JPH01279187A - Valve device - Google Patents

Abstract

PURPOSE:To decrease a differential pressure between a valve unit in its valve seat part and an orifice in its seat surface part thus preventing generation of cavitation by throttling a controlled material being dispersed by two or more circumferential fitting parts in a fine opening region. CONSTITUTION:A seat part 9 is provided between a valve unit 15 of a plug collective unit 10 in its uppermost upstream side and an orifice 6 in the uppermost upstream side of the orifices of a seat ring 5, while a circumferential fitting part 15 is provided neighboring to said seat part 9. Further circumferential fitting parts 16, 17, serving as the throttle part in a fine opening condition, are provided between valve units 12, 13 in the downstream side and orifices 7, 8 in the downstream side.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a valve device equipped with a seat ring having a plurality of orifices in the axial direction.

[Conventional technology]

In general, in valve devices such as control valves, when controlling liquid, which is the fluid to be controlled, with a high differential pressure, cavitation occurs due to fluctuations in pressure conditions after the valve, and cavitation occurs in the seating area of the valve body and the seat of the valve seat. Since the valve function is easily lost due to localized erosion of the surface, various countermeasures have been taken.

Conventionally, this type of valve device was disclosed in Japanese Patent Application Laid-Open No. 61-3177.
The one disclosed in Publication No. 2 (Figure 4) is adopted.

[Problem to be solved by the invention]

By the way, in conventional valve devices, the flow rate is controlled by the flow rate characteristic part of each valve body immediately after the valve opens, so although it is effective as a pressure reducing valve in the medium and high opening range, it is not effective in the low opening range. Cavitation was likely to occur between the seating area and the seat surface. That is, in the low opening degree region, the gap between the seating portion of the valve body and the seat surface of the orifice is the narrowest. This was noticeable when a foreign object was caught between the seating portion and the seat surface when the valve was closed. As a result, under small opening conditions, the seating part of the valve body and the seat surface of the valve seat may locally erode or generate noise, making it impossible to maintain stable valve performance over a long period of time. There was a problem.

The present invention has been made in view of these circumstances, and can prevent erosion of the seating portion of the valve body and the seat surface of the valve seat, and can also suppress the generation of noise in the small opening range. , thereby providing a valve device that can maintain stable valve performance over a long period of time.

[Means for Solving the Problem] The valve device according to the present invention includes a seat portion between the most upstream valve body of the valve bodies of the plug assembly and the most upstream orifice of the orifices of the seat ring. At the same time, a circumferential fitting part is provided adjacent to this seat part, and the circumferential fitting part is provided between the downstream valve body and the downstream orifice, which becomes a constriction part in a small opening state. be.

In a valve device according to another invention, the axial dimension of the circumferential fitting portion is set to a dimension that gradually increases from the upstream side to the downstream side.

[For production]

In the present invention, the fluid to be controlled can be dispersed and throttled by the circumferential fitting part (throttling part) in the minute opening range.

〔Example〕

EMBODIMENT OF THE INVENTION Hereinafter, the structure etc. of this invention will be explained in detail by the Example shown in the figure.

1 and 2 are cross-sectional views showing a low opening state and a high opening state of a valve device according to the present invention, and FIG. 3 is a cross-sectional view showing the entire valve device according to the present invention. In the same figure,
1 is a cylindrical valve box, and the peripheral wall thereof is provided with a communication hole 2 that communicates with downstream piping (not shown).

Reference numeral 3 denotes a pipe body communicating with upstream piping (not shown), which is fixed to the valve box 1, and has connecting flanges 4 at both ends.
is provided. Reference numeral 5 designates a seat ring serving as a valve seat that communicates with both the upper and lower piping (not shown), a portion of which faces into the valve box 1 and is held on the flange end surface 4a of the pipe body 3. Three orifices 6 to 8 are provided in parallel at predetermined intervals in the axial direction. Of these orifices 6 to 8, the most upstream orifice 6 is provided with a seat surface 9 on which a seating portion of a valve body, which will be described later, can be seated. Reference numeral 10 denotes a plug assembly having three valve bodies 11 to 13 for controlling opening and closing of the fluid passage holes 68 to 8a of each of the orifices 6 to 8, and is provided movably on the axis of the seat ring 5. The valve bodies 11 to 13 of this plug assembly 10 are provided with fluid characteristic parts 11a to 13a, respectively, and the most upstream valve body 11 has a seating part 14 that seats on the seat surface 9 when the valve is closed. is provided.

A circumferential fitting portion 15 is provided between the fluid characteristic portion 11a of the valve body 11 and the fluid passage hole 6a of the orifice 6 by forming each circumferential wall with a circumferential surface having approximately the same diameter. It is being On the other hand, each peripheral wall is formed with a circumferential surface having approximately the same diameter between the fluid characteristic portions 12a, 13a of the downstream valve body 12.13 and the fluid passage holes 7a, 8a of the downstream orifice 7.8. As a result, circumferential fitting portions 16 and 17 are provided, which together with the circumferential fitting portion 15 act as a converging portion in the slightly opened state. Further, between the valve body 11 on the most upstream side and the orifice 6 on the most upstream side, the seating portion 14
A seat portion 18 is provided by the seat surface 9. 19 is a cylindrical top guide for guiding the plug assembly 10, and is fixed inside the valve box 1;
The peripheral wall is provided with a communication hole 19a that opens to the inside and outside of the guide. Reference numeral 20 denotes an annular bottom guide having a flow hole 20a through which the controlled fluid passes, and is interposed between the seat ring 5 and the tube body 3, and is connected to the top guide 19.
The plug assembly 10 is configured to be guided along with the plug assembly 10. In addition, the controlled fluid has a differential pressure P+ Pz=P(
>O) causes the flow to flow in the direction shown by the arrow in FIG.

In the valve device configured in this way, the controlled fluid passes through the gaps between the three circumferential fitting parts 15 to 17 in the minute opening range, so that the controlled fluid passes through the gaps between the three circumferential fitting parts 15 to 17. The fluid to be controlled can be dispersed and throttled by the circumferential fitting parts 15 to 17 (throttling parts).

Therefore, in the present invention, since the differential pressure at the seat portion 18 can be reduced in the minute opening range, the valve body 1
1 and the seat surface 9 of the orifice 6, erosion of the seating section 14 and the seat surface 9 can be prevented, and noise generation in the seat section 18 can be suppressed. can do.

In addition, in the middle and high opening state, the controlled fluid is dispersed and throttled by the orifices 6 to 8 as in the conventional device, so the pressure difference at the seat portion 18 does not become large. In this case, if the pressure reduction ratio in the orifices 6 to 8 is divided equally, cavitation will occur between the most downstream orifice 8 and the valve body 13. It is desirable to reduce the differential pressure at the downstream constriction section by changing the

Although this embodiment shows an example in which a step is formed on the outer circumferential surface of the valve body 12 and 13 on the downstream side, the present invention is not limited to this, and the circumferential fitting portions 16 and 17 are There is no problem even if it is a valve body (not shown) without a step as long as it has the following characteristics.

In addition, in the present invention, the aperture lengths (axial dimensions) 2t to 12 (shown in FIG. 1) of the circumferential fitting parts 15 to 17 are dimensions that gradually increase from the upstream side to the downstream side (1, < 1
．． <1. ), the differential pressure in the seat portion 18 can be reliably reduced.

Furthermore, the number of orifices 6 to 8 in the present invention is not limited to the above-mentioned embodiments, and is, for example, 2, 4, or 5.
. . , and the number can be changed as appropriate.

〔Effect of the invention〕

As explained above, according to the present invention, a seat portion is provided between the most upstream valve body of the valve bodies of the plug assembly and the most upstream orifice of the orifices of the seat ring, and the seat portion A circumferential fitting part is provided adjacent to the valve body, and a circumferential fitting part is provided between the downstream valve body and the downstream orifice, which becomes a constriction part in the minute opening state. The fluid to be controlled can be dispersed and throttled by the circumferential fitting portion, and the differential pressure between the seating portion of the valve body and the seat surface of the orifice can be reduced. Therefore, it is possible to prevent the occurrence of cavitation in the seat part in the minute opening range, so it is possible to prevent erosion of the seating part and the seat surface, and to suppress the generation of noise in this seat part, making it possible to Stable valve performance can be maintained over a period of time. In addition, in another invention, since the axial dimension (aperture length) of the circumferential fitting part is set to a dimension that gradually increases from the upstream side to the downstream side, the differential pressure at the seat part can be reliably reduced. It has the advantage that it can be made small.

[Brief explanation of the drawing]

1 and 2 are sectional views showing a low opening state and a high opening state of a valve device surface according to the present invention, and FIG. 3 is a sectional view showing the entire valve device according to the present invention. 5... Seat ring, 6-8... Orifice,
6a to 8a...Fluid passage hole, 9...Seat surface,
10... Plug assembly, 11-13... Valve body,
14... Seating portion, 15-17... Circumferential fitting portion.

Claims (2)

[Claims] (1) A seat ring having a plurality of orifices arranged in parallel at a predetermined interval in the axial direction, and a plug having a plurality of valve bodies that are movable forward and backward on the axis of the seat ring and control the opening and closing of the fluid passage hole of the orifice. a seat part is provided between the most upstream valve body of the valve bodies of the plug assembly and the most upstream orifice of the orifices of the seat ring, and a seat part is provided adjacent to the seat part. A circumferential fitting portion is provided between the downstream valve body and the downstream orifice, and the circumferential fitting portion serves as a constriction portion together with the circumferential fitting portion in a slight opening state. Features a valve device. (2) The valve device according to claim 1, wherein the axial dimension of the circumferential fitting portion is set to a dimension that gradually increases from the upstream side to the downstream side.