JP2005273691A - Shaft sealing structure by seal lip - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To maintain necessary sealing performance and lubricating action over a long period of time in a shaft sealing structure by a seal lip 11. <P>SOLUTION: An inner circumference part 112 of the seal lip 11 made of elastically deformable material is put slidably close to an outer circumference surface of a rotary shaft 2. The outer circumference surface 21a of a sealed part 21 positioned on an inner circumference of the seal lip 11 of the outer circumference surfaces of the rotary shaft 2 forms a cylindrical surface eccentric to a rotation center O<SB>22</SB>. A spiral groove 112a extending in a direction pumping fluid to a sealed space side by rotation of the rotary shaft 2 is formed on the inner circumference surface of the seal lip 11. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a shaft sealing structure in which a shaft periphery is sealed by a seal lip in close contact with an outer peripheral surface of a rotating shaft.

  The sealing device that seals the periphery of the rotating shaft is molded with a low-friction synthetic resin material such as PTFE (polytetrafluoroethylene), which is superior in heat resistance and wear resistance and has a low friction coefficient compared to rubber-like elastic materials. Some have a sealed lip. However, a synthetic resin material such as PTFE is less elastic than a rubber-like elastic material, and has less followability to the eccentric motion (axial runout) of the rotating shaft. Therefore, compared with a seal lip made of a rubber-like elastic material. There is a problem that leakage is likely to occur.

Therefore, for the purpose of compensating the eccentric followability of the synthetic resin seal lip and improving the sealing performance by the screw pump action, for example, as described in Patent Document 1 below, this type of synthetic resin seal is used. It is known that the lip is provided with a spiral groove.
JP 2002-323137 A

  However, such a seal lip having a spiral groove also has a required sealing performance and lubrication due to the screw pump action if the groove cross-sectional area is reduced due to wear over time of the inner peripheral surface due to sliding with the rotating shaft. The effect could not be obtained, leading to the occurrence of leakage.

  The present invention has been made in view of the above points, and a technical problem thereof is to make it possible to maintain required sealing performance and lubricating action over a long period of time in a shaft seal structure using a seal lip. .

  The technical problem described above can be effectively solved by the present invention. That is, in the shaft seal structure with the seal lip according to the first aspect of the invention, the inner peripheral portion of the seal lip made of an elastically deformable material is slidably in close contact with the outer peripheral surface of the rotary shaft. Among the outer peripheral surfaces, the outer peripheral surface of the sealed portion located on the inner periphery of the seal lip forms a cylindrical surface that is eccentric with respect to the rotation center.

  Further, in the shaft seal structure with the seal lip according to the invention of claim 2, the inner peripheral portion of the seal lip made of an elastically deformable material is slidably in close contact with the outer peripheral surface of the rotary shaft. Of the outer peripheral surface of the sealing lip, the cross-sectional shape obtained by cutting the outer peripheral surface of the sealed portion with a plane orthogonal to the axis is an ellipse, and the rotation center of the rotating shaft is a short of the ellipse. It passes through the intersection of diameter and major axis.

  According to a third aspect of the present invention, the shaft sealing structure with the seal lip extends on the inner peripheral surface of the seal lip in the direction of pumping fluid to the sealed space side by the rotation of the rotary shaft. A spiral groove is formed.

  The shaft seal structure with a seal lip according to the invention of claim 4 is the structure according to claim 1 or 2, wherein a plurality of grooves continuous in the circumferential direction are formed on the inner peripheral surface of the seal lip. .

  The shaft seal structure with a seal lip according to the invention of claim 5 is the structure according to claim 3 or 4, wherein the angle formed by the rising surface near the sealed space of the groove with respect to the outer peripheral surface of the rotation shaft is the rotation shaft. This is smaller than the angle formed by the rising surface near the anti-sealing space of the groove with respect to the outer peripheral surface.

  According to the shaft seal structure with the seal lip according to the first aspect of the invention, the outer peripheral surface of the sealed portion of the rotary shaft located on the inner periphery of the seal lip forms a cylindrical surface eccentric with respect to the rotation center. The parts where the surface pressure of the seal lip with respect to the shaft is small and large move in the circumferential direction as it rotates, generating dynamic pressure in the fluid around the shaft, resulting in good lubrication and reduced wear on the seal lip In addition, twisting of the seal lip due to sliding torque can be effectively prevented.

  According to the shaft seal structure with the seal lip according to the invention of claim 2, the cross-sectional shape obtained by cutting the outer peripheral surface of the sealed portion of the rotating shaft located on the inner periphery of the seal lip with a plane perpendicular to the axis is an ellipse. The rotation center of the rotating shaft passes through the intersection point of the minor axis and the major axis of the ellipse, so that the portion where the surface pressure of the seal lip with respect to the rotating shaft is small and large is moved in the circumferential direction with rotation. In addition, since dynamic pressure is generated in the fluid around the shaft, good lubrication is obtained, wear of the seal lip is reduced, and vibration of the rotating shaft due to rotation does not occur, and sealing by sliding torque occurs. Lip twisting can be effectively prevented.

  According to the shaft seal structure with the seal lip according to the invention of claim 3, the screw pump effect by the spiral groove formed on the inner peripheral surface of the seal lip is large with the portion where the surface pressure of the seal lip with respect to the rotating shaft is small. Since the height is increased by the movement of the portion in the circumferential direction, the sealing performance can be improved.

  According to the shaft seal structure with the seal lip according to the invention of claim 4, the portion in which the surface pressure of the seal lip with respect to the rotating shaft is small and the portion with the large fluid are contained in the spiral groove formed on the inner peripheral surface of the seal lip. Since the dynamic pressure is generated by the movement in the circumferential direction, lubrication can be promoted and wear of the seal lip can be reduced.

  According to the shaft seal structure with the seal lip according to the invention of claim 5, due to the dynamic pressure generated in the fluid in the groove, the fluid slides from the rising surface near the sealed space having a small angle with respect to the outer peripheral surface of the rotating shaft. Since it becomes easy to intervene as a lubricating film on the surface, the lubricating effect can be further enhanced.

  Hereinafter, a preferred embodiment of a shaft seal structure with a seal lip according to the present invention will be described with reference to the drawings. FIG. 1 is a half sectional view showing a shaft sealing structure according to the first embodiment by cutting along a plane passing through the axis, and FIG. 2 is a schematic perspective view showing the shape of the rotating shaft in the first embodiment. 3 is an explanatory view showing the behavior of the rotating shaft in a cross section orthogonal to the shaft center, and FIG. 4 is a partial half view showing the behavior of the seal lip along with the behavior of the rotating shaft cut along a plane passing through the shaft center. Sectional drawing and FIG. 5 are perspective views which show the eccentric sleeve as a modification of a 1st form.

  First, in FIG. 1, reference numeral 1 is a sealing device having a seal lip 11 slidably in contact with an outer peripheral surface 2 a of a rotating shaft 2. The sealing device 1 includes a body 13 formed integrally with the reinforcing ring 12 and a seal lip 11 held by the body 13.

  Specifically, the reinforcing ring 12 is manufactured by punching a metal plate, and the cross-sectional shape cut by a plane passing through the axis is substantially L-shaped, that is, from the cylindrical portion 121 and one axial end thereof. An inward flange 122 extending inward and in a plane perpendicular to the axis.

  The body 13 is made of a rubber-like elastic material, and includes an outer peripheral seal portion 131 integrally vulcanized and bonded to the outer peripheral surface of the cylindrical portion 121 in the reinforcing ring 12 and an inward flange portion 122 in the reinforcing ring 12. The back support portion 132 is vulcanized and bonded in an embedded state, and the dust strip 133 extends from the inner periphery to the inner periphery side of the back support portion 132. That is, the body 13 is defined between the inner surface of the mold and the reinforcing ring 12 in a clamped state by setting the reinforcing ring 12 previously coated with a vulcanizing adhesive in a predetermined mold (not shown). An unvulcanized rubber material is filled in an annular cavity and heated and pressurized to be integrally vulcanized and formed on the reinforcing ring 12.

  The outer peripheral seal portion 131 of the body 13 is in close contact with the seal mounting surface 3a formed in the shaft hole of the stationary housing 3 with a required tightening margin, and the dust lip 133 has an inner peripheral end of the rotary shaft 2. The outer peripheral surface is lightly contacted or closely opposed via a slight gap.

  The seal lip 11 is formed of a low-friction synthetic resin material such as PTFE (polytetrafluoroethylene), and is fitted to the inner periphery of the cylindrical portion 121 in the reinforcing ring 12 and at the back support portion in the body 13. A disc-shaped outer peripheral portion 111 attached in close contact with 132, and extends from the inner periphery to the opposite side of the dust lip 133, that is, to the sealed space A side in the machine, and can slide on the outer peripheral surface 2a of the rotary shaft 2 It consists of the inner peripheral part 112 closely_contact | adhered to.

  A spiral groove 112a is formed on the inner peripheral surface of the inner peripheral portion 112 including the inner curved portion of the disk-shaped outer peripheral portion 111 of the seal lip 11, and more specifically, the spiral groove 112a has the rotating shaft 2 formed on the rotating shaft 2. When rotating in the R direction, the fluid in contact with the shaft circumference is pumped to the sealed space A side (right side in FIG. 1), that is, extends toward the tip 113 of the seal lip 11 while circling in the R direction. Is formed. Similarly, a spiral groove 112b is formed on the outer peripheral surface of the inner peripheral portion 112 including the curved portion. Specifically, when the rotary shaft 2 rotates in the R direction, the spiral groove 112b contacts the shaft periphery. It is formed so as to extend toward the tip 113 of the seal lip 11 while circulating in the direction in which the fluid being pumped to the sealed space A side (right side in FIG. 1), that is, in the R direction.

  The spiral grooves 112a and 112b are formed at the same pitch and at positions shifted from each other with respect to the extending direction of the seal lip 11, and the inner peripheral portion 112 of the seal lip 11 is formed by the spiral grooves 112a and 112b. It has a wavy cross-sectional shape having spiral peaks and valleys. For this reason, the seal lip 11 is formed of a synthetic resin material such as PTFE, which is less elastic than rubber, but the inner peripheral portion 112 can be deformed flexibly by forming a wavy cross-sectional shape. It has become.

  Further, the spiral groove 112a on the inner peripheral surface is discontinuous at one or more places as indicated by reference numeral 112c, and when the pumping action of the spiral groove 112a is lost due to the stop of the rotating shaft 2, The fluid to be sealed in the sealed space A is prevented from flowing out to the anti-sealed space (atmosphere) B side through the spiral groove 112a.

The rotating shaft 2 forms a cylindrical surface in which the outer peripheral surface 21 a of the sealed portion 21 located on the inner periphery of the seal lip 11 is eccentric with respect to the rotation center O ₂₂ of the rotating shaft 2. That is, as shown in FIG. 2, the rotating shaft 2 is rotatably supported by the supported portion 22 on the inner peripheral surface of the shaft hole of the housing 3 via the bearing 4, and the axis O of the sealed portion 21 is supported. ₂₁ is eccentric with an eccentric amount δ with respect to the axis (rotation center O ₂₂ ) of the supported portion 22 by the bearing 4.

In the shaft sealing structure according to the first embodiment configured as described above, when the rotary shaft 2 rotates, the sealed portion 21 (axial center O ₂₁ ) is around the rotation center O ₂₂ as shown in FIG. 1 and 4, as shown in FIGS. 1 and 4, the outer peripheral surface 21a of the sealed portion 21 is apparently reciprocated by 2δ in the radial direction every rotation. In the sealing device 1, the inner peripheral portion 112 of the seal lip 11 that is in close contact with the outer peripheral surface 21 a of the sealed portion 21 has a wavy cross-sectional shape formed by the spiral grooves 112 a and 112 b, and therefore, as shown in FIG. 4. Furthermore, it follows the displacement of the outer peripheral surface 21a of the sealed portion 21 while flexibly deforming. Therefore, the inner peripheral portion 112 of the seal lip 11 can maintain a good close contact state with the outer peripheral surface 21a of the sealed portion 21 in the rotating shaft 2 that moves eccentrically.

  The spiral groove 112a formed on the inner peripheral surface of the inner peripheral portion 112 of the seal lip 11 is provided with a pump pressure (screw pump action) for sending fluid toward the sealed space A side by the rotation of the rotary shaft 2 (sealed portion 21). ) Is generated. For this reason, it has the effect | action which pushes back the sealing object fluid which passes between the sealing lip 11 and the rotating shaft 2 (sealed part 21) from the sealing space A, and is going to leak to the anti-sealing space B side to the sealing space A.

Further, the eccentricity of the sealed portion 21 in the rotation axis 2, on the side where the outer circumferential surface 21a is close to the center of rotation O ₂₂ is an inner peripheral portion 112 of the seal lip 11, as indicated by the solid line in FIG. 4 , the surface pressure with the contact width with respect to the outer peripheral surface 21a of the sealing portion 21 becomes smaller and smaller, in the the 180-degree symmetrical positions on the side of the outer peripheral surface 21a is away from the rotational center O _22, the seal lip As shown by a two-dot chain line in FIG. 4, the inner circumferential portion 112 of 11 has a larger contact pressure with respect to the outer circumferential surface 21 a of the sealed portion 21 and a larger surface pressure. Then, such a portion P _MIN having a small surface pressure and a portion P _MAX having a large surface pressure move in the circumferential direction as the sealed portion 21 rotates, as indicated by a one-dot chain line or two-dot chain line in FIG. Therefore, it has the effect | action which scrapes out the fluid which is contacting the outer peripheral surface 21a of the to-be-sealed part 21, ie, the fluid which exists in the spiral groove 112a along this spiral groove 112a. Therefore, the screw pump function by the spiral groove 112a is backed up, and an excellent sealing function can be achieved.

Moreover, the portion P _MIN having a small surface pressure and the portion P _MAX having a large surface pressure as described above move in the circumferential direction as the sealed portion 21 rotates, thereby generating dynamic pressure in the fluid in the spiral groove 112a. Therefore, a part of the fluid intervenes as a lubricating film on the sliding portion S between the inner peripheral portion 112 of the seal lip 11 and the outer peripheral surface 21a of the sealed portion 21. Therefore, in addition to the fact that the seal lip 11 is made of PTFE having a low coefficient of friction, good lubrication by the fluid can be obtained, so that the wear of the seal lip 11 is remarkably reduced and the seal lip 11 due to the sliding torque is reduced. Twist can also be effectively prevented.

  The eccentricity δ is larger than the normal allowable eccentricity of 0 mm. However, the larger the eccentricity δ, the larger the repeated deformation of the seal lip 11 with the rotation of the rotary shaft 2 and the higher the sliding resistance. Therefore, considering this, it is assumed that the allowable deformation amount in the radial direction by the spiral grooves 112a and 112b of the inner peripheral portion 112 in the seal lip 11 is sufficiently smaller.

  On the other hand, the dust lip 133 formed on the body 13 prevents dust or the like in the atmosphere of the anti-sealed space B from entering the sealed space A.

In the above description, the sealed portion 21 that is eccentric with respect to the rotation center O ₂₂ is formed on the rotary shaft 2 itself. However, the eccentric sleeve 23 as shown in FIG. The part 21 can also be formed. That is, in the eccentric sleeve 23 shown in FIG. 5, the outer peripheral surface 23a and the inner peripheral surface 23b into which the rotation shaft is inserted through an O-ring (not shown) are eccentric from each other. Therefore, the same effect as described above can be obtained by extrapolating such an eccentric sleeve 23 to the rotary shaft 2 having no eccentric portion and located on the inner periphery of the seal lip 11 of FIG.

  Next, FIG. 6 is a schematic perspective view showing the shape of the rotating shaft in the second embodiment of the present invention, FIG. 7 is an explanatory view showing the behavior of the rotating shaft of FIG. 6 in a cross section orthogonal to the axis, FIG. 8 is a perspective view showing an elliptic sleeve as a modified example of the second embodiment.

  In this embodiment, the configuration of the sealing device 1 is the same as that in FIG. 1, and the difference from the first embodiment described above is the shape of the rotary shaft 2. That is, the rotary shaft 2 has a cross-sectional shape obtained by cutting the outer peripheral surface 21a of the sealed portion 21 located on the inner periphery of the seal lip 11 shown in FIG. Make an ellipse.

Specifically, as shown in FIG. 6, the rotating shaft 2 is rotatably supported on the inner peripheral surface of the shaft hole of the housing 3 via the bearing 4 in the cylindrical supported portion 22. The rotation center O ₂₂ thereby passes through the intersection of the minor axis r _S and the major axis r _L in the elliptical cross section of the sealed portion 21 as shown in FIG.

  In the shaft sealing structure according to the second embodiment configured as described above, when the rotating shaft 2 rotates, the outer peripheral surface 21a of the sealed portion 21 apparently reciprocates twice in the radial direction every rotation. become.

Further, the inner peripheral portion 112 of the seal lip 11 of the sealing device 1 shown in FIG. 1 is in intimate contact with the outer peripheral surface 21a of the sealed portion 21 in the rotating shaft 2, and the outer peripheral surface 21a of the sealed portion 21 is Since it has an elliptical cross-sectional shape, the inner peripheral portion 112 of the seal lip 11 is covered in the portion close to the minor axis r _S direction as shown by the solid line in FIG. 4 described above. surface pressure with the contact width is reduced with respect to the outer peripheral surface 21a of the sealing portion 21 is smaller in the portion closely to the major axis r _L direction, the inner peripheral portion 112 of the seal lip 11, two-dot chain line in FIG. 4 As shown, the contact width with respect to the outer peripheral surface 21a of the sealed portion 21 is increased and the surface pressure is increased. Such a portion P _MIN having a small surface pressure and a portion P _MAX having a large surface pressure (two locations each) move in the circumferential direction as the sealed portion 21 rotates, as indicated by a dotted line or a one-dot chain line in FIG. As a result, the fluid in contact with the outer peripheral surface 21a of the sealed portion 21, in other words, the fluid existing in the spiral groove 112a is scraped along the spiral groove 112a. Therefore, the screw pump function by the spiral groove 112a of the seal lip 11 is backed up, and an excellent sealing function can be achieved.

Further, according to the second embodiment, the rotation center O ₂₂ of the rotating shaft 2 passes through the intersection of the short diameter r _S and the long diameter r _L in the elliptical cross section of the sealed portion 21, and therefore the center of gravity on the cross section Coincides with the rotation center O _22, and therefore vibration of the rotating shaft 2 accompanying rotation does not occur.

The larger the difference between the minor axis r _S and the major axis r _L , the larger the repeated deformation of the seal lip 11 accompanying the rotation of the rotary shaft 2 and the larger the sliding resistance. The difference between the diameter r _S and the major axis r _L is set appropriately.

Also in this embodiment, the sealed portion 21 can be formed using a sleeve, as in the first embodiment described above. That is, the elliptical sleeve 24 shown in FIG. 8 has an elliptical cross-sectional shape obtained by cutting the outer peripheral surface 24a with a plane orthogonal to the axial center, and a cylindrical shape into which a rotating shaft is inserted via an O-ring (not shown). A central axis O ₂₄ (rotation center) of the inner peripheral surface 24b passes through the intersection of the minor axis r _S and the major axis r _L of the elliptical cross section. Therefore, the effect similar to the above can be obtained by extrapolating such an elliptic sleeve 24 to the rotating shaft 2 located on the inner periphery of the seal lip 11 of FIG.

  Next, FIG. 9 is a half sectional view showing the shaft sealing structure according to the third embodiment of the present invention by cutting along a plane passing through the shaft center, and FIG. 10 shows the behavior of the seal lip accompanying the behavior of the rotating shaft. It is a fragmentary sectional view cut and shown by the plane which passes through the heart.

  In this embodiment, the sealing device 1 includes a plurality of annular grooves 112d continuous in the circumferential direction on the inner peripheral surface and the outer peripheral surface of the inner peripheral portion 112 including the curved portion on the inner periphery of the disc-shaped outer peripheral portion 111 in the seal lip 11. , 112e are formed, and the other components basically have the same configuration as that shown in FIG.

The annular grooves 112 d and 112 e are formed at the same pitch and at positions shifted from each other with respect to the extending direction of the seal lip 11. Therefore, the inner peripheral portion 112 of the seal lip 11 has a wavy cross-sectional shape having an annular crest and a trough by the annular grooves 112d and 112e. Further, as shown in FIG. 10, the annular groove 112 d on the inner peripheral surface is an angle formed by the rising surface 112 d _A near the sealed space A (right side in FIG. 10) of the annular groove 112 d with respect to the outer peripheral surface of the rotating shaft 2. α has a smaller than the angle β formed by the rising surface 112d _B of (left side in FIG. 10) opposite to the sealed space B side of the annular groove 112d to the outer peripheral surface of the rotating shaft 2.

Rotary shaft 2, as shown in FIG. 2 described above, i.e. the outer circumferential surface 21a of the sealing portion 21 located on the inner periphery of the seal lip 11, eccentricity with respect to the rotational center O ₂₂ of the rotary shaft 2 The cylindrical shape decentered by δ, or the one shown in FIG. 6 described above, that is, the cross-sectional shape obtained by cutting the outer peripheral surface 21a of the sealed portion 21 with a plane perpendicular to the axis is elliptical. The center of rotation O ₂₂ passes through the intersection of the minor axis r _S and the major axis r _L of the ellipse.

In sealing structure according to the third embodiment structured as described above, when the rotary shaft 2 is rotated, if those having a cylindrical surface which the sealing portion 21 is eccentric to the rotational center O _22, the outer periphery When the surface 21a is apparently displaced so as to reciprocate once in the radial direction for each rotation, and the sealed portion 21 has an elliptical shape, the outer peripheral surface 21a apparently appears every rotation. It is displaced so as to reciprocate twice in the radial direction. And since the inner peripheral part 112 of the seal lip 11 in the sealing device 1 has a wavy cross-sectional shape by the annular grooves 112d and 112e, it follows the displacement of the outer peripheral surface 21a of the sealed part 21 while flexibly deforming. Therefore, the inner peripheral portion 112 of the seal lip 11 can maintain a good close contact state with the outer peripheral surface 21 a of the sealed portion 21 in the rotating shaft 2.

Further, in the portion where the outer peripheral surface 21a of the sealed portion 21 in the rotation axis 2 is close to the rotational center O _22, the inner peripheral portion 112 of the seal lip 11, as indicated by the solid line in FIG. 4 described above , the surface pressure with the contact width with respect to the outer peripheral surface 21a of the sealing portion 21 becomes smaller and smaller, in the portion where the outer peripheral surface 21a is away from the rotational center O _22, the inner peripheral portion 112 of the seal lip 11, previously As indicated by the two-dot chain line in FIG. 4 described above, the contact width with respect to the outer peripheral surface 21a of the sealed portion 21 is increased and the surface pressure is increased. For this reason, as shown by a solid line and a two-dot chain line in FIG. 10, the cross-sectional shape of the annular groove 112d repeatedly expands and contracts with the apparent radial displacement of the outer peripheral surface 21a of the sealed portion 21. become.

Therefore, in the portion where the annular groove 112d is crushed, the fluid existing in the groove flows toward the portion where the cross section of the annular groove 112d is enlarged, and a part of the fluid is indicated by an arrow F in FIG. as indicated, so as to push open the rising surface 112d _a angle α is small sealed space a toward forming the outer peripheral surface of the rotary shaft 2, so to intervene to the sliding portion S of the sealed space a side, A good lubricating film is formed. Further, in this embodiment, the screw pump function like the spiral groove cannot be achieved, but the pumping action in the direction of arrow F due to the cross-sectional shape of the annular groove 112d is induced, so that the sealing function can be improved. Moreover, since this pump action does not depend on the rotation direction of the rotary shaft 2, an excellent sealing function can be achieved even in a device in which the rotary shaft 2 rotates forward and reverse.

  The groove cross-sectional shape shown in FIG. 10 can also be applied to the spiral groove 112a shown in FIG. In this case, in addition to the screw pump function of the spiral groove 112a, the above-described pump action due to the groove cross-sectional shape is induced, so that the lubricity and the sealing performance can be further improved.

  Furthermore, the eccentric sleeve 23 shown in FIG. 5 or the elliptic sleeve 24 shown in FIG. 8 can also be used for this third embodiment.

It is a half sectional view which cuts and shows the shaft seal structure by the 1st form of the present invention by the plane which passes along an axis. It is a schematic perspective view which shows the shape of the rotating shaft in the 1st form of this invention. In the 1st form of this invention, it is explanatory drawing which shows the behavior of the rotating shaft in the cross section orthogonal to an axial center. In the 1st form of this invention, it is a partial half section view which cut | disconnects and shows the behavior of the seal lip accompanying the behavior of a rotating shaft by the plane which passes along an axial center. It is a perspective view which shows the eccentric sleeve as a modification of a 1st form. It is a schematic perspective view which shows the shape of the rotating shaft in the 2nd form of this invention. It is explanatory drawing which shows the behavior of the rotating shaft of FIG. 6 in the cross section orthogonal to an axial center. It is a perspective view which shows the elliptical sleeve as a modification of a 2nd form. FIG. 6 is a half sectional view showing a shaft sealing structure according to a third embodiment of the present invention by cutting along a plane passing through an axis. It is a fragmentary sectional view which cuts and shows the behavior of a seal lip accompanying the behavior of the rotating shaft in the 3rd form in the plane which passes along an axis.

Explanation of symbols

1 sealing device 11 seal lip 111 disc outer peripheral portion 112 inner peripheral portion 112a, 112b spiral grooves 112d, 112e annular groove 112d _A, 112d _B rising surface 113 tip 12 reinforcing ring 121 cylindrical portion 122 inward collar portion 13 the body 131 peripheral seal Part 132 Back support part 133 Dustrip 2 Rotating shaft 2a, 21a, 23b, 24a Outer peripheral surface 21 Sealed part 22 Supported part 23 Eccentric sleeve 24 Elliptical sleeve 3 Housing 3a Seal mounting surface A Sealing space B Anti-sealing space S Sliding part _{O 22, O 24} center of rotation

Claims (5)

An inner peripheral portion (112) of the seal lip (11) made of an elastically deformable material is slidably in close contact with the outer peripheral surface of the rotating shaft (2). The seal lip is characterized in that the outer peripheral surface (21a) of the sealed portion (21) located on the inner periphery of the seal lip (11) forms a cylindrical surface that is eccentric with respect to the rotation center (O ₂₂ ). Shaft seal structure. An inner peripheral portion (112) of the seal lip (11) made of an elastically deformable material is slidably in close contact with the outer peripheral surface of the rotating shaft (2). The cross-sectional shape obtained by cutting the outer peripheral surface (21a) of the sealed portion (21) located on the inner periphery of the seal lip (11) along a plane perpendicular to the axis is an ellipse, and the rotation of the rotary shaft (2) A shaft seal structure with a seal lip, characterized in that the center (O ₂₂ ) passes through the intersection of the ellipse minor axis (r _S ) and major axis (r _L ).   The spiral groove (112a) extending in the direction of pumping fluid toward the sealed space by rotation of the rotating shaft (2) is formed on the inner peripheral surface of the seal lip (11). 2. A shaft seal structure with a seal lip as described in 2.   The shaft seal structure with a seal lip according to claim 1 or 2, wherein a plurality of grooves (112d) continuous in the circumferential direction are formed on the inner peripheral surface of the seal lip (11). The angle (α) formed by the rising surface (112d _A ) near the sealed space (A) of the groove (112d) with respect to the outer peripheral surface of the rotating shaft (2) is defined as a groove ( anti-seal space (B) nearer the shaft seal structure by sealing lip according to claim 3 or 4, the rising surface (112d _B) characterized in that is smaller than the angle (beta) formed by the in 112d).

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