JP2018119550A - Centrifugal fan - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a centrifugal fan capable of reducing the noise during air blowing, and capable of reducing the size and the cost.SOLUTION: In a centrifugal fan 1, an impeller 3 having a plurality of blades 4 arranged in a circumferential direction is stored between an upper plate 11 and a motor base 12. The centrifugal fan 1 includes a motor 2 for rotating the impeller 3, and a circuit board 23 on which an electronic component 24 is mounted. The centrifugal fan 1 can blow out air sucked through a suction port to a radial direction outward of the impeller 3 in accordance with rotation of the impeller 3. The motor base 12 is made of metal, and has a recession 15 recessed downward. The motor 2 is installed on a bottom surface of the recession 15. A part of an insulator 22 of the motor 2 and the circuit board 23 are stored in an inside of the recession 15.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a centrifugal fan, and more particularly to a centrifugal fan that reduces noise caused by blowing air and reduces costs.

  A centrifugal fan (or simply referred to as “centrifugal fan”) is configured by housing an impeller in a scroll casing having a suction port and a blow-out port. An impeller has a large number of blades arranged around a rotation axis of a motor. The centrifugal fan causes the air sucked from the suction port to flow between the blades from the center of the impeller, and blows the air toward the outside of the impeller by a fluid force due to the centrifugal action accompanying the rotation of the impeller. The air blown out from the outer periphery of the impeller passes through the inside of the scroll casing, becomes high-pressure air, and is blown out from the blowout opening.

  Centrifugal fans are widely used for cooling, ventilating, air-conditioning, blowers for vehicles, and the like for home appliances, OA equipment, and industrial equipment. The blowing performance and noise of the centrifugal fan are greatly influenced by the blade shape of the impeller and the scroll casing shape (the structure of the centrifugal fan).

  In order to reduce noise and improve air blowing performance, the shape of the impeller and the structure of the scroll casing have been optimized, and various proposals have been made. In the impeller, a centrifugal fan that has been conventionally designed to reduce noise by optimizing the blade shape has been proposed (see, for example, Patent Document 1 below).

  6 is a plan view showing a centrifugal fan described in Patent Document 1 below, and FIG. 7 is a perspective view showing an impeller in the centrifugal fan shown in FIG.

  With reference to FIGS. 6 and 7, the impeller 120 of the centrifugal fan 100 has a plurality of blades 123 installed between a main plate 121 and a sub plate 122. The outer peripheral side of the blades 123 rotates with a delay with respect to the rotational direction of the impeller 120 (counterclockwise in FIG. 6). The impeller 120 is attached to a spiral casing 127 and blows air.

  The air to be blown is sucked in from the suction port 140 of the impeller 120, is subjected to fluid force due to centrifugal action by the blades 123 of the impeller 120, and is discharged from the outer periphery of the impeller 120. The pressure of the air discharged from the outer periphery of the impeller 120 is increased by the spiral casing 127 surrounding the outer periphery of the impeller 120, and the air is blown out from the outlet 141.

  In this way, the blade structure in which the outer peripheral side of the blades 123 rotates with respect to the rotation direction of the impeller 120 rather than the inner peripheral side of the blades 123 is referred to as a backward blade. That is, as shown in FIG. 6, the wing 123 has a blade shape curved and inclined backward with respect to the rotation direction. A centrifugal fan having such a blade shape is generally called a turbo fan.

  In the turbofan shown in FIG. 6, a plurality of blades 123 are sandwiched between a main plate 121 and a sub plate 122 having the same outer diameter as the main plate 121. The blade 123 has a trailing edge that is cut so that the blade arc 135 on the main plate 121 side is shorter than the blade arc 134 on the sub plate 122 side. Thereby, a time difference can be provided between the time when the rear edge 131 located on the main plate 121 side crosses the casing tongue 129 and the time when the rear edge 132 located on the sub plate 122 side crosses the casing tongue 129. . Therefore, since the pressure fluctuation generated by the wing 123 crossing the casing tongue 129 is temporally dispersed, it is described in Patent Document 1 that the generation energy of sound is dispersed and the generation of noise is suppressed. Yes.

JP-A-63-289295

  The turbofan described in the above-mentioned Patent Document 1 is designed to suppress noise during blowing by examining the shape of the blade 123. However, since the casing tongue 129 is formed in the spiral casing 127, the noise generated when the air blown from the impeller 120 collides with the casing tongue 129 cannot be sufficiently reduced.

  Moreover, in patent document 1, the air discharged from the outer periphery of the impeller 120 blows off from the blower outlet 141 along the inner wall surface of the spiral casing 127. For this reason, the air flow is likely to be disturbed near the inner wall surface of the spiral casing 127 and the vicinity of the outlet 141, and the disturbance of the air flow causes noise.

  Furthermore, in recent years, centrifugal fans incorporated in blowers of home appliances, OA devices, vehicles and the like have been strongly demanded to reduce costs as well as to reduce noise and size.

  However, in the spiral casing 127 as shown in FIG. 6, it is necessary to form a flow path for guiding air to the outlet on the outer periphery of the impeller 120. For this reason, the outer diameter of the spiral casing 127 usually requires about twice the outer diameter of the impeller 120. As a result, it is difficult to reduce the size of the turbofan. The spiral casing 127 and the impeller 120 are generally formed of synthetic resin, but coupled with the fact that it is difficult to reduce the size of turbofans, the cost of centrifugal fans has increased due to the recent economic situation such as soaring synthetic resin materials. There is a problem that reduction is not easy.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a centrifugal fan that achieves noise reduction during blowing, and that is reduced in size and cost.

  In order to achieve the above object, according to one aspect of the present invention, a casing composed of an upper plate having an opening and a motor base, and the upper plate and the motor base are housed between the suction port and the circumferential direction. An impeller having a plurality of blades arranged on the motor, a motor for rotating the impeller, and a circuit board on which electronic components are mounted, and through the suction opening from the opening of the upper plate as the impeller rotates. A centrifugal fan that can blow inhaled air toward the outside of the diameter of the impeller has a motor base made of a metal plate, and has a recess recessed downward and a diameter from the periphery of the recess. A flat portion extending outward and facing the lower surface of the impeller, the outer peripheral edge of the flat portion forms an air outlet, and the motor is attached to the bottom surface of the recess. A part of the insulator and the circuit board are recessed. Is housed inside the outer peripheral edge of the circuit board is close to the side of the recess.

  Preferably, the circuit board is attached to the lower part of the insulator.

  Preferably, an electronic component is mounted on the lower side of the circuit board.

  Preferably, the side surface of the recess has a tapered shape that tapers downward.

  Preferably, the air discharged toward the outside of the diameter of the impeller is blown out from an opening portion on a side portion of the casing except for a support portion provided between the upper plate and the motor base. It is configured.

  According to the above-described invention, it is possible to provide a centrifugal fan that achieves noise reduction during blowing and that is reduced in size and cost.

It is a perspective view which shows the centrifugal fan in one of the embodiments of this invention. FIG. 2 is a half sectional view of the centrifugal fan shown in FIG. 1. It is sectional drawing of the impeller shown in FIG. It is the figure which showed the measurement result of the noise of the centrifugal fan in embodiment of this invention. It is the figure which showed the static pressure-air volume characteristic in the centrifugal fan in embodiment of this invention. It is a top view which shows the conventional centrifugal fan. It is a perspective view which shows the impeller in the centrifugal fan shown in FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 is a perspective view showing a centrifugal fan according to one embodiment of the present invention, FIG. 2 is a half sectional view of the centrifugal fan shown in FIG. 1, and FIG. 3 is a view of the impeller shown in FIG. It is sectional drawing.

  1 to 3, the centrifugal fan 1 includes an impeller 3 in which a large number of blades 4 are arranged, and a casing 10 in which the impeller 3 is stored. The impeller 3 is rotationally driven by the motor 2.

  The impeller 3 has a configuration in which a large number of blades 4 are arranged at equal intervals in the circumferential direction, and one end side of these blades 4 is supported by an annular shroud 5. The main plate 121 shown in FIG. 5 is not provided on the other end side of the blade 4. The upper surface of the annular shroud 5 is formed with a predetermined curved surface, and a cylindrical portion 9 is formed at the center of the shroud 5. A suction port 8 is formed on the inner side of the cylindrical portion 9.

  The impeller 3 has a cup-shaped boss 6 at the center thereof. The blades 4 are curved with a predetermined curvature, and are all formed in the same shape. The blade 4 is a rearward blade, and has a blade shape curved and inclined backward with respect to the rotation direction, as in FIG. 6, and constitutes a turbofan. The blade 4, the annular shroud 5, and the boss portion 6 are integrally formed of synthetic resin. The rotor of the motor 2 is joined to the inside of the cup-shaped boss portion 6. As the motor 2 rotates, the impeller 3 rotates.

  The shape of the casing 10 is a quadrangle. The casing 10 includes a synthetic resin upper plate 11 having a circular opening formed in the center. Near the four corners of the upper plate 11, substantially cylindrical columns 13 are provided. A return portion 12 that protrudes downward is formed at the periphery of the opening of the upper plate 11. The cylindrical portion 9 of the shroud 5 is disposed inside the return portion 12 (on the rotating shaft side of the impeller 3) with a predetermined gap therebetween.

  A motor base 14 is disposed so as to face the upper plate 11. Four struts 13 are interposed between the upper plate 11 and the motor base 14. The upper plate 11 and the column 13 are coupled by a connecting material 28 (for example, a bolt, a screw, a rivet, etc.). The support 13 and the motor base 14 are coupled by a connecting member 28 (for example, a bolt, a screw, a rivet, etc.). The support 13 may be formed by integral molding with the upper plate 11, and the support 13 and the motor base 14 may be coupled by a connecting member 28.

  A portion surrounded by the adjacent columns, the upper plate 11, and the motor base 14 among the plurality of columns 13 is an opening. The opening serves as an air outlet.

  As described above, the four sides of the casing 10 of the centrifugal fan 1 according to the present embodiment have openings. That is, the side surface of the casing 10 has a configuration including only the support column 13 (a configuration in which an opening is formed except for a portion where the support column 13 exists).

  The outer diameter dimension of the impeller 3 accommodated in the casing 10 is set smaller than the dimension of one side of the casing 10. When the outer diameter dimension of the impeller 3 is larger than the dimension of one side of the casing 10, the rotating impeller 3 protrudes from the outer edge of the casing 10, and there is a risk of contact with other members or damage due to the contact. Absent. For this reason, it is preferable to set the outer diameter of the impeller 3 so as not to protrude from the outer edge of the casing 10.

  The motor 2 is an outer rotor type brushless motor. The rotor includes a cup-shaped rotor yoke 25, a ring-shaped magnet 27, and a shaft 7. The magnet 27 is fixed to the inner peripheral surface of the rotor yoke 25. The shaft 7 is fixed to a boss 26 formed at the center of the rotor yoke 25.

  The shaft 7 is rotatably supported by a pair of bearings 19 attached to a bearing holder 18. A laminated stator core 20 is mounted on the outer peripheral surface of the bearing holder 18. An insulator 22 around which a coil 21 is wound is attached to the stator core 20. The bearing holder 18 is attached to the motor base 14. The stator core 20 attached to the bearing holder 18 is disposed to face the magnet 27 with a predetermined gap in the radial direction (left-right direction in FIG. 2). The motor base 14 is formed by pressing a metal plate (for example, an iron plate). The shape of the motor base 14 is a quadrangle like the casing 10, and a recess 15 is formed at the center. The outer peripheral edge is bent in the axial direction (vertical direction in FIG. 2) to constitute the side plate 16. By forming the side plate 16, the rigidity of the motor base 14 can be improved. An opening is formed in the center of the recess 15 of the motor base 14, and a bearing holder 18 is attached to the opening, and the motor 2 is accommodated in the recess 15.

  The blades 4 of the impeller 3 joined to the rotor yoke 25 are disposed to face the flat portion 17 of the motor base 14 with a predetermined gap length G in the axial direction (vertical direction in FIG. 2). In other words, the impeller 3 includes a plurality of blades 4, and at least a part of the lower portion of each blade 4 is exposed to the plane portion 17 side of the motor base 14. Each blade 4 may be exposed at the lower portion of the motor base 14 on the entire flat portion 17 side. A PCB substrate 23 is attached to the lower surface of the insulator 22. An electronic component 24 for controlling the motor 2 is mounted on the PBC board 23.

  When the impeller 3 is rotated by driving the motor 2, the air sucked from the suction port 8 passes between the blades 4 of the impeller 3, and the impeller is caused by the fluid force due to the centrifugal action accompanying the rotation of the impeller 3. 3 is blown out toward the outer diameter.

  The motor base 14 also functions as a main plate 121 of the conventional impeller 120 shown in FIG. 7 and also functions as a lower plate of the casing 10. For this reason, the setting of the gap length G formed between the impeller 3 and the flat portion 17 of the motor base 14 is important. When the gap length G is too large, the air sucked from the suction port 8 passes between the blades 4 and also flows into the gap. As a result, the pressure of the air blown out from the impeller 3 is reduced, and the blowing characteristics are deteriorated. On the other hand, when the gap length G is too small, there is a possibility that the blades 4 of the impeller 3 may come into contact with the flat portion 17 of the motor base 14 when the dimensional accuracy of each component varies. In order to prevent such contact, it is necessary to manage the dimensional accuracy of each component with high accuracy, and as a result, the cost of the centrifugal fan 1 increases.

  As described above, the gap length G is an important factor affecting the air blowing characteristics of the centrifugal fan. Specifically, the gap length G is set in consideration of the air blowing characteristics and cost of the centrifugal fan.

  FIG. 4 is a diagram showing measurement results of noise between the centrifugal fan according to the embodiment of the present invention and a centrifugal fan having a conventional spiral casing.

  "Comparative example 1" in FIG. 4 shows a centrifugal fan provided with a conventional spiral casing. “Comparative example 2” uses a casing whose outer shape is a square and all sides have openings as in the centrifugal fan according to the present embodiment, but the structure of the impeller is different from that of the present embodiment. is there. The impeller in “Comparative Example 2” has a structure including an annular shroud on one end side of the blade and a main plate (as indicated by reference numeral 121 in FIG. 7) on the other end side of the blade. In “Comparative Example 2”, since the main plate is provided, it is not necessary for the motor base to also function as the main plate. For this reason, in “Comparative Example 2”, the gap G for making the motor base also function as the main plate as shown in FIG. 2 is not provided (the interval between the lower side of the blade and the main plate is 0 mm). Become). “Embodiment” in FIG. 4 is the centrifugal fan described in FIGS. 1 to 3, and the gap length G between the impeller 3 and the flat portion 17 of the motor base 14 is set to 0.5 mm. It is.

  As shown in FIG. 4, the noise in the centrifugal fan having the conventional spiral casing is 61 dB (A), whereas in Comparative Example 2, the noise is 57.3 dB (A), and in the centrifugal fan according to the present embodiment, the noise is 58 dB. (A). Thus, according to the present embodiment, noise can be suppressed.

  FIG. 5 shows a gap between the impeller 3 and the flat portion 17 of the motor base 14 using a casing (a casing shown in FIG. 1) whose outer shape is a quadrangle and whose side surfaces are all open in this embodiment. It is a figure which shows the static pressure-air volume characteristic in case the length G (refer FIG. 2) is 1 mm, 0.5 mm, and 0 mm (no gap). In the figure, the horizontal axis indicates the flow rate, and the vertical axis indicates the pressure.

  A gap length G of 0 mm (no gap) means that an impeller having an annular shroud on one end side of a blade and a main plate (as indicated by reference numeral 121 in FIG. 7) on the other end side of the blade. The case where it is used is shown.

  As shown in FIG. 5, it can be seen that the maximum static pressure decreases as the gap length G between the impeller 3 and the flat portion 17 of the motor base 14 increases. When the gap length G is 1 mm, the maximum static pressure is reduced by about 25% compared to the case without a gap. It can also be seen that when the gap length G is 0.5 mm, the maximum static pressure is slightly lower than when there is no gap, but a static pressure-air volume characteristic substantially equivalent to that without a gap is obtained.

  From the static pressure-air flow characteristics shown in FIG. 5, by setting the gap length G between the impeller 3 and the flat portion 17 of the motor base 14 to 0.5 mm or less, the static pressure-air flow characteristics are such that the gap length G is It can be seen that the characteristics approach 0 mm (no gap).

  That is, it is necessary to appropriately control the gap length G between the impeller 3 and the flat portion 17 of the motor base 14. By setting the gap length G to 0.5 mm or less, even if the main plate of the impeller 3 is omitted, characteristics almost equivalent to the static pressure-air volume characteristics when the gap length G is 0 mm (no gap) can be obtained. .

  [Effects of the embodiment]

  As described above, the centrifugal fan according to the present embodiment stores the impeller in which a large number of blades are arranged in the circumferential direction in the casing, and impellers the air sucked from the suction port as the motor rotates. The centrifugal fan is configured to be ejected toward the outside of the diameter of the impeller by a centrifugal force accompanying the rotation of the fan and ejected from the casing. The casing includes an upper plate, a lower plate, and a plurality of support columns. The upper plate and the lower plate sandwich a plurality of columns. A side surface of the casing includes only a support column to form an opening. The lower plate of the casing is composed of a motor base on which a motor is mounted. The impeller includes an annular shroud and a plurality of blades formed integrally with the shroud. The motor base is arranged to face the plurality of blades with a predetermined gap in the axial direction.

  According to the centrifugal fan in the present embodiment, the impeller of the centrifugal fan is housed in a casing in which an upper plate and a lower plate are connected by a support column. The casing does not have a side wall like the fan of FIG. 6, and the side wall is an opening. For this reason, the air ejected toward the outer diameter of the impeller is not disturbed by the side wall of the casing. That is, by improving the casing shape, it is possible to provide a centrifugal fan that can significantly suppress noise due to air turbulence during blowing.

  That is, the centrifugal fan according to the present embodiment employs a casing having a quadrangular outer shape and having four openings on the side surfaces, and provided only with support columns on the side surfaces, instead of the conventional spiral casing. Since the casing does not have a side wall, the noise of the fan can be reduced and the centrifugal fan can be downsized.

  In addition, since the casing can be formed to have substantially the same outer diameter as the impeller, a centrifugal fan that can be reduced in diameter compared with a centrifugal fan that uses a conventional spiral casing is provided. it can.

  Further, the main plate of the impeller 3 and the lower plate of the casing 10 formed of synthetic resin are abolished, and the lower plate of the casing 10 is combined with the main plate of the impeller 3 by an inexpensive metal motor base 14. ing. As a result of reducing the number of parts made of synthetic resin, the cost of the centrifugal fan 1 can be greatly reduced. As a specific example, iron is used as the metal of the motor base 14.

  In the present embodiment, the casing 10 is formed in a regular square, but the present invention is not limited to this. The casing 10 may have any arbitrary shape including a polygon, a circle, and an asymmetric shape. The support column 13 is not limited to the structure arranged on the inner side from the outer peripheral edge of the upper plate 11 of the casing 10, and the support column 13 is provided at a location protruding from the outer peripheral edge of the upper plate 11 in a radially outward manner. It may be a structure.

  Moreover, if the shape of the support | pillar 13 is a substantially cylindrical shape which has a magnitude | size which can insert the connection material 28, the air which blown off from the impeller 3 will receive outward from the side surface of the casing 10 hardly receiving resistance. Can be blown out. Such a shape of the support 13 can reduce noise.

  The above-described embodiment is to be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1 Centrifugal fan 2 Motor 3 Impeller 4 Blade 5 Shroud 6 Boss part 7 Shaft 8 Suction port 9 Cylindrical part 10 Casing 11 Upper plate 12 Return part 13 Support | pillar 14 Motor base 15 Recess 16 Side plate 17 Flat part 18 Bearing holder 19 Bearing 20 Stator core 21 Coil 22 Insulator 23 PCB substrate 24 Electronic component 25 Rotor yoke 26 Boss portion 27 Magnet 28 Connecting material

The present invention aims at providing a centrifugal fan downsized.

In order to achieve the above object, according to one aspect of the present invention, the centrifugal fan is made of metal, and has a motor base having a recessed portion that is recessed downward, and is located above the motor base , in the suction port and in the circumferential direction. An impeller having a plurality of blades arranged, a motor that is attached to the bottom surface of the recess and rotates the impeller, and a circuit board that is housed in the recess and on which electronic components are mounted ; The outer peripheral edge of the substrate is close to the side surface of the recess, and blows out the air sucked through the suction port toward the outside of the diameter of the impeller as the impeller rotates .

Preferably, the circuit board is attached to the lower part of the insulator of the motor .

According to the invention, it is possible to provide a centrifugal fan downsized.

The above-described embodiment is to be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.
In addition, the turbo fan described in the above-mentioned patent document 1 is intended to suppress noise during blowing by examining the shape of the blade 123. However, since the casing tongue 129 is formed in the spiral casing 127, the noise generated when the air blown from the impeller 120 collides with the casing tongue 129 cannot be sufficiently reduced.
Moreover, in patent document 1, the air discharged from the outer periphery of the impeller 120 blows off from the blower outlet 141 along the inner wall surface of the spiral casing 127. For this reason, the air flow is likely to be disturbed near the inner wall surface of the spiral casing 127 and the vicinity of the outlet 141, and the disturbance of the air flow causes noise.
Furthermore, in recent years, centrifugal fans incorporated in blowers of home appliances, OA devices, vehicles and the like have been strongly demanded to reduce costs as well as to reduce noise and size.
However, in the spiral casing 127 as shown in FIG. 6, it is necessary to form a flow path for guiding air to the outlet on the outer periphery of the impeller 120. For this reason, the outer diameter of the spiral casing 127 usually requires about twice the outer diameter of the impeller 120. As a result, it is difficult to reduce the size of the turbofan. The spiral casing 127 and the impeller 120 are generally formed of synthetic resin, but coupled with the fact that it is difficult to reduce the size of turbofans, the cost of centrifugal fans has increased due to the recent economic situation such as soaring synthetic resin materials. There is a problem that reduction is not easy.
According to the above-described embodiment, it is possible to provide a centrifugal fan that achieves noise reduction at the time of blowing and that is reduced in size and cost.

Claims (5)

A casing composed of an upper plate having an opening and a motor base;
An impeller that is housed between the upper plate and the motor base, and includes a suction port and a plurality of blades arranged in a circumferential direction;
A motor for rotating the impeller;
A circuit board on which electronic components are mounted,
A centrifugal fan capable of blowing air sucked from the opening of the upper plate through the suction port toward the outside of the diameter of the impeller as the impeller rotates,
The motor base is made of a metal plate, and has a recessed portion that is recessed downward, and a flat portion that extends outward from the periphery of the recessed portion and faces the lower surface of the impeller, The outer peripheral edge of the flat portion constitutes an air outlet,
The motor is attached to the bottom surface of the recess,
A part of the insulator of the motor and the circuit board are housed in the recess,
A centrifugal fan in which an outer peripheral edge of the circuit board is close to a side surface of the recess.   The centrifugal fan according to claim 1, wherein the circuit board is attached to a lower portion of the insulator.   The centrifugal fan according to claim 1 or 2, wherein the electronic component is mounted on a lower side of the circuit board.   The centrifugal fan according to any one of claims 1 to 3, wherein the side surface of the concave portion has a tapered shape that tapers downward. The air discharged toward the outside of the diameter of the impeller is blown out from an opening portion on a side portion of the casing except for a support portion provided between the upper plate and the motor base. The centrifugal fan according to any one of claims 1 to 4, wherein the centrifugal fan is configured as follows.

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