JP2015143534A - diaphragm valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a diaphragm valve capable of suppressing generation of particles so as to overcome problems that a diaphragm of a diaphragm valve with the diaphragm used as a valve element elastically deforms to repeatedly press or separate from a valve seat and that particles may be generated over long-term use.SOLUTION: In a diaphragm valve 1 comprising: a valve box 2 in which a fluid inflow passage 2a and a fluid outflow passage 2b are provided; an annular valve seat 3 provided integrally on the valve box 2 so as to be located on a peripheral edge of the fluid inflow passage 2a; and a diaphragm 4 opening or closing the fluid inflow passage 2a by pressing or separating from the valve seat 3, a tip end portion of the valve seat 3 being formed such that a tip end portion of the valve seat 3 has a circular arc cross-section, an inner circumferential surface thereof is a cylindrical surface, and an outer circumferential surface thereof is a conical surface, whereby the friction between a load acting position and the tip end position of the valve seat 3. As a result, it is possible to prevent generation of particles.

Description

  The present invention relates to a diaphragm valve, and more particularly to a diaphragm valve advantageous for use at high temperatures.

  As a diaphragm valve advantageous for use at high temperatures, Patent Document 1 discloses a valve box provided with a fluid passage, an annular valve seat provided at the periphery of the fluid passage, and a fluid that is pressed or spaced apart from the valve seat. There is disclosed a diaphragm including a diaphragm that opens and closes a passage and a valve rod that has a diaphragm presser at the lower end and is movable up and down.

JP 2004-92825 A

  Since the diaphragm is elastically deformed and repeatedly presses and separates from the valve seat, there is a possibility that particles are generated with long-term use.

  Conventionally, with respect to the generation of particles, the shift between the applied load position on the diaphragm and the tip position of the valve seat has not been considered.

  An object of the present invention is to provide a diaphragm valve capable of suppressing the generation of particles by paying attention to the deviation between the applied load position in the diaphragm and the tip position of the valve seat.

  A diaphragm valve according to the present invention includes a valve box provided with a fluid passage, an annular valve seat provided at the periphery of the fluid passage, a diaphragm pressed or spaced apart from the valve seat to open and close the fluid passage, and a diaphragm at the lower end. A diaphragm valve having a presser and a vertically movable valve rod is characterized in that the load application position in the diaphragm and the tip position of the valve seat are the same.

  “The load acting position on the diaphragm and the tip position of the valve seat are the same” means that the deviation is at least 15 μm or less, preferably 5 μm or less.

  The valve seat is preferably provided integrally with the valve box, and is preferably made of stainless steel and a double melt material.

  The valve seat preferably has a circular arc at the tip, a cylindrical surface at the inner peripheral surface, and a conical surface at the outer peripheral surface.

  In the conventional diaphragm valve, the tip position of the valve seat is radially outward from the load application position in the diaphragm. The cross-sectional shape of the valve seat with a circular arc at the tip, a cylindrical surface at the inner periphery, and a conical surface at the outer periphery is suitable for moving the tip position of the valve seat radially inward. By setting the valve seat to this cross-sectional shape, the load acting position in the diaphragm and the tip position of the valve seat can be easily made the same.

  In order to make the load acting position and the valve seat tip position in the diaphragm the same, the valve seat diameter (twice the distance from the valve seat center line to the valve seat tip) and the valve seat height (valve box) The distance between the load application position on the diaphragm and the valve seat tip position is determined by changing the distance from the bottom of the recess to the valve seat tip, and the distance between the load application position on the diaphragm and the valve seat tip position is conventionally What is necessary is just to set the diameter and height of a valve seat so that it may become smaller from the thing (it becomes substantially 0).

  In this specification, the moving direction of the stem is referred to as the vertical direction. However, this direction is convenient, and in actual mounting, the vertical direction is not only the vertical direction but also the horizontal direction. Sometimes it is said.

  According to the diaphragm valve of the present invention, the generation of particles due to the displacement between the applied load position in the diaphragm and the tip position of the valve seat is prevented, and thus, even in severe use environments such as high temperature conditions, Can be suppressed.

FIG. 1 is a longitudinal sectional view showing the entire configuration of a diaphragm valve according to the present invention. FIG. 2 is an enlarged longitudinal sectional view showing a characteristic portion of the diaphragm valve according to the present invention. FIG. 3 is a diagram showing a simulation result of the shear stress distribution for the diaphragm valve of FIG. FIG. 4 is a graph showing test results of the number of particle generations for the diaphragm valve of FIG. FIG. 5 is an enlarged longitudinal sectional view showing a characteristic part of a diaphragm valve of a comparative example. FIG. 6 is a diagram showing a simulation result of shear stress distribution for the diaphragm valve of the comparative example. FIG. 7 is a graph showing test results of the number of particle generations for the diaphragm valve of the comparative example.

  Embodiments of the present invention will be described below with reference to the drawings. In the following description, the upper, lower, left, and right refer to the upper, lower, left, and right in FIG.

  FIG. 1 shows the overall configuration of a diaphragm valve targeted by the present invention.

  In the figure, the diaphragm valve (1) has a valve box (2) provided with a fluid inflow passage (2a) and a fluid outflow passage (2b), and a valve box so as to be positioned at the periphery of the fluid inflow passage (2a). An annular valve seat (3) provided integrally with (2), a diaphragm (valve body) (4) that opens or closes the fluid passage (2a) by being pressed or separated by the valve seat (3), and a diaphragm at the lower end A vertically movable disc (valve body retainer) (5) with a retainer (5a) attached, a bonnet (6) fitted over the disc (5), and a lower casing provided on the top of the valve box (2) (7), the upper casing (8) connected to the lower casing (7), and the upper and lower casings (7), (8) are arranged in a space formed by the lower end abutting against the valve disc holder (5). The valve stem (9), the piston (10) disposed in the upper part of the casing (7) (8), and the piston (10) provided below the piston (10) in the casing (7) (8). Force Amplified and and a booster means (11) for transmitting to the valve rod (9).

  The valve box (2) has a recess (2c) that opens upward, and the fluid inflow passage (2a) has one end that opens toward the left and the other end that is a recess (2c). The fluid outflow passageway (2b) has one end opened to the right and the other end opened to the bottom right part of the recess (2c).

  The disk (5) is formed in a columnar shape and has a flange portion in the middle. The bonnet (6) is formed in a cylindrical shape, and a large-diameter guide portion (6a) for guiding the flange portion of the disk (5) is formed on the inner periphery of the lower portion of the bonnet (6). The disc (5) is inserted into the bonnet (6) so as to be loose, that is, movable up and down. The bonnet (6) is fitted into the recess (2c) of the valve box (2) and pressed downward by the lower casing (7), thereby allowing the outer periphery of the diaphragm (4) to pass through the holding adapter (12). The part is fixed to the valve box (2).

  The lower casing (7) includes a bottom wall (7a), a peripheral wall (7b) that is provided on the bottom wall (7a) in a standing manner and has a threaded portion formed on the outer peripheral surface, and a lower surface from the bottom surface of the bottom wall (7a). It consists of a small-diameter cylindrical downward projecting portion (7c) having a female thread portion formed on the inner peripheral surface. The lower casing (7) is formed by screwing the female thread part of the downward projecting part (7c) with the male thread part provided on the outer peripheral surface of the recess (2c) of the valve box (2), thereby ).

  At the center of the bottom wall (7a) of the lower casing (7), a through hole (13) for guiding the valve rod (9) so as to be movable up and down is provided.

  The upper casing (8) includes a cylindrical peripheral wall (8a) and a disk-shaped top wall (8b) that is provided at the upper end of the peripheral wall (8a) and is screwed to the threaded portion. A female threaded portion is formed on the lower inner peripheral surface of the peripheral wall (8a), and this female threaded portion is screwed to the male threaded portion of the peripheral wall (7b) of the lower casing (7), so that the upper casing ( 8) and the lower casing (7) are integrated so as to form a space inside. The top wall (8b) of the upper casing (8) is provided with a through hole (14) in the center thereof, and a compressed air introducing joint (15) is attached to the through hole (14). .

  The valve stem (9) includes a large-diameter shaft portion (21) having a downward projecting portion (21a) slidably fitted in the central through hole (13) of the lower casing (7), and a threaded portion at the lower end. The male screw portion is provided on the upper portion of the large-diameter shaft portion (21), and is therefore composed of a small-diameter shaft portion (22) integrated with the large-diameter shaft portion (21) by being screwed into the screw. The large-diameter shaft portion (21) has a flange portion (21b) positioned at the base end portion of the downward projecting portion (21a) and an upper end portion that has a smaller diameter than the other portions and is abutted against the small-diameter shaft portion (22) ( 21c). The small-diameter shaft portion (22) has a flange portion (22a) having a slightly smaller diameter than the upper end portion (21c) of the large-diameter shaft portion (21) at an intermediate portion thereof.

  The piston (10) is formed in a disk shape composed of a lower large-diameter portion (10a) and an upper small-diameter portion (10b), and an annular piston is formed on the outer peripheral portion of the lower surface of the large-diameter portion (10a). The ring (23) is integrated. A recess (24) is formed at the center of the lower surface of the top wall (8a) of the upper casing (8), and the top wall (8a) of the upper casing (8) formed by this recess (24). The space between the piston 10 and the piston 10 is a space for introducing compressed air.

  A metal bellows (16) formed in a cylindrical shape as a whole is arranged on the outer periphery of the small diameter portion (10b) of the piston (10), and the lower end of the metal bellows (16) is the large diameter portion (10a). The space for introducing compressed air is sealed by being fixed to the upper surface and the upper end thereof being fixed to the lower surface of the top wall (8a) of the upper casing (8). The metal bellows (16) is called a welding bellows, and is manufactured by punching metal into a disk shape to form a precise corrugated plate and welding the inner and outer circumferences of the corrugated plate. .

  The booster means (11) has a plurality of oscillating bodies (25) supported so as to be able to oscillate around the horizontal axis (26). The rocking body (25) has an outer end abutting against the lower surface of the piston ring (23) and an inner end abutting against the lower surface of the flange portion (22a) of the small diameter shaft portion (22) of the valve stem (9). It has been made. The piston contact position of the outer end of the rocking body (25) is above the valve rod contact position of the inner end of the rocking body (25), and the axis of the horizontal axis (26) is the axis of the rocking body (25). The piston is positioned closer to the inner end than the intermediate position between the piston contact position of the outer end and the valve rod contact position of the inner end of the rocking body (25). Therefore, when the piston (10) moves downward, the outer end of the rocking body (25) of the booster means (11) moves downward, and the rocking body (25) rotates around the horizontal axis (26) accordingly. The inner end of the oscillating body (25) moves upward, and the valve stem (9) is moved upward. Since the horizontal shaft (26) is positioned closer to the inner end, the downward force of the piston (10) is amplified and transmitted to the valve stem (9). The amplification factor is (distance from the axis of the horizontal axis to the piston contact position of the outer end of the oscillator) / (distance from the axis of the horizontal axis to the valve rod contact position of the inner end of the oscillator). .

  For example, three rockers (25) are provided at intervals of 120 ° or four at intervals of 90 °. The horizontal shaft (26) is held by a cylindrical retainer (27) placed on the upper surface of the large diameter shaft portion (21). The retainer (27) includes a perforated disk-shaped bottom wall (27a) and a peripheral wall (27b) in which notches that allow the oscillating body (25) to move are formed at predetermined intervals. A recess (25a) opening upward is provided at the inner end of the rocking body (25), and a pin (28) fitted into the recess (25a) so as to be able to roll is a valve stem (9 ) In contact with the flange portion (22a) of the small diameter shaft portion (22).

  The biasing member (17) that biases the valve stem (9) downward is a disc spring, and the flange portion (21b) of the large-diameter shaft portion (21) of the valve stem (9) and the retainer (27) And the bottom wall (27a). A metal seal (18) is interposed between the outer peripheral surface of the bottom wall (27a) of the retainer (27) and the inner peripheral surface of the peripheral wall (7b) of the lower casing (7).

  In the above, the valve box (2) and the valve seat (3) provided integrally therewith are made of stainless steel such as SUS316L and are made of a double melt material. Double melt is a method in which electroslag remelting or vacuum arc remelting is performed after vacuum induction furnace melting or vacuum oxygen decarburization.

  The diaphragm retainer (5a) is a nickel alloy (for example, NW2201). Both the metal bellows (16) and the belleville spring as the biasing member (17) are made of Inconel (registered trademark). The metal bellows (16) is, for example, a solid solution strengthened Ni-base superalloy called IN625, and the disc spring of the biasing member (17) is made of, for example, a precipitation hardening Ni-base superalloy, called IN718. Has been.

  According to the diaphragm valve (1), the metal bellows (16) is used for sealing the space for introducing compressed air, and the rubber O-ring is not used. Therefore, it has excellent heat resistance and can sufficiently withstand high temperatures. In addition, by having the boosting means (11), a large diaphragm pressing force can be obtained even if the compressed air pressure to be introduced is reduced, so that the pressure applied to the metal bellows (16) can be reduced. And a high-temperature diaphragm valve with excellent pressure resistance can be obtained.

  The diaphragm valve (1) according to the present invention is the one shown in FIG. 1, in which the shape of the valve seat (3) is optimized as follows.

  In order to realize optimization of the valve seat (3), first, regarding the valve seat (30) of the comparative example (conventional general one) shown in FIG. 30) The deviation from the tip position was simulated.

  In FIG. 5, the valve seat (30) has a tip end portion (41) having an arcuate cross section and an inner peripheral surface (42) and an outer peripheral surface (43) having a conical surface. It is symmetric with respect to the line (line passing through the tip of the valve seat (30)) (O ').

  FIG. 6 shows a shear stress distribution by simulation in the case of the valve seat (30) having the shape shown in FIG. From this, it can be seen that the displacement between the applied load position of the diaphragm (4) and the tip position of the valve seat (30) is about 35 μm. Such a deviation is a cause of rubbing between the valve seat (30) and the diaphragm (4), and thus causes generation of particles.

  FIG. 7 shows the measurement of the transition of the particle generation state with the number of opening and closing in the case of the valve seat (30) having the shape shown in FIG. The number of particles is determined by distinguishing the size. From FIG. 7, when the number of particles (the number of particles generated by opening and closing 90 times) increases as the number of times of opening and closing increases, and the particle generation reference is set to 1.0 or less / 1 opening / closing, It can be seen that this is more than the opening and closing times.

  Therefore, paying attention to the deviation between the applied load position in the diaphragm (4) and the tip position of the valve seat (3) (30), the model of FIG. 2 was studied so as to eliminate this deviation.

  In FIG. 2, the valve seat (3) has a distal end portion (31) having an arcuate cross section, an inner peripheral surface (32) having a cylindrical surface, and an outer peripheral surface (33) having a conical surface. O) is asymmetric.

  FIG. 3 shows a shear stress distribution by simulation in the case of the valve seat (3) having the shape shown in FIG. From this, it can be seen that the deviation between the applied load position of the diaphragm (4) and the tip position of the valve seat (30) is substantially zero. Such a deviation is a cause of rubbing between the valve seat (30) and the diaphragm (4), and thus causes generation of particles.

  FIG. 4 shows the measurement of the transition of the particle generation state with the number of opening / closing in the case of the valve seat (3) having the shape shown in FIG. 2 in the same manner as in FIG. From FIG. 4, the number of particles (the number of particles generated by opening and closing 90 times) increases at the time when the number of opening and closing is 100,000 times, but then decreases, and the particle generation standard is 1.0 or less / If it is set to 1 open / close, it is significantly below this standard. If the displacement between the applied load position on the diaphragm (4) and the tip position of the valve seat (30) is 15 μm or less, the number of particles generated can be greatly reduced compared to the comparative example. By setting the value to 5 μm or less, it is possible to achieve 1.0 particles or less / 1 open / close, which is a particle generation standard.

  In the optimized shape shown in FIG. 2, the diameter and height are changed at points other than the cross-sectional shape. The diameter of the valve seat (3) (the centerline of the valve seat (3) = the valve stem (9) The distance from the central axis to the tip of the valve seat (3) is twice as small as 6 mm to 4.1 mm, and the height of the valve seat (3) is increased by 0.1 mm. From this, it can be seen that in terms of dimensions, it is preferable to reduce the diameter of the valve seat (3) and increase the height of the valve seat (3). The diameter of the diaphragm (4) is 20 mm, the diameter of the bulge portion is 18 mm, and the bulge height (distance from the lowermost surface to the uppermost surface) is 0.75 mm. As a preferable range of the diameter d and the height h of the valve seat (3), the diameter of the bulging portion of the diaphragm (4) is D and the bulging height of the diaphragm (4) is H, and d / D = 0. Examples are 2 to 0.3 and h / H = 0.1 to 0.2.

  Thus, by optimizing the shape of the valve seat (3) with respect to the valve seat (30) of the comparative example shown in FIG. 5, the particle generation standard of 1.0 or less particles / 1 open / close is achieved. be able to.

(1): Diaphragm valve, (2): Valve box, (2a): Fluid inflow passage (fluid passage), (3): Valve seat, (4): Diaphragm, (5a): Diaphragm retainer, (9): Valve stem, (31): Tip, (32): Inner peripheral surface, (33): Outer peripheral surface

Claims (2)

A valve box provided with a fluid passage, an annular valve seat provided at the periphery of the fluid passage, a diaphragm that opens or closes the fluid passage by being pressed or spaced apart from the valve seat, and a diaphragm presser at the lower end, and is movable up and down Diaphragm valve equipped with a simple valve stem,
A diaphragm valve characterized in that a load application position and a tip position of a valve seat in the diaphragm are the same.   2. The diaphragm valve according to claim 1, wherein the valve seat has a circular arc at the tip, a cylindrical surface at the inner peripheral surface, and a conical surface at the outer peripheral surface.