JPS62169000A - Muffling device for submersible pump - Google Patents

Abstract

PURPOSE:To reduce pressure vibration and mechanical vibration during operation by making the length of an expansion chamber partly formed with an elastic wall of a rubber etc. 1/4 the pressure pulsation wave length of the fundamental frequency and providing a stay for restricting the length of said elastic wall via a vibration isolating material. CONSTITUTION:A pressure pulsation wave generated from a submersible pump P is shifted by half a wave length from the pressure pulsation ware reflected at the expanded part or contracted part of an expansion chamber V having a length 1/4 of the wave length of the pressure pulsation, thereby causing them to interfere with each other to damp down the pressure pulsation of a fundamental frequency. Also, mechanism vibration from the pump P is insulated by the absorbing effect of the elastic flexible pipe 3 forming the expansion chamber V, without being transmitted to a pipe line. And,since the length of the flexible pipe 3 is restricted by a stay bolt 6 which is provided via a vibration isolating material 7, the elongation of the flexible pipe 3 due to the weight of the pump P or the inner pressure of the pipe line, and the vibration of the submersible pump P, can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Field of Industrial Application The present invention relates to a noise reduction device that reduces pressure pulsations and mechanical vibrations that are the main sources of noise when a submersible pump is operated.

(Prior Art) When a pump is operated, the main sources of noise include pressure pulsations caused by rotation of an impeller and mechanical vibrations caused by mass imbalance.

The above pressure pulsations generated from the pump contain many frequency components, but the fundamental frequency of the pressure pulsations with the greatest energy is calculated using the following formula using the impeller rotation speed and the number of blades. % formula % However, Hz・−・−・−・−Frequency of pressure pulsation N・
−−−−1−−・Rotation speed of impeller (r, p, m) Z
・・・-・-・・・The number of blades in a pump usually has a rotation speed of 1500 to 200 Or,
Since the number of p, m and blades is 4 to 6, the fundamental frequency of pressure pulsation is approximately 100 to 200 Hz.

Conventionally, as shown in Fig. 6, there is a noise reduction device consisting of an iron expansion chamber A (the length of this expansion chamber is designed to be 2 times the pressure pulsation wavelength of the fundamental frequency).
(See Publication No. 0 (Figure 1)). However, in the above-mentioned silencer, although the expansion chamber A can reduce the pressure pulsation at the fundamental frequency,
Mechanical vibrations were transmitted to the fully flexed expansion chamber and could not be absorbed.

Furthermore, as shown in Fig. 7, a noise muffling device using a rubber expansion chamber has been devised (see Utility Model Publication No. 56-50090 (Fig. 2)). There are problems such as the expansion chamber being stretched due to fluctuations in weight and internal pressure when suspended, and the vibration of the submersible pump increasing.Also, the resonance frequency of the elastic body is a low frequency of several to several + H2. Therefore, it is effective in insulating mechanical vibrations, and the resonance frequency of the elastic body (several H2
~ several tens of H), the conversion from pressure pulsation energy to deformation energy of the elastic body is greatest, so there is a reduction effect, but it is not expected to have much of a reduction effect on the pressure pulsation frequency of the above-mentioned normal pump. Ta.

(Problems to be Solved by the Invention) In view of the above-mentioned drawbacks of the prior art, the present invention can reduce both pressure pulsation and mechanical vibration, which are the main causes of noise in submersible pumps. The purpose of the present invention is to provide a silencer for a submersible pump that can prevent extension of the pump and rocking of the pump.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention forms a part of the expansion chamber with an elastic wall made of rubber or the like in a silencer for a submersible pump, and the length of the expansion chamber is set as the basic length. It is characterized in that the frequency is set to 2 of the pressure pulsation wavelength, and a stay that regulates the length of the elastic wall is provided via a vibration isolating material.

(Function) Since the length of the expansion chamber is set to two times the pressure pulsation wavelength of the fundamental frequency, the pressure pulsations transmitted through the discharge pipe and the pressure pulsations reflected at the expanding or contracting portions are shifted by half a wavelength and interfere with each other. Fundamental frequency pressure pulsations are reduced. Furthermore, due to the vibration-absorbing effect of the elastic wall that forms part of the expansion chamber, mechanical vibrations from the pump are insulated and are not transmitted to the piping. Furthermore, since the length of the elastic wall is regulated by the stay via the vibration isolating material, elongation of the elastic wall and rocking of the pump due to pump weight and internal pressure are prevented.

(Example) Examples of the present invention will be described below with reference to FIGS. 1 to 3.

FIG. 1 is a longitudinal cross-sectional view of the vibration isolator 1. 2 is an upper joint pipe having an outlet flange 2a at the upper end and an enlarged flange 2b at the lower end, and has the same diameter as the inner diameter of the pipe. The upper end of a bellows-shaped flexible tube 3 made of an elastic material such as rubber and having an inner diameter larger than the pipe inner diameter D1 is fixed to the lower surface by an annular fixing plate 4. 5 has an inlet flange 5a at the lower end
and an enlarged flange 5b at the upper end, and an inner diameter D at the upper end.
The lower end of the flexible tube 3 is fixed to the upper surface of the enlarged flange 5b by an annular fixing plate 4''. .

The expansion chamber (2) is formed by the elastic flexibility 'ff3 and the enlarged portion of the lower joint tube 5, and its length is designed to be equal to 2 of the wavelength λ of the pressure pulsation at the fundamental frequency. Incidentally, the elastic flexible tube may be arranged in the middle of the long expansion chamber (2). Reference numeral 6 denotes a stay port, which is inserted into a plurality of holes drilled at the peripheral edge of the enlarged flange 2b of the upper joint pipe 2 through a vibration isolating material 7 such as rubber, and its lower end is inserted into the enlarged flange 5b of the lower joint pipe 5. After inserting it into the hole, tighten it with nut 8.

The vibration isolator l constructed as described above is disposed in the pipe line T of the submersible pump P, as shown in FIG.

Since the present embodiment is as described above, the pressure pulsating waves generated from the submersible pump P and the pressure pulsating waves reflected at the expanding or contracting portion of the expansion chamber V having a length of two times the wavelength of the pressure pulsating By shifting by half a wavelength, they interfere with each other and the pressure pulsations at the fundamental frequency are reduced. Furthermore, mechanical vibrations from the submersible pump P are insulated and are not transmitted to the pipeline due to the absorption effect of the elastic flexible tube 3 forming the expansion chamber V.

Furthermore, since the length of the flexible tube 3 is regulated by the stay bolt 6 provided with the vibration isolating rubber 7 interposed, the submersible pump P
Stretching of the flexible pipe 3 and rocking of the submersible pump P due to the weight of the pipe and the internal pressure of the pipe can be prevented.

Fig. 3 shows another embodiment of the present invention, which is similar to Fig. 1 except that a portion 5'C of the same diameter as the conduit of the lower joint pipe 5'' is inserted into the expansion chamber v by L/2. There is no difference from the embodiment.

According to this embodiment, the attenuation characteristic (
As shown in FIG. 4, there is a frequency with an attenuation amount O), which is improved as shown by the solid line in FIG.

(Effects of the Invention) As can be seen from the above explanation, the length of the expansion chamber of the present invention is designed to be equal to the wavelength A of the pressure pulsation of the fundamental frequency. The pressure pulsation waves reflected at the expanding or contracting portion of the pump are shifted by half a wavelength, so that they interfere with each other, and the fundamental frequency pressure pulsation from the pump is reduced.

Furthermore, mechanical vibrations are reduced due to the absorption effect of the elastic flexible tube forming the expansion chamber.

Therefore, it is extremely unlikely that the vibrations caused by these things will be propagated to the floor, walls, and ceiling and cause noise.

In addition, the length of the elastic wall that forms part of the expansion chamber is regulated by a stay via vibration isolating material, so the elastic wall does not stretch due to the weight or hydraulic pressure of the submersible pump, and the expansion chamber becomes noiseless. It can maintain its function for a long time, and also prevents the submersible pump from shaking and causing damage to the pipes and joints.

[Brief explanation of drawings]

, Fig. 1 to Fig. 5 are drawings according to an embodiment of the present invention, in which Fig. 1 is a longitudinal cross-sectional view of a muffler, and Fig. 2 is a view of the muffler installed in the discharge pipe of a submersible pump. A schematic diagram showing the
FIG. 3 is a longitudinal cross-sectional view of a silencer according to another embodiment, FIG. 4 is a diagram showing the attenuation characteristics of the silencer of FIG. 1, and FIG. 5 is a diagram showing the attenuation characteristics of the silencer of FIG. 3. The drawings, FIGS. 6 and 7, are all vertical sectional views of a conventional silencer. l...--Sound damping device, 3-----------Elastic wall, 6---Stay, 7---Vibration isolating material, P---- −1・−1−− Submersible pump, T−・−−
---One discharge pipe, ■--...--Expansion chamber.

Claims (1)

[Claims] In a silencer having an expansion chamber disposed in the discharge pipe of a submersible pump, a part of the expansion chamber is formed of an elastic wall made of rubber or the like, and the length of the expansion chamber is determined by pressure pulsations at the fundamental frequency. A sound muffling device characterized in that a stay that regulates the length of the elastic wall to 1/4 of the wavelength is provided via a vibration isolating material.