JPH0630860A - Vacuum cleaner - Google Patents

Abstract

PURPOSE:To provide a vacuum cleaner capable of reducing the operating noises without enlarging a vacuum cleaner main body and without impairing the suction performance. CONSTITUTION:At least one resonance type acoustic filter 34 having multiple resonance side pipes 35 with different lengths is provided on an exhaust air duct 31 between an electric fan 6 stored in a vacuum cleaner main body 1 and the exhaust port of the vacuum cleaner main body 1, sounds of multiple frequencies are attenuated by the resonance action by the side pipes 35 with different lengths respectively, and the operating noises of the vacuum cleaner are reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum cleaner capable of reducing operating noise.

[0002]

2. Description of the Related Art Conventionally, as a measure for reducing the operation noise of an electric vacuum cleaner, a silencer formed of a felt, urethane foam having open cells, or high-density paper in a cylindrical shape is used.
It is common to surround the periphery of an electric blower that is a sound source, and to arrange a muffling body made of the same material in the exhaust air passage to allow the wind blown from the electric blower to pass through them and reduce the operating noise. Has been done in. In addition to this, there is also known a structure in which an exhaust air passage extending from an electric blower to an exhaust port of a cleaner body has a muffler structure to reduce operating noise.

[0003]

In the conventional electric vacuum cleaner, which uses only the silencer for silencing, in order to realize even quieter operation, a silencer such as a felt is installed in the exhaust air duct. It is necessary to provide a large number in. However, since a silencer such as felt becomes an air passage resistance and reduces the momentum of the wind sent from the electric blower, when a large number of such silencers are arranged, the air passage resistance increases accordingly. Therefore, there is a problem that the suction performance of the electric vacuum cleaner is deteriorated.

Further, for example, a frequency analysis diagram of operating noise of a conventional vacuum cleaner equipped with an electric blower for rotating a fan having nine blades at 30,000 rpm is shown in FIG. 6 (horizontal axis is logarithmic scale). , About 4.5 KHz and about 9
The amplitude of the sound with the frequency of KHz is particularly large. About 9 KHz of that is the frequency range (1
Since it is outside the range of ~ 6 KHz), it does not matter so much, but a sound of about 4.5 KHz with an extremely large amplitude (the driving sound level is 58.8 dB) is particularly noisy.

The sound of this frequency is determined by the number of revolutions A of the electric blower and the number B of blades of the fan, and is (A / power supply frequency) ×
It is given by the formula of B. In addition, the rotation speed of the electric blower changes depending on the amount of collected dust, and in the case of an electric vacuum cleaner capable of switching the input to the electric blower, it also changes depending on the input switching. As a result, the frequency of the sound with extremely large amplitude naturally changes.

By the way, in order to obtain a sufficient silencing effect with the silencing material such as the felt, it is necessary to make the silencing material thick. However, if so, the air passage becomes narrow, so that the thickness thereof is limited. Therefore, the silencing effect for the sound of the frequency given by the above equation is small. Therefore, the conventional electric vacuum cleaner has its operating sound level O.S. A
There is a problem that the value is as large as 72.9 dB.

In addition, the conventional exhaust air passage having the muffler structure has a problem that the main body of the cleaner is inevitably large because the exhaust air passage needs to be long.

An object of the present invention is to obtain an electric vacuum cleaner which can reduce the operating noise without making the main body of the vacuum cleaner large and without impairing the suction performance.

[0009]

In order to achieve the above object, an electric vacuum cleaner according to the present invention comprises a plurality of resonance side tubes having different lengths on the exhaust side of an electric blower built in a cleaner body. Or at least one resonance type acoustic filter having the same length, or a plurality of resonance type acoustic filters having a plurality of resonance side tubes having the same length, and a plurality of side tubes having the same length. The lengths of the side tubes of the plurality of acoustic filters that are provided are different from each other.

[0010]

In the above structure, the side tube of the acoustic filter resonates the sound of a specific frequency among the sounds carried by the air flowing to the exhaust side of the electric blower, thereby attenuating the energy of the specific sound. Since the acoustic filter has a plurality of side tubes having different lengths from each other, or the plurality of acoustic filters have side tubes having different lengths from each other, these side tubes correspond to the lengths. Resonating the frequency sound,
Attenuate the energy of the sound. Moreover, unlike the felt, the acoustic filter rarely impairs the wind force. Furthermore, since the operating noise is reduced by using the acoustic filter, it is not necessary to use a long exhaust air duct having a muffler structure to reduce the operating noise.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS. FIG. 2 is a cross-sectional view showing the structure of the rear portion of the electric vacuum cleaner, in which 1 is a cleaner body formed in a horizontally long shape, 2 is a rear moving wheel attached to the main body 1, and 3 is a cleaner. The carrying handle which is provided on the upper surface side of the main body 1 and is rotatable around the pivot 4 is shown as a hoistable carrying handle. A dust suction port to which a dust suction hose or the like is detachably connected is provided in the front portion of the cleaner body 1 which is not shown, and an exhaust port 5 is opened in the rear surface of the cleaner body 1.

At the rear of the cleaner body 1, an electric blower 6 is installed in a horizontal orientation. As shown in FIG. 2, the electric blower 6 includes an electric motor 7 and a centrifugal fan 9 attached to the front end of a horizontal rotary shaft 8.

The electric motor 7 has a bottomed cylindrical electric motor case 1 having a front end opened and a rear end closed as a bottom wall.
A substantially rectangular frame-shaped stator 11 is housed in the housing 0, and a plurality of air passages 12 are formed between the stator 11 and the inner surface of the cylindrical wall portion of the electric motor case 10. A case end face plate 13 that crosses the front end opening in the radial direction is installed on the electric motor case 10, and bearings 14 and 15 fixed to the end face plate 13 and the bottom wall of the electric motor case 10 make the inside of the stator 11 inside. The rotating shaft 8 of the arranged rotor 17 with the commutator 16 is rotatably supported. Further, an air outlet 10a is formed on the bottom wall side of the electric motor case 10, and a pair of brush devices 18 are attached. The electric motor 7 is formed with the above configuration.

The rotation speed of the electric motor 7 is controlled by a control device (not shown) in response to a manual input suitable for the cleaning condition, and the suction capacity is changed to "strong", "medium" or "weak".
It is possible to switch to one of the two driving modes. And at its maximum output (operating state in "strong operation mode"), the fan 9 is rotated 30000 times per minute, and in operation in "medium operation mode", the fan 9 is rotated 18000 times per minute,
In operation in the "weak operation mode", the fan 9 can be rotated 9,000 times per minute.

The front end of the rotary shaft 8 penetrates the front bearing 14, and the fan 9 is fixed to the penetrating end.
The number of blades of the fan 9 is 9, for example. A rectifying plate 19 fixed to the end face plate 13 and the motor case 10 is arranged between the fan 9 and the case end face plate 13. Further, a fan cover 20 having an intake port 20a is attached to the motor case 10, and the cover 20 hides the fan 9 and the current plate 19.

When the electric blower 6 is operated, the fan 9 is rotated together with the rotor 17, so that air is sucked into the fan 9 through the intake port 20a, and this air is discharged from the peripheral portion of the fan 9, Fan cover 20 and current plate 1
9 is sequentially guided, passes through the air passage 12 from the opening between the opening edge of the electric motor case 10 and the side edge of the case end face plate 13, and is blown from the air outlet 10a to the periphery of the electric motor case 10. It is supposed to work.

An annular anti-vibration rubber 21 is attached to the peripheral portion of the fan cover 20 of the electric blower 6, and the outside of the bearing fitting projection 10b formed in the center of the bottom wall of the electric motor case 10. Also, the anti-vibration rubber 22 is attached.
Then, the anti-vibration rubbers 21 and 22 are attached to the support ribs 23 to 25 and the support wall 26 which are integrally formed with the cleaner body 1.
The electric blower 6 is supported in the cleaner main body 1 in a horizontally placed state by engaging with the above. The space in front of the electric blower 6 installed as described above is a dust collection chamber 27, and a bag-shaped dust collection filter (not shown) is provided here.
Is accommodated, and the air sucked from the dust suction port (not shown) of the cleaner body 1 is filtered by the blower action of the electric blower 6. Further, in FIG.
Reference numeral 41 is a code reel and 42 is a bumper.

As shown in FIGS. 1 and 2, a silencer cylinder 29 is provided in the cleaner body 1 so as to surround the cylindrical wall portion of the motor case 10 from the outside. The front end of the muffler cylinder 29 is in contact with the back surface of the annular flange portion extending from the opening edge of the electric motor case 10, and the rear end is in contact with the front surfaces of the continuous support ribs 24, 25. . Silencer 2
Although 9 is made of foamed urethane having open cells, a muffling cylinder made of felt or high-density paper may be used instead.

A through hole 30 is provided in a portion of the support rib 24 located outside the muffling cylinder 29, whereby an exhaust air passage 31 from the air outlet 10a of the electric blower 6 to the exhaust port 5 is formed. ing. In the middle of the exhaust air passage 31, a rear silencer plate 32 is arranged across the air passage 31. The sound deadening plate 32 is also made of foamed urethane having open cells, but a rear sound deadening plate made of felt or high-density paper may be used instead. Exhaust port 5
Is formed by the rear end opening of the exhaust port body 33 attached to the rear end part of the cleaner body 1, and the muffler plate 32 is supported at the inlet part of the exhaust port body 33. The exhaust port body 33 has an exhaust air guide 33a.

On the exhaust side of the electric blower 6, for example, in the exhaust air passage 31, a pair of resonance type acoustic filters 34 is provided as shown in FIGS. 1 and 2, and these are integrally molded of synthetic resin. It is a product and is arranged so as to surround the silencer cylinder 29 from the outside thereof. As shown in FIG. 1, these acoustic filters 34 are arranged in the circumferential direction of the electric motor 7 and have first to third resonance side pipes 35 to 3 having different lengths.
Have 7. These first to third side tubes 35 to 37 are arranged in two rows in the axial direction of the electric motor 7 as shown in FIG.

Each of the first to third side pipes 35 to 37 is formed in the vertical direction in FIGS. 1 and 2 and has a bottomed cylindrical shape with one end closed. First to third side tubes 35 to 3
7 is the length L required to attenuate the sound of the specific frequency.
1 to L3. That is, the side tubes 35 to 37
The lengths L1 to L3 are fm (Hz), which is a frequency determined by the number of rotations of the electric motor 7 and the number of blades of the fan 9, and C is the speed of sound.
(346670 mm / s, 25 ° C.), where N is an integer constant (1, 2, 3, ...), (2N−1) ·
The length is set to the value calculated by the formula of C / (4fm). Here, the sound of the specific frequency to be erased is the electric blower 6
Is a peculiar sound generated by the number of blades of the fan 9 based on the imbalance of the rotation of these blades.

That is, since the number of blades of the fan 9 is 9, and the electric motor 7 is rotated at 30000 rpm as described above during the operation in the "strong operation mode", the frequency of the sound generated by the fan 9 is increased. fm is the number of blades of the fan 9 (9
It is calculated by multiplying the number of sheets by 4500 Hz. Then, by applying this frequency of 4500 Hz to the above equation, the shortest length L1 of the first side pipe 35 can be obtained, and the length L1 of the first side pipe 35 thus determined is 19.25. mm. Further, the longest third side pipe 37 is provided corresponding to the operation in the "weak operation mode", and the electric motor 7 is rotated at 9000 rpm as described above during the operation in the "weak operation mode". Therefore, the frequency fm of the sound generated by the fan 9 is C / (4 ·
150 ・ 9) = 64.19 mm, and this length L3 (64.19
mm) and the third side tube 37 is formed. Similarly, the second side pipe 36 having an intermediate length is in the "medium operation mode".
The motor 7 is rotated at 18000 rpm as described above during the operation in the "medium operation mode", so that the frequency f of the sound generated by the fan 9 is f.
m is C / (4 · 300 · 9) = 32.09 mm according to the above formula
The second side pipe 36 is formed with this length L2 (32.09 mm).

In the electric vacuum cleaner having the resonance type acoustic filter 34 having the above construction, the wind flowing out from the wind outlet 10a of the electric blower 6 and carrying the sound generated by the electric blower 6 is exhausted. Not only is the sound deadening effect passed through the sound deadening cylinder 29 and the rear sound deadening plate 32 in 31, but also the sound deadening effect is obtained by the acoustic filter 34 immediately after passing through the sound deadening cylinder 29.

FIG. 3 shows the principle of the acoustic filter 34,
The length L (L1 or L2 or L3) of the resonance side pipe 35A (the side pipe 35 or the side pipe 36 or the side pipe 37) orthogonal to the exhaust air passage 31 through which the wind exhausted with sound passes is ,
Since the sound having the frequency of fm = (2N-1) · C / 4L resonates in the side tube 35A, the sound having the resonance frequency is attenuated due to the energy loss consumed by the resonance. It is what is done. FIG. 4 shows the characteristics in the principle diagram of FIG. 3, where f1,
f3 and f5 are center frequencies resonating in the side tube 35A,
The chain double-dashed line shows the energy of the sound lost by resonance. As can be seen from FIG. 4, the acoustic filter 34 exhibits a sound deadening effect with respect to an odd multiple of the resonance frequency.

Therefore, the acoustic filter 34 as described above is used.
Due to the sound deadening principle of the fan, when the vacuum cleaner is operated in the "strong operation mode", the fan 9
The sound having a frequency of about 4.5 KHz that is offensive to the ear can be attenuated by the resonance action in the first side tube 35. That is, FIG. 5 (horizontal axis is a logarithmic scale) is an analysis diagram showing the frequency of the electric vacuum cleaner incorporating the acoustic filter 34 in terms of the acoustic power level. As shown in FIG. Of 56.2 dB, which is 2.6 dB lower than that without the acoustic filter 34. It was proved that the A value could be as low as 71.5 dB. Of course, the length L of the second and third side tubes 36, 37
Sounds of frequencies corresponding to 2 and L3 are also generated by these side tubes
It can be damped by the resonance effect at 7, and that is also the driving sound level O. It helps to lower the A value.

When the electric vacuum cleaner is operated in the "medium operation mode", the frequency of the sound having a large amplitude generated by the fan 9 decreases according to the rotation speed at that time, and therefore the first frequency is applied to the sound of this frequency. Side tube 35 and third side tube 3
No attenuation due to the resonance effect at 7 can be expected. However, since the acoustic filter 34 has the second side tube 36 of the length L2 that resonates the frequency of the sound with a large amplitude generated from the fan 9 during the operation in the "medium operation mode", this The resonance can be damped by the side tube 36.

Similarly, when the vacuum cleaner is operated in the "weak operation mode", the frequency of the sound having a large amplitude generated by the fan 9 according to the rotation speed at that time is higher than that in the "medium operation mode". As the sound of this frequency is further lowered, the attenuation due to the resonance action in the first and second side tubes 35, 36 cannot be expected. However, the acoustic filter 3
4 is a length L for resonating the frequency of a sound with a large amplitude generated from the fan 9 during operation in the "weak operation mode"
Since the third side pipe 37 is provided, the resonance can be performed by the side pipe 37.

That is, as described above, no matter which operation mode the vacuum cleaner is operated in, the sound of the frequency generated by the fan 9 having a large amplitude can be attenuated, and the quiet operation can be performed.

Since the acoustic filter 34 attenuates sound by utilizing the resonance phenomenon, it does not substantially reduce the force of the wind passing through the exhaust passage 31. Therefore,
The sound deadening effect of the vacuum cleaner can be improved and quiet operation can be performed without impairing the suction performance of the electric vacuum cleaner.

Moreover, unlike the sound muffler, the acoustic filter 34 does not need to have a long exhaust air passage, so that the cleaner main body 1 may be made larger to improve the sound deadening effect. Can be implemented without.

The present invention is not limited to the above embodiment. For example, side tubes with different lengths of acoustic filters are
Instead of a closed tube with a bottom, an open tube without a bottom may be formed. In this case, the length of the side tube may be set to the length obtained by the formula of (N · C) / 2fm, so that the sound of the specific frequency fm caused by the rotation of the fan is opened. Can be resonated in the side tube.

Further, the acoustic filter may be provided anywhere within the exhaust air passage, or may be provided integrally with the cleaner body. Further, the acoustic filter may be located near the exhaust port and provided outside the cleaner body. The number of acoustic filters may be one or more, and the side tubes may be obliquely provided as long as the sound deadening principle that the sound is attenuated by utilizing the resonance phenomenon can be obtained.

Further, in the above-mentioned one embodiment, the lengths of a plurality of resonance side tubes included in one acoustic filter are different from each other,
Sounds of different frequencies to be eliminated were attenuated depending on the operation mode. Instead of this, a plurality of acoustic filters with multiple resonance side tubes of the same length were provided in the exhaust air duct, and these same lengths were provided. A plurality of acoustic filters having a plurality of side pipes may be arranged so that the lengths of the side pipes of the acoustic filters are different from each other, so that the sound of the frequency to be eliminated which is different depending on the operation mode may be attenuated.

In addition, when applied to an electric vacuum cleaner having one operation mode, when a sound of a frequency having a large amplitude is generated in addition to the frequency based on the number of blades of the fan and the rotation speed of the electric motor (for example, 5 and 6, 500 Hz,
For a sound having a frequency of 1000 Hz), by providing an acoustic filter 34 provided with a side tube having a length having the frequency as a resonance frequency, the sound can be attenuated and the operation sound can be reduced.

[0035]

As described in detail above, the electric vacuum cleaner of the present invention is a resonance type acoustic cleaner having a plurality of resonance side tubes of different lengths on the exhaust side and the electric blower built into the cleaner body. At least one filter is provided, or a plurality of resonance type acoustic filters having a plurality of resonance side tubes having the same length are provided, and a plurality of acoustic filters having a plurality of side tubes having the same length are provided. By making the lengths of the side tubes different from each other, the sound of multiple frequencies can be attenuated by the resonance action of the side tubes having different lengths, and the operation noise of the vacuum cleaner can be reduced. In order to reduce the driving noise by using an acoustic filter, it is not necessary to use a long exhaust air passage with a muffler structure in order to reduce the driving noise. Very little loss of wind power In, it can be realized without impairing or with large the cleaner main body to reduce the aforementioned operating noise, or the suction performance.

[Brief description of drawings]

FIG. 1 is a sectional view showing a main part of an electric vacuum cleaner according to an embodiment of the present invention, taken along line ZZ in FIG.

FIG. 2 is a vertical sectional side view showing a configuration of a rear portion of the electric vacuum cleaner according to the embodiment.

FIG. 3 is a cross-sectional view showing the principle of a resonant acoustic filter.

FIG. 4 is a diagram showing the characteristics of the resonant acoustic filter shown in FIG.

FIG. 5 is a frequency analysis diagram of a driving sound of the vacuum cleaner according to the embodiment.

FIG. 6 is a frequency analysis diagram of a driving sound of a conventional electric vacuum cleaner.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Vacuum cleaner main body, 5 ... Exhaust port, 6 ... Electric blower, 7 ... Electric motor, 8 ... Rotating shaft, 9 ... Fan, 31 ... Exhaust air passage, 34
... Acoustic filter 35-37 ... Side tube for resonance.

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[Procedure amendment]

[Submission date] September 24, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0005

[Correction method] Change

[Correction content]

The sound of this frequency is the rotational speed A of the electric blower.
(Rpm) and the number of fan blades B, (A / 6
0 ) × B. In addition, the rotation speed of the electric blower changes depending on the amount of collected dust, and in the case of an electric vacuum cleaner capable of switching the input to the electric blower, it also changes depending on the input switching. As a result, the frequency of the sound with extremely large amplitude naturally changes.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0022

[Correction method] Change

[Correction content]

That is, since the number of blades of the fan 9 is 9, and the electric motor 7 is rotated at 30000 rpm as described above during the operation in the "strong operation mode", the frequency of the sound generated by the fan 9 is increased. fm is the number of rotations of the electric motor 7 30000 (r
pm) converted to frequency, that is, 30000/60 [H
It is calculated by multiplying the value of z] by the number of blades of the fan 9 (nine), which is 4500 Hz. And this frequency 4500
By applying Hz to the above equation, the shortest length L1 of the first side pipe 35 can be obtained, and the length L1 of the first side pipe 35 thus determined is 19.25 mm. Further, the longest third side pipe 37 is provided corresponding to the operation in the "weak operation mode", and when operating in this "weak operation mode", the electric motor 7 is 9000rp as described above.
Since it is rotated at m, the frequency fm of the sound generated by the fan 9 is C / (4 · 150 · 9) = 64.19 according to the above equation.
mm, and with this length L3 (64.19 mm), the third
The side tube 37 of the is formed. Similarly, the second side pipe 36 having an intermediate length is provided corresponding to the operation in the "middle operation mode", and the electric motor 7 is operated as described above during the operation in the "middle operation mode". Since it is rotated at 18000 rpm, the frequency fm of the sound generated by the fan 9 is C / (4 · 300 · 9) = 32.09 mm according to the above formula, and this length L
The second side tube 36 is formed with 2 (32.09 mm).

Claims (1)

[Claims] 1. An electric blower in which a fan is attached to a rotating shaft of an electric motor in a cleaner body having a dust suction port and an exhaust port, and an air blower of the electric blower moves the dust suction port into the cleaner body. In a vacuum cleaner that has a built-in dust collecting filter that captures dust contained in sucked air, and discharges the air filtered by this dust collecting filter from the exhaust port to the outside of the cleaner main body, on the exhaust side of the electric blower. , At least one resonance type acoustic filter having a plurality of resonance side tubes having different lengths, or a plurality of resonance type acoustic filters having a plurality of resonance side tubes of the same length At the same time, the electric vacuum cleaner is characterized in that a plurality of acoustic filters having a plurality of side tubes having the same length have mutually different side tubes.