JP2007185413A - Vacuum cleaner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of controlling a motor by suppressing the high-frequency noise and a vacuum cleaner using the method. <P>SOLUTION: The vacuum cleaner comprises an electric blower 110 with a centrifugal fan, resonance type mufflers 111 and 112 with a plurality of recesses 113 to resonate with a plurality of frequencies determined by the integral multiple of the product of the number of blades and the rotational frequency of the centrifugal fan, a rotational frequency detecting means 215 for detecting the rotational frequency of the electric blower 110, and a control means 214 for receiving signals from the rotational frequency detecting means 215 and controlling the rotational frequency so that the rotational frequency of the electric blower 110 approximates a predetermined target rotational frequency. The control means 214 controls the rotational frequency of the electric blower 110 so that the rotational frequency is fixed at a rotational frequency corresponding to the resonance frequency of the resonance type mufflers 111 and 112. As a result, the high-frequency noise generated in the frequency can be muffled. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to noise reduction of a vacuum cleaner.

  In a conventional vacuum cleaner, a centrifugal turbofan is used as an impeller for an electric blower that generates a suction force. A characteristic of this turbofan is that an unpleasant high-frequency sound is generated at a frequency that is an integral multiple of the product of the number of blades and the rotational frequency. These high-frequency sounds are generally called NZ sounds, and with the recent increase in the suction work rate, the sound level has become large, and reducing this has become one of the major issues. Yes.

Various approaches have been proposed to reduce this. Among them, there is a resonance muffler as a means for eliminating sound of a specific frequency. This is provided in the vicinity of the exhaust port of the electric blower that is the source of sound, in a direction perpendicular to the direction in which the noise passes, with a concave portion (side branch) having a silencing effect for only a certain frequency, The sound of the frequency that resonates at the depth of the groove is reflected to have an opposite phase, and only the sound of the specific frequency of the original sound source is erased in a sound pressure distribution. FIG. 7 shows an application of the recess 113 to the soundproof cylinder 213 that covers the outer periphery of the electric blower 110. Among exhaust sounds discharged from the exhaust port of the electric blower, a specific depth determined by the depth D of the recess 113 is shown. It is intended to erase the sound of the frequency (for example, see Patent Document 1).
JP 2001-165097 A

  However, the conventional configuration is effective for high-frequency sound of a certain frequency, but, for example, dust accumulates in the dust collection chamber of the vacuum cleaner, resulting in a reduction in the air volume. When the rotation speed changes, the frequency of the high-frequency sound also changes. Therefore, resonance does not occur at the preset side branch slit depth, and the high-frequency sound can be silenced. There was a risk of disappearing.

  The present invention solves the above-described conventional problems, and provides a vacuum cleaner in which the silencing effect does not decrease with respect to the load fluctuation of the motor by combining the conventional resonance silencer and the motor speed control. Is.

  In order to solve the above-described conventional problems, the present invention includes an electric blower having an intake port and an exhaust port, a centrifugal fan, and a blade of the centrifugal fan disposed in the vicinity of the exhaust port of the electric blower. A resonance-type silencer having a plurality of recesses that resonate at a plurality of frequencies determined by an integral multiple of the product of the number of sheets and the number of rotations, a number-of-rotations detection unit that detects the number of rotations of the electric blower, and the number of rotations detection unit And a control means for controlling the rotational speed so that the rotational speed of the electric blower approaches a predetermined target rotational speed set in advance, and the control means is configured to control the electric blower in the predetermined air volume interval. By controlling the rotation speed to be constant at the rotation speed corresponding to the resonance frequency of the resonance type silencer, the high frequency sound generated at the frequency is silenced. Your Air volume change due to accumulation, even if the air volume changes or the like occurs due to a change in the floor in the cleaning, the rotation speed of the electric blower is constant, but that can always exhibit the effect of the resonance type silencer.

  Irritating high frequency sound (protruding sound) of the electric vacuum cleaner can be suppressed regardless of the load fluctuation of the electric blower.

  The first invention comprises an air blower having an air inlet and an air outlet and a centrifugal fan, and the product of the number of blades and the number of rotations of the centrifugal fan disposed in the vicinity of the air outlet of the electric fan. In response to a signal from the resonance muffler having a plurality of recesses that resonate at a plurality of frequencies determined by an integral multiple of the frequency, a rotation speed detection means for detecting the rotation speed of the electric blower, and a signal from the rotation speed detection means, Control means for controlling the rotational speed of the electric blower so as to approach a predetermined target rotational speed set in advance, and the control means is configured such that the rotational speed of the electric blower is set to the resonance type silencer in a predetermined air volume section. By controlling the frequency to be constant at the rotation speed corresponding to the resonance frequency of the container, the high-frequency sound generated at the frequency is silenced. Even air volume changes or the like occurs due to a change in the floor in a rotational speed of the electric blower is constant, but that can always exhibit the effect of the resonance type silencer.

  In the second aspect of the present invention, the resonance-type silencer system is a side branch system that is determined only by the depth of the recesses, so that the length in the width direction is not so much required, and the silencer that combines a plurality of recesses continuously. It becomes possible to install the fan in the vicinity of the electric blower.

  In the third aspect of the invention, since the resonance-type silencer method is a Helmholtz method determined by the depth of the recess, the cross-sectional area, and the inner volume of the back space, it can be determined by three kinds of parameters, so that the design of the silencer is free. The degree becomes higher.

  According to a fourth aspect of the present invention, the control means keeps the rotational speed of the electric blower constant in the air volume range from the maximum air volume that opens the suction port of the vacuum cleaner to the air volume that narrows the suction port and the suction work rate is near the peak. By providing a plurality of air volume sections to be controlled, a degree of freedom is provided in the control of the rotational speed that changes according to the air volume, and the feasibility of the control to keep the rotational speed constant is improved.

  In the fifth aspect of the invention, the rotational speed of the electric blower controlled by the control means so as to be constant in each air volume section is set so as to increase stepwise as the air volume section moves from a large air volume section to a small air volume section. In order to reduce the overall noise of the vacuum cleaner or to save energy, it is possible to operate at a low rotational speed and to increase the rotational speed step by step until the air flow at the maximum work rate. By raising it, it is possible to maintain a high suction work rate while muting high-frequency sound.

  In the sixth aspect of the invention, in addition to the function and effect of the fifth aspect of the invention, the maximum suction work rate is obtained by setting the rotational speed and input of the electric blower to be maximum in the vicinity of the air volume at which the suction work rate reaches a peak. Can be demonstrated.

In the seventh aspect of the present invention, the control means sets the rotation speed of the electric blower to be constant in the air volume range from the vicinity of the air volume at which the suction work efficiency reaches a peak until the suction port is narrowed and the protective device operates in the vicinity of the air seal. By providing one or more air volume sections to be controlled,
It is possible to reduce high-frequency sound that is particularly noticeable in a region where the air volume is restricted.

  In the eighth aspect of the invention, the effect of the resonance type silencer is obtained by making the rotational speed of the electric blower constant in the air volume range from the maximum air volume until the suction port is narrowed down and the protective device operates in the vicinity of or near the airtight. It can be used in all airflow ranges.

  9th invention sets the input (rotation speed) of each position so that the frequency of the low-order high frequency sound of a certain input position and the frequency of the high-order high frequency sound in the input position lower than the said position may overlap. As a result, in the case of a vacuum cleaner having a plurality of operation positions, the design of the recesses of the silencer can be made common at the overlapping frequency and the number thereof can be reduced, so that the space can be saved. .

  In the tenth aspect of the invention, by using an inverter-driven brushless motor as the electric blower, the number of times can be easily controlled by PWM control or PAM control using a feedback gain signal.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the embodiment.

(Embodiment 1)
The first embodiment of the present invention will be described below with reference to FIGS. In addition, the same code | symbol is attached | subjected about the same component as a prior art example, and the description is abbreviate | omitted.

  FIG. 1 shows a cross section of the main body 101 of the vacuum cleaner, 202 is a dust collection chamber into which a dust bag 203 for collecting dust is inserted, and 204 is an electric blower chamber in which an electric blower 110 is built. Reference numeral 205 denotes a suction port of the electric vacuum cleaner main body 101, to which a hose (not shown) is attached, and an extension pipe and a floor nozzle (not shown) are attached to the front thereof. The dust collection chamber 202 and the electric blower chamber 204 are partitioned by a partition wall 207 having a communication hole 206, and a prefilter 208 is disposed in front of the partition wall 207. Further, an exhaust port 209 of the main body is provided at the rear of the vacuum cleaner main body 101, and an exhaust filter 210 is provided immediately before the exhaust port 209. Reference numeral 214 denotes control means for controlling the rotational speed of the electric blower 110, and reference numeral 215 denotes rotational speed detection means for detecting the rotational speed of the electric blower 110.

  Next, the periphery of the electric blower will be described. Reference numeral 110 denotes an electric blower. A support rubber fly 211 is attached to the front of the electric blower, and a support rubber fly 212 is attached to the rear. The electric blower 110 is fixed and stored in the electric blower chamber 204 through the support rubber. Reference numeral 213 denotes a soundproof cylinder for blocking the noise of the electric blower, and is mounted so as to cover the electric blower 110. 111 and 112 are side branch type silencers provided with a plurality of recesses 113 attached around the electric blower 110.

  Next, the internal configuration of the electric blower 110 will be described with reference to FIG. Reference numeral 301 denotes an impeller composed of a plurality of blades 302 that generates an airflow. 303 is an air guide for guiding the airflow generated by the impeller. 304 is a casing having an air inlet 305 in the center and containing the impeller 301 and the air guide 303. It is. A plurality of jet outlets 315 for discharging a part of the airflow that has passed through the air guide 303 are provided on the outer periphery of the casing 304. Reference numeral 306 denotes an electric motor that rotationally drives the impeller 301, and supplies power to a rotor 308 that is rotatably supported by bearings 307 at both ends, a rotating shaft 309, a stator 310 that generates a magnetic field around the rotor 308, and a commutator 311. It consists of a pair of carbon brushes 312 and is covered with a bracket 313.

  Next, a method for controlling the electric blower 110 mounted on the electric vacuum cleaner 101 will be described. FIG. 3 is a circuit block diagram of the electric vacuum cleaner of the present invention, FIG. 4 (a) is the relationship between the amount of air flowing through the passage inside the electric vacuum cleaner and the number of rotations of the electric blower 110, and below (b) is the same air amount. And the input of the electric blower 110 are shown. From FIG. 4, the rotational speed of the electric blower 110 is set to take one of four steps N1 to N4 in a stepped manner with respect to the change in the air volume. The input curve is a curve that decreases as the air volume is reduced in the section because the rotation speed is constant in a certain air volume section.

  Moreover, the four recessed parts 113 of D1-D4 are provided so that the depth of the recessed part 113 of the side branch type silencer 111, 112 of FIG. 2 may correspond to four rotation speeds N1-N4 on a one-to-one basis. . That is, the relationship between them is given by the following equation (1).

f = C / 4 / D (1)
Here, f represents the rotational speed (Hz) of the electric blower 110, D represents the depth (m) of the recess 113, and C represents the speed of sound (m / s). It is said that the depth D (m) of the recess 113 is effective to mute the sound having the frequency f (Hz).

  With the above configuration, the operation will be described. When electric power is supplied to the electric blower 110, the electric motor 306 rotates, and the impeller 301 directly connected thereto rotates. And while the air accelerated in the impeller 301 is decelerated by the air guide 303, a part of the air is ejected from the outer periphery of the casing 304, flows inside the soundproof cylinder 213, and enters the vacuum cleaner 101, exhaust port To 209. Further, the other air is guided to the electric motor 306 and is discharged from the exhaust port 314 of the bracket 313 while cooling the rotor 308, the stator 310, and the carbon brush 312, and passes through the soundproof cylinder 213 to the outside of the electric vacuum cleaner 101. And discharged. At this time, high frequency sound called NZ sound is mixed with other noises at the frequency of the product of the number of blades 302 of the impeller 301 and the number of rotations N (Hz), or an integral multiple thereof, and discharged together with the exhaust gas.

  However, in this embodiment, since the rotation speed of the electric blower 110 is detected and a signal is sent to the control means 214, the operation of the electric blower 110 is controlled to have the characteristics shown in FIG. The rotational speed of the electric blower 110 takes one of four predetermined rotational speeds. That is, when the air flow rate Q is the air flow interval Q1 <Q <= Q0, the electric blower 110 is operated at the preset rotation speed N1, and in the air flow interval Q2 <Q <= Q1, the electric blower 110 is set in advance. Control is performed by the control means 214 so as to operate at the rotational speed N2. The same applies to N3 and N4. At that time, the depths D1 to D4 of the four recesses 113 of the silencers 111 and 112 provided around the electric blower 110 are set so as to mute the high-frequency sound generated at each rotation speed. An unpleasant high-frequency sound can be suppressed against the air volume.

  In addition, when it is known that the suction work rate reaches a peak in the vicinity of the air volume Q2, if the input and rotation speed of the electric blower 110 are set to the maximum at Q2, a high suction work rate can be obtained. Will be.

  As described above, according to the embodiment of the present invention, the resonance silencer is controlled by controlling the number of rotations of the electric blower 110 in advance for any change in the air volume. The effect of this can always be exhibited, and an unpleasant high frequency sound can be reduced.

  In the present embodiment, the side branch type silencer is arranged around the electric blower, but the arrangement is not limited, and a recess (groove or hole) is formed with respect to the passage through which the sound passes. ) Are arranged in the vertical direction, the same effect can be obtained. Furthermore, instead of the side branch type, a generally known Helmholtz type silencer that is determined by the depth of the recess, the cross-sectional area, and the inner volume of the space behind it is arranged perpendicularly to the direction in which sound passes. The effect is obtained. If you set up several recesses with different depths as much as possible, it will be a muffler that is robust against fluctuations in the number of revolutions, and you can set the number of revolutions accordingly. Therefore, it is possible to realize control that makes smoother changes.

  In the present embodiment, the commutator motor is provided with a rotational speed detection means to control the rotational speed of the electric blower with high accuracy. However, the rotational speed and the current value flowing through the electric blower are one-to-one. It may be realized by current detection using a current sensor instead of rotation speed detection. Other than the commutator motor, an inverter-driven brushless motor that uses a magnet to detect the rotor position, an SR motor, and the like can easily detect the rotational speed, and can be combined with control means such as PWM and PAM. There exists an advantage which is easy to comprise a silencer system like an embodiment.

(Embodiment 2)
The second embodiment of the present invention will be described below with reference to FIGS. The same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  FIG. 5 shows an electric blower in which side branch type silencers 111 and 112 are arranged around the electric blower 110 as in the first embodiment, using the electric blower 110 with nine impellers 301 (Z = 9). FIG. 6 is a characteristic diagram showing the relationship between the air volume, the rotational speed, and the input at that time. In FIG. 6, three characteristic curves are drawn, and these show characteristic curves corresponding to the three operating positions (strong, medium, and weak) of the vacuum cleaner 101. Among these, strong performs stepwise rotational speed control as in the first embodiment, and medium and weak perform control in which the rotational speed from the open air volume to sealing is constant. From FIG. 6, there are four rotation speeds N1 to N4 as the number of rotations at which the electric blower 110 is operated. Specifically, N1 is 36000 r / min (600 Hz), N2 is 42000 r / min (700 Hz), N3 is 48000 r / min (800 Hz), and N4 is 24000 r / min (400 Hz). At this time, the fundamental frequencies of the generated NZ sounds are N1: 5400 Hz, N2: 6300 Hz, N3: 7200 Hz, and N4: 3600 Hz, respectively. Furthermore, when considering up to higher frequencies for each NZ sound, the depth of the concave portion of the side branch to be set is a considerable number, but a frequency of 10 kHz or higher is difficult to hear by human ears. Assuming that they are ignored, for N1 to N3, only the fundamental frequency is considered, and for N4, up to a second order term is taken into consideration and become 3600 Hz and 7200 Hz. Accordingly, the total number of high-frequency sounds to be dealt with is 5, but 7200 Hz overlaps with the fundamental frequency of N3, so that the number of side branch recesses actually provided is only four. Therefore, as shown in FIG. 5, four types of recesses are provided, and the depth may be set for each of them according to the mathematical formula shown in the first embodiment.

  As described above, according to the present embodiment, each driving position is set such that the high-order frequency of a high-frequency sound at a certain driving position overlaps with the frequency of a high-frequency sound at a higher input driving position. Thus, since the number of concave portions of the side branch can be reduced, space saving can be achieved.

  Needless to say, the same applies to the case of a Helmholtz type silencer.

  As described above, the electric blower of the electric vacuum cleaner according to the present invention is also useful in devices other than the electric vacuum cleaner where high frequency sound using a centrifugal fan is a problem.

Sectional drawing of the vacuum cleaner in Embodiment 1 of this invention Partial sectional view of the electric blower Control block diagram of the vacuum cleaner (A) Characteristic diagram of rotational speed with respect to air volume of the vacuum cleaner (b) Characteristic diagram of input with respect to air volume of the vacuum cleaner Sectional drawing of the electric blower in Embodiment 2 of this invention (A) Characteristic diagram of rotational speed with respect to air volume of the vacuum cleaner (b) Characteristic diagram of input with respect to air volume of the vacuum cleaner Partial cross-sectional view of a soundproofing cylinder showing the silencing configuration of a conventional vacuum cleaner

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Electric vacuum cleaner 110 Electric blower 111 Silencer 112 Silencer 113 Concave part 202 Dust collection chamber 203 Dust collection bag 204 Electric blower chamber 205 Suction port 206 Communication hole 207 Bulkhead 208 Prefilter 209 Exhaust port 210 Exhaust filter 211 Support rubber mae 212 Support Rubber shaft 213 Soundproof cylinder 214 Control means 215 Rotational speed detection means 301 Impeller 302 Blade 303 Air guide 304 Casing 305 Air inlet 306 Electric motor 307 Bearing 308 Rotor 309 Rotating shaft 310 Stator 311 Commutator 312 Carbon brush 313 Bracket 315 Spout

Claims (10)

A plurality of electric blowers having an intake port and an exhaust port, which are determined by an integral multiple of the product of the electric fan provided with a centrifugal fan, and the number of blades of the centrifugal fan and the number of rotations disposed in the vicinity of the exhaust port of the electric fan. Resonance-type silencer having a plurality of recesses that resonate with the frequency, rotational speed detection means for detecting the rotational speed of the electric blower, and a signal from the rotational speed detection means to receive the rotational speed of the electric blower. Control means for controlling the rotation speed so as to approach a predetermined target rotation speed set in advance, and the control means corresponds to the resonance frequency of the resonant silencer in the predetermined air volume section. A vacuum cleaner characterized in that the high frequency sound generated at the frequency is silenced by controlling the rotation speed to be constant. The electric vacuum cleaner according to claim 1, wherein the resonance muffler is a side branch method determined only by the depth of the recess. The vacuum cleaner according to claim 1, wherein the resonance silencer is a Helmholtz method determined by the depth of the recess, the cross-sectional area, and the inner volume of the back space. In the air volume range from the maximum air volume that opens the suction port of the vacuum cleaner to the air volume that narrows the suction port and the suction work rate is close to the peak, the control means controls the rotation speed of the electric blower to be constant. The electric vacuum cleaner according to any one of claims 1 to 3, wherein a plurality of sections are provided. The control means is characterized in that the rotational speed of the electric blower that is controlled so as to be constant in each air volume section is set to increase stepwise as the air volume section moves from a large air volume section to a small air volume section. The electric vacuum cleaner according to claim 4. 6. The electric vacuum cleaner according to claim 5, wherein the electric blower is set so that the number of rotations and input are maximized in the vicinity of the air volume at which the suction work rate reaches a peak. In the air volume range from the vicinity of the air volume at which the suction work rate reaches its peak to the operation of the protective device with the suction port narrowed down or closed, the control means controls the air volume section to control the rotation speed of the electric blower to be constant. The vacuum cleaner according to any one of claims 1 to 4, wherein one or a plurality of sections are provided. The electric vacuum cleaner according to any one of claims 1 to 3, wherein the number of rotations of the electric blower is constant in a range of air volume from the maximum air volume until the suction port is narrowed and the protective device operates in the vicinity of or in the vicinity of the airtight seal. Multiple operating positions where the input (rotation speed) of each position is set so that the frequency of the low-order high-frequency sound at a certain input position overlaps with the frequency of the high-order high-frequency sound at an input position lower than the above position. The vacuum cleaner of Claims 1-8 provided with these. The electric vacuum cleaner according to any one of claims 1 to 9, wherein an inverter-driven brushless motor is used as the electric blower.

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