JPS60245880A - Sealing mechanism - Google Patents

Abstract

PURPOSE:To simplify construction, by playably fitting an annular back-up ring, which moves in a free state by a pressure difference of fluid, in an annular groove to its inner side from a sealing ring, in the case of a sealing mechanism. CONSTITUTION:A sealing mechanism 7 in a butterfly valve 3 has an annular groove 13, sealing ring 14 having a cut part 14a, sealing ring 15 having a cut part 15a and a back-up ring 16. The back-up ring 16, which moves in a free state from a high pressure side to a low pressure side by a pressure difference of fluid in the annular groove 13, can close the cut part 14a or 15a. As a result, construction of the sealing mechanism is simplified by enabling a leak of fluid to be surely prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a sealing mechanism used to prevent fluid leakage.

(B) Prior Art Conventionally, in this type of sealing mechanism, a pair of seal rings having a notch in an annular groove provided on the outer periphery of an inner member such as a butterfly/help, etc. is placed at a position where the notch is substantially opposite to each other. Some seal rings are fitted in an overlapping state, and the seal ring is brought into sliding contact with an outer member such as a casing surrounding the inner member to prevent fluid leakage. Specifically, as shown in Fig. 4, an annular groove is provided on the outer periphery of the inner member/help a, and a pair of seal rings e and f having cutouts c and d are respectively inserted into the annular groove. Notch C
, d are shifted by approximately 180° in the circumferential direction and are fitted over each other, and both seal rings e and f are brought into sliding contact with the casing g, which is an outer member. In such a rail mechanism, the sole ring is provided with a notch in order to absorb the difference in thermal expansion between the seal ring and the outer member when the temperature rises. Therefore, such a sealing mechanism cannot be used at high temperatures.
For example, it is suitable for use in preventing leakage of high temperature fluid.

Furthermore, the reason why the pair of seal rings are stacked one on top of the other with the notches substantially facing each other is to prevent fluid from leaking from the notches.

However, even with such a device, leakage of fluid from the notch cannot be reliably prevented. However, if we take the seal mechanism shown in FIG. 4 as an example, the fourth
As shown by the arrow in the figure, fluid flows into the annular groove from the high-pressure region JI&A through the notch C of the upper seal ring e, goes around the annular groove approximately halfway, and then seals the lower seal. This is because it flows out from the notch d of the ring f to the region B on the low pressure side. Such leakage is noticeable when the temperature inside the outer member is low and therefore the seal ring does not expand and the width of the notch is wide.

(c) The objective tree invention was made with attention to these circumstances.
It is an object of the present invention to provide a sealing mechanism that can reliably prevent fluid leakage, has a simple structure, and is easy to implement.

(d) In order to achieve this object, the invention is characterized in that an annular backup ring that moves freely due to the pressure difference of the fluid is loosely fitted inside the seal ring of the annular groove of the conventional device.

(e) Example An example of the present invention will be described below with reference to FIGS. 1 to 3.

A butterfly valve 3 is interposed in a conduit 2 formed in a casing 1, which is an outer member, to control the flow of fluid. , a valve shaft 5, an actuator 6, and a sealing mechanism 7.The integral member 4 is formed by bringing the back surfaces of two butterfly plates 8 and 9, each having an annular cutout on the outer periphery of the back surface, into close contact with each other. The valve shaft 5 is disposed slightly inclined from perpendicular to the axial direction of the casing 1, and is arranged at approximately the center in the axial direction so as to be able to rotate together with the valve body 4. Actuator 6
is arranged outside the casing l, and is configured to rotate the valve shaft 5 within a range of 90'' around the axis. It is a bearing that can be supported by the casing 1. Also, the sealing mechanism 7
is an annular groove 13, a seal ring 14 having a notch 14a, and a seal ring 15 having a notch 15a;
It has a backup ring 16. The annular groove 13 is formed by aligning the annularly cut inner peripheries of both butterfly plates 8.9.

The two seal rings 14 and 15 form a pair, and are placed one on top of the other with the notches 14a and 15a placed at substantially opposite positions, that is, at positions offset from each other by about 180'' in the circumferential direction. The backup ring 16 is fitted into the annular groove 13. The backup ring 16 is an annular member loosely fitted inside the annular groove 13 than the seal rings 14 and 15, and prevents the fluid in the annular groove 13 from flowing. Due to the pressure difference, the cutout portion 14a or 15 moves freely from the high pressure side to the low pressure side.
It is now possible to block a.

In addition, in FIG. 1, for convenience of explanation, notches 14a,
The positions of 15a are shifted approximately 90 degrees in the circumferential direction from the actual positions. Please refer to Figure 2 for details.

Next, the operation of this embodiment will be explained.

When the actuator 6 is actuated to rotate the valve shaft 5 and the valve body 4 closes the pipe line 2, the valve body 4 blocks the flow from the high pressure region A to the low pressure region B. Further, the seal rings 14 and 15 of the seal mechanism 7 are in sliding contact with the inner circumferential surface of the casing 1 during such shutoff, and the seal rings 14 and 15 of the seal mechanism 7 are in sliding contact with the inner circumferential surface of the casing 1.
Prevent fluid from leaking from the gap between the At this time,
A part of the fluid in the area A on the high pressure side flows from the notch 14a of the seal ring 14 to the annular groove 13 as shown by the arrow in FIG.
It flows into the annular groove, goes around the annular groove approximately halfway, and then tries to flow out from the notch 15a of the seal ring 15 to the region B on the low pressure side.

However, when the fluid flows into the annular groove 13 from the notch 14a, a pressure difference is generated in the annular groove 13 due to the pressure of the fluid, and the backup ring 16 moves toward the notch 15a due to the pressure difference. 15a is closed. Therefore, the fluid that has flowed into the annular groove 13 is transferred to the notch 15.
The fluid cannot flow out from the annular groove 13 and remains in the annular groove 13, thereby preventing fluid from leaking from the high-pressure region A to the low-pressure region B.

In this way, fluid flow is blocked, and in this embodiment, the seal ring 14 of the annular groove '13.
With the simple structure of adding a simple component such as loosely fitting an annular backup ring 16 that moves inwardly from 15 due to the pressure difference of the fluid, even if fluid flows into the annular 1113 when the pipe line 2 is shut off, , the backup ring 16 moves toward the notch 15a due to the pressure difference within the annular 44713 caused by the inflow of fluid, and the backup ring 16 moves toward the notch 15a.
Since the notch 15a is closed, fluid can be prevented from leaking from the notch 15a to the low-pressure region B unlike in the conventional case. Further, since the backup ring 16 has a simple annular shape, it can be manufactured at low cost, and therefore there is almost no problem of increased cost.

It should be noted that the present invention is of course not limited to the above-mentioned embodiments, and the present invention is not limited to butterfly valves, but may be applied to pistons, for example.

Furthermore, the number of seal rings is not limited to two, but may be three or more as long as they form a pair.

Various modifications can be made without departing from the spirit of the invention.

(F) Effects Since the present invention has the above-described configuration, it is possible to provide a sealing mechanism that can reliably prevent fluid leakage and is simple in structure and easy to implement.

[Brief explanation of the drawing]

1 to 3 show one embodiment of the present invention, FIG. 1 is a front sectional view, FIG. 2 is a partially enlarged sectional view taken along line II-II in FIG. 1, and FIG. 3 is a seal ring and backup It is a perspective view showing a ring. FIG. 4 is a sectional view showing a conventional example. Knee...Outer member (casing) 3...Butterfly valve 4...Inner member (valve body) 7φ...Seal mechanism 13...Annular groove 14.15##I seal ring 14a, 15a--Fist Notch 16... Backup ring agent Patent attorney Hiroshi Akazawa ■1 Figure 2

Claims (1)

[Claims] A pair of seal rings each having a cutout in an annular groove provided on the outer periphery of the inner member are fitted in an overlapping state with the cutouts substantially opposed to each other, and the seal ring is attached to an outer surface surrounding the inner member. In a sealing mechanism that prevents leakage of the corrugated body by slidingly contacting a member, an annular banker that moves inside the seal ring of the annular groove due to a pressure difference of the fluid! A seal mechanism characterized by a loosely fitted spring.