JP3506748B2 - Variable volume silencer for liquid - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable volume silencer for liquids, and more particularly to a resonance type variable volume silencer having a neck and an expanded volume. Specifically, the silencer targeted by the present invention is an operating device, in which a target medium is a liquid, and which is provided around a conduit for the liquid,
For example, it is a silencer for obtaining a suitable result by being used to reduce pressure pulsation generated in a pipe by a hydraulic pump or a water pump, that is, vibration in liquid.

[0002]

2. Description of the Related Art A silencer of a resonance type having a variable volume,
In addition, research has been conducted on the target medium that is a gas and has already been implemented as a practical device.

For example, a volume variable resonance type gas silencer used to reduce pressure pulsations (in-air vibrations) generated in a pipe due to a blower, a fan or the like is
The Acoustical Society of Japan, Vol. 46, No. 6 (1990), p. 479-
P. 485.

FIG. 8 is an apparatus diagram used by the applicants of the present patent application to confirm the effect of a volume silencer for gas of variable resonance type. In the figure, a pressure pulsation generated from a sound source b on the upstream side a passes through the main pipe c and flows to the downstream side d, and a neck portion e is provided between the upstream measurement portion P ₁ and the downstream measurement portion P _2.
By attaching one end of the cavity, attaching the cavity f to the other end of the neck e, loading the piston g into the cavity f, and moving the piston g using the moving means h provided outside.
It is configured so that the volume of the cavity f can be changed. The pressure pulsation of the sound source b is detected by the detection means i, which is input as frequency information to the personal computer j, and the drive command obtained by processing is transferred from the DC servo motor m to the movement means h via the servo amplifier k.
And the piston g is moved to an appropriate position to obtain a sound deadening effect. According to this device, when the medium is a gas, as shown in FIG. 9, it is shown that the sound deadening effect can be obtained with a volume suitable for the frequency. That is, when the frequency is 40 Hz, the sound reduction volume decreases to -40 dB near the piston stroke 440 mm, and when the frequency is 120 Hz, the sound reduction volume extremely decreases to -32 dB near the piston stroke 40 mm. It is recognized that

As another example of the prior art, Japanese Patent Publication No.
-7553 is available. This also relates to a resonance type silencer having a variable volume, and uses the target medium as a gas as in the above case. In this prior art, the frequency of the maximum sound pressure is detected, the resonance frequency is calculated by using the control unit, and the actuator is operated to control the volume of the resonator to a volume in which resonance that matches the frequency is performed. A configuration of such an automatic control method is disclosed.

As described above, a plurality of documents have already been published for the case where the target medium is a gas. However, when the medium is a liquid, the case of applying the resonance silencer is as follows. It is difficult to find in the prior art.

[0007]

As described above, even in the resonance type silencer which can obtain a sufficient silencing effect when the medium is a gas, when the medium is a liquid, the effect cannot be obtained as expected. . For example, when the volume of the resonance type silencer having the configuration shown in FIG. 8 is changed from a gas to a liquid, the spectral state of the sound pressure is changed even if the volume is changed, as shown in FIGS. It hasn't changed much. Figure 1
0 is a record of the increase and decrease of the sound pressure level with respect to the frequency (Hz) over the entire range from 0 to 1000, but the sound pressure at the resonance point, which should be conspicuous only at a specific frequency, is recorded. No reduction in level (so-called depression) is recognized. In addition, in FIG. 11, the volume corresponding to the same silencer is changed (increase by 100 mm in the figure) to find the location corresponding to the calculated target frequency (about 410 Hz) on the graph, and the state of the sound pressure level at that location. Is shown together with the relationship with the whole. As is clear from the figure, in this case as well, there seems to be no apparent drop in sound pressure level.

As described above, it is impossible to apply the equation relating to the sound pressure established when the medium is gas as it is to the case where the medium is water. The reason for this is that when the medium is changed from gas to liquid, the specific acoustic resistance is about 3,500 times that of air to 4,
This is because it becomes 000 times, and as a result, it is greatly affected by the rigidity of the end surface and wall surface of the resonance silencer.

When the target medium is a liquid, the progress of the calculation performed about how much the rigidity of the end surface or wall surface of the silencer should be increased in order to use the resonance type silencer and to exert a sufficient silencing effect. The main points of are shown below.

Now, it is assumed that the wall surface having the area S is held with the rigidity k.

When the internal pressure p ₀ acts on this wall surface, the force F applied to all the wall surfaces becomes F = p ₀ S and the wall surface displacement χ becomes χ = F / k = p ₀ S / k.

Assuming that the fluctuating frequency of the internal pressure is f, the fluctuating velocity ν of the wall surface is ν = 2πfχ = 2πfp ₀ S / k.

As a result, the sound pressure P radiated from the wall surface is given by P = σρсν = σρс2πfp ₀ S / k, and the pressure ratio << τ = P / p ₀ >> is obtained by the following equation.

Τ = P / p ₀ = σρс2πfS / k where σ is the acoustic conversion coefficient, ρ is the fluid density, and с is the speed of sound.

Here, σ = 1.0 and ρ = 10 ³ kg /
m ³ , с = 1.5 × 10 ³ m / sec, f = 500 Hz,
Substituting S = π / 4 · 0.2 ² (= 3.14 × 10 ⁻² m ² ) into the above equation, the pressure ratio τ is τ = 1.0 · 10 ³ × 1.5 × 10 ³ × 2π · 5 × 10 ² × 3.14 × 10 ⁻² / k = 1.48 × 10 ⁸ / k.

Assuming that the upper limit of the required pressure ratio τ is 0.1, the value of the rigidity k required to satisfy << τ <0.1 >> is k> 1.48 × 10 ⁹ N / M (= 1.51 × 10 ⁸ kgf / m) (= 1.51 × 10 ⁶ kgf / cm) Further, as a preferable reference value of the pressure ratio τ, << τ <0.0
5 >> is applied, the required stiffness k must be a value satisfying k> 2.96 × 10 ⁹ N / m. To this end, the so-called acoustic influence (pressure ratio τ) is kept as small as possible to enhance the rigidity of the silencer as a whole, and as a result, the resonance effect of the resonance silencer with the liquid as the target medium is significantly demonstrated. It is necessary to let

The present invention has been made in view of the current state of the art as described above. For a resonance type silencer having a variable volume, the rigidity of the end face and the wall surface, and the rigidity of the entire silencer are compared with those of the silencer. The volume for liquids that can significantly increase the volume before and after the volume change in any case, thereby significantly increasing the silencing effect of the resonance silencer for liquids. The purpose is to realize a variable silencer.

Another object of the present invention is to add a simple structure so that the moving operation of the movable part for volume fluctuation of the silencer can be sufficiently performed even when the target medium has a high pressure. This is to further promote work efficiency.

[0019]

As a means for solving the above-mentioned problems, in a variable volume silencer for liquid of the present invention, a cylindrical neck having one end connected to a structure to be silenced, and a neck In a muffler for liquid consisting of an expansion volume connected to the other end of the section, the expansion volume is composed of a combination of two cylinders, and one cylinder is fixed to the other end of the neck as a fixed cylinder. , The other cylinder is used as a movable cylinder and is configured to be movable using the peripheral surface of the fixed cylinder as a guide, and the movable cylinder has means for supplying power for the movement, and the movement is performed as necessary. comprising a clamping device which can stop firmly on the peripheral surface of the movable cylinder, it said in the expansion volume
Conducting working fluid to assist the movement of the movable cylinder
Provide a balance pressure receiving surface on the outer peripheral part of the expansion volume.
There is .

As described in claim 2, a silencer for liquid, comprising: a cylindrical neck portion having one end connected to the sound deadening target structure; and an expansion volume portion connected to the other end of the neck portion. The part is composed of one piston and a cylinder that is capable of relative movement with respect to the piston, and is fixed to the other end of the neck by using one of the piston and the cylinder as a fixed part. However, the other part is configured as a movable part and is configured to be capable of relative movement using the inner peripheral surface or the outer peripheral surface of the fixed part as a guide, and the movable part includes means for supplying power for the movement, and the movement is performed. A clamp device that can be firmly stopped as needed is provided on the peripheral surface of the movable part, and the movable seal in the expanded volume part is provided .
A bulk that conducts the working fluid to assist the movement of the Linda.
The Nsu pressure-receiving surface may be configured to Ru formed on the outer peripheral portion of the expansion volume.

According to a third aspect of the present invention, there is provided a liquid muffler having a cylindrical neck portion having one end connected to the sound deadening target structure and an expansion volume portion connected to the other end of the neck portion, wherein The total length of the neck of the subject is divided into two parts, one of which is attached to the structure to be silenced and the other is attached to the expanded volume part so that the free ends of both necks are in a relational position facing each other. One neck attached to the body is configured to allow the other neck attached to the inflation volume to move with the inflation volume, and the two necks are in and out of each other during the movement. The inner and outer diameters of both necks are set so that the mating state can be maintained in a continuous manner, and the expansion volume has means for supplying power for the above movement, and the movement is strong as necessary. The clamp device that can be stopped at Provided on the peripheral surface of the product unit, the expansion volume
To assist the movement of the movable cylinder in the stacking section
The pressure receiving surface for balance that conducts working fluid is the expansion volume
It may be configured to be provided on the outer peripheral portion of the .

[0022]

[0023]

In order to muffle sound in the structure to be silenced, for example, in the water conduit, by the silencer having the structure of claim 1, one end of the neck is connected to the water conduit and the other end of the neck is expanded. The fixed cylinder of the volume portion is fixed, and the movable cylinder is moved by the power of the moving power supply means using the peripheral surface of the fixed cylinder as a guide. The amount of movement is the amount necessary to achieve a volume that matches the frequency of pressure pulsations occurring in the conduit. As the power supply means, for example, a moving method using a ball screw via a servo motor is used.

When the movement is completed, the movable cylinder is firmly tightened and stopped by the clamp device provided on the peripheral surface of the movable cylinder at that position. Since the muffler of the present invention is a liquid muffler, it is natural that a structure for increasing the rigidity of the muffler itself is required, and therefore, the wall thickness of the end surface and wall surface of the muffler body is possible. As long as thick material is used. The high rigidity of the silencer body obtained in this way and the clamping device with a strong stopping force make it possible to increase the rigidity of the silencer as a whole, thereby making the silencer effect of the resonance silencer remarkable. Can be increased to

[0025] In addition, the variation provided on the outer peripheral portion of the expansion volume
Flow the working fluid to the pressure receiving surface for
Movement to help reduce the volume of the silencer.
Operation of the movable cylinder when the target medium is high pressure.
Can be fully addressed, thereby improving work efficiency.
The layers are promoted.

According to the silencer of claim 2, the silencer
Expansion volume associated with a single piston
It consists of one cylinder and one of them,
For example, the piston is the fixed part and the other cylinder is the movable part.
Move the cylinder using the outer peripheral surface of the piston as a guide.
If you do so, the procedure for movement or the cylinder
The lamp procedure is the same as in the case of claim 1.
On the contrary, the cylinder is used as a fixed part and
As the movable part and the inner peripheral surface of the cylinder as a guide.
Even if you move tons, there is a point of movement
The method for clamping the piston or the piston is also claim 1.
And the same procedure.

According to the silencer of claim 3, the silencer pair
Divide the neck that connects the elephant structure and the expanded volume into two parts.
Attach each to the structure to be silenced and the expansion volume, and
Each end is facing each other and fits into each other
Are combined with. That is, increase or decrease in the volume of the silencer
In the above-mentioned claim 1, the location where
By the relative movement of the two cylinders that make up and
In contrast to this, the muffler of claim 3 has two necks.
It is performed by relative movement in the fitting / removing direction. Remove this difference
The procedure for moving the expansion volume or the
The pump procedure is the same as in claim 1.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a variable volume silencer of the present invention will be described with reference to the drawings. The embodiment of FIG. 1 corresponds to claim 1, and the muffler of the present embodiment includes a cylindrical neck portion 1 and an expansion volume portion 2 connected to the neck portion 1, and has one end of the neck portion 1. Is connected to the main pipe A as the structure to be silenced. The expansion volume section 2 is composed of two cylinders combined in an internal and external relationship, one cylinder of which is a fixed cylinder 3
Is fixed to the other end of the neck portion 1, the other cylinder is used as the movable cylinder 4, and the outer peripheral surface of the fixed cylinder 3 is used as a guide for movement. As a result, the volume of the cavity 5 involved in resonance can be changed by the movement of the movable cylinder 4. The movable cylinder 4 is provided with a ball screw rod 6, a nut 7, a reduction gear 8, a servomotor 9, and the like as a means for supplying the moving power.

Reference numeral 10 denotes a clamp device provided on the peripheral surface of the movable cylinder 4, which is usually formed as a ring body of two split parts, and the movable cylinder 4 is moved by externally tightening the peripheral surface of the movable cylinder 4. It is for tightly tightening and stopping as needed. Two different embodiments of the clamping device 10 are shown in FIGS. 5 and 6. In FIG. 5, the upper metal piece 11 has a receiving plate 12, the lower metal piece 13 has a ceiling plate 14, and a taper pin 15 is inserted in a space therebetween. A spring 16 is fitted on the lower surface of the receiving plate 12, and when the taper pin 15 is pulled out, the receiving plate 12 is made to closely adhere to the lower surface of the taper pin 15 so that the receiving plate 1
The upper metal part 11 is lifted together with 2, and the tightening is released. Oil chambers 17 and 18 are provided at both ends of the taper pin 15, and the tapping pin 15 is inserted and removed by letting pressurized oil into and out of the oil chambers 17 and 18 through a hydraulic hose. The medium for inserting / removing the taper pin 15 is not limited to hydraulic pressure. Needless to say, it may be one using air pressure or spring force.

Further, in the case of FIG. 6, the fastening metal fitting 19 is locked on the side surface of the lower metal fitting 13 by the wedge 20, and the lower liner 21 fitted on the upper surface of the lower metal fitting 13 and the fastening metal fitting 1 are attached.
An oil chamber 23 provided on the back surface of each liner by sandwiching the upper metal part 11 with the upper liner 22 fitted in the inner surface of
Tightening the upper metal part 11 toward the lower metal part 13 by letting pressure oil in and out through 24 through a hydraulic hose,
Or release. Also in this case, as in the case of the embodiment of FIG. 5, the medium for operation is not limited to hydraulic pressure, and of course pneumatic pressure or spring force can be used.

The expansion volume portion 2 of FIG. 1 is provided with a balance cylinder 25 on its outer peripheral portion, and when the movable cylinder 4 moves using the outer peripheral surface of the fixed cylinder 3 as a guide, a flange formed on the end portion of the movable cylinder 4. The peripheral surface of 26 slides while maintaining a liquid-tight state with the inner peripheral surface of the balance cylinder 25, and the outer peripheral surface of the movable cylinder 4 is liquid-tight with the end plate 27 of the balance cylinder 25. It is configured to be able to slide while maintaining the state of. Based on this configuration,
When the hydraulic pressure in the main pipe A is introduced by the pipe 28 into the balance chamber 29 formed between the flange 26 and the end plate 27, the side of the flange 26 facing the balance chamber 29 becomes the balance pressure receiving surface 30. , The force in the movable direction acting on the movable cylinder 4 is balanced and reduced,
Can be assisted in the movement, especially when the hydraulic pressure is high.

Next, the operation of detecting the sound pressure generated by the structure to be silenced by the liquid silencer and silencing the sound of the detected frequency by the resonance means will be described. The means for realizing the volume of the cavity obtained from the frequency information on the expansion volume is not limited to the means described below. For example, a conventionally known control unit shown in FIG. 8 is used. It is convenient to follow the method. Using this method, for example, when the servo motor 9 shown in FIG. 1 is driven and the ball screw rod 6 is rotated through the reduction gear 8, the movable cylinder 4 together with the nut 7 uses the outer peripheral surface of the fixed cylinder 3 as a guide to form a hollow portion. The volume within 5 moves to a position corresponding to a predetermined cavity volume, and as a result, a state in which resonance can occur is realized.

The embodiment of FIG. 2 corresponds to claim 2. In this muffler, the expansion volume portion 33 of the muffler is moved relative to one fixed cylinder 31 and the inner peripheral surface of the fixed cylinder 31 as a guide. One movable piston 3 that can be combined
2 and. The fixed cylinder 31 is the neck 1.
Is fixed to the other end of. As a result, the volume of the hollow portion 5 involved in resonance can be changed by the movement of the movable piston 32. The structure in which the movable piston 32 is provided with a ball screw rod 6, a nut 7, a reduction gear 8, a servomotor 9, etc. as a means for supplying power for movement is the same as the structure in the movable cylinder 4 of the embodiment of FIG. is there. Further, the point that the clamp device 10 for stopping the movable piston 32 is provided is the same as that of the embodiment of FIG.

The embodiment of FIG. 3 corresponds to claim 2 as in the case of FIG. 2, but differs from that of FIG. 2 in that the piston is fixed and the cylinder is movable. That is the point. That is, in the muffler of this example, the expansion volume 36
However, it is constituted by one fixed piston 34 and one movable cylinder 35 which is combined so as to be capable of relative movement using the outer peripheral surface of the fixed piston 34 as a guide. The fixed piston 34 is fixed to the other end of the neck 1. This allows
The volume of the cavity 5 involved in resonance can be changed by the movement of the movable cylinder 35. The movable cylinder 35 includes a reduction gear 8 that is rotationally driven by a motor or the like, and a rack 39 that is fixed to the outer peripheral surface of the movable cylinder 35 and meshes with the reduction gear 8, as a means for supplying power for movement.
A clamp device 10 for stopping the movable cylinder 35 is provided on the peripheral surface of the movable cylinder 35. A lid plate 37 having a hole that penetrates the center of the movable cylinder 35 by the neck 1 and allows the neck 1 to slide in a liquid-tight manner is provided. The cover plate 37 closes the open end surface, and a balance chamber 29 is formed between the cover plate 37 and the back surface of the fixed piston 34. The hole 38 is for communicating the hydraulic pressure on the main pipe A side into the balance chamber 29, and is formed near the other end of the neck 1.

The embodiment of FIG. 4 corresponds to the constitution of claim 3, and the characteristic feature of the muffler of this embodiment is that the expansion volume is constituted only by the movable cylinder 4, and therefore the content of the cavity 5 is The product is constant, and the neck 1 is divided into two parts and the total length L is made variable. As shown in the figure, the entire length of the neck portion 1 is divided into two parts, that is, a neck portion 1a and a neck portion 1b. Attached to the main pipe A,
The other is attached to the movable cylinder 4, and the movable cylinder 4 is moved via the moving means while maintaining the liquid-tight state of the joint between the two. By moving the entire length L of the neck 1 to a predetermined length, a state in which the sound can be silenced by resonating with the sound pressure level of the main pipe A is realized. Other configurations, that is, a structure for supplying the moving power of the movable cylinder 4 and the clamp device 10 for stopping the movable cylinder 4, and the hydraulic pressure in the main pipe A are introduced into the balance chamber 29 by the pipe 28. The point that the balance pressure receiving surface 30 for balancing the hydraulic pressure inside the cavity 5 is provided is the same as that of the embodiment of FIG.

FIG. 7 is a graph showing the silencing effect of the liquid resonance type silencer of the present invention. The graph A in the figure shows the sound pressure state when the liquid resonance type silencer is installed, and the graph B shows the sound pressure state when no silencer is installed at frequencies (Hz) of 0 to 1000, respectively. It was recorded about the variation of sound pressure level over the whole area, and the power of the sound source (vibrator) in this case was recorded under the same condition both with and without the silencer. It is a thing. The position of 325 Hz in the figure is the position where the drop in the sound pressure level of graph A shows the maximum value, and the frequency at this position is almost the same as the frequency range calculated based on the calculation when the silencer is designed. ing. From this figure, the insertion loss due to the installation of the silencer is about 38 dB.
It is shown that a large sound deadening effect as expected can be obtained, compared with the fact that the conventional sound deadening effect for gas was not applied at all when it was diverted for liquid. There is.

[0037]

Since the variable volume silencer for liquid of the present invention is constructed as described above, the following effects can be obtained.

(1) According to the structure of claim 1, the rigidity of the end surface and the wall surface of the movable cylinder forming the expansion volume part and the rigidity of the silencer as a whole are measured before and after the volume change of the silencer. Can be significantly increased,
As a result, the silencing effect of the silencer using the target medium as a liquid can be significantly enhanced.

(2) In the structure of claim 2, the rigidity of the end surface and the wall surface of the movable piston or the movable cylinder forming the expansion volume portion and the rigidity of the silencer as a whole are determined before and after the volume change of the silencer. Since it is possible to greatly increase in the state, it is possible to remarkably enhance the silencing effect of the silencer in which the target medium is a liquid.

(3) According to the third aspect of the invention, the rigidity of the end surface and the wall surface of the movable cylinder forming the expansion volume portion and the rigidity of the silencer as a whole are significantly increased before and after the volume change of the silencer. It is possible to significantly increase the silencing effect of the silencer in which the target medium is a liquid.

(4) In each of the above-mentioned configurations 1 to 3, by adding a simple configuration, the moving operation of the movable cylinder for changing the volume of the silencer can be sufficiently performed even when the target medium has a high pressure. It is possible to further improve the work efficiency.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of a silencer of the present invention.

FIG. 2 is a cross-sectional view of another embodiment of the silencer of the present invention.

FIG. 3 is a sectional view of still another embodiment of the silencer of the present invention.

FIG. 4 is a cross-sectional view of yet another embodiment of the silencer of the present invention.

FIG. 5 (a) is a cross-sectional view of an embodiment of a clamp device used in the silencer of the present invention. The same (b) is a sectional view in a different fracture surface of the same (a).

FIG. 6 is a cross-sectional view of a different embodiment of the clamp device used in the muffler of the present invention.

FIG. 7 is a graph diagram relating to the muffling characteristics of the muffler of the present invention.

FIG. 8 is a layout system diagram of a conventional silencer (for gas).

FIG. 9 is a graph showing the silencing characteristics of a conventional silencer (for gas).

FIG. 10 is a graph showing a sound deadening characteristic for a liquid measured by using a conventional sound deadener (for gas).

FIG. 11 is a graph showing a sound deadening characteristic for a liquid measured by using a conventional sound deadener (for gas).

[Explanation of symbols]

1,1a, 1b neck 2,33,36 Expansion volume 3,31 Fixed cylinder 4,35 Movable cylinder 5 cavity 6 ball screw rod 7 nuts 8 reduction gears 9 Servo motor 10 Clamp device 25 balance cylinder 26 Flange 27 End plate 28 plumbing 29 Balance room 30 Balance pressure receiving surface 32 Movable piston 34 Fixed piston 37 Lid plate 38 holes 39 racks

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Bibliography Sho 59-81891 (JP, U) Rikai 54-80121 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) F16L 55/02-55/04 F02M 35/12 F01N 1/02

Claims (3)

(57) [Claims] 1. A liquid silencer having a cylindrical neck portion having one end connected to a sound deadening target structure and an expansion volume portion connected to the other end of the neck portion, wherein the expansion volume portion comprises two cylinders. , One of the cylinders is fixed to the other end of the neck as a fixed cylinder, and the other cylinder is a movable cylinder so that the peripheral surface of the fixed cylinder can move as a guide. together provided with a means to be powered for the mobile, provided with a clamping device which can stop firmly as necessary the movement in the circumferential surface of the movable cylinder, the movement of the movable cylinder in the expansion volume assisting
In order to keep the working fluid flowing,
A variable volume silencer for liquid, which is provided on the outer peripheral portion of the expansion volume . 2. A silencer for liquid having a cylindrical neck portion having one end connected to a structure to be silenced and an expansion volume portion connected to the other end of the neck portion, wherein the expansion volume portion is one piston. And a cylinder that is movable relative to the piston. One of the piston and the cylinder is fixed to the other end of the neck and the other is the movable part. The movable portion is provided with means for supplying power for the movement, and the movement is made strong as necessary by using the inner peripheral surface or the outer peripheral surface of the fixed portion as a guide. It includes a can stop the clamping device on the peripheral surface of the movable portion, the piston and the cylinder in the expansion volume
Balance that conducts working fluid to assist relative movement
A variable volume silencer for liquid , wherein a pressure receiving surface for liquid is provided on an outer peripheral portion of the expanded volume portion . 3. A liquid muffler having a cylindrical neck portion having one end connected to the noise reduction target structure and an expansion volume portion connected to the other end of the neck portion, wherein the entire length of the cylindrical neck portion is It is divided into two parts and one of them is attached to the structure to be silenced, the other is attached to the expansion volume part so that the free ends of both necks are in a relational position facing each other. The other neck attached to the expansion volume is configured to be movable together with the expansion volume relative to the neck of the subject, and both necks are overlapped with each other in an internal and external relationship during the movement. inner and outer diameters of the duration of engagement capable both neck is set, the expansion volume is provided with a means to be powered for the mobile and the clamping device may stop firmly as necessary the movement together when equipped on the peripheral surface of the expansion volume
A working fluid to assist the movement of the expansion volume.
A variable volume silencer for liquids, which is provided with a balance pressure-receiving surface on the outer periphery thereof.