JP3150903B2 - Packing for spline shaft - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art For example, in a fluid pressure cylinder device using a spline shaft, a convex sealing portion which is in close contact with a spline groove of the spline shaft is provided on the inner peripheral side lip of a U packing for sealing the spline shaft. . The U packing is formed by a mold, but it is not easy to form the convex sealing portion into a shape matching the spline groove. For this reason, it is easy to bring the inner peripheral side lip into close contact with the outer peripheral surface of the spline shaft excluding the spline groove with a uniform contact surface pressure, but the convex sealing portion is uniformly contacted with the entire outer peripheral surface of the spline groove. It was difficult to make them close by pressure. Therefore, there is a problem that the sealing performance in the spline groove is insufficient.

Therefore, in order to improve the sealing performance of the spline groove, a U-packing shown in FIG.
In Japanese Patent Application Laid-Open No. 44270/20), thick portions 2 are provided on the inner peripheral side of the outer peripheral side lip 22 opposite to the portion where the convex sealing portion 21 is provided, and on the outer peripheral side of the inner peripheral side lip 23 as well.
4, 25 are provided. As shown in FIG. 7B, the two 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 lip 22 and the inner lip 23 are close to each other. I do. Then, 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 side lip 23.

Accordingly, since the convex sealing portion 21 is pressed against the spline groove 28 with a stronger force than the case where the inner peripheral side lip 23 is stretched, the shape thereof is changed to the spline groove 28.
The spline grooves 28 are pressed against the spline grooves 28 with a high contact pressure even if they do not match the above. As a result, the sealing performance in the spline groove 28 is improved.

[0005]

However, the above U
In the packing 20, the convex sealing portion 21 is connected to the inner peripheral side lip 24.
Instead of being tightly contacted with the spline groove 28 by the elastic tension, the two thick portions 24 and 25 are brought into pressure contact with each other by an elastic force due to elastic deformation. Therefore, the contact surface pressure applied to the spline groove 28 from the convex sealing portion 21 becomes unnecessarily large, and 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.

SUMMARY OF THE INVENTION 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 capable of improving sealing performance while suppressing an increase in frictional resistance in a spline groove. To provide.

[0007]

According to a first aspect of the present invention, an annular base is formed at an inner peripheral end of the base, and a tip of the base is formed by a spline. A spline shaft packing comprising: an inner peripheral side lip that is in pressure contact with the outer peripheral surface of the shaft; and a convex sealing portion that is provided at the distal end of the inner peripheral side lip and is in press contact with the outer peripheral surface of the spline groove of the spline shaft. In addition, the convex sealing portion is
A sliding contact surface closely contacting the outer peripheral surface of the plunging groove;
Arc shape of the sliding contact surface viewed from the center axis direction of the line axis
Is smaller than the radius of curvature of the arc on the outer peripheral surface.
And the center axis of the spline shaft.
Direction, the radius of curvature of the arc shape of the sliding contact surface is
Outer circumference of the spline groove at the tip of the inner circumference side lip
Smaller than the radius of curvature of the arc shape of the sliding surface that is in close contact with the surface
The convex sealing portion is formed such that the shape viewed from the central axis direction of the spline shaft is such that both side edges thereof are in close contact with the outer peripheral surface at substantially the same contact pressure as the inner peripheral side lip, and the center thereof The higher the contact pressure, the higher the contact pressure.

According to a second aspect of the present invention, in the first aspect, the convex sealing portion has a circumferential width of the spline shaft equal to a circumferential width of the spline groove. />.

According to a third aspect of the present invention, in the second aspect, the convex sealing portion is formed in an arc shape smaller than the distal end portion. Therefore, according to the invention <br/> recited in each claim, the distal end portion of the inner peripheral lip which is formed on the inner peripheral end of the base portion which is formed in an annular shape is in close contact with the outer peripheral surface of the spline shaft. And the convex sealing part provided in the front-end | tip part of an inner peripheral lip contacts closely the outer peripheral surface of a spline groove. At this time, the shape of the convex sealing portion as viewed from the center axis direction of the spline shaft is such that both side edges thereof are in close contact with the outer peripheral surface at substantially the same contact pressure as the inner peripheral side lip, and the closer to the center thereof. It is formed to be in close contact with high contact pressure. For this reason, even when the shape of the convex sealing portion does not slightly match the shape of the spline groove, the entire convex sealing portion is in close contact with the entire outer peripheral surface of the spline groove due to the tension of the inner peripheral side lip.

Further , since the tip and the convex sealing portion are formed in an arc shape in the direction of the center axis of the spline shaft, the sliding contact surface of the tip is on the outer peripheral surface of the spline shaft and the sliding of the convex sealing portion. The contact surfaces are in close contact with the outer peripheral surfaces of the spline grooves in the form of circular arcs. As a result, the length of the arc surface closely contacting the outer peripheral surface of the spline shaft in the central axis direction becomes smaller, and the contact surface pressure applied to the outer peripheral surface from the tip end increases. Similarly, since the length in the central axis direction of the arc surface closely contacting the outer peripheral surface of the spline groove is reduced, the contact surface pressure applied to the outer peripheral surface from the convex sealing portion increases. In addition, 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.

Further, since the convex sealing portion is formed in an arc shape smaller than the tip portion, the length of the arc surface close to the outer peripheral surface of the spline groove in the center axis direction is closer to the outer peripheral surface other than the spline groove. Is smaller than the length of the arc surface in the central axis direction. As a result, the frictional resistance between the convex sealing portion and the spline groove, which increases the frictional resistance, is reduced.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One 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 provided with 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. The U packing 5 is provided with 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 is formed in an arc-shaped cross section.

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

The base 8 is in contact with the left side surface 4a of the circumferential groove 4. The outer peripheral side lip 9 is provided on the outer peripheral surface 4 of the peripheral groove 4.
b. The outer diameter of the outer peripheral side lip 9 is slightly larger than the inner diameter of the outer peripheral surface 4b in a natural state, and is elastically deformed so as to bend toward the inner peripheral side when housed in the peripheral groove 4.

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

As shown in FIG. 1B, the sliding surface 11a of the tip 11 is formed in an arc shape in the direction of the center axis of the spline shaft 6. On the sliding contact surface 11 a of the tip end portion 11, the convex sealing portions 12 are provided by the number of spline grooves 7. The sliding contact surface 12a of each of the convex sealing portions 12 is in close contact with the outer peripheral surface 7a of the spline groove 7. As shown in FIG. 4, the sliding contact surface 12 a is formed in an arc shape in a natural state, as viewed from the center axis direction of the spline shaft 6, substantially matching 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. The circumferential width D of the spline shaft 6 of the convex sealing portion 12 is equal to the width D of the spline groove 7 in the circumferential direction. As a result, the convex sealing portion 12 is in close contact with the outer peripheral surface 7a at the contact surface pressure of substantially the same size as the inner peripheral side lip, and is closer to the center with the higher contact surface pressure. It is supposed to.

As shown in FIG. 1B, the convex sealing portion 12 has a sliding contact surface 12a formed in an arc shape in the direction of the center axis of the spline shaft 6. More specifically, as shown in FIG. 6, the radius of curvature R3 of the arc of the sliding contact surface 12a is:
The radius of curvature R4 of the circular arc in the same direction on the sliding contact surface 11a of the tip 11 is formed smaller.

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 engagement protrusions 13 is engaged with an engagement 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 a spline shaft configured as described above will be described. When air is introduced into the pressure chamber 3, the outer peripheral side lip 9 becomes the outer peripheral surface 4 b of the peripheral groove 4.
And the tip 11 of the inner lip 10
Are in close contact with the outer peripheral surface 6 a of the spline shaft 6. at the same time,
The sliding contact surface 12a of each convex sealing portion 12 is
Is closely contacted with the outer peripheral surface 7a.

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

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

The convex sealing portion 12 is in close contact with the spline groove 7 at almost the same contact pressure as the inner peripheral lip 10 at both end edges, and is closer to the center with a higher contact pressure at the center. It is formed so that. Therefore, the convex sealing portion 1
2 is the outer peripheral surface 7a of the spline groove 7
Even if the shape does not slightly match the shape of the inner peripheral side lip 10
The tight sealing portion 12 is brought into close contact with the entire outer peripheral surface 7a of the spline groove 7 due to the tension.

Further, in the direction of the center axis of the spline shaft 6, the radius of curvature R3 of the sliding contact surface 12a of the convex sealing portion 12 is determined.
Is formed smaller than the radius of curvature R4 of the sliding surface 11a of the distal end portion 11, so that the length of the arc surface of the sliding surface 12a in close contact with the outer peripheral surface 7a in the center axis direction is closer to the outer peripheral surface 6a. The length of the sliding surface 11a is smaller than the length of the arc surface 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.

Also, since each engaging projection 13 of the U packing 5 is engaged with each engaging recess 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 does not deviate or come off with respect to the spline groove 7.

As described in detail above, according to the packing for a spline shaft of the present embodiment, the following effects can be obtained. (A) Spline grooves 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 in the circumferential direction, is made smaller than the radius of curvature R1 of the outer peripheral surface 7a. As a result, both ends of the convex sealing portion 12 come into close contact with the outer peripheral surface 7a of the spline groove 7 at substantially the same contact pressure as the inner peripheral lip, and the closer the center, the higher the contact surface pressure. I did it. Therefore, even when the shape of the sliding contact surface 12a of the convex sealing portion 12 does not slightly match the shape of the outer peripheral surface 7a of the spline groove 7,
Due to the tension of the inner peripheral side lip 10, the convex sealing portion 12 comes into close contact with the outer peripheral surface 7a with a high contact pressure. As a result, the sealing performance of the spline groove 7 can be improved.

(B) In addition, in (a), the convex sealing portion 12 has the inner peripheral side lip 10 with respect to the spline groove 7.
The thick portion 2
Compared to the case where the pressure contact is performed by pressing between 4, 25,
An increase in frictional resistance in the spline grooves 7 can be suppressed.

(C) The sliding contact surface 11a of the distal end portion 11 and the sliding contact surface 12a of the convex sealing portion 12 are connected to the spline shaft 6
Are formed in an arc shape in the direction of the central axis. Therefore, the sliding contact surface 1
1a is in close contact with the outer peripheral surface 6a of the spline shaft 6, and the sliding contact surface 12a is in close contact with the outer peripheral surface 7a of the spline groove 7 in an arc surface. As a result, since the contact surface pressure can be increased by reducing the length of the surface to be in contact with the central axis direction, the sealing performance can be further improved. Since the scraping can be prevented, the frictional resistance can be further reduced by the lubricating film formed stably. (D) The radius of curvature of the arc in the center 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 in the direction of the central axis of the sliding contact surface 11a of the tip end portion 11.
Accordingly, the length of the arc surface of the sliding contact surface 12a in close contact with the spline groove 7 can be further reduced in the central axis direction, and the frictional resistance in the spline groove 7 can be further reduced.

(E) A plurality of engaging projections 13 are provided on the back side of the U packing 5, and each of the engaging projections 13 is engaged with an engaging recess 14 provided on the left side surface 4 a of the circumferential groove 4. I made it. 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
Can be prevented from deviating or coming off with respect to the spline groove 7, so that a decrease in sealing performance due to rotation of the U packing 5 can be prevented.

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 distal end portion 11 and the sliding contact surface 12a of the convex sealing portion 12 in an arc shape in the direction of the center axis of the spline shaft 6, for example, an angle which makes line contact. It may be formed in a shape or a quadrangular shape that makes contact in a plane. Also 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 arc in the center axis direction of the sliding contact surface 12a of the convex sealing portion 12 is formed smaller than the radius of curvature R4 of the arc in the center axis direction of the sliding contact surface 11a of the tip end portion 11. However, the radius of curvature may be the same. Even in this case, the spline shaft 6 can be securely sealed,
In addition, the frictional resistance can be reduced.

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

(4) The U packing 5 without the engaging projection 13 may be used. (5) Although the U packing 5 is used for the air cylinder 1, the U packing 5 may be used for other pneumatic cylinders. Further, the present invention may be applied to a U packing used for a hydraulic cylinder.

The technical ideas other than the claims which can be grasped from the embodiment will be described below together with their effects. (1) A packing for a spline shaft in which an engaging portion 13 is provided on a base 8. According to such a configuration, rotation with respect to the spline shaft 6 can be prevented, and a decrease in sealing performance due to rotation can be prevented.

[0035] (2) spline axis packing, and air cylinder device. According to such a configuration, the spline shaft 6 used in the air cylinder device 1 can be reliably sealed, and the frictional resistance can be reduced.

[0036]

According to the invention described in each claim , the sealing performance can be improved while suppressing an increase in the frictional resistance of the spline shaft.

Further , the sealing performance can be further improved.
Moreover, the frictional resistance can be further reduced .

[Brief description of the drawings]

1A is a front view of a U packing, and FIG.

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

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

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

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

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

7A 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, 10: inner lip, 11 ...
Tip portion, 12: convex sealing portion.

Claims (2)

(57) [Claims] 1. A base (8) formed in an annular shape; and a base (8) formed at an inner peripheral end of the base (8),
1) is provided on the inner peripheral side lip (10) closely contacting the outer peripheral surface (6a) of the spline shaft (6), and on the tip end (11) of the inner peripheral side lip (10). ) Is a packing for a spline shaft having a convex sealing portion (12) pressed against the outer peripheral surface (7a) of the spline groove (7), wherein the convex sealing portion (12) is provided with the spline groove (7). )of
A sliding contact surface (12a) closely contacting the outer peripheral surface (7a);
The sliding contact as viewed from the center axis direction of the spline shaft (6).
The radius of curvature (R1) of the arc shape of the surface (12a) is
Smaller than the radius of curvature (R2) of the arc of the peripheral surface (7a)
And in the direction of the center axis of the spline shaft (6).
The radius of curvature (R3) of the arc shape of the sliding contact surface (12a) is
The above at the tip (11) of the inner lip (10)
Sliding contact surface closely contacting the outer peripheral surface (7a) of the spline groove (7)
Smaller than the radius of curvature (R4) of the arc shape of (11a)
The convex sealing portion (12) is formed in a shape viewed from the center axis direction of the spline shaft (6), and both side edges thereof are formed on the inner peripheral side lip (10) with respect to the outer peripheral surface (7a). A packing for a spline shaft, which is formed so as to be in close contact with substantially the same contact pressure as that of the spline shaft, and to be in close contact at a higher contact pressure toward the center thereof. 2. The convex sealing portion (12) has a spline shaft (6) having a width (D) in a circumferential direction of a spline groove.
The packing for a spline shaft according to claim 1, wherein the packing is formed to be equal to the width (D) in the same circumferential direction of (7) .