JP2006207508A - Fan noise reducing device and fan noise reducing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fan noise reducing device and a fan noise reducing method simultaneously reducing noise on an upstream side and on a downstream side of a fan while enabling to design the device configuration relatively simple and compact. <P>SOLUTION: An intake air duct 3 and a delivery duct 4 of an axial fan 2 are divided by a partition wall 30. Each duct is arranged in both sides of the partition wall in parallel and at least a part of the partition wall is formed out of flexible film 40 and a flat speaker 50. Fan noise in each duct is canceled by sound wave interference of the intake air duct and the delivery duct via the flexible film and fan noise in each duct is simultaneously attenuated by vibration or generated sound of each surface of the flat speaker. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an apparatus and a method for reducing fan noise, and more specifically, fan noise that propagates to an upstream flow path (intake side flow path) and a downstream flow path (discharge side flow path) of the fan. The present invention relates to a fan noise reduction device and a fan noise reduction method for reducing fan noise by utilizing the symmetry and the antiphase property.

  As a noise prevention device or silencer, the control sound is a passive type device such as a soundproof cover, a soundproof hood, a silencer, etc., and a sound wave having the same amplitude and opposite phase as the target noise (a sound wave with a phase difference of 180 °). Or it is divided roughly into the active type (active type) apparatus which radiates | emits as a cancellation sound.

  As passive noise prevention devices or silencers (hereinafter simply referred to as “silencers”), for example, silencers such as a sound absorption duct or a sound absorption chamber arranged in a propagation path of sound waves emitted by a sound source are known ( JP-A-2004-251197, JP-A-9-212175, etc.). This type of silencer has a sound-absorbing effect of a sound-absorbing material disposed in a duct or chamber, a shock wave attenuation interference that occurs when the volume or direction of an air flow changes, or a reflected sound that occurs in an air flow path. The noise is attenuated by utilizing interference with the target noise.

  On the other hand, the active silencer is configured to analyze a noise waveform and generate a sound wave having an antiphase in the air flow path, and to attenuate the noise by utilizing a sound wave interference principle (Japanese Patent Laid-Open No. 9-1990). No. 54491, JP-A-9-127756, JP-A-10-20866, JP-A-10-268872, JP-A-2002-244667, etc.).

There is also known a silencer of a type in which both such a passive silencer and an active silencer are combined (Japanese Patent Laid-Open Nos. 3-174198 and 7-319482). Further, as a special silencer, for example, a configuration in which a pair of fans are operated synchronously and the wind noise of one fan is canceled by the wind noise of the other fan is known (Japanese Patent Laid-Open No. 2001-92013). Issue gazette).
JP 2004-251197 A JP 9-212175 A JP 2001-92013 A Japanese Patent Laid-Open No. 9-54491 Japanese Patent Laid-Open No. 9-127956 Japanese Patent Laid-Open No. 10-20866 Japanese Patent Laid-Open No. 10-268872 JP 2002-244667 A

  The characteristics of an electronic component built in an electronic device or an OA device change according to temperature conditions. For this reason, an electronic component that serves as a heating element, for example, a power source or a light source, a CPU (Central Processing Unit), a personal computer equipped with a semiconductor such as a memory, a liquid crystal display device, an electronic device such as a printer, or an OA device, An air cooling fan is provided to cool electronic components in the machine. In particular, in an electronic device or OA device that generates a relatively large amount of heat, for example, a liquid crystal projector that generates a relatively large amount of internal heat, a plurality of air cooling fans (a plurality of air supply fans and / or exhaust fans). May need to be installed. The installation of such an air cooling fan is effective for preventing overheating of the apparatus, but the air cooling fan generates a relatively large fan noise, which is not desirable for ensuring a room sound environment such as quietness.

  In order to eliminate such inconvenience, it can be assumed that a conventional passive silencer is disposed in an electronic device or the like. However, this type of silencer requires a relatively large cabin space. For this reason, it is difficult to secure a space in which the silencer that exhibits an effective silencing effect can be installed in the in-machine region of the electronic device. Therefore, it is extremely difficult to design an electronic device or the like so as to obtain a sufficient silencing effect by a conventional passive silencing device.

  On the other hand, the active silencer, for example, arranges a muffler speaker that generates a control sound in a fan noise propagation path so as to cancel a sound wave using an air-cooled fan as a sound source. A sensor microphone to be detected is arranged in the system, and a control sound (secondary sound) having the same amplitude and opposite phase as the fan noise is radiated from the muffler speaker based on the noise signal of the sensor microphone. Such a muffler not only requires relatively complicated control, but also requires a sound source for control sound on both the upstream side (intake side) and downstream side (discharge side) of the fan. Will be complicated.

  In addition, in the conventional silencer in which the passive silencer and the active silencer are combined, it is necessary to design the device configuration to be complicated or large in order to achieve different types of silencer, or the air flow path. There are problems such as restrictions on the structure of

  The present invention has been made in view of such a problem, and an object of the present invention is to make it possible to design the apparatus configuration relatively simply and in a small size, and to make noise on the upstream side and downstream side of the fan. It is an object of the present invention to provide a fan noise reduction device and a fan noise reduction method that can simultaneously reduce the noise.

As a result of earnest research to achieve the above object, the present inventor has achieved the present invention by paying attention to the bidirectionality of noise in an axial fan used as a small fan for cooling electronic devices and the like. is there.
That is, the present invention provides a fan noise reduction device having the following configuration in a fan noise reduction device for reducing fan noise of an axial fan.

(1) The intake flow channel and the discharge flow channel of the axial fan are partitioned by partition walls, and the flow paths are arranged in parallel on both sides of the partition wall, and at least a part of the partition walls is formed by a flexible film that can be vibrated by fan noise. The fan noise reduction apparatus is characterized in that the fan noise in each flow path interferes with each other by the fan noise in the intake flow path and the discharge flow path and cancels out.

(2) The suction flow channel and the discharge flow channel of the axial flow fan are partitioned by partition walls, the flow channels are arranged in parallel on both sides of the partition wall, and a flat speaker whose surfaces face the suction flow channel and the discharge flow channel, respectively. A fan noise reduction apparatus, wherein at least a part of the partition wall is formed, and fan noise in the intake flow path and discharge flow path is simultaneously attenuated by vibration and / or transmission sound of the flat speaker.

(3) The intake flow channel and the discharge flow channel of the axial fan are partitioned by partition walls, the flow channels are arranged in parallel on both sides of the partition wall, and a flexible membrane that can be vibrated by fan noise, and each surface is an intake flow channel Forming at least a part of the partition wall by planar speakers facing the path and the discharge flow path, and canceling the fan noise of the flow paths by interfering with each other by the fan noise of the intake flow path and the discharge flow path, A fan noise reduction device characterized in that fan noise in each flow path is attenuated simultaneously by vibration and / or transmission sound of a flat speaker.

  The present invention also provides a fan noise reduction method for reducing the fan noise of an axial fan having the following configuration.

(1) A partition wall between the intake passage and the discharge passage of the axial fan is at least partially formed of a flexible film, and the intake passage and the discharge using the axial fan as a sound source. It is characterized by causing fan noise of a flow path to act on each surface of the flexible membrane, and reducing fan noise of each flow channel by interference of anti-phase fan noise acting on each surface of the flexible membrane. Fan noise reduction method.

(2) A partition between the flow paths defining the intake flow path and the discharge flow path of the axial fan is at least partially formed by a flat speaker, and the intake flow path and the discharge flow path using the axial flow fan as a sound source The fan noise reduction method is characterized in that the fan noise is reduced by vibration and / or transmission sound of the flat speaker.

(3) A partition between the intake flow path and the discharge flow path of the axial flow fan is formed at least partially by a flexible membrane and a flat speaker, and the intake flow using the axial flow fan as a sound source. The fan noise of the passage and the discharge passage is caused to act on each surface of the flexible membrane, and the fan noise in each passage is reduced by the interference of the anti-phase fan noise acting on each surface of the flexible membrane. A fan noise reduction method for reducing fan noise in the intake passage and the discharge passage by vibration and / or transmission sound of the flat speaker.

  According to the above configuration of the present invention, the intake flow channel and the discharge flow channel are partitioned by the partition wall, and at least a part of the partition wall is formed by the flexible film and / or the flat speaker. The noise of the axial fan mainly consists of wind noise from moving blades. Fan noise diffusing in both directions of the intake side and the discharge side is propagated to the intake flow path and the discharge flow path as sound waves of opposite phases. Fan noise diffused in the intake flow path and the discharge flow path is incident on the flexible film and / or the flat speaker as a sound wave having an opposite phase. Fan noise in each channel interferes with each other through the flexible membrane and cancels each other out. The fan noise in each flow path is simultaneously attenuated by vibration excited on each surface of the flat speaker, or is simultaneously attenuated by control sound radiated from each surface of the flat speaker.

From another viewpoint, the present invention provides a fan noise reduction device for reducing fan noise of an axial fan.
The suction flow path and discharge flow path of the axial fan are partitioned by the partition wall, the partition wall is positioned on the rotation plane of the moving blade perpendicular to the rotation axis of the axial fan, and at least a part of the partition wall is flexible Fans in each flow path are formed by interference of anti-phase fan noise that is formed by a membrane and / or a flat speaker and acts on each surface of the flexible membrane, and / or vibration and / or emitted sound of the flat speaker. Provided is a fan noise reduction device characterized in that noise is reduced.

  According to the present invention, there is provided a fan noise reduction device and a fan noise reduction method capable of designing the device configuration to be relatively simple and small, and further reducing noise on the upstream side and downstream side of the fan at the same time. Is done.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic plan view showing an air-cooling fan unit according to the first embodiment of the present invention, and FIGS. 2, 3 and 4 show the II, II-II and III-lines shown in FIG. It is sectional drawing of the air cooling fan unit in an III line.

  FIG. 1 shows an air cooling fan unit 1 that can be installed in an electronic device such as a liquid crystal projector or a printer. The air cooling fan unit 1 includes an axial fan 2, an intake passage 3, and a discharge passage 4. The intake flow path (upstream flow path) 3 communicates with the intake port 5 of the axial fan 2, and the discharge flow path (downstream flow path) 4 communicates with the discharge port 6 of the axial flow fan 2. A fan motor 7 is disposed in the fan casing 9 of the axial fan 2, and the fan motor 7 is connected to a power source (not shown) via a power supply line (not shown). A predetermined number (e.g., 8) of moving blades 8 are arranged at equal intervals around the rotation drive unit of the fan motor 7. The rotor blade 8 rotates around the rotation axis 10 of the fan motor 7 and generates an airflow in the direction of the rotation axis as indicated by an arrow in FIG.

  The intake flow path 3 and the discharge flow path 4 are partitioned by the left and right side walls 20, the end wall 21, the top wall 22, the bottom wall 23, and the partition walls 30 and 31, and extend in parallel to a direction orthogonal to the rotation axis 10. The side wall 20, the end wall 21, the top wall 22, and the bottom wall 23 form an integral rectangular parallelepiped housing whose one surface is open, and the partition wall 30 is a housing that divides the region in the housing equally on the left and right. Extends on the centerline. If desired, the surfaces of the side wall 20, the end wall 21, the top wall 22, the bottom wall 23, and the partition walls 30 and 31 facing the flow paths 3 and 4 are covered with a sound absorbing material 25.

  The partition wall 30 is positioned on the rotation plane of the moving blade 8 orthogonal to the rotation axis 10. The intake flow path 3 and the discharge flow path 4 are arranged symmetrically on both sides of the partition wall 30 as parallel flow paths having an equal flow path cross section. The partition wall 31 connected to the end of the partition wall 30 extends from the end of the partition wall 30 to the left and right objects in a direction orthogonal to the partition wall 30 (parallel to the end wall 21). The overall length (planar wall length) of the partition wall 31 is set to a dimension corresponding to the depth dimension of the axial fan 2, and an area that can accommodate the axial fan 2 is formed between the wall body 31 and the end wall 21. The axial fan 2 is disposed between the wall 31 and the end wall 21 with the rotation axis 10 oriented in a direction orthogonal to the partition wall 30, the intake flow path 3, and the discharge flow path 4. An intake region 3 a and a discharge region 4 a facing the intake port 5 and the discharge port 6 are formed at end portions of the intake channel 3 and the discharge channel 4.

  Openings 32 and 33 having predetermined dimensions are arranged in the partition wall 30 with a predetermined interval. A flexible membrane 40 and a flat speaker 50 are stretched between the openings 32 and 33. The flexible film 40 is made of a synthetic resin, elastomer, or metal thin film that can be vibrated by sound waves propagated in the flow paths 3 and 4, and the flat speaker 50 is made of a film member to which a piezoelectric (piezo) element is attached. As a modification, the flexible film 40 may be formed of cloth, paper, or a fibrous material.

  The piezoelectric element of the flat speaker 50 is connected to the power supply control device 60 via the electrical wiring 61, and the power supply control device 60 applies a voltage to the piezoelectric element to excite the vibration of the flat speaker 50. The acoustic sensor 70 (microphone) is connected to the power supply control device 60 via the control signal line 62, and the error microphone 71 is connected to the power supply control device 60 via the control signal line 63.

  The flexible membrane 40 is disposed on the partition wall 30 at a position relatively close to the axial flow fan 2, and each surface of the flexible membrane 40 faces the intake flow path 3 and the discharge flow path 4. The flat speaker 50 is disposed at a position relatively separated from the axial fan 2 as compared with the flexible membrane 40. The acoustic sensor 70 is disposed on the side wall 20 in the intake region 3a. The flat speaker 50 and the acoustic sensor 70 are separated by a distance that can ensure the operation time of the power supply control device 60. Therefore, the power supply control device 60 can analyze the detection result (noise waveform or the like) of the acoustic sensor 70 and optimize the voltage to be applied to the piezoelectric element of the flat speaker 50. The error microphone 71 is disposed on the side wall 20 at the upstream end of the intake flow path 3 (upstream side of the flat speaker 50), and the detection result (noise waveform, etc.) of the error microphone 71 is also input to the power supply control device 60. . The power supply control device 60 can perform feedback control of the voltage to be applied to the piezoelectric element of the flat speaker 50 based on the detection result of the error microphone 71. The error microphone 71 may be disposed in the discharge flow path 4.

  Next, the operation of the air cooling fan unit 1 will be described.

  The air-cooling fan unit 1 is disposed in a casing or the like of the electronic device so as to cool a space inside the electronic device. An intake side duct 13 and a discharge side duct 14 (shown by broken lines in FIG. 1) are connected to the open ends 11 and 12 of the air cooling fan unit 1 located on the side opposite to the axial flow fan 2, respectively.

  When the in-machine temperature of the electronic device rises, the air cooling fan unit 1 drives the axial fan 2 and rotates the moving blade 8. The axial fan 2 sucks indoor air or air in the electronic device through the intake duct 13. Indoor air or air in the electronic device is attracted into the intake flow path 3 under the intake pressure of the axial fan 2 as indicated by an arrow A in FIG. The intake flow A is sucked from the intake port 5 to the axial fan 2 in the intake region 3a, flows out from the discharge port 6 of the axial fan 2 to the discharge region 4a, and is discharged as a discharge flow indicated by an arrow B in FIG. Sent to path 4. The discharge flow B of the discharge flow path 4 flows out into the indoor space or the in-machine region via the discharge side duct 14.

  During operation of the axial fan 2, noise is generated using the axial fan 2 as a sound source. The noise of the axial fan 2 is mainly wind noise of the moving blades 8, and the noise on the intake side and the exhaust side diffuses symmetrically in each flow path as sound waves having opposite phases.

  FIG. 5 is a diagram showing the frequency characteristics of fan noise propagating to the upstream side of the axial fan 2 (the intake passage 3 side), and FIG. 6 shows the downstream side of the axial fan 2 (the discharge passage 4). It is a diagram which shows the frequency characteristic of the fan noise which propagates to the (side).

  As shown in FIG. 18, the inventor manufactured an experimental model (air cooling fan unit 100) of an air cooling fan unit that does not include the flexible membrane 40 and the flat speaker 50 as a comparative example, and the axial flow in the air cooling fan unit 100. The fan noise of fan 2 was measured. FIG. 5 and FIG. 6 show the measured values of fan noise in the air cooling fan unit 100.

  As shown in FIGS. 5 and 6, fan noise (FIG. 5) that propagates to the upstream flow path (intake flow path 3) and fan noise (FIG. 6) that propagates to the downstream flow path (discharge flow path 4). Have substantially the same frequency characteristics and amplitude, and the dominant part of the fan noise appears in the frequency range of about 850 Hz and about 1700 Hz.

  The diagram shown in FIG. 7 is a combination of the measurement results shown in FIGS. 5 and 6, and the phase difference between the upstream (suction side) and downstream (discharge side) fan noises is shown in FIG. 7. ing.

  As shown in FIG. 7, the fan noises propagating through the intake flow path 3 and the discharge flow path 4 respectively show opposite phases (180 °) in the frequency range of the dominant portion (about 850 Hz and about 1700 Hz). Therefore, when the fan noise propagated to each part of the intake flow path 3 and the discharge flow path 4 that are equidistant from the axial fan 2 is interfered, the noises of the respective flow paths interfere with each other and cancel each other. Works.

  FIG. 19 shows an air cooling fan unit 1 ′ according to the second embodiment of the present invention. The air-cooling fan unit 1 ′ is a modification of the air-cooling fan unit 1 (first embodiment) shown in FIGS. 1 to 4. As shown in FIG. 19, the flat speaker 50 is not provided and only the flexible film 40 is used. Prepare. The inventor measured the fan noise of the axial fan 2 in the air cooling fan unit 1 '.

  8 and 9 show the fan noise measurement values of the air cooling fan unit 1 '. FIG. 8 is a diagram showing the frequency characteristics of fan noise propagating to the upstream side of the axial fan 2 (the intake passage 3 side), and FIG. 9 shows the downstream side of the axial fan 2 (the discharge passage 4). It is a diagram which shows the frequency characteristic of the fan noise which propagates to the (side). In FIG. 8 and FIG. 9, the fan noise measurement values of the above-described air cooling fan unit 100 (FIG. 18) are indicated by broken lines as a comparative example.

  As shown in FIGS. 8 and 9, in the air-cooled fan unit 1 ′ in which a part of the partition wall 30 is formed of the flexible film 40, the noise value of the dominant portion (about 850 Hz and about 1700 Hz) is significantly reduced. That is, since the flexible membrane 40 faces the intake flow path 3 and the discharge flow path 4 at a position equidistant from the sound source (axial fan 2), the flexible film 40 faces the intake flow path 3 and the discharge flow path 4, respectively. The propagated fan noise acts on the flexible film 40 as a sound wave having an opposite phase, and interferes so as to cancel each other through the flexible film 40.

  FIG. 10 is a diagram showing the fan noise level of the air cooling fan unit 1 ′ (second embodiment) and the fan noise level of the air cooling fan unit 100 (comparative example) in comparison.

  As described above, the flexible membrane 40 exhibits an interference action that cancels out noises in the intake flow path 3 and the discharge flow path 4, so that in the air-cooling fan unit 1 ′ having the flexible film 40, The noise levels of the flow path 3 and the discharge flow path 4 are considerably reduced as shown in FIG.

  An air cooling fan unit 1 "according to a third embodiment of the present invention is shown in Fig. 20. The air cooling fan unit 1" is a modification of the air cooling fan unit 1 (first embodiment) shown in Figs. As an example, as shown in FIG. 20, only the flat speaker 50 is provided without the flexible membrane 40. The inventor measured the fan noise of the axial fan 2 in the air-cooled fan unit 1 ″.

  11 and 12 show fan noise measurement values of the air-cooled fan unit 1 ″. FIG. 11 shows the frequency of fan noise propagating to the upstream side of the axial fan 2 (the intake flow path 3 side). Fig. 12 is a diagram showing the characteristics, and Fig. 12 is a diagram showing the frequency characteristics of the fan noise propagating to the downstream side of the axial fan 2 (the discharge flow path 4 side). The fan noise measured value of the above-mentioned air cooling fan unit 100 (FIG. 18) is shown by a broken line as a comparative example.

  As shown in FIGS. 11 and 12, the fan noise in the intake flow path 3 and the discharge flow path 4 is also reduced in the air-cooled fan unit 1 ″ in which the flat speaker 50 is stretched over the opening 33. The flat speaker 50 It faces both the intake flow path 3 and the discharge flow path 4 at a position that is equidistant from the sound source (axial fan 2) The power supply control device 60 is based on the detection value of the acoustic sensor 70. The noise waveform is analyzed, and the flat speaker 50 is operated so as to generate vibration and control sound in the opposite phase to the noise in the intake passage 3. The flat speaker 50 excites vibration in the opposite phase on each surface. At the same time, the control sound having the opposite phase is radiated from each surface of the flat speaker 50. Due to the symmetry of the intake flow path 3 and the discharge flow path 4, the reverse phase characteristics of the intake side noise and the discharge side noise, Control sound is the discharge flow path Thus, the flat speaker 50 generates vibrations and control sounds in phases opposite to those of the fan noise in the intake passage 3 and the discharge passage 4 on each surface. Attenuates the fan noise at the same time.

  FIG. 13 is a diagram showing the fan noise level of the air cooling fan unit 1 ″ (third embodiment) and the fan noise level of the air cooling fan unit 100 (comparative example) in comparison.

  As shown in FIG. 13, noise in the intake passage 3 and the discharge passage 4 is reduced by the operation of the flat speaker 5.

  14 and 15 are diagrams showing fan noise measurement values of the air-cooled fan unit 1 (FIGS. 1 to 4) of the first embodiment. FIG. 14 shows the frequency characteristics of the fan noise propagated to the intake flow path 3, and FIG. 15 shows the frequency characteristics of the fan noise propagated to the discharge flow path 4. FIG. 16 is a diagram showing the fan noise level of the air cooling fan unit 1 (first embodiment) and the fan noise level of the air cooling fan unit 100 (comparative example) in comparison.

  The air-cooling fan unit 1 exhibits a noise attenuating action due to interference between intake-side noise and discharge-side noise made through the flexible membrane 40, and intake-side noise and discharge-side noise, vibration of the flat speaker 50, and control sound. Demonstrates noise attenuating effect due to sound wave interference. Accordingly, since the air cooling fan unit 1 further reduces the fan noise in the intake flow path 3 and the discharge flow path 4 as compared with the second and third embodiments described above, the fan noise is as shown in FIGS. Greatly reduced.

  FIG. 17 shows the fan noise level of the air cooling fan unit 1 (first embodiment), the fan noise level of the air cooling fan unit 1 ′ (second embodiment), and the fan noise level of the air cooling fan unit 100 (comparative example). FIG.

  In contrast to the air cooling fan unit 100 that does not include the flexible membrane 40 and the flat speaker 50, the air cooling fan unit 1 'provided with the flexible membrane 40 exhibits a remarkable noise attenuation effect as shown in FIG. And the air-cooling fan unit 1 provided with both the flexible film | membrane 40 and the flat speaker 50 exhibits the remarkable noise attenuation effect. The difference between the noise attenuation effect of the air cooling fan unit 1 ′ (second embodiment) and the noise attenuation effect of the air cooling fan unit 1 (first embodiment) is grasped as the difference between the operation and non-operation of the flat speaker 50. Also good.

  FIG. 21 is a schematic plan view showing an air cooling fan unit according to the fourth embodiment of the present invention.

  In the present embodiment, the axial fan 2 is disposed in the center of the air cooling fan unit 1 </ b> A, and the intake flow path 3 and the discharge flow path 4 include extension portions 3 b and 4 b that extend on the opposite side of the axial flow fan 2. A rotation plane P of the moving blade 8 orthogonal to the rotation axis 10 is shown by an imaginary line in FIG. The partition wall 30 is located on the rotation plane P. A partition wall 30 ′ that partitions the extended portions 3 b and 4 b is disposed on the rotation plane P on the side opposite to the partition wall 30. The partition wall 30 ′ is at least partially formed by the flexible membrane 40 and / or the flat speaker 50.

  The air-cooled fan unit 1 is configured to reduce the intake-side noise and the discharge-side noise generated through the flexible film 40 due to the symmetry of the intake flow path 3 and the discharge flow path 4 and the antiphase characteristics of the intake-side noise and the discharge-side noise. It exhibits a noise attenuating effect due to interference, or a noise attenuating effect due to vibration of the flat speaker 50 and / or control sound.

  The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above-described embodiments, and various modifications or changes can be made within the scope of the present invention described in the claims. Is possible.

  For example, FIGS. 22 to 24 are schematic plan views showing modifications of the air cooling fan unit. In each figure, the same reference numerals are assigned to components that are substantially the same or equivalent to the components of the above-described embodiment.

  The air cooling fan unit 1B shown in FIG. 22 is attached to the housing 90 of the electronic device. The air cooling fan unit 1B receives the intake air flow A flowing at a predetermined angle (right angle in this example) into the intake flow channel 3, and discharges the discharge flow B of the discharge flow channel 4 in a predetermined direction (right angle direction in this example). Then, it flows into the region in the housing 90.

  The air cooling fan unit 1C shown in FIG. 23 has a relatively compact configuration in which the intake flow path 3 and the discharge flow path 4 are shortened. The intake air flow A and the discharge air flow B are slightly detoured in the air cooling fan unit 1C, but are introduced into the region in the housing 90 through a flow path having a generally linear shape as a whole.

  The air cooling fan unit 1D shown in FIG. 24 has a configuration in which the intake passage 3 and the discharge passage 4 are linearly aligned. The intake air flow A and the discharge air flow B are not deflected in the air cooling fan unit 1D, and are pumped in the same direction by the axial fan 2. The intake passage 3 and the discharge passage 4 have enlarged regions 3c and 4c that are enlarged on both sides of the axial flow fan 2, respectively. A partition wall 30 ″ separating the intake flow channel 3 and the discharge flow channel 4 extends on both sides of the axial fan 2 on the rotation plane P of the axial fan 2. At least a part of the partition wall 30 ″ includes the flexible membrane 40 and / Or formed by the flat speaker 50.

  Such air cooling fan units 1B, 1C, and 1D are flexible because of the symmetry of the intake flow path 3 and the discharge flow path 4 and the reverse phase of the intake side noise and the discharge side noise, as in the above-described embodiments. The noise attenuating action is exhibited by the interference between the intake side noise and the discharge side noise made through the membrane 40, or the noise attenuating action is exhibited by the vibration and / or control sound of the flat speaker 50.

  In addition, the noise reduction device of the present invention can be appropriately changed in design according to its application. For example, depending on the application, the flexible film may be changed to a simple hole or opening, and the same fan. It is also possible to obtain a noise reduction effect.

  The fan noise reduction device and the fan noise reduction method of the present invention are preferably applied to a cooling fan that cools an electronic device such as a large computer, a liquid crystal projector, a personal computer, a liquid crystal display device, a printer, a copying machine, or an OA device, Used as a means to effectively prevent fan noise. The fan noise reduction device and the fan noise reduction method of the present invention are also used for cooling fans or ventilation fans for buildings, electronic component manufacturing facilities, plants, substations and power receiving facilities, general home appliances, AV devices, and communication devices that generate internal heat. The present invention is applied to a cooling fan or a ventilation fan, and can be used as a device or method for preventing fan noise.

It is a schematic plan view which shows the air cooling fan unit which concerns on 1st Embodiment of this invention. It is sectional drawing of the air cooling fan unit in the II line | wire shown in FIG. It is sectional drawing of the air cooling fan unit in the II-II line | wire shown in FIG. It is sectional drawing of the air cooling fan unit in the III-III line | wire shown in FIG. It is a diagram which shows the frequency characteristic of the fan noise which propagates to the upstream (side of an intake flow path) of an axial fan. It is a diagram which shows the frequency characteristic of the fan noise which propagates to the downstream (exhaust flow path side) of an axial fan. It is a diagram which shows the phase difference of each fan noise of an upstream (suction side) and a downstream (discharge side). It is a diagram which shows the fan noise measured value of the air-cooled fan unit of 2nd Embodiment, and the frequency characteristic of the fan noise which propagates to the upstream (intake flow path side) of an axial fan is shown. It is a diagram which shows the fan noise measured value of the air-cooling fan unit of 2nd Embodiment, and the frequency characteristic of the fan noise which propagates to the downstream (discharge flow path side) downstream of an axial fan is shown. It is a diagram which compares and shows the fan noise level of the air cooling fan unit of 2nd Embodiment, and the fan noise level of the air cooling fan unit which concerns on a comparative example. It is a diagram which shows the fan noise measured value of the air-cooled fan unit of 3rd Embodiment, and the frequency characteristic of the fan noise which propagates to the upstream (intake flow path side) of an axial fan is shown. It is a diagram which shows the fan noise measured value of the air-cooled fan unit of 3rd Embodiment, and the frequency characteristic of the fan noise which propagates to the downstream (discharge channel side) of an axial flow fan is shown. It is a diagram which compares and shows the fan noise level of the air cooling fan unit of 3rd Embodiment, and the fan noise level of the air cooling fan unit which concerns on a comparative example. It is a diagram which shows the fan noise measured value of the air-cooling fan unit of 1st Embodiment, and the frequency characteristic of the fan noise which propagates to the upstream (intake flow path side) of an axial fan is shown. It is a diagram which shows the fan noise measured value of the air-cooling fan unit of 1st Embodiment, and the frequency characteristic of the fan noise which propagates to the downstream (discharge flow path side) downstream of an axial fan is shown. It is a diagram which compares and shows the fan noise level of the air cooling fan unit of 1st Embodiment, and the fan noise level of the air cooling fan unit which concerns on a comparative example. FIG. 6 is a diagram showing a comparison between the fan noise level of the air cooling fan unit of the first embodiment, the fan noise level of the air cooling fan unit of the second embodiment, and the fan noise level of the air cooling fan unit according to the comparative example. It is a schematic plan view which shows the air cooling fan unit which concerns on a comparative example. It is a schematic plan view which shows the air cooling fan unit which concerns on 2nd Embodiment of this invention. It is a schematic plan view which shows the air cooling fan unit which concerns on 3rd Embodiment of this invention. It is a schematic plan view which shows the air-cooling fan unit which concerns on 4th Embodiment of this invention. It is a schematic plan view which shows the modification of an air cooling fan unit. It is a schematic plan view which shows the other modification of an air cooling fan unit. It is a schematic plan view which shows the other modification of an air cooling fan unit.

Explanation of symbols

1, 1 ', 1 ", 1A, 1B, 1C, 1D Air-cooled fan unit (first to fourth embodiments and modifications)
2 Axial fan 3 Intake flow path
4 Discharge flow path 30, 30 ', 30 "Partition 40 Flexible membrane 50 Flat speaker 60 Power supply control device

Claims (7)

In the fan noise reduction device that reduces the fan noise of axial fans,
The intake flow channel and the discharge flow channel of the axial fan are partitioned by partition walls, the flow channels are arranged in parallel on both sides of the partition wall, and at least a part of the partition walls is formed by a flexible film that can be vibrated by fan noise. A fan noise reduction apparatus characterized in that the fan noise of each flow path interferes with each other by the fan noise of the intake flow path and the discharge flow path and cancels out. In the fan noise reduction device that reduces the fan noise of axial fans,
The intake flow channel and the discharge flow channel of the axial flow fan are partitioned by a partition wall, the flow channels are arranged in parallel on both sides of the partition wall, and the partition wall A fan noise reduction apparatus, wherein at least a part of the fan noise is formed, and the fan noise in the intake flow path and the discharge flow path is simultaneously attenuated by vibration and / or transmission sound of the flat speaker. In the fan noise reduction device that reduces the fan noise of axial fans,
The intake flow channel and discharge flow channel of the axial flow fan are partitioned by partition walls, the flow channels are arranged in parallel on both sides of the partition wall, and a flexible membrane that can be vibrated by fan noise, and each surface is an intake flow channel and discharge channel At least a part of the partition wall is formed by a flat speaker facing each of the flow paths, and the fan noise of each flow path is caused to interfere with each other by the fan noise of the intake flow path and the discharge flow path. A fan noise reduction device characterized in that fan noise in each flow path is attenuated simultaneously by vibration and / or transmission sound. In the fan noise reduction method for reducing the fan noise of an axial fan,
A partition between the intake flow path and the discharge flow path of the axial flow fan is at least partially formed by a flexible film, and the intake flow path and the discharge flow path of the axial flow fan are used as a sound source. Fan noise is caused to act on each surface of the flexible membrane, and fan noise in each flow path is reduced by interference of anti-phase fan noise acting on each surface of the flexible membrane. Reduction method. In the fan noise reduction method for reducing the fan noise of an axial fan,
Fan noise in the intake flow path and discharge flow path using the axial flow fan as a sound source, where a partition between the flow paths defining the intake flow path and the discharge flow path of the axial flow fan is at least partially formed by a flat speaker. Is reduced by vibration and / or transmission sound of the flat speaker. In the fan noise reduction method for reducing the fan noise of an axial fan,
A partition between the intake passage and the discharge passage of the axial fan is at least partially formed by a flexible membrane and a flat speaker, and the intake passage and the discharge using the axial fan as a sound source. The fan noise of the flow path is caused to act on each surface of the flexible membrane, and the fan noise of each flow channel is reduced by the interference of the anti-phase fan noise acting on each surface of the flexible membrane, and the intake air A fan noise reduction method characterized by reducing fan noise in a flow path and a discharge flow path by vibration and / or transmission sound of the flat speaker. In the fan noise reduction device that reduces the fan noise of axial fans,
The suction flow path and discharge flow path of the axial fan are partitioned by the partition wall, the partition wall is positioned on the rotation plane of the moving blade perpendicular to the rotation axis of the axial fan, and at least a part of the partition wall is flexible Fans in each flow path are formed by interference of anti-phase fan noise that is formed by a membrane and / or a flat speaker and acts on each surface of the flexible membrane, and / or vibration and / or emitted sound of the flat speaker. A fan noise reduction device characterized by reducing noise.

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