JP2002039489A - Water hammer preventing device for uniaxial decompression valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To absorb impact waves generated with quick close of a terminal unit in the downstream of a uniaxial decompression valve without influencing the sensitivity of the decompression valve while the valve is arranged as installed without involving any restriction on the connection of the terminal unit such as a shower. SOLUTION: The uniaxial decompression valve A has a flow passage for a fluid from the primary side X to the secondary side Y inside the body 1, and a resilient piece c such as foaming rubber whose volume shrinks with a pressure is attached to the passage in its appropriate position ranging from a pressure regulating valve part consisting of the a cylindrical valve 20 of a pressure adjusting mechanism W and a ring-shaped valve seat 3 mating with the valve 20 to the connection hole 11 on the secondary side Y.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a single-shaft pressure reducing valve which is a kind of a pressure reducing valve, and when a valve mechanism of a water supply device connected to a secondary side of the pressure reducing valve has a sudden valve closing, A single-shaft pressure reducing valve that prevents impulse waves propagating to the side from suddenly closing the pressure regulating valve of the single-shaft pressure reducing valve and causing a secondary water hammer phenomenon originating from the single-shaft pressure reducing valve Water hammer prevention device.

[0002]

2. Description of the Related Art An impulse wave of a fluid generated when a valve mechanism connected to a secondary side of a pipe of a water supply apparatus is rapidly closed is propagated to a primary side, so that each apparatus connected to the primary side is transmitted to the primary side. As means for preventing the influence which may be exerted, as shown in FIG. 1, silicon rubber or the like having a high compressive deformation capability is mainly provided on the inner wall surface in the middle of a pipe b to which a terminal device a such as a faucet is connected. A means for lining an elastic body (or cushioning material) c to absorb shock waves by compressive deformation of the elastic body c is known from Japanese Patent Application Laid-Open No. Hei 3-186691.

[0003] Further, as water pressures have been increased, the use of single-shaft pressure reducing valves in the water meter section of each home, the connection section of the water supply equipment, the installation section of the shower, and the like has increased the number of water pressures that are easy to use. .

[0004] For this reason, an impulse wave generated when the on-off valve of the water supply terminal such as a faucet is rapidly opened and closed is generated on the secondary side of the single-shaft pressure reducing valve provided in the water supply equipment. Is propagated to the single-shaft pressure reducing valve, the pressure regulating valve thereof is rapidly closed, and a secondary water hammer using the single-shaft pressure reducing valve as a generation source may be generated.

[0005] For this reason, as means for preventing the generation of a secondary water hammer using the single-shaft pressure reducing valve as a generation source, there is a means filed by the present applicant as Japanese Patent Application Laid-Open No. 11-131830.

As shown in FIGS. 2 and 3, this means has a cylindrical shape having a connection port 10 connected to the primary side X at one end and a connection port 11 connected to the secondary side Y at the other end. The valve body 12 is formed in the body 1 of the cylindrical body 2, and the cylindrical body 2 formed in the lumen 2 in the water passage 2 a is positioned in the valve chamber 12 so that the axial direction thereof is along the axial direction of the valve chamber 12. A cylindrical valve portion 20 is provided at an end of the cylindrical body 2 on the primary side, and the valve portion 20 is located at a position closer to the primary side X of the valve portion 20. An annular valve seat 3 which abuts with 20 is fixedly mounted on the body 1 and flows into a pressure-sensitive chamber z communicating with a secondary-side channel u at a secondary-side end of the tubular body 2. A pressure-sensitive plate 21 that moves in the axial direction due to a pressure change on the secondary side is provided integrally connected,
The pressure-sensitive plate 21 is urged to be pushed out to the secondary side by the spring 4 to constitute the uniaxial pressure-reducing valve A, and the cylindrical body 2 to be inserted into the valve chamber 12 formed in the body 1 lumen. Secondary side Y
Is provided at an end thereof with a cylindrical portion 22 that fits into a secondary flow path u formed in the inner cavity of the body 1, and an outer circumferential surface of the cylindrical portion 22 and an inner circumferential surface of the secondary flow channel u are formed. In between, the pressure-sensitive chamber z of the secondary flow path u
A narrow gap v is formed to restrict the flow of water to the secondary side, and an impulse wave generated when the terminal device closes abruptly on the secondary side propagates and the secondary side flow of the uniaxial pressure reducing valve A When the pressure reaches the inside of the path u, the pressure of the impulse wave is restricted from flowing into the pressure-sensitive chamber z by the narrow gap v, and the pressure-sensitive plate 21 is rapidly pushed, so that the pressure regulating valve is a valve. This is means for preventing the part 20 from closing suddenly.

[0007]

The conventional means for preventing the water hammer is to dispose a buffer material having a high compressive deformation capacity on the inner wall surface of the pipe of the water supply device, and to provide a valve mechanism at the terminal side of the water supply device. Is suddenly closed and an impulse wave occurs,
In the means for absorbing by the elastic body, the end device is, for example, as shown in FIG. 4, a one-touch type shower e which is opened by actuation of a push button type operation part d.
In this case, when the single-shaft pressure reducing valve A is connected to the pipe b so as to cope with the increasing water pressure, there is a problem that the connection and assembly of the single-shaft pressure reducing valve A and the shower e are restricted.

This is because the single-shaft pressure reducing valve A is usually set to a shower e
However, when the shower e is connected in this manner, there is a problem that it is difficult to install the elastic body c lining the pipe b.

[0009] From this, the elastic body c is, for example,
As shown in FIG. 4, the mixing faucet MV to which the uniaxial pressure reducing valve A is connected on the downstream side is installed so as to be lined in the middle of the piping b on the upstream side. The uniaxial pressure reducing valve A increases the impulse wave generated by the sudden closing of the shower e, and the impulse propagates to the mixing faucet MV. Will not be.

As shown in FIGS. 2 and 3, in the means for incorporating a mechanism for absorbing an impact wave generated on the secondary side in the body 1 of the single-shaft pressure reducing valve A, an end of a shower or the like is used. The restrictions on the connection of the devices are eliminated, and the connection of the terminal devices can be easily performed.However, the absorption of the pressure wave is reduced by narrowing the flow path from the secondary flow path u to the pressure-sensitive chamber z, Since the pressure wave is not easily propagated and the rapid closing of the valve section 20 which is the pressure regulating valve operated by the pressure sensitive plate 21 is suppressed, the sensitivity of the pressure regulating valve due to the operation of the pressure sensitive plate 21 is reduced. A problem arises in that the performance of the single-shaft pressure reducing valve A is reduced due to dulling.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem which has occurred in the conventional means, and has been made in view of the above-described circumstances, while allowing a uniaxial pressure reducing valve to be incorporated without restricting the connection of a terminal device such as a shower. It is another object of the present invention to provide a new means for absorbing shock waves generated by sudden closing of a terminal device downstream of a single-shaft pressure reducing valve without affecting the sensitivity of the single-shaft pressure reducing valve.

[0012]

According to the present invention, as a means for achieving the above object, a single-shaft pressure reducing valve A in which a pressure adjusting mechanism W is housed in a cylindrical body 1 is provided. 1, a cylindrical valve portion 20 of the pressure regulating mechanism W of the flow path through which the fluid flows from the primary side X to the secondary side Y
An elastic member c such as foamed rubber whose volume is reduced by pressure is attached to an appropriate portion between the pressure regulating valve portion of the valve member 3 and the annular valve seat 3 opposed thereto and the connection port 11 on the secondary side Y, and A uniaxial pressure reducing valve characterized in that the pressure of the shock wave generated on the side Y is absorbed by contraction of an elastic body c provided in a flow path in the body 1 to prevent the generation of a secondary water hammer. The present invention proposes a water hammer prevention device.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the means of the present invention, an impact caused by a sudden closing of a secondary end device in a body of a single-shaft pressure reducing valve without affecting the operation of a pressure adjusting mechanism of the single-shaft pressure reducing valve. A pressure absorbing means for absorbing a strong wave is incorporated.

For this reason, the single-shaft pressure reducing valve A may have the same basic structure as the conventional single-shaft pressure reducing valve. That is, as shown in FIG. 5, a cylindrical body 1 is formed.
Is provided with a connection port 10 connected to the primary side X at one end thereof, and a connection port 11 connected to the secondary side Y at the other end side thereof. Valve chamber 1 along the direction
2, a primary side flow path 10a for connecting the connection port 10 to the valve chamber 12 is formed in the lumen of the connection port 10 on the primary side X of the body 1, and the connection port on the secondary side Y is formed. A secondary channel u is formed in the lumen of the valve 11 so that the connection port 11 communicates with the valve chamber 12.

In the valve chamber 12, the cylindrical body 2 formed in the axial flow passage 2 a is formed so that the axial direction thereof is oriented along the axial direction of the valve chamber 12 in the axial direction. At the end of the primary side X of the cylindrical valve 2 which is movably charged, a cylindrical valve-shaped valve portion 20 serving as a side seal valve is formed, and at the end of the secondary side Y, an outer peripheral edge has a valve chamber. A pressure-sensitive plate 21 slidably in contact with the inner peripheral surface of the cylindrical body 12 is integrally or integrally connected to the cylindrical body 2 and installed.
A pressure-sensitive chamber z partitioned by a pressure-sensitive plate 21 is formed at an end of the valve chamber 12 on the secondary side Y, and a spring 4 for urging the pressure-sensitive plate 21 to be pushed to the secondary side Y is connected to the pressure-sensitive plate 21.

A valve seat 30 is provided at the end of the primary side X of the valve chamber 12 in the body 1, and the valve seat 30 is formed at the end of the primary side X of the tubular body 2. The valve seat 3 facing the valve-shaped valve portion 20 is formed in a ring shape and attached, whereby tap water flowing from the connection port 10 on the primary side X is
The valve seat 3 and the valve portion 2 are formed from the water passage holes 31 on the periphery of the valve seat fitting 30.
When the air flows through the water passage 2a in the lumen of the cylindrical body 2 and flows from the secondary passage u to the secondary Y through the interval between 0 and 0, the pressure on the secondary increases. Then, the pressure sensitive plate 21 facing the pressure sensitive chamber z moves to the primary side X against the spring 4 and
The distance between the valve portion 20 at the end and the valve seat 3 is reduced, the amount of water flowing through the valve portion 20 is reduced, and the pressure adjusting mechanism W that maintains the pressure on the secondary side Y constant is configured. I do.

As described above, a single-shaft in which the pressure adjusting mechanism W composed of the pressure-sensitive plate 21, the cylindrical valve portion 20, and the annular valve seat 3 is incorporated in the valve chamber 12 formed in the bore of the body 1. The pressure reducing valve A is configured, and among the flow paths of the fluid formed in the lumen of the body 1 of the pressure reducing valve A, a secondary side flow path u which is a part located on the secondary side from the pressure adjusting mechanism W. On the inner wall of
An elastic body c having a high compressive deformation capacity and made of, for example, foamed rubber such as silicon rubber is provided so as to be lined.

The elastic body c is mounted on the inner wall surface of the secondary flow path u by forming the elastic body c into a thick sheet and directly bonding the elastic body c to the inner wall surface of the secondary flow path u. Good,
As shown in FIG. 6, the diameter of the wall of the secondary flow path u formed between the pressure-sensitive chamber z in the lumen of the body 1 and the end face of the connection port 11 on the secondary side is entirely or partially enlarged. A portion k may be formed, and an elastic body c such as foamed rubber may be formed into the enlarged diameter portion k in a shape corresponding to the enlarged diameter portion k and then loaded.

At this time, the enlarged diameter portion k formed on the inner wall surface of the secondary flow path u has a pressure-sensitive chamber z of the secondary flow path u as shown in FIG.
On the side, a throttle flange 14 having a diameter smaller than the diameter of the pressure-sensitive chamber z.
It is effective to increase the diameter while leaving the inner diameter of the secondary flow path u to be equal to the inner diameter of the secondary flow path u in order to facilitate the work of loading the elastic body c.

As shown in FIG. 8, the elastic body c loaded in the enlarged diameter portion k formed on the inner wall surface of the secondary flow path u is connected to the outer end side of the connection port 11 of the body 1 as shown in FIG. An enlarged diameter portion formed in a cylindrical shape with a flange provided with a flange portion f joined to the outer end surface of the secondary side Y, and formed so as to enlarge the inner wall surface of the secondary flow path u. k, and may be mounted in a state of being fixed by fitting of a fitting portion formed between the flange portion f and the end face of the connection port 11.

This elastic body c is, as shown in FIG.
A pipe having a diameter corresponding to the inner diameter of the secondary flow path u before forming the enlarged-diameter portion k so that the secondary flow path u is formed on the inner peripheral side by a thin plate of a metal material or a resin material. A cylindrical or cylindrical holder 5 having a flange 50 at one end in the axial direction is formed, and the elastic body c is fitted around the outer periphery of the body 51 so as to be wound therearound. In some cases, the holding tool 5 in the state is fitted to the enlarged diameter portion k formed on the inner wall surface of the secondary flow path u, and the outer peripheral edge of the flange portion 50 is crimped.

At this time, the elastic member c is provided on the outer peripheral side of the holder 5.
Are formed in the body portion 51 holding the main body 51, and when the pressure of the tap water flowing through the lumen of the body portion 51 of the holder 5 as the secondary flow path u increases, Hole 52
Are transmitted to the elastic body c, and the elastic body c is compressed and deformed so that the pressure is absorbed.

The elastic member c provided in the secondary flow path u is
As shown in FIG. 10, there is a case where the enlarged diameter portion k is formed in a part of the inner wall surface of the secondary channel u as a fitting concave portion, and the elastic body c is fitted so as to be fitted therein. Is formed separately from the elastic body c, and after the cylindrical or pipe-shaped pressing member 6 fitted to the secondary flow path u is formed and the elastic body c is loaded,
In some cases, the pressing member 6 is inserted into the secondary-side channel u so that the elastic body c fitted to the enlarged-diameter portion k is pressed down to the state.

As described above, the elastic body c loaded in the enlarged diameter portion k
Is held by the holding member 6 inserted into the outer surface of the elastic member c, the pressure of the impact wave generated on the secondary side Y is absorbed by the compressive deformation of the elastic body c. In the same manner as in the above case, the elastic body c is compressed and deformed by the pressure acting on the elastic body c from the holes 61 formed in the body 60 of the pipe-shaped or cylindrical holding member 6. Alternatively, by forming the pressing member 6 with a net or a perforated plate, the elastic body c to be pressed is entirely compressed and deformed.

The pressure adjusting function of the pressure adjusting mechanism W, which is incorporated in the body 1 of the single-shaft pressure reducing valve A and includes a cylindrical valve portion 20, an annular valve seat 3, a pressure sensing plate 21, a spring 4, and the like, is affected. In order to absorb the impact wave generated on the secondary side Y by the elastic body c provided in the body 1 without giving the elastic body c, the elastic body c is connected between the pressure sensitive plate z and the connection port 11 on the secondary side. However, the present invention is not limited to the case where the large diameter portion k is formed on the inner wall surface of the secondary flow path u.

It is sufficient that the pressure adjusting mechanism W is located on the secondary side of the valve mechanism section composed of the cylindrical valve section 20 and the annular valve seat 3. And a cylindrical body 2 having a cylindrical valve-shaped valve portion 20 at the end on the primary side.
The elastic body c may be directly mounted on the inner wall surface of the above, or an enlarged diameter portion may be formed on the inner wall surface and the elastic body c may be provided so as to be lined there.

The secondary side Y of the pressure adjusting mechanism W
On the inner peripheral side of the cylindrical valve portion 20 provided at the end of the primary side X of the cylindrical member 2 which moves in the axial direction of the body 1 in accordance with the pressure change, the cylindrical valve portion 20 is provided. Annular valve seat 3 facing
The elastic member c such as foamed rubber is provided at the center of the cylindrical member 2 inside the cylindrical valve portion 20 as shown in FIG.
A body 7 is formed in such a shape as to protrude so as to protrude toward the inner cavity of the body, and is mounted so as to fix and mount the annular valve seat 3 on the body 1. It may be provided by assembling it at the central part of the valve seat fitting 30 assembled in one lumen.

At this time, the elastic body c made of foam rubber or the like
May be formed in a block shape of an appropriate shape so that the whole is compressed and deformed by pressure, but may be formed in a hollow body having an empty space therein, or may be formed of an elastic body c of the mounting bracket 7.
The elastic body c is attached to the mounting bracket 7 so as to form an empty space 70 surrounded by the elastic body c at the center of the mounting surface where the elastic body c is mounted. It is effective to keep crushed.

As described above, in the means of the present invention, the movable tubular body 2 having the pressure-sensitive plate 21 at the secondary end and the cylindrical valve portion 20 at the primary end, A pressure adjusting mechanism W composed of a spring 4 for pushing it out to the secondary side and an annular valve seat 3 and the like, which is supported on a valve seat 30 and fixedly mounted on the primary side of a cylindrical valve portion 20, is provided. In the single-shaft pressure reducing valve A incorporated in the body 1, a cylindrical valve portion 20 and an annular valve seat in a flow path in which fluid such as hot water or water flows from the primary side X to the secondary side Y in the body 1. An elastic body c such as foamed rubber whose volume shrinks in response to a pressure change is provided at an appropriate portion between the valve mechanism section 3 and the secondary side connection port 11, and this uniaxial pressure reducing valve A is connected. When an impulse wave is generated on the secondary side by suddenly closing the terminal device on the secondary side of the water supply device, this is the body of the single-shaft pressure reducing valve A. Before coming propagated to the valve mechanism portion of a cylindrical valve-shaped valve portion 20 and the annular valve seat 3 of the pressure regulating mechanism W of the inner,
Since the elastic body c absorbs the pressure by being compressed and deformed by receiving the pressure of the impulse wave, it does not interfere with the pressure adjusting function of the pressure adjusting mechanism W and has a cylindrical valve shape. Can be prevented from suddenly closing the annular valve seat 3 to generate a secondary water hammer. An elastic body c for absorbing the pressure of the shock wave generated on the secondary side is incorporated into the body 1 of the single-shaft pressure reducing valve A, so that a downstream device such as a shower is provided downstream of the single-shaft pressure reducing valve A. Can be connected without any trouble.

[0030]

As described above, according to the present invention, the sensitivity of the single-shaft pressure reducing valve is affected while the single-shaft pressure reducing valve can be incorporated without restricting the connection of the terminal equipment such as the shower. The shock wave generated by the sudden closing of the terminal equipment can be absorbed downstream of the uniaxial pressure reducing valve without

[Brief description of the drawings]

FIG. 1 is a partially broken explanatory view of a conventional water hammer prevention device.

FIG. 2 is a longitudinal sectional side view of a single-shaft pressure reducing valve in which a conventional water hammer prevention device is incorporated in a body.

FIG. 3 is an explanatory diagram of an operation of the single-shaft pressure reducing valve according to the first embodiment.

FIG. 4 is an explanatory diagram of a water supply device to which a uniaxial pressure reducing valve having no water hammer prevention device is connected.

FIG. 5 is a longitudinal sectional side view of a conventional single-shaft pressure reducing valve having no water hammer prevention device according to the first embodiment.

FIG. 6 is a vertical sectional side view of a single-shaft pressure reducing valve embodying the present invention.

FIG. 7 is a vertical sectional side view of another embodiment of the single-shaft pressure reducing valve according to the embodiment.

FIG. 8 is a longitudinal sectional side view of still another embodiment of the uniaxial pressure reducing valve of the above.

FIG. 9 is a longitudinal sectional side view of still another embodiment of the uniaxial pressure reducing valve of the above.

FIG. 10 is a longitudinal sectional side view of still another embodiment of the single-shaft pressure reducing valve of the above.

FIG. 11 is a longitudinal sectional side view of an embodiment in which the elastic body of the uniaxial pressure reducing valve is disposed at a central portion of an annular valve seat.

[Explanation of symbols]

A: uniaxial pressure reducing valve, X: primary side, Y: secondary side, W: pressure adjusting mechanism, MV: mixing faucet, a: terminal equipment, b: piping, c
... elastic body (or cushioning material), d ... operating section, e ... shower, f ... flange section, k ... diameter enlarged section, u ... secondary side flow path, v ... gap, z ... pressure sensitive chamber, 1 ... body … 10 ・ 11 ... Connection port, 1
0a: primary side flow path, 12: valve chamber, 14: throttle flange, 2: cylindrical body, 2a: water flow path, 20: valve portion, 21: pressure sensitive plate, 2
2 ... cylindrical part, 3 ... valve seat, 30 ... valve seat fitting, 31 ... water passage hole, 4 ... spring, 5 ... holder, 50 ... flange part, 51 ... trunk part,
52: hole, 6: holding member, 60: trunk, 61: mesh or hole, 7: mounting bracket, 70: empty room.

Claims (7)

[Claims] In a single-shaft pressure reducing valve (A) having a pressure adjusting mechanism (W) housed in a cylindrical body (1), a pressure in a flow passage through which a fluid flows from a primary side (X) to a secondary side (Y) in the body (1). Cylindrical valve portion 20 of adjusting mechanism W and annular valve seat 3 opposed thereto
An elastic body c such as foam rubber whose volume is contracted by pressure is attached to an appropriate portion between the pressure regulating valve portion and the connection port 11 on the secondary side Y to reduce the impact wave generated on the secondary side Y. A device for preventing water hammer in a single-shaft pressure reducing valve, wherein pressure is absorbed by contraction of an elastic body c provided in a flow path in a body 1 to prevent generation of a secondary water hammer. 2. In a uniaxial pressure reducing valve A having a pressure adjusting mechanism W housed in a cylindrical body 1, a pressure sensitive chamber z in the body 1 and an outer end face of a connection port 11 of a secondary side Y are connected. An elastic body c such as foamed rubber whose volume is reduced by pressure is attached to all or a part of the inner wall surface of the secondary side flow path u between the secondary side Y and the secondary side Y.
The pressure of the impulse wave generated in the step (b) is absorbed by the contraction of the elastic body c provided on the inner wall surface of the secondary side channel u, thereby preventing the occurrence of a secondary water hammer. Water hammer prevention device for uniaxial pressure reducing valve. 3. In a uniaxial pressure reducing valve A having a pressure adjusting mechanism W housed in a cylindrical body 1, a pressure sensitive chamber z in the body 1 and an outer end face of a connection port 11 of a secondary side Y are connected. All or part of the inner wall surface of the secondary flow path u between the secondary flow paths u
Forming an enlarged diameter portion k for increasing the inner diameter of the
And an elastic body c such as foamed rubber whose volume is contracted by pressure is mounted and mounted, and an impact wave generated on the secondary side Y is caused by the contraction of the elastic body c mounted on the secondary side channel u. A device for preventing water hammer in a single-shaft pressure reducing valve, wherein the device is absorbed to prevent generation of secondary water hammer. 4. In a uniaxial pressure reducing valve A having a pressure adjusting mechanism W housed in a cylindrical body 1, a pressure sensitive chamber z in the body 1 and an outer end face of a connection port 11 of a secondary side Y are connected. On the inner wall surface of the secondary-side flow path u, an enlarged-diameter portion k for increasing the inner diameter of the secondary-side flow path u is formed while leaving the throttle flange 14 on the pressure-sensitive chamber z side. An elastic body c such as foamed rubber is formed in the portion k to form a flanged cylindrical shape having a flange portion f joined to the outer end surface of the connection port 11 on the secondary side Y on the outer end side, and fitted. Attached, the impact wave generated on the secondary side Y is absorbed by the contraction of the elastic body c mounted on the secondary side channel u to prevent the occurrence of a secondary water hammer. Water hammer prevention device in a uniaxial pressure reducing valve. 5. In a uniaxial pressure reducing valve A having a pressure adjusting mechanism W housed in a cylindrical body 1, a pressure sensitive chamber z in the body 1 and an outer end face of a connection port 11 of a secondary side Y are connected. On the inner wall surface of the secondary-side flow path u, an enlarged-diameter portion k for increasing the inner diameter of the secondary-side flow path u is formed while leaving the throttle flange 14 on the pressure-sensitive chamber z side. An elastic body c such as foamed rubber is formed on the outer periphery of the body portion 51 of the holder 5 formed of a metal material or a resin material into a cylindrical or pipe shape forming a secondary flow path u on the inner circumference side. The holder 51 is fitted and fitted together with the holder 5, and the body 51 is inserted through a mesh or a hole 52 formed in the body 51 of the holder 5.
The elastic body c attached to the secondary flow path u is exposed to the secondary flow path u on the inner peripheral side of the
A water hammer prevention device for a single-shaft pressure reducing valve, wherein the water hammer is prevented from being generated by absorbing the water hammer by contraction of the water. 6. In a single-shaft pressure reducing valve A having a pressure adjusting mechanism W housed in a cylindrical body 1, a pressure-sensitive chamber z in the body 1 and an outer end face of a connection port 11 on a secondary side Y are connected. A part of the inner wall surface of the secondary flow path u is formed with an enlarged diameter part k for increasing the inner diameter of the secondary flow path u. The body c is loaded, and a cylindrical or pipe-shaped holding member 6 formed of a metal material, a resin material or the like and fitted to the secondary flow path u is fitted and held on the outer surface side of the body c. The elastic body c is exposed to the secondary flow path u through meshes or holes 61 formed in the body portion 60 of FIG. The water in a single-shaft pressure reducing valve, wherein the water is absorbed by contraction of an elastic body c attached to a path u to prevent the occurrence of a secondary water hammer. -Hammer prevention device. 7. An annular valve seat (3) opposed to a cylindrical valve portion (20) provided at an end of a primary side (X) of a movable cylindrical body (2) of a pressure adjusting mechanism (W). At the center portion of the cylindrical valve portion, the inner peripheral side of the cylindrical valve portion 20 is formed so as to bulge toward the inner cavity of the cylindrical body 2, is arranged, and is attached to and supported by the valve seat fitting 30. The device for preventing water hammer in a single-shaft pressure reducing valve according to claim 1, wherein: