JP2002089775A - Liquid hammer preventing tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid hammer preventing tool capable of maintaining a liquid hammer preventing function for a long period, providing high sealability, stabilizing quality, and reducing manufacturing cost with a simple holding structure. SOLUTION: This liquid preventing tool comprises a casing 20 passed through a liquid flow path and a through hole 1, elastic damping body 50 stored in the casing 20, and a protective film 60 dividing the inside of the casing 20 into an area communicating with the flow path and an area storing the elastic damping body 50. The elastic damping body 50 is a foam body having an initial hardness of C30 to 85 in Asker C and an apparent gravity of 0.30 to 0.70.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to water pipes and water appliances,
The present invention relates to a liquid hammer preventing device that suppresses a liquid hammer phenomenon that occurs in a liquid flow path of a hydraulic device or the like.

[0002]

2. Description of the Related Art Conventionally, a liquid hammer preventing device that effectively reduces a liquid hammer phenomenon occurring in a liquid flow path in a water supply pipe or the like has been widely used. The liquid hammer prevention device includes an externally mounted type that is connected in the middle of a liquid flow path, and an internally mounted type that is built in an operation handle for opening and closing the liquid flow path.

[0003] Further, as one type of the liquid hammer preventive device, an outer flange type in which the outer peripheral edge of the protective film is held by an outer flange, and an inner flange type in which the outer peripheral edge of the protective film is held by an inner flange. There is. The outer flange type liquid hammer preventing device is basically configured as shown in FIG. 25 in order to effectively absorb and reduce the liquid hammer phenomenon.
That is, the elastic buffer K accommodated in the casing K0 of the liquid hammer preventing device 700 has a cylindrical shape having a height H substantially equal to the outer diameter D thereof. The elastic buffer K has a hat-shaped protective film C disposed on the surface side thereof,
In a state where the outer peripheral edge C2 is joined to the upper surface of the flange C3, the casing K0 is hermetically sealed by caulking means 725 around the opening. And it is attached to the pipe P1 by the attachment screw portion C4 of the flange C3. FIG.
As shown in FIG. 6, the protective film C of the elastic buffer K
1 so that the elastic buffer K that has received the liquid hammering force P can follow the movement of large displacement L in this height direction.
And a hat-shaped diaphragm.

The reason why the liquid hammer preventing device 700 has a cylindrical shape is that a certain amount or more of the volume of the elastic buffer K is required to exhibit the liquid hammer absorbing effect. This is because the elastic buffer K needs to have a predetermined hardness and a height capable of compressing and displacing by a predetermined amount. The protective film C of the elastic buffer is durable to prevent the surface of the elastic buffer from being perforated by the liquid hammering force, and has elasticity capable of following the elastic displacement of the elastic buffer K. That's why.

[0005] The elastic buffer K is composed of a silicone gel buffer K1 as a base material of the elastic buffer, and an elastic hollow sphere K2 interposed in the silicone gel buffer K1. A hollow sphere-added silicone gel is used.

However, when the elastic hollow sphere-added silicone gel is repeatedly subjected to the liquid hammer absorbing action for a long period of time, the joint surface between the elastic hollow sphere K2 and the silicone gel buffer K1 becomes loose or peels off. It has been found that long-term liquid hammer absorption is not guaranteed. This is referred to as a softening phenomenon of the above-mentioned elastic hollow sphere-added silicone gel, and when a constant or more external force is continuously applied to the above-mentioned elastic hollow sphere-added silicone gel, a decrease in hardness occurs. Let it.

This decrease in hardness induces a so-called "bottoming phenomenon" in which the deformation of the elastic hollow sphere-added silicone gel due to the liquid hammer reaches the portion in contact with the casing and the liquid hammer absorbing action is no longer guaranteed. In addition, the pressure energy conversion efficiency is greatly reduced due to the reduction in the resilience characteristics.

[0008] This is because the continuous compression displacement of the elastic hollow sphere K2 causes separation at the joint portion with the silicone resin, which causes a reduction in the external force propagation function to the elastic hollow sphere. This is considered to cause a decrease in hardness of the entire buffer. Therefore, when the silicone gel buffer K1 is used, a volume that is equal to or more than a certain value and a height that can be compressed and displaced by a predetermined amount are required.

A typical embodiment of the inner flange type liquid hammer will be described with reference to FIGS. 27 and 28. FIG.
The liquid hammer prevention device 800 shown in FIG. 27 is of a type that is branched and connected in the middle of a pipeline. The liquid hammer prevention device 800
Is a main body 8 that communicates with the flow path through the through hole 801.
03 is screwed with the screw portion 805B of the mounting ring 805 to the screw portion 803A of the connection portion, and is connected by the screw portion 805A at the lower end. The casing KO is put on the outer periphery of the mounting ring 805 and is fastened with the two screw portions 805C and 807. A fitting groove 803E is formed between the head 803D of the main body inserted and arranged in the casing KO and the mounting ring 805, and the fitting groove 803E is formed so as to protrude radially inward from the opening of the protective film C. The fitted protrusion C1 is fitted. Thus, the protective film C is divided into a region S1 communicating with the flow path through the through hole 801 and a region S2 of the elastic buffer 809 housed in the casing KO. The liquid tightness between the region S1 and the region S2 is determined by the screw portion 80 between the head 803D of the main body composed of two members and the mounting ring 805.
3A and 805B are secured by clamping the fitting projection C1 in the axial direction X.

[0010] The liquid hammer 900 shown in FIG.
It is a water stopcock type with a built-in liquid hammer and is installed in a handle 919 for opening and closing the spindle 911. The spindle 911 includes a screw portion 911A screwed into a female screw portion of a valve body (not shown) and a valve body 913 at the lower end thereof. The spindle 911 is provided with a through hole 901 at the axis thereof, and a main body 903 is screwed to the upper end in a liquid-tight manner. Then, similarly to the configuration of the liquid hammer preventing device 800, a mounting ring 905 is screwed to a screw portion 903N screwed to an outer periphery 903B of the main body 903, and a casing KO serving as a handle 919 is put on the mounting ring 905, and both screws are screwed. The parts 905C and 907 are tightened.

A fitting groove 9 is provided between a head 903D of the main body inserted and arranged in the casing KO and a mounting ring 905.
03E is formed, and a fitting convex portion C1 that protrudes radially inward from the opening of the protective film C is fitted into the fitting groove portion 903E. Thus, the protective film C is divided into a region S1 that communicates with the flow path through the through hole 901 and a region S2 of the elastic buffer 909 housed in the casing KO.
The liquid tightness between the region S1 and the region S2 is determined by the screw portion 903 between the head 903D of the main body composed of two members and the mounting ring 905.
N, 905B is secured by clamping the fitting protrusion C1 from the axial direction X by tightening.

In the inner flange type liquid hammer preventive device, as a structure required to effectively absorb and reduce the liquid hammer phenomenon, the elastic buffer can maintain the liquid hammer preventive function for a long period of time. Another object of the present invention is to increase the liquid tightness of the protective film and prevent the liquid from leaking through the connection between the protective film and the casing in the casing space containing the elastic buffer. If the liquid leaks into the casing and the elastic buffer is placed in the liquid and becomes so-called floating, liquid hammer acts from all directions of the elastic buffer, and effective energy conversion is not performed. If liquid invades between the elastic buffer and the protective film and a liquid layer is formed, the pressure energy of the liquid hammer is not effectively transmitted to the elastic buffer, so that effective energy conversion is not performed and the liquid hammer is not performed. This is because the phenomenon cannot be effectively absorbed or reduced.
Another object of the present invention is to prevent leakage of liquid to the outside of the casing and not to reduce the soundness of the device.

In the above-mentioned liquid hammer preventer, tightening for ensuring the liquid tightness of the protective film is performed by screwing between two members of the main body head and the mounting ring. For this reason, the number of parts increases, the number of processing steps and the number of steps of assembly also increase, and the economical problem of increasing the manufacturing cost of the liquid hammer prevention device,
There is a technical problem that it is difficult to maintain a constant product quality due to variations in screwing torque during assembly.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems of the conventional liquid hammer, and a first object of the present invention is to provide a liquid hammer capable of maintaining the liquid hammer preventing function for a long period of time. An object of the present invention is to provide an anti-strike device. A second object of the present invention is to provide a liquid hammer preventing device capable of maintaining a liquid hammer preventing function for a long period of time, having a high liquid tightness, and having a simple holding structure to achieve stable quality and reduced manufacturing cost. Is to provide.

[0015]

According to a first aspect of the present invention, there is provided a liquid hammer preventing device, comprising: a casing that communicates with a liquid flow path through a through-hole; and an elastic buffer housed in the casing. A protective film for partitioning the casing into a region communicating with the flow path and a region in which the elastic buffer is accommodated. The elastic buffer has an initial hardness of Asker C30 to 85 and an apparent specific gravity of 0.30. It is characterized by being a foam of about 0.70.

According to a second aspect of the present invention, there is provided a liquid hammer preventing device, wherein a casing communicated with a liquid flow path through a through-hole, an elastic buffer housed in the casing, The elastic buffer has an initial hardness of Asker C50-85 and an apparent specific gravity of 0.1.
It is characterized by being a foam of 30 to 0.40.

According to a third aspect of the present invention, there is provided a liquid hammer preventing device, wherein a casing communicated with a liquid flow path through a through hole, an elastic buffer housed in the casing, The elastic buffer has an initial hardness of ASKER C55-70 and an apparent specific gravity of 0.1.
It is characterized by being a foam of 30 to 0.40.

According to a fourth aspect of the present invention, there is provided a liquid hammer preventing apparatus according to any one of the first to third aspects.
The elastic buffer has a flat shape that is thinner in a thickness direction and is larger in an outer diameter direction, and the protective film is a flat plate having a larger outer diameter than the elastic buffer, and an outer peripheral edge of the protective film is formed on an inner peripheral wall of a casing. It is characterized by being held.

According to a fifth aspect of the present invention, there is provided a liquid hammer preventing apparatus according to any one of the first to third aspects.
A casing, an elastic buffer disposed in the casing, a main body having a through-hole disposed in the casing and communicating with the flow path, and a fitting protrusion formed to protrude radially inward at an opening edge. The fitting protrusion is fitted into the fitting groove formed in the head of the main body, and is formed of a protective film held and fixed by the inner wall surface of the casing and the protective film. Radially outward on the outer peripheral surface such that the length dimension between the radially inner peripheral surface and the outer peripheral surface of the fitting protrusion is equal to or greater than the depth dimension between the side outer peripheral surface of the fitting groove portion and the inner wall surface of the casing. It is characterized by forming a protruding part that protrudes

The liquid hammer according to claim 6 of the present invention is the liquid hammer according to any one of claims 1 to 3,
A casing, an elastic buffer disposed in the casing, a main body having a through-hole disposed in the casing and communicating with the flow path, and a fitting protrusion formed to protrude radially inward at an opening edge. The fitting projection is fitted into a fitting groove formed in the head of the main body, and is formed of a protective film held and fixed by the inner wall surface of the casing. A projection is formed on the outer peripheral surface so as to project radially outward.

According to a seventh aspect of the present invention, there is provided a liquid hammer preventing apparatus according to any one of the first to third aspects.
A casing, an elastic buffer disposed in the casing, a main body having a through-hole disposed in the casing and communicating with the flow path, and a fitting protrusion formed to protrude radially inward at an opening edge. The fitting protrusion is fitted into the fitting groove formed in the head of the main body, and is formed of a protective film held and fixed by the inner wall surface of the casing and the protective film. Radially outward on the outer peripheral surface such that the length dimension between the radially inner peripheral surface and the outer peripheral surface of the fitting protrusion is equal to or greater than the depth dimension between the side outer peripheral surface of the fitting groove portion and the inner wall surface of the casing. And a protrusion protruding outward in the radial direction on the side outer peripheral surface of the fitting groove.

The liquid hammer according to claim 8 of the present invention is the liquid hammer according to any one of claims 5 to 7,
The protective film is characterized in that a thin lip portion is formed on the lower surface on the radially inner side of the fitting protrusion so as to be in close contact with the lower surface of the fitting groove by hydraulic action.

[0023]

In the liquid hammer according to the first aspect of the present invention, the elastic buffer is formed of a foam having an initial hardness of Asker C30 to 85 and an apparent specific gravity of 0.30 to 0.70. . This is an elastic buffer with countless minute independent foams. It can function as a pressure energy conversion medium by securing the amount of displacement by elasticity and energy loss by internal friction (viscoelasticity). Since it is not a composite of the above, there is no bonding interface, it can be set to an arbitrary high hardness, it has high mechanical strength, and it has excellent durability such as low compression set and little set due to repeated compression. Therefore, the function of absorbing and attenuating the liquid hammer can be maintained for a long period of time, and the degree of freedom of shape change is increased, so that space can be saved.

According to a second aspect of the present invention, the elastic shock absorber is formed of a foam having an initial hardness of Asker C50 to 85 and an apparent specific gravity of 0.30 to 0.40. This material can exert an excellent function as a pressure energy conversion medium by securing the amount of displacement by elastic characteristics and energy loss by internal friction (viscoelastic characteristics), can be set to high hardness, has large mechanical strength, Excellent durability such as permanent set and little set due to repeated compression.In addition, it can maintain excellent energy absorption and damping function against liquid hammer for a long time even under severe conditions of high temperature and high pressure. Also, the degree of freedom of shape change is increased, and it is possible to cope with space saving.

According to a third aspect of the present invention, the elastic shock absorber is formed of a foam having an initial hardness of Asker C55 to 70 and an apparent specific gravity of 0.30 to 0.40. This material can exert a particularly excellent function as a pressure energy conversion medium by securing the amount of displacement by elastic characteristics and energy loss by internal friction (viscoelastic characteristics), can be set to high hardness, and has large mechanical strength. It has excellent durability, such as low compression set and little set due to repeated compression, and can maintain excellent energy absorption / damping function against liquid hammer for a long time even under severe conditions of high temperature and high pressure. Also, the degree of freedom in shape change is increased, and it is possible to cope with space saving.

According to a fourth aspect of the present invention, in the liquid hammer preventive device, the elastic shock absorbing member made of the above foam is employed, so that the liquid shock preventing device has a flat shape which is thin in a height direction and large in an outer diameter direction.
The protective film is a thin plate having a larger outer diameter than the elastic buffer. In other words, the height of the elastic buffer and the protective film can be reduced, and thus, the liquid hammer can be manufactured in a flat structure capable of saving space in the height direction, and a liquid is used. It can be easily stored in narrow spaces such as various devices.

According to a fifth aspect of the present invention, there is provided a liquid hammer preventing device in which a fitting groove formed in a head of a main body disposed in the casing is formed so as to protrude radially inward from an opening edge of the protective film. By fitting the convex portion and holding and fixing the convex portion with the inner wall surface of the casing, the convex portion is divided into a region communicating with the flow path through the through hole and a region of the elastic buffer housed in the casing. ing. The fitting convex portion of the protective film has a projection formed on the outer peripheral surface so as to protrude outward in the radial direction, and the length dimension between the inner peripheral surface and the outer peripheral surface in the radial direction of the fitting convex portion is set in the fitting groove portion. The outer peripheral surface is pressed against the inner wall surface of the casing and swells and deforms radially inward and outward, and the inner peripheral surface is fitted. It is pressed against the outer peripheral surface of the side of the mating groove to exert a liquid-tight action.
Further, the lower surface of the upper surface of the fitting protrusion in the axial direction is pressed against the lower surface of the upper surface of the fitting groove, and a liquid-tight action is exhibited.

Thus, there is no danger of liquid infiltrating into the elastic buffer housed in another area in the casing from the area that communicates with the flow path through the through hole, whereby the elastic buffer is arranged in the liquid. It is in a so-called floating state, or in a state where a liquid layer is formed between the elastic buffer and the protective film,
The problem that effective energy conversion cannot be performed is eliminated, and the function as a liquid hammer preventing device can be exhibited for a long time. In addition, there is no possibility of liquid leakage from the casing to the outside, and the soundness of the device is maintained.
In addition, a fitting convex portion formed so as to protrude inward in the radial direction into an opening of the protective film is fitted into a fitting groove portion provided on the head of the main body disposed in the casing, and this is fitted to the inner wall surface of the casing. Since the structure of holding and fixing is achieved, the number of parts can be reduced, the number of assembling steps can be reduced, the manufacturing cost of the liquid hammer preventing device can be reduced, and the product quality can be kept constant.

In the liquid hammer preventer according to the sixth aspect, first, the fitting groove formed in the head of the main body inserted and arranged in the casing is formed so as to protrude radially inward at the opening edge of the protective film. By fitting the fitting protrusions, a region communicating with the flow path via the through hole and a region of the elastic buffer housed in the casing are defined. The fitting protrusion of the protective film is formed such that a protrusion formed radially outward on the outer peripheral surface of the side of the fitting groove is pushed into the inner peripheral surface of the fitting protrusion. The fitting projection is pushed by the projection and swells and deforms in the radial direction and the axial direction. As a result, the outer peripheral surface of the fitting convex portion is pressed against the inner wall surface of the casing, and the inner peripheral surface of the fitting convex portion is strongly pressed by the projecting portion due to the reaction force, so that a liquid-tight action is exhibited. Further, the lower surface of the upper surface of the fitting protrusion in the axial direction is pressed against the lower surface of the upper surface of the fitting groove, and a liquid-tight action is exhibited.

Thus, there is no danger that the liquid will penetrate from the region communicating with the flow path through the through hole into the elastic buffer housed in another region in the casing, whereby the elastic buffer is arranged in the liquid. It is in a so-called floating state, or in a state where a liquid layer is formed between the elastic buffer and the protective film,
The problem that effective energy conversion cannot be performed is eliminated, and the function as a liquid hammer preventing device can be exhibited for a long time. In addition, there is no possibility of liquid leakage from the casing to the outside, and the soundness of the device is maintained.
In addition, a fitting convex portion formed so as to protrude inward in the radial direction into an opening of the protective film is fitted into a fitting groove portion provided on the head of the main body disposed in the casing, and this is fitted to the inner wall surface of the casing. Since the structure of holding and fixing is achieved, the number of parts can be reduced, the number of assembling steps can be reduced, the manufacturing cost of the liquid hammer preventing device can be reduced, and the product quality can be kept constant.

According to a seventh aspect of the present invention, there is provided a liquid hammer preventive device which is formed so as to protrude radially inward from an opening edge of a protective film in a fitting groove provided in a head of a main body disposed in the casing. By fitting the convex portion and holding and fixing the convex portion with the inner wall surface of the casing, the convex portion is divided into a region communicating with the flow path through the through hole and a region of the elastic buffer housed in the casing. ing. The fitting convex portion of the protective film has a projection formed on the outer peripheral surface so as to protrude outward in the radial direction, and the length dimension between the inner peripheral surface and the outer peripheral surface in the radial direction of the fitting convex portion is set in the fitting groove portion. The outer peripheral surface is pressed against the inner wall surface of the casing and swells and deforms radially inward and outward, and the inner peripheral surface is fitted. It is pressed against the side outer peripheral surface of the mating groove. Further, in the fitting protrusion of the protective film, a protrusion formed so as to protrude radially outward on a side outer circumferential surface of the fitting groove is pushed into the inner circumferential surface of the fitting protrusion, and is pushed into the protrusion. As a result, it further swells and deforms in the radial and axial directions. As a result, the outer peripheral surface of the fitting projection is strongly pressed against the inner wall surface of the casing, and the inner peripheral surface of the fitting projection is strongly pressed by the projection due to the reaction force, so that a liquid-tight action is exhibited. Further, the lower surface of the upper surface of the fitting protrusion in the axial direction is pressed against the lower surface of the upper surface of the fitting groove, and a liquid-tight action is exhibited.

Thus, there is no danger of liquid infiltrating into the elastic buffer housed in another area in the casing from the area that communicates with the flow path through the through hole, whereby the elastic buffer is arranged in the liquid. It is in a so-called floating state, or in a state where a liquid layer is formed between the elastic buffer and the protective film,
The problem that effective energy conversion cannot be performed is eliminated, and the function as a liquid hammer preventing device can be exhibited for a long time. In addition, there is no possibility of liquid leakage from the casing to the outside, and the soundness of the device is maintained. In addition, a fitting convex portion formed so as to protrude inward in the radial direction into an opening of the protective film is fitted into a fitting groove portion provided on the head of the main body disposed in the casing, and this is fitted to the inner wall surface of the casing. Since the structure of holding and fixing is achieved, the number of parts can be reduced, the number of assembling steps can be reduced, the manufacturing cost of the liquid hammer preventing device can be reduced, and the product quality can be kept constant.

In the liquid hammer preventer according to the present invention, a thin lip portion is formed on the lower surface of the protective film on the radially inner side of the fitting convex portion so as to be in close contact with the lower surface of the fitting groove portion by hydraulic action. Even if a liquid enters the fitting groove, the lip is strongly adhered to the lower surface of the fitting groove by receiving the force in the direction of the hydraulic pressure, and a high liquid-tight action is exhibited.

Thus, there is no danger of liquid infiltrating from the region communicating with the flow path through the through hole to the elastic buffer housed in another region in the casing, whereby the elastic buffer is arranged in the liquid. It is in a so-called floating state, or in a state where a liquid layer is formed between the elastic buffer and the protective film,
The problem that effective energy conversion cannot be performed is eliminated, and the function as a liquid hammer preventing device can be exhibited for a long time. In addition, there is no possibility of liquid leakage from the casing to the outside, and the soundness of the device is maintained.
In addition, a fitting convex portion formed so as to protrude inward in the radial direction into an opening of the protective film is fitted into a fitting groove portion provided on the head of the main body disposed in the casing, and this is fitted to the inner wall surface of the casing. Since the structure of holding and fixing is achieved, the number of parts can be reduced, the number of assembling steps can be reduced, the manufacturing cost of the liquid hammer preventing device can be reduced, and the product quality can be kept constant.

[0035]

Embodiments of the present invention will be described below with reference to the drawings. FIGS. 1 to 6 show various types of liquid hammer mitigation devices in which the present invention is applied to a vertically elongated type of the MW2 liquid hamper developed by the applicant. FIG.
11 to 11 show test results of the liquid hammer preventive device of each of the above embodiments. FIGS. 12 to 17 show various embodiments of the liquid hammer preventive device in which the present invention is applied to a flat type.

First, an embodiment in which the liquid hammer preventing device of the present invention has the same vertical shape as the MW2 liquid hammer preventing device will be described with reference to FIG. In the liquid hammer prevention device 100 of the first embodiment shown in FIG. 1, the elastic buffer 50 housed in the casing K0 is
The cylindrical shape has a height dimension substantially equal to the outer diameter dimension. The elastic buffer 50 is provided with a hat-shaped protective film F on the surface side, and is hermetically sealed by the caulking means 25 on the peripheral edge of the opening of the casing K0 in a state where the outer peripheral edge F2 is joined to the upper surface of the outer flange F3. I have.

The protective film F is formed as a hat-shaped diaphragm provided with a telescopic portion F1 so as to be able to follow the movement of the elastic buffer 50 which receives the liquid hammering force P from the through hole 1 and largely displaces in the height direction. I have. And it is attached to the pipe P1 by the attachment screw portion F4 of the outer flange F3. Thereby, the liquid hammer prevention device 100 is provided with a casing KO which is communicated with the liquid flow path through the through hole 1, and the casing has an area E 1 in which the inside communicates with the liquid flow path by the protective film F, It is divided into a region E2 where the elastic buffer 50 is stored.

The elastic buffer 50 and the protective film F communicate with the liquid flow path through the through hole 1. The through hole 1 is
It functions as a so-called orifice, and has a pressure reduction effect and a frequency (phase) conversion function as complementary functions of the pressure energy conversion efficiency by suppressing the volume of the elastic buffer 50. In this case, the elastic buffer 50 and the protective film F are disposed relatively close to each other, and the diameter thereof is appropriately set according to the specifications of the elastic buffer 50 and the like, but is preferably about 3 mm.

The elastic buffer 50 incorporated in the liquid hammer protector 100 has an initial hardness of Asker C30 to 85.
Foam 51 having an apparent specific gravity of 0.30 to 0.70
Is used. Further, as the elastic buffer 50, a foam having an initial hardness of Asker C55 to 70 and an apparent specific gravity of 0.30 to 0.40 can obtain the best result. The same good results are obtained with foams having an initial hardness of Asker C50-85 and an apparent specific gravity of 0.30-0.40, which are provided as intended mass-produced products. As the foam 51,
Foams formed of various polymers can be used, and a polyurethane fine foam 51 is used as a specific example. As the polyurethane fine foam 51, those having an initial hardness and apparent specific gravity within the above ranges of "Damptron ES202" and "Damptron ES206" manufactured by Nisshinbo Industries, Inc. can be suitably used. Incidentally, the polyurethane fine foam 51 in this range is obtained by pouring a resin into a mold and foaming it into a sheet shape. At this time, since the outside gas escapes, the foamed particle diameter becomes slightly coarser to 300 to 400 μm. No gas escape inside, foamed particle size 50-100μm
And it is dense. As the protective film F, a high-strength millable silicone rubber is used.

The polyurethane fine foam 51 is a kind of polyurethane foam and is an elastic buffer having an infinite number of minute independent foams, and belongs to a semi-rigid type, and among them, is a high hardness type. . The production method is a method in which a glycol component and a diisocyanate component are produced by foaming using a gas generated when they are reacted with water and crosslinked to form a network. It is directly exposed to the outdoors, is used for a long time under the constraint of high load, and has a proven track record as a railway vibration isolator with excellent vibration absorption and durability.

The specific production method is a low foaming urethane elastomer for elastic sleepers, which is disclosed in JP-B-58-5-5.
No. 0590, Japanese Patent Publication No. Sho 61-60202, Japanese Patent Publication No. Hei 4-22170, Japanese Patent Publication No. Hei 4-58494, Japanese Patent Publication No. Hei 8-18391, Patent No. 252183
No. 7, Japanese Patent No. 2973847, and the like.

In the polyurethane fine foam 51, especially, the initial hardness of "Damplon ES202" is Asker C55-70, and the apparent specific gravity is 0.30-0.30.
0.40 is preferably used. The initial hardness of this product and "Damplon ES206" is Asker C30-70.
Table 1 shows foam specifications and mechanical properties of the foams having an apparent specific gravity of 0.60 to 0.70.

[Table 1]

As shown in Table 1 above, the initial hardness was Asker C
The polyurethane microfoam 51 having an apparent specific gravity of 55 to 70 and an apparent specific gravity of 0.30 to 0.40 functions as a pressure energy conversion medium due to securing of a displacement amount by elastic characteristics and energy loss by internal friction (viscoelastic characteristics). It can be demonstrated and because it is not a composite of different materials, there is no bonding interface,
High hardness, high mechanical strength, compression set,
Excellent durability, such as less set due to repeated compression.
Therefore, the function of absorbing and attenuating the liquid hammer can be maintained for a long period of time, and the degree of freedom of shape change is increased, which can cope with space saving. In addition, the initial hardness, which is a mass-produced product for cost reduction, is Asker C50-85, and the apparent specific gravity is 0.30-0.4.
It has been confirmed that the polyurethane fine foam of No. 0 has the same performance as described above.

Next, the liquid hammer prevention device 110 of the second embodiment shown in FIG. 2 will be described. The liquid hammer prevention device 110 is the same as the liquid hammer prevention device 100 of the first embodiment, except that the initial hardness is Asker C30 to 85 and the apparent specific gravity is 0.30 to 0.30.
A 0.70 polyurethane fine foam 51 is used, and the protective film F has a cross-sectional shape that is locked to the inner flange F5. The other configuration is the same as that of the liquid hammer prevention device 100 of the first embodiment, and the description is omitted.

Next, the liquid hammer prevention device 120 of the third embodiment shown in FIG. 3 will be described. The liquid hammer preventive device 120 is the liquid hammer preventive device 100 of the first embodiment described above, and has an initial hardness of Asker C30 to 85 and an apparent specific gravity of 0.30 to 0.30.
A microfine polyurethane foam 51 of 0.70 is used, and the protective film F has an even higher octopus-shaped cross-sectional shape. The other configuration is the same as that of the liquid hammer prevention device 100 of the first embodiment, and the description is omitted.

Next, the liquid hammer prevention device 130 of the fourth embodiment shown in FIG. 4 will be described. This liquid hammer prevention device 130 has a built-in liquid hammer prevention device 130 compactly housed in a one-touch type faucet 130A. That is, a cavity 133 is provided in the main body 131, and the initial hardness thereof is Asker C30 to 85 and the apparent specific gravity is 0.30 to 0.35.
A 0.70 polyurethane microfoam 51 is incorporated. In the polyurethane fine foam 51, the protective film F is connected to the passage 135 through the through hole 137. The tap water W is discharged from the faucet 130 by operating the lever 139.

Next, a liquid hammer preventing device 140 according to a fifth embodiment shown in FIG. 5 will be described. This is a water stopcock with a liquid hammer 1
The liquid hammer preventing device 140 having the same configuration as the liquid hammer preventing device 100 of the first embodiment is built in the handle 19 of the 40A, and is called a spindle type. Inside the handle 19, the initial hardness is Asker C30-85.
In addition, a polyurethane fine foam 51 having an apparent specific gravity of 0.30 to 0.70 is incorporated. The valve body 2 of the water stopcock 140A with a liquid hammer is provided with a connecting portion 3 connected to a pipeline.
And a valve seat 5 provided therein, and a vertical screw 2 </ b> A of the valve body 2.
And a valve element 7 attached to the lower end of the spindle 9. By operating the handle 19 to open and close, the spindle 9 is moved in the direction in which the pipeline opens and closes, and the valve element 7 opens and closes the valve seat 5. As for the through-hole (orifice), the portion of the hole from the connection portion 3 to the spindle 9 exhibits its function.

Next, a liquid hammer prevention device 150 according to a sixth embodiment shown in FIG. 6 will be described. This is a water stopcock with a liquid hammer 1
This is a modification of the liquid hammer preventing device 140 of the fifth embodiment installed in the handle 19 of the 40A, and is also a spindle type liquid hammer preventing device 150. This also has an initial hardness of Asker C30 to 85 and an apparent specific gravity of 0.30 to 0.7.
Polyurethane fine foam 51 of 0 is used, and the shape of the protective film F is made an octopus-shaped cross-sectional shape with a higher height.
The flange portion holding the protective film F is divided into two pieces to enhance liquid tightness, and the outer shape of the handle 19 is made slimmer. Note that the other configuration is the same as that of the liquid hammer prevention device 140 of the fifth embodiment, and the description is omitted.

The liquid hammer prevention devices 100 to 150 according to the first to sixth embodiments of the present invention are configured as described above.
Various tests were conducted on the water hammer prevention effect by employing a polyurethane microfoam 51 having an initial hardness of Asker C 30 to 85 and an apparent specific gravity of 0.30 to 0.70.

First, FIG. 7 shows an initial performance comparison between an elastic hollow sphere-added silicone gel K in the form of a vertically elongated buffer similar to that of the MW2 liquid hammer and a fine polyurethane foam 51 (maximum water hammer pressure). Suppression rate%, mounting part: spindle type continuous water hammer supply 100 times). According to the above graph, the polyurethane fine foam 51 is “ES206 / specific gravity 0.6”.
-0.7 "" ES206 / specific gravity 0.5-0.6 "" ES
206 / specific gravity 0.4-0.5 "," ES202 / specific gravity 0.
4 to 0.5 "and" ES202 / specific gravity 0.3 to 0.4 "are values approaching 68.5% of the elastic hollow sphere-added silicone gel K, which is a practical range as a liquid hammer preventive device. Can be confirmed.

FIG. 8 shows an endurance test of an elastic hollow sphere-added silicone gel K in the form of an MW2 liquid hammer shock absorber and a polyurethane microfoam 51 (maximum water hammer pressure suppression rate%, mounting portion : 100,000 times of continuous supply of spindle type: Number of times of water hammer supply equivalent to two years of actual use in house equipment). From the above graph, it can be seen that the polyurethane microfoam 51 has the best value of “ES202 / specific gravity 0.3 to 0.4” close to the elastic hollow sphere-added silicone gel K up to 100,000 times of continuous water hammer supply. It can be seen that excellent performance can be maintained up to 100,000 times of continuous water hammer supply. "ES206 / specific gravity 0.6-0.7"
However, although it is lower than the above “ES202 / specific gravity 0.3 to 0.4”, the numerical value exceeding 60% is maintained, and it can be confirmed that the number of continuous water hammer supply can be used up to 100,000 times.

FIGS. 9 to 11 show the above-mentioned elastic hollow sphere-added silicone gel K and polyurethane fine foam 51 "E".
S202 / specific gravity 0.3-0.4 "and" ES206 / specific gravity 0.6-0.7 "of the above-mentioned normal use conditions and heating,
Shows water hammer suppression performance under severe conditions in a pressurized state. still,
In the figure, the normal use condition is shown as “continuous water hammer”, and the severe use condition is shown as “heating + pressurization + continuous water hammer”. The heating condition was 85 ° C., and the pressurizing condition was 0.65 MPa (maximum possible condition of house equipment). FIG. 9 shows the water hammer suppressing performance and the supply conditions of the silicone gel buffer K in the MW2 liquid hammer preventing device shape. Maximum water hammer pressure suppression rate%
The maximum water hammer pressure suppression rate under normal use conditions is stable at “70 to 65%” up to 100,000 times of water hammer supply. Further, the maximum water hammer pressure suppression rate under severe use conditions is reduced to 60%, and this 60% can be said to be the lower limit of the line within the acceptable range of the water hammer suppression performance (water hammer noise suppression degree).

FIG. 10 shows a fine polyurethane foam “ES2”.
02 / specific gravity 0.3 to 0.4 "shows water hammer suppressing performance and supply conditions. The maximum water hammer pressure suppression rate is stable from "70% to 65%" under normal use conditions up to 100,000 times of water hammer supply.
In addition, the maximum water hammer pressure suppression rate under severe use conditions is “67%
To 63% ". From these results, the polyurethane fine foam “ES202 / specific gravity 0.3 to 0.4”
It was confirmed that the maximum water hammer pressure suppression rate% could be maintained at the same or higher value for a long time than the silicone gel buffer K.

FIG. 11 shows a fine polyurethane foam “ES2”.
06 / specific gravity 0.6 to 0.7 "shows the water hammer suppressing performance and supply conditions. The maximum water hammer pressure suppression rate is stable from "70% to 65%" under normal use conditions up to 100,000 times of water hammer supply.
Further, the maximum water hammer pressure suppression rate under severe use conditions is greatly reduced to 50%. From these results, the polyurethane microfoam “ES206 / specific gravity 0.6 to 0.7” has reduced water hammer suppression performance under severe use conditions, but can be used without any problem under normal use conditions. It can be said that it passes if limited.

The polyurethane fine foam 51 "ES20"
2 / specific gravity 0.3-0.4 ”means that the initial hardness is Asker C55.
-70, "ES206 / specific gravity 0.6-0.7", initial hardness of Asker C30-70, and other initial durability of polyurethane fine foam 51 of each product number which is practical level in durability and liquid hammer suppression rate. In terms of hardness, the usable polyurethane fine foam 51 has an initial hardness of Asker C30.
~ 85, and the apparent specific gravity is in the range of 0.30 to 0.70. The above test results are shown as spindle type data. This is because the spindle type has the best workability and is widely used in the market. Of course, any type other than the spindle type shows the same tendency.

According to the liquid hammer prevention devices 100 to 150 of the first to sixth embodiments, the following operations and effects are obtained. First, the elastic buffer 50 has an initial hardness of Asker C30 to 85, and an apparent specific gravity of 0.30 to 0.30.
A polyurethane microfoam 51 of 0.70 is used.
It is a closed cell foam with a high expansion ratio and a small cell diameter, high hardness, low permanent set due to compression set and repeated compression, excellent durability, and temperature dependence. It has been proved from the above-mentioned test results by comparison with the silicone gel buffer K that it has characteristics such as relatively small properties. In particular, "Damptron ES20
In the case where the initial hardness of "2" is Asker C55-70 and the apparent specific gravity is 0.30-0.40, it has stable durability under normal and severe use conditions, and is optimal. It can be said that. In addition, good results can be obtained in the same manner as described above for a polyurethane fine foam having an initial hardness of Asker C50 to 85 and an apparent specific gravity of 0.30 to 0.40, which is a mass-produced product in which the cost is reduced. Was done.

Each of the liquid hammer prevention devices 100 to 150 is provided with a casing which communicates with a fluid flow path through a through hole. , And an area in which the elastic buffer is accommodated, and the elastic buffer has a basic configuration formed of polyurethane fine foam. Thereby, the liquid hammer prevention function excellent in the energy absorption / damping characteristics with respect to the liquid hammer can be maintained for a long time.

Next, a description will be given of flattened liquid hammer prevention devices of various embodiments shown in FIGS. First, in the liquid hammer prevention device 200 of the seventh embodiment shown in FIGS. 12 to 14, the casing 20 includes a container body 30 having a concave cross section and an attachment body 40 screwed thereto.
The container body 30 includes a dish-shaped space S1 having a small depth, a large-diameter peripheral step portion 33 provided on an outer peripheral edge thereof, and a female screw portion 35 on an inner wall of the opening. The mounting body 40 has a disk shape, and has a large-diameter male screw portion 43 connected to the female screw portion 35 of the container body 30, a through hole 45 opened at the center, and a space portion 47 connected to the through hole. And a connecting portion 49 having a female screw portion 49A on the opposite side of the space portion 47. In addition, the outer periphery of the connection part 49 forms a square pole, and serves as a locking part 49B of the spanner.

When the mounting body 40 is screwed onto the container body 30 to form the casing 20, a flat internal space S is formed therein. One space S2 of the internal space S
In addition, a space portion 47, a through hole 45 having a reduced diameter, and a connection port 49A are arranged on the entrance side. In the space S1 of the internal space S, a flat elastic cushioning body 50 that is thin in the height direction and large in the outer diameter direction is accommodated without a gap. On the surface side of the elastic buffer 50, a thin flat protective film 60 having a larger outer diameter than the elastic buffer is superimposed. The protective film 60 is housed so as to face the through hole 45 with the space S2. The protective film 60 includes a pressing surface 42 of the mounting body 40 screwed to the container body 30 and the container body 3.
The outer peripheral edge 63 of the protective film 60 is held on the inner peripheral wall 23 of the casing 20 by being sandwiched between the outer peripheral step portion 33 of the casing 20.

That is, as shown in FIG. 14, the liquid hammer preventing device 200 includes the casing 20 which is communicated with the flow path 3A of the fluid passage 3 through the through hole 45.
0 denotes a region E in which the inside communicates with the flow path 3A by the protective film 60.
1 and an area E2 in which the elastic buffer 50 is stored. The elastic buffer 50 has a thin flat shape in the thickness direction, and the protective film has a thin flat plate shape.

The material of the elastic cushioning member 50 is, as in the first to sixth embodiments, an initial hardness of Asker C30 to 85 and an apparent specific gravity of 0.30 to 0.70.
Is used. The material of the protective film 60 is a high-strength millable silicone rubber.

The elastic buffer 50 and the protective film 60 are manufactured as follows. The elastic buffer 50 is, for example,
It is manufactured by punching out a sheet material having a thickness of about 10 mm and formed in a flat plate shape into a predetermined circular shape by punching and molding using a press. Similarly, the protective film 60 is also manufactured by punching out a sheet material formed into a flat plate having a thickness of 1.5 to 5 mm, preferably 2 mm, into a predetermined circular shape by press punching.
When the elastic buffer 50 and the protective film 60 are manufactured by the above manufacturing method, the thickness thereof is as thin as about 12 mm, the cut surface can be cut flat, the manufacturing method is simple, and the manufacturing cost is reduced.

Next, FIG. 15 shows a liquid hammer preventing device 210 according to an eighth embodiment having the flat shape. In the liquid hammer prevention device 210 of the eighth embodiment, a casing 20 is made of a metal container body 21 and attached to a mounting body 40 having a connection port 49A and a through hole 45 in the same manner as the conventional structure shown in FIG. It is fastened by caulking means 25. Other configurations are the same as those of the liquid hammer prevention device 200 of the seventh embodiment, and are denoted by the same reference numerals, and description thereof is omitted.

Next, the liquid hammer prevention device 220 of the ninth embodiment shown in FIG. 16 will be described. The liquid hammer preventing device 220 has an internal space S formed at the joint between the large block bodies B1 and B2, and has a through hole 45 narrowed to one side of the internal space and a connection port 49A thereof. In the internal space, a flat elastic buffer 50 thinner in the thickness direction and larger in the outer diameter direction and a flat protective film 60 having a larger outer diameter than the elastic buffer are overlapped with each other. It is structured to be housed so as to face the space 45 and the space 47. The liquid hammer preventing device 220 according to the ninth embodiment does not have any protrusions due to the liquid hammer preventing device, and the size is further reduced. Other configurations are the same as those of the liquid hammer prevention device 200 of the seventh embodiment, and are denoted by the same reference numerals, and description thereof is omitted.

The liquid hammer prevention devices 200 to 220 according to the seventh to ninth embodiments of the present invention are configured as described above and operate as follows. First, the liquid hammer 200-220
The elastic buffer 50 has a flat shape that is thinner in the height direction and larger in the outer diameter direction, and the protective film 60 has a thin flat plate shape whose outer diameter is larger than the elastic buffer 50.
Is held on the inner peripheral wall 23 of the casing 20.

Thus, the elastic buffer 50 and the protective film 60
Means a flat, large outer diameter and a large pressure receiving area. Therefore, when the liquid hammer P exerts a pressure action on the elastic buffer body 50 through the through hole 45, the displacement in the outer diameter direction is taken into account and the lateral displacement is added. The amount increases. Thus, the amount of displacement in the height direction is reduced, and the amount of displacement can be reduced. Therefore, the "play allowance in the vertical direction", which is extended in the liquid hammering direction, which has a margin in the expansion and contraction direction of the protective film in the conventional type, becomes unnecessary. The same performance as the protection film for the liquid hammer is obtained, and the mechanical deterioration of the elastic buffer 50 and the protection film 60 and the deterioration of the liquid prevention function can be maintained for a long time.

Further, since the polyurethane fine foam 51 has a thin flat shape and the protective film 60 has a thin flat plate shape, the height of the elastic buffer 50 and the protective film 60 is reduced. Therefore, the height dimension of the liquid hammer preventing devices 200 to 220 can be reduced, and the space can be saved. As a result, as shown in FIG.
It can be easily attached to the water supply pipe 3 installed in the pipe 3.

Further, since the elastic buffer 50 has a thin flat shape and the protective film 60 has a thin flat plate shape, it is manufactured by punching and molding a sheet material having a predetermined thickness. As a result, since the elastic buffer and the protective film can be manufactured at a low manufacturing cost, the liquid hammer can be provided at a low price, and can be arranged at various places of various devices such as a home washing machine and a dishwasher. It becomes easier. It is a matter of course that the elastic buffer of the embodiment other than the seventh to ninth embodiments is not limited to the manufacturing method by stamping and molding a sheet material having a predetermined thickness from a press.

As described above, according to the liquid hammer prevention devices 200 to 220 of the seventh to ninth embodiments, the following effects are obtained.

First, Asker C30-85 initial hardness
The polyurethane fine foam 51 having an apparent specific gravity of 0.30 to 0.70 has excellent energy absorption / damping characteristics against liquid hammer, maintains the liquid hammer preventing function for a long period of time, and has a flat required volume. It can also be obtained by a free shape such as a shape. Then, even if the volume is reduced to a certain amount, the energy absorption / attenuation characteristics are guaranteed, and the liquid hammer preventing device can be downsized to save space.

Further, in the liquid hammer preventing devices 200 to 220 described above, even when the height of the elastic buffer is reduced, the polyurethane fine foam having a function of preventing liquid hammer excellent in energy absorption / damping characteristics against liquid hammer is exhibited. Adopted, this is thin in the height direction, and has a flat shape large in the outer diameter direction, and the protective film is a thin flat plate having a larger outer diameter than the elastic buffer,
The height dimension between the elastic buffer and the protective film can be reduced. Thereby, the liquid hammer preventing device is manufactured in a structure capable of saving space in the height direction. Therefore, it can be easily stored in a narrow space in a wall or various devices using liquid.

Further, the elastic buffer and the protective film can be manufactured by punching and molding a sheet material having a required thickness with a press, and the elastic buffer and the protective film have a low manufacturing cost and a low liquid hammer prevention. Vessel can be provided. Therefore, it can be installed at low cost in various kinds of equipment using liquids such as a home washing machine.

The liquid hammer preventing device according to the present invention is not limited to the above embodiments, and the design can be changed within the gist. For example, the liquid hammer is not limited to the one used for domestic water taps, the one disposed under a sink, the one attached to a main pipe such as a water pipe, and the liquid equipment such as oil. The present invention can be applied to a liquid hammer preventing device which is configured as a single unit as well as a device which is configured as a part incorporated in a home electric appliance. Also, the casing 20
May be formed of a reinforced plastic material or a stainless steel material. Further, the material of the protective film 60 can be appropriately changed.

Next, a tenth embodiment of the present invention will be described with reference to FIG. 18, FIG. 19, and FIG. The liquid hammer preventing device 300 shown in FIG.
O, an elastic buffer 309 and a casing KO.
A main body 303 having a through hole 301 disposed therein and communicating with the flow path, and a fitting convex part A1 formed to protrude radially inward at an opening edge, and the fitting convex part A1 is provided on the head of the main body 303. The protective film A is fitted into the recessed fitting groove 303E and held and fixed by the inner wall surface 307A of the casing KO.

The main body 303 is provided with a screw portion 303A, which is connected to a water supply pipe. Body 3
03 is provided with a through-hole 301, through which it communicates with the flow path. At the outer peripheral portion 303B of the main body 303, a mounting screw portion 3 is provided.
03C is provided, and the casing KO is fitted thereto and tightened with the screw portions 303C and 307, whereby the main body 3 is provided.
03 and the casing KO are made liquid-tight. In addition, body 3
A ring groove is formed in the outer peripheral portion 303B of the casing 03, and an O-ring R is fitted into the groove, and the O-ring R presses against the inner wall surface 307A of the casing KO to ensure liquid tightness. However, the fitting projection A1 and the fitting groove 3 of the protective film are used.
This configuration is not always necessary because watertightness can be maintained by close contact with E.

A fitting groove 303E is formed integrally with the head 303D of the main body 303 inserted and arranged in the casing KO. The fitting groove 303E is formed so as to protrude radially inwardly D1 at the opening edge of the protective film A. The fitted protrusion A1 is fitted. The protective film A is formed by fitting the fitting projection A1 to the fitting groove 303E.
And the inner wall surface 307A of the casing, the region S1 communicating with the flow path through the through hole, and the region S2 of the elastic buffer 309 housed in the casing KO.
It is divided into and.

As shown in FIG. 21, the fitting protrusion A1 of the protective film is formed by forming a protrusion A4 having two peaks protruding outward in the radial direction on the outer peripheral surface A3. The length H2 between the inner circumferential surface A2 and the outer circumferential surface A3 in the radial direction of A1 is determined by the outer circumferential surface 303F of the fitting groove 303E and the casing KO.
Is set to a depth dimension H1 or more between the inner wall surfaces 307A.

Thus, when the fitting projection A1 of the protective film A is held and fixed by the fitting groove 303E and the inner wall surface 307A of the casing KO, the outer peripheral surface A3 is pressed against the inner wall surface 307A of the casing KO. Being radially inward D
1 and outward D2, and the fitting projection A
The upper and lower surfaces 1 are also swelled and deformed in the axial direction X. Thereby, the inner peripheral surface A2 is formed on the side outer peripheral surface 30 of the fitting groove 303E.
3F is pressed.

Further, the thickness L2 of the fitting protrusion A1 in the protective film A in the axial direction X is slightly larger than the groove width L1 of the fitting groove 303E (specifically, about 0.1 mm). Is set. In this case, the dimensions may be the same. Due to such a dimensional relationship, the lower surface of the upper surface of the fitting protrusion A1 is pressed against the lower surface of the upper surface of the fitting groove 303E.

As the material of the protective film A, a high-strength millable silicone rubber having excellent wear resistance can be suitably used. The elastic buffer 309 is made of a material having an initial hardness of Asker C30 to 85 and an apparent specific gravity of 0.30.
A foam of ~ 0.70 is preferably used. The details are the same as those described in the first to ninth embodiments.

The stopcock type liquid hammer 400 of the eleventh embodiment shown in FIG. 20 is installed in the handle 19 for opening and closing the spindle 11. The spindle 411 includes a screw portion 411A screwed into a female screw portion of a valve body (not shown) and a valve body 413 at the lower end thereof.
The main body 403 is screwed to the upper end of the spindle 411,
A through hole 401 is formed in these axes. The other configuration is the same as that of the liquid hammer prevention device 300, and the description is omitted.

The liquid hammer 30 according to the tenth embodiment of the present invention
The liquid hammer prevention devices 400 of the zeroth and eleventh embodiments are configured as described above, and the operation thereof will be described based on the liquid hammer prevention device 300 as a representative. First, a fitting groove 303 provided in the head of the main body 303 disposed in the casing KO is described.
E, a fitting projection A1 which is formed to protrude inward in the radial direction at the opening edge of the protective film A is fitted to the casing K.
By holding and fixing with O inner wall surface 307A,
It is divided into a region S1 that communicates with the flow path through the through hole 301 and a region S2 of the elastic buffer 309 housed in the casing KO.

As a means for holding the region S1 communicating with the flow path via the through hole 301 and the region S2 of the elastic buffer 309 housed in the casing KO in a liquid-tight manner, the fitting protrusion A1 is fitted. The fitting structure with the mating groove 303E acts.
That is, a protrusion A4 is formed on the outer peripheral surface A3 of the fitting convex portion A1 so as to protrude outward in the radial direction, and the length dimension between the inner peripheral surface A2 and the outer peripheral surface A3 in the radial direction of the fitting convex portion A1 is measured. Since H2 is set to be equal to or greater than the depth dimension H1 between the side outer peripheral surface 303F of the fitting groove 303E and the inner wall surface 307A of the casing KO, the outer peripheral surface is pressed against the inner wall surface 307A of the casing KO and radially inward. D1 and outward D2 are swelled and deformed, and both the upper and lower surfaces of the fitting projection A1 are swelled and deformed in the axial direction X as well. Thereby, the inner peripheral surface A2 is pressed against the side outer peripheral surface 303F of the fitting groove, and a liquid-tight action is exhibited.

Further, the thickness L2 of the fitting projection A1 in the protective film A in the axial direction X is set slightly larger than the groove width L1 of the fitting groove 303E (specifically, about 0.1 mm). Since the lower surface of the upper surface of the fitting protrusion A1 is pressed against the lower surface of the upper surface of the fitting groove 303E, a liquid-tight action is exhibited.

As a result, the fitting protrusion A1 and the fitting groove 30
A liquid-tight action is exerted on each inner surface of 3E to prevent the liquid from entering the area around the elastic buffer 309 housed in the area S2 in the casing KO from the area S1 communicating with the flow path through the through hole 301. Is done. As a result, there is no danger of liquid infiltrating from the region communicating with the flow path through the through hole to the periphery of the elastic buffer housed in another region in the casing. Gone
The function of the liquid hammer can be maintained for a long time. According to the result of the durability test, it is confirmed that the performance is maintained even after the number of continuous supply of 400,000 times. Also, the casing KO
It has been confirmed that there is no leakage of liquid to the outside. The above operation is the same for the liquid hammer 400.

As described above, the liquid hammer preventing devices 300 and 4 of the present embodiment are described.
According to 00, the following effects are obtained. First, since the liquid-tightness is exhibited by fitting the fitting protrusion A1 of the protective film A to the fitting groove 303E of the main body 303, another region in the casing from the region communicating with the flow path through the through-hole. There is no danger of liquid infiltrating into the surroundings of the elastic buffer housed in the region, and there is no problem that the elastic buffer comes to the surface, and the function as a liquid hammer preventing device can be exhibited for a long time.

Further, there is no possibility that the liquid leaks from the casing to the outside, and the soundness of the equipment is maintained. Also,
A fitting protrusion formed radially inward from the opening of the protective film is fitted into a fitting groove provided in the head of the main body disposed in the casing, and is held by the fitting protrusion and the inner wall surface of the casing. -Since the structure is fixed, the number of parts can be reduced, the number of assembling steps can be reduced, the manufacturing cost of the liquid hammer can be reduced, and the product quality can be kept constant.

Next, a liquid hammer preventing device 500 according to a twelfth embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 22, the liquid hammer prevention device 500 includes a casing KO.
And an elastic buffer 509 arranged in the casing KO
And a main body 503 having a through-hole 501 disposed in the casing KO and communicating with the flow path, and a fitting convex part A1 formed on the opening edge so as to protrude inward in the radial direction. The protective film A is fitted into the fitting groove 503E formed in the concave portion and held and fixed by the fitting groove 503E and the inner wall surface of the casing KO.

The main body 503 is provided with a screw portion 503A, which is connected to a water supply pipe. Body 5
03 is provided with a through-hole 501, through which it communicates with the flow path. At the outer peripheral portion 503B of the main body 503, a mounting screw portion 5 is provided.
03C is provided, and the casing KO is fitted thereto and tightened with the screw portions 503C and 507 to thereby form the main body 5C.
03 and the casing KO are made liquid-tight. In addition, body 5
A ring groove is formed in an outer peripheral portion 503B of the casing 03, and an O-ring R is fitted into the groove, and the O-ring R presses against the inner wall surface 7A of the casing KO to ensure liquid tightness.
However, the fitting projection A1 and the fitting groove 503 of the protective film are provided.
This configuration is not always necessary because watertightness can be maintained by close contact with E.

A fitting groove 503E is formed integrally with the head 503D of the main body 503 inserted and arranged in the casing KO, and the fitting groove 503E is formed so as to protrude radially inwardly D1 at the opening edge of the protective film A. The fitted protrusion A1 is fitted. The protective film A is formed by fitting the fitting projection A1 to the fitting groove 503E.
And the inner wall surface of the casing, it is divided into a region S1 communicating with the flow path via the through hole 501 and a region S2 of the elastic buffer housed in the casing KO.

As shown in FIG. 23, the fitting projection A1 of the protective film is formed by forming a projection A4 having two peaks projecting outward in the radial direction D2 on the outer peripheral surface A3. Part A1
Length dimension H2 between the inner peripheral surface A2 and the outer peripheral surface A3 in the radial direction
Is set to be equal to or greater than the depth dimension H1 between the side outer peripheral surface 503F of the fitting groove 503E and the inner wall surface 507A of the casing KO. The protrusion A3 may have a single crest.
The thickness L2 of the fitting protrusion A1 in the protective film A in the axial direction X is set slightly larger (specifically, about 0.1 mm) than the groove width L1 of the fitting groove 503E. I have. In this case, the dimensions may be the same.

As the material of the protective film A, a high-strength millable silicone rubber having excellent wear resistance can be suitably used. The material of the elastic buffer 509 has an initial hardness of Asker C30 to 85 and an apparent specific gravity of 0.30.
A foam of ~ 0.70 is used. The details are the same as those of the first embodiment, and the description is omitted.

The outer peripheral surface 503 of the side of the fitting groove 503E.
F has a protrusion 503G formed of two peaks bulging outward in the radial direction D2. Accordingly, when the fitting protrusion A1 of the protective film A is held and fixed by the fitting groove 503E and the inner wall surface 507A of the casing KO, the protrusion 5
03G is pushed into the inner peripheral surface of the fitting projection A1, and the fitting projection A1 of the protective film is pushed by the projection 503G and swells and deforms in the radial and axial directions. Thereby, the fitting convex portion A1
Is pressed against the inner wall surface of the casing KO, and the reaction force causes the inner peripheral surface of the fitting projection A1 to project from the projection 503G.
To be strongly pressed.

Further, a thin lip A5 is formed on the lower surface on the radially inner side of the fitting projection A1. When the liquid enters the fitting groove 503E,
The pressure receiving surface A extends in a direction substantially orthogonal to the direction of action of the liquid pressure J1.
6, the liquid pressure J1 is displaced in the direction of the hydraulic pressure and is brought into close contact with the lower surface of the fitting groove 503E, thereby exhibiting a high liquid-tight action.

The liquid hammer 50 according to the twelfth embodiment of the present invention
0 is configured as described above and operates as follows. First, the main body 50 disposed in the casing KO
3 is fitted into the fitting groove 503E provided in the head of the protective film A, and the fitting protrusion A1 which is formed so as to protrude inward in the radial direction at the opening edge of the protective film A is held and held by the inner wall surface 507A of the casing KO. By being fixed, it is divided into a region S1 that communicates with the flow path via the through hole 501 and a region S2 of the elastic buffer 509 housed in the casing KO.

As means for holding the region S1 communicating with the flow path via the through hole 501 and the region S2 of the elastic buffer 509 housed in the casing KO in a liquid-tight manner, the fitting protrusion A1 is fitted. The fitting structure with the mating groove 503E operates.
That is, a protrusion A4 is formed on the outer peripheral surface of the fitting convex portion A1 so as to protrude outward in the radial direction, and a length dimension H2 between the inner peripheral surface A2 and the outer peripheral surface A3 in the radial direction of the fitting convex portion A1 is formed. Is set to be equal to or greater than the depth dimension H1 between the side outer peripheral surface 503F of the fitting groove 503E and the inner wall surface 507A of the casing KO.
The fitting protrusion A1 of the protective film A is fitted to the fitting groove 503 of the main body 503.
E, and when it is held and fixed by the inner wall surface of the casing KO, this outer peripheral surface
Is pressed against the inner wall surface 507A and bulges inward in the radial direction D1 and outward D2, and both upper and lower surfaces of the fitting projection A1 bulge in the axial direction X. Thereby, the inner peripheral surface A2 is pressed against the side outer peripheral surface 503F of the fitting groove 503E. Further, a projection 503G formed so as to protrude radially outward on a side outer peripheral surface of the fitting groove 503E is pushed into the inner peripheral surface of the fitting projection A1, and the fitting projection of the protective film is formed as a projection. By being pushed by 503G, it further expands and deforms radially outward D2. As a result, the outer peripheral surface of the fitting convex portion A1 is pressed against the inner wall surface of the casing KO, and the inner peripheral surface of the fitting convex portion is strongly pressed by the projection 503G due to the reaction force, so that a liquid-tight action is exerted on both surfaces. Be demonstrated.

Further, the thickness L2 of the fitting protrusion A1 in the protective film A in the axial direction X is set slightly larger than the groove width L1 of the fitting groove 503E (specifically, about 0.1 mm). Due to such a dimensional relationship, the lower surface of the upper surface of the fitting protrusion A1 is pressed against the lower surface of the upper surface of the fitting groove 503E, and the liquid-tight action is exerted here as well.

Further, a thin lip A5 is formed on the lower surface of the protective film on the radially inner side of the fitting projection A1. In the case where the liquid enters the fitting groove portion 503E, the lip portion A5 is strongly adhered to the lower surface of the fitting groove portion 503E by receiving a force in the direction of the hydraulic pressure, and a high liquid-tight action is exhibited. You.

As a result, the fitting projection A1 and the fitting groove 50 are formed.
A strong liquid-tight action is exerted on the inner surface of the casing KO from the region S1 communicating with the flow path through the through hole 1.
The liquid is prevented from entering the periphery of the elastic buffer 509 housed in the housing 2.

As described above, according to the liquid hammer prevention device 500 of the present embodiment, the following effects are obtained. First, the fitting protrusion A
1, the fitting protrusion A1 of the protective film A is formed by the protrusion A4 on the outer peripheral surface.
Is fitted in the fitting groove portion 503E of the main body 503, and is swelled and deformed in the radially inward direction D1 and the outward direction D2, and is formed on the inner peripheral surface of the fitting convex portion A1 by the projection portion 503G of the fitting groove portion 503E. It is pushed in and swells and deforms in the radial and axial directions. As a result, the outer peripheral surface of the fitting projection A1 is
While being pressed by the inner wall surface 507A of O, the inner peripheral surface of the fitting convex part A1 is strongly pressed by the protrusion 503G by the reaction force. Therefore, strong liquid tightness is exhibited, and there is no danger of liquid infiltrating from the region communicating with the flow path through the through hole to the periphery of the elastic buffer housed in another region in the casing. There is no problem that the surface comes to the surface, and the function as the liquid hammer preventing device can be exhibited for a long time as in the tenth embodiment.

Further, there is no possibility that the liquid leaks from the casing KO to the outside, and the soundness of the equipment is maintained. In addition, a fitting convex portion A1 which is formed to protrude inward in the radial direction into the opening of the protective film is fitted into a fitting groove portion 503E provided in the head of the main body arranged in the casing, and the fitting convex portion A1 is formed inside the casing. Since it is structured to be held and fixed to the wall, the number of parts can be reduced, the number of assembling steps can be reduced, the manufacturing cost of the liquid hammer prevention device can be reduced, and the product quality can be kept constant.

Next, a liquid hammer prevention device 600 according to a thirteenth embodiment of the present invention will be described with reference to FIG. Liquid hammer 600
Is such that a projecting portion projecting outward in the radial direction is formed on the outer peripheral surface of the side of the fitting groove. As shown in FIG. 24, a fitting groove 603E is formed integrally with the head 603D of the main body 603 inserted and arranged in the casing KO, and the fitting groove 603E is formed on the opening edge of the protective film A in a radially inward direction D1. The fitting protrusion A1 that is formed to protrude is fitted. The protective film A is formed by holding and fixing the fitting projection A1 between the fitting groove 603E and the inner wall surface of the casing, so that the region communicating with the flow path through the through hole and the elastic buffer housed in the casing KO. It is divided into body areas.

The fitting projection A1 of the protective film has a length H2 between the inner peripheral surface A2 and the outer peripheral surface A3 in the radial direction.
Is set to be approximately the same as the depth H1 between the outer peripheral surface 603F of the fitting groove 603E and the inner wall surface 607A of the casing KO. Further, the fitting protrusion A on the protective film A
1, the thickness L2 in the axial direction X is equal to the fitting groove 603.
E is slightly larger than the groove width dimension L1 (specifically, 0.1
mm). In this case, the dimensions may be the same.

On the outer peripheral surface 3F of the side of the fitting groove 603E, a projection 60 composed of two peaks bulging outward in the radial direction D2 is provided.
3G is formed. The protrusion 603G may have a single peak. Thus, when the fitting protrusion A1 of the protective film A is held and fixed between the fitting groove 603E and the inner wall surface of the casing KO, the protrusion 603G is pushed into the inner peripheral surface of the fitting protrusion A1. The fitting projection of the protective film is pushed by the projection and swells and deforms in the radial and axial directions.
Thus, the outer peripheral surface of the fitting convex portion A1 is pressed against the inner wall surface 607A of the casing KO, and the inner peripheral surface of the fitting convex portion A1 is strongly pressed by the projection 603G due to the reaction force. I have. Other configurations are the same as those of the twelfth embodiment, and description thereof will be omitted.

The liquid hammer preventing device 60 according to the thirteenth embodiment of the present invention.
0 is configured as described above and operates as follows. First, the main body 60 disposed in the casing KO
3 is fitted into the fitting groove 603E provided on the head of the casing 3, and the fitting projection A1 which is formed to protrude inward in the radial direction from the opening edge of the protective film A is fitted and held by the inner wall surface of the casing KO.
Fix it. Then, the projection 603G formed so as to protrude outward in the radial direction on the outer peripheral surface of the side of the fitting groove 603E is pushed into the inner peripheral surface of the fitting projection A1, and the fitting projection A1 of the protective film becomes a projection. The upper and lower surfaces of the fitting protrusion A1 are also swelled and deformed in the axial direction X while being swelled and deformed outward in the radial direction by being pushed by the portion 603G. Thereby, the fitting convex portion A1
Is pressed against the inner wall surface of the casing KO, and the reaction force causes the inner circumferential surface of the fitting projection to be pressed by the protrusion 603G, so that a liquid-tight action is exerted on both surfaces.

Further, the thickness L2 of the fitting projection A1 in the protective film A in the axial direction X is set slightly larger than the groove width L1 of the fitting groove 603E (specifically, about 0.1 mm). Due to such a dimensional relationship, the upper surface lower surface of the fitting protrusion A1 is pressed against the upper surface lower surface of the fitting groove portion 603E, thereby exerting a liquid-tight action.

As a result, the fitting projection A1 and the fitting groove 60
A liquid-tight action is exerted on the inner surface of the casing KO from the region S1 communicating with the flow path through the through hole 601.
The liquid is prevented from entering the periphery of the elastic buffer 609 housed in the housing 2.

As described above, according to the liquid hammer preventing device 600 of the present embodiment, the following effects can be obtained. The protrusion 603G of the fitting groove 603E pushes into the inner peripheral surface of the fitting convex portion A1 and swells and deforms in the radial direction and the axial direction, whereby the outer peripheral surface of the fitting convex portion A1 becomes Inner wall 607A
And the inner peripheral surface of the fitting projection A1 is strongly pressed by the projection 603G due to the reaction force. Therefore, liquid tightness is exhibited, and there is no danger of liquid infiltrating from the region communicating with the flow path through the through hole to the periphery of the elastic buffer housed in another region in the casing. There is no longer a problem of floating, and the function as a liquid hammer preventing device can be exerted for a long time as in the tenth embodiment.

Further, there is no possibility that liquid leaks from the casing KO to the outside, and the soundness of the equipment is maintained. In addition, a fitting protrusion A1 which is formed to protrude inward in the radial direction into an opening of the protective film is fitted into a fitting groove 603E provided in the head of the main body arranged in the casing, and the fitting protrusion A1 is fitted in the casing. Since it is structured to be held and fixed to the wall, the number of parts can be reduced, the number of assembling steps can be reduced, the manufacturing cost of the liquid hammer prevention device can be reduced, and the product quality can be kept constant.

The liquid hammer preventing device according to the present invention is not limited to the above embodiments, and the design can be changed within the gist. For example, in the liquid hammer prevention devices of the tenth, eleventh, and thirteenth embodiments, a structure in which a thin lip portion A5 is formed on the fitting projection A1 may be employed. Even with this configuration, the twelfth
The same effect as the liquid hammer preventing device of the embodiment can be obtained. Further, the casing KO may be formed of a reinforced plastic material or a stainless material. Further, the material of the protective film A can be appropriately changed. In addition, the liquid hammer prevention device of the present invention is not limited to a device that prevents noise generated due to a sudden pressure fluctuation due to a sudden closing of a valve in a piping system, but also a device such as a centrifugal pump, a centrifugal compressor, or the like that generates a surge. The present invention can also be applied to the case of preventing noise due to an excitation phenomenon and pulsating noise generated by a pulsating flow of a pump.

[0111]

As described in detail above, in the case of the liquid hammer according to the present invention, the elastic buffer has an initial hardness of Asker C30.
Since it is formed of a foam having an apparent specific gravity of 0.30 to 0.70 and an apparent specific gravity of 0.30 to 0.70, an effect of maintaining a liquid hammer prevention function excellent in energy absorption / damping characteristics with respect to liquid hammer over a long period of time is exhibited. You. Further, the degree of freedom in shape change is increased, and it is possible to cope with space saving.

Further, the liquid hammer preventing device is an inner flange type, and is formed so as to protrude radially inward from an opening edge of the protective film in a fitting groove formed in a head of a main body disposed in the casing. In the case where the fitting projection is fitted and held and fixed between the fitting projection and the inner wall surface of the casing, liquid tightness is exhibited, and thereby, the region communicating with the flow path through the through hole is provided. There is no danger of liquid infiltrating into the surroundings of the elastic buffer housed in another area in the casing, thereby eliminating the problem that the elastic buffer floats up and exhibiting the function as a liquid hammer for a long time be able to. In addition, there is no possibility of liquid leakage from the casing to the outside, and the soundness of the device is maintained. In addition, the number of parts can be reduced, the number of assembling steps can be reduced, the manufacturing cost of the liquid hammer preventing device can be reduced, and the product quality can be kept constant.

In the above configuration, if a thin lip portion is formed on the lower surface of the protective film on the radially inner side of the fitting protrusion, even if a liquid intrudes into the fitting groove,
The lip portion is strongly adhered to the inner surface of the fitting groove portion by receiving the force in the direction of the hydraulic pressure action, so that a more reliable liquid-tight action can be exhibited.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a liquid hammer preventing device according to a first embodiment of the present invention.

FIG. 2 shows a second embodiment of the present invention and is a cross-sectional view of a liquid hammer prevention device.

FIG. 3 shows a third embodiment of the present invention and is a cross-sectional view of a liquid hammer prevention device.

FIG. 4 is a sectional view of a liquid hammer preventing device according to a fourth embodiment of the present invention.

FIG. 5 is a sectional view of a liquid hammer preventing device according to a fifth embodiment of the present invention.

FIG. 6 shows a sixth embodiment of the present invention and is a cross-sectional view of a liquid hammer prevention device.

FIG. 7 is a characteristic diagram of the liquid hammer preventing device in each of the above embodiments of the present invention.

FIG. 8 is a characteristic diagram of the liquid hammer preventing device in each of the above embodiments of the present invention.

FIG. 9 is a characteristic diagram of the liquid hammer preventing device in each of the above embodiments of the present invention.

FIG. 10 is a characteristic diagram of the liquid hammer preventing device in each of the above embodiments of the present invention.

FIG. 11 is a characteristic diagram of the liquid hammer preventing device in each of the embodiments of the present invention.

FIG. 12 is an exploded perspective view of a liquid hammer preventing device according to a seventh embodiment of the present invention.

FIG. 13 shows a seventh embodiment of the present invention and is a cross-sectional view of a liquid hammer prevention device.

FIG. 14 shows a seventh embodiment of the present invention, and is an operation sectional view of a liquid hammer prevention device.

FIG. 15 is a sectional view of a liquid hammer preventing device according to an eighth embodiment of the present invention.

FIG. 16 shows a ninth embodiment of the present invention and is a cross-sectional view of a liquid hammer prevention device.

FIG. 17 is a view showing an installed state of a liquid hammer preventing device according to seventh to ninth embodiments of the present invention.

FIG. 18 is a developed perspective view of the liquid hammer preventing device according to the tenth embodiment of the present invention.

FIG. 19 is a cross-sectional view of an externally mounted liquid hammer prevention device according to a tenth embodiment of the present invention.

FIG. 20 is a sectional view of a stopcock type liquid hammer according to an eleventh embodiment of the present invention.

FIG. 21 is an operation sectional view of a protective film according to a tenth embodiment and an eleventh embodiment of the present invention.

FIG. 22 is a developed perspective view of the liquid hammer preventing device according to the twelfth embodiment of the present invention.

FIG. 23 is an operation sectional view of a protective film according to a twelfth embodiment of the present invention.

FIG. 24 is an operation sectional view of a protective film according to a thirteenth embodiment of the present invention.

FIG. 25 is a cross-sectional view of a conventional outer flange type liquid hammer.

FIG. 26 is an operation view of a conventional outer flange type liquid hammer preventing device.

FIG. 27 is a cross-sectional view of a conventional inner flange type externally mounted liquid hammer preventer.

FIG. 28 is a cross-sectional view of a conventional inner flange type water stopcock type liquid hammer preventer.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Through-hole 2 Valve main body 2A Vertical screw 3 Water pipe 3A Flow path 5 Valve seat 7 Valve 9 Spindle 19 Handle 20 Casing 23 Inner peripheral wall 25 Caulking means 30 Container body 33 Step peripheral part 35 Female screw part 40 Mounting member 43 Male screw part 45 Through hole 47 Space part 49A Connection port 49B Lock part 50 Elastic buffer 51 Polyurethane fine foam 60 Protective film 63 Peripheral edge 70 Washing machine 73 Space 130A One-touch faucet 131 Main body 139 Lever 130 Faucet 140A With liquid hammer Stopcocks B1 and B2 Block body E1, E2 Area F Protective film F1 Expandable portion F2 Outer edge F3 Outer flange F4 Mounting screw portion F5 Protective film pressing portion K0 Casing P1 Piping S Internal space 301 Through hole 303 Main body 303A Screw portion 303B Outer periphery Part 303C, 307 Mounting screw part 303D Head 303E Fitting groove portion 303F Side outer peripheral surface 503G Projecting portion 307A Inner wall surface 309 Elastic buffer D1, D2 Radial outward and inward A Protective film A1 Fitting convex portion A2 Inner peripheral surface A3 Outer peripheral surface A4 Projecting portion A5 Lip portion A6 Pressure receiving surface J1 Liquid pressure KO Casing L1 Groove width dimension L2 Thickness dimension H1 Depth dimension between inner wall surface and groove outer peripheral surface of casing H2 Dimension between inner peripheral surface and outer peripheral surface RO ring S1, S2 area X Axial direction

Claims (8)

[Claims] 1. A casing that communicates with a liquid flow path through a through hole, an elastic buffer that is accommodated in the casing, an area that communicates the casing with the flow path, and an elastic buffer. A liquid hammer wherein the elastic buffer is a foam having an initial hardness of Asker C30 to 85 and an apparent specific gravity of 0.30 to 0.70. . 2. A casing which communicates with the liquid flow path through a through hole, an elastic buffer accommodated in the casing, an area which communicates the casing with the flow path, and an elastic buffer. A liquid hammer comprising a protective film partitioned into two regions, wherein the elastic buffer is a foam having an initial hardness of Asker C50 to 85 and an apparent specific gravity of 0.30 to 0.40. . 3. A casing which communicates with the liquid flow path via a through hole, an elastic buffer accommodated in the casing, an area which communicates the casing with the flow path, and an elastic buffer are accommodated. And a protective film that is divided into regions. The elastic shock absorber is a foam having an initial hardness of Asker C55 to 70 and an apparent specific gravity of 0.30 to 0.40. . 4. The elastic buffer has a flat shape thinner in a thickness direction and larger in an outer diameter direction, and the protective film has a flat plate shape having a larger outer diameter than the elastic buffer. The liquid hammer according to any one of claims 1 to 3, wherein the liquid hammer is held on an inner peripheral wall of the casing. 5. A casing, an elastic buffer disposed in the casing, a main body having a through-hole disposed in the casing and communicating with a flow path, and a fitting formed to protrude radially inward at an opening edge. A protective film which has a convex portion and which fits the fitting convex portion into the fitting groove formed in the head of the main body and is held and fixed by this and the inner wall surface of the casing; On the outer peripheral surface of the fitting protrusion, the length dimension between the inner peripheral surface and the outer peripheral surface in the radial direction of the fitting protrusion is equal to or greater than the depth dimension between the side outer peripheral surface of the fitting groove and the inner wall surface of the casing. 4. A liquid hammer according to any one of claims 1 to 3, wherein a protrusion protruding outward in the radial direction is formed on the liquid hammer. 6. A casing, an elastic buffer disposed in the casing, a main body having a through-hole disposed in the casing and communicating with the flow path, and a fitting formed to protrude radially inward at an opening edge. A protective film that has a convex portion and that fits the fitting convex portion into the fitting groove formed in the head of the main body and that is held and fixed by this and the inner wall surface of the casing; The liquid hammer preventive device according to any one of claims 1 to 3, wherein a protrusion protruding outward in the radial direction is formed on an outer peripheral surface of a side portion of the mating groove portion. 7. A casing, an elastic buffer disposed in the casing, a main body disposed in the casing and having a through hole communicating with a flow path, and a fitting formed to protrude radially inward at an opening edge. A protective film which has a convex portion and which fits the fitting convex portion into the fitting groove formed in the head of the main body and is held and fixed by this and the inner wall surface of the casing; On the outer peripheral surface of the fitting protrusion, the length dimension between the inner peripheral surface and the outer peripheral surface in the radial direction of the fitting protrusion is equal to or greater than the depth dimension between the side outer peripheral surface of the fitting groove and the inner wall surface of the casing. And a protrusion protruding radially outward is formed on the outer peripheral surface of the side of the fitting groove, and the main body is formed with a protrusion protruding outward in the radial direction. The liquid hammer prevention device according to any one of the preceding claims. 8. The protective film has a thin lip formed on the lower surface on the radially inward side of the fitting projection in close contact with the lower surface of the fitting groove by a hydraulic action. The liquid hammer preventing device according to any one of the above items.