JPH083398B2 - Silencer for cooling system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Industrial field of application) The present invention actively suppresses noise from a silencer used in a cooling device such as a refrigerator, and particularly from a machine room accommodating a compressor. The present invention relates to a sound deadening device for a cooling device.

(Prior Art) A cooling device using a compressor, for example, a refrigerator is often installed in a living room of a general household and is continuously operated regardless of the season. Noise reduction is an issue. In this case, the most problematic noise source of the refrigerator is noise from the machine room in which the compressor and the piping system connected to the compressor are stored. That is, in the machine room, the compressor itself generates relatively large noise (operation noise of the compressor motor, fluid noise due to compressed gas, mechanical noise in movable mechanical elements of the compression mechanism portion, etc.) and is connected to the compressor. The piping system also generates noise due to its vibration, and such machine room noise accounts for the majority of refrigerator noise. Therefore, suppressing the noise from the machine room greatly contributes to the noise reduction of the entire refrigerator.

Therefore, in the past, in order to reduce noise from the machine room, in addition to noise reduction of the compressor itself (for example, adoption of a rotary type compressor), improvement of the vibration isolation support structure of the compressor and improvement of the shape of the piping system etc. By reducing the vibration in the vibration propagation path by arranging it, or by arranging a sound absorbing member and a sound insulating member around the compressor and the piping system, the sound absorption volume in the machine room increases and the noise transmission loss increases. Increases are being made.

(Problems to be Solved by the Invention) In general, a mechanical room of a refrigerator is provided with a plurality of openings for heat radiation in order to release heat generated by driving a compressor to the outside. Noise will leak from the outside. Therefore, the conventional noise reduction measures as described above are naturally limited, and the noise level reduction effect can be expected to be only about 2 dB (A).

On the other hand, in recent years, with the development of electronics application technologies, especially acoustic data processing circuits and acoustic control technologies, the application of active noise control technology that reduces noise by using sound wave interference has attracted attention. Has been done.
That is, this active control basically converts a sound from a noise source into an electric signal by a sound receiver provided at a specific position, and controls the electric signal based on a signal processed by an arithmetic unit. By operating the sound generator, an artificial sound having a phase opposite to that of the original sound (sound from the noise source) at the control target point and having the same wavelength and the same amplitude is generated from the sounder, and the artificial sound and the original sound are generated. It is intended to attenuate the original sound by causing interference. However, when such active noise control is used to reduce machine room noise in a refrigerator, the machine room is in a non-sealed state and the noise generated in the machine room leaks freely in three dimensions. Since it is below, there is a problem that the active control mode becomes extremely complicated, and it is the actual situation that there is no idea about the practical use of the active noise control in the refrigerator.

The present invention has been made in view of the above circumstances, and an object thereof is to perform active control of canceling noise generated in response to driving of a compressor in a machine room by interference with artificial sound. It is an object of the present invention to provide a muffler for a cooling device, which can simplify the above and improve the control accuracy, and can prevent the characteristic deterioration of the active control device due to the evaporated water from the defrost water evaporation tray.

[Configuration of the Invention] (Means for Solving the Problem) In order to achieve the above-mentioned object, the present invention actively generates a sound generated by driving a compressor housed in a machine room by interference with an artificial sound. In a muffler for a cooling device that cancels out, a partition plate that partitions the machine chamber into a storage space for the compressor and a storage space for a defrost water evaporation tray is provided, and the storage space for the compressor is provided with a heat dissipation opening. Is closed and the one-dimensional dimension of each dimension in the three-dimensional direction in the storage space of the compressor is set to be larger than the other dimension, so that the sound in the storage space of the compressor is The standing wave is configured so that only the first-order mode is established below the frequency band to be canceled.

(Function) For example, in a refrigerator, which is a typical example of a cooling device, in the case of a refrigerator having a general structure, the sound level of noise generated in response to the driving of the compressor is 700H as shown in FIG.
It has the property of increasing in the band of z or less and in the band of 1.5 to 5 KHz. Of the noises corresponding to each of these bands, those on the high frequency side can be easily silenced by the conventional noise reduction technology using a sound absorbing member or the like. Therefore, when the active control of noise is actually performed, the noise on the low frequency side should be the target frequency (about 700 Hz or less in this case).

Thus, as in the present invention, when the inside of the machine room is partitioned by the partition plate into the storage space of the compressor and the storage space of the defrosting water evaporation tray, if the target frequency is about 700 Hz or less, the storage space of the compressor Is the wavelength of the original noise (700Hz) (sound velocity 3
If it is configured in a duct shape so as to be longer than about 50 cm in the case of 40 m / sec), the standing wave of noise generated in the storage space can be established only in the primary mode. With this configuration, the sound generated in the machine room can be regarded as a one-dimensional plane traveling wave, and the sound generated by the compressor and the artificial sound from the control sound generator are interfered with each other. It becomes possible to perform the active control aiming at easily and accurately both theoretically and technically.

In this case, the machine room is partitioned by a partition plate into a storage space for the compressor and a storage space for the defrosting water evaporating dish, so that the moisture containing the moisture evaporating from the defrosting water evaporating dish is
It is possible to prevent the noise from flowing into the muffling space (compressor storage space), and prevent deterioration of the characteristics of the active control device due to moisture.

(Example) Hereinafter, one example in which the present invention is applied to a refrigerator will be described. Prior to this, a principle of silencing by active control used in the present example will be schematically described.

In FIG. 5, 1 is a noise source such as a compressor,
Reference numeral 2 denotes a control target point for which it is desired to muffle noise. The sound from the noise source 1 is converted into an electric signal by a sound receiver 3 such as a microphone, and the electric signal is passed through an arithmetic unit 4 including a filter or the like. The sound generator 5 such as a speaker is driven by the processed signal.

That is, the sound generated by the noise source 1 is S1, the sound generated by the speaker 5 is S2, the sound received by the sound receiver 3 is R1, the sound at the controlled point 2 is R2, and the above-mentioned sound output And the acoustic transfer function between each of the input points is T11, T21, T12, T22,
The following equation holds as a two-input two-output system.

Therefore, the sound S2 to be generated by the speaker 5 is obtained from the above equation as S2 = (-T12 / R1 + T11 / R2) / (T11 / T22-T12 / T21). Since the target is to make the sound level of 0 to 0, it is possible to set R2 = 0. As a result, S2 = R1 · T12 / (T12 · T21-T11 · T22). As can be understood from this equation, in order to reduce the sound R2 at the controlled point 2 to zero, the sound received by the microphone 3
If the sound S2 processed by applying the filter F = T12 / (T12 ・ T21−T11 ・ T22) to R1 is generated from the speaker 5, the sound level at the controlled point 2 should be theoretically zero. You can

Thus, FIGS. 1 to 4 show a first embodiment of the present invention, which will be described below.

That is, in FIG. 4 showing the entire structure of the refrigerator, 11 is the refrigerator main body, and the inside of this is the freezer compartment 1 in order from the top.
2, a refrigerating room 13 and a vegetable room 14 are provided. 15 is a freezer
A cooler arranged at the back of 12 and a fan 16 for supplying the cool air generated by the cooler 15 to the freezing compartment 12 and the refrigerating compartment 13. 17 is a machine room formed at the bottom of the refrigerator body 11,
As shown in FIG. 1, the machine room 17 includes a flat defrost water evaporation tray storage space 18 formed on the front side of the bottom of the refrigerator main body 11,
Compressor storage space 19 formed horizontally behind it
And have. The defrosting water evaporation tray 20 is stored on the pedestal 18a forming the bottom surface of the defrosting water evaporation tray storage space 18 so that it can be taken in and out from the front. On the other hand, as shown in FIG. 2, the compressor storage space 19 is closed on both left and right side surfaces by the left and right side plates 11a and 11b of the refrigerator body 11, and the top and bottom surfaces thereof are closed by the bottom plate 11c of the refrigerator body 11 and the pedestal 19a. In addition, the back surface is closed by the machine room cover 21. On the pedestal 19a, a rotary compressor 22 is disposed on the right side when viewed from the rear side, and in order to radiate heat from the compressor 22, the side edge portion of the machine chamber cover 21 (from the rear side) An elongated rectangular heat radiation opening 21a extending in the up-down direction is formed at the left edge when viewed. still,
The machine chamber cover 21 is formed of a material (for example, metal such as iron) having excellent heat conductivity and large sound transmission loss.

Thus, in the machine room 17, the compressor storage space 19
At the boundary between the defrosted water evaporation tray storage space 18 and the partition plate 23
This partition plate 23 partitions the inside of the machine room 17 into a compressor storage space 19 and a defrost water evaporation tray storage space 18. The partition plate 23 is made of, for example, an iron plate or plastic and has a thickness of about 1 to 1.2 mm, and mounting flanges 23a and 23b are formed at both upper and lower ends as shown in FIG. A drain hose insertion hole 24a and two refrigerant distribution pipe insertion holes 24b are formed at predetermined positions of the partition plate 23, and a drain hose and a refrigerant distribution pipe (not shown) are formed in these insertion holes 24a, 24b. It has been inserted. In this case, an anti-vibration rubber packing (not shown) is provided on the inner periphery of the refrigerant flow pipe insertion hole 24b to prevent the vibration of the refrigerant flow pipe from being transmitted to the partition plate 23. And both refrigerant flow pipe insertion holes 24b
By holding both the refrigerant flow pipes, the resonance caused by the contact between the two refrigerant flow pipes is also prevented. With such a partition plate 23, the compressor housing space 19 is configured in a hermetically sealed manner except for the heat dissipation opening 23a.

The procedure for attaching the partition plate 23 is as follows. First, the two refrigerant circulation pipes (not shown) coming out from the receiving table 18a of the defrost water evaporation tray 20 are connected to the refrigerant circulation pipe insertion holes 24 of the partition plate 23.
Pass through b. Then, the pedestal 18a of the defrosting water evaporation dish 20 is
After connecting to the pedestal 19a of the compressor 22, the partition plate 23
Is fixed to the pedestal 19a of the compressor 22. This fixation is
A screw (not shown) is inserted into the screw insertion hole 24c of the mounting flange 23b at the lower end of the partition plate 23 and tightened. And
The soft tape 25 for sealing is attached to the upper surface of the mounting flange 23a at the upper end of the partition plate 23, and then the refrigerator main body 11 is assembled so as to be covered from above. In this case, soft tape
25 (see FIG. 1) plays a role of sealing the gap between the upper end of the partition plate 23 and the bottom plate 11c of the refrigerator main body 11 and a role of suppressing vibration of the partition plate 23 and preventing chattering noise. .

On the other hand, in FIG. 2, 26 is a compressor storage space 19
A sound receiver, for example, a microphone disposed inside is disposed near the compressor 26 and away from the heat dissipation opening 21a, and converts the sound from the noise source compressor 26 into an electric signal. Is provided. 27
Is a speaker, which is a control sound generator arranged in the compressor storage space 19. This is, for example, the compressor storage space.
It is attached to the back wall of 19 (bottom plate 11c of the refrigerator main body 11) in a portion near the opening 21a for heat radiation in an embedded manner. The speaker 27 is operated by a signal obtained by processing an electric signal from the microphone 26 by a calculator (not shown) of a circuit for generating an anti-phase sound. It is designed to be performed based on the silencing principle by the active control.

Therefore, in the case of the refrigerator configured as described above, the noise level generated in the compressor storage space 19 in the machine room 17 in response to the driving of the compressor 22 is in the range of about 700 Hz or less as shown in FIG. It becomes a state that it has the property of increasing in the band of 1.5 to 5 KHz. Of the noise corresponding to each of these bands, the noise on the high frequency side is
Since it can be attenuated by transmission loss at the compressor storage space, and can be easily silenced by installing an appropriate sound absorbing member in the compressor storage space 19, the microphone 26, the speaker 27, and the calculator as described above are used. The active control of noise may be performed with a target frequency of 700 Hz or less.

Further, when performing active control of noise as described above,
It is important to configure the compressor so that the noise in the compressor housing space 19 becomes a one-dimensional plane traveling wave in order to control the noise easily and accurately both theoretically and technically. Therefore, in the present embodiment, the widthwise dimension W of the compressor housing space 19 is set larger than the depth and height dimensions D and H (specifically, W = 600 mm, D).
= H = 200 mm), the standing wave of the sound in the machine room 17 is constituted only in the first-order mode. That is, for example, assuming that the compressor storage space 19 is a rectangular cavity, the following equation holds.

However, f is the resonance frequency (Hz), Nx, Ny, Nz are the modes in the X, Y, Z directions, and Lx, Ly, Lz are the dimensions in the X, Y, Z directions in the machine room 17 (that is, D , W, H) and C are sound speeds. Therefore, from the above equation, the frequency f of the first standing wave in each of the X, Y, and Z directions
x, fy, fz can be calculated.

That is, as described above, when the depth dimension D = 200 mm, the width dimension W = 600 mm, and the height dimension H = 200 mm are set, the frequency fx of the first standing wave in the X direction is Ny.
= Nz = 0, speed of sound C = 340 m / sec, Similarly, the frequencies fy and fz of the first standing wave in the Y and Z directions are Becomes As a result, the target frequency (= 700Hz)
Below, the standing wave of noise in the compressor storage space 19 is established only in the Y-direction (width direction) mode, and the noise in the compressor storage space 19 can be regarded as a one-dimensional plane traveling wave. it can. Therefore, at the time of silencing by active noise control using the speaker 27 or the like, theoretical treatment of the wavefront becomes easy, and silencing control can be performed easily and accurately.

Further, in the present embodiment, the partition plate 23 that partitions the inside of the machine room 17 into the compressor storage space 19 and the defrost water evaporation tray storage space 18
The compressor storage space 19 is isolated from the defrosting water evaporating tray 20 so that the moisture containing the moisture evaporating from the defrosting water evaporating tray 20 is divided into the compressor storing space 19 side. It can be reliably prevented by the plate 23, and it is possible to prevent the characteristics of the active control equipment such as the microphone 26 and the speaker 27 in the compressor storage space 19 from being exposed to moisture and deteriorating their characteristics. The life of the device can be extended.

Furthermore, in this implementation order, in the compressor storage space 19,
Since no ceramic fin for defrost water evaporation is provided, the problem that sound is reflected by the ceramic fin and the sound pressure distribution is disturbed can be eliminated, and a stable silencing effect can be obtained. Moreover, if the ceramics fins are eliminated, the compressor storage space 19 becomes wider, and the degree of freedom in designing the piping of the refrigerant distribution pipe can be increased, and accordingly, there is an advantage that it is easy to take measures to prevent resonance of the refrigerant distribution pipe.

Of course, in this case, since the compressor storage space 19 of the machine room 17 communicates with the outside through the heat dissipation opening 21a, the temperature inside the machine room 17 may rise abnormally due to heat generated when the compressor 22 is driven. Disappear. Further, since the machine room cover 21 is made of a material having excellent thermal conductivity, the heat radiation efficiency of the heat generated in the machine room 17 is improved, and from this aspect, the temperature rise in the machine room 17 also increases. Will be kept low.

In the above embodiment, the defrosting water evaporation tray 20 and the compressor 22 are arranged in the front and rear in the machine room 17, and the partition plate 23 is provided between them in the width direction so that the compressor storage space 18 is elongated in the width direction. Although not limited to this, for example, the defrosting water evaporation tray and the compressor are arranged on the left and right in the machine room, and a partition plate is provided in the front-rear direction between them to make the compressor storage space elongated in the front-rear direction. Is also good.

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

[Effect of the Invention] According to the present invention, as is clear from the above description,
A partition plate is provided for partitioning the machine room into a storage space for the compressor and a storage space for the defrosting water evaporation tray, and the storage space for the compressor is configured to be closed while leaving the heat radiation opening, and the storage space for the compressor is also provided. By setting the dimension in one direction out of the three-dimensional dimensions in the space to be larger than the dimension in the other direction, the standing wave of the sound in the storage space of the compressor is below the frequency band to be canceled. In the above, since only the primary mode is established, in performing active control in which noise generated in response to driving of the compressor is canceled by the signal sound from the control sounder, simplification of the active control and control accuracy are improved. The improvement can be realized.

Moreover, since a partition plate for partitioning the machine room into a storage space for the compressor and a storage space for the defrosting water evaporation tray is provided, the storage space for the compressor is isolated from the defrosting water evaporation tray.
The defrosting water evaporation tray can reliably prevent the moisture containing the evaporated water from flowing into the compressor storage space side by the partition plate, and the active control equipment in the compressor storage space is exposed to the moisture and It is possible to prevent deterioration of characteristics, further improve the control accuracy of active control, and prolong the life of active control equipment.

[Brief description of drawings]

1 to 4 show an embodiment of the present invention. FIG. 1 is a vertical side view of a lower part of a refrigerator, FIG. 2 is a rear view of a machine room with a machine room cover removed, and FIG. Is an enlarged perspective view of the partition plate, and FIG. 4 is a vertical side view of the entire refrigerator. Further, FIG. 5 is a schematic configuration diagram showing a silencing principle by active control, and FIG. 6 is a noise level characteristic diagram. In the figure, 11 is a refrigerator main body, 17 is a machine room, 18 is a defrosted water evaporation tray storage space, 19 is a compressor storage space, 20 is a defrosted water evaporation tray, 21 is a machine room cover, 21a is a heat dissipation opening, 22 is a compressor, 23 is a partition plate, 26 is a microphone (sound receiver),
Reference numeral 27 indicates a speaker (control sound generator).

Claims (1)

[Claims] 1. A compressor and a defrosting water evaporation tray are housed in a machine room, and the sound generated when the compressor is driven is converted into an electric signal by a sound receiver, and this electric signal is processed by a calculator. In a silencer for a cooling device, which is configured to actively cancel the sound emitted from the machine room to the outside by operating a control sounder based on a signal, in the machine room, a storage space for the compressor is provided. A partition plate is provided to partition the storage space of the defrosting water evaporation tray into the storage space of the compressor in a closed state except for the heat radiation opening. By setting the dimension in one direction to be larger than the other dimension among the dimensions, the standing wave of the sound in the compressor storage space is set to be primary in the frequency band below the cancellation target. Silencer cooling apparatus characterized by being configured so holds only over de.