WO2010018640A1

WO2010018640A1 - Piston sealant

Info

Publication number: WO2010018640A1
Application number: PCT/JP2008/064650
Authority: WO
Inventors: 彰上田; 晃広永野; 純一山下; 暢南
Original assignee: 日本バルカー工業株式会社
Priority date: 2008-08-15
Filing date: 2008-08-15
Publication date: 2010-02-18

Abstract

[PROBLEMS] To provide a piston sealant which contributes to cost reduction by reducing the number of components and which is less likely to come off by improving mounting property. [MEANS FOR SOLVING PROBLEMS] The piston sealant is composed of a cylindrical sealant main body (14) which is housed in an annular seal groove (7) formed in the outer circumferential surface of a piston (1) reciprocating on the inner circumferential surface (4a) of a cylinder (4) and a first guide ring (16a) and a second guide ring (16b) which are respectively mounted between both of the ends of the sealant main body (14) in an axial direction and both of the lateral walls of the seal groove (7) in order to prevent the sealant main body (14) from projecting from the seal groove (7). The piston sealant is characterized in that the sealant main body (14) has a convex part (18) obtained by radially swelling its outer circumferential surface at an intermediate part in an axial direction and has concave parts (20a, 20b) for receiving the first guide ring (16a) and the second guide ring (16b) formed respectively on the outer circumferential surface at both of the ends in the axial direction, and that the first guide ring (16a) and the second guide ring (16b) have cylindrical parts (26) which are made of hard resin and slidingly contact with the inner circumferential surface (4a) of the cylinder (4) in the axial direction and inner flange parts (28) which are connected at a right angle to respectively one ends of the cylindrical parts (26) to fit into the concave parts (20a, 20b) of the sealant main body (14).

Description

Piston seal material

The present invention relates to, for example, a piston seal material, and more particularly, to a piston seal material mounted on a piston that slides in an axial direction on an inner peripheral surface of a hydraulic cylinder.

In various hydraulic cylinders, for example, a piston seal material is used to guide the gentle sliding of a piston operated by hydraulic pressure.

FIG. 4 is a cross-sectional view showing a relationship between the hydraulic cylinder 4 and the piston 1 on which the conventional piston seal material 2 disclosed in Non-Patent Document 1 is mounted.

An annular first seal groove 3 is formed on the outer peripheral surface of the substantially cylindrical piston 1, and a large-diameter second seal groove 5 is formed in communication with the opening end side of the first seal groove 3. . That is, the seal groove of the piston 1 of this embodiment is composed of a large-diameter portion on the inlet side and a small-diameter portion on the inner side.

On the other hand, the piston seal material 2 mounted in the seal groove includes a seal material body 6 mounted in the first seal groove 3, and

backup rings

8a and 8b disposed at both axial ends of the seal material body 6. And

guide rings

10a and 10b mounted between the second seal groove 5 and the first seal groove 3 outside the

backup rings

8a and 8b. That is, the piston seal material 2 is composed of five members.

For example, when the piston 1 to which such a piston seal material 2 is attached is pressed by hydraulic pressure from the upper side in FIG. 4, it moves downward by the hydraulic pressure.

At this time, in the piston seal material 2, the sliding contact with the cylinder 4 is ensured by the relatively

hard guide rings

10a and 10b, and the flexible seal material main body is provided by the

backup rings

8a and 8b softer than the

guide rings

10a and 10b. While the protrusion of 6 is prevented, sealing performance is ensured.
Nippon Torelborg Sealing Solutions Co., Ltd. (former name: Nippon Busak and Shabang Co., Ltd.) Product Catalog, page 27 http://tss.trelleborg.com/com/www/media/downloads/catalogs/product#range#jp # 1.pdf

By the way, in such a piston seal material, since the two

backup rings

8a and 8b and the two

guide rings

10a and 10b are arranged on both sides in addition to the seal material body 6 arranged in the center portion, the whole As a result, there is a problem that the number of parts increases and the cost increases. In addition, there is a problem that it takes time to install the seal groove.

In addition, in such a conventional piston seal material, the seal material body 6 protrudes into the gap between the

backup rings

8a and 8b and the radially inner side of the seal groove 3 as the piston 1 slides, and the seal There was a problem that the material main body 6 was bitten and tearing occurred on the radially inner side.

Also, circumferential damage occurred in the

backup rings

8a and 8b. This is considered to be due to the following reason. That is, when the pressure is applied, when the

backup rings

8a and 8b are pressed against the

guide rings

10a and 10b, the seal material body 6 is similarly deformed following this. Thereby, it is estimated that the thinnest part of the

backup rings

8a and 8b is damaged without being able to withstand the deformation and load.

The present invention has been made in view of such conventional circumstances, and has an object to provide a piston seal material that has a small number of parts, contributes to cost reduction, and has good mountability and is not easily broken.

The piston sealing material according to the present invention for achieving the above object is
A cylindrical sealing material main body accommodated in an annular sealing groove formed on the outer peripheral surface of the piston that reciprocates on the inner peripheral surface of the cylinder;
In order to prevent the seal material body from protruding from the seal groove, a first guide ring and a second guide ring respectively mounted between both end portions of the seal material body in the axial direction and both side walls of the seal groove. A piston seal material composed of a guide ring,
The sealing material main body has a convex portion in which an outer peripheral surface of an axially intermediate portion bulges in a radial direction, and the first guide ring and the second second outer peripheral surface of both axial end portions. Recessed parts that receive the guide ring are formed,
The first guide ring and the second guide ring are made of hard resin, and are connected to the cylindrical portion slidably in the axial direction with the inner peripheral surface of the cylinder, and are connected to one end of the cylindrical portion at right angles to the seal. And an inward flange portion that fits into the concave portion of the material main body.

According to the present invention having such a configuration, the number of parts can be reduced and the cost can be reduced. In addition, since the concave portion that receives the guide ring is formed in the seal material main body, the guide ring and the seal material main body can maintain a stable posture even when moved by hydraulic pressure.

In the present invention, it is preferable that the first guide ring and the second guide ring are made of polyacetal resin reinforced with glass fibers.

With such a configuration, a bearing function can be sufficiently imparted to the first guide ring and the second guide ring.

Further, in the present invention, in a state where the first guide ring and the second guide ring are mounted in the seal groove, the axially outer end portions of the first guide ring and the second guide ring The clearance with the outer end of the seal groove is preferably 0.1 mm or less.

With such a configuration, the first guide ring and the second guide ring are securely mounted in the seal groove, thereby preventing the guide ring from moving in the axial direction. Biting and tearing can be prevented as much as possible.

Further, in the present invention, the concave portion of the seal material main body and the tip end portion of the inner flange of the guide ring are configured by a curved surface having a substantially complementary shape, and the radius of the curved surface is set to R, the outside of the piston. When the groove width dimension obtained by subtracting the piston seal groove inner diameter from the diameter is H,
R> 1 / 3H is preferred.

With such a set dimension, if the receiving portion is formed in an arc shape, even if the guide ring is deformed by movement, there is no possibility that the seal material body is destroyed by the movement.

The piston seal material according to the present invention is inexpensive because the number of parts is small and the shape is not complicated. Moreover, since the number of parts is small, the mountability is also good. Furthermore, since the guide ring is made of a hard resin, the guide ring can exhibit a bearing function. Moreover, since the recessed part used as a receiving of a guide ring is formed in the sealing material main body, the stable state at the time of contact | abutting can be maintained.

FIG. 1 is a cross-sectional view showing the relationship between a piston fitted with a piston sealing material according to an embodiment of the present invention and a hydraulic cylinder. FIG. 2 is a cross-sectional view of a sealing material body constituting the piston sealing material shown in FIG. FIG. 3 is a half sectional view of a guide ring constituting the piston seal material shown in FIG. FIG. 4 is a cross-sectional view showing a relationship between a piston fitted with a conventional piston seal material and a hydraulic cylinder.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Piston 3 1st seal groove 4 Hydraulic cylinder 4a Inner peripheral surface 5 2nd seal groove 7 Seal groove 12 Piston seal material 14 Seal material main body 16a 1st guide ring 16b

2nd guide rings

20a and 20b Recessed part 26 Cylindrical part 28 Inner flange part

Hereinafter, preferred embodiments of the present invention shown in the drawings will be described.

FIG. 1 is a cross-sectional view showing a piston and a hydraulic cylinder equipped with a piston sealing material according to an embodiment of the present invention. The same elements as those in FIG.

An annular first seal groove 3 is formed on the outer peripheral surface of the substantially cylindrical piston 1, and a large-diameter second seal groove 5 is formed in communication with the opening end side of the first seal groove 3. . That is, the seal groove 7 of the piston 1 of the present embodiment is constituted by the first seal groove 3 and the second seal groove 5.

On the other hand, the piston seal material 12 of this embodiment mounted in the seal groove 7 includes a seal material body 14 having a substantially chevron cross section mounted in the first seal groove 3 and both axial ends of the seal material body 14. It is comprised from the

guide rings

16a and 16b arrange | positioned at a part. That is, the piston seal material 12 is composed of three members. The seal body 14 is symmetrical in the axial direction, and the guide rings 16a and 16 are formed in the same shape. However, the piston seal material 12 is not necessarily symmetrical.

As shown in FIG. 2, the piston seal material 12 has a convex portion that bulges in the radial direction (arrow B direction) perpendicular to the axial direction on the outer peripheral surface in the axial direction indicated by the arrow AA ′. 18.

The sealing material main body 14 has

concave portions

20a and 20b formed in arc shapes at both ends in the axial direction.

The sealing material body 14 has

small protrusions

22a and 22b and second

concave portions

24a and 24b formed on the way from the

concave portions

20a and 20b at both ends to the convex portion 18 at the center. Yes. A gap is secured between the

small protrusions

22 a and 22 b and the inner peripheral surface 4 a of the cylinder 4. In this way, the clearance around the

small protrusions

22a and 22b is secured, so that the sealing material body 14 is prevented from being bitten.

On the other hand, since the guide rings 16a and 16b of the present embodiment have the same shape, the guide ring 16a will be described below with reference to FIG.

The guide ring 16a (16b) has a cylindrical portion 26 that is in sliding contact with the inner peripheral surface 4a of the cylinder 4, and an inner flange portion 28 that is connected at a right angle from the cylindrical portion 26 inward. . Further, although the guide ring 16a is formed in an annular shape as a whole, a slit is formed in a part of the outer periphery in the axial direction or in a direction inclined obliquely with respect to the axial direction in consideration of the mounting property to the piston 1. Has been. In this way, the guide ring 16a can be expanded in the radial direction through one slit, so that the mounting property to the outer periphery of the piston 1 is improved. Further, the front end portion of the inner flange portion 28 is mounted so as to face the first seal groove 3. Further, the distal end portion of the inner flange portion 28 is formed in a substantially complementary shape corresponding to the concave portion 20 a of the sealing material body 14. Although the radius R of the arc of the concave portion 20a and the inner flange 28 varies depending on the dimension of the seal groove, as shown in FIG. 1, the radius R is a width dimension obtained by subtracting the seal groove inner diameter from the piston outer diameter. When H, R> 1 / 3H is preferable. According to the experiment, when the radius R was set to such a dimension, the sealing material body did not break. On the other hand, when the radius R was 28% of H and the condition of R> 1 / 3H was not satisfied, damage to the seal material body was confirmed.

Further, it is preferable that the guide rings 16a and 16b are formed of an engineering plastic obtained by reinforcing polyacetal resin (POM) with glass fiber. If the polyacetal resin is reinforced with glass fibers in this way, the deformation of the guide rings 16a and 16b can be prevented as much as possible.

As described above, the piston seal material 12 including the seal material main body 14, the first guide ring 16a, and the second guide ring 16b is attached to the piston 1 as follows. .

That is, first, the seal body 14 is mounted in the first seal groove 3 of the piston 1. Thereafter, the first guide ring 16a and the second guide ring 16b are expanded by the slits described above, and are mounted on both sides of the seal material main body 14. In addition, after mounting | wearing with

guide ring

16a, 16b, the clearance gap between slits is sealed. At this time, the inner flange portions 28 of the first guide ring 16a and the second guide ring 16b are fitted into the

concave portions

20a and 20b of the cylinder body 14, respectively. Thereby, each front-end | tip part of the inner flange 28 of the guide rings 16a and 16b is fitted with the recessed

parts

20a and 20b of the cylinder main body 14 with substantially no gap.

Furthermore, when the guide rings 16a and 16b are mounted on the outer periphery of the piston 1, the clearance between the axially outer end of the cylindrical portion 26 and the outer end of the seal groove 5 in the guide rings 16a and 16b is 0. It is preferable that it is 1 mm or less. As described above, if the guide rings 16a and 16b are mounted without gaps in the axial direction of the seal groove, the movement and deformation of the guide rings in the axial direction can be prevented as much as possible. Moreover, this can prevent the sealing material body 14 from being bitten as much as possible.

When the hydraulic pressure is applied in the direction of arrow A ′ from the upper side of the piston 1 in FIG. 1 to the piston 1 to which the piston seal material 12 is mounted in this way, the piston 1 is pressed in the axial direction (downward in FIG. 1). Slid along the inner peripheral surface 4 a of the cylinder 4. At this time, the relatively hard guide ring 16a presses the concave portion 20a of the softer cylinder body 14 than this. On the other hand, the lower guide ring 16 b is subjected to deformation of the concave portion 20 b of the cylinder body 14. In this way, the piston 1 moves downward. The guide rings 16a and 16b are in contact with the substantially complementary

concave portions

20a and 20b, so that they do not protrude from the seal groove 3, and the cylinder body 14 and the guide rings 16a and 16b, etc. There will be no damage. Further, the sealing performance is ensured by the convex portion 18 of the piston seal material 12.

As mentioned above, although the piston sealing material 12 which concerns on one Example of this invention was demonstrated, this invention is not limited to the said Example at all.

For example, in the above-described embodiment, the example in which the piston 1 is operated by the hydraulic pressure supplied into the cylinder 4 has been described. However, the present invention is not limited to this. For example, the arrow A- The present invention can also be applied to a hydraulic cylinder in which the piston 1 moves in the A ′ direction.

Furthermore, in the above embodiment, the seal groove 7 in which the piston seal material 12 is mounted is composed of the two seal grooves 3 and 5, but is not limited to this, and only one seal groove 3 may be provided. That is, the cylindrical portions 26 of the guide rings 16 a and 16 b may be directly attached to the outer peripheral surface of the piston 1 instead of being accommodated in the seal groove 5.

Claims

A cylindrical sealing material body housed in an annular sealing groove formed on the outer peripheral surface of the piston that reciprocates on the inner peripheral surface of the cylinder;
In order to prevent the seal material body from protruding from the seal groove, a first guide ring and a second guide ring respectively mounted between both end portions of the seal material body in the axial direction and both side walls of the seal groove. A piston seal material composed of a guide ring,
The sealing material main body has a convex portion in which an outer peripheral surface of an axially intermediate portion bulges in a radial direction, and the first guide ring and the second second outer peripheral surface of both axial end portions. Recessed parts that receive the guide ring are formed,
The first guide ring and the second guide ring are made of hard resin, and are connected to the cylindrical portion slidably in the axial direction with the inner peripheral surface of the cylinder, and are connected to one end of the cylindrical portion at right angles to the seal. A piston sealing material, comprising: an inner flange portion that fits into the concave portion of the material main body.
2. The piston seal material according to claim 1, wherein the first guide ring and the second guide ring are made of polyacetal resin reinforced with glass fibers.
In a state where the first guide ring and the second guide ring are mounted in the seal groove, the outer ends of the first guide ring and the second guide ring in the axial direction and the outside of the seal groove The piston seal material according to claim 1 or 2, wherein a gap with an end is 0.1 mm or less.
The concave portion of the seal material main body and the tip end portion of the inner flange of the guide ring are configured by a curved surface having a substantially complementary shape, and the radius of the curved surface is changed from R to the piston seal groove inner diameter from the piston outer diameter. When the groove width dimension minus is H,
2. The piston seal material according to claim 1, wherein R> 1 / 3H.