JPH09310763A - Packing for spline shaft - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve sealing ability while the increase of frictional resistance of a spline groove is suppressed. SOLUTION: A protrusion seal part 12 formed on a lip 10 on the inner circumferential side is formed in an arcuate shape conforming to that of a spline groove 7 having an outer peripheral surface 7a formed in an arcuate shape in a peripheral direction. The curvature of radius of the circular arc is reduced to that of the circular arc of the outer peripheral surface 7a of the spline groove 7. As a result, the slide contact surface 12a of a protrusion seal part 12 is forced into close contact with the outer peripheral surface 7a of the spline groove 7 at approximately the same contact surface pressure as that of the lip 10 on the inner peripheral side at two edges, and forced into a further high contact surface force at a central part. The slide contact surface 11a of the tip part 11 and the slide contact surface 12a of the protrusion seal part 12 is formed in an arcuate shape in the direction of a central axis, and the curvature radius of the circular arc of the slide contact surface 12a of the protrusion seal part 12 is reduced to a value lower than that of the slide contact surface 11a of the tip part 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spline shaft packing used for a fluid pressure cylinder or the like.

[0002]

2. Description of the Related Art For example, in a fluid pressure cylinder device using a spline shaft, a U-packing for sealing the spline shaft is provided with a convex sealing portion which is in close contact with a spline groove of the spline shaft on an inner peripheral side lip. . Although the U packing is molded by a mold, it is not easy to form the convex sealing portion in a shape that matches the spline groove. For this reason, although it is easy to bring the inner peripheral lip into close contact with the outer peripheral surface of the spline shaft excluding the spline groove with a uniform contact surface pressure, the convex sealing portion has a uniform contact surface with the entire outer peripheral surface of the spline groove. It was difficult to bring them into close contact with each other by pressure. Therefore, there is a problem that the sealing property in the spline groove becomes insufficient.

Therefore, in order to improve the sealing performance in the spline groove, a U packing (actual flat plate 3) shown in FIG.
No. 44270), the thick-walled portion 2 is provided on the inner peripheral side of the outer peripheral lip 22 facing the portion where the convex sealing portion 21 is provided, and also on the outer peripheral side of the inner peripheral lip 23.
4, 25 are provided. As shown in FIG. 7B, the thick portions 24 and 25 are pressed against each other when the U packing 20 is mounted in the circumferential groove 26 and the outer peripheral side lip 22 and the inner peripheral side lip 23 are close to each other. To do. The convex sealing portion 21 is pressed against the spline groove 28 of the spline shaft 27 without depending on the tension of the inner peripheral lip 23.

Therefore, since the convex sealing portion 21 is pressed against the spline groove 28 with a stronger force than in the case where the inner peripheral lip 23 is tensioned, the shape thereof is different from that of the spline groove 28.
Even if it does not match the above, it is pressed against the spline groove 28 with a high contact surface pressure. As a result, the sealing property in the spline groove 28 is improved.

[0005]

However, the above U
In the packing 20, the convex sealing portion 21 is attached to the inner peripheral lip 24.
Instead of being brought into intimate contact with the spline groove 28 by the elastic tension, the elastic contact is made by the elastic force of the elastic deformation of the thick portions 24 and 25. Therefore, the contact surface pressure applied from the convex sealing portion 21 to the spline groove 28 becomes unnecessarily large, so that the frictional resistance between each convex sealing portion 21 and the spline groove 28 becomes excessively large. As a result, the frictional resistance between the U-packing 20 and the spline shaft 27 increases, and the operability of the cylinder device deteriorates.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a packing for a spline shaft which can improve sealing performance while suppressing an increase in frictional resistance in the spline groove. To provide.

[0007]

In order to solve the above-mentioned problems, the invention as set forth in claim 1 has a base portion formed in an annular shape, and an inner peripheral end of the base portion, the tip portion of which is a spline. A packing for a spline shaft, comprising an inner peripheral lip that is in pressure contact with the outer peripheral surface of the shaft, and a convex sealing portion that is provided at the tip of the inner peripheral lip and that is in pressure contact with the outer peripheral surface of the spline groove of the spline shaft. The convex sealing portion has a shape as viewed from the central axial direction of the spline shaft, and both side edges of the convex sealing portion are in close contact with the inner peripheral side lip at substantially the same contact surface pressure as that of the center thereof. The higher the contact pressure, the closer the layers are formed.

According to a second aspect of the present invention, in the first aspect of the invention, the tip end portion and the convex sealing portion are formed in an arc shape in the central axis direction of the spline shaft.

According to a third aspect of the present invention, in the second aspect of the invention, the convex sealing portion is formed in an arc shape smaller than the tip portion. Therefore, according to the first aspect of the present invention, the tip end portion of the inner peripheral side lip formed at the inner peripheral end of the base portion formed in an annular shape comes into close contact with the outer peripheral surface of the spline shaft. Then, the convex sealing portion provided at the tip of the inner peripheral lip comes into close contact with the outer peripheral surface of the spline groove. At this time, the shape of the convex sealing portion as viewed from the direction of the central axis of the spline shaft is such that both side edges of the convex sealing portion are in close contact with the outer peripheral surface at substantially the same contact surface pressure as the inner peripheral lip, and the closer to the center the It is formed in close contact with a high contact pressure. For this reason, even if the shape of the convex sealing portion does not slightly match the shape of the spline groove, the entire convex sealing portion is brought into close contact with the entire outer peripheral surface of the spline groove by the tension of the inner peripheral lip.

According to the second aspect of the present invention, the first aspect is provided.
In the invention described in the above, since the tip portion and the convex sealing portion are formed in an arc shape in the central axis direction of the spline shaft, the sliding contact surface of the tip portion is on the outer peripheral surface of the spline shaft, and the convex sealing portion The sliding contact surface closely contacts the outer peripheral surface of the spline groove with an arc surface. As a result, the length of the arcuate surface in close contact with the outer peripheral surface of the spline shaft in the direction of the central axis decreases, so that the contact pressure applied from the tip to the outer peripheral surface increases. Similarly, since the length of the arcuate surface in close contact with the outer peripheral surface of the spline groove in the direction of the central axis decreases, the contact surface pressure applied from the convex sealing portion to the outer peripheral surface increases. Moreover, since the lubricating film on the outer peripheral surface of the spline shaft and the outer peripheral surface of the spline groove is not scraped off, the lubricating film is stably formed on each outer peripheral surface.

According to the invention described in claim 3, according to claim 2
In the invention described in, since the convex sealing portion is formed in an arc shape smaller than the tip portion, the length in the central axis direction of the arc surface closely contacting the outer peripheral surface of the spline groove, in the outer peripheral surface other than the spline groove. It is smaller than the length in the direction of the central axis of the arc surfaces that are in close contact with each other. As a result, the frictional resistance between the convex sealing portion and the spline groove, which increase the frictional resistance, is reduced.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment in which the present invention is embodied in a U packing for an air cylinder will be described below with reference to FIGS.

FIG. 2 shows a part of the air cylinder 1 having a U packing. A peripheral groove 4 for packing is provided in the cylinder tube 2 adjacent to the pressure chamber 3, and a U packing 5 is accommodated in the peripheral groove 4. This U packing 5 is a spline shaft 6 through which the cylinder tube 2 is inserted.
Is in sliding contact with The spline shaft 6 is provided with a spline groove 7. As shown in FIG. 1A, the spline groove 7 has an arcuate cross section.

As shown in FIG. 3, the U-packing 5 has an annular base portion 8, an annular outer peripheral lip 9 extending from the outer peripheral end of the base portion 8 to one side, and an inner peripheral end of the base portion 8 to one side. And an annular inner peripheral lip 10 extending in the direction of.
The U packing 5 is made of NBR (nitrile rubber), H-N
Made integrally of materials such as BR (hydrogenated nitrile rubber), X-NBR (carboxyl nitrile rubber), FKM (fluorine rubber), AU (polyester type urethane rubber), EU (polyether type urethane rubber) There is.

The base portion 8 is in contact with the left side surface 4a of the circumferential groove 4. The outer peripheral side lip 9 is the outer peripheral surface 4 of the peripheral groove 4.
It is closely related to b. The outer peripheral side lip 9 is formed such that its outer diameter is slightly larger than the inner diameter of the outer peripheral surface 4b in a natural state, and when it is accommodated in the peripheral groove 4, it is elastically deformed so as to bend toward the inner peripheral side.

The sliding contact surface 11a of the tip portion 11 of the inner peripheral lip 10 is in sliding contact with the outer peripheral surface 6a of the spline shaft 6. The inner peripheral side lip 10 is formed such that the inner diameter of the sliding contact surface 11a of the tip portion 11 is slightly smaller than the outer diameter of the spline shaft 6 in the natural state, and the inner peripheral side lip 10 is accommodated in the peripheral groove 4. Is elastically deformed so as to bend toward the outer peripheral side.

As shown in FIG. 1B, the sliding contact surface 11a of the tip portion 11 is formed in an arc shape in the direction of the central axis of the spline shaft 6. The sliding contact surface 11 a of the tip portion 11 is provided with as many convex sealing portions 12 as there are spline grooves 7. The sliding contact surface 12 a of each convex sealing portion 12 is in close contact with the outer peripheral surface 7 a of the spline groove 7. As shown in FIG. 4, in the natural state, the sliding contact surface 12a is formed in an arc shape in which the shape seen from the central axis direction of the spline shaft 6 substantially matches the same shape of the spline groove 7. More specifically, as shown in FIG. 5, in the convex sealing portion 12, the radius of curvature R1 of the arc of the sliding contact surface 12a in the natural state is made smaller than the radius of curvature R2 of the arc of the outer peripheral surface 7a of the spline groove 7. ing. In the convex sealing portion 12, the circumferential width D of the spline shaft 6 is formed to be equal to the circumferential width D of the spline groove 7. As a result, the convex sealing portion 12 is brought into close contact with the outer peripheral surface 7a at both end edges with a contact surface pressure of substantially the same magnitude as the inner peripheral lip, and with a higher contact surface pressure toward the center thereof. It is supposed to do.

Further, as shown in FIG. 1B, the sliding contact surface 12a of the convex sealing portion 12 is formed in an arc shape in the central axis direction of the spline shaft 6. More specifically, as shown in FIG. 6, the radius of curvature R3 of the circular arc of the sliding contact surface 12a is
It is formed smaller than the radius of curvature R4 of the arc of the sliding contact surface 11a of the tip portion 11 in the same direction.

As shown in FIGS. 1 (a) and 1 (b), a plurality of engaging projections 13 are provided on the back side of the base 8 at equal angular intervals. Each of the engaging projections 13 is engaged with an engaging recess 14 formed on the left side surface 4 of the circumferential groove 4 in a state where the U packing 5 is mounted.

Next, the operation of the packing for the spline shaft constructed as described above will be described. When air is introduced into the pressure chamber 3, the outer peripheral lip 9 causes the outer peripheral surface 4 b of the peripheral groove 4 to move.
And the tip 11 of the inner lip 10
Is brought into close contact with the outer peripheral surface 6a of the spline shaft 6. at the same time,
The sliding contact surface 12a of each convex sealing portion 12 is connected to each spline groove 7
Is closely contacted with the outer peripheral surface 7a.

At this time, since the sliding contact surface 11a of the tip portion 11 is formed in an arc shape in the direction of the central axis of the spline shaft 6, the sliding contact surface 11a comes into close contact with the outer peripheral surface 6a as an arc surface. Therefore, a high contact pressure is applied from the sliding contact surface 11a to the outer peripheral surface 6a, and the lubricating film is stably formed on the outer peripheral surface 6.

Similarly, since the sliding contact surface 12a of the convex sealing portion 12 is formed in an arc shape in the direction of the central axis of the spline shaft 6, the sliding contact surface 12a closely contacts the outer peripheral surface 7a in an arc surface. . Therefore, a high contact pressure is applied from the sliding contact surface 12a to the outer peripheral surface 7a, and the lubricating film is stably formed on the outer peripheral surface 7a.

Further, the convex sealing portion 12 is brought into close contact with the spline groove 7 at both end edges thereof with a surface pressure substantially the same as the inner peripheral lip 10, and with a higher surface pressure toward the center thereof. Is formed. Therefore, the convex sealing portion 1
The shape of the second sliding contact surface 12a is the outer peripheral surface 7a of the spline groove 7.
Even if the shape does not match the shape of the
The convex sealing portion 12 is brought into close contact with the entire outer peripheral surface 7a of the spline groove 7 by the tension.

Further, in the direction of the central axis of the spline shaft 6, the radius of curvature R3 of the sliding contact surface 12a of the convex sealing portion 12
Is smaller than the radius of curvature R4 of the sliding contact surface 11a of the tip portion 11, the length of the circular arc surface of the sliding contact surface 12a that is in close contact with the outer peripheral surface 7a is close to the outer peripheral surface 6a. Is smaller than the length of the circular arc surface of the sliding contact surface 11a in the direction of the central axis. As a result, the frictional resistance between the convex sealing portion 12 and the spline groove 7 where the frictional resistance becomes high is reduced.

Further, since the engaging protrusions 13 of the U packing 5 are engaged with the engaging recesses 14 of the circumferential groove 4, respectively,
The packing 5 does not rotate with respect to the spline shaft 6. Therefore, each convex sealing portion 12 is prevented from being displaced from the spline groove 7 or coming off.

As described in detail above, according to the spline shaft packing of the present embodiment, the following effects can be obtained. (A) Spline groove 7 formed in an arc shape in the circumferential direction
The radius of curvature R2 of the sliding contact surface 12a of the convex sealing portion 12 which is also formed in an arc shape in the circumferential direction is made smaller than the radius of curvature R1 of the outer peripheral surface 7a. As a result, the convex sealing portion 12 comes into close contact with the outer peripheral surface 7a of the spline groove 7 at both end edges at a surface contact pressure that is substantially the same as the inner peripheral side lip, and becomes closer to the center thereof with a higher contact surface pressure. I did it. Therefore, even if the shape of the sliding contact surface 12a of the convex sealing portion 12 does not match the shape of the outer peripheral surface 7a of the spline groove 7 to some extent,
The convex sealing portion 12 is brought into close contact with the outer peripheral surface 7a with a high contact surface pressure due to the tension of the inner peripheral side lip 10. As a result, the sealing performance in the spline groove 7 can be improved.

(B) Moreover, in (a), the convex sealing portion 12 is provided with the inner peripheral lip 10 with respect to the spline groove 7.
Since it is closely contacted by the tension of the
Compared with the case of pressure contact by pressure contact of 4, 25,
It is possible to suppress an increase in frictional resistance in the spline groove 7.

(C) The sliding contact surface 11a of the tip portion 11 and the sliding contact surface 12a of the convex sealing portion 12 are connected to each other by the spline shaft 6
It was formed in an arc shape in the direction of the central axis of. Therefore, the sliding contact surface 1
1a is brought into close contact with the outer peripheral surface 6a of the spline shaft 6, and the sliding contact surface 12a is brought into close contact with the outer peripheral surface 7a of the spline groove 7 as circular arc surfaces. As a result, the length in the central axis direction of the closely contacted surfaces can be reduced and the contact surface pressure can be increased, so that the sealing performance can be further improved, and the close contact with the arcuate surfaces can reduce the lubricating film. Since scratching can be prevented, the frictional resistance can be further reduced by the lubricating film that is stably formed. (D) The radius of curvature of the arc in the central axis direction of the sliding contact surface 12a of the convex sealing portion 12 R3 is smaller than the radius of curvature R4 of the circular arc of the sliding contact surface 11a of the tip portion 11 in the direction of the central axis.
Therefore, the length in the central axis direction of the circular arc surface of the sliding contact surface 12a that is in close contact with the spline groove 7 can be further reduced, so that the frictional resistance in the spline groove 7 can be further reduced.

(E) A plurality of engaging protrusions 13 are provided on the back side of the U packing 5, and each engaging protrusion 13 is engaged with an engaging recess 14 provided on the left side surface 4a of the circumferential groove 4. I chose Therefore, rotation of the U packing 5 with respect to the spline shaft 6 can be prevented. As a result, the convex sealing portion 12
Since it can be prevented from displacing or coming off from the spline groove 7, it is possible to prevent deterioration of the sealing performance due to the rotation of the U packing 5.

It should be noted that the present invention is not limited to the above-described embodiment, but may be configured as follows. (1) Instead of forming the sliding contact surface 11a of the tip portion 11 and the sliding contact surface 12a of the convex sealing portion 12 in an arc shape in the direction of the central axis of the spline shaft 6, for example, a corner that makes line contact Alternatively, it may be formed in a rectangular shape or in a flat shape so as to be in contact with each other. Even in this case, the spline shaft 6 can be reliably sealed and the frictional resistance can be reduced.

(2) The radius of curvature R3 of the circular arc of the sliding contact surface 12a of the convex sealing portion 12 in the central axis direction is made smaller than the radius of curvature R4 of the circular arc of the sliding contact surface 11a of the tip portion 11 in the central axis direction. However, they may have the same radius of curvature. Even in this case, the spline shaft 6 can be reliably sealed,
Moreover, the frictional resistance can be reduced.

(3) The spline groove 7 is not limited to have an arc-shaped cross section, and may be, for example, substantially V-shaped. In this case, by making the cross-sectional shape of the sliding contact surface 12a of the convex sealing portion 12 into a substantially V-shape that is more acute than the shape of the spline groove,
The spline groove 7 has the strongest close contact with the center of the outer peripheral surface 7a,
It can be gradually weaker and closer to both sides.

(4) The U packing 5 may be provided without the engaging convex portion 13. (5) Although the U packing 5 for the air cylinder 1 is used, it may be applied to the U packing used for other gas pressure cylinders. Further, it may be applied to the U packing used for the hydraulic cylinder.

The technical ideas other than the claims that can be understood from the above-described embodiment will be described below along with their effects. (1) A packing for a spline shaft in which an engaging portion 13 is provided on the base portion 8. According to such a configuration, it is possible to prevent rotation with respect to the spline shaft 6 and prevent deterioration in sealing performance due to rotation.

(2) The packing for a spline shaft according to any one of claims 1 to 3 is for an air cylinder device. According to such a configuration, the air cylinder device 1
It is possible to reliably seal the spline shaft 6 used for, and to reduce the frictional resistance.

[0036]

According to the invention described in claim 1, it is possible to improve the sealing performance while suppressing an increase in frictional resistance in the spline shaft.

According to the invention described in claim 2, according to claim 1
In addition to the effect of the invention described in (1), the sealing performance can be further improved, and the frictional resistance can be further reduced. According to the invention of claim 3, in addition to the effect of the invention of claim 2, the frictional resistance can be further reduced.

[Brief description of drawings]

FIG. 1A is a front view of a U packing, and FIG. 1B is a sectional view taken along line AA.

FIG. 2 is a partial cross-sectional view of an air cylinder having a U packing.

FIG. 3 is a perspective view from the front side of the U packing.

FIG. 4 is a partial front view including a convex sealing portion.

FIG. 5 is a detailed front view of the convex sealing portion.

FIG. 6 is a cross-sectional view of an inner peripheral side lip including a convex sealing portion.

FIG. 7 (a) is a cross-sectional view of a conventional U packing, and FIG.
Sectional drawing of a U packing and a spline shaft.

[Explanation of symbols]

6 ... Spline shaft, 6a ... Outer peripheral surface, 7 ... Spline groove,
7a ... outer peripheral surface, 8 ... base portion, 10 ... inner peripheral side lip, 11 ...
Tip part, 12 ... Convex sealing part.

Claims (3)

[Claims] 1. A base portion (8) formed in an annular shape, and a tip portion (1) formed at an inner peripheral end of the base portion (8).
1) is provided on the inner peripheral side lip (10) that is in close contact with the outer peripheral surface (6a) of the spline shaft (6), and on the tip portion (11) of the inner peripheral side lip (10), and the spline shaft (6) ) Is a packing for a spline shaft, which is provided with a convex sealing portion (12) in pressure contact with the outer peripheral surface (7a) of the spline groove (7), wherein the convex sealing portion (12) is the spline shaft (6). ), The shape viewed from the central axis direction is such that both side edges thereof come into close contact with the outer peripheral surface (7a) at substantially the same contact surface pressure as the inner peripheral side lip (10), and the higher the contact is toward the center thereof. Packing for spline shaft that is formed so as to come into close contact with the surface pressure. 2. The spline shaft according to claim 1, wherein the tip portion (11) and the convex sealing portion (12) are formed in an arc shape in a central axis direction of the spline shaft (6). Packing. 3. A convex sealing portion (12) is provided with the tip portion (1).
The packing for a spline shaft according to claim 2, which is formed in an arc shape smaller than 1).