JP3858753B2 - Centrifugal blower - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a centrifugal blower including a centrifugal fan and a scroll casing.
[0002]
[Prior art]
As a prior art, for example, there is a centrifugal blower described in JP-A-10-196596. An example of this centrifugal blower is shown in FIG.
[0003]
As shown in FIG. 10, the centrifugal fan 101 has a plurality of blades 111 arranged in an annular shape and is driven by a motor (not shown) to discharge the air sucked from the rotation axis direction in the radially outward direction. Then, a spiral air passage 126 is formed around the centrifugal fan 110 with the nose portion 127 as a starting point, and the end of the centrifugal fan 110 in the rotation axis direction (the end on the front side in FIG. 10) is opened. And a scroll casing 120 having a suction port 124. The scroll casing 120 is provided with an overhanging portion 123 a that partially closes the suction port 124.
[0004]
In the vicinity of the nose portion 127, which is the starting point of the spiral air passage 126, the inner surface 121 of the outer peripheral portion of the scroll casing 120 (cylindrical cylindrical portion extending in the rotation axis direction of the centrifugal fan 110) and the blade of the centrifugal fan 110 111 is close to the tip, and the internal pressure tends to increase. When the internal pressure at this portion increases, a backflow of air to the suction port 124 is likely to occur, so that the backflowed air is prevented from flowing out of the suction port 124 by the overhang portion 123a.
[0005]
[Problems to be solved by the invention]
However, when the present inventors examined the downsizing of the centrifugal blower of the above-described prior art, although the backflowed air does not flow out from the suction port 124, there is a problem that noise increases.
[0006]
As a result of intensive studies by the present inventors, it has been clarified that the main cause of this noise is an air flow vortex generated in the vicinity of the nose portion 127 in the scroll casing 120.
[0007]
FIG. 11 is a schematic diagram showing a cross-sectional structure in the vicinity of the nose portion 127 of the centrifugal blower. When the centrifugal fan 110 is driven and rotated by a motor (not shown), the air sucked from the suction port 124 is discharged outwardly by the blade 111. The wind speed of the wind discharged at this time varies depending on the position in the rotation axis direction.
[0008]
As shown in FIG. 11, when the suction port 124 is provided only on the lower side in the rotation axis direction, the wind speed of the discharge air tends to be higher on the upper side than on the lower side. Then, the upper discharge wind whose wind speed is fast reaches the inner surface 121 (the inner surface of the cylindrical portion) 121 of the scroll casing 120 facing the blade 111 before the lower discharge wind whose wind speed is slower than this. A part goes around downward. Since the flow of the sneak wind is opposite to the flow of the discharge air on the lower side, an air flow vortex is likely to occur. This air flow vortex causes noise.
[0009]
In order to reduce this noise, there is a means of increasing the distance between the blade 111 and the inner surface 121 (closer to the distance before considering miniaturization) and decreasing the wind speed of the discharge air reaching the inner surface 121. There is a problem that the size of the centrifugal fan increases.
[0010]
This invention is made | formed in view of the said point, and it aims at providing the centrifugal air blower which can reduce a noise, without enlarging a physique.
[0011]
[Means for Solving the Problems]
  In order to achieve the above object, in the invention described in claim 1,
  A plurality of blades (11) arranged in an annular shape, and a centrifugal fan (10) that discharges air sucked from the direction of the rotation axis in a radially outward direction;
  A motor (30) for rotationally driving the centrifugal fan (10);
  A spiral air passage (26) is formed around the centrifugal fan (10) starting from the nose portion (27), and a suction port (24) that opens an end of the centrifugal fan (10) in the rotational axis direction. In a centrifugal blower (1) comprising a scroll casing (20) having
  The scroll casing (20) has an inner surface (21) facing the blade (11) in the vicinity of the nose portion (27),By providing an inclined surface (28) with respect to the rotational axis of the centrifugal fan (10),The part of the centrifugal fan (10) that is slower than the part where the wind speed of the discharge air is faster is formed so that the distance from the blade (11) is shorter.And
  The inclined surface (28) is provided on the rotational direction side of the centrifugal fan (10) on the tip side of the nose portion (27) where the wind speed is higher than the slow wind speed.It is characterized by being.
[0012]
  according to this,By forming the inner surface (21) of the scroll casing (20) having a different distance from the blade (11) by the inclined surface (28),It is possible to prevent the discharge wind having a high wind speed from reaching the inner surface (21) facing the blade (11) before the discharge wind having a low wind speed. Therefore, by making the distance between the inner surface (21) and the blade (11) of the portion where the wind speed of the discharge air is slow, smaller than the portion where the wind speed of the discharge air is fast, It is possible to prevent sneaking inTherefore, unnecessary vortices are unlikely to occur when the discharge air collides.In this way, noise can be reduced without increasing the size of the centrifugal blower (1).
[0015]
  Also,Claim 2In the invention described in
  A plurality of blades (11) arranged in an annular shape, and a centrifugal fan (10) that discharges air sucked from the direction of the rotation axis in a radially outward direction;
  A motor (30) for rotationally driving the centrifugal fan (10);
  A spiral air passage (26) is formed around the centrifugal fan (10) starting from the nose portion (27), and a suction port (24) that opens an end of the centrifugal fan (10) in the rotational axis direction. In a centrifugal blower (1) comprising a scroll casing (20) having
  The suction port (24) is open only on one end side in the rotation axis direction of the scroll casing (20),
  The scroll casing (20) has an inner surface (21) facing the blade (11) in the vicinity of the nose portion (27),By providing an inclined surface (28) with respect to the rotational axis of the centrifugal fan (10),The part closer to the part far from the inlet (24) is formed so that the distance to the blade (11) is shorter.And
  The inclined surface (28) is provided closer to the rotational direction side of the centrifugal fan (10) at the distal end of the nose portion (27) than on the side closer to the suction port (24) than on the side closer to the suction port (24). BeingIt is characterized by being.
[0016]
  according to this,By forming the inner surface (21) of the scroll casing (20) having a different distance from the blade (11) by the inclined surface (28),The inner surface (21) facing the blade (11) before the discharge air having a high wind speed that is likely to be generated at a site far from the suction port (24) is earlier than the discharge wind having a low wind speed that is likely to be generated at a site near the suction port (24). ) Can be prevented. Therefore, the distance between the inner surface (21) and the blade (11) of the part where the discharge wind speed is slow is made smaller than the part where the wind speed of the discharge wind is fast. It is possible to prevent sneaking inTherefore, unnecessary vortices are unlikely to occur when the discharge air collides.In this way, noise can be reduced without increasing the size of the centrifugal blower (1).
[0019]
  Also,Claim 3The inclined surface (28) is characterized in that the inclined surface (28) is formed on substantially half of one end side in the rotational axis direction of the inner surface (21) facing the blade (11) in the vicinity of the nose portion (27). .
[0020]
According to this, when the scroll casing (20) is formed by two members (20a, 20b) divided into two at the approximate center in the rotation axis direction, the inclined surface (28) is formed only on one member (20b). Since it should just form, manufacture of a scroll casing (20) is easy.
[0021]
  Also,Claim 4The inclined surface (28a) is characterized in that the inclined surface (28a) is formed in substantially the entire region in the rotational axis direction of the inner surface (21) facing the blade (11) in the vicinity of the nose portion (27).
[0022]
According to this, it is possible to reliably prevent the discharge wind having a high wind speed from wrapping around.
[0023]
  Also,Claim 5In the invention described in (4), a metal cover (220a) provided with a substrate (31) having a drive circuit for driving the motor (30) and arranged to cover the substrate (31) is provided as one part of the scroll casing (20). It is characterized by constituting the part.
[0024]
Thus, since the metal cover (220a) which comprises a part of scroll casing (20) has covered the board | substrate (31), it can suppress that the electromagnetic wave which a board | substrate (31) generate | occur | produces leaks outside, It is possible to suppress the substrate (31) from receiving electromagnetic waves from the outside.
[0025]
  Also,Claim 6In the invention described in (1), the motor (30) is arranged inside the scroll casing (20) and the plurality of blades (11).
[0026]
According to this, since the motor (30) is not disposed outside the scroll casing (20), it is easy to miniaturize the centrifugal blower (1).
[0027]
  Also,Claim 7In the invention described inClaim 6Described inCentrifugal blowerThe scroll casing (20) is characterized in that at least a part thereof is formed of a conductive member.
[0028]
According to this, it can suppress that the electromagnetic wave which the motor (30) arrange | positioned in a scroll casing (20) generate | occur | produces outside leaks, and suppresses that a motor (30) malfunctions with the electromagnetic wave from the outside. It is possible.
[0029]
In addition, the code | symbol in the parenthesis attached | subjected to each said means shows the correspondence with the specific means of embodiment description later mentioned.
[0030]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0031]
(First embodiment)
The centrifugal blower of the present invention is a so-called static pressure blower capable of blowing air even if the downstream side has a high-pressure loss structure, and the centrifugal blower (hereinafter abbreviated as “blower”) 1 of this embodiment is, for example, FIG. It is suitable for application to a seat air conditioner as shown in FIG. As shown in FIG. 1, the blower 1 is disposed below the sheet 2, and the sheet 2 is formed with a passage 3 through which air blown from the blower outlet 25 of the blower 1 is circulated. Here, illustration of a passage forming member for forming the passage 3 and a structural member for obtaining sheet strength is omitted.
[0032]
The air flowing through the passage 3 is blown out from the pores of the skin 2a forming the seating surface and the back surface of the seat 2, and the conditioned air is supplied to the user seated on the seat 2. In the present embodiment, the air blown out from the pores of the skin 2a is blown out from the blower 1 and then heated by a heating means (not shown) disposed in the sheet 2 so as to have an appropriate temperature.
[0033]
2 and 3 are schematic configuration diagrams of the blower 1 according to the present embodiment, FIG. 2 is a plan view, and FIG. 3 is a cross-sectional view taken along line AA of FIG.
[0034]
As shown in FIGS. 2 and 3, the blower 1 has a plurality of (27 in this example) blades 11 arranged in an annular shape on the outer periphery at regular intervals, and one end in the rotation axis direction (the back side of the paper surface in FIG. 2). A centrifugal fan (hereinafter abbreviated as “fan”) 10 is provided which introduces air from a suction port 24 of a scroll casing 20 (described later) provided at the end of the direction and discharges the air outward. In FIG. 2, a part of the blade 11 is illustrated and a part of the blade 11 is omitted.
[0035]
As shown in FIG. 3, a motor 30 is arranged at the center of the inside of the plurality of blades 11 arranged in an annular shape of the fan 10. Yes. In the present embodiment, a brushless motor is employed as the motor 30.
[0036]
Around the fan 10, a scroll casing 20 is disposed that surrounds the fan 10 and forms a spiral air passage 26 that gradually expands toward the air outlet 25. As shown in FIG. 3, the scroll casing 20 includes an upper casing 20a and a lower casing 20b, and both the casings 20a and 20b are formed by molding a polypropylene material.
[0037]
The motor 30 is disposed on the upper surface 22 of the scroll casing 20 which is the bottom surface of the casing 20a (the ceiling surface in the arrangement shown in FIG. 3). The aforementioned suction port 24 is provided on the lower surface 23 of the scroll casing 20 that is the bottom surface of the casing 20b (the surface in the rear side direction in FIG. 2). Further, the side surface portion 20c of the scroll casing 20 is formed by the cylindrical portions of the casings 20a and 20b.
[0038]
As shown in FIG. 2, the scroll casing 20 is sucked from the side of the portion where the outer periphery of the fan 10 and the side surface portion 20c are close to each other in the vicinity of the nose portion 27 that is the starting point of the spiral air passage 26 of the scroll casing 20. An overhang portion 23 a is provided so as to partially close the suction port 24 toward the inside of the port 24.
[0039]
A blower outlet 25 is provided on the most downstream side of the spiral air passage 26 of the scroll casing 20. For example, as shown in FIG. 1, when the blower 1 is used in a seat air conditioner, this blower outlet is provided. 25 communicates with the passage 3 in the seat 2.
[0040]
In the vicinity of the nose portion 27 of the scroll casing 20, an inclined surface 28 is formed on the inner surface 21 of the side surface portion 20 c facing the blade 11 of the fan 10. The inclined surface 28 extends smoothly in the direction of the tip of the nose portion 27.
[0041]
FIG. 4 is a cross-sectional view taken along the line B-B in FIG. 2 schematically showing the structure in the vicinity of the nose portion 27. As shown in FIG. 4, the inner surface 21 of the scroll casing 20 facing the blade 11 has an inclined surface 28 in which a substantially lower half (substantially half on one end side in the rotation axis direction of the fan 10) is inclined with respect to the rotation axis of the fan 10. It has become.
[0042]
Here, the inclined surface 28 is inclined so that the distance from the blade 11 is shorter in the portion closer to the suction port 24 than in the portion far from the suction port 24. Therefore, the inner surface 21 in the vicinity of the nose portion 27 has a shorter distance from the blade 11 in a portion closer to the suction port 24 than in a portion far from the suction port 24.
[0043]
The inclined surface 28 is formed in the lower casing 20 b of the casings constituting the scroll casing 20. Therefore, the inclined surface 28 can be easily formed at the time of molding the casing 20b, and mold release after molding is also easy.
[0044]
Next, the operation of the blower 1 will be described based on the above configuration.
[0045]
When the motor 30 is driven and the fan 10 is rotated, air is sucked from the suction port 24 by the movement of the blade 11 that is annularly arranged on the fan 10. The air sucked from the suction port 24 is pushed out (discharged) radially by the blade 11 and collected by the spiral air passage 26. At this time, the wind speed of the wind (air flow) pushed out by the blade 11 is affected by the wind sucked from the suction port 24, and the vicinity of the upper surface 22 far from the suction port 24 is closer to the suction port as shown in FIG. 4. The distribution is faster than the vicinity of the lower surface 23 near 24.
[0046]
However, the inner surface 21 in the vicinity of the nose portion 27 of the casing 20 is provided with an inclined surface 28, and the portion closer to the suction port 24 where the wind speed is slower than the portion far from the suction port 24 where the wind speed of the pushed-out wind is faster. The distance from the blade 11 is shortened. Therefore, it is difficult for a difference in time required for the winds of different wind speeds pushed out by the blade 11 to reach the inner surface 21. As a result, the wind pushed out by the blade 11 is rectified in the spiral air passage 26 and flows toward the outlet 25 without the wind in the vicinity of the upper surface 22 having a high wind speed turning around to the lower surface 23 side.
[0047]
According to the above-described configuration and operation, it is easy to prevent the wind in the vicinity of the upper surface 22, which is pushed out by the blade 11, from flowing fast toward the lower surface 23. Therefore, it is difficult to generate wind and vortex pushed out on the lower surface 23 side. In this way, it is possible to reduce noise caused by the generation of wind (air flow) vortices. Moreover, since the above-mentioned structure only provided the inclined surface 28 in the inner surface 21 near the nose part 27, the physique of the air blower 1 does not become large.
[0048]
The inclined surface 28 is provided only in the vicinity of the nose portion 27 and is not provided in the downstream side. However, except for the vicinity of the nose portion 27, the distance between the blade 11 and the inner surface of the side surface portion 20 c of the scroll casing 20 is the nose portion 27. Since it is larger than the vicinity, the wind speed of the discharge air reaching the inner surface is reduced, and the vortex of the air flow is hardly generated.
[0049]
Further, as shown in FIG. 2, the inclined surface 28 extends smoothly up to the distal end direction of the nose portion 27. Therefore, when a part of the air flow directed to the flow outlet 25 in the spiral air passage 26 is divided by the nose portion 27 and recirculated to the spiral air passage 26, this flow can be prevented from being disturbed. Thereby, it is possible to suppress noise generation due to turbulence of the recirculation wind.
[0050]
Further, in the blower 1 having the above-described configuration, the motor 30 is disposed inside the plurality of blades 11 that are annularly disposed in the scroll casing 20. Therefore, it is possible to reduce the size of the blower 1 as compared with the case where it is arranged outside the scroll casing 20. Furthermore, it is possible to suppress the drive sound of the motor 30 being released to the outside as compared with the case where the motor 30 is disposed outside the scroll casing 20.
[0051]
FIG. 5 is a graph showing the evaluation results of the blower 1 performed by the present inventors. When the blower 1 of the present embodiment is mounted below the vehicle seat and the motor 30 is driven to rotate the fan 10 4320 revolutions per minute, a microphone is installed at the position of the ear of the user seated on the seat, and the noise level Was measured.
[0052]
As shown in FIG. 5, the noise level of the blower 1 of the present embodiment was 43.1 dB (A). On the other hand, in the blower having the same structure as the blower 1 of the present embodiment and having a conventional structure in which the inclined surface 28 is not formed in the scroll casing 20, the noise level is 45.6 dB (A). Confirmed that the noise of the blower 1 of the present embodiment was significantly reduced from the noise of the blower having a conventional structure.
[0053]
(Second Embodiment)
Next, a second embodiment will be described based on the drawings.
[0054]
The second embodiment is different from the first embodiment in the shape of the scroll casing. In addition, about the part similar to 1st Embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.
[0055]
The blower of the present embodiment has substantially the same configuration as the blower 1 of the first embodiment. As shown in FIG. 6, the scroll casing 20 of the present embodiment is formed as an inclined surface 28 a in which the inner surface 21 in the vicinity of the nose portion 27 is inclined with respect to the rotation axis over the entire region in the rotation axis direction of the fan 10. .
[0056]
The inclined surface 28a is formed so that the distance from the blade 11 is shorter in the portion closer to the suction port 24 where the wind speed is slower than the portion far from the suction port 24 where the wind speed of the wind pushed out by the blade 11 is faster. Yes.
[0057]
Also with this configuration, substantially the same effect as in the first embodiment can be obtained. However, since the inclined surface 28a is formed in the vicinity of the nose portion 27 over the entire region in the direction of the rotation axis of the fan 10, the wind in the vicinity of the upper surface 22 pushed by the blade 11 is faster than in the first embodiment. Is more easily prevented from entering the lower surface 23 side. Therefore, it is possible to further reduce the noise caused by the vortex of the air flow.
[0058]
FIG. 7 is a result of evaluation of the noise of the blower performed by the present inventors, and is a result of performing the same evaluation as that of the blower of the first embodiment. As shown in FIG. 7, the noise level of the blower of this embodiment is 40.1 dB (A), and the present inventors have confirmed that the noise is significantly reduced as compared with the blower having the conventional structure.
[0059]
(Third embodiment)
Next, a third embodiment will be described with reference to the drawings.
[0060]
The third embodiment is different from the first embodiment in the structure of the scroll casing. In addition, about the part similar to 1st and 2nd embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.
[0061]
FIG. 8 is a cross-sectional view showing a schematic structure of the blower 201 of the present embodiment. 8, the cross section which passes along the rotating shaft of the fan 10 of the air blower 201 and the nose part vicinity of the scroll casing 220 is shown, and illustration of the blower outlet 25, the channel | path etc. which communicate with this is abbreviate | omitted.
[0062]
As shown in FIG. 8, the blower 201 includes the fan 10 that is substantially the same as that of the first embodiment. A motor 30 is arranged in the center of the plurality of blades 11 arranged in an annular shape of the fan 10, and the fan 10 is connected to a rotor of the motor 30. Reference numeral 31 denotes a substrate on which a drive circuit of the motor 30 is formed. A stator of the motor 30 is held on the lower surface of the substrate 31. In addition, although the element which comprises a part of drive circuit is mounted in the upper surface of the board | substrate 31, the illustration is abbreviate | omitted.
[0063]
Around the fan 10, a scroll casing 220 is disposed that surrounds the fan 10 and forms a spiral air passage 26 that gradually expands toward an air outlet 25 (not shown). The scroll casing 220 includes an upper metal casing 220a and a lower resin casing 220b. The resin casing 220b is formed by molding a conductive resin containing metal fibers.
[0064]
As shown in FIG. 8, the metal casing 220a, which is a metal cover, includes a first step portion 229a, a second step portion 229b, and a third step portion 229c inside the outer peripheral locking portion. The above-described substrate 31 is fixed to the metal casing 220a in contact with the second step portion 229b. Thereby, the metal casing 220a covers the substrate 31 so that the first step portion 229a of the metal casing 220a covers an element (not shown) of the substrate 31 and the like. The upper surface 22 of the scroll casing 220 is configured by the third step portion 229c of the metal casing 220a and the substrate 31.
[0065]
In the vicinity of the nose portion of the resin casing 220b, an inclined surface 28a is formed on the inner surface 21 of the side surface portion 20c over the entire rotation axis direction of the fan 10 as in the second embodiment. Further, a stainless steel metal mesh 40 is screwed onto the bottom surface of the resin casing 220b so as to cover the suction port 24.
[0066]
According to the above-described configuration, the substantial scroll casing including the spiral air passage 26 is formed by the third step portion 229c of the metal casing 220a, the substrate 31, and the resin casing 220b. Thus, by making the board | substrate 31 a part of substantial scroll casings, it is possible to make the physique of the air blower 201 smaller than the case where the board | substrate 31 is mounted in the exterior of a scroll casing.
[0067]
Further, the scroll casing 220 of the present embodiment is formed with the inclined surface 28a as in the second embodiment, and thus has an effect of reducing noise caused by the vortex of the air flow.
[0068]
The scroll casing 220 includes a metal casing 220a and a resin casing 220b made of a conductive resin, and a metal mesh 40 is disposed in the resin casing 220b so as to cover the suction port 24. Therefore, the electromagnetic waves generated by the motor 30 and the board 31 including the mounting components (not shown) can be prevented from leaking to the outside. Furthermore, it is possible to prevent the motor 30 from malfunctioning due to external electromagnetic waves. The metal mesh 40 also has a function of preventing foreign matter from being sucked from the suction port 24.
[0069]
In the present embodiment, the metal casing 220a, the resin casing 220b, and the metal mesh 40 are all formed of a conductive member. However, the conductive member is only partially used in accordance with the required performance of the electromagnetic wave shield. It doesn't matter. For example, in this embodiment, the resin casing 220b may be formed of a general non-conductive resin that does not contain a conductive component.
[0070]
Further, the motor 30 and the substrate 31 are covered with a metal casing 220a. Therefore, even if a droplet or the like falls from above, it is possible to prevent the droplet from adhering to the motor 30 or the drive circuit.
[0071]
(Other embodiments)
In each of the above-described embodiments, the inclined surfaces 28 and 28a are surfaces formed linearly in the direction of the rotation axis of the fan 10, but are higher than a portion far from the suction port 24 where the wind speed of the air pushed out by the blade 11 is fast. As long as the portion closer to the suction port 24 where the wind speed is slower is a surface formed so that the distance from the blade 11 is shortened, the surface is not limited thereto. For example, as shown in the cross-sectional structure in FIG. 9, the inclined surface may be formed as a curved surface in the rotation axis direction of the fan 10.
[0072]
Moreover, in each said embodiment, the inclined surfaces 28 and 28a were formed in a part (the range of about 60 degree | times of the perimeter as shown in FIG. 2) of the side part 20c of the scroll casings 20 and 220. However, the present invention is not limited to this. For example, according to various characteristics of the blower such as the shape and size of the spiral air passage 26, the installation range of the inclined surface can be appropriately set as long as it includes the vicinity of the nose portion 27.
[0073]
Moreover, in the said 1st Embodiment, the inclined surface 28 was formed in the lower half side of the inner surface 21, and the inclined surface 28a was formed in the whole inner surface 21 in the said 2nd and 3rd embodiment. However, the fan 10 rotation axis direction range which forms an inclined surface is not limited to these. However, when the scroll casing is composed of a plurality of members and the member provided with the inclined surface is processed using a mold, the inclined surface is preferably provided in a portion that does not have an overhang structure. Thereby, manufacture of the scroll casing which has an inclined surface becomes easy.
[0074]
Further, in each of the above embodiments, the distance between the inner surface 21 and the blade 11 is closer to the portion closer to the suction port 24 where the wind speed is slower than to the portion farther from the suction port 24 where the wind speed of the wind pushed out by the blade 11 is faster. The smooth inclined surface 28 or the inclined surface 28a is provided so as to be shorter, but is not limited thereto. A surface near the suction port 24 where the wind speed is slower than a portion far from the suction port 24 where the wind speed of the wind is faster is formed with a surface where the distance from the blade 11 is shortened. If it does not occur, a multi-stage shape, for example, may be used.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a seat air conditioner to which a centrifugal blower according to a first embodiment of the present invention is applied.
FIG. 2 is a plan view showing a schematic structure of the centrifugal fan according to the first embodiment of the present invention.
FIG. 3 is a cross-sectional view of the centrifugal fan shown in FIG.
4 is a cross-sectional view taken along the line B-B showing a schematic structure of a main part of the centrifugal blower shown in FIG. 2;
FIG. 5 is a graph showing the measurement result of the noise level of the centrifugal blower in the first embodiment performed by the present inventors.
FIG. 6 is a cross-sectional view showing a schematic structure of a main part of a centrifugal blower according to a second embodiment of the present invention.
FIG. 7 is a graph showing the measurement result of the noise level of the centrifugal blower in the second embodiment performed by the present inventors.
FIG. 8 is a cross-sectional view showing a schematic structure of a centrifugal fan according to a third embodiment of the present invention.
FIG. 9 is a schematic cross-sectional view of a main part of a centrifugal blower according to another embodiment.
FIG. 10 is a plan view of a conventional centrifugal blower.
FIG. 11 is a schematic cross-sectional view of a main part of a conventional centrifugal fan.
[Explanation of symbols]
1 Centrifugal blower
10 Centrifugal fan
11 blades
20 Scroll casing
20c side part
21 Inside
24 Suction port
26 Spiral ventilation
27 Nose Club
28, 28a Inclined surface
30 motor
31 substrates
220a Metal casing (conductive member, metal cover)

Claims (7)

A plurality of blades (11) arranged in an annular shape, and a centrifugal fan (10) that discharges air sucked from the direction of the rotation axis in a radially outward direction;
A motor (30) for rotationally driving the centrifugal fan (10);
A spiral air passage (26) is formed around the centrifugal fan (10) starting from a nose portion (27), and a suction port (opening an end in the rotational axis direction of the centrifugal fan (10)) In a centrifugal blower (1) comprising a scroll casing (20) having 24),
In the scroll casing (20), an inner surface (21) facing the blade (11) in the vicinity of the nose portion (27) includes an inclined surface (28) with respect to the rotation shaft, whereby the centrifugal fan (10 ) Is formed so that the distance from the blade (11) is shorter in the part that is slower than the part in which the wind speed of the discharge wind is fast .
The inclined surface (28) is provided on the rotation direction side of the centrifugal fan (10) on the tip side of the nose portion (27) where the wind speed is higher than the slow wind speed side . A centrifugal blower characterized by that. A plurality of blades (11) arranged in an annular shape, and a centrifugal fan (10) that discharges air sucked from the direction of the rotation axis in a radially outward direction;
A motor (30) for rotationally driving the centrifugal fan (10);
A spiral air passage (26) is formed around the centrifugal fan (10) starting from a nose portion (27), and a suction port (opening an end in the rotational axis direction of the centrifugal fan (10)) In a centrifugal blower (1) comprising a scroll casing (20) having 24),
The suction port (24) is open only on one end side in the rotation axis direction of the scroll casing (20),
In the scroll casing (20), the inner surface (21) facing the blade (11) in the vicinity of the nose portion (27) includes an inclined surface (28) with respect to the rotation shaft, whereby the suction port (24). The part closer to the part far from the part is formed such that the distance from the blade (11) is shorter,
The inclined surface (28) has a distal end portion of the nose portion (27) of the centrifugal fan (10) on the side farther from the suction port (24) than on the side closer to the suction port (24). A centrifugal blower characterized by being provided on the rotational direction side . The centrifugal blower according to claim 1 or 2 , wherein the inclined surface (28) is formed on substantially half of one end side of the inner surface (21) in the rotation axis direction . The centrifugal blower according to claim 1 or 2 , wherein the inclined surface (28a) is formed in substantially the entire region of the inner surface (21) in the rotation axis direction . A substrate (31) having a drive circuit for driving the motor (30);
The metal cover (220a) arranged so as to cover the substrate (31) constitutes a part of the scroll casing (20), according to any one of claims 1 to 4. Centrifugal blower. The centrifugal type according to any one of claims 1 to 5, wherein the motor (30) is disposed inside the scroll casing (20) and the plurality of blades (11). Blower. The centrifugal blower according to claim 6 , wherein at least a part of the scroll casing (20) is formed of a conductive member .

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