JPH0726621Y2 - Seal mechanism of valve stem in switching valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a switching valve, and more specifically,
The present invention relates to the valve rod sealing mechanism.

[Prior Art] A valve main body having a plurality of ports, a valve body having a valve seat in a flow path for communicating these ports, and a valve rod having a valve body for opening and closing the valve seat, and a valve on a guide surface of the valve body. A switching valve that guides the sliding of the rod is well known without being specifically exemplified.

The known switching valve described above is an O-ring fitted between the sliding portion of the valve rod and the guide surface in the groove of the valve rod, or a double-end fixed diaphragm having inner and outer edges fixed to the valve rod and the valve body, respectively. However, all of these known sealing mechanisms have the following problems.

That is, in the sliding seal using the O-ring, the lubricant applied to the O-ring, the wear powder of the O-ring, etc. are mixed in the fluid, which causes clogging of the silencer, malfunction of the valve and shortening of life, environmental pollution, etc. Becomes On the other hand, the seal with the fixed diaphragms at both ends has a problem that the stroke amount of the valve rod is small and the valve rod is easily fatigued and damaged by repeated operation.

[Problems to be Solved by the Invention] An object to be solved by the present invention is to provide a valve stem sealing mechanism in a switching valve which does not contain a lubricant or abrasion powder and has a long life.

[Means for Solving the Problems] In order to solve the above problems, a valve rod sealing mechanism in a switching valve according to the present invention includes a valve body having a plurality of ports and a valve seat in a flow path for communicating these ports with each other. And a valve rod having a valve body that opens and closes the valve seat and guides the sliding of the valve rod on the guide surface of the valve body, wherein the guide surface of the valve body and the sliding portion of the valve rod are , The openings each have an annular groove facing each other, and the axial width of the groove is made larger than the axial width of the annular seal packing whose inner and outer edges are in close contact with the bottom surface of these grooves, The seal packing is mounted so that it can be slid slightly with the inner and outer edges closely contacting the bottom surface of the groove, and the seal packing is pressed against the side wall of the groove by the fluid pressure acting on the seal packing to seal the groove. It has a feature.

In order to solve the same problem, the side wall of the groove is formed into an inclined surface whose diameter increases on the opening side in the valve rod sealing mechanism.

[Operation and Effect of Invention] When the valve rod slides to open and close the valve seat, the annular seal packing mounted in the groove provided in the sliding portion and the guide surface presses against the fluid pressure acting on the seal packing. The inner and outer edges are slightly slid in close contact with the bottom surface of the groove, and are pressed against the side wall of the groove on the side opposite to the fluid pressure side to seal the sliding portion of the valve rod.

Since the seal packing bends due to fluid pressure and is pressed against the side wall of the groove for sealing, unlike the O-ring that seals the sealing surface by sliding, it is not necessary to apply a lubricant, and there is almost no wear of the seal. It is possible to prevent malfunction of the valve, shortening of service life, environmental pollution, etc. due to wear powder of lubricant or packing.

In addition, the axial width of the groove is made larger than the axial width of the seal packing to allow the seal packing to move slightly with respect to the groove, so that the stroke amount of the valve rod can be made larger than that of a diaphragm with fixed ends. No damage due to fatigue even after repeated operation.

Further, since the side wall of the groove is an inclined surface that expands to the opening side, the sealing by the seal packing is more reliable.

[Embodiment] FIG. 1 and FIG. 2 show a first embodiment of the present invention, in which the valve body 1 in this switching valve has a first port 2 and a second port 3 and a flow path for communicating these ports. The adapter 6 provided with the through hole 4 and the valve seat 5 in the through hole and attached to the enlarged hole at one end of the through hole is provided with the guide hole 6a which is substantially concentric with the through hole 4 and has the same diameter.

On the other end of the through hole 4 and on the enlarged diameter portion formed outside the guide hole 6a, guide members 7 and 7 are mounted with the concave portions 8 and 8 facing each other, and the inner peripheral surfaces of the through hole 4 and the guide hole 6a are mounted. And the recess 8 having a larger diameter than this,
With the inner peripheral surface of 8, the guide surface 9a,
9a, 9b, 9b are formed, and between these guide surfaces 9a and 9b, annular grooves 10a, 10b whose diameter is increased on the opening side are formed.

The valve rod 12 loosely inserted into the through hole 4 has the guide surfaces at both ends.
First sliding parts 12a, 12a guided by 9a, 9a and guide surfaces 9b, 9b
A large-diameter second sliding portion 12b, 12b, and an annular groove 13a, 13b whose opening side between these sliding portions expands in diameter.
A valve element 14 for opening and closing the valve seat 5 is attached to the intermediate expanded portion, and annular seal packings 15a and 15b are mounted between the grooves 10a and 13a and 10b and 13b. These seal packings 15a, 15b have an inner diameter slightly smaller than the diameter of the bottom surface of the grooves 13a, 13b and an outer diameter substantially equal to the diameter of the bottom surfaces of the grooves 10a, 10b.
The axial width is smaller than the axial width of the bottom surface of each groove 10a, 10b, 13a, 13b.

Therefore, the seal packings 15a and 15b are formed in the grooves 9a, 13a and 9a.
When mounted between b and 13b, these inner and outer edges are lightly pressed against the bottom surface of the groove. Moreover, pilot chambers 16a and 16b are formed by both ends of the valve rod 12 and the recesses 8 and 8.

In the first embodiment, in the state shown in FIG. 1 in which the pilot fluid is supplied to the pilot chamber 16b, the valve body 14 closes the valve seat 5 and the communication between the ports 2 and 3 is cut off, and the seal packing is formed. 15a is groove 10a, 13a by the fluid pressure of the first port 2
, The seal packing 15b is pressed against the inner side walls of the grooves 10b, 13b by the pilot fluid pressure,
As a result, the sliding portion and the guide surface are hermetically sealed.

In this case, when the diameters of the guide surface 9a, the first sliding portion 12a and the valve seat 5 are equal to the diameters of the guide surface 9b and the second sliding portion 12b, the effective diameters of the seal packings 15a and 15b are the same as those of the valve seat 5. Although the diameter is smaller than the diameter and the balance of the valve rod 12 is lost, the diameters of the guide surface 9a, the first sliding portion 12a and the valve seat 5 are smaller than those of the guide surface 9b and the second sliding portion 12b in the above embodiment. Therefore, the effective diameter of the seal packing is increased, the valve rod 12 is well balanced, and a stable opening / closing operation can be performed.

When the pilot fluid in the pilot chamber 16b is discharged and the pilot fluid is supplied to the pilot chamber 16a, the valve rod 1
2 moves downward in the figure, and the valve element 14 opens the valve seat 5, so that the fluid in the first port 2 flows out from the second port 3, and the Pasir packing 15b is connected to the inlet port 2 and the pilot chamber 1.
It is pressed by the fluid pressure of 6a to seal between the sliding portion and the guide surface (see FIG. 2).

The grooves 9a, 9b, 13a, 13b, the axial width of the groove bottom is made larger than the width of the seal packing 15a, 15b in the same direction, the inner and outer edges of the seal packing 15a, 15b by these sliding the valve rod 12 Although it slides a little on the bottom of the groove, the seal packing 15a,
Since 15b is pressed against the side wall of the groove by fluid pressure and seals, unlike a known O-ring seal, it is not necessary to apply a lubricant, and the sliding portion is hardly worn. Therefore, it is possible to prevent the valve life from being shortened and the environmental pollution due to the lubricant and the abrasion powder. In addition, since the side walls of these grooves are formed as inclined surfaces whose diameter increases on the opening side, the seal packing 15a,
15b can reliably seal between the sliding portion and the guide surface.

Further, unlike the seal with the diaphragm fixed on both edges, not only the stroke amount of the valve rod 12 can be increased, but also the tension due to the sliding of the valve rod 12 does not act on the seal packing 15a, 15b, so the direction of pushing the valve rod back No force is applied and it will not be damaged even if it is repeatedly operated. Also, by changing the depth of each groove, seal packing 15
The effective cross-sectional area of a and 15b can be changed.

FIG. 3 shows a second embodiment of the present invention in which the first port 22 is connected to a vacuum source (not shown). In the second embodiment, the inner diameters of the guide surfaces 25a, 25a are the inner diameters of the guide surfaces 25b, 25b. Greater,
The outer diameter of the first sliding portions 26a, 26a of the valve rod 26 is equal to the second sliding portions 16b, 26b.
Is larger than the outer diameter of.

The other structure and operation of the second embodiment are the same as those of the first embodiment except that the fluid pressure of the first port 22 is always lower than the fluid pressures of other portions, so that the same parts as those in the figure are the same. Detailed description of the reference numerals is omitted.

[Brief description of drawings]

The drawings show an embodiment of the present invention, and FIGS. 1 and 2 are longitudinal sectional views of the first embodiment showing different operating states, and FIG.
It is a longitudinal cross-sectional view of an example. 1 …… Valve body, 2,3,22 …… Port, 5 …… Valve seat, 9a, 9b,
25a, 25b ... guide surface, 10a, 10b, 13a, 13b ... groove, 12 ... valve rod, 12a, 12b, 26a, 26b ... sliding part, 14 ... valve body, 15a, 15b
…… Seal packing.

Claims (2)

[Scope of utility model registration request] 1. A valve having a valve body having a plurality of ports, a valve body having a valve seat in a flow path for communicating these ports, and a valve rod having a valve body for opening and closing the valve seat, and a valve on a guide surface of the valve body. In a switching valve that guides the sliding of a rod, the guide surface of the valve body and the sliding portion of the valve rod have annular grooves whose openings face each other, and the axial width of the groove is defined by the inner and outer edges. Is larger than the axial width of the annular seal packing closely contacting the bottom of these grooves,
The seal packing is mounted in this groove so that the inner and outer edges of the groove are in close contact with the bottom surface of the groove, and the seal packing is pressed against the side wall of the groove by the fluid pressure acting on the seal packing. A seal mechanism for a valve rod in a switching valve, which is characterized in that 2. The seal mechanism for a valve rod in a switching valve according to claim 1, wherein the side wall of the groove is formed as an inclined surface whose diameter increases on the opening side.