Patent Grant
10989440
This application is a U.S. national stage application of PCT/JP2016/087762 filed on Dec. 19, 2016, the contents of which are incorporated herein by reference.
The present invention relates to air-conditioning apparatuses including air passages through which air flows, and in particular, relates to an air-conditioning apparatus including a housing structure that achieves reduction of housing-vibration-induced sound resulting from rotation of a fan.
For example, as described in Patent Literature 1, there has been a method for reducing noise in a centrifugal air-sending device. To reduce noise of, for example, vibration resulting from rotation of a fan, this method includes reducing a frequency that contributes to noise by providing a resonant space in proximity to an air inlet of a bell mouth.
Furthermore, as described in Patent Literature 2, there has been an air-conditioning-apparatus outdoor unit including a bell mouth having ribs (strengthening ribs 53) arranged at predetermined positions on a rear surface of the bell mouth to reduce vibration of the bell mouth caused by a fluid flowing through the bell mouth.
Patent Literature 1: Japanese Unexamined Patent Application Publication No. 2009-264121
Patent Literature 2: Japanese Unexamined Patent Application Publication No. 2010-127594
In the related art described in Patent Literature 1, the resonant space is provided at a rear of the bell mouth. Disadvantageously, a fluid flowing at the rear of the bell mouth may create turbulence in the resonant space, causing generation of new vibration-induced sound (noise).
In the related art described in Patent Literature 2, many ribs are arranged at predetermined intervals in a circumferential direction. For resonant vibration propagating from a housing, however, the ribs may not be arranged at suitable positions for reducing vibration resulting from resonance. Some ribs are of little or no use in reducing vibration resulting from, for example, resonance. Furthermore, the ribs may create new vibration by themselves, causing generation of new vibration-induced sound.
Noise includes not only sound of a fluid through a fan but also resonance sound of a structure having an air passage and housing-vibration-induced sound of a structure. The resonance sound of a structure having an air passage and the housing-vibration-induced sound of a structure are in form of noise that has a plurality of characteristic peak frequencies and is unpleasant to hear.
In particular, rotation of a device, for example, a fan, generates sound (typically referred to as NZ sound) having a frequency characteristic obtained by multiplying a rotation period (N) by the number of blades (Z). As such sound, sound resulting from a fluid passing through a fan is known. Surprisingly, however, it is relatively unknown that noise includes not only the above-described sounds but also sound resulting from vibration of a housing vibrated by a fluid passing through the housing.
Such vibration can include a vibration component resulting from fluid-induced vibration of a housing, a vibration component propagated to the housing, serving as a structure, from, for example, a motor to which a fan is connected and fixed, and a vibration component resulting from resonance with natural vibration of the housing structure. It has been found that resonance with natural vibration of the housing structure can cause resonance sound to be generated from unexpected part of the housing structure and such resonance sound becomes a problem.
The present invention has been made in view of the above-described problems, and aims to provide an air-conditioning apparatus in which a countermeasure against vibration-induced sound resulting from vibration of a housing is adopted and in which unpleasant sound having a peak frequency of the vibration-induced sound resulting from vibration of the housing is attenuated without obstruction to fluid flow.
An air-conditioning apparatus according to an embodiment of the present invention includes a housing having an air inlet and an air outlet, a fan disposed in the housing, and a bell mouth through which a fluid flowing from the air inlet to the air outlet passes in association with rotation of the fan. The bell mouth includes curved part having a curved sectional shape in a fluid flow direction and a vibration-damping element disposed on at least one of a front surface and a rear surface of the curved part. The vibration-damping element is disposed at a position corresponding to a node of vibration of the bell mouth.
As the vibration-damping element is disposed at the position corresponding to a node of a vibration mode of the bell mouth on at least one of the rear surface and the front surface of the curved part of the bell mouth, the air-conditioning apparatus according to an embodiment of the present invention can reduce or eliminate divided vibration of the bell mouth caused by rotation of the fan, thus effectively attenuating a peak frequency of NZ sound generated by vibration of the bell mouth.
Embodiment of the present invention will be described with reference to the drawings. Note that the relationship between the sizes of components illustrated in the following drawings including
The air-conditioning apparatus 100 has functions of an indoor unit installed in an indoor space (air-conditioned space) in, for example, a house, a building, or an apartment, and supplies conditioned air to the air-conditioned space by using a refrigeration cycle. Although the air-conditioning apparatus 100 of a ceiling embedded type will be described herein as an example, the type of the air-conditioning apparatus 100 is not limited to this example. The present invention is applicable to any type of air-conditioning apparatus, for example, a ceiling suspended type, a wall hung type, or a floor standing type.
The air-conditioning apparatus 100 includes a housing 1 accommodating an air passage 50 through which the air is circulated.
The air-conditioning apparatus 100 further includes a motor 7 suspended from substantially central part of an inner upper surface of the housing 1, a fan 6 attached to a shaft of the motor 7, and a heat exchanger 9 disposed around the fan 6. The air-conditioning apparatus 100 further includes a front panel 4 attached to lower part of the housing 1.
The housing 1 is box-shaped and has an open bottom, sides 2, and a top 3. The housing 1, serving as a body of the air-conditioning apparatus 100, accommodates the motor 7, the fan 6, and the heat exchanger 9. The housing 1 further accommodates the air passage 50 through which the air is circulated. Driving the fan 6 circulates the air through the air passage 50 (as represented by the dotted-line arrows A).
In addition, a foam material 10 is disposed at an interior of the sides 2 and the top 3 of the housing 1. A wall may be interposed between the foam material 10 and the air passage 50.
The motor 7 is suspended from the housing 1 by support rubber 8 in such a manner that the shaft of the motor extends downward, and rotates the fan 6. Specifically, the support rubber 8 is fastened to the inner surface of the top 3 of the housing 1, and the motor 7 is fastened to the support rubber 8.
The fan 6 is fastened to the shaft of the motor 7 in such a manner that an air inlet of the fan faces downward. The fan 6 suctions the air from the air-conditioned space, such as an indoor space where the air-conditioning apparatus 100 is installed, allows the air to pass through the heat exchanger 9, and blows the air into the air-conditioned space.
The front panel 4 has an air inlet 4a through which the air is suctioned into the housing 1 and an air outlet 4b through which the air is discharged out of the housing 1. The air inlet 4a is open and located at central part of the housing 1 in plan view. The air outlet 4b is open and located around the air inlet 4a. A bell mouth 5 is disposed at the air inlet 4a. The bell mouth 5 regulates the flow of the air suctioned from the air-conditioned space into the housing 1 to reduce or eliminate noise and thus reduce or eliminate a degradation in user comfort.
The heat exchanger 9 acts as a condenser in a heating operation, acts as an evaporator in a cooling operation, and exchanges heat between the air supplied from the fan 6 and a heat medium, such as refrigerant, supplied from a heat source unit (outdoor unit), which is not illustrated, to produce heating air or cooling air.
The air passage 50 is provided inside the housing 1 in such a manner that the air inlet 4a communicates with the air outlet 4b. In the air passage 50, the air suctioned from the air-conditioned space through the air inlet 4a flows through the fan 6, the inside of the heat exchanger 9, the outside of the heat exchanger 9, and the air outlet 4b in the stated order.
A grille having a plurality of openings through which the air to be suctioned into the housing 1 passes and an air filter for removing dust contained in the air are preferably arranged at the air inlet 4a of the front panel 4 in such a manner that the air filter is located above the grille.
A vertical air-directing vane for adjusting a blowing direction in which the air is blown is typically disposed at the air outlet 4b of the front panel 4.
Furthermore, the front panel 4 is disposed in such a manner that, for example, a lower surface of the front panel 4 is substantially flush with a ceiling to which the front panel 4 is installed.
<Housing-Vibration-Induced Sound Resulting from Rotation of Fan>
As sound that is generated in a device including a fan, sound resulting from a fluid passing through the fan is known. Surprisingly, it is relatively unknown that examples of the sound that is generated in a device including a fan further include sound resulting from vibration of a housing, or housing-vibration-induced sound. It has been found that housing-vibration-induced sound includes a vibration-induced sound component resulting from fluid-induced vibration of a housing, a vibration-induced sound component propagated to the housing, serving as a structure, from, for example, a motor to which a fan is connected and fixed, and resonance sound that results from resonance with natural vibration of the housing structure and that is generated from unexpected part of the housing structure.
Like the air passage 50 in the air-conditioning apparatus 100, a sound propagation path in a device including a fan may be defined by, for example, a heat-insulating foam material. The foam material may be vibrated by a fluid or may resonate with vibration associated with rotation of a motor or a fan, propagate the vibration through the structure, and thus generate “vibration”. The “vibration” generated by the foam material may be propagated to components constituting the device including the fan, thus forcibly vibrating the components or causing resonance-induced vibration of the components. This action results in noise unpleasant to hear.
This noise results from vibration of the components constituting the device. Specifically, rotation of the fan generates NZ sound. The NZ sound directly vibrates an air passage structure, resulting in vibration of a bell mouth disposed at an air inlet. The NZ sound is obtained by multiplying a rotation period (N) of the fan by the number (Z) of blades. Such a phenomenon can similarly occur in the air-conditioning apparatus 100.
A typical bell mouth (including the bell mouth 5), which serves as an air passage, has a curved vertical section not to obstruct air flow. Vibration associated with rotation of a fan can be propagated to the bell mouth having such a structure through a housing structure. The bell mouth has one end coupled to the housing and is thus inevitably included in a vibration propagation path. Propagation of the vibration associated with the rotation of the fan to the bell mouth causes a divided vibration mode in which a first “antinode (+)”, a “node”, and another “antinode (−)” appear in parts of the bell mouth included in the vibration propagation path. This vibration mode has a feature in which the amplitude of vibration of part close to the housing is larger than that of part remote from the housing.
The bell mouth has vibration states as illustrated in
These figures demonstrate that reducing or eliminating vibration of the bell mouth 5X is an effective countermeasure against the NZ sound and this countermeasure differs from a countermeasure against fluid-induced vibration from a fan.
As the bell mouth 5X serves as an air passage, bumps, such as ribs, on the bell-mouth front surface 5X-2 and the bell-mouth rear surface 5X-3 interfere with fluid flow, or generate new sound associated with a fluid. As even merely forming a rib having a simple shape causes the same problem, care must be taken in providing bumps.
<Measures to Reduce or Eliminate Vibration of Bell Mouth>
Examples of measures to reduce or eliminate vibration of a bell mouth, or countermeasures against the NZ sound, include the following three measures:
First measure including performing a vibration-damping process on the bell mouth, serving as an air flow passage;
Second measure including performing a vibration attenuation process on a vibration propagation path including a housing and the bell mouth; and
Third measure including adopting a countermeasure against vibration to make a bell mouth body.
The first measure is intended to increase the stiffness of the bell mouth. This measure includes structurally processing the bell mouth to reduce or eliminate vibration of the bell mouth. Specifically, the measure includes allowing the bell mouth to have a rib having a specific shape in such a manner that the rib does not obstruct the air passage.
The second measure is intended to attenuate vibration of the bell mouth. This measure includes fixing a vibration-to-heat transforming unit (vibration-damping element) to the bell mouth. Specifically, the measure includes bonding a vibration-damping element to the bell mouth or applying vibration-damping paint to the bell mouth.
The third measure is intended to damp vibration of the bell mouth by using a material for the bell mouth. This measure includes forming a material containing a vibration-damping material into the bell mouth. Specifically, the measure includes molding the bell mouth from vibration-damping resin.
Adopting such a measure enables control in the propagation path to achieve overall reduction or elimination of vibration, and ensures attenuation of the NZ sound having a characteristic peak frequency.
(Example of First Measure)
As illustrated in
Specifically, the rib 5-5 has a mound-like sectional shape having a tip located at the node of the vibration mode (refer to
Such a shape reduces or eliminates secondary vibration of the rib 5-5 and allows the fluid to smoothly flow without being obstructed by the rib 5-5.
It is only required that at least one rib 5-5 is disposed on the curved part 5-1. Any number of ribs 5-5 may be arranged. The rib 5-5 and the bell mouth 5 may be molded in one piece. The rib 5-5 may be molded as a separate piece and be attached to the bell mouth 5.
The rib 5-5 may be molded out of the same material as that for the bell mouth 5. Alternatively, the rib 5-5 may be molded out of a vibration-damping material capable of transforming vibration into heat. Molding the rib 5-5 out of such a vibration-damping material provides greater vibration attenuating effects.
(Example of Second Measure)
As illustrated in
Furthermore, a recess 5-7 having a predetermined depth is formed not to obstruct the air passage, and the vibration damper 5-6 is attached to the recess 5-7. Specifically, the recess 5-7 is formed in part that is subjected to the vibration mode of the bell mouth 5, or in an area extending from part in proximity to the fixed end of the bell mouth 5 (or the lower end of the bell mouth 5 in
Consequently, the bell-mouth rear surface 5-3 has no protrusion, such as a rib, so that the fluid flowing on the bell mouth 5 is not obstructed. Vibration in the divided vibration mode in the curved part 5-1 of the bell mouth 5 can be effectively attenuated.
It is only required that at least one vibration damper 5-6 is bonded to the curved part 5-1. Any number of vibration dampers 5-6 may be arranged.
Although
(Second Example of Second Measure)
As illustrated in
Consequently, the bell-mouth front surface 5-2 has no protrusion, such as a rib, so that the fluid flowing on the bell mouth 5 is not obstructed. Vibration in the divided vibration mode in the curved part 5-1 of the bell mouth 5 can be effectively attenuated.
It is only required that at least one vibration damper 5-6 is bonded to the curved part 5-1. Any number of vibration dampers 5-6 may be arranged.
Although
Although the vibration damper 5-6 bonded or applied to either one of the bell-mouth front surface 5-2 and the bell-mouth rear surface 5-3 of the bell mouth 5 is illustrated as an example in
(Example of Third Measure)
An example of the third measure is to form a material containing a vibration-damping material into the bell mouth 5 and thus damp vibration of the bell mouth 5 by using the material. The material for the bell mouth 5 is a mixture containing carbon, which can exhibit vibration-damping performance, or any of polyester-based resins, which tend to thermally expand, and further containing a proper amount of resin to be originally used to make the bell mouth 5. The bell mouth 5 made of such a material allows vibration of the bell mouth 5 to be transformed into heat, thus reducing or eliminating the vibration.
Furthermore, mixing a silicone-based material into the above-described material enables the surfaces of the bell mouth 5 to remain smooth.
The vibration-damping material is preferably mixed into the resin to be originally used to make the bell mouth 5. The vibration-damping material is preferably mixed by up to approximately 50% of the total amount of the mixture in consideration of the fluidity of the mixture containing the vibration-damping material in a “mold” for molding the bell mouth 5.
As the thickness of the bell mouth 5 itself achieves reduction or elimination of vibration, the bell mouth 5 is advantageously allowed to have a smaller thickness than those in the related art. For example, related-art bell mouths require a thickness of approximately 3 mm. In contrast, the bell mouth 5 having a thickness up to approximately 1.5 mm can offer advantages similar to those in the related art.
The whole of the bell mouth 5 may be molded out of a resin mixture containing a vibration-damping material (polymer). Part of the bell mouth 5 may be molded out of this mixture. When part of the bell mouth 5 is molded out of the resin mixture containing the vibration-damping material (polymer), insert molding and traditional resin can be used to make the bell mouth 5.
<Advantages Offered by Air-Conditioning Apparatus 100>
The air-conditioning apparatus 100 has an effect of reducing peak frequencies of vibration-induced sound. This effect will be described below with reference to
The air-conditioning apparatus 100 includes the fan 6 as a component and the air passage 50 is defined by the foam material 10. In such a configuration, the foam material 10 may be vibrated by the fluid and thus generate “vibration”. The foam material 10 may resonate with vibration associated with rotation of the motor 7 and the fan 6, propagate the vibration through the structure, and thus generate “vibration”. The “vibration” generated by the foam material 10 may be propagated to the components constituting the air-conditioning apparatus 100, for example, the bell mouth 5. In other words, rotation of the fan 6 generates NZ sound, resulting in vibration of the bell mouth 5.
As represented by the dotted line in
In contrast, as the air-conditioning apparatus 100 includes the bell mouth 5 subjected to any of the first to third measures, as represented by the full line in
As described above, as the air-conditioning apparatus 100 includes the bell mouth 5 subjected to any of the first to third measures, the air-conditioning apparatus 100 ensures a reduction in vibration-induced sound resulting from NZ sound associated with rotation of the fan 6. In addition, the bell mouth 5 subjected to any of the first to third measures does not obstruct air flow through the air-conditioning apparatus 100.
Although the first to third measures have been described as individual countermeasures against vibration of the bell mouth 5 in Embodiment, the bell mouth 5 may be made by using a combination of these measures. Furthermore, the third measure is intended to be used together with at least one of the first and second measures.
1 housing 2 side 3 top 4 front panel 4a air inlet 4b air outlet 5 bell mouth 5-1 curved part 5-2 bell-mouth front surface 5-3 bell-mouth rear surface 5-5 rib 5-6 vibration damper 5-7 recess 5X bell mouth 5X-1 curved part 5X-2 bell-mouth front surface 5X-3 bell-mouth rear surface 6 fan 7 motor 8 support rubber 9 heat exchanger 10 foam material 50 air passage 100 air-conditioning apparatus
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2016/087762 | 12/19/2016 | WO | 00 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2018/116340 | 6/28/2018 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 7883312 | Eguchi | Feb 2011 | B2 |
| 9145900 | Kim | Sep 2015 | B2 |
| 20020015640 | Nishiyama et al. | Feb 2002 | A1 |
| 20050223732 | Kim et al. | Oct 2005 | A1 |
| 20100218403 | Imamura et al. | Sep 2010 | A1 |
| 20110002775 | Ma et al. | Jan 2011 | A1 |
| Number | Date | Country |
|---|---|---|
| 1336482 | Feb 2002 | CN |
| 1678842 | Oct 2005 | CN |
| 1680753 | Oct 2005 | CN |
| 2009-264121 | Nov 2009 | JP |
| 2010-127594 | Jun 2010 | JP |
| 2012-207643 | Oct 2012 | JP |
| 2013-228168 | Nov 2013 | JP |
| 2013228168 | Nov 2013 | JP |
| Entry |
|---|
| English Machine translation of JP2013228168, Oct. 19, 2020. |
| Office Action dated Jun. 28, 2020 issued in corresponding CN patent application No. 201680090678.0 (and English translation). |
| International Search Report of the International Searching Authority dated Feb. 28, 2017 for the corresponding international application No. PCT/JP2016/087762 (and English translation). |
| Extended European Search Report dated Nov. 8, 2019 issued in corresponding European patent application No. 16924821.8. |
| Office Action dated Feb. 10, 2021 issued in corresponding CN patent application No. 201680090678.0 (and English machine translation). |
| Number | Date | Country | |
|---|---|---|---|
| 20200072495 A1 | Mar 2020 | US |
