Silencer for motor and vacuum cleaner including the same

Abstract

To reduce noise of a vacuum cleaner.SOLUTION: A vacuum cleaner includes: a cleaner body 1 for storing an electric blower 40; an error microphone 62 for detecting noise of the electric blower 40; a band-pass filter 63 for filtering a signal detected by the error microphone 62; delay means 64 for controlling a phase of a signal which has passed through the band-pass filter 63 so as to delay the signal; gain adjustment means 65 for adjusting amplitude of the signal delayed by the delay means 64; and a speaker 61 to be driven by the signal gain-adjusted by the gain adjustment means 65 so as to emit control sound to perform interference with respect to the noise of the electric motor 40. The speaker 61 is arranged to allow an emission direction of the control sound from the speaker 61 to be opposed to an emission direction of the noise of the electric blower 40.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a silencer for an electric motor and a vacuum cleaner equipped with the same. [Background technology]

[0002] Vacuum cleaners clean floors and other surfaces by sucking in (inhaling) air containing dust. This suction creates noise. This noise is caused by the operating sound of the motor built into the electric blower, the sound generated when the vibration and sound of the electric blower are transmitted to the vacuum cleaner body, and airflow noise caused by turbulence generated by the collision of airflows during intake and exhaust. This type of noise is unpleasant for users and, ultimately, is a nuisance to neighboring residents.

[0003] Therefore, measures have been taken to reduce the noise made by vacuum cleaners. In addition to passive methods such as sound absorption and blocking, active methods have been proposed that utilize wave interference by adding sound waves of the same amplitude but in opposite phase to reduce the noise made by vacuum cleaners.

[0004] Such active noise reduction technology is described, for example, in Patent Document 1. In Patent Document 1, the phase and amplitude of the rotation speed signal of the electric blower detected by a rotation sensor are adjusted by a delay circuit and an amplifier so that the sound pressure signal detected by a microphone is minimized, and a control sound is output from a speaker to silence the noise. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 7-155275 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the technology described in Patent Document 1, the direction of noise emission from the electric fan (the noise source) and the direction of noise emission from the speaker are not taken into consideration, so there are places where the noise is out of phase and places where it is in phase due to interference between the waves. For this reason, in Patent Document 1, while the noise at the microphone position can be reduced, noise reduction at other positions is not sufficient, and there are problems with silencing noise at positions other than the microphone, and ultimately silencing noise throughout the entire space.

[0007] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a motor silencer that reduces noise generated by an electric motor and an electric blower, and a vacuum cleaner equipped with the same. [Means for solving the problem]

[0008] In order to achieve the above-mentioned object, the present invention provides an electric vacuum cleaner comprising a vacuum cleaner body accommodating an electric blower that generates suction force, an error microphone that detects noise from the electric blower, a bandpass filter that filters a signal detected by the error microphone, a delay means that controls the phase of a signal that has passed through the bandpass filter and delays the signal, a gain adjustment means that adjusts the amplitude of the signal delayed by the delay means, and a speaker that is driven by a signal whose gain has been adjusted by the gain adjustment means and that emits a control sound that interferes with the noise from the electric blower, wherein the speaker is positioned so that the direction in which the control sound is emitted from the speaker is opposite to the direction in which the noise from the electric blower is emitted. Effect of the Invention

[0009] According to the present invention, it is possible to reduce noise generated from an electric motor and an electric blower. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a perspective view showing a state in which the electric vacuum cleaner 100 according to the first embodiment of the present invention is stored in a charging stand in a stick state. [Diagram 2]FIG. 2 is a perspective view of the vacuum cleaner in a handheld state. [Diagram 3] 1 is a cross-sectional view of a vacuum cleaner body 1 to which the present invention is applied, cut along the front-rear direction. [Figure 4] 1 is a cross-sectional view of a cleaner body 1 according to a first embodiment of the present invention, cut along a front-rear direction. [Diagram 5] FIG. 1 is a diagram illustrating interference of sound waves. [Figure 6] FIG. 4 is a diagram showing the noise reduction effect in the present embodiment. [Figure 7] FIG. 11 is a cross-sectional view of a cleaner body 1 according to a second embodiment of the present invention, cut along the front-rear direction. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Each drawing is merely a schematic illustration to allow a sufficient understanding of the present invention. Therefore, the present invention is not limited to the illustrated examples. In addition, in each drawing, common components or similar components are given the same reference numerals, and duplicated explanations thereof will be omitted. Hereinafter, an embodiment of the present invention will be described. EXAMPLES

[0012] A first embodiment of the present invention will be described with reference to Figures 1 to 3. In each figure, from the user's viewpoint, the front is defined as "front", the rear is defined as "rear", the left hand side is defined as "left", the right hand side is defined as "right", the ceiling side is defined as "upper", and the side of the surface to be cleaned is defined as "lower".

[0013] FIG. 1 is a perspective view showing a state in which a vacuum cleaner 100 according to a first embodiment of the present invention is stored in a charging stand in a stick state.

[0014] The vacuum cleaner 100 comprises a vacuum cleaner body 1, a vacuum cleaner head 10, a handle portion 12, and an extension tube 20. The vacuum cleaner 100 can be changed into various usage states such as a handheld state and a stick state for cleaning. The charging stand 70 in which the vacuum cleaner 100 is stored stores the vacuum cleaner 100 in the stick state, and comprises a base member 71, three stand members 72, and a holder member 73.

[0015] In the vacuum cleaner 100, the vacuum cleaner main body 1 is placed on a holder member 73 so that the handle portion 12 and the switch portion 12a face forward. In the charging base 70, the holder member 73 is adapted to receive an output plug of an AC adapter for charging the battery 30 (see FIG. 2) attached to the vacuum cleaner 100. When the vacuum cleaner 100 is set on the charging base 70, the output plug is connected to an input jack of the vacuum cleaner 100, enabling charging.

[0016] Furthermore, the holder member 73 has a holding portion (recess) that engages with an engaging portion of the extension tube 20. This allows the extension tube 20 to be stored compactly, as shown in Fig. 1. This allows the charging stand 70 itself to be configured without electrical components, reducing costs and improving productivity. Also, since there is no change in electrical connection whether the stand member 72 is present or not, product reliability can be ensured.

[0017] Furthermore, when the electric vacuum cleaner 100 is in operation, that is, when cleaning is performed, air containing dust flows from the suction port of the vacuum cleaner head 10 through the extension tube 20 to the vacuum cleaner body 1. The dust then accumulates in a dust case 11 (see FIG. 2) provided in the vacuum cleaner body 1. For this reason, the vacuum cleaner body 1 is provided with an electric blower 40 (see FIG. 3) that generates suction force. In this embodiment, a silencer is provided for this vacuum cleaner body 1. The vacuum cleaner body 1 will be described below.

[0018] FIG. 2 is a perspective view of the vacuum cleaner used in a handheld state. In FIG. 2, the vacuum cleaner main body 1 has a dust case 11, a handle section 12, a main body section 13, and a storage section 14. Here, the main body section 13 is connected to the extension tube 20 and has a connection port 13a through which the sucked air flows in. The dust case 11 is provided on the air ventilation path and accumulates dust contained in the air sucked in via the connection port 13a. The handle section 12 is held by a user and has a switch section 12a for operating the vacuum cleaner 100. The storage section 14 has various mechanisms for generating suction force for the air and an exhaust port 15. The storage section 14 is provided with a battery 30 as a power source and an electric blower 40 (see FIG. 3) that operates with power supplied from the battery 30. The electric blower 40 is provided with an electric motor having a rotating shaft and a blower fixed to the rotating shaft and rotated by the electric motor.

[0019] Here, the internal structure of the vacuum cleaner body 1 constituting the electric vacuum cleaner will be described. Fig. 3 is a cross-sectional view of the vacuum cleaner body 1 to which the present invention is applied, cut along the front-rear direction. Electric blower 40 of this embodiment is disposed in the vacuum cleaner body 1 so that the rotating shaft connecting the electric motor and the blower faces in the front-rear direction.

[0020] 3, the intake air drawn in by electric blower 40 via connection port 13a flows in the direction indicated by the arrow. That is, the intake air flows from connection port 13a to dust case 11 to storage section 14, and is exhausted from exhaust port 15. In storage section 14, the intake air passes through filter 50 and then flows through electric blower 40. Then, the intake air is exhausted from exhaust port 15. For this reason, connection port 13a, electric blower 40, and battery 30 are arranged in this order from the upstream side in the flow direction of the intake air.

[0021] Electric blower 40 is housed in a cylindrical casing 41 and attached to vacuum cleaner body 1 via anti-vibration rubber 42. Anti-vibration rubber 42 is arranged in the front and rear directions of vacuum cleaner body 1. Casing 41 has an open section 41a that is open on the rear side. Exhaust air discharged from electric blower 40 flows rearward along casing 41, is discharged from open section 41a, and is then discharged from exhaust port 15 formed in vacuum cleaner body 1. In this embodiment, by providing a soundproofing device in vacuum cleaner body 1, the noise of electric blower 40 can be reduced, and therefore the noise of vacuum cleaner body 1 can be reduced.

[0022] FIG. 4 is a cross-sectional view of the cleaner body 1 according to the first embodiment of the present invention cut along the front-rear direction.

[0023] The silencer of this embodiment includes an error microphone 62 that detects noise from a noise source, a bandpass filter 63 that filters the noise signal detected by the error microphone 62 to a desired frequency band, a delay means 64 that controls the phase of a signal that has passed through the bandpass filter 63 and delays the signal, a gain adjustment means 65 that adjusts the amplitude of the signal delayed by the delay means 64, and a speaker 61 that is driven by a signal whose gain has been adjusted by the gain adjustment means 65 and emits a control sound that interferes with the noise. The delay means 64 delays the signal so that it has an inverse phase to the phase of the noise. The speaker 61 has a circular sound emission surface and is disposed in the vacuum cleaner body 1 so that the central axis of the circle faces the front-rear direction. In the figure, the bandpass filter 63, the delay means 64, and the gain adjustment means 65 are shown outside the vacuum cleaner body 1, but these means may be mounted, for example, in a control unit housed in the vacuum cleaner body 1.

[0024] When the silencer of this embodiment is applied to the first rotational component that is a problem in a vacuum cleaner, the procedure is as follows.

[0025] First, error microphone 62 is installed near electric blower 40, which is considered to be the sound source of the primary rotational component, and speaker 61 is also installed near electric blower 40. In this embodiment, speaker 61 and electric blower 40 are installed so that the axial direction of speaker 61 and the axial direction of the rotation shaft of electric blower 40 are in the same direction (front-to-back direction). In addition, open portion 41a of casing 41 is formed in a position facing speaker 61.

[0026] Furthermore, the pass frequency band of the band pass filter 63 is set so that the first-order rotational component can pass. Next, the band pass filter 63 extracts the first-order rotational component from the signal detected by the error microphone 62, and the delay means 64 and gain adjustment means 65 adjust the phase and amplitude so that the first-order rotational component is minimized. Finally, a control sound that interferes with the noise is output from the speaker 61. This makes it possible to reduce the first-order rotational component. Note that although the first-order rotational component is the subject of this embodiment, theoretically it is also applicable to other rotation order components.

[0027] Here, in this embodiment, the error microphone 62 is installed on the lower side of the electric blower 40 facing the paper surface, but there is no problem in installing it in another position as long as it can detect noise that is highly correlated with the sound source to be silenced. In addition, from the above considerations, it is preferable to install the speaker 61 in a position facing the exhaust port surface of the electric blower 40, which is the sound source surface, as shown in FIG. 4. In particular, in this embodiment, the rear side of the casing 41 is provided with an opening 41a, and exhaust sound is emitted from this opening 41a together with the exhaust air of the electric blower 40 (see arrow). The direction of emission of the sound source (control sound) from the speaker 61 faces the direction of emission of the exhaust sound from the opening 41a as shown by the arrow, so the sound source from the speaker 61 can effectively reduce the exhaust sound of the electric blower 40.

[0028] Fig. 5 is a diagram explaining the interference of sound waves. When using the interference of sound waves to reduce noise by generating sound waves from a speaker with the same amplitude and in opposite phase to the sound source as in this embodiment, as shown on the left side of the figure, the sound waves from the sound source and the speaker interfere with each other, creating places where the sound is in opposite phase and places where it is in the same phase, resulting in places where the sound is lower and places where the sound is higher.

[0029] If the positions of the sound source and the speaker can be perfectly aligned as shown on the right side of the figure, the phases of the sound waves from the sound source and the speaker will be perfectly in phase and of the same amplitude, making it possible to reduce noise throughout the entire space. In this embodiment, in order to approach this ideal position, the axis of the speaker 61 is arranged coaxially with the rotation axis of the electric blower 40, which is the sound source, and the radiating surface of the speaker 61 is arranged as close as possible to the exhaust side surface of the electric blower 40. Furthermore, the areas of the radiating surface on the exhaust side of the electric blower 40 and the speaker 61 are almost equal. As a result, the radiated sound (noise) radiated in the axial direction of the electric blower 40, which is the sound source, is in the same direction as the radiated sound (control sound) emitted from the speaker 61, and since they are close to each other with almost the same area, it is possible for the sound waves to cancel each other out between the surfaces.

[0030] Fig. 6 is a diagram showing the noise reduction effect of this embodiment. In Fig. 6, the horizontal axis indicates the distance from the vacuum cleaner body 1, and the vertical axis indicates the peak level of the first rotational component. For comparison, the case where the silencer of this embodiment is not applied is also shown. As shown in Fig. 6, it can be seen that in the vacuum cleaner using the silencer of this embodiment, noise is reduced in all areas from 0.1 m to 0.5 m away from the vacuum cleaner body 1.

[0031] In the above embodiment, the speaker 61 and the electric blower 40 are installed so that the axial direction of the speaker 61 and the axial direction of the rotating shaft of the electric blower 40 are in the same direction (front-rear direction), but the speaker 61 may be installed on the outer periphery (radial outer side) of the electric blower 40. In this embodiment, the outer periphery (radial outer side) of the electric blower 40 is covered with the casing 41, an opening 41a is provided on the rear side of the casing 41, and the noise of the electric blower 40 is radiated from this opening 41a. For example, the opening 41a may be closed on the rear side of the casing 41, and an opening may be formed on the outer periphery (radial outer side) of the casing 41. In this case, it is preferable to install the speaker 61 so that the sound from the speaker 61 is radiated toward the opening formed on the outer periphery (radial outer side) of the casing 41. In other words, the speaker 61 is installed so that the axial direction of the speaker 61 faces the opening. When multiple openings are formed on the outer periphery (radially outward) of casing 41, it is preferable to arrange multiple speakers 61 in accordance with the number of openings. With this configuration, it is possible to reduce sound radiating radially outward from electric blower 40.

[0032] As described above, this embodiment can provide a noise suppressor that is effective for reducing noise from a vacuum cleaner. Also, when the axial direction of speaker 61 and the axial direction of the rotary shaft of electric blower 40 are arranged in the same direction (front-rear direction), one speaker 61 is sufficient, so the cost of installing the noise suppressor can be reduced. EXAMPLES

[0033] Next, a second embodiment will be described with reference to Fig. 7. Fig. 7 is a cross-sectional view of a cleaner body 1 according to a second embodiment of the present invention cut along the front-rear direction. Hereinafter, the silencer according to the second embodiment will be described with reference to Fig. 7.

[0034] In addition to the configuration of Example 1 shown in Fig. 4, Example 2 is provided with a shielding plate 43 so as to cover the outer periphery of casing 41. There are considered to be two types of noise radiated from electric blower 40. One is noise radiated in the axial direction of the rotating shaft of electric blower 40, and the other is noise radiated in the radial direction.

[0035] The latter noise radiated in the radial direction is considered to be radiated from the cylindrical surface of casing 41. Shielding plate 43 has a cylindrical shape and is attached so as to cover the outer periphery of the cylindrical surface of casing 41, and has the function of blocking noise radiated in the radial direction. As a result, the noise radiated from electric blower 40 is controlled only in the axial direction, thereby achieving a higher noise reduction effect.

[0036] The casing 41 arranged around the outer periphery of the electric blower 40 has the effect of reducing noise radiated in the radial direction of the electric blower 40, but in this embodiment, in order to further reduce noise radiated in the radial direction, a shielding plate 43 is provided to cover the outer periphery of the casing 41. EXAMPLES

[0037] In the first and second embodiments, an example is shown in which the silencer is applied to a vacuum cleaner. However, the present invention is not limited to vacuum cleaners, and can also be applied, for example, as a silencer for an electric motor used in a power tool or the like.

[0038] The electric motor is used to generate a driving force. The noise suppressor for the electric motor comprises an error microphone that detects the noise of the electric motor, a bandpass filter that filters the signal detected by the error microphone, a delay means that controls the phase of the signal that has passed through the bandpass filter and delays the signal, a gain adjustment means that adjusts the amplitude of the signal delayed by the delay means, and a speaker that is driven by the signal whose gain has been adjusted by the gain adjustment means and emits a control sound that interferes with the noise of the electric motor. As in the first and second embodiments, the speaker is arranged so that the emission direction of the control sound from the speaker faces the emission direction of the noise of the electric motor.

[0039] In addition, a casing is provided around the outer periphery of the motor, and the speaker is arranged so that its axial direction is the same as the axial direction of the rotating shaft of the motor. In this case, it is preferable that the speaker shaft is arranged coaxially with the rotating shaft of the motor.

[0040] Furthermore, it is preferable that the casing has an opening formed in a position opposite the speaker.

[0041] Furthermore, it is preferable to provide a shielding plate on the outer periphery of the casing.

[0042] According to this embodiment, the noise generated from the electric motor can be reduced.

[0043] The present invention is not limited to the above-mentioned embodiment, and various modifications are included. For example, the above-mentioned embodiment has been described in detail to easily explain the present invention, and is not necessarily limited to those including all of the configurations described. Also, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Also, it is possible to add, delete, or replace a part of the configuration of each embodiment with another configuration. [Explanation of symbols]

[0044] 1...vacuum cleaner body, 10...vacuum cleaner head, 11...dust case, 12...handle section, 13...main body section, 14...storage section, 15...exhaust port, 20...extension tube, 30...battery, 40...electric blower, 41...casing, 41a...opening section, 42...vibration isolating rubber, 43...shielding plate, 50...filter, 61...speaker, 62...error microphone, 63...bandpass filter, 64...delay means, 65...gain adjustment means, 100...electric vacuum cleaner

Claims

1. An electric vacuum cleaner comprising: a vacuum cleaner body accommodating an electric blower that generates suction force; an error microphone that detects noise from the electric blower; a bandpass filter that filters a signal detected by the error microphone; delay means that controls the phase of a signal that has passed through the bandpass filter and delays the signal; gain adjustment means that adjusts the amplitude of the signal delayed by the delay means; and a speaker that is driven by a signal whose gain has been adjusted by the gain adjustment means and that emits a control sound that interferes with the noise from the electric blower, The electric vacuum cleaner according to claim 1, wherein the speaker is disposed so that a direction in which a control sound is emitted from the speaker faces a direction in which a noise of the electric blower is emitted.

2. 2. The vacuum cleaner according to claim 1, A casing is provided to cover an outer periphery of the electric blower, The electric vacuum cleaner according to claim 1, wherein the speaker is disposed so that an axial direction of the speaker is the same as an axial direction of a rotation shaft of the electric blower.

3. 3. The vacuum cleaner according to claim 2, 13. An electric vacuum cleaner, wherein the axis of the speaker is arranged coaxially with the rotation axis of the electric blower.

4. 3. The vacuum cleaner according to claim 2, The vacuum cleaner according to claim 1, wherein the casing has an opening formed at a position opposite the speaker.

5. 3. The vacuum cleaner according to claim 2, The vacuum cleaner further comprises a shielding plate covering an outer periphery of the casing.

6. A noise suppression device for an electric motor comprising: an error microphone for detecting noise of an electric motor generating a driving force; a band pass filter for filtering a signal detected by said error microphone; a delay means for controlling the phase of a signal that has passed through said band pass filter and delaying the signal; a gain adjustment means for adjusting the amplitude of the signal delayed by said delay means; and a speaker that is driven by a signal whose gain has been adjusted by said gain adjustment means and emits a control sound that interferes with the noise of the electric motor, 1 is a block diagram showing a noise suppression device for a motor according to an embodiment of the present invention;

7. 7. A silencer for an electric motor according to claim 6, A casing is provided to cover an outer periphery of the electric motor, 13. A silencer for an electric motor, wherein the speaker is disposed so that an axial direction of the speaker is the same as an axial direction of a rotating shaft of the electric motor.

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