JPH0372877B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a pressure pulsation reducing device for piping that handles liquid. [Prior art] Generally, based on the drive of fluid machines such as pumps,
When the generated pressure pulsations are transmitted to the piping system, it causes the piping system to vibrate and radiate noise. For example, in pump equipment, when the impeller blades pass through the discharge volute inlet, a pressure change occurs, that is, a pulsation of the number of blades x rotation speed occurs, and this pulsation propagates through the water column in the piping, and the piping system It makes the whole thing vibrate and makes noise. To deal with the occurrence of pulsation as mentioned above,
Previously, Utility Model Application No. 57-181993 and Utility Model Application No. 55-39382
Various pressure pulsation reducing means are used, such as those described in Japanese Patent Laid-Open No. 51-51006. [Problems to be Solved by the Invention] None of the above-mentioned conventional pressure pulsation reduction devices could cope with a case where the frequency of pressure pulsation changes, and could not obtain a pressure pulsation reduction effect over a wide range. In addition, in a device that attempts to absorb pulsations by elastic deformation of an elastic body or air, such as the one described in JP-A No. 51-51006, a large chamber must be provided to absorb the pulsations. The durability of the elastic body was poor, and the pressure pulsation reduction effect fluctuated due to changes in the amount of air trapped in the pulsation absorption chamber and aging of the elastic body. The purpose of the present invention is to provide a pressure pulsation reduction effect that can be achieved over a wide range of liquid piping channels where the pressure pulsation frequency changes, is compact, has a large pressure pulsation reduction effect, and is highly durable. The object of the present invention is to obtain a pressure pulsation reducing device with less variation in effectiveness. [Means for Solving the Problems] In order to achieve the above object, the present invention includes a liquid pipe and a tapered portion connected to the pipe flow path of the liquid pipe and having a length equal to or greater than the wall thickness of the pipe. a passage, a highly rigid resonance chamber connected to the passage, having a larger space than the passage and filled with the same liquid as the liquid in the liquid piping, and having a tapered surface that matches the tapered portion of the passage; and a stem movable in the axial direction of the passage, and by moving the stem in the axial direction, the cross-sectional area and length of the aperture formed by the tapered part of the passage and the tapered surface of the stem are simultaneously changed. The present invention is characterized in that the resonant frequency of the resonant chamber is configured to be variable. [Operation] By having the present invention configured as described above, the resonance chamber resonates with respect to the pressure pulsations propagating within the liquid piping, and the pressure pulsations within the piping can be reduced. In addition, the resonant frequency fres of the resonant chamber is required. Here, α is the propagation velocity of the pressure wave, V is the volume of the resonant chamber, and G is a value determined by the shape, size, etc. of the connecting passage to the resonant chamber, and is called conductivity. In the present invention, the passage has a tapered part having a length equal to or longer than the wall thickness of the liquid pipe, has a tapered surface that matches the tapered part of the passage, and is movable in the axial direction of the passage. and a stem, and by moving the stem in the axial direction, the cross-sectional area and length of the aperture formed by the tapered portion of the passage and the tapered surface of the stem are simultaneously changed, thereby satisfying the equation (1). ) The resonant frequency of the resonant chamber can be varied over a wide range by changing the value of the conductivity G. Therefore, the effect of reducing pressure pulsation can be obtained over a wide range even in liquid piping channels where the pressure pulsation frequency changes. In particular, the present invention includes a highly rigid resonance chamber that has a wider space than the passageway and is filled with the same liquid as the liquid in the liquid pipe, so that the resonance chamber can withstand pressure pulsations propagating in the liquid pipe. Because it resonates, the pressure fluctuations of the liquid confined in the highly rigid resonance chamber become extremely large due to resonance.This reduces the pressure fluctuations in the piping, so the resonance chamber can be made more compact. Even with this configuration, a large pressure pulsation reduction effect can be obtained. Furthermore, since the present invention does not elastically absorb pressure pulsations in the piping with an elastic body or air, it has excellent durability, and also prevents pressure pulsations caused by deterioration of the elastic body or changes in the amount of air, etc. There is also almost no change in the reduction effect. [Example] Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of a variable resonance frequency type pressure pulsation reducing device for liquid piping according to the present invention, and FIG. 2 is a view taken along the line A--A in FIG. 1. A resonance chamber 2 is formed by the liquid pipe 1, the outer tube 3, and the partition plate 10. Further, 4 is a passage connected to the pipe flow path of the liquid pipe 1 and has a tapered part with a length equal to or longer than the wall thickness of the pipe 1, and 5 is a passage having a tapered surface that matches the taper part of the passage 4. The stem is movable in the axial direction of 4. The resonance chamber 2 is connected to the piping channel by a passage 4, and is formed in a space wider than the passage 4. Further, the resonance chamber 2 is made of the same rigid material as the pipe 1, and is filled with the same liquid as the liquid inside the pipe 1. In this embodiment, an air vent valve 12 is used to fill the resonance chamber 2 with liquid.
By removing the air from the resonance chamber 2 through the air vent valve 12, the resonance chamber 2 can be completely filled with liquid. In addition, 6 is a stem case, 7 is a shaft sealing mechanism, 8 is an indicator attached to the stem 5, 9 is an indicator scale ring, 11 is a handle for rotating the stem 5, and 13 is a drain plug. In the present invention, by moving the stem 5 in the axial direction,
The cross-sectional area and length of the aperture formed by the tapered portion of the passage 4 and the tapered surface of the stem 5 can be changed at the same time, and the resonance frequency fres within the resonance chamber 2 can be varied over a wide range. In other words, as mentioned above, the resonant frequency fres is

〔Effect of the invention〕

According to the present invention, it is possible to obtain a pressure pulsation reduction effect over a wide range of liquid piping channels in which the pressure pulsation frequency changes, and moreover, the pressure fluctuations in the resonance chamber are larger than the pressure fluctuations in the piping channels. Because it reduces pulsation in the piping flow path, it is compact and has a large pressure pulsation reduction effect, and it is used by filling a highly rigid resonance chamber with liquid.
It has excellent durability and no fluctuation in pressure pulsation reduction effect.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of a resonant frequency variable type pressure pulsation reduction device for liquid piping, Fig. 2 is a view taken along arrow A-A in Fig. 1, and Figs. 3 and 4 are views of the connection passage to the resonance chamber. FIG. 5, which is an explanatory diagram of conductivity change, is a longitudinal sectional view of another embodiment of the present invention. 1...Liquid piping, 2...Resonance chamber, 3...Outer tube, 4...
Passage, 4'... Resonance chamber passage pipe, 5... Stem, 6... Stem case, 7... Shaft sealing mechanism, 8... Indicator, 9... Indicator scale, 10... Partition plate, 1
1...Handle, 12...Air vent valve, 13...Drain plug, 14...Drain valve.

Claims (1)

[Scope of Claims] 1. A liquid pipe, a passage connected to the pipe flow path of the liquid pipe and having a tapered portion with a length equal to or longer than the wall thickness of the pipe, and a space connected to the passage and wider than the passage. and a highly rigid resonance chamber filled with the same liquid as the liquid in the liquid pipe, and a stem movable in the axial direction of the passage, having a tapered surface that matches the tapered part of the passage. The resonant frequency of the resonant chamber can be varied by simultaneously changing the cross-sectional area and length of the aperture formed by the tapered portion of the passage and the tapered surface of the stem by moving the stem in the axial direction. A pressure pulsation reducing device characterized by: 2. The stem extends outside through the resonance chamber, and the stem of the penetrating portion and the wall of the resonance chamber are screwed together to enable axial movement. Pressure pulsation reduction device as described. 3. The pressure pulsation device according to claim 2, wherein a handle is provided at an end of the stem extending outside the resonance chamber to move the stem in the axial direction. 4. The pressure pulsation reducing device according to claim 3, wherein an indicator is attached to the stem to indicate the value of the resonance frequency based on the amount of axial movement of the stem.