JPH08135430A - Silencer - Google Patents

Abstract

(57) [Abstract] [Purpose] The composition is provided with a composition whose characteristic frequency can be changed according to the frequency of the sound wave to be absorbed, and absorbs (silences) the sound wave of the desired frequency in the exhaust sound. [Construction] The sound deadening case 27 is formed by joining a pair of split cases 26 to which heat-resistant sound-absorbing material 24 is pressed and fixed via a perforated plate 25. An exhaust passage forming pipe 29 having a large number of holes 28 formed in its surface is provided so as to penetrate therethrough. The exhaust sound is silenced by the resonance of the many holes 28 of the tube 29 and the sound absorption of the heat-resistant sound absorbing material 24. Besides, one electrode plate 18 of the pair of electrode plates 17 and 18 facing each other with a gap is fixed to the inner peripheral surfaces of the pair of horizontal portions of the sound deadening case 27 which face each other, and the pair of electrode plates An ENC fluid composition containing solid particles having an electric field arranging effect in an electrically insulating medium is housed between 17 and 18, and a pair of electrode plates 1
A variable power source 13 applies a voltage to 7 and 18.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is mainly used as a silencer for an engine exhaust pipe in an automobile, in which a so-called exhaust passage forming pipe having a large number of holes formed in its peripheral surface is provided in a silencer case. Resonance type silencer.

[0002]

2. Description of the Related Art FIG. 14 is a vertical sectional view of a conventional silencer of this type, and FIG. 15 is a sectional view taken along line DD of FIG. As shown in FIG. 14 and FIG. 15, the sound deadening case 44 is formed by joining a pair of split cases 43 in which a heat-resistant sound absorbing material (glass mat, etc.) 41 is pressed and fixed via a perforated plate 42. (Spot welding), and an exhaust passage forming pipe 46 having a number of holes 45 formed on its peripheral surface is penetrated into the sound deadening case 44 so as to extend across an inlet 47 and an outlet 48 of the sound deadening case 44. Are provided. Inside the exhaust passage forming pipe 46, a pipe 50 having a large number of holes 49 formed on its peripheral surface is formed.
Its end is located midway between the inlet 47 and the outlet 48,
Further, it is inserted from the inlet 47 side in a state where an annular space 51 is formed between the outer peripheral surface thereof and the inner peripheral surface of the exhaust passage forming pipe 46. As a result, the holes 4 are formed on the peripheral surfaces of both tubes 46 and 50.
The exhaust sound is silenced by the resonance caused by forming a large number of 5, 49, the expansion of the exhaust gas moving in the pipe 50 between the end of the pipe 50 and the outlet 48, and the sound absorption by the heat-resistant sound absorbing material 41. Configure a silencer. Exhaust path forming pipe 46
Is fixed to the sound deadening case 44 over its entire length through a plate-like stay 53 that divides the sound deadening case 44 into two and has a large number of holes 52 that connect the partitioned chambers (actually open shoji). 60-194117).

According to the above construction, the distance L between the end of the pipe 50 and the outlet 48 (see FIG. 14) and the both pipes 46, 50 are set in accordance with the exhaust pressure, the exhaust flow velocity, etc. based on the characteristics of each engine. By appropriately selecting the size, pitch, and number of the holes 45, 49, the diameter of the pipe 50, and the front and rear positions of the pipe 50 with respect to the exhaust passage forming pipe 46, the exhaust noise can be suppressed and the engine output can be improved. Can be planned. That is, by arranging the end of the pipe 50 inserted into the exhaust passage forming pipe 46 from the inlet 37 side in the middle of the inlet 37 and the outlet 48, the exhaust gas moving in the pipe 50 is exhausted from the end of the pipe 50 and the outlet. Four
The expansion of the exhaust gas and the expansion of the exhaust gas are performed so that the exhaust sound is silenced by the expansion of the exhaust gas. Therefore,
By appropriately setting the distance between the end of the pipe 50 and the outlet 48 in accordance with the engine speed change range, that is, the frequency of the exhaust noise, the exhaust noise having a frequency that cannot be silenced only by resonance can be silenced to some extent. it can.

[0004]

However, in the above-described conventional silencer, as shown in FIGS. 14 and 15, a pipe 50 having a hole 49 is further inserted into the exhaust passage forming pipe 46. There is a problem that the structure is complicated and the cost is unavoidable. Further, since the distance between the end of the pipe 50 and the outlet 48 is appropriately set according to the engine type, the engine speed change range, etc., that is, the frequency of the exhaust sound, the vehicle exhaust sound whose frequency changes over a wide range. To muffle sound, it is not practical because it is complicated to handle, and the frequency range of sound waves that can be absorbed is narrow (only sound waves with a component close to the natural frequency can be absorbed).
There is a problem that reliability is extremely low.

By the way, the inventors of the present invention are conducting research on a fluid composition for electro-sensitive acoustic wave absorption control having a novel electric field arrangement characteristic which has not been known. This fluid composition is, for example, a fluid obtained by dispersing solid particles in an electrically insulating medium. When an electric field is applied to the fluid composition, the solid particles cause dielectric polarization, and electrostatic attraction based on the dielectric polarization causes the solid particles to undergo dielectric polarization. It has the property of forming a chain structure by aligning and aligning in the direction of the electric field. In addition, some solid particles exhibit the property of exhibiting an array lump structure by electrophoresis and array alignment. In this way, the array orientation of particles under an electric field is referred to as an electric field array effect, and solid particles having such properties are referred to as an electric field array particle. Then, the inventors of the present invention arrived at the present invention by proceeding with research on the fluid composition for electro-sensitive sound wave absorption control having this novel structure.

The present invention has been made in view of the above problems of the prior art, and is provided with a fluid composition whose characteristic frequency can be changed by applying a voltage in accordance with the frequency of a sound wave to be absorbed. , Especially effective for absorbing low frequency sound waves, and can effectively absorb sound waves regardless of frequency range,
The purpose of the present invention is to provide a silencer that is low in cost and easy to handle.

[0007]

SUMMARY OF THE INVENTION To achieve the above object, a silencer of the present invention comprises a pipe for forming an exhaust passage having a large number of holes formed in its peripheral surface in the silencer case. In a silencer that is provided so as to extend through the inlet and the outlet, an inner peripheral surface of the silencer case is fixed with one electrode plate of a pair of electrode plates facing each other with a gap, and An electro-sensitive type acoustic wave absorption control fluid composition containing solid particles having an electric field array effect in an electrically insulating medium is housed between the pair of electrode plates, and a voltage is applied between the pair of electrode plates. And a voltage adjusting means for varying the applied voltage) and a voltage adjusting knob for adjusting the applied voltage. In addition, a film is attached to the outer surface of the other electrode plate, the voltage applying means includes a variable power source connected across the pair of electrode plates, and a switch connected in series to the variable power source. Can be composed of

[0008]

In the muffler of the present invention, a sound wave absorption control device (fluid composition type sound absorbing portion) is provided on the inner peripheral surface of the muffler case via one of the pair of electrode plates. . In the state where no voltage is applied between the pair of electrode plates, the electro-sensitive type acoustic absorption control fluid composition (hereinafter referred to as El
A solid particle (electric field array particle) having an electric field arrangement effect (hereinafter, Electric Alignment effect is abbreviated as “EA effect”) in an electric Noise-Control fluid composition is abbreviated as “ENC fluid composition”. Abbreviated as "EA particles") are randomly dispersed and randomly dispersed in an electrically insulating medium. When a voltage is applied to the pair of electrode plates by the voltage applying means, the EA particles are arrayed and linked in a chain to form a chain (particle chain), and the chain is aligned parallel to the electric field direction. In this state, if a sound wave (air vibration) is applied to the other electrode plate that is not fixed to the inner peripheral surface of the sound deadening case, this electrode plate will vibrate, but the chain itself has elastic properties. Therefore, when the chain is pulled, the particles facing each other attract each other to generate an attractive force, and when compressed, the chain bends to generate a repulsive force, and the movement of the chain in the electrically insulating medium causes viscous resistance. Occurs, which causes a loss (dissipation) of energy of the sound wave, and the noise can be absorbed.

That is, the sound wave incident on the other electrode plate causes the ENC fluid composition containing the chain to resonate with the electrode plate. The sound wave frequency that gives vibration to such a chain is a characteristic frequency of the chain (presumed to be a so-called natural frequency, which is a balance between the elasticity of the chain and the inertia of the other electrode plate). When a sound wave having a frequency determined by the characteristic frequency is incident on the other electrode plate, the chain resonates and absorbs the sound wave, and sound waves of other frequencies are reflected.

Since the attractive force (stress generated in the chain) acting between the particles increases as the voltage applied to the pair of electrode plates increases, the elastic modulus and viscosity of the chain itself are applied. The present invention takes advantage of this as the voltage increases as the voltage increases. In other words, the applied voltage is adjusted by the voltage adjustment knob so that the characteristic frequency of the chain itself matches the frequency of the component of the incident sound wave (air vibration) that is desired to be removed, so that the chain resonates (resonance). ), Consumes the energy of the component desired to be absorbed (removed), and reflects the other components.

The muffler of the present invention is provided in, for example, the exhaust pipe of an automobile, and the applied voltage is adjusted in accordance with the characteristics of each engine or the engine speed, for example, so that the exhaust noise of the vehicle can be adjusted in accordance with any speed Is reduced.

FIG. 10 shows the effect of the electric field strength on the electric field arrangement characteristics (hereinafter referred to as "EA characteristics") when the EA particle 30 wt% dispersion system is housed between a pair of opposing electrode plates. It is a graph which shows the measured result. It is clear from this graph that the stress acting on the chain increases as the applied voltage increases. The EA characteristic is due to the fact that the dielectrically polarized particles are arranged in the direction of the electric field by an electric attraction and form a chain structure. At low shear rates,
Since the electric attraction is dominant, the chain structure is repeatedly destroyed and reformed gently. The yield stress is the force that is generated when a chain arranged in the direction of the electric field undergoes shear failure in the direction perpendicular to it. Considering that the particles of all chains formed have the same diameter and connect the electrode plates in a straight line, the number of chains is proportional to the particle concentration, so the yield stress is also proportional to the particle concentration. It will be. FIG. 11 shows an equivalent circuit of the electrode plate vibration system described above, that is, in the electrode plate vibration system, a coil spring 22 having an elastic modulus K and a dashpot 23 having a viscosity C are connected in parallel between a pair of electrode plates. It can be regarded as an equivalent circuit.

[0013]

EXAMPLE An example of the silencer of the present invention will be described below.
A detailed description will be given with reference to the drawings. In order to facilitate understanding of the present invention, hereinafter, a fluid composition for controlling electro-acoustic sound wave absorption (ENC fluid composition) and a sound wave absorbing material constituted by accommodating the ENC fluid composition between a pair of electrode plates will be described. The control device and the silencer will be sequentially described.

First, FIG. 4 shows a specific example of the electro-sensitive acoustic wave absorption control fluid composition (ENC fluid composition) used in the muffler of the present invention. In this ENC fluid composition, EA particles (electric field arranging particles) 2 which are solid particles are uniformly dispersed in an electrically insulating medium 1. The EA particles 2 include a core 3 made of an organic polymer compound and particles 4 which are electric field aligning inorganic substances (hereinafter referred to as “EA inorganic substances”).
And the surface layer 5 composed of the In this specific example, the electrically insulating medium 1 is colorless and transparent silicone oil, the organic polymer compound forming the core body 3 of the inorganic / organic composite particles is polyacrylic ester, and the EA inorganic substance forming the surface layer 5 is used. The particles 4 are white titanium hydroxide that is an inorganic ion exchanger and an electric semiconductor inorganic substance. The color of the EA particles (inorganic / organic composite particles) is, for example, white. The proportion of the EA particles 2 contained in the electrically insulating medium 1 is, for example, 7.5% by weight.

As shown in FIG. 5, this ENC fluid composition is interposed between a pair of electrode plates 7 and 8 which are spaced apart and arranged in parallel. As shown in FIG. 6, when a voltage is applied to the pair of electrode plates 7 and 8 from the power source 9 through the switch 10, the EA particles 2 are chained in the direction perpendicular to the surfaces of the electrode plates 7 and 8 due to the EA effect. To form a chain (particle chain) 6. At this time, the chain-like bodies 6 are separated from each other and oriented in parallel.

Next, a description will be given of a sound wave absorption control device (sound vibration damping device) configured by accommodating the above ENC fluid composition between a pair of opposing electrode plates. As shown in FIG. 7, a pair of electrode plates 17 and 18 are arranged to face each other with a gap (composition storage space) therebetween.
Between 18 is the EA having the EA effect of the present invention described above.
An ENC fluid composition containing particles 2 in an electrically insulating medium 1 is contained. One (lower) electrode plate 18
Is fixedly arranged on a fixing member (not shown), and the other electrode plate 17 is uniformly adhered to the lower surface of, for example, a PET (polyethylene terephthalate) film 17a that is flexible against sound waves. A frame-shaped sealing member 15 is fixed to the periphery of the pair of electrode plates 17 and 18 and the periphery of the PET film 17a.

The ENC fluid composition of the present invention is housed in the space formed by the pair of electrode plates 17 and 18 and the seal member 15 in a sealed state. The one electrode plate 17 and the PET film 17a have their peripheral edges fixed, but are configured so that they can be vibrated in the facing direction of the pair of electrode plates 17 and 18 (the vertical direction indicated by the arrow X). As a result, the sound wave (air vibration) 11 is transmitted to PET.
When the light enters the film 17a, the PET film 1
7a and one electrode plate 17 can vibrate vertically. By sticking the PET film 17a on the outer surface of the electrode plate 17, the vibration followability of the electrode plate 17 due to the incidence of sound waves is improved.

Reference numeral 13 is a variable power supply that applies a voltage between the pair of electrode plates 17 and 18 and makes the applied voltage variable. A switch 14 is connected in series to the variable power supply 13. By turning on the switch 14, a voltage can be applied between the pair of electrode plates 17 and 18. This sound wave absorption control device is usually in the form of a rectangular plate or a circular plate in appearance, but of course, it has an appropriate shape according to the area where it is installed.

Next, the operation of the sound wave absorption control device having the above configuration will be described. As shown in FIG. 7, when no voltage is applied between the pair of electrode plates 17 and 18, EN
The EA particles 2 of the C fluid composition are randomly suspended and irregularly dispersed in the electrically insulating medium 1 (see FIG. 5). When a voltage is applied to the pair of electrode plates 17 and 18, the EA particles 2 in the ENC fluid composition are array-bonded in a chain to form a chain (particle chain) 6, and the chain 6 is directed in the electric field direction. Are arranged in parallel with each other (see FIG. 6).

In this state, when a sound wave (air vibration) 11 is made incident on one of the electrode plates 17, (a) in FIG.
The states of (b), (c), and (d) occur sequentially, and this electrode plate 17 moves along with the PET film 17a along with the arrow X.
As shown in (FIGS. 7 and 8), the chain body 6 itself vibrates in the opposite direction, but since the chain body 6 itself has an elastic property, as shown in FIG. , When compressed, it bends, for example, in a V shape to generate a repulsive force.
As shown in (d), when the chain-shaped body 6 is pulled, the EA particles 2 facing each other attract each other to generate an attractive force. As a result, due to the movement of the chain-like body 6 in the ENC fluid composition, viscous resistance is generated and energy loss (dissipation) of the sound wave 11 occurs.

Then, with the vibration of the electrode plate 17, the chain 6 is repeatedly pulled and compressed, and as a result, the chain 6 itself vibrates. That is, the sound wave 11 incident on the electrode plate 17 resonates with the ENC fluid composition containing the chain 6 and the electrode plate structure composed of the electrode plate 17 and the PET film 17a.
The sound wave frequency that gives vibration to the chain 6 is determined by the characteristic frequency of the chain 6, and when a sound wave 11 having a frequency matching the characteristic frequency enters the electrode plate 17, the chain 17 Resonates (see arrows A and B in FIG. 8) to absorb the sound wave, and the sound wave 12 having another frequency is reflected.

The force acting between the electric field arranging particles 2 (stress generated in the chain body 6) increases with an increase in the voltage applied to the pair of electrode plates 17 and 18. Therefore, the chain body 6 itself. The elastic modulus and the viscous coefficient of γ increase as the applied voltage increases. The present invention utilizes this fact to remove a desired component of a sound wave. That is, by adjusting the applied voltage and making the characteristic frequency of the particle chain 6 itself coincide with the frequency of the component (sound wave having a specific wavelength) to be removed in the sound wave (air vibration) incident on the electrode plate 17, As shown in FIG. 9, the chain body 6 is moved by the action of inertial force to the left and right arrows A and B.
As shown by (1), the resonance (resonance) is performed to consume the energy of the component of the incident sound wave 11 to be removed, and the other sound wave component (denoted by reference numeral 12) is reflected. in this way,
The applied voltage can absorb a desired specific wavelength component of the incident sound wave.

The characteristic frequency of the sound wave absorption control device is EA
Size of particles (solid particles), elastic force acting between EA particles,
It also changes depending on the natural frequency of the electrode plates and the distance between the electrode plates. In the present invention, since the spherical EA particles having a substantially uniform particle size are dispersed in the electrically insulating medium (without using irregular particles), the above-mentioned repulsive force and attractive force fluctuate under a constant voltage. In addition, the balance between the elastic force acting between the EA particles and the inertial force of the electrode plate does not easily change.
In the above-mentioned embodiment, the chain body is supposed to be bent in a V shape, but in addition to this, for example, an S-shape as shown in FIG. 12 (a) or (b) in FIG. It is considered that there is a case where the wire is bent into a W shape as shown in ().

Further, in the above embodiment, the phenomenon in which the EA particles (inorganic / organic composite particles) 2 form a row of chain-like bodies 6 and are arranged in parallel by the application of an electric field has been described. When the number of
Instead of the chain bodies 6 in one row, the chain bodies 6 are joined to each other in a plurality of rows to form and arrange the columns 19 as shown in FIG. In this column 19, the left and right chain-shaped EA particles 2 are staggered by one and adjoin each other.
With respect to this, the inventors of the present invention, as shown in FIG. 13B, have the EA particles 2 that are dielectrically polarized in the + pole portion and the − pole portion.
It is presumed that this is because it is more stable in terms of energy when the positive pole portion and the negative pole portion are alternately arranged adjacent to each other.

Next, an embodiment of the silencer of the present invention will be described with reference to the drawings. 1 is a vertical sectional view of this silencer, FIG. 2 is a sectional view taken along the line EE of FIG. 1, and FIG. 3 is a diagram showing an operation panel of a voltage applying means. As shown in FIGS. 1 and 2, in the sound deadening case 27, a heat-resistant sound-absorbing material (such as a glass mat) 24 is provided on the inner surface of each split case 26 to form the perforated plate 2.
The exhaust passage forming pipe 29 having a large number of holes 28 formed in its peripheral surface is joined to (spot welded) the members which are pressed and fixed via 5, and the exhaust passage forming pipe 29 It is provided so as to penetrate through the inlet 30 and the outlet 31. As a result, resonance due to the formation of a large number of holes 28 on the peripheral surface of the exhaust passage forming tube 29 and the heat-resistant sound absorbing material 2
The sound absorption by 4 composes a silencer that silences the exhaust sound. In addition, as a characteristic part of this embodiment, as will be described later, a sound wave absorption control device (fluid) including a pair of electrode plates 17 and 18 on the inner peripheral surface of the sound deadening case 27, that is, the inner peripheral surface of the perforated plate 25. A composition type sound absorbing part) is provided. The exhaust passage forming pipe 29 divides the inside of the muffling case 27 into two parts, and is fixed to the inside of the muffling case 27 through a plate-shaped stay 33 having a large number of holes 32 for communicating the partitioned chambers. ing.

The sound wave absorption control devices shown in FIG. 7 are provided on the inner peripheral surfaces of the horizontal portions of the pair of perforated plates 25 which are opposed to each other in the vertical direction. That is, on the inner peripheral surface of the horizontal portion of the perforated plate 25, one electrode plate 18 of the pair of electrode plates 17 and 18 facing each other with a gap is fixed, and between the pair of electrode plates 17 and 18. An ENC fluid composition containing solid particles 2 (see FIG. 1) having an electric field arranging effect in an electrically insulating medium 1 (see FIG. 1) is contained. PET film 17 on the outer surface of the other electrode plate 17
“A” faces the outer peripheral surface of the exhaust passage forming pipe 29. As the film to be attached to the outer surface of the electrode plate 17, besides the PET film, a heat resistant film is preferable because it is exposed to high temperature due to exhaust gas. Also, the seal member 15 (see FIG. 7) is preferably made of a heat resistant material. A pair of electrode plates 17, 18 provided on the upper perforated plate 25
Is configured to be applied with a voltage by the variable power supply 13, and the applied voltage is turned on / off by a switch 14 connected in series to the variable power supply 13. The voltage applying means 3 is constituted by the variable power source 13 and the switch 14.
5, the voltage applying means 35 is also configured to apply a voltage to the pair of electrode plates 17 and 18 provided on the lower perforated plate 25. Further, the applied voltage value can be easily adjusted by, for example, a rotary type voltage adjusting knob 36 as shown in FIG. Reference numeral 34 indicates an operation panel, which is the switch 14 described above.
A voltage control knob 36 and a scale 37 thereof are provided, and for example, it is provided at an appropriate height portion of the dashboard so as to be easily operated by a person in an automobile. Voltage applying means 3 described above
In FIG. 5, the pair of sound wave absorption control devices collectively controls the voltage, but the voltage may be individually controlled.

As shown in FIGS. 1 to 3, when the engine of the automobile is stopped, the switch 14 is turned off and no voltage is applied between the pair of electrode plates 17 and 18. When the engine is operating, the switch 14 is turned on in order to absorb the exhaust sound, and the voltage adjustment knob 36 is used to particularly absorb the sound wave (for example, the frequency range of the most included exhaust sound in the exhaust sound at a certain engine speed). The applied voltage is set according to the frequency of the sound wave component). Further, the applied voltage may be adjusted so that a high sound in the exhaust sound is absorbed by the heat-resistant sound absorbing material (glass mat etc.) 24 and a low sound is absorbed by the sound wave absorption control device of the present invention. Similar to the operation of the sound wave absorption control device described above, when a sound wave is incident on the electrode plate 17,
The electrode plate 17 vibrates. Due to the PET film 17a, the vibration followability of the electrode plate 17 is high. The ENC fluid composition containing the chain resonates with the electrode plate due to the sound wave incident on the electrode plate 17. The sound wave frequency that gives vibration to such a chain is determined by the characteristic frequency of the chain (which is estimated to be a so-called natural frequency, which is a balance between the elasticity of the chain and the inertia of the electrode plate 17). When a sound wave having a frequency that matches the characteristic frequency is incident on the electrode plate 17, the chain resonates and absorbs the sound wave, and sound waves of other frequencies are reflected.

According to the above configuration, the applied voltage is adjusted according to the exhaust pressure, the exhaust flow velocity, etc. based on the characteristics of each engine, so that the multiple holes 28 of the exhaust passage forming pipe 29 are adjusted.
It is possible to muffle exhaust noise of a frequency that could not be muffled only by resonance, and it is possible to provide a muffler that is useful for muffling exhaust noise of automobiles whose frequency changes over a wide range by a simple operation of adjusting the applied voltage. .

In the above embodiment, an example in which a silencer is attached to an exhaust pipe of an automobile is used, but the present invention is not limited to this, and the present invention is also applied to an exhaust pipe of an engine of a small ship or an engine of a power machine or the like. It goes without saying that the invention can be applied. Further, although the one in which the ENC fluid composition is directly contained between the pair of electrode plates 17 and 18 is shown, the invention is not limited to this, and the ENC fluid composition
A porous body sufficiently impregnated with the C fluid composition may be housed between the pair of electrode plates 17 and 18. In this case, the porous body preferably has open cells so as not to impair the EA effect. Further, the sound wave absorption control device as in the above embodiment is not limited to be provided only on the inner peripheral surface of the horizontal portion of the perforated plate 25, but the sound wave absorption control device may be provided on the inner peripheral surface of the perforated plate 25 which is inclined. Alternatively, it may be provided only on the inclined inner peripheral surface. Furthermore, the voltage control is not limited to the one in which the pair of sound wave absorption control devices is collectively controlled as in the above-described embodiment, and the pair of sound wave absorption control devices or the sound wave absorption control devices provided at three or more locations are individually voltage-controlled. It may be one. Further, the perforated plate 25 is not limited to the one having the holes formed in the entire area thereof, and the holes may not be formed in the portion where the sound wave absorption control device is provided (horizontal portion in this embodiment).

The electrically insulating medium 1 used in the ENC fluid composition according to the present invention is, for example, diphenyl chloride,
Butyl sebacate, aromatic polycarboxylic acid higher alcohol ester, halophenyl alkyl ether, trans oil, chlorinated paraffin, fluorine oil, silicone oil, fluorosilicone oil, etc. Chemically stable and E
Any fluid or a mixture thereof can be used as long as it can stably disperse the A particles. This electrically insulating medium 1 can be colored according to the purpose. For coloring, it is preferable to use a type and amount of an oil-soluble dye or a dispersible dye that is soluble in the selected electrically insulating medium and does not impair its electrical properties. The electrically insulating medium 1 may further contain a dispersant, a surfactant, a viscosity modifier, an antioxidant, a stabilizer and the like.

The kinematic viscosity of this electrically insulating medium 1 is 1 cS.
It is preferably in the range of t to 30,000 cSt. When the kinematic viscosity is less than 1 cSt, the storage stability of the fluid composition is insufficient, and when the kinematic viscosity is more than 30,000 cSt, it becomes difficult to uniformly disperse the EA particles, and bubbles are entrained during the adjustment, and the bubbles are It is difficult to pull out, and it is difficult to handle, which is not preferable. From this viewpoint, the kinematic viscosity is preferably in the range of 10 cSt to 1000 cSt, particularly preferably in the range of 10 cSt to 100 cSt. Of course, the kinematic viscosity of the electrically insulating medium 1 changes with temperature, but this temperature effect can be suppressed by the applied voltage.

The EA particles 2 used in the present invention may be any element, organic compound, or inorganic compound, or a mixture thereof, as long as it is an inorganic-organic composite particle having an EA effect.
Either material can be used. Examples thereof include particles of inorganic ion exchangers, metal oxides, silica gel, inorganic substances having electric semiconductors, carbon black, and particles having these as a surface layer. However, as shown in the above examples, the EA particles 2 are composed of the core body 3 made of an organic polymer compound and the EA inorganic particle 4
It is particularly preferable that the inorganic-organic composite particles are formed by the surface layer 5 consisting of. In this inorganic-organic composite particle, a surface layer 5 composed of particles 4 of EA inorganic material having a relatively high specific gravity is carried on a core body 3 which is an organic polymer compound having a relatively low specific gravity, and the specific gravity of the entire particle is changed to an electric value. It can be adjusted to approximate the insulating medium 1. Therefore, the ENC fluid composition obtained by dispersing this in the electrically insulating medium 1 has excellent storage stability.

Examples of the organic polymer compound that can be used as the core 3 of the EA particles (inorganic / organic composite particles) 2 include poly (meth) acrylic acid ester, (meth) acrylic acid ester-styrene copolymer, Polystyrene, polyethylene, polypropylene, nitrile rubber, butyl rubber, AB
S resin, nylon, polyvinyl butyrate, ionomer, ethylene-vinyl acetate copolymer, vinyl acetate resin,
One or a mixture of two or more such as a polycarbonate resin or a copolymer may be mentioned.

Particles 4 which are the EA inorganic substance forming the surface layer 5
Although various compounds can be used, preferred examples include inorganic ion exchangers, silica gel, and electrically semiconducting inorganic substances. When these particles 4 are used to form the surface layer 5 on the core 3 made of an organic polymer compound, the obtained inorganic / organic composite particles become useful EA particles 2.

Examples of the above inorganic ion exchanger include (1)
Hydroxide of polyvalent metal, (2) hydrotalcites,
(3) Acid salt of polyvalent metal, (4) Hydroxyapatite, (5) Nasicon type compound, (6) Clay mineral, (7)
Mention may be made of potassium titanates, (8) heteropolyacid salts, and (9) insoluble ferrocyanide.

The respective inorganic ion exchangers will be described in detail below. (1) Hydroxide of polyvalent metal. These compounds are represented by the general formula MO _x (OH) _y (M is a polyvalent metal, x is a number of 0 or more, and y is a positive number), and examples thereof include titanium hydroxide and hydroxide. Zirconium, bismuth hydroxide, tin hydroxide, lead hydroxide, aluminum hydroxide, tantalum hydroxide,
Examples include niobium hydroxide, molybdenum hydroxide, magnesium hydroxide, manganese hydroxide, and iron hydroxide. Here, for example, titanium hydroxide means hydrous titanium oxide (also known as metatitanic acid or β-titanic acid, TiO (OH) ₂ ) and titanium hydroxide (also known as orthotitanic acid or α-titanic acid,
It includes both Ti (OH) ₄ and other compounds.

(2) Hydrotalcites. These compounds have the general formula M ₁₃ Al ₆ (OH) ₄₃ (CO) ₃ · 12H
It is represented by ₂ O (M is a divalent metal), and the divalent metal M is, for example, Mg, Ca or Ni. (3) Acid salt of polyvalent metal. These are, for example, titanium phosphate, zirconium phosphate, tin phosphate, cerium phosphate,
Chromium phosphate, zirconium arsenate, titanium arsenate, tin arsenate, cerium arsenate, titanium antimonate, tin antimonate, tantalum antimonate, niobium antimonate, zirconium tungstate, titanium vanadate, zirconium molybdate, selenate Examples include titanium and tin molybdate.

(4) Hydroxyapatite. These are, for example, calcium apatite, lead apatite, strontium apatite, cadmium apatite and the like. (5) Nasicon type compound. These include (H ₃ O)
Although Zr ₂ (PO ₄ ) _{3 and} the like are included, a Nasicon type compound in which H ₃ O is replaced with Na can also be used in the present invention. (6) Clay mineral. These are, for example, montmorillonite, sepiolite, bentonite and the like, with sepiolite being particularly preferred.

(7) Potassium titanates. These are general formulas aK ₂ O · bTiO ₂ · nH ₂ O (a is a positive number satisfying 0 <a ≦ 1, b is a positive number satisfying 1 ≦ b ≦ 6,
n is a positive number), for example, K ₂ · TiO ₂ · 2H
₂ O, K ₂ O ・₂ TiO ₂・ 2 H ₂ O, 0.5 K ₂ O ・ Ti
O ₂ · 2H ₂ O, and the like _{K 2 O · 2.5TiO 2 · 2H} 2 O. In addition, among the above compounds, a compound in which a or b is not an integer is easily synthesized by subjecting a compound in which a or b is an appropriate integer to an acid treatment and replacing K with H.

(8) Heteropolyacid salt. These are the general formula H
₃ AE ₁₂ O ₄₀ · nH ₂ O (A is phosphorus, arsenic, germanium, or silicon, E is molybdenum, tungsten, or vanadium, and n is a positive number), for example, ammonium molybdophosphate, And ammonium tungstophosphate. (9) Insoluble ferrocyanide. These are compounds represented by the following general formula. M _b-pxa A [E (CN) ₆ ] (M
Is an alkali metal or hydrogen ion, A is zinc, copper, nickel, cobalt, manganese, cadmium, iron (III)
Or a heavy metal ion such as titanium, E is iron (II), iron (III), or cobalt (II), b is 4 or 3, a is a valence of A, and p is 0 to b. /
It is a positive number of a. ) These include, for example, insoluble ferrocyanine compounds such as Cs ₂ Zn [Fe (CN) ₆ ] and K ₂ Co [Fe (CN) ₆ ].

The inorganic ion exchangers (1) to (6) each have an OH group, and some or all of the ions present at the ion exchange sites of these inorganic ion exchangers are different ions. Those substituted with (hereinafter, referred to as a substitutional inorganic ion exchanger) are also included in the inorganic ion exchanger of the present invention. That, R-M ¹ inorganic ion exchanger described above (M ¹ represents an ion species of the ion exchange sites) is expressed as a part or all of M ¹ in the R-M ^1, the ion exchange reaction below A substituted inorganic ion exchanger in which an ionic species M ² different from M ¹ is substituted by
It is an inorganic ion exchanger in the present invention. xR−M ¹ + yM ² → Rx− (M ² ) y + xM ¹ (where x and y represent the valences of the ion species M ² and M ¹ , respectively). M ¹ varies depending on the type of the inorganic ion exchanger having an OH group, but when the inorganic ion exchanger exhibits a cation exchange property, M ¹ is generally H ⁺ , and in this case, M ² is an alkali metal or an alkali. Any metal ion other than H ⁺ , such as earth metals, polyvalent typical metals, transition metals or rare earth metals. When the inorganic ion exchanger having an OH group exhibits anion exchange property, M ¹ is generally OH ^−.
Where M ² is, for example, I, Cl, SCN, N
Any of anions other than OH ⁻ such as O ₂ , Br, F, CH ₃ COO, SO ₄ or CrO ₄ and complex ions.

Further, regarding the inorganic ion exchanger which has once lost the OH group due to the high temperature heat treatment, but becomes to have the OH group again by an operation such as immersion in water, the inorganic ion after the high temperature heat treatment is used. Exchangers and the like are also a kind of inorganic ion exchangers that can be used in the present invention, and specific examples thereof include a Nasicon type compound such as (H ₃ O) Zr ₂
(PO ₄₎ HZr ₂ obtained by heating ₃ (PO _{4) 3} and high-temperature heat treatment of hydrotalcite (500 to 70
Heat treated at 0 ° C.) and the like. These inorganic ion exchangers can be used not only in one kind but also in many kinds simultaneously as a surface layer. It is particularly preferable to use a hydroxide of a polyvalent metal and an acid salt of a polyvalent metal as the above-mentioned inorganic ion exchanger.

An example of an electrically semiconductive inorganic material that can be used as the surface layer 5 of the EA particles (inorganic / organic composite particles) 2 is a metal having an electric conductivity of 10 ³ to 10 ^-11 Ω ^-1 / cm at room temperature. Oxides, metal hydroxides, metal oxide hydroxides, inorganic ion exchangers, or metal-doped at least one of these, or at least any one of these regardless of the presence or absence of metal doping For example, those applied as an electric semiconductor layer on another support.

Examples of preferable electrically semiconductive inorganic substances are shown below. (A) Metal oxide: For example, SnO ₂ or amorphous titanium dioxide (manufactured by Idemitsu Petrochemical Co., Ltd.). (B) Metal hydroxide: For example, titanium hydroxide or niobium hydroxide. Here, titanium hydroxide means hydrous titanium oxide (manufactured by Ishihara Sangyo Co., Ltd.), metatitanic acid (also known as β-titanic acid,
TiO (OH) ₂ ) and orthotitanic acid (also known as α-titanic acid, Ti (OH) ₄ ) are included. (C) Metal oxide hydroxide: For example, FeO
(OH) (goethite) and the like can be mentioned. (D) Hydroxide of polyvalent metal: equivalent to inorganic ion exchanger (1). (E) Hydrotalcites: Inorganic ion exchanger (2)
Equivalent to (F) Acid salt of polyvalent metal: equivalent to the inorganic ion exchanger (3). (G) Hydroxyapatite: Inorganic ion exchanger (4)
Equivalent to (H) Nashicon type compound: equivalent to the inorganic ion exchanger (5). (I) Clay mineral: equivalent to the inorganic ion exchanger (6). (J) Potassium titanate: equivalent to the inorganic ion exchanger (7). (K) Heteropolyacid salt: equivalent to the inorganic ion exchanger (8). (L) Insoluble ferrocyanide: equivalent to inorganic ion exchanger (9). (M) Metal-Doped Electric Field Alignment Inorganic Material: This is an ER inorganic material doped with a metal such as antimony (Sb) in order to increase the electric conductivity of the above-mentioned electric semiconductor inorganic materials (A) to (L). As an example, antimony (Sb) -doped tin oxide (SnO ₂ ) and the like can be mentioned. (N) An electric field arranging inorganic substance as an electric semiconductor layer on another support: for example, inorganic oxide particles such as titanium oxide, silica, alumina, or silica-alumina as a support,
Alternatively, organic polymer particles such as polyethylene and polypropylene are used, and antimony (S
b) Doped tin oxide (SnO ₂ ) may be used. The particles in which the electric field aligning inorganic substance is applied to the other support in this manner can be regarded as the electric field aligning inorganic substance as a whole. These electric field aligning inorganic materials may be used not only in one kind but also in two kinds or more simultaneously as a surface layer.

The EA particles (inorganic / organic composite particles) 2 can be manufactured by various methods. For example, there is a method in which a particulate core body 3 made of an organic polymer compound and fine particulate particles 4 are transported by a jet stream and collided with each other to produce them. In this case, the fine particles of the particles 4 collide with the surface of the particulate core 3 at a high speed and are fixed to form the surface layer 5. Another example of the manufacturing method is a method in which the particulate core body 3 is suspended in a gas, and a solution of the particles 4 is atomized and sprayed on the surface. In this case, the surface layer 5 is formed by adhering the solution onto the surface of the core 3 and drying it.

A particularly preferred method for producing the EA particles (inorganic / organic composite particles) 2 is to form the surface layer 5 at the same time as the core body 3. In this method, for example, when the monomer of the organic polymer compound forming the core 3 is emulsion-polymerized, suspension-polymerized, or dispersion-polymerized in a polymerization medium, the particles 4 which are fine-grained electric field-aligning inorganic substances are added to the monomer. During,
Alternatively, it is present in the polymerization medium. Water is preferred as the polymerization medium, but a mixture of water and a water-soluble organic solvent can also be used, and an organic poor solvent can also be used. According to this method, the monomers are polymerized in the polymerization medium to form the core particles 3, and at the same time,
The fine particle EA inorganic particles 4 are oriented in layers on the surface of the core body 3 and cover the core body 3 to form the surface layer 5.

In the case of producing EA particles (inorganic / organic composite particles) by emulsion polymerization or suspension polymerization, the electric field aligning property is obtained by combining the hydrophobic property of the monomer and the hydrophilic property of the inorganic substance. Most of the inorganic particles 4 can be attached to the surface of the core body 3. According to the method of simultaneously forming the core body 3 and the surface layer 5, the EA inorganic particles 4 are densely and firmly adhered to the surface of the core body 3 made of an organic polymer compound, and the EA particles (inorganic / organic composite) Particles 2) are formed.

The shape of the EA particles 2 used in the present invention does not necessarily have to be spherical, but when the particulate core 3 is produced by a controlled emulsion / suspension polymerization method, the EA obtained is obtained. The shape of the particles 2 is almost spherical. EA
The particle size of the particles 2 is not particularly limited, but is 0.1
The thickness is preferably in the range of μm to 500 μm, particularly 5 μm to 200 μm. Fine particle EA at this time
The particle size of the inorganic particles 4 is not particularly limited, but is preferably 0.005 μm to 100 μm, and more preferably 0.01 μm to 10 μm.

In the EA particles (inorganic / organic composite particles) 2, the particles 4 which are the EA inorganic substance forming the surface layer 5 and the core 3
The weight ratio of the organic polymer compound forming the is not particularly limited, but in order to obtain an ENC fluid composition having high storage stability, the EA inorganic particles 4 and the organic polymer compound core 3 are used. 1% by weight of particles 4 to 6% of the total weight
It is preferably in the range of 0% by weight, particularly preferably in the range of 4% by weight to 30% by weight. If the proportion of the core 3 is less than 1% by weight, the EA characteristics of the obtained EA particles 2 will be insufficient, and if it exceeds 60% by weight, the specific gravity of the EA2 particles will be excessive and the storage stability may be impaired. There is. Further, the ENC fluid composition according to the present invention can be produced by uniformly stirring and mixing the above-mentioned EA particles 2 in an electrically insulating medium together with a dispersant and other components, if necessary. As the stirrer, any stirrer normally used for dispersing solid particles in a liquid dispersion medium can be used. The content of the EA particles 2 in the electrically insulating medium 1 is not particularly limited, but is preferably 0.5 to 75% by weight, particularly preferably 5 to 50% by weight. If the content is less than 1%, a sufficient EA effect cannot be obtained, and if the content is 75% or more, the initial viscosity of the ENC fluid composition when a voltage is not applied becomes too large, which makes it difficult to use.

The EA particles 2 produced by the above-mentioned various methods, particularly the method of simultaneously forming the core 3 and the surface layer 5,
The surface layer 5 is wholly or partly covered with a thin film of an organic polymer substance, a dispersant, an emulsifier or other additive substances used in the manufacturing process, and the electric field arrangement effect as electric field arrangement particles is not sufficiently exhibited. There are cases. This thin film of inert material can be easily removed by polishing the surface of the particles. Therefore, when the core body 3 and the surface layer 5 are simultaneously formed, it is preferable to polish the surfaces thereof.

The polishing of the particle surface can be performed by various methods. For example, EA, which is an inorganic / organic composite particle
The method can be performed by dispersing the particles 2 in a dispersion medium such as water and stirring this. At this time, a method of mixing an abrasive such as sand particles or balls into the dispersion medium and stirring with the EA particles 2, a method of stirring with a grinding wheel, or the like can be used. For example, it is also possible to dry-stir without using a dispersion medium, using the EA particles 2 and the above-mentioned abrasive or grinding stone.

A more preferred polishing method is a method in which the EA particles 2 are agitated by a jet stream or the like. This is a method of polishing particles by violently colliding with each other in a gas phase, and is a preferable method in that the polished particles can be easily separated by classification without the need for another abrasive. In the above jet stream agitation, it is necessary to select polishing conditions depending on the type of equipment used, the agitation speed, the material of the EA particles 2, etc., but generally 60
It is preferable to perform jet stream stirring at a stirring speed of 00 rpm for about 0.5 min to 15 min.

The ENC fluid composition according to the present invention can be produced by uniformly stirring and mixing the above-mentioned EA particles 2 in the electrically insulating medium 1 together with other components such as a dispersant, if necessary. As the stirrer, any stirrer normally used for dispersing solid particles in a liquid dispersion medium can be used.

[0054]

Since the present invention is configured as described above, it has the following effects. The silencer of the present invention, by setting the characteristic frequency of the fluid composition having an electric field array effect in accordance with the frequency of the component of the sound wave to be absorbed, without changing the fluid composition,
It is possible to absorb a sound wave of a desired frequency of the sound wave of almost the entire frequency range including the low frequency range. Further, the muffler of the present invention is provided in, for example, an exhaust pipe of an automobile, and the applied voltage is adjusted according to the engine speed or the exhaust pressure or exhaust flow velocity based on the characteristics of each engine to form an exhaust passage. Exhaust noise with a frequency that could not be silenced only by resonance due to the many holes in the pipe can be silenced, and by simple operation of adjusting the applied voltage, it is possible to muffle the exhaust noise of automobiles whose frequency changes over a wide range. A very useful silencer can be provided. As a result, it is possible to provide a silencer that is lightweight, inexpensive, and easy to handle. Further, by attaching a film to the outer peripheral surface of the electrode plate on the side where the sound wave is incident, the vibration followability of the electrode plate due to the sound wave incident is enhanced.

[Brief description of drawings]

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

FIG. 2 is a sectional view taken along line EE of FIG.

FIG. 3 is a diagram showing an operation panel.

FIG. 4 is a cross-sectional view showing an example of the electro-sensitive sound wave absorption control fluid composition.

FIG. 5 is a cross-sectional view showing an aspect of a fluid composition for electro-sensitive sound wave absorption control when the power is off.

FIG. 6 is a cross-sectional view showing an aspect of the fluid composition for electro-sensitive sound wave absorption control when the power is turned on.

FIG. 7 is a cross-sectional view of a sound wave absorption control device (sound control device) provided with a fluid composition for electro-sensitive sound wave absorption control.

FIG. 8 is a cross-sectional view showing a state in which a sound wave is incident and resonates in a sound wave absorption control device including the electro-sensitive type sound wave absorption control fluid composition.

FIG. 9 is a cross-sectional view showing a state where a sound wave is incident on one of the electrode plates and vibrates in a sound wave absorption control (sound control) device including the electro-sensitive type sound wave absorption control fluid composition.

FIG. 10 is a graph showing the results of measuring the effect of electric field strength on electric field arrangement characteristics of an electric field arrangement particle dispersion system.

FIG. 11 is a diagram showing an equivalent circuit of a vibration system.

FIG. 12 is a view showing another example of the bending state of the chain in the sound wave absorption control device provided with the fluid composition for electro-sensitive sound wave absorption control.

FIG. 13 is a view showing a column in which a plurality of chains are joined to each other in a sound wave absorption control device provided with a fluid composition for electro-sensitive sound wave absorption control.

FIG. 14 is a vertical cross-sectional view of a conventional silencer.

15 is a cross-sectional view taken along line DD of FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Electrically insulating medium, 2 ... Electric field arrangement particles (EA particles,
Solid particles, inorganic / organic composite particles, 3 ... Core body (organic polymer compound), 4 ... Particles (particles of electric field aligning inorganic material), 5
... Surface layer, 6 ... Chain-like body (particle chain), 7, 8 ... Electrode plate, 9 ...
Power source, 10 ... Switch, 11 ... Incident sound wave, 12 ... Reflected sound wave, 13 ... Variable power supply, 14 ... Switch, 15 ... Seal member, 17, 18 ... Electrode plate, 17a ... PET (polyethylene terephthalate) film, 19 ... Column, 20, 2
DESCRIPTION OF SYMBOLS 1 ... Chain-shaped body (particle chain), 22 ... Coil spring, 23 ... Dashpot, 24 ... Heat-resistant sound-absorbing material, 25 ... Perforated plate, 26
... split case, 27 ... muffling case, 28 ... hole, 29 ... exhaust passage forming tube, 30 ... inlet, 31 ... outlet, 32 ... hole, 33
... plate-like stay, 34 ... operation panel, 35 ... voltage applying means, 36 ... voltage adjusting knob, 37 ... scale.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Kazuya Edamura 2-6-15 Shiba Park, Minato-ku, Tokyo Inside Fujikura Kasei Co., Ltd. (72) Inventor Hidenobu Anzai 1-5 Kiba, Koto-ku, Tokyo No. 1 Fujikura Co., Ltd. (72) Inventor Yasufumi Otsubo 9-21-1 Konakadai, Inage-ku, Chiba-shi, Chiba 206

Claims (3)

[Claims] 1. A pipe (29) for forming an exhaust passage, having a number of holes (28) formed in its peripheral surface, in a muffler case (27),
Inlet (30) and outlet (31) of the silencing case (27)
In a muffler that is provided so as to penetrate therethrough, one electrode plate (18) of a pair of electrode plates (17, 18) facing each other with a gap on the inner peripheral surface of the muffler case (27). ) Is fixed and the pair of electrode plates (1
7 and 18), a fluid composition for electro-sensitive acoustic wave absorption control containing solid particles (2) having an electric field arrangement effect in an electrically insulating medium (1) is housed, and the pair of electrodes. A voltage applying means (35) for applying a voltage between the plates (17, 18) and varying the applied voltage, and a voltage adjusting knob (36) for adjusting the applied voltage are provided. A muffler characterized by that. 2. The silencer according to claim 1, wherein a film (17a) is attached to the outer surface of the other electrode plate (17). 3. The voltage applying means (35) includes a variable power source (13) connected across the pair of electrode plates (17, 18) and a switch (14) connected in series to the variable power source (13). ) And the silencer according to claim 1 or 2.