JP6685504B2 - Sealing device - Google Patents

Description

  The present invention relates to a sealing device, and more particularly to a sealing device mounted on a hydraulic shock absorber (shock absorber) of an automobile or a motorcycle.

  Conventionally, in a shock absorber, particularly a single-cylinder shock absorber, the inside of one cylinder is divided into an oil chamber and a gas chamber by a free piston, and a piston rod moves in the oil chamber and enters the oil chamber. Oil equivalent to the volume of the piston rod pushes down the free piston and compresses the gas chamber to generate a damping force.

  In such a single-cylinder shock absorber, a sealing device is provided to seal the outer peripheral surface of the piston rod and prevent the hydraulic oil inside the cylinder from leaking from the outer peripheral surface of the piston rod to the outside. .

  As shown in FIGS. 4 and 5, a conventional sealing device 100 includes a reinforcing ring 103, a seal lip portion 101 integrally formed with the reinforcing ring 103, and a dust lip portion 102 integrally formed with the reinforcing ring 103. Is equipped with.

  The reinforcing ring 103 is made of a metal annular member, and is present on the caulking portion 110a formed by bending the opening end of the cylinder 110 of the single-cylinder shock absorber, and on the sealing target side (direction of arrow a) with respect to the caulking portion 110a. It is sandwiched between the rod guide 115.

  The seal lip portion 101 is a portion integrally formed so as to cover the end surface 103a of the reinforcing ring 103 on the sealing target side (direction of arrow a), and has an outer peripheral side lip 101a and an inner peripheral side lip 101b. The outer peripheral lip 101a is a portion that seals between the inner peripheral surface 110a of the cylinder 110 and the outer peripheral surface 115a of the rod guide 115. The inner peripheral lip 101b is a lip portion that is slidably and liquid-tightly contacted with the outer peripheral surface 120a of the piston rod 120 when the sealing device 100 is mounted.

  The dust lip portion 102 is a portion integrally formed so as to cover the end surface 103b of the reinforcing ring 103 on the atmosphere side (direction of arrow b). The dust lip portion 102 is provided on the atmosphere side (direction of arrow b) with respect to the seal lip portion 101, and is a lip portion slidably and liquid-tightly contacted with the outer peripheral surface 120a of the piston rod 120 when the sealing device 100 is mounted. Is.

  When the sealing device 100 having such a configuration is mounted between the cylinder 110 and the piston rod 120, the inner peripheral lip 101a of the seal lip portion 101 contacts the outer peripheral surface 120a of the piston rod 120 with an appropriate tightening margin. To be done. As a result, the sealing device 100 prevents the hydraulic oil inside the cylinder 110 from flowing out from the outer peripheral surface 120a of the piston rod 120 to the atmosphere side (arrow b direction).

  However, in recent years, in the single-cylinder shock absorber, the hydraulic pressure F of the hydraulic oil inside the cylinder 110 is applied to the rear surface portion of the inclined slope of the inner peripheral lip 101a as the pressure of the high-pressure gas is increased. Then, at the same time, the component force Fa in the direction parallel to the back surface portion (slope) acts, and at the same time, the component force Fb in the direction perpendicular to the back surface portion (slope) acts.

  Due to the presence of this component force Fb, the inner peripheral side lip 101a is pressed against the outer peripheral surface 120a of the piston rod 120, the contact area between the inner peripheral side lip 101a and the outer peripheral surface 120a of the piston rod 120 increases, and the inner peripheral side The tense force of the lip 101a increases. As a result, so-called gouging wear occurs in which the contact portion of the inner peripheral side lip 101a with increased tightening force is gouged by friction, and the sealing performance of the sealing device 100 becomes unstable.

  Therefore, as a measure for preventing the occurrence of such gouging wear, a sealing device in which a backup ring is added to the seal lip portion 101 has been proposed (for example, refer to Patent Document 1).

  As shown in FIG. 6, the sealing device 150 includes reinforcement rings 151 and 153 each formed of a metal annular member, a seal lip portion 152 integrally formed with the reinforcement ring 151, and a dust lip portion 156 integrally formed with the reinforcement ring 153. , And a backup ring 160 attached to the inner peripheral side (direction of arrow d) of the seal lip portion 152.

  The seal lip 152 is integrally formed so as to cover the reinforcing ring 151 from the sealing target side (the direction of the arrow a), and the outer peripheral seal lip 152a that seals by contacting with the inner peripheral surface of the cylinder (not shown) and the piston rod (not shown). An inner peripheral side seal lip 152b that slidably contacts the outer peripheral surface to seal the outer peripheral surface.

  On the inner peripheral side (arrow d direction) end surface of the inner peripheral seal lip 152b, a wedge-shaped annular lip tip portion 152bs whose shape in a cross section along the axis x is convex toward the inner peripheral side (arrow d direction). Are formed. A garter spring 154, which applies a biasing force for pressing the lip tip portion 152bs to the outer peripheral surface of the piston rod, is attached to the recess formed in the rear surface portion on the outer peripheral side (in the direction of arrow c) of the inner peripheral seal lip 152b. ing.

  The backup ring 160 is arranged in an annular recess formed on the inner peripheral side (arrow d direction) of the inner seal lip 152b and on the atmosphere side (arrow b direction) with respect to the lip tip portion 152bs. It is mounted in a state of being sandwiched between the peripheral side seal lip 152b and the end surface of the reinforcing ring 153 on the sealing target side (direction of arrow a).

  Therefore, even if the inner peripheral side lip 152b is pressed against the outer peripheral surface of the piston rod by the hydraulic pressure of the hydraulic oil in the cylinder, the inner peripheral surface of the backup ring 160 contacts the outer peripheral surface of the piston rod, As described above, the inner peripheral lip 152b is not pressed against the outer peripheral surface of the piston rod. Therefore, it is possible to prevent the contact area between the inner peripheral lip 152b and the outer peripheral surface of the piston rod from increasing.

JP, 2008-309263, A

  However, according to the sealing device 150 of Patent Document 1 described above, although it is possible to effectively suppress an increase in the contact area between the inner peripheral side lip 152b and the outer peripheral surface of the piston rod by the backup ring 160, the backup is concerned. Since the ring 160 is added, the number of parts is increased, the structure is complicated, and the manufacturing cost is increased.

  The present invention has been made in view of the above problems, and an object thereof is to provide a simple structure and a low cost sealing device capable of suppressing an increase in a contact area between a seal lip and a shaft.

  In order to achieve the above object, a sealing device according to the present invention is an elastic body including an annular reinforcing ring having an axis as a center and an annular elastic body having the axis as a center and integrally formed with the reinforcing ring. A lip formed on the lip body so that the elastic body slidably contacts the outer peripheral surface of the shaft to be sealed and the lip body extending in the direction along the axis. An annular seal lip having a tip portion, and an annular protrusion provided adjacent to the seal lip and protruding in a direction along the axis, the protrusion being orthogonal to the axis. A ceiling portion having a flat ceiling surface parallel to the direction, and a neck portion that supports the ceiling portion in a direction along the axis and is formed so as to be bendable in a direction orthogonal to the axis. Holding, the ceiling portion of the protrusion is the shaft When pushed down toward the outer peripheral surface, the ceiling part bends in a direction orthogonal to the axis through the neck part, and a part of the ceiling part is on the back side of the lip tip part. It is characterized in that an annular space is formed in contact with the back surface of the main body.

  In the sealing device according to one aspect of the present invention, when the annular space is formed, a back surface portion of the lip body is covered by the ceiling portion.

  In the sealing device according to one aspect of the present invention, the elastic body portion has a dust lip provided on the atmosphere side of the seal lip so as to slidably contact the outer peripheral surface of the shaft. And

  ADVANTAGE OF THE INVENTION According to this invention, the simple structure which can suppress increase of the contact area of a seal lip and a shaft, and a low-cost sealing device can be implement | achieved.

It is sectional drawing which shows the state with which the sealing device which concerns on embodiment of this invention was mounted between the piston rod and the cylinder. It is an expanded sectional view showing composition of a sealing device concerning an embodiment of the invention. It is a partial expanded sectional view showing a state when a projection of a sealing device concerning an embodiment of the invention and the back of an inner circumference side seal lip contact, and an annular space is formed. It is sectional drawing which shows the state with which the conventional sealing device was mounted between the piston rod and the cylinder. It is an expanded sectional view which shows the structure of the conventional sealing device. It is an expanded sectional view showing the composition of the conventional sealing device with which the backup ring was attached.

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

  FIG. 1 is a sectional view showing a state in which a sealing device according to an embodiment of the present invention is mounted between a piston rod and a cylinder. FIG. 2 is an enlarged cross-sectional view showing the configuration of the sealing device according to the embodiment of the present invention. FIG. 3 is a partially enlarged cross-sectional view showing a state in which the projection of the sealing device according to the embodiment of the present invention and the back surface of the inner peripheral side seal lip are in contact with each other to form an annular space.

  Hereinafter, for convenience of description, in FIGS. 1 to 3, in the arrow ab direction along the axis x (hereinafter, also referred to as “stroke direction”), the sealing target side is the arrow a along the axis x direction. And the atmosphere side is the direction of arrow b along the direction of the axis x. That is, the side to be sealed is the direction inside the cylinder 110 and facing the hydraulic oil. The atmosphere side is the direction outside the outer tube 120 and facing the atmosphere. Further, in the arrow cd direction orthogonal to the axis x (hereinafter, also referred to as “radial direction”), the outer peripheral side is the arrow c direction away from the axis x, and the inner peripheral side is the arrow d approaching the axis x. Direction.

<Structure of sealing device>
As shown in FIGS. 1 and 2, a sealing device 1 according to an embodiment of the present invention is mounted between a cylinder 110 and a piston rod 120, and in particular, seals an outer peripheral surface 120a of the piston rod 120 to form a cylinder 110. This is to prevent leakage of hydraulic oil inside.

  The sealing device 1 includes a metal-made reinforcing ring 2 centered on the axis x, and an elastic body portion 3 made of an annular elastic body centered on the axis x. The elastic body portion 3 covers the entire reinforcing ring 2 from the sealing target side (arrow a direction), the outer peripheral surface side (arrow c direction), the inner peripheral surface side (arrow d direction), and the atmosphere side (arrow d direction). It is attached as one. However, the elastic body portion 3 completely covers the end surface 2a of the reinforcing ring 2 on the sealing target side (arrow a direction), but does not cover the inner surface of the reinforcing ring 2 on the atmosphere side (arrow b direction). Only part of the side (direction of arrow d) is covered.

  The reinforcing ring 2 is manufactured to have a rectangular cross section by, for example, pressing or forging, and the elastic body portion 3 is molded by cross-linking (vulcanization) using a molding die. During this cross-linking molding, the reinforcing ring 2 is arranged in the molding die, the elastic body portion 3 is bonded to the reinforcing ring 2 by cross-linking adhesion, and the elastic body portion 3 is molded integrally with the reinforcing ring 2. .

  Examples of the metal material of the reinforcing ring 2 include stainless steel and SPCC (cold rolled steel). Examples of the elastic body of the elastic body portion 3 include various rubber materials. Examples of various rubber materials are synthetic rubbers such as nitrile rubber (NBR), hydrogenated nitrile rubber (H-NBR), acrylic rubber (ACM), and fluororubber (FKM).

  The elastic body portion 3 is formed on an annular seal lip portion 4 that covers the reinforcing ring 2 from the sealing target side (direction of arrow a), and on the atmosphere side of the seal lip portion 4 (direction of arrow b). An annular dust lip portion 5 is provided to cover the air from the atmosphere side (direction of arrow b).

  The seal lip portion 4 includes an outer peripheral side lip 31, an inner peripheral side lip 32, and a protrusion 33. The outer peripheral side lip 31 is a lip portion extending from the outer peripheral side (arrow c direction) end of the reinforcing ring 2 toward the sealed target side (arrow a direction) in the stroke direction (arrow ab direction) along the axis x. A convex lip tip portion 31a that slidably contacts and seals the inner peripheral surface 110a of the cylinder 110 is formed on the outer peripheral side (arrow c direction) end surface of the outer peripheral lip 31.

  The inner peripheral side lip 32 as a seal lip extends from the inner peripheral side (arrow d direction) end of the reinforcing ring 2 toward the sealed side (arrow a direction) in the stroke direction (arrow ab direction) along the axis x. The lip main body 321 and a lip tip 322 integrally formed on the inner peripheral side (arrow d direction) end surface of the lip main body 321. The lip tip 322 is formed in an annular wedge shape whose cross-section along the axis x is convex from the inner peripheral side (arrow d direction) end surface of the lip main body 321 toward the inner peripheral side (arrow d direction). ing.

  The lip body portion 321 is continuous with the back surface 323, which is the back side (outer peripheral side (direction of arrow c)) of the lip tip portion 322, the lip tip portion 322, and the back surface 323, and is radially (arrow cd direction). It has a parallel and flat ceiling surface 324 along it. The back surface 323 is an inclined surface that is inclined from the ceiling surface 324 toward the reinforcing ring 2 toward the outer peripheral side (direction of arrow c).

  The projecting portion 33 is formed between the outer peripheral side lip 31 and the inner peripheral side lip 32 and adjacent to the inner peripheral side lip 32 at a position separated from the inner peripheral side lip 32 by a predetermined distance. It is a protruding portion that protrudes toward the sealed target side (arrow a direction) in the stroke direction (arrow ab direction) along the axis x.

  The protrusion 33 includes a ceiling portion 331 and a neck portion 339. The ceiling portion 331 is an annular portion having a flat ceiling surface 332 parallel to the radial direction (arrow cd direction) orthogonal to the axis x.

  The projecting portion 33 has a flat inner peripheral side end surface (hereinafter, also referred to as “inner peripheral side end surface”) that is parallel to the direction orthogonal to the ceiling surface 332, that is, the stroke direction (arrow ab direction) along the axis x. 334, an end surface on the outer peripheral side that is parallel and flat to the inner peripheral end surface 334 (hereinafter, also referred to as “outer peripheral side end surface”) 335, and an inclined surface 336 connecting the ceiling surface 332 and the outer peripheral side end surface 335. Have The inclined surface 336 is formed in parallel with the inner peripheral side inclined surface 116a of the convex portion 116 protruding in a trapezoidal shape protruding from the rod guide 115 (see FIG. 1) toward the atmosphere (in the direction of arrow b).

  The neck portion 339 is an annular portion formed so that the ceiling portion 331 can be bent in the radial direction (arrow cd direction) orthogonal to the axis x, and supports the ceiling portion 335 in the direction along the axis x. Here, the neck portion 339 has an outer diameter D2 smaller than the outer diameter D1 of the ceiling portion 331 in the radial direction (arrow cd direction). As a result, an outer peripheral side constricted portion 33pg and an inner peripheral side constricted portion 33pi are formed between the ceiling portion 331 and the neck portion 339. The outer peripheral side constricted portion 33pg is formed to be substantially conical in a substantially semicircular shape toward the inner peripheral side (arrow d direction). On the other hand, the inner peripheral side constricted portion 33pi is formed so as to be constricted to the outer peripheral side (arrow c direction) smaller than the outer peripheral side constricted portion 33pg.

  The dust lip portion 5 is a lip portion extending from an end portion on the inner peripheral side (arrow d direction) of the reinforcing ring 2 to the atmosphere side (arrow b direction) in the stroke direction (arrow ab direction) along the axis x. A convex lip tip portion 5a that slidably contacts and seals the outer peripheral surface 120a of the piston rod 120 is formed on the end surface of the dust lip portion 5 on the inner peripheral side (arrow d direction).

<Action and effect>
When the sealing device 1 having such a configuration is mounted between the piston rod 120 and the cylinder 110, the inner peripheral lip 32 of the seal lip portion 4 contacts the outer peripheral surface 120a of the piston rod 120 with an appropriate tightening margin. To be done. As a result, the sealing device 1 can prevent the hydraulic oil inside the cylinder 110 from flowing out from the outer peripheral surface 120a of the piston rod 120 to the atmosphere side (direction of arrow b).

  When the sealing device 1 is mounted, as shown in FIG. 3, the inclined surface 336 of the protruding portion 33 of the seal lip portion 4 abuts on the inner peripheral side inclined surface 116a of the protruding portion 116 of the rod guide 115, and the protruding portion The protrusion 33 is pushed by the inner peripheral side (arrow d direction) in the radial direction (arrow cd direction) orthogonal to the axis x by 116.

  In this case, the protrusion 33 bends due to the presence of the neck portion 339 so as to fall toward the inner peripheral side (direction of arrow d), and the inner peripheral side end surface 334 of the relevant protrusion 33 is the sealing target side of the back surface 323 of the inner peripheral side lip 32. It comes into contact with the end portion (in the direction of arrow a). As a result, the inner peripheral side constricted portion 33pi of the protrusion 33 and the back surface 323 of the inner peripheral side lip 32 form an annular space IC closed in the seal lip portion 4, and the rear surface 323 of the inner peripheral side lip 32 is formed. It is hidden by the ceiling portion 331 of the protrusion 33.

  As a result, the hydraulic pressure of the hydraulic oil in the cylinder 110 rises in accordance with the operation of the piston rod 120, and even when the hydraulic pressure F is applied to the ceiling surface 332 of the ceiling portion 331 of the protrusion 33, the inner peripheral side The hydraulic pressure F is not applied to the inclined surface that is the back surface 323 of the lip 32.

  Therefore, unlike the conventional case, the component force Fb (see FIG. 4) that presses the inner peripheral side lip 32 against the outer peripheral surface 120a of the piston rod 120 by the hydraulic pressure F does not act, and the inner peripheral side lip 32 and the piston. It is possible to suppress an increase in the contact area with the outer peripheral surface 120a of the rod 120. Thus, the sealing device 1 can prevent the inner peripheral side lip 101a from being gouged and wear and stabilize the sealing performance.

  In addition, the sealing device 1 does not use the conventional backup ring 160 or the like, but the presence of the protrusion 33 integrally formed with the outer peripheral side lip 31 and the inner peripheral side lip 32 of the seal lip portion 4 makes it possible to achieve the above-described operational effects. As a result, it is possible to prevent deterioration of the sealability and maintain stable sealing performance with a simple structure.

  Thus, it is possible to realize the sealing device 1 having a simple structure and a low cost, which can suppress an increase in the contact area between the inner peripheral side seal lip 32 and the outer peripheral surface 120a of the piston rod 120.

<Other Embodiments>
In addition, in the above-mentioned embodiment, although the case where the protrusion 33 is integrally formed adjacent to the inner lip 32 is described, the present invention is not limited to this, and the inner lip 32 of the inner lip 32 is not limited to this. If the back surface 323 can be covered by the ceiling portion 331 of the protrusion 33, the inner peripheral lip 32 and the protrusion 33 may be formed separately.

  Further, in the above-described embodiment, the case where the protrusion 33 is provided adjacent to the inner peripheral side lip 32 as the seal lip has been described, but the present invention is not limited to this, and the outer peripheral side as the seal lip. The protrusion 33 may be provided adjacent to the lip 31, and the protrusion 33 may be provided on both the inner peripheral lip 32 and the outer peripheral lip 33.

  Although the preferred embodiment of the present invention has been described above, the present invention is not limited to the sealing device 1 according to the above-mentioned embodiment, and all aspects included in the concept of the present invention and the scope of claims. including. Further, the respective configurations may be appropriately and selectively combined so as to achieve at least a part of the problems and effects described above. For example, the shape, material, arrangement, size, etc. of each constituent element in the above-described embodiment can be appropriately changed depending on the specific usage mode of the present invention.

  The sealing device of the present invention has been described for the case of being applied to a hydraulic shock absorber of an automobile or a motorcycle. However, what uses the sealing device of the present invention is not limited to this, it is mounted between the piston rod and the cylinder, and is used as a hydraulic buffer for various other vehicles and industrial machines that are affected by the hydraulic pressure in the cylinder. It can be used as a container.

1, 100 Sealing device 2 Reinforcement ring 3 Elastic body part 4 Seal lip part 5 Dustrip part 5a Lip tip part 23 Fixed contact part 24 Lip support part 24a Inner peripheral surface 24b Outer peripheral surface 25 First dust lip 25s Lip tip part 26 Garter Spring 27 Recess 29 Second dust lip 31 Outer peripheral lip 31a Lip tip 32 Inner peripheral lip (seal lip)
33 protrusion part 33pg outer peripheral side constricted part 33pi inner peripheral side constricted part 110 cylinder 115 rod guide 116 convex part 116a inner peripheral side inclined surface 120 piston rod (shaft)
120a Inner peripheral surface 321 Lip body 322 Lip tip 323 Back surface 324 Ceiling surface 331 Ceiling portion 332 Ceiling surface 334 Inner peripheral end surface 335 Outer peripheral end surface 336 Inclined surface 339 Neck portion x Axis

Claims (3)

An annular reinforcing ring centered on the axis,
An elastic body portion formed of an annular elastic body integrally formed with the reinforcing ring around the axis is provided,
The elastic body portion,
An annular seal lip having a lip body extending in a direction along the axis, and a lip tip formed on the lip body so as to slidably contact an outer peripheral surface of a shaft to be sealed,
An annular protrusion that is provided adjacent to the seal lip and protrudes in a direction along the axis,
The protrusion is
A ceiling portion having a flat ceiling surface that is parallel to the direction orthogonal to the axis;
The ceiling portion is supported in a direction along the axis, and the ceiling portion has a neck portion formed so as to be bendable in a direction orthogonal to the axis,
When the ceiling portion of the protrusion is pressed toward the outer peripheral surface of the shaft, the ceiling portion bends in a direction orthogonal to the axis through the neck portion, and a part of the ceiling portion is A sealing device, which is brought into contact with a back surface of the lip main body portion, which is a back side of a lip tip portion. An annular space is formed between the ceiling portion and the lip body portion when a part of the ceiling portion is in contact with the back surface of the lip body portion, and the back surface of the lip body portion is hidden by the ceiling portion. The sealing device according to claim 1, wherein: The said elastic body part has a dust lip provided in the atmospheric side rather than the said seal lip so that it may slidably contact with the outer peripheral surface of the said shaft. apparatus.

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