JP2007101145A - Duct fan - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a duct fan capable of being installed, in particular, in a narrow space above the ceiling of a high-rise condominium and the like, with respect to the duct fan installed in the space under the roof of a building and the like and used for air supply ventilation. <P>SOLUTION: The duct fan which can be thinned and miniaturized while securing necessary air volume, is provided by mounting a single suction type air blower 9 in a flow channel of a machine body 3, mounting a motor in the flow channel at a fan suction port 11 side, of the single suction-type air blower 9, defining a supplied air chamber 21 by a fan discharge opening partitioning wall 17 between a plurality of first machine body supply openings 2 and a fan discharge opening 16 of the single suction-type air blower 9, positioning a center 25 of the fan discharge opening in a state of being offset to a side opposite to a tongue portion 24 of a scroll 27 of the single suction-type air blower 9 with respect to a supplied air chamber center 26, and disposing an air cleaning filter 10 for cleaning the air between the machine body suction port 1 and the fan suction port 11. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a duct fan that is arranged in a space such as the back of a ceiling of a building and is used for air supply and ventilation through a duct from the outside to the room, and is particularly installed in a narrow space behind the ceiling of a high-rise apartment or the like.

  Conventionally, what is shown by FIGS. 10-12 is known as an example of the duct fan of a general living space (for example, refer patent document 1).

  The configuration will be described below with reference to FIGS.

As shown in FIG. 10 to FIG. 12, there is a box-shaped airframe 106 that is installed by connecting a suction-side duct 103 to the airframe inlet 102 and a blower-side duct 105 to the airframe outlet 104 in the deep ceiling 101. . The machine body 106 has a structure in which a machine body suction port 102 is provided on the suction side, a machine body outlet 104 is provided on the discharge side, a single suction blower 108 having a fan casing 107 inside the machine body 106, and an air purification filter 109. When the airframe 106 is operated, fresh air outside the outdoor 110 is sucked into the airframe 106 through the suction side duct 103, passes through the single suction blower 108, the air purifying filter 109, and the blowout side duct 105, and then the indoor 111 Was being aired.
JP 2001-272074 A

  In such a conventional duct fan, which is a ventilation device for a living space, a large air passage for increasing the suction flow component in the direction of the central axis of the impeller is required at the fan suction port, and the blowout from the fan discharge port is required. In order to make the airflow at multiple air outlets uniform while reducing fan pressure loss and demonstrating fan capacity, a wide air chamber from the fan outlet to the air outlet is required and a wide air outlet is effective. The filter was placed in the blowout air chamber so that it could be used. As a result, there is a problem that the height dimension of the airframe is inevitably high. Also, in recent high-rise apartments, there is a market trend to increase the floor to ceiling materials in order to make the room look wider, and it is difficult to secure the dimensions of the ceiling, and duct fans that enter the ceiling with a low dimension are required. Yes.

  The present invention solves such a conventional problem, and an object of the present invention is to provide a thin and compact duct fan while incorporating a single suction type blower to ensure a necessary air volume.

  In order to achieve the above object, the duct fan of the present invention has a box-shaped airframe having two airframe inlets and a plurality of first airframe outlets facing each other, and extends from the airframe inlet to the airframe outlet. A duct fan having a flow path, provided with a single suction blower in the flow path, the single suction blower having a motor disposed on a fan suction port side, and the motor facing the flow path; The fan casing side plate on the side opposite to the motor of the single-suction blower is opposed to the vicinity of the top plate of the fuselage, and the fan discharge is between the first fuselage outlet and the fan discharge port of the single-suction blower. A fan discharge port partition having an outlet opening is provided, a blown air chamber is formed between the first airframe blowout port and the fan discharge port, and the center of the fan discharge port is defined with respect to the blown air chamber center. On the opposite side of the tongue of the scroll of the suction fan Offset disposed, in which arranged an air cleaning filter for cleaning the air between said body inlet and the fan inlet.

  Another means is that a plurality of first airframe outlets are arranged in two upper and lower stages, and the number of upper first airframe outlets located close to the fan discharge port of the single suction blower is set to the other lower stage. More than the number of the first aircraft outlet.

  Further, the other means is formed by inclining the fan discharge port partition wall in the direction in which the cross-sectional area of the blowout air chamber expands toward the first airframe blowout port.

  In addition, the other means is formed by inclining the fan discharge port partition wall downward toward the fan suction port.

  Further, the other means is such that the flat portion on the side opposite to the tongue of the scroll of the single-suction blower is formed integrally with a lateral plate connecting the airframe inlet to the first airframe outlet.

  Another means is that a plurality of second airframe outlets are provided on a lateral plate connecting the airframe inlet to the first airframe outlet.

  Another means is to make the second airframe outlet and the first airframe outlet have different opening areas.

  In another means, the second airframe outlet has an opening area larger than that of the first airframe outlet.

  The other means is such that the air volume passing through the second airframe outlet is substantially equal to the air volume passing through the first airframe outlet.

  Another means is that the fan outlet partition wall is provided with at least one bent portion between the tongue portion of the scroll and the lateral plate.

  Another means has a sound absorbing material on the inner surface of the blown air chamber.

  According to the present invention, the blower air chamber is provided between the fan discharge port of the single-suction blower and the plurality of airframe blowout ports, and the fan discharge port center is offset from the blown air chamber center. It has the effect of reducing the pressure loss of the airflow and reducing the pressure loss of the airframes while making the airflow at the multiple air outlets uniform, and making it thin enough to fit in the low ceiling behind a high-rise apartment. A duct fan can be provided.

  The duct fan according to claim 1 of the present invention is a box-shaped airframe having two airframe inlets and a plurality of first airframe outlets facing each other, and a flow path extending from the airframe inlet to the airframe outlet. A single-suction blower is provided in the flow path, the single-suction blower is a duct fan in which a motor is disposed on the fan suction port side, and the motor faces the flow path, The fan casing side plate on the side opposite to the motor of the single suction blower is opposed to the vicinity of the top plate of the airframe, and the fan discharge port is disposed between the first air blower outlet and the fan discharge port of the single suction blower. A fan outlet partition wall having an opening is provided, a blown air chamber is formed between the first airframe outlet and the fan outlet, and the center of the fan outlet with respect to the center of the blown air chamber is the single suction type Offset to the opposite side of the blower scroll tongue And location, between the body inlet port and the fan inlet are those constructed by arranging an air cleaning filter for cleaning the air. As a result, the height of the fuselage is increased while air is evenly distributed from the plurality of first aircraft outlets without causing a pressure loss due to the airflow being offset to some of the plurality of first aircraft outlets. It has the effect that the dimensions can be reduced.

  The duct fan according to claim 2 of the present invention has a plurality of first airframe outlets arranged in two upper and lower stages, and an upper first airframe outlet located close to the fan outlet of the single suction blower. Is configured to be greater than the number of the first airframe outlets on the other lower stage. Thereby, without generating a pressure loss due to the airflow being shifted to some of the plurality of first airframe outlets, it is possible to distribute the air evenly from the plurality of first airframe outlets. Have.

  The duct fan according to claim 3 of the present invention is formed by inclining the fan outlet partition wall in a direction in which the cross-sectional area of the blowout air chamber expands toward the first fuselage outlet. is there. Thereby, airflow easily flows through the plurality of first airframe outlets, and there is an effect that the resistance of the blowing portion can be reduced and the air volume can be secured.

  According to a fourth aspect of the present invention, the duct fan is formed by inclining the fan discharge port partition wall downward toward the fan suction port. Thereby, it has the effect | action that the resistance of a suction part can be decreased and air volume can be ensured.

  In the duct fan according to claim 5 of the present invention, the flat portion on the side opposite to the tongue of the scroll of the single suction blower is integrally formed with a lateral plate connecting the airframe inlet to the first airframe outlet. It is configured. Thereby, it has the effect | action that a material can be reduced.

  According to a sixth aspect of the present invention, a duct fan is configured by providing a plurality of second airframe outlets on a lateral plate connecting the airframe inlet to the first airframe outlet. As a result, it is possible to supply a large amount of air according to the amount of exhaust air, and to have an effect that the ventilation balance between the air supply and the exhaust can be made uniform.

  The duct fan according to claim 7 of the present invention is configured such that the second airframe outlet and the first airframe outlet have different opening areas. As a result, it is possible to supply a large amount of air according to the amount of exhaust air, and to have an effect that the ventilation balance between the air supply and the exhaust can be made uniform.

  The duct fan according to claim 8 of the present invention is configured such that the second airframe outlet is larger in opening area than the first airframe outlet. As a result, it is possible to supply a large amount of air according to the amount of exhaust air, and to have an effect that the ventilation balance between the air supply and the exhaust can be made uniform.

  The duct fan according to claim 9 of the present invention is configured so that the air volume passing through the second airframe outlet is substantially equal to the air volume passing through the first airframe outlet. As a result, it is possible to supply a large amount of air according to the amount of exhaust air, and to have an effect that the ventilation balance between the air supply and the exhaust can be made uniform.

  The duct fan according to claim 10 of the present invention is configured such that at least one bent portion is provided between the tongue portion of the scroll and the lateral plate on the fan outlet partition. Thereby, it has the effect | action that the resistance of the blowing part of a 2nd body fuselage outlet can be decreased, and air volume can be ensured.

  The duct fan according to claim 11 of the present invention is configured to have a sound absorbing material on the inner surface of the blown air chamber. This has the effect of reducing noise.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
A first embodiment of the present invention will be described with reference to FIGS. 1 is a side perspective view of the first embodiment of the present invention, FIG. 2 is a plan perspective view of the first embodiment of the present invention, and FIG. 3 is a side view showing an installation state of the first embodiment of the present invention.

  As shown in FIG. 1, a box-like body 3 is provided on two surfaces facing a body inlet 1 and a plurality of first body outlets 2. The airframe 3 is provided with a suction adapter 5 for connecting a suction side duct 4 to the airframe suction port 1 and a blowout adapter 7 for connecting a blowout side duct 6 to the plurality of first airframe outlets 2. . The airframe 3 has a flow path 8 from the airframe inlet 1 to the first airframe outlet 2, and a single suction blower 9 and an air purifying filter 10 are incorporated in the flow path 8. Yes. The single suction type blower 9 has a motor 13 with an impeller 12 attached to the fan suction port 11 side, and the fan casing side plate 14 on the side opposite to the motor of the single suction type blower 9 is arranged in the vicinity of the top plate 15 of the body 3. It is attached to face. A fan discharge port partition 17 having an opening of the fan discharge port 16 is provided at the fan discharge port 16 of the single-suction blower 9 so as to face the air blower outlet plate 18, and the fan discharge port partition wall 17 and the machine body are provided. A blowout air chamber 21, which is a space surrounded by the blowout plate 18, the top plate 15, the bottom plate 19, and the horizontal plate 20, is provided between the fan discharge port 16 and the fuselage blowout plate 18. Yes.

  The motor 13 is disposed in the flow path 8, and the air purification filter 10 is provided on the airframe suction port plate 22 between the airframe suction port 1 and the fan suction port 11. It is arranged inside. The single-suction blower 9 uses a fan casing width 23 that is smaller than the diameter of the fuselage inlet 1.

  Further, as shown in FIG. 2, the plurality of first airframe outlets 2 are arranged on the airframe outlet plate 18 at a substantially equal pitch. This is because in the air-conditioning ventilation design, it is a constraint that the air volume of the single suction blower 9 is equally distributed from the first air blower outlet 2 to eliminate uneven ventilation. Moreover, it is for securing the work space at the time of constructing the said several blowing side duct 6 in said 1st body blower outlet 2 by separating | separating each distance of said some said 1st fuselage blower outlet 2. FIG. .

  Further, the fan discharge port center 25 is arranged to be offset to the opposite side of the tongue portion 24 with respect to the blow-out air chamber center 26, and the fan discharge port 16 of the single suction fan 9 on the fan discharge port partition wall 17. The air flows from along the tongue 24, and blows toward the blowout air chamber center 26 in the vicinity of the fuselage outlet plate 18 through the blowout air chamber 21.

  The shape of the fan discharge port partition wall 17 is an integral structure formed by bending the extension of the scroll 27 of the single suction blower 9 from the fan discharge port 16 toward the lateral plate 20. This makes it possible to reduce the cost and make it cheaper.

  When the duct fan is operated in the above configuration, as shown in FIG. 3, the single-suction type blower 9 built in the airframe 3 installed in the ceiling 28 is operated, and the air in the outdoor 29 passes through the suction-side duct 4. The air is sucked into the single suction blower 9 through the flow path 8, and exhausted into the room 30 through the blowout duct 6 through the blowout air chamber 21.

  As shown in FIG. 1 and FIG. 2, the airflow sucked from the machine body suction port 1 flows in the direction of the motor lower portion 31, and the impeller 12 of the single suction blower 9. Is sucked in the direction of the central axis of the air and flows into the fan inlet 11. The airflow blown out from the fan discharge port 16 is blown out toward the plurality of first airframe outlets 2 through the blowout air chamber 21. Here, in FIG. 2, the main discharge air flow 32 blown out from the fan discharge port 16 flows toward the tongue portion 24 side, and the fan discharge port center 25 and the blow-out are made using the space of the blow-out air chamber 21 as a flow path. Since the air chamber center 26 has a stepped structure, the first airframe outlet 2 does not generate a pressure loss due to the airflow being shifted to some of the plurality of the first airframe outlets 2. The air is distributed evenly from each.

  The direction of the main discharge airflow 32 from the fan discharge port 16 of the single suction fan 9 increases as the characteristics of the impeller 12 are set to a high pressure specification according to the pressure loss characteristic of the air cleaning filter 10. There is a tendency toward the tongue 24 side.

  In addition, in order to reduce the thickness of the airframe 3, when the single suction blower 9 is made narrower by using the fan casing width 23 that is smaller than the diameter of the airframe inlet 1, the blade diameter is increased and the air volume is secured. The scroll 27 of the single suction fan 9 can be expanded to the vicinity of the lateral plate 20 without increasing the height of the airframe 3. Furthermore, by making the area of the fan suction port 11 larger and approaching the area of the air purification filter 10, uneven wind speed in the vicinity of the air purification filter 10 can be suppressed, and pressure loss can be reduced and air volume can be secured.

  From these things, the duct fan which can achieve thickness reduction of the height dimension 33 of a body can be provided.

  Further, since the single suction blower 9 is arranged so as to be biased toward the top surface from the center of the fuselage suction port 1, the air entered from the fuselage suction port 1 does not directly hit the back surface of the single suction blower 9. Since it is configured, the resistance of the suction portion can be reduced, and furthermore, the space in front of the fan suction port 11 necessary for sucking air in the direction of the central axis of the impeller 12 can be secured. The height dimension 33 of the airframe can be suppressed while ensuring the air volume.

  Further, when performing maintenance, as shown in FIG. 3, the ceiling inspection port 35 provided in the ceiling material 34 is opened directly below the body 3, the bottom plate 19 is removed, and the inside of the body 3 is inspected. And since the motor 13 is arranged on the bottom plate 19 side, the bottom plate 19 can be removed from the ceiling inspection port 35, and the motor 13, the impeller 12 and the air purification filter 10 can be checked at the same time. A duct fan with good maintainability can be provided.

  In the blowout air chamber 21, an air chamber distance 37 from the fan discharge port 16 to the fuselage outlet plate 18 is larger than a center distance 36 between the fan discharge port center 25 and the blowout air chamber center 26. Is desirable.

(Embodiment 2)
The second embodiment is different from the first embodiment in that the plurality of first airframe outlets 2 are arranged in two upper and lower stages and the fan discharge port partition wall 17 is inclined. Yes.

  FIG. 4 is a side perspective view of the second embodiment of the present invention. The same components as those in FIGS.

  As shown in FIG. 4, a plurality of the first air outlets 2 are arranged in two upper and lower stages on the air outlet plate 18 of the airframe 3, and are close to the fan outlet 16 of the single suction blower 9. The number of the upper first airframe outlets 38 positioned is larger than the number of the first lower airframe outlets 39 on the other lower stage. Further, the fan discharge port partition wall 17 is formed so as to be inclined in a direction in which the cross-sectional area of the blowout air chamber 21 expands toward the first airframe blowout port 2.

  When the duct fan is operated in the above-described configuration, the main discharge air flow 32 blown out from the fan discharge port 16 is such that the single suction blower 9 is in the first stage above the lower first airframe outlet 39. Since the total air volume distributed to the upper first aircraft outlet 38 is large because it is biased to the aircraft outlet 38, the number of the upper first aircraft outlet 38 is set to the other of the upper aircraft outlet 38. Since the number is lower than the number of the first airframe outlets 39 on the lower stage, the first airframe outlets 2 do not generate a pressure loss due to the airflow being shifted to some of the first airframe outlets 2. It is possible to provide a duct fan capable of equally distributing and blowing air from the machine body outlet 2.

  In addition, since the fan discharge port partition wall 17 is inclined in a direction in which the cross-sectional area of the blow-out air chamber 21 expands toward the first airframe outlet 2, the lower first airframe outlet 39 is provided. The airflow can easily flow, the resistance of the blowing portion can be reduced, and the air volume can be secured.

  Since the number of rooms in a general house is 5, the total number of the first airframe outlets 2 is 5, the number of the first airframe outlets 38 in the upper stage is 3, and the number in the other lower stage is It is desirable that the number of first airframe outlets 39 be two.

(Embodiment 3)
The third embodiment is different from the first embodiment in that the fan discharge partition wall 17 is inclined.

  FIG. 5 is a side perspective view of the third embodiment of the present invention. The same components as those in FIGS.

  As shown in FIG. 5, the fan discharge port partition wall 17 is formed so as to be inclined downward toward the fan suction port 11.

  When the duct fan is operated in the above configuration, the fan discharge port partition wall 17 is formed so as to be inclined downward toward the fan suction port 11, so that the suction airflow in front of the fan suction port 11 is the fan discharge port partition wall. Thus, it is possible to provide a duct fan that can be guided to 17 and can easily suck air in the direction of the central axis of the impeller 12, can reduce the resistance of the suction portion, and can secure the air volume.

(Embodiment 4)
FIG. 6 is a plan perspective view of the fourth embodiment of the present invention. The same components as those in FIGS.

  As shown in FIG. 6, the flat plate 40 on the side opposite to the tongue of the scroll 27 of the single-suction blower 9 is connected to the lateral plate 20 connecting the airframe inlet 1 to the first airframe outlet 2. It is integrally formed.

  In the above configuration, since the scroll 27 of the single suction type blower 9 can shorten the length of the flat portion 40 on the side opposite to the tongue portion, the duct fan can reduce the material of the scroll 27. Can be provided.

(Embodiment 5)
FIG. 7 is a plan perspective view of the fifth embodiment of the present invention. The same components as those in FIGS.

  As shown in FIG. 7, a second airframe outlet 41 is arranged on a portion of the lateral plate 20 facing the blowout air chamber 21, and the second airframe outlet 41 is the first airframe outlet. The air volume passing through the second airframe outlet 41 is substantially equal to the total airflow passing through the plurality of first air outlets 2. The second aircraft outlet 41 communicates with a kitchen in a general house, and the first aircraft outlet 2 communicates with other rooms such as a bedroom.

  When the duct fan is operated in the above configuration, the amount of air passing through the second airframe outlet 41 is larger than the total amount of air passing through the plurality of first airframe outlets 2, so the second airframe outlet 41 is connected to a general house. When communicating with other kitchens, depending on the amount of exhaust air from the range hood fan of a large-sized kitchen, it is possible to supply air that is larger than the airflow to the bedroom and other living rooms, and the ventilation balance between supply and exhaust is even A duct fan that can be provided can be provided.

  The area of the second airframe outlet 41 is preferably set to a size that is equivalent to the total area of the plurality of first airframe outlets 2.

(Embodiment 6)
FIG. 8 is a plan perspective view of the sixth embodiment of the present invention. The same components as those in FIGS.

  As shown in FIG. 8, the fan discharge port partition wall 17 is provided with a bent portion 42 between the tongue 24 of the scroll 27 and the lateral plate 20, and the fan discharge port partition wall 17 is connected to the blowing air chamber 21. The cross-sectional area is such that it expands toward the second airframe outlet 41.

  When the duct fan is operated in the above configuration, the fan discharge port partition wall 17 is provided with the bent portion 42 in a direction in which the cross-sectional area of the blowout air chamber 21 expands toward the second airframe outlet 41. Thus, a duct fan can be provided in which the airflow discharged from the fan discharge port 16 is guided to the second airframe outlet 41, the resistance of the blowout portion can be reduced, and the air volume can be secured.

(Embodiment 7)
FIG. 9 is a plan perspective view of Embodiment 7 of the present invention. The same components as those in FIGS.

  As shown in FIG. 9, a sound absorbing material 43 is provided on the inner surface of the blowing air chamber 21.

  When the duct fan is operated in the above configuration, the noise generated from the single suction type blower 9 is absorbed by the sound absorbing material 43 on the inner surface of the blown air chamber 21, so that a low noise duct fan can be provided. .

  In addition to air supply ventilation in general houses, facility equipment can be cooled by using the air blown from the air outlet, reducing the pressure loss of the air flow and securing the air volume, and can be installed in a thin and compact installation. It can also be applied to the use of air blowing.

Side perspective view of the duct fan according to the first embodiment of the present invention. Plane perspective view of the duct fan Side view showing the installation state of the duct fan Side perspective view of a duct fan according to Embodiment 2 of the present invention Side perspective view of a duct fan according to Embodiment 3 of the present invention Plane perspective drawing of the duct fan of Embodiment 4 of this invention Plane perspective drawing of the duct fan of Embodiment 5 of this invention Plane perspective drawing of the duct fan of Embodiment 6 of this invention Plane perspective drawing of the duct fan of Embodiment 7 of this invention Side perspective view of a conventional duct fan Plane perspective view of the duct fan Side view showing the installation state of the duct fan

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Airframe inlet 2 1st airframe outlet 3 Airframe 8 Flow path 9 Single suction type blower 10 Air cleaning filter 11 Fan inlet 13 Motor 14 Fan motor side plate on the non-motor side 15 Top plate 16 Fan outlet 17 Fan outlet Bulkhead 20 Horizontal plate 21 Blowing air chamber 24 Tongue portion 27 Scroll 38 Upper first aircraft outlet 39 Lower first aircraft outlet 40 Anti-tongue side flat portion 41 Second aircraft outlet 42 Bending portion 43 Sound absorption Material

Claims (11)

A box-shaped airframe having two airframe inlets and a plurality of first airframe outlets facing each other has a flow path from the airframe inlet to the airframe outlet, and a single suction fan in the flow path The single suction fan is a duct fan in which a motor is disposed on the fan suction port side, and the motor faces the flow path, and the fan casing side plate on the side opposite to the motor of the single suction fan Facing the vicinity of the top plate of the fuselage, and providing a fan discharge port partition having an opening of the fan discharge port between the first fuselage outlet and the fan discharge port of the single suction blower, A blowout air chamber is formed between the first airframe blowout port and the fan discharge port, and the fan discharge port center is offset from the center of the blowout air chamber on the opposite side of the tongue portion of the scroll of the single suction blower The airframe inlet and the fan inlet Duct fan, characterized in that arranged an air cleaning filter for cleaning the air between. A plurality of first airframe outlets are arranged in two upper and lower stages, and the number of upper first airframe outlets located close to the fan outlet of the single suction blower is set to the number of the first lower airframe outlet. The duct fan according to claim 1, wherein the number is larger than the number of the duct fans. 3. The duct fan according to claim 2, wherein the fan discharge port partition wall is formed so as to be inclined in a direction in which a cross-sectional area of the blow-out air chamber expands toward the first airframe blow-out port. 3. The duct fan according to claim 1, wherein the fan discharge port partition is formed so as to be inclined downward toward the fan suction port. 5. The flat portion on the side opposite to the tongue of the scroll of the single suction blower is formed integrally with a lateral plate connecting the airframe inlet to the first air outlet. Duct fan. The duct fan according to any one of claims 1 to 5, wherein a plurality of second air outlets are provided on a lateral plate connecting from the air inlet to the first air outlet. The duct fan according to claim 6, wherein the second airframe outlet and the first airframe outlet have different opening areas. The duct fan according to claim 6, wherein the second airframe outlet has a larger opening area than the first airframe outlet. The duct fan according to claim 6, wherein the air volume passing through the second airframe outlet and the airflow passing through the first airframe outlet are substantially equal. The duct fan according to any one of claims 6 to 9, wherein the fan discharge port partition wall is provided with at least one bent portion between a tongue portion of the scroll and the lateral plate. The duct fan according to any one of claims 1 to 10, further comprising a sound absorbing material on an inner surface of the blowing air chamber.

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