JP2624858B2 - refrigerator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a refrigerator having a sound deadening function.

(Prior Art) As is well known, most home refrigerators have an integrated compressor that generates noise. Such a home refrigerator is usually installed in a living room space in many cases. Therefore, how to reduce the noise is an important issue.

In the case of refrigerators, the majority of the noise generated is from the compressor and the piping connected to it. That is, the compressor generates noise such as motor rotation noise, fluid noise due to the compressed gas, and mechanical noise of the compression mechanism.
Further, a piping system connected to the compressor also vibrates in response to the vibration of the compressor, thereby generating noise.

For this reason, a machine room having a so-called duct structure that normally accommodates a compressor that is a noise source and a piping system connected to the compressor is provided, and noise that leaks outside due to the presence of the machine room is reduced. The method is adopted. In addition, a rotary type compressor with relatively low noise is used, the vibration isolating support structure of the compressor is improved, the shape of the piping system is improved to achieve attenuation in the vibration propagation path, or the compressor and piping system Measures have also been taken to arrange a sound absorbing member or a sound insulating member around to increase the sound absorption volume in the machine room and increase the noise transmission loss.

However, it is necessary to provide an opening for heat dissipation for releasing heat generated by driving the compressor to the outside in the wall of the machine room. For this reason, noise leaks to the outside from this opening, and there is a problem that the noise level can be reduced at most by about 2 dB (A) even if the noise reduction measures described above are taken.

Therefore, recently, sound control technology has been applied to artificially create a sound with the opposite phase, the same wavelength, and the same amplitude as the noise, and this artificially created sound tries to leak from the opening of the machine room. Attempts have been made to reduce the noise of the refrigerator by actively canceling the noise. The active noise reduction control basically converts a sound from a noise source into an electric signal with an acoustic sensor such as a microphone provided at a specific position, and also processes the electric signal through a computing unit to generate a speaker. By operating a control sounding device such as a noise, an artificial sound having the opposite phase, the same wavelength, and the same amplitude as the noise is generated, and the artificial sound interferes with the original sound to attenuate the original sound. I have. This active silence control will be further described with reference to FIG.

That is, in FIG. 6, X _{s represents} the sound generated by the compressor S, which is a noise source, Xa, the sound generated by the speaker A, which is a control sounding device, and the microphone M, which is an acoustic sensor.
Where X _m is the sound received at, X _o is the sound at the target point O, and G _AM , G _AO , G _SM , G _SO
The following equation holds as a two-input two-output system. Each of the above acoustic transfer function _{G AM, G AO, G SM} , meaning of G _SO is preceding subscript transmission side, in which the subsequent index corresponds to the responder, for example, G _AM input side speaker A And the microphone M
Shows the value when the measurement was made with the output side.

From the above equation, the sound Xa speaker A should _{occur, Xa = (- G SO ·} X m + G SM · X o) is obtained as a _{/ (G SM · G AO -G} SO · G AM). In this case, since the goal is to reduce the sound level at the sound-reduction target point O to zero, _Xo = 0 can be set. As a result, _{Xa = X m · G SO /} (G SO · G AM -G SM · G AO). As can be seen from this equation, the sound X _o at the silencing target point O
Is set to zero by adding a filter corresponding to a transfer function G represented by the following equation to the sound X _m received by the microphone M: G = G _SO / (G _SO · G _AM −G _SM · G _AO ) Is generated from the speaker A, the sound level at the control target point O can be reduced to zero theoretically. An arithmetic unit H is provided to perform such processing. In the configuration of FIG. 6, _GSM and _GSO in equation (1) cannot be directly measured. Therefore, using the relationship of G _SO / G _SM = G _MO ,
Equation (1) is modified to G = G _MO / (G _AM · G _MO −G _AO ) (2) to obtain G from G _AM , G _MO , and G _AO .

However, there is the following problem even in a refrigerator that attempts to reduce noise by adopting such an active noise reduction control method. That is, even if the filter of the arithmetic unit H is created in advance by obtaining the transfer function of the equation (2), the transfer function changes due to the environment of the installation location, particularly, a change in the speed of sound due to a change in temperature or atmospheric pressure. In the case of a refrigerator, the temperature in the machine room changes because the compressor generates heat. When the temperature inside the machine room changes in this way, the acoustic transfer function also changes accordingly. For example, the speed of sound is about 344 m / s at 20 ° C,
When it changes by 1 ° C, it changes by 0.6m / s. Therefore, if the temperature is 30
At ℃, the speed of sound becomes 350 m / s.

Considering a sound of 100 Hz, one wavelength is 3.44 m when the sound speed is 344 m / s, and 3.5 m at 350 m / s. The width of a general refrigerator is about 66 cm, and in the case of a sound of 100 Hz, the phases entering the width direction of the refrigerator are 69 deg and 120 deg, respectively, and a phase difference of 51 deg is generated. Generally, in order to expect a noise reduction effect of 5 dB or more, the phase shift must be within 30 deg. Therefore, the phase of the sound is 50de due to the change in temperature.
If g is shifted, the silencing effect can hardly be expected.

(Problems to be Solved by the Invention) As described above, in the conventional refrigerator provided with the active noise reduction device, if the acoustic transfer function fluctuates due to the installation environment of the refrigerator or changes over time, the additional sound for noise reduction changes. There was a problem that the effect was reduced.

Therefore, an object of the present invention is to provide a refrigerator that can solve the above-described problems and can always operate in a low-noise state.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention provides a compressor, which is intermittently driven in accordance with a temperature state in a refrigerator, in a machine room having a heat radiation opening. And a silencer that actively silences noise that is about to leak out of the machine room through the heat dissipation opening. A first acoustic sensor to be detected, a control sounding device for generating a sound required for silencing, and a filter having characteristics corresponding to the acoustic transfer characteristics in the machine room were processed on the output of the first acoustic sensor. First control means for driving a sound generator for control with a signal, a random noise generator, a second acoustic sensor for detecting a volume of a heat radiation opening of a machine room, and random noise during a stop period of the compressor. Above at generator output Is generated from the control sound producer levels lower random noise of the compressor sound,
At this time, a sound transfer characteristic in the machine room is measured using data including data obtained by the first and second sound sensors, and a filter characteristic in the first control means is corrected based on the measurement result. 2 control means.

(Operation) When the compressor is stopped, the transfer function is measured using random noise (however, for _GMO , the transfer function is measured during the period when the compressor is operating), and the system is identified. Note that the level of random noise at the time of measurement is suppressed to a value lower than the sound pressure during rotation of the compressor. Then, a silencing operation is performed while the compressor is rotating. That is, in the present invention, the compressor of the refrigerator is not always operated, but attention is paid to the point that the compressor is intermittently operated according to the temperature in the refrigerator. I have to. Since the flow of heat into and out of the machine room is not so intense, the temperature in the machine room does not change so much in a short period of time.
However, when viewed on a daily or seasonal basis, the temperature in the machine room changes although it is warm but follows changes in the outside air temperature. When the temperature in the machine room changes, the sound transmission characteristics in the machine room change, so that there is a possibility that the noise reduction effect is reduced. However, using the shutdown period of the compressor as in the present invention,
With the method to identify the noise reduction system, even if the acoustic transfer characteristics in the machine room change due to the installation environment or changes over time, the filter characteristics can be changed by following this change,
As a result, operation in a low noise state is always possible.

(Example) Hereinafter, an example is described, referring to drawings.

FIG. 3 shows a schematic configuration of the electric refrigerator 1 applied to the present invention. The electric refrigerator 1 has a housing 2 divided vertically into three parts like a known refrigerator, and a freezing room 3, a refrigerator room 4, and a vegetable room 5 are provided in this order from the top. Each room is provided with a door which can be opened and closed at the front. Further, a cooler 6 and a blower 7 are arranged at a rear position in the freezing room 3.

A machine room 8 having a duct structure is provided at a lower portion on the rear side of the housing 2, and a compressor 9 that is controlled to be turned on and off according to the temperature in the refrigerator and a piping system 10 connected to the machine room 8 are provided in the machine room 8. Is housed.

The machine room 8 is closed by a cover 11 as shown in FIG. Therefore, the compressor 9 and the piping system 10 are housed in a closed space. And
The cover 11 has an opening 12 for discharging heat generated when the compressor 9 is operated to the outside.

In the machine room 8, there are arranged acoustic sensors as components of the silencer 21 described below, that is, microphones 22 and 23, and a control sounding device, for example, a speaker 24. The microphone 22 is arranged in a deep place in the machine room 8, the microphone 23 is arranged near the opening 12, and the speaker 24 is arranged near the opening 12.

The silencer 21 is configured as shown in FIG.
That is, the outputs of the microphones 22 and 23 and the ON / OFF signals to the compressor 9 are introduced into the muffling controller 25.

The muffling controller 25 includes a first control system and a second control system.

The first control system, the characteristic compressor 9 while in the operating state, the output X _m of the microphone 22, the acoustic transfer function G _AM of the machine chamber 8, represented by G _AO, determined by G _MO (2) formula The signal is processed by applying the above-mentioned filter, and the signal is supplied to the speaker 24 via the changeover switch 26.

On the other hand, when the compressor 9 is operating, the second control system controls the sound transfer function G between the microphones 22 and 23.
Measure _MO . When the compressor 9 is stopped, the output of the random noise generator 27 is switched by the changeover switch 26.
, A random noise having a level lower than that of the compressor sound is generated by the speaker 24, and the sound transfer function _GAM and the speaker between the speaker 24 and the microphone 22 are obtained from the outputs of the microphones 22 and 23 at this time. Two
The acoustic transfer function G _AO between 4 and the microphone 23 is measured. Then, using these acoustic transfer functions G _AM and G _AO and the above-described acoustic transfer function G _MO , G in equation (2) is calculated,
The filter characteristic in the first control system is corrected based on the calculation result. Note that the sound transfer function
In order to measure G _AM and G _AO , the level of random noise output from the speaker 24 is set to be, for example, 45 dB (A) or less. That is, if the sound is not silenced using the silencer, the noise level at the opening 12 is 55 dB.
Assuming that it was (A), if the silencer was used and it decreased by 10 dB (A) to 45 dB (A), the random noise level was set to 45 dB (A) or less and the random noise itself became noise. I try not to appear.

With such a configuration, when the compressor 9 is in the operating state, a sound for canceling the noise in the opening 12 is output from the speaker 24 by the operation of the first control system in the muffling controller 25.

When the compressor 9 is stopped, the sound transfer functions G _AM and G _AO are measured by the operation of the second control system in the silencing controller 25, and the sound transfer functions and the sound measured during the operation of the compressor 9 are measured. G of the equation (2) at that time is calculated using the transfer function _GMO, and the filter characteristic in the first control system is corrected to a characteristic at which the maximum noise reduction effect is obtained at this time. .

FIG. 2 is a diagram showing the operation described above. The level indicated by the two-dot chain line in the figure indicates the noise level when sound is not muted. As can be seen from this figure, the compressor 9
During the off period, the acoustic transfer functions G _AM and G _AO are measured using random noise equal to or lower than the compressor sound pressure level. FIG. 5 is a flow chart of an operation for correcting the filter characteristics in the first control system in the second control system.

As described above, even if the temperature in the machine room 8 changes due to a change in the outside air temperature or the like, and the sound transfer characteristics in the machine room 8 change with the change, the characteristics of the filter are changed by following the change. Therefore, the muffling device 21 can always be maintained in a state where the maximum muffling effect is obtained at that time. Therefore, the noise reduction of the refrigerator can be stably realized.

[Effects of the Invention] As described above, according to the present invention, even if the sound transfer characteristic of the machine room changes, the noise suppression system can be corrected by following the change, so that low-noise operation can always be performed. .

[Brief description of the drawings]

FIG. 1 is a block diagram of a silencer incorporated in a refrigerator according to an embodiment of the present invention, FIG. 2 is a diagram for explaining the operation of the silencer, and FIG. FIG. 4 is an exploded perspective view for explaining the structure of a machine room provided in the refrigerator, FIG. 5 is a flow diagram for explaining the operation of the muffler, and FIG. It is the schematic which shows the structure of the active silencer built into the conventional refrigerator. DESCRIPTION OF SYMBOLS 1 ... Refrigerator, 8 ... Machine room, 9 ... Compressor, 10 ... Piping system, 12 ... Opening, 21 ... Muffler, 22,23 ... Microphone, 24 ... Speaker, 25 ... Muffler controller, 26 ... Changeover switch, 27 ... random noise generator.

Claims (1)

(57) [Claims] 1. A refrigerator main body in which a compressor intermittently driven in accordance with a temperature state in a refrigerator is housed in a machine room having a heat-dissipating opening, and a compressor is provided from the heat-dissipating opening of the machine room to the outside. A silencer that actively silences the noise that is about to leak out, wherein the silencer comprises:
A first acoustic sensor for detecting noise in the machine room, a control sounder for generating a sound required for silencing, and an output of the first acoustic sensor according to an acoustic transfer characteristic in the machine room. A first control unit for driving the control sounding device with a signal processed by applying a characteristic filter, a random noise generator, and a second control unit for detecting a sound volume of the heat radiation opening of the machine room. An acoustic sensor, and a random noise having a lower level than the compressor sound is generated from the control sounding device at the output of the random noise generator during a stop period of the compressor. At this time, the first and second acoustic sensors generate Second control means for measuring sound transfer characteristics in the machine room using data including the obtained data, and correcting filter characteristics in the first control means based on the measurement result; Refrigerators characterized by being provided.