JP6386990B2 - Centrifugal fan - Google Patents

Description

  The present invention relates to a centrifugal fan.

  Centrifugal fans are known as blowers that are widely used for cooling, ventilation, and air conditioning of home appliances, OA equipment, and industrial equipment, air conditioning for vehicles, and ventilation. As a conventional centrifugal fan, the casing consists of an upper casing and a lower casing. An impeller is accommodated between the upper casing and the lower casing, and the air sucked from the suction port as the impeller rotates is placed between the upper casing and the lower casing. There is known a structure that discharges outward from a blow-out port formed on the side surface (see, for example, Patent Document 1).

  FIG. 7 shows a centrifugal fan 100 described in Patent Document 1, in which a rectangular casing 120 includes an upper casing 121 and a lower casing 122, and an impeller 130 is accommodated between the upper casing 121 and the lower casing 122. The impeller 130 includes an annular shroud 131. The annular shroud 131 has a cylindrical portion 132 in the center. The outer periphery of the annular shroud 131 is warped from the cylindrical portion 132 toward the upper casing 121, and the annular shroud 131 extends from the end of the cylindrical portion 132 of the annular shroud 131. The upper surface shape is formed by a curved surface formed by connecting four circular arcs having different curvature radii, and the cross-sectional area of the air flow path to the outer peripheral portion of the annular shroud 131 is gradually increased. As a result, the pressure of the air is increased, and an air flow is blown outward from the outer peripheral portion of the impeller 130.

JP2012-207600A

  In the structure of FIG. 7, due to the high speed rotation of the impeller 130, the air sucked from the suction port 110 passes between the blades 135 and is blown outward from the outer periphery of the impeller 130. The air is discharged outward from a blow-out port 111 formed on the side surface therebetween. However, since the centrifugal fan 100 having this structure has a shape in which the outer periphery of the annular shroud 131 is warped toward the upper casing 121, a part of the air blown from the outer periphery of the impeller 130 is annular. There is a risk of backflow from the gap 125 between the shroud 131 and the upper casing 121 toward the suction port 110. When this reverse flow occurs, the flow of air is disturbed in the vicinity of the suction port 110 due to the reverse flow air, which causes noise.

  An object of the present invention is to provide a centrifugal fan capable of reducing noise by suppressing a part of air blown from an impeller from flowing backward in the centrifugal fan.

The invention according to claim 1 has a structure in which an impeller is rotatably held between an upper casing and a lower casing, and the impeller includes an annular shroud, a main plate, the shroud, and the main plate. The lower casing is configured by stacking a metal motor base and a resin base plate in the axial direction, and the upper casing is provided with a suction port. Between the lower surface of the outer peripheral end of the upper casing and the upper surface of the outer peripheral end of the base plate, there is provided a blow-out port for blowing out the air flow generated by the impeller in a radially outward direction, and the blow-out port extends from the horizontal direction to the axial direction. faces the direction of downward, the lower surface of the outer peripheral edge of the upper casing is formed in a curved surface curved in the direction of the lower casing toward the radially outer side, front The upper surface of the outer peripheral edge of the base plate of the lower casing is formed in a curved surface curved in a direction away from the upper casing toward the radially outer side, the outer peripheral end of the motor base portion of the curved surface of the outer peripheral edge of said base plate The centrifugal fan is characterized in that it is covered by an edge cover portion formed in the shape of extending in the axial direction.

According to a second aspect of the present invention, in the first aspect of the invention, the base plate has an opening, a step portion is formed by the opening and the motor base, and the step plate has a step portion formed on the main plate of the impeller. Since the outer peripheral side is positioned, the lower surface of the outer peripheral side of the main plate is disposed to face the motor base .

The invention according to claim 3 is the invention according to claim 1 or 2, wherein the motor base includes a lead wire outlet, and a lead wire outlet cover portion provided on the base plate is provided in the lead wire outlet. It is fitted .

  ADVANTAGE OF THE INVENTION According to this invention, in the centrifugal fan, the centrifugal fan which can suppress noise by suppressing that a part of air blown out from the impeller flows backward is provided.

It is a disassembled perspective view of the centrifugal fan of this invention. It is sectional drawing of the centrifugal fan shown in FIG. It is the elements on larger scale of the centrifugal fan shown in FIG. It is explanatory drawing which shows the flow of the air which blows off from the blower outlet in the centrifugal fan of this invention. It is a perspective view which shows the assembly condition of the lower casing of the centrifugal fan shown in FIG. It is a perspective view which shows the bottom face of the lower casing shown in FIG. It is a figure which shows the conventional centrifugal fan.

(1) Basic Structure of Centrifugal Fan FIGS. 1 and 2 show a centrifugal fan 1. The basic structure of the centrifugal fan 1 is substantially the same as the structure described in Patent Document 1. The centrifugal fan 1 includes a casing 2. The casing 2 includes an upper casing 3 and a lower casing 4, and an impeller 8 is accommodated between the upper casing 3 and the lower casing 4 in a rotatable state. The air sucked in the axial direction (the lower direction in FIGS. 1 to 3) from the suction port 35 along with the rotation of the impeller 8 passes between the blades 10 and is interposed between the upper casing 3 and the lower casing 4. The air is discharged from the blow-out port 36 formed on the side surface excluding the support column 7 toward the outside (radially outward direction) of the casing 2.

  The impeller 8 is driven to rotate by a motor 21 which is an outer rotor type brushless DC motor. The motor 21 is mounted on the bottom surface of the recess 5 a formed in the motor base 5. A circuit board 30 on which an electronic circuit for driving the motor 21 is mounted is mounted on the lower insulator 24 b of the motor 21. The circuit board 30 and the electronic component 31 on the circuit board 30 are also accommodated in the recess 5a.

  The motor 21 includes a stator 22. The stator 22 includes a stator core 23 formed by stacking a predetermined number of cores, a resin insulator 24 including an upper insulator 24 a and a lower insulator 24 b mounted from both axial sides of the stator core 23, and the stator core 23 via the insulator 24. The coil 25 is wound around the teeth. The core includes a plurality of teeth (in this example, having six teeth) extending radially outward from the annular yoke, and the stator core 23 is configured by stacking the cores.

  The stator 22 is disposed outside the bearing holding portion 26. That is, the stator 22 is disposed outside the bearing holding portion 26 by fitting the bearing holding portion 26 into an opening formed in the center of the stator core 23. Bearings 27 and 28 are mounted inside the bearing holding portion 26, and the bearings 27 and 28 support the shaft 16 in a rotatable state.

  A rotor 15 is coupled to the center of the impeller 8. The rotor 15 includes a shaft 16, a boss portion 17 attached to the shaft 16, a cup-shaped rotor yoke 18 attached to the boss portion 17, and an annular magnet 19 fixed to the inside of the rotor yoke 18. Yes. The rotor yoke 18 is caulked and fixed to the boss portion 17.

  The impeller 8 includes an annular shroud 9, a plurality of blades 10, and a main plate 11, and the blades 10 and the main plate 11 are formed by integral molding of resin. The blade 10 is erected from the main plate 11 in the axial direction, has a shape that is curved and inclined backward with respect to the rotation direction, and is a backward blade (so-called turbo type) with respect to the rotation direction. All the blades 10 have the same shape. The blade 10 and the annular shroud 9 are joined by ultrasonic welding.

  The main plate 11 of the impeller 8 has an inclined surface 11a between the inner peripheral side and the outer peripheral side. That is, the inner peripheral side of the impeller 8 is positioned upward in the axial direction, the outer peripheral side of the impeller 8 is positioned lower in the axial direction, and the inclined surface 11a is provided between the inner peripheral side and the outer peripheral side.

  The impeller 8 and the rotor 15 are coupled as follows. First, the annular flange 20 is welded to the outer peripheral surface of the rotor yoke 18 by, for example, resistance welding. On the other hand, a pin (not shown) formed by integral molding is provided on the lower surface on the inner peripheral side of the main plate 11, this pin is fitted into a through hole formed in the flange 20, and the tip of the pin is crushed by heat. The two plates are joined together by heat caulking, and the main plate 11 is fixed to the rotor yoke 18. Thus, the impeller 8 is attached to the rotor 15.

  A plurality of concave portions 3a (meat stealing portions) are formed on the upper surface side of the upper casing 3, and a flange portion 40 extending radially outward is formed on the outer periphery of the upper casing 3, and the flange portion 40 has a shaft. A column 7 projecting downward in the direction is integrally formed. The upper casing 3, the flange portion 40, and the support column 7 are integrally formed by resin injection molding. The upper casing 3 and the lower casing 4 are coupled by interposing a support 7 between the upper casing 3 and the lower casing 4 and fastening the support 7 with a fastening material such as a screw. In this example, the upper casing 3 and the lower casing 4 are coupled by tightening a tapping screw 29 having through holes 5 e and 6 e passing through a prepared hole formed in the support column 7. The fastening means is not limited to this. For example, a configuration may be adopted in which screws (or bolts) are inserted into the through holes of the support column 7 from the lower casing 4 side and fixed with nuts from the upper casing 3 side.

  The lower casing 4 includes a motor base 5 made of metal (for example, an iron plate) and a base plate 6 made of resin, and the lower casing 4 is formed by superimposing both. An edge cover portion 6 a extending downward is formed at the outer peripheral end of the base plate 6, and the outer peripheral end of the motor base 5 contacts the inside of the edge cover portion 6 a.

  As described above, the centrifugal fan 1 has a structure in which the impeller 8 is rotatably held between the upper casing 3 and the lower casing 4, and the lower casing 4 includes the motor base 5 and the base plate 6. The lower surface 3b of the outer peripheral end of the upper casing 3 is formed in a curved surface having an arc shape in cross section, and the upper surface 6b of the outer peripheral end of the base plate 6 is formed in a curved surface having an arc shape in cross section. Between the lower surface 3b of the outer peripheral end of the base plate 6 and the upper surface 6b of the outer peripheral end of the base plate 6, there is provided a blow-out port 36 for blowing out the air flow generated by the impeller 8 in the radially outward direction. 6 by the edge cover portion 6a having a shape extending in the axial direction at the tip (side toward the edge) of the portion (the portion denoted by reference numeral 6b) formed on the arcuate curved surface at the outer peripheral end of Are we.

  Here, the lower surface 3b of the outer peripheral end of the upper casing 3 is formed in a curved surface that curves in the direction of the lower casing 4 as it goes radially outward, and the upper surface 6b of the outer peripheral end of the base plate 6 of the lower casing 4 goes radially outward. Accordingly, a curved surface bent in a direction away from the upper casing 3 is formed. According to this structure, the airflow toward the outside of the diameter is forced to be directed downward in FIG. 4 and is blown out in the flow path indicated by reference numeral 37.

(2) Features of the invention (2) -1. About the reduction of noise The outer diameter of the base plate 6 of the upper casing 3 and the lower casing 4 is larger than the outer diameter of the impeller 8. As shown in FIG. 4, the lower surface 3 b of the outer peripheral end of the upper casing 3 is formed in a curved surface having a circular arc cross section. Moreover, the upper surface 6b of the outer peripheral end of the base plate 6 of the lower casing 4 is formed in a curved surface having a circular arc cross section. For this reason, the air blown out from the outer peripheral end of the impeller 8 in the radially outward direction is directed outward from the casing 2 from the space serving as the air outlet 36 formed between the upper casing 3 and the base plate 6 of the lower casing 4. When blown out, the blown-out direction is blown downward in the axial direction, and then the direction is changed slightly upward and blown in the horizontal direction. In FIG. 4, the flow of the airflow at this time is indicated by reference numeral 37. Thus, the blowout port 36 faces in the direction between the horizontal direction and the downward direction (the direction from the upper casing 3 toward the lower casing 4), and the direction blown out from the blowout port 36 is downward in the axial direction. In addition, it is possible to suppress the air flowing backward from the gap 3c between the upper casing 3 and the annular shroud 9 to the suction port 35 side. As a result, noise can be reduced.

FIG. 3 shows a cut surface including the rotating shaft. As shown in FIG. 3 , the upper end of the cylindrical portion that forms the opening serving as the suction port 35 of the annular shroud 9 constitutes an annular protrusion 9 a that extends in the axial direction, and this protrusion 9 a is the upper casing 3. Located in the annular groove 3d. According to this structure, the upper casing 3 has a shape covering the upper end of the cylindrical portion of the annular shroud 9. For this reason, even if the air from the outer peripheral edge of the impeller 8 flows backward, the backward flow entering the suction port 35 can be suppressed by the resistance at this location.

(2) -2. Others The metal motor base 5 and the resin base plate 6 constituting the lower casing 4 are formed separately. Since the metal motor base 5 is formed by pressing, burrs may appear on the cut surface. When the motor base 5 is held by hand, there is a risk that the finger may be injured by touching the burr on the cut surface, which may hinder the work. For this reason, the cut surface of the motor base 5 is configured to be covered by an edge cover portion 6 a formed on the base plate 6. Further, the lead wire outlet port cover portion 6c formed on the base plate 6 is fitted to the lead wire outlet port 5c of the motor base 5, and the edge of the lead wire outlet port 5c is protected by the lead wire outlet port cover portion 6c. . As a result, even if there is a burr on the cut surface of the motor base 5, injury is prevented. Further, damage to the coating film of the lead wire (not shown) is also prevented.

  The metal motor base 5 and the resin base plate 6 constituting the lower casing 4 are formed separately. However, the motor base 5 may be formed by insert molding and the base plate 6 may be integrally molded. .

DESCRIPTION OF SYMBOLS 1 ... Centrifugal fan, 2 ... Casing, 3 ... Upper casing, 3a ... Recessed part, 3b ... Lower surface of outer peripheral end, 3c ... Gap, 3d ... Annular groove, 4 ... Lower casing, 5 ... Motor base, 5a ... Recessed part, 6 ... Base plate, 6a ... edge cover part, 6b ... upper surface of outer peripheral edge, 7 ... column, 8 ... impeller, 9 ... annular shroud, 9a ... projection, 10 ... blade, 11 ... main plate, 11a ... inclined surface, 15 ... rotor , 16 ... shaft, 17 ... boss, 18 ... rotor yoke, 19 ... magnet, 20 ... flange, 21 ... motor, 22 ... stator, 23 ... stator core, 24 ... insulator, 24a ... upper insulator, 24b ... lower insulator, 25 ... Coil, 26 ... Bearing holding portion, 27 ... Bearing, 28 ... Bearing, 30 ... Circuit board, 31 ... Electronic component, 35 ... Suction port, 36 ... Air outlet, 37 ... Air Of flow, 40 ... flange portion.

Claims (3)

The impeller is rotatably held between the upper casing and the lower casing,
The impeller is composed of an annular shroud, a main plate, and a plurality of blades disposed between the shroud and the main plate,
The lower casing is configured by overlapping a metal motor base and a resin base plate in the axial direction,
The upper casing is provided with a suction port,
Between the lower surface of the outer peripheral end of the upper casing and the upper surface of the outer peripheral end of the base plate, a blowout port for blowing out the air flow generated by the impeller in a radially outward direction is provided,
The outlet is directed from the horizontal direction to the axially lower direction,
The lower surface of the outer peripheral end of the upper casing is formed in a curved surface that is bent in the direction of the lower casing as it goes radially outward,
The upper surface of the outer peripheral end of the base plate of the lower casing is formed into a curved surface that is bent in a direction away from the upper casing as it goes radially outward,
It said motor base of the outer peripheral end, a centrifugal fan characterized in that it is covered by the edge cover of the shape extending in the axial direction formed in portions of the curved surface of the outer peripheral edge of said base plate. The base plate has an opening, and a step portion is formed by the opening and the motor base, and the outer peripheral side of the main plate of the impeller is positioned at the step portion so that the lower surface of the outer peripheral side of the main plate is the motor. The centrifugal fan according to claim 1, wherein the centrifugal fan is disposed to face the base . The centrifugal fan according to claim 1 or 2, wherein the motor base includes a lead wire outlet, and a lead wire outlet cover portion provided in the base plate is fitted to the lead wire outlet. .

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