JP2018035844A - Sealing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sealing device which can simultaneously improve dust resistance and low friction performance.SOLUTION: A sealing device 1 which is attached to an opening end of an outer tube 120 for allowing the insertion of an inner tube 110 along an axial line x so as to be retractable comprises an annular reinforcing ring 10 with the axial line x as a center, and an annular elastic body part 20 with the axial line x as a center which is composed of an elastic body integrally formed at the reinforcing ring 10. The elastic body part 20 has: a lip main body 21 attached to the opening end of the outer tube 120; a dust lip 25 having a protrusive annular lip tip 25s which is formed so as to contact with an external peripheral face of the inner tube 110; an arm-shaped lip support part 24 which is formed while extending from the lip main body 21 so as to support the dust lip 25; and a recess 27 which is formed in a prescribed point of the lip support part 24 so as to change a contact angle β with respect to an external peripheral face of the lip tip 25s while maintaining a state that the lip tip 25s contacts with the external peripheral face.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a sealing device, and more particularly to a sealing device used for a hydraulic shock absorber such as a front fork for a motorcycle.

  2. Description of the Related Art Conventionally, in a hydraulic shock absorber such as a front fork for a motorcycle, an inner tube is inserted into an outer tube so that the inner tube can freely enter and exit, and a sealing device (oil seal) is attached to the inner peripheral side of the opening end of the outer tube. ing. This sealing device prevents leakage of hydraulic oil in the outer tube (see, for example, Patent Document 1).

  As shown in FIG. 5, the sealing device 100 is mounted between the inner tube 110 and the outer tube 120 of the front fork and at the open end of the outer tube 120.

  The sealing device 100 includes a metal reinforcing ring 10 and an elastic body portion 220 made of a rubber material. The reinforcing ring 10 has an L-shaped cross section, and is a hollow disk-shaped disk part 11 and a cylinder that extends from the tip of the disk part 11 on the atmosphere side (arrow a direction) toward the outer peripheral side (arrow c direction). A flange portion 12 is provided. The sealing device 100 is fitted in a state where the flange portion 12 of the reinforcing ring 10 is positioned on the end surface 120a of the outer tube 120 on the atmosphere side (arrow a direction) via the elastic body portion 220.

  The elastic body portion 220 is integrally formed so as to entirely cover the reinforcing ring 10, and is provided on the atmosphere side (in the direction of arrow “a”), and on the airframe side (indicated by the arrow). The second dust strip 29 provided in the (b direction) is provided on the inner peripheral side (arrow d direction). The first dust lip 25 is a portion formed at the tip of an annular lip support 24 that extends from the lip main body 21 of the elastic body 220 toward the atmosphere side (in the direction of arrow a) in an arm shape when viewed in cross section.

  On the end surface on the inner peripheral side (arrow d direction) of the first dust strip 25, there is a wedge-shaped annular lip tip portion 25s whose shape in the cross section along the axis x is convex toward the inner peripheral side (arrow d direction). Is formed. Further, a concave portion is formed on the outer peripheral side (arrow c direction) end surface of the first dust strip 25, and a biasing force for pressing the lip tip portion 25s against the outer peripheral surface of the inner tube 110 is applied to the concave portion. A garter spring 26 is fitted.

  An annular lip tip portion 29s whose shape in a cross section along the axis x is convex toward the inner circumference side (arrow d direction) is formed at the tip of the second dust strip 29 on the inner circumference side (arrow d direction). Yes.

  The lip tip portion 25s of the first dust lip 25 and the lip tip portion 29s of the second dust lip 29 are in sliding contact with the outer peripheral surface of the inner tube 110 when the inner tube 110 is projected and retracted with respect to the outer tube 120. Intrusion of foreign matter (dust) from the (arrow a direction) to the machine body (arrow b direction) is doubled.

JP 2007-225067 A

  Since the sealing device 100 having the above-described configuration assumes a severe use environment, further improvement in dust resistance by the first dust strip 25 and the second dust strip 29 is required.

  Therefore, the contact pressure (stressing force) with respect to the outer peripheral surface of the inner tube 110 by the first dust strip 25 is set strongly. The contact pressure of the first dust strip 25 depends on the thickness in the horizontal direction (arrow cd direction) of the lip support 24 connecting the lip body 21 and the lip tip 25 of the elastic body 20 and the inner tube of the lip support 24. The angle of inclination with respect to the outer peripheral surface of 110 and the urging force by the garter spring 26 are set.

  As shown in FIG. 6, in the state where the sealing device 100 is mounted between the inner tube 110 and the outer tube 120, the hydraulic oil inside the outer tube 120 is outside the lip tip 25 s of the first dust lip 25. In order to prevent leakage, it is strongly pressed against the outer peripheral surface of the inner tube 110.

  In particular, since the lip support portion 24 is formed to have a rigidity that does not bend around the bending point CP1 of the lip support portion 24 in the lip main body 21, the lip support portion 24 is bent so that the inner portion of the lip support portion 24 is bent. There is no significant elastic deformation to the outer peripheral side (in the direction of arrow c) away from the outer peripheral surface of the tube 110.

  Here, the imaginary line G1 in FIG. 6 is a line that gives an image of the difficulty of bending (rigidity) of the lip support portion 24 in which the lip support portion 24 does not bend around the bending point CP1 of the lip body 21. That is, even when the lip tip portion 25s of the first dust lip 25 is pressed against the outer peripheral surface of the inner tube 110, the lip support portion 24 is not bent and is slightly elastically deformed.

  In this way, when the lip support portion 24 has strong rigidity that does not bend and the contact pressure of the lip tip portion 25s of the first dust lip 25 with the outer peripheral surface of the inner tube 110 is set strongly, the lip tip portion 25 s is the sliding resistance (high friction) of the inner tube 110.

  For this reason, in the sealing device 100, although the dust resistance by the first dust strip 25 is improved, the movement on the machine body side, that is, the movement of the inner tube 110 with respect to the outer tube 120 is hindered by the lip tip 25s. End up. Therefore, the sealing device 100 is also required to improve the low friction property without impeding the movement of the airframe side while improving the dust resistance.

  The present invention has been made in view of the above problems, and an object thereof is to provide a sealing device that can simultaneously improve dust resistance and low friction.

  In order to achieve the above object, a sealing device according to the present invention is a sealing device attached to an opening end of an outer tube that allows an inner tube to be inserted and retracted along an axis, and has an annular shape centered on the axis. And an annular elastic body portion centering on the axis formed of an elastic body formed integrally with the reinforcing ring, and the elastic body portion is a lip attached to the opening end of the outer tube. A main body, a dust lip having a convex annular lip tip formed so as to be in contact with the outer peripheral surface of the inner tube, and an arm-like shape formed extending from the lip main body so as to support the dust lip. The position of the lip support portion is changed so that the contact angle of the lip tip portion with the outer peripheral surface is changed while the lip support portion and the lip tip portion are in contact with the outer peripheral surface. And having a recess formed in places.

  In the sealing device according to an aspect of the present invention, the concave portion is formed on the inner peripheral side of the lip support portion facing the outer peripheral surface of the inner tube.

  In the sealing device according to one aspect of the present invention, the concave portion is chamfered in an R shape.

  With the sealing device according to the present invention, it is possible to realize a sealing device that can simultaneously improve dust resistance and low friction.

It is a figure which shows schematic structure of the sealing device which concerns on embodiment of this invention, FIG. 1 (A) is sectional drawing in the cross section along the axis line of a sealing device, FIG.1 (B) is FIG. It is a partial expanded sectional view of the sealing device shown to A). FIG. 2A is a diagram illustrating a usage state of the sealing device according to the embodiment of the present invention, and FIG. 2A is a partial cross-sectional view illustrating a state in which a lip tip is pressed against the outer peripheral surface of the inner tube; (B) is a partial expanded sectional view for demonstrating the contact angle of a lip front-end | tip part and the outer peripheral surface of an inner tube. It is a partial expanded sectional view which shows the state after the contact angle of the lip front-end | tip part of the 1st dust lip which concerns on embodiment of this invention, and the outer peripheral surface of an inner tube changed. It is a graph which shows the change of the contact distance and contact pressure of the sealing device of this invention and the conventional sealing device. It is a fragmentary sectional view which shows schematic structure of the conventional sealing device. It is a partial expanded sectional view which shows the contact angle of the lip tip part of the 1st dust lip in the conventional sealing device, and the outer peripheral surface of an inner tube.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing a schematic configuration of a sealing device according to an embodiment of the present invention. 1A is a cross-sectional view in a cross section along the axis of the sealing device, and FIG. 1B is a partially enlarged cross-sectional view of the sealing device shown in FIG. 1A. FIG. 2 is a diagram illustrating a usage state of the sealing device according to the embodiment of the present invention. FIG. 2A is a partial cross-sectional view showing a state where the lip tip is pressed against the outer peripheral surface of the inner tube, and FIG. 2B is an explanation of the contact angle between the lip tip and the outer peripheral surface of the inner tube. It is a partial expanded sectional view used for. FIG. 3 is a partially enlarged cross-sectional view showing a state after the contact angle between the lip tip portion of the first dust lip and the outer peripheral surface of the inner tube according to the embodiment of the present invention is changed. FIG. 4 is a chart showing changes in contact distance and contact pressure of the sealing device of the present invention and the conventional sealing device.

  Hereinafter, for convenience of explanation, in FIG. 1 and FIG. 2, in the arrow ab direction along the axis x (hereinafter, also referred to as “protrusion direction”), the atmosphere side means the direction of the arrow a along the axis x direction. The inside of the machine is the direction of the arrow b along the direction of the axis x. That is, the atmosphere side is the direction outside the outer tube 120 and facing the atmosphere. The inside of the machine is the direction inside the outer tube 120 and facing the working oil (fork oil). In the direction of arrow cd orthogonal to the axis x (hereinafter also referred to as “radial direction”), the direction away from the axis x (arrow c direction) is the outer peripheral side, and the direction approaches the axis x (arrow d direction). Is the inner circumference side.

<Configuration of sealing device>
A sealing device 1 according to an embodiment of the present invention is between an inner tube 110 (see FIG. 2A) of a front fork of a motorcycle and an outer tube 120, and at an opening end of the outer tube 120. It is attached and prevents leakage of hydraulic oil in the outer tube 120.

  As shown in FIG. 1, the sealing device 1 includes an annular metal reinforcing ring 10 centered on the axis x and an elastic body portion 20 made of an annular elastic body centered on the axis x. The elastic body portion 20 is integrally attached so as to cover the entire reinforcing ring 10.

  The reinforcing ring 10 is manufactured to have an L-shaped cross section by, for example, pressing or forging, and the elastic body portion 20 is molded by cross-linking (vulcanization) molding using a molding die. At the time of this cross-linking molding, the reinforcing ring 10 is disposed in the mold, the elastic body portion 20 is bonded to the reinforcing ring 10 by cross-linking adhesion, and the elastic body portion 20 is formed integrally with the reinforcing ring 10. .

  Examples of the metal material of the reinforcing ring 10 include stainless steel and SPCC (cold rolled steel). Examples of the elastic body of the elastic body portion 20 include various rubber materials. Examples of the various rubber materials include synthetic rubbers such as nitrile rubber (NBR), hydrogenated nitrile rubber (H-NBR), acrylic rubber (ACM), and fluorine rubber (FKM).

  The reinforcing ring 10 includes a disk part 11 and a flange part 12. The disk part 11 is a hollow disk-shaped part that extends parallel to the axis x. The flange portion 12 is a cylindrical bowl-shaped portion extending from the end of the disk portion 11 on the atmosphere side (arrow a direction) to the outer peripheral side (arrow c direction).

  The elastic body portion 20 includes a lip main body 21, a lip positioning portion 22, a fixed contact portion 23, a lip support portion 24, a first dust strip 25, and a second dust strip 29. The lip main body 21 is a main base located approximately at the center of the elastic body portion 20.

  The lip positioning portion 22 is a portion that covers the flange portion 12 of the reinforcing ring 10 from the atmosphere side (arrow a direction), and protrudes to the outer peripheral side (arrow c direction) from the fixed contact portion 23. A machine inner surface (in the direction of arrow b) 22a (hereinafter also referred to as “machine side surface”) 22a of the lip positioning portion 22 is engaged with an end surface 120a of the outer tube 120 on the atmosphere side (in the arrow a direction), and sealed. The position in the direction of appearance (arrow ab direction) when the device 1 is attached to the open end of the outer tube 120 is determined.

  The fixed contact portion 23 is a portion that is fixed in close contact with the inner peripheral surface of the outer tube 110 when the sealing device 1 is attached to the outer tube 120. On the outer peripheral side (arrow c direction) surface (hereinafter also referred to as “outer side surface”) 23m of the fixed contact portion 23, a slight trapezoidal shape is formed slightly from the outer peripheral side surface 23m to the outer peripheral side (arrow c direction). Protruding protrusions 23a and 23b are continuously provided along the axis x.

  When the sealing device 1 is fitted to the inner peripheral surface of the outer tube 120, the projecting portions 23 a and 23 b are fixed in a state where the projecting portions 23 a and 23 b are slightly crushed and abutted against the inner peripheral surface. It functions as a part that prevents internal hydraulic oil from leaking to the atmosphere side (in the direction of arrow a).

  The lip support portion 24 is a portion that connects the lip body 21 of the elastic body portion 20 and the first dust strip 25, extends from the lip body 21 of the elastic body portion 20 to the atmosphere side (in the direction of arrow a), and has an inner circumference. This is an annular portion extending in a cross-sectional view arm shape slightly inclined toward the outer peripheral surface of the inner tube 110 on the side (arrow d direction).

  The lip support portion 24 is also a portion that regulates the contact pressure with the garter spring 26 when the lip tip portion 25 s of the first dust strip 25 is pressed against the outer peripheral surface of the inner tube 110. This contact pressure is determined by the inner peripheral surface (hereinafter also referred to as “inner peripheral surface”) 24a and the outer peripheral surface (hereinafter referred to as “outer peripheral” in the radial direction (arrow cd direction) of the lip support 24. It is also set by the thickness between the surface 24b and the inclination angle of the lip support 24 with respect to the outer peripheral surface of the inner tube 110.

  The first dust lip 25 has a wedge-shaped annular lip tip portion 25s whose shape in a cross section along the axis line x is convex toward the inner peripheral side (arrow d direction) at the inner peripheral side (arrow d direction) end. Have. The lip tip 25s is slidably in close contact with the outer peripheral surface of the inner tube 110, and is formed so as to maintain a sealed state with the outer peripheral surface of the inner tube 110 in use.

  In the lip tip 25s (see FIG. 2B), the tip angle toward the lip tip is formed at α degrees. The lip tip of the lip tip 25s has an atmosphere side (arrow a direction) surface (hereinafter also referred to as “atmosphere side surface”) 25a and an airframe side opposite to the atmosphere side surface 25a (arrow b direction). (Hereinafter also referred to as “airframe side surface”) 25b.

  Here, the contact angle when the lip tip 25s of the first dust lip 25 contacts the outer peripheral surface of the inner tube 110 is made between the body side surface 25b of the lip tip 25s and the outer peripheral surface of the inner tube 110. It is defined as an angle β (hereinafter also referred to as “contact angle β”). In FIG. 2B, for convenience of explaining the contact angle β, a state in which the lip tip 25s is not crushed is displayed unlike FIG. 2A.

  In the annular recess formed on the outer peripheral side (in the direction of the arrow c) of the first dust strip 25, that is, on the back side with respect to the lip tip 25s, the lip tip 25 is arranged in the radial direction (arrow cd). A garter spring 26 that is urged toward the inner peripheral side (in the direction of arrow d) in the direction) is fitted. The urging force when the garter spring 26 presses the lip tip 25 against the outer peripheral surface of the inner tube 110 is constant.

  The second dust lip 29 is a portion provided on the airframe side (arrow b direction) with respect to the first dust lip 25. The second dust lip 29 includes an annular lip tip 29s whose shape in a cross section along the axis line x is convex toward the inner circumference (arrow d direction) at the tip on the inner circumference (arrow d direction). Yes.

  In addition to this configuration, the elastic body portion 20 is an end portion of the inner peripheral surface 24a of the lip support portion 24 on the atmosphere side (in the direction of arrow a), and is closer to the inner side (in the direction of arrow b) than the first dust strip 25. A concave portion 27 made of a concave depression is formed at a predetermined position. The recess 27 is formed in an R surface shape.

  The concave portion 27 is formed on the inner peripheral surface 24a of the lip support portion 24 of the sealing device 1 so that a predetermined position (portion) inside the machine (in the direction of the arrow b) is slightly cut away from the first dust strip 25. Has been. That is, the lip support portion 24 is formed so as to become thinner (thin) gradually when extending from the lip body 21 toward the first dust lip 25, and the concave portion 27 functions as a neck portion of the first dust lip 25. It is formed as follows.

  In this case, as shown in FIG. 3, the lip support portion 24 of the elastic body portion 20 has a rigidity that does not bend around the bending point CP <b> 1 of the lip body 21, but is formed in the lip support portion 24. Due to the presence of the concave portion 27, a new bending point CP <b> 2 is generated in the elastic body portion 20 in the vicinity of the concave portion 27 so that only the first dust seal portion 25 is bent.

  Here, the imaginary line G2 in FIG. 3 is a line that makes it imagine that the lip support portion 24 has rigidity that does not bend around the bending point CP1 of the lip body 21. On the other hand, the imaginary line G3 is a line that makes the image that the first dust strip 25 has rigidity that does not bend at any location on the atmosphere side (arrow a direction) from the bending point CP2.

<Sealing operation of the sealing device>
As shown in FIG. 3, when the sealing device 1 having such a configuration is attached to the opening end of the outer tube 120, the lip tip portion 25 s of the first dust strip 25 is pressed against the outer peripheral surface of the inner tube 110. At this time, the lip support 24 is hardly elastically deformed.

  However, since the concave portion 27 is formed between the lip support portion 24 and the first dust strip 25, the first dust strip 25 is generally opposed to the outer peripheral side (the direction of the arrow c) via the bending point CP2. Bend slightly as shown. However, since the urging force of the garter spring 26 is applied to the lip tip portion 25s, the first dust lip 25 is not separated from the outer peripheral surface of the inner tube 110 and is in surface contact. State is maintained.

  The first dust strip 25 is bent so as to be entirely warped outward (in the direction of the arrow c) via the bending point CP2, whereby the inner peripheral surface 25b (see FIG. 2B) of the lip tip 25s. Approaching the outer peripheral surface of the inner tube 110, the contact angle β (see FIG. 2B) between the inner peripheral surface 25b of the lip tip 25s and the outer peripheral surface of the inner tube 110 decreases.

  That is, as shown in FIG. 6, the first dust strip 25 of the conventional sealing device 100 is not bent, so that the length of the lip tip 25s and the outer peripheral surface of the inner tube 110 are in contact with each other (hereinafter referred to as “the following”). This is also referred to as “contact length”.) Is defined by W1. Here, the contact length W1 is a distance from a position on the inner side (arrow b direction) where the lip tip 25s is in contact with the outer peripheral surface of the inner tube 110 to a position on the atmosphere side (arrow a direction). Say.

  On the other hand, the first dust lip 25 of the sealing device 1 is bent so as to warp toward the outer peripheral side (in the direction of arrow c) via the bending point CP2, so that the inner peripheral surface 25b of the lip tip 25s and the inner tube 110 are The contact angle β with the outer peripheral surface is reduced. Therefore, the contact length W2 at which the lip tip 25s is in contact with the outer peripheral surface of the inner tube 110 is longer than the contact length W1 of the conventional sealing device 100. As a result, the contact area between the lip tip 25s and the outer peripheral surface of the inner tube 110 becomes larger than the conventional one.

  Thus, as shown in FIG. 4, the first dust strip 25 of the sealing device 1 is bent so as to warp to the outer peripheral side (in the direction of arrow c) via the bending point CP2, so that the inner tube 110 of the lip tip 25s is The contact pressure against the outer peripheral surface is slightly reduced. However, the first dust strip 25 of the sealing device 1 has a contact length W2 longer than that of the conventional sealing device 100 and also has a larger contact area, so that the dust resistance from the atmosphere side (arrow a direction) is improved. Further improvement can be achieved.

  Thereby, the dust resistance can be improved by increasing the contact area of the lip tip portion 25s while improving the low friction property without hindering the movement of the inner tube 110 by reducing the contact pressure of the lip tip portion 25s. Therefore, it is possible to realize the sealing device 1 that can simultaneously improve low friction and dust resistance, which are in a trade-off relationship with each other.

<Other embodiments>
In the above-described embodiment, the case where the concave portion 27 is formed on the inner peripheral surface 24a of the lip support portion 24 has been described. However, the present invention is not limited to this, and the tip end of the lip of the first dust strip 25 is described. If the contact angle of the portion 25s with the outer peripheral surface of the inner tube 110 can be changed, the concave portion of the outer peripheral surface 24b of the lip support portion 24 may be formed.

  The preferred embodiment of the present invention has been described above. However, the present invention is not limited to the sealing device 1 according to the above-described embodiment, and all aspects included in the concept of the present invention and the claims. including. In addition, the respective configurations may be selectively combined as appropriate so as to achieve at least part of the above-described problems and effects. For example, the shape, material, arrangement, size, and the like of each component in the above embodiment can be changed as appropriate according to the specific usage mode of the present invention.

  The case where the sealing device of the present invention is applied to a front fork of a motorcycle has been described. However, what is used for the sealing device of the present invention is not limited to a front fork of a motorcycle, but can be used for a front fork of other equipment having a similar configuration such as a front fork of a bicycle.

DESCRIPTION OF SYMBOLS 1,100 Sealing device 10 Reinforcement ring 11 Disk part 12 Cylindrical part 20, 220 Elastic body part 21 Lip body 22 Lip positioning part 23 Fixed adhesion part 24 Lip support part 24a Inner peripheral surface 24b Outer peripheral surface 25 First dust strip 25s First tip of lip Portion 26 Garter Spring 27 Recess 29 Second Dustrip 110 Inner Tube 120 Outer Tube x Axis

Claims (3)

A sealing device attached to an open end of an outer tube that allows an inner tube to be inserted and retracted along an axis,
An annular reinforcing ring centered on the axis, and an annular elastic body portion centered on the axis composed of an elastic body formed integrally with the reinforcing ring;
The elastic body part is
A lip body attached to the open end of the outer tube;
A duster strip having a convex annular lip tip formed so as to be in contact with the outer peripheral surface of the inner tube;
An arm-shaped lip support formed to extend from the lip body to support the dust lip,
A concave portion formed at a predetermined position of the lip support portion so as to change a contact angle of the lip tip portion with the outer peripheral surface while the lip tip portion is in contact with the outer peripheral surface. Sealing device. The sealing device according to claim 1, wherein the concave portion is formed on an inner peripheral side of the lip support portion facing an outer peripheral surface of the inner tube. The sealing device according to claim 1, wherein the recess is chamfered in an R shape.

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