JP6719068B1 - Pressure reducing valve and upper diaphragm addition unit used for this - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid increasing the size of a diaphragm in the centrifugal direction. A valve box (8) connected to a valve body (5) through a valve rod (6) and having a lowermost diaphragm (7) that is displaced by pressure fluctuations in a secondary flow path (2), and an upper diaphragm having the same shape as the lowermost diaphragm (7). 9. One or more upper layer diaphragm addition units 13 are interposed between the spring cover 10 provided with a cover flange 10a capable of press-contacting the peripheral edge of 9 and the upper opening 29a of the unit 13 is closed by the upper layer diaphragm 9. A concave pressure chamber 29 connectable to the secondary side flow path 2 and a bottom plate 29b of the concave pressure chamber 29 are partitioned to cover the lowermost layer or other upper layer diaphragms 7 and 9, and these diaphragms 7 and 9 are opened as necessary. A diaphragm chamber 31 containing a valve spring for urging the valve in the valve direction is provided, and connecting valve rods 32 are projectingly provided above and below the upper diaphragm 9. The lower and other upper diaphragms 7, 9 are connected to the valve rod upper end 6a or the connecting valve rod upper end 32a protruding through. [Selection diagram] Fig. 3

Description

The present invention relates to a pressure reducing valve and an upper layer diaphragm adding unit used for the pressure reducing valve.

Patent Document 1 discloses a valve body that is provided so that a primary-side flow path and a secondary-side flow path communicate with each other through a valve port, and that is attachable to and detachable from a valve seat provided on the end face of the secondary-side opening of the valve port. And a valve box that is connected to the valve body via a valve rod and that includes a diaphragm that is displaced by pressure fluctuations in the secondary side flow path, and a cover flange that can press-contact the peripheral edge of the diaphragm. Disclosed is a pressure reducing valve including an adjusting spring for urging the valve body in the valve opening direction and a spring cover in which an adjusting screw is screwed up and down so as to press the adjusting spring in the valve opening direction. ..

This pressure reducing valve adjusts the urging force of the adjusting spring to the valve closing force of the valve body corresponding to the product of the pressure receiving area of the diaphragm and the secondary side pressure by the vertical position by screwing the adjusting screw into the spring cover. The diaphragm responds to the pressure drop on the secondary side due to the use of tap water and opens the valve body, reducing the high-pressure tap water supplied from the primary side to the desired set pressure through the valve port and to the secondary side. It is designed to flow in.

JP, 2013-127803, A

By the way, in the pressure reducing valve having the above-mentioned configuration, when the valve diameter is increased to increase the flow rate, the pressure receiving area of the valve element is inevitably expanded, and the valve opening force for the valve element is increased. As described above, the diameter of the diaphragm must be increased, so that the pressure reducing valve is expanded in the centrifugal direction of the diaphragm.

If this happens, it will interfere with other pipes and other equipment adjacent to the pipe where the pressure reducing valve is installed, making it difficult to secure the installation space for the expanded pressure reducing valve, and the position where the pressure reducing valve is attached to the pipe. This leads to troubles such as changing the posture.

Therefore, in the present invention, the valve closing force with respect to the valve opening force of the valve body, which corresponds to the product of the pressure receiving area of the valve body and the primary side pressure, which is increased by the diameter expansion of the valve opening, is used without increasing the diameter of the diaphragm. We provide a pressure reducing valve that multi-stages the diaphragms and prevents the diaphragms from becoming larger in the centrifugal direction according to the product of the total area of each diaphragm and the secondary pressure, and the upper layer diaphragm additional unit used for this. The purpose is to

In view of the above problems, the pressure reducing valve according to the present invention is provided so that the primary side flow passage and the secondary side flow passage communicate with each other through a valve opening, and a valve seat provided on the end surface of the secondary side opening of the valve opening. A valve box having a detachable valve body, a lowermost diaphragm that is connected to the valve body through a valve rod, and that is displaced by pressure fluctuations in the secondary side flow path; and a valve box having the same shape as the lowermost diaphragm A cover flange that can press the peripheral edge of the upper diaphragm is installed, and an adjustment spring that urges the upper diaphragm in the valve opening direction is installed inside, and the adjustment screw is moved up and down to press the adjustment spring in the valve opening direction. A spring cover freely screwed in, and at least one or more upper layer diaphragm additional units are interposed and connected between the spring cover and the valve box. The upper layer diaphragm additional unit has an upper opening closed by the upper layer diaphragm. In addition, a concave pressure chamber connectable to the secondary side flow passage and a bottom plate of the concave pressure chamber, which is partitioned by the bottom plate of the concave pressure chamber or another upper layer diaphragm, is capped, and the lowermost layer diaphragm or another upper layer diaphragm is formed. A diaphragm chamber containing a valve spring for urging the valve body in the valve opening direction is provided, and connecting valve rods project through the upper and lower diaphragms, and the lower end of the connecting valve rod is slidable in the center of the bottom plate. It is characterized in that it can be connected to the upper end of a valve rod which is watertightly inserted and projects through the lowermost diaphragm or the upper end of a connecting valve rod which projects through another upper diaphragm.
Further, the upper layer diaphragm adding unit used for the pressure reducing valve according to the present invention is configured such that at least one or more units are interposed and connected between the valve box and the spring cover to configure the pressure reducing valve, and the upper layer diaphragm is opened upward. with parts are closed, the concave pressure chamber connectable to the secondary-side flow path, is defined by the bottom plate of the recess-type pressure chamber with the lowermost diaphragm or other upper diaphragm to be bears, lowermost diaphragm or other And a diaphragm chamber for accommodating a valve spring for urging the upper diaphragm in the valve opening direction, and a connecting valve rod is projected through the upper and lower diaphragms, and the lower end of the connecting valve rod is located at the center of the bottom plate. It is characterized in that it can be slidably inserted in a watertight manner and connected to the upper end of a valve rod that projects through the lowermost diaphragm or the upper end of a connecting valve rod that projects through another upper diaphragm.

In short, the present invention comprises at least one upper layer diaphragm addition unit interposed between the spring cover and the valve box of the pressure reducing valve as described above, and the upper layer diaphragm addition unit is the upper layer diaphragm and has an upper opening. Is closed and a concave pressure chamber connectable to the secondary side flow passage and a bottom plate of the concave pressure chamber are partitioned to cover the lowermost layer diaphragm or other upper layer diaphragm, and the lowermost layer diaphragm or other A diaphragm chamber containing a valve spring for urging the upper diaphragm in the valve opening direction is provided, and a connecting valve rod is projected through the upper and lower diaphragms, and the lower end of the connecting rod is slid on the center of the bottom plate. Since it can be freely water-tightly inserted and connected to the upper end of the valve rod that protrudes through the lowermost diaphragm or the upper end of the connecting valve rod that protrudes through another upper diaphragm, it is possible to increase the valve diameter to increase the flow rate. Since the pressure receiving area of the valve body is inevitably expanded and the valve opening force against the valve body is increased, it is necessary to increase the size of the diaphragm to accommodate this valve opening force. For the valve, the existing diaphragms of the same shape (lowermost layer and upper layer) are multi-staged without expanding the diaphragm as in the past, and the product of the pressure-receiving area of the valve body and the primary pressure increases due to the expansion of the valve opening. The valve closing force against the valve opening force corresponding to the above is corresponded by the product of the total area of the lowermost diaphragm and the upper diaphragm and the secondary pressure, thus avoiding the enlargement of the pressure reducing valve in the centrifugal direction of the diaphragm. To do.
Therefore, according to the present invention, in the conventional pressure reducing valve whose diameter is expanded in the centrifugal direction of the diaphragm, the expanded diameter portion interferes with another pipe or other equipment adjacent to the pipe to which the pressure reducing valve is attached, and therefore the expansion of the expansion valve is prevented. It is possible to solve the conventional problems that it is difficult to secure a space for installing the reduced pressure reducing valve, and it takes time and labor to change the mounting position and the posture of the pressure reducing valve with respect to the pipe.
In addition, when multiple diaphragms are used, by using the same upper layer diaphragm addition unit, the assembly can be done relatively easily, and the number of newly developed parts is reduced, so the cost is reduced accordingly. The practical effect is great.

It is a longitudinal cross-sectional view of the pressure reducing valve according to the present invention in a closed state. It is a longitudinal cross-sectional view of the same valve open state. It is an exploded sectional view same as the above. It is a longitudinal cross-sectional view of a valve closed state showing another example. It is a longitudinal cross-sectional view of the same valve open state. It is an exploded sectional view same as the above. It is sectional drawing of the conventional pressure reducing valve.

An embodiment of the present invention will be described below with reference to the drawings.
The pressure reducing valve according to the present invention shown in FIGS. 1 to 6 is provided so that a primary-side flow passage 1 and a secondary-side flow passage 2 that are on the same straight line communicate with each other via a valve opening 3, and The valve body 5 is detachably attached to the valve seat 4 provided on the end face 3a of the secondary side opening, and is connected to the valve body 5 via the valve rod 6 and is displaced by the pressure fluctuation of the secondary side flow passage 2. A valve box 8 having a lowermost diaphragm 7 and a cover flange 10a capable of press-contacting a peripheral edge of an upper diaphragm 9 of the same shape as the lowermost diaphragm 7 are provided, and the upper diaphragm 9 is biased toward the valve opening direction of the valve body 5. At least one spring cover 10 is provided between the spring cover 10 and the valve box 8 in which a spring 11 is installed, and an adjusting screw 12 is screwed up and down so as to press the adjusting spring 11 in the valve opening direction. It is constituted by interposing and connecting the upper layer diaphragm adding unit 13 of.

As shown in FIG. 7, the pressure reducing valve according to the present invention is a conventional pressure reducing valve including a valve box 8 and a spring cover 10 equipped with one or more upper layer diaphragm adding units 13.

The valve box 8 is provided with an inlet 14 and an outlet 15 on its left and right sides, respectively, and is internally provided with a primary-side flow passage 1 and a secondary-side flow passage 2 which communicate with the inlet 14 and the outlet 15, respectively.

At the center of the valve box 8, a partition wall 16 is provided which divides the primary-side flow path 1 and the secondary-side flow path 2 into upper and lower parts, and a valve port 3 is opened in a horizontal portion of the partition wall 16 to form the both flow paths 1. 2, the flow paths 1 and 2 of the inlet 14 and the outlet 15 are formed in a Z shape in the illustrated example.

A circular dish-shaped concave pressure chamber (hereinafter referred to as a pressure detection chamber) 17 is provided in the upper portion of the valve box 8 so as to surround a flange 17a and whose upper opening is closed by the lowermost diaphragm 7.

The pressure detection chamber 17 is provided with a circular opening at the center of its lower portion (corresponding to a portion corresponding to the valve opening 3 on the upper portion of the valve box 8) and communicates with the primary side flow passage 1, and is continuously connected downward to the opening. A tubular portion 18 having a predetermined length is provided.

The lower peripheral wall of the tubular portion 18 is hung so as to be continuous with the partition wall 16 of the primary side flow passage 1 and the secondary side flow passage 2, and is one of the parts of the lower peripheral wall facing the primary side flow passage 1. The portion is opened so as to communicate with the primary side flow passage 1, and a portion adjacent to the lower portion of the pressure detection chamber 17 and the cylindrical portion 18 corresponding to the secondary side flow passage 2 in the partition 16 is opened to form the secondary side. The flow path 2 and the pressure detection chamber 17 are communicated with each other.

Further, a valve rod 6 having a cylindrical portion 18 and a valve opening 3 inserted therein is formed at the center of the lowermost diaphragm 7, and a disc-shaped valve for opening and closing the valve opening 3 is formed at the lower end of the valve rod 6. A body 5 is provided.

The valve body 5 is detachably provided on a valve seat 4 projecting in an annular shape on the end face 3a of the secondary opening of the valve opening 3 so as to receive the primary pressure in the valve opening direction. The opening degree is controlled by the displacement of.

Further, the valve body 5 has a disc-shaped synthetic rubber valve portion 5a, which has a circular dish shape in which only the upper surface of the valve portion 5a facing the valve seat 4 (upper surface in the figure) is opened. It is loaded in the valve body cover 5b and retains the shape of the valve portion 5a.

A piston 19 which slides on the inner wall of the tubular portion 18 is provided on the upper portion of the valve rod 6 so as to project outward, and an O-ring 20 is attached to a groove formed around the piston 19 so that the primary side flow The passage 1 and the pressure detection chamber 17 are partitioned in a watertight manner.

The effective pressure receiving area of the piston 19 is set to be slightly larger than the effective pressure receiving area on the primary side of the valve body 5.

The lowermost diaphragm 7 provided directly above the piston 19 has its upper and lower surfaces sandwiched by a disk-shaped diaphragm retainer 21 and a diaphragm receiver 22.

The diaphragm retainer 21 joined to the upper surface of the lowermost diaphragm 7 penetrates and projects through the lowermost diaphragm 7, and the upper end 6a of the valve rod 6 screwed with a male screw penetrates through the upper end 6a of the valve rod and the washer 23. A collar 24 having a height is inserted so that the valve rod upper end 6a projects a predetermined length from the collar 24 (see FIGS. 3 and 6).

The diaphragm receiver 22 joined to the lower surface of the lowermost layer diaphragm 7 is formed integrally with the valve rod 6 and has a diameter larger than that of the tubular portion 18. With the lowermost layer diaphragm 7 displaced to the lowermost limit, the diaphragm receiver 22 is formed. The receiver 22 is seated on the end surface of the upper opening of the tubular portion 18 to regulate the lift of the valve body 5 in this state.

A guide rod 25 is vertically provided at the center of the lower portion of the valve body 5, and the guide rod 25 is slidably fitted in a cylindrical recess 26 formed in the bottom of the valve box 8.

The spring cover 10 is formed in a hat shape by surrounding a cover flange 10a at the lower opening end, and a projecting portion 10b with a female screw is projectingly provided at the center of the upper end thereof, and a seal washer 27 is provided on the projecting portion 10b. The adjusting screw 12, which is a bolt into which the lock nut 28 is screwed, is screwed into the spring cover 10 from above the convex portion 10b.

The upper layer diaphragm adding unit 13 (hereinafter, simply referred to as a unit 13) has a dish-shaped concave pressure chamber 29 that is connectable to the secondary side flow passage 2 while the upper opening 29a is closed by the upper layer diaphragm 9. The lowermost diaphragm 7 or other upper diaphragm 9 is partitioned in a watertight manner by being partitioned by the bottom plate 29b of the concave pressure chamber 29, and the lowermost diaphragm 7 or other upper diaphragm 9 is opened as needed. A hat-type diaphragm chamber 31 containing a valve spring 30 for urging in the valve direction is provided, a connecting valve rod 32 is projectingly provided above and below the upper diaphragm 9, and a lower end 32b of the connecting valve rod 32 is located at the center of the bottom plate 29b. It is slidably water-tightly inserted and can be connected to the valve rod upper end 6a protruding through the lowermost layer diaphragm 7 or the upper end 32a of the connecting valve rod 32 protruding through the other upper layer diaphragm 9.

Further, the unit 13 has an upper flange 13a and a lower flange 13b projecting from the upper opening peripheral edge of the concave pressure chamber 29 and the lower opening edge of the diaphragm chamber 31, respectively. The upper flange 13a has a cover flange of the spring cover 10. 10a or the lower flange 13b of the other unit 13 is joined, the upper flange 13a of the other unit 13 of the flange 17a of the valve box 8 is joined to the lower flange 13b, and the flanges 13a, 13b joined in this way , 10a, 17a are joined and fixed using a fastening member (not shown) such as a bolt or a nut.

In the unit 13, the insertion port 33 of the connecting valve rod 32 provided on the bottom plate 29b is formed to have a diameter smaller than that of the valve port 3, and the insertion port 33 is provided with a cylindrical portion 33a of a predetermined length continuously downwardly. A piston 34 that slides on the inner wall of the cylindrical portion 33a is provided by expanding the lower end 32b of the connecting valve rod 32, and an O-ring 35 is attached to a concave groove formed around the piston 34 to form a concave pressure chamber 29. The diaphragm chamber 31 is partitioned in a watertight manner.

The upper diaphragm 9 provided directly above the piston 34 has upper and lower surfaces thereof sandwiched by a diaphragm retainer 36 and a diaphragm receiver 37.

The diaphragm retainer 36 joined to the upper surface of the upper diaphragm 9 is penetrated by the upper end 32a of the connecting valve rod threaded with a male screw, and the upper end 32a of the connecting valve rod is inserted with a washer 38 and a collar 39 of a predetermined height. The upper end 32a of the connecting valve rod 32 projects from the valve 39 by a predetermined length (see FIGS. 4 to 6).

The diaphragm receiver 37 joined to the lower surface of the upper diaphragm 9 is formed integrally with the connecting valve rod 32 and has a diameter larger than that of the cylindrical portion 33a. With the upper diaphragm 9 displaced to the lowest limit, the diaphragm receiver 37 is formed. 37 is set so as to be seated on the upper end surface of the insertion port 33.

In addition, only in the unit 13 connected to the spring cover 10, the nut 40 is screwed onto the upper end 32a of the connecting valve rod without inserting the washer 38 and the collar 39 into the upper end 32a of the connecting valve rod (FIGS. 3 and 6). reference).

Then, the flange 17a of the valve box 8 and the lower flange 13b of the unit 13 are joined via the lowermost layer diaphragm 7 and fastened by a fastening member, and the valve rod upper end 6a protruding upward from the lowermost layer diaphragm 7 is connected to the connecting valve. The valve rod 6 and the connecting valve rod 32 are integrally connected on the same vertical axis by being inserted into a female screw threaded on the bottom surface of the rod lower end 32b (piston 34).

At this time, when the valve spring 30 is installed inside the diaphragm chamber 31 (see FIGS. 4 to 6), the valve rod upper end 6a is loosely inserted into the valve spring 30 and the top plate of the diaphragm chamber 31 of the unit 13 ( A valve spring 30 is interposed between the bottom plate) 29b and a diaphragm retainer 21 provided on the upper surface of the lowermost diaphragm 7 so that the elastic force of the valve spring 30 acts on the upper surface of the lowermost diaphragm 7.

Note that the valve spring 30 uses the urging force of the adjusting spring 11 as a total pressure receiving area obtained by combining the total pressure receiving area of the upper diaphragm 9 and the pressure receiving area of the lowermost diaphragm 7 according to the number of units 13 equipped in the pressure reducing valve. If it can be adjusted so as to correspond to the valve closing force of the valve body 5 corresponding to the product of the area and the secondary pressure, it is not necessary to install it in the diaphragm chamber 31 as shown in FIGS. Since the upper diaphragm 9 increases in accordance with the number of units 13 used, if the urging force of the adjusting spring 11 cannot deal with the above valve closing force, as shown in FIGS. The unit 30 is appropriately housed and installed in the diaphragm chamber 31 of the unit 13.

When one unit 13 is interposed between the spring cover 10 and the valve box 8, the spring attached to the lower end of the adjusting screw 12 with the unit 13 mounted on the valve box 8 is connected as described above. The adjusting spring 11 is compressed and interposed between the receiver 41 and the diaphragm retainer 36 provided on the upper surface of the upper diaphragm 9 of the unit 13 so that the elastic force of the adjusting spring 11 acts on the upper surface of the upper diaphragm 9 (FIG. 1 to 3).

The spring receiver 41 is provided with a recess 41a for receiving the tip of the adjusting screw 12 at the center of the upper surface of a circular substrate having a predetermined diameter, and at the center of the lower surface thereof a bulging portion 41b having a flat cylindrical shape. Is fitted on the upper end of an adjusting spring 11 that biases the valve body 5 in the valve closing direction.

Further, in the case of interposed connecting two or more groups of unit 13 between the spring cover 10 and the valve body 8, similarly to the matters described in paragraphs [0035], while loaded on connecting unit 13 to the valve box 8 , One or more other units 13 are stacked on the unit 13.

That is, the upper flange 13a of the lower unit 13 on the valve box 8 and the lower flange 13b of the upper unit 13 stacked on it are joined via the lower upper layer diaphragm 9 to form a fastening member. At the same time, the connecting valve rod upper end 32a protruding upward from the lower upper layer diaphragm 9 is screwed into the female screw of the connecting valve rod lower end 32b (piston 34) of the upper upper layer diaphragm 9, and one or more units are provided on the valve box 8. Units 13 are stacked in multiple stages, and the valve rod 6 and the connecting valve rod 32 of each unit 13 are integrally connected on the same vertical axis, and the uppermost unit 13 has the upper surface of the upper diaphragm 9 of the unit 13. The adjusting spring 11 is compression-inserted between the diaphragm retainer 36 and the spring receiver 41 of the spring cover 10 so that the elastic force of the adjusting spring 11 acts on the upper surface of the upper diaphragm 9 to cap the spring cover 10.

Then, the adjusting screw 12 is moved up and down to adjust the biasing force of the adjusting spring 11 and the valve spring 30 used, and the displacement of the lowermost diaphragm 7 and the upper diaphragm 9 is adjusted.

Further, the concave pressure chamber 29 of each unit 13 has a secondary side communication passage 42 connected to the secondary side flow passage 2 so as to exert a secondary side pressure on the lower surface of the upper layer diaphragm 9. When the pressure reducing valve is equipped with a plurality of units 13, each of the secondary side communication passages 42 connected to each concave pressure chamber 29 may be connected to the secondary side flow passage 2, and as shown in FIGS. In addition, the secondary side communication passage 42 connected to the secondary side flow path 2 may be branched and connected to each concave pressure chamber 29.

The pressure reducing valve configured as described above is configured such that the pressure detecting chamber 17 communicating with the secondary side flow passage 2 in the valve box 8 and the concave pressure communicating with the secondary side flow passage 2 via the secondary side communication passage 42. The upward pressure (closing direction) on the lowermost diaphragm 7 and the upper diaphragm 9 due to the secondary pressure of the chamber 29, and only the adjusting spring 11 in the pressure reducing valve shown in FIGS. 1 to 3, the pressure reducing valve shown in FIGS. Then, the downward force (valve opening direction) of the adjustment spring 11 and the valve spring 30 is balanced to control the opening degree of the valve body 5 and maintain the secondary pressure at a certain pressure lower than the primary pressure. ..

Further, according to the pressure reducing valve of the present invention, when the valve diameter is increased in order to increase the flow rate, the pressure receiving area of the valve body is inevitably expanded and the valve opening force for the valve body is increased. In contrast to the conventional pressure reducing valve, which has to be upsized, such as the diaphragm having to have a larger diameter, the diaphragm 7 of the same shape (the lowermost layer and the uppermost layer) can be manufactured without expanding the diameter of the diaphragm as in the past. , 9 in multiple stages, the valve closing force against the valve opening force of the valve body 5 corresponding to the product of the pressure receiving area of the valve body 5 and the primary side pressure, which increases due to the expansion of the diameter of the valve opening 3, is applied to the lowermost diaphragm 7 and the upper layer. The product of the total area of the diaphragm 9 and the pressure on the secondary side corresponds to the increase in size of the pressure reducing valve in the centrifugal direction of the diaphragm.

As a result, in the conventional pressure reducing valve whose diameter is expanded in the centrifugal direction of the diaphragm, the expanded diameter portion interferes with another pipe or other equipment adjacent to the pipe in which the pressure reducing valve is installed. It is possible to solve the conventional problems that it is difficult to secure a space for installing the valve, and it takes time and effort to change the mounting position and posture of the pressure reducing valve with respect to the pipe.

Further, when a plurality of diaphragms are used in a laminated manner, by using the same unit 13, the assembly can be performed relatively easily, and the number of newly developed parts is reduced, so that the cost can be reduced accordingly. You can

1 Primary side flow path 2 Secondary side flow path 3 Valve port
3a Secondary side opening end face 4 Valve seat 5 Valve body 6 Valve rod
6a Upper end 7 Lowermost layer diaphragm 8 Valve box 9 Upper layer diaphragm
10 spring cover
10a Cover flange
11 Adjustment spring
12 Adjustment screw
13 Upper diaphragm additional unit
29 concave pressure chamber
29b Bottom plate
30 valve spring
31 diaphragm chamber
32 connecting valve rod
32a upper end
32b bottom

Claims (2)

A valve body which is provided so that the primary-side flow passage and the secondary-side flow passage communicate with each other through a valve opening, and which is detachable from a valve seat provided on the end face of the secondary-side opening of the valve opening, and the valve body. While being connected via a valve rod, a valve box having a lowermost diaphragm that is displaced by pressure fluctuations in the secondary side flow path, and a cover flange that can press-contact the upper diaphragm periphery of the same shape as the lowermost diaphragm, A spring cover, which is internally equipped with an adjusting spring for urging the upper diaphragm in the valve opening direction, and in which an adjusting screw is screwed up and down so as to press the adjusting spring in the valve opening direction, and the spring cover and the valve box. And at least one upper-layer diaphragm adding unit is interposed between the upper-layer diaphragm adding unit and the upper-layer diaphragm adding unit, and the upper opening is closed by the upper-layer diaphragm. A pressure chamber and a bottom plate of the concave pressure chamber are partitioned to cover the lowermost diaphragm or other upper diaphragm, and a valve spring for urging the lowermost diaphragm or other upper diaphragm in the valve opening direction of the valve body. An inner diaphragm chamber is provided, and connecting valve rods are projectingly provided above and below the upper diaphragm, and the lower end of the connecting valve rod is slidably inserted in the center of the bottom plate in a watertight manner so that the valve rod protrudes through the lowermost diaphragm. A pressure reducing valve characterized in that it can be connected to the upper end of a connecting valve rod protruding through the upper end of the above or other upper layer diaphragm. A valve body which is provided so that the primary-side flow passage and the secondary-side flow passage communicate with each other through a valve opening, and which is detachable from a valve seat provided on the end face of the secondary-side opening of the valve opening, and the valve body. While being connected via a valve rod, a valve box having a lowermost diaphragm that is displaced by pressure fluctuations in the secondary side flow path, and a cover flange that can press-contact the upper diaphragm periphery of the same shape as the lowermost diaphragm, An adjusting spring for urging the upper diaphragm in the valve opening direction is provided inside, and at least one adjusting screw is inserted between the adjusting spring and the spring cover so as to press the adjusting spring in the opening direction. An upper layer diaphragm additional unit that constitutes a pressure reducing valve by interposing and connecting the above, wherein the upper layer diaphragm additional unit has an upper opening portion closed by the upper layer diaphragm and a concave pressure connectable to a secondary side flow passage. The chamber and the bottom plate of the concave pressure chamber are partitioned to cover the lowermost diaphragm or other upper diaphragm, and a valve spring for urging the lowermost diaphragm or other upper diaphragm in the valve opening direction is installed. A diaphragm chamber is provided, and connecting valve rods are projectingly provided above and below the upper diaphragm, and the lower end of the connecting valve rod is slidably inserted in the center of the bottom plate in a watertight manner so that the valve rod protrudes through the lowermost diaphragm. An upper-layer diaphragm adding unit, which can be connected to the upper end of a connecting valve rod that protrudes through the upper end or another upper-layer diaphragm.

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