JPH02225960A - Noise suppressor for cooling device - Google Patents

Abstract

PURPOSE:To simplify active control by forming the shape of a machine room into L-shape or a horizontal U-shape viewed in a plane for setting a size of the machine room among three-dimensional sizes to be the same, the machine room to be accommodated with a compressor. CONSTITUTION:A machine room 17 is constructed into a closed state leaving a heat dissipation opening part 21a as it is. Further, the shape in the machine room 17 is formed into a L-shape or a horizontal U-shape viewed in a plane so as to set a size of the machine room among three-dimensional sizes larger than the other sizes. Thereby, only a primary mode is formed in a frequency band or less where a standing wave of a sound in the machine room 17 is to be cancelled out. Thus, simplification of the active control and improvement of control accuracy are assured to reduce noises.

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 an extinguisher 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 noise source for refrigerators is the noise coming from the machine room at the bottom of the refrigerator body, which houses the compressor and the piping system connected to it. That is, in the upper SP machine room, the compressor itself 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 the compressor The connected piping system also generates noise due to its vibrations, and the fresh 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, in the past, measures to reduce noise from the machine room have focused on reducing the noise of the compressor itself (for example, using a rotor-type fan breather), improving the vibration-proof support structure of the compressor, and changing the shape of the piping system. 6 etc. to attenuate vibrations in the vibration propagation path, 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.

(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 'F8 acoustic data processing circuits and acoustic control technology, active noise control technology that uses sound wave interference to reduce noise has been applied. is attracting attention. In other words, 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 then controls the sound based on the signal processed by a computing unit. By operating the artificial η generator, the generator generates an artificial η that has the opposite phase, the same wavelength, and the same amplitude as the original sound (sound from the noise source) at the control target point, and produces an artificial sound with the same wavelength and amplitude. The idea is to attenuate the original sound by causing it 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. As a result, there is a problem that the active control mode is extremely complicated, and the reality is that the practical application of active noise control in refrigerators is uncertain.

The present invention has been made in view of the above circumstances, and its purpose is to perform active control in which the noise generated in response to the drive of a compressor in an unsealed machine room is canceled by interference with artificial sound. It is an object of the present invention to provide a silencing device for a cooling device, which can simplify its active control and improve control accuracy, and can sufficiently exhibit a noise reduction effect.

[Structure of the invention] (Means for solving the problem) In order to achieve the above object, the present invention provides a cooling device main body F.
In a noise damping device for a cooling device, the sound generated by the drive of a compressor housed in a machine room of a machine is actively canceled by interference with artificial sound, the machine room being left with an opening for heat radiation. In addition to configuring the machine room in a closed state, the shape of the machine room is L-shaped or U-shaped when viewed from above in order to set one dimension of the three-dimensional dimensions in the machine room larger than the other dimensions. By forming this, the standing wave of sound in the machine room is configured so that only the first mode is established below the frequency band to be canceled.

(Function) For example, in the case of a refrigerator, which is a typical example of a cooling device, in the case of a membrane structure, the acoustic level of the noise generated in response to the drive of the compressor is 700% as shown in Fig. 6.
It is clear that the sound becomes louder in the frequency band below about Hz and in the frequency range of 1.5 to 5 KHz. 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, it is sufficient to set the noise on the low frequency side to the target frequency (in this case, approximately 700 Hz or less). In this way, when the target frequency is about 700 Hz or higher, two directions of the height, depth, and width inside the machine room are set to the wavelength of the original noise ('g,'speed', 340 m, 50 m in the case of 7 seconds).
If the remaining 11 no.j directions are set to longer than the above wavelength, only the first mode of the standing wave of noise generated in the machine room will be established.

Therefore, by forming the shape of the machine room into an L-shape or a U-shape when viewed from above, one dimension of the three-dimensional h° direction inside the machine room can be set larger than the other dimensions. It can be configured so that only the first mode exists below the frequency band where the standing waves of sound are to be canceled (target frequency), and when configured in this way, the sound generated in the machine room is It can be regarded as the original plane traveling wave, and the sound from the compressor is silenced by crossing the sound with the artificial air from the control generator at the heat radiation opening, which is the outlet to the outside. It becomes possible to easily and precisely perform active control in theory and technology. In addition, as mentioned above, by forming the machine room into an L-shape or a U-shape, it is possible to sufficiently secure one direction in which the machine room extends. Even if the compressor as a source of noise Tg has a size in its extending direction, the above active control can be performed.

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) An example in which the present invention is applied to a refrigerator will be described below. Prior to this, the extinguishing principle by active control used in this example will be briefly described.

In Figure 5, 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
When the sound from the source is converted into electricity (No. 3) by a sound receiver 3 such as a microphone, this electricity No. 13 is processed through an arithmetic unit 4 including a filter, etc., and the processed signal is used to output a signal from a speaker, etc. It is adapted to drive the sound generator 5.

That is, the sound generated by the noise source 1 is S11, the sound generated by the speaker 5 is 82, the sound received by the microphone 3 is R1, the sound at the control target point 2 is R2, and the above-mentioned sound output and human power are The g-1jP transfer function between each point is Tit,
T21. T1.2. When T22 is assumed, the following equation holds true as a two-man power two-output system.

Therefore, the sound S2 that should be generated by the speaker 5 is calculated from the above equation as follows: S2- (-TI2・R1+Tth・R2)/(T11・
T22-TI2・T21), but in this case, since the goal is to make the sound level at control pair 'A;i'i 2 zero, it can be set as R2-0. . As a result, S2-R1-T12/
(TI2◆T 21- T 1.1-722).

As can be understood from this equation, the sound R2 at the control target point 2
In order to make it zero, the sound Rt received by microphone 3 is given by F-TI2/(T12・T 21- T 11- T
22) If the filtered and processed sound S2 is generated from the speaker 5, the sound level at the control target point 2 can be theoretically reduced to zero.

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 1' 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. 17 is a machine room formed at the lower part of the back side of the refrigerator body 11, and inside this is a rotary type compressor ]8
A condenser vibrator 19 and a defrosting water evaporator 20 using so-called ceramic fins are housed.

Now, Figures 1 and 2 (here, capacitor vibe 1
9 and the defrosting water evaporator 20 are omitted), the machine room 17 includes a main body portion 17a extending in the width direction of the refrigerator main body 11, and a main body portion 17a extending in the depth direction on the left side of the main body portion 17a in the figure. It is formed into an L-shape when viewed from above by the protruding portion 17b protruding from the side, and has a rectangular opening only on the back side, and this opening portion is closed by the machine room cover 21. It looks like this. At this time, the peripheral edge of the machine room cover 21 is airtightly attached to the opening edge of the machine room 17, and the left edge in FIG. opening 2
1a is formed.

In other words, when the machine room cover 21 is installed, the machine room 17
is in a closed state leaving the heat dissipation opening 21a. Note that the machine room cover 21 is made of a material (for example, metal such as iron) that has excellent thermal conductivity and high sound transmission loss.

Reference numeral 22 denotes a sound receiver such as a microphone arranged in the machine room 17, and this is arranged so as to face the compressor 18 from the side opposite to the heat radiation opening 21a (the right side in FIG. 1). Compressor 1, which is the source of noise,
It is provided to convert the sound from 8 into an electrical signal. Reference numeral 23 denotes a speaker serving as a control sound device disposed in the machine room 17, and this is mounted and supported, for example, at a portion of the machine room 17 on the left side near the heat dissipation opening 21a. The speaker 23 is operated by a signal obtained by adding an electric signal from the microphone 22 by an arithmetic unit (not shown) in an anti-phase sound generation circuit, and the above-mentioned electric signal The second addition is performed based on the above-mentioned active control silencing principle.

Therefore, in the case of the refrigerator configured as described above, the noise level generated in the machine room 17 in response to the drive of the compressor 18 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 where H 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 21, etc.
The microphone 22 as described above can be easily muffled by installing an appropriate suction member inside the microphone 22.
．． The active control of noise by the speaker 23 and the computing unit is as follows:
The target frequency may be 00 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 W-plane traveling wave, both theoretically and technically. To do it easily and accurately! It becomes important.

Therefore, in this embodiment, as shown in FIG.
When the width and height dimensions of the main body portion 17a in the machine room 17 formed in the shape of a letter are Dl, W, and H, and the depth dimension of the protruding portion 17b is D2, the extension direction of the machine room 17 is When viewed at the center of the machine room 17, the dimensions of can be regarded as (W+D to -D) (see the dotted chain line A in Figure 2), and in this extending direction, which is one of the three dimensions, = J ° method (W + D2 - DI), main part 17
Set larger than the depth dimension of a and the height dimension H (
Specifically, W + D 2- D H-60011%
(D-H-200 ms) 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#X X + y y
+ Zl, 7. /2 However, f is the resonance frequency (Hz), NX, Ny.

Nz is the th mode of the traveling wave in each of the two-dimensional x, y, and z directions, and Lx, Ly, and Lz are the dimensions of the traveling wave in the machine room 17 in the x, y, and z directions (that is, Dt, W D2-D
l, H), C is the speed of sound. Therefore, from the above formula, X,
Frequencies fx, f of the first standing wave in each direction of Y and Z
y and fz can be found.

That is, as described above, the depth/j dimension of the main body portion 17a is −200 mm, and the 1 dimension (W+
D7 DI)-600mm, height/J゛ method H-20
()g+s, the frequency fX of the standing wave of 1'tr11 in the X direction is Ny - NZ
-〇, the sound speed is C-340 m/sec, fx -340,/2 850Hz, and similarly, the frequencies fy and fz of the first standing wave in the Y and Z directions are fy-340,1,/2 - 283 Hz fz -340,2) /2 -850H2. As a result, the target frequency (-700H
z) In the following, the standing wave of noise in the machine room 17 is established only for the mode in the Y direction (extending direction of the machine room 17).
], and the noise in the machine room 17 is one-dimensional.
However, it can be regarded as a traveling wave. Therefore, when silencing by active noise control using the speaker 23 or the like, the theoretical handling of the wavefront corresponds to the container, and the silencing control can be performed with high precision for each container. As in this embodiment, by forming the machine room 17 in an L-shape when viewed from above, a sufficient dimension in the extending direction of the machine room 17 can be secured, so that it can be used, for example, in a small refrigerator. Even if the widthwise dimension W of the machine room 17 cannot be secured sufficiently, or even if the noise source has a size in the extending direction of the machine room 17, such as a horizontal rotary compressor, noise can be reduced by active control. can be realized.

Of course, in this case, the machine room 17 is connected to the heat radiation opening 2.
Since it communicates with the outside through 1a, compressor 1
The temperature in the machine room 17 will not rise abnormally due to heat generated when the motor 8 is driven. In addition, machine room cover 2
Since 1 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 is kept low. You will be able to control it.

Incidentally, in the above embodiment, the machine room 17 is formed into an L-shape when viewed from above, but the shape may be a mouth-shape when viewed from above.

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

[Effects of the Invention] According to the present invention, as is clear from the above description, the machine room in which the compressor is housed in the lower part of the cooling device main body is
In addition to configuring it in a closed state leaving an opening for heat dissipation, the shape of the machine room was viewed in plan to set one dimension of the 317 three-dimensional direction inside the machine room larger than the other dimension. By forming it into an L-shape or mouth-shape, the standing wave of the sound in the machine room is configured so that only the first mode is established below the frequency band where the noise reduction pair 9 is formed. When carrying out active control in which the noise generated in response to the drive of the compressor is canceled by the signal sound from the control sound generator, it is possible to simplify the active control and improve the control accuracy. be. Further, in the present invention, as described above, by forming the machine room into an L-shape or a mouth-shape when viewed from above, a sufficient dimension in the extending direction of the machine room can be ensured. Even if the compressor is small in size, or even if the noisy compressor is large in the extending direction of the machine room, noise reduction can be achieved through active control.

[Brief explanation of the drawing]

Figures 1 to 4 show one embodiment of the present invention. Figure 1 is a perspective view showing the main parts in an exploded state, Figure 2 is a schematic plan view of the machine room, and Figure 3 is the main parts. FIG. 4 is a longitudinal sectional view of the refrigerator. Also,
FIG. 5 is a schematic configuration diagram showing the principle of silencing by active control, and FIG. 6 is a noise level characteristic diagram. In the figure, 11 is the refrigerator main body (cooling device main body),] 7 is the machine room, 18 is the compressor, 20 is the defrosting water evaporation device, 21
21a is a heat radiation opening, 22 is a microphone (receiver), and 23 is a speaker (control sound generator). Applicant: Toshiba Corporation

Claims (1)

[Claims] 1. A compressor is housed in a machine room provided at the bottom of the cooling device main body, and a sound receiver converts the sound generated as the compressor is driven into an electrical signal, and the electrical signal is A sound damping device for a cooling device that actively cancels out sound radiated from the machine room to the outside by operating a control sound generator based on a signal processed by a computing unit. In addition to configuring the machine room in a closed state leaving an opening for heat dissipation, the shape of the machine room was viewed in plan to set one dimension larger than the other dimension among the three-dimensional dimensions inside the machine room. A cooling device characterized in that the cooling device is formed into an L-shape or a U-shape so that only the primary mode of the standing wave of sound in the machine room is established below the frequency band to be canceled. Device.