JP6460957B2 - Centrifugal fan - Google Patents

Description

  The present invention relates to a centrifugal fan, and more particularly, to a centrifugal fan designed to reduce noise.

  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 centrifugal fan that discharges outward from a blow-out port formed on the side surface of the door (see, for example, Patent Document 1).

  FIG. 5 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, and the outer periphery of the annular shroud 131 is warped toward the upper casing 121 from the cylindrical portion 132, and the outer periphery of the annular shroud 131 from the end of the cylindrical portion 132 of the shroud 131. The top surface is formed by a curved surface formed by connecting four arcs having different radii of curvature, and the cross-sectional area of the air flow path to the outer periphery of the annular shroud 131 is gradually increased.

  According to said structure, the pressure of air is increased and it blows off from the outer peripheral part of the impeller 130 outward. 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, and is formed on the side surface between the upper casing 121 and the lower casing 122. The air is discharged outward from the outlet 111.

  However, since the centrifugal fan 100 described in Patent Document 1 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 out from the outer periphery of the impeller 130 is obtained. However, there is a possibility that the gas flows backward from the gap 125 between the annular 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.

  Conventionally, for example, Patent Document 2 has been proposed as a structure in which the air blown out from the blowout port is prevented from flowing back toward the suction port. FIG. 6 shows a centrifugal fan disclosed in Patent Document 2. A bell mouth 231 that forms an air intake port 236 is formed in an upper case 222 on an upper side of a case 220 that houses the fan. The bell mouth 231 is a shroud. It is formed in a semicircular cross section so as to wrap around the protrusion 262 of 226. The inner wall 311 of the bell mouth 231 and the protrusion 262 have a minute constant interval δ, and the case inner wall 221 near the base of the bell mouth 231 has a substantially constant minute interval δ from the top surface 263 of the shroud 226. Is formed. The substantially constant minute interval δ is formed from the outer peripheral wall of the projection 262 of the shroud 226 to the radially outer end 264 of the top surface 263 that is smoothly curved radially outward. Since the gap between the shroud 226, the bell mouth 231 and the case inner wall 221 is narrow and formed over a long distance by a small interval δ, the back flow from the outlet of the blade 225 passes through the gap to the inner diameter side. The air volume to be reduced is reduced.

JP2012-207600A Japanese Patent No. 2715839

  However, in Patent Document 2, even if the width dimension of the minute interval δ is set to be small, the existence of the minute interval δ is indispensable for maintaining the function of the centrifugal fan. It is difficult to prevent the occurrence of the backflow air flowing through the minute interval δ, and there is a problem that even if the flow rate is small, a blowing sound is generated due to the backflow air passing through the minute interval δ.

  In such a background, the present invention provides a centrifugal fan in which a blowout port is formed between the upper casing and the lower casing on the side surface of a rectangular casing, and a part of the air blown from the outer periphery of the impeller is used as the suction port. An object of the present invention is to provide a centrifugal fan that suppresses backflow and reduces noise.

The invention according to claim 1 includes a casing composed of an upper casing and a lower casing, and an impeller housed in a rotatable state in the casing. The lower casing includes a motor base and a base plate. The outer diameter of the casing and the base plate is larger than the outer diameter of the impeller, the lower surface of the outer peripheral end of the upper casing is formed in a curved surface with a circular cross section, and the upper surface of the outer peripheral end of the base plate of the lower casing is The cross section is formed in an arcuate curved surface, a gap is provided between the upper casing and the impeller, an annular groove is provided on the lower surface of the upper casing, and the annular groove is provided on the upper surface of the impeller. An annular protrusion is provided in a state having a gap in the gap, and the gap between the annular protrusion and the groove is formed by the annular protrusion. A gap L5 between one side surface of the groove and the outer side surface of the groove, and a gap L6 between the other side surface of the annular protrusion and the inner side surface of the groove, the gap L5 and the gap L6 is rather narrow as compared to the gap in the other portion, the top surface of the impeller, and the stepped portion of the inner peripheral side of the stepped portion and the outer peripheral side, is formed between the step portion The lower surface of the upper casing is formed in a shape along the upper surface with the gap formed in the upper surface of the impeller. And the impeller include a gap L1 between the outer peripheral stepped portion and the casing, a gap L2 between the inner peripheral stepped portion and the casing, the inclined surface and the casing. L3 between and the outer peripheral side of the inner peripheral step And the casing, and a gap L7 between the upper end surface of the protrusion and the groove, the gap L1, the gap L2, the gap L3, and the gap L4 are substantially equal, and the gap L7 is a centrifugal fan characterized by being not more than the gap L4 .

The invention according to claim 2 is characterized in that, in the invention according to claim 1, the gap L5 and the gap L6 are substantially equal .

  According to the present invention, in the centrifugal fan in which the air outlet is formed between the upper casing and the lower casing on the side surface of the rectangular casing, a part of the air blown out from the outer periphery of the impeller flows backward toward the air inlet. A centrifugal fan that suppresses the noise and reduces noise can be obtained.

It is a disassembled perspective view of the centrifugal fan of embodiment. 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 a figure explaining the clearance gap in the centrifugal fan of embodiment. It is a figure which shows the conventional centrifugal fan. It is a figure which shows another conventional centrifugal fan.

(1) Basic Structure of Centrifugal Fan FIG. 1 is an exploded perspective view of the centrifugal fan of the embodiment. FIG. 2 shows a sectional view of the centrifugal fan shown in FIG. FIG. 3 shows a partially enlarged view of the centrifugal fan shown in FIG. The basic structure of the centrifugal fan 1 is substantially the same as the structure described in Patent Document 1, and the casing 2 includes an upper casing 3 and a lower casing 4. An impeller 8 is housed between the upper casing 3 and the lower casing 4 in a rotatable state. The air sucked from the suction port 35 along with the rotation of the impeller 8 passes between the blades 10, and the blowout port 36 formed on the side surface excluding the column 7 interposed between the upper casing 3 and the lower casing 4. From the casing 2 toward the outside of the casing 2.

  The impeller 8 is driven by the motor 21 and rotates. The motor 21 is an outer rotor type brushless DC motor, and is mounted on the bottom surface of a recess 5 a formed in the motor base 5. The motor 21 includes a stator 22 and a rotor 15. A circuit board 30 is attached to the motor 21 via a lower insulator 24b. The circuit board 30 is accommodated in a recess 5 a formed in the motor base 5.

  A stator 22 is fixed to the motor base 5 via a bearing holding portion 26. Bearings 27 and 28 are mounted inside the bearing holding portion 26 to support the shaft 16 rotatably. The stator 22 includes a stator core 23 formed by stacking a predetermined number of cores, an 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 teeth of the stator core 23 via the insulator 24. The coil 25 is wound around. The core includes a plurality of teeth (having six teeth in FIG. 3) extending radially outward from the annular yoke, and the stator core 23 is configured by stacking the cores. And the structure by which the stator 22 was arrange | positioned on the outer side of the bearing holding part 26 is obtained by fitting the bearing holding part 26 in the opening formed in the center of the stator core 23.

  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. . The rotor yoke 18 is caulked and fixed to the boss portion 17.

An impeller 8 is fixed to the rotor 15. The impeller 8 includes an annular shroud 9, a plurality of blades 10, and a disk-shaped main plate 11. The blade 10 and the main plate 11 are formed by integral molding of resin. The blade 10 is erected in the axial direction from the main plate 11, has a shape that is curved and inclined backward with respect to the rotation direction, and has a structure of a backward blade (so-called turbo type) with respect to the rotation direction. All the blades 10 have the same shape, and the blade 10 and the annular shroud 9 are joined by ultrasonic welding. The upper surface of the annular shroud 9 has two step portions, each step portion is a flat surface, and an inclined surface is formed between the step portions. The plane of the step portion of the annular shroud 9 makes it easy to apply the electrode of the ultrasonic welder when the blade 10 and the annular shroud 9 are joined by ultrasonic welding.

  Gaps L1 to L7 are formed between the annular shroud 9 and the upper casing 3. An annular protrusion 9 a is formed at the axial upper end of the annular shroud 9. The top of the annular projection 9a is covered with the upper casing 3 with a gap. That is, an annular groove 3d is formed on the lower surface of the upper casing 3 (the surface facing the impeller 8). The annular protrusion 9a is in a positional relationship where it enters the annular groove 3d with a gap. Here, the gap between the upper end of the annular projection 9a and the upper casing is L7, and the lateral gaps of the annular projection 9a are L5 and L6. In this example, L5 = L6 <L7 is set. Further, the gaps in the other portions are set to dimensions such that L1 = L2 = L3 = L4 = L7.

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

  On the upper surface side of the upper casing 3, a plurality of concave portions 3a (meat stealing portions) are formed. The upper casing 3 and the lower casing 4 are joined 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. That is, the support column 7 is formed by integrally molding the upper casing 3 and the resin, and the lower casing 4 is configured by a metal (for example, iron plate) motor base 5 and a resin base plate 6. Here, the upper casing 3 and the lower casing 4 are formed by passing the column 7 through the through hole 6d of the base plate 6 and screwing and tightening the tapping screw 40 into the prepared hole formed in the column 7 through the through hole 5d of the motor base 5. Are combined. 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 7 from the lower casing 4 side and is fixed by a nut from the upper casing 3 side is naturally possible.

  The motor 8 is mounted on the bottom surface of a recess 5 a formed in the motor base 5. Side portions 6 a extending downward are formed at four locations on the outer peripheral end of the base plate 6, and the inside of the side portion 6 a is in contact with the outer periphery of the four sides of the motor base 5 for positioning.

  Components for driving and controlling the motor 21 and electronic components 31 such as a control IC are mounted on the circuit board 30. Therefore, in order to prevent contact between the electronic component 31 mounted on the circuit board 30 and the impeller 8 in a limited space, the main plate 11 is formed with an inclined surface 11a, and the inclined surface 11a is positioned at the position of the inclined surface 11a. A part of the electronic component 31 is accommodated. According to this structure, contact between the electronic component 31 and the impeller 8 can be prevented, and the axial thickness can be reduced.

  As described above, the centrifugal fan 1 includes the casing 2 including the upper casing 3 and the lower casing 4, and the impeller 8 housed in the casing 2 so as to be rotatable. The lower casing 4 includes the motor base 5 and the casing 2. The outer surface of the upper casing 3 and the base plate 6 is larger than the outer diameter of the impeller 8, and the lower surface 3 b of the outer peripheral end of the upper casing 3 is formed in a curved surface having a circular cross section. The upper surface 6b of the outer peripheral end of the base plate 6 is formed in a curved surface having an arcuate cross section, a gap is provided between the upper casing 3 and the impeller 8, and an annular groove 3d is provided on the lower surface of the upper casing 3. The upper surface of the impeller 8 is provided with an annular projection 9a that enters the annular groove 3d with a gap, and the gaps L5 and L6 on the side surface of the projection 9a It has a narrow structure compared to the portion of the gap L1~4 and L7.

(2) Features (2) -1. About 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. The lower surface 3b at the outer peripheral end of the upper casing 3 facing the blowing port 36 is formed in a curved surface having a circular arc cross section. Further, the upper surface 6b of the outer peripheral end of the base plate 6 of the lower casing 4 facing the blowout port 36 is formed in a curved surface having a circular cross section. For this reason, when the air blown out from the outer peripheral end of the impeller 8 is blown out of the casing 2 from the space serving as the blowout port 36 formed between the upper casing 3 and the base plate 6 of the lower casing 4, The direction to be blown out is blown downward in the axial direction, and then the direction is changed slightly upward and blown in the horizontal direction.

  A part of the air blown out from the blow-out port 36 may flow backward from the gap 3c between the upper casing 3 and the annular shroud 9 to the suction port 35 side. This reverse flow flows toward the suction port 35 through the gap 3c.

  Here, the gaps L1, L2, L3, and L4 between the upper casing 3 and the annular shroud 9 are formed substantially evenly, and the gap L5 between the side surface of the protrusion 9a of the annular shroud 9 and the upper casing 3 is formed. , L6 are substantially equal, and the gaps L7 and L1 to L4 between the top of the projection 9a of the annular shroud 9 and the upper casing 3 are larger than the gaps L5 and L6. That is, the relationship between the gaps is L1 = L2 = L3 = L4 = L7> L5 = L6. Here, L7 may be smaller than L4, but it is necessary to satisfy L7> L5 = L6.

  In this structure, a labyrinth structure is formed by the gaps L5 and L6. The air passing through L5 decreases due to the resistance of the flow path passing through L5. By increasing the spatial volume at L7, reflux occurs, the air passing through L6 decreases, and further, the resistance of the flow path passing through L6 passes. Air to be reduced. As described above, the labyrinth structure using L5 and L6 can suppress the backflow entering the suction port 35.

  Since the gaps L1 to L4 between the upper casing 3 and the annular shroud 9 are formed substantially evenly, there is no pressure difference due to the wind speed at each location, noise caused thereby is suppressed, and the gaps L5 and L6 are further reduced. The air flowing back to the suction port 35 side is suppressed by the labyrinth structure formed by the above, so that noise can be reduced.

  DESCRIPTION OF SYMBOLS 1 ... Centrifugal fan, 2 ... Casing, 3 ... Upper casing, 3a ... Recessed part, 3b ... Lower surface of outer peripheral end of upper casing 3, 3c ... Gap, 3d ... Annular groove, 4 ... Lower casing, 5 ... Motor base, 5a ... concave portion, 5d ... through hole, 6 ... base plate, 6a ... side portion, 6b ... upper surface of outer peripheral end of base plate 6, 6d ... through hole, 7 ... prop, 8 ... impeller, 9 ... shroud, 9a ... projection, 10 ... blades, 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 holder, 27 ... Bearing, 28 ... Bearing, 30 ... Circuit board, 31 ... Child parts, 35 ... suction port, 36 ... air outlet.

Claims (2)

A casing composed of an upper casing and a lower casing;
An impeller housed in a rotatable state in the casing,
The lower casing is composed of a motor base and a base plate,
The outer diameter of the upper casing and the base plate is larger than the outer diameter of the impeller,
The lower surface of the outer peripheral end of the upper casing is formed in a curved surface having a circular arc cross section,
The upper surface of the outer peripheral end of the base plate of the lower casing is formed in a curved surface having a circular arc cross section,
A gap is provided between the upper casing and the impeller,
An annular groove is provided on the lower surface of the upper casing,
An annular protrusion is provided on the upper surface of the impeller with a gap in the annular groove.
The gap between the annular protrusion and the groove includes a gap L5 between one side surface of the annular protrusion and the outer peripheral side surface of the groove, and the other side surface of the annular protrusion. and a gap L6 between the inner peripheral side surface of said groove and said gap L5 and the gap L6 is rather narrow in comparison to the gap at other portions,
The upper surface of the impeller has a step portion on the inner peripheral side and a step portion on the outer peripheral side, and an inclined surface that becomes a descending surface from the inner peripheral side to the outer peripheral side formed between these step portions,
The lower surface of the upper casing is formed in a shape along the upper surface with the gap formed in the upper surface of the impeller,
The gap between the upper casing and the impeller is:
A gap L1 between the step portion on the outer peripheral side and the casing,
A gap L2 between the inner peripheral step and the casing,
A gap L3 between the inclined surface and the casing;
A gap L4 between an outer peripheral side surface of the inner peripheral step and the casing,
A gap L7 between the upper end surface of the protrusion and the groove,
The centrifugal fan , wherein the gap L1, the gap L2, the gap L3, and the gap L4 are substantially equal, and the gap L7 is equal to or less than the gap L4 .   The centrifugal fan according to claim 1, wherein the gap L5 and the gap L6 are substantially equal.

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