Fluid control valve

Abstract

A fluid control valve has a first diaphragm (36) and a second diaphragm (38) disposed between a spool (26) and a body (12) with a diaphragm chamber (46) formed between the first and second diaphragms. The first diaphragm divides the valve chamber (44) from the diaphragm chamber and the second diaphragm divides the diaphragm chamber from a back pressure chamber (48). Further, the diaphragm chamber is in communication with an outlet port (18) and the valve chamber and back pressure chamber are in communication with an inlet port (16). The difference between the effective area (Sa) of the first diaphragm and the effective area (Sb) of the second diaphragm is equal to the passage area (Sc) in the valve seat (22).

Description

Technical Field

[0001] This invention relates to a fluid control valve capable of controlling the pressure or flow rate of a fluid. Background Technology

[0002] Previously, pressure regulating valves capable of adjusting secondary pressure have been known to be used. For example, Japanese Patent Application Publication No. 2007-148465 describes a pressure reducing valve having a pressure regulating shaft that moves the valve core closer to and further away from the valve seat. This pressure regulating shaft is connected to a pressure regulating diaphragm and reciprocates, and the pressure regulating diaphragm operates to find a balance point between the secondary pressure and the spring force of the pressure regulating spring. The secondary pressure acts as a back pressure on the pressure regulating shaft, and a lip gasket is disposed between the pressure regulating shaft and the cage.

[0003] Furthermore, Japanese Patent Application Publication No. 2001-099344 discloses a back pressure control valve comprising: a stem having a valve portion for opening and closing a valve seat; a first diaphragm portion disposed in a first chamber; and a second diaphragm portion disposed in a second chamber. In this back pressure control valve, the effective pressure-bearing area of ​​the second diaphragm portion is equal to the effective area of ​​the valve seat, and the back pressure control valve is configured such that the stem portion does not move with changes in the load on the secondary side. Summary of the Invention

[0004] However, the pressure reducing valve in Japanese Patent Application Publication No. 2007-148465 does not take into account changes in primary pressure. Furthermore, problems such as dust accumulation can occur due to resistance generated by the sliding of the pressure regulating shaft and the lip gasket. The back pressure control valve in Japanese Patent Application Publication No. 2001-099344 also does not take into account changes in primary pressure.

[0005] The purpose of this invention is to solve the above-mentioned technical problems.

[0006] The fluid control valve of the present invention includes a body having an input port and an output port, and a valve core capable of abutting against a valve seat of the body. A first diaphragm and a second diaphragm are disposed between the valve core and the body. A diaphragm chamber is formed between the first diaphragm and the second diaphragm. The first diaphragm divides the valve chamber and the diaphragm chamber, and the second diaphragm divides the diaphragm chamber and the back pressure chamber. The diaphragm chamber communicates with the output port, and the valve chamber and the back pressure chamber communicate with the input port. The difference between the effective pressure-bearing area of ​​the first diaphragm and the effective pressure-bearing area of ​​the second diaphragm is equal to the passage area in the valve seat. Instead of communicating the diaphragm chamber with the output port and communicating the valve chamber and the back pressure chamber with the input port, it is also possible to communicate the diaphragm chamber with the input port and communicate the valve chamber and the back pressure chamber with the output port.

[0007] Furthermore, the fluid control valve of the present invention includes a body having an input port and an output port, and a valve core capable of abutting against a valve seat of the body. A first diaphragm and a second diaphragm are disposed between the valve core and the body. A diaphragm chamber is formed between the first diaphragm and the second diaphragm. The first diaphragm divides the valve chamber and the diaphragm chamber, and the second diaphragm divides the diaphragm chamber and the back pressure chamber. The diaphragm chamber communicates with the output port, and the valve chamber and the back pressure chamber communicate with the input port. One end of the valve core extends from the back pressure chamber toward the chamber disposed outside the body and communicating with the output port. The difference between the effective pressure-bearing area of ​​the first diaphragm and the effective pressure-bearing area of ​​the second diaphragm is equal to the difference between the passage area in the valve seat and the cross-sectional area of ​​one end of the valve core.

[0008] According to the fluid control valves described above, even if one or both of the primary and secondary pressures change, the force that would cause instability in the operation will not be applied to the valve core, thus maintaining stable control or operation.

[0009] The fluid control valve of the present invention has a predetermined relationship between the effective pressure-bearing area of ​​the first diaphragm, the effective pressure-bearing area of ​​the second diaphragm, and the passage area in the valve seat. Therefore, stable control or operation is maintained even if one or both of the primary and secondary pressures change.

[0010] The above-described objectives, features, and advantages can be easily understood from the following description of the embodiments, which are illustrated with reference to the accompanying drawings. Attached Figure Description

[0011] Figure 1 This is a cross-sectional view of the fluid control valve according to the first embodiment of the present invention.

[0012] Figure 2 yes Figure 1 A partial enlarged view of the fluid control valve.

[0013] Figure 3 This is a cross-sectional view of the fluid control valve according to the second embodiment of the present invention.

[0014] Figure 4 yes Figure 3 A partial enlarged view of the fluid control valve.

[0015] Figure 5 This is a schematic cross-sectional view of the fluid control valve according to the third embodiment of the present invention.

[0016] Figure 6 yes Figure 5 An enlarged view of the valve assembly of a fluid control valve. Detailed Implementation

[0017] In the following description, when using terms related to up and down directions, it refers to the directions shown in the attached drawings for convenience, and does not limit the actual configuration of each component, etc.

[0018] (First Implementation)

[0019] Reference Figure 1 and Figure 2 The fluid control valve 10 according to the first embodiment of the present invention will be described. The fluid control valve 10 is a component that functions as a pressure reducing valve (pressure regulating valve). The fluid control valve 10 has a body 12, a valve cover 52, and a balancing mechanism and a pressure regulating mechanism assembled inside the body 12 and the valve cover 52. The balancing mechanism is composed of a valve core 26, a first diaphragm 36, a second diaphragm 38, etc. The pressure regulating mechanism is composed of a pressure regulating shaft 54, a pressure regulating spring 58, a pressure regulating diaphragm 60, etc. The body 12 is composed of a body main body 14 and a cover 24, and the valve core 26 is composed of a main valve core 28, an auxiliary valve core 30, and a valve stem 34.

[0020] The torso body 14 has an input port 16 and an output port 18 arranged opposite each other on the same axis. A cover 24 is installed on the lower part of the torso body 14. The torso body 14 has a valve core receiving chamber 20 enclosed by the cover 24. The upper part of the valve core receiving chamber 20 is connected to the input port 16 via an input passage 14a and to the output port 18 via an output passage 14b. The torso body 14 has a valve seat 22 on the part of the valve core receiving chamber 20 facing the output passage 14b.

[0021] The cover 24 has an upwardly protruding cylindrical fitting portion 24a that fits into a fitting hole 14c in the lower part of the torso body 14. The upper end of the fitting portion 24a of the cover 24 is opposite to the stepped portion 14d of the torso body 14 that connects to the fitting hole 14c, separated by a predetermined gap. The outer periphery 36b of the first diaphragm 36, the second gasket 42, and the outer periphery 38b of the second diaphragm 38 (described later) are disposed in this gap. The bottom of the cover 24 has a cylindrical guide portion 24d protruding toward the valve core receiving chamber 20.

[0022] The main valve core 28 is disposed within the valve core receiving chamber 20, and a sealing member 32 abutting against the valve seat 22 is provided on the upper end face of the main valve core 28. The main valve core 28 has an upper large-diameter portion 28a and a lower small-diameter portion 28c. The large-diameter portion 28a is for mounting the sealing member 32, and the small-diameter portion 28c is connected to the large-diameter portion 28a via a stepped portion 28b. The valve stem 34 and the auxiliary valve core 30 are connected to the main valve core 28. Specifically, the lower part of the valve stem 34 is inserted into the valve stem hole 28g provided in the large-diameter portion 28a of the main valve core 28, and the two are connected by pressing or other means. In addition, the small-diameter portion 28c of the main valve core 28 is inserted into the inner side of the auxiliary valve core 30, and the two are connected by screwing or other means.

[0023] The valve stem 34 is inserted into the valve core insertion hole 14e provided in the main body 14. The auxiliary valve core 30 has a large-diameter portion 30a at the top and a small-diameter portion 30c connected to the large-diameter portion 30a via a stepped portion 30b. The auxiliary valve core 30 is inserted at its small-diameter portion 30c and supported inside the guide portion 24d of the cover 24. Therefore, the main valve core 28, the auxiliary valve core 30, and the valve stem 34 are integrated and supported to be displaceable in their axial direction (vertical direction). The upper end of the auxiliary valve core 30 is opposite to the stepped portion 28b of the main valve core 28 with a predetermined gap. The inner peripheral portion 36a of the first diaphragm 36 (described later), the first gasket 40, and the inner peripheral portion 38a of the second diaphragm 38 (described later) are arranged in this gap. In addition, the fluid in the back pressure chamber 48 (described later) flows around the inside of the guide portion 24d of the cover 24.

[0024] A valve spring 50 is arranged between the stepped portion 30b of the auxiliary valve core 30 and the bottom surface of the cover 24, wound around the outer periphery of the guide portion 24d of the cover 24. The valve spring 50 is a coil spring and applies an upward force to the auxiliary valve core 30. The main valve core 28, which is integral with the auxiliary valve core 30, is subjected to the force of the valve spring 50 and is forced in the direction of abutting against the valve seat 22.

[0025] Within the valve core housing 20, a first diaphragm 36 and a second diaphragm 38 are disposed between the valve core 26 and the body 12. These diaphragms are formed of an elastic material in a thin film and are annular. An annular first gasket 40 is disposed between the inner peripheral portion 36a of the first diaphragm 36 and the inner peripheral portion 38a of the second diaphragm 38. An annular second gasket 42 is disposed between the outer peripheral portion 36b of the first diaphragm 36 and the outer peripheral portion 38b of the second diaphragm 38.

[0026] The first diaphragm 36, the first gasket 40, and the second diaphragm 38 are inserted through the small-diameter portion 28c of the main valve core 28. The inner peripheral portion 36a of the first diaphragm 36 is sandwiched between the stepped portion 28b of the main valve core 28 and the upper surface of the first gasket 40. The inner peripheral portion 38a of the second diaphragm 38 is sandwiched between the upper end of the auxiliary valve core 30 and the lower surface of the first gasket 40. The outer peripheral portion 36b of the first diaphragm 36 is sandwiched between the stepped portion 14d of the body 14 and the upper surface of the second gasket 42. The outer peripheral portion 38b of the second diaphragm 38 is sandwiched between the upper end of the fitting portion 24a of the cover 24 and the lower surface of the second gasket 42.

[0027] When the valve core 26 moves vertically, the inner peripheral portion 36a of the first diaphragm 36 moves together with the valve core 26, and the thin film portion 36c between the inner peripheral portion 36a and the outer peripheral portion 36b of the first diaphragm 36 deforms. Similarly, when the valve core 26 moves vertically, the inner peripheral portion 38a of the second diaphragm 38 moves together with the valve core 26, and the thin film portion 38c between the inner peripheral portion 38a and the outer peripheral portion 38b of the second diaphragm 38 deforms.

[0028] The second gasket 42 has a stepped portion 42a on its inner periphery. The inner diameter of the second gasket 42 is larger near the upper surface that contacts the first diaphragm 36 than near the lower surface that contacts the second diaphragm 38. Therefore, the area of ​​the thin film portion 36c, which is the deformation region of the first diaphragm 36, is larger than the area of ​​the thin film portion 38c, which is the deformation region of the second diaphragm 38. That is, the effective pressure-bearing area of ​​the first diaphragm 36 is larger than the effective pressure-bearing area of ​​the second diaphragm 38. The technical significance of this difference in effective pressure-bearing area will be described later.

[0029] The valve core receiving chamber 20 is divided into a valve chamber 44 above the first diaphragm 36, a diaphragm chamber 46 between the first diaphragm 36 and the second diaphragm 38, and a back pressure chamber 48 below the second diaphragm 38. The valve chamber 44 is connected to the input port 16 via the input passage 14a. Furthermore, the term "valve chamber" as used in this invention refers to the chamber near the valve seat 22, which is part of the passage for fluid to flow from the input port 16 to the output port 18.

[0030] The first gasket 40 has a plurality of radially penetrating bores 40a. One end of each bore 40a opens into the diaphragm chamber 46. The main valve core 28 has: an annular groove 28d surrounding the outer circumferential surface in a small diameter portion 28c; a plurality of bores 28e connected at one end to the annular groove 28d; and a shaft bore 28f connected to the other end of each bore 28e. The shaft bore 28f extends along the axial direction of the main valve core 28 to the valve stem bore 28g. The valve stem 34 has a bore 34a and a shaft bore 34b. The bore 34a is radially penetrating and opens at both ends into the output passage 14b. The shaft bore 34b communicates with the bore 34a and extends to the lower end of the valve stem 34.

[0031] The other end of the bore 40a of the first gasket 40 is connected to the annular groove 28d of the main valve core 28. The upper end of the shaft bore 28f of the main valve core 28 is opposite to the lower end of the shaft bore 34b of the valve stem 34. These bores 40a of the first gasket 40, the annular groove 28d of the main valve core 28, the bore 28e of the main valve core 28, the shaft bore 28f of the main valve core 28, the shaft bore 34b of the valve stem 34, and the bore 34a of the valve stem 34 constitute a secondary pressure introduction passage that introduces the pressure of the fluid from the output port 18 into the diaphragm chamber 46. That is, the diaphragm chamber 46 is connected to the output port 18 via the secondary pressure introduction passage and the output passage 14b.

[0032] The fitting portion 24a of the cover 24 has an annular groove 24b surrounding the outer peripheral surface of the fitting portion 24a and a plurality of transverse holes 24c, one end of which is connected to the annular groove 24b and the other end of which opens into the back pressure chamber 48. The torso body 14 has a connecting passage 14f, one end of which is connected to the annular groove 24b of the cover 24 and the other end of which is connected to the input port 16. The transverse holes 24c of the cover 24, the annular groove 24b of the cover 24, and the connecting passage 14f of the torso body 14 constitute a primary pressure introduction passage for introducing the pressure of the fluid from the input port 16 into the back pressure chamber 48. That is, the back pressure chamber 48 is connected to the input port 16 via the primary pressure introduction passage. In addition, the primary pressure introduction passage is kept airtight relative to the outside by a seal 51 disposed between the torso body 14 and the cover 24.

[0033] A cylindrical valve cover 52 is mounted on the upper end of the body 14 and extends upward from the body 14. An annular pressure regulating diaphragm 60, integrally formed from an elastic material into a thin film, is disposed between the body 14 and the valve cover 52. The outer periphery 60b of the pressure regulating diaphragm 60 is sandwiched between the upper surface of the body 14 and the lower surface of the valve cover 52. A base retainer 64 is inserted through the center of the pressure regulating diaphragm 60, and a disc-shaped retaining plate 66 is mounted on the base retainer 64. The inner periphery 60a of the pressure regulating diaphragm 60 is sandwiched between the base retainer 64 and the retaining plate 66.

[0034] The base retainer 64 has a recess 64a at its lower center. The upper end of the valve stem 34, protruding from the body 14, is inserted into this recess 64a. The upper end of the valve stem 34 abuts against the base retainer 64 via a seal 65 mounted in the recess 64a. When the base retainer 64 moves vertically, the area between the inner circumference 60a and the outer circumference 60b of the pressure regulating diaphragm 60 deforms.

[0035] A pressure regulating diaphragm chamber 62 is disposed below the pressure regulating diaphragm 60. The pressure regulating diaphragm chamber 62 is connected to the output passage 14b via a bypass passage 14g of the body 14. That is, the pressure regulating diaphragm chamber 62 is connected to the output port 18 via the bypass passage 14g and the output passage 14b. The pressure regulating diaphragm chamber 62 is kept airtight relative to the interior of the valve cover 52 that extends above the pressure regulating diaphragm 60 by the aforementioned seal 65 mounted on the base holder 64.

[0036] An adjusting shaft 54, an adjusting spring 58, and an adjusting spring seat 56 are disposed inside the valve cover 52. The adjusting shaft 54 ​​has a flange 54a near its axial center, and a threaded portion 54b below the flange 54a. The upper end of the adjusting shaft 54 ​​protrudes upward from the valve cover 52 and is connected to a handle 68 that covers the upper part of the valve cover 52. Specifically, the bottom of the bottom of the bottom cylindrical handle 68 has a cylindrical protrusion 68a, and the upper end of the adjusting shaft 54 ​​is fixed to the cylindrical protrusion 68a by means of pressing or the like.

[0037] The pressure regulating spring seat 56 is disposed below the flange portion 54a of the pressure regulating shaft 54. The pressure regulating spring seat 56 consists of an annular plate portion 56a and a cylindrical portion 56b. The plate portion 56a abuts against the flange portion 54a of the pressure regulating shaft 54, and the cylindrical portion 56b extends axially from the inner periphery of the plate portion 56a. The cylindrical portion 56b of the pressure regulating spring seat 56 is screwed into the threaded portion 54b of the pressure regulating shaft 54. The outer periphery of the plate portion 56a of the pressure regulating spring seat 56 is connected to the valve cover 52 via an anti-rotation member such as a spline. Therefore, the pressure regulating spring seat 56 is supported on the valve cover 52 in a manner that restricts rotation about its axis and allows displacement in the axial direction (vertical direction).

[0038] The pressure regulating spring 58 is a helical spring and is positioned between the pressure regulating spring seat 56 and the retaining plate 66. The spring constant of the pressure regulating spring 58 is greater than that of the valve spring 50. When the pressure regulating shaft 54 ​​is rotated by the operator rotating the handle 68, the pressure regulating spring seat 56 is displaced in the vertical direction, and the retaining plate 66 and the base retainer 64 are also displaced in the same direction.

[0039] Here, the force in the vertical direction based on the pressure of the fluid acting on the valve core 26 is examined. The pressure at the input port 16, i.e., the primary pressure, is defined as P1, and the pressure at the output port 18, i.e., the secondary pressure, is defined as P2. Furthermore, the effective pressure-bearing area of ​​the first diaphragm 36 is defined as Sa, the effective pressure-bearing area of ​​the second diaphragm 38 is defined as Sb, and the circular passage area in the valve seat 22 (the seat area of ​​the valve seat 22) is defined as Sc. Additionally, the cross-sectional area of ​​the small-diameter portion 28c of the main valve core 28, which supports the inner peripheral portion 36a of the first diaphragm 36 and the inner peripheral portion 38a of the second diaphragm 38, is defined as S1.

[0040] Since valve chamber 44 is connected to input port 16 via input passage 14a, the pressure of the fluid in valve chamber 44 is equal to the primary pressure P1. Since diaphragm chamber 46 is connected to output port 18 via secondary pressure inlet passage and output passage 14b, the pressure of the fluid in diaphragm chamber 46 is equal to the secondary pressure P2. Since back pressure chamber 48 is connected to input port 16 via primary pressure inlet passage, the pressure of the fluid in back pressure chamber 48 is equal to the primary pressure P1.

[0041] The first diaphragm 36 bears the pressure of the fluid in the valve chamber 44 and the pressure of the fluid in the diaphragm chamber 46. Therefore, the valve core 26 connected to the first diaphragm 36 bears a downward force P1×(Sa-Sc) from the pressure of the valve chamber 44 and an upward force P2×(Sa-S1) from the pressure of the fluid in the diaphragm chamber 46.

[0042] The second diaphragm 38 bears the pressure of the fluid in the diaphragm chamber 46 and the pressure of the fluid in the back pressure chamber 48. Therefore, the valve core 26 connected to the second diaphragm 38 bears a downward force P2×(Sb-S1) from the pressure in the diaphragm chamber 46, and an upward force P1×Sb from the pressure in the back pressure chamber 48. In addition, the valve core 26 bears a downward force P2×Sc from the upper surface of the main valve core 28 facing the output passage 14b.

[0043] The force acting on valve core 26 due to fluid pressure is as described above. If the upward force is set to positive and the downward force is set to negative, and all these forces are added together and rearranged, the result is (P1-P2)×(-Sa+Sb+Sc).

[0044] To ensure that the sum of the forces acting on the valve core 26 due to the pressure from the aforementioned fluid (hereinafter referred to as the "sum of valve core forces") is substantially zero, Sa - Sb = Sc. That is, the effective pressure-bearing area Sa of the first diaphragm 36 and the effective pressure-bearing area Sb of the second diaphragm 38 are set such that the difference between the effective pressure-bearing area Sa of the first diaphragm 36 and the effective pressure-bearing area Sb of the second diaphragm 38 is equal to the passage area Sc in the valve seat 22. By setting it in this way, the sum of valve core forces can be made substantially zero regardless of the magnitudes of the primary pressure P1 and the secondary pressure P2. Therefore, even if one or both of the primary pressure P1 and the secondary pressure P2 change, forces that cause instability in the operation are not applied to the valve core 26.

[0045] Next, the setting of the secondary pressure via handle 68 and the pressure regulating function of the pressure regulating mechanism will be explained. Since the pressure regulating diaphragm chamber 62 is connected to the output port 18 via the bypass passage 14g and the output passage 14b, the pressure of the fluid in the pressure regulating diaphragm chamber 62 is equal to the secondary pressure P2. The pressure regulating diaphragm 60 bears the pressure of the pressure regulating diaphragm chamber 62 and applies an upward force to the base holder 64 supporting the inner periphery 60a of the pressure regulating diaphragm 60.

[0046] The pressure regulating spring 58 applies a downward force to the base holder 64. The base holder 64 abuts against the valve stem 34, and the valve spring 50 applies an upward force to the base holder 64 via the valve core 26. The downward force generated by these pressure regulating springs 58 and the upward force generated by the valve spring 50 are determined by the position of the base holder 64. The value obtained by subtracting the force of the valve spring 50 from the force applied by the pressure regulating spring 58 can be adjusted by rotating the handle 68. The lower the base holder 64 is positioned, the larger the secondary pressure can be set.

[0047] When the fluid pressure device (not shown) connected to the output port 18 is in a rest or stopped state, and no pressurized fluid is supplied to the input port 16, the main valve core 28 moves significantly away from the valve seat 22. Operation of the fluid pressure device begins from this state. When fluid is supplied to the input port 16 from a fluid supply source (not shown), the fluid flows through the space between the valve seat 22 and the main valve core 28 to the output port 18. As a result, the secondary pressure gradually increases, and the pressure in the pressure regulating diaphragm chamber 62 also gradually increases.

[0048] As the pressure in the pressure regulating diaphragm chamber 62 increases, the base holder 64 moves upward, and the flow rate of fluid from the input port 16 to the output port 18 decreases. Then, when the secondary pressure reaches the pressure set by the handle 68, the main valve core 28 abuts against the valve seat 22 to prevent fluid from flowing towards the output port 18, and the displacement of the base holder 64 also stops. The pressure regulating mechanism then continues to regulate the pressure to maintain the secondary pressure at the pressure set by the handle 68.

[0049] As described above, even if one or both of the primary pressure P1 and secondary pressure P2 change, the total force of the valve core remains substantially zero. Therefore, the balance of forces required to maintain the desired secondary pressure set by the operator via handle 68 is not disrupted. Thus, stable pressure regulation is achieved, and the pressure at output port 18 is maintained at the desired secondary pressure.

[0050] According to this embodiment, the difference between the effective pressure-bearing area Sa of the first diaphragm 36 and the effective pressure-bearing area Sb of the second diaphragm 38 is equal to the passage area Sc in the valve seat 22. Therefore, even if the primary or secondary pressure varies, a stable pressure regulation operation can be performed to obtain the desired secondary pressure. Furthermore, in the absence of a sliding portion requiring a seal, the valve core 26 is supported so that it can move along the axial direction. Therefore, in addition to the operation not becoming unstable due to sliding resistance, dust will not be generated due to sliding.

[0051] In this embodiment, the diaphragm chamber 46 is connected to the output port 18, and the valve chamber 44 and the back pressure chamber 48 are connected to the input port 16. Alternatively, the diaphragm chamber 46 can be connected to the input port 16, and the valve chamber 44 and the back pressure chamber 48 can be connected to the output port 18. This is because, in this case, the sum of the forces acting on the valve core 26 replaces the values ​​of P1 and P2 in the above formula (P1-P2)×(-Sa+Sb+Sc), while the condition for making this value zero (Sa-Sb=Sc) remains unchanged.

[0052] (Second Implementation)

[0053] Next, refer to Figure 3 and Figure 4 The fluid control valve 80 according to the second embodiment of the present invention will be described. The fluid control valve 80 functions as a pressure reducing valve (pressure regulating valve). The fluid control valve 80 includes a body 82, a valve cover 52, and a balancing mechanism and a pressure regulating mechanism assembled inside the body 82 and the valve cover 52. The balancing mechanism is composed of a valve core 100, a first diaphragm 106, a second diaphragm 108, etc. The body 82 is composed of a body main body 84, a first cover 96, and a second cover 98, and the valve core 100 is composed of a main valve core 102 and an auxiliary valve core 104. In addition, the same reference numerals are used for structures that are the same as or equivalent to those of the fluid control valve 10 of the first embodiment, and detailed descriptions are omitted.

[0054] The torso body 84 has an input port 86 and an output port 88 arranged opposite each other on the same axis. A first cover 96 is installed at the lower part of the torso body 84, and a second cover 98 is installed at the upper part of the torso body 84. The torso body 84 has a valve core receiving chamber 90 inside, which houses the valve core 100. The valve core receiving chamber 90 is connected to the input port 86 via an input passage 84a, and to the output port 88 via an output passage 84b.

[0055] The main body 84 has a horizontal wall portion 92 with an opening 92a through which the main valve core 102 is inserted. The horizontal wall portion 92 protrudes into the valve core receiving chamber 90, and the output chamber 94, which is connected to the output passage 84b, is located below the horizontal wall portion 92. A valve seat 92b is provided on the lower surface of the horizontal wall portion 92 near the opening 92a. A first cover 96 has a cylindrical guide portion 96a protruding toward the output chamber 94, and the first cover 96 is fitted into the lower part of the main body 84. Fluid in the output chamber 94 flows into the inside of the guide portion 96a through a through hole 96b provided in the guide portion 96a of the first cover 96.

[0056] The second cover 98 has a downwardly protruding cylindrical fitting portion 98a that fits into a fitting hole 84c on the upper part of the torso body 84. The lower end of the fitting portion 98a of the second cover 98 is spaced apart from the stepped portion 84d of the torso body 84 that connects to the fitting hole 84c by a predetermined gap. The outer peripheral portion 106b of the first diaphragm 106, the second gasket 112, and the outer peripheral portion 108b of the second diaphragm 108 are disposed in this gap.

[0057] The main valve core 102 has a first flange portion 102a located below the horizontal wall portion 92 of the main body 84 and a second flange portion 102b located above the horizontal wall portion 92. A sealing member 103 abutting against the valve seat 92b is mounted on the upper surface of the first flange portion 102a. The portion of the main valve core 102 lower than the first flange portion 102a is inserted through and supported on the inner side of the guide portion 96a of the first cover 96. A valve spring 120 is arranged between the lower surface of the first flange portion 102a and the bottom surface of the first cover 96, wound around the outside of the guide portion 96a of the first cover 96. The valve spring 120 is a coil spring and applies an upward force to the main valve core 102.

[0058] The auxiliary valve core 104 is connected to the main valve core 102. Specifically, the auxiliary valve core 104 consists of a large-diameter portion 104a having a connecting hole 104b and a small-diameter portion 104c extending upward from the large-diameter portion 104a. The upper part of the main valve core 102 is inserted into the connecting hole 104b of the auxiliary valve core 104, and the two are connected by means of screwing or the like. The small-diameter portion 104c of the auxiliary valve core 104 is inserted into the valve core insertion hole 84e of the second cover 98, and the small-diameter portion 104c extends into the pressure regulating diaphragm chamber 62 disposed above the second cover 98.

[0059] The upper surface of the second flange portion 102b of the main valve core 102 is positioned opposite the lower end of the large-diameter portion 104a of the auxiliary valve core 104, separated by a predetermined gap. Within this gap are the inner peripheral portion 106a of the first diaphragm 106 (described later), the first gasket 110, and the inner peripheral portion 108a of the second diaphragm 108. The main valve core 102 and the auxiliary valve core 104 are integral and supported to allow displacement along their axial direction (vertical direction).

[0060] Within the valve core housing 90, a first diaphragm 106 and a second diaphragm 108 are disposed between the valve core 100 and the body 82. These diaphragms are formed of an elastic material in a thin film and are annular. An annular first gasket 110 is disposed between the inner peripheral portion 106a of the first diaphragm 106 and the inner peripheral portion 108a of the second diaphragm 108. An annular second gasket 112 is disposed between the outer peripheral portion 106b of the first diaphragm 106 and the outer peripheral portion 108b of the second diaphragm 108.

[0061] The first diaphragm 106, the first gasket 110, and the second diaphragm 108 are inserted through the portion of the main valve core 102 above the second flange 102b. The inner peripheral portion 106a of the first diaphragm 106 is sandwiched between the second flange 102b of the main valve core 102 and the lower surface of the first gasket 110. The inner peripheral portion 108a of the second diaphragm 108 is sandwiched between the upper surface of the first gasket 110 and the lower end of the auxiliary valve core 104. The outer peripheral portion 106b of the first diaphragm 106 is sandwiched between the stepped portion 84d of the body 84 and the lower surface of the second gasket 112. The outer peripheral portion 108b of the second diaphragm 108 is sandwiched between the upper surface of the second gasket 112 and the lower end of the fitting portion 98a of the second cover 98.

[0062] When the valve core 100 moves vertically, the inner peripheral portion 106a of the first diaphragm 106 moves together with the valve core 100, and the thin film portion 106c between the inner peripheral portion 106a and the outer peripheral portion 106b of the first diaphragm 106 deforms. Similarly, when the valve core 100 moves vertically, the inner peripheral portion 108a of the second diaphragm 108 moves together with the valve core 100, and the thin film portion 108c between the inner peripheral portion 108a and the outer peripheral portion 108b of the second diaphragm 108 deforms.

[0063] The second gasket 112 has a stepped portion 112a on its inner periphery. The inner diameter of the second gasket 112 is larger near the lower surface that contacts the first diaphragm 106 than near the upper surface that contacts the second diaphragm 108. Therefore, the area of ​​the thin film portion 106c, which is the deformation region of the first diaphragm 106, is larger than the area of ​​the thin film portion 108c, which is the deformation region of the second diaphragm 108. That is, the effective pressure-bearing area of ​​the first diaphragm 106 is larger than the effective pressure-bearing area of ​​the second diaphragm 108. The technical significance of this difference in effective pressure-bearing area will be described later.

[0064] The valve core receiving chamber 90 is divided above the horizontal wall 92 of the main body 84 into a valve chamber 114 below the first diaphragm 106, a diaphragm chamber 116 between the first diaphragm 106 and the second diaphragm 108, and a back pressure chamber 118 above the second diaphragm 108. The valve chamber 114 is connected to the input port 86 via the input passage 84a.

[0065] The first gasket 110 has a plurality of radially penetrating bores 110a. One end of each bore 110a opens into the diaphragm chamber 116. The main valve core 102 has: an annular groove 102c surrounding the outer peripheral surface at a position above the second flange portion 102b; a plurality of bores 102d connected at one end to the annular groove 102c; and a shaft bore 102e connected to the other end of the bores 102d. The shaft bore 102e extends along the axial direction of the main valve core 102 to the lower end of the main valve core 102. The other end of the bore 110a of the first gasket 110 is connected to the annular groove 102c of the main valve core 102.

[0066] The bore 110a of the first gasket 110, the annular groove 102c of the main valve core 102, the bore 102d of the main valve core 102, and the shaft bore 102e of the main valve core 102 constitute a secondary pressure introduction passage that introduces the pressure of the fluid from the output port 88 into the diaphragm chamber 116. That is, the diaphragm chamber 116 is connected to the output port 88 via the secondary pressure introduction passage, the output chamber 94, and the output passage 84b.

[0067] The fitting portion 98a of the second cover 98 has an annular groove 98b surrounding the outer peripheral surface of the fitting portion 98a and a plurality of transverse holes 98c, one end of which is connected to the annular groove 98b and the other end of which opens into the back pressure chamber 118. Additionally, the torso body 84 has a connection passage 84f, one end of which is connected to the annular groove 98b of the second cover 98 and the other end of which is connected to the input port 86. These transverse holes 98c of the second cover 98, the annular groove 98b of the second cover 98, and the connection passage 84f of the torso body 84 constitute a primary pressure introduction passage for introducing the pressure of the fluid from the input port 86 into the back pressure chamber 118. That is, the back pressure chamber 118 is connected to the input port 86 via the primary pressure introduction passage.

[0068] Here, the force in the vertical direction based on the pressure of the fluid acting on the valve core 100 is examined. The pressure at the input port 86, i.e., the primary pressure, is defined as P1, and the pressure at the output port 88, i.e., the secondary pressure, is defined as P2. Furthermore, the effective pressure-bearing area of ​​the first diaphragm 106 is defined as Sa, the effective pressure-bearing area of ​​the second diaphragm 108 is defined as Sb, and the circular passage area in the valve seat 92b (the seat area of ​​the valve seat 92b) is defined as Sc. Additionally, the cross-sectional area of ​​the main valve core 102 supporting the inner circumference 106a of the first diaphragm 106 and the inner circumference 108a of the second diaphragm 108 is defined as S1. Moreover, the cross-sectional area of ​​the valve core insertion hole 84e of the second cover 98 (the cross-sectional area of ​​the small-diameter portion 104c of the additional valve core 104, which is the cross-sectional area of ​​one end of the valve core 100) is defined as S2.

[0069] Since valve chamber 114 is connected to input port 86 via input passage 84a, the pressure of the fluid in valve chamber 114 is equal to the primary pressure P1. Since diaphragm chamber 116 is connected to output port 88 via secondary pressure inlet passage, output chamber 94, and output passage 84b, the pressure of the fluid in diaphragm chamber 116 is equal to the secondary pressure P2. Since back pressure chamber 118 is connected to input port 86 via primary pressure inlet passage, the pressure of the fluid in back pressure chamber 118 is equal to the primary pressure P1. Since pressure regulating diaphragm chamber 62 is connected to output port 88 via bypass passage 83 provided in the torso body 84 and the second cover 98, the pressure of the fluid in pressure regulating diaphragm chamber 62 is equal to the secondary pressure P2.

[0070] The first diaphragm 106 bears the pressure of the fluid in the valve chamber 114 and the pressure of the fluid in the diaphragm chamber 116. Therefore, the valve core 100 connected to the first diaphragm 106 bears an upward force P1×(Sa-Sc) from the pressure of the valve chamber 114 and a downward force P2×(Sa-S1) from the pressure of the fluid in the diaphragm chamber 116.

[0071] The second diaphragm 108 bears the pressure of the fluid in the diaphragm chamber 116 and the pressure of the fluid in the back pressure chamber 118. Therefore, the valve core 100 connected to the second diaphragm 108 bears an upward force P2×(Sb-S1) from the pressure in the diaphragm chamber 116 and a downward force P1×(Sb-S2) from the pressure in the back pressure chamber 118. In addition, since the lower end of the main valve core 102 faces the output chamber 94, the valve core 100 bears an upward force P2×Sc. Furthermore, since the upper end of the auxiliary valve core 104 faces the pressure regulating diaphragm chamber 62, the valve core 100 bears a downward force P2×S2.

[0072] The force acting on the valve core 100 due to the pressure of the fluid is as described above. If the upward force is set to positive and the downward force is set to negative, and all these forces are added together and rearranged, the result is (P1-P2)×(Sa-Sb-Sc+S2).

[0073] To ensure that the sum of the forces acting on the valve core 100 due to the pressure from the aforementioned fluid (hereinafter referred to as the "sum of valve core forces") is substantially zero, Sa - Sb = Sc - S2. That is, the effective pressure-bearing area Sa of the first diaphragm 106 and the effective pressure-bearing area Sb of the second diaphragm 108 are set such that the difference between the effective pressure-bearing area Sa of the first diaphragm 106 and the effective pressure-bearing area Sb of the second diaphragm 108 is equal to the difference between the passage area Sc in the valve seat 92b and the cross-sectional area S2 of the additional valve core 104 protruding into the pressure regulating diaphragm chamber 62. By setting it in this way, the sum of valve core forces can be made substantially zero regardless of the magnitudes of the primary pressure P1 and the secondary pressure P2. Therefore, even if one or both of the primary pressure P1 and the secondary pressure P2 change, forces that cause instability in the operation are not applied to the valve core 100.

[0074] (Third Implementation)

[0075] Next, refer to Figure 5 and Figure 6The fluid control valve 130 according to the third embodiment of the present invention will be described. The fluid control valve 130 functions as a flow control valve. The fluid control valve 130 is composed of a valve assembly 132, an actuator assembly 134, a sensor assembly 150, a control assembly 158, an inlet assembly 162, and an outlet assembly 164. In addition, the same reference numerals are used to denote structures that are the same as or equivalent to those of the fluid control valve 10 of the first embodiment, and detailed descriptions are omitted.

[0076] The valve assembly 132 has a balancing mechanism, which consists of a valve core 26, a first diaphragm 36, a second diaphragm 38, etc., which are assembled inside the body 12. The body 12 consists of a body main 14 and a cover 24, and the valve core 26 consists of a main valve core 28, an auxiliary valve core 30, and a valve stem 34.

[0077] The torso body 14 has an input port 16 and an output port 18 arranged opposite each other on the same axis. A cover 24 is installed on the lower part of the torso body 14. The torso body 14 has a valve core receiving chamber 20 enclosed by the cover 24. The upper part of the valve core receiving chamber 20 is connected to the input port 16 via an input passage 14a and to the output port 18 via an output passage 14b.

[0078] The upper end of the valve stem 34 is located within the output passage 14b. The body 14 has a hole 14h that connects the output passage 14b with the space above the body 14. The hole 14h and the valve stem 34 are configured coaxially. The shaft 144 of the linear motor, described later, is inserted into the hole 14h and abuts against the upper end of the valve stem 34.

[0079] The valve core receiving chamber 20 is divided into a valve chamber 44 above the first diaphragm 36, a diaphragm chamber 46 between the first diaphragm 36 and the second diaphragm 38, and a back pressure chamber 48 below the second diaphragm 38. The valve chamber 44 is connected to the input port 16 via the input passage 14a.

[0080] The bore 40a of the first gasket 40, the annular groove 28d of the main valve core 28, the bore 28e of the main valve core 28, the shaft bore 28f of the main valve core 28, the shaft bore 34b of the valve stem 34, and the bore 34a of the valve stem 34 constitute a secondary pressure introduction passage for introducing the pressure of the fluid from the output port 18 into the diaphragm chamber 46. The diaphragm chamber 46 is connected to the output port 18 via the secondary pressure introduction passage and the output passage 14b.

[0081] The transverse hole 24c of the cover 24, the annular groove 24b of the cover 24, and the connecting passage 14f of the torso body 14 constitute a primary pressure introduction passage for introducing the pressure of the fluid from the input port 16 into the back pressure chamber 48. The back pressure chamber 48 is connected to the input port 16 via the primary pressure introduction passage.

[0082] The force acting on the valve core 26 in the vertical direction due to the fluid pressure is the same as in the fluid control valve 10 of the first embodiment, and will be briefly described below. Let the pressure at the input port 16, i.e., the primary pressure, be P1, and the pressure at the output port 18, i.e., the secondary pressure, be P2. Furthermore, let the effective pressure-bearing area of ​​the first diaphragm 36 be Sa, the effective pressure-bearing area of ​​the second diaphragm 38 be Sb, and the circular passage area in the valve seat 22 (the seat area of ​​the valve seat 22) be Sc. The sum of the forces acting on the valve core 26 due to the fluid pressure is (P1-P2)×(-Sa+Sb+Sc).

[0083] To make the sum of the forces acting on the valve core substantially zero, Sa - Sb = Sc. That is, the effective pressure-bearing area Sa of the first diaphragm 36 and the effective pressure-bearing area Sb of the second diaphragm 38 are set such that the difference between them equals the passage area Sc in the valve seat 22. By setting it in this way, the sum of the forces acting on the valve core can be made substantially zero regardless of the magnitudes of the primary pressure P1 and the secondary pressure P2. Therefore, even if one or both of the primary pressure P1 and the secondary pressure P2 change, forces that would cause instability in the operation are not applied to the valve core 26.

[0084] The actuator assembly 134 is disposed above the valve assembly 132 and constitutes a linear motor. The mounting members of the linear motor include an outer magnetic yoke 136 mounted on the body 12 of the valve assembly 132 and an electromagnetic coil 138 fixed to the inner side of the outer magnetic yoke 136.

[0085] The movable part of the linear motor is constructed by fixing a central yoke 140 and a pair of permanent magnets 142a and 142b to a shaft 144. The pair of permanent magnets 142a and 142b, magnetized axially (vertically), are arranged such that the central yoke 140 is sandwiched in the middle and their like poles face each other. When a drive current flows to the electromagnetic coil 138, it generates an upward or downward thrust on the magnets 142a and 142b and the central yoke 140, depending on the direction of the drive current. The magnitude of this thrust is proportional to the magnitude of the drive current.

[0086] A position sensor 146, composed of a Hall element and a magnetic drag element, is disposed above the movable member. The position of the movable member is detected by the position sensor 146, and the detection signal is sent to the control assembly 158. A holding yoke 148 is disposed below the movable member. Even when the electromagnetic coil 138 is not energized, an attractive force acts between the permanent magnet 142a below and the holding yoke 148. This maintains the lower end of the holding shaft 144 in contact with the valve stem 34.

[0087] Sensor assembly 150 is mounted at input port 16 of valve assembly 132. Sensor assembly 150 includes: a main flow path 152 connected to input port 16 of valve assembly 132, a secondary flow path 154 branching from the main flow path 152, and a flow sensor 156 facing the secondary flow path 154. Flow sensor 156 detects the flow rate of fluid flowing in the main flow path 152, and the detection signal is sent to control assembly 158.

[0088] Inlet assembly 162 is installed upstream of the main flow path 152 of sensor assembly 150. Outlet assembly 164 is installed at the output port 18 of valve assembly 132. Fluid supplied from a pressure supply source (not shown) to inlet assembly 162 is supplied to input port 16 of valve assembly 132 via the main flow path 152 of sensor assembly 150. Fluid output from output port 18 of valve assembly 132 is output to a fluid device (not shown) via outlet assembly 164. The flow rate of fluid from input port 16 to output port 18 is detected by flow sensor 156.

[0089] The control component 158, equipped with a control board 160, performs feedback control on the current applied to the solenoid coil 138 based on the detection signals from the flow sensor 156 and the position sensor 146. Specifically, firstly, the actual flow rate value based on the detection signal from the flow sensor 156 is compared with the target flow rate value to calculate the target valve opening (target position of the valve core). Next, the actual valve opening based on the position sensor 146 is compared with the target valve opening to calculate the current applied to the solenoid coil 138, and a drive signal is output to direct a specified drive current to the solenoid coil 138.

[0090] As described above, even if one or both of the primary pressure P1 and secondary pressure P2 change, forces that would cause instability in the operation are not applied to the valve core 26. Therefore, the energization control of the solenoid coil 138 of the linear motor is stable and unaffected by so-called external disturbances. Thus, heating of the solenoid coil 138 can be suppressed as much as possible.

[0091] According to this embodiment, the difference between the effective pressure-bearing area Sa of the first diaphragm 36 and the effective pressure-bearing area Sb of the second diaphragm 38 is equal to the passage area Sc in the valve seat 22. Therefore, even if the primary or secondary pressure changes, the force that would cause instability in the operation is not applied to the valve core 26, and the heating of the electromagnetic coil 138 of the linear motor can be suppressed as much as possible.

[0092] This invention is not limited to the embodiments described above, and various structures can be adopted without departing from the spirit of this invention.

Claims

1. A fluid control valve (10) comprising a body (12) having an input port (16) and an output port (18) and a valve core (26) capable of abutting against a valve seat (22) of said body, characterized in that, A first diaphragm (36) and a second diaphragm (38) are disposed between the valve core and the body. A diaphragm chamber (46) is formed between the first diaphragm and the second diaphragm. The first diaphragm divides the valve chamber (44) and the diaphragm chamber, and the second diaphragm divides the diaphragm chamber and the back pressure chamber (48). The diaphragm chamber is connected to the output port, and the valve chamber and the back pressure chamber are connected to the input port. The difference between the effective pressure-bearing area of ​​the first diaphragm and the effective pressure-bearing area of ​​the second diaphragm is equal to the passage area in the valve seat. The effective pressure-bearing area of ​​the first diaphragm is the area of ​​the thin film portion, which is the deformation region of the first diaphragm, and the effective pressure-bearing area of ​​the second diaphragm is the area of ​​the thin film portion, which is the deformation region of the second diaphragm.

2. The fluid control valve according to claim 1, characterized in that, A gasket (40) is disposed between the inner periphery of the first diaphragm and the inner periphery of the second diaphragm, and the diaphragm chamber is connected to the output port via a secondary pressure inlet passage disposed on the gasket and the valve core.

3. The fluid control valve according to claim 1, characterized in that, A gasket (42) is disposed between the outer periphery of the first diaphragm and the outer periphery of the second diaphragm, and the inner periphery of the gasket has a stepped portion (42a), so that the effective pressure-bearing area of ​​the first diaphragm is larger than that of the second diaphragm.

4. The fluid control valve according to claim 1, characterized in that, The valve is equipped with a pressure regulating diaphragm, which divides a pressure regulating diaphragm chamber (62) connected to the output port. The inner periphery of the pressure regulating diaphragm is sandwiched between a base retainer (64) and a retaining plate (66). The base retainer abuts against the valve stem (34) that constitutes the valve core. The retaining plate supports one end of the pressure regulating spring (58), and the fluid control valve functions as a pressure reducing valve.

5. The fluid control valve according to claim 1, characterized in that, The valve core is equipped with a linear motor that controls the opening degree of the valve core by controlling the energization of the electromagnetic coil (138), and the shaft (144) of the movable part of the linear motor abuts against the valve core.

6. The fluid control valve according to claim 5, characterized in that, The system includes a flow sensor (156) that detects the flow rate of fluid from the input port toward the output port, and the fluid control valve performs feedback control to make the actual flow rate value detected by the flow sensor the target flow rate value.

7. A fluid control valve comprising a body having an input port and an output port, and a valve core capable of abutting against a valve seat of the body, characterized in that, A first diaphragm and a second diaphragm are disposed between the valve core and the body. A diaphragm chamber is formed between the first diaphragm and the second diaphragm. The first diaphragm divides the valve chamber and the diaphragm chamber, and the second diaphragm divides the diaphragm chamber and the back pressure chamber. The diaphragm chamber is connected to the input port, and the valve chamber and the back pressure chamber are connected to the output port. The difference between the effective pressure-bearing area of ​​the first diaphragm and the effective pressure-bearing area of ​​the second diaphragm is equal to the passage area in the valve seat. The effective pressure-bearing area of ​​the first diaphragm is the area of ​​the thin film portion, which is the deformation region of the first diaphragm, and the effective pressure-bearing area of ​​the second diaphragm is the area of ​​the thin film portion, which is the deformation region of the second diaphragm.

8. A fluid control valve (80) comprising a body (82) having an input port (86) and an output port (88) and a valve core (100) capable of abutting against a valve seat (92b) of said body, characterized in that, A first diaphragm (106) and a second diaphragm (108) are disposed between the valve core and the body. A diaphragm chamber (116) is formed between the first diaphragm and the second diaphragm. The first diaphragm divides the valve chamber (114) and the diaphragm chamber, and the second diaphragm divides the diaphragm chamber and the back pressure chamber (118). The diaphragm chamber is connected to the output port, and the valve chamber and the back pressure chamber are connected to the input port. One end of the valve core extends from the back pressure chamber toward the chamber disposed on the outside of the body and connected to the output port. The difference between the effective pressure-bearing area of ​​the first diaphragm and the effective pressure-bearing area of ​​the second diaphragm is equal to the difference between the passage area in the valve seat and the cross-sectional area of ​​one end of the valve core. The effective pressure-bearing area of ​​the first diaphragm is the area of ​​the thin film portion, which is the deformation region of the first diaphragm, and the effective pressure-bearing area of ​​the second diaphragm is the area of ​​the thin film portion, which is the deformation region of the second diaphragm.

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