 that connects the sealed fluid chamber 21 and the intermediate vacant chamber 15 with, for example, a pipe or a hole in the housing 22. Further, a pressure reducing valve 26 is provided in the flow path 19 to introduce the high pressure side pressure P ₁ into the intermediate vacant space 15 while reducing the pressure. In FIG. 7, a small hole 18 similar to that of the above-described embodiment is used as a part of the channel 19. According to the embodiment of FIG. 7, there is an advantage that the intermediate pressure P ₂ of the intermediate empty space 15 can be stably set (adjusted) to an appropriate value, and the first seal portion 51 and the second seal portion 52 are appropriate. The contact surface pressure can be brought into contact with the rotating shaft 20, and the life and durability are reliably extended.

At a main part enlarged sectional view shown in FIG. 6 (a) ~ (f) , as described above, so that the intermediate pressure P ₂ of the intermediate air chamber 15 becomes higher than the low-pressure side pressure P ₃ pressurized Various examples of the first seal portion 51 that are pressurized by the pressure means Y and are suitable for effectively using the pressurized intermediate pressure P ₂ will be listed.
At a respective embodiment of FIG. 6 (a) ~ (f) , the cross-sectional shape of the end lip 53 including a first sliding portion 23 of the first seal portion 51, the rotary shaft contacting the intermediate pressure P ₂ and the pressure-receiving A rear protrusion 54 is provided so as to lift radially outward so as to reduce the surface pressure.

More specifically, the cross-sectional shape of the front end lip 53 including the first sliding contact portion 23 of the first seal portion 51 is such that the back surface protruding portion 54 that receives the intermediate pressure P ₂ and the high pressure side pressure P ₁ respectively. The high-pressure protrusion 55 has a cross-sectional ginko leaf type (repellent type).
In other words, the rear protrusion 54 has an arc shape on the inner peripheral surface side, and the outer peripheral surface side protrudes into the intermediate cavity 15 in a substantially triangular shape in cross section, and the high pressure protrusion 55 has an inner peripheral surface. The side is arcuate and the outer peripheral surface side is a straight line with a gradient and protrudes to the high-pressure side (sealing fluid side) C in a triangular cross section. The portion of the high-pressure protrusion 55 is the same as that shown in FIG. It can be said that it is the same cross-sectional shape as FIG. 1, FIG. 5, FIG. 7 which showed embodiment.
Further, in FIGS. 6A to 6F, the inner peripheral edge of the axial center orthogonal wall portion 5b of the rubber seal member 5 is formed in a cross-sectional ginkgo leaf shape (repellent shape), and the intermediate pressure P ₂ and The high pressure side pressure P ₁ is received, and the first sliding contact portion 23 is lifted radially outward so as to reduce the contact surface pressure at which it contacts the rotating shaft 20.

FIG. 6A shows a ginkgo-leaf type cross-sectional shape in which a rear protrusion 54 and a high-pressure protrusion 55 protrude in a substantially symmetrical manner. As shown by a two-dot chain line 56 in FIG. 6 (a), the high-pressure protrusion 55 is omitted (so to speak, the tip lip 53 shown in FIG. 1, FIG. 5 and FIG. ) it is also preferred to increase the effect of the action lifting by the intermediate pressure P _2.
Next, in FIG. 6 (b), a notch recess 58, 59 is formed in the root portion 57 of the tip lip 53 to facilitate elastic deformation of the tip lip 53 in the radial outward direction (at the time of pressure reception). The contact surface pressure with 20 is further reduced.
In FIG. 6C, it is also preferable that the high-pressure side notch recess 58 and the intermediate pressure-side notch recess 59 have different radial positions. In particular, by corresponding the cut recess 59 in the inner edge of the axis-orthogonal portion 9b of the first inner case 9, by increasing the back projection 54, the upward force has in the radial outward by the intermediate pressure P ₂ It is getting bigger.

Further, At a FIG. 6 (d), the back to form a notch recess 59 only (intermediate check 15) side, cleverly balance the magnitude difference between the pressure P ₁ and the pressure P _2, effectively radial outside The contact surface pressure of the first slidable contact portion 23 to the rotating shaft 20 is reduced by generating a lifting force.
Further, in FIG. 6 (e), a large notch recess 59 is provided on the back surface (intermediate empty space 15) side, and a small notch recess 58 is provided on the sealing fluid side C.

Point O ₁ indicates the center of rocking deformation of the tip lip 53 due to the high-pressure side pressure P ₁ , while point O ₂ is the center point of the line segment connecting the bottoms of the front and rear recesses 58 and 59, ie, m , M divided into two equal parts, indicating the center of rocking deformation of the tip lip 53 due to the intermediate pressure P ₂ , and this point O ₂ is located radially outward from the point O ₁ By being present, the influence of the bending moment of the back protrusion 54 on which the intermediate pressure P ₂ acts is greater than the influence of the bending moment of the high pressure protrusion 55 on which the high pressure side pressure P ₁ acts, and the pressure P ₂ and cleverly balance the difference in pressure in the pressure P _1, it is effective to lift the lip 53 in the radial outward reduces the contact surface pressure between the rotary shaft 20. In FIG. 6 (e), the cross-sectional area of the back protrusion 54 is made larger than that of the high-pressure protrusion 55 (with different sizes) so as to maintain a better balance.

Next, in the embodiment shown in FIG. 6 (f), the first seal portion 51 is held in a sandwiched manner by two metal fittings (metal plate pieces) 60 and 61 inside and outside. . Specifically, the bent end pieces 60a and 61a corresponding to the outer diameter side inclined surfaces 53a and 53b of the ginkgo-leaf type tip lip 53 are formed on the metal plate pieces (metal fittings) 60 and 61, respectively. When fluid pressure acts as shown by arrows P ₁ and P _{2 in} FIG. 6 (f), the tip lip 53 is reliably and stably deformed as shown by a two-dot chain line. In this way, the shape after elastic deformation (in the pressure-receiving state) is regulated, deformed radially outward while maintaining a stable posture, the contact surface pressure with the rotating shaft 20 is reliably reduced, and early wear and Abnormal wear can be prevented and durability can be significantly improved. The metal plate piece (metal fitting) 60 can be configured by the first inner case 9 of FIG. 1, while the metal plate piece (metal fitting) 61 is an inner flange portion 2 of the outer case 1 of FIG. It is also possible to stretch the film in a bent shape in the inner diameter direction. Further, FIG. 6 (f) shows a case where the notch recesses 58 and 59 are provided in the root portion 57, which further facilitates the elastic deformation of the tip lip 53 radially outward.

  In addition, the above embodiments (examples) are combined with each other, for example, those shown in FIGS. 6 (a) to 6 (f) are replaced with those shown in FIGS. 5 and FIG. 7 are desirable in order to more reliably achieve the intended purpose.

  In addition to the above-described embodiments, the present invention can be freely modified as follows. That is, as the second seal portion 52, a seal portion having a rubber lip is used instead of the illustrated seal element 7, or another rubber is used in front (high pressure side) or rear (low pressure side) of the seal element 7. It is also free to attach a sealing material having a lip or to add another sealing element.

As described above, the present invention includes a first seal portion 51 having a first sliding contact portion 23 disposed on the sealing fluid side C so as to seal a fluid having a predetermined high-pressure side pressure P ₁ and contacting the rotary shaft 20. And a second sliding contact portion 25 which is disposed on the low pressure side E of the predetermined low pressure side pressure P ₃ and contacts the rotary shaft 20 so as to form an intermediate space 15 between the first seal portion 51 and the back surface. and a second seal portion 52, at a sealing structure with higher than the low side pressure P _3, and the pressure P ₂ of the intermediate air chamber 15 to the intermediate pressure P ₂ lower than the high-pressure side pressure P ₁ Since the pressurizing means Y for increasing the pressure is provided, even if the high pressure side pressure P ₁ gradually increases due to recent demand, the first seal portion 51 has a so-called difference between the high pressure side pressure P ₁ and the intermediate pressure P _2. It acts as a small pressure corresponding to the pressure, and can cope with a sufficiently high pressure. In particular, the first sliding contact of the first seal portion 51 that contacts the rotating shaft 20 23 can be prevented effectively that the premature wear and abnormal wear occurs, durable, it is suitable as a sealing of the high pressure gas such as refrigerant.

Further, the pressurizing means Y is constituted by the communication passage 12 that introduces the high pressure side pressure P ₁ of the sealed fluid chamber 21 while reducing the pressure to the intermediate empty chamber 15, so that the structure becomes simple and the high pressure side pressure P ₁ varies. The intermediate pressure P ₂ in the intermediate vacant space 15 can be applied to the first seal portion 51 in a prompt and reliable manner.

The rotary shaft seal 16 is interposed between the housing 22 and the rotary shaft 20, and the rotary shaft seal 16 has an outer case 1 integrated with the first seal portion 51. The outer peripheral surface 5c of the cylindrical portion covering portion 5a that is integrally formed on the surface and in close contact with the housing 22, the axial communication portion 13 formed between the housing 22, and the outer case 1 and the cylindrical portion covering portion 5a The communication path 12 is configured with a small hole 18 that penetrates in the direction and connects the axial direction communication portion 13 and the intermediate vacant space 15, so that the structure is simple, easy to manufacture, and inexpensive. There is no increase, and the intermediate pressure P ₂ in the intermediate vacant space 15 can be applied to the first seal portion 51 in a quick and reliable manner corresponding to the fluctuation of the high pressure side pressure P ₁ .

The pressure means Y has a passage 19 for connecting communicating the sealed fluid chamber 21 and the intermediate air chamber 15, and a pressure reducing valve 26 which is interposed in the flow path 19, comprises a high-pressure side pressure P ₁ Since the pressure is reduced and introduced into the intermediate vacant space 15, the intermediate pressure P ₂ can be controlled with high accuracy by the pressure reducing valve 26, and the wear of the first sliding contact portion 23 can be more stably prevented, resulting in a long life. The sealed structure is obtained.

Further, as the cross-sectional shape of the end lip 53 including a first sliding portion 23 of the first seal portion 51, go up has an intermediate pressure P ₂ in the radial outward so as to lower the pressure to the rotation axis contact surface pressure Since the rear projecting portion 54 is provided, the wear of the first sliding contact portion 23 can be further prevented, and the life is remarkably extended.
Further, the cross-sectional shape of the tip lip 53 including the first sliding contact portion 23 of the first seal portion 51 receives the intermediate pressure P ₂ and the high pressure side pressure P ₁ , respectively, so as to reduce the rotating shaft contact surface pressure. Since it has a ginko-leaf type cross section with a rear projection 54 and a high-pressure projection 55 so that it can be lifted radially outward, it slides on the rotary shaft 20 with an appropriate low contact surface pressure while maintaining a stable posture to ensure wear. This can improve durability.
Further, since the first seal portion 51 has notches 58 and 59 in the root portion 57 of the tip lip 53, the elastic deformation to the radial outer side is further facilitated, and the contact surface pressure with the rotary shaft 20 is reduced. It is reliably reduced and further durability can be obtained.

It is principal part sectional drawing which shows one Embodiment of this invention. It is a principal part expanded sectional view. It is a principal part expanded sectional view which shows other embodiment. It is a principal part expanded sectional view which shows another embodiment. It is a principal part expanded sectional view which shows other embodiment. It is a principal part expanded sectional view which shows various examples of a front-end | tip lip and its vicinity. It is structure explanatory drawing which shows another embodiment. It is sectional drawing which shows a prior art example. It is sectional drawing which shows another prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Outer case 5 Seal member 5a Cylindrical part coating | coated part 5c Outer peripheral surface
12 passage
13 Axial communication section
15 Intermediate vacancy
16 Rotating shaft seal
18 small holes
19 Flow path
20 axis of rotation
22 Housing
23 First sliding contact
25 Second sliding contact
26 Pressure reducing valve
51 First seal
52 Second seal
53 Tip lip
54 Rear protrusion
55 High pressure protrusion
57 Root
58, 59 Notch recess C Sealed fluid side (high pressure side)
E Low pressure side (anti-sealing fluid side)
P ₁ High pressure side P ₂ Intermediate pressure Y Pressurizing means P ₀

Claims (7)

A first sealing portion (51) having a first sliding contact portion (23) disposed on the sealing fluid side (C) and in contact with the rotating shaft (20) so as to seal a fluid having a predetermined high pressure side pressure (P ₁ ). ) And the low pressure side (E) of the predetermined low pressure side pressure (P ₃ ) and the rotating shaft so as to form an intermediate vacant space (15) between the back surface of the first seal portion (51). In a sealing structure including a second seal portion (52) having a second sliding contact portion (25) in contact with (20),
Higher than the low-pressure side pressure (P _3), and pressurized to increase the pressure (P ₂₎ of the intermediate check (15) in the intermediate pressure (P ₂₎ is lower than the high-pressure side pressure (P ₁₎ A sealing structure comprising a pressure means (Y). The pressure means (Y) is the high-pressure side pressure (P ₁₎ of claim 1, wherein constructed with a communication passage (12) for introducing while reduced to the intermediate check (15) of the sealing fluid chamber (21) Sealing structure.   An outer case comprising a rotary shaft seal (16) interposed between the housing (22) and the rotary shaft (20), wherein the rotary shaft seal (16) is integrated with the first seal portion (51). An outer peripheral surface (5c) of a cylindrical covering portion (5a) that is integrally formed on the outer peripheral surface of the outer case (1) and is in close contact with the housing (22), and the housing (22). The axial communication part (13) formed between the outer case (1) and the cylindrical part covering part (5a) in the radial direction, and the intermediate communication part (13) and the intermediate part. The sealing structure according to claim 2, wherein the communication path (12) is configured by a small hole (18) that communicates with the vacant chamber (15). The pressurizing means (Y) includes a flow path (19) communicating with the sealed fluid chamber (21) and the intermediate empty chamber (15), and a pressure reducing valve ( 26), and is configured to be introduced into the intermediate vacant space (15) while reducing the high-pressure side pressure (P ₁ ). The cross-sectional shape of the tip lip (53) including the first sliding contact portion (23) of the first seal portion (51) receives the intermediate pressure (P ₂ ) so as to reduce the rotating shaft contact surface pressure. The sealing structure according to claim 1, 2, 3, or 4, further comprising a rear protrusion (54) so as to be lifted radially outward. The cross-sectional shape of the tip lip (53) including the first sliding contact portion (23) of the first seal portion (51) receives the intermediate pressure (P ₂ ) and the high pressure side pressure (P ₁ ), respectively. 5. A cross-sectional ginko leaf type having a rear protrusion (54) and a high-pressure protrusion (55) so as to be lifted radially outward so as to reduce the rotating shaft contact surface pressure. The sealing structure as described.   The sealing structure according to claim 6, wherein the first seal part (51) has a notch recess (58) (59) in a root part (57) of the tip lip (53).

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