JP3101116B2 - Exhaust device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust device having a noise reduction function.

[0002]

2. Description of the Related Art As an exhaust device, there is an exhaust device used for exhausting steam or oil smoke generated in a range.
This type of exhaust device is shown in FIG. This exhaust device is arranged above a range or the like, and the steam or oil smoke emitted from the range is collected by the hood portion 2, the steam or oil smoke is sucked by a fan 1 such as a sirocco fan, and the exhaust device is outdoor through an exhaust duct 3. It is structured to discharge to Here, a filter 4 is provided inside the hood portion 2 so as to remove oil contained in exhausted air.

In this type of exhaust device, wind noise is generated at the opening of the suction port 1a of the fan 1 to generate noise. Therefore, the opening edge of the suction port 1a is bent, and the bent portion 1c prevents the generation of wind noise.

[0004]

By the way, the exhaust device having the above structure has a problem that when the rotation speed of the fan 1 is increased, the noise increases accordingly. In addition, a standing wave is generated depending on the length of the exhaust duct 3, and the standing wave reduces the pressure in the exhaust duct 3, which places a burden on the fan 1 and further increases the noise. Was. When this type of exhaust device is used for home use, noise may be generated so that the sound of the television cannot be heard.

[0005] The present invention has been made in view of the above points, and an object of the present invention is to provide an exhaust device capable of reducing noise.

[0006]

According to the first aspect of the present invention, in order to achieve the above object, the interior of the hood portion is divided into upper and lower spaces, and a muffler having a duct structure is installed at the boundary thereof. The fan is placed vertically in the upper space of the hood with the suction direction as the horizontal direction, and a front panel that can be opened and closed is provided on the opposite surface of the fan of the hood, the cross-sectional area of the fan inlet and the duct of the silencer The cross-sectional area of the upper space is larger than the cross-sectional area of the portion.

[0007] In order to enhance the efficiency of collecting steam, oily smoke, etc., it is preferable that the muffler be disposed in the front of the hood. In order to increase the suction efficiency of the exhaust device, it is preferable that the cross-sectional area of the duct of the silencer is larger than the cross-sectional area of the intake port of the fan.

[0008] Further, in order to further improve the noise reduction effect,
As described in claim 4, it is preferable to attach a sound absorbing material to the opposite surface of the hood portion in the intake direction of the fan. Furthermore, in order to improve the noise reduction effect and to prevent oil from flowing down through the duct portion,
The duct portion of the muffler may be protruded from the upper surface.

In order to reduce wind noise generated in the duct portion of the silencer, it is preferable that the duct portion is formed in a tapered shape which expands downward on the intake side of the duct portion. Further, in order to facilitate the manufacture of the muffler, the duct section may be formed in a rectangular shape.

[0010] In order to particularly improve the noise reduction efficiency of the low frequency component of the noise, a microphone for picking up noise propagating in the duct portion and an inverting amplifier for inverting and amplifying the picked-up signal. And a speaker that emits inverted and amplified noise into the duct portion are provided in the muffler, and an active muffling function is added to mute the noise in the duct by sound interference, and at least the microphone and the speaker are housed in the base of the muffler. A sound-absorbing material that absorbs high-frequency sound is formed between the sound-passing hole, the microphone, and the speaker by forming a sound-passing hole that inputs sound to the microphone, outputs sound from the speaker, and communicates with the duct unit. Is also good.

Here, in order to stabilize the muffling operation of the active muffling function part, the present invention according to claim 8 has a structure in which the sound absorbing material is not interposed between the microphone and the speaker. Is preferred. In the invention of claim 8, in order to efficiently perform the muffling operation of the active muffling function section, as described in claim 10, a sound passage hole is formed in at least a surface of the base of the muffling device facing the speaker. Forming an expansion chamber communicating with the duct section through
It is preferable to store the sound absorbing material in the expansion chamber.

Further, in the invention according to any one of claims 8 to 10, in order to reduce the wind noise of the sound passage hole, the sound passage hole is provided with an air flow in the duct portion. Is preferably formed in a slit shape that is long in the flow direction. Here, in the invention according to any one of claims 8 to 10, in order to prevent oil from adhering to a speaker, a microphone, or a sound-absorbing material, the first aspect of the invention is described.
As shown in FIG. 2, the storage section for storing the speaker and the microphone or the storage section for storing the sound absorbing material may be communicated with the duct section through the opening, and a filter for passing sound and collecting oil may be detachably attached to the opening. .

Further, in the invention according to any one of claims 8 to 10, in order to stabilize the muffling operation of the active muffling function section, a speaker and a microphone are arranged in parallel with the duct section. It is preferable to dispose them on the same plane. Further, in the invention according to any one of claims 8 to 10, in order to reduce the weight and the cost, as described in claim 14, the speaker has a low noise that is particularly annoying due to noise generated by a fan. It is preferable to use one having a minimum diameter capable of emitting a frequency sound.

Further, in the invention according to any one of claims 8 to 10, in order to prevent unnecessary activation of the active silence function section, the present invention provides the following:
The active silencer may be operated in conjunction with the operation of the fan.

[0015]

According to the first aspect of the present invention, the upper space of the hood portion is so-called by making the cross-sectional area of the upper space larger than the cross-sectional area of the intake port of the fan and the cross-sectional area of the duct portion of the muffler. Let it function as a silencer for an extended silencer,
Mute fan noise. In addition, the provision of the muffling device, together with the muffling function of the upper space, effectively muffles the noise of the fan. Further, by disposing the fan vertically in the upper space of the hood portion with the intake direction as the horizontal direction and providing a front panel that can be opened and closed on the opposite surface of the fan of the hood portion, the front panel is opened, and the fan and It is possible to easily clean the upper space.

According to a second aspect of the present invention, by disposing the muffler in the front portion of the hood portion, steam, oily smoke, etc. generated in the front portion of the range can rise to the duct position of the muffler. For example, since the exhaust device targeted by the present invention is usually mounted on a wall surface, it is possible to efficiently collect steam, oil smoke, and the like generated at the rear portion of the range between the wall surface and the hood portion. It is possible to increase the collection efficiency of such as.

According to a third aspect of the present invention, the cross-sectional area of the duct of the silencer is made larger than the cross-sectional area of the intake port of the fan, so that the air-intake capacity of the fan is sufficiently exhibited and the suction efficiency of the exhaust device is improved. It becomes possible to raise it. Claim 4
As shown in the figure, if a sound absorbing material is attached to the opposite surface of the hood in the direction of intake of the fan, noise from the fan can be directly absorbed by the sound absorbing material, and noise generated by the fan can be reduced.
Combined with the muffling effect of claim 1, it is possible to improve the muffling effect.

According to a fifth aspect of the present invention, when the duct portion of the muffler is protruded from the upper surface, the length of the duct portion can be increased to improve the muffling effect. This prevents the flowing oil from entering the duct, and prevents the oil from flowing down through the duct. According to a sixth aspect of the present invention, when the intake side of the duct portion is formed in a tapered shape in which the diameter is increased downward, air flows smoothly into the duct portion, and generation of wind noise is suppressed.

According to a seventh aspect of the present invention, when the duct is formed in a rectangular shape, the structure of the duct is simplified, and the muffler can be easily manufactured. As set forth in claim 8, a microphone that picks up noise propagating in the duct portion,
By providing an inverting amplifier for inverting and amplifying the picked-up signal and a speaker for emitting the inverted and amplified noise into the duct unit in the muffler, and adding an active muffling function for muffling the noise in the duct by sound interference, The active silencer silences low-frequency components of noise that cannot be muffled very well with a passive silencer,
Further, the noise reduction efficiency can be improved. Further, by placing at least the microphone and the speaker in the base of the muffler, it is possible to prevent the range from affecting the function of discharging steam, oil smoke, and the like generated by the range. Further, a sound-passing hole for inputting sound to the microphone and outputting sound from the speaker and communicating with the duct portion is formed, and a sound-absorbing material that absorbs high-frequency sound is interposed between the sound-passing hole and the microphone and the speaker. Thus, the high-frequency component contained in the noise is absorbed by the sound absorbing material, the high-frequency sound is prevented from being picked up by the microphone, and the active noise reduction effect functions efficiently.

According to the eighth aspect of the present invention, as described in the ninth aspect, by providing a structure in which the sound absorbing material is not interposed between the microphone and the speaker, a phase delay is caused in sound propagation between the microphone and the speaker by the sound absorbing material. The active silence operation can be performed stably. In the invention of claim 8 or claim 9, claim 1
As shown in FIG. 0, the sound is emitted from the speaker by forming an expansion chamber communicating with the duct section through a sound passage hole at least on a surface of the base of the muffler opposite to the speaker, and storing the sound absorbing material in the expansion chamber. It is possible to reduce the reflection of the sound from the duct portion and efficiently perform the silencing operation of the active silencing function portion. Claims 8 to 10
In the invention according to any one of the above, as described in claim 11, by forming the sound passage hole in a slit shape long in the flow direction of the air flow in the duct portion, the resistance of the sound passage hole to the flow of the air flow is reduced. Thus, it is possible to reduce the wind noise of the sound passage hole.

In the invention according to any one of claims 8 to 10, as described in claim 12, the storage section for storing the speaker and the microphone or the storage section for storing the sound absorbing material is communicated with the duct section through an opening. By detachably attaching a filter that passes sound and collects oil to the opening, it is possible to prevent oil from adhering to a speaker, a microphone, or a sound absorbing material by the filter.

In the invention according to any one of the eighth to tenth aspects, as described in the thirteenth aspect, the speaker and the microphone are arranged on the same plane parallel to the duct part.
It is possible to prevent a phase delay in sound propagation between a microphone and a speaker, and to stabilize a muffling operation of an active muffling function unit. In the invention according to any one of claims 8 to 10, as described in claim 14, a speaker having a minimum diameter capable of emitting a particularly unpleasant low-frequency sound due to noise generated by a fan is provided. By using such a speaker, it is possible to reduce the weight and cost of the exhaust device by using a speaker that is light in weight and inexpensive.

In the invention according to any one of claims 8 to 10, as described in claim 15, the active muffling function unit is unnecessarily operated by operating the active muffling function unit in conjunction with the operation of the fan. To prevent from operating.

[0024]

【Example】

(Embodiment 1) An embodiment of the present invention will be described with reference to FIGS. In the exhaust device of the present embodiment, the fan 1 is installed vertically inside the hood portion 2, and the muffler 5 is built in the hood portion 2 below the fan 1. If the fan 1 is built in the hood part 2 as described above, the construction of the exhaust device can be easily performed.

A front panel 2a is provided at a portion of the hood 2 facing the front of the fan 1, and the front panel 2a
Can be opened and closed freely. That is, by providing the front panel 2a, the front panel 2a can be opened to remove oil stains and the like adhering to the inside of the hood portion 2, and the blades 1a of the fan 1 can be easily removed to cover the blades 1a. It is designed to remove oil stains and the like that have been deposited. Moreover, since the fan 1 is placed vertically, the blade 1a can be easily removed.

By the way, when the silencer 5 inside the hood portion 2 is provided as described above, it is necessary to make sure that the air sucked by the fan 1 passes through the silencer 5. Therefore, below the fan 1, in order to maintain a hermetic seal between the space above the hood portion 2 where the fan 1 is installed and the space below the silencer 5, and to prevent airflow and sound leakage from occurring. Panel 6 is attached. Note that the structure for maintaining the airtightness between the upper space and the lower space of the hood portion 2 is not necessarily limited to the structure using the panel 6.

Further, in this embodiment, FIG. 1 (b) shows the upper space of the hood 2 where the fan 1 is installed, which is divided by the panel 6.
Is larger than the cross-sectional area of the suction port 1b of the fan 1 and the cross-sectional area of the upper space of the hood section 2 in which the fan 1 is installed in FIG. It is formed so as to be larger than the cross-sectional area. By forming the upper space of the hood portion 2 in this manner,
This upper space functions as a so-called muffling room for an extended muffler.

When the silencer 5 is installed on the front side of the hood 2 as shown in FIG. 1B, an empty space is created in that direction. So, in this empty space,
The lighting equipment 7 and the like can be stored. When the silencing device 5 has an active silencing function, the control circuit 5b can be installed in the empty space.

In the case of this embodiment, as the exhaust device,
The hood section 2 collects steam and oil smoke emitted from a range or the like. Here, the oil contained in the collected steam or oil smoke is removed by the filter 4. The air from which oil has been removed in this way is sucked in by the fan 1 via the silencer 5 and exhausted outside through the exhaust duct 3.
That is, the original function of the exhaust device is performed in the same manner as the conventional one.

As described above, when exhausting steam or oil smoke emitted from a range or the like, noise generated by the rotation of the fan 1 is emitted from below the hood 2 through the silencer 5. However, in the case of the present embodiment, the noise can be effectively reduced by the function as the sound deadening chamber of the expanded sound deadener in the space above the hood part 2 and the sound deadening effect of the sound deadening device 5. For this reason, a standing wave is generated in the exhaust duct 3 and the load on the fan 1 is increased. Even if the noise is loud, the noise can be reduced to a level that does not substantially cause a problem.

Incidentally, this type of exhaust device is generally mounted on a wall 9 as shown in FIG. In such an installation situation, the muffler 5 is provided on the front side of the hood 2. Here, the position of the duct portion 5 a of the silencer 5 is set above the front portion of the range 10. In this way, the steam, oil smoke, and the like emitted from the range 10 installed below the hood portion 2 and placed on the range stand 11 or the like, for example, are removed from the hood portion as shown by arrows a and b in FIG. It is collected and sucked at 2. That is, steam, oily smoke, etc. generated in the front part of the range 10 are
Is sucked into the duct portion 5a of the silencer 5 located in front of the vehicle. Further, steam, oil smoke, and the like generated in the rear portion flow forward due to the influence of the wall 9. It is to be noted that such a flow is natural and does not occur as indicated by the arrow C in the broken line in the figure. That is, steam and oil smoke can be effectively collected over a wide range, and the efficiency of collecting steam and oil smoke can be improved.

The opening area S of the intake port 1b of the fan 1
₁And the cross-sectional area S of the duct portion 5a of the silencer 5_TwoBetween
Is S₁<S_TwoIt is preferable to have the following relationship. Toes
The cross-sectional area S of the duct portion 5a of the silencer 5_TwoThe fan
Opening area S of the intake port 1b ₁Larger than
The air intake capacity of fan 1 can be fully exhibited, and exhaust
The suction efficiency of the device can be improved.

When the silencer 5 is an active silencer for silencing by sound interference, the upper limit of the size of the cross-sectional area S ₂ of the duct 5a is limited by the fact that the noise passing through the duct 5a is The size can be performed. (Embodiment 2) FIG. 5 shows another embodiment of the present invention. This embodiment is basically the same as the first embodiment. The feature of the present embodiment is that a panel 8 that divides the upper and lower spaces of the hood portion 2 into two is used, and the muffler 5 is also detachable. On the point.

The panel 8 has a portion corresponding to the panel 6 of the first embodiment for closing the lower position of the fan 1 and a portion for accommodating the muffling device 5, and this portion communicates with the air passage 5a of the muffling device 5. Opening 8a is formed. The structure of the panel 8 is not particularly limited as long as it can prevent airflow and sound leakage in the upper and lower spaces except for the opening 8a and can support the muffler 5.

As described above, if the silencer 5 is also detachable, oil stains and the like adhering to the silencer 5 can be removed. It goes without saying that other noise reduction effects can be obtained in the same manner as in the first embodiment. (Embodiment 3) FIG. 6 shows still another embodiment of the present invention.
In this embodiment, a sound absorbing material 13 such as glass wool is attached to a portion corresponding to the front surface of the fan 1 inside the hood portion 2.

When the sound absorbing material 13 is attached to the inside of the front surface of the hood portion 2 as described above, the noise of the fan 1 is reduced as shown in FIG.
As shown by the arrow A in the middle, the sound directly strikes the sound absorbing material 13.
Therefore, noise can be efficiently absorbed. When the sound absorbing material 13 is installed in this manner, the noise reducing effect of the sound absorbing material 13 is added to the noise reduction effect as an extended silencer in the upper space of the hood portion 2, which greatly contributes to a reduction in noise level.

By the way, inside the hood portion 2, steam, oily smoke, and the like take a flow shown by an arrow A in FIG. 6B. That is, the flow shown by the arrow B in the figure is not taken.
Therefore, oil stains on the sound absorbing material 13 hardly occur. (Embodiment 4) FIG. 7 shows another embodiment of the present invention, which is characterized in that the upper part of the duct portion 5a of the silencer 5 projects from the upper surface of the silencer 5. .

When the upper portion of the duct portion 5a is protruded from the upper surface of the silencer 5, the length of the duct portion 5a becomes longer, and the noise attenuation efficiency increases.
Is a passive type, the noise reduction effect is improved. In addition, even in the case of the active type, the noise reduction effect can be improved. Further, the duct portion 5a is
Projecting from the upper surface of the muffler 5, it is possible to prevent oil or the like adhering to the upper surface of the muffler 5 from being transmitted to the duct portion 5a and flowing down. In addition, it is preferable that the projecting portion of the duct portion 5a can be removed because the muffler 5 can be easily cleaned.

(Embodiment 5) FIG. 8 shows still another embodiment of the present invention. In this embodiment, the lower portion of the duct portion 5a is tapered so that its diameter is enlarged downward. The tapered portion is indicated by 5c in the figure. When the lower portion of the duct portion 5a is tapered in this manner, the turbulence of the airflow generated at the lower end opening of the duct portion 5a can be reduced, and the generation of wind noise can be reduced. Further, the flow of the airflow flowing into the duct portion 5a becomes smooth, and the suction efficiency of the exhaust device can be improved. In particular, when the silencer 5 is of the active type, unnecessary wind noise does not enter the pickup microphone that picks up noise, and the active silence operation can be improved.

(Embodiment 6) FIG. 9 shows a case where the cross section of the duct portion 5a of the silencer 5 is rectangular.
This is an embodiment in which the assembling workability is improved. In addition, in the case of this silencer 5, as shown in FIG.
By making the lower part of a a tapered portion 5c, the generation of wind noise is reduced.

(Embodiment 7) FIG. 10 shows a further enhanced silencing function of the silencing device 5, in which the diameter of the upper part of the duct 5a is increased.
The sound absorbing member 14 is attached to the fixed cylinder 5d, and a fixed cylinder 5f having a plurality of sound passage holes 5e is fitted to the enlarged diameter portion 5d. Note that the fixed cylinder 5f may be formed integrally with the base of the muffler 5.

In this silencer 5, the duct portion 5a is straight for the flow of air, so that steam, oily smoke, etc. can flow without any difference from the conventional one. However, acoustically, the enlarged diameter portion 5d communicates through the sound passage hole 5e, so that the enlarged diameter portion 5f functions as an acoustic expansion chamber. Moreover, the noise generated by the fan 1 is absorbed by the sound absorbing material 14. Therefore, noise can be effectively reduced.

Here, the cross-sectional area of the duct portion 5a needs to be larger than the intake port 1b of the fan 1 in consideration of the suction efficiency of the exhaust device. A typical sirocco fan 1b generally used as the fan 1 includes an intake port 1
b is a circle of φ180 (the cross-sectional area is π × (18
0/2) ² ). Therefore, the sectional area of the duct portion 5a is 1.5
In this case, the size of the duct portion 5a may be, for example, about 95 × 410 mm. Needless to say, this dimensional relationship is not particularly limited.

Although the sound absorbing material 14 is used in the above-described case, a noise reduction effect can be expected only with the enlarged diameter portion 5d. (Embodiment 8) FIG. 11 shows an active type silencer 5 in which an interference sound in the frequency band of the noise to be silenced is emitted from the speaker 15 and the noise is canceled out by the interference to perform the silence. Here, the interference sound emitted from the speaker 15 must satisfy the following plane wave condition. When the shape of the duct portion 5a is rectangular, the relational expression between the plane wave propagation limit frequency fc and the cross section is: fc = c / 2a [Hz] (1) 2a: long side length [m], c : Sound velocity (≒ 340 m / s), and when the shape of the duct portion 5a is rectangular, fc = 1.2197 × c / 2b (2) b: radius [m].

Therefore, in order to perform active silence sufficiently,
Requires that fc = about 1500 Hz
Has been experimentally confirmed, and as a result
When the shape of a is rectangular, the length of the long side is about 220
mm or less, and a circular one needs to have a diameter of about 270 mm or less. Note that the circular shape is advantageous in that the sectional area is increased. By the way, the muffling device 5 of the seventh embodiment.
The size of the duct 5a of 95 × 410 mm described in the above does not sufficiently satisfy the plane wave condition. For this reason, the duct portion 5a
Need to make the long side smaller.

For this reason, in the case of this embodiment, FIG.
As shown in (a) and (b), the middle of the duct portion 5a is partitioned by a partition plate 16. In this case, the cross-sectional area becomes 95 × 205 mm, and the above-mentioned plane wave condition can be sufficiently satisfied. Figure 12 shows the active extinguishing of circular ducts .
Sound device, showing a state of attaching the speaker 15 in the mounting plate 17 on both sides of the circular duct section 5a. The rectangular duck in FIG.
It can be seen that the rectangular shape is easier to assemble as compared with the active silencer . Also, speaker 1
A rectangular filter (not shown) provided on the front surface of the speaker 5 and preventing oil from adhering to the speaker 15 is easy to attach and detach, is easy to clean, and is practically advantageous.

FIG. 13A shows a specific configuration in the case where an active noise reduction function is added to the noise reduction device 5. The muffler 5 includes a microphone 20 that collects noise in the duct 5a,
Inverting amplifier 2 for inverting and amplifying the noise picked up by the microphone 20
1 and a speaker 15 that emits the noise inverted and amplified by the inverting amplifier 21 into the duct portion 5a. The silencing method of this active silencing function unit reduces noise and sound pressure by acoustic conductance, and the AAC (Active Acoustics) is used.
It is a method called ustic Conductance). This type of active silencer can effectively muffle low-frequency noise, which is difficult to mitigate with a passive silencer. Conversely, high-frequency noise is difficult to interfere with and has a low muffling effect. .

In the active noise reduction function section, a sound passage hole 23 is provided in the duct section 5a in order to collect noise in the duct section 5a and to emit inverted and amplified noise from the speaker 15. Then, the speaker 15 is attached to the mounting plate 17.
Speaker 1 mounted using a speaker and having a mounting plate 17 interposed
The microphone 20 is disposed near the microphone 5, and a sound absorbing material 22 made of glass wool or the like is interposed between the microphone 20 and the speaker 15 and the sound passage hole 23.

The reason why the sound absorbing member 22 is provided is to prevent the microphone 20 from picking up high frequency noise. This point will be described in more detail. The noise extends over a wide frequency band from low frequency to high frequency. The sound absorbing material 22
When there is no sound, the microphone 20 collects not only low-frequency sound but also high-frequency sound. In this case, if a high-frequency sound obtained by inverting and amplifying the high-frequency sound is generated from the speaker 15, it is difficult to cancel the high-frequency sound by interference, and on the contrary, the noise may increase.

Therefore, the high frequency sound is prevented from being picked up by the microphone 20 by interposing the sound absorbing material 22 as described above.
Noise can be effectively silenced. In this case, it is also useful for a howling prevention function. further,
The sound-absorbing material 22 is provided by the speaker 1 from the hot airflow passing through the duct 5a.
5 can also be expected to be effective. By the way, FIG.
In FIG. 2B, the thickness of the sound absorbing material 22 shown in FIG. When the thickness of the sound absorbing material 22 is large as shown in FIG. 13A, the sound absorbing material 22 is interposed between the microphone 20 and the speaker 15, and a phase lag occurs in the transfer characteristics between the two.
This may adversely affect the active silencing operation. Therefore, in FIG. 13B, the sound absorbing material 22 is not interposed between the microphone 20 and the speaker 15. The microphone 20 and the loudspeaker 15 may be formed using other methods in addition to making the sound absorbing material 22 thin as described above.
Needless to say, the sound absorbing material 22 may not be interposed between the two.

FIG. 14 shows still another muffler 5. In this silencer 5, the duct 5a has a rectangular cross section,
A sound absorbing material 24 made of glass wool or the like is arranged on a surface facing the speaker 15. Note that the storage portions of the sound absorbing material 24 and the speaker 15 are communicated with the duct portion 5a through the sound passage hole 23. By arranging the sound absorbing material 24 on the surface facing the speaker 15 in this way, it is possible to suppress the reflection of the interference sound emitted from the speaker 15 from the surface facing the duct portion 5a, and to remove the adverse effect due to the reflected sound.
The silencing effect can be improved. Also, the sound absorbing material 24
Absorbs the high-frequency sound included in the sound emitted from the speaker 15, thereby stabilizing the muffling operation. Further, when viewed from the airflow, the duct portion 5a is straight, but acoustically, the portion containing the sound absorbing material 24 functions as an expansion chamber, and a sound-muffling effect as an expansion-type muffler can be obtained.

FIG. 15 shows a case where the duct 5a is partitioned by the partition plate 16 when the cross-sectional area of the duct 5a is not large enough to satisfy the plane wave condition. FIG. 16A shows FIG.
15 shows a detailed configuration of the active type silencer 5 shown in FIG. 15, and FIG. Here, the sound passage hole 23 is formed by a slit parallel to the flow of the air current. That is, the slit 23a is vertically long. By doing so, the sound passage holes 23
The wind noise generated at the opening edge of the can be reduced,
The silencing operation of the active silencing function unit can be stabilized. The sound passage hole 23 also has a function of achieving acoustic impedance matching between the speaker 15 and the duct portion 5a.

By the way, the above-mentioned sound passage hole 23 is formed directly in the base of the silencer 5 as shown in FIG.
As shown in FIG.
5, and a mesh filter 26 may be detachably attached to the opening. Here, a metal grease filter for collecting oil is used as the filter 26. However, other filters may be used. That is, in the present embodiment, the filter 26 has the role of the sound passage hole 23, and at the same time, the speaker 15 and the sound absorbing material 24 are provided.
It also has the function of preventing oil from adhering to the surface. Here, if the filter 26 can be easily removed, the cleaning property is improved.

FIG. 17B shows the case where the above-described structure is applied to the case where the sound absorbing material 22 is also provided on the speaker 15 side. FIG. 18 is a diagram showing a mounting structure of the speaker 15 and the microphone 20. The speaker 15 is mounted on the rear side of a portion where the opening 17a of the mounting plate 17 is formed, and the microphone 20 is mounted by being fitted into the mounting plate 17. ing.
In addition, the vibration-proof rubber 27 is fitted around the microphone 20,
The vibration of the speaker 15 is not picked up by the microphone 20. FIG. 19A shows a state in which the anti-vibration rubber 27 is fitted to the microphone 20, and FIG. 19B shows the microphone 20 and the anti-vibration rubber 27 individually.

Here, as shown in FIG.
Is arranged near the speaker 15 so that the microphone 2
It is expected that the phase delay between 0 and the speaker 15 is suppressed, the silencing effect can be improved, howling can be prevented, and a stable silencing operation can be performed.
Further, since the microphone 20 and the speaker 15 are mounted on the same mounting plate 17, there is also an advantage that the production becomes easy.

The microphone 20 is mounted on the mounting plate 17 by using the vibration isolating rubber 28 having the structure shown in FIG.
The anti-vibration measures of the microphone 20 may be strengthened. By the way, as shown in FIG.
In the case of using the mm type, the noise reduction effect appears in a frequency band of about 100 to 400 Hz as shown in FIG. Here, when the speaker 15 having a larger diameter is used, the low frequency characteristic of the speaker 15 itself is further improved, so that the muffling effect can be obtained even in a frequency band of 100 Hz or less. That is, a speaker 1 having a large diameter
The more the number 5 is used, the better the noise reduction effect can be expected.

However, the speaker 15 having a large diameter
However, since the weight of the silencer is very large, it leads to an increase in the weight of the silencer and also increases the cost. FIG. 21D shows the noise reduction characteristics when the speaker 15 having a diameter of 80 mm shown in FIG. 21C is used. Diameter 80mm
Compared to the case where the speaker 15 having a diameter of 160 mm is used, the volume at around 100 Hz is smaller.

However, with respect to the noise emitted from the fan 1, a sufficient noise reduction effect can be obtained even with the speaker 15 having a diameter of 80 mm, and the speaker 15 having a diameter of 160 mm can be heard.
Almost no difference was observed. That is, in the case of an exhaust device that exhausts steam, oil smoke, and the like generated by the range using the fan 1, the speaker 15 having a diameter of 80 mm is sufficient. Moreover, by using such a small speaker 15, a significant reduction in weight and cost can be achieved. In other words, by removing the silencing function up to an unnecessarily low frequency range, a more practical silencing device 5 can be obtained. Note that the diameter of the speaker 15 is not limited to 80 mm, and the diameter of the speaker 15 to be used is not limited to 80 mm as long as the level of the frequency band that requires silencing can be reduced to some extent sufficiently. For example, a speaker 15 of 120 mm or less can be used.

(Embodiment 9) FIG. 22 shows still another embodiment of the present invention. In this embodiment, the operation switch 3 of the operation unit 29 for operating the fan 1
The configuration is such that the amplification factor of the inverting amplifier 21 is adjusted in conjunction with turning on and off of 0 . That is, when the operation of the fan 1 is stopped, the gain of the inverting amplifier 21 is set to 0 by a built-in control unit (not shown) of the operation unit 1 to substantially stop the operation of the active noise reduction function unit. . Then, the operation of the active type silencer 5 is performed only when the fan 1 is operating. The power supply to the inverting amplifier 21 may be stopped to stop the operation of the active noise reduction function unit.

By doing so, the active silence operation can be stopped except when the exhaust device is used, and it is possible to prevent the occurrence of accidental howling.
5 can be expected to have an effect of extending the life. By the way, since the noise of the fan 1 increases during the strong operation, the active silencer may be operated in conjunction with the operation of the strong operation switch 29c . The operation of the fan 1 can be switched between the weak operation and the medium operation by the switches 29a and 29b .

The configurations described with reference to FIGS. 8, 9, 13 to 18, and 21 may be applicable to devices other than the hood-equipped exhaust device described above.

[0062]

According to the first aspect of the present invention, as described above, the cross-sectional area of the upper space is larger than the cross-sectional area of the intake port of the fan and the cross-sectional area of the duct of the silencer. The space can function as a so-called muffling room for a so-called extended muffler, and can muffle fan noise. Further, since the muffler is provided, the noise of the fan can be effectively muffled in combination with the muffler function of the upper space. In addition, the fan is placed vertically in the upper space of the hood with the suction direction as the horizontal direction, and a front panel that can be opened and closed is provided on the opposite surface of the fan of the hood, so open the front panel and open the fan. And the upper space can be easily cleaned.

According to a second aspect of the present invention, when the muffler is disposed at the front of the hood, steam, oily smoke, etc. generated at the front of the range can rise up to the position of the duct of the muffler. Since the exhaust device targeted by the present invention is usually mounted on a wall surface, steam and oil smoke generated at the rear part of the range can be efficiently collected by the wall surface and the hood portion. Can improve the collection efficiency.

When the sectional area of the duct portion of the silencer is made larger than the sectional area of the intake port of the fan, the intake capacity of the fan is sufficiently exhibited and the suction efficiency of the exhaust device is increased. be able to. According to a fourth aspect of the present invention, when a sound absorbing material is attached to the opposite surface of the hood portion in the intake direction of the fan, noise from the fan can be directly absorbed by the sound absorbing material, and noise generated by the fan can be reduced. In combination with the noise reduction effect, the noise reduction effect can be further improved.

According to a fifth aspect of the present invention, when the duct portion of the muffling device is protruded from the upper surface, the length of the duct portion can be increased to improve the muffling effect, and adhere to the upper surface of the muffling device. The oil can be prevented from entering the duct, and the oil can be prevented from flowing down through the duct. According to a sixth aspect of the present invention, when the intake side of the duct portion is formed in a tapered shape in which the diameter is increased downward, air can smoothly flow into the duct portion, and generation of wind noise can be reduced.

According to a seventh aspect of the present invention, when the duct is formed in a rectangular shape, the structure of the duct is simplified, and the muffler can be easily manufactured. According to an eighth aspect of the present invention, a microphone that collects noise propagating in the duct, an inverting amplifier that inverts and amplifies the collected signal, and a speaker that emits the inverted and amplified noise into the duct are provided in the muffler. The active silencer has an active silencer function that silences the noise in the duct due to sound interference.The active silencer suppresses low-frequency components of noise that cannot be muffled with a passive silencer. In addition, the silencing efficiency can be further improved. Further, since at least the microphone and the speaker are housed in the base of the muffler, there is no effect on the function of discharging steam or oil smoke generated by the range. Furthermore, a sound-absorbing material that absorbs high-frequency sound is formed between the sound-passing hole, the microphone, and the speaker by forming a sound-passing hole that communicates with the duct part by inputting sound to the microphone and outputting sound from the speaker. Therefore, the high frequency component contained in the noise is absorbed by the sound absorbing material, and the high frequency sound can be prevented from being picked up by the microphone, so that the active noise reduction effect can be made to function efficiently. According to the eighth aspect of the present invention, by providing a structure in which the sound absorbing material is not interposed between the microphone and the speaker, a phase delay is caused in sound propagation between the microphone and the speaker by the sound absorbing material. Can be prevented, and the active silencing operation can be performed stably.

In the invention of claim 8, as in claim 10, an expansion chamber communicating with the duct portion through a sound passage hole is formed on at least a surface of the base of the muffler that faces the speaker. By containing the sound absorbing material, the reflection of the sound emitted from the speaker from the duct portion can be reduced, and the noise reduction operation of the active noise reduction function portion can be efficiently performed.

In the invention according to any one of the eighth to tenth aspects, as described in the eleventh aspect, the sound passage hole is formed in a slit shape that is long in a flow direction of the airflow in the duct portion, thereby providing a sound. The resistance of the passage hole to the flow of air current is reduced, and the wind noise of the sound passage hole can be reduced. In the invention according to any one of claims 8 to 10, as set forth in claim 12, the storage section for storing the speaker and the microphone or the storage section for storing the sound absorbing material communicates with the duct section through the opening, and By detachably attaching a filter that passes sound and collects oil, the filter can prevent oil from adhering to a speaker, a microphone, or a sound absorbing material. Since the filter is detachably attached to the opening, the filter can be replaced.

In the invention according to any one of the eighth to tenth aspects, as described in the thirteenth aspect, the speaker and the microphone are arranged on the same plane parallel to the duct part.
A phase delay in sound propagation between the microphone and the speaker can be prevented, and the muffling operation of the active muffling function unit can be stabilized. In the invention according to any one of claims 8 to 10, as described in claim 14, a speaker having a minimum diameter capable of emitting a particularly unpleasant low-frequency sound due to noise generated by a fan is provided. By using
By using a speaker that is light in weight and inexpensive as the speaker, the weight of the exhaust device can be reduced, and the cost can be reduced.

In the invention according to any one of claims 8 to 10, as described in claim 15, the active muffling function unit is unnecessarily operated by operating the active muffling function unit in conjunction with the operation of the fan. Can be prevented from operating. This can prevent howling from occurring and prolong the life of the speaker.

[Brief description of the drawings]

1 (a) and 1 (b) are a perspective view and a sectional view showing a structure of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a method of cleaning a fan.

FIG. 3 is an explanatory diagram showing a suction state of steam, oil smoke, and the like emitted from a range.

FIG. 4 is an explanatory diagram showing a relationship between a cross-sectional area of an intake port of a fan and a cross-sectional area of a duct portion of a muffler.

FIG. 5 is an explanatory view showing the structure of the embodiment when the muffling device is made detachable.

FIGS. 6A and 6B are explanatory views of the structure and effects of still another embodiment.

FIG. 7 is a cross-sectional view of another embodiment.

FIG. 8 is a sectional view of still another embodiment.

FIGS. 9A and 9B are a perspective view and a cross-sectional view of a muffler of another embodiment.

FIG. 10 is a cross-sectional view showing a silencer having another structure.

FIGS. 11 (a) to 11 (c) are a perspective view, a plan view of a silencer, and a front view of a silencer of still another embodiment.

[12] (a), (b) is a front view and a plan view <br/> showing a mounted state of the speaker to the silencing apparatus having a duct portion of the circular shape.

FIGS. 13A and 13B are explanatory views showing the structure of an active type silencer, respectively.

14A and 14B are a front view and a plan view showing the structure of an active type silencer having another structure.

FIG. 15 is a plan view showing a structure of an active type silencer in which a duct portion is divided into two by a partition plate.

FIG. 16 is a specific configuration diagram of the active type silencer of FIGS. 14 and 15, and a partial front view showing a specific structure of a sound passage hole.

17] (a), (b) is a positive showing the essential structure of the case comprising a case having no sound absorbing material to each speaker side
FIG .

FIGS. 18 (a) and (b) are a front view and a side cross-sectional view showing a mounting state of a speaker and a microphone on a mounting plate.

FIG. 19A is a perspective view showing a state where a vibration isolating rubber is attached to the microphone, and FIG. 19B is a perspective view showing the microphone and the vibration isolating rubber individually.

FIG. 20 is a side cross-sectional view showing a state where a speaker and a microphone are mounted on a mounting plate by another method.

21A is a front view of a mounting plate provided with a large-sized speaker, FIG. 21B is a characteristic diagram showing the noise reduction characteristics of FIG. 21A, and FIG.
FIG. 4 is a front view of a mounting plate provided with a small speaker, and FIG. 4D is a characteristic diagram showing the noise reduction characteristic of FIG.

FIG. 22 is an explanatory diagram illustrating a configuration of an exhaust device including a control unit.

FIG. 23 is an explanatory view showing the structure of a conventional exhaust device.

[Explanation of symbols]

 Reference Signs List 1 fan 1b intake port 2 hood section 2a front panel 3 exhaust duct 5 silencer 5a duct section 5c taper section 9 wall 13 sound absorbing material 15 speaker 20 microphone 21 inverting amplifier 22, 24 sound absorbing material 23 sound passing hole 25 opening 26 filter

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F24F 7/06 101 G10K 11/16

Claims (15)

(57) [Claims] 1. A hood disposed above a range collects steam and oil smoke emitted from the range, and a fan such as a sirocco fan sucks steam and oil smoke through the hood portion through an exhaust duct. In the exhaust system that exhausts outdoors, the inside of the hood is divided into two vertical spaces, and a silencer with a duct structure is installed at the boundary,
The fan is placed vertically in the upper space of the hood with the suction direction as the horizontal direction, and a front panel that can be opened and closed is provided on the opposite surface of the fan of the hood, the cross-sectional area of the fan inlet and the duct of the silencer An exhaust device wherein the cross-sectional area of the upper space is larger than the cross-sectional area of the portion. 2. The exhaust device according to claim 1, wherein the muffler is disposed at a front portion inside the hood. 3. The exhaust device according to claim 1, wherein a cross-sectional area of the duct portion of the muffler is made larger than a cross-sectional area of an intake port of the fan. 4. The exhaust device according to claim 1, wherein a sound absorbing material is attached to an opposite surface of the hood portion in a suction direction of the fan. 5. The exhaust device according to claim 1, wherein a duct portion of the silencer is projected from an upper surface. 6. The exhaust device according to claim 1, wherein the intake side of the duct portion is formed in a tapered shape in which the diameter of the intake portion is increased downward. 7. The exhaust device according to claim 1, wherein the duct is formed in a rectangular shape. 8. A muffler comprising: a microphone for picking up noise propagating in the duct, an inverting amplifier for inverting and amplifying the picked-up signal, and a speaker for emitting the inverted and amplified noise into the duct; Adds an active noise reduction function to mitigate noise in the duct by sound interference. At least a microphone and a speaker are housed in the body of the muffler, and sound is input to the microphone and output from the speaker to communicate with the duct. 8. The exhaust device according to claim 1, wherein a sound-absorbing material that absorbs high-frequency sound is interposed between the sound-passing hole and the microphone and the speaker. 9. The exhaust device according to claim 8, wherein the exhaust device has a structure in which the sound absorbing material is not interposed between the microphone and the speaker. 10. An expansion chamber communicating with a duct portion through a sound passage hole at least on a surface of the base of the muffler facing the speaker, and a sound absorbing material is housed in the expansion chamber. The exhaust device according to claim 8 or 9. 11. The exhaust device according to claim 8, wherein the sound passage hole is formed in a slit shape that is long in a flow direction of the airflow in the duct portion. 12. The speaker and microphone accommodating portion or the accommodating portion accommodating the sound absorbing material is communicated with the duct portion through an opening, and a filter for passing sound is detachably attached to the opening. 8 to 10
The exhaust device according to any one of the above. 13. The speaker according to claim 8, wherein the speaker and the microphone are arranged on the same plane parallel to the duct.
The exhaust device according to claim 10. 14. The speaker according to claim 8, wherein said speaker has a minimum diameter capable of emitting a particularly unpleasant low-frequency sound due to noise generated by a fan. The exhaust device according to any one of the above. 15. The exhaust device according to claim 8, wherein the active silencer is operated in conjunction with the operation of a fan.