JPH05312197A - Centrifugal fan - Google Patents

Abstract

PURPOSE:To provide a centrifugal fan in which interference sound due to a wane wheel and a tongue part is not generated. CONSTITUTION:This centrifugal fan is constituted of a rotating speed detector 1 to detect rotating speed of a vane wheel 101, a frequency computing means 2 to compute the frequency of interference sound from the detected rotating speed, a signal computing means 3 to prepare an additional sound signal to be opposite phase against the interference sound, and a speaker 4 to convert the additional sound signal to voice and transmit it.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a centrifugal fan used in air conditioners and ventilation fans.

[0002]

2. Description of the Related Art In recent years, air conditioners and ventilation fans used in living and non-living spaces have been required to reduce noise generated from the equipment.

Conventionally, this type of centrifugal fan has, as shown in FIG. 6, an impeller 101 and a tongue that surrounds the circumference of the impeller 101 and has the end closest to the impeller 101. And a spiral casing 103 having 102.

With the above structure, when the impeller 101 rotates, the suction air is boosted in pressure and is discharged to the outlet through the inside of the spiral casing 103. At this time, the impeller 101 and the tongue 1
It is well known that the distance of 02 is optimally about 5 to 10% of the outer diameter of the impeller, and the shorter the distance, the higher the total pressure obtained.

[0005]

In such a conventional centrifugal fan, when the distance between the impeller 101 and the tongue 102 is shortened to obtain a high total pressure, an interference sound is generated and the noise is increased. It was

It is known that the frequency fnz of this interference sound is expressed by the formula fnz = nz / 60 (Hz), where n is the rotation speed of the impeller.
(rpm) and z are the number of blades of the impeller.

The present invention solves the above problems, and an object of the present invention is to provide a centrifugal fan that does not generate interference noise.

[0008]

In order to achieve the above object, the centrifugal fan of the present invention has a first means for detecting the number of rotations of an impeller, and a rotation speed detector for detecting interference noise from the detected rotation speed. A frequency calculation means for calculating a frequency, a signal calculation means for generating an additional sound signal having an opposite phase to the interference sound, and a speaker for converting the additional sound signal into voice and transmitting the sound are provided. ..

The second means is provided with an acceleration sensor for detecting the vibration of the spiral casing in order to detect the frequency of the interference sound of the first means, and the interference sound is detected from the vibration signal detected by the acceleration sensor. It is configured to include a calculation unit that calculates the frequency.

The third means is provided with a microphone outside the spiral casing in order to detect the frequency of the interference sound of the first means, and calculates the frequency of the interference sound from the noise signal detected by the microphone. It is configured to include a calculation means.

The fourth means connects the vibrating part of the vibrator to the spiral casing to convert the additional sound signal of the first means into sound and transmits the sound, and the spiral casing is connected to the sound transmitting plate. It is configured to be used as.

[0012]

According to the present invention, by the structure of the above-mentioned first means, the frequency of the interference sound is calculated from the rotation speed detected by the detector for detecting the impeller rotation speed, and the frequency of the interference sound is opposite to the interference sound. The additional sound signal is generated by the calculation means and emitted from the speaker, so that the interference sound can be canceled.

Further, according to the structure of the second means, the frequency of the interference sound is detected by the vibration detector for detecting the vibration of the spiral casing, and the additional sound signal having a phase opposite to the interference sound is generated by the calculating means. Then, the interference sound can be canceled by being emitted from the speaker.

Further, according to the structure of the third means, the frequency of the interference sound is detected by the microphone outside the spiral casing, and the additional sound signal having a phase opposite to the interference sound is created by the calculating means, and is output from the speaker. By being emitted, the interference sound can be canceled.

With the configuration of the fourth means, the additional sound signal generated by the first means is radiated from the spiral casing connected to the vibration part of the vibration exciter to cancel the interference sound. You can

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIG. The same parts as those in the conventional example are designated by the same reference numerals, and detailed description thereof will be omitted.

As shown in the figure, when the impeller 101 rotates, an interference sound is generated by the impeller 101 and the tongue 102. The rotation frequency detector 1 for detecting the rotation speed of the impeller and the frequency calculation means 2 calculate the frequency of the interference sound. From the calculated frequency of the interference sound, an additional sound signal having a phase opposite to the interference sound is created by the signal calculation means 3 and emitted from the speaker 4 as the additional sound. The emitted additional sound cancels the interference sound and prevents it from being propagated to the space.

As described above, according to the centrifugal fan of the first embodiment of the present invention, the frequency of the interference sound is calculated from the rotation speed of the impeller 101, and the additional sound having a phase opposite to the interference sound is generated by the speaker 4.
The interference sound can be canceled by radiating from.

Next, a second embodiment of the present invention will be described with reference to FIG. The same parts as those in the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

As shown in the figure, the impeller 101 and the tongue 10
The interference sound due to 2 propagates to the spiral casing 103 as solid vibration. The vibration of the spiral casing 103 is detected by the acceleration sensor 5, and the frequency of the interference sound is calculated by the calculation means 6 from the detected signal. From the calculated frequency of the interference sound, an additional sound signal having a phase opposite to the interference sound is created by the signal calculation means 3 and emitted from the speaker 4 as the additional sound. The emitted additional sound cancels the interference sound and prevents it from being propagated to the space.

As described above, according to the centrifugal fan of the second embodiment of the present invention, the frequency of the interference sound is detected from the vibration of the spiral casing 103, and the additional sound having the opposite phase to the interference sound is emitted from the speaker 4. By doing so, the interference sound can be canceled.

Next, a third embodiment of the present invention will be described with reference to FIG. The same parts as those in the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

As shown in the figure, the noise signal of the interference sound is detected by the microphone 7 arranged outside the spiral casing 103, and the frequency of the interference sound is calculated by the calculating means 6 from the detected signal. An additional sound signal having an opposite phase to this interference sound is created by the signal calculation means 3 and is emitted from the speaker 4 as an additional sound. The emitted additional sound cancels the interference sound and prevents it from being propagated to the space.

As described above, according to the centrifugal fan of the third embodiment of the present invention, the frequency of the interference sound is detected by the microphone 7 arranged outside the spiral casing 103, and an additional sound having a phase opposite to the interference sound is detected. The interference sound can be canceled by radiating from the speaker 4.

Next, a fourth embodiment of the present invention will be described with reference to FIG. The same parts as those in the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

As shown in the figure, an additional sound signal having an opposite phase to the interference sound is created by the signal calculation means 3 and given to the vibrator 8. The vibrating portion 9 of the vibrator 8 excites the connected spiral casing 103 with the additional sound signal, and is emitted from the excited spiral casing 103 as an additional sound having a phase opposite to the interference sound. The emitted additional sound cancels the interference sound and prevents it from being propagated to the space.

As described above, according to the centrifugal fan of the fourth embodiment of the present invention, the interference sound can be canceled by radiating the additional sound from the spiral casing 103.

[0028]

As is apparent from the above embodiments, according to the present invention, the interference sound generated by the impeller and the tongue is canceled by the additional sound having the opposite phase, so that the centrifugal fan without the interference sound can be provided. ..

[Brief description of drawings]

FIG. 1 is a sectional view of a centrifugal fan according to a first embodiment of the present invention.

FIG. 2 is a sectional view of the second embodiment.

FIG. 3 is a sectional view of the third embodiment.

FIG. 4 is a sectional view of the fourth embodiment.

FIG. 5 is a comparison diagram of noise spectra of a conventional centrifugal fan and a centrifugal fan of the present invention.

FIG. 6 is a sectional view of a conventional centrifugal fan.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 rotational speed detector 2 frequency calculating means 3 signal calculating means 4 speaker 5 acceleration sensor 6 calculating means 7 microphone 8 vibrator 9 vibrating section

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Naka Hori 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Hiroyuki Hashimoto, 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd

Claims (4)

[Claims] 1. A rotation speed detector for detecting the rotation speed of an impeller,
The frequency calculation means for calculating the frequency of the interference sound from the detected rotation speed and the signal calculation means for generating an additional sound signal having a phase opposite to the interference sound are provided, and the additional sound signal is converted into voice. Centrifugal fan equipped with a speaker to transmit. 2. The centrifugal fan according to claim 1, further comprising an acceleration sensor for detecting vibration of the spiral casing, and arithmetic means for calculating a frequency of an interference sound from a vibration signal detected by the acceleration sensor. 3. The centrifugal fan according to claim 1, further comprising a microphone provided outside the spiral casing, and an arithmetic means for calculating the frequency of the interference sound from the noise signal detected by the microphone. 4. The centrifugal fan according to claim 1, wherein the vibrating portion of the vibrator is connected to the spiral casing, and the spiral casing is used as a sound transmitting plate.