JPH0580776A - Active muffling device - Google Patents

Abstract

PURPOSE:To muffle with good follow-up performance without detecting vibration generating the noise by generating a signal which is opposite in phase from and equal in width to the noise according to information regarding rotation including a rotation command signal and actively eliminating the noise. CONSTITUTION:In the case of an active muffling device which eliminates a noise generated by the compressor of a refrigerator driven by a DC brushless motor, the DC brushless motor of the compressor 21 as a noise source provided in the machine chamber 31 of the refrigerator is driven through a commutator 7, but the DC brushless motor rotates its rotor in synchronism with the rotating speed of a rotating magnetic field, so the rotating speed of the rotor can be known in the stage wherein a driving control means 23 controls a signal driving the commutator 7. A control means 25 puts a sound generator 27 for control in operation according to the signal generated by processing the rotating speed and an artificial sound which is opposite in phase and has the same waveform and amplitude with the noise from the compressor 21 is generated at the opening part 33 of the machine chamber 31 and made to interfere with the noise, which is attenuated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active muffling apparatus that actively muffles noise generated by rotation of a motor used to operate a compressor, such as an electric refrigerator.

[0002]

2. Description of the Related Art In order to muffle noise generated from the rotating body of a motor for operating a compressor of a refrigerator, for example, an active muffler of this type is usually applied with an acoustic control technique to invert the noise. A sound of homologous amplitude is artificially formed, and the artificially created sound actively cancels the noise that leaks from the opening of the machine room that houses the compressor, motor, etc. It is designed to make noise.

This active silencer basically detects a sound from a noise source by a detection means such as a microphone provided at a specific position, converts it into an electric signal, and converts this electric signal into a signal processed by a computing unit. By operating a control sounding device such as a speaker based on the sound source, an artificial sound of an opposite phase, the same wavelength, and the same amplitude is generated from the sounding device at the opening, which is a desired point of silence for the original sound from the noise source, The signal sound and the original sound are interfered with each other to attenuate or mute the original noise.

The noise generated by the refrigerator compressor is
Rotational noise (rotational frequency and its harmonics) generated by the rotation of the mechanism, and motor noise (twice the power supply frequency and its harmonics) caused by electromagnetic torque that acts between the stator and rotor of the motor. It consists of

Conventionally, an induction motor operating at a commercial frequency is generally used to drive a compressor. Since the rotor of an induction motor rotates with a rotating magnetic field due to the principle of torque generation, the motor noise and the rotation noise have different frequencies.

That is, in the active control, as shown in FIG. 4, a signal from a microphone 42 provided in the vicinity of the compressor 41, which is a noise source, is supplied to the rotational frequency detecting means 4 as a signal.
3, or as shown in FIG. 5, the signal from the signal pickup 52 directly attached to the compressor 41 is supplied to the rotation frequency detecting means 53 to detect the rotation frequency of the compressor, and the detected compressor is detected. Is supplied to the control means 45 to generate a signal for silencing noise generated due to the rotation of the compressor, and the frequency of the power supplied to the compressor 41, which is a noise source, is detected by the power frequency detecting means 44. And supplies the detected power supply frequency to the control means 45 to generate a signal for silencing electromagnetic noise generated due to the power supply frequency. The mute signal thus generated is output from the control sounder 46, which is a speaker, and interferes with the noise from the compressor 41, which is a noise source, in the opening 54 of the machine room 55 in which the compressor 41 is provided. Thus, the noise from the compressor is silenced or reduced, and the noise from the compressor is prevented from leaking to the outside. A microphone 47 is provided immediately in front of the opening 54, detects a sound silenced in the opening, and feeds back the detected sound to the control means 45.

When the microphone 42 is used, a sound other than the compressor, for example, an artificial sound for noise elimination generated from a speaker for generating a muffling signal in a duct which is a machine room accommodating the compressor of the refrigerator is generated. There is a possibility of entering. Further, since the vibration pickup 52 is directly attached to the compressor and has a high temperature (100 ° C. or higher), heat resistance is required. Furthermore, since it is necessary to separate the charge amplifier for amplifying the weak signal output from the vibration pickup from the compressor as a measure against temperature, there is a problem that the signal line is vulnerable to noise.

FIG. 6 is an explanatory diagram showing a signal processing process of the above-described active silencer. This signal processing process is
It consists of a process for silencing rotational noise and a process for silencing electromagnetic noise. In the process of silencing the rotational noise, a noise signal from the compressor 41 detected by a microphone or a vibration pickup is supplied to a bandpass filter (BPF) 61 and a rotational speed component (about 49 Hz in the case of operation at 50 Hz). Only the extracted spectrum is supplied to the control circuit 62, and the spectrum of this rotation speed component is used to obtain the spectrum of this integral multiple, that is, the simulated rotation sound source
9, 98, 147, 196 Hz, ... Are artificially produced, and this simulated rotary sound source is supplied to the DSP control circuit 63 to produce the silence anti-phase tone 1. On the other hand, in the process of suppressing the electromagnetic noise, the power supply frequency is detected by the power supply frequency detection circuit 65 from the power supply voltage supplied to the compressor 41 (50 Hz in the case of operation at 50 Hz),
The detected power supply frequency is supplied to the control circuit 66, and the spectrum of the power supply frequency is an even multiple of the spectrum, that is, simulated motor sound sources 100, 200, 400H.
z, ... are artificially created, and the simulated motor sound source is D
It is supplied to the SP control circuit 67 to produce the mute antiphase sound 2. The mute antiphase tones 1 and 2 produced as described above are output from the speaker 68 to mute.

[0009]

In the above-mentioned conventional active noise suppressor, when the compressor is operated at a variable speed by an inverter or the like, a follow-up delay for detecting the rotation speed occurs in a transient state during acceleration / deceleration. However, there is a problem that muffling becomes difficult.

The present invention has been made in view of the above,
It is an object of the present invention to provide an active silencer capable of silencing without detecting vibrations that generate noise and without delay in following a variable speed operation of a compressor or the like.

[0011]

In order to achieve the above object, an active noise canceling device of the present invention is an active noise canceling device which actively muffles noise generated by rotation, and information about rotation including a rotation command signal. And a rotation information acquisition means for acquiring the rotation information and an active signal that forms a signal having the same amplitude and opposite phase to the noise based on the rotation information acquired by the rotation information acquisition means, and actively silences the noise by the signal. The gist is to have a sound deadening means.

[0012]

In the active muffler of the present invention, information about the rotation including the rotation command signal is obtained, and a signal having the opposite phase and same amplitude to the noise is formed based on the information about the rotation to actively muffle the noise. To do.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a drive D for a compressor of a refrigerator to which an active silencer according to an embodiment of the present invention is applied.
It is a figure which shows the drive circuit of a C brushless motor, and the active muffling device of this invention is applied to muffle the noise generated from the compressor of a refrigerator as an example. In the figure, a DC brushless motor 1 is used as a motor for driving a compressor of a refrigerator, and the DC brushless motor 1 has a stator 1a and a magnet rotor 1b. The drive circuit of the motor 1 includes a single-phase 100 V, 50 or 60 Hz commercial frequency power source 3, a voltage doubler rectifier 5 including a diode and a capacitor, and a 120-degree conduction type three-phase bridge connection commutator 7 including a plurality of transistors and diodes. And a control microcomputer 9 which controls the commutator 7 and is supplied with a start / stop speed command for starting / stopping the commutator 7 from the outside.

Further, in FIG. 1, a counter electromotive force detection circuit 11 for detecting the position of the rotor of the DC brushless motor 1.
Is connected to the output of the commutator 7. In addition,
A sensor such as a Hall element is generally used to detect the position of the rotor of the DC brushless motor 1. However, since the temperature inside the compressor is high temperature and pressure, it is difficult to provide the sensor inside, and Since it is better to avoid taking out the signal line from the pressure vessel, when the DC brushless motor is used as the compressor, the back electromotive force detection circuit 11 is used as described above. In the 120-degree conduction type brushless motor, the utilization factor of the winding is 2/3, and one of the three windings is not energized at all times, so the counter electromotive force induced in this non-conducting winding is The position of the rotor can be detected by detecting.

FIG. 2 is a diagram showing the construction of an active noise suppressor according to one embodiment of the present invention, which silences noise generated from a compressor of a refrigerator driven by the DC brushless motor 1 shown in FIG. In the figure, the machine room 31 of the refrigerator
The DC brushless motor of the compressor 21, which is a noise source provided inside, is driven via the commutator 7. However, the DC brushless motor rotates the rotor in synchronization with the rotation speed of the rotating magnetic field, so the drive control means 23. The rotational speed of the rotor can be known at the stage of controlling the signal for driving the commutator 7.

In the active muffler shown in FIG. 2, the rotational speed of the rotor of the DC brushless motor of the compressor 21, which can be obtained as described above, is supplied to the control means 25, and based on the signal processed by the control means 25. The control sounder 27 including a speaker or the like is operated to generate an artificial sound having the opposite phase, the same wavelength, and the same amplitude at the opening 33 of the machine room 31, which is a desired point of noise suppression for the noise from the compressor 21. The sound is generated by the sound generator 27, and the signal sound and the noise are interfered with each other to attenuate or muffle the noise.

In FIG. 2, the microphone 26 is provided immediately before the opening 33, but the opening 3
The sound muted in 3 is detected, and the detected sound is fed back to the control means 25.

FIG. 3 is an explanatory diagram showing the flow of the silencing process of the active silencing apparatus shown in FIG. This active silencer is DC
Since the rotor of the brushless motor 1 rotates in synchronism with the rotating magnetic field, the fundamental frequency components of the rotating sound and the motor sound become equal, so the flow of the silencing processing becomes one as shown in FIG.

That is, as shown in FIG. 3, the control means 25 of FIG. 2 receives information on the rotational frequency component from the drive control means 23 (that is, in the case of 50 Hz operation, 50H
When z) is received (processing), an integral multiple of the fundamental spectrum (that is, 50, 100, 150, 20)
0 Hz, ...) is artificially created (processing), and the artificially created simulated sound source is supplied to the DSP control means 25 to create an antiphase sound (processing), against noise from the compressor 21. At the opening 33 of the machine room 31, which is the desired point of silence, an artificial sound of opposite phase, same wavelength, and same amplitude is generated from the control sound generator 27 (process), and the artificial sound and noise are caused to interfere with each other to generate noise. It is designed to be muted. The rotation frequency information received from the drive control means 23 includes a rotation command signal input from the outside.

As described above, since the drive control means 23 obtains the rotation speed information of the DC brushless motor 1, even when the rotation speed of the DC brushless motor 1 is changed in order to increase or decrease the capacity of the compressor, the rotation speed of the compressor is changed. The number of revolutions of the compressor can be detected with less delay and the follow-up delay can be reduced as compared with the case where the number is detected using a vibration pickup or the like.

Further, since the motor sound generated to generate the rotating magnetic field is also synchronized with the rotation speed of the rotating magnetic field, the motor sound can be silenced based on the same information.

[0023]

As described above, according to the present invention,
Information about rotation including a rotation command signal is obtained, and signals with the same amplitude and opposite phase are formed to noise based on this information about rotation, and noise is actively silenced. Even if there is no sensor for detecting the vibration of the compressor or the like, the vibration caused by the rotation of the compressor or the like can be silenced, and there is no delay in following the rotation speed detection.

[Brief description of drawings]

FIG. 1 is a diagram showing a drive circuit of a DC brushless motor that drives a compressor of a refrigerator to which an active noise canceling device according to an embodiment of the present invention is applied.

FIG. 2 is a diagram showing a configuration of an active silencer according to an embodiment of the present invention, which silences noise generated from a compressor of a refrigerator driven by the DC brushless motor shown in FIG.

FIG. 3 is an explanatory diagram showing a flow of a muffling process of the active muffling device shown in FIG. 2.

FIG. 4 is a configuration diagram of a conventional active silencer that detects vibration from a compressor with a microphone and actively silences the noise.

FIG. 5 is a configuration diagram of a conventional active silencer that detects vibrations from a compressor with a vibration pickup and actively silences the noise.

FIG. 6 is an explanatory diagram showing a silencing process of a conventional active silencing device.

[Explanation of symbols]

 1 DC Brushless Motor 7 Commutator 9 Control Microcomputer 21 Compressor 23 Drive Control Means 25 Control Means 26 Microphone 27 Control Sounder 31 Machine Room 33 Opening

Claims (1)

[Claims] 1. An active muffling device that actively muffles noise generated by rotation, comprising rotation information obtaining means for obtaining information about rotation including a rotation command signal, and rotation obtained by the rotation information obtaining means. An active muffling device, comprising: a signal having an opposite phase and same amplitude with respect to the noise based on information; and an active muffling means for actively muffling the noise by the signal.