JPH02225967A - Noise suppressor for cooling device - Google Patents

Abstract

PURPOSE:To prevent an increase in noise by generating an alarming signal when a component of a silencing control system is subjected to an operation failure and its silencing capacity drops or disappears. CONSTITUTION:A noise suppressor for a cooling device which is designed to cancel actively sound generated from a compressor 8 with the interruption of artificial sound, comprises a sound receiver 12 which converts sound generated resultant from the drive of the compressor 8 housed in a machine compressor 7 into an electric signal, a computing element 15 which processes the electric signal, a control sound generator which generates artificial sound based on the processed electric signal, an auxiliary sound receiver 16 which monitors silencing effect of the control sound generator 13 per specified time, and a control means 17 which changes an operating factor by a specified value when the monitor result by this auxiliary sound receiver 16 is deviated from a specified allowance, and keeps the changing motion until the monitor result stays within the specified allowance. In addition, the silencer is designed to generate an alarming signal when the changing motion of the control means 17 exceeds the specified number of motion within a specified time.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a silencer used in a cooling device such as a refrigerator;
In particular, the present invention relates to a silencer for a cooling device that actively cancels out noise from a machine room housing a compressor.

(Prior art) Cooling devices that use compressors, such as refrigerators, are often installed in the living space of ordinary homes.
Moreover, since they are operated continuously throughout the season, reducing noise has become an issue. In this case, the most problematic noise source for the refrigerator is noise from the machine room in which the compressor tube and the piping system connected thereto are housed. That is, in the machine room, the compressor itself generates relatively large noises (compressor motor operating noise, fluid noise due to compressed gas, mechanical noise from movable mechanical elements in the compressor, etc.), and the The piping system also generates noise due to its vibration, and such machine room noise accounts for most of the refrigerator noise. Therefore, suppressing the noise from the machine room greatly contributes to reducing the noise of the entire refrigerator.

Therefore, conventional measures to reduce noise from the machine room include reducing the noise of the compressor itself (for example, using a rotary compressor), improving the vibration-proof support structure of the compressor, and improving the shape of the piping system. By doing this, vibration damping in the vibration propagation path can be achieved, or
BACKGROUND ART By arranging sound absorbing members and sound insulating members around the compressor and piping system, it is attempted to increase the amount of absorption in the machine room and increase the noise transmission loss.

However, in the machine room of a refrigerator inside the shell, there are multiple openings for heat dissipation in order to release the heat generated by the compressor to the outside, and noise leaks to the outside from these openings. I'm going to go out. For this reason, the conventional noise reduction measures as described above naturally have a limit, and the effect of reducing the noise level can only be expected to be about 2 dB (A) at most.

On the other hand, in recent years, with the development of electronics application technology, especially acoustic data processing circuits and acoustic control technology, the application of active noise control technology, which reduces noise by using sound wave interference, has attracted attention. “It has been numbered 1.

In other words, this active control basically converts the sound from the noise source into an electrical signal using a sound receiver (for example, a microphone) installed at a specific location, and then converts this electrical signal into a signal processed by a computing device. By operating a control sound generator (for example, a speaker) based on the control target point, the sound generator generates an artificial sound that has the same wavelength and same amplitude as the original sound (sound from the noise source) with an opposite phase at the control target point. The idea is to attenuate the original sound by causing this artificial sound to interfere with the original sound.

In addition, in order to realize such active control, it is necessary to correct characteristic fluctuations due to aging of components constituting the signal system for noise reduction and characteristic fluctuations due to ambient temperature. For this reason, in practical use, the arithmetic coefficient (transfer function) of the arithmetic unit is corrected to follow the fluctuations in the silencing ability. An auxiliary sound receiver (for example, a microphone) that monitors the silencing effect of the device, and if the monitoring result by this auxiliary sound receiver is outside a predetermined tolerance range, the calculation coefficient of the arithmetic unit is changed by a predetermined amount, and the change is made. It has also been considered to perform so-called adaptive control in which a control means is provided that performs the operation until the monitor result falls within the permissible range, thereby constantly maintaining the silencing ability at an optimum level during active control.

(Problems to be Solved by the Invention) A problem that arises when putting into practical use a muffling device using active control as described above is when a failure occurs in the components that constitute the signal system for muffling the sound. In other words, the receiver,
If a failure occurs in the control sound generator, etc., the artificial sound output for active control will have the effect of increasing the noise, and when such a situation occurs, a notification to that effect will be sent. It is desirable to stop the active control. However, it is extremely disadvantageous in terms of cost to separately construct a system that self-diagnoses the occurrence of a failure and generates an alarm signal for failure notification or active shutdown, and this point remains unresolved. This had become an issue.

The present invention has been made in view of the above-mentioned circumstances, and its purpose is to prevent noise reduction when a failure occurs in the parts constituting the control system for noise reduction and the noise reduction ability is reduced or lost. It is possible to generate an alarm signal and to obtain such an alarm signal using an auxiliary receiver and control means provided for stabilizing the silencing ability, which is very cost-effective. An object of the present invention is to provide a silencing device for a cooling device that exhibits effects such as being advantageous.

[Structure of the Invention] (Means for Solving the Problem) In order to achieve the above-mentioned 1:1 objective, the present invention provides a receiver that converts the sound generated by the drive of a compressor housed in a machine room into an electrical signal. A sound generator, a computing unit that processes the electric signal, and a control sound generator that generates artificial sound using the processed signal are provided, and the sound from the compressor is actively canceled by interference with the artificial sound. A silencing device for a cooling device equipped with an auxiliary sound receiver for monitoring the silencing effect of the control sound generator at predetermined intervals, and an auxiliary sound receiver for monitoring the silencing effect by the control sound generator at predetermined intervals, and a case where the results of monitoring by the auxiliary sound receiver are out of a predetermined tolerance range. A control means is provided that changes the calculation coefficient of the calculation unit by a predetermined amount and performs the changing operation until the monitor result falls within the tolerance range, and then the control f1 stage is changed to the change operation of the calculation coefficient. The system is configured to generate an alarm signal when this is performed a predetermined number of times or more within a predetermined period of time.

(Function) The sound from the compressor is converted into an electric signal by the sound receiver, and the arithmetic unit operates the control sound generator based on a signal obtained by processing the electric signal. As a result, the sound from the compressor is canceled out by interference between this and the human sound output from the control sound generator. Furthermore, the silencing effect of such active control is monitored by an auxiliary sound receiver at predetermined intervals, and if the monitoring result is outside a predetermined tolerance range, the control means The calculation coefficient (transfer function) of the device is changed by a predetermined amount, and accordingly, the silencing effect by active control is changed in a direction that falls within the above-mentioned allowable range. This operation of changing the calculation coefficients is carried out until the monitoring result by the auxiliary sound receiver falls within the allowable range, and as a result, adaptive control is performed in order to always keep the noise reduction ability at the optimum level during active control. .

However, if a failure occurs in the parts such as the sound receiver, auxiliary sound receiver, and 8 control sound generators that make up the control system for sound muffling, the sound may be muffled by artificial sound despite the above adaptive control. The effect (corresponding to the results monitored by the auxiliary receiver) may no longer fall within the allowable range. Then, the control means changes the calculation coefficient of the arithmetic unit a predetermined number of times or more within a predetermined period of time, and accordingly generates an alarm signal. Therefore, it is possible to notify the occurrence of a failure or to stop the active control based on this alarm signal, thereby eliminating the risk of an increase in noise as in the conventional case when a component failure occurs as described above. It disappears.

(Example) Hereinafter, an example in which the present invention is applied to a refrigerator will be described.

First, in FIG. 3 showing the overall configuration of a refrigerator, 1 is a refrigerator main body which is a cooling device main body, and inside this, from the top, there are freezer compartments 2. A refrigerator compartment 3 and a vegetable compartment 4 are provided. 5 is a cooler disposed at the back of the freezer compartment 2; 6 is a fan that directly supplies cold air generated by the cooler 5 to the freezer compartment 2 and the refrigerator compartment 3. 7 is a machine room formed at the lower part of the back side of the refrigerator body 1, and inside this is a rotary type compressor 8. A condenser vibrator 9 and a defrosting water evaporator 10 using so-called ceramic fins are housed.

Now, as shown in FIG. 4 (here, the illustration of the condenser vibrator 9 and the defrosting water evaporator 10 is omitted), the machine room 7 has a rectangular opening only on its back side. This opening portion is closed by a machine room cover 11. At this time, the machine room cover 11
The peripheral edge of the tube is airtightly connected to the opening edge of the machine room 7, and an elongated rectangular heat dissipation opening 11a extending in the vertical direction is formed at the left edge in the figure. There is. That is, when the machine room cover 11 is attached, the machine room 7 is in a closed state leaving the heat radiation opening 11a. The machine room cover 11 is made of a material (for example, metal such as iron) that has excellent thermal conductivity and high sound transmission loss.

Further, in FIG. 4, reference numeral 12 denotes a microphone, which is a receiver placed in the machine room 7, and is located on the opposite side of the compressor 8 from the heat dissipation opening 11a (on the right side in the figure). The compressor 8 is arranged so as to face the compressor 8, and is provided so as to convert the sound from the compressor 8, which is a noise source, into an electrical signal. Reference numeral 13 denotes a speaker serving as a control sound generator disposed in the machine room 7, and this is placed, for example, in a part of the back wall of the machine room 7 (corresponding to the bottom wall of the refrigerator body 1) near the heat radiation opening 11a. It is installed and supported in a buried manner.

As shown in FIG.
It is operated by a signal processed by the arithmetic unit 15 inside, and the above-mentioned processing of the electrical signal is performed based on the principle of silencing by active control as described below. .

That is, to roughly explain the principle of silencing by active control with reference to FIG.
2. The sound received by the microphone 12 is R1, the sound at the heat radiation opening 11a which is the control target point is R2, and the acoustic transfer function between the sound output and human power points as described above is T.
ll, T21, T12. When T22 is assumed, the following equation holds true as a two-man power two-output system.

Therefore, the sound S2 to be generated by the speaker 13 is calculated from the above equation as follows: S2 − (−T12・R1, +Ti1−R2)/(
Tll-T22-TI2·T21) is set as 7+, J, but in this case, since the goal is to make the sound level at the heat radiation opening 11a zero, it can be set as R2-0. As a result, S2-R1-TI2/ (T21-TI in T12
t・T22). As can be understood from this equation, in order to make the sound R2 at the heat dissipation opening 11a zero, the sound R1 received by the microphone 12 is given by F-T12/ (T12- T21-Tll-T22).
If the speaker 13 generates the sound S2 processed through a filter, the sound level at the heat dissipation opening 11a can theoretically be reduced to zero. The output of the speaker 13 is controlled while performing processing (calculation) at high speed.

Here, in the case of the refrigerator configured as described above, the level of noise generated in the machine room 7 in response to the drive of the compressor 8 is in the band of about 700 Hz or less and in the range of 1.5 to 1.5 Hz, as shown in FIG. It becomes a state in which it has the property of increasing in the band of 5KH2. Among the noise corresponding to each of these bands, the noise on the high frequency side can be attenuated by transmission loss in the machine room cover 11, etc., and by installing appropriate sound absorbing members in the machine room 7. Therefore, the active control of noise using the microphone 12, speaker 13, and computing unit 15 as described above can be performed at 70%.
The target frequency may be 0 Hz or less.

In addition, when performing active noise control as described above, it is important to configure the noise in the machine room 7 so that it becomes a one-dimensional plane traveling wave, both theoretically and technically. This is important for easy and accurate execution.

Therefore, in this embodiment, among the three-dimensional depth, width, and height dimensions W and H in the machine room 7 shown in FIG. Dimensions.

Set larger than H (specifically, W=600ms, D-
H-200-1), the machine room 7
The structure is such that the standing wave of sound within is established only in the layer mode. That is, for example, when the machine room 7 is assumed to be a rectangular cavity, the following equation holds true.

f−C−NXLX +NyLy +NzLz)
/2 However, f is ノ(layer wave number (Hz), NX, Ny.

NZ is number 1 mode in each direction of x, y, and z, LX, Ly,
Lz is the -J' method (that is, W, H) in each of the x, y, and z directions in the machine room 7, and C is the speed of sound. Therefore, from the above equation, the frequency f of the first standing wave in each of the x, y, and z directions is
x, fy, fz can be found.

That is, as described above, when the depth dimension D-2001, the width dimension W-600 am, and the height dimension Hm are set to 200 sg, the frequency Ex of the first standing wave in the X direction is Ny −Nz− 0, sound speed c-'340m/sec, fx-3401,2)/2 =850Hz, and similarly, the frequencies ry and fz of the first standing wave in the Y and Z directions are fy-340,6 ) /2 283Hz fz-340,2) /2 -8.50 Hz. As a result, the target frequency (-700H
z) Above, the standing wave of noise in the machine room 7 moves in the Y direction (
This is true only for the mode in the width direction), and the noise in the machine room 7 can be interpreted as a one-dimensional plane traveling wave. Therefore, in silencing by controlling noise using the front Ae speaker 13 or the like, theoretical handling of the wavefront becomes easy, and silencing control can be performed easily and accurately.

Now, in FIG. 1, reference numeral 16 denotes an auxiliary microphone serving as an auxiliary sound receiver, which is configured to convert the sound at the heat radiation opening 11a into an electric signal Se, and is then transmitted to the speaker 13.
It is provided so that the silencing effect can be monitored.

The electrical signal Se is then manually inputted to the adaptive control circuit 17 which is a control means within the out-of-phase sound generation circuit 14.

Therefore, in the above, the functions of the adaptive control circuit 17 will be explained with reference to the flowchart of FIG. 2.

That is, the adaptive control circuit 17 executes a routine for adaptive control starting from step B at every predetermined time, for example, every time a certain period of time T (about 10 minutes) has elapsed (step A in FIG. 2). At this time, first use the auxiliary microphone 1.
Based on the electric signal Se from 6, the silencing effect by the above-mentioned active control is monitored (Step B), and then the count value N of an internal counter (not shown) is initialized (Step C).
.

Then, it is determined whether or not the above-mentioned monitoring result is outside a predetermined tolerance range (step D), and if it is within the tolerance range, the process returns to step A.

On the other hand, if the monitoring result of the silencing effect is outside the allowable range, the calculation coefficient (transfer function) of the computing unit 15 is changed by a predetermined amount in the direction of increasing the silencing ability (step E). ), as a result, the output from the speaker 13 is increased by 13 meters, and the silencing effect of the two sounds from the speaker 13 is changed to fall within the above-mentioned allowable range. Also, at this time, the 3f number (ifN) of the internal counter is
1'' (step F), and it is determined whether the count value N has reached a preset upper limit value Nsaw (step G). If it is determined "NO" here, the process returns to step C, and from this point on, a loop is formed to repeatedly execute steps CG, and the operation of changing the calculation coefficients of the calculation unit 15 described above is repeated. do. still,
This loop is repeated at a cycle of, for example, a little less than one second.

During the execution of the above loop, if the monitoring result of the silencing effect falls within the permissible range (if judged as -rNOJ in step D), the operation coefficient changing operation of the arithmetic unit 15 is stopped and the process returns to step A. Operation coefficient change operation is Naa
When the process has been repeated X times, select ``YES'' in step G.
”. When such a judgment is made, it generates an alarm signal, and after stopping the active control by the computing unit 15, stops its own control operation (step H11). Note that the above-mentioned alarm signal is used, for example, to display or notify that an abnormal state has occurred.

In short, the adaptive control circuit 17 monitors the silencing effect of the artificial sound from the speaker 13 through the auxiliary microphone 16 at a constant j interval, and the monitoring result is
Components that make up the signal system for the silencer (microphone 12
．． Speaker 13. When the noise is out of the allowable range due to a change in the characteristics of the auxiliary microphone 16, etc., the operation of correcting the calculation coefficient of the calculator 15 by a predetermined m increment is repeated until the silencing effect falls within the allowable range. Adaptive control is performed to always keep the noise reduction capability at the optimum level during active control. In addition, the adaptive side 8 circuit 17 is configured to handle the case where the muffling effect due to artificial g is no longer within the permissible range despite the above-mentioned adaptive control due to a failure of components such as the microphone 12. In this case, an alarm signal Sa is generated based on the correction operation of the calculation coefficient performed by itself a predetermined number of times (N*aX) within a predetermined period of time. Therefore, it is possible to notify the occurrence of a failure or to stop active control based on this alarm signal Sa, and there is no risk of an increase in noise as in the conventional case when a failure occurs in a component.

Of course, in the above embodiment, the machine room 7 has the heat radiation opening 1
Compressor 8 communicates with the outside through 1a.
The temperature in the machine room 7 will not rise abnormally due to heat generated during driving.

In addition, since the machine room cover 11 is made of a material with excellent thermal conductivity, the heat dissipation efficiency of the heat generated in the machine room 7 is improved. Increases can be kept low.

In the above-described embodiment, the adaptive control circuit 17 performs the adaptive control at regular intervals. It may be done at every predetermined time, for example, at a predetermined time.

In addition, the present invention is not limited to the embodiments described above and shown in the drawings. For example, the outdoor unit of an air conditioner or a refrigerated showcase may be applied as a cooling device to be silenced. Various modifications can be made without departing from the scope.

[Effects of the Invention] According to the present invention, as is clear from the above description, the sound generated by the drive of the compressor housed in the machine room is transmitted from the control sound generator operated by the signal processed by the arithmetic unit. In a silencing device for a cooling system that actively cancels out interference with human T-sound, there is a possibility that the silencing ability may decrease or disappear due to a failure in the parts that make up the control system for silencing. It is possible to generate an alarm signal in the event of a problem, and thus it becomes possible to appropriately deal with the increase in noise caused by the occurrence of component failure.

In addition, the above-mentioned alarm signal can be generated using an auxiliary sound receiver and control means provided for the purpose of stabilizing the noise reduction ability, which is very advantageous in terms of cost. It is.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a schematic electrical configuration diagram, FIG. 2 is a flowchart showing the control contents of the control means, FIG. 3 is a longitudinal cross-sectional view of the refrigerator, and FIG. The figure is a perspective view showing the main parts in an exploded state, Fig. 5 is a schematic configuration diagram showing the principle of silencing by active control, Fig. 6 is a schematic perspective view for explaining the dimensional relationship of the main parts, and Fig. 7 is a noise reduction diagram. It is a level characteristic diagram. In the figure, 1 is the refrigerator body, 7 is the machine room, 8 is the compressor, 10 is the defrosting water evaporator, 11 is the machine room cover 11a
is a heat radiation opening, 12 is a microphone (FI receiver),
Reference numeral 13 indicates a speaker (control sound generator), 14 indicates an anti-phase sound generation circuit, 15 indicates an arithmetic unit, 16 indicates an auxiliary microphone (auxiliary sound receiver), and 17 indicates an adaptive control circuit (control means). Figure 1 Applicant Toshiba Co., Ltd. Agent Patent Attorney Tsuyoshi Sato pJ2 Figure Figure Figure Figure

Claims (1)

[Claims] 1. Converting the sound generated by the drive of the compressor housed in the machine room into an electrical signal using a sound receiver, and operating the control sound generator based on the signal processed by this electrical signal using an arithmetic unit. A silencing device for a cooling device that actively cancels out sound radiated from the machine room to the outside, the silencing device comprising: an auxiliary sound receiver for monitoring the silencing effect of the control sound generator at predetermined intervals; and the auxiliary sound receiver when the result of monitoring is outside a predetermined tolerance range, the operation coefficient of the arithmetic unit is changed by a predetermined amount, and the changing operation is continued until the monitor result falls within the tolerance range. A silencer for a cooling device, wherein the control means is configured to generate an alarm signal when the operation coefficient is changed a predetermined number of times or more within a predetermined period of time. .