JPH09100988A - Water hammer preventing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water hammer preventing device that can satisfactorily absorb pressure wave generated by water hammering, hardly generating pulsation. SOLUTION: A water hammer preventing device has a cylinder 3 for connecting an opening end part 1 to a pipeline, a piston 4 slidably inserted in the cylinder 3, and a spring body disposed in a space 5 on the opposite side to the opening end part 1 in the cylinder 3 partitioned by the piston 4. In this case, the opening end part 1 is gradually narrowed toward the inside of the cylinder 3 from the pipeline side and sharply enlarged in the cylinder 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water hammer prevention device, and more particularly, it is used by being attached to a pipe to prevent a water hammer by absorbing a rapid pressure change generated in the pipe such as hot water supply and water supply. Water hammer prevention device.

[0002]

2. Description of the Related Art Pipes are laid for hot water supply and water supply in various buildings such as apartment houses, detached houses and hospitals. When a faucet or valve provided in such a pipe is closed, the pressure inside the pipe rises sharply, and this increased pressure becomes a pressure wave that gradually attenuates while reciprocating in the pipe. Is commonly known as. Since such a water hammer causes noise and vibrates the piping equipment, it is not preferable for using the piping equipment.

As a countermeasure against this, various water hammer prevention devices that absorb and mitigate sudden pressure changes are used. For example, a water hammer prevention device as shown in FIG. 9 has been conventionally used.

This water hammer prevention device has a cylinder 3 for connecting the open end 1 to a pipe through a branch pipe or the like, and a piston 4 slidably fitted in the cylinder 3. A space 5 on the side opposite to the open end 1 in the cylinder 3 partitioned by 4 is provided as an air spring.

In this water hammer prevention device, when water is not flowing through the pipe, the piston 4 is located on the side of the opening end 1 at the lowermost end, as shown in (A). At the time of water passage, as shown in (B), the piston 4 is maintained at a position where it is pushed up to some extent by the pressure of water passage. When the pressure in the pipe suddenly rises, (C)
As shown in FIG. 3, the piston 4 is pushed up by this rising pressure, and the air spring sealed in the cylinder 3 by the piston 4 absorbs this rising pressure and prevents generation of a pressure wave.

In such a water hammer prevention device, since the opening end portion 1 is wide and water easily flows in and out, the water hammer prevention device has a particularly high sensitivity to water hammer.

[0007]

However, in the above-mentioned conventional example, although the sensitivity of preventing water hammer is high, the generation of the pressure wave is not always completely prevented, and the pressure wave pulsates to some extent. There is a tendency to be in the prevention state. This is presumed to be due to the repulsive force of the pressure spring acting because the open end 1 communicates widely with the cylinder 3.

Further, as shown in (B) during the passage of water, since the piston 4 has risen to some extent, the pressure absorption capacity is inferior to that in the state of (A).

The present invention has been made to solve the above problems, and an object thereof is to provide a water hammer prevention device capable of absorbing a pressure wave generated by a water hammer with little pulsation. It is in.

[0010]

According to a first aspect of the invention for solving the above-mentioned problems, a cylinder 3 for connecting an open end 1 to a pipe 2 and a piston slidably fitted in the cylinder 3. 4 and a water hammer prevention device having a spring body in a space 5 on the side opposite to the opening end 1 in the cylinder 3 partitioned by the piston 4, the opening end 1 is connected to the pipe 2
It is characterized in that it is narrowed from the side toward the inside of the cylinder 3 for a while and is rapidly expanded inside the cylinder 3. Examples of the spring body referred to here include an air spring and a coil spring.

In such a water hammer prevention device, the water in the pipe 2 smoothly enters the cylinder 3 from the wide opening end 1 on the pipe 2 side due to the rapid pressure increase in the pipe 2, and the piston 4 is moved. It can be pushed up, and the rise in pressure in the pipe 2 can be absorbed by the spring body. Further, the water that has entered the cylinder 3 is pushed back from the abruptly expanded cylinder 3 to the narrow portion of the opening end near the inner side of the cylinder 3 by the spring body, and can exit relatively slowly. . Since the water flows out gently in this way, the pressure of the water that is pushed back makes it difficult to generate pressure in the pipe 2.

A second aspect of the invention is characterized in that, in the first aspect of the invention, a portion of the open end 1 closer to the inside of the cylinder 3 is formed in the pipe line 6.

In such a water hammer prevention device, the opening end 1 is
The narrow portion on the inner side of the cylinder 3 serves as the conduit 6 having a certain length, and the loss resistance when water passes through this portion is particularly large, which makes it difficult for the water to come out of the cylinder 3.

The invention according to claim 3 is characterized in that, in the invention according to claim 2, the pipe line 6 is provided so as to project into the cylinder 3.

In such a water hammer prevention device, the end of the pipe 6 inside the cylinder 3 is opened at a position where the end enters the cylinder 3. Therefore, the water that has entered the cylinder 3 passes from the wide cylinder 3 to the end of the narrow pipe 6 inside the cylinder 3, so that the loss resistance becomes particularly large, and the water does not easily come out of the cylinder 3. Has become.

The invention described in claim 4 is the first to third aspects of the present invention.
In any one of the inventions described above, the valve 7 is provided in the opening end portion 1, and the invention is characterized in that.

In such a water hammer prevention device, the valve 7 can be adjusted to adjust the size of the flow path at the opening end 1 to adjust the ease of water entry and exit.

The invention according to claim 5 has a cylinder 3 for connecting the open end 1 to the pipe 2 via a branch pipe 11, and a piston 4 slidably fitted in the cylinder 3. In the water hammer prevention device having a spring body in a space on the side opposite to the opening end 1 in the cylinder 3 partitioned by the piston 4, a main flow path that matches the flow direction of water in the branch pipe 11. It is characterized in that 13 is formed to be narrower in the direction of water flow for a while, and a branch flow passage 14 is provided to connect the narrowed portion 13a of the main flow passage 13 to the opening end 1 of the cylinder 3. I am configuring.

In such a water hammer prevention device, the main flow path is
In the narrowed portion 13a of 13, the flow velocity of the flowing water becomes faster, and the pressure of the space communicating with the cylinder 3 from the branch flow passage 14 decreases, so that the piston 4 is sucked and drawn toward the open end portion 1 side. Therefore, the spring body behind the piston 4 is maintained on the open side.

The invention of claim 6 is characterized in that the branch flow passage 14 is formed narrower toward the main flow passage 13 for a while.

In such a water hammer prevention device, the branch channel 14
The water flowing through the pipe 2 is less likely to enter from the narrowed portion of the pipe, and the pressure in the space communicating with the cylinder 3 from the branch flow passage 14 is likely to drop.

[0022]

FIG. 1 shows a first embodiment of the present invention.
The following description will be made with reference to FIG.

FIG. 1 is a sectional view showing a water hammer prevention device of this embodiment, and FIG. 2 is a front view showing a state in which the water hammer prevention device is incorporated in a pipe 2. Further, FIG. 3 is a graph showing pressure fluctuations in the pipe 2 when the valve (calant 10) is closed using such a water hammer prevention device.

FIGS. 4 and 5 are similar graphs showing pressure fluctuations in the pipe as a comparative example. FIG. 4 shows the pressure fluctuations in the pipe 2 without the water hammer prevention device. FIG. 5 shows pressure fluctuations when the water hammer prevention device in this embodiment is communicated with the inside of the cylinder 3 with the opening end portion 1 having the opening diameter on the pipe 2 side.

As shown in FIGS. 1 and 2, this water hammer prevention device comprises a cylindrical cylinder 3 having an open end 1 for connecting to a pipe 2 by using a branch pipe 11 or the like. As the branch pipe 11 in this case, a pipe having a constant inner diameter is branched in three directions. A piston 4 is slidably fitted in the cylinder 3, and the opening end 1 in the cylinder 3 is partitioned by the piston 4.
The space 5 on the opposite side is used as an air spring. Further, 12 is a seal member such as an O-ring which is provided around the piston 4 and serves to maintain watertightness. In addition,
The air spring may be replaced with another spring body such as a coil spring.

In such a water hammer preventive device, when the valve 12 is closed and the pressure in the pipe 2 suddenly rises, the water in the pipe 2 passes through the open end 1 and the water in the cylinder 3 flows. The air spring absorbs a sudden pressure increase that causes a water hammer, and works to mitigate it.

In the water hammer prevention device of this embodiment, the opening end 1 is narrowed from the side of the pipe 2 toward the inside of the cylinder 3 for a while, and is rapidly expanded inside the cylinder 3. Since the opening end portion 1 having such a shape is provided, water can smoothly enter the cylinder 3 from the wide opening end portion 1 on the pipe 2 side, and the piston 4 can be pushed up. Therefore, the pressure rise in the pipe 2 is absorbed by the air spring, and the water hammer is prevented with good sensitivity. Also,
The water that has entered the cylinder 3 is pushed back by the spring body from the abruptly expanded inside of the cylinder 3 to the narrow portion of the opening end portion 1 near the inside of the cylinder 3 and can exit relatively slowly. Therefore, it is difficult for pressure to be generated in the pipe 2 due to the pushed back water, and water hammer is prevented without causing pulsation.

The shape of the opening end 1 will be described in more detail below. In other words, in this water hammer prevention device, the opening end 1 is smoothly inclined toward the inside of the cylinder 3, and the portion having the smallest diameter is made relatively long to form the conduit 6 having the smallest diameter. This conduit 6 is provided so as to project into the cylinder 3.

In the opening end 1 having such a shape, the narrow portion near the inner side of the cylinder 3 becomes the conduit 6 having a certain length, and the loss resistance when water passes through this portion becomes particularly large. There is. Further, the end of the pipe 6 inside the cylinder 3 is opened at the position where it enters the cylinder 3, and the water that enters the cylinder 3 is transferred from the wide cylinder 3 to the end of the narrow pipe 6 inside the cylinder 3. Therefore, the loss resistance becomes particularly large, and it is difficult for water to come out of the cylinder 3. Therefore, a rapid pressure increase in the pipe 2 can be smoothly reduced.

FIG. 3 is a graph showing pressure fluctuations in the pipe 2 when the calan 10 which is the valve in the pipe 2 shown in FIG. 2 is closed. In this figure, the vertical axis represents the water pressure in the pipe 2, and the horizontal axis represents the time from the time when the calan 10 is closed. As described above, when the calan 10 is closed, the pressure is once increased, but is temporarily decreased without pulsation, and the pressure is reduced to 0.
After 2 seconds, it has almost returned to the steady state.

Further, the graph of FIG. 4 shows the same pressure fluctuation when the water hammer prevention device is not provided, and the graph of FIG. 5 shows that the opening end 1 has the opening diameter on the side of the pipe 2 and the cylinder 3 has the same opening diameter.
It shows the pressure fluctuation when communicating with the inside.

As shown in these figures, in the case where the water hammer prevention device is not provided, the amplitude of the pressure fluctuation continues almost unchanged from the initial amplitude even after 0.2 seconds. On the other hand, in the case of FIG. 5, when 0.2 seconds has passed, the state is returned to a substantially steady state, but the value of 0.05-
It can be seen that a relatively large amplitude still remains for about 0.1 second and pulsates. That is, such pulsation can be prevented by forming the opening end portion 1 so as to narrow toward the inside of the cylinder 3 for a while as in the present embodiment.

FIG. 6 is a sectional view showing a water hammer prevention device according to the second embodiment. The water hammer prevention device will be described below.

The water hammer prevention device shown in this figure is different from that shown in the first embodiment, in that the valve 7 is provided with a screw capable of advancing and retracting at a portion of the opening end portion 1 near the inside of the cylinder 3. It is what is said.

In such a water hammer prevention device, the valve 7 is adjusted to adjust the size of the flow path in the portion of the opening end 1 near the inside of the cylinder 3 to adjust the ease of water entry and exit. be able to. Therefore, the balance between the workability of the water hammer prevention effect and the work of preventing the occurrence of pulsation can be adjusted according to preference. The portion of the open end 1 near the inner side of the cylinder 3 is a portion that is particularly susceptible to the entry and exit of water, and effective adjustment is possible by providing a simple screw in this portion.

Further, unlike the one shown in FIG. 1, the inner surface of the opening end 1 is formed into a bell-shaped smooth curve narrowly toward the inner side of the cylinder 3 for a while, so that water can be more smoothly supplied. This is an attempt to guide the inside of the cylinder 3.

In addition to the above example, the shape of the inclined surface may be a trumpet type or a stepped shape, that is, the shape is narrowed toward the inside of the cylinder 3. It is all right.

FIG. 7 shows a water hammer prevention device according to the third embodiment, and the water hammer prevention device will be described below. FIG. 8 is a graph showing pressure fluctuations in the pipe 2 when the valve (calan 10) is closed by using the water hammer prevention device according to this embodiment.

As shown in FIG. 7, in this embodiment, unlike the first or second embodiment, the inner diameter of the open end 1 of the cylinder 3 is constant, The branch pipe 11 is characterized by its shape.

That is, the main flow path 13, which is a pipe line that coincides with the flow direction of water in the branch pipe 11, is temporarily narrowed toward the flow direction of water. And this main flow path 13
A branch flow path 14 is provided to connect the narrowed portion 13a of the cylinder 3 to the open end 1 of the cylinder 3. In particular, the branch flow path 14 in this case is opened at the end of the branch pipe 11 on the downstream side of the main flow path 13, and is the narrowest part of the main flow path 13,
This portion is a connection portion with the pipe 2. In addition, the branch flow path 14 extends in the water flow direction of the pipe 2.

In such a water hammer prevention device, the main flow path is
The flow velocity of water flowing through the narrowed portion 13a of 13 becomes faster,
Since the pressure of the space communicating with the cylinder 3 from the branch flow passage 14 is lowered, the piston 4 is sucked and drawn toward the opening end portion 1 side. Therefore, the spring body behind the piston 4 is maintained on the open side. That is, since the pressure absorbing capacity of the spring body is maintained in a high state, the water hammer when the calan 10 is closed while water is flowing in the pipe 2 is well absorbed.

Further, since the branch flow passage 14 is formed narrower toward the main flow passage 13 for a while, the water flowing through the pipe 2 flows backward from the narrowed portion of the branch flow passage 14 and is unlikely to enter. There is. Further, since the branch flow path 14 extends in the flow direction of water, it is also difficult for water to flow backward. That is, when the water is flowing, the water that flows back into the branch flow passage 14 and invades does not adversely affect, and the pressure of the space communicating with the cylinder 3 from the branch flow passage 14 is easily lowered, and the piston 4 is It can be pulled closer to the open end 1 side, and the ability to absorb a water hammer is further improved.

As shown in FIG. 8, according to such a water hammer prevention device, the pulsation is the same as in the case where the pipe line of the branch pipe 11 shown in FIG. 5 has no characteristic. Although it remains to some extent, its amplitude can be reduced. That is, when comparing the first peak pressure after 0.03 seconds, whereas a ² approximately in FIG. 5 7 Kg / cm, in the present embodiment is about 5Kg / cm ^2.

In each of the above-described embodiments, the fluid in the pipe 2 is limited to water, but needless to say, the fluid is not limited to water and may be another type of fluid, and likewise a sudden pressure fluctuation. It is possible to prevent noise and vibration caused by the pressure wave generated by.

[0045]

According to the first aspect of the invention, since the open end of the cylinder is formed wide on the pipe side, the water in the pipe smoothly enters the cylinder. Therefore, a rapid pressure rise in the pipe that causes a water hammer is reliably absorbed and prevented. In addition, the inner edge of the opening is narrower toward the inside of the cylinder, and it is formed by abruptly expanding inside the cylinder. become. Therefore, when the water that has entered the cylinder is pushed back, pressure is less likely to be generated in the pipe, and water hammer can be prevented without causing pulsation.

According to the second aspect of the invention, the loss resistance when the water passes through the narrow portion of the opening end near the inner side of the cylinder becomes particularly large, and it is difficult for the water to come out of the cylinder and pulsation may occur. The sex is very low.

According to the third aspect of the present invention, the end of the pipeline inside the cylinder is opened at the position where it enters the cylinder, and the water entering the cylinder is lost when passing through the end of this pipeline. The resistance is particularly high, the water does not easily come out of the cylinder, and the possibility of pulsation is greatly reduced.

According to the fourth aspect of the present invention, by adjusting the valve, it is possible to adjust the speed at which water enters and leaves the cylinder. Therefore, it is possible to adjust the balance between the ease of working to prevent water hammer and the work to prevent the occurrence of pulsation.

According to the fifth aspect of the invention, since the piston can be pulled toward the opening end side while water is flowing in the pipe, the spring body in the back of the piston is kept open. It has a high water hammer absorption capacity.

According to the sixth aspect of the invention, the water flowing through the pipe is less likely to enter the cylinder side from the narrowed portion of the branch flow passage, and the pressure in the space communicating with the cylinder from the branch flow passage is easily lowered. Therefore, the piston can be pulled closer to the opening end side, and the ability to absorb the water hammer is further improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a water hammer prevention device according to a first embodiment of the present invention.

FIG. 2 is a front view showing a state in which the above water hammer prevention device is provided in a pipe.

FIG. 3 is a graph showing pressure fluctuations in the pipe when the water hammer prevention device of the above is used and the valve is closed.

FIG. 4 is a graph showing, as a comparative example, pressure fluctuations in a pipe without a water hammer prevention device.

FIG. 5 is a graph showing a pressure variation in a pipe provided with a water hammer prevention device as a comparative example as a comparative example.

FIG. 6 is a sectional view showing a water hammer prevention device according to a second embodiment of the present invention.

FIG. 7 is a sectional view showing a water hammer prevention device according to a third embodiment of the present invention.

FIG. 8 is a graph showing pressure fluctuations in the pipe when the water hammer prevention device of the above is used and the valve is closed.

FIG. 9 is a cross-sectional view showing a conventional water hammer prevention device,
(A), (B), and (C) show different states.

[Explanation of symbols]

 1 Open End 2 Piping 3 Cylinder 4 Piston 5 Space 6 Pipeline 7 Valve 10 Karan 11 Branch Pipe 12 Sealing Member 13 Main Flow Path 14 Branch Flow Path

Claims (6)

[Claims] 1. A cylinder having an opening end connected to a pipe, and a piston slidably fitted in the cylinder. The cylinder is partitioned by the piston and is provided on the opposite side of the opening end. A water hammer prevention device comprising a spring body in a space, wherein the opening end is temporarily narrowed from the pipe side toward the inside of the cylinder and is rapidly expanded in the cylinder. 2. The water hammer prevention device according to claim 1, wherein a portion of the opening end portion closer to the inner side of the cylinder is formed in a pipe line. 3. The water hammer prevention device according to claim 2, wherein the pipe line is provided so as to project into the cylinder. 4. The water hammer prevention device according to claim 1, wherein a valve is provided in the opening end portion. 5. A cylinder having an open end connected to a pipe via a branch pipe, and a piston slidably fitted in the cylinder, and the open end in the cylinder partitioned by the piston. In a water hammer prevention device having a spring body in the space on the side opposite to the section, the main flow passage that matches the flow direction of water in the branch pipe is formed to be narrower toward the water flow direction for a while. A water hammer prevention device comprising a branch flow passage that connects a narrowed portion of the flow passage to an opening end of a cylinder. 6. The water hammer prevention device according to claim 5, wherein the branch channel is formed narrower toward the main channel for a while.