JP2012215188A - Sealing structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sealing structure which enables a longer-term use of a seal member.SOLUTION: The seal member 3 includes a seal body 30 which is accommodated in an annular groove 21, a lip-like first seal part 31 which extends from the seal body 30 toward a shaft 1 while inclining on one side in an axial direction and is in slidable contact with the shaft 1, a second seal part 32 that is in slidable contact with the shaft 1 on the another side of the axial direction from the first lip 31, and a third seal part 33 that is in close contact with a housing 2. The housing 2 includes a pressing part configured to be capable of pressing the seal member 3 and capable of adjusting the pressing force so that a force in different positions in a radial direction and opposing each other acts to cause the deformation in the seal member 3 to enhance the degree of adhesion of the first seal part 31 to the shaft 1.

Description

  The present invention relates to a sealing structure.

  Conventionally, a rod sealing system is known as a sealing device for sealing a rod portion of a hydraulic cylinder used in a construction machine or the like (see, for example, Patent Document 1). A rod sealing system according to a conventional example will be described with reference to FIGS. FIG. 5 is a schematic perspective view showing a cross-sectional configuration of the hydraulic cylinder. FIG. 6 is a schematic cross-sectional view of a rod sealing system.

  As shown in FIG. 5, the hydraulic cylinder 101 includes a cylinder 102, a piston 103 that is slidably fitted into the cylinder 102, and a rod 104 that is coupled to the piston 103. The cylinder 102 is provided with two hydraulic pressure introduction holes 105 and 106 at positions where the piston 103 is sandwiched. By selectively applying hydraulic oil pressure to the oil pressure introduction holes 105 and 106, the piston 103 is moved in the axial direction, and the relative positions of the mounting portions 107 and 108 of the cylinder 102 and the rod 104 are changed. The rod sealing system is provided at the end of the cylinder 102 and seals the gap between the cylinder 102 and the rod 104.

  As shown in FIG. 6, the rod sealing system includes a rod packing R, a buffer ring B, and a dust seal D. The rod packing R mainly prevents leakage of hydraulic oil to the outside (A) side. The buffer ring B mounted on the inside (O) side (hydraulic side) of the rod packing R buffers the impact pressure and fluctuating pressure at high loads, and cuts inflow of hot hydraulic oil to the rod packing R side. Thus, the durability of the rod packing R is improved. The dust seal D is attached to the outside of the rod packing R, and mainly prevents dust and foreign matter from entering from the outside.

  Each seal member is lubricated by forming an oil film between the rod surface and the hydraulic oil slightly leaking from the inside of the cylinder. However, depending on use conditions, sufficient lubricity cannot be obtained, and the seal member may be damaged due to wear. The damage of the seal member in the rod portion is the situation that should be avoided most because it directly leads to oil leakage to the outside of the cylinder. However, it is often used under conditions where it is difficult to obtain sufficient lubrication, and it is often requested that continuous use is possible even after wear occurs.

  A V-packing has been conventionally known as a seal member that can be used continuously even if wear occurs. The V-packing is configured so that it can be continuously used even after it is worn by adjusting the interference with shims or springs. However, the V-packing is configured to be attached using a male adapter and a female adapter, and when used to seal internal oil and external dust at the same time, it is necessary to ensure a large mounting groove width. For this reason, when there is a demand for space saving and double-sided seals, there is a limit to the use of V-packing.

  On the other hand, in the case of a dust seal as shown in FIG. 6, it can be used alone and can be saved in a space-saving manner. However, the conventional dust seal cannot adjust the interference allowance, so that the continuous use becomes difficult when wear occurs.

JP 2006-029518 A

  The present invention has been made to solve the above-described problems of the prior art, and an object of the present invention is to provide a sealing structure that enables a long-term use of the sealing member.

In order to achieve the above object, the sealing structure in the present invention comprises:
The axis,
A housing having a shaft hole into which the shaft is inserted so as to be relatively movable;
A sealing member for sealing an annular gap between these two members;
A sealing structure comprising:
The sealing member is
A seal body housed in an annular groove provided in one of the two members;
A lip-shaped first seal portion that extends from the seal body toward the other member of the two members while being inclined toward the other side in the axial direction, and is in sliding contact with the other member;
A second seal portion that is in sliding contact with the other member on the other axial side than the first lip of the seal body;
A third seal portion provided on the groove bottom side of the annular groove in the seal body, and in close contact with the one member;
Have
The one member is subjected to a force that is different from each other in the radial direction and opposite to the axial direction in order to cause the seal member to be deformed so as to increase the degree of adhesion of the first seal portion to the other member. Thus, the seal member is configured to have a pressing portion configured to be able to press and adjust the pressing force.

  According to the present invention, even when the lip-shaped first seal portion is worn by sliding with the other member, and the degree of close contact (tightening allowance) between the first seal portion and the other member is lowered, By applying the pressing force, the lowered degree of adhesion can be increased. Further, by adjusting the pressing force according to the progress degree of wear to increase the degree of deformation of the seal member, the degree of adhesion can be maintained even after the wear further progresses. Thereby, use can be continued even if abrasion arises in the 1st seal part.

The pressing portion is
A first pressing portion that presses the seal body from one axial side toward the other axial side;
A second pressing portion that presses the seal member from the other axial side toward the one axial side at a position closer to the bottom of the annular groove than the pressing position of the first pressing portion in the radial direction;
It is good to include.

  According to such a configuration, the moment of force as if the seal member rotates in the cross section (judgment surface) by pressing by each pressing portion, that is, as if the inner peripheral side and the outer peripheral side of the seal member are turned over. Is generated in the seal member. Thereby, with the pressing position of the first pressing portion as a boundary, the inner peripheral side and the outer peripheral side of the sealing member, that is, the side pressed by the second pressing portion and the side on which the first sealing portion on the opposite side is provided The seal member is deformed so as to be displaced in directions opposite to each other. The lip-shaped first seal portion that inclines from the seal body toward one side in the axial direction and extends toward the other member causes the base side to be displaced toward the other side in the axial direction and the other member side due to such deformation, and the tip side is the other member. It will be in a state of being pressed against. Thereby, the adhesion degree of the 1st seal part to the other member can be raised.

The annular groove is configured to be able to change the interval between the groove side surfaces,
The first pressing portion is provided on any one of the groove side surfaces,
The second pressing portion may be provided on either one of the groove side surfaces.

  By changing the interval between the groove side surfaces of the annular groove, the relative positions in the axial direction of the first pressing portion and the second pressing portion change, and the pressing force acting on the seal member can be adjusted.

The second seal portion is a lip-shaped seal portion that extends from the seal main body toward the other member while being inclined toward the other axial direction, and is in close contact with the other member,
The one member may have a contact portion that contacts the base portion of the second seal portion from the opposite side to the other member.

  Due to the deformation by the pressing portion, the portion of the seal body in the base portion of the lip-shaped second seal portion tends to be displaced in a direction away from the other member. When the contact portion presses the base portion of the second seal portion, it is possible to suppress the second seal portion from being separated from the other member. Thereby, the fall of the close_contact | adherence degree with respect to the other member of the 2nd seal part by the said deformation | transformation can be suppressed, and the sealing performance of a 2nd seal part can be maintained.

  The first seal portion may include a lip-shaped portion protruding toward the other member on the lip base side.

  When the lip tip side of the first seal portion is pressed against the other member due to the deformation of the seal member, the protruding direction of the lip-shaped portion located on the lip root side of the first seal portion is inclined to the other side in the axial direction. As a result, a lip-shaped seal portion extending obliquely toward the other axial direction side is formed on the other axial side with respect to the lip tip side of the first seal portion, and the sealing performance of the first seal portion is further enhanced.

  According to the present invention, the seal member can be used for a longer period.

1 is a schematic cross-sectional view of a sealing structure according to Example 1. FIG. 1 is a schematic cross-sectional view of a sealing structure according to Example 1. FIG. 1 is a schematic cross-sectional view in the vicinity of a dust seal with a sealing structure according to Embodiment 1. FIG. FIG. 6 is a schematic cross-sectional view in the vicinity of a dust seal with a sealing structure according to a second embodiment. The typical perspective view which shows the cross-sectional structure of a hydraulic cylinder. The typical sectional view showing composition of a rod sealing system.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be exemplarily described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified. .

Example 1
With reference to FIGS. 1-3, the sealing structure which concerns on Example 1 of this invention is demonstrated. FIG. 1 is a schematic cross-sectional view of a sealing structure according to the present embodiment. FIG. 2 is a schematic cross-sectional view of the sealing structure according to the present embodiment and shows a state when a pressing force is applied. FIG. 3 is a schematic cross-sectional view of the vicinity of the dust seal of the sealing structure according to the present embodiment.

<Schematic configuration of sealing structure>
As shown in FIG. 1, the sealing structure according to this embodiment includes a shaft 1, a housing 2, and a dust seal 3. The housing 2 has a shaft hole 20 into which the shaft 1 is inserted. The dust seal 3 is an annular seal member that seals the annular gap 4 between the shaft 1 and the shaft hole 20 of the housing 2. The dust seal 3 is mounted in an annular groove 21 provided in the shaft hole 20 and is in sliding contact with a shaft that reciprocates in the axial direction with respect to the housing 2.

  The sealing structure according to the present embodiment can be applied to a dust seal assembly structure for preventing intrusion of dust and the like from the outside in a rod sealing system of a hydraulic cylinder as shown in FIGS. 5 and 6, for example. . In this case, the dust seal 3 mainly serves to prevent dust and the like from entering from the outside (A) side to the inside (O) side, but from the inside (O) side to the outside (A) side such as hydraulic oil. Prevention of leakage is also required as a function.

<Dust seal>
The dust seal 3 is slidably in contact with the shaft 1 on the inner (O) side of the seal body 30, the first lip 31 as a first seal portion that is slidably in contact with the shaft 1, and the first lip 31. A second lip 32 serving as a second seal portion and a third lip 33 serving as a third seal portion in close contact with the housing 2 (the groove bottom surface 22 of the annular groove 21). The dust seal 3 seals the annular gap 4 when each lip is in close contact with the shaft 1 and the housing 2.

  The first lip 31 is provided on the inner peripheral side and the outer (A) side of the seal main body 30, and extends inclined toward the outer (A) side toward the shaft 1. The first lip 31 mainly functions as a dust lip for preventing intrusion of dust and the like from the outside (A).

  The second lip 32 is provided on the inner peripheral side and the inner (O) side of the seal body 30 and extends toward the inner (O) side toward the shaft 1. The second lip 32 mainly functions as an oil lip for preventing leakage of oil from the inside (O).

  The third lip 33 is provided on the outer peripheral side and the inner (O) side of the seal body 30, and extends inclined toward the inner (O) side toward the groove bottom surface 22 of the annular groove 20. The third lip 33 functions as a seal portion that is in close contact with the housing 2.

<Housing>
In the sealing structure according to the present embodiment, the opening of the shaft hole 20 of the housing 2 is configured to expand in a step shape. The dust seal 3 is attached to the housing 2 by being attached to the diameter-expanded portion of the opening and attaching a presser plate 23 to the outside thereof. That is, the dust seal 3 is sandwiched between the presser plate 23 and the surface facing the presser plate 23 in the enlarged diameter portion of the shaft hole 20. And the sealing structure is formed by inserting the shaft 1 into the shaft hole 20 to which the dust seal 3 is attached.

  The presser plate 23 is an annular member having an inner diameter smaller than the diameter-enlarged portion (groove bottom surface 22). The presser plate 23 is attached to the opening end surface of the shaft hole 20, so that the presser plate 23 accommodates the dust seal 3. A mounting space (annular groove 21) is formed in the shaft hole 20.

  The holding plate 23 is configured to be capable of changing the mounting position with respect to the housing 2 in the axial direction. In this embodiment, as shown in FIG. 1, a spacer 25 such as a shim is sandwiched between the housing 2 and a fastener 26 such as a bolt. By replacing the spacers 25 with different thicknesses, the mounting position of the presser plate 23 can be adjusted in the axial direction.

Note that the structure of the presser plate 23 attached to the housing 2 so that the position thereof can be adjusted is not limited to the structure of the present embodiment, and other conventionally known structures can be appropriately employed. Further, the configuration of the housing 2 is not limited to the configuration using the pressing plate 23 as described above. If the housing 2 is configured to be split in the annular groove 21 for mounting the dust seal 3, various conventionally known configurations can be employed.

  The pressing plate 23 is provided with a protrusion 23 b as a first pressing portion on a side surface 23 a that forms a side wall surface on the outside (A) side of the annular groove 22. The protrusion 23b protrudes substantially in the axial direction toward the inside (O) side. The protrusion 23 b is configured to press the root portion of the first lip 31 of the seal body 30.

  The side wall surface on the inside (O) side of the annular groove 22, that is, the surface facing the presser plate 23 in the enlarged diameter portion of the shaft hole 20, the end surface 24 a on the opening side of the annular groove 22, It is comprised by the end surface 24b as a 2nd press part of the side, and the protrusion 24c as a contact part between the end surface 24a and the end surface 24b. The protrusion 24c protrudes substantially in the axial direction toward the outside (A).

  The end surface 24 b abuts against the tip of the third lip 33 of the dust seal 3, and the pressing force toward the outside (A) side is applied via the third lip 33 as a reaction force against the force pushing the dust seal 3 toward the inside (O) side. The seal body 30 is configured to be able to act. As shown in FIG. 2, the position P <b> 2 where the end surface 24 b contacts the tip of the third lip 33 in the radial direction is radially outside the position P <b> 1 where the projection 23 b presses the seal body 30.

  A space between the second lip 32 and the third lip 33 of the dust seal 3 has a concave shape like a groove opened to the inside (O) side having a substantially U-shaped cross section. The protrusion 24c is configured to fit in the recess.

<Excellent points of this embodiment>
In the sealing structure according to the present embodiment, when the first lip 31 is worn by sliding with the shaft 1, and the degree of closeness (crimping allowance) of the first lip 31 to the shaft 1 is reduced, such closeness is restored. It is comprised so that it can be made to. That is, the dust seal 3 is deformed so as to increase the degree of adhesion of the first lip 31 to the shaft 1. The pressing portions (protrusions 23b and end surfaces 24b) are configured to be able to press the dust seal 3 so that the radial positions are different from each other and the axially opposing forces act on the dust seal 3.

  Further, the pressing force against the dust seal 3 is configured to be adjustable. That is, by tightening the presser plate 23, the position of the protrusion 23b is moved in the axial direction toward the inside (O), and the distance from the end surface 24b is narrowed (the relative distance in the axial direction is shortened). 3 can be increased and the degree of deformation can be increased.

  As shown in FIG. 1, for example, at the stage where the first lip 31 is not worn, as in the initial stage of use, the first lip 31 can be secured by the projection 23b because a sufficient amount of interference is secured for the first lip 31. It will be in the mounting state in which the base of is slightly pressed. At this time, the end surface 24 b may not be in contact with the tip of the third lip 33. That is, since there is no wear on the dust seal 3, it is not necessary to positively apply a pressing force that causes the seal body 30 to be deformed to increase the adhesion of the first lip 31.

  As shown in FIG. 2, when wear occurs in the first lip 31 and the interference of the first lip 31 decreases, the presser plate 23 is tightened to move the position of the protrusion 23b to the inside (O) side. As a result, the dust seal 3 is pushed into the inside (O) side, and the tip of the third lip 33 comes into contact with the end surface 24 b of the housing 2. By pressing the dust plate 3 toward the inside (O) side by retightening the holding plate 23, a reaction force (pressing force) is applied to the seal body 30 from the end face 24b to the outside (A) side through the third lip 33. Works.

  When such a pressing force acts on the dust seal 3, a force as if the dust seal 3 rotates in the cross section (determination surface), that is, as if the inner side and the outer side of the dust seal 3 are turned over. A moment is generated in the dust seal 3. Thereby, with the pressing position of the protrusion 23b as a boundary, the inner and outer peripheral sides of the dust seal 3, that is, the side pressed by the end face 24b and the side provided with the first lip 31 on the opposite side are mutually connected. The dust seal 3 is deformed so as to be displaced in the opposite direction. The first lip 31 that is inclined from the seal body 30 toward the outside (A) and extends toward the shaft 1 is displaced in the root side toward the inside (O) side and the shaft 1 side by such deformation, and the tip side is further pressed against the shaft 1. It becomes a state. Thereby, the adhesion degree of the 1st lip 31 with respect to the axis | shaft 1 can be raised.

  That is, according to the present embodiment, even if the first lip 31 is worn and the degree of close contact of the first lip 31 with the shaft 1 is reduced, the pressing force is adjusted to increase the degree of deformation of the dust seal 3, The degree of close contact of one lip 31 with the shaft 1 can be restored. Further, by adjusting the pressing force according to the progress of wear and increasing the degree of deformation of the dust seal 3, the degree of close contact with the shaft 1 can be maintained even after the wear further progresses. Thereby, the use can be continued even after the first lip 31 is worn.

  In particular, in the rod sealing system as shown in FIGS. 5 and 6, the dust seal (particularly the outer dust lip) is disposed on the outermost side and is likely to be worn due to insufficient lubrication. By applying the sealing structure according to the present embodiment as an assembly configuration of such a dust seal, it is possible to extend the life of the sealing system. That is, even if the dust seal is worn due to insufficient lubrication, the pressing force can be adjusted to increase the degree of adhesion of the dust lip and maintain the sealing performance. The function required in the dust seal is mainly the intrusion of dust and the like from the outside, and the continuous use after the wear has occurred can be made possible by maintaining the adhesion degree of the dust lip for a long period of time.

  Further, as shown in FIG. 1, the projection 24 c is configured to fit with a gap in the recess of the dust seal 3 in the initial stage of use when the dust seal 3 (first lip 31) is not worn. ing. Thereafter, as shown in FIG. 2, at the stage where the dust seal 3 is abraded and tightening of the presser plate 23 is increased, the dust seal 3 is pushed into the inside (O) side, so that the tip of the protrusion 24 c becomes the second lip 32. It will be in the state contact | abutted to the root of (refer FIG. 3).

  The base portion of the second lip 32 in the seal body 30 is displaced in a direction away from the shaft 1 due to deformation of the seal body 30 caused by tightening the presser plate 23. At this time, the protrusion 24c presses the base of the second lip 32 from the outer peripheral side, so that the second lip 32 is prevented from being separated from the shaft 1 due to the deformation of the seal body 30. Thereby, the fall of the adhesion degree with respect to the axis | shaft 1 of the 2nd lip 32 by the said deformation | transformation of the seal body 30 can be suppressed, and the sealing performance of the 2nd lip 32 can be maintained.

  Therefore, according to the present embodiment, the dust seal 3 can be used for a longer period.

<Others>
In the present embodiment, the dust seal 3 is attached to the housing 2, but the configuration for attaching the dust seal 3 is not limited to this. For example, the shaft 1 may be configured to be divided into a plurality of members, and the dust seal 3 may be mounted between these members.

The protrusion 23b constituting the pressing portion is not limited to an annular protrusion. For example, a configuration in which a plurality of protrusions are arranged in an annular shape may be used. Further, the end face 24b is not limited to an annular end face, and may be constituted by, for example, a plurality of end faces provided intermittently in the circumferential direction. That is, the configuration of the above-described embodiment is not limited as long as the deformation can be generated in the dust seal 3 to enable long-term use.

  The adjustment of the pressing force is performed by changing the mounting position of the pressing plate in the axial direction, but is not limited thereto. For example, it can be replaced with another presser plate with a different protrusion amount, or the width and shape can be changed as well as the protrusion amount to change not only the pressing position in the axial direction but also the pressing surface and the radial pressing position. The pressing force may be adjusted by. That is, the configuration of the above-described embodiment is not limited as long as the deformation can be generated in the dust seal 3 to enable long-term use.

  In the present embodiment, as a specific application example of the sealing structure according to the present embodiment, a dust seal mounting configuration of a reciprocating rod sealing system in a hydraulic cylinder as shown in FIGS. 5 and 6 is given. The configuration to which the example can be applied is not limited to this, and can be applied to other piston sealing systems.

  In the present embodiment, the end surface 24b of the housing 2 is positioned on the outside (A) side of the end surface 24a, and the third lip 33 of the dust seal 3 is projected to the inside (O) side of the second lip 32. It is configured to be large. In this configuration, when the dust seal 3 is pushed into the inside (O) side by retightening the presser plate 23, the end face 24b comes into contact with the tip of the third lip 33 first, and the end face 24b. It is an example of the structure for generating a pressing force reliably. That is, the configuration of the above-described embodiment is not limited as long as the deformation can be generated in the dust seal 3 to enable long-term use.

(Example 2)
With reference to FIG. 4, the sealing structure based on Example 2 of this invention is demonstrated. FIG. 4 is a schematic cross-sectional view of the vicinity of the dust seal of the sealing structure according to the present embodiment. The configuration that is not particularly described here is the same as that of the first embodiment, and a description thereof is omitted.

  The sealing structure according to the present embodiment is characterized in that a secondary lip (lip-shaped portion) 31 a protruding in the inner diameter direction toward the shaft 1 is provided on the base side of the first lip 31 of the dust seal 3.

  When the deformation occurs in the dust seal 3 due to the tightening of the presser plate 23, the lip tip side of the first lip 31 is pressed against the shaft 1. At this time, the protruding direction of the sub lip 31a located on the lip base side of the first lip 31 is inclined toward the inside (O) side. As a result, a lip-shaped seal portion that is inclined and extends toward the inner (O) side is formed closer to the inner (O) side than the lip tip side of the first lip 31.

  The seal portion configured in this manner exhibits a function of scraping hydraulic oil toward the inside (O) side. That is, another oil lip is formed on the outer side (O) of the second lip 32, which is an oil lip. Therefore, the sealing performance against leakage of hydraulic oil from the inside (O) to the outside (A) is improved.

1 shaft 2 housing 20 shaft hole 21 annular groove 22 groove bottom 23 presser plate 23a side surface 23b protrusion (first pressing portion)
24a end face 24b end face (second pressing portion)
24c Projection 3 Seal member 30 Seal body 31 First lip 32 Second lip 33 Third lip 4 Annular gap

Claims (5)

The axis,
A housing having a shaft hole into which the shaft is inserted so as to be relatively movable;
A sealing member for sealing an annular gap between these two members;
A sealing structure comprising:
The sealing member is
A seal body housed in an annular groove provided in one of the two members;
A lip-shaped first seal portion that extends from the seal body toward the other member of the two members while being inclined toward the other side in the axial direction, and is in sliding contact with the other member;
A second seal portion that is in sliding contact with the other member on the other axial side than the first lip of the seal body;
A third seal portion provided on the groove bottom side of the annular groove in the seal body, and in close contact with the one member;
Have
The one member is subjected to a force that is different from each other in the radial direction and opposite to the axial direction in order to cause the seal member to be deformed so as to increase the degree of adhesion of the first seal portion to the other member. A sealing structure comprising a pressing portion configured to be able to press the sealing member and adjust the pressing force. The pressing portion is
A first pressing portion that presses the seal body from one axial side toward the other axial side;
A second pressing portion that presses the seal member from the other axial side toward the one axial side at a position closer to the bottom of the annular groove than the pressing position of the first pressing portion in the radial direction;
The sealing structure according to claim 1, comprising: The annular groove is configured to be able to change the interval between the groove side surfaces,
The first pressing portion is provided on any one of the groove side surfaces,
The sealing structure according to claim 2, wherein the second pressing portion is provided on any one of the side surfaces of the groove. The second seal portion is a lip-shaped seal portion that extends from the seal main body toward the other member while being inclined toward the other axial direction, and is in close contact with the other member,
4. The sealing structure according to claim 2, wherein the one member has a contact portion that contacts a root portion of the second seal portion from the side opposite to the other member.   5. The sealing structure according to claim 1, wherein the first seal portion includes a lip-shaped portion protruding toward the other member on a lip base side.

Images