JPH03219183A - Valve device - Google Patents

Abstract

PURPOSE:To prevent the occurrence of cavitation, noise, vibration or the like by forming donut-like space in a seat ring, and making the space continuous to the external surface of the seat ring via a flow passage. CONSTITUTION:A cylindrical seat ring 3 erected on a division 2 is provided within a valve body 1, and the center hole of the division 2 forms a fluid flow hole 6. Also, donut-like space 7 continuous to the hole 6 is formed beneath the seat ring 3, and a flow passage 8 is so formed as to have one end continuous to the space 7 and the other end open to the external surface of the seat ring 3. When a valve plug 15 is moved up, a fluid flowing into the donut-like space 7 via a throttle 9 is decompressed and becomes a vortex, due to the aforesaid space 7 forming an expansion chamber. The external portion of the vortex has higher pressure than the center portion, thereby preventing the occurrence of cavitation, erosion, noise and vibration.

Description

[Detailed Description of the Invention] 7. Fields of Industrial Application] The present invention relates to a valve device having a contour type valve plug, and is particularly applicable to a valve device suitable for controlling high-pressure fluid. be.

2. Conventional technology In general, in valve devices that control high-pressure fluid, when resistance is applied to the flow of fluid, when the fluid pressure is significantly reduced, the turbulence of the flow that occurs at the throttle part of the valve causes it to become abnormally high. It may generate noise or cavitation/erosion. Therefore, as a method for solving this problem, various valve devices have been proposed in which the fluid pressure is gradually lowered. As for the method of depressurization, ■Multi-stage decompression method using many balls (
(Example Special Publication No. 52-10522), ■ Labyrinth method in which a labyrinth-like groove is formed on the seat ring (Example Special Publication No. 55-25314)
There are three types: 0) and a multi-hole gauge system in which a large number of small holes are formed in a cylindrical seat ring (Example: Japanese Patent Publication No. 1983-44910).

[Problem to be solved by the invention] However, the multi-stage depressurization method according to (1) above cannot necessarily prevent the occurrence of cavitation, and in order to improve the cavitation suppression effect, it may be necessary to increase the number of stages. However, there was a problem in that the valve opening body became larger.

The labyrinth method (2) has the disadvantage that the seat ring is troublesome to manufacture and the manufacturing cost is high, and the flow path is narrow due to the labyrinth shape and is easily clogged due to scale accumulation. In addition, in the porous cage method (2), since it is necessary to reduce the diameter of the small holes in order to improve the cavitation suppression effect, it has the disadvantage of being easily clogged, similar to the labyrinth method described above.

Therefore, the present invention has been made in view of the drawbacks of the various conventional methods as described above, and its purpose is to reduce fluid pressure with a relatively simple configuration without increasing the size of the device. cavitation
To provide a valve device capable of suppressing the occurrence of erosion, noise, etc., and free from clogging.

Means for Solving the Problem] In order to achieve the above object, the present invention includes a cylindrical seat ring having a fluid circulation hole, and a flow rate of a fluid that moves up and down inside the seat ring and flows through the fluid circulation hole. a donut-shaped space surrounding the vicinity of the characteristic portion of the valve plug on the upstream side of the fluid flow hole in the seat ring, and one end opening on the outer circumferential surface of the seat link, A channel is formed to communicate the donut-shaped space to the downstream side.

[Function] In the present invention, the donut-shaped space portion of the seat ring is provided downstream of the constriction portion to form an expansion chamber and reduce the pressure of the driftwood. The fluid flowing into the donut-shaped space turns into a ring-shaped vortex, and since the outer periphery has a higher pressure than the center, the differential pressure acting on the characteristic part of the valve plug is smaller than when there is no vortex. The fluid whose pressure is reduced by the donut-shaped space flows out to the downstream side through a flow path formed in the seat ring. The vapor bubbles generated in the fluid as the pressure drops are caught in the center of the vortex on the low-pressure side, and do not come into contact with the wall of the donut-shaped space and collapse.

[Example] The present invention will be described in detail below based on an example shown in the drawings.

FIG. 1 is a sectional view showing an embodiment of a valve device according to the present invention;
FIG. 2 is an enlarged sectional view of the seat ring, and FIG. 3 is a sectional view taken along the line Ill--[FIG. 2]. In these figures, 1 is a bowl-shaped valve body whose interior center is partitioned by a partition wall 2;
is a cylindrical seat ring whose lower end is fitted into an opening 4 formed in the center of the partition wall 2 via a gasket 5, and which is erected and fixed on the partition wall 2; the center hole of this seat ring 3 is A fluid communication hole 6 is formed. Also, within the thickness of the seat ring 3, the lower end opening side, that is, the -next side (upstream side)
A donut-shaped space 7 is formed which has a circular cross-sectional shape and communicates with the fluid circulation hole 6, and one end communicates with the donut-shaped space 7 and the other end opens on the outer peripheral surface of the seat link 3. A flow path 8 is formed, and this flow path 8 communicates the donut-shaped space 7 with the secondary side (downstream side) of the valve body 1. For example, four channels 8 are formed equally spaced in the circumferential direction within the thickness of the seat ring 3, and their total cross-sectional area is within about twice the area of the constricted section (contraction section) 9 of the seat ring 3. It is said that

Reference numeral 10 indicates a lid body that is fitted into an opening 11 formed in the center of the upper surface of the valve body 1 through a gas get 12, and is fixed with a plurality of bolts 13 and nuts 14; This valve plug 15 is a contour type valve plug that is slidably fitted into the flow hole 6.
A substantially gun head-shaped characteristic part 16 is integrally provided at the lower end of the seat ring 3, and a seat part 18 is formed which seats on a seat part 17 formed inside and below the seat ring 3 when the seat ring 3 is fully closed.

19 is a valve shaft that is inserted into the center hole 20 of the lid 10 through a packing (not shown) and raises and lowers the valve plug 15, 21 is a packing flange, 22 is a packing follower, and 2.1 is a packing flange. 21 to the lid 10.

The donut-shaped space 7 is formed near the seat portion 17 on the downstream side of the throttle portion 9 so as to surround the vicinity of the characteristic portion 16 of the valve plug 15.

In the valve device having such a configuration, when the valve plug 15 is gradually raised from the fully open state, the seat portion 18 is separated from the seat portion]7 of the seat ring 3, so that the primary side and the secondary side of the valve body 1 are separated from each other. The next side is communicated via the fluid communication hole 6 of the seat ring 3, the donut-shaped space 7, and the flow path 8. Therefore, the fluid 25 that has flowed into the valve body 1 from the primary opening 1a of the valve body 1 flows into the donut-shaped space 7 through the fluid flow path 6, and flows through the flow path 8 into the valve body 1. It is flowed downstream.

At the second time, the fluid 20 flowing into the donut-shaped space 7 through the constriction part 9 is depressurized because the donut-shaped space 7 forms an expansion chamber, and moves along the wall surface of the toroidal space 7 to form a vortex 27. Become. The outer circumference of this vortex 27 has a higher pressure than the center, and therefore the differential pressure acting on the characteristic portion 16 of the valve plug 15 is smaller than in the case where the vortex 27 does not occur, which prevents cavitation and erosion of the characteristic portion 16. Suppress and prevent outbreaks. In addition, the vortex flow 27 generates little noise and vibration, and moreover, especially when the valve opening degree is low, steam bubbles that are generated significantly due to high differential pressure are caught in the vortex center and collapse upon contact with the wall surface of the donut-shaped space 7. Therefore, the effect of suppressing -layer cavitation is large.

Furthermore, since it is only necessary to form the donut-shaped space 7 and the flow path 8 in the seat ring 3, the structure is simple and there is no risk of increasing the size of the valve device.

Note that if the total cross-sectional area of the flow path 8 is made within about twice the area of the constriction portion 9, the generation of the ring-shaped vortex flow 27 will not be hindered.

[Effects of the Invention] As explained above, the valve device according to the present invention forms a donut-shaped space surrounding the vicinity of the characteristic portion of the valve plug in the seat ring, and also connects the donut-shaped space with the outer periphery of the seat ring. When the fluid flows into the donut-shaped space through the fluid flow hole of the seat ring, it expands and is depressurized, forming a vortex. Therefore, the differential pressure acting on the plug characteristic part is smaller than in the case where no vortex is generated, and therefore cavitation, noise, vibration, etc. can be effectively prevented from occurring, and the durability and noise reduction of the valve device can be achieved. I can do it. Further, the structure is simple, the device does not become large, and if the present invention is applied to a multi-stage pressure reduction type valve, it is possible to reduce the number of stages and shorten the trim length.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of a valve device according to the present invention;
FIG. 2 is an enlarged sectional view of the seal 1 to the ring, and FIG. 3 is a sectional view taken along the line [1-III in FIG. 2. DESCRIPTION OF SYMBOLS 1-- Valve body, 2... Partition wall, 3- Seat ring, 6... Fluid circulation hole, l-1- Nut shaped space, 8... Channel, 15 - Valve plug,
16. Characteristics section, 19 Valve stem.

Claims (1)

[Claims] a cylindrical seat ring having a fluid communication hole; a valve plug that moves up and down within the seat ring to control the flow rate of fluid flowing through the fluid communication hole; A donut-shaped space surrounding the vicinity of the characteristic portion of the valve plug is formed, and a flow path is formed at one end of the outer peripheral surface of the seat ring to communicate the donut-shaped space to the downstream side. Valve device.