JPH09292031A - Sealing device for reciprocating motion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce frictional force of a seal lip, and also improve abrasion resistance. SOLUTION: A pair of projections 9, 10 which are separated apart for a prescribed distance in an axial direction are arranged on the contact surface of the counterpart member 4 of a seal lip 6, and in the case where the contact angle of the oil side of the projection 10 arranged on the atmosphere side is set to β2 and the contact angle of the atmosphere side is set α2, the relation of those angles is set to β2>α2. In the case where the contact angle of the oil side of the projection 9 to the oil side is set to β1 and the contact angle of the atmosphere side is set to α1, the relation of those angles is set to β2>β1>α1. Since a pair of projections 9, 10 having a specified contact angle structure are arranged, a fluid such as oil is led and accumulated between the projections 9, 10 positively. It is thus possible to improve the lubricating property of a seal lip sliding surface, and it is also possible to reduce frictional force and abrasion.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reciprocating sealing device, and more particularly to a sealing lip provided with a plurality of projections on a sliding surface thereof.

[0002]

2. Description of the Related Art As a conventional reciprocating sealing device of this type, there is, for example, a device shown in FIG. That is, a seal is provided between the housing 100 and the shaft 101, which are provided so as to be relatively reciprocally movable in the axial direction, and an annular sealing device body 103 fixed to the inner circumference of the shaft hole 102 of the housing 100 and an integral body of the sealing device body 103. And a seal lip 104 that is attached to the seal lip 104.

A second step projection 106 is provided on the lip sliding surface of the seal lip 104 for the main purpose of stabilizing the contact state of the first step projection 105 due to pressure fluctuation or the like. . The contact angle α of each projection 105, 106 with the shaft 101 on the atmosphere side and the contact angle β on the oil side are β2> α2, β1 ≧ in the projections 105, 106 of each step.
The sealing property was improved by setting β2> α1.

In this conventional example, the main seal is 1
It is the projection 105 of the step.

[0005]

However, in the case of the above-mentioned prior art, since the first-stage projection 105 scrapes off the oil, the frictional force is reduced due to insufficient lubrication in the second and subsequent projections 106 in the subsequent stage. There was a problem of getting bigger.

Further, when the sealing pressure becomes high, the seal lip 104 is pressed against the shaft, so that the tightening force becomes large and the frictional force also becomes large.

As shown in FIG. 5 (c), it is also known that a plurality of fine projection groups 108 are provided on the lip sliding surface of the seal lip 107 to reduce friction.

However, as shown in FIG. 5 (e), the seal lip 107 composed of such a conventional multi-stage fine projection group 108 also has fine projections 109 of the same shape arranged so that oil is simply applied to the fine projections 109. They kept it in the middle and expected the lubricating effect by it, but did not actively introduce the oil and utilize its effect. The contact angles α and β between the fluid to be sealed and the atmosphere side of each fine projection 109 are almost the same α1≈α2≈β.
1≈β2, or β1≈β2 ≧ as in the conventional example
When α2 is set and the oil is not introduced between the fine protrusions 109, the original friction reducing effect cannot be obtained due to insufficient lubrication.

Further, as shown in FIG.
The maximum contact pressure at the tip of 09 (a in the figure) is considerably higher than that in the case without the protrusion (b in the figure), so that the wear is promoted under the use condition where the oil film becomes thin. Even under those conditions, the sealing pressure increases and the seal lip 10
When the pressing force of No. 7 is increased, the oil film is thinned by the amount of the increased pressing force, which hinders the introduction of oil between the fine protrusions 109, further promoting the increase of the frictional force.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art.
An object of the present invention is to provide a reciprocating sealing device capable of reducing frictional force of a seal lip and improving wear resistance.

[0011]

In order to achieve the above object, in the present invention, a seal is provided between two members provided so as to be relatively movable in the axial direction, and an annular member fixed to one member. A reciprocating sealing device comprising: a sealing device main body; and a sealing lip extending from the sealing device main body toward the other member and slidably contacting the other member, wherein the sealing lip is in contact with a mating member. A pair of protrusions that are separated from each other by a predetermined distance in the axial direction are provided on the surface, and the tips of the protrusions are slidably contacted with the mating sliding surface to form a valley space between the protrusions and the mating sliding surface. When the contact angle on the sealing target fluid side of the projection on the sealing target fluid side is β2 and the contact angle on the anti-sealing target fluid side is α2, β2> α2 is set and the projection on the sealing target fluid side is sealed. The contact angle on the target fluid side is β1,
When the contact angle on the anti-sealing target fluid side is α1, β2>
The feature is that β1> α1 is set.

According to the present invention, a fluid such as oil to be sealed is positively introduced between the protrusions due to the peculiar contact angle of the pair of protrusions to eliminate the lack of the amount of the fluid. Improves lubricity and reduces friction. The fluid is sealed mainly by the second projection. This point is different from the conventional one in which the main seal is formed by the projection of the first stage.

That is, when the mating member relatively moves to the anti-sealing target fluid side with respect to the seal lip (push stroke), the contact angle β1 of the projection on the sealing target fluid side on the sealing target fluid side is opposite. Since the contact angle of the protrusion on the sealing target fluid side is smaller than the contact angle β2 on the sealing target fluid side, that is, β1 <β2, the oil film formed by the protrusion on the sealing target fluid side is more than the protrusion on the anti-sealing target fluid side. The thickness increases, and the fluid to be sealed flows into the valley space between the protrusions by the difference.

The fluid flowing into the valley space contacts the anti-sealing target fluid side of the projection on the sealing target fluid side and the sealing target fluid side of the projection on the anti-sealing target fluid side with respect to the conventional shape, and the pair of projections. Improve the lubricity of.

On the other hand, since the contact angle of the projection on the side of the fluid to be sealed is set to β2> α2, the fluid flowing into the valley space is an extremely thin oil film (or a thick oil film).
Does not leak outside.

That is, by setting the contact angle β1 of the protrusion on the sealing target fluid side on the sealing target fluid side to be small,
When the mating member relatively moves to the anti-sealing target fluid side with respect to the seal lip (push stroke), the projection on the sealing target fluid side is formed with a thicker film than the projection on the anti-sealing target fluid side, and At the projections on the side of the fluid to be sealed off, friction is reduced by the improvement of lubricity due to the fluid introduced between the projections.

On the contrary, when the mating member relatively moves to the fluid to be sealed side (pulling stroke), the lubrication of the projection on the fluid side to be sealed is improved due to the improvement of lubricity due to the oil introduced between the projections. Will be reduced.

A method of positively injecting a fluid between a pair of both projections to improve the lubricity of both projections is to make the contact angle of the projections on the fluid side to be sealed β2>β1> α1 as compared with the conventional product.
In addition to the above, it is effective to make the tip of the projection have a rounded shape.

That is, by setting a roundness on the projection on the sealing target fluid side, when the mating member relatively moves to the anti-sealing target fluid side (push stroke), the film thickness of the projection on the sealing target fluid side is changed. However, due to the rounded tip, the protrusion becomes thicker than the protrusion on the side of the fluid to be sealed, and the fluid can flow into and accumulate in the valley space between the protrusions. Therefore, the lubricity of both protrusions is improved and the frictional force is reduced.

Further, a plurality of pairs of projections are provided in the axial direction.

In this way, the projections of each set are lubricated by the formation of a fluid film by the relative reciprocating motion of the mating member, but when the mating member relatively moves to the side of the fluid to be sealed (the pushing stroke). ), The fluid film formed by the projections on the anti-sealing target fluid side becomes thinner than the projections on the sealing target fluid side, that is, the fluid film is scraped off by the projections on the anti-sealing target fluid side, and in the valley space between the projections. The fluid to be sealed is inflowed and accumulated. In this way, since the shape is such that the fluid is positively accumulated in the valley space between the two projections of one set, the projections of each set always contact the fluid, and the lubricity is good and the friction is low. Less wear

The height of the protrusions is preferably a fine protrusion having a minimum height of about 1 [μm].

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to illustrated embodiments.

[First Embodiment] FIG. 1 shows a reciprocating sealing device according to a first embodiment of the present invention. This reciprocating sealing device 1 is provided so as to be relatively movable in the axial direction.
A metal ring, which seals between a housing 2 as a member and a shaft 4 inserted into a shaft hole 3 of the housing 2 and is fixed to the inner periphery of the shaft hole 3 of the housing 2 as a main body of an annular sealing device. 5 and a seal lip 6 extending from the metal ring 5 toward the shaft 4 and slidably contacting the outer peripheral surface.

The metal ring 5 is an annular member having a substantially L-shaped cross section,
A cylindrical outer fitting portion 7, an inward flange portion 8 extending radially inward from one end of the outer fitting portion 7,
It has.

The seal lip 6 is made of a rubber-like elastic material such as synthetic rubber, has a tapered cylindrical shape extending substantially in parallel with the outer peripheral fitting portion 7 of the metal ring 5, and has a large diameter one end of the inward flange portion 8. The tip of the lip having a small diameter is fixed to the inner end and is in contact with the outer circumference of the shaft 4. A spring member 16 is mounted on the back surface of the lip tip.

A pair of projections 9 and 10 are formed on the contact surface of the seal lip 6 with the mating shaft 4 and are separated from each other by a predetermined distance in the axial direction.
Is provided. The axial cross-sectional shape of the protrusions 9 and 10 is a substantially triangular shape having slopes inclined toward the axial sealing target fluid side and the anti-sealing target fluid side with the tip of the protrusion as an apex, and the contact angle of each of the protrusions 9 and 10. The angle is set by the angle between the slope and the outer circumference of the shaft 4. The tip ends of the projections 9 and 10 slidably contact the surface of the shaft 4, and a valley space 11 having a triangular cross section is formed between the projections 9 and 10 and the outer peripheral surface of the shaft 4.

In the following description, the sealing target fluid side is the oil side O, the non-sealing target fluid side is the atmosphere side A, the oil side O protrusion is the first stage protrusion 9, and the atmosphere side protrusion is the second stage protrusion 10. Further, the case where the shaft 4 moves from the oil side O to the atmosphere side A will be described as a pushing stroke (Pumping Stroke), and the case where the shaft 4 moves from the atmosphere side A to the oil side O will be described as a pulling stroke (Motoring Stroke). I shall.

In the present invention, as shown in FIG. 1 (b), when the contact angle on the atmosphere side A of the second stage protrusion 10 is α2 and the contact angle on the oil side O is β2, β2 is calculated from α2 If it is set to be large (α2 <β2), the contact angle of the oil side O of the first stage projection 9 is β1, and the contact angle of the atmosphere side A (valley space 11 side) is α1, β2> It is set so that β1> α1. α1 and α2 are set to approximately α1 = α2.

According to the present invention, due to the unique contact angle of the pair of first and second step projections 9 and 10 described above, fluid such as oil to be sealed can be used for the first and second step projections 9 and 10. By positively introducing into the valley space 11 between 10 to solve the shortage of the amount of fluid, the lubricity of the first-stage and second-stage projections 9 and 10 is improved, and the friction is reduced. The fluid is sealed mainly by the second stage protrusion 10. This point is different from the conventional one in which the main sealing is performed by the first step projection 9.

That is, in the pushing stroke in which the shaft 4 slides to the atmosphere side A, the oil film formed on the second-step projection 10 becomes thinner than the first-step projection 9, that is, the oil film is scraped off by the second-step projection 10. Therefore, oil is introduced into the valley space 11 between the first and second stage projections 9 and 10.

The oil introduced into the valley space 11 improves the lubricity on the atmosphere side A of the first-stage protrusion 9 and the oil side O of the second-stage protrusion 10 and reduces friction.

That is, the contact angle β on the oil side of the first stage projection 9
By setting 1 to be small, a thick oil film is formed on the first-stage protrusion 9 in the pushing stroke, and the second-stage protrusion 10 is formed.
Then, the friction is reduced by the improvement of lubricity due to the oil introduced into the valley space 11. On the contrary, in the pulling stroke in which the shaft 4 slides to the oil side O, the friction of the first stage projection 9 is reduced due to the improvement of the lubricity due to the oil introduced into the valley space 11.

In the conventional shape, since the first step projection 9 scrapes off the oil, the second step projection 10 has poor lubricity and large frictional force and wear. On the other hand, the shape of the present invention reduces the frictional force and wear by positively supplying the oil to the second stage protrusion 10.

On the other hand, in the present invention, the seal lip 6
Because of the cantilever structure, the tightening force of the first-step projection 9 and the second-step projection 10 is pushed in the axial center direction as the sealing pressure increases, and increases. At this time, the seal lip 6
Has a thickness, pressure acts on this thickness portion in the axial direction toward the atmosphere side, and the seal lip 6 receives a compressive force, but since the seal lip 6 is pressed by the pressure from the outer peripheral side, 4, the second stage projection 10 is further pushed in the axial center direction. Therefore, the tightening force of the second-stage protrusion 10 is larger than that of the oil-side first-stage protrusion 9, and there is an effect that the sealing is surely performed.

Further, in the free state, the inner diameter of the first-step projection 9 is set to be equal to or larger than the inner diameter of the second-step projection 10 and brought into contact with the shaft 4, thereby improving the sealing performance by the second-step projection 10. It is preferable to plan.

In the above-mentioned embodiment, α1 = α2 is set, but α1 <α2 may be set, or α1> α.
It may be 2. If α1> α2 is set, the flow rate of returning to the oil side O through the first-stage projection 9 decreases during the pulling stroke in which the shaft 4 moves relatively to the oil side O with respect to the seal lip 6, The repeated reciprocating movement further promotes the accumulation of fluid in the valley space 11.

-Experimental Example- Using the conventional sample A shown in FIG. 5A and the sample B of the present invention shown in FIG. 1, the contact angle with the shaft 4 shown in Table 1 is obtained. And the frictional force was measured.

[0039]

[Table 1] The test was performed with the apparatus shown in FIG.

The sample S is mounted on the lower part of the chamber 20, and the oil 21 is put on the upper part thereof. The seal lip of the sample S is in contact with the surface of the shaft 22 at a contact angle shown in Table 1. In this state, oscillate the shaft 22 with a sine wave in the vertical direction,
The frictional force at that time was measured by a force detector 23 such as a load cell.

The test conditions are: oil type; paraffinic mineral oil, rod stroke; 50 [mm], reciprocating frequency; 1.2.
[Hz], chamber pressure: 0 [MPa] (open to the atmosphere), temperature: 25 [° C].

The obtained results are shown in FIGS. 2 (b) and 2 (c) in terms of the relationship between the stroke position and the frictional force.
The one-sided average frictional force at the stroke center position obtained in (c) is shown.

[0043]

[Table 2] Comparing the sample A of the conventional shape with the sample B of the present invention, it is clear that the frictional force is remarkably reduced in the sample B of the present invention as shown in FIGS. 2 (b) and (c). According to Table 2, the one-sided average frictional force is approximately halved.

[Second Embodiment] FIG. 3 shows a second embodiment of the present invention.

A pair of first-stage protrusion 29 and second-stage protrusion 1
As a method of positively injecting a fluid into the valley space 11 between 0s to improve the lubricity of both protrusions 29 and 10, as shown in FIG. 3, the tip of the first stage protrusion 29 has a rounded shape 29a. It is what

The radius of curvature R is, for example, R.
It is effective to set R to about R ≧ 0.03 [mm], and preferably R ≧ 0.3 [mm].

By adding the roundness 29a to the first-stage protrusion 29, the film thickness of the first-stage protrusion 29 is rounded 29a at the tip thereof in the pushing stroke in which the shaft 4 moves relatively to the atmosphere side A. As a result, the thickness becomes thicker than that of the second-stage projection 10, and the fluid can flow into and accumulate in the valley space 11 between the projections 29 and 10. Therefore, the lubricity of both protrusions 29, 10 is improved and the frictional force is reduced.

Since other configurations and operations are the same as those in the first embodiment, the same components are designated by the same reference numerals and the description thereof will be omitted.

[Third Embodiment] FIG. 4 shows a reciprocating sealing device according to a third embodiment of the present invention.

In the third embodiment, the seal lip 12
As shown in FIG. 4 (c), the second stage protrusion 1 of the set of protrusions closest to the oil side O covers the entire area of contact with the shaft 4.
4 and the contact angles α2 and β2 between the shaft 4 and α2 <β2, 1
The contact angles α1 and β1 between the step projection 13 and the shaft 4 are β2> β1
> Α1 and these first and second stage projections 13 and 14 are set as one set, and a plurality of sets of fine projections 15 are provided with a projection height of 5 to 50.
It is formed within the range of [μm]. A spring member 16 is attached to the back surface of the fine projection group 15.

The height of the protrusion is preferably 5 to 50 [μm], but a height of at least about 1 [μm] is sufficient, and the height is 50.
It may be [μm] or more.

Since the other structure is the same as that of the first embodiment, the same components are designated by the same reference numerals and the description thereof will be omitted.

In the reciprocating sealing device according to the third embodiment,
In the plurality of sets of fine projections 15 based on the one-to-two-step fine projections 13 and 14 that slide in contact with the shaft 4, in the pushing stroke in which the shaft 4 slides toward the atmosphere side A, In comparison, the oil film formed by the second-stage protrusion 14 becomes thinner, that is, 2
The oil film is scraped off by the step protrusion 14, and the first step, 2
Oil flows into and accumulates in the valley space 17 between the step projections 13 and 14. In this way, since the shape is such that the fluid is positively accumulated in the valley space 17 between the two sets of protrusions 13 and 14, the protrusions 13 and 14 of each set are always in contact with the fluid for lubrication. Good properties, low friction and less wear.

In the conventional fine protrusion group of the seal lip shown in FIG. 5 (c), oil is not actively introduced between the protrusions, so that insufficient lubrication occurs in the contact sliding region. Easy to wear, friction force increases and it is easy to wear. In particular, in the protrusions in the contact area on the atmosphere side, oil is blocked by the protrusions close to the oil side, so that lubrication is insufficient and wear tends to occur. Further, when the sealing pressure is increased, the oil film generated by sliding becomes thin, so that the abrasion of the protrusions is easily promoted.

On the other hand, in the fine protrusion group 15 of the present invention, since the oil is accumulated between the fine protrusions 13 and 14 in two stages, each fine protrusion 13 and 14 must be formed. In contact with oil, it has the effects of good lubricity, low friction, and low wear.

In each of the above embodiments, the case where the seal lip 12 contacts the shaft 4 has been described as an example, but the main body of the sealing device is fixed to the shaft and the seal lip 12 contacts the inner peripheral side of the housing 2. The same applies to a sliding outer seal.

In each of the above embodiments, a so-called oil seal has been described as an example. However, the present invention is not limited to this, and a general reciprocating sealing device having a seal lip such as a molded packing such as a U packing. It can be widely applied.

The fluid to be sealed is not limited to oil, but can be used for sealing various liquids or gases such as water and various chemicals. Further, the anti-sealing target fluid is not limited to open to the atmosphere but can be applied to various gases and the like.

[0059]

As described above, according to the present invention,
The following effects can be obtained.

[Claim 1] Since the pair of protrusions having a unique contact angle structure is provided, a fluid such as oil is positively introduced and accumulated between the protrusions to improve the lubricity of the seal lip sliding surface.
It is possible to reduce frictional force and wear.

[Claim 2] Further, by setting a roundness on the protrusion on the sealing target fluid side, when the mating member relatively moves to the anti-sealing target fluid side, the film thickness on the protrusion on the sealing target fluid side. Is thicker than the projection on the anti-sealing target fluid side due to the roundness of the tip, and the fluid can flow into and accumulate in the valley space between both projections. Therefore, the lubricity of both protrusions is improved and the frictional force is reduced.

[Claim 3] Further, if a plurality of pairs of protrusions are provided in the axial direction, the inflow of the fluid is gradually expanded between the protrusions on the side of the non-sealing target fluid, and the protrusions of each set are always fluid. Good contact, good lubricity, low friction and little wear.

[Claim 4] The protrusion is at least approximately 1 [μm].
The fine protrusions having a certain height have the effect of selecting the contact angle. Further, the volume of the valley space between the fine protrusions is small, and the fluid can be instantaneously introduced into the valley space.

[Brief description of drawings]

1A and 1B show a reciprocating sealing device according to a first embodiment of the present invention, in which FIG. 1A is a sectional view of a main part and FIG. 1B.
FIG. 4 is a diagram showing a contact state of a seal lip.

FIG. 2 is a diagram showing an experimental device of the device of FIG.

3A and 3B show a reciprocating sealing device according to a second embodiment of the present invention, wherein FIG. 3A is a sectional view of a main part and FIG.
FIG. 4 is a diagram showing a contact state of a seal lip.

FIG. 4 shows a reciprocating sealing device according to a third embodiment of the present invention, in which FIG. 4 (a) is a sectional view of a main part and FIG. 4 (b).
Is a view showing a contact state of the seal lip, and FIG. 7C is an enlarged view of the contact portion.

FIG. 5 is a diagram showing a conventional reciprocating sealing device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reciprocating sealing device 2 Housing 3 Shaft hole 4 Shaft 5 Metal ring (sealing device main body) 6 Seal lip 7 Cylindrical fitting part 8 Inward flange part 9 Protrusion 10 Protrusion 11 Valley space 12 Seal lip 13 Fine protrusion 14 Fine Projection 15 Fine projection group 16 Spring 20 Chamber 21 Oil 22 Axis 23 Force detector 29 Projection 29a Roundness O Oil side (sealing target fluid side) A Atmosphere side (anti-sealing target fluid side) S Sample α1, α2 Contact angle (atmosphere side) ) Β1, β2 contact angle (oil side)

Claims (4)

[Claims] 1. An annular sealing device main body fixed to one member for sealing between two members provided so as to be relatively movable in the axial direction, and extending from the sealing device main body toward the other member. In a reciprocating sealing device having a seal lip slidably contacting the other member, a pair of protrusions spaced apart by a predetermined distance in the axial direction are provided on a contact surface of the seal lip with a mating member, The tip is slidably brought into contact with the mating sliding surface to form a valley space between the projections and the mating sliding surface, and the contact angle of the projection on the non-sealing target fluid side on the sealing target fluid side is β2. When the contact angle on the anti-sealing target fluid side is α2, β2> α2 is set, and the contact angle on the sealing target fluid side of the protrusion on the sealing target fluid side is β
1, and β2>β1> α1 when the contact angle on the anti-sealing target fluid side is α1, the reciprocating sealing device. 2. An annular sealing device body fixed to one member and extending from the sealing device body toward the other member for sealing between two members provided so as to be relatively movable in the axial direction. In a reciprocating sealing device having a seal lip slidably contacting the other member, a pair of protrusions spaced apart by a predetermined distance in the axial direction are provided on a contact surface of the seal lip with a mating member, The tip is slidably brought into contact with the mating sliding surface to form a space between the projections and the mating sliding surface, and the contact angle of the projection on the anti-sealing target fluid side on the sealing target fluid side is β2, and anti-sealing When the contact angle on the target fluid side is α2, β2> α2 is set, and the tip of the protrusion on the sealing target fluid side is rounded. 3. The reciprocating sealing device according to claim 1, wherein a plurality of pairs of projections are provided in the axial direction. 4. The reciprocating sealing device according to claim 3, wherein the protrusions are fine protrusions having a minimum height of about 1 [μm].