JPH08312871A - Water hammer buffering device - Google Patents

Abstract

PURPOSE: To provide a buffering device effective not only for primary water hammer, but also for secondary water hammer caused through repulsion by forming a second airtight chamber continued to a first airtight chamber across a partition wall which has large diameter communication holes freely communicated through check valves, and a small diameter communication hole always communicated. CONSTITUTION: An elastic body 2 is fixed to a main pipe 1 over a range provided with through-holes 11 of the pipe 1, for covering all of them in a steady state. A first airtight chamber 3 is a structural body fixed to an outer peripheral surface of the main pipe 1, and continued to a second airtight chamber 5 across a partition plate 4. The first airtight chamber 3 is communicated with the second airtight chamber 5 through bilateral large diameter communication holes 41 and a center small diameter communication hole 42 on the partition plate 4. A check valve 51 is provided on the side of the second airtight chamber 5 of each of the large diameter communication holes 41. In a usual state, the large diameter communication hole is closed by the self weight of the check valve. When pressing force is energized from a lower side exceeding the self weight, the large diameter communication hole 41 is opened through rotation of the valve.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water hammer shock absorber which is installed in a pipe line to prevent damage caused by a water hammer caused by something.

[0002]

2. Description of the Related Art When a flow rate (velocity) in a pipeline changes rapidly, a pressure wave is generated and the pressure in the pipeline rises abnormally. It is not rare to have troubles that cause damage. The phenomenon of so-called water hammer or water hammer is one of the most important items in the maintenance of pipelines, and attention must be paid to it. For example, if the pump that maintains the water pressure in the pipe fails and stops, the water pressure on the downstream side may exceed the upstream side and may flow backward.Therefore, a check valve is installed at a key point in the pipeline to prevent backflow. Often. However, when the check valve operates, the reverse flow is blocked as intended, but there is a risk that a pressure wave is generated and the water pressure on the downstream side suddenly rises. In addition, the fact that there is a similar risk when water use on the downstream side is temporarily interrupted is a factor that cannot be ignored. It should be noted that this phenomenon occurs regardless of the type of fluid as long as it is a fluid flowing in the pipe.

FIG. 2 shows an example of a conventional water hammer shock absorber, in which a closed chamber 101 communicating with the main pipe 1a is provided in the middle of the pipe to enclose a gas having a constant pressure in the upper portion of the chamber. When a water hammer occurs, the unsteady internal pressure of the pipe is consumed in the middle of the pipeline, the energy of the water hammer is lost, and the purpose of preventing damage by the shock wave is fulfilled.

FIG. 3 and FIG. 4 are also devices for interposing in the pipe line for the purpose of buffering the water hammer, and FIG. 3 is a system called a diaphragm type, in which the diaphragm 10 is inserted into a closed container.
2 is attached and the inside of the vessel is divided into a pipe side 103 (lower side in the figure) and an airtight chamber 104 in which a gas of a constant pressure is sealed, and when a water hammer occurs in the pipe, the gas in this airtight chamber is By compressing, the energy of the water hammer is consumed. In addition, FIG. 4 is a system called a bladder type, in which a bladder 105 is installed in an airtight container to form an airtight chamber 106, and when the water hammer occurs, the energy is absorbed by gas compression in the airtight chamber. Yes,
Due to its structure, it is said that it is suitable for accumulating a small amount of pressure and absorbing pulsation.

As a type of prior art directly attached to the main pipe of the pipeline, there is also a type as shown in FIG. In this example, a large number of through holes 108 are bored in an inner pipe 107 which is directly interposed in the main pipe, an outer peripheral surface of the inner pipe 107 is surrounded by an elastic body 109, and an outer cylinder 110 which further surrounds the outer peripheral side of the elastic body 109 is formed. It is capped and has a structure in which an appropriate level of gas is sealed in the space between the outer cylinder 110 and the elastic body 109. As a result, when a water hammer that impacts the members that make up the pipe, such as the pipe itself, joints, valves, pumps, etc. suddenly occurs and a sudden increase in pressure begins in the main pipe, the water penetrates due to the high pressure in the pipe. From the hole 108 to the elastic body 109
Is pressed and expanded, and the elastic body 109 and the outer cylinder 11 on the outer peripheral side
The volume between 0 and 0 is compressed and reduced, and this action consumes the energy of the water hammer, and has the effect of preventing adverse effects such as damage and deformation around the pipeline.

[0006]

However, none of the conventional techniques illustrated here has the problem that the purpose of preventing water hammer is not always satisfied. Although there is a method that cannot be applied to a case with a structurally large capacity (Figs. 3 and 4), the bigger problem is that the prior art water hammer shock absorbers are all transient phenomena without exception. It is in the point that I understand. That is, when a sudden rise in the pipe pressure suddenly occurs in the pipeline due to any of the above causes, and when it reaches the shock absorber interposed during the rapid propagation in the pipeline, it is installed inside the shock absorber. The elastic body is pressed and elastically deformed to the side opposite to the duct to press the airtight chamber, the high pressure in the duct is consumed and the pressure is reduced, and the action is common.

However, when a water hammer occurs in the actual piping system, the elastic body is suddenly pressed and deformed to compress the volume of the airtight chamber as described above. This deformation returns to the original state, and the reaction causes the volume of the airtight chamber to rapidly expand.
This rapid expansion abruptly presses the pressure in the pipeline, so that the pressure in the pipeline again rapidly rises and induces a secondary water hammer. That is, the sudden shock of the primary water hammer causes the secondary water hammer to be generated, and the shocking and destructive pressure pulsates again in the pipeline to form the cause of unexpected damage. . Since the water hammer is a continuously pulsating shock wave as described above, it cannot be considered as a satisfactory preventive measure simply by consuming the energy at that moment by recognizing it as a transient pressure increase.

In order to solve the above-mentioned problems, an object of the present invention is to provide a shock absorber that is effective not only for a primary water hammer but also for a secondary water hammer that is reactively induced. .

[0009]

SUMMARY OF THE INVENTION A shock absorber for a water hammer according to the present invention comprises an elastic body 2 attached to a plurality of through holes 11 formed in a main body 1, and a book surrounding the elastic body 2. A partition plate 4 having a first airtight chamber 3 fixed to the pipe 1, a large-diameter communication hole 41 openably and closably communicating with the first airtight chamber 3 via a check valve 51, and a small-diameter communication hole 42 always communicating with the first airtight chamber 3. The above-mentioned problem is solved by the second airtight chamber 5 that is connected to the second airtight chamber with a space between the second airtight chamber 5 and the internal pressure sealing means 6 that is openably and closably connected to the second airtight chamber 5.

In the above basic structure, the internal pressure enclosing means 6
Is a preferred embodiment in which a pressure adjusting valve 63 for adjusting the internal pressures of the first airtight chamber 3 and the second airtight chamber 5 is freely openable and closable.

[0011]

[Operation] While the inside of the conduit is maintained at a normal inner pressure, a large number of through holes formed in the main pipe are closely attached by the elastic body to disconnect the main pipe from the first hermetic chamber. Is dripping The first airtight chamber and the second airtight chamber are kept at a constant inner pressure by the action of the inner pressure sealing means, and the large-diameter communication hole of the partition plate, which is the boundary between the first airtight chamber and the second airtight chamber, is non-returned. They are closed by a valve, and they communicate with each other only through a small diameter communication hole to maintain a uniform internal pressure.

When a water hammer occurs in the pipe line and the pressure in the pipe rises abnormally, the pressure passes through the through hole and presses the attached elastic body to elastically deform the first airtight chamber. The internal pressure rises sharply because the volume decreases sharply. Due to this pressurizing action, the check valve that had been closed until then is opened, and the line pressure that has entered from the line in the state where the first airtight chamber and the second airtight chamber are connected by the large diameter communication hole and the small diameter communication hole. Accept. When the internal pressure of the pipe, the pressure of the first airtight chamber, and the pressure of the second airtight chamber are balanced, the check valve closes because the pressure is equalized between the first airtight chamber and the second airtight chamber, and the communication between the two chambers is the same as before. Only the communication hole. As the water hammer is suppressed, the expanded elastic body tries to return from the deformed state to the original attached state, but until the pressure inside the pipe returns to normal, it can return only to a level that equilibrates with this pressure inside the pipe. Can not. Since the pressure from the second airtight chamber is constantly applied to the first airtight chamber through the small diameter communication hole, the deformation of the elastic body is gradually recovered by this pressing force to push back the pipe internal pressure, Only when the pressure in the closed chamber becomes higher, the elastic deformation of the elastic body disappears completely, and the elastic body is attached to the outer peripheral surface of the main pipe to close the through hole communicating with the first airtight chamber.

In summary of the above operation, when a water hammer occurs in the pipeline, the shock absorber immediately communicates with the pipeline to rapidly buffer the abnormal pressure, and after the water hammer is sedated, the communication is gradually resumed. A remarkable feature is that it slowly returns to a steady state while maintaining a slight buffering effect while closing.

The operation according to claim 2 is that the internal pressures of the first airtight chamber and the second airtight chamber are arbitrarily increased or decreased to make a normal adjustment so as to meet the peculiar conditions of the water hammer of the pipeline. A possible action is obtained.

[0015]

1 (A) and 1 (B) are a vertical sectional front view (A) and a side view (B) showing an embodiment of the present invention. In the case of this embodiment, not only fresh water but also sewage mixed with solid matter, sewage, etc., for example, it can be applied to a pipeline of a mud shield method often used in tunnel excavation work, and is extremely versatile. This is a rich example. When attaching the shock absorber installed at an arbitrary position to the main pipe 1, a plurality of through holes 11 are bored in the pipe body of the main pipe. In the example of this drawing, the through holes 11 are arranged such that the upper half of the shaft center is regularly evenly arranged, and the buffer of the water hammer is evenly received and eliminated, but it is not limited thereto. Of course, it is needless to say that they may be arranged in any of the pipe bodies of the main pipe 1 under the condition matched with the pipe line used.

The elastic body 2, which is capped and attached to the main pipe 1 in the steady state, is fixed to the main pipe 1 over the entire area where the through hole 11 is provided. The fixing method is arbitrary, but it is desirable to fasten it together with the end portion of the first hermetic chamber 3 with the bolt nut 21 as shown in the figure so as to firmly sandwich it so as to sufficiently resist impact. The elastic body is made of a natural or synthetic rubber having a suitable elastic modulus. The first airtight chamber 3 is a structure fixed on the outer peripheral surface of the main pipe 1, and the second airtight chamber 5 at the upper part is separated by the partition plate 4.
Is connected to. The partition plate 4 penetrates four large-diameter communication holes 41 on the left and right and two small-diameter communication holes 42 in the center to communicate the first airtight chamber 3 and the second airtight chamber 5, of which the large-diameter communication Check valves 51 are attached to the second airtight chamber 5 side of the holes 41, respectively, and in a steady state, the large diameter communication holes 41 are closed by the dead weight of the check valve, and a pressing force exceeding this dead weight is urged from below. The large-diameter communication hole 41 is opened by rotating. The second hermetic chamber 5 and the first hermetic chamber 3 are generally manufactured by an iron plate structure by welding and assembly. Also, main 1
Is generally made of an iron plate structure, but if the liquid in the flowing pipeline is corrosive, reinforced plastic,
It is necessary to select a corrosion resistant material such as stainless steel, and when a fluid mixed with a solid substance such as the above-mentioned muddy water shield method is targeted, it is also effective to manufacture it with a wear resistant metal material.

An internal pressure sealing means 6 is attached to the upper part of the second hermetic chamber 5. That is, the first airtight chamber 3 and the second airtight chamber 5 need a means for always maintaining an internal pressure higher than the steady pressure in the pipe. In the example of this figure, a pressure gas source (not shown) (for example, a compressor) Pressure supply pipe 6 connected to
1. A stop valve 62 and a pressure adjusting valve 63 that connect and disconnect the air supply and exhaust. Of these, the pressure adjusting valve 63 is a member that plays a role of adjusting the internal pressures of the first airtight chamber 3 and the second airtight chamber 5, and is appropriately adjusted to meet the unique conditions of the water hammer that are different depending on the pipeline. Adjust the shock absorber internal pressure to accommodate. Further, even if the flow condition of the fluid passing through the pipe is changed even in the same pipeline, there is a high possibility that the water hammer will change, so that the first hermetic chamber 3 or Increasing or decreasing the internal pressure of the second hermetic chamber 5 may lead to more effective prevention of water hammer.

With respect to the operation of this embodiment shown in FIG. 1, portions which overlap with the above description will not be repeated for the sake of simplicity. In the figure, the elastic body 2 is closely attached to the outer peripheral surface of the main pipe 1 when the pipe line is constantly maintained,
When an abnormal pressure rise occurs in the conduit, it swells as shown by the chain double-dashed line in the figure, and the action of instantaneously reducing the volume of the first hermetic chamber 3 is exhibited. As described above, after the abnormal pressure disappears, it gradually contracts and returns to the original impregnation state. In the figure, the check valve 51 is a tilt pin 52.
It is rotatably supported by, and normally has a shape with a center of gravity at a position where it blocks the large diameter communication hole 41 by its own weight, and when a pressing force exceeding its own weight is applied, as shown by the chain double-dashed line in the figure. The tilting pin is rotated about the fulcrum to open the large diameter communication hole 41. This check valve is merely an example, and any type of check valve may be used. Further, the check valve is provided with a spring that always biases the valve in the closing direction, and is accompanied by a biasing force such as hydraulic pressure. It goes without saying that it may be a model.

[0019]

As described above, according to the present invention, since the water hammer shock absorber of the prior art is limited to the transient and temporary operation, it is impossible to completely prevent the water hammer and it is unintentional. It overcomes the drawbacks that were only demonstrated by its function, and has the outstanding effect of completely maintaining the safety of pipelines and the maintenance of equipment. As a result, not only the maintenance of the pipeline but also the secondary effect of improving the production efficiency of the construction site including the pipeline and the entire factory equipment and improving the overall workability cannot be overlooked. It should be noted that the service life can be further extended by appropriately selecting the material used for the shock absorber, or the optimum operating conditions matching the conditions of each used pipeline can be set by adjusting the shock absorbing function as in claim 2. Since it also has variability, it also has the effect of playing a part in work improvement that meets individual conditions.

[Brief description of drawings]

FIG. 1 is a vertical sectional front view (A) and a partial sectional side view (B) of an embodiment of the present invention.

FIG. 2 is a vertical sectional front view of a conventional technique.

FIG. 3 is a vertical sectional front view of another conventional technique.

FIG. 4 is a partially sectional front view of still another conventional technique.

FIG. 5 is a vertical sectional front view of still another conventional technique.

[Explanation of symbols]

 1 main pipe 2 elastic body 3 first airtight chamber 4 partition plate 5 second airtight chamber 6 internal pressure sealing means 11 through hole 41 large diameter communication hole 42 small diameter communication hole 51 check valve 63 pressure control valve

Claims (2)

[Claims] 1. In a water hammer shock absorber interposed in a pipe, a plurality of through holes 11 formed in a pipe body of a main pipe 1.
An elastic body 2 attached to the first airtight chamber 3 that surrounds the elastic body 2 and is fixed to the main pipe 1, and a large-diameter communication that opens and closes the first airtight chamber 3 via a check valve 51. A second airtight chamber 5 connected to each other with a partition plate 4 having a hole 41 and a small-diameter communication hole 42 that is always in communication with each other, and an internal pressure sealing means 6 that is openably and closably connected to the second airtight chamber 5. Water hammer shock absorber. 2. The water according to claim 1, wherein the internal pressure enclosing means 6 is provided with a pressure adjusting valve 63 capable of adjusting the internal pressures of the first airtight chamber 3 and the second airtight chamber 5 so as to be openable and closable. Hammer shock absorber.