JP3564932B2 - Sealing device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a sealing device for sealing a gap between a shaft of various devices and a housing. In particular, it relates to a configuration in which one sealing device can cope with bidirectional rotation.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, resin materials such as PTFE, which has better heat resistance and wear resistance than rubber-like elastic materials, have been applied to sealing lips for rotating shafts used under high-speed, high-pressure, and high-temperature conditions. . However, the resin material is inferior in elastic restoring property as compared with the rubber-like elastic material, and has a low ability to follow the shaft runout (eccentricity following ability).
[0003]
FIG. 3 is a diagram illustrating a cross-sectional configuration of the sealing device 101 using a resin material as the material of the seal lip. In the sealing device 101, an outer reinforcing ring 102 and an inner reinforcing ring 103 having an L-shaped cross section into which the outer rings 102a and 103a are fitted, and an outer peripheral fixing portion 104a is sandwiched between radial portions 102b and 103b of the reinforcing rings. The annular plate 104 is made of a resin material.
[0004]
The inner diameter of the annular plate 104 is set smaller than the diameter of the rotating shaft 105 inserted into the inner annular portion of the sealing device 101, and is deformed to the sealed fluid side M along the outer peripheral surface of the rotating shaft 105, The inner peripheral surface of the inner diameter tip side of the inner surface 104 is slidably contacted with the lip sliding surface 104b.
[0005]
The lip sliding surface 104b is provided with a spiral groove 104c in one direction, and the sealing performance is improved by the effect of returning the sealed fluid to the sealed fluid side M by the pump action of the spiral groove 104c generated as the rotating shaft 105 rotates. The structure to be made has been conventionally adopted.
[0006]
[Problems to be solved by the invention]
However, in the sealing device 101, when the rotating shaft 105 is rotated in the other direction, leakage of the sealing fluid occurs, and the sealing device 101 is applicable to a shaft rotating in one direction, but is applicable to a shaft rotating in both directions. There was a problem that I could not do it.
[0007]
Further, in the sealing device 101 of FIG. 3, since the sealed fluid side M and the atmosphere side O communicate with each other by the spiral groove 104c, the sealed fluid is statically leaked through the spiral groove 104c when the rotating shaft 1 is stationary. There were also problems.
[0008]
The present invention has been made in order to solve the above-mentioned problems of the prior art, and has an object to provide a function of returning a sealed fluid to a sealed fluid side with respect to bidirectional rotation, and to provide a sliding surface. It is an object of the present invention to provide a sealing device capable of improving the sealing performance by preventing static leakage of a sealing fluid when the device is stopped.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, there is provided a sealing device having an annular lip sliding portion abutting on a rotating sliding surface,
The lip sliding portion includes, in each of the contact pressure distributions with respect to the sliding surface, an annular contact portion in which a maximum contact pressure portion has a distribution form deviated more toward the sealed fluid side than the atmosphere side, and is formed in a plurality of stages in the axial direction. It is characterized by having.
[0010]
According to this, when the sliding surface with which the lip sliding portion abuts is rotating, the contact pressure distribution form of each annular abutment has a maximum contact pressure point on the sealed fluid side of the annular abutment. When the sealed fluid flows out to the atmosphere side due to a skewed distribution, the pressure gradient at the fluid inlet corresponding to the sealed fluid side of the annular abutment is large, so that the fluid flows out to the atmosphere side hydrodynamically. The thickness of the sealing fluid to be formed is small and the outflow amount is small.
[0011]
Then, the sealed fluid that has flowed out to the atmosphere side is held between the annular abutting portions. Since the pressure gradient at the fluid inlet corresponding to the above is small, the fluid film thickness flowing into and returning to the sealed fluid side is formed thick, and the return amount of the fluid is increased.
[0012]
That is, since the amount of inflow returning to the sealed fluid side is larger than the amount of outflow to the atmosphere side, good sealing performance is exerted as a whole of the annular contact portions provided in a plurality of stages in the axial direction.
[0013]
This effect can be obtained in any direction regardless of the rotating direction of the sliding surface, so that the sealing device can be used for a sliding surface such as a shaft or a housing that rotates in both directions. Become.
[0014]
In addition, the annular contact portion provided with a plurality of stages in the axial direction separates the sealed fluid side from the atmosphere side in a plurality of stages even when the sliding surface is stopped, so that the sealed fluid does not pass therethrough. In addition, a sealing property in a static state can be obtained.
[0015]
It is also preferable that the plurality of annular contact portions are the lip sliding portions divided by a plurality of annular cuts inclined toward the sealed fluid side.
[0017]
The lip sliding portion may be a circumferential surface portion on a lip tip side which is bent toward a sealing fluid side along the sliding surface of the annular seal lip made of a resin material.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
(Embodiment 1)
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a view for explaining a cross-sectional configuration of the sealing device 1. FIG. 1A shows the sealing device 1 provided in an annular gap 107 between a housing 106 and a shaft 105, and a sliding surface of a rotating shaft 105. FIG. 1B is a diagram illustrating a state in which an annular lip sliding portion 4a is in contact with an outer peripheral surface 105a as a first example, and FIG. 1B is a diagram illustrating the lip sliding portion 4a in which a portion D1 in FIG. It is. FIG. 2 is a front view of a state before the resin lip 4 having the lip sliding portion 4a is assembled as the sealing device 1.
[0019]
This sealing device 1 sandwiches an outer ring portion of a resin lip 4 constituting an annular lip sliding portion between respective radial portions 2a, 3a of an outer reinforcing ring 2 and an inner reinforcing ring 3 having an L-shaped cross section. Equipped. The outer reinforcing ring 2 and the inner reinforcing ring 3 are fastened by crimping by bending an end 2b of the outer reinforcing ring 2 on the sealed fluid side M.
[0020]
The resin lip 4 is formed of, for example, a resin material such as PTFE, and in a state of FIG. 2 in which the shaft 105 is not inserted (before assembling) (shown by a broken line 4 ′ in FIG. 1A). 1) It is a substantially flat washer shape, and when the shaft 105 is inserted after assembling as shown in FIG. 1A, the inner edge bends while expanding along the outer peripheral surface 105a of the shaft 105, and The inner peripheral surface is an annular lip sliding portion 4a which comes into contact with the outer peripheral surface 105a to exhibit sealing properties. In addition, by using PTFE as a material, it has characteristics such as good sliding properties due to low frictional resistance and excellent wear resistance in a state of sliding against the outer peripheral surface 105a of the shaft 105.
[0021]
However, the basic form of the resin lip 4 is not limited to the one shown in FIG. 1, and the lip sliding portion directly obliquely projects inward from the annular outer peripheral holding portion, In the case of contact with the peripheral surface, there is no problem at all if the lip sliding portion projects outward from the annular inner peripheral holding portion.
[0022]
The lip sliding portion 4a of the resin lip 4 is provided with a plurality of annular cuts 4c inclined from the lip surface 4b toward the sealed fluid side, and a plurality of annular contact portions 4d are provided between the cuts 4c. It is formed in the axial direction.
[0023]
This annular contact portion 4d will be described with reference to FIG. 1B. The contact region 4e of each annular contact portion 4d that contacts the outer peripheral surface 105a is sealed in the region of the lip surface 4b divided by the cut 4c. The contact area on the fluid side M. If the end of the sealed fluid side M is 4f and the end of the atmosphere side O is 4g in each of the divided contact areas 4e, the end 4f is larger than the end 4g when the shaft 105 is inserted. Since a large tension force (contact load) is generated due to the large diameter expansion amount of the contact area 4e, the contact pressure distribution in the contact area 4e is, as shown in the upper graph of FIG. The maximum contact pressure portion Pa has a distribution form deflected more toward the sealed fluid side M than the atmosphere side O.
[0024]
Therefore, when the sliding surface with which the lip sliding portion 4a abuts is rotating, the contact pressure distribution form of each abutting region 4e is such that the maximum contact pressure portion Pa is on the sealed fluid side M of the abutting region 4e. When the sealed fluid flows out to the atmosphere side O, the pressure gradient at the fluid inlet corresponding to the sealed fluid side M of the contact area 4e is large, and therefore, The film thickness of the sealed fluid flowing out to the side O is formed only thinly, and the outflow amount is reduced.
[0025]
Then, the sealed fluid that has flowed out to the atmosphere side O is held between the contact areas 4e. However, when the fluid flows back into the sealed fluid side M and returns, the contact area 4e is closed. Since the pressure gradient at the fluid inlet corresponding to the atmosphere side O is small, the fluid film flowing into and returning to the sealed fluid side M is formed to be thick, and the return amount of the fluid is increased.
[0026]
That is, since the amount of inflow returning to the sealed fluid side M is greater than the amount of outflow to the atmosphere side O, good sealing properties are exhibited as a whole in the contact region 4e provided in a plurality of stages in the axial direction.
[0027]
This effect can be obtained in any direction regardless of the rotating direction of the sliding surface, so that the sealing device can be used for a sliding surface such as a shaft or a housing that rotates in both directions. Become.
[0028]
Further, the contact area 4e of the annular contact portion 4d provided in a plurality of stages in the axial direction separates the sealed fluid side M and the atmosphere side O into a plurality of stages even when the shaft 105 is stopped. Therefore, the sealing fluid does not pass through the cuts 4c to communicate from the sealing fluid side M to the atmosphere side O, and a sealing property in a static state can be obtained.
[0029]
In this embodiment, the lip sliding portion 4a is described as being formed on the resin lip 4. However, the present invention can be applied to a lip made of a rubber-like elastic material having more elasticity. .
[0036]
【The invention's effect】
In the present invention described above, the sealing property is exerted on the sliding surface that rotates in both directions, and the sliding surface can be used without having to specify the rotating direction of the sliding surface.
[0037]
In addition, the annular contact portion provided with a plurality of stages in the axial direction separates the sealed fluid side from the atmosphere side in a plurality of stages even when the sliding surface is stopped, so that the sealed fluid does not pass therethrough. In addition, a sealing property in a static state can be obtained.
[Brief description of the drawings]
FIG. 1 is a cross-sectional configuration explanatory view of a sealing device according to a first embodiment of the present invention.
FIG. 2 is a diagram illustrating a resin lip.
FIG. 3 is an explanatory view of a cross-sectional configuration of a conventional sealing device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Sealing device 2 Outer reinforcing rings 2a, 3a Radial portion 2b End 3 Inner reinforcing ring 4 Resin lip 4a Lip sliding portion 4b Lip surface 4c Cut 4d Annular contact portion 4e Contact region 4f End of sealed fluid side M 4g Atmospheric side O end 105 Shaft 105a Outer surface (sliding surface)
106 Housing 107 Annular gap M Sealed fluid side O Atmosphere side

Claims (2)

In a sealing device having an annular lip sliding portion abutting on a rotating sliding surface,
The lip sliding portion has a plurality of annular contact portions divided by a plurality of annular cuts inclined in a direction away from the sliding surface in the radial direction and toward the sealed fluid side. Provided in the axial direction,
The contact pressure distribution of each of the annular contact portion with respect to the sliding surface, the sealing device that maximum contact pressure unit is characterized and this has Tsu Do and distribution form biased to sealed fluid side from the atmosphere side. The lip sliding portion is a circumferential surface portion on a tip side of the lip which is bent toward a sealing fluid side along the sliding surface of the annular seal lip made of a resin material, according to claim 1, wherein The sealing device as described.

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