JP2016102469A - Centrifugal fan - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a centrifugal fan capable of being thinned and reducing noise.SOLUTION: A centrifugal fan 100 discharges air sucked from a suction port 136 in accompany with rotation of an impeller 140, outward from a blowout port, an annular recessed portion 133 is formed on an outer peripheral portion of a boss portion 131a, a peripheral edge portion of an opening forming a suction port of an annular shroud 141 is disposed in the recessed portion 133 of an upper casing 131, and a clearance between the upper casing 131 and the annular shroud 141 has a throttled constitution to be gradually narrowed toward the suction port 136. An annular projection portion 141c is formed on an inclined face 142a of the annular shroud 141, and has a relationship of L1>L3>L2≥L4, L5≥1.5*L3. An axial dimension between the annular shroud 141 and a main plate 13 is gradually increased from an outermost peripheral edge of a blade toward an outer peripheral edge of the impeller 140, and has a relationship of a diameter of a circle passing an outer diameter of the outer peripheral edge of the impeller 140>the outermost peripheral edge of the blade.SELECTED DRAWING: Figure 3

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, a casing is composed of an upper casing and a lower casing. An impeller is accommodated between the upper casing and the lower casing, and air sucked from the suction port as the impeller rotates is moved to the lower casing. There is known a centrifugal fan that discharges outward from a blowout port formed on a side surface between casings (see, for example, Patent Document 1).

JP 2014-15849 A

  The centrifugal fan described in Patent Document 1 eliminates the main plate of the impeller by a configuration in which the lower casing also functions as the main plate of the impeller, and stores a motor and a circuit board in a recess formed in the lower casing. . As a result, the size of the upper part of the lower casing can be reduced.

  However, when the total height of the centrifugal fan is specified due to restrictions on the installation space for equipment and devices, it is necessary to provide space so that electronic components such as control ICs mounted on the circuit board do not touch the lower surface of the impeller. However, it cannot always meet the demand for thinning.

  Since the upper shroud constituting the impeller rotates inside the opening of the upper casing, the diameter of the opening of the upper casing is slightly larger than the outer diameter of the portion constituting the suction port of the upper shroud. For this reason, a slight gap is formed between the opening of the upper casing and the portion constituting the suction port of the upper shroud. When the impeller rotates at high speed, air is sucked from the suction port, and the pressure of the sucked air is increased and discharged. For this reason, an air pressure difference occurs in the vicinity of the suction port, and a phenomenon occurs in which air flows backward from the gap formed between the opening of the upper casing and the portion constituting the suction port of the upper shroud toward the suction port. This reverse flow may cause turbulence in the air flow near the suction port, resulting in vortices. The generation of such vortices causes noise.

  The present invention has been made in view of such a problem, and an object thereof is to provide a centrifugal fan that can be reduced in thickness and reduced in noise.

In order to solve the above problems, (1) a centrifugal fan of the present invention includes an impeller and a casing having an upper casing and a lower casing, and the impeller is accommodated between the upper casing and the lower casing. Then, the air sucked from the suction port with the rotation of the impeller rotated by the motor is moved outward from the blowout port formed on the side surface excluding the support column interposed between the upper casing and the lower casing. A centrifugal fan that discharges toward the bottom, wherein the motor is mounted on a bottom surface of a recess formed in the lower casing, and the impeller includes an annular shroud, a plurality of blades, a main plate, and a hub, Arranged between the annular shroud and the main plate, an annular groove is formed on the bottom surface of the main plate, and a part of the electronic component mounted on the circuit board is accommodated in the annular groove, A boss portion extending downward is formed at the periphery of the opening of the above casing, an annular recess is formed at the outer periphery of the boss, and the periphery of the opening forming the suction port of the annular shroud is Arranged in the concave portion of the casing and narrowed so that the gap between the upper casing and the annular shroud becomes narrower toward the suction port, and an annular convex portion is formed on the inclined surface of the annular shroud. And have the following relationship:
L1>L3> L2 ≧ L4
L5 ≧ 1.5 * L3
(Here, L1 is a gap between the annular shroud and the upper casing, L2 is a gap between the convex portion of the annular shroud and the upper casing, and L3 is an upper end of the peripheral edge of the opening of the annular shroud. L4 is a radial gap between the peripheral edge of the opening of the annular shroud and the concave part of the upper casing, and L5 is a peripheral edge of the opening of the annular shroud. And the length of the concave portion of the upper casing facing each other)
The axial dimension between the annular shroud and the main plate gradually increases from the outermost peripheral edge of the blade toward the outer peripheral edge of the impeller, and the outer diameter of the outer peripheral edge of the impeller> the outermost peripheral edge of the blade. It has the relationship of the diameter of the passing circle.

(2) In the above (1), the inner diameter side of the blade has an inclined surface that is not exposed to the suction port side and is inclined on the outer peripheral side of the blade, and the inclined surface is formed by a quadratic function. Have

(3) In the above (1) or (2), the annular shroud and the plurality of blades are integrally formed by resin injection molding.

  ADVANTAGE OF THE INVENTION According to this invention, while aiming at thickness reduction, the centrifugal fan which can reduce noise can be provided.

It is sectional drawing which shows the centrifugal fan which concerns on embodiment of this invention. It is an expanded partial sectional view of the centrifugal fan shown in FIG. It is explanatory drawing for demonstrating a part of suction port shown in FIG. It is a top view of the centrifugal fan shown in FIG.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention (hereinafter referred to as embodiments) will be described in detail with reference to the accompanying drawings. Note that the same number is assigned to the same element throughout the description of the embodiment.

  FIG. 1 is a cross-sectional view showing a centrifugal fan according to an embodiment of the present invention. FIG. 2 is an enlarged partial sectional view of the centrifugal fan shown in FIG. FIG. 3 is an explanatory diagram for explaining a part of the suction port shown in FIG. FIG. 4 is a plan view of the centrifugal fan shown in FIG.

(Basic structure of centrifugal fan)
The basic structure of the centrifugal fan 100 is substantially the same as the structure described in Patent Document 1 (Japanese Patent Application Laid-Open No. 2014-15849), and the casing 130 includes an upper casing 131 and a lower casing 132. The upper casing 131 and the lower casing The impeller 140 is accommodated between 132 and the air sucked from the suction port 136 as the impeller 140 rotates is formed on the side surface excluding the support column 139 interposed between the upper casing 131 and the lower casing 132. This is a centrifugal fan that discharges outward from the blowout port 137.

  The motor 110 is mounted on the bottom surface 134 of the recess 133 formed in the lower casing 132, and the circuit board 125 mounted on the lower insulator 123 of the motor 110 is also housed in the recess 133. The motor 110 is an outer rotor type brushless DC motor. A pair of bearings 114 and 115 are mounted inside the bearing holding portion 113 and rotatably support the shaft 117 constituting the rotor 112. Reference numeral 127 denotes an E-shaped retaining ring attached to the shaft 117. A stator 111 is disposed outside the bearing holding portion 113.

  The stator 111 includes a stator core 120 formed by laminating a predetermined number of cores, an insulator 121 including an upper insulator 122 and a lower insulator 123 mounted from both axial sides of the stator core 120, and each salient pole of the stator core 120 via the insulator 121. And a coil 124 wound around. The core includes a plurality of salient poles extending radially outward from the annular yoke, and has pole teeth extending in the circumferential direction at the tip of the salient pole. The stator core 120 is configured by stacking these cores. The bearing holding portion 113 is fitted into an opening formed at the center of the annular yoke of the stator core 120, and the stator 111 is disposed outside the bearing holding portion 113.

  The rotor 112 includes a shaft 117, a cup-shaped rotor yoke 118 attached to the shaft 117, and an annular magnet 119 fixed to the inside of the rotor yoke 118. The outer peripheral surface of the stator core 120 is disposed to face the inner peripheral surface of the magnet 119 with a predetermined air gap therebetween. A circuit board 125 is attached to the lower insulator 123. A flange 116 is provided on the lower end side of the bearing holding portion 113, and is fastened to the bottom surface 134 of the concave portion 133 formed in the lower casing 132 by three fastening materials 151 such as screws.

  The impeller 140 includes an annular shroud 141, a plurality of blades 142, a main plate 143, and a hub 144, and the annular shroud 141 and the blades 142 are formed by integral molding. The main plate 143 and the hub 144 are formed by integral molding. These are molded by injection molding with resin. Then, the lower end of the blade 142 is fitted into the recess formed in the main plate 143, and a plurality of pins formed at the time of integral molding are fitted into the lower end of the blade 142 in the holes formed in the recess, respectively, and each pin is heat caulked. It is joined with. In addition, it is not limited to a heat caulking, A means by ultrasonic welding may be sufficient and a means will not be ask | required if it is a means which has joining strength.

  The blade 142 is a shape that extends in the axial direction from one surface of the annular shroud 141, has a curved shape, is the same shape, and is a backward blade that is curved and inclined backward with respect to the rotation direction (so-called Turbo type). The main plate 143 has a substantially disk shape extending in the radial direction from the outer peripheral surface of the cup-shaped hub 144. The rotor yoke 118 of the motor 110 is fitted inside the cup-shaped hub 144, and a plurality of bosses 145 formed on the hub 144 are fitted into a plurality of through holes formed on the bottom surface of the cup-shaped rotor yoke 118, respectively. Both ends are joined by heat caulking, and the impeller 140 is mounted on the rotor 112. An annular groove 146 (concave portion) is formed on the bottom surface of the main plate 143 (the surface facing the lower casing 132).

  Further, the inner diameter side (the front edge on the air inlet side) of the blade 142 is not exposed to the suction port 136 side as in the prior art, and has an inclined surface 142a inclined to the outer peripheral side of the blade 142 (suction). Inclined in a direction along the flow of air sucked from the mouth 136). The inner diameter side (front edge on the air inlet side) of the blade 142 has a shape formed by a quadratic function (so-called parabola).

  A boss 131a extending downward is formed on the periphery of the opening of the upper casing 131, and an annular recess 131b is formed on the outer periphery thereof. The peripheral edge portion 141a of the opening forming the suction port 136 of the annular shroud 141 constituting the impeller 140 is disposed in the recess 131b of the upper casing 131, and the opening of the upper casing 131 is formed in a bell mouth shape. For this reason, since the boss 131a extending downward at the peripheral edge of the opening of the upper casing 131 is positioned inside the peripheral edge 141a of the opening that forms the suction port 136 of the annular shroud 141 and rotates, It is possible to suppress a backflow from occurring between the upper casing and the annular shroud. An annular convex portion 141 c is formed on the slope of the annular shroud 141, and a gap L <b> 2 is formed between the annular convex portion 141 c and the slope of the upper casing 131.

  The relationship between the gaps of the respective parts between the upper casing 131 and the annular shroud 141 is that the gap L1 between the annular shroud 141 and the upper casing 131> the upper end of the peripheral edge 141a of the opening of the annular shroud 141 and the recess 131b of the upper casing 131. A gap L3 between the convex portion 141c of the annular shroud 141 and the upper casing 131 and a radial direction between the peripheral edge portion 141a of the opening of the annular shroud 141 and the concave portion 131b of the upper casing 131. The gap between the upper casing 131 and the annular shroud 141 is narrowed and narrowed from the outer peripheral side of the annular shroud 141 toward the suction port 136.

  Due to the high-speed rotation of the impeller 140, the pressure at the suction port 136 decreases, and the gap between the upper casing 131 and the annular shroud 141 is directed from the outer periphery side of the annular shroud 141 toward the suction port 136 as shown in FIG. As shown by the arrows, a flow occurs (back flow). Since this flow becomes narrower at the position of the gap L2 than the gap L1, the resistance when passing through the gap L2 is increased and the flow is blocked. The space between the gap L2 and the gap L3 is increased. For this reason, when passing through the gap L2, a part of the flow is divided to become a vortex and swirls as indicated by an arrow, and the flow rate as a reverse flow is significantly suppressed by this vortex. Further, since the gap L3 and the gap L4 exist and become narrower at the gap L4 than the gap L3, the resistance when passing through the gap L3 and the gap L4 is further increased and the flow is blocked. . The radial gap L4 is set to be the narrowest. Further, the length L5 of the opening 141 of the annular shroud 141 facing the recess 131b of the upper casing 131 is the axial direction between the upper end of the opening 141a of the annular shroud 141 and the recess 131b of the upper casing 131. The gap L3 is set to 1.5 times or more. For example, in this embodiment, L2 = 0.3 mm, L3 = 1 mm, and L4 = 0.3 mm are set. If the length L5 is smaller than 1.5 * L3, the effect cannot be expected.

  In this way, the backward flow toward the suction port 136 is suppressed by the configuration in which the gap between the upper casing 131 and the annular shroud 141 is gradually narrowed toward the suction port 136, and as a result, noise is reduced.

  The air sucked from the suction port 136 of the impeller 140 does not directly collide with the inner diameter side of the blade 142 (the front edge on the air inlet side), so that the air flow is not disturbed near the suction port 136. . For this reason, the noise in the location of the suction inlet 136 can be suppressed. Then, after being guided into the impeller 140 and passing between the blades 142, the outer peripheral edge of the impeller 140 is blown outward from between the annular shroud 141 and the main plate 143. The axial dimension between the annular shroud 141 and the main plate 143 gradually increases from the outermost peripheral edge of the blade 142 toward the outer peripheral edge of the impeller 140. In other words, it spreads in a trumpet shape. Further, the impeller 140 (the outer diameter of the annular shroud 141 and the main plate 143) is formed to be larger than the outer diameter (diameter) of a circle passing through the outermost peripheral edge of the blade 142. For this reason, the air blown from the outer peripheral edge of the blade 142 spreads in accordance with the shape of the outer peripheral edge of the impeller 140 and spreads in accordance with the shape of the impeller 140, and the air flow is disturbed near the outlet 137. Absent. For this reason, the noise in the location of the blower outlet 137 can be suppressed.

  Components for driving and controlling the motor 110 and electronic components 126 such as a control IC are mounted on the circuit board 125. Therefore, in order to prevent interference (contact) between the electronic component 126 and the impeller 140 in a limited space, an annular groove 146 (concave portion) is formed on the bottom surface of the main plate 143 (the surface facing the lower casing 132). Has been. Since a part of the electronic component 126 is accommodated in the annular groove 146 (concave portion), interference (contact) between the electronic component 126 and the impeller 140 is prevented and the thickness is reduced.

A plurality of recesses 138 (meat stealing portions) are formed on the upper surface side of the upper casing 131. The upper casing 131 and the lower casing 132 are joined by interposing a support column 139 between the upper casing 131 and the lower casing 132 and fastening the support column 139 with a fastening material 150 such as a screw. Specifically, the support column 139 is formed by integral molding with the upper casing 131, and is fastened by tightening a tapping screw into a prepared hole formed in the support column 139. The fastening means is not limited to this. For example, a configuration in which a screw (or bolt) is inserted into the through hole of the support column 139 from the lower casing 132 side and fixed with a nut from the upper casing 131 side is also possible. The outer peripheral portion of the lower casing 132 is a side plate 135 bent in the axial direction. By providing the side plate 135, the rigidity of the lower casing 132 can be increased. The shape of the casing 130 is not limited to a quadrangle, and may be a circle, for example.
Reference numerals 141b, 143a, and 144a denote annular grooves for mounting the balance adjusting weight of the impeller 140. In addition, each annular groove is not limited to this shape, Of course, the structure which has arrange | positioned several recessed part on the same periphery may be sufficient.

(About features of the invention)
Components for driving and controlling the motor 110 and electronic components 126 such as a control IC are mounted on the circuit board 125. For this reason, in order to prevent the interference (contact) between the electronic component 126 mounted on the circuit board 125 and the impeller 140 in a limited space, the bottom surface of the main plate 143 (the surface facing the lower casing 132) is annular. The groove 146 (concave portion) is formed. Since a part of the electronic component 126 is accommodated in the annular groove 146 (concave portion), interference (contact) between the electronic component 126 and the impeller 140 is prevented and the thickness is reduced.

  A main plate 143 is provided on the lower surface of the blade 142, and the conventional lower casing does not have a configuration in which the main plate of the impeller is also used. For this reason, even when the lower casing 132 is manufactured by a press, it is not necessary to manage the dimensional accuracy (flatness) with high accuracy. As a result, cost can be reduced.

  Since the impeller 140 includes the main plate 143, the number of parts increases. However, in the conventional structure in which the lower casing 132 also serves as the main plate of the impeller, when the lower casing 132 is manufactured by a press, dimensional accuracy (flatness) is improved. It is necessary to manage with high accuracy, and this is costly. The inner diameter side (air inlet side front edge) of the blade 142 is not exposed to the suction port 136 side as in the prior art, and has an inclined surface 142a inclined on the outer peripheral side of the blade 142. It has a shape consisting of a next function (so-called parabola). For this reason, the air flow from the suction port 136 does not disturb the air flow in the vicinity of the suction port 136. For this reason, the noise in the location of the suction inlet 136 can be suppressed.

  A procedure for creating the shape of the inner diameter side (air inlet side front edge) of the blade 142 will be briefly described. The inner peripheral surface of the peripheral edge portion 141a of the opening forming the suction port 136 of the annular shroud 141 forms a surface perpendicular to the axial direction and has a predetermined dimension. The inner diameter (opening diameter) of the peripheral portion 141a is based on a dimension that provides the maximum static pressure required in the design. The lowermost end portion of the inner peripheral surface of the peripheral edge portion 141 a of the opening is a reference numeral 142 b and becomes the innermost diameter portion of the blade 142. A portion where the blade 142 is in contact with the main plate 143 is a reference numeral 142c. Therefore, the inclined surface 142a on the inner diameter side (air inlet side front edge) of the blade 142 is a quadratic function (parabola) passing through two points of the innermost diameter portion 142b of the blade 142 and the portion 142c where the blade 142 contacts the main plate 143. The shape is represented. That is, the portion 142c where the blade 142 contacts the main plate 143 is the apex in the quadratic function. A portion 142c where the blade 142 contacts the main plate 143 is set at a position where noise is reduced.

  A boss 131a extending downward is formed on the periphery of the opening of the upper casing 131, and an annular recess 131b is formed on the outer periphery thereof. The peripheral edge portion 141 a of the opening forming the suction port 136 of the annular shroud 141 constituting the impeller 140 is disposed in the concave portion 131 b of the upper casing 131. And the backflow which goes to the suction inlet 136 can be suppressed by the structure which narrows so that the clearance gap between the upper casing 131 and the cyclic | annular shroud 141 may become narrow toward the suction inlet 136, As a result, noise can be reduced.

  The axial dimension between the annular shroud 141 and the main plate 143 gradually increases from the outermost peripheral edge of the blade 142 toward the outer peripheral edge side. In other words, it spreads in a trumpet shape. Further, the outer diameter of the impeller 140 (the outer diameter of the upper casing 131 and the lower casing 132) is formed to be larger than the outer diameter of a circle passing through the outermost peripheral edge of the blade 142. The air blown out from the outer peripheral edge of the blade 142 spreads in a trumpet shape at the outer peripheral edge of the impeller 140, so that the air flow is not disturbed in the vicinity of the outlet 137. For this reason, the noise in the location of the blower outlet 137 can be suppressed. In the present embodiment, the outer peripheral edge of the annular shroud 141 spreads in a trumpet shape, and the outer peripheral edge of the main plate 143 is a straight line (plane), but the present invention is not limited to this, and the outer peripheral edge of the annular shroud 141 is a straight line. (Planar), the outer peripheral edge of the main plate 143 may have a trumpet shape, or the outer peripheral edge of the annular shroud 141 and the outer peripheral edge of the main plate 143 may naturally have a trumpet shape. With the structure of the present invention, the noise value in the conventional structure is reduced from 61 dB (A) to 52 dB (A).

  As mentioned above, although this invention was demonstrated using embodiment, it cannot be overemphasized that the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiments. Further, it is apparent from the description of the scope of claims that embodiments with such changes or improvements can also be included in the technical scope of the present invention.

100 Centrifugal fan 110 Motor 130 Casing 131 Upper casing 132 Lower casing 133 Concave part 131a Boss part 136 Suction port 140 Impeller 141 Annular shroud 141a Peripheral part 141c Convex part 142 Blade 142a Inclined surface 143 Main plate 144 Hub 146 Groove

Claims (3)

Impeller,
A casing having an upper casing and a lower casing,
The impeller is housed between the upper casing and the lower casing, and the air sucked from the suction port with the rotation of the impeller rotated by a motor is interposed between the upper casing and the lower casing. A centrifugal fan that discharges outward from the air outlet formed on the side surface excluding
The motor is mounted on the bottom surface of a recess formed in the lower casing,
The impeller includes an annular shroud, a plurality of blades, a main plate, and a hub.
The plurality of blades are disposed between the annular shroud and the main plate,
An annular groove is formed on the bottom surface of the main plate,
A part of the electronic component mounted on the circuit board is accommodated in the annular groove,
A boss portion extending downward is formed on the periphery of the opening of the upper casing,
An annular recess is formed on the outer periphery of the boss,
The peripheral edge of the opening forming the suction port of the annular shroud is disposed in the recess of the upper casing,
In the configuration that narrows so that the gap between the upper casing and the annular shroud becomes narrower toward the suction port, an annular convex portion is formed on the slope of the annular shroud, and has the following relationship:
L1>L3> L2 ≧ L4
L5 ≧ 1.5 * L3
(Here, L1 is a gap between the annular shroud and the upper casing, L2 is a gap between the convex portion of the annular shroud and the upper casing, and L3 is an upper end of the peripheral edge of the opening of the annular shroud. L4 is a radial gap between the peripheral edge of the opening of the annular shroud and the concave part of the upper casing, and L5 is a peripheral edge of the opening of the annular shroud. And the length of the concave portion of the upper casing facing each other)
The axial dimension between the annular shroud and the main plate gradually increases from the outermost peripheral edge of the blade toward the outer peripheral edge of the impeller,
A centrifugal fan having a relationship of an outer diameter of an outer peripheral edge of the impeller> a diameter of a circle passing through an outermost peripheral edge of the blade.   The inner diameter side of the blade has an inclined surface that is not exposed to the suction port side and is inclined on the outer peripheral side of the blade, and the inclined surface has a shape formed by a quadratic function. The centrifugal fan according to 1.   The centrifugal fan according to claim 1 or 2, wherein the annular shroud and the plurality of blades are integrally formed by resin injection molding.

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