JPH06124092A - Noise eliminating device for air conditioner - Google Patents

Abstract

PURPOSE:To reduce the cost since no error detecting means is required for the normal operation of the air conditioner and to obtain the noise eliminating device which greatly eliminates of reduces a noise with high follow-up control since a control filter coefficient is updated as a sound wave propagation medium changes in state. CONSTITUTION:The 1st signal showing characteristics of the noise and the 2nd signal showing characteristics of the state of the sound wave propagation medium are transmitted from a 1st detecting means 7 and a 2nd detecting means 8 to an electronic control means 9 respectively, and the optimum control filter coefficient which is determined previously for a certain state of the sound wave propagation medium is updated by a correcting means in the electronic control means 9 and outputted to a canceling means 6, thereby eliminating or reducing the noise with a canceling sound generated by the canceling means 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an indoor unit of an air conditioner, and more particularly to an air conditioner which actively and effectively eliminates noise emitted from the indoor unit of an air conditioner at low cost. The muffler for indoor units.

[0002]

2. Description of the Related Art Conventionally, as a method for reducing the noise of equipment, passive methods such as reducing the noise of the component parts of the equipment itself, absorbing sound, and insulating sound have been generally used. However, in recent years, an active control method for muting sound has been developed, and its application to noise reduction of equipment has been attempted. These active control methods are disclosed in JP-A-3-2
As disclosed in Japanese Patent Publication No. 94725, an error monitoring microphone is indispensable, and its output is minimized.

[0003]

FIG. 4 and FIG. 5 show a general basic configuration in conventional active control. In this case, as shown in the block diagram of FIG. 5, the noise of the noise source is detected by the noise detecting means and input to the level adjusting means and the phase converting means in the electronic control means. Here, a waveform signal that cancels the noise source is created, and a sound is emitted from the sounding means (normal speaker). Sound receiving means (that is, error microphone) for synthesized sound of noise and sound emitted by the sound generating means
It is a method of performing active control by operating the sounding means by the amplitude adjusting means and the phase converting means in the electronic control means so that this level is always minimized.

In the above conventional method, when the electronic control means performs the optimum control for correcting the change in the noise propagation characteristic due to the change in the medium, the sound receiving means is indispensable and further feedback control is required. As a result, the electronic control means becomes high-performance and complicated, and the cost increase is inevitable.
Further, in active control that does not use sound receiving means, it is not possible to cope with a change in sound velocity associated with a change in the state of the sound wave propagation medium, that is, an error for an effective cancellation condition, and a sufficient effect cannot be obtained.

An object of the present invention is to reduce the noise emitted from the indoor unit of the air conditioner at a low cost without deteriorating the followability of the active control, and to reduce the noise for the air conditioner. To provide.

[0006]

In order to achieve the above object, a silencer for an indoor unit of an air conditioner according to the present invention is provided with a first signal generating a first signal representing the amplitude and phase characteristics of the noise. A detection means, a cancellation means for generating a cancellation sound, a second detection means for generating a second signal representing a characteristic of a state of a sound wave propagation medium (usually air in a room), the first signal and the And an electronic control unit for varying the amplitude and phase of the first signal so as to minimize the sum of the noise and the canceling sound from the second signal and outputting the variable to the canceling unit.

[0007]

According to the present invention, a first signal representing the amplitude and phase characteristics of noise emitted from an indoor unit of an air conditioner and a second signal representing the characteristics of the state of a sound wave propagation medium are input. In the electronic control means, the control filter coefficient is adjusted in advance from the temperature and humidity of the indoor air by the learning means, and gradually adjusts the amplitude and phase of the first signal based on the results obtained by the level adjusting means and the phase converting means. However, the signal that is stored in the storage means and that generates the canceling sound that minimizes the sum of the noise by updating the control filter coefficient based on the first signal and the second signal is canceled by the canceling means. The noise is reduced by inputting the noise to the noise generator.

[0008]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example in which the present invention is applied to an indoor unit of a ceiling-embedded air conditioner. In the figure, 1
Is a casing, 2 is a front panel, 3 is an intake grill, 4 is a heat exchanger, 5 is a centrifugal fan, 6 is a canceling means, 7 is a first detecting means, 8 is a second detecting means, and 9 is an electronic control means. .

The control filter coefficient is determined by the following procedure. The noise emitted from the indoor unit of the air conditioner is received by at least one monitor microphone or other first detection means 7, and a first signal representing the characteristics of the noise is transmitted to at least one electronic control means 9. Here, the first detection means is, in addition to the monitor microphone, the impeller rotation speed and the motor rotation speed,
Alternatively, a velocity fluctuation component may be detected and the first signal may be processed and generated via a waveform generator (not shown in the figure). The electronic control means 9 receives the sum signal of the noise and the canceling sound generated from the canceling means such as at least one speaker, that is, the error signal by the error detecting means such as the error microphone.
Send to. In the electronic control means 9, a digital signal processor (hereinafter referred to as DSP) composed of an FIR filter or the like.
Abbreviated), and in the DSP, a learning filter having an adaptive algorithm composed of control software such as an LMS algorithm (least mean square method) so that the difference between the error signal and the control target value becomes zero is a control filter. The coefficient is determined and stored in the storage means. The control filter coefficient shall be determined and stored when a decrease in the silencing effect is observed or at regular intervals.

After the control filter coefficient is determined, the error detecting means is removed, and then at least one temperature or the second detecting means 8 such as a temperature and humidity sensor is used to output a second signal representing the characteristic of the state of the indoor air. Is transmitted to the electronic control means 9. Here, the second detecting means may be provided inside or near the air conditioner or in the remote control device 10 for controlling the operation of the air conditioner as shown in FIG. Further, the transmission may be wired or wireless or both. If the air conditioner has temperature and humidity sensors for operation control, they may be shared with the second detecting means. Electronic control means 9
In the above, the stored control filter coefficient is updated by the correction means having the temperature-humidity change tracking type adaptive control algorithm based on the first signal and the second signal, and transmitted to the cancellation means. As a result, the canceling sound is dissipated from the canceling means 6, and the noise is reduced and muted.

In performing the adaptive control, the error detecting means 11 such as an error microphone is conventionally used as shown in FIG. 4, whereas the present invention is controlled by using the temperature and humidity sensor as described above. Therefore, it is not necessary to newly provide an error detecting means, and if the temperature / humidity sensor for operation control of the air conditioner is also used as the second detecting means, it is not necessary to additionally provide a temperature / humidity sensor, and a significant cost reduction can be achieved. . or,
Since the number of components is reduced, the air conditioner can be easily arranged in the indoor unit. Further, the error detecting means 11 is required only when the sound field is mainly determined by factors other than the sound wave propagation medium, and the error detecting means 11 is located at an arbitrary position depending on the environment in which the air conditioner is used. The optimum control filter coefficient can be determined and stored in advance. Incidentally, by performing such an operation in the initial setting or the occasional setting, the output signal of the second detecting means shown in the present invention, that is, the medium of the sound wave propagation, is obtained in other normal states of the air conditioner. By updating the control filter coefficient in the electronic control means 9 based on the change, a large amount of muffling is always realized.

Further, by incorporating a temperature / humidity sensor in the remote control device 10, the control filter coefficient is taken into consideration not only the state of the room air at the position where the second detecting means 8 is installed, but also the state of the air at the human hand. Can be updated and controlled.

[0014]

According to the present invention, in the normal operation of the air conditioner, the adaptive control is performed without using the error detecting means, so that the cost can be reduced. Further, since the control filter coefficient is updated by the signal representing the characteristic of the state of the sound wave propagation medium generated by the second detecting means, a high followability can be obtained. Further, by incorporating the second detection means in the remote control device, it is possible to consider the state of the sound wave propagation medium in the human hand, and it is possible to perform adaptive control so as to create a more comfortable space. Further, if the temperature / humidity sensor for operation control of the air conditioner is also used as the second detecting means, it is not necessary to additionally provide a temperature / humidity sensor, and a significant cost reduction can be achieved.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

FIG. 2 is a block diagram of signal processing showing an embodiment of the present invention.

FIG. 3 is an explanatory view of mounting the silencer according to the embodiment of the present invention on an air conditioner.

FIG. 4 is an explanatory diagram of how the conventional silencer is attached to an air conditioner.

FIG. 5 is a block diagram of signal processing showing an embodiment of a conventional method.

[Explanation of symbols]

1 ... Casing, 2 ... Front panel, 3 ... Intake grill, 4
... heat exchanger, 5 ... centrifugal fan, 6 ... offsetting means, 7 ... first detecting means, 8 ... second detecting means, 9 ... electronic control means.

 ─────────────────────────────────────────────────── ─── Continued front page (72) Inventor Joji Okamoto 390 Muramatsu, Shimizu City, Shizuoka Prefecture Hitachi Ltd. Shimizu Plant

Claims (1)

[Claims] 1. A silencer for an air conditioner for attenuating noise emitted from an indoor unit, comprising first detecting means for generating a first signal representing characteristics of amplitude and phase of the noise.
Second detection means for generating a second signal representing the characteristics of the state of the sound wave propagation medium, so that the sum of the noise and the canceling sound from the first signal and the second signal is minimized, A silencer for an air conditioner, comprising: electronic control means for changing the amplitude and phase of the first signal to output to the canceling means, and canceling means for generating canceling sound.