JPH07334163A - Noise decreasing device - Google Patents

Abstract

PURPOSE:To obtain a noise decreasing device which lowers the output sound pressure level of the noises generated when an apparatus is operated. CONSTITUTION:This noise decreasing device for decreasing the noises within the apparatus which radiates the noises has a first resonance chamber 7 which is disposed on a motor 5 side, i.e., a noise source and a prescribed resonance frequency band, a first filter 11 which is disposed to face the motor 5 so as to form the first resonance chamber 7 and has plural pieces of cylindrical open holes 13, a second resonance chamber 8 which is different in resonance frequency band from the first resonance chamber 7 and a second filter 12 which is disposed to have a prescribed spacing from the first filter 11 so as to form the second resonance chamber 8 and has plural pieces of cylindrical open holes 15 of the diameter different from the diameter of the cylindrical open holes 13 of the first filter 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a countermeasure device for reducing the output sound pressure level of noise generated from equipment.

[0002]

2. Description of the Related Art FIG. 13 is a sectional view of a main body of a known vacuum cleaner. In FIG. 13, reference numeral 51 denotes a vacuum cleaner casing, and 52
Is a dust collecting part in the vacuum cleaner, 53 is a dust filter, 54 is a dust collecting motor for absorbing dust, 55 is a vibration isolator fixed around the dust collecting motor 54, 56 is an exhaust port, 57 is a pipe, Reference numeral 58 is a brush surface. In this conventional vacuum cleaner, a fan (not shown) fixed to the dust collecting motor 54.
The suction operation occurs with the rotation of the
The dust is sucked from the brush surface 58 and passes through the pipe 57 to collect the dust.
Collected in 2. The noise radiated from the dust collecting motor 54 and the airflow generated by the fan are discharged from the exhaust port 56 to the outside of the casing 51 of the cleaner.

14 and 15 show a known silencer, FIG. 14 shows a cavity silencer, and FIG. 15 shows a resonance silencer. 14 and 15 both show a muffler utilizing the resonance phenomenon. In the figures, 60 is a suction part, 61 is a discharge part, 6
Reference numeral 2 is a cavity portion, and 63 is a resonance portion. With this silencer,
The noise that has passed through the suction unit 60 is transmitted to the cavity 62 or the resonance unit 6
It is reduced by utilizing the resonance phenomenon of No. 3 and is discharged from the discharge unit 61 to the outside of the silencer.

FIG. 16 shows a silencer disclosed in Japanese Utility Model Laid-Open No. 2-134599, in which a silencer using an acoustic lens is applied to an exhaust port of an automobile. FIG.
In the figure, an arrow (→) is a flow of exhaust gas, 64 is a cylindrical body, 65 is an exhaust introduction cylinder, 66 is an acoustic lens, 67 is a sound absorbing material, and 68 is an exhaust discharge cylinder. In this silencer, the acoustic energy of the exhaust gas introduced from the exhaust introduction tube 65 is once focused by the acoustic lens 66, and the focused acoustic energy is absorbed by the sound absorbing material 67 arranged at the focusing point. The acoustic energy that could not be absorbed at one time is attenuated by passing through the portion having the same configuration several times, and the attenuated acoustic energy is discharged from the exhaust pipe 68.

FIG. 17 and FIG. 18 show the actual Kaihei 3-33499.
17 is a plan view and FIG.
8 is a longitudinal sectional view. In the figure, 70 is a silencer body,
71 is an exhaust port, 72 is a ventilation hole, 73 is a housing, 74 is a fan, and 75 is an expansion chamber. In this silencer, the noise of the fan 74 fixed to the housing 73 is introduced into the expansion chamber 75 through the ventilation holes 72. The noise of the introduced fan 74 is reduced by utilizing the resonance phenomenon of the expansion chamber 75, and is discharged to the outside from the discharge port 71.

[0006]

Conventionally, a device for reducing noise radiated from a motor is rarely provided inside the vacuum cleaner shown in FIG. 13, and a vibration isolator or the like is fixed to the motor itself. Therefore, the mainstream idea was to consider noise generated by vibration as a countermeasure. Therefore, the acoustic energy of the sound propagating in the space cannot be taken as a countermeasure, and it is directly discharged from the exhaust port.

With regard to the known silencer shown in FIGS. 14 and 15, the noise reduction characteristic is determined by the volume of the cavity 62 of the silencer and the conditions such as the diameter and length of the suction portion 60. Since it has a steep curve attenuation characteristic with a frequency peak, there is a problem that the sound reduction effect is significantly reduced if it deviates a little from the resonance frequency. For this reason, in order to expect a noise reduction effect over a wide band, it is necessary to combine a large number of silencers, which results in a large structure. The structure of the silencer shown in FIGS. 17 and 18 is an example in which the known silencer shown in FIGS. 14 and 15 is used. As in the conventional example, the structure becomes large, and home appliances It was impossible to use it for relatively small devices such as products. Further, the end surfaces of the suction portion 60 of FIGS. 14 and 15 and the ventilation hole 72 of FIG. 17 have an acute angle, and in the case of noise accompanied by airflow, turbulence occurs at the acute angle portion, and the acoustic energy of noise is reduced. On the contrary, there is a problem of amplification.

In the structure of the silencer shown in FIG. 16, the acoustic design of the acoustic lens and the like is complicated, and there is a problem that the acoustic lens needs to be long in order to cope with the acoustic energy in the low frequency range. In order to reduce the noise in consideration of the range, the length of the silencer itself becomes long as a result.
In addition, the structure itself is very complicated, and the manufacturing cost is high. Further, in the case of noise accompanied by airflow, the acoustic lens portion may resonate, and an acoustic characteristic in which a certain frequency band is projected may occur.

As described above, in the conventional noise reduction device,
It is clear that the noise reducing device itself has a complicated shape and becomes large in size, and in order to configure the noise reducing device, it is necessary to newly form a space and a shape for accommodating the device. Further, in the case of noise accompanied by airflow, the shape of the device for reducing the noise itself may cause resonance or turbulence and further increase the noise.

The present invention has been made in order to solve the above-mentioned problems, and is small in size without changing the structure of the device itself, and the output sound pressure level of noise generated when the device is operated can be reduced. The purpose is to obtain a noise reduction device that reduces the noise.

[0011]

A noise reduction device according to a first aspect of the invention has the following elements. (A) a first resonance chamber provided on the noise source side and having a predetermined resonance frequency band; (b) a plurality of cylindrical shapes provided to face the noise source so as to form the first resonance chamber. A first filter having an open hole, (c) a second resonance chamber having a resonance frequency band different from that of the first resonance chamber, and (d) a predetermined resonance with the first filter so as to form the second resonance chamber. A second filter having a plurality of cylindrical open holes provided at intervals and having a diameter different from that of the first filter.

In the noise reducing device according to the second aspect of the present invention, the open hole of the first filter is formed in a cylindrical shape whose inner peripheral wall is a drum-shaped curved surface, and the open hole of the second filter is The inner peripheral wall is formed in a cylindrical shape having a drum-shaped curved surface.

In the noise reducing device according to the third aspect of the invention, the open hole of the first or second filter is formed in a truncated cone shape having a large opening diameter on the noise source side.

A noise reduction device according to a fourth aspect of the invention has the following elements. (A) a first resonance chamber provided on the noise source side and having a predetermined resonance frequency band; (b) a plurality of cylindrical shapes provided to face the noise source so as to form the first resonance chamber. A first filter having an open hole, (c) a sound having a plurality of cylindrical open holes at arbitrary positions on the peripheral wall, and having a tubular space inside which guides noise from the open hole of the first filter. A pipe, (d) a closed space surrounding the sound pipe, and (e) a plurality of cylinders provided on the noise outlet side of the sound pipe and having a diameter different from the cylindrical open hole of the first filter. Second filter having a circular open hole.

According to a fifth aspect of the present invention, there is provided a noise reduction device in which the sound passage tube is formed in a shape bent to the bottom surface side.

A noise reducing device according to a sixth aspect of the present invention is such that the open hole of the first filter is formed in a cylindrical shape whose inner peripheral wall is a drum-shaped curved surface.

In a noise reducing device according to a seventh aspect of the invention, the open hole of the first filter is formed in a truncated cone shape having a large opening diameter on the noise source side.

A noise reduction device according to an eighth aspect of the invention has the following elements. (A) A labyrinthine sound tube in which a closed space having an entrance and exit is formed in a labyrinth type, and the entrance is arranged so as to face the noise source side; A filter with one cylindrical open hole.

[0019]

In the noise reduction device according to the first aspect of the present invention, the noise generated in the device is attenuated by the resonance phenomenon of the first resonance chamber in the low range of the acoustic characteristics thereof, and the noise of the plurality of the first filters is reduced. High frequencies are attenuated when passing through the cylindrical open hole. Next, when the low frequency range which has not been attenuated in the first resonance chamber is attenuated by the resonance phenomenon in the second resonance chamber and passes through the plurality of cylindrical open holes of the second filter, The high frequencies that were not attenuated by the cylindrical open hole of the filter are attenuated and discharged to the outside of the equipment.

In the noise reduction device according to the second aspect of the invention, the cylindrical open hole provided in the first filter and having an inner peripheral wall with a drum-shaped curved surface has a high range of acoustic characteristics of noise generated in the device. Attenuates, and reliably prevents turbulence generated at the end of the open hole when passing noise accompanied by air flow,
Let the air flow smoothly.

In the noise reducing device according to the third aspect of the present invention, a frustoconical opening hole provided in the first or second filter and having a large opening diameter on the noise source side causes noise generated in the device. Attenuating the high range of the acoustic characteristics, the turbulent flow generated at the end of the open hole at the time of the passage of the noise accompanied by the air flow is surely prevented, and the air flow smoothly flows.

In the noise reduction device according to the fourth aspect of the present invention, the noise generated in the equipment is attenuated by the resonance phenomenon of the first resonance chamber in the low range of the acoustic characteristics thereof, and the noise of the plurality of the first filters is reduced. High frequencies are attenuated when passing through the cylindrical open hole. Next, the low frequency range which is not attenuated in the first resonance chamber is attenuated by the resonance phenomenon in the sound guide tube, and becomes high when passing through the cylindrical open hole provided at an arbitrary position on the peripheral wall of the sound guide tube. The range is attenuated, and the low range is attenuated in the closed space surrounding the sound pipe. When passing through the plurality of cylindrical open holes of the second filter, the high region that remains without being attenuated is attenuated,
It is discharged to the outside of the equipment.

In the noise reduction device according to the fifth aspect of the invention, the low range of the acoustic characteristics of the noise generated in the device is attenuated by the resonance phenomenon in the sound pipe having the shape bent to the bottom side, and the noise after attenuation is reduced. Is discharged downward.

In the noise reducing device according to the sixth aspect of the present invention, the cylindrical open hole provided in the first filter and having an inner peripheral wall with a drum-shaped curved surface has a high acoustic characteristic range of noise generated in the device. Attenuates, and reliably prevents turbulence generated at the end of the open hole when passing noise accompanied by air flow,
Let the air flow smoothly.

In the noise reduction device according to the seventh aspect of the present invention, the frustoconical opening hole provided in the first filter and having a large opening diameter on the noise source side has acoustic characteristics of noise generated in the device. In addition to dampening the high frequency range, the turbulent flow generated at the end of the open hole when the noise accompanied by the air flow passes is surely prevented, and the air flow smoothly flows.

In the noise reduction device according to the eighth aspect of the invention, the noise generated in the device causes distance attenuation when passing through the maze type sound tube, and the high frequency range is attenuated by the cylindrical open hole of the filter. , Discharged outside the equipment.

[0027]

【Example】

Example 1. 1 is a partial side sectional view of a noise reduction device according to a first embodiment of the present invention used in a cleaner body.
1 is a plan sectional view of FIG. 1, FIG. 3 is a rear view of FIG. 1, and FIG.
FIG. 5 is a partially enlarged cross-sectional view of an acoustic filter portion that is a constituent member of the noise reduction device, and FIG. 5 is a characteristic diagram showing an example of a noise reduction effect of the cleaner.

In the figure, 1 is the main body of the vacuum cleaner, 2 is the upper part of the vacuum cleaner 1, 3 is the rear part of the vacuum cleaner 1, 4 is the internal space of the vacuum cleaner 1, and 5 is an arbitrary position of the internal space 4. It is a motor that is installed and serves as a noise source, and is rotating at high speed in order to perform the suction operation of the cleaner 1. The rotation operation of the motor 5 is controlled so as to move according to the operation mode of an operation switch section (not shown) provided on the hose for sucking dust.

Reference numeral 6 is the bottom surface of the vacuum cleaner 1, 7 and 8 are sound path space portions having resonance frequencies different from each other due to the difference in volume, 1
Reference numeral 0 denotes an acoustic filter portion provided to face the noise source. In the first embodiment, the acoustic filter portion 10 is composed of two filters, a filter 11 and a filter 12, and the two filters 11 and 12 are sound paths. The spaces 7 and 8 are arranged at predetermined intervals at positions that define the volumes. In the first embodiment, the volume of the sound path space 7 is set to be larger than the volume of the sound path space 8.

Reference numeral 13 is an open hole having a resonance function, and a plurality of holes are opened at arbitrary positions of the filter 11 in a cylindrical shape. The inner peripheral wall 14 of the cylindrical open hole 13 has an hourglass-shaped curved surface shape as shown in an enlarged manner in FIG. 4, and the radius of curvature of this curved surface is preferably 15 mm to 21 mm according to experimental results. Reference numeral 15 is an open hole having a resonance function, and a plurality of holes are opened in a cylindrical shape at an arbitrary position of the filter 12. The inner peripheral wall 16 of the cylindrical open hole 15 has a drum-shaped curved surface shape as shown in FIG. 4, and the radius R of this curved surface is also 15
mm to 21 mm is desirable. The open holes 13 and 15 have different diameters so as to have different resonance frequencies in order to reduce noise in different frequency bands. In the first embodiment, the total volume of the open holes 13 is larger than the total volume of the open holes 15. Reference numeral 17 denotes wheels required when the cleaner 1 moves.

The arrow (→) in FIG. 1 indicates the spatial radiation / propagation direction (vector map) of the sound generated inside the vacuum cleaner 1. The noise generated by the rotational movement of the motor 5 is reduced by the muffling mechanism, and the reduced noise is the vacuum cleaner 1.
It is discharged to the outside of the vacuum cleaner 1 from the back portion 3 of the.

The noise reduction device according to the first embodiment is configured as described above, but its basic structure is that the filter 11 having a plurality of cylindrical opening holes 13 and a plurality of cylindrical opening holes. The filter 12 having 15 is provided in the internal space portion 4 of the vacuum cleaner 1, and the sound passage space portions 7 and 8 are formed.

Next, the operation of the noise reduction device according to the first embodiment will be described in detail. The user of the cleaner 1 selects the operation mode required for the rotation operation (suction operation) of the motor 5 to rotate the motor 5 and perform the work required for the cleaner 1. With the rotation of the motor 5, noise is generated in synchronization with the rotation of the motor 5. This noise is first radiated to the sound path space 7 adjacent to the motor 5, and the acoustic energy of the noise is converted into vibration energy, heat energy, etc. according to the volume of the sound path space 7. Or the low-frequency component is canceled by the reflection of the wall portion of the filter 11 and the wall surface of the sound path space portion 7, and the low-frequency component is canceled, so that the sound pressure level related to the low-frequency component of the cleaner noise is attenuated. Is performed as the first stage. In the first stage, the sound pressure level mainly related to 350 to 550 Hz is attenuated.

Next, the cleaner noise radiated to the sound path space 7 passes through the open hole 13 provided in the filter 11. When passing, the noise is rectified once by the drum-shaped inner peripheral wall 14 formed in the opening hole 13. Further, although the resonance phenomenon occurs in the open hole 13, by causing resonance with the high frequency band of the cleaner noise that matches the diameter and volume,
An antiphase component of the high frequency component of the noise is created while passing through the open hole 13, and the high frequency component is canceled when leaving the open hole 13, so that the sound pressure level related to the high frequency component of the cleaner noise is reduced. Damping takes place as the second stage. In the second stage, mainly 1
Attenuates the sound pressure level related to 000 to 1500 Hz.

The noise reduced to some extent by the sound path space section 7 and the filter 11 is radiated to the sound path space section 8 at the next stage in order to further reduce the sound pressure level. Attenuation of the sound pressure level related to the low frequency component of the vacuum cleaner noise is performed as the third stage with the volume of 8. Third
In the step, the sound pressure level mainly related to 550 to 1000 Hz is attenuated.

The cleaner noise radiated to the sound path space 8 passes through the open hole 15 provided in the filter 12 at the next stage. When the noise passes through the open hole 15, it resonates with a high frequency band that cannot be reduced by the filter 11 in the previous stage in accordance with its diameter and volume, so that the sound pressure related to the high frequency component of the cleaner noise is increased. Level decay occurs as the fourth stage. In the fourth stage, the sound pressure level mainly related to 1500 to 5000 Hz is attenuated. The open hole 15 has a drum-shaped inner peripheral wall 16 in order to take measures against high frequencies in a relatively wide band, and widens the frequency range in which resonance occurs.

FIG. 5 shows the output sound pressure level (solid line) of noise radiated from a vacuum cleaner which has not yet taken countermeasures against noise, and the radiated noise from the vacuum cleaner 1 which is provided with the noise reduction device according to the first embodiment. In the characteristic diagram comparing the output sound pressure level of the generated noise (broken line), the horizontal axis is the frequency of the noise emitted from the cleaner, and the vertical axis is the output sound pressure level indicating the attenuation amount. As shown in the characteristic diagram of FIG. 5, the noise reduction device according to the first embodiment has a reducing effect on the sound of 350 Hz to 20 KHz, and has a particularly large reducing effect on the sound of 350 Hz to 5000 Hz.

As described above, by mounting the noise reduction device of the first embodiment, it is possible to effectively reduce the noise emitted from the cleaner 1 from the low frequency region to the high frequency region.

Example 2. In the above-described first embodiment, the noise reducing device that discharges the reduced noise from the back surface portion 3 of the vacuum cleaner 1 to the outside has been described, but in the second embodiment, the noise of the motor 5 is emitted from the bottom surface 6 of the cleaner 1 to the outside. The noise reduction device to discharge is shown.
FIG. 6 is a partial side sectional view of the noise reduction device according to the second embodiment used in a vacuum cleaner, and FIG. 7 is a partial upper sectional view of the above-described FIG. 6, similar to the first embodiment shown in FIG. The same numbers are assigned to the items and the description thereof will be omitted. In FIGS. 6 and 7, 18 is an elbow-type sound tube, 19 is a plurality of open holes provided at arbitrary positions on the wall of the elbow-type sound tube 18, and 20 is so as to enclose the elbow-type sound tube 18. This is a sound path cavity formed by the elbow type sound path tube 18 and the sound path cavity 20. The Helmholtz structure is formed. The diameter of the elbow-type sound tube 18 and the volume of the sound path cavity 20 are
Determined at the time of design depending on the frequency reduced by the noise reduction device.

Next, the operation will be described. The noise radiated from the motor 5 is rectified and passes through the open hole 13 whose inner peripheral wall has a drum-like curved surface shape. At the time of the passage, the high frequency band of the cleaner noise is attenuated by the same operation as that of the first embodiment.

The noise radiated from the open hole 13 of the filter 11 into the elbow-type sound guide tube 18 is transmitted through the open holes 19 formed in plural at arbitrary positions of the elbow-type sound guide tube 18.
The noise is reduced by being radiated to the acoustic passage cavity 20 and causing a resonance phenomenon by the open hole 19 and the acoustic passage cavity 20. The frequency band that can be reduced by the open hole 19 is mainly a high frequency band. Further, the frequency band that can be reduced by the sound passage cavity 20 is mainly in the middle and low range, and the efficiency that can be reduced is determined by the inner volume of the sound passage cavity 20.

A filter 12 is installed at the final end of the elbow type sound pipe 18, and when noise passes through the open hole 15 of the filter 12, the filter 11 of the preceding stage is used.
The high frequency band other than the frequency band reduced by the open hole 13 is further reduced.

According to the second embodiment, with the above structure,
It is possible to obtain substantially the same noise reduction effect as that of the first embodiment. Further, since the noise itself is radiated from the bottom surface 6 to the floor surface, there is an effect that the noise is not directly radiated to the consumer who uses the vacuum cleaner. Furthermore, there is an effect that noise is attenuated even on the floor.

FIG. 8 is a characteristic diagram showing an example of the noise reduction effect according to the second embodiment. In FIG. 8, the meanings of the horizontal axis and the vertical axis, and the solid line and the broken line are the same as those in FIG. Figure 8
According to the second embodiment, as shown in the characteristic diagram of
It has the effect of reducing the high frequency band above Hz.

Example 3. In the first and second embodiments, the structure in which the filter is inserted is shown. However, in the third embodiment, the acoustic filter part is not configured and the first and second embodiments are described.
A structure having an effect substantially equal to that of No. 2 will be shown. FIG. 9 is a partial side sectional view of the noise reduction device according to the third embodiment used in a vacuum cleaner. The same parts as those of the first embodiment shown in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted. In FIG. 9, 2
Reference numeral 1 denotes a maze-type sound tube, and the structure is such that the maze-type sound tube 21 can be directly attached to the back surface portion 3 of the cleaner 1. It should be noted that each end portion in the maze type sound guide tube 21 has a curved surface shape in order to rectify the noise accompanying the air flow.

When the noise radiated from the motor 5 passes through the long maze type sound tube 21, the sound path spaces 7 and 8 formed in the middle of the maze type sound tube 21 and the maze. Due to the structure of the mold sound tube 21 itself, distance attenuation is caused, and noise is reduced from the low range to the high range. The reduced noise is generated by the filter 1 installed at the final end of the maze type sound tube 21.
When passing through the open hole 13 of No. 1, the high frequency range other than the frequency band reduced by the passage of the maze type sound guide tube 21 is further reduced and is discharged to the outside of the cleaner 1.

Example 4. In the above embodiments, the open hole of the filter has a cylindrical shape. However, the shape of the open hole is not limited to this. For example, a truncated cone shape has the same effect. FIG. 10 is a partially enlarged view of the filters 11 and 12 shown in FIG. 1 according to the fourth embodiment, and 8 is a sound path space portion provided between the filters 11 and 12,
22 is a truncated cone-shaped open hole, L1 is a large opening, L2
Is a small opening. In order to give the open hole 22 a rectifying effect, it is necessary to arrange the filters 11 and 12 so that the open end of the surface close to the noise source (on the left side in FIG. 10) becomes a large opening. According to the experimental results, the diameter of the large opening L1 is preferably 1.5 to 2 times the diameter of the small opening L2.

Example 5. Up to the above embodiment, the case where one or two acoustic filter units are used has been described, but the number of acoustic filter units is not limited to this, and any number may be used depending on the size of the device to be attached. In Figure 11,
The case where three acoustic filter parts are configured is shown. Figure 11
Is a cylindrical open hole 1 whose inner peripheral wall 14 is a drum-shaped curved surface.
11a having 3 and a frustoconical opening 22
And a filter 11b having a cylindrical open hole 15 whose inner wall 16 is a drum-shaped curved surface.
And are arranged in order from the noise source side.

The filters may be combinations other than those shown in FIG. 11, and for example, all three filters may be filters 11b having a truncated cone-shaped opening 22. Any combination of filters may be used as long as it causes resonance with different frequency bands depending on the diameter of the open hole of each filter. Further, the arrangement order of the filters may be other than that shown in FIG. 11, for example, the arrangement order of the filters 11a and 11b may be changed, or the arrangement order of the filters 11b and 12 may be changed, and the rectifying effect may be provided on the side closest to the noise source. It suffices to attach a filter having.

Example 6. In the above embodiments, the case where the noise reduction device is configured as a vacuum cleaner has been described, but the noise reduction device of the present invention is not limited to the vacuum cleaner and can be applied to all devices that generate sound (noise). FIG. 12 shows a case where the noise reduction device of the present invention is used for a ventilation fan. In FIG. 12, 23 is a ventilation fan installation member such as a wall material, 24 is a fan part of the ventilation fan, and 25 is a noise reduction device attached later. It is a unit. Arrows (→) in the figure indicate the spatial radiation and propagation directions of the sound generated by the ventilation fan.

As shown in FIG. 12, the noise reduction device of the present invention can be retrofitted to a device that is already on the market and has a problem of noise.

As described above, according to the first aspect of the present invention, the first resonance chamber provided on the noise source side and having a predetermined resonance frequency band, and the noise for forming the first resonance chamber. A first filter having a plurality of cylindrical open holes provided opposite to the source, a second resonance chamber having a resonance frequency band different from that of the first resonance chamber, and the second resonance chamber. And a second filter having a plurality of cylindrical open holes having a diameter different from that of the first filter. As a result, it is possible to obtain a noise reduction device that can be attached without changing the structure of the device itself, is small, and effectively reduces the noise generated from the device from the low range to the high range.

According to the second invention, the opening hole of the first filter is formed in a cylindrical shape whose inner peripheral wall is a drum-shaped curved surface, and the opening hole of the second filter is formed in the inner peripheral wall. By forming the drum into a drum-shaped curved surface, the noise associated with the air flow generated in the equipment is rectified by the open hole of the first filter, effectively reducing the noise from high to high frequencies. Can be reduced.

According to the third aspect of the present invention, the open hole of the first or second filter is formed in a truncated cone shape having a large opening diameter on the noise source side. The noise accompanied by is rectified by the open hole of the first filter,
It is possible to effectively reduce the low to high noise range.

According to the fourth invention, a first resonance chamber provided on the noise source side and having a predetermined resonance frequency band, and a first resonance chamber facing the noise source so as to form the first resonance chamber. A first filter having a plurality of cylindrical open holes and a plurality of cylindrical open holes at arbitrary positions on the peripheral wall, and a tubular space inside which guides noise from the open holes of the first filter And a closed space surrounding the sound passage tube, and a sound exit side of the sound passage tube.
Since it has a second filter having a plurality of cylindrical open holes having a diameter different from the cylindrical open hole of the filter, it can be installed without changing the structure of the device itself, and is small in size. It is possible to effectively reduce a relatively high frequency range of noise generated from the device.

According to the fifth aspect of the invention, since the sound pipe is formed in a shape bent to the bottom side, and the noise generated from the equipment is radiated from the bottom surface of the equipment, the noise is directly transmitted to consumers. Do not radiate.

According to the sixth aspect of the present invention, the open hole of the first filter is formed in a cylindrical shape whose inner peripheral wall is a drum-shaped curved surface, so that noise accompanying air flow generated in the device is reduced. The open holes of the first filter can be used to rectify the noise and effectively reduce a relatively high frequency band of noise.

According to the seventh aspect of the present invention, the open hole of the first filter is formed in a truncated cone shape having a large opening diameter on the noise source side, so that the noise accompanying the air flow generated from the device is reduced. The open holes of the first filter can be used to rectify the noise and effectively reduce a relatively high frequency band of noise.

According to the eighth aspect of the present invention, the closed space having the entrance and exit is formed into a labyrinth type, and the labyrinthine sound tube provided with the entrance facing the noise source side, and the exit of this maze sound tube. Since it is equipped with a filter that has a plurality of cylindrical open holes provided on the side, it can be installed without changing the structure of the device itself, and it is compact, and the noise generated from the device is high in the low range. The area can be effectively reduced.

[Brief description of drawings]

FIG. 1 is a partial side sectional view of a noise reduction device according to a first embodiment of the present invention when used in a vacuum cleaner.

FIG. 2 is a plan sectional view of FIG.

FIG. 3 is a rear view of FIG. 1.

FIG. 4 is a partially enlarged cross-sectional view of the acoustic filter unit shown in FIG.

5 is a characteristic diagram showing an example of a noise reduction effect of the vacuum cleaner of FIG.

FIG. 6 is a partial side sectional view of a noise reduction device according to a second embodiment of the present invention used in a vacuum cleaner.

7 is a partial top cross-sectional view of FIG.

8 is a characteristic diagram showing an example of a noise reduction effect of the vacuum cleaner of FIG.

FIG. 9 is a partial side sectional view of a noise reduction device according to a third embodiment of the present invention used in a vacuum cleaner.

FIG. 10 is a partially enlarged view of the filter according to the fourth embodiment of the present invention.

FIG. 11 is a partially enlarged view of the filter according to the fifth embodiment of the present invention.

FIG. 12 is a side sectional view showing an example in which the noise reduction device according to the sixth embodiment of the present invention is used for a ventilation fan.

FIG. 13 is a sectional view of a main body of a known vacuum cleaner.

FIG. 14 is a known cavity-type silencer.

FIG. 15 is a known resonance type silencer.

FIG. 16 is a sectional view of a conventional silencer.

FIG. 17 is a plan view of a conventional silencer.

FIG. 18 is a vertical cross-sectional view of the conventional silencer shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vacuum cleaner 4 Internal space 5 Motor 6 Bottom 7, 8 Sound path space 10 Acoustic filter section 11, 12 Filter 13, 15 Open hole 14, 16 Inner wall 18 Elbow type sound tube 19 Open hole 20 Sound path Cavity 21 Maze sound tube 22 Frustum-shaped open hole 25 Reduction device unit

Claims (8)

[Claims] 1. A noise reduction device having the following elements for reducing noise in a device that emits noise. (A) a first resonance chamber provided on the noise source side and having a predetermined resonance frequency band; (b) a plurality of cylindrical shapes provided to face the noise source so as to form the first resonance chamber. A first filter having an open hole, (c) a second resonance chamber having a resonance frequency band different from that of the first resonance chamber, and (d) a predetermined resonance with the first filter so as to form the second resonance chamber. A second filter having a plurality of cylindrical open holes provided at intervals and having a diameter different from that of the first filter. 2. The opening hole of the first filter is formed in a cylindrical shape whose inner peripheral wall is a drum-shaped curved surface, and the opening hole of the second filter is a drum-shaped curved surface. The noise reduction device according to claim 1, wherein the noise reduction device is formed into a cylindrical shape. 3. The noise reduction device according to claim 1, wherein the open hole of the first or second filter is formed in a truncated cone shape having a large opening diameter on the noise source side. 4. A noise reduction device having the following elements for reducing noise in a device that emits noise. (A) a first resonance chamber provided on the noise source side and having a predetermined resonance frequency band; (b) a plurality of cylindrical shapes provided to face the noise source so as to form the first resonance chamber. A first filter having an open hole, (c) a sound having a plurality of cylindrical open holes at arbitrary positions on the peripheral wall, and having a tubular space inside which guides noise from the open hole of the first filter. A pipe, (d) a closed space surrounding the sound pipe, and (e) a plurality of cylinders provided on the noise outlet side of the sound pipe and having a diameter different from the cylindrical open hole of the first filter. Second filter having a circular open hole. 5. The noise reduction device according to claim 4, wherein the sound passage tube is formed in a shape bent to the bottom surface side. 6. The noise reduction device according to claim 4, wherein the open hole of the first filter is formed in a cylindrical shape whose inner peripheral wall is a drum-shaped curved surface. 7. The noise reducing device according to claim 4, wherein the opening hole of the first filter is formed in a truncated cone shape having a large opening diameter on the noise source side. 8. A noise reduction device having the following elements for reducing noise in a device that emits noise. (A) A labyrinthine sound tube in which a closed space having an entrance and exit is formed in a labyrinth type, and the entrance is arranged so as to face the noise source side; A filter with one cylindrical open hole.