JP5304057B2 - Sealing device and sealing structure - Google Patents

Description

  The present invention relates to a sealing device having a bearing function and a sealing structure including the same.

  2. Description of the Related Art A sealing system composed of a plurality of members is known as a sealing device (piston or rod sealing device) used for high pressure. For example, in a hydraulic cylinder for construction machinery, a piston sealing system including a piston seal and a wear ring is used. Such a conventional sealing device will be described with reference to FIG. FIG. 4 is a schematic cross-sectional view of a sealing structure according to a conventional example.

  The piston sealing system is disposed in an annular gap between an inner peripheral surface of a shaft hole 601 provided in the cylinder 600 and an outer peripheral surface of the piston 500 inserted through the shaft hole 601. The outer circumferential surface of the piston 500 is provided with a first annular groove 501, a second annular groove 502 and a third annular groove 503 provided on both sides in the axial direction across the first annular groove 501. Yes.

  The central first annular groove 501 is made of a first ring 100 made of a hard material such as nylon, and a rubber-like elastic body such as NBR that presses the first ring 100 toward the inner peripheral surface of the shaft hole 601. A piston seal comprising the second ring 200 is attached. Wear rings 301 and 302 made of a hard material such as nylon are attached to the second annular groove 502 and the third annular groove 503, respectively. These wear rings 301 and 302 are provided as bearings for the piston 500, and are provided for preventing the piston 500 and the cylinder 600 from being galled, reducing eccentricity, and improving the durability of the piston seal. .

  As described above, by using the piston sealing system including the piston seal and the pair of wear rings provided on both sides thereof, the sealing function and the bearing function can be stably exhibited over a long period of time even at high pressure. .

  However, in such a piston sealing system, the number of parts is large and the cost becomes high. Therefore, it is required to realize a sealing device that can reduce the cost while maintaining the same quality while reducing the number of parts. In view of this, in the sealing device according to the conventional example, in order to reduce the number of parts, a technique for providing the first ring 100 with a bearing function is considered. Such a technique will be described with reference to FIG. FIG. 5 is a schematic cross-sectional view of a sealing structure according to virtual technology.

  In the sealing structure shown in FIG. 5, a first annular groove 511 and a second annular groove 512 provided on the groove bottom surface of the first annular groove 511 are formed on the outer peripheral surface of the piston 510. A first ring 110 made of a hard material such as nylon is attached to the first annular groove 511, and the first ring 110 is pressed against the inner peripheral surface of the shaft hole 601 in the second annular groove 512, such as NBR. A second ring 210 made of a rubber-like elastic body is attached.

  The first ring 110 in this virtual technology is based on the idea of integrating the first ring 100 and the pair of wear rings 301 and 302 in the conventional example. According to this virtual technique, a sealing function is particularly exerted in the vicinity of the first ring 110 being pressed by the second ring 210. In the first ring 110, a portion disposed between the bottom surface of the first annular groove 511 (a portion excluding the region where the second annular groove 512 is provided) and the inner peripheral surface of the shaft hole 601. In particular, the bearing function is exhibited. That is, the wear ring function is exhibited in this portion.

  According to the piston seal ring configured as described above, the sealing function is exhibited near the center of the first ring 110 and the bearing function is exhibited on both sides thereof, as in the case of the conventional example.

  Here, since the first ring 110 is made of a hard material, the first ring 110 is compressed between the groove bottom surface of the first annular groove 511 and the inner peripheral surface of the shaft hole 601. The first ring 110 cannot be mounted in the first annular groove 511. If so, the sliding resistance between the first ring 110 and the inner peripheral surface of the shaft hole 601 becomes too high. Therefore, it is necessary to provide a clearance S1 between the inner peripheral surface of the first ring 110 and the groove bottom surface of the first annular groove 511 in consideration of dimensional errors and the like.

  Since the first ring 110 hardly deforms, the clearance S1 remains at a substantially constant interval regardless of whether or not the pressure of the fluid to be sealed is acting.

On the other hand, when the second ring 200 made of a rubber-like elastic body receives the pressure of the fluid to be sealed, it moves to the low pressure side in the second annular groove 512 and deforms itself. For this reason, part of the second ring 200 may protrude into the clearance S1 and be damaged. As a related technique, there is one disclosed in Patent Document 1.
JP-A-9-177987

  An object of the present invention is to provide a sealing device having a bearing function and a sealing structure including the same, having a small number of parts and excellent quality.

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

That is, the sealing device of the present invention is
A sealing device that seals an annular gap between an inner peripheral surface of a shaft hole provided in a housing and an outer peripheral surface of a shaft inserted through the shaft hole, and serves as a bearing that supports the shaft,
A first annular groove provided concentrically with the shaft center of the shaft and a second annular groove provided concentrically with the shaft center are formed on the groove bottom surface of the first annular groove on the outer peripheral surface of the shaft. And
A first ring made of a hard material, mounted in the first annular groove and slidable with respect to the first annular groove;
A second ring made of a rubber-like elastic body that is attached to the second annular groove and presses the first ring toward the inner peripheral surface of the shaft hole;
The first ring is configured to enter the second annular groove, and is in close contact with the side wall surface of the second annular groove by sliding the first ring due to the pressure of the fluid to be sealed. An annular convex portion that is provided concentrically with the shaft center is provided to prevent the second ring from protruding into the gap therebetween.

The sealing structure of the present invention is
A housing having a shaft hole;
A shaft inserted through the shaft hole;
A sealing device that seals an annular gap between the inner peripheral surface of the shaft hole and the outer peripheral surface of the shaft and serves as a bearing that supports the shaft;
A first annular groove provided concentrically with the shaft center of the shaft and a second annular groove provided concentrically with the shaft center are formed on the groove bottom surface of the first annular groove on the outer peripheral surface of the shaft. And
The sealing device includes:
A first ring made of a hard material, mounted in the first annular groove and slidable with respect to the first annular groove;
A second ring made of a rubber-like elastic body that is attached to the second annular groove and presses the first ring toward the inner peripheral surface of the shaft hole;
The first ring is configured to enter the second annular groove, and is in close contact with the side wall surface of the second annular groove by sliding the first ring due to the pressure of the fluid to be sealed. An annular convex portion that is provided concentrically with the shaft center is provided to prevent the second ring from protruding into the gap therebetween.

  According to the sealing device and the sealing structure of the present invention, a sealing function is particularly exerted in the vicinity of the first ring pressed by the second ring. Of the first ring, a bearing is particularly provided at a portion disposed between the bottom surface of the first annular groove (a portion excluding the region where the second annular groove is provided) and the inner peripheral surface of the shaft hole. Function is demonstrated. Thereby, according to this invention, the function as a bearing which supports an axis | shaft can be exhibited with two rings, exhibiting the sealing function which seals an annular clearance. Therefore, the number of parts can be reduced.

  According to the present invention, since the first ring is provided with the annular convex portion, the first ring slides when the pressure by the fluid to be sealed is received, and the side wall surface of the annular convex portion is the second annular groove. It adheres to the side wall surface. Thereby, it can suppress (prevent) that a part of 2nd ring protrudes into the clearance gap between a 1st ring and a axis | shaft. Therefore, stable sealing performance can be maintained, and quality and durability can be improved.

Further, both sides of the axial direction across said annular protrusion in the first ring are all together is also disposed between the inner circumferential surface of the groove bottom and the shaft hole of the first annular groove, of the two side A clearance is provided between the portion and the bottom surface of the first annular groove.

  As a result, the bearing function is exerted at both portions in the axial direction across the portion where the sealing function is exhibited. Thereby, a sealing function can be exhibited stably.

  Further, a groove for introducing a fluid to be sealed may be provided on an outer peripheral surface of a portion of the first ring disposed between the groove bottom surface of the first annular groove and the inner peripheral surface of the shaft hole.

  Thereby, sliding resistance can be reduced, maintaining the stable sealing performance.

  In addition, said each structure can be employ | adopted combining as possible.

  As described above, according to the present invention, it is possible to improve quality while reducing the number of parts.

  The best mode for carrying out the present invention will be exemplarily described in detail below 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. .

  In a present Example, the case of the piston sealing system used for the hydraulic cylinder for construction machines is shown as an example of a sealing device.

Example 1
With reference to FIG.1 and FIG.2, the sealing device which concerns on Example 1 of this invention and a sealing structure provided with the same are demonstrated. FIG.1 and FIG.2 is typical sectional drawing of a sealing structure provided with the sealing device which concerns on Example 1 of this invention. 1 shows a state in which the pressure of the fluid to be sealed is not acting, and FIG. 2 shows a state in which the pressure of the fluid to be sealed is acting.

<Sealing structure>
The sealing device (piston sealing system) according to the present embodiment includes an inner peripheral surface of a shaft hole 61 provided in a cylinder 60 serving as a housing and an outer peripheral surface of a piston 50 serving as a shaft inserted through the shaft hole 61. It arrange | positions in the cyclic | annular clearance gap between. The sealing device according to the present embodiment includes a first ring 10 made of a hard material such as nylon and a second ring 20 made of a rubber-like elastic body such as NBR. As a material of the first ring 10, in addition to nylon, a laminated material such as polyamide, polyimide, PEEK, polyacetal, polyethylene, polyester, phenol, cloth-containing phenol, and PTFE can be given as examples. Of course, a filler (additive) may be added in order to improve frictional wear characteristics, strength, and the like. Moreover, as a material of the 2nd ring 20, HNBR, XNBR, FKM, and urethane other than NBR can be mentioned as an example. Of course, a filler (additive) may be added in order to improve frictional wear characteristics, strength, and the like.

  A first annular groove 51 provided concentrically with the axis T of the piston 50 on the outer peripheral surface of the piston 50, and a second annular groove provided concentrically with the axis T on the groove bottom surface of the first annular groove 51. 52 is formed. In the present embodiment, the second annular groove 52 is provided at the center of the first annular groove 51 in the axial direction.

  The first ring 10 is attached to the first annular groove 51, and the second ring 20 is attached to the second annular groove 52. The second ring 20 presses the first ring 10 toward the inner peripheral surface of the shaft hole 61 by its own elastic repulsive force.

  In the present embodiment, an annular convex portion 11 configured to enter the second annular groove 52 is provided on the inner peripheral side of the first ring 10. The annular convex portion 11 is provided concentrically with the axis T of the piston 50.

  Here, the outer diameter of the first ring 10 is set to be substantially the same as the inner diameter of the shaft hole 61 so that the outer peripheral surface of the first ring 10 slides on the inner peripheral surface of the shaft hole 61. . The first ring 10 is dimensioned to fit in the first annular groove 51. Furthermore, the dimension of the annular convex portion 11 is such that the annular convex portion 11 provided in the first ring 10 fits in the second annular groove 52 in a state where the first ring 10 is fitted in the first annular groove 51. Is set. Specifically, the axial length of the first ring 10 is substantially equal to the axial length of the first annular groove 51, and the inner diameter of the portion of the first ring 10 excluding the annular convex portion 11 is the first annular groove 51. The axial length of the annular convex portion 11 is set to be substantially equal to the axial length of the second annular groove 52, being substantially equal to the outer diameter of the groove bottom portion. In addition, the height of the annular convex portion 11 is set to a height that slightly enters the second annular groove 52.

  However, since the first ring 10 is made of a hard material, the first ring 10 is compressed between the groove bottom surface of the first annular groove 51 and the inner peripheral surface of the shaft hole 61. The 1 ring 10 cannot be mounted in the first annular groove 51. If so, the sliding resistance between the first ring 10 and the inner peripheral surface of the shaft hole 61 becomes too high. Wearability and dimensional errors must also be considered.

Therefore, between the inner peripheral surface of the first ring 10 and the groove bottom surface of the first annular groove 51, between the side wall surface of the annular protrusion 11 and the side wall surface of the second annular groove 52, and on the first ring 10 side. Clearances S1, S2, and S3 are provided between the wall surface and the side wall surface of the first annular groove 51, respectively. However, in order to exert a sealing function, the clearance is set so that there is no clearance between the outer peripheral surface of the first ring 10 and the inner peripheral surface of the shaft hole 61.

<Sealing operation by the sealing device>
In FIG. 2, the right side in the drawing shows a high pressure, and the left side shows a low pressure. In this case, the first ring 10 and the second ring 20 receive the pressure (hydraulic pressure) of the fluid to be sealed (oil in this embodiment) on the high pressure side (H), and both slide to the low pressure side (L) ( In FIG. 2, it slides in the direction of arrow A). Since the 1st ring 10 is comprised with a hard material, even if it receives the pressure of the fluid to be sealed, it hardly deforms. Therefore, the clearance S1 between the inner peripheral surface of the first ring 10 and the groove bottom surface of the first annular groove 51 remains at a substantially constant interval.

  However, when the first ring 10 moves to the low pressure side (L), the side wall surface of the annular convex portion 11 in the first ring 10 is in close contact with the side wall surface of the second annular groove 52. Thereby, the clearance gap between the side wall surface of the cyclic | annular convex part 11 and the side wall surface of the 2nd annular groove 52 is lose | eliminated (refer the part shown by the arrow X in the figure). Therefore, the second ring 20 can be prevented from protruding into the clearance S <b> 2 between the side wall surface of the annular protrusion 11 and the side wall surface of the second annular groove 52. In addition, even when the left side in the drawing becomes high pressure and the right side becomes low pressure, the same behavior is exhibited (the right side wall surface in the drawing of the annular convex portion 11 is in close contact with the right side wall surface of the second annular groove 52. ).

  In addition, when the first ring 10 slides under the pressure of the fluid to be sealed, the clearance S3 is set so that the side wall surface of the annular convex portion 11 is more closely attached to the side wall surface of the second annular groove 52. It is desirable to set the length to be greater than the clearance S2.

<Excellent points of this embodiment>
According to the sealing device (piston sealing system) and the sealing structure including the same according to the present embodiment, the sealing function is particularly exhibited in the vicinity of the first ring 10 being pressed by the second ring 20. And the part distribute | arranged between the groove bottom face (the part except the area | region in which the 2nd annular groove 52 is provided) of the 1st annular groove 51 and the internal peripheral surface of the shaft hole 61 among the 1st rings 10. In particular, the bearing function is exhibited.

  Thus, according to the sealing device and the sealing structure including the sealing device according to the present embodiment, the function as a bearing for supporting the piston 50 is exhibited while the sealing function for sealing the annular gap is exhibited by the two rings. be able to. Therefore, the number of parts can be reduced.

  In addition, as described above, by providing the annular protrusion 11 on the first ring 10, the first ring 10 slides when the pressure by the fluid to be sealed is received, and the side wall surface of the annular protrusion 11 is the second. It is in close contact with the side wall surface of the annular groove 52. Thereby, it can suppress (prevent) that a part of 2nd ring 20 protrudes into the clearance gap between the 1st ring 10 and piston 50. FIG. Therefore, stable sealing performance can be maintained, and quality and durability can be improved.

  In the present embodiment, both the axially opposite portions of the first ring 10 sandwiching the annular protrusion 11 are between the groove bottom surface of the first annular groove 51 and the inner peripheral surface of the shaft hole 61. The arrangement is used. Therefore, the bearing function is exhibited at both portions in the axial direction with the portion where the sealing function is exhibited. Thereby, a sealing function can be exhibited stably.

(Example 2)
FIG. 3 shows a second embodiment of the present invention. In a present Example, the structure in the case of providing the groove | channel which introduce | transduces the sealing object fluid in the outer peripheral surface of a 1st ring is shown. Since other configurations and operations are the same as those in the first embodiment, the same components are denoted by the same reference numerals and description thereof is omitted.

  FIG. 3 is a schematic cross-sectional view of a sealing structure including a sealing device according to Embodiment 2 of the present invention. FIG. 3 shows a state where the pressure (hydraulic pressure) of the fluid to be sealed (oil) is not acting. In addition, (V) in FIG. 3 has shown a part of figure which looked at the 1st ring in the sealing device which concerns on Example 2 of this invention to the axial direction.

  In the sealing device (piston sealing system) according to the first embodiment, the area of the sliding portion with respect to the inner peripheral surface of the shaft hole becomes larger than in the case of the piston sealing system shown in the conventional example. Therefore, the sliding resistance tends to be high.

  Therefore, in the first ring 10a according to the present embodiment, the fluid to be sealed (oil) is applied to the outer peripheral surface of the portion disposed between the groove bottom surface of the first annular groove 51 and the inner peripheral surface of the shaft hole 61. Grooves 12 and 13 to be introduced are provided. In the present embodiment, a plurality of these grooves 12 and 13 are provided at regular intervals in the circumferential direction. However, the arrangement position, number, shape, size, and the like of the grooves may be appropriately set according to the size, material, usage environment, and the like of the first ring. The configuration is the same as that of the first embodiment except that these grooves 12 and 13 are provided.

  As described above, in this embodiment, the grooves 12 and 13 are provided on the outer peripheral surface of the first ring 10a, so that the object to be sealed is interposed between the outer peripheral surface of the first ring 10a and the inner peripheral surface of the shaft hole 61. Oil, which is a fluid, is introduced. Therefore, the sliding resistance between the outer peripheral surface of the first ring 10a and the inner peripheral surface of the shaft hole 61 can be reduced.

(Other)
In the above embodiments, as shown in FIGS. 1 to 3, the second ring 20 has a rectangular cross-sectional shape. However, the second ring 20 can seal the annular gap between the groove bottom surface of the second annular groove 52 and the inner peripheral surface of the first ring 10, and the first ring 20 by its own elastic repulsive force. What is necessary is just to exhibit the function which presses 10 and 10a toward the internal peripheral surface of the shaft hole 61. FIG. Therefore, the cross-sectional shape is not limited to a rectangular shape, and an appropriate shape such as a circle or an ellipse can be adopted.

  Moreover, about the 1st rings 10 and 10a which consist of hard materials, the thing of a type which does not have a cutting part in any location of the circumferential direction can also be employ | adopted, and in order to improve mounting property, the circumferential direction It is also possible to adopt a type in which one or a plurality of points are cut. As a specific example of the cutting part in the latter case, a step cut or a special step cut can be adopted.

In addition, a configuration in which an introduction path for guiding the fluid to be sealed (oil) more reliably to the inside of the second annular groove 52 can be employed. Specifically, in the first rings 10 and 10 a, the fluid to be sealed (oil) is applied to the inner peripheral surface of the portion disposed between the groove bottom surface of the first annular groove 51 and the inner peripheral surface of the shaft hole 61. A configuration in which a groove to be introduced is provided can be employed. Moreover, the structure which provides the groove | channel which introduce | transduces the fluid (oil) for sealing into the side wall surface and groove bottom face of the 1st annular groove 51 is also employable. Furthermore, the structure which provides the groove | channel which introduce | transduces the sealing object fluid (oil) also into the side wall surface of the 2nd ring 20 is also employable. By adopting these configurations, the fluid to be sealed (oil) can be more reliably guided into the second annular groove 52. This makes it possible to suppress blow-through leakage (passing). That is, generally, in the case of a combined seal consisting of a first ring made of a hard material and a second ring made of a rubber-like elastic body, the second ring exerts an expansion force by fluid pressure (hydraulic pressure) during pressurization. By obtaining, it has a mechanism that can achieve sealing performance even at high pressure. For that purpose, it is necessary to introduce the fluid to be sealed (oil) into the groove in which the second ring is mounted. Therefore, as described above, by appropriately providing grooves in each part of each member, the fluid to be sealed (oil) is more reliably guided into the second annular groove 52, so that the expansion force of the second ring 20 can be further increased. It becomes possible to obtain reliably. As a result, it is possible to stably obtain a sealing property, and to suppress blowout leakage.

  Moreover, in Example 2, in order to reduce sliding resistance, although the structure in the case of providing a groove | channel in the outer peripheral surface of the 1st ring 10a was shown, in order to hold | maintain the oil which is a sealing object fluid on the said outer peripheral surface. Sliding resistance can be reduced by providing a plurality of dimples (holes).

1 is a schematic cross-sectional view of a sealing structure including a sealing device according to Embodiment 1 of the present invention. FIG. 2 is a schematic cross-sectional view of a sealing structure including the sealing device according to Embodiment 1 of the present invention. FIG. 3 is a schematic cross-sectional view of a sealing structure including a sealing device according to Embodiment 2 of the present invention. FIG. 4 is a schematic cross-sectional view of a sealing structure according to a conventional example. FIG. 5 is a schematic cross-sectional view of a sealing structure according to virtual technology.

Explanation of symbols

10, 10a 1st ring 11 Annular convex part 12, 13 Groove 20 Second ring 50 Piston 51 1st annular groove 52 2nd annular groove 60 Cylinder 61 Shaft hole S1, S2, S3 Clearance T Axis center

Claims (4)

A sealing device that seals an annular gap between an inner peripheral surface of a shaft hole provided in a housing and an outer peripheral surface of a shaft inserted through the shaft hole, and serves as a bearing that supports the shaft,
A first annular groove provided concentrically with the shaft center of the shaft and a second annular groove provided concentrically with the shaft center are formed on the groove bottom surface of the first annular groove on the outer peripheral surface of the shaft. And
A first ring made of a hard material, mounted in the first annular groove and slidable with respect to the first annular groove;
A second ring made of a rubber-like elastic body that is attached to the second annular groove and presses the first ring toward the inner peripheral surface of the shaft hole;
The first ring is configured to enter the second annular groove, and is in close contact with the side wall surface of the second annular groove by sliding the first ring due to the pressure of the fluid to be sealed. to prevent protrusion of the second ring into the gap between the axis and the annular projection which is concentrically arranged are provided,
The portions on both sides in the axial direction across the annular convex portion in the first ring are both arranged between the groove bottom surface of the first annular groove and the inner peripheral surface of the shaft hole, A sealing device characterized in that a clearance is provided between the bottom surface of the first annular groove . A groove for introducing a fluid to be sealed is provided on an outer peripheral surface of a portion of the first ring disposed between the groove bottom surface of the first annular groove and the inner peripheral surface of the shaft hole. The sealing device according to claim 1 . A housing having a shaft hole;
A shaft inserted through the shaft hole;
A sealing device that seals an annular gap between the inner peripheral surface of the shaft hole and the outer peripheral surface of the shaft and serves as a bearing that supports the shaft;
A first annular groove provided concentrically with the shaft center of the shaft and a second annular groove provided concentrically with the shaft center are formed on the groove bottom surface of the first annular groove on the outer peripheral surface of the shaft. And
The sealing device includes:
A first ring made of a hard material, mounted in the first annular groove and slidable with respect to the first annular groove;
A second ring made of a rubber-like elastic body that is attached to the second annular groove and presses the first ring toward the inner peripheral surface of the shaft hole;
The first ring is configured to enter the second annular groove, and is in close contact with the side wall surface of the second annular groove by sliding the first ring due to the pressure of the fluid to be sealed. to prevent protrusion of the second ring into the gap between the axis and the annular projection which is concentrically arranged are provided,
The portions on both sides in the axial direction across the annular convex portion in the first ring are both arranged between the groove bottom surface of the first annular groove and the inner peripheral surface of the shaft hole, A sealing structure characterized in that a clearance is provided between the bottom surface of the first annular groove . A groove for introducing a fluid to be sealed is provided on an outer peripheral surface of a portion of the first ring disposed between the groove bottom surface of the first annular groove and the inner peripheral surface of the shaft hole. The sealing structure according to claim 3 .

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