JPH063220Y2 - Seal mechanism - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a seal mechanism used for a pressure cylinder such as an air cylinder or a hydraulic cylinder.

TECHNICAL BACKGROUND OF THE INVENTION AND PROBLEMS THEREOF In general, as shown in FIG. 2, the pressure cylinder 1 is a pressure cylinder body in which both ends of a cylindrical cylinder 2 are sealed by rod covers 3 and 3 and connected by tie rods 4. 5, a sliding member S including a piston 6 or a piston rod 7 is provided so as to slide back and forth relative to the pressure cylinder body 5.

This piston 6 and cylinder 2 or piston rod 7
Between the rod cover 3 and the rod cover 3, a U-packing 8 made of synthetic rubber is provided in a packing groove 9 for sealing the both.

The U-packing 8 has a substantially U-shaped cross section, and as shown in detail in FIG. 3, the side where the pressure P such as hydraulic pressure is introduced from the heel portion 8a (hereinafter, simply referred to as the pressure side). Name)
It has a pair of lip portions 8b so as to project toward. The lip portion 8b expands upon receiving the pressure P and comes into pressure contact with the outer peripheral wall 10 of the packing groove 9 and the piston rod 7 and the like,
It is to seal.

However, due to the structure of the U packing 8, when the fluid pressure P decreases, the expanding force of the lip portion weakens, the sealing surface pressure decreases, and the sealing performance may deteriorate. As a means for preventing such a decrease in the seal surface pressure, the rigidity of the U packing 8 is increased to increase the expanding force of the lip portion 8b, and thereby the contact pressure between the lip portion 8b and the outer peripheral wall 10 of the packing groove 9 ( There is also one that is designed to increase the seal pressure).

However, in this case, the U packing 8 may be deformed during long-term use, the contact pressure of the lip portion 8b may be reduced, and leakage may occur.

In addition, in order to increase the contact pressure of the lip portion 8b, the projection margin (tension margin) in the radial direction may be increased. However, in this case, the sliding resistance is increased and the lip portion 8b There is a disadvantage that wear is increased and the life of the U packing 8 is shortened.

The purpose of the present invention is to solve the problems associated with the above-mentioned conventional technology. The present invention has excellent sealing properties regardless of whether the pressure acting on the U packing is high pressure or low pressure, and the U packing itself. It is an object of the present invention to provide a durable sealing mechanism for a pressure cylinder, which does not hinder the point that the frictional resistance, which is a structural advantage, is small.

SUMMARY OF THE INVENTION A sealing mechanism according to the present invention for achieving the above object includes a U packing that seals between a casing into which a fluid pressure is introduced and a sliding member that slides back and forth relative to the casing. A sealing mechanism in which a lip portion of the U-packing is fitted into a packing groove formed in one of the pressure cylinder main body or the sliding member so as to widen toward the pressure side. On the outer peripheral wall
It is characterized in that a tapered inclined portion whose diameter is reduced toward the pressure side is formed, and the opposite lip side of the U packing is elastically repelled toward the pressure side by a spring means.

In the seal mechanism having such a structure, when the pressure becomes high, the high pressure causes the lip portion of the U-packing to widen and an appropriate seal surface pressure to be obtained. Also, when the pressure drops,
The spring means moves the lip portion toward the inclined portion of the outer peripheral wall, and the inclined portion compensates for the decrease in the contact pressure of the lip portion. Therefore, even at this low pressure, an appropriate sealing surface pressure can be obtained, and regardless of the pressure level, the sealing property is generally improved and stable sealing can be performed for a long time.

DETAILED DESCRIPTION OF THE INVENTION An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of an essential part showing an embodiment of the present invention, in which members having the same functions as those shown in FIGS. 2 and 3 are designated by the same reference numerals.

The pressure cylinder sealing mechanism 20 according to the illustrated embodiment is for sealing between the rod cover 3 as a casing and the piston rod 7 as a sliding member. The pressure cylinder sealing mechanism 20 is fitted into a packing groove 9 formed in the rod cover 3, has a U-shaped cross section, and has a ring shape as a whole, and the U packing 8. The spring means 21 is provided on the opposite lip side of the U packing 8 so as to repel.

The spring means 21 has a ring-shaped spring retainer 23 that abuts a packing retainer plate 22 that is provided so as to close one end of the packing groove 9, and a pin 24 that is pressed against the heel portion 8 a of the U packing 8. It has a holding plate 25 and a coil spring 26 mounted between them.

Further, the packing groove 9 has a taper-shaped inclined portion 10a whose diameter is reduced so that the width dimension W becomes smaller as the distance from the U-packing 8 is increased in substantially half of the outer peripheral wall 10 on the pressure side. The contact pressure of the lip portion 8b is adjusted by the portion 10a.

In this case, it is desirable that the width dimension W of the packing groove 9 and the length l of the tapered inclined portion 10a have a relation of 1> W.

In addition, for example, in the case of the U packing 8 having an outer diameter of 26 to 200 mm, the tapered inclined portion 10a has a length l.
Is preferably 5 to 11 mm and the angle α is 5 to 12 degrees. More specifically, the outer diameter dimension is 26 to 45 mm,
45-90mm, 90-175mm, 175-200mm U
In the case of the packing 8, the length 1 is preferably about 5 mm, about 6 mm, about 8.5 mm and about 11 mm, respectively.

In such a U packing, the length l is 11 mm.
If it is larger, the dimension of the packing groove 9 becomes longer, and if the length is 5 mm or less, the lip portion 8 of the U packing 8 at the time of low pressure.
This is because there is a risk of damaging a. Also, the angle α is 1
If it is 2 degrees or more, the U packing 8 does not move smoothly when it is repelled by the spring means, and the angle α is 5
If it is less than 100 degrees, the size of the packing groove 9 becomes long, and the pressure cylinder sealing mechanism 20 becomes too large, which is not preferable.

Next, the operation will be described.

When the pressure P is high, the pressure P presses the U packing 8 against the elastic force of the spring means 21, and the pressure P is also applied.
Thereby, the lip portion 8b is expanded. Due to the expansion of the lip portion 8b, the lip portion 8b is brought into pressure contact with the outer peripheral wall 10 of the packing groove 9 and the piston rod 7, and an appropriate sealing surface pressure is obtained between them.

Next, when the pressure P decreases, the elastic force of the coil spring 26 of the spring means 21 overcomes the pressure P, and the lip portion 8b moves toward the inclined portion 10a of the outer peripheral wall 10. Since the width W of the inclined portion 10a becomes narrower as the U packing 8 faces the pressure side, the lip portion 8b is gradually narrowed. In other words, the lip portion 8b becomes less apt to spread due to the decrease in the pressure P, and the outer peripheral wall 10
Even if the contact pressure with the like is about to decrease, this inclined portion 10a
As a result, the lip portion 8b is compressed in the radial direction to compensate for the decrease in the contact pressure with the outer peripheral wall 10 and an appropriate sealing surface pressure can be obtained.

Therefore, regardless of whether the pressure P is high or low, the sealing performance is always improved, and stable sealing can be performed for a long period of time. Moreover, since it is not necessary to unnecessarily project the lip portion 8b inward and outward in the radial direction, there is no need to worry about wear.

In the above-described embodiment, the U packing 8 is attached to the rod covers 3 and 3.
And the piston rod 7 as a sliding member, the sliding member does not necessarily have to be the piston rod 7 and may be another sliding member.

As described above, according to the present invention, in the pressure cylinder seal mechanism, the lip portion of the U packing makes a predetermined contact with the outer peripheral wall regardless of whether the pressure acting on the packing is high pressure or low pressure. The pressure is maintained and an appropriate sealing surface pressure is obtained, so that stable sealing can be performed for a long period of time.

[Brief description of drawings]

FIG. 1 is a sectional view showing an essential part of an embodiment of the present invention, FIG. 2 is a sectional view showing a general pressure cylinder, and FIG. 3 is a sectional view showing an essential part of FIG. 5 ... Pressure cylinder body, 8 ... Packing, 8b ... Lip part, 9 ... Packing groove, 10 ... Outer peripheral wall, 10a ... Inclined part, 20 ... Pressure cylinder sealing mechanism, 21 ... Spring means, W ... Width, α ... Angle, S ... Sliding member, l ... Length.

Claims (1)

[Scope of utility model registration request] 1. A U-packing for sealing between a casing into which a fluid pressure is introduced and a sliding member that slides back and forth relative to the casing is formed on one of the pressure cylinder body and the sliding member. In a sealing mechanism in which the lip portion of the U-packing is inserted into the formed packing groove so as to expand toward the pressure side, the outer peripheral wall on the pressure side of the packing groove is reduced in diameter toward the pressure side. A seal mechanism in which a tapered inclined portion formed is formed, and the opposite lip portion side of the U packing is elastically repelled toward the pressure side by a spring means.