Patent Grant
9318091
The present invention relates to an air conditioner, and more specifically, to an air conditioner capable of reducing noise during operation, such as blower sound.
Conventionally, in order to reduce noise of an air conditioner during operation, such as blower sound, it has been proposed to include an active noise control mechanism (also called active noise cancellation) for superimposing a canceling sound wave which is in antiphase to noise to cancel the noise.
For example, in Patent Literature 1, a microphone and a flat plate speaker are placed in a predetermined space within an indoor unit of an air conditioner, and the flat plate speaker radiates a sound wave having substantially the same frequency and substantially the same sound pressure level as, and being in substantially antiphase to, noise at a specific frequency detected by the microphone, to thereby perform noise cancellation effectively.
Further, Patent Literature 2 discloses a technology in which operation sound detecting means, reference operation sound setting means, and correction sound emitting means are provided and, when a temporal fluctuation amount of operation sound is larger than a predetermined level, the correction sound emitting means compares the operation sound to a reference operation sound set by the reference operation sound setting means, and radiates a correction sound so that a combined sound obtained when the correction sound is combined with the operation sound becomes the reference operation sound.
Still further, Patent Literature 3 discloses a technology in which a plurality of microphones, controllers, and speakers are provided to constitute independent control systems, respectively, and the microphones and the speakers are disposed at predetermined intervals along an axial direction of a transverse fan.
In active noise cancellation, a sound wave (noise) traveling through a closed space, such as a duct, which is a one-dimensional sound field (sound field in which the spread of sound is restricted in one direction), is similar to a plane wave, and hence the noise can be canceled well by an antiphase sound wave radiated from a cancellation sound source, and noise cancellation can be performed effectively. However, in a three-dimensional sound field (sound field in which sound spreads in random directions) such as free space propagation, the sound wave is a spherical wave. Thus, there occur a region in which the noise is overcome by an antiphase sound wave and a region in which the noise level contrarily increases because of in-phase sound waves. It is therefore impossible for the current technologies to achieve noise cancellation on a practical level.
As for noise cancellation of blower noise, an air conditioning duct apparatus has a duct as a blower passage, which can be a one-dimensional sound field, and hence it is possible to apply active noise cancellation relatively easily. However, in an air conditioner to be used so that an indoor unit is mounted on an indoor wall surface, there is no blower passage regarded as a one-dimensional sound field, and hence, even if a cancellation sound source is provided in a blower passage, just as in the case where active noise cancellation is performed in a three-dimensional sound field as described above, it sounds rather noisy depending on the place in the room. This is not practical at all. In fact, various technologies of reducing operation noise have been studied as exemplified by Patent Literatures 1 to 3, but there are no cases where those technologies are put into practical use. In other words, it is understood that effective noise cancellation of blower noise needs a portion which can be a one-dimensional sound field having a certain length in a blower passage, especially on the downstream side of blower means.
In view of the above-mentioned problem, it is therefore an object of the present invention to obtain a sufficient noise canceling effect in a wall-mounted air conditioner.
In order to achieve the above-mentioned object, according to the present invention, there is provided an air conditioner to be used by being mounted on an indoor wall surface, including: a casing; an inlet provided to the casing, for introducing air in a room; an outlet provided to the casing, for delivering conditioned air, which is obtained by conditioning air introduced from the inlet, to the room; blower means for moving air from the inlet to the outlet; a blower passage communicating between the inlet and the outlet; and air flow direction changing means and sound emitting means, which are provided in a vicinity of the outlet, in which the air flow direction changing means is operable to form a duct-like outlet passage in the vicinity of the outlet, and, in the duct-like outlet passage, the sound emitting means radiates a sound wave for canceling out operation noise including blower sound of the blower means.
According to this configuration, the duct-like outlet passage, which can be a one-dimensional sound field, is formed in the vicinity of the outlet located on the downstream side of the blower means in the blower passage. Then, in this duct-like outlet passage, the sound wave for canceling out the operation noise including the blower sound of the blower means is radiated from the sound emitting means. Therefore, the operation noise is efficiently canceled out while passing through the duct-like outlet passage. With this, the noise to be radiated into the room can be reliably reduced, and a sufficient noise canceling effect can be obtained.
Further, in the air conditioner of the present invention having the above-mentioned configuration, the air flow direction changing means may include an air flow guide panel, which is vertically pivotable for opening and closing the outlet, and when the duct-like outlet passage is to be formed, the air flow guide panel may pivot so as to be open upward and may be disposed so as to extend a lower surface of the blower passage while covering over the outlet.
According to this configuration, the inner surface of the air flow guide panel, the upper surface, the lower surface, and the left and right side surfaces of the blower passage, and a part of the front surface of the casing together form the duct-like outlet passage for delivering air toward the ceiling of the room, and further, the air flow guide panel covers the outlet. With this, there are obtained effects that the blower sound of the blower means is less likely to diffuse and that the air flow guide panel insulates the noise to be radiated into the room, which can contribute to the reduction of noise.
Further, in the air conditioner of the present invention having the above-mentioned configuration, the air flow direction changing means may include an air flow guide panel, which is vertically pivotable for opening and closing the outlet, and when the duct-like outlet passage is to be formed, the air flow guide panel may pivot so as to be open downward and may be disposed so as to extend an upper surface of the blower passage while covering over the outlet.
According to this configuration, the inner surface of the air flow guide panel, the upper surface, the lower surface, and the left and right side surfaces of the blower passage, and a part of the lower surface of the casing together form the duct-like outlet passage for delivering air toward the floor of the room, and further, the air flow guide panel covers the outlet. With this, there are obtained effects that the blower sound of the blower means is less likely to diffuse and that the air flow guide panel insulates the noise to be radiated from the outlet, which can contribute to the reduction of noise. When the air conditioner further includes the auxiliary panel, which is disposed so as to extend the lower surface of the blower passage when the duct-like outlet passage is to be formed, the duct-like outlet passage having a sufficient length can be reliably formed.
Note that, in order that a closed space through which sound can travel as a plane wave be formed in the vicinity of the outlet, the length of the air flow guide panel in the blower direction needs to be at least more than the height of the outlet at the position at which the sound emitting means is installed.
Further, the air conditioner of the present invention having the above-mentioned configuration may further include reference sound detecting means for detecting a sound wave of the operation noise, in which the sound emitting means may radiate a sound wave in antiphase to the sound wave detected by the reference sound detecting means.
According to this configuration, it is possible to detect sound which is actually generated when the blower means is driven and to radiate a canceling sound wave against the actually generated sound. Thus, the accuracy of the active noise cancellation can be increased. In this case, it is desired to dispose the reference sound detecting means on the upstream side of the sound emitting means in the duct-like outlet passage so as not to detect a sound wave radiated from the sound emitting means, which is not a detection target of the reference detecting means.
Further, the air conditioner of the present invention having the above-mentioned configuration may further include correction sound detecting means for detecting a noise level after the operation noise is canceled out, in which the sound wave to be radiated from the sound emitting means may be corrected so that the noise level detected by the correction sound detecting means falls within a predetermined range.
According to this configuration, the accuracy of the active noise cancellation can be increased more by feedback control of the noise level after cancellation. In this case, it is desired to dispose the correction sound detecting means on the downstream side of the sound emitting means in the duct-like outlet passage so as not to detect operation noise, which is not a detection target of the correction detecting means.
Further, the air conditioner of the present invention having the above-mentioned configuration may further include a plurality of vertical louvers in the outlet, in which a plurality of the sound emitting means may be disposed for respective sections divided by the plurality of vertical louvers.
According to this configuration, the blower passage can be divided into small sections, and hence the blower sound of the blower means is even less likely to diffuse, and the noise canceling effect can be obtained satisfactorily. It is more desired that the width of the section be 85 mm or less. According to this configuration, the width of the section becomes equal to or less than about ½ of the wavelength of a sound wave of 2,000 Hz. Thus, a sound wave passing through the section can be regarded as a substantially plane wave, that is, the inside of the section can be regarded as a one-dimensional sound field. In particular, a sufficient noise canceling effect can be obtained in a low frequency range of 2,000 Hz or less, where the active noise cancellation is targeted.
Further, the air conditioner of the present invention having the above-mentioned configuration may further include a plurality of vertical louvers in the outlet, in which a plurality of the sound emitting means and a plurality of the reference sound detecting means may be disposed for respective sections divided by the plurality of vertical louvers, thereby performing canceling control of the operation noise independently for each of the sections.
According to this configuration, canceling control against actually generated sound can be performed for each small sectioned space. Thus, the accuracy of the active noise cancellation can be increased. It is more desired that the width of the section be 85 mm or less. According to this configuration, the width of the section becomes equal to or less than about ½ of the wavelength of a sound wave of 2,000 Hz. Thus, a sound wave passing through the section can be regarded as a substantially plane wave, that is, the inside of the section can be regarded as a one-dimensional sound field. In particular, a sufficient noise canceling effect can be obtained in a low frequency range of 2,000 Hz or less, where the active noise cancellation is targeted.
Further, in the air conditioner of the present invention having the above-mentioned configuration, a plurality of the correction sound detecting means may each be disposed so that the sound emitting means is sandwiched between the reference sound detecting means and the correction sound detecting means in a blower direction.
According to this configuration, for example, the air flow guide panel pivots so as to be open upward in the case of cooling and so as to be open downward in the case of heating and is disposed so as to cover over the outlet. In either case of upward opening or downward opening, detection target sound can be detected satisfactorily by the sound detecting means which are disposed on both the upstream side and the downstream side of the sound emitting means.
Further, in the air conditioner of the present invention having the above-mentioned configuration, the sound emitting means may be disposed on the air flow guide panel. According to this configuration, the speaker faces the casing of the indoor unit, and hence, owing to the diffraction effect, a sound wave radiated from the speaker can be prevented from leaking into the room. Thus, the noise canceling effect is increased more.
Further, in the above-mentioned configuration of the present invention, the correction sound detecting means, the correction sound detecting means, and the reference sound detecting means may be disposed on the air flow direction changing means so that the sound emitting means is sandwiched between the correction sound detecting means and the reference sound detecting means in a blower direction, and the correction sound detecting means and the reference sound detecting means may be configured to be switchable.
According to this configuration, for example, the air flow direction changing means may pivot so as to be open upward in the case of cooling and so as to be open downward in the case of heating and may be disposed so as to cover over the outlet. In either case of upward opening or downward opening, the reference sound detecting means and the correction sound detecting means may be disposed on the upstream side and the downstream side of the sound emitting means, respectively.
According to the air conditioner of the present invention, the duct-like outlet passage, which can be a one-dimensional sound field, is formed in the vicinity of the outlet, and in this duct-like outlet passage, the operation noise including the blower sound of the blower means is subjected to active noise cancellation. Thus, the operation noise to be radiated into the room can be reliably reduced, and a sufficient noise canceling effect can be obtained.
Hereinafter, embodiments of the present invention are described with reference to the drawings. In the embodiments of the present invention, a description is given of an example of a separate air conditioner including an indoor unit to be mounted on an indoor wall surface and an outdoor unit to be mounted outdoors for stationary use.
As illustrated in
The cabinet 2 is provided with a claw portion (not shown) on a rear side surface thereof. The cabinet 2 is supported by a mounting plate (not shown) which is mounted on a side wall W1 of the room at a height position closer to a ceiling S in a manner that the claw portion is engaged with the mounting plate. An outlet 5 is provided in a gap between a lower end portion of the front panel 3 and a lower end portion of the cabinet 2. The outlet 5 is formed into a substantially rectangular shape extending in a width direction of the indoor unit 1, and is provided so as to face downward in the front.
Inside the indoor unit 1, a blower passage 6 communicating to the outlet 5 from the inlet 4 is formed. A fan 7 as blower means for delivering air is disposed in the blower passage 6. A fan to be suitably used as the fan 7 is a crossflow fan (transverse fan), but other types of fans may be used. In the blower passage 6, on the downstream side of the fan 7, there are formed an upper wall 6a and a lower wall 6b which guide the air delivered by the fan 7 downward in the front and whose cross-sectional area increases more on the downstream side. Note that, although not illustrated, the blower passage 6 also has left and right side walls which are flush with left and right side walls to which the fan 7 is pivotally supported.
On the upper wall 6a of the blower passage 6, a speaker 21 as sound emitting means is provided so as to face the blower passage 6. As the speaker 21, a small-footprint flat plate speaker is suitably used, but other types of speakers including a cylindrical speaker may be used. Alternatively, it is possible to use a speaker having the directivity in a blower direction.
In the vicinity of the outlet 5, an air flow guide panel 20 (vertical air flow direction changing means) which is pivotally supported to open and close the outlet 5 is provided.
In the operation stop state of the air conditioner, the air flow guide panel 20 is disposed at a position to close the outlet 5 as illustrated in
The air flow guide panel 20 is pivotally supported at two vertical positions by two upper and lower different shafts (not shown) so that a regulating portion (not shown) for regulating one of the two shafts as a pivot shaft while releasing the other shaft and a moving portion (not shown) for pivoting the air flow guide panel 20 about the pivot shaft may operate in a linked manner. For example, in cooling, the air flow guide panel 20 is pivoted counterclockwise as indicated by the arrow A of
In this case, the inner surface of the air flow guide panel 20, the upper surface, the lower surface, and the left and right side surfaces of the blower passage 6, and a part of the front surface of the front panel 3 together form a duct-like outlet passage 10 for changing the direction of air flow upward and delivering air toward the ceiling of the room, and further, the air flow guide panel 20 covers the outlet 5 when the front panel 3 is viewed from the front (from the left of the sheet of
On the other hand, for example, in heating, the air flow guide panel 20 can also be pivoted so as to be open downward as indicated by the arrow B of
Note that, in
Note that, although not illustrated, the indoor unit 1 of the air conditioner according to the present invention may be configured so as to change the direction of air flow to the horizontal direction or the front downward direction through a combination of appropriate selection of the pivot shaft of the air flow guide panel 20 made by the regulating portion and appropriate setting of a pivot angle of the air flow guide panel 20 made by the moving portion.
Further, in the outlet 5, as illustrated in
A width W of the section 15 is set equal to or less than about ½ of the wavelength of a sound wave of 2,000 Hz, and is desirably set to 85 mm or less. With this setting, a sound wave passing through the section 15 can be regarded as a substantially plane wave, that is, the inside of the section can be regarded as a one-dimensional sound field. In particular, a sufficient noise canceling effect can be obtained in a low frequency range of 2,000 Hz or less, where active noise cancellation is targeted.
At a position opposing the front panel 3, an air filter 8 for collecting and removing dust contained in the air sucked from the inlet 5 is provided. In a space formed between the front panel 3 and the air filter 8, an air filter cleaning device (not shown) for removing the dust accumulated on the air filter 8 is provided. Between the fan 7 and the air filter 8 in the blower passage 6, an indoor heat exchanger 9 having a bent structure provided with pipes (not shown) at a plurality of stages in a plurality of rows is disposed so as to oppose the inlet 4. The indoor heat exchanger 9 is connected to a compressor (not shown) of the outdoor unit placed outdoors, and a refrigeration cycle is operated by the driving of the compressor. Further, an electric dust collector (not shown) is provided between the air filter 8 and the indoor heat exchanger 9.
Next, the principle of operation noise control, which is the feature of the air conditioner according to the present invention, is described while comparing with conventional one. First, the principle of the operation noise control of the air conditioner according to the present invention is described in comparison with the conventional one.
As illustrated in
In the conventional air conditioner not provided with the air flow guide panel 20, as illustrated in
In contrast, the air conditioner according to the present invention includes, as illustrated in
It can be understood from the findings above that the reason why the air conditioner of the present invention exhibits the noise canceling effect is because the duct-like outlet passage through which a sound wave can propagate as a plane wave is formed in the vicinity of the outlet 5. In this sense, the air flow guide panel 20 needs to have a length at least equal to or more than the height L1 of the outlet 5 at the position at which the speaker 21 is installed (the distance from the center of the speaker 21 to the lower surface of the blower passage 6 in the direction perpendicular to the surface on which the speaker 21 is installed).
By the way, the noise canceling effect realized by the air conditioner according to the present invention is a composite effect including not only the noise canceling effect by the duct-like outlet passage but also the actions of (a) sound insulation, (b) reflection and interference, and (c) diffraction by the air flow guide panel 20 itself. That is, owing to (a) the sound insulation effect by the air flow guide panel 20 which is disposed so as to cover over the outlet 5, (b) the reflection and interference effect by the closed space surrounded by the inner surface of the air flow guide panel 20 and the upper surface, the lower surface, and the left and right side surfaces of the blower passage 6, and (c) the diffraction effect obtained because the air flow direction (blowing direction) is front upward or downward, noise is less likely to diffuse in the room, which can contribute to the reduction of noise.
Next, an operation noise control system according to the air conditioner of this embodiment is described with reference to a block diagram of
A control portion 30 is constituted by a microcomputer or the like, and includes, as illustrated in
The speaker driving portion 309 directly receives a signal from the operation mode detecting portion 301 or the fan rpm detecting portion 305 as indicated by dotted lines of
Next, an example of an operation noise control method for the air conditioner of this embodiment having the above-mentioned configuration is described with reference to a flowchart of
For example, when cooling operation is started, first, the indoor unit 1 of the air conditioner receives the signal of the remote control 13 and then the operation detection mode detecting portion 301 detects the operation mode (Step S1). Next, the air flow guide panel 20 operates in accordance with the operation mode and is disposed so as to be open upward while covering over the outlet 5 as illustrated in
Then, the fan 7 is rotationally-driven so that air is sucked into the indoor unit 1 from the inlet 4. The air passes through the blower passage 6 and is delivered into the room from the outlet 5. Noise generated by the indoor unit 1, mainly blower noise generated when the fan 7 is rotationally-driven, is also radiated into the room. As a countermeasure, a preset sound wave is selected in accordance with the operation mode (Step S3), and the selected sound wave is radiated from the speaker 21 (Step S4). In this way, in the duct-like outlet passage 10, the noise, mainly the blower noise generated when the fan 7 is rotationally-driven, can be canceled out, thereby performing active noise cancellation.
According to the operation noise control method in this example, in accordance with the operation mode of the air conditioner, the duct-like outlet passage 10, which can be a one-dimensional sound field, is formed in the vicinity of the outlet 5 located on the downstream side of the fan 7 in the blower passage 6. Then, in this duct-like outlet passage, the sound wave which is preset in accordance with the operation mode is radiated from the speaker 21. Therefore, the operation noise is efficiently canceled out while passing through the duct-like outlet passage 10. With this, the noise to be radiated into the room can be reliably reduced, and a sufficient noise canceling effect can be obtained.
Next, another example of the operation noise control method according to the air conditioner of this embodiment is described with reference to a flowchart of
In the operation noise control method in this example, after that, in Step S13, the rpm of the fan 7 is detected, and in Step S14, the detected rpm of the fan 7 is compared with the rpm of the fan 7 which is set in accordance with the operation mode. When a difference between the detected rpm of the fan 7 and the rpm of the fan 7 which is set in accordance with the operation mode is within a preset range (YES in Step S15), selected sound is radiated from the speaker 21 in Step S16. In other words, when the difference between the detected rpm of the fan 7 and the rpm of the fan 7 which is set in accordance with the operation mode is not within a preset range (NO in Step S15), the processing returns to Step S13, and Steps S13 to S15 are repeated until the difference falls within the range.
The operation noise control method in this example is targeted at steady-state noise, which is relatively stable. Therefore, active noise cancellation can be performed relatively easily.
As illustrated in
As illustrated in
A width W of the section 15 is set equal to or less than about ½ of the wavelength of a sound wave of 2,000 Hz, and is desirably set to 85 mm or less. With this setting, a sound wave passing through the section 15 can be regarded as a substantially plane wave, that is, the inside of the section 15 can be regarded as a one-dimensional sound field. In particular, a sufficient noise canceling effect can be obtained in a low frequency range of 2,000 Hz or less, where active noise cancellation is targeted.
Next, an operation noise control system according to the air conditioner of this embodiment is described with reference to a block diagram of
As illustrated in
In this embodiment, the control portion 30 further includes a reference noise level determining portion 311 for comparing a sound pressure (noise level) of the operation noise detected by the reference microphone 22 with a predetermined reference value and outputting a result of the comparison.
The speaker driving portion 309 directly receives a signal from the operation mode detecting portion 301, the fan rpm detecting portion 305, or the reference noise level determining portion 311 as indicated by dotted lines of
Next, an example of an operation noise control method for the air conditioner of this embodiment having the above-mentioned configuration is described with reference to a flowchart of
According to the operation noise control method in this example, in accordance with the operation mode of the air conditioner, the duct-like outlet passage 10, which can be a one-dimensional sound field, is formed in the vicinity of the outlet 5 located on the downstream side of the fan 7 in the blower passage 6. Then, in this duct-like outlet passage 10, the sound wave in antiphase to the sound wave of the operation noise including a blower sound of the fan 7 is radiated. Therefore, the operation noise is efficiently canceled out while passing through the duct-like outlet passage 10. With this, the noise to be radiated into the room can be reliably reduced, and a sufficient noise canceling effect can be obtained.
Further, according to the operation noise control method in this example, it is possible to detect sound which is actually generated when the fan 7 is driven and to radiate sound having such a waveform as to cancel against the actually generated sound. Thus, the accuracy of the noise canceling effect can be increased.
Next, another example of the operation noise control method according to the air conditioner of this embodiment is described with reference to a flowchart of
In the operation noise control method in this example, after that, in Step S43, the rpm of the fan 7 is detected, and in Step S44, the detected rpm of the fan 7 is compared with the rpm of the fan 7 which is set in accordance with the operation mode. When a difference between the detected rpm of the fan 7 and the rpm of the fan 7 which is set in accordance with the operation mode is within a preset range (YES in Step S45), in Step S46, a sound wave of operation noise generated when the fan 7 is driven is detected by the reference microphone 22. In Step S47, the phase of the detected sound wave is inverted. In Step S48, the obtained antiphase sound wave is radiated from the speaker 21. In other words, when the difference between the detected rpm of the fan 7 and the rpm of the fan 7 which is set in accordance with the operation mode is not within a preset range (NO in Step S45), the processing returns to Step S43, and Steps S43 to S45 are repeated until the difference falls within the range.
The operation noise control method in this example is targeted at steady-state noise, which is relatively stable. Therefore, active noise cancellation can be performed relatively easily.
As illustrated in
As illustrated in
A width W of the section 15 is set equal to or less than about ½ of the wavelength of a sound wave of 2,000 Hz, and is desirably set to 85 mm or less. With this setting, a sound wave passing through the section 15 can be regarded as a substantially plane wave, that is, the inside of the section can be regarded as a one-dimensional sound field. In particular, a sufficient noise canceling effect can be obtained in a low frequency range of 2,000 Hz or less, where active noise cancellation is targeted.
Further, as illustrated in
Next, an operation noise control system according to the air conditioner of this embodiment is described with reference to a block diagram of
As illustrated in
In this embodiment, the antiphase sound wave signal obtained through inversion by the phase inverting portion 310 is subjected to necessary correction processing by the sound wave correcting portion 313 and is then input to the speaker driving portion 309 as a canceling sound wave signal. When the correction noise level determining portion 312 determines that the noise level after cancellation is larger than a predetermined reference value, the sound wave correcting portion 313 calculates a correction signal from the sound wave detected by the correction microphone 23, and corrects the antiphase sound wave signal obtained through inversion by the phase inverting portion 310.
The speaker driving portion 309 directly receives a signal from the operation mode detecting portion 301, the fan rpm detecting portion 305, or the reference noise level determining portion 311 as indicated by dotted lines of
Next, an example of an operation noise control method for the air conditioner of this embodiment having the above-mentioned configuration is described with reference to a flowchart of
In addition, in Step S56, a sound wave after cancellation is detected by the correction microphone 23, and in Step S57, the noise level detected by the correction microphone 23 is compared with a predetermined reference value. When it is determined that the noise level after cancellation is larger than the predetermined reference value (NO in Step S57), the correction signal is calculated from the sound wave detected by the correction microphone 23, and the antiphase sound wave signal obtained through inversion by the phase inverting portion 310 is corrected. Then, the processing returns to Step S55, and the corrected sound wave (canceling sound wave) is radiated from the speaker 21.
According to the operation noise control method in this example, in accordance with the operation mode of the air conditioner, the duct-like outlet passage 10, which can be a one-dimensional sound field, is formed in the vicinity of the outlet 5 located on the downstream side of the fan 7 in the blower passage 6. Then, in this duct-like outlet passage 10, the sound wave in antiphase to the sound wave of the operation noise including a blower sound of the fan 7 is radiated. Therefore, the operation noise is efficiently canceled out while passing through the duct-like outlet passage 10. With this, the noise to be radiated into the room can be reliably reduced, and a sufficient noise canceling effect can be obtained.
Further, according to the operation noise control method in this example, it is possible to detect sound which is actually generated when the fan 7 is driven and to radiate sound having such a waveform as to cancel against the actually generated sound. Thus, the accuracy of the noise canceling effect can be increased.
In addition, according to the operation noise control method in this example, the accuracy of the active noise cancellation can be increased more by feedback control of the noise level after cancellation.
Next, another example of the operation noise control method according to the air conditioner of this embodiment is described with reference to a flowchart of
In the operation noise control method in this example, after that, in Step S63, the rpm of the fan 7 is detected, and in Step S64, the detected rpm of the fan 7 is compared with the rpm of the fan 7 which is set in accordance with the operation mode. When a difference between the detected rpm of the fan 7 and the rpm of the fan 7 which is set in accordance with the operation mode is within a preset range (YES in Step S65), in Step S66, a sound wave of operation noise generated when the fan 7 is driven is detected by the reference microphone 22. In Step S67, the phase of the detected sound wave is inverted. In Step S68, the obtained antiphase sound wave (canceling sound wave) is radiated from the speaker 21. In other words, when the difference between the detected rpm of the fan 7 and the rpm of the fan 7 which is set in accordance with the operation mode is not within a preset range (NO in Step S65), the processing returns to Step S63, and Steps S63 to S65 are repeated until the difference falls within the range. Steps S66 to S71 thereafter are the same as described above for Steps S55 to S58 of the example in
The operation noise control method in this example is targeted at steady-state noise, which is relatively stable. Therefore, active noise cancellation can be performed relatively easily.
As described above for the air conditioner and the operation noise control method therefor according to the present invention by way of the first to third embodiments, according to the air conditioner or the operation noise control method therefor of the present invention, harsh operation noise of the air conditioner can be significantly reduced without exposing a user directly to cold air or warm air. Therefore, delivery of an imperceptible air flow can be realized, which enables the user to sense substantially no air flow and no sound, thereby preventing a feeling of discomfort to a user and greatly increasing comfort.
Further, the operation sound of the air conditioner can be significantly reduced, and hence the air volume of the indoor unit can also be increased without giving a user an uncomfortable feeling. In other words, the refrigeration cycle efficiency can be increased consequently, which can greatly contribute to energy saving.
Note that, the present invention is not limited to the above-mentioned embodiments, and appropriate modifications may be made thereto without departing from the spirit of the present invention.
For example, in the above-mentioned embodiment, the speaker 21 and the reference microphone 22 are provided on the upper wall 6a of the blower passage 6 constituting the casing of the indoor unit 1, and the correction microphone 23 is provided on the air flow guide panel 20. Alternatively, however, as illustrated in FIG. 20, the speaker 21, the reference microphone 22, and the correction microphone 23 may be provided on the air flow guide panel 20. In this case, the speaker 21 faces the casing of the indoor unit 1, and hence, owing to the diffraction effect, a sound wave radiated from the speaker 21 can be prevented from leaking into the room. Thus, the noise canceling effect is increased more. Further, when the reference microphone 22 and the correction microphone 23 are configured to be switchable, in both cases of the upward opening and the downward opening of the air flow guide panel 20, the active noise cancellation can be performed satisfactorily.
The present invention is applicable to an air conditioner to be used by being mounted on an indoor wall surface.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2009-211759 | Sep 2009 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2010/061685 | 7/9/2010 | WO | 00 | 2/29/2012 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2011/030612 | 3/17/2011 | WO | A |
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| Number | Date | Country | |
|---|---|---|---|
| 20120171947 A1 | Jul 2012 | US |
