JP5598701B2 - Check valve - Google Patents

Description

  In carrying out a so-called purge (pressurization) operation in which the concentration of the gas in the predetermined space is increased by supplying the gas into the predetermined space at a pressure higher than the pressure in the surrounding space. The present invention relates to a backflow prevention valve that prevents backflow of the gas. More specifically, the present invention relates to a backflow prevention valve that operates stably even if the differential pressure between the predetermined space and the surrounding space is small, and can ensure a practically sufficient gas supply amount.

  Metal magnet materials used in so-called rare earth magnets with strong magnetic force are highly active in powder and are rapidly oxidized, so that the oxidation is suitably suppressed until the compacting-sintering operation. Is required. Therefore, in various manufacturing processes such as a compression molding process, the atmosphere around the material or the processing apparatus itself must be controlled to a low oxidation concentration by supplying nitrogen, for example. Patent Document 1 discloses a technique for enclosing the entire manufacturing apparatus and air-tightening the manufacturing line for the purpose of replacing the gas in the space with nitrogen. In this technique, for example, when the oxygen concentration inside a space called a so-called maintenance zone is reduced, the gas inside the space is rapidly purged and replaced with nitrogen to obtain a state where the manufacturing process can be performed. Further, in maintaining the concentration thereafter, the supply amount of nitrogen is decreased, and the supply of nitrogen is continued in that state, thereby reducing the manufacturing cost by reducing the amount of nitrogen used.

  At the time of the rapid purge described above, if nitrogen can be supplied at a flow rate of a certain level or more, it is relatively easy to obtain a space having a predetermined low oxygen concentration. Further, even when the purge efficiency is high, the so-called purge time can be easily reduced by increasing the nitrogen flow rate. Further, in the case where the entire apparatus is sealed in a casing, the amount of nitrogen required for purging can be suppressed if the casing is highly sealed. However, when the actual manufacturing apparatus is movable, the amount of nitrogen used in a state where the low oxygen concentration is maintained often becomes a big problem in manufacturing cost. Therefore, the amount of nitrogen required for maintaining the concentration is preferably as small as possible. However, in this case, since the differential pressure between the space inside the housing and the external space becomes a slight condition, it is not easy to take a sufficient differential pressure between the so-called upstream and downstream in the nitrogen supply line. In this case, if the differential pressure obtained between the upstream and downstream in the path connected to the surroundings or inside the apparatus is small, it is conceivable that a backflow of supplied nitrogen or the like occurs.

JP 2007-083280 A Japanese Patent Laid-Open No. 9-042499 Utility Model Registration No. 3100586

  A so-called backflow prevention valve disclosed in Patent Document 2 or 3 is known as a configuration for preventing backflow when supplying gas. However, the configuration disclosed in Patent Document 2 targets a liquid, and a clear pressure difference can be obtained upstream and downstream of the valve as compared with the case where a gas as described above is targeted. Therefore, even if the configuration disclosed in this document is used as it is in the purge apparatus targeted by the present invention, it is considered that a sufficient effect cannot be obtained because the acting differential pressure is slight. Moreover, although the structure disclosed by patent document 3 is intended for gas, at the time of supply of a large flow rate gas at the time of the rapid purge described above and at the time of supply of a small flow rate gas at the time of maintaining the state of the apparatus Is not considered at all. That is, the disclosed apparatus can actually only be used under either condition. In view of the above, it is desired to provide a backflow prevention valve that can operate with a slight differential pressure and can handle a large flow rate (eg, 3000 L / min) to a small flow rate (eg, 10 L / min).

  The present invention has been made in view of the above situation, and can be operated even when the pressure difference between the upstream and downstream positions is small, and from a large flow rate to a small flow rate as necessary. An object of the present invention is to provide a backflow prevention valve that can supply gas up to.

  In order to solve the above-mentioned problem, the backflow prevention valve according to the present invention is arranged in a system in which gas flows from the primary side to the secondary side, and prevents the backflow of gas from the secondary side to the primary side. A gas flow path that is connected to the primary side and the secondary side and through which a gas can flow; and a primary pressure that is disposed in the gas flow path and that acts from the gas present on the primary side and A valve body that can move in a predetermined region by a force that acts due to a pressure difference from the secondary pressure that acts from the gas present on the secondary side, and constitutes one end of the gas flow path, and a part of the gas flow path A primary side member having a primary side vent and a sheet-like elastic member fixed to the primary side opening of the primary side vent and having a seal opening coaxial with the primary side opening, and is in close contact with the valve body A sealing member capable of closing the gas flow path by, and in the sealing member The inner diameter of Lumpur opening is smaller than the inner diameter of the primary-side opening, the sealing member is characterized by having a portion protruding protruding inside the primary-side opening.

  In the above-described backflow prevention valve, the inner diameter of the primary side opening of the primary side vent is preferably larger than the inner diameter of the other part of the primary side vent. In addition, it is preferable that the check valve further includes a valve body operation range regulating means that defines a predetermined region that is a moving range of the valve body and that promotes seating of the valve body at a predetermined position on the seal member. Furthermore, it is preferable that there are a plurality of the valve bodies, and the primary side vent and the seal member are arranged corresponding to each of the valve bodies. In this case, it is more preferable that the plurality of valve bodies include valve bodies having different weights. Alternatively, the plurality of primary side vents corresponding to the plurality of valve bodies more preferably include primary side vents having different inner diameters of the openings.

  Moreover, in order to solve the said subject, the backflow prevention valve which concerns on this invention is arrange | positioned in the system into which gas flows from a primary side to a secondary side, and prevents the backflow of the said gas from a secondary side to the said primary side. A backflow prevention valve that is connected to the primary side and the secondary side and is capable of flowing gas, and is disposed in the gas flow path and acts from the gas present on the primary side A valve body capable of moving in a predetermined region by a force acting due to a pressure difference between the side pressure and the secondary pressure acting from the gas existing on the secondary side, and one end of the gas flow path, A primary side member having a primary side vent that is a part of the channel, and a seal member that is fixed to the primary side opening of the primary side vent and that can close the gas flow path by being in close contact with the valve body. However, there are a plurality of valve bodies, and the primary side vent and the seal member are arranged corresponding to each valve body. It is characterized by being.

  In the backflow prevention valve described above, it is preferable that the plurality of valve bodies include valve bodies having different weights. Or it is preferable that the several primary side vent which respond | corresponds to a some valve body contains the primary side vent which the internal diameter of a primary side opening differs. For the above-described backflow prevention valve, the inner diameter of the seal opening fixed coaxially with the primary side opening in the seal member is smaller than the inner diameter of the primary side opening, and the seal member protrudes inside the primary side opening. More preferably, it has a portion.

  According to the present invention, even when the differential pressure between the upstream and downstream where the backflow prevention valve is arranged is small, the backflow prevention valve can perform a backflow prevention operation that is stable and excellent in responsiveness. It becomes possible. In addition, since a sufficient gas flow path can be secured, it is possible to supply gas from a large flow rate to a small flow rate. Furthermore, according to the present invention, it is possible to actually observe the operation of the mechanism by forming the case with, for example, a transparent resin material, and it is possible to easily know whether the operation is appropriate. In addition, since electrical control is unnecessary, it is possible to obtain effects such as a reduction in cost required for construction of a gas supply system and a reduction in management and maintenance costs.

About the one aspect | mode of the backflow prevention valve which concerns on this invention, the structure of the principal part in the cross section which cut | disconnected this backflow prevention valve which is 1st embodiment along the gas flow direction (axial direction of a backflow prevention valve) is typical. FIG. It is a side surface schematic diagram for demonstrating the relationship between seal thickness and the amount of protrusion. It is a figure which shows typically the structure of the principal part in the cross section which cut | disconnected this backflow prevention valve along the flow direction of gas about 1st embodiment of the backflow prevention valve which concerns on this invention. It is a figure which shows typically the state which prevented the backflow actually in the structure shown to FIG. 3A. It is a figure which shows typically the structure of the principal part in the cross section which cut | disconnected this backflow prevention valve along the gas flow direction about 2nd embodiment of this invention. It is a figure which shows typically the structure of the principal part in the cross section which cut | disconnected this backflow prevention valve along the flow direction of gas about 3rd embodiment of this invention. It is a figure which shows typically the structure of the principal part in the cross section which cut | disconnected this backflow prevention valve along the flow direction of gas about 4th embodiment of this invention. 6A is a diagram schematically showing a state in which a cross section of the backflow prevention valve taken along line 6B-6B in the drawing is viewed from the direction B in the embodiment shown in FIG. 6A. FIG. It is a figure which shows typically the structure of the principal part in the cross section which cut | disconnected this backflow prevention valve along the flow direction of gas about 5th embodiment of this invention. FIG. 7B is a diagram schematically showing a state in which the backflow prevention valve actually supplies a small flow rate gas in the embodiment shown in FIG. 7A. It is a figure which shows typically the structure of the principal part in the cross section which cut | disconnected this backflow prevention valve along the flow direction of gas about 6th embodiment of this invention. FIG. 8B is a diagram schematically showing a state in which the backflow prevention valve actually supplies a small flow rate gas in the embodiment shown in FIG. 8A.

(First embodiment)
A first embodiment of a check valve according to the present invention will be described below with reference to the drawings. FIG. 1: has shown schematic structure in the cross section when this is cut | disconnected along the flow direction of the gas in this backflow prevention valve about the main structures of the backflow prevention valve 1 which concerns on 1st embodiment of this invention. The backflow prevention valve 1 includes a valve body 2, a seal member 3, a primary side member 5, a secondary side member 7, a case member 9, a fastening member 11, a guide member 13, and a stopper member 19. In the backflow prevention valve 1, gas flows from the lower side in the figure where the primary side member 5 is placed to the upper side in the figure where the secondary side member 7 is placed, and the backflow prevention valve 1 Prevent flow. In the present embodiment, for convenience, the primary side of the system connected to the primary side member 5 is the upstream side and the gas is discharged to the backflow prevention valve 1 for the secondary side. The secondary side of the system connected to the side member 7 is the downstream side.

  The primary side member 5 is a member on a flat plate, and has a primary side vent hole 5c having a substantially circular opening penetrating from the flat surface 5a to the back surface 5b at the center. An opening on the back surface 5b side of the primary side vent 5c is defined as a primary side opening 5d. The front surface 5a described here is a surface arranged on the upstream side (the side indicated as the primary side in the drawing) connected to the backflow prevention valve 1, and the back surface 5b is a surface facing the inner side of the backflow prevention valve 1. It is. Moreover, the secondary side member 7 is also a flat plate-like member, and has a secondary side vent hole 7c having a substantially circular opening penetrating from the flat surface 7a to the back surface 7b at the center. The front surface 7a described here is a surface disposed on the downstream side (the side indicated as the secondary side in the drawing) connected to the backflow prevention valve 1, and the back surface 7b faces the inner side of the backflow prevention valve 1. Surface.

  The case member 9 having a hollow is arranged so as to be sandwiched between the back surface 5b of the primary side member 5 and the back surface 7b of the secondary side member 7, and the primary side end surface 9a and the secondary side end surface 9b are respectively on the primary side. The airtight member 15 and the secondary side airtight member 17 are in close contact with each other. In the present embodiment, so-called O-rings are used for the primary side and secondary side airtight members 15 and 17. The fastening member 11 is constituted by, for example, a so-called bolt and nut, and a case member 9 is sandwiched between the primary side member 5 and the secondary side member 7, and these are integrated to form a case of the cylindrical backflow prevention valve 1. To do. The primary side vent 5c in the primary side member 5, the hollow part in the case member 9, and the secondary side vent 7c in the secondary side member 7 constitute the gas flow path 12 in the check valve 1 in the present invention. To do.

  The valve body 2 is a spherical member having a predetermined weight. The sealing member 3 is a sheet-like elastic member made of, for example, silicon rubber, and has an outer dimension larger than the inner diameter of the primary side opening 5d and a through hole having an inner diameter smaller than the inner diameter of the primary side opening 5d. The opening of the through hole that penetrates the sheet surface of the seal member 3 is defined as a seal opening 3a (see FIGS. 3A and 4). In the backflow prevention valve 1, the primary side member 5 is disposed below in the vertical direction. Therefore, in a state where no gas pressure is applied to the valve body 2, the valve body 2 affected by gravity is supported by the peripheral surface of the seal opening 3 a of the seal member 3 and is in close contact with the peripheral surface. The details of the relationship between the seal opening 3a and the primary side opening 5d will be described later. The guide member 13 restricts the operation direction of the valve body 2 and exhibits the action of prompting the valve body 2 to be seated at a predetermined position on the seal member 3. In this embodiment, the guide member 13 is made of a rod-shaped member, and the primary side opening 5d is formed in the case member 9 so as to extend from the secondary side member 7 side of the backflow prevention valve 1 to the primary side member 5 side. A plurality of them are arranged so as to surround them.

  Next, the principle of operation of the check valve 1 of the embodiment shown in FIG. 1 will be described with reference to FIG. The valve body 2 is detachable from the seal member 3. The guide member 13 has a function of restricting the moving direction of the valve body 2 and maintaining the positional relationship between the valve body 2 and the seal member 3 in a suitable state. The stopper member 19 cooperates with the guide member 13 to regulate the movement range of the valve body 2, and details will be described later. As described above, the check valve 1 is disposed between the upstream system (primary gas path) and the downstream system (secondary gas path), and the pressure of the gas acting from each of these systems. Due to the difference and gravity, the valve body 2 moves inside the check valve 1. The force received by the valve body 2 from the gas pressure existing in the primary path is greater than the sum of the force received by the valve body 2 from the gas pressure existing in the secondary path and the gravity acting on the valve body 2. If larger, the valve body 2 is separated from the seal member 3. As a result, the gas flow path 12 connected from the primary side vent 5c to the secondary side vent 7c is opened. Therefore, gas flows from the primary side path toward the secondary side path.

  Conversely, the force received by the valve element 2 from the gas pressure existing in the primary path and the force received by the valve element 2 from the gas pressure existing in the secondary path and the gravity acting on the valve element 2 If smaller, the valve body 2 is seated at a predetermined position of the seal member 3. As a result, the valve body 2 contacts and closely contacts the seal member 3, and the gas flow path 12 connected from the primary side vent 5c to the secondary side vent 7c is closed. Therefore, no gas flows from the primary side path toward the secondary side path. That is, if the action of gravity is ignored, it acts from the upstream (primary side) pressure acting from the gas existing on the primary side or upstream side in the gas flow path 12 and from the gas existing on the secondary side or downstream side. The valve body 2 moves in the predetermined region 14 due to the pressure difference between the downstream side (secondary side) pressure, that is, the change in the differential pressure acting on the differential pressure. Here, the predetermined area 14 refers to an area in which the valve body 2 is movable, which is regulated by the seal member 3, the stopper member 19 (or the secondary side member 7), and the guide member 13 in the present embodiment.

  In the present embodiment, the case member 9 is made of a transparent material such as glass, acrylic, polycarbonate, or vinyl chloride. By using the material, it is possible to directly confirm the operation of the valve body 2 by visual observation, and it is possible to confirm the suitability of the operation without providing a special detection mechanism for the operation abnormality. . In this embodiment, the case member 9 has a cylindrical shape. However, the case member 9 may be formed of a cylindrical member having a polygonal cross section.

  The valve body 2 is preferably made of polypropylene (PP) resin. PP resin has a light specific gravity of 0.9 g / cc, high strength, low hygroscopicity, and resistance to chemicals. In addition, a so-called true sphere is preferable as the shape, but by using a sheet-like member as the seal member 3 as in the present embodiment, the contact between the valve body 2 and the seal member 3 can be brought into surface contact, and the sphericity can be increased. Necessary and sufficient sealing characteristics can be obtained even at the lowest. As the seal member 3, a silicon rubber sheet having a thickness of 0.2 mm, which is an elastic sheet in this embodiment, is used. As described above, the inner diameter of the seal opening 3a in the seal member 3 is smaller than the inner diameter of the primary side opening 5d in the primary side vent 5c, and is seen in a cross section in the axial direction (gas flow direction) of the check valve 1. In addition, the silicon rubber sheet protrudes inside the primary side opening 5d. The protruding portion can be easily bent by reducing the thickness of the sheet and by making the sheet an elastic body. Therefore, even if the valve body 2 is light and has a low sphericity, the surface of the valve body 2 and the surface of the seal member 3 are brought into surface contact with each other by this bending, and a necessary and sufficient sealing performance can be reliably obtained. In this embodiment, a silicon rubber sheet is used as a material for the sealing member from the viewpoint of durability, ease of processing, elasticity, and the like. However, if a sheet-like material having appropriate elasticity is used, It is possible to use. The shape of the seal opening 3a is similar to the perspective shape when the valve body 2 is viewed from the gas flow direction, is smaller than the perspective shape, and the outer edge of the valve body 2 when the center of the shape is matched. If it is the shape which contact | abuts the circumference | surroundings of the seal opening 3a, it is not prescribed | regulated in the circular shape mentioned above.

  Next, with reference to FIG. 2, the relationship between the opening diameter of the primary side vent 5c and the protruding portion 3b of the seal member will be described. FIG. 2 is a cross section of the backflow prevention valve 1 cut in the gas flow direction, and schematically shows the opening end and the vicinity thereof in the primary side opening 5d of the primary side member 5 to which the sealing member 3 and the sealing member 3 are fixed. Is shown. In the figure, the amount of protrusion of the protruding portion 3b (the amount protruding from the inner edge of the primary side opening 5d of the seal member 3 toward the center of the substantially circular opening) is h, and the sheet thickness is t. When the protrusion amount h is small, the amount of bending of the sheet itself is small, and the sealing effect is reduced. Further, when the protruding amount h is large, the sealing effect itself does not vary greatly, but the effect of narrowing the primary side vent 5 becomes large, and the actual flow rate of gas passing through the valve begins to be affected. According to experiments, when the sheet thickness is t = 0.2 mm, the condition that the protrusion h is 1.0 mm is most suitable, and a suitable sealing effect is obtained in the range of 0.8 mm to 1.2 mm. Has been confirmed. As described above, the shape of the seal opening 3a is preferably similar to the shape of the valve body 2, and the shape of the primary side opening 5d is also concentrically arranged with the seal opening 3a. A similar shape is preferred. However, the shape of the primary side opening 5d can be different from the shape of the seal opening 3a.

  With reference to FIGS. 3A and 3B, the first embodiment described so far and the behavior of the valve body 2 in the embodiment will be described in more detail below. As shown in the figure, the primary side member 5 is provided with a primary side vent hole 5c. Further, the seal member 3 is fixed to the back surface 5b of the primary side member 5 so that the center of the circular primary side opening 5d coincides with the center of the seal opening 3a and the primary side opening 5d is surrounded by the seal member 3. ing. As described above, the inner diameter D3 of the seal opening 3a is set smaller than the inner diameter D5 of the primary side opening 5d, and the amount of protrusion of the protruding portion 3b of the sheet member 3 with respect to the primary side opening 5d is h described above. ing.

  By arranging the primary side member 5 vertically downward, gravity corresponding to the weight of the valve body acts on the valve body 2. However, as shown in FIG. 3A, a force (hereinafter referred to as differential pressure) acting on the valve body 2 due to the differential pressure between the pressure of the gas supplied from the upstream side and the pressure of the gas acting from the downstream side. In the case of resisting the gravity acting on 2, the valve body 2 is lifted by the differential pressure. That is, as shown in FIG. 3A, the valve body 2 is separated from the seat member 3, and the primary side vent 5 c is opened to allow gas to flow into the backflow prevention valve 1, in other words, the gas flow path 12. The downstream pressure rises due to the sufficient supply of gas to the downstream side which is the secondary side, etc., or the supply pressure of the upstream side which is the primary side falls and the upstream pressure is lowered, etc. In this state, the above-described differential pressure cannot resist the gravity acting on the valve body 2. As a result, the valve body 2 falls toward the seat member 3, and is seated and abutted on the periphery of the seal opening 3a of the seat member 3 in a predetermined positional relationship as shown in FIG. 3B. The seat member 3 is bent by the valve body 2, and the sheet member 3 is brought into surface contact with the surface of the valve body 2 by the bending, and as a result, the gas flow path 12 in the check valve 1 is completely closed from the upstream side. By the operation of the valve body 2 and the like described above, the backflow of gas from the downstream side to the upstream side through the backflow prevention valve 1 is suitably prevented.

Here, the valve opening / closing pressure (so-called cracking pressure) due to the weight of the valve body 2 will be verified. In addition, the resistance in the piping such as the gas inflow path, the outflow path, and the backflow prevention valve actually varies depending on the gas flow rate. However, in the following verification, these are ignored, and finally the airtightness in the backflow prevention state in the backflow prevention valve, so that the pressure rise in the space must not exceed a certain limit value such as 1 to 2 Kpa. Think of it as good. Here, for example, when the hole diameter of the seal opening 3a in the seal member 3 is φ30 mm,
Cross-sectional area = 30 ² × π / 4 = 707 mm ² = 7.07 cm ²
The pressure-receiving surface is a spherical surface, but it can be assumed that the surface is flat.
7.07 cm ² × 100 Pa = 7.07 gf
When the weight of the valve body 2 is 5.0 g, the cracking pressure is
100Pa / 7.07gf × 5.0gf = 70.72Pa
That is, the valve opens at 70.72 Pa.
When the weight of the valve body 2 is 5.1 g, 100 Pa / 7.07 gf × 5.1 gf = 72.14 Pa.
When the weight of the valve body is 6.0 g, 100 Pa / 7.07 gf × 6.0 gf = 84.86 Pa.
Thus, the present check valve 1 becomes capable of operating at a differential pressure of 10 ¹ to 10 ² classes like 70～80Pa, even pressure difference of very small compared to the atmospheric pressure of 10 ⁵ Pa class It becomes possible to operate.

  In the present embodiment, a spherical body made of PP resin is used as the valve body 2. However, this invention is not limited to the said form, For example, it is good also as comprising from another resin or material. For example, a hollow sphere may be formed using a thermoplastic resin, and this may be used. According to the thermoplastic resin, it is easy to increase the sphericity, the weight is lighter than that of the PP resin, and there is a merit of high strength. Although the range of use is limited due to the property of thermoplasticity, there is also a merit that surface contact with the seal member 3 can be obtained more easily, so even if the differential pressure is smaller, the differential pressure is followed. It is considered that it can be suitably used.

  In the present embodiment, the guide member is composed of a plurality of rod-shaped members, but the mode of the guide member is not limited to this. For example, it is good also as a cylindrical structure which consists of a raw material which has sufficient air permeability, such as a mesh or a punching metal, and has an internal diameter larger than the diameter of the valve body 2. FIG. In this case, the component restricts the movement range of the valve body 2 as the predetermined region 14 inside the case member 9 and closes the gas flow path 12 to the seating position on the seat member 3 of the valve body 2. If it has the effect | action which accelerates | stimulates this quick movement, you may be comprised from shapes other than illustrated. An object of the present invention is to provide a check valve that can be used in an environment where it is necessary to operate at a slight differential pressure and at the same time be capable of supplying a gas at a large flow rate. Therefore, the inner diameter of the case member 9 is set to a value that maintains a sufficient size with respect to the outer diameter of the valve body 2.

  By arranging the guide member as in this embodiment, it is possible to secure a gas flow path having a sufficient inner diameter by widening the inner diameter of the case member 9 and to move the valve body 2 to the appropriate position with respect to the seal member 3, that is, to the seating position. The effect of achieving both reliable and quick movement is obtained. That is, the movement of the valve body 2 in the plane perpendicular to the axial direction of the gas flow path 12 (flow path axial direction) is restricted by the guide member 13 to ensure reliable seating of the seal member 3 at a predetermined position. Yes. In the case of this embodiment, the guide member 13 alone defines the operating range of the valve body 2 as the predetermined region 14 and promotes the seating of the valve body 2 on the seat member 3 in an appropriate and predetermined position. The restricting means 13 is configured. In this embodiment, as a modification of the embodiment shown in FIG. 1, the operation range to the downstream side (secondary side) of the valve body 2 is defined by the secondary side member 7. The predetermined position described here is that the seal opening 3a of the seal member 3 and the center of gravity of the valve body 2 are aligned on the axis on which the differential pressure acts, and the valve body 2 is in close contact with the periphery of the seal opening 3a. This refers to the position where the seal opening 3a and the primary side opening 5d are closed (that is, the position of the valve body 2 shown in FIG. 3B).

  However, when the flow rate of the supplied gas is large, for example, the valve body 2 may be blown up inside the case member 9 and may come into contact with the secondary side opening 7c to close the gas flow path 12. In the present embodiment, as a countermeasure to such a case, as shown in FIG. 1, a stopper member 19 is further arranged inside the case member 9 to prevent an extreme approach to the downstream opening of the valve body 2. It is said. That is, the seal member 3 and the stopper member 19 mainly define the movement range of the valve body 2 in the flow path axis direction, and the guide member 13 mainly defines the movement range in a plane parallel to the flow path axis direction. Therefore, it is preferable to define the movement range of the valve body 2 as a predetermined area. In this case, the stopper member 19, together with the guide member 13, defines the operating range of the valve body 2 as a predetermined range and promotes the seating of the valve body 2 at an appropriate position on the seat member 3. , 19 is configured. The stopper member 19 can take various forms as long as it can define the operating range of the valve body 2, and can be eliminated depending on the flow rate of the gas flowing as shown in FIG. 3A. . In the present embodiment, the operation direction of the valve body 2 is perpendicular to the seal opening 3a, and the guide member 13 is also arranged accordingly. The center of the secondary vent 7c also coincides with the operation axis of the valve body 2. However, in the present invention, the operation direction of the valve body 2 may have an angle with respect to the opening direction of the seal opening 3a as long as the valve body operation range regulating means can exhibit the above-described function. The secondary vent 7c may also be arranged at a location spaced from the operation axis.

With the above-described configuration, even when the pressure difference is 10 ⁻⁴ times or less compared to the atmospheric pressure, the valve body 2 and the seal member 3 make a large sealing effect by making a sufficiently large surface contact. It is possible to construct the check valve 1 that can be present and can operate reliably. In addition, when the valve body 2 opens the gas flow path 12, it is possible to ensure a sufficiently wide gas flow path 12 between the valve body 2 and the case member 9. Further, even when the pressure difference between the primary side path and the secondary side path gradually disappears, the valve body 2 surely moves to an appropriate position on the seat member 3. It is possible to obtain a reliable operation.

(Second embodiment)
Next, a second embodiment of the present invention will be described with reference to FIG. In addition, about the same component as 1st embodiment mentioned above, this shall be shown in a figure using the same reference number, and detailed description here is abbreviate | omitted. In the first embodiment described above, since the seal member 3 protrudes inside the primary side opening 5d in the primary side vent 5c, it is considered that the seal member 3 narrows the gas flow path. It is not preferable from the viewpoint of flow rate correspondence, and when the seal member 3 bends, the seal member 3 is pressed only against the opening edge of the primary side opening 5d and is bent at approximately 90 degrees. There is concern about excessive load. In the second embodiment shown in FIG. 4, a so-called tapered portion 5 e is provided in the primary side vent 5 c so that the inner diameter of the primary side vent 5 c gradually increases with D5 as the distance from the back surface 5 b approaches. In this case, the inner diameter D6 of the primary side opening 5d is defined as the maximum diameter of the tapered portion 5e.

  In the present embodiment, by providing the tapered portion 5e, the inner diameter D3 of the seal opening 3a of the seal member 3 can be maintained equal to or greater than the inner diameter of the primary side vent 5c. Accordingly, the flow rate can be easily maintained, and the flow rate obtained from the gas flow path can be reliably obtained as a design value. Here, the relationship among the inner diameter D3 of the seal opening 3a, the inner diameter D5 at the primary-side vent 5c, and the inner diameter of the primary-side opening 5d (that is, the maximum diameter at the tapered portion 5e) D6 is preferably D5 ≦ D3 <D6. . That is, the inner diameter of the primary side opening 5d is set larger than the inner diameter of the primary side vent 5c other than the primary side opening 5d and smaller than the inner diameter of the seal opening 3a. Further, due to the presence of the tapered portion 5e, even when the valve body 2 comes into contact with the seal member 3 and the seal member 3 is bent, the angle of the bent portion is made gentler and the taper portion 5e is tapered. This can be partially supported by the portion 5e. Therefore, an effect that an excessive load on a specific part of the seal member 3 can be avoided is also obtained. At the same time, since the tapered portion 5e can contact the surface of the valve body 2 as a surface, the surface contact between the seal member 3 and the valve body 2 is supported, and the effect of making the sealing effect more reliable is also obtained. .

(Third embodiment)
In the second embodiment shown in FIG. 4, secondary effects such as reduction of the load on the seal member 3 and assistance of the sealing effect by the tapered surface can be obtained. The third embodiment shown in FIG. 5 is a form that enables adaptation of a large flow rate in the check valve in a form that is easier to process than the second embodiment. In addition, about the same component as 1st or 2nd embodiment mentioned above, this shall be shown in a figure using the same reference number, and detailed description here is abbreviate | omitted. In the embodiment shown in FIG. 5, a so-called step portion 5f having an inner diameter D6 larger than D5 is provided in the primary side opening 5d of the primary side vent 5c. Here, the relationship among the inner diameter D3 of the annular seal member 3, the inner diameter D5 of the primary side vent 5c, and the inner diameter D6 of the primary side opening 5d (that is, the step portion 5f) is D5 ≦ D3 as in the second embodiment. <D6 is desirable. That is, the inner diameter of the primary side opening 5d is set larger than the inner diameter of the primary side vent 5c other than the primary side opening 5d and smaller than the inner diameter of the seal opening 3a. By satisfying the above relationship and setting the axial depth d of the backflow prevention valve 1 at the step portion 5f to a value that can accommodate the amount of deflection of the seal member 3, the seal member 3 protrudes from the gas flow. It becomes possible to suppress the influence of the amount as much as possible.

(Fourth embodiment)
In the first to third embodiments, when it is attempted to further increase the flow rate of the gas passing through the check valve, the primary side vent 5c that is simply the upstream side vent and the second side vent that is the downstream side vent. It is also conceivable to enlarge the valve body 2 correspondingly by enlarging the secondary vent 7c. However, increasing the size of the valve body 2 makes it difficult to perform a suitable operation of the check valve at a slight differential pressure. The embodiment described below is a form that is constructed in view of the situation and that can cope with a larger flow rate and a slightly differential pressure operation. FIG. 6A is a diagram showing a schematic configuration of a cross section of the backflow prevention valve 1 according to the fourth embodiment, which is cut along a plane along the axial direction and including the shaft. Moreover, FIG. 6B has shown schematic structure of the state which looked at the cross section which cut | disconnected the said backflow prevention valve 1 along line 6B-6B in FIG. 6A from the arrow B direction. In addition, about the same component as 1st embodiment mentioned above etc., the same name and the same reference number are used fundamentally, and when there are a plurality of these components, in the detailed explanation, the first, second, etc. These are indicated by reference numerals for distinguishing reference numbers such as a, b, and c in the drawings, and detailed description thereof is omitted here.

  In the present embodiment, a configuration in which a plurality of valve bodies 2 (four in this embodiment) are arranged in a single case member 9 is shown. Corresponding to the valve bodies 2, the same number of primary side vents 5 c as the valve bodies 2 are arranged, and a set of guide members 13 for the individual valve bodies 2 is arranged for each of the valve bodies 2. In the present embodiment, the secondary side member 7 is provided with a single secondary side vent hole 7c having a large diameter. This form also has a stopper member 19 in order to prevent the valve body 2 from jumping out of the secondary vent 7c or out of a predetermined movement range. The stopper member is disposed downstream of the guide member 13 in the gas flow direction (the side where the secondary member 7 is disposed), and defines one end of the operating range of the valve body 2 defined by the guide member 13. To do. Here, the other end of the operating range is defined by the seal member 3. In the present embodiment, the support member 21 as a support column is protruded from the secondary side member 7, and the stopper member 19 is supported by the support member 21.

  The stopper member 19 is a flat plate-like member, and when the support member 21 is supported in parallel with the secondary side member 7, the valve body 2 cannot pass through the position facing each of the primary side vents 5a. The through hole 19a is positioned. The guide members 13 are supported by the stopper members 19 so as to extend toward the primary member 5. In this embodiment, the protruding amount h of the protruding portion 3b of the seal member 3 and the shape of the primary side opening 5d of the primary side vent 5a are the same as those of the first to third embodiments described above. desirable. In the present embodiment, the number of the valve bodies 2 is four, but the present embodiment is not limited to the number, and the number of valve bodies can be further increased to eight, sixteen, etc. In addition, the secondary vent 7c may not be formed of a single large-diameter through-hole, but may be provided with a plurality of small-diameter through-holes (vents).

(Fifth embodiment)
In the fourth embodiment described above, the valve bodies 2 are all equal components. Here, as shown in the verification of the cracking pressure, the pressure changes depending on the weight of the valve body 2. In the fifth embodiment, by using the weight of the valve body 2 as a parameter, the backflow prevention valve can be operated with a more differential pressure. The embodiment will be described with reference to FIGS. 7A and 7B. These drawings show the main components of the present embodiment in the same manner as in FIG. 3A showing the first embodiment. As described above, the same components are the same. Reference numerals and the like are used, and description thereof is omitted. FIG. 7A shows a state where the relationship of P1 <P2 is established between the upstream pressure P1 and the downstream pressure P2, and the backflow prevention valve 1 prevents the backflow of gas. FIG. 7B shows a state in which this relationship is reversed, and gas inflow partially starts to occur in the check valve 1.

  In the present embodiment, the first valve body 2a, the second valve body 2b, and the third valve body 2c, which are three valve bodies, are used. Wa, Wb, and It is assumed that the relationship of Wa> Wb> Wc is established between them. When the pressure on the upstream side increases and P1> P2, the cracking pressure applied from the gas to each valve body is small when the flow rate is small. Therefore, as shown in FIG. In the present embodiment, for example, only the third valve body 2 c is separated from the seat member 3. Only a flow rate corresponding to the cracking pressure can flow gas through the backflow prevention valve 1. That is, according to the weight of the valve body, the pressure acting on each valve body and the gravity are actuated sequentially from the balance, and the gas corresponding to the weight of the valve body can be supplied. In this way, by setting the weight of the valve body as appropriate, the valve body opens the primary-side vent 5c with good responsiveness to the differential pressure change, and can cope with a very small differential pressure change. It becomes possible. Moreover, at the time of a large flow rate, all the valve bodies open the primary side vent hole 5c, and it becomes possible to flow gas as in the fourth embodiment described above. Therefore, it is possible to operate in a wide gas flow range from a minute flow rate with a small differential pressure to a large flow rate.

(Sixth embodiment)
Further, as described above, the cracking pressure varies depending on the pressure receiving area of the valve body 2. Therefore, the same effect as that of the fifth embodiment can be obtained by changing the pressure receiving area, that is, the inner diameter of the primary side vent 5c. Such an embodiment will be described as a sixth embodiment with reference to FIGS. 8A and 8B. 8A and 8B are diagrams illustrating the embodiment in the same manner as in FIGS. 7A and 7B. In this embodiment, the three primary side vents of the upstream member 5 are the first primary side vent 5ca, the second primary side vent 5cb, and the third primary side vent 5cc. . Each inner diameter is D5a, D5b, and D5c, and satisfies the relationship D5a <D5b <D5c. Here, for example, when D5b = 30 mm and D5c = 32 mm,
When the inner diameter of the seal opening 3a of the seal member 3 (corresponding to the inner diameter of the primary vent) is φ30 mm, the cross-sectional area = 30 ² × π / 4 = 707 mm ² = 7.07 cm ²
The pressure-receiving surface is a spherical surface, but it can be assumed that the surface is flat.
7.07 cm ² × 100 Pa = 7.07 gf
If the weight of the valve body 2 is 2.7 g, the cracking pressure is
100 Pa / 7.07 gf × 2.7 gf = 38.19 Pa
That is, the valve opens at 38.19 Pa.
On the other hand, when the inner diameter of the seal opening 3b of the seal member 3 is φ32 mm, the cross-sectional area = 32 ² × π / 4 = 804 mm ² = 8.04 cm ²
The thrust of 8.04 gf at 100 Pa Since the weight of the valve body 2 is 2.7 g, the cracking pressure is
100 Pa / 8.04 gf × 2.7 gf = 33.58 Pa
Therefore, even with the same weight of the valve body 2, a difference in cracking pressure of about 4.6 Pa can be secured. That is, in accordance with the inner diameter of each primary side vent hole 5c (the inner diameter of the primary side opening 5d), the pressure acting on each valve body is actuated sequentially from the balance of gravity and gas corresponding to the inner diameter is supplied. It becomes possible to do. That is, the backflow prevention valve of this form includes a plurality of primary-side vents corresponding to a plurality of valve bodies, and the plurality of primary-side vents include those having different primary-side opening inner diameters. . In this way, by appropriately changing the inner diameter of the primary side vent, the valve body opens the primary side vent 5c with good responsiveness to the differential pressure change, and even for a very small differential pressure change. It becomes possible to respond. Moreover, at the time of a large flow rate, all the valve bodies open the primary side vent hole 5c, and it becomes possible to flow gas as in the fourth embodiment described above. Therefore, it is possible to operate in a wide gas flow range from a minute flow rate with a small differential pressure to a large flow rate.

  In the fourth and fifth embodiments described above, the case where the above-described sheet-like elastic member is used as the seal member 3 is shown, but the present embodiment is not limited to this. That is, since a corresponding cracking pressure can be set at each primary side vent, for example, an O-ring shaped member can be used as the seal member 3.

  As described above in the fourth to sixth embodiments, in the backflow prevention valve having a mode using a plurality of valve bodies, the operating pressure of each of the plurality of primary-side vents 5c is made different by making the operation pressure different. It is possible to cope with gas supply at a small flow rate due to a differential pressure to gas supply at a large flow rate with all the primary vents 5c opened. In the fourth to sixth embodiments, various application examples described in the first to third embodiments including the primary-side vent 5c can be applied. Furthermore, since no electrical control is required for the operation of these valves, it is possible to reduce the cost required for constructing the gas supply system.

  The backflow prevention valve in the present invention is applicable not only to the metal magnet-related manufacturing apparatus at the beginning but also to various uses in that low pressure gas is used without waste in purging or the like. For example, various applications such as flux-free soldering equipment and facilities that require constant filling with inert gas, or intake into areas where the concentration of airborne solvents needs to be reduced for explosion protection, etc. Application is conceivable.

1: backflow prevention valve 2, 2a, 2b, 2c: valve body, 3: seal member, 3a: seal opening, 3b: protruding portion, 5: primary side member, 5a: front surface, 5b: back surface, 5c, 5ca, 5cb, 5cc: Primary side vent, 5d: Primary side opening, 5e: Tapered portion, 5f: Stepped portion, 7: Secondary side member, 7a: Front surface, 7b: Back surface, 7c: Secondary side vent, 9: Case member, 9a: Primary side end surface, 9b: Secondary side end surface, 11: Fastening member, 12: Gas flow path, 13: Guide member, 15: Primary side airtight member, 17: Secondary side airtight member, 19 : Stopper member, 19a: Through hole, 21: Support member

Claims (3)

A backflow prevention valve disposed in a system in which gas flows from a primary side to a secondary side to prevent backflow of the gas from the secondary side to the primary side;
A gas flow path connected to the primary side and the secondary side through which the gas can flow;
Predetermined by a force that is arranged in the gas flow path and acts by a pressure difference between a primary side pressure acting from the gas existing on the primary side and a secondary side pressure acting from the gas existing on the secondary side A hollow valve body made of resin that is movable in the region;
A primary side member that constitutes one end of the gas flow path and has a primary side vent that is part of the gas flow path;
A seal member fixed to the primary side opening of the primary side vent and capable of closing the gas flow path by closely contacting the valve body;
There are a plurality of the valve bodies, and the primary vent and the seal member are arranged corresponding to each of the valve bodies,
The plurality of primary side vents corresponding to the plurality of valve bodies include primary side vents having different inner diameters of the primary side openings, and the pressure receiving areas of the respective valve bodies are made different depending on the different inner diameters. Backflow prevention valve.   An inside diameter of the seal opening fixed coaxially with the primary side opening in the seal member is smaller than an inside diameter of the primary side opening, and the seal member has a protruding portion that protrudes inside the primary side opening. The backflow prevention valve according to claim 1.   3. A valve body operating range restricting means that regulates a predetermined area, which is a movement range of the valve body, and promotes seating of the valve body at a predetermined position on the seal member. The check valve according to any one of the above.

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