JPH10169611A - Tightly sealing device of cylindrical body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To contrive improvement in workability, easiness in assembly and reduction in the number of parts for a tightly sealing device by forming an annular seal groove on the outer periphery of a cap end outside of a stop ring or a screw, and fitting a seal between the groove and the internal periphery of a cylindrical body. SOLUTION: A piston rod is inserted in a cylinder tube 1 via a piston, a cap 4 is inserted therein from above of the cylinder tube 1, a thick wall part 15 is arranged below of the annular groove C and a snap ring 13 is fitted in the groove C. Then, when the piston rod is pulled upward, the upper end of the piston hits the lower end of a cap 4, and if the cap 4 is forcibly pulled upward, the cap 4 passes over the inside of the snap ring 13 to move outward, and the inside of the snap ring 13 is fitted between the outside contact surface 27b and the inside contact surface 27a, and the cap 4 is fixed. If an O ring 30 is pushed in downward from the upper side by means of a jig, etc., under this state, the O ring 30 is fitted in a seal groove 26. Thus the number of parts is small, and assembling property and workability are excellent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic device such as a hydraulic cylinder or a hydraulic shock absorber which prevents a cap disposed at an end of a cylinder such as a cylinder from moving in the axial direction and allows rainwater or the like to enter the cylinder. The present invention relates to a sealing device for a cylindrical body suitable for preventing intrusion of a cylindrical body.

[0002]

2. Description of the Related Art A hydraulic cylinder is usually provided with a cap for sealing the inside of the cylinder tube at the end of the cylinder tube. The mounting structure of this cap is, for example, as shown in FIG. 7-35126
The one disclosed in Japanese Patent Application Laid-Open Publication No. H10-260, 1993 is known.

[0003] The cap mounting structure shown in FIG. 4 has a cap 21 in which a snap ring 23 is connected to the inner circumference of the end of the cylinder tube 20, and a cap 21 between the inner circumference of the upper end of the cylinder tube 20 and the outer circumference of the upper end of the cap 21. And a plate 25 connected to the upper end surface of the cap 21 via bolts 26 and having a lower surface in contact with the upper end surface of the cylinder tube 20. , A piston rod 22 is slidably contacted via a seal.

In the above cap mounting structure, the cap 21 is inserted into the cylinder tube 20 via a seal, and then the snap ring 23 is fitted into the inner peripheral groove of the cylinder tube 20, and then the cap 21 is moved upward. And forcibly insert the seal 24 between the cap 21 and the cylinder tube 20 while keeping the upper end surface at the same level as the upper end surface of the cylinder tube 20. The bolt 26 is tightened while being in contact with the bolt. At this time, if the seal 24 is forcibly inserted, the cap 21 moves downward due to friction.
The seal 24 is mounted in a state where the cap 21 is pulled up in advance so as not to move downward, and then the bolt 26 is removed.
To fasten to the cap 21.

On the other hand, the cap mounting structure disclosed in Japanese Utility Model Publication No. Hei 7-35126 discloses a cap having a snap ring interposed between an inner peripheral fixing groove of a cylinder tube and a contact surface formed on an outer periphery of the cap. Of the cap is prevented from coming out in the axial direction, and a stop ring facing the snap ring is attached to the outside of the outer periphery of the cap to restrict the movement of the cap in the axial direction. That is, in the cap mounting structure, when an external load is applied to the cap due to the internal pressure in the cylinder tube, the outward movement in which the contact surface of the cap contacts the lower outer surface of the snap ring is restricted, and conversely, When an inward load acts on the cap due to external pressure, the stop ring abuts against the upper outer surface of the snap ring to prevent the cap from moving inward.

[0006]

The above-mentioned conventional cap mounting structure does not cause any problem in operation and effect, but has some disadvantages in workability, mounting performance and cost.
That is, the cap mounting structure shown in FIG.
It is necessary to use bolts 26 or other jigs in advance so that the cap 21 itself does not move downward when the device is mounted, so that the assembling work of the seal 24 is troublesome. Since the plate 25 and the bolt 26 are required to hold the plate 24, the number of parts is large, and the assemblability and economic efficiency are poor.

Further, in the cap mounting structure disclosed in the above publication, since a stop ring is also provided on the cap side, the processing is troublesome, the processing cost increases, and the stop ring is fitted into the groove. Therefore, the assembling work is troublesome and cost increases, and the number of parts increases due to the necessity of a stop ring, resulting in an increase in weight and cost.

Accordingly, it is an object of the present invention to improve workability, facilitate assembly, reduce the number of parts, excel in economy, improve sealing in the cylinder, and remove the cap from the cylinder. An object of the present invention is to provide a sealing device for a cylinder suitable for prevention.

[0009]

According to a first aspect of the present invention, a cap for sealing the inside of a cylindrical body is disposed on an inner peripheral side of an end of the cylindrical body. In a cylindrical sealing device connected to the inner periphery of a body via a stop ring or a screw, an annular seal groove is formed on an outer periphery of an end portion of the cap outside the stop ring or the screw, and the seal is formed. A seal is fitted between the groove and the inner periphery of the cylindrical body.

[0010] Similarly, in a second configuration, a cap for sealing the inside of the cylindrical body is disposed on the inner circumferential side of the end of the cylindrical body, and a half of the outer diameter section or the snap ring of the snap ring is provided in a groove formed on the inner circumference of the cylindrical body. Approximately half are fitted, and the inner contact surface formed on the outer periphery of the end of the cap contacts the snap ring to prevent the cap from coming off in the axial direction. The outer contact surface formed between the caps is brought into contact with the snap ring to prevent the cap from coming inward in the axial direction, and a seal groove is formed in the outer periphery of the cap outside the outer contact surface. The outer diameter of the outer mounting surface in the groove is smaller than the outer diameter of the inner mounting surface and larger than the inner diameter of the seal.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings.

1 to 3 show an embodiment of the present invention applied to a hydraulic cylinder.

As shown in FIG. 1, a hydraulic cylinder A includes a cylinder tube 1 as a cylindrical body and a piston rod 3 movably inserted into the cylinder tube 1 via a piston 2.
A cap 4 fixed to the end of the cylinder tube 1 via a stopper structure B; an O-ring 30 serving as a seal interposed between the inner periphery of the upper end of the cylinder tube 1 and the outer periphery of the upper end of the cap 4; Piston 2 in tube 1
Pressure chambers 5 and 6, oil passages 7 and 8 communicating with the pressure chambers 5 and 6 formed in the cylinder tube 1, and a dust seal provided on the inner periphery of the cap 4 and in sliding contact with the piston rod 3. 9 and an oil seal 10.

The hydraulic cylinder A supplies pressure oil to the oil passage 8, and when the oil passage 7 is connected to the tank, the piston 2 and the piston rod 3 extend, and conversely, the oil passage 8 is connected to the tank. 7 is connected to a pump and compressed when pressure oil is supplied.

The O-ring 30 according to the present invention is disposed above the retaining structure B to prevent intrusion of rainwater, dust and the like from the outside and to prevent grease and the like filled in the retaining structure B from leaking to the outside. It is to prevent.

A seal groove 26 is formed on the outer periphery of the upper end of the cap 4, and the seal groove 26 is formed from outside after the cap 4 is assembled.
The O-ring 30 as a seal is forcibly fitted therein. As will be described later, the seal groove 26 has an inner mounting surface 26a with which the inside of the O-ring 30 contacts, and an outer mounting surface 26b with which the outside of the O-ring 30 contacts.

In the stop structure B, the cap 4 may be screw-connected to the inner periphery of the end of the cylinder tube 1, but in the present embodiment, the case where the cap 4 is connected by the snap ring 13 will be described.

The inner circumference 11 at the end of the cylinder tube 1 is expanded outward from the inner circumference 12 of the main body of the cylinder tube 1,
A snap ring 1 serving as a stop ring is provided on the inner circumference 11 side.
3 is provided to prevent the seal 16 from being damaged by the operation of assembling the cap 4. The cap 4 has a thickened portion 15 which bulges outward from the outer periphery 14 of the main body of the cap 4 and has an increased diameter. A contact surface 27 facing the snap ring 13 is formed at an end of the thickened portion 15. Has formed.

The main body of the cylinder tube 1 is provided with an inner periphery 12 with which the piston 2 slides through a seal on the outer periphery thereof, and the inner periphery 11 at the end of the cylinder tube 1 is expanded outward from the inner periphery 12 of the main body. An annular groove c for fitting the snap ring 13 is formed on the inner circumference 11 of the end.

A half or substantially half of the cross section of the snap ring 13 in the outer diameter direction is fitted and held in the annular groove c, and a half or substantially half of the cross section of the snap ring 13 is inward from the inner circumference 11 of the cylinder tube 1. It protrudes.

The cap 4 has an outer periphery 14 abutting against the inner periphery 12 of the cylinder tube 1 via a seal 16, and further has an annular or spaced-apart outer periphery of the end of the cap 4 which is radially expanded from the outer periphery 14 of the main body. A thick portion 15 serving as a land is formed, and the outer surface of the thick portion 15 is fitted to the inner periphery 11 of the cylindrical portion of the cylinder tube 1.

The end face of the thick portion 15 of the cap 4 is provided with a contact surface 27 that contacts the snap ring 13.
7 is formed by bending the snap ring 13 along the spherical surface of the snap ring 13 as shown in FIG.
It is preferable in terms of strength because a large contact area with the contact can be secured.

Further, the contact surface 27 of the cap 4 has a diameter larger than the inner diameter of the snap ring 13 and continues to the outer diameter of the thick portion 15 of the cap 4 to prevent the cap 4 from moving outward. 27a and an outer abutment surface 27b which is larger in diameter than the inner diameter of the snap ring 13 and smaller than the abutment surface 27a and is continuous with the vertical surface d to prevent the cap 4 from moving inward.
Is formed. That is, in FIG. 3, the lower contact surface 2
7a is located below the center P in the cross section of the snap ring 13 in the line body, and the upper contact surface 27b is located above the center P.

In the seal groove 26, the inner mounting surface 26a is connected to the outer diameter of the vertical surface d, and the outer mounting surface 26b is connected to the vertical surface d.
Is connected to the inner end of the tapered surface e having a diameter smaller than the outer diameter of the O-ring 30 and larger than the inner diameter of the O-ring 30. That is, in FIG. 3, the lower inner mounting surface 26a is located below the center Q in the line section of the O-ring 30, and the upper outer mounting surface 26b is located above the center Q. Therefore, when the O-ring 30 is inserted through the tapered surface e in the mounting operation of the O-ring 30, the outer diameter of the inner mounting surface 26a is large. Can be installed without passing.

When the cap 4 is attached, for example,
1, 2 and 3 are performed as follows.

A piston rod 3 is inserted into a cylinder tube 1 via a piston 2. In this case, when the inner circumference 11 of the end of the cylinder is larger than the inner circumference 12 of the main body, the outer peripheral seal of the piston does not interfere with the edge of the groove c, and the piston 2 can be inserted without damaging the seal. .

Next, the cap 4 is inserted into the cylinder tube 1 from above in FIG. 3, and the thick portion 15 is disposed below the annular groove c of the cylinder tube 1. In this state, the snap ring 13 is inserted into the annular groove c. Is fitted.

Next, when the piston rod 3 is pulled upward, the upper end of the piston 2 hits the lower end of the cap 4, and when the cap 4 is forcibly pulled up, the cylinder tube 1 is slightly bent in the outer diameter direction, or the upper end of the cap 4 Is slightly bent in the inner diameter direction, and the cap 4 moves over the inside of the snap ring 13 and moves outward through the tapered surface e and the vertical surface d.
At this time, the inside of the snap ring 13 is
And the inner contact surface 27a is fitted in the inner contact surface 27a, and the inner contact surface 27a contacts the snap ring 13, so that the cap 4 cannot move further axially outward. In the above-mentioned state, even if an external load acts on the cap 4, the outer contact surface 27 b of the cap 4 has the snap ring 13 unless a large external force acts on the upper end of the cylinder tube 1 or the cap 4. Does not move inward in the axial direction.

Although it can be carried out without the tapered surface e,
In order to mount the snap ring 13 and the O-ring 30 smoothly, it is preferable to form them.

Although the piston 2 and the piston rod 3 are used by being pulled up from the outside in order to pull up when the cap 4 is mounted, the piston 2 may be extended by supplying pressure oil from the oil passage 8, or The pressure oil may be guided from the oil passage 7 to the pressure chamber 5, and the cap 4 may be pushed up using the internal pressure of the pressure chamber 5.

After the cap 4 is mounted as described above, the cap 4 does not move downward. In this state, if the O-ring 30 is pushed downward through the tapered surface e using a jig or the like from above, O The ring 30 does not fit into the seal groove 26 and cannot come off. For this reason, rainwater and dust do not enter from the outside of the O-ring 30, and leakage of grease, oil, and the like to the outside is prevented.

[0032]

According to the invention of each claim, the seal groove is formed on the outer periphery of the end of the cap, and the seal is fitted in the seal groove, so that rainwater and dust enter the cylinder from the outside. This prevents the grease and oil filled in the stop structure such as the stop ring and the screw portion from leaking to the outside.

Similarly, when the seal is fitted, the outer contact surface of the cap is in contact with the stop ring in advance, so that the cap does not move into the cylinder due to the pressing force of the seal, thereby improving workability.

Similarly, since the seal can be fixed by being fitted into the seal groove formed in the cap, other members for fixing the seal are not required, the number of parts is small, the assembling property,
Excellent workability and economy.

According to the second aspect of the present invention, the inner contact surface hits the snap ring against the axially outward load of the cap, and the outer abutment surface against the axially inward load. Also hits the snap ring so that the cap does not move in either direction and can be held in place. In addition, since the cap can be fixed only by forming the two surface portions, the number of parts is small, the workability and economy are excellent, and even when a seal such as an O-ring is installed in the seal groove, the cap moves inward. A jig or the like for restricting the movement of the work is unnecessary, and the workability is remarkably improved.

[Brief description of the drawings]

FIG. 1 is a vertical sectional front view of a hydraulic cylinder using a stop structure according to an embodiment of the present invention.

FIG. 2 is a partially enlarged sectional view of FIG.

FIG. 3 is an enlarged sectional view of a seal and a stop structure.

FIG. 4 is a partially cutaway sectional view of a conventional hydraulic cylinder.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder tube which is a cylindrical body 13 Snap ring which is a stop ring 15 Thick part which is a land 26 Seal groove 26a Inside contact surface 26b Outside contact surface 27 Contact surface 27a Inside mounting surface 27b Outside mounting surface 30 Sealing O-ring c groove d Vertical surface e Tapered surface

Claims (2)

[Claims] 1. A sealing device for a cylindrical body, wherein a cap for sealing the cylindrical body is disposed on an inner peripheral side of an end portion of the cylindrical body, and the cap is connected to an inner peripheral of the cylindrical body via a stop ring or a screw. An annular seal groove is formed on the outer periphery of the end of the cap outside the stop ring or the screw, and a seal is fitted between the seal groove and the inner periphery of the cylindrical body. Body sealing device. 2. A cap for sealing the inside of the cylindrical body is disposed on the inner peripheral side of the end of the cylindrical body, and a half or substantially half of the outer diameter cross section of the snap ring is fitted into a groove formed on the inner circumference of the cylindrical body. The inner contact surface formed on the outer periphery of the end of the cap is brought into contact with the snap ring to prevent the cap from coming off in the axial direction, and the outer surface formed by sandwiching the snap ring with the contact surface. The contact surface is brought into contact with the snap ring to prevent the cap from coming inward in the axial direction, and a seal groove is formed on the outer periphery of the cap outside the outer contact surface, and the outer mounting surface in the seal groove is formed. Wherein the outer diameter of the cylinder is smaller than the outer diameter of the inner mounting surface and larger than the inner diameter of the seal.