JPH02225962A - Noise suppressor for cooling device - Google Patents

Abstract

PURPOSE:To improve the accuracy of active control by keeping a machine room, where a horizontal type compressor is housed, under a closed state except for a radiation opening and mounting a sound receiver at a place which is near the center of the compressor on its opposite side and as far as possible from a sound generator for control service. CONSTITUTION:To cancel actively noise generated by the drive of a horizontal type compressor 18 housed in a machine room 17 based on an artificial interruption, the machine room 17 is closed except for a radiation opening 20 which is deviated to one side. At the same time, it is arranged that only a primary mode be established below a frequency band in which a standing wave of sound in the machine room 17 is to be canceled by setting a dimension only in one direction larger than the other dimensions in three dimensional directions in the machine room 17. Furthermore, a control sound generator 21 is mounted near the radiation opening 20 so that it may be directed to the opening 20 while the compressor 18 is laid out on the other end of the machine room 17 so that it may cross the longitudinal direction of the machine room 17. A sound receiver 22 is mounted at a place which faces the center of the compressor 18 and in the farthest distance from the control sound generator 21. It is, therefore, possible to simplify active control, improve control accuracy, and reduce noise as well.

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 households.
Moreover, since they are operated continuously regardless of the season, reducing noise has become an issue. in this case,
The most problematic source of refrigerator noise is the compressor.
The noise is coming from the machine room at the bottom of the refrigerator body, where the rack and the piping system connected to it are housed. That is, in the machine room, the compressor unit generates relatively large noise (compressor motor operating noise, fluid noise due to compressed gas, mechanical noise from movable mechanical elements of the compression mechanism, etc.) and also The piping system also generates noise due to its vibrations, and such machine room noise accounts for most of the refrigerator noise. Therefore, suppressing the noise from the machine room will greatly contribute to reducing the noise of the entire refrigerated JPO.

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 changing the shape of the piping system. By doing this, we aim to attenuate vibrations in the vibration propagation path, or by arranging sound absorbing and sound insulating materials around the compressor and piping system, we increase the amount of absorption in the machine room and reduce noise transmission loss. Efforts are being made to increase the number of people.

(Problem to be Solved by the Invention) Generally, the machine room of a refrigerator is provided with multiple openings for heat dissipation due to the need to release heat generated by the compressor to the outside. Noise will leak outside.

For this reason, the conventional noise reduction measures mentioned above naturally have their limits, and the noise level reduction effect is at most 2 dB (A
) can only be expected.

On the other hand, in recent years, with the development of electronics application technology, especially acoustic data processing circuits and sound control technology, the application of active control technology that uses sound wave interference to reduce noise has begun. Attention has been paid. That is, this active control basically converts the sound from the noise source into an electrical signal using a sound receiver installed at a specific position, and
By operating a control sound generator based on a signal processed by a computing unit from this electrical signal, the sound generator emits n sounds with the same wavelength and opposite phase from the original sound (sound from the noise source) at the control target point. The idea is to attenuate the original sound by having a person generate a sound with the same amplitude and causing the artificial sound to interfere with the original sound.

However, when such active noise control is used to reduce machine room noise in a refrigerator, the machine room is not sealed and the noise generated within the machine room leaks freely in three-dimensional directions. However, the active control mode is extremely complicated, and the reality is that there is no certainty that active control of noise in refrigerators will be put to practical use.

Recently, horizontal rotary type compressors have been widely used as compressors, but these compressors are generally large in length in the horizontal direction (and the main source of noise is the rotating sound of the compressor motor. Since two types of sound, including electromagnetic sound, are generated from both ends of the compressor, when using such a horizontal compressor, there is a problem that the active control mode becomes more complicated.

The present invention has been made in view of the above circumstances, and its purpose is to use a horizontally placed compressor as a compressor, and to reduce the amount of air generated in a non-sealed machine room in response to the drive of the compressor. When performing active control that cancels noise by interference with artificial sound, it is possible to simplify the active control and improve control performance.
An object of the present invention is to provide a silencer for a cooling device that can sufficiently exhibit a noise reduction effect.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above-mentioned [Object 4], the present invention provides a method for driving a horizontal compressor housed in a machine room; , in a silencer for a cooling device that actively cancels out interference with artificial sound! A The machine room is configured in a closed state with a heat dissipation opening located near one end thereof, and one dimension of each three-dimensional dimension inside the machine room is set larger than the other dimensions. By doing so, the standing wave of the sound in the machine room is configured so that only a mode is established below the frequency band to be canceled, and furthermore, the control sound generator is located near the heat dissipation opening. The compressor is installed at the other end of the machine room so as to intersect with the longitudinal force direction of the machine room, and a sound receiver is installed at a part facing the center of the compressor and for the control. It is installed as far away from the sound generator as possible.

(Function) For example, in the case of a refrigerator, which is a typical example of a cooling device, the acoustic level of the noise generated in response to the drive of the compressor is 70% as shown in Fig. 7.
It has the characteristic that it becomes louder in the band below 0HzfSi degree and in the band from 1.5 to 5KHz. Among the noises corresponding to each of these bands, those on the high frequency side can be easily muffled by conventional noise reduction techniques using sound absorbing members or the like. Therefore, when actually performing active noise control, the noise on the low frequency side should be adjusted to the target frequency (
In this case, the frequency may be set to about 700 Hz or less). In this way, when the target frequency is about 700 Hz or less, two directions of the height, depth, and width inside the machine room are shorter than the wavelength of the original noise (about 50 cm when the sound speed is 340 m/s), and the remaining If the dimension in one direction is set to be longer than the above wavelength, the standing wave of the noise generated in the machine room will become more likely to have only one mode. In other words, by setting the -j dimension in one of the three-dimensional directions (height, depth, and width) in the machine room to be larger than the other dimensions, the standing waves of sound in the machine room can be canceled. It can be configured so that only one mode is established below the frequency (target frequency) band, and when configured in this way, the sound generated in the machine room can be regarded as a one-dimensional plane traveling wave, Active control, which attempts to muffle the sound from the compressor by interfering with the artificial sound from the control sound generator at the heat dissipation opening, which is the exit of the sound from the compressor, is theoretically and technically possible. This makes it easier and more accurate.

In addition, at this time, by placing a horizontal compressor at the other end of the machine room on the opposite side from the heat dissipation opening and the control sound generator so as to cross the longitudinal direction of the machine room, the compressor can be The sound receiver can be placed as far as possible from the heat radiation opening, which is the exit of the sound, and the sound receiver can be placed at a location facing the center of the compressor, and 1. By installing the sound receiver as far away as possible from the control sound generator, the sound receiver can receive the noise generated from the horizontally long compressor as accurately as possible, while also minimizing the influence of the sound emitted from the control sound generator. Therefore, active control when using a horizontal compressor can be performed more easily and with high precision.

Of course, there is an opening for heat radiation in the machine room, so
There is no risk of an abnormal rise in the temperature inside the machine due to heat generated when the compressor is driven.

(Example) Hereinafter, an example in which the present invention is applied to a refrigerator will be described.
About the principle of silencing by formations! l! Let me explain it in terms of EII3.

In Figure 6, 1 is a noise source such as a compressor, 2
indicates the control target point for which noise is desired to be muted, and noise source 1
A sound receiver '3 such as a microphone converts the sound from the source into an electrical 1= signal, and this electrical 1J signal is processed through a calculator 4 including a filter, and the processed lj signal is used to generate a signal from a speaker, etc. It is designed to drive the generator 5.

That is, the sound generated by the noise source 1 is St, and the sound generated by the speaker 5 is St32. The sound received by the microphone 3 is R1, the sound at the control target point 2 is R2, and the C3"jJ transfer function between the above-mentioned output and human power points is GSM+
When GAMa - Gbut GAU, the following equation holds true as a two-man power two-output system.

Therefore, the sound S2 to be generated by the speaker 5 is calculated from the above equation as S2'' (Gso-R1+GsM-R2)/(G
S&l -G AO-G so -G AM), but in this case, the first vote is to make the sound level at control target point 2 zero, so it can be set as R2-0. . As a result, S2 = RI ・Gs
o/(Gso-GhM-GsM-GAO). As can be understood from this equation, in order to reduce the sound R2 at the control target point 2 to zero, the sound R1 received by the microphone 3 is given the following formula: G = Gso/ (AM GsM - GAO for Gso-)
- (1) If the filtered sound S2 is generated from the speaker 5, the sound level at the control target point 2 can be theoretically reduced to zero.

In addition, each transfer function G sy* CAMI G got
G The time delay in the air in AO is rSM+
τAM+rS. .

Assuming rAo, the above equation (1) can be expressed as follows.

G -08L) -cxp(-jωrso＞/l G
so “CAM” (!XI) (-jω(rso+
τAIJ) ) G s, A' G AO-eXl) (
−Jω(rsl+1+τAO) ) )= 1 /
(G AM' eXl) (-jω r
AM) (CAU-G 5hal G so) ・eX
I) (-jω(τAO+τsM-τso)) 1 Here, suppose G AM >) G AO” G SM/
If G so, then G"? (1/ CAM) -expU (i
J'r^M), which means that if the sound received by the microphone 3 is multiplied by (1/CAM) and the phase is advanced by ωτA7, only the sound coming from the speaker 5 will enter the microphone 3.

On the other hand, CAM <(G AO' G SM/ G 50
Then, G″nee Gso/Gs, A-GAo) kaicxp(publishedω(r so-r AO-r sM))-
(2), which indicates that when the sound from the speaker 5 does not enter the microphone 3, it is possible to process the sound faster than it propagates through the air and output the control sound from the speaker 5. .

Although the two extreme cases have been described above, the normal case is considered to be somewhere between them. In any case, it can be understood from this that in order to perform active noise control, the smaller the CAM, the better; that is, it is better to place the microphone 3 as far away from the speaker 5 as possible.

Also, from the above equation (2), the noise source 1 and the control target point 2 should be kept as far away as possible, while the speaker 5 and the control target point 2,
It can be seen that it is better to place the noise source 1 and microphone 3 as close as possible.

One embodiment of the present invention is shown in FIGS. 1 through 4, and will be described below.

That is, in FIG. 4 showing the overall structure of the refrigerator, 11 is a refrigerator main body which is a main body of a cooling device, and inside this, from above, there are freezing compartments 12. A refrigerator compartment 13 and a vegetable compartment 14 are provided. 15 is a cooler disposed at the back of the freezer compartment 12, and 16 is a fan that directly supplies cold air generated by the cooler 15 to the freezer compartment 12 and the refrigerator compartment 13.

Reference numeral 17 denotes a machine room formed at the lower part of the back side of the refrigerator main body 11, in which a horizontal rotary compressor 18 and a condenser vibrator (not shown) are housed.

Now, as shown in FIG. 2, the machine room 17 has an oblong shape with a rectangular opening only on the back side.
This opening portion is closed by a machine room cover 19. At this time, the peripheral edge of the machine room cover 19 is hermetically fitted to the opening edge of the machine room 17, and the right edge in FIG. A rectangular heat radiation opening 20 is formed. In other words, when the machine room cover 19 is attached, the machine room 17 is closed except for the heat dissipation opening 20 at the right end, which is one end thereof. The machine room cover 19 is made of a material (for example, metal such as iron) that has excellent thermal conductivity and high sound transmission loss.

The compressor 18 has a horizontally long shape, and the compressor 18 is located at the left end of the machine room 17, which is the other end of the machine room 17, as shown in FIG.
It is arranged so as to intersect with the longitudinal direction of the machine room 17 by tilting it at an angle θ in the longitudinal direction (it is tilted upward to the right in FIG. 1).

21 is a speaker which is a sound generator for control, and this is a speaker in machine room 1.
It is attached near the heat dissipation opening 20 at the right end of the heat dissipation opening 20 . 22 is a sound receiver, for example a microphone, which is mounted on a compressor at the left end of the machine room 17.

11 are attached to the central part of the compressor 18 in the χ·1 direction and at a position as far away as possible from the above-mentioned transmission force 21, thereby converting the sound from the compressor 18, which is the noise source, into electrical fz. It is set up like this. The speaker 21 is operated by a signal processed by an arithmetic unit (not shown) in an anti-phase sound generation circuit from an electrical signal from the microphone 22, and is configured to be operated by a signal processed by an arithmetic unit (not shown) in an anti-phase sound generation circuit. The processing is carried out based on the above-mentioned active control silencing principle.

However, in the case of the refrigerator configured as described above, the qh level generated in the machine room 17 in response to the drive of the compressor 18 is in the band below about 700 H7 and 1.5 as shown in FIG. In the band of 5KH2 to 5KH2, the state becomes more intense. Among these noises corresponding to the low band, the noise on the 8th frequency side can be attenuated by transmission loss in the machine room cover 19, etc., and can be easily attenuated by installing an appropriate sound absorbing member in the machine room 17. Since the sound can be muted, the above-mentioned microphone 22. Active control of noise by the speaker 21 and the computing unit may be performed using a target frequency of 70 tl) Hz or less.

In addition, when performing active noise control as described above, it is important to configure the noise in the machine room 17 so that it becomes a one-dimensional plane traveling wave, both theoretically and technically. It becomes easier and more accurate to urinate.

Therefore, in this embodiment, the machine room 17 shown in FIG.
Depth 1 Width and height direction δ・
Among the j-dimensions, W and H, the width direction dimension W is set larger than the other 11-dimensions and H (specifically, W = 600
mm, D-H-200-1) so that the standing wave of sound in the machine room 17 is established only in the primary mode.

That is, when the machine room 17 is assumed to be a simple rectangular cavity, the following equation holds true.

f = C-NX 1. X + Ny t, y + (
NZ, 1. z'/2(]'', f is the resonant frequency (
Hz), NX, Ny.

NZ is the number 1 mode in each direction of x, y, z, Lx, Ly, L
z is the dimension in each of the x, y, and z directions (that is, W, H) in the machine room 17, and C is the speed of sound. Therefore, from the above formula, x
, 11 constant/L wave frequencies fx for each direction, y, z
, fy, fy can be obtained.

That is, as mentioned above, in case of J8, where the depth dimension is set to D-, 2001, width dimension W-600+gs, and height dimension H-200sv, the frequency fX of the first standing wave in the X direction is Ny -Nz-0, speed C-340m
/second, fx -340(10,2)/2 = 850Hz, and similarly, the frequencies fy and fz of the standing wave of No. 1 [1] in the Y and Z directions are fy -340(1,10,6 ) ノ / 2=
283 H2 fz -3401, 2)'/2 850H2. As a result, the target frequency (-700H
z) In the following, the fixed wave of noise in the machine room 17 is valid only for the mode in the Y direction (longitudinal direction of the machine room 17), and the noise in the machine room 17 is treated as a one-dimensional plane traveling wave. can be considered. Therefore, when silencing noise through active noise control using the microphone 22, speaker 21, etc., the theoretical handling of the wavefront becomes easy, and silencing can be easily and precisely performed.

Also, at this time, the compressor 18 is disposed at the left end of the machine room 17 on the opposite side from the heat radiation opening 20 so as to cross the longitudinal direction of the machine room 17, so that the compressor 18, which is long in the lateral force direction, is used to radiate heat. can be kept as far away from the opening 20 as possible. Furthermore, since the microphone 22 is attached to the compressor 18 at a location opposite to the center of the compressor 18 and at a location farthest from the speaker 21, the microphone 22 is attached to the compressor 18 at both ends of which noise sources are respectively generated. Even when the speaker is in the H mode, those noises can be received accurately, and the influence of the sound from the speaker 21 can be minimized as much as possible. As a result, the above active control when using the groove-type compressor 18 can be performed more easily and accurately.

Of course, in this case, the machine room 17 is connected to the heat radiation opening 2.
Since it communicates with the outside through 0, the compressor 18
The temperature inside the machine room 17 will not rise abnormally due to heat generated during driving. In addition, the machine room cover 19
Since it is made of a material with excellent thermal conductivity, the heat dissipation efficiency of the heat generated in the machine room 17 is improved, and from this aspect as well, the temperature rise in the machine room 17 can be suppressed to a low level. Become.

In the above-described embodiment, the compressor 18 is arranged in an upwardly right-hand direction with respect to the longitudinal direction of the machine room 17 in FIG. It is also possible to have a slanted arrangement.
Further, in this case, the microphone 22 is arranged as shown by the same two-dot chain line. Furthermore, as shown in FIG. 5, if the length of the compressor 23 is shorter than the compressor 18 of the above-described embodiment, the comb 1 connector 23 is arranged perpendicular to the longitudinal direction of the machine room 17. At the same time, the microphone 22 is arranged on the left inner surface of the machine room 17 so as to face the center part of the compressor 23. With this configuration, the above active control can be performed with higher accuracy.

In addition, the present invention is not limited to the embodiments shown in the drawings described above; 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 and changes can be made without departing from the scope of the invention.

[Effects of the Invention] According to the present invention, as is clear from the above description, a machine room in which a picture-type compressor is housed is closed leaving a heat dissipation opening located near one end of the machine room. By setting one dimension of the three-dimensional dimensions in the machine room to be larger than the other method, the frequency band in which the constant pressure waves of the sound in the machine room are subject to muffling can be set. Since the above structure is configured so that only one mode is established, when performing active control in which the noise generated in response to the drive of the compressor in the non-sealed machine room is canceled by the signal sound from the control sound generator, This makes it possible to simplify the active control and improve control accuracy. Furthermore, in the present invention, by arranging the horizontal compressor at the other end of the machine room on the opposite side from the heat dissipation opening and the control sound generator so as to intersect with the longitudinal direction of the machine room, By locating the compressor as far as possible from the heat dissipation opening, which is the outlet of the row, and by installing the sound receiver at a location facing the center of the compressor and as far away from the control sound generator as possible, The sound receiver is able to receive the noise generated from the horizontally long compressor as accurately as possible, and is also able to receive as little influence as possible from the sound emitted from the control sound generator. Active control can be carried out more easily and with higher precision when using the .

[Brief explanation of the drawing]

1 to 4 show one embodiment of the present invention, and FIG. 1 is a schematic plan view of the main part, FIG. The figure is a schematic perspective view for explaining the dimensional relationship of main parts, and FIG. 4 is a longitudinal sectional view of the refrigerator. Further, FIG. 5 is a diagram corresponding to FIG. 1 showing a different embodiment of the present invention. FIG. 6 is a schematic configuration diagram showing the principle of silencing by active control, and FIG. 7 is a noise level characteristic diagram. In the figure, 11 is the refrigerator body, 17 is the machine room, 18 is the compressor, 19 is the machine room cover, 20 is the heat radiation opening, 2
] is the speaker (control sound generator), 22 is the microphone (
receiver), 2'3 indicates the compressor. Applicant Toshiba Corporation Agent Patent Attorney Tsuyoshi Sato

Claims (1)

[Claims] 1. A horizontal compressor is housed in a machine room, and a sound receiver converts the sound generated when the compressor is driven into an electrical signal, and this electrical signal is processed by a computing unit. In the noise reduction device for a cooling device, the sound emitted from the machine room to the outside is actively canceled by operating a control sounder based on a signal generated by the machine room. By configuring the machine room in a closed state while leaving the heat dissipation openings located, and by setting one dimension larger than the other dimensions in the three-dimensional directions within the machine room, the noise in the machine room can be reduced. The configuration is such that only the first-order mode of the standing wave is established below the frequency band to be canceled, and the control sound generator is mounted near the heat dissipation opening facing the opening, and the The compressor is disposed at the other end of the machine room so as to intersect with the longitudinal direction of the machine room, and the sound receiver is located at a location facing the center of the compressor and located as far away from the control sound generator as possible. A silencer for a cooling system, characterized in that it is installed in a silencing device.