Proportional control valve

Abstract

To provide a proportional control valve which can suppress a change of downstream-side pressure (secondary pressure) with respect to a change of upstream-side pressure (primary pressure), and achieves reduction in the size of a drive source as well as the overall size and weight.SOLUTION: A proportional control valve includes: a housing 10 including an upstream-side chamber 11b and a downstream-side chamber 11d for allowing fluid to flow therein, and a valve seat 11a interposed between the upstream-side chamber and the downstream-side chamber; a first diaphragm 20 arranged in the housing so that the pressure P1 of the upstream-side chamber acts on a front face 21a1, and the pressure P2 of the downstream-side chamber acts on a back face 21a2; a second diaphragm 30 arranged in the housing so that the pressure P2 of the downstream-side chamber acts on a front face 31a1, and atmospheric pressure acts on a back face 31a2; a valve body 40 interlocked with the first diaphragm and the second diaphragm, and moving so as to be seatable on the valve seat 11a and releasable therefrom; and a drive unit Du exerting a drive force to the valve body.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a proportional control valve that proportionally controls the opening degree of a valve body for opening and closing a fluid passage, and particularly to a proportional control valve applied when adjusting the gas flow rate incorporated in a gas water heater system.

Background Art

[0002] As a conventional proportional control valve, as shown in FIG. 12, a case 1 defining an inlet chamber 1a, an outlet chamber 1b, and a valve seat 1c located between the inlet chamber 1a and the outlet chamber 1b for a gas fluid, a diaphragm 2 closing the surface of the inlet chamber 1a opposite to the valve seat 1c, a valve body 3 that reciprocates integrally with the diaphragm 2 and can seat on the valve seat 1c, a solenoid 4 including a movable iron core 4a that reciprocally drives the valve body 3, and a spring 5 that cancels the self-weights of the valve body 3 and the movable iron core 4a are known (see, for example, Patent Document 1).

[0003] In the gas proportional control valve having the above configuration, generally, in order to keep the pressure in the outlet chamber 1b (secondary pressure P2) constant with respect to the pressure in the inlet chamber 1a (primary pressure P1), the effective area Av of the valve body 3 and the effective area Ad of the diaphragm 2 are set to be the same in design. For example, when the force exerted by the solenoid 4 in the valve opening direction is F, the force balance equation in the moving direction of the valve body 3 is F + Av·P1 = Ad·P1 + Av·P2. Rearranging this equation gives P2 = [F + (Av - Ad)·P1] / Av. Therefore, if the effective area Av of the valve body 3 and the effective area Ad of the diaphragm 2 are the same, the secondary pressure P2 can be kept constant regardless of the primary pressure P1.

[0004] However, in a gas proportional valve having the above configuration, the diaphragm 2 is made of a flexible material that can be elastically deformed, and the diaphragm 2 is attached by sandwiching its outer edge between two members. Therefore, due to variations in the dimensions of each component or variations in the assembly position, the effective diameter that defines the effective area Ad of the diaphragm 2 changes, and the predetermined effective area Ad may not be obtained. As a result, there is a risk that the change in secondary pressure P2 will be larger than the change in primary pressure P1. Furthermore, in conventional gas proportional valves, as shown in Figure 13, the load that balances the secondary pressure P2 decreases as the outer diameter (effective diameter) of the valve body decreases, so even a small change in load can lead to a large change in the secondary pressure. For this reason, it is difficult to miniaturize the valve body and solenoid, and to miniaturize and lighten the gas proportional valve as a whole. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2007-162911 [Overview of the project] [Problems that the invention aims to solve]

[0006] The present invention has been made in view of the above circumstances, and its purpose is to provide a proportional control valve that can solve the problems of the conventional invention and suppress changes in the downstream pressure (secondary pressure) in response to changes in the upstream pressure (primary pressure) of the valve body without improving the dimensional accuracy or assembly accuracy of each component, and that enables a reduction in the diameter of the valve body, miniaturization of the drive source, and overall miniaturization and weight reduction. [Means for solving the problem]

[0007] The proportional control valve of the present invention includes a housing containing an upstream chamber and a downstream chamber through which fluid passes, and a valve seat interposed between the upstream and downstream chambers; a first diaphragm positioned within the housing such that the pressure from the upstream chamber acts on the front and the pressure from the downstream chamber acts on the back; a second diaphragm positioned within the housing such that the pressure from the downstream chamber acts on the front and atmospheric pressure acts on the back; a valve body that moves in conjunction with the first and second diaphragms and is capable of seating and detaching from the valve seat; and a drive source that provides driving force to the valve body. The housing includes a back pressure chamber that the back surface of the first diaphragm faces, and the valve body includes a communication passage that connects the downstream chamber and the back pressure chamber.

[0008] In the above proportional control valve, when the pressure in the upstream chamber is P1, the pressure in the downstream chamber is P2, the effective area of ​​the first diaphragm is Ad1, the effective area of ​​the second diaphragm is Ad2, the effective area of ​​the valve body is Av, and the driving force of the drive source is F, the force balance equation in the direction of movement of the valve body is: P2=[F+(Ad1-Av)·P1] / (Ad2+Ad1-Av) A configuration that satisfies the following conditions may be adopted.

[0009] In the above-described proportional control valve, a configuration may be adopted in which the effective area Ad1 of the first diaphragm and the effective area Ad2 of the second diaphragm are formed such that Ad2 / Ad1 > 1.

[0010] In the proportional control valve described above, the valve body may be configured to include a valve portion with an annular tapered surface that narrows toward the downstream chamber so as to be able to contact the valve seat, and a rod portion connected to the first diaphragm and the second diaphragm.

[0012] In the proportional control valve described above, the drive source may be a solenoid that includes a movable iron core that engages with the valve body and an excitation coil arranged around the movable iron core.

[0013] In the proportional control valve described above, the valve body moves in the vertical direction. and A configuration may be adopted in which both are positioned to sit on the valve seat by their own weight.

[0014] In the above-described proportional control valve, a configuration may be adopted that includes a biasing member that biases the movable iron core toward the valve body.

[0015] In the above-described proportional control valve, a configuration may be adopted in which the upstream chamber is located above the valve seat and the downstream chamber is located below the valve seat.

[0016] In the above-described proportional control valve, the housing may include a housing body that defines a first opening that opens to the upstream chamber and a second opening that opens to the downstream chamber, respectively, toward the outward sides in the direction of movement of the upstream chamber, downstream chamber, valve seat, and valve body; a first housing cover that covers a first diaphragm positioned to close the first opening from the outside; and a second housing cover that covers a second diaphragm positioned to close the second opening from the outside.

[0017] In the proportional control valve described above, the valve body moves in the vertical direction. and A configuration may be adopted in which both chambers are positioned to sit on the valve seat by their own weight, with the upstream chamber positioned above the valve seat and the downstream chamber positioned below the valve seat.

[0018] In the above-described proportional control valve, the housing body may include a fluid inlet leading to an upstream chamber and a fluid outlet leading to a downstream chamber, and the inlet and outlet may be arranged at the same height in the direction of movement of the valve body.

[0019] In the above proportional control valve, the first housing cover is The above back pressure chamber is defined, You may adopt this configuration.

[0020] In the proportional control valve described above, the second housing cover may be configured to include an opening that opens the back surface of the second diaphragm to the atmosphere. [Effects of the Invention]

[0021] According to the proportional control valve having the above configuration, without increasing the dimensional accuracy and assembly accuracy of each component, it is possible to suppress the change in the downstream pressure (secondary pressure) with respect to the change in the upstream pressure (primary pressure) of the valve body, and it is possible to achieve a smaller diameter of the valve body, a smaller drive source, a smaller size as a whole, and a lighter weight.

Brief Description of the Drawings

[0022] [Figure 1] It shows a proportional control valve according to an embodiment of the present invention, and is an external perspective view seen obliquely from above. [Figure 2] It is an external perspective view of a proportional control valve according to an embodiment seen obliquely from below. [Figure 3] It is an external perspective view of a drive unit included in a proportional control valve according to an embodiment. [Figure 4] In a proportional control valve according to an embodiment, it is a perspective cross-sectional view cut along a plane including a straight line passing through the center of the axis extending in the vertical direction and the center of the fluid inlet and outlet. [Figure 5] In a proportional control valve according to an embodiment, it is a longitudinal cross-sectional view cut along a plane including a straight line passing through the center of the axis extending in the vertical direction and the center of the fluid inlet and outlet. [Figure 6] In a proportional control valve according to an embodiment, it is a longitudinal cross-sectional view cut along a plane including an axis perpendicular to the straight line passing through the center of the fluid inlet and outlet and extending in the vertical direction. [Figure 7] In a proportional control valve according to an embodiment, it is an external perspective view of the housing body constituting the housing seen obliquely from above. [Figure 8] In a proportional control valve according to an embodiment, it is an external perspective view of the housing body constituting the housing seen obliquely from below. [Figure 9] In a proportional control valve according to an embodiment, it is a schematic diagram showing pressures, effective areas, driving forces, etc. related to the balance formula of forces in the moving direction of the valve body. [Figure 10]This graph shows the relationship between the ratio of the effective area of ​​the first diaphragm to the effective area of ​​the second diaphragm (Ad2 / Ad1) and the change in pressure (secondary pressure) in the downstream chamber (ΔP2) in the proportional control valve of the present invention. [Figure 11] This graph shows the relationship between the pressure in the upstream chamber (primary pressure P1) and the pressure in the downstream chamber (secondary pressure P2) in the proportional control valve of the present invention. [Figure 12] This is a cross-sectional view showing the structure of a conventional proportional control valve. [Figure 13] This graph shows the relationship between the outer diameter (effective diameter) of the valve body and the change in downstream pressure (secondary pressure) (ΔP2) in a conventional proportional control valve. [Modes for carrying out the invention]

[0023] Embodiments of the present invention will be described below with reference to the accompanying drawings. One embodiment of the proportional control valve is incorporated into a gas water heater system, for example, to control the flow rate of gas fluid, and as shown in Figures 1 to 3, it consists of a valve unit Vu and a drive unit Du as a drive source.

[0024] The valve unit Vu comprises a housing 10, a first diaphragm 20, a second diaphragm 30, and a valve body 40. The drive unit Du comprises a frame member 50, a sleeve 60, a movable iron core 70, an excitation coil 80, and a spring 90 as a biasing member. The proportional control valve is then incorporated into the gas water heater system with the axis S, which is the direction of movement of the valve body 40 and the movable iron core 70, oriented in the vertical direction Vd, so that the valve body 40 is positioned on the upper side and the movable iron core 70 is positioned on the lower side.

[0025] The housing 10 consists of a housing body 11 formed from a metal material such as aluminum, and a first housing cover 12 and a second housing cover 13 press-formed from a metal material such as stainless steel sheet.

[0026] As shown in Figures 1, 2, 4 to 8, the housing body 11 has a hexahedral contour and includes a valve seat 11a centered on the axis S, an upstream chamber 11b, an inlet 11c, a downstream chamber 11d, an outlet 11e, a first opening 11f, a first annular groove 11g, a first annular recess 11h, two screw holes 11i, a second opening 11j, a second annular groove 11k, a second annular recess 11m, and two boss portions 11n.

[0027] The valve seat 11a is formed in an annular shape to define a circular hole 11a1 with an inner diameter D centered on the axis S, which serves as a passage for fluid, and the valve portion 41 of the valve body 40 can be seated detachably in the direction of the axis S. Here, the inner diameter D defines the effective diameter of the valve body 40, as shown in Figure 9. The upstream chamber 11b is a passage for fluid and is formed upstream of the valve seat 11a and above the valve seat 11a in the vertical direction Vd. The inlet 11c is formed as a circular hole with its center on a straight line C perpendicular to the axis S, in order to allow fluid to flow into the housing 10. The downstream chamber 11d is a passage for fluid and is formed downstream of the valve seat 11a and below the valve seat 11a in the vertical direction Vd. The outlet 11e is formed as a circular hole with its center on a straight line C perpendicular to the axis S, in order to allow the fluid to flow out of the housing 10. Furthermore, the inlet 11c and outlet 11e are connected to the gas supply pipe in the gas water heater system. Furthermore, the inlet 11c and outlet 11e are arranged on a straight line C, meaning they are positioned at the same height in the direction of movement of the valve body 40 (axis S direction). This allows for a reduction in the dimensions of the housing body 11 in the axis S direction, contributing to miniaturization.

[0028] The first opening 11f is formed as a circular hole that opens the upstream chamber 11b toward the axial direction S, that is, toward one side in the direction of movement of the valve body 40. The first opening 11f is then closed by the first diaphragm 20. The first annular groove 11g is formed in an annular shape that is recessed outward in the axial direction S around the first opening 11f, so that the outer peripheral edge 21b of the first diaphragm 20 can be fitted into it. The first annular recess 11h is formed adjacent to the outside of the first annular groove 11g in the axial direction S, and is formed so that the annular portion 12b of the first housing cover 12 is fitted into it. The two screw holes 11i are formed for screwing in screws b1 that fasten and secure the first housing cover 12.

[0029] The second opening 11j is formed as a circular hole that opens the downstream chamber 11d toward the other side of the axial direction S, i.e., the direction of movement of the valve body 40. The second opening 11j is then closed by the second diaphragm 30. The second annular groove 11k is formed in an annular shape that is recessed outward in the axial direction S around the second opening 11j, so that the outer peripheral edge 31b of the second diaphragm 30 can be fitted into it. The second annular recess 11m is formed adjacent to the outside of the second annular groove 11k in the axial direction S, and is formed so that the annular portion 13a of the second housing cover 13 is fitted into it. The two boss portions 11n are formed in a cylindrical shape that protrudes outward in the axial direction S, and are designed to accommodate screws b2 that fasten and fix the frame member 50 (outer yoke 51) of the drive unit Du.

[0030] As shown in Figures 1, 4 to 6, the first housing cover 12 includes a flange portion 12a, an annular portion 12b, and a bottomed cylindrical portion 12c. The flange portion 12a is a region that is joined to the end face of the housing body 11 in the axial direction S, and is provided with two circular holes 12a1 through which the screw b1 passes. The annular portion 12b is formed to fit into the first annular recess 11h of the housing body 11 in order to press the outer peripheral edge portion 21b of the first diaphragm 20 toward the first annular groove portion 11g. The bottomed cylindrical portion 12c is formed to include a bottom wall that protrudes outward and a cylindrical wall centered on the axis S, defining a back pressure chamber Bc1 that the back surface 21a2 of the first diaphragm 20 faces.

[0031] The first housing cover 12 is then joined to the housing body 11 and fastened with screws b1, with the first diaphragm 20 positioned so as to be connected to the valve body 40 and close the first opening 11f of the housing body 11, and the first housing cover 12 presses and fixes the outer peripheral edge 21b of the first diaphragm 20 and covers the first diaphragm 20 from the outside in the axial direction S.

[0032] As shown in Figures 2, 4 to 6, the second housing cover 13 includes an annular portion 13a, an annular recess 13b, a fitting recess 13c, a central opening 13d, and an open hole 13e. The annular portion 13a is formed to fit into the second annular recess 11m of the housing body 11 in order to press the outer peripheral edge portion 31b of the second diaphragm 30 toward the second annular groove portion 11k. The annular recess 13b is formed as an annular recess centered on the axis S, defining a back pressure chamber Bc2 that the back surface 31a2 of the second diaphragm 30 faces. The outer surface of the annular recess 13b is formed as a flat surface perpendicular to the axis S, and is pressed inward in the direction of the axis S by the outer yoke 51 of the frame member 50 included in the drive unit Du. The fitting recess 13c defines an inner cylindrical surface centered on the axis S, and is formed so that the sleeve 60 of the drive unit Du is fitted into it via the O-ring R1. The central opening 13d is formed as a circular hole centered on the axis S, and the fitting shaft portion 42d of the valve body 40 is inserted through it without contact, that is, with a predetermined gap. The opening 13e opens the back pressure chamber Bc2 to the atmosphere via the recess 51a2 of the frame member 50 (outer yoke 51) in order to allow atmospheric pressure to act on the back surface 31a2 of the second diaphragm 30.

[0033] The second housing cover 13 is positioned such that the second diaphragm 30 is connected to the valve body 40 and closes the second opening 11j of the housing body 11. The second housing cover 13 is joined to the housing body 11 so as to press and fix the outer peripheral edge 31b of the second diaphragm 30 and cover the second diaphragm 30 from the outside in the axial direction S. The second housing cover 13 is held in place by being pressed by the outer yoke 51 of the frame member 50 and the outer yoke 51 being fastened and fixed by the screw b2.

[0034] As shown in Figures 4 to 6, the first diaphragm 20 includes a rubber plate 21 and a fixing cap 22 made of an elastically deformable rubber material. The rubber plate 21 comprises an elastically deformable annular membrane portion 21a, an outer peripheral edge portion 21b that fits into the first annular groove portion 11g of the housing body 11, and a central portion 21c. The annular membrane portion 21a is an elastically deformable thin film and is formed in an annular shape with respect to the axis S, and has a front surface 21a1 facing the upstream chamber 11b and a back surface 21a2 facing the back pressure chamber Bc1. The outer peripheral edge portion 21b is formed in an annular shape centered on the axis S, and has a wall thickness greater than the groove depth of the first annular groove portion 11g. The central portion 21c is formed in a cylindrical shape with a wall thickness greater than that of the outer peripheral edge portion 21b, and defines a fitting hole centered on the axis S so that the fitting shaft portion 42b of the valve body 40 can be fitted into it. The fixing cap 22 is formed to fix the valve body 40 by pressing the central part 21c of the rubber plate 21 against the fitting shaft portion 42b of the valve body 40, and also to abut against the inner wall surface of the first housing cover 12 to define the fully open position of the valve body 40.

[0035] In other words, the first diaphragm 20 is positioned upstream of the valve seat 11a, facing the upstream chamber 11b and closing the first opening 11f within the housing 10. It is linked to the valve body 40, which moves in the axial direction S, and the pressure from the upstream chamber 11b (primary pressure P1) acts on the front surface 21a1, while the pressure from the downstream chamber 11d (secondary pressure P2) acts on the back surface 21a2 via the communication passage 40a of the valve body 40. The first diaphragm 20 then plays a role in regulating the pressure in response to fluctuations in the pressure P1 in the upstream chamber 11b and the pressure P2 in the downstream chamber 11d.

[0036] As shown in Figures 4 to 6, the second diaphragm 30 includes a rubber plate 31 and a fixed plate 32 made of an elastically deformable rubber material. The rubber plate 31 comprises an elastically deformable annular membrane portion 31a, an outer peripheral edge portion 31b that fits into the second annular groove portion 11k of the housing body 11, and a central portion 31c. The annular membrane portion 31a is an elastically deformable thin film and is formed in an annular shape with respect to the axis S, and has a front surface 31a1 facing the downstream chamber 11d and a back surface 31a2 facing the back pressure chamber Bc2. The outer peripheral edge portion 31b is formed in an annular shape centered on the axis S, and has a wall thickness greater than the groove depth of the second annular groove portion 11k. The central portion 31c is formed to include a disc portion 31c1 and a cylindrical portion 31c2 that defines a fitting hole centered on the axis S for fitting the fitting shaft portion 42d of the valve body 40, and has a wall thickness greater than that of the outer peripheral edge portion 31b. The fixing plate 32 is positioned adjacent to the central portion 31c of the rubber plate 31 and is formed to hold the disc portion 31c1 and fix the cylindrical portion 31c2 to the fitting shaft portion 42d of the valve body 40.

[0037] In other words, the second diaphragm 30 is positioned downstream of the valve seat 11a, facing the downstream chamber 11d and closing the second opening 11j. It is linked to the valve body 40 which moves in the axial direction S, and the pressure of the downstream chamber 11d (secondary pressure P2) acts on the front surface 31a1, while atmospheric pressure acts on the back surface 31a2 through the opening 13e of the second housing cover 13. The second diaphragm 30 then plays a role in regulating the pressure in response to fluctuations in the pressure P2 of the downstream chamber 11d.

[0038] The valve body 40 is formed as a poppet valve and includes a valve portion 41 and a rod portion 42 extending from the valve portion 41 in the axial direction S. The valve portion 41 is formed in a substantially frustoconical shape with axis S as the center, and has an annular tapered surface 41a that tapers towards the downstream chamber 11d and curves convexly so that it can contact the valve seat 11a in the outer peripheral region. The rod portion 42 is formed in a cylindrical shape with the axis S as its center, and includes an upper shaft portion 42a, a fitting shaft portion 42b, a lower shaft portion 42c, and a fitting shaft portion 42d. Furthermore, the valve body 40 extends from the region facing the downstream chamber 11d to the region facing the back pressure chamber Bc1, which is faced by the back surface 21a2 of the first diaphragm 20, and is provided with a communication passage 40a that connects the downstream chamber 11d and the back pressure chamber Bc1.

[0039] The upper shaft portion 42a is formed in a cylindrical shape within the upstream chamber 11b, extending outward (upward) from the valve portion 41 in the axial direction S. The fitting shaft portion 42b is continuous with the upper shaft portion 42a in the axial direction S and has a multi-stage outer diameter smaller than that of the upper shaft portion 42a. It is formed so that the central portion 21c of the rubber plate 21 of the first diaphragm 20 is fitted into it, and the fixing cap 22 is also fitted into it. The fitting shaft portion 42b may be formed integrally with the upper shaft portion 42a, or it may be formed separately and then connected and fixed to the upper shaft portion 42a. The lower shaft portion 42c has the same outer diameter as the upper shaft portion 42a and is formed in a cylindrical shape that extends inward (downward) from the valve portion 41 in the axial direction S within the downstream chamber 11d. The fitting shaft portion 42d is integrally formed with the lower shaft portion 42c so as to be continuous with the lower shaft portion 42c in the axial direction S and to have a multi-stage outer diameter smaller than that of the lower shaft portion 42c. The central portion 31c (cylindrical portion 31c2) of the rubber plate 31 of the second diaphragm 30 is fitted into the fitting shaft portion 42d, and the fixing plate 32 is also fitted into it. Furthermore, the tip portion of the fitting shaft portion 42d is inserted through the central opening 13d of the second housing cover 13, and its end portion 42d1 is in detachable contact with the movable iron core 70 of the drive unit Du.

[0040] In other words, the valve body 40 moves in conjunction with the first diaphragm 20 and the second diaphragm 30 in the axial direction S, and is capable of seating on and detaching from the valve seat 11a, and is also subjected to the driving force of the movable core 70 in the axial direction S.

[0041] The frame member 50 is made of soft iron or the like and functions as a magnetic path through which magnetic field lines pass, and is composed of an outer yoke 51, an inner yoke 52, and an end yoke 53. The outer yoke 51 is formed by bending in a roughly U-shape and includes a flat plate portion 51a defining a fitting hole 51a1 and a recess 51a2 located on the axis S, two leg portions 51b, two flange portions 51c extending from the flat plate portion 51a and including a circular hole 51c1 through which a screw b2 passes, and two connecting portions 51d. The inner yoke 52 comprises a substantially rectangular flat plate portion 52a, a cylindrical portion 52b that defines a fitting hole 52b1 located on the axis S and is continuous with the flat plate portion 52a, and into which the bobbin 81 is fitted on the outer circumferential surface, and two connecting portions 52c that are connected to the connecting portion 51d of the outer yoke 51. The end yoke 53 comprises a roughly rectangular flat plate 53a, a bottomed cylindrical portion 53b with two diameters centered on the axis S, and two connecting portions 53c that are connected to the connecting portion 51d of the outer yoke 51.

[0042] The sleeve 60 is formed in a cylindrical shape using a metal material such as stainless steel, with the axis S as its center, and serves to guide the movable iron core 70 so that it can slide freely in the direction of the axis S. The sleeve 60 is then fitted into the fitting hole 51a1 of the outer yoke 51 and the fitting hole 52b1 of the inner yoke 52, and its upper end region is fitted into the fitting recess 13c of the second housing cover 13 via an O-ring R1, and its lower end region is fitted into the bottomed cylindrical portion 53b of the end yoke 53 via an O-ring R2 to complete the assembly. As a result, the sleeve 60 guides the movable iron core 70 so that it can slide freely in the axial direction S.

[0043] The movable iron core 70 is cylindrical in shape and extends in the axial direction S, is slidably arranged within the sleeve 60, and is equipped with an upper end contact portion 71 and a lower end spring receiving portion 72. The upper end contact portion 71 is formed as a circular flat surface and detachably contacts the end portion 42d1 of the fitting shaft portion 42d of the valve body 40. The lower end spring receiving portion 72 is formed as a flat surface at the bottom of the annular recess and receives the upper end of the spring 90 in the axial direction S. In other words, the movable iron core 70 is configured to engage with the valve body 40 in the axial direction S and exert a driving force.

[0044] The excitation coil 80 is wound around a resin bobbin 81 that is sandwiched and held between the outer yoke 51 and the inner yoke 52, with the axis S as its center. The bobbin 81 has two terminals 81a extending from the excitation coil 80 integrally molded into it by molding.

[0045] The spring 90 is a compression-type coil spring and is positioned inside the sleeve 60 so as to bias the movable core 70 toward the valve body 40 in the axial direction S, with its upper end 91 in contact with the lower end spring receiving portion 72 of the movable core 70 and its lower end 92 in contact with the bottom wall of the bottomed cylindrical portion 53b of the end yoke 53, allowing it to expand and contract in the axial direction S.

[0046] The spring 90 supports the valve body 40, the first diaphragm 20, the second diaphragm 30, and the movable core 70 in the axial direction S (vertical direction Vd) in such a way that it almost cancels out their weight, and also exerts an upward biasing force on the movable core 70 in the vertical direction Vd so that the valve body 40 is in a resting position where it is seated on the valve seat 11a by its own weight.

[0047] In the proportional control valve having the above configuration, as shown in Figure 9, when the pressure in the upstream chamber 11b of the housing 10 (primary pressure) is P1 and the pressure in the downstream chamber 11d (secondary pressure) is P2, the effective area of ​​the first diaphragm 20 is Ad1, the effective area of ​​the second diaphragm 30 is Ad2, the effective area of ​​the valve body 40 is Av, and the driving force of the drive unit Du (movable core 70) is F, the force balance equation in the direction of movement of the valve body 40 (axis S direction) is: In the direction of axis S, An upward force = a downward force F+Av·P2+Ad1·P1=Ad2·P2+Av·P1+Ad1·P2 Rearranging the above equation in terms of P1 and P2, (Ad2+Ad1-Av)·P2=F+(Ad1-Av)·P1 Therefore, the function equations for the input variable pressure P1 and the output variable pressure P2 are as follows: P2=[F+(Ad1-Av)·P1] / (Ad2+Ad1-Av) ···(a) You can obtain this. Here, the effective areas Ad1, Av, and Ad2 are calculated from the effective diameter of the surface that receives pressures P1 and P2 and effectively acts as thrust. The effective diameter is the diameter of the surface that receives pressures P1 and P2 and effectively acts as thrust. Furthermore, although the effective area Ad1 of the first diaphragm 20 and the effective area Av of the valve body 40 are preferably set to the same value in the design, due to variations in the dimensions of each component and variations in assembly, the two will be approximate values. In other words, the proportional control valve having the above configuration is formed to satisfy the above function equation (a).

[0048] Furthermore, in a proportional control valve having the above configuration, the relationship between the change in pressure P2 in the downstream chamber 11d (change amount ΔP2) and the ratio (Ad2 / Ad1) of the effective area Ad2 of the second diaphragm 30 and the effective area Ad1 of the first diaphragm 20 is obtained as the graph shown in Figure 10. In other words, a relationship is obtained in which the pressure (secondary pressure) P2 in the downstream chamber 11d changes gradually in response to increases or decreases in the value of Ad2 / Ad1. In particular, as the value of Ad2 / Ad1 increases, the amount of change ΔP2 in the pressure (secondary pressure) P2 in the downstream chamber 11d decreases. In other words, as shown in Figure 11, compared to conventional proportional control valves, the proportional control valve of the present invention can reduce the change (ΔP2) in the pressure (secondary pressure) P2 in the downstream chamber 11d in response to a change in the pressure (primary pressure) P1 in the upstream chamber 11b. Therefore, the flow rate can be controlled by bringing the pressure P2 in the downstream chamber 11d closer to a desired constant value.

[0049] Now, let's consider the ratio (Ad2 / Ad1) of the effective area Ad2 of the second diaphragm 30 to the effective area Ad1 of the first diaphragm 20. If we assume that Ad2 / Ad1 = 1 (Ad2 = Ad1), then the above relationship (a) becomes: P2 can be replaced with [F + (Ad1 - Av) · P1] / (Ad1 + Ad1 - Av), Since Ad1 and Av are approximately the same (approximate values), the following approximation formula is used. P2 can be expressed as P2 = [F + (Ad1 - Av)·P1] / Ad1, and this approximation is equivalent to the relationship between P1 and P2 in conventional proportional control valves, P2 = [F + (Av - Ad)·P1] / Av. Therefore, it is preferable that the value of Ad2 / Ad1 be greater than 1. In other words, in a proportional control valve having the above configuration, it is preferable that the relationship between the effective area Ad1 of the first diaphragm 20 and the effective area Ad2 of the second diaphragm 30 is formed such that Ad2 / Ad1 > 1. More preferably, it is formed such that Ad2 / Ad1 > 2.

[0050] Next, we will describe the operation of the proportional control valve when it is incorporated into a gas water heater system. First, in the stopped state, the control valves (not shown) located upstream and downstream of the proportional control valve are closed, the excitation coil 80 is de-energized, and the valve body 40 is in a closed, resting position, seated on the valve seat 11a as shown in Figure 5. When the control device issues a signal to start combustion operation from this stopped state, the control valve opens appropriately, the excitation coil 80 is energized, and the driving force F of the movable iron core 70 acts, causing the valve body 40 to lift from the valve seat 11a and open. Then, in response to the control signal, the energization of the excitation coil 80 is controlled by PWM and adjusted to the required valve opening.

[0051] Furthermore, when the valve body 40 reaches its maximum lift, the fixing cap 22 comes into contact with the inner wall surface of the first housing cover 12, restricting further movement. On the other hand, when a signal to stop combustion is issued by the control equipment, the control valve is closed as appropriate, and the excitation coil 80 is de-energized, so that the driving force F of the movable iron core 70 does not act, and the valve body 40 sits on the valve seat 11a by its own weight and closes.

[0052] As described above, the proportional control valve of the present invention comprises a housing 10 including an upstream chamber 11b and a downstream chamber 11d through which fluid passes, and a valve seat 11a interposed between the upstream chamber 11b and the downstream chamber 11d; a first diaphragm 20 positioned within the housing 10 such that the pressure of the upstream chamber 11b acts on the front surface 21a1 and the pressure of the downstream chamber 11d acts on the rear surface 21a2; a second diaphragm 30 positioned within the housing 10 such that the pressure of the downstream chamber 11d acts on the front surface 31a1 and atmospheric pressure acts on the rear surface 31a2; a valve body 40 that moves in conjunction with the first diaphragm 20 and the second diaphragm 30 and is capable of seating and detaching from the valve seat 11a; and a drive source (drive unit Du) that provides driving force to the valve body 40. In particular, when the pressure in the upstream chamber 11b is P1, the pressure in the downstream chamber 11d is P2, the effective area of ​​the first diaphragm 20 is Ad1, the effective area of ​​the second diaphragm 30 is Ad2, the effective area of ​​the valve body 40 is Av, and the driving force of the drive source (drive unit Du) is F, the force balance equation in the direction of movement of the valve body 40 (axis S direction) is formed to satisfy P2 = [F + (Ad1 - Av) · P1] / (Ad2 + Ad1 - Av). Furthermore, the effective area Ad1 of the first diaphragm 20 and the effective area Ad2 of the second diaphragm 30 are formed such that Ad2 / Ad1 > 1. According to this, without increasing the dimensional accuracy or assembly accuracy of each component, the change in the downstream pressure (secondary pressure) P2 in response to the change in the upstream pressure (primary pressure) P1 of the valve body 40 can be suppressed compared to conventional methods. Furthermore, the valve body 40 can be made smaller, and the drive source (drive unit Du), as well as the overall size and weight, can be reduced.

[0053] Furthermore, according to the proportional control valve of the present invention, the valve body 40 has a valve portion 41 that includes an annular tapered surface 41a that tapers toward the downstream chamber 11d so as to be able to contact the valve seat 11a, and a rod portion 42 that is connected to the first diaphragm 20 and the second diaphragm 30. According to this, in a configuration in which the valve body 40 is moved in the vertical direction Vd and a driving force F is applied from below in the vertical direction Vd, two diaphragms (first diaphragm 20, second diaphragm 30) that are interlocked with the valve body 40 can be easily arranged to satisfy the above balance equation. Furthermore, the housing 10 includes a back pressure chamber Bc1 that the back surface 21a2 of the first diaphragm 20 faces, and the valve body 40 includes a communication passage 40a that connects the downstream chamber 11d and the back pressure chamber Bc1. According to this, it is possible to achieve weight reduction and structural simplification of the valve body 40.

[0054] Furthermore, according to the proportional control valve of the present invention, the drive source (drive unit Du) is a solenoid including a movable iron core 70 that engages with the valve body 40 and an excitation coil 80 arranged around the movable iron core 70, and is arranged so that the valve body 40 moves in the vertical direction Vd and sits on the valve seat 11a by its own weight. According to this, the desired driving force can be easily obtained, and the valve body 40 can be held in the closed position with a simple structure even when the excitation coil 80 is not energized. Furthermore, since it includes a biasing member (spring 90) that biases the movable iron core 70 toward the valve body 40, the biasing member (spring 90) can exert a biasing force that cancels out the weight of the valve body 40 and the movable iron core 70, and the driving force can be reduced accordingly.

[0055] Furthermore, according to the proportional control valve of the present invention, in the housing 10, the upstream chamber 11b is positioned above the valve seat 11a and the downstream chamber 11d is positioned below the valve seat 11a. Therefore, the present invention can be easily realized in a configuration in which the valve body 40 moves in the vertical direction Vd. Furthermore, according to the proportional control valve of the present invention, the housing 10 includes a housing body 11 that defines a first opening 11f that opens the upstream chamber 11b and a second opening 11j that opens the downstream chamber 11d, respectively, toward the outward sides in the direction of movement of the upstream chamber 11b, downstream chamber 11d, valve seat 11a, and valve body 40; a first housing cover 12 that covers the first diaphragm 20, which is positioned to close the first opening 11f, from the outside; and a second housing cover 13 that covers the second diaphragm 30, which is positioned to close the second opening 11j, from the outside. This makes the assembly of each component easier, and also allows for easy disassembly when necessary.

[0056] Furthermore, according to the proportional control valve of the present invention, since the inlet 11c and outlet 11e of the housing body 11 are arranged at the same height in the direction of movement of the valve body 40 (axis S direction), it is possible to make the housing body 11 thinner in the axis S direction, and thus the proportional control valve as a whole can be made smaller. In particular, the first housing cover 12 defines a back pressure chamber Bc1 that the back surface 21a2 of the first diaphragm 20 faces, and the second housing cover 13 includes an opening 13e that opens the back surface 31a2 of the second diaphragm 30 to the atmosphere, thus simplifying the structure of the housing body 11.

[0057] In the above embodiment, a proportional control valve is shown in which the valve body 40 moves in the vertical direction Vd and sits on the valve seat 11a due to its own weight, and which is equipped with a spring 90 that biases the movable iron core 70 upward in the vertical direction Vd. However, the invention is not limited to this. For example, in addition to the above embodiment in which the top and bottom are reversed, that is, in which the valve body 40 moves from bottom to top to seat on the valve seat 11a and close the valve, and the movable iron core 70 exerts a driving force from top to bottom on the valve body 40, the present invention can also be similarly applied to a configuration in which a biasing member (coil spring) is employed to bias the lower end of the valve body 40, which is located in the back pressure chamber Bc1, upward in the vertical direction Vd.

[0058] In the above embodiment, a solenoid including a movable iron core 70 and an excitation coil 80 that engage with the valve body 40 was shown as the drive source that applies driving force to the valve body 40. However, the invention is not limited to this, and for example, a drive source that applies driving force to the valve body may be adopted in which the valve body and a fixed iron core are arranged in a non-contact manner, and a magnet that generates a repulsive force with the solenoid consisting of the fixed iron core and the excitation coil is provided on the valve body.

[0059] In the above embodiment, a housing 10 consisting of a housing body 11, a first housing cover 12, and a second housing cover 13 was shown as a housing that defines the upstream and downstream chambers, which are fluid passages, and the valve seat. However, the embodiment is not limited to this, and other forms of housing may be used.

[0060] In the above embodiment, a configuration is shown in which a communication passage 40a is provided in the valve body 40 to connect the downstream chamber 11d and the back pressure chamber Bc1 in order to apply the pressure P2 of the downstream chamber 11d to the back surface 21a2 of the first diaphragm 20. However, the configuration is not limited to this, and a communication passage may be provided in the housing body.

[0061] As described above, the proportional control valve of the present invention can suppress changes in the downstream pressure (secondary pressure) in response to changes in the upstream pressure (primary pressure) without increasing the dimensional accuracy or assembly accuracy of each component. It can also achieve a smaller valve body diameter, a smaller drive source, and overall miniaturization and weight reduction. Therefore, it can be applied not only as a proportional control valve to control the flow rate of gas fluids, but is also useful in systems that control the flow rate of other fluids. [Explanation of symbols]

[0062] S axis Vd Vertical direction Vu valve unit Du drive unit (power source) F Driving force of the drive source 10 Housing 11 Housing body (housing) 11a Valve seat 11a1 circular hole D: Inner diameter of the circular hole defined by the valve seat. 11b Upstream room P1 Pressure in the upstream chamber 11c entrance 11d Downstream chamber Pressure in the downstream chamber of P2 11e exit 11f 1st opening 11j 2nd opening 12. First housing cover (housing) Bc1 back pressure chamber 13. Second housing cover (housing) Bc2 back pressure chamber 13e open hole 20. First diaphragm 21a1 front 21a2 back Ad1 Effective area of ​​the first diaphragm 30. Second diaphragm 31a1 front 31a2 back Ad2 Second diaphragm effective area 40 valve body 40a Communication path 41 Valve 41a Annular tapered surface Effective area of ​​the Av valve body 42 Rod section 42a Upper shaft portion (rod portion) 42b Fitting shaft portion (rod portion) 42c Lower shaft section (rod section) 42d Mating shaft portion (rod portion) 50 Frame members (drive source) 51 Outer yoke (frame component) 52 Inner yoke (frame component) 53 End yoke (frame component) 60 sleeves (power source) 70. Movable iron core (solenoid, drive source) 80. Excitation coil (solenoid, drive source) 90 Spring (Biasing Member)

Claims

1. A housing including an upstream chamber and a downstream chamber through which fluid passes, and a valve seat interposed between the upstream chamber and the downstream chamber, A first diaphragm is positioned within the housing such that the pressure from the upstream chamber acts on the front and the pressure from the downstream chamber acts on the back. A second diaphragm is positioned within the housing such that the pressure of the downstream chamber acts on the front and atmospheric pressure acts on the back, A valve body that moves in conjunction with the first diaphragm and the second diaphragm and is capable of seating and detaching from the valve seat, The valve body comprises a drive source that applies driving force to the valve body, The housing includes a back pressure chamber that the back surface of the first diaphragm faces, The valve body includes a communication passage that connects the downstream chamber and the back pressure chamber. A proportional control valve characterized by the following features.

2. P1 is the pressure in the upstream chamber, P2 is the pressure in the downstream chamber, and Ad is the effective area of ​​the first diaphragm. １ The effective area of ​​the second diaphragm is Ad ２ When the effective area of ​​the valve body is Av and the driving force of the drive source is F, the force balance equation in the direction of movement of the valve body is: P2=[F+(A]) １ --Rv・P1] / (A$) ２ ++A$ １ (-A6) Satisfying The proportional control valve according to feature 1.

3. The effective area Ad of the first diaphragm １ and the effective area Ad of the second diaphragm ２ are formed so as to satisfy Ad ２ / Ad １ > 1 The proportional control valve according to claim 2.

4. The valve body includes a valve portion having a conical surface that tapers toward the downstream chamber so as to be able to contact the valve seat, and a rod portion connected to the first diaphragm and the second diaphragm. The proportional control valve according to feature 3.

5. The drive source is a solenoid including a movable iron core that engages with the valve body and an excitation coil arranged around the movable iron core. A proportional control valve according to any one of features 1 to 4.

6. The valve body is positioned to move vertically and to sit on the valve seat by its own weight. The proportional control valve according to feature 5.

7. Includes a biasing member that biases the movable core toward the valve body, The proportional control valve according to feature 6.

8. The upstream chamber is located above the valve seat, and the downstream chamber is located below the valve seat. The proportional control valve according to feature 6.

9. The aforementioned housing is A housing body that defines a first opening that opens to the upstream chamber and a second opening that opens to the downstream chamber, respectively, toward both outward directions in the direction of movement of the upstream chamber, the downstream chamber, the valve seat, and the valve body, A first housing cover that covers the first diaphragm from the outside, which is positioned to close the first opening, Including a second housing cover that covers the second diaphragm from the outside, which is positioned to close the second opening, A proportional control valve according to any one of features 1 to 4.

10. The valve body is arranged to move vertically and to sit on the valve seat by its own weight. The upstream chamber is located above the valve seat, and the downstream chamber is located below the valve seat. The proportional control valve according to feature 9.

11. The housing body includes a fluid inlet leading to the upstream chamber and a fluid outlet leading to the downstream chamber. The inlet and outlet are positioned at the same height in the direction of movement of the valve body. The proportional control valve according to feature 9.

12. The first housing cover defines the back pressure chamber, The proportional control valve according to feature 9.

13. The second housing cover includes an opening that opens the back surface of the second diaphragm to the atmosphere. The proportional control valve according to feature 9.

Images