JPH05312196A - Fan device - Google Patents

Abstract

PURPOSE:To provide a fan device in which noise of wide band range of an axial flow fan can be remarkably reduced. CONSTITUTION:This fan deice is constituted of a fan 7 consisting of a trunk part 7b and blade parts 7a and rotationally driven so as to feed air, a detecting sensor 8 which is provided on a decided position on the negative pressure side blade face of the blade part, detects variation of air flow along the negative pressure side blade face, and outputs a first signal, a computation processing device internally mounted in the trunk part 7b and outputting a second signal computation processed from the signal of the detecting sensor 8, and an air flow control means 9 which controls air flow so as to cancel the variation of air flow based on the second signal of the computation processing device provided on the decided position on the lower stream side of the detecting sensor of air flow on the negative pressure side blade face.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fan device for reducing noise generated by an axial fan that is rotationally driven.

[0002]

Blowers are widely used in air conditioners, ventilation fans and the like, and it is very important socially to reduce the noise generated from the impeller as much as possible. In order to reduce the noise of the blower, it is conceivable to devise the shape and material of the blades of the fan itself, which is the source of noise, but to reduce the noise while optimizing the blade shape while satisfying the blowing capacity. Is limited. There are also means such as sound absorption and sound insulation, but these also reduce the ventilation effect,
There are problems such as requiring a large space. Therefore,
As a noise control device for a blower, a method has been proposed in which active control technology is used to reduce the noise of the blower without requiring a large space and without lowering the blowing capacity of the blower.

FIG. 16 shows, for example, Japanese Patent Application Laid-Open No. 2-285799.
FIG. 7 is a cross-sectional view showing a configuration of a conventional fan device shown in Japanese Patent Publication. In the figure, 1 is a casing of a device, 2 is an internal cooling fan attached to the casing 1, 3 is a small speaker such as a ceramic piezoelectric speaker of a control sound source arranged facing the fan 2, and 4 is a casing. 1
An optical sensor, which is provided in the vicinity of the rotating part of the fan 2 inside the fan, and includes a diode and a light receiving element, 5 is a microphone that is arranged at a position where noise reduction is expected at the outer edge of the casing 1, and serves as a sound receiving means, and 6 is a microphone. 5 and the detection signals of the optical sensor 4 are input and processed.

Next, the operation will be described. The detection signals of the microphone 5 and the optical sensor 4 are input to and processed by the arithmetic processing unit 6, and the drive control signal is output to the speaker 3, and the speaker 3 produces a control sound. The arithmetic processing unit 6 is a kind of digital filter whose transfer characteristic can be fixed or variable. The rotation signal input from the optical sensor 4 is taken into the arithmetic processing unit 6 via the A / D converter, and the control signal is output via the D / A converter.
The arithmetic processing unit is made as a fixed type or an adaptive type, and is configured as shown in FIG. 17 or 18. The transfer characteristics of the arithmetic processing unit 6 are the optical sensor 4 and the speaker 3.
Is designed to compensate for the transfer characteristic of and to produce a sound having a phase opposite to that of the noise at the position of the microphone 5.
With the above configuration, noise is reduced at the position of the microphone 5.

[0005]

Since the conventional fan device is constructed as described above, it is difficult to mute the entire space because it creates and muffles noise in a phase opposite to the noise in the vicinity of the microphone. In addition, since the signal synchronized with the rotation speed is used as the control signal, it has the disadvantage that it has an effect only on noise of a frequency that is an integral multiple of the rotation speed of the blower, and has no silencing effect on broadband noise. It was

The present invention has been made in order to solve the above problems, and a fan device capable of muffling the entire space and significantly reducing not only noise of an integral multiple of the number of revolutions but also wideband noise. The purpose is to get.

[0007]

SUMMARY OF THE INVENTION A fan device according to the present invention includes a fan composed of a body portion and a blade portion, which is rotationally driven and blows air, and a fan surface provided on a suction side blade surface at a predetermined position of the suction side blade surface. A detection sensor that detects a variation in the air flow along the side and outputs a first signal, an arithmetic processing unit that is installed in the body and outputs a second signal obtained by arithmetically processing the first signal of the detection sensor, and a negative pressure side wing. And an air flow control means for controlling the air flow based on the second signal and canceling the fluctuation of the air flow, which is provided at a predetermined position on the downstream side of the air flow detection sensor.

[0008] Further, the first signal, which is provided at a predetermined position on the suction-side blade surface of the blade portion and which is driven by rotation of the body portion and the blade portion to blow air, captures the fluctuation of the air flow along the suction-side blade surface. A detection sensor that outputs a signal, an arithmetic processing unit that is installed in the body and outputs a second signal obtained by arithmetically processing the first signal of the detection sensor, and a fan that is generated by the fan based on the second signal. It is composed of a control sounding device that generates a sound in a phase opposite to the noise and actively cancels it.

[0009]

It is known that the noise source of the axial fan, which is a particular problem, is caused by the turbulence of the flow generated and developed in the boundary layer on the suction side of the fan. The generation process of turbulence and noise in the boundary layer on the suction surface is considered as follows. As shown in FIG. 14, the air flow is separated at the leading edge of the fan blade, and the turbulence caused by the re-adhesion, the minute turbulence present in the atmosphere, the turbulence caused by acoustic pressure fluctuation, etc.
After the amplification process on the suction side of the fan, vortices are emitted at the trailing edge of the fan blade. As a result, the circulation of the fan blade itself changes slightly, and its lift changes. Noise is generated by this slight change in lift. Further, when the flow of air flowing into the fan is locally non-uniform, the circulation of the fan blade itself changes in synchronization with the rotation speed. As a result, noise is generated from the fan that is an integral multiple of the rotation speed. In the fan device according to the present invention, the air pressure turbulence generated on the suction side blade surface or a minute pressure fluctuation due to the air flow disturbance is detected by the detection sensor arranged on the blade surface. The first signal of the turbulence in the same airflow converted into an electric signal is input to the arithmetic processing unit, and the second signal output from the arithmetic processing unit is used to arrange the airflow control means, for example, the vibration device, on the blade surface. To operate.
As shown in FIG. 15, the arithmetic processing unit compensates the transfer function of the detection sensor and the transfer function of the vibration device, and the transfer function representing the transport / amplification of the air flow turbulence between the detection sensor and the vibration device, and the control vibration device described above. Operates to cancel airflow turbulence. By rectifying the turbulence in the airflow, fluctuations in wind speed near the trailing edge of the blade are reduced, changes in lift of the blade are reduced, and noise generated from the blade is reduced.

Further, the air flow turbulence generated on the blade surface of the blade or a minute pressure fluctuation due to the air flow disturbance is detected by a detection sensor arranged on the blade surface. The first signal of the turbulence in the same airflow converted into an electric signal is input to the arithmetic processing device, and the second signal output from the arithmetic processing device operates the sounding device arranged on the wing surface or on the body. .. The arithmetic processing unit compensates the transfer function of the detection sensor and the transfer function of the sounding device, and the transfer function in which noise generated at the trailing edge of the blade due to the turbulence detected by the turbulence sensor propagates to the sounding device. It operates to cancel the noise generated by the turbulence of the air flow.

[0011]

【Example】

Example 1. A first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an external view of a fan device according to Embodiment 1 of the present invention, and FIG. 2 is a block diagram showing the configuration. In the figure, 7 is a fan including a blade portion 7a and a body portion 7b, and 8 is a detection sensor which is provided on the negative pressure side blade surface of the fan 7 and which detects an air flow variation and outputs an electric signal, here a speed sensor portion of an anemometer. Reference numerals 9 and 9 denote a vibration device provided on a blade surface on the negative pressure side downstream of the speed sensor 8 and constituted by a piezo element serving as an air flow control means. Here, a vibration actuator, 10 is an anemometer amplifier section, and 11 is a fan 7. An arithmetic processing unit 12 is provided in the body portion, 12 is a vibration device amplifier unit, and a vibration actuator 9 formed of a piezo element is provided for each blade. Although these devices are mounted on the rotating part, the power source thereof is input through, for example, a collector ring.

A minute turbulence on the blade surface is detected by the speed sensor 8 mounted on the suction surface of the fan blade. The signal (first signal) representing the turbulence obtained by the speed sensor 8 is input to the arithmetic processing device 5. In the processor 11,
Adjust the phase and output gain for each frequency of the signal,
The output signal (second signal) is output to the vibration device amplifier unit 12. At this time, the adjustment of the phase and the output gain in the arithmetic processing unit 11 is performed by the transfer function of the speed sensor 8 and the transfer function of the vibration device amplifier section 6 and the vibration actuator 9, and the disturbance in the boundary layer from the speed sensor 8 to the vibration actuator 9. Is compensated for the transfer function that represents the movement / amplification of A, and the vibration is set to be displaced by a certain phase with respect to the disturbance in the boundary layer at the position of the vibration actuator 9 on the suction surface. When a vibration amplitude having a certain phase shift is applied to the boundary layer by the vibration actuator 9 with respect to the disturbance transported to the position of the vibration actuator 9, the magnitude of the disturbance is reduced to almost zero. As a result, the vorticity change of the blade due to the turbulence emitted from the trailing edge of the blade is reduced, and the noise emitted from the fan is reduced.

The position of the speed sensor 8 and the position of the vibration actuator 9 and the distance between the speed sensor 8 and the vibration actuator 9 at which the above-mentioned noise reduction effect is most obtained are defined as follows. The distance from the rear edge of the speed sensor 8 is S, the distance from the rear edge of the vibration actuator 9 is V, the distance between the speed sensor 2 and the vibration actuator 9 is L (= S−V),
The blade tip speed of the fan is U, the time constant of the speed sensor 8 is τ _S ,
The time constant of the vibration actuator 9 is τ _V , the arithmetic processing unit 1
The computation end time of 1 is τ _C. The position where the minute disturbance that is a noise source develops changes depending on the fan shape, and it is necessary to determine the development position of the disturbance by numerical calculation or experiment. If this position is defined as the position of the speed sensor 8,
The distance to the vibration actuator 9 must be L> U × (τ _S + τ _V + τ _C ). For example, in this embodiment, τ _S = 10
μs, τ _V = 100 μs, τ _C = 200 μs, the rotation speed N _D of the fan 1 = 1000 rpm, the number of blades Z = 3, the fan diameter D = 300 mm, and the fan chord length l = 330 mm, then U = 15. It will be 7 m / s. L ≧ 5 (mm). Naturally, this value depends on the rotation speed and fan diameter of the fan 7, the calculation speed of the arithmetic processing unit 11, the response speed of the speed sensor 8 and the vibration actuator 9, and is not limited to this depending on the conditions. On the contrary, the turbulence on the fan blade surface has a reduced cross-correlation as the speed sensor 8 and the vibration actuator 9 move away from each other, making it difficult to control. FIG. 3 is a graph showing the cross-correlation between the speed fluctuation of the sensor unit and the noise generated from the fan, with respect to the distance S between the sensor unit and the blade trailing edge. From this figure,
The distance S from the blade trailing edge of the sensor unit needs to be about S ≦ 50 mm (= S _D ). In the present embodiment, considering the above, S = 20 mm and the distance V from the trailing edge of the blade to the actuator V = 5 mm, so L = 15 mm. However, this value varies depending on the shape and size of the fan, and is not limited to this depending on the conditions.
The cross-correlation is considered to be proportional to the boundary layer thickness δ.
That is, S ₀ / δ = constant δ is δ˜l (lU / ν) ^−1/2 . Where ν is the kinematic viscosity coefficient, and l and D /
Z has a proportional relationship, and U and ND have a proportional relationship. Where N
Is the number of revolutions (rpm). From the above, S ₀ and (ZN)
^-1/2 is proportional. In other words, from the similarity rule from the shape of the fan, it can be roughly considered that S ≦ 50 mm × (1000 × 3) ^1/2 / (NZ) ^1/2 in inverse proportion to the square root of the fan rotation speed. By installing a speed sensor inside, effective noise reduction is possible for fans with different fan diameters and rotational speeds. FIG. 4 shows the frequency analysis results of the noise generated by the conventional fan and the noise generated by the fan device according to the first embodiment. According to this embodiment, 2k
It can be seen that it is effective for periodic noise below H _Z and broadband noise.

Example 2. In the first embodiment, the vibration actuator 9 is used to suppress the turbulence generated on the blade surface, but heat generation using, for example, a nichrome wire that utilizes the change in the air viscosity due to the temperature that suppresses the turbulence due to the change in pressure is used. The vibration actuator 9 is a device or a cooling device, and a device having a function of blowing and sucking air into the boundary layer.
Similar effects can be obtained by using instead of.

Example 3. A third embodiment of the present invention will be described with reference to FIGS. In the figure, 7 is a fan, 2 is a speed sensor part of an anemometer, 13 is a sounding device constituted by a piezo element, 10 is an anemometer amplifier part, 11 is an arithmetic processing device, and 14 is an amplifier part of the sounding device. The sounding device 14 is attached downstream of the speed sensor 8. The speed sensor 8, the sounding device amplifier unit 14, the arithmetic processing unit 11, and the sounding device 13 using a piezo element are provided for each fan blade. A minute turbulence on the blade surface is detected by the speed sensor 8 mounted on the suction surface of the fan blade. Speed sensor 8
The signal representing the turbulence obtained in step 1 is input to the signal arithmetic processing unit 11. In the arithmetic processing unit 11, the phase and the output gain are adjusted for each frequency of the signal and output to the sounding device amplifier section 14. At this time, the adjustment of the phase and the output gain in the arithmetic processing unit 11 is caused by the transfer function of the speed sensor 8 and the transfer function of the sounding device amplifier unit 14 and the sounding device 13, and the disturbance detected from the speed sensor unit 8 by the speed sensor. The noise generated by is compensated for the transfer function propagating to the sounding device 13, and the sound emitted from the sounding device 13 is set to have an opposite phase to the noise at the sounding device position. When a sound of the opposite phase is added to the generated noise from the sounding device 13, the superposed sound level is reduced to nearly zero. As a result, the noise emitted from the blades is reduced. Although the piezo element is used for the sounding device 13, the same effect can be obtained by using a sounding device such as a voice coil.

Example 4. Further, as a fourth embodiment, it is possible to obtain the same effect by attaching the sound producing device 15 to the fan body portion 7b as shown in FIG. Further, as shown in FIG. 8, the same effect can be obtained by mounting the sounding device, for example, the speaker 16 inside the casing 17 surrounding the fan. In this case, the number of loudspeakers 16 mounted in the casing is made larger than the number of blades of the fan, and the output from the sensor on the blade of the fan closest to a certain control sounding device is used to further increase the number of speakers. The effect can be obtained.

Embodiment 5. Although the speed sensor 8 is used as the sensor for catching the wind fluctuation in the above-described first to third embodiments, the same effect can be obtained by using the pressure sensor in the meaning of catching the pressure fluctuation due to the wind speed fluctuation in the fourth embodiment.

Example 6. The transfer function in the processor is
In order to be effective in eliminating noise, it must change in accordance with changes in fan speed and static pressure before and after the fan. In addition, it is generally difficult to obtain the transfer function configured inside the arithmetic processing device from the transfer function of the speed sensor, the transfer function of the vibration actuator, the transfer function in the movement / amplification of the disturbance from the sensor position to the vibration actuator, and the like. is there. Therefore, as a sixth embodiment of the present invention, as shown in FIG. 9, an error sensor 18 including a microphone or the like is attached to the fan 7, and an arithmetic processing unit is provided with an adaptive filter so as to minimize the level of the error sensor 18. Thus, the transfer function inside the arithmetic processing unit can be easily determined. Further, as shown in FIG. 10, even if the error sensor 18 is attached to a place other than the fan 7, the same effect can be obtained. FIG. 11 shows the configuration of the error sensor and the processing device at this time. FIG. 11 shows the error sensor 1
A microphone is used as 8, and the output of this error sensor is input to the arithmetic processing unit through the microphone amplifier 19. The arithmetic processing unit is an adaptive control type, and an internal filter is set so as to minimize the output of the error sensor. Further, in the above embodiment, for example, one velocity sensor and one vibration actuator are used for one blade, but it is possible to obtain a further effect by using a plurality of velocity sensors and vibration actuators. ..

Example 7. 12A, 12B, 12C show a seventh embodiment as an application form of the first embodiment. In the figure, 7 is a fan, 8 is a velocity sensor part of an anemometer, and 19 is a vibration actuator constituted by both electrodes 19b and 19c of a piezo element 19a. Here, the vibration actuator 1
9 is arranged at the trailing edge of the blade, and a speed sensor is attached upstream of the suction surface of the blade to detect the speed fluctuation of the suction blade surface. The detected velocity fluctuation signal is input to the arithmetic processing unit, and the excessive discharge state at the trailing edge of the blade and the vibration amount of the vibration actuator at the trailing edge of the blade such that the vorticity of the entire blade is always constant , Calculates the vibration phase and outputs it to the vibration device. As a result, lift fluctuations around the blade are reduced, and noise generation is suppressed. It should be noted that FIG. 12-C shows an operating state in which a current is input to the vibration actuator 19. The error sensor 17 described in the sixth embodiment may be provided in the seventh embodiment to configure as shown in FIG.

[0020]

As described above, according to the present invention, the fan composed of the body portion and the blade portion and driven to rotate and blows air, and the fan portion along the suction side blade surface provided at the predetermined position of the suction side blade surface. A detection sensor that detects a change in the air flow and outputs a first signal, an arithmetic processing unit that is installed in the body section and that outputs a second signal that arithmetically processes the first signal of the detection sensor, and a negative pressure side wing surface Since the air flow control means is provided at a predetermined position on the downstream side of the electric flow detection sensor and controls the air flow based on the second signal to cancel the fluctuation of the air flow, the wind speed near the trailing edge of the fan blades. It is possible to obtain a fan device that can reduce the fluctuation, reduce the lift fluctuation of the blade, reduce the noise generated from the blade, and muffle the entire space.

[Brief description of drawings]

FIG. 1 is a perspective view showing the outer appearance of a fan device according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing the configuration of the apparatus of the first embodiment.

FIG. 3 is a cross-correlation coefficient table for positions of turbulence of airflow.

FIG. 4 is a correspondence table showing effects of noise reduction by the present invention.

FIG. 5 is a perspective view showing the external appearance of a fan device according to Embodiment 3 of the present invention.

FIG. 6 is a block diagram showing a configuration of an apparatus according to a third embodiment.

FIG. 7 is a perspective view showing the external appearance of a fan device according to Embodiment 4 of the present invention.

FIG. 8 is a cross-sectional view showing an applied form of the fourth embodiment.

FIG. 9 is a perspective view showing the external appearance of a fan device according to Embodiment 6 of the present invention.

FIG. 10 is a cross-sectional view showing an applied form of Example 6.

FIG. 11 is a block diagram showing a configuration of a sixth embodiment.

FIG. 12 shows a fan device according to a seventh embodiment of the present invention, in which A is a perspective view of the appearance and B is a line BB in A.
2 is a cross-sectional view taken along line C, and FIG.

FIG. 13 is a perspective view showing an external appearance of a fan device in which an error sensor is additionally provided in the seventh embodiment.

FIG. 14 is a cross-sectional view showing an air flow on a blade surface of a fan according to the present invention.

FIG. 15 is a cross-sectional view showing an air flow on a blade surface of a conventional fan.

FIG. 16 is a cross-sectional view showing a configuration of a conventional fan device.

FIG. 17 is a block diagram showing a configuration of a conventional fan device.

FIG. 18 is a block diagram showing another configuration of a conventional fan device.

[Explanation of symbols]

 7 Fan 7a Wing 7b Body 8 Speed sensor (detection sensor) 9 Vibration device (air flow control means) 10 Anemometer amplifier 11 Arithmetic processing device 12 Vibration device amplifier 13 Sounding device 14 Sounding device amplifier 17 Air sensor 19 Microphone amplifier

Claims (4)

[Claims] 1. A fan composed of a body portion and a blade portion, which is rotationally driven to blow air, and a fan which is provided at a predetermined position on a suction side blade surface of the blade portion and detects a fluctuation of an air flow along the suction side blade surface. From the detection sensor that outputs the No. 1 signal, the arithmetic processing unit that is installed in the body section and that arithmetically processes the first signal and outputs the second signal, and the detection sensor that detects the air flow on the suction side blade surface. A fan device comprising an air flow control means which is provided at a predetermined position on the downstream side and controls the air flow based on the second signal to cancel fluctuations in the air flow. 2. A fan composed of a body portion and a blade portion, which is driven to rotate and blows air, and a fan which is provided at a predetermined position on the suction side blade surface of the blade portion and catches a fluctuation of an air flow along the suction side blade surface. From the detection sensor that outputs the No. 1 signal, the arithmetic processing unit that is installed in the body section and that arithmetically processes the first signal and outputs the second signal, and the detection sensor that detects the air flow on the suction side blade surface. A fan device provided at a predetermined position on the downstream side, comprising air flow control means for vibrating so as to act on the air flow based on the second signal and canceling fluctuations in the air flow. 3. A fan composed of a body portion and a blade portion, which is rotationally driven to blow air, and a fan which is provided at a predetermined position on a suction side blade surface of the blade portion and catches a fluctuation of an air flow along the suction side blade surface. From the detection sensor that outputs the No. 1 signal, the arithmetic processing unit that is installed in the body section and that arithmetically processes the first signal and outputs the second signal, and the detection sensor that detects the air flow on the suction side blade surface. A fan device, which is provided at a predetermined position on the downstream side, and is provided with air flow control means for canceling fluctuations in the air flow by raising or lowering the temperature so as to act on the air flow based on the second signal. .. 4. A fan composed of a body portion and a blade portion, which is rotationally driven to blow air, and a fan which is provided at a predetermined position on the suction side blade surface of the blade portion and catches a fluctuation of an air flow along the suction side blade surface. Based on the second signal which is attached to the fan, a detection sensor which outputs the first signal, an arithmetic processing device which is installed in the body portion and arithmetically processes the first signal and outputs the second signal. A fan device comprising a sounding device that cancels the noise by generating a sound having a phase opposite to that of the noise generated by the fan.