JP2005098351A - Triple eccentric butterfly valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a triple eccentric butterfly valve, easily controlling the quantity of fluid in a low opening area, letting a large quantity of fluid flow when the valve is fully opened, completely sealing at a valve seat surface, and smoothly opening the valve from the totally closed state. <P>SOLUTION: In this triple eccentric butterfly valve, a valve surface to which a valve shaft is not attached is formed flat, the outer peripheral surface on an orifice side is formed as a circumference surface vertically extending from the above surface, and the outer peripheral surface on a nozzle side is formed as a truncated cone surface gradually spreading from the surface to the back, whereby when the valve is totally closed, the nozzle side on the valve body surface is projected in the opposite direction to the valve shaft attaching direction more than the orifice side and inclined in the valve body. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a triple eccentric butterfly valve.

  The triple eccentric butterfly valve is a special type of butterfly valve. That is, the butterfly valve is composed of a valve body having a circular fluid passage and a valve body that is rotatable around the valve shaft in the fluid passage of the valve body. Thus, since the valve body is rotated about the valve shaft, the valve shaft is rarely attached to the valve body.

However, in the triple eccentric butterfly valve, the valve stem is attached to the valve body while being offset. That is, the valve shaft is deviated from the plane connecting the outer circumferences of the valve bodies, and one of the planes is attached to protrude from the hook and is eccentric first. Further, in the triple eccentric butterfly valve, the valve shaft is offset from the center of the valve body to one side, and is eccentric eccentrically. Further, in the valve body, the valve seat surface that is in close contact with the outer periphery of the valve body is on one inclined conical surface and is eccentrically tertiary. Such a butterfly valve in which eccentricity from primary to tertiary is piled up is a triple eccentric butterfly valve, and such a butterfly valve is described in Japanese Patent Laid-Open Nos. 62-83563 and 11-148563. Known.
JP-A-62-83563 JP-A-11-148563

  In the triple eccentric butterfly valve, in order to prevent fluid from leaking from between the valve body and the valve body when the valve is fully closed, the valve body is provided with a seat ring in the same manner as a normal butterfly valve. This seat ring ensures that the valve is fully closed by bringing its inner peripheral surface into close contact with the outer periphery of the valve body. The inner peripheral surface of the seat ring constitutes a valve seat surface.

  Triple eccentric butterfly valves are particularly used to control high temperature and high pressure fluids. The triple eccentric butterfly valve has the advantage that it is easy to start opening the valve from the fully closed state because the entire outer periphery of the valve element can be separated from the valve seat surface simultaneously with a slight force. However, the advantage that the valve bodies can be separated simultaneously over the entire circumference causes a problem that it is difficult to control the flow of fluid when the valve has a low opening.

  In order to solve this problem, it can be easily considered that the thickness of the outer periphery of the valve body may be increased over the entire circumference. However, in such a case, when opening and closing the valve body, the inner peripheral surface of the seat ring is easily damaged, and when the valve body is fully opened, the thickness of the valve body blocks the flow of fluid. This causes a problem that the fluid cannot flow.

Japanese Patent Application Laid-Open No. 2003-161374 shows one proposal for solving the above-described problem. That is, in this publication, the above-mentioned problem is solved by making the shape of the triple eccentric butterfly valve cut by a plane passing through the center of the valve shaft and perpendicular to the valve shaft as shown in FIG.
JP 2003-161374 A

  In FIG. 1, a valve body 3 is attached to a valve body 1 so as to be rotatable about a valve shaft 2 to constitute a butterfly valve. In this butterfly valve, the valve shaft 2 protrudes from the plane connecting the outer periphery of the valve body 3 by a length X, and is eccentric first. Further, the valve shaft 2 is offset from the center of the valve body 3 to the one side by the length Y, and is eccentric eccentrically. Furthermore, the inner peripheral surface of the seat ring 4 attached to the valve main body 1 is on the inclined conical surface R indicated by a dotted line with S as the apex, and forms a valve seat surface and is eccentric eccentrically. FIG. 1 attempts to solve the above problem in such a triple eccentric butterfly valve.

  The solution to the above problem shown in FIG. 1 is as follows. That is, in FIG. 1, when the upper side of the valve body 3 is called the orifice side and the lower side of the valve body 3 is called the nozzle side, the orifice side outer peripheral surface 32 of the valve body 3 is perpendicular to the surface 31 of the valve body 3. The outer peripheral surface 33 on the nozzle side is a truncated cone surface extending obliquely from the front surface 31, and the truncated conical surface is inclined so as to spread from the front surface 31 toward the rear surface 34. At the same time, the thickness of the valve body 3 is gradually increased as it approaches the outer peripheral surface. Here, the orifice side is the half of the valve body 3 to which the valve shaft 2 is offset and the nozzle side is the other half of the valve body 3, in other words, the valve It is a half part of the valve body 3 on the side where the shaft is not offset and attached. Reference numeral 35 denotes a valve shaft support portion in the valve body 3.

  In JP-A-2003-161374, as shown in FIG. 1, the thickness of the valve body 3 is increased as it approaches the outer peripheral surface. Therefore, the flow rate when the valve is fully opened is reduced. However, the degree of increasing the wall thickness is small, and the change in thickness is smoothed, so that the decrease in fluid when the valve is fully opened is small. However, it cannot be denied that there is still a problem that the flow rate when fully opened is reduced. Accordingly, it has been desired to develop a means for facilitating fluid control in a low opening region of the valve body by another means.

  The present invention was born in response to the above-mentioned demand. That is, the present invention makes it possible to easily control the amount of fluid in a low opening region in a triple eccentric butterfly valve, and to allow a large amount of fluid to flow when the valve is fully opened, and to seal the valve seat surface. It is intended to be able to open the valve completely and smoothly from the fully closed position.

  Until now, in the triple eccentric butterfly valve, when fully closed, the valve body surface 31 is held perpendicular to the fluid flow direction, that is, the central axis direction of the fluid passage, as disclosed in Japanese Patent Laid-Open No. 2003-161374. I came. This is because it was considered to be the most reasonable means to employ when the fluid is fully closed. However, this inventor, when fully closing the triple eccentric butterfly valve, slightly inclines the valve body surface 31 in the direction opposite to the direction in which the valve body opens, without increasing the thickness of the outer periphery of the valve body, It was found that the fluid amount can be easily adjusted in a low opening range. The present invention has been completed based on such knowledge.

  The present invention relates to a butterfly valve comprising a valve body having a tubular fluid passage and a valve body rotatably provided around the valve shaft in the fluid passage. The valve body is attached so as to protrude from the plane connecting the outer peripheral surfaces of the body, and the valve shaft is attached to the outer side of the valve body with one side being offset from the center of the valve body. In the triple eccentric butterfly valve which is one inclined conical surface having an apex on the opposite side of the valve shaft, the valve body has a substantially flat surface on the side where the valve shaft is not provided. The outer peripheral surface on the orifice side is a circumferential surface extending perpendicularly from the surface, the outer peripheral surface on the nozzle side is a truncated cone surface that gradually spreads from the surface to the back surface, and when the valve is fully closed, the valve body surface is the orifice on the nozzle side. The valve protrudes in the opposite direction to the valve shaft installation side from the side. Characterized in that it is in an inclined state in the body, there is provided a triple offset butterfly valve.

  In the present invention, the valve body is attached to the valve shaft so as to protrude from the plane connecting the outer peripheral surface of the valve body, and is eccentric in the primary direction. Therefore, when the valve body starts to open from the fully closed state of the valve, the valve body is easily separated from the valve seat surface of the valve body at the same time, and the outer peripheral surface on the nozzle side moves more than the outer peripheral surface on the orifice side. . At this time, in the valve body, the outer peripheral surface on the orifice side is a circumferential surface extending perpendicularly from the surface of the valve body, the outer peripheral surface on the nozzle side is a truncated cone surface, and in the fully closed state, the outer peripheral surface on the nozzle side is the orifice side. Since it protrudes to the opposite side of the valve shaft mounting side from the outer peripheral surface of the nozzle, only a small gap is formed on the nozzle side at the beginning of rotation, and therefore the total amount of fluid flowing through the gap can be kept low. . For this reason, the amount of fluid can be easily controlled in a low opening region of the valve body.

  In addition, the valve body has a substantially flat surface, and the outer wall thickness is not increased on the back surface side, so that a large amount of fluid can flow when the valve is fully opened. Furthermore, since the valve seat surface is an inclined conical surface and a triple eccentric butterfly valve is used, the seal can be completely opened and the valve can be opened smoothly from the fully closed state. The present invention provides such an effect.

  An embodiment of the present invention will be described with reference to the drawings as follows. FIG. 2 is a cross-sectional view of the valve when the triple eccentric butterfly valve according to the present invention is cut off on a plane passing through the center of the valve shaft and perpendicular to the valve shaft when the valve is fully closed. FIG. 3 is a similar cross-sectional view showing the state when the triple eccentric butterfly valve according to the present invention shown in FIG. 2 is opened by an angle of about 15 degrees from the fully closed state. FIG. 4 shows a flow characteristic curve of the triple eccentric butterfly valve according to the present invention.

  As is apparent from a comparison between FIG. 1 and FIG. 2, the triple eccentric butterfly valve according to the present invention shown in FIG. 2 is different from the known triple eccentric butterfly valve shown in FIG. The mounting state is different. That is, both FIG. 1 and FIG. 2 show the fully closed state of the triple eccentric butterfly valve. In the triple eccentric butterfly valve according to the present invention, the valve body 5 has a uniform thickness, and the surface 51 is formed on the valve body. Although the known valve body 3 is thicker toward the outer periphery, the surface 31 is perpendicular to the center axis of the fluid passage in the valve body 1. It is different in point.

  2, the valve body 5 shown in FIG. 2 has an orifice-side outer peripheral surface 52 that extends perpendicularly to the surface 51 of the valve body 5 in the same manner as the valve body 3 shown in FIG. The outer peripheral surface 53 is a truncated cone surface that gradually spreads away from the surface 51. Further, the valve body 5 has a substantially flat surface 51 and a substantially flat back surface 54 except for a portion 55 that supports the valve shaft 2. Therefore, the valve body 5 has a substantially uniform thickness.

  In the fully closed state, the valve body 5 is slightly inclined with respect to the surface 51 perpendicular to the central axis of the fluid passage of the valve body 1. Accordingly, the surface 51 is also inclined in the same manner with respect to the plane connecting the side surfaces of the seat ring 4. The inclination direction is a direction in which the nozzle side protrudes in the direction opposite to the side on which the valve shaft 2 is attached rather than the orifice side. This direction is also the direction in which the apex of the cone formed by the valve seat surface of the seat ring 4 exists. This inclination is slight, and the inclination angle α is in the range of 2 to 5 degrees.

  In the triple eccentric butterfly valve, the thickness of the valve body 5 is made larger than the thickness of the seat ring 4. Accordingly, the fact that the valve body 5 protrudes the nozzle side to the opposite side to the attachment side of the valve shaft 2 and retracts the orifice side means that the front half of the truncated cone surface 53 protrudes from the inner peripheral surface of the seat ring 4. Will be.

  Accordingly, the fluid is caused to flow along the arrow P opposite to the direction in which the valve shaft 2 is attached to the triple eccentric butterfly valve according to the present invention, and the valve body 5 is moved at a slight angle, for example, about 15 degrees from the fully closed state. When opened by turning in the direction of arrow Q, the butterfly valve is in the state shown in FIG.

  Since the triple eccentric butterfly valve according to the present invention is originally in the state of FIG. 2 and the valve body 5 is inclined, the valve body 3 is perpendicular to the central axis of the fluid passage from the beginning as shown in FIG. Compared to the conventional triple eccentric butterfly valve, the valve body 5 is rotated excessively until the valve body 5 is perpendicular to the central axis of the fluid passage. Moreover, in the triple eccentric butterfly valve according to the present invention, since the fluid flows from the time when the valve body starts to open, the same degree of opening as before is reached over a longer time than the conventional one. Therefore, the triple eccentric butterfly valve according to the present invention gradually brings the same flow rate change over a longer time than the conventional one at the beginning of the valve opening, so that the flow rate change per hour is small. Therefore, the initial flow rate can be easily adjusted.

  Actually, a flow characteristic curve of the triple eccentric butterfly valve according to the present invention is shown in FIG. FIG. 4 shows a flow rate characteristic curve of the triple eccentric butterfly valve, with the horizontal axis representing the valve opening angle and the vertical axis representing the flow coefficient. A curve B in FIG. 4 shows a flow characteristic curve of the triple eccentric butterfly valve according to the present invention. The curve A uses the same valve body and is in a fully closed state with the valve body surface perpendicular to the central axis of the fluid passage. The flow characteristic curve of the conventional triple eccentric butterfly valve is shown. According to FIG. 4, at a low opening of the valve body up to an angle of 40 degrees, the triple eccentric butterfly valve according to the present invention has a smaller flow coefficient than the conventional one, so that the flow control at the initial stage of valve opening is easy. Thus, it is found that the flow coefficient remains unchanged when the valve body is opened by 40 degrees or more. The present invention provides such an unexpected effect.

It is a fully closed state sectional view of the conventional triple eccentric butterfly valve. It is a full-closed state sectional view of the triple eccentric butterfly valve concerning this invention. It is sectional drawing of the valve opening initial stage of the triple eccentric butterfly valve concerning this invention. It is the graph which showed the flow characteristic curve of the triple eccentric butterfly valve concerning this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Valve body 2 Valve shaft 3 Conventional valve body 4 Seat ring 5 Valve body 31, 51 Valve body surface 32, 52 Outer peripheral surface 33, 53 of valve body Nozzle side outer surface 34, 54 Back side of valve body 35, 55 Valve shaft support part A Flow characteristic curve of conventional triple eccentric butterfly valve B Flow characteristic curve of triple eccentric butterfly valve according to the present invention

Claims (2)

  Of the butterfly valves consisting of a valve body having a circular fluid passage and a valve body rotatably provided around the valve shaft in the fluid passage, the valve body has a valve shaft that has a valve body outer peripheral surface. The valve shaft is attached to the valve body so that it protrudes from the connecting plane, and the valve stem is attached to the outer side of the valve body. In the triple eccentric butterfly valve which has one inclined conical surface with a crocodile apex opposite to the shaft, the valve body has a substantially flat surface on the side where the valve shaft is not attached, and the outer circumference on the orifice side. The surface is a circumferential surface extending perpendicularly from the surface, the outer peripheral surface on the nozzle side is a truncated cone surface that gradually spreads from the surface to the back surface, and when the valve is fully closed, the valve body surface is positioned on the nozzle side more than the orifice side. Inclined in the valve body by protruding in the opposite direction to the shaft side Characterized in that it is in the state, triple offset butterfly valve. 2. The triple eccentric butterfly valve according to claim 1, wherein an angle of inclination of the valve body surface is in a range of 2 to 5 degrees from a plane perpendicular to the central axis direction of the fluid passage.

Images