JP6610673B2 - Dust seal - Google Patents

Description

  The present invention relates to a dust seal that seals an annular gap between a relatively reciprocating shaft and a housing to suppress entry of foreign matter.

  In various devices such as a hydraulic cylinder, a dust seal is provided in order to suppress entry of foreign matter from the outside into the device. A dust seal according to a conventional example will be described with reference to FIG. FIG. 6 is a schematic cross-sectional view of a dust seal according to a conventional example. The dust seal 200 according to this conventional example includes a metal reinforcing ring 210 and an elastic seal body 220 integrally formed with the reinforcing ring 210. An annular groove 221 that opens to the atmosphere side A is formed in the seal body 220. In addition, the seal body 220 includes a seal lip 222 on the inner peripheral surface side through the annular groove 221. Further, in the dust seal 200 according to this conventional example, a pressing member (metal spring) 230 that presses the seal lip 222 radially inward is provided in the annular groove 221. With the dust seal 200 configured as described above, it is possible to suppress entry of foreign matter from the atmosphere side A to the sealing target fluid side O.

  However, in the dust seal 200 according to the conventional example, foreign matter may accumulate in the annular groove 221. This makes it difficult for the seal lip 222 to be deformed, and when the shaft is decentered, an excessive force may be applied to the seal lip 222 to cause damage. Further, the elasticity of the pressing member 230 is impaired, and the pressing function by the pressing member 230 may be reduced. Further, the pressing member 230 may be rusted or electrolytically corroded by salt or metal powder contained in the foreign matter, and the function may be deteriorated.

JP 2009-174555 A Japanese Patent Application Laid-Open No. 2014-163459

  An object of the present invention is to provide a dust seal with improved durability.

  The present invention employs the following means in order to solve the above problems.

That is, the dust seal of the present invention is
A dust seal that seals an annular gap between the relatively reciprocating shaft and the housing and suppresses the intrusion of foreign matter,
With et provided on the inner peripheral surface side is via an annular groove that opens to the sealed fluid side, the sealed fluid side and extends radially inwardly slidably contact with the elastic body made of the outer periphery surface of said shaft With a sealing lip,
The tip of the seal lip is provided with a first inclined surface that increases in diameter toward the fluid to be sealed, and a second inclined surface that increases in diameter as it goes to the side opposite to the fluid to be sealed. The inclination angle of the two inclined surfaces is larger than the inclination angle of the first inclined surface.

  According to the present invention, since the annular groove opens on the fluid to be sealed side, foreign matter from the atmosphere side can be prevented from accumulating in the annular groove. Further, since the inclination angle of the second inclined surface is larger than the inclination angle of the first inclined surface, the foreign matter adhering to the shaft can be discharged to the atmosphere side, and the foreign matter enters the sealing target fluid side. This can be suppressed.

  A pressing member that presses the seal lip radially inward may be provided in the annular groove.

  As a result, even if the seal lip is worn down over time, the sealing function by the seal lip can be stably exhibited over a long period of time.

  As described above, according to the present invention, the durability of the dust seal can be improved.

FIG. 1 is a partially broken perspective view of a hydraulic cylinder. FIG. 2 is a schematic cross-sectional view of a sealing system according to an embodiment of the present invention. FIG. 3 is a schematic cross-sectional view of a dust seal according to an embodiment of the present invention. FIG. 4 is a plan view of an intermediate product of a metal spring according to an embodiment of the present invention. FIG. 5 is a plan view of a metal spring according to an embodiment of the present invention. FIG. 6 is a schematic cross-sectional view of a dust seal according to a conventional example.

  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)
With reference to FIGS. 1-5, the dust seal which concerns on the Example of this invention is demonstrated. The dust seal of the present invention can be used for hydraulic cylinders provided in construction machines, shock absorbers for automobiles, dampers, general industrial equipment, and the like. Hereinafter, a case where a dust seal is applied to a hydraulic cylinder will be described as an example.

<Hydraulic cylinder>
With reference to FIG. 1, the structure of the whole hydraulic cylinder provided with the dust seal which concerns on a present Example, etc. are demonstrated. FIG. 1 is a partially broken perspective view of a hydraulic cylinder. The hydraulic cylinder 100 includes a piston rod 110 as a shaft to which a piston 120 is fixed, and a cylinder 130 as a housing. The piston rod 110 and the cylinder 130 are configured to reciprocate relatively. More specifically, the piston 120 and the piston rod are controlled by controlling the oil pressure through two ports 134 and 135 provided in the cylinder 130 (controlling the oil pressure in the direction of arrow P in the figure). 110 can be reciprocated relative to the cylinder 130.

  The hydraulic cylinder 100 includes a first sealing system S10 that seals an annular gap between the piston rod 110 and the cylinder 130, and a second sealing system S20 that seals an annular gap between the piston 120 and the cylinder 130. And are provided. The first sealing system S10 seals between the inside and the outside of the hydraulic cylinder 100, and the second sealing system S20 separates two sealed regions inside the hydraulic cylinder 100.

  The first sealing system S10 mainly suppresses (prevents) leakage of the buffer portion S11 that mainly buffers the fluid pressure (here, hydraulic pressure) and the fluid to be sealed (here, oil) mainly inside the hydraulic cylinder 100 to the outside. Main seal portion S12 and dust seal portion S13 that mainly suppresses (prevents) entry of foreign matters such as dust. Examples of the foreign material include earth and sand, ore, oil, water, ice, and sap.

<First sealing system>
In particular, the first sealing system S10 will be described in more detail with reference to FIG. FIG. 2 is a schematic cross-sectional view of a sealing system according to an embodiment of the present invention. On the inner peripheral surface of the shaft hole of the cylinder 130, a first annular groove 131 and a second annular groove 132 provided on the atmosphere side A (opposite side to the sealing target fluid side O) than the first annular groove 131, Furthermore, an annular notch 133 provided on the atmosphere side A is provided. A buffer portion S11 is provided in the first annular groove 131, a main seal portion S12 is provided in the second annular groove 132, and a dust seal portion S13 is provided in the annular notch 133.

  The buffer unit S11 includes a buffer ring 10 and a backup ring 20. The main seal portion S12 includes a packing 30 and a backup ring 40. In this embodiment, a U-packing made of a rubber-like elastic body having a U-shaped cross section is adopted as the packing 30. A resin backup ring 40 is provided on the atmosphere side A of the packing 30. Thereby, it is suppressed that the inner peripheral edge of the packing 30 protrudes into a minute annular gap between the piston rod 110 and the cylinder 130. The dust seal portion S13 is configured by a dust seal 50.

  With the configuration as described above, the buffer ring 10 is disposed closer to the sealing target fluid side O than the packing 30, so that the fluid pressure (hydraulic pressure) with respect to the packing 30 can be buffered. Further, by disposing the dust seal 50 on the atmosphere side A with respect to the packing 30, it is possible to prevent foreign matters (dust, dust, etc.) from entering the packing 30 side from the outside. From the above, the durability of the packing 30 can be improved. In this embodiment, the dust seal 50 is exposed to the atmosphere.

<Dust seal>
In particular, the dust seal according to this embodiment will be described in more detail with reference to FIGS. FIG. 3 is a schematic cross-sectional view of a dust seal according to an embodiment of the present invention. FIG. 3 shows a cross-sectional view cut along a plane including the central axis of the dust seal, omitting the depth line, and showing only the cut plane. Further, in FIG. 3, in order to make it easy to understand the dimensional relationship of each member constituting the dust seal, a state in which each member is not subjected to external force is illustrated, and the members are partially overlapped. Show. FIG. 4 is a plan view of an intermediate product of the metal spring according to the embodiment of the present invention, and FIG. 5 is a plan view of the metal spring according to the embodiment of the present invention.

  The dust seal 50 includes a reinforcing ring 60 and a seal body 70 fixed to the reinforcing ring 60 by integral molding. The reinforcing ring 60 is fixed to the inner peripheral surface of a shaft hole (corresponding to the notch 133) provided in the housing (corresponding to the cylinder 130). The reinforcing ring 60 is made of metal, and includes a cylindrical portion 61 and an inward flange portion 62 that extends radially inward from the end of the cylindrical portion 61. The seal body 70 is formed with an annular groove 71 that opens to the sealing target fluid side O. The seal body 70 is provided with a seal lip 72 on the inner peripheral surface side through the annular groove 71. The seal lip 72 extends from the vicinity of the tip of the inward flange portion 62 of the reinforcing ring 60 toward the sealing target fluid side O and radially inward so as to slidably contact the outer peripheral surface of the shaft (piston rod 110). It is configured. In addition, since the seal lip 72 is required to have a function of scraping off foreign matters such as dust adhered to the outer peripheral surface of the piston rod 110, an elastic material having a relatively high rigidity (for example, a high hardness) is used as the material of the seal body 70. Rubber, urethane, resin) are used.

  Further, at the tip of the seal lip 72, a first inclined surface 72a having a diameter increasing toward the fluid to be sealed O and a second inclined surface 72b having a diameter increasing toward the atmosphere side A are provided. The inclination angle α2 of the second inclined surface 72b is set to be larger than the inclination angle α1 of the first inclined surface 72a. The first inclined surface 72a and the second inclined surface 72b according to the present embodiment are both tapered surfaces, and the latter taper angle is set to be larger. For example, the inclination angle α1 may be set to 10 ° and the inclination angle may be set to 60 °. About the 1st inclined surface 72a and the 2nd inclined surface 72b, it is also possible to make it not only a taper surface but a curved surface where a cross section turns into a curve line.

  The intersecting portion of the first inclined surface 72a and the second inclined surface 72b is preferably pointed in order to increase the surface pressure against the outer peripheral surface of the piston rod 110. In addition, when making the intersection part of this 1st inclined surface 72a and the 2nd inclined surface 72b into a curved surface (what is called R surface), it is suitable to set a curvature radius to 0.1 mm or more and 0.2 mm or less.

  In the dust seal 50 according to this embodiment, a metal spring 80 as a pressing member that presses the seal lip 72 radially inward is provided in the annular groove 71 of the seal body 70. The metal spring 80 extends radially inward and presses the outer peripheral surface of the seal lip 72 radially inward, and the radially outer groove side surface of the annular groove 71 outward in the radial direction. And a second pressing portion 82 that presses toward it. A method for manufacturing the metal spring 80 will be briefly described with reference to FIGS. First, an intermediate product 80A extending so as to meander in the circumferential direction is manufactured by cutting a metal plate (see FIG. 4). The intermediate product 80A is bent through the vicinity of the center in the radial direction so that the inner part and the outer part in the radial direction are bent in the front direction of the paper in FIG. Thereby, the metal spring 80 can be obtained. FIG. 5 shows a plan view of the metal spring 80 obtained by bending. The metal spring 80 configured as described above is mounted in the annular groove 71 in the seal body 70.

<Excellent point of dust seal according to the present embodiment>
According to the dust seal 50 according to the present embodiment, since the annular groove 71 provided in the seal body 70 opens to the sealing target fluid side O, the foreign matter from the atmosphere side A accumulates in the annular groove 71. This can be suppressed. Thereby, it is possible to suppress a problem that the seal lip 72 is hardly deformed due to the accumulation of foreign matters. Moreover, it can suppress that the elasticity of the metal spring 80 is impaired. Furthermore, even if the foreign matter contains salt or metal powder, the metal spring 80 can be prevented from rusting or electrolytic corrosion.

  At the tip of the seal lip 72 according to the present embodiment, the inclination angle α2 of the second inclined surface 72b is set to be larger than the inclination angle α1 of the first inclined surface 72a. Thereby, regarding the surface pressure with respect to the outer peripheral surface of the piston rod 110 at the tip of the seal lip 72, the surface pressure peak is biased toward the atmosphere side A, and the gradient of the atmosphere side A is more than the gradient of the fluid side O to be sealed. The surface pressure distribution increases. Therefore, the foreign matter adhering to the piston rod 110 can be discharged to the atmosphere side A, and the foreign matter can be prevented from entering the sealing target fluid side O. This point will be described in more detail. It is assumed that foreign matter is attached to the outer peripheral surface of the piston rod 110 in a film shape. In this case, when the dust seal 50 moves to the atmosphere side A with respect to the piston rod 110, the film thickness of the foreign matter adhering to the rod surface is the same as that when the dust seal 50 moves to the sealing target fluid side O with respect to the piston rod 110. It becomes thinner than the film thickness of the foreign material adhering to the rod surface. This is due to the surface pressure distribution as described above. As described above, the foreign matter adhering to the rod surface is discharged to the atmosphere side.

  In the dust seal 50 according to the present embodiment, a metal spring 80 is provided in the annular groove 71 of the seal body 70 to press the seal lip 72 radially inward. Therefore, even if the seal lip 72 is deteriorated over time, the sealing function by the seal lip 72 can be stably exhibited over a long period of time.

  As described above, according to the dust seal 50 according to the present embodiment, the dust seal 50 can be prevented from accumulating foreign matter in the annular groove 71 and the function of the metal spring 80. The durability of can be effectively improved.

DESCRIPTION OF SYMBOLS 10 Buffer ring 20 Backup ring 30 Packing 40 Backup ring 50 Dust seal 60 Reinforcement ring 61 Cylindrical part 62 Inward flange part 70 Seal body 71 Annular groove 72 Seal lip 72a First inclined surface 72b Second inclined surface 80 Metal spring 80A Intermediate product 81 1st press part 82 2nd press part 100 Hydraulic cylinder 110 Piston rod 120 Piston 130 Cylinder 131 1st annular groove 132 2nd annular groove 133 Annular notch 134,135 Port A Atmosphere side O Sealed fluid side S10 Sealing system S11 Buffer Part S12 Main seal part S13 Dust seal part S20 Sealing system α1 Inclination angle α2 Inclination angle

Claims (2)

A dust seal that seals an annular gap between the relatively reciprocating shaft and the housing and suppresses the intrusion of foreign matter,
With et provided on the inner peripheral surface side is via an annular groove that opens to the sealed fluid side, the sealed fluid side and extends radially inwardly slidably contact with the elastic body made of the outer periphery surface of said shaft With a sealing lip,
The tip of the seal lip is provided with a first inclined surface that increases in diameter toward the fluid to be sealed, and a second inclined surface that increases in diameter as it goes to the side opposite to the fluid to be sealed. The dust seal characterized in that the inclination angle of the two inclined surfaces is larger than the inclination angle of the first inclined surface.   The dust seal according to claim 1, wherein a pressing member that presses the seal lip radially inward is provided in the annular groove.

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