JP4288772B2 - Sealing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sealing device used for a fluid pressure cylinder or the like, and more particularly to a sealing device such as a double pressure piston seal that receives the pressure of a sealing fluid from both sides.
[0002]
[Prior art]
Conventionally, in a fluid pressure cylinder or the like that introduces a high-pressure sealed fluid into the cylinder, an annular clearance between the outer peripheral surface of the piston that slides in the axial direction under the pressure of the sealed fluid from both sides in the cylinder and the inner peripheral surface of the cylinder A piston seal is provided for the purpose of sealing.
[0003]
As described above, piston seals used in portions to which pressure from both directions is applied have various cross-sectional shapes (for example, O-type, rectangular-type, X-type, etc.) according to the required performance. .
[0004]
FIG. 5 is a cross-sectional configuration explanatory view of the piston seal 101 made of such a double-pressure type rubber-like elastic body disclosed in Japanese Utility Model Laid-Open No. 62-128277.
[0005]
The piston seal 101 seals the annular gap 104 between the inner peripheral surface of the cylinder 102 and the outer peripheral surface of the piston 103, and is accommodated in a concave groove 103 a formed on the outer peripheral surface of the piston 103.
[0006]
The cross-sectional shape of the piston seal 101 is substantially X-shaped, and outer peripheral lips 105a and 105b and inner peripheral lips 106a and 106b are formed. Grooves 107a and 107b are provided on the end faces 108 and 109 in the axial direction of the piston seal 101 so as to divide the outer peripheral lip and the inner peripheral lip.
[0007]
Reference numerals 110a and 110b denote radial grooves for introducing the pressure of the sealing fluid into the grooves 107a and 107b.
[0008]
When the dimensional relationship among the outer peripheral lips 105a and 105b and the inner peripheral lips 106a and 106b and the grooves 107a and 107b is the outer peripheral lip interference allowance α, the inner peripheral lip interference allowance β, and the groove width γ, γ− (Α + β) = δ (difference) = 0.1 mm to 0.5 mm.
[0009]
FIG. 6 shows a state in which the piston seal 101 is accommodated in the concave groove 103a on the outer peripheral surface of the piston 103. Each lip is deformed and the grooves 107a and 107b exist as narrow gaps.
[0010]
[Problems to be solved by the invention]
However, in the piston seal 101 accommodated in the concave groove 103a as shown in FIG. 6, since the grooves 107a and 107b still exist as narrow gaps, for example, when the pressure of the sealing fluid is applied from above the annular gap 104 in the figure. The gap on the pressure side groove 107a increases, and the rubber-like elastic body of the lip is deformed so that the groove 107b on the counter pressure side fills the groove 107b.
[0011]
As a result, the rubber-like elastic body around the groove 107b moves in the direction of the groove 107b in order to fill the groove 107b, so that tensile stress is generated inside the lip. As the difference δ increases (maximum of 0.5 mm in the case of the piston seal 101 in FIG. 6), the tensile stress around the groove 107b also increases, and the stress is concentrated under use conditions in which the impact pressure is repeatedly input. There is a possibility that breakage such as cracks is likely to occur at the bottom of the groove where it is easy to occur.
[0012]
The present invention solves the above-described problems of the prior art, and an object of the present invention is to provide a sealing device that is not easily damaged by repeated input of pressure and that exhibits stable sealing performance over a long period of time. It is in.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, the present invention is arranged in an annular holding part between two opposing surfaces in which a sealing fluid having a pressure is involved, and extends in the opposite direction from the connecting part to the two opposing parts. Two first lip portions that abut one side of the surface, and two second lip portions that extend in opposite directions from the connection portion and abut against the other side of the two opposing surfaces, and the first opposing lip portions And a circumferential groove provided between the lip portion and the second lip portion, wherein the second lip is defined by α as a fastening margin with respect to one of the two opposing surfaces of the first lip portion. The groove width γ is set to be smaller than the interference margin α + β of the first lip portion and the second lip portion, where β is the interference allowance for the other of the two opposing surfaces of the portion and γ is the groove width of the circumferential groove. In addition, the inner and outer peripheral surfaces of the connecting portion respectively contact the two opposing surfaces. Set to, sealing device, characterized by a state of surroundings always closing said circumferential groove so that the compressed state of the circumferential grooves by placing between the 2 opposing surface.
[0014]
In this way, by setting the groove width of the circumferential groove and the interference margin of the lip portion, the circumferential groove of the sealing device can be placed between the two opposing surfaces in a closed state, and the circumference of the circumferential groove is Always in a compressed state.
[0015]
The lip portion and the circumferential groove on the side receiving the pressure of the sealing fluid are in a compressed state around the circumferential groove, and the lip portion on the side where the pressure of the sealing fluid is applied from the opposite side is the circumferential direction. The groove is closed and pressed into the annular holding portion, but in order to fill the circumferential groove, the members around the circumferential groove are not moved and deformed in the circumferential groove direction. The generation of tensile stress is suppressed.
[0016]
Therefore, the stress of the member around the circumferential groove is not a state of both compressive and tensile stresses, but is always a stress fluctuation in the compressed state, hardly damaged by repeated input of pressure, and stable for a long time. Sealing performance can be exhibited.
[0017]
It is also preferable to provide a pressure introduction groove that guides the sealing fluid from the end face of the first lip part or the second lip part to the groove bottom part of the circumferential groove.
[0018]
The pressure of the sealing fluid can be introduced to the groove bottom portion of the circumferential groove closed by the pressure introduction groove, and the expansion force of the lip portion can be increased according to the pressure, and the sealing performance can be enhanced.
[0019]
It is also preferable that a plurality of minute protrusions are provided in parallel to the lip portion between at least one of the lip tip portions of the two first lip portions or between the lip tip portions of the two second lip portions. It is.
[0020]
With these minute protrusions, the sealing fluid can be held between the facing surface, the lubricity can be increased to suppress friction, and the sliding resistance between the facing surface and the lip portion can be reduced.
[0021]
The connecting portion includes a contact surface that is parallel to the two opposing surfaces,
The first lip part and the second lip part have an inclined surface that inclines toward the facing surface abutting from the connecting portion and continues to the lip tip,
The cross-sectional shape of the microprojections provided on the inclined surfaces of the first lip portion and the second lip portion is such that the contact angle with the facing surface on the side toward the lip tip is the contact surface on the side toward the connecting portion. Is an asymmetrical mountain shape set larger than the contact angle of
It is also preferable that the cross-sectional shape of the minute protrusion provided in the connection portion is a substantially symmetrical mountain shape.
[0022]
By providing the microprotrusions in this way, the microprotrusions provided on the inclined surfaces of the first lip portion and the second lip portion function to prevent leakage of the sealing fluid from the tip of the lip toward the connecting portion, and are provided at the connecting portion. The formed microprotrusions function to form a lubricating film of the sealing fluid and hold the sealing fluid. It is also preferable that the lip tip portions of the first lip portion and the second lip portion are rounded.
[0023]
It is no longer necessary to cut the lip tip at the time of molding, and the manufacturing process of the sealing device can be simplified and the cost can be reduced.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a diagram illustrating a cross-sectional configuration of an annular sealing device 1 to which the present invention is applied. Since the sealing device 1 is axisymmetric, only a cross section on one side is shown in FIG. In the figure, the left side is the outer peripheral side and the right side is the inner peripheral side.
[0025]
This sealing device 1 seals the annular gap 4 between the inner peripheral surface 2a of the cylinder 2 and the outer peripheral surface 3a of the piston 3 as two opposing surfaces as shown in FIG. Sealing fluid such as oil is repeatedly applied from both directions like pressures P1 and P2 to move the piston 3.
[0026]
An annular holding portion 3b having a rectangular cross section is formed on the outer peripheral surface 3a of the piston 3 over the entire circumference, and the sealing device 1 is disposed on the annular holding portion 3b. The outer peripheral side of the sealing device 1 is a sliding surface with respect to the inner peripheral surface 2 a of the cylinder 2.
[0027]
The sealing device 1 is integrally formed with a rubber-like elastic body in a free state (FIG. 1) so as to have a substantially X-shaped cross section, and extends in a direction opposite to the axial direction from a connecting portion 11 located in the center in the axial direction. Two first lip portions 12, 13 that contact the inner peripheral surface 2a of the cylinder 2, and two second lip portions 14, that extend from the connection portion 11 in opposite directions in the axial direction and contact the bottom surface of the annular holding portion 3b. 15, and first and second lip portions 12 and 14 that face each other, and circumferential grooves 16 and 17 that are provided between the first and second lip portions 13 and 15 that face each other.
[0028]
The connecting portion 11 is about 1/3 of the axial length of the sealing device 1, the connecting portion outer peripheral surface 11a is in light contact with the inner peripheral surface 2a of the cylinder 2, and the connecting portion inner peripheral surface 11b is an annular holding portion 3b. It is set so as to lightly contact the bottom surface of the.
[0029]
The first lip portions 12 and 13 protrude to the outer peripheral side so as to rise toward the lip tip portions 12a and 13a, and reliefs 12c and 13c for preventing biting into the annular gap 4 are provided on the outer peripheral sides of the end surfaces 12b and 13b. It has been.
[0030]
The lip tip portions 12a and 13a are rounded, so that it is not necessary to cut the lip tip portion during molding.
[0031]
Further, the end faces 12b and 13b have pressure introduction grooves 12d and 13d for introducing pressure into the circumferential grooves 16 and 17 that are closed, and pressure introduction grooves 12d and 13d and circumferential grooves at a plurality of locations in the circumferential direction. Nozzle portions 12e and 13e for guiding the sealing fluid to the circumferential grooves 16 and 17 are provided at the boundary between the end portions 16 and 17 (inner peripheral sides of the end faces 12b and 13b).
[0032]
The second lip portions 14, 15 have lip tip portions 14 a, 15 a that project inwardly on the inner peripheral side, and the boundary between the end surfaces 14 b, 15 b and the circumferential grooves 16, 17 (the end surfaces 14 b, 15 b Nozzle portions 14c and 15c for guiding the sealing fluid to the circumferential grooves 16 and 17 are provided on the outer peripheral side.
[0033]
Pressure introducing grooves 14d and 15d connected from the end faces 14b and 15b of the second lip parts 14 and 15 to the groove bottoms of the circumferential grooves 16 and 17 are provided.
[0034]
FIG. 3 is a diagram illustrating the configuration of the pressure introducing grooves 13d and 15d to the circumferential groove 17. 3A is a V1-V1 arrow view of FIG. 1, FIG. 3B is a C1-C1 cross-sectional view of FIG. 3A, and FIG. 3C is V2-V2 of FIG. FIG. 3D is a cross-sectional view taken along the line C2-C2 of FIG. 3C.
[0035]
The pressure introducing grooves 13d and 15d lead the sealing fluid from the side where the pressure introducing grooves 13d and 15d exist to the circumferential groove 17, and when the pressure is applied from the opposite side, the sealing fluid is discharged from the circumferential groove 17. It becomes a route.
[0036]
Further, the interference amount of the first lip portions 12 and 13 with respect to the inner peripheral surface 2a of the cylinder 2 is defined as α, and the interference amount of the second lip portions 14 and 15 with respect to the bottom surface of the annular holding portion 3b is defined as β. When the groove width of 17 is γ, the groove width γ is set smaller than the interference allowance α + β of the first lip portions 12 and 13 and the second lip portions 14 and 15.
[0037]
Accordingly, the circumferential grooves 16 and 17 are closed as shown in FIG. 2 in a state where the sealing device 1 is disposed in the annular holding portion 3b.
[0038]
As described above, by setting the groove width γ of the circumferential grooves 16 and 17 and the interference margin α + β of the lip portion, the periphery of the circumferential grooves 16 and 17 of the sealing device 1 is always in a compressed state.
[0039]
For example, in FIG. 2, when the pressure P1 acts as the pressure of the sealing fluid, the first lip portion 12, the second lip portion 14 and the circumferential groove 16 on the side receiving the pressure P1 are The surrounding compression state becomes a more compressed state.
[0040]
The sealing fluid having the pressure P1 proceeds from the pressure introduction groove 12d toward the circumferential groove 16 to the area surrounded by the nozzle portion 12e and the nozzle portion 14c, and pushes the closed circumferential groove 16 in a closed state. And enter into the groove.
[0041]
Further, the pressure introduction groove 14d connected from the end face 14b of the second lip part 14 to the groove bottom part of the circumferential groove 16 assists the entry of the sealing fluid into the circumferential groove 16, and the pressure side first is in accordance with the pressure. The expansion force of the lip portion 12 and the second lip portion 14 can be increased, and the sealing performance can be improved.
[0042]
The first lip portion 13 and the second lip portion 15 on the side where the pressure of the sealing fluid is applied from the opposite side is in a state in which the circumferential groove 17 is closed and is in pressure contact with the circumferential wall surface of the annular holding portion 3b. In order to fill 17, the rubber-like elastic body around the circumferential groove 17 does not move and deform in the direction of the circumferential groove 17, and the generation of tensile stress is suppressed inside the lip portion.
[0043]
Accordingly, in both the pressure-side and counter-pressure-side circumferential grooves 16 and 17, the stress of the rubber-like elastic body around them is not in both the compression state and the tension state, but is always in the compression state. Fluctuates and is not easily damaged by repeated input of pressure, and can exhibit a stable sealing performance over a long period of time.
[0044]
Even if the direction in which the pressure is applied is changed, the same effect is exhibited in the opposite lip portion and the circumferential groove.
[0045]
FIG. 4 is an enlarged view of the first lip portion 12 and the connection portion outer peripheral surface 11a. A plurality of minute protrusions 18a, 18b, 18c, 19a, 19b,... Are provided in the sliding region S1 between the lip tip portions 12a, 13a serving as sliding surfaces with respect to the inner peripheral surface 2a of the cylinder 2. 12a and 13a are provided in parallel.
[0046]
The first lip portion 12 has an inclined surface 12f that is inclined (in a free state) to the inner peripheral surface 2a side that contacts the connecting portion 11 and continues to the lip tip portion 12a (the second lip 13 is also the same). Is).
[0047]
The cross-sectional shape of the microprotrusions 18a, 18b, 18c on the inclined surface 12f is the contact angle K1 with the inner peripheral surface 2a on the side facing the lip front end 12a (from the microprotrusion tip to the microprojection slope and the inner peripheral surface 2a). Is an asymmetrical mountain shape in which the angle between the contact surface 11 and the inner peripheral surface 2a facing the connecting portion 11 is set larger than the contact angle K2. Similarly, the second lip portion 13 side has a larger contact angle on the side toward the lip tip portion 13a side.
[0048]
Moreover, the cross-sectional shape of the microprotrusions 19a, 19b... Provided in the connecting portion 11 is a substantially symmetrical mountain shape.
[0049]
By forming the minute projections 18a, 19a and the like, the sealing fluid can be held as a lubricating film between the inner peripheral surface 2a which is the opposing surface, and the friction is suppressed by increasing the lubricity, and the inner peripheral surface 2a The sliding resistance with the lip portion can be reduced.
[0050]
Further, by setting the contact angle of the minute projections provided on the inclined surfaces of the first lip portion 12 and the second lip portion 13 as shown in FIG. 4, the sealing fluid from the lip tip portion 12a toward the connection portion 11 is set. .., Provided on the connecting portion 11 to form a lubricating film of the sealing fluid and hold the sealing fluid, thereby further sealing the sealing device 1. Slidability can be improved.
[0051]
In the above description, the two opposing surfaces on which the sealing device 1 is disposed have been described as the sliding surfaces of the cylinder inner periphery and the piston outer periphery, but the two first lips and the two second lips are opposite in the radial direction. The present invention can also be applied to sliding surfaces that extend in the direction and face each other in the thrust direction, and a device that generates a pressure difference in the radial direction can also be sealed.
[0052]
【The invention's effect】
As described above, by applying the present invention, it is possible to obtain a sealing device that is not easily damaged by repeated input of pressure and that exhibits a stable sealing performance over a long period of time.
[0053]
In other words, the stress of the member around the circumferential groove does not become both a compressive and tensile stress state, but is always a stress fluctuation in the compressed state, hardly breaks against repeated input of pressure, and is stable over a long period of time. Sealing performance can be exhibited.
[0054]
The pressure of the sealing fluid can be introduced to the groove bottom portion of the circumferential groove closed by the pressure introduction groove, and the expansion force of the lip portion can be increased according to the pressure, thereby improving the sealing performance.
[0055]
With the minute protrusions, the sealing fluid can be held between the facing surface, the lubricity can be increased to suppress friction, and the sliding resistance between the facing surface and the lip portion can be reduced.
[0056]
By specifying the cross-sectional shape of the microprotrusions, the microprotrusions provided on the inclined surfaces of the first lip and the second lip function function to prevent leakage of the sealing fluid from the lip tip toward the connecting portion. The provided microprotrusions function to form a sealing fluid lubricating film and hold the sealing fluid.
[0057]
By making the lip tip portions of the first lip portion and the second lip portion into a round shape, it is not necessary to cut the lip tip portion at the time of molding, and the manufacturing process of the sealing device can be simplified and the cost can be reduced. it can.
[Brief description of the drawings]
FIG. 1 is a cross-sectional configuration explanatory diagram of a sealing device according to an embodiment.
FIG. 2 is a cross-sectional configuration explanatory diagram in which the sealing device according to the embodiment is arranged in an annular holding portion.
FIG. 3 is an explanatory view of a pressure introducing groove.
FIG. 4 is an explanatory diagram of minute protrusions provided on a lip portion.
FIG. 5 is a cross-sectional view of a conventional sealing device.
FIG. 6 is a view showing a state in which a conventional sealing device is mounted.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Sealing device 2 Cylinder 2a Inner peripheral surface 3 Piston 3a Outer peripheral surface 3b Annular holding part 4 Annular gap 11 Connection part 12, 13 First lip part 12a, 13a Lip tip part 12b, 13b End face 12c, 13c Escape 12d, 13d Pressure introduction Grooves 12e, 13e Nozzle portion 12f Inclined surfaces 14, 15 Second lip portions 14a, 15a Lip tip portions 14b, 15b End surfaces 14c, 15c Nozzle portions 14d, 15d Pressure introducing grooves 16, 17 Circumferential grooves 18a, 19a Micro projections α, β interference allowance γ groove width P1, P2 pressure K1, K2 contact angle S1 sliding region

Claims (5)

Arranged in an annular holding part between two opposing surfaces involving a sealing fluid having pressure,
Two first lip portions extending in opposite directions from the connecting portion and contacting one side of the two opposing surfaces;
Two second lip portions extending in opposite directions from the connecting portion and contacting the other side of the two opposing surfaces;
Circumferential grooves provided between the first lip portion and the second lip portion facing each other;
In a sealing device comprising:
The fastening margin for one side of the two opposing surfaces of the first lip portion is α,
The fastening margin for the other side of the two opposing surfaces of the second lip portion is β,
When the groove width of the circumferential groove is γ,
The groove width γ is set smaller than the interference margin α + β of the first lip portion and the second lip portion , and
The inner and outer peripheral surfaces of the connection part are set so as to abut on the two opposing surfaces, respectively .
The sealing device characterized in that the circumferential groove is closed so that the periphery of the circumferential groove is always compressed by being disposed between the two opposing surfaces. 2. The sealing device according to claim 1, further comprising a pressure introducing groove that guides a sealing fluid from an end face of the first lip portion or the second lip portion to a groove bottom portion of the circumferential groove. A plurality of minute projections are provided in parallel to the lip portion between at least one of the lip tip portions of the two first lip portions or between the lip tip portions of the two second lip portions. The sealing device according to claim 1 or 2. The connecting portion includes a contact surface that is parallel to the two opposing surfaces,
The first lip part and the second lip part have an inclined surface that inclines toward the facing surface abutting from the connecting portion and continues to the lip tip,
The cross-sectional shape of the microprojections provided on the inclined surfaces of the first lip portion and the second lip portion is such that the contact angle with the facing surface on the side toward the lip tip is the contact surface on the side toward the connecting portion. Is an asymmetrical mountain shape set larger than the contact angle of
The sealing device according to claim 3, wherein a cross-sectional shape of the minute protrusion provided in the connection portion is a substantially symmetrical mountain shape. The sealing device according to any one of claims 1 to 4, wherein lip tips of the first lip portion and the second lip portion are rounded.

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