JPH058139U - Butterfly valve - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a butterfly valve that is excellent in controllability and noise prevention while preventing erosion by suppressing cavitation that tends to occur in a butterfly valve as much as possible. [Structure] A plurality of rectifying disks are symmetrically attached to the front and rear of the valve body, a large number of rectifying holes are provided in the rectifying disk, and the size of the rectifying disk can be opened and closed while being closest to the pipe. That is, the outer peripheral edge of the flow regulating disk is set on the outer circumference of the rotation orbit circle of the valve body so that the clearance between the valve body and the pipe is minimized as in the case of the valve body.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a butterfly valve that suppresses cavitation on the downstream side of a valve body.

[0002]

[Prior Art]

 Conventionally, in a butterfly valve, an orifice jet is formed when fluid passes through the valve body when the valve is opened, and cavitation is generated by concentrating on this orifice side wake, and the energy acts on the inner wall of the pipe. In the end, there is a big problem that erosion (so-called erosion) occurs on the wall of the pipe and a hole is opened.

In order to solve this drawback, various improvement measures have been taken, and many proposals for utility models and patents have been made. For example, Japanese Utility Model Laid-Open No. 56-138266, Japanese Utility Model Laid-Open No. 61-193274, Japanese Utility Model Laid-Open No. 62-6568, Japanese Utility Model Laid-Open No. 63-17372, Japanese Patent Application Laid-Open No. 62-151674, Japanese Patent Laid-Open No. Hei-2. No. 118288 and many other publications disclose means for suppressing the generation of cavitation, but none of them have the satisfactory effect, and in particular, the generation of vortices due to a jet core generated at a low opening degree. The inhibitory effect is insufficient and further improvement is required.

[0004]

[Problems to be solved by the device]

 The present invention was made for the purpose of developing a butterfly valve that can suppress the occurrence of cavitation as much as possible. The present invention aims to provide a new butterfly valve that can prevent the occurrence of low pressure parts in the engine and can suppress the occurrence of cavitation with an excellent effect that has never been seen before.

[0005]

[Means for Solving the Problems] As a result of various studies to achieve the above object, a plurality of rectifying disks having a large number of rectifying holes on the upstream side and the downstream side of a valve body are attached so as to be symmetrical to each other. They have found that by sizing the rectifying disk so that the gap between the valve body and the rectifying disk and the pipe can be rotated to the minimum, a very good effect can be obtained.

That is, according to the present invention, a support shaft protruding from the center of the valve body to the upstream side and the downstream side is provided, and a plurality of rectifying disks are arranged on the support shaft so that the upstream side and the downstream side are symmetrical. The rectifying disk has a large number of rectifying holes, and the rectifying disk has a size such that the outer peripheral edge thereof is located on the outer circumference of the rotation orbit circle of the valve body. The gist is a butterfly valve, which is characterized in that the valve body and the rectifying disk are rotatably closest to the pipe.

The present invention will be described with reference to the drawings by citing one embodiment. FIG. 1 is a plan sectional view showing a state where a butterfly valve of the present invention is installed in a pipe, showing a low opening state. FIG. 2 is a front view of a portion of the butterfly valve of the present invention installed in a pipe. FIG. 3 is a side view of a portion of the butterfly valve of the present invention installed in a pipe.

As shown in these figures, the present invention is provided with a support shaft (2) protruding from the center of the valve body (1) toward the downstream side and the upstream side, and the support shaft (2) is provided. A plurality of rectifying discs (3) are attached to the.

In the case of this embodiment, two rectifying disks (3) are provided on each of the upstream side and the downstream side, but the number of rectifying disks (3) is not limited to this. Even if about 5 pieces are provided, it does not matter. However, this rectifying disk (3) needs to be mounted so that the downstream side and the upstream side are symmetrical in order to reduce the opening / closing torque.

A large number of rectifying holes (4) are formed in the rectifying disk (3), and the diameter, number, distribution state, etc. of the rectifying holes (4) are not specified, but In the embodiment, the design is made in the state shown in FIGS.

The size of the rectifying disk (3) is set so that the butterfly valve can be closest to the inner wall of the pipe (P) when the butterfly valve is opened and closed about the rotary shaft (5). -ing That is, in FIG. 1, both ends of the valve body (1) are positioned so that the outer peripheral edges of the flow regulating discs (3) are located on the outer circumference of the rotation orbit circle (s) that is drawn during opening and closing rotations. The size is fixed.

By doing so, when the rectifying disk (3) and the pipe (P) are closest to each other, the clearance between them is minimized so that the valve body (1) can rotate. Although the drawing shows only the inside of the pipe (P) of the butterfly valve of the present invention, the rotating shaft (5) can be rotated by a handle provided outside the pipe (P). Needless to say.

[0013]

[Action]

 The present invention is configured as described above, and its operation will be described below. At a low opening as shown in Fig. 1, if there is no rectifying disk (3), the fluid passing between the valve body (1) and the inner wall of the pipe (P) is most likely to generate a jet core, and the orifice jet The formation of cavitation is severe and the occurrence of cavitation is maximized. However, if a rectifying disk (3) is provided as in the present invention, the occurrence of cavitation can be very effectively prevented.

That is, since the gap between the inner wall of the pipe (P) and the flow regulating disk (3) is small when the valve is opened at a low opening, a large amount of fluid is present on the way to the downstream side of the flow regulating disk (3). The rectifying hole (4) flows as a bypass, and this bypass flow is ejected to the downstream side. As a result, the formation of an orifice jet when the fluid passes through the valve body (1) is hindered and a large differential pressure across the valve body is prevented.

Therefore, cavitation is suppressed from being concentrated in the wake behind the orifice, and the generated cavitation bubbles are finely crushed by the large number of flow rectifying holes (4), so that the cavitation is concentrated and destroyed in the wake pipe. This prevents erosion due to noise and suppresses the generation of noise and vibration.

Further, since a plurality of rectifying disks (3) are attached, a large resistance can be obtained at an intermediate opening degree, and the decompression effect is large, which is suitable for a decompression type butterfly valve. Furthermore, since the rectifying discs (3) are symmetrically installed in the front and rear of the valve body, the opening and closing torque is small, and the valve opening and the flow rate are close to the proportional value, making it a very easy-to-control butterfly valve. Of.

Regarding the above-mentioned effects, various data were obtained by actually making a prototype butterfly valve of the present invention as shown in the drawings, with a pipe (P) diameter of 150 mm, a straightening hole (4) diameter of 10 mm. The result of measurement will be described below.

Initial Cavitation Coefficient This coefficient is a cavitation coefficient when cavitation occurs for the first time, and the lower the value, the smaller the cavitation occurrence, indicating that the butterfly valve is an excellent one. This coefficient is calculated from the valve upstream pressure, valve downstream pressure, flow velocity, atmospheric pressure, saturated vapor pressure, and gravitational acceleration, and the calculation method (mathematical formula) is omitted. The following table shows the results of measurement of this initial cavitation in the prototype example and the comparative example in which the support shaft and the rectifying disk are removed from this example.

Cavitation coefficient according to valve opening degree Valve opening degree 20% 40% 60% 80% 100% Example 1.90 2.19 4.37 5.11 6.10 Comparative example 1.95 4.27 7.55 10.9 11.8

As shown in this table, the butterfly valve of the present invention has a smaller cavitation coefficient at any opening than the comparative example without the rectifying disk, and it is recognized that the occurrence of cavitation can be suppressed very effectively. is there.

Loss coefficient This coefficient is a coefficient indicating the degree of pressure reduction before and after the valve body. The larger this value is, the higher the pressure reducing effect is, and the more suitable it is as a pressure reducing butterfly valve. This loss coefficient is calculated from the differential pressure between the valve upstream and the valve downstream, the flow velocity, and the gravitational acceleration, and the calculation method (mathematical formula) will be omitted. The following table shows the results of measurement of this loss coefficient for the same examples and comparative examples as described above.

Loss coefficient due to valve opening degree Valve opening degree 20% 40% 60% 80% 100% Example 326.4 42.9 11.5 3.72 3.33 Comparative example 362.4 28.7 4.75 1.01 0.60

As shown in this table, the resistance due to the presence or absence of the rectifying disk does not change much at a low opening, and the loss coefficient is relatively larger in the comparative example, but the resistance of the embodiment of the present invention becomes larger as the opening becomes larger. The loss factor is also larger than that of the comparative example, and it can be judged that it is suitable as a pressure reducing butterfly valve.

Capacity Coefficient Ratio (Cv Value Ratio) This capacity coefficient ratio (%) shows the relationship between the valve opening and the flow rate at that time, and if the numerical value (%) is close to the valve opening (%), It shows that the opening and the flow rate are close to proportional, and that the flow rate is easy to change in comparison with the valve opening and has excellent controllability. This capacity coefficient ratio (capacity coefficient / maximum capacity coefficient) is calculated from the flow rate, the differential pressure between the valve upstream and the valve downstream, and the specific gravity of the fluid, and the calculation method (mathematical formula) is omitted. To do. The following table shows the results of measuring the capacity coefficient ratio in the same examples and comparative examples as described above.

Valve opening (%) and capacity coefficient ratio at that time (%) Valve opening 20 40 60 80 100 Example 10.2 27.2 48.9 88.2 100 Comparative example 4.0 13.2 31 .7 74.1 100

From this table, the values of the valve opening (%) and the capacity coefficient ratio (%) are closer to each other in the embodiment of the present invention than in the comparative example, and the flow rate according to the opening is easily obtained and the valve control is excellent. Is recognized.

In addition, when the cavitation coefficient at an opening of 30% according to the Reynolds number was measured, the cavitation coefficient of the present invention example is smaller than that of the comparative example. For example, when the Reynolds number is about 14,000, the cavitation coefficient of the embodiment is small. The value of 2.67 was obtained in the comparative example in contrast to 2.14. In addition, as a result of noise measurement of the example and the comparative example, it was confirmed that the noise level was small, which was as low as 98 decibel in the example, while the decibel was 103 decibel in the comparative example at an opening of 30%. It was.

[0028]

[Effect of the device]

 The effect of the present invention is as described in detail in the above-mentioned action column, but it is summarized as follows. (A) A butterfly valve that can very effectively suppress the occurrence of cavitation. (B) Therefore, erosion can be prevented and the life of piping equipment can be greatly extended.

(C) It is suitable as a pressure-reducing butterfly valve because the pressure-reducing effect is large at an intermediate opening. (D) Since the valve body is a front-rear symmetrical type, the opening / closing torque is small and the handleability is excellent. (E) The butterfly valve has excellent controllability because the valve opening and the flow rate are easily proportional. (F) The butterfly valve has a large noise prevention effect. As described above, the present invention has various excellent effects and is a very useful butterfly valve.

[Brief description of drawings]

FIG. 1 is a plan sectional view of a butterfly valve of the present invention installed in a pipe.

FIG. 2 is a front view of an internal portion of a butterfly valve of the present invention.

FIG. 3 is a side view of an internal portion of a butterfly valve of the present invention.

[Explanation of sign]

 (1) Valve body (2) Support shaft (3) Rectifying disk (4) Rectifying hole (5) Rotating shaft (P) Piping (s) Rotating orbit circle

Claims (1)

[Claims for utility model registration] [Claim 1] Support shafts projecting from the center of the valve body to the upstream side and the downstream side are provided, and a plurality of rectifying disks are symmetrical to the support shafts on the upstream side and the downstream side. The rectifying disk has a large number of rectifying holes, and the size of the rectifying disk is such that the outer peripheral edge thereof is located on the outer circumference of the rotation orbit circle of the valve body. The butterfly valve is characterized in that the valve body and the rectifying disk are rotatably closest to the pipe.