JP3007486U - Butterfly valve - Google Patents

Abstract

(57) [Abstract] [Purpose] This is an attempt to develop a butterfly valve that can effectively suppress cavitation. By improving the shape of the valve body, the cavitation that occurs downstream of the orifice is significantly reduced, and the erosion phenomenon occurs. Remarkably reduce the adverse effects of cavitation such as noise and noise. [Structure] Only the valve body nozzle side portion on the downstream side with respect to the flow is eccentric to the shaft upstream side, in other words, the valve shaft center is provided at a position eccentric from the concentric position with respect to the valve body nozzle side portion to the upstream side. The butterfly valve is formed so that the valve body orifice side portion is concentric with the valve axis.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

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

[0002]

[Prior art]

 Conventionally, when a butterfly valve is opened, an orifice jet is formed when fluid passes through the valve body, causing cavitation to concentrate on the downstream side of the orifice, resulting in a loud noise and its energy. Has a big problem that erosion (so-called loose erosion) occurs in the wall of the pipe and finally a hole is opened.

In order to solve this drawback, various improvement measures have been taken, and many proposals have been made in utility models and patents. 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 Laid-Open No. 62-151674, Japanese Laid-Open Patent Application No. Hei-2 (JP-A) No. Hei. No. 118288 and many other publications disclose means for suppressing the generation of cavitation, but none of them have satisfactory effects, and in particular, vortex generation due to a jet core generated at a low opening degree is generated. The inhibitory effect is insufficient and further improvement is required.

[0004]

[Problems to be solved by the device]

 The present invention is intended to develop a butterfly valve that can effectively suppress cavitation, and to improve the shape of the valve body to significantly reduce cavitation generated downstream of the orifice side. .

[0005]

[Means for Solving the Problems]

 In order to reduce the orifice jet flow by improving the shape of the valve disc, it is considered that it is a basic condition that the main flow of the flow be directed toward the valve disc nozzle side part. As a result, various types of valve bodies were prototyped. Then, for each of the valve bodies, the Navier-Stokes equation of motion was discretized and analyzed by the finite difference method based on the control volume method, and the turbulent kinetic energy, pressure, and eddy viscosity at the steady state were calculated. It was calculated. Based on this calculated turbulent kinetic energy distribution, the cavitation generation region was found, and the region range and the shape with the smallest maximum value were selected.

As a result, only the valve element nozzle side portion on the downstream side with respect to the flow is eccentric to the shaft upstream side, and the valve element orifice side portion on the upstream side is concentric with the eccentric shaft. I found that if you create it like this, it will show a very good effect.

That is, according to the present invention, the valve shaft center is provided at a position eccentric to the upstream side from the position concentric with the valve body nozzle side portion that rotates toward the downstream side, and the valve shaft center is rotated toward the upstream side. The butterfly valve is characterized in that the valve body orifice side portion is formed so as to be concentric with the valve axis.

The present invention will be described in detail with reference to the drawings with reference to embodiments. FIG. 1 is a sectional view showing how a butterfly valve according to an embodiment of the present invention is incorporated in a pipe. As shown in this figure, in the butterfly valve of the present invention, the valve body nozzle side portion (2) has a shape inclined in the downstream direction with respect to the valve axis (1), while the valve body orifice side portion (3) is The shape is perpendicular to the valve axis (1) with respect to the pipe (p). (Hereafter, it is called a folding type.)

In other words, the concentricity (m) with respect to the valve body nozzle side portion (2) exists at the center of the vertical surface of the tip position (t) of the valve body nozzle side portion (2) as shown in the figure. The valve shaft center (1) is provided at a position eccentric to the upstream side, and the valve body nozzle side portion (2) is formed in a shape from the valve shaft center (1) to the t position, The body orifice side portion (3) is formed in a shape in which the valve axis (1) is concentric, that is, a shape which is vertically downward from the valve axis (1) and is directed to the s position in the figure.

In the figure, the arrow (a) indicates the flow direction of the fluid, and the valve body nozzle side portion (2) rotates toward the downstream side as shown by the broken line with the valve shaft center (1) as the rotation center. However, the valve body orifice side portion (3) rotates toward the upstream side with the valve shaft center (1) as the rotation center, as shown by the broken line in the figure.

2 and 3 are cross-sectional views of another embodiment of the butterfly valve according to the present invention, both of which are shown assembled in a pipe. In FIG. 2, the bent upstream side wall of FIG. 1 is formed into a smooth arc shape and the downstream side wall is formed into a flat surface. (Hereinafter, it is called a crescent moon type.) Further, in FIG. 3, the downstream side wall of the crescent moon type has the same arc shape as the upstream side. (Hereinafter, referred to as a lens type.)

Also in these cases of FIGS. 2 and 3, the valve shaft center (1) is located at a position eccentric to the upstream side from the concentricity (m) of the valve body nozzle side portion (2) as in FIG. The concentricity of the body orifice side portion (3) coincides with the valve shaft center (1). That is, in any of FIGS. 1 to 3, there are three points: the tip position t of the valve body nozzle side portion (2), the valve shaft center (1), and the tip position s of the valve body orifice side portion (3). The positional relationship is the same, and only the valve body surface shape is different.

FIG. 4 is a cross-sectional view of the most preferred embodiment of the butterfly valve of the present invention, which is shown to be installed in a pipe. In the case of FIG. 4 as well, as in the embodiment of FIGS. 1 to 3, the valve shaft center (1) is at a position eccentric to the upstream side from the concentricity (m) of the valve body nozzle side portion (2), The body nozzle side portion (2) has its upstream side wall surface formed from the valve axis center (1) toward the t position, and the valve body orifice side portion (3) has its concentricity aligned with the valve axis center (1). , S position.

The shape of FIG. 4 satisfies the conditions of the position of the valve shaft center (1) and the positions of t and s described above by the inventor of the present invention among various valve shapes, and is most effective for cavitation. It was selected as a shape that can be suppressed, and has a streamlined shape like the head of a long-necked bird. (Hereinafter, referred to as streamlined.)

In any of FIGS. 1 to 4, the eccentric distance from the concentric (m) of the valve body nozzle side portion (2) to the valve axis (1) is 15 to 25 of the inner diameter of the pipe (p). % Is preferable, and if this eccentric distance is too small, the effect decreases, while if it is too large, it becomes unsuitable as a butterfly valve.

[0016]

[Action]

 The present invention has a configuration as described above, and is a butterfly valve formed such that only the valve body nozzle side portion is eccentric to the shaft upstream side, and the valve body orifice side portion is concentric with the shaft center. is there. In the conventional eccentric butterfly valve, both the nozzle side and the orifice side are eccentric. With this shape, at a low opening of 30 or less, there is almost no flow to the orifice side and turbulent motion to the nozzle side. Energy was concentrated and cavitation could not be suppressed.

However, in the butterfly valve of the present invention, although the main flow of the flow is directed toward the nozzle side, turbulent kinetic energy is dispersed because part of the flow escapes toward the orifice side even at a low opening degree, and cavitation is effective. Can be suppressed. Particularly, in the streamline type of FIG. 4, the turbulent kinetic energy is very small even at a low opening, and the suppression of cavitation is effectively achieved.

1 to 4 (all of which have an eccentric distance from the concentric m to the valve shaft center (1) set to 20% of the pipe inner diameter), and as a comparative example, a conventional concentric type and an eccentric type. When the maximum velocity and the turbulent kinetic energy depending on the opening were measured and calculated under the same conditions under the other conditions, the results shown in FIGS. 5 and 6 were obtained.

FIG. 5 is a graph showing the relationship between the opening and the maximum velocity, and FIG. 6 is a graph showing the relationship between the opening and the turbulent kinetic energy. As a result, as shown in FIG. 5, in comparison with the conventional butterfly valve (concentric type, eccentric type) which is a comparative example, the maximum speeds of the embodiments of the butterfly valve of the present invention are considerably low at the opening of 60 or less. It shows that turbulence is unlikely to occur.

Further, from the results of FIG. 6, in all the embodiments of the butterfly valve of the present invention, the turbulent kinetic energy is considerably lower than that of the conventional butterfly valve, and the tendency is remarkable especially at the opening of 60 or less. Especially, in the streamlined embodiment, it is recognized that this turbulent kinetic energy is very low and effective suppression of cavitation can be obtained at a low opening.

[0021]

[Effect of device]

 The present invention is as described above, and the effects thereof are listed below as a list of items. (A) Since the valve element nozzle side part is a butterfly valve eccentric to the shaft upstream side, at a low opening, the nozzle side flow becomes the main flow and the orifice jet that causes cavitation does not grow, and the turbulent kinetic energy Can be significantly reduced and cavitation can be effectively suppressed.

(B) Since the shape of the valve body orifice side portion is concentric, it escapes partly to the orifice side as well, so the jet flow generation on the nozzle side is not concentrated, and the turbulent kinetic energy is dispersed and concentrated. It is possible to suppress the occurrence of cavitation, and as a result, it is possible to greatly reduce the erosion phenomenon in the downstream pipe and also to prevent noise. (C) Due to the one-sided eccentric shape, stable twin vortices that cause cavitation on the downstream side of the valve body are not generated at low openings, and cavitation is generated at all openings from low to high. Can be suppressed.

(D) Since only the shape of the valve body has been improved, the manufacturing by casting can be easily performed as an integrated body. (E) As in any of the embodiments, particularly in the streamlined type, the upstream side shape does not face the flow, so that the pressure loss is extremely smaller than that of the conventional valve body.

(F) Since the shape on the upstream side is close to the shape along the shunt of the flow, the pressure applied to the entire valve is extremely smaller than that of the conventional valve body, and the valve body can be opened and closed with low torque. (G) Since it is an eccentric type valve body, the pressure received on the orifice side is large, so a force acts in the closing direction of the valve body at a low opening degree, so a good seal is obtained. As described above, the present invention has various excellent effects and exhibits extremely high utility in the industrial field related to butterfly valves.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a butterfly valve of the present invention installed in a pipe.

FIG. 2 is a cross-sectional view showing another embodiment of the butterfly valve of the present invention installed in a pipe.

FIG. 3 is a cross-sectional view showing a still further embodiment of the butterfly valve of the present invention installed in a pipe.

FIG. 4 is a sectional view showing the most preferred embodiment of the butterfly valve of the present invention installed in a pipe.

FIG. 5 is a graph showing the relationship between the opening and the maximum speed in the examples and comparative examples (conventional concentric type and eccentric type) of FIGS.

FIG. 6 is a graph showing the relationship between the opening degree and the turbulent kinetic energy in the examples and comparative examples (conventional concentric type and eccentric type) of FIGS. 1 to 4.

[Explanation of symbols]

 1 valve shaft center 2 valve body nozzle side part 3 valve body orifice side part p tube concentric with respect to m 2 (center of vertical plane of t) tip position of t 2 (upstream side) tip of s 3 (vertically below valve shaft center)

Claims (1)

[Scope of utility model registration request] 1. A valve body which is provided with a valve shaft center at a position which is eccentric to an upstream side from a position which is concentric with a valve body nozzle side portion which is rotated toward the downstream side, and which is rotated toward the upstream side. The butterfly valve, wherein the orifice side portion is formed so as to be concentric with the valve axis.