JP2016205336A - Centrifugal blower and cleaning machine - Google Patents

Abstract

SOLUTION: An impeller 12A has an upper shroud 51A having a cylindrical part 511A forming an intake hole 513A, a lower shroud 52A and a plurality of blades 53A arranged between the upper shroud and the lower shroud. A blower casing 13A stores at least an upper end of a motor 11A and an impeller at an inside in a radial direction. A radial clearance between an inner peripheral surface or an outer peripheral surface of a cylinder part and a blower casing has an upper labyrinth part 81A having a narrow width in a radial direction than a width in an axial direction of an upper axial clearance 73A between the upper end surface of the cylinder and the blower casing. A lower axial clearance 74A between a lower surface of the lower shroud and an upper surface of the motor cover 22A has a lower labyrinth part 84A where the axial width is partially narrowed.EFFECT: A size management in an axial direction at the time of assembly of a centrifugal blower is facilitated and a reduction in air blowing amount can be restricted.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a centrifugal blower and a vacuum cleaner.

  Conventionally, centrifugal blowers have been used for high-power blowers such as vacuum cleaners and intake / exhaust devices. The centrifugal blower has a motor that generates a driving force, an impeller that blows air, and a blower casing that houses the motor and the impeller. A conventional centrifugal blower is described in, for example, Japanese Patent Laid-Open No. 1996-326685.

In the centrifugal blower disclosed in Japanese Patent Laid-Open No. 1996-326685, a minute gap is formed by arranging an annular protrusion in an axial gap between a centrifugal fan (impeller) and a fixed fan arranged below the centrifugal fan. . Thereby, it is suppressed that a part of the airflow generated by the rotation of the centrifugal fan (impeller) travels along a path different from the blower path on the lower side of the centrifugal fan (impeller). As a result, a reduction in the amount of blown air is suppressed (paragraph 0019).
JP-A-1996-326685

  In recent years, there has been a demand for higher output and higher efficiency of centrifugal blowers. Therefore, it is desirable to suppress not only the lower side of the impeller but also the upper side of the impeller from traveling a part of the airflow generated by the rotation of the impeller along a path different from the air blowing path.

  However, with respect to the centrifugal blower described in Japanese Patent Laid-Open No. 1996-326685, there is a small gap in the axial direction between the centrifugal fan (impeller) and the fan cover (blower casing) even just above the centrifugal fan (impeller). When formed, not only is it difficult to manage the axial dimension of the centrifugal fan (impeller) and the fixed fan, but also it is difficult to manage the axial dimension of the centrifugal fan (impeller) and the fan cover (blower casing). .

  The objective of this invention is providing the technique which makes easy the dimension management of the axial direction at the time of the assembly of a centrifugal blower, and can suppress the reduction | decrease in ventilation volume.

  An exemplary first invention of the present application includes a stationary part having a motor cover, a motor having a rotating part that rotates about a central axis that extends vertically, and a motor that is disposed above the motor and rotates together with the rotating part. An impeller, and at least an upper end of the motor and a blower casing that accommodates the impeller radially inside. The impeller extends substantially perpendicularly to the central axis, and a lower surface faces the upper surface of the motor cover. A plate-like lower shroud, an upper shroud disposed above the lower shroud and having a suction hole in the center, and a plurality of blades disposed between the lower shroud and the upper shroud. The upper shroud includes a cylindrical portion that forms the intake hole, and a skirt that extends radially outward from a lower end portion of the cylindrical portion, and the lower shroud The lower surface of the motor cover and the upper surface of the motor cover are opposed to each other in the axial direction through a lower axial gap, and the lower axial gap has a lower labyrinth portion in which the axial width is partially narrowed. The upper end surface of the cylindrical portion and the blower casing face each other in the axial direction through an upper axial gap, and the inner peripheral surface or the outer peripheral surface of the cylindrical portion and the blower casing pass through a radial gap. And the radial gap is a centrifugal fan having an upper labyrinth portion having a radial width narrower than an axial width of the upper axial gap.

  According to the exemplary first invention of the present application, it is possible to easily manage the axial dimension when assembling the centrifugal blower, and to suppress a reduction in the amount of blown air.

FIG. 1 is a longitudinal sectional view of a centrifugal blower according to the first embodiment. FIG. 2 is a longitudinal sectional view of a centrifugal blower according to the second embodiment. FIG. 3 is a partial longitudinal sectional view of a centrifugal blower according to the second embodiment. FIG. 4 is a partial longitudinal sectional view of a centrifugal blower according to a modification. FIG. 5 is a partial longitudinal sectional view of a centrifugal blower according to a modification. FIG. 6 is a partial longitudinal sectional view of a centrifugal blower according to a modification.

  Hereinafter, exemplary embodiments of the present invention will be described with reference to the drawings. In the present application, the direction parallel to the central axis of the centrifugal blower is referred to as “axial direction”, the direction orthogonal to the central axis of the centrifugal blower is referred to as “radial direction”, and the direction along the circumference centered on the central axis of the centrifugal blower is defined. These are referred to as “circumferential directions”, respectively. Further, in the present application, the shape and positional relationship of each part will be described with the axial direction as the vertical direction and the impeller side as the upper side with respect to the motor. However, the definition of the vertical direction is not intended to limit the direction of the centrifugal blower during manufacture and use.

<1. First Embodiment>
FIG. 1 is a longitudinal sectional view of a centrifugal fan 1A according to the first embodiment. As shown in FIG. 1, the centrifugal blower 1A includes a motor 11A, an impeller 12A, and a blower casing 13A.

  The motor 11A includes a stationary portion 20A having a motor cover 22A and a rotating portion 30A that rotates about a central axis 9A that extends vertically.

  The impeller 12A is disposed above the motor 11A and rotates together with the rotating portion 30A of the motor 11A. The impeller 12A includes an upper shroud 51A, a lower shroud 52A, and a plurality of blades 53A disposed between the upper shroud 51A and the lower shroud 52A.

  The upper shroud 51A is disposed above the lower shroud 52A. The upper shroud 51A has an intake hole 513A in the center thereof. Further, the upper shroud 51A has a cylindrical portion 511A that forms the intake hole 513A, and a skirt portion 512A that extends radially outward from the lower end portion of the cylindrical portion 511A. The lower shroud 52A is a plate-like member that extends substantially perpendicular to the central axis 9A. The lower surface of the lower shroud 52A faces the upper surface of the motor cover 22A.

  The blower casing 13A accommodates at least the upper end of the motor 11A and the impeller 12A inside in the radial direction.

  The inner peripheral surface of the cylindrical portion 511A and the blower casing 13A are opposed to each other in the radial direction via the radial gap 71A. The upper end surface of the cylinder portion 511A and the blower casing 13A are opposed to each other in the axial direction via the upper axial gap 73A. The radial gap 71A has an upper labyrinth portion 81A whose radial width is narrower than the axial width of the upper axial gap 73A.

  The lower surface of the lower shroud 52A and the upper surface of the motor cover 22A are opposed to each other in the axial direction via the lower axial gap 74A. The lower axial gap 74A has lower labyrinth portions 84A and 85A in which the axial width is partially narrowed.

  In this centrifugal blower 1A, a part of the air flow generated by the rotation of the impeller 12A travels through a different path from the air supply path by the two types of labyrinth parts, the upper side labyrinth part 81A and the lower side labyrinth parts 84A, 85A, and the amount of air flow decreases. Is effectively suppressed.

  Further, in the centrifugal blower 1A, the upper labyrinth portion 81A is formed not in the axial gap between the upper shroud 51A such as the upper axial gap 73A and the blower casing 13A but in the radial gap 71A. Thereby, even if the impeller 12A is displaced upward in the axial direction with respect to the blower casing 13A, the contact between the impeller 12A and the blower casing 13A is suppressed. Therefore, it is possible to easily manage the dimensions in the axial direction when assembling the centrifugal blower 1A, and to suppress a decrease in the amount of air blown.

<2. Second Embodiment>
<2-1. Centrifugal blower configuration>
FIG. 2 is a longitudinal sectional view of the centrifugal blower 1 according to the second embodiment. The centrifugal blower 1 is a turbo centrifugal fan that sucks upward air from an intake hole 513 provided in an upper portion and discharges the air downward. A turbo centrifugal fan is more efficient and has less noise than a sirocco centrifugal fan.

  The centrifugal blower 1 of this embodiment is provided in a vacuum cleaner, for example, and is used to generate a suction force. However, the centrifugal blower of the present invention may be used for applications other than the vacuum cleaner. For example, it is installed in other blower devices such as range hood fans and air supply and exhaust devices used for building ducts, home appliances, medical devices, industrial large equipment, etc., and performs intake and exhaust Also good.

  As shown in FIG. 2, the centrifugal blower 1 includes a motor 11, an impeller 12, and a blower casing 13. The rotating part 30 and the impeller 12 described later of the motor 11 rotate about the central axis 9.

  The motor 11 is an inner rotor type brushless DC motor. The motor 11 has a stationary part 20 and a rotating part 30. The stationary part 20 is relatively stationary with respect to the blower casing 13. The rotating unit 30 is supported to be rotatable about the central axis 9 with respect to the stationary unit 20.

  The stationary part 20 includes a stator 21, a motor cover 22, a bottom plate 23, a circuit board 24, an upper bearing 25 and a lower bearing 26. The rotating unit 30 includes a shaft 31 and a rotor 32.

  The stator 21 is an armature that generates a magnetic flux according to the drive current supplied from the circuit board 24. The stator 21 surrounds the center axis 9 extending vertically in an annular shape. The stator 21 includes a stator core 211, an insulator 212, and a plurality of coils 213.

  The stator core 211 is made of a laminated steel plate in which electromagnetic steel plates are laminated in the axial direction. The stator core 211 has an annular core back 41 and a plurality of teeth 42 protruding radially inward from the core back 41. The core back 41 is disposed substantially coaxially with the central axis 9. The plurality of teeth 42 are arranged at substantially equal intervals in the circumferential direction.

  The insulator 212 is attached to the stator core 211. As a material of the insulator 212, a resin which is an insulator is used. The insulator 212 covers both end surfaces in the axial direction and both end surfaces in the circumferential direction of the teeth 42. The coil 213 is composed of a conductive wire wound around the teeth 42 via an insulator 212.

  The motor cover 22 is a member that holds the stator 21 and the upper bearing 25. The motor cover 22 includes an upper plate part 221, a side plate part 222, a first fixing part 223, a second fixing part 224, and a third fixing part 225.

  The upper plate portion 221 is a plate-like portion that extends substantially perpendicular to the central axis 9 above the stator 21. An upper bearing 25 is held inside the upper plate portion 221 in the radial direction. The side plate portion 222 extends in a substantially cylindrical shape from the outer edge of the upper plate portion 221 downward in the axial direction. For this reason, the upper surface of the motor cover 22, that is, the upper surface of the upper plate portion 221 extends substantially perpendicular to the central axis 9 above the stator 21. Further, the outer peripheral surface of the motor cover 22, that is, the outer peripheral surface of the side plate portion 222 extends in a cylindrical shape downward from the outer edge of the upper surface of the motor cover 22.

  The first fixing portion 223 and the second fixing portion 224 protrude radially inward from the inner peripheral surface of the side plate portion 222. The first fixing portion 223 is disposed above the core back 41 of the stator core 211. The first fixing portion 223 has a screw hole that is recessed upward from the lower surface. The second fixing portion 224 is disposed below the core back 41 of the stator core 211. The 2nd fixing | fixed part 224 has a screw hole penetrated up and down.

  The core back 41 is provided with a through hole 411 penetrating in the axial direction. The stator 21 and the motor cover 22 are fixed by fitting the screw 43 into the screw hole provided in the motor cover 22 and the through hole 411.

  In the motor 11 of this embodiment, the screw holes and the through holes 411 of the first fixing portion 223 and the second fixing portion 224 into which the screws 43 are fitted are provided at three locations in the circumferential direction. Note that the number of fixing points between the stator 21 and the motor cover 22 is not limited to three, and may be two or four or more. Further, the fixing method of the stator 21 and the motor cover 22 is not limited to screwing. The stator 21 and the motor cover 22 may be fixed by other methods such as press fitting or adhesion.

  The third fixing portion 225 protrudes radially outward from the vicinity of the lower end portion of the side plate portion 222. The bottom plate 23 is fixed to the third fixing portion 225 by screwing. In the motor 11 of the present embodiment, the third fixing portions 225 are provided at three locations in the circumferential direction. Note that the number of places where the motor cover 22 and the bottom plate 23 are fixed is not limited to three, and may be two or four or more. Further, the motor cover 22 and the bottom plate 23 may be fixed by other methods.

  The bottom plate 23 is a member that covers at least a part of the opening below the motor cover 22. The bottom plate 23 extends substantially perpendicular to the central axis 9. A lower bearing 26 is held at the center of the bottom plate 23. The stator 21, the circuit board 24, the upper bearing 25, the lower bearing 26, and the rotor 32 are accommodated in a housing constituted by the motor cover 22 and the bottom plate 23.

  The circuit board 24 is disposed substantially perpendicular to the central axis 9 below the stator 21. On the circuit board 24, electronic components constituting an electric circuit for supplying a drive current to the coil 213 are mounted. The ends of the conductive wires constituting the coil 213 are electrically connected to an electric circuit on the circuit board 24.

  The upper bearing 25 is a mechanism that rotatably supports the shaft 31 with respect to the motor cover 22. The upper bearing 25 is disposed below the lower labyrinth portions 84 to 86 described later. The lower bearing 26 is a mechanism that rotatably supports the shaft 31 with respect to the bottom plate 23. As the upper bearing 25 and the lower bearing 26, for example, ball bearings in which spherical rolling elements are interposed between an inner ring and an outer ring are used.

  An elastic member 27 is interposed between the motor cover 22 and the upper bearing 25. Thereby, the vibration at the time of rotation of the motor 11 and the impeller 12 can be reduced.

  The shaft 31 is a columnar member disposed along the central axis 9. The shaft 31 is supported by the upper bearing 25 and the lower bearing 26 and rotates around the central axis 9. The upper end portion of the shaft 31 protrudes above the motor cover 22 and the impeller 12 is fixed. In the present embodiment, the impeller 12 is directly fixed to the shaft 31, but the impeller 12 may be indirectly fixed to the shaft 31 via another member.

  The rotor 32 is fixed to the shaft 31 and rotates together with the shaft 31. The rotor 32 of the present embodiment is made of magnet resin formed in a substantially cylindrical shape. On the outer peripheral surface of the rotor 32, N poles and S poles are alternately magnetized in the circumferential direction. Further, the outer peripheral surface of the rotor 32 faces the end surface on the radially inner side of the tooth 42 in the radial direction with a slight gap therebetween. That is, the rotor 32 has a magnetic pole surface that faces the stator 21 in the radial direction.

  In this embodiment, the magnet resin rotor 32 is used. However, the rotor 32 may be one in which a plurality of magnets are fixed to the outer peripheral surface or inside of a cylindrical rotor core that is a magnetic body. Good.

  When the motor 11 is driven, a drive current is supplied from the electric circuit on the circuit board 24 to the coil 213, and magnetic flux is generated in the plurality of teeth 42 of the stator core 211. Thereby, circumferential torque is generated by the action of the magnetic flux between the teeth 42 and the rotor 32. As a result, the rotating unit 30 rotates about the central axis 9. The impeller 12 rotates with the rotation of the rotating unit 30.

  The impeller 12 is a so-called turbo centrifugal impeller. The impeller 12 is disposed above the motor cover 22 of the motor 11. As shown in FIG. 2, the impeller 12 includes an upper shroud 51, a lower shroud 52, and a plurality of blades 53.

  The upper shroud 51 includes a cylinder portion 511, a skirt portion 512, and an intake hole 513. The upper shroud 51 is disposed above the lower shroud 52 and the plurality of blades 53.

  The cylindrical part 511 is a substantially cylindrical part centering on the central axis 9. The cylindrical portion 511 of the present embodiment has a substantially constant diameter regardless of the position in the axial direction. The cylindrical portion 511 may have a shape that gradually increases in diameter as it goes downward in the axial direction.

  The skirt portion 512 extends radially outward from the lower end portion of the cylindrical portion 511. The radial position of the outer edge of the skirt 512 is substantially the same as the radial position of the outer edge of the lower shroud 52. The intake hole 513 is disposed at the center of the upper shroud 51. The intake hole 513 is formed by the cylindrical portion 511 and penetrates the upper shroud 51 in the axial direction on the radially inner side of the cylindrical portion 511.

  The lower shroud 52 is a plate-like portion that extends substantially perpendicular to the central axis 9 above the motor cover 22. The lower surface of the lower shroud 52 faces the upper surface of the motor cover 22 in the axial direction. The lower shroud 52 is fixed to the shaft 31 of the motor 11 at its radially inner end.

  The blade 53 is disposed between the upper shroud 51 and the lower shroud 52. The plurality of blades 53 are arranged at substantially equal intervals in the circumferential direction. When the centrifugal blower 1 is driven, the gas between the upper shroud 51 and the lower shroud 52 is accelerated radially outward by the plurality of blades 53.

  The blower casing 13 includes a top plate portion 131 and a wall portion 132. The top plate 131 is disposed above the impeller 12 and extends in an annular shape along the upper surface of the upper shroud 51. The top plate portion 131 has a central hole 130 at the center thereof. The wall 132 extends downward in a cylindrical shape from the top plate 131 on the radially outer side of the motor 11. The motor 11 and the impeller 12 are accommodated inside the wall portion 132 in the radial direction.

  The blower casing 13 of the present embodiment is formed from three annular members of an upper casing 133, a central casing 134, and a lower casing 135. The central casing 134 is disposed below the upper casing 133. Further, the lower casing 135 is disposed below the central casing 134. The upper casing 133 includes the top plate part 131 and the upper end of the wall part 132. The central casing 134 and the lower casing 135 are cylindrical members that form the wall portion 132. Although the blower casing 13 of this embodiment is formed of three members, the blower casing 13 may be formed of one member, or may be formed of two or four or more members.

  The outer peripheral surface of the motor cover 22 and the inner peripheral surface of the wall portion 132 of the blower casing 13 are arranged with a gap in the radial direction. A space between the outer peripheral surface of the motor cover 22 and the inner peripheral surface of the wall portion 132 serves as a gas flow path 10 when the centrifugal blower 1 is driven.

<2-2. About airflow>
Next, the flow of the airflow when the centrifugal blower 1 is driven will be described with reference to FIGS. 2 and 3. FIG. 3 is a partial longitudinal sectional view of the centrifugal blower 1.

  When the centrifugal blower 1 is driven, a drive current is supplied to the stator 21 of the motor 11, and the rotating unit 30 and the impeller 12 of the motor 11 rotate. When the impeller 12 rotates, the gas above the blower casing 13 is sucked through the central hole 130 of the blower casing 13 and the intake hole 513 of the impeller, as indicated by solid arrows in FIG. 2 and FIG. . The gas passes between the upper shroud 51 and the lower shroud 52 and is discharged to the outside in the radial direction of the impeller 12.

  As shown in FIG. 2, the gas discharged to the radially outer side of the impeller 12 changes its direction downward near the wall portion 132 of the blower casing 13, so that the outer peripheral surface of the motor cover 22 and the inner wall portion 132 It progresses in the axial direction downward in the flow path 10 formed between the peripheral surfaces. Then, the gas is discharged from the lower end portion of the flow path 10 to the outside of the centrifugal blower 1.

  Here, the top plate portion 131 of the blower casing 13 includes an inner annular portion 61, a connection annular portion 62, and an outer annular portion 63 at the radially inner end thereof. The inner annular portion 61 is disposed at the innermost end in the radial direction of the top plate portion 131. The inner annular portion 61 is a substantially cylindrical portion that is disposed on the radially inner side of the cylindrical portion 511 of the impeller 12 and extends vertically. The connection annular portion 62 is a plate-like and annular portion extending radially outward from the upper end of the inner annular portion 61. The outer annular portion 63 is a cylindrical portion that extends downward from the outer edge of the connection annular portion 62 and is disposed on the radially outer side of the cylindrical portion 511. The outer annular portion 63 of the present embodiment has a conical surface shape in which the distance from the central axis 9 gradually increases from the upper end toward the lower side.

  The blower casing 13 has an annular member 136 that is fixed to the inner peripheral surface of the outer annular portion 63. The annular member 136 has two annular casing protrusions 64 that protrude radially inward from the inner peripheral surface of the outer annular part 63. The two casing protrusions 64 are arranged at an upper end portion and a lower end portion of the annular member 136 with an interval in the axial direction.

  The inner peripheral surface of the cylindrical portion 511 of the impeller 12 and the outer peripheral surface of the inner annular portion 61 of the blower casing 13 are opposed to each other in the radial direction through the inner radial gap 71. The outer peripheral surface of the cylindrical portion 511 of the impeller 12 and the inner peripheral surface of the annular member 136 of the blower casing 13 are opposed to each other in the radial direction through the outer radial gap 72. Further, the upper end surface of the cylindrical portion 511 of the impeller 12 and the lower surface of the connection annular portion 62 of the blower casing 13 are opposed to each other in the axial direction through the upper axial gap 73.

  The inner radial gap 71 is a first upper labyrinth portion 81 whose radial width is narrower than the axial width of the upper axial gap 73. Further, the outer radial gap 72 has a second upper labyrinth portion 82 and a third upper labyrinth portion 83 whose radial width is narrower than the axial width of the upper axial gap 73. As shown in an enlarged manner in FIG. 3, the radial width D <b> 1 of the first upper labyrinth portion 81 is narrower than the axial width D <b> 2 of the upper axial gap 73. The radial width D3 of the second upper labyrinth portion 82 and the third upper labyrinth portion 83 is smaller than the axial width D2 of the upper axial gap 73.

  The second upper labyrinth portion 82 is formed between the outer peripheral surface of the cylindrical portion 511 of the impeller 12 and the upper casing protrusion 64. The third upper labyrinth portion 83 is formed between the outer peripheral surface of the cylindrical portion 511 and the lower casing protrusion 64. The outer radial gap 72 has a wide portion 89 having a larger radial width than the upper labyrinth portions 81, 82, 83 between the second upper labyrinth portion 82 and the third upper labyrinth portion 83. That is, the second upper labyrinth portion 82 is disposed on the upper side in the axial direction of the wide portion 89, and the third upper labyrinth portion 83 is disposed on the lower side in the axial direction of the wide portion 89.

  As described above, the upper labyrinth portions 81, 82, and 83 are provided between the cylindrical portion 511 of the impeller 12 and the vicinity of the inner end portion of the blower casing 13. As a result, a part of the gas discharged to the outside in the radial direction of the impeller 12 by the plurality of blades 53 and directed to the flow path 10 is formed between the upper shroud 51 and the blower casing 13 as indicated by broken line arrows in FIG. Leakage into the space between is suppressed.

  Since the blower casing 13 has the casing protrusion 64, the plurality of upper labyrinth portions 82 and 83 can be easily provided in the outer radial gap 72. By providing the two upper labyrinth portions 82, 83 in the outer radial gap 72, the axial airflow in the outer radial gap 72 is smaller than when one long upper labyrinth portion is provided in the entire outer radial gap 72. The movement of can be suppressed more. That is, part of the gas discharged to the radially outer side of the impeller 12 by the plurality of blades 53 is further suppressed from leaking into the space between the upper shroud 51 and the blower casing 13. In this manner, the casing protrusion 64 can be formed in accordance with the required labyrinth characteristics. Therefore, the target labyrinth characteristic can be obtained inexpensively and easily. As a result, it is possible to suppress a decrease in the amount of blown air.

  In order to make the entire outer radial gap 72 as one upper labyrinth portion, it is necessary to increase the dimensional accuracy of the entire surface constituting the outer radial gap 72. On the other hand, the provision of the wide portion 89 facilitates dimensional management and improves work efficiency during manufacturing.

  By providing the first upper labyrinth portion 81 in the inner radial gap 71 and the second upper labyrinth portion 82 and the third upper labyrinth portion 83 in the outer radial gap 72, the cylindrical portion 511 of the impeller 12 and the blower casing are provided. Three upper labyrinth portions 81, 82, and 83 are provided between the inner end portion and the vicinity of 13 inner ends. Thus, by providing a larger number of upper labyrinth parts, a part of the gas discharged to the radially outer side of the impeller 12 by the plurality of blades 53 and directed to the flow path 10 is separated from the upper shroud 51 and the blower casing 13. Leakage into the space between is further suppressed.

  The lower surface of the lower shroud 52 of the impeller 12 and the upper surface of the motor cover 22 face each other in the axial direction with the lower axial gap 74 interposed therebetween. As shown in FIG. 3, a substantially T-shaped washer 14 is in contact with the lower surface of the impeller 12. The washer 14 has a cylindrical shaft portion 141 whose inner peripheral surface is in contact with the outer peripheral surface of the shaft 31, and a flange portion 142 that extends radially outward from the upper end of the shaft portion 141. The lower end surface of the shaft portion 141 is in contact with the upper surface of the upper bearing 25. That is, the washer 14 is an annular contact member that is located on the lower surface of the lower shroud 52 and contacts the rotating portion 30 of the motor 11.

  The washer 14 prevents the impeller 12 from being displaced downward in the axial direction. Thereby, it is suppressed that the impeller 12 slip | deviates to an axial direction lower side, and the impeller 12 and the motor cover 22 contact. The lower surface of the flange portion 142 of the washer 14 and the upper surface of the motor cover 22 are opposed to each other in the axial direction with the lower axial gap 74 interposed therebetween.

  The motor cover 22 has three annular motor protrusions 226, 227 and 228 that protrude upward from the upper surface of the motor cover 22. The three motor protrusions 226, 227, and 228 are arranged in the radial direction.

  A first lower labyrinth portion 84 is formed between the first motor projection 226 disposed on the outermost side in the radial direction among the three motor projections 226, 227, and 228 and the lower surface of the lower shroud 52. . A second lower labyrinth portion is provided between the second motor protrusion 227 disposed radially inward of the first motor protrusion 226 and radially outward of the third motor protrusion 228 and the lower surface of the lower shroud 52. 85 is formed. In addition, a third lower labyrinth portion is provided between the third motor projection 228 disposed on the innermost radial direction among the three motor projections 226, 227, and 228 and the lower surface of the flange portion 142 of the washer 14. 86 is formed.

  Thus, the lower axial gap 74 has three lower labyrinth portions 84, 85, 86 whose axial width is partially narrowed. This suppresses the gas from leaking radially inward in the lower axial gap 74 from the air flow path from the radially outer side of the impeller 12 toward the flow path 10 along the outer peripheral surface of the motor 11. Is done.

  In the present embodiment, in order to form the lower labyrinth portions 84, 85, 86, the motor projections 226, 227, which are projections on the motor cover 22 side, which is a stationary member, not the impeller 12 side, which is a rotating body, 228 is provided. Thereby, compared with the case where a projection part is provided in the lower surface of the lower shroud 52 of the impeller 12, loads such as centrifugal force acting on the impeller 12 can be reduced.

  As described above, in the centrifugal blower 1, a part of the air flow generated by the rotation of the impeller 12 is blown by the two types of labyrinth parts of the upper labyrinth parts 81, 82, 83 and the lower labyrinth parts 84, 85, 86. It is possible to effectively suppress a decrease in the amount of air flow through a different route.

  At this time, the upper labyrinth portions 81, 82, 83 are not formed in the axial gap between the upper shroud 51 and the blower casing 13 such as the upper axial gap 73 but in the inner radial gap 71 and the outer radial gap 72. ing. Thereby, even if it is a case where the impeller 12 has shifted | deviated to the axial direction upper direction with respect to the blower casing 13, it is suppressed that the impeller 12 and the blower casing 13 contact. Therefore, it is possible to easily manage the dimensions in the axial direction when the centrifugal blower 1 is assembled, and to suppress a decrease in the amount of air blown.

  Each part such as the motor cover 22, the impeller 12, and the blower casing 13 constituting the centrifugal blower 1 has a tolerance in the axial height. Therefore, if the axial width of the upper axial gap 73 is designed to be narrower than the axial width of the lower labyrinth portions 84, 85, 86, the blower casing 13 and the upper shroud 51 are separated when the centrifugal blower 1 is assembled. There is a risk of contact.

  However, in the centrifugal blower 1, the axial width of the upper axial gap 73 is wider than the axial width of the lower labyrinth portions 84, 85, 86. For this reason, even if the tolerance of each part is large, only the width of the axial gap between the motor cover 22 and the impeller 12 needs to be accurately dimensionally managed in the axial direction.

  In the present embodiment, by providing a plurality of lower labyrinth portions 84, 85, 86 in the lower axial gap 74, the axial width of each lower labyrinth portion 84, 85, 86 is extremely narrowed. And leakage of gas can be suppressed. Accordingly, even when the impeller 12 is displaced upward in the axial direction with respect to the motor 11, it is possible to suppress the occurrence of radial airflow between the lower surface of the impeller 12 and the upper surface of the motor 11. That is, it is possible to more easily manage the dimensions in the axial direction when the centrifugal blower 1 is assembled.

  In the centrifugal blower 1, three lower labyrinth portions 84, 85, 86 are provided in the lower axial gap 74. As described above, the lower axial gap 74 has three or more lower labyrinth portions, whereby gas leakage can be further suppressed.

  When the number of the lower labyrinth portion provided in the lower axial gap 74 is one, in a region where the rotational speed of the motor 11 is low (for example, 5,000 rpm) compared to the case where the lower labyrinth portion is not provided. Although the suction power increases, no significant improvement in the suction power is observed in a region where the rotational speed is high (for example, 60,000 revolutions per minute). As the number of lower labyrinth portions provided in the lower axial gap 74 is increased, the suction power is improved even in a region where the rotation number of the motor 11 is high.

  This centrifugal blower 1 is used in a vacuum cleaner, and is used in a region where the number of revolutions is about 60,000 rpm. Therefore, it is preferable to provide three or more lower labyrinth portions in the lower axial gap 74.

  In the present embodiment, of the three motor protrusions 226, 227, and 228, the outermost first motor protrusion 226 is disposed approximately at the center between the center shaft 9 and the inner peripheral surface of the blower casing 13. As described above, by arranging the motor protrusions 226, 227, and 228 as radially inward as possible, even if the impeller 12 rotates at a high speed, the resistance force that the impeller 12 receives can be reduced. It is more preferable that the motor protrusion provided on the upper surface of the motor cover 22 is disposed radially inward from the radial center between the central shaft 9 and the inner peripheral surface of the blower casing 13.

  Further, as shown in FIG. 3, the third lower labyrinth portion 86 is disposed below the first lower labyrinth portion 84 and the second lower labyrinth portion 85 in the axial direction. That is, among the lower labyrinth portions 84, 85, 86, the third lower labyrinth portion 86 arranged on the innermost radial direction is lower in the axial direction than the first lower labyrinth portion 84 arranged on the outermost radial direction. Placed in. Thus, one of the plurality of lower labyrinth portions 84, 85, 86 has a different axial height from the other one of the plurality of lower labyrinth portions 84, 85, 86. Thereby, it is possible to further suppress the occurrence of radial airflow in the lower axial gap 74.

  The radial length of the first lower labyrinth portion 84 is longer than the radial length of the second lower labyrinth portion 85 and the radial length of the third lower labyrinth portion 86. In this way, by providing the lower labyrinth portion having a long radial direction, the generation of an air flow from the radially outer side to the inner side in the lower axial gap is further suppressed. Therefore, in this way, the length in one radial direction of the plurality of lower labyrinth portions 84, 85, 86 is longer than the length in the other radial direction of the plurality of lower labyrinth portions 84, 85, 86. It is preferable. In particular, as in the present embodiment, it is more preferable that the first lower labyrinth portion 84 on the outermost radial direction is long in the radial direction.

<3. Modification>
As mentioned above, although exemplary embodiment of this invention was described, this invention is not limited to said embodiment.

  FIG. 4 is a partial longitudinal sectional view of a centrifugal blower 1B according to a modification. In the example of FIG. 4, the impeller 12 </ b> B has two annular impeller protrusions 521 </ b> B and 522 </ b> B that protrude downward from the lower surface of the lower shroud 52 </ b> B. The two annular impeller protrusions 521B and 522B are arranged in the radial direction.

  The lower axial gap 74B between the lower surface of the lower shroud 52B and the motor cover 22B has three lower labyrinth portions 84B, 85B, 86B. Of the three lower labyrinth portions 84B, 85B, 86B, the first lower labyrinth portion 84B and the second lower labyrinth portion 85B are respectively formed between the upper surface of the motor cover 22B and the impeller projections 521B, 522B. Is done. Of the three lower labyrinth portions 84B, 85B, 86B, the third lower labyrinth portion 86B arranged on the innermost radial direction is formed between the upper surface of the motor cover 22B and the flange portion 142B of the washer 14B. .

  As in the example of FIG. 4, the lower labyrinth portions 84B and 85B may be formed by providing a protrusion on the impeller 12B side.

  FIG. 5 is a partial longitudinal sectional view of a centrifugal blower 1C according to another modification. In the example of FIG. 5, the outer annular portion 63C of the blower casing 13C has a substantially cylindrical shape, and the blower casing 13C does not have an annular member.

  The inner peripheral surface of the cylindrical portion 511C of the impeller 12C and the outer peripheral surface of the inner annular portion 61C of the blower casing 13C are opposed to each other in the radial direction through the inner radial gap 71C. The outer peripheral surface of the cylindrical portion 511C of the impeller 12C and the inner peripheral surface of the outer annular portion 63C of the blower casing 13C are opposed to each other in the radial direction through the outer radial gap 72C. Further, the upper end surface of the cylindrical portion 511C of the impeller 12C and the lower surface of the connection annular portion 62C of the blower casing 13C are opposed to each other in the axial direction via the upper axial gap 73C.

  The inner radial gap 71C is a first upper labyrinth portion 81C whose radial width is narrower than the axial width of the upper axial gap 73C. The outer radial gap 72C is a second upper labyrinth portion 82C whose radial width is narrower than the axial width of the upper axial gap 73C.

  As in the example of FIG. 5, the blower casing 13 </ b> C may not have an annular member.

  FIG. 6 is a partial longitudinal sectional view of a centrifugal blower 1D according to another modification. In the example of FIG. 6, the outer annular portion 63D of the blower casing 13D has an approximately cylindrical upper cylindrical portion 631D and lower cylindrical portion 632D, and a concave portion 633D that is recessed radially outward from the upper cylindrical portion 631D and lower cylindrical portion 632D. And have. The recess 633D is disposed below the upper cylindrical portion 631D and above the lower cylindrical portion 632D. Further, the blower casing 13D does not have an annular member.

  The inner peripheral surface of the cylindrical portion 511D of the impeller 12D and the outer peripheral surface of the inner annular portion 61D of the blower casing 13D are opposed to each other in the radial direction through the inner radial gap 71D. The outer peripheral surface of the cylindrical portion 511D of the impeller 12D and the inner peripheral surface of the outer annular portion 63D of the blower casing 13D are opposed to each other in the radial direction via the outer radial gap 72D. Further, the upper end surface of the cylindrical portion 511D of the impeller 12D and the lower surface of the connection annular portion 62D of the blower casing 13D are opposed to each other in the axial direction via the upper axial gap 73D.

  The inner radial gap 71D is a first upper labyrinth portion 81D whose radial width is narrower than the axial width of the upper axial gap 73D. The outer radial gap 72D includes a second upper labyrinth portion 82D and a third upper labyrinth portion 83D that are narrower in radial width than the axial width of the upper axial gap 73D. The second upper labyrinth portion 82D is formed between the outer peripheral surface of the cylindrical portion 511D of the impeller 12D and the inner peripheral surface of the upper cylindrical portion 631D. The third upper labyrinth portion 83D is formed between the outer peripheral surface of the cylindrical portion 511D of the impeller 12D and the inner peripheral surface of the lower cylindrical portion 632D.

  As in the example of FIG. 6, the outer annular portion 63D includes the upper cylindrical portion 631D, the lower cylindrical portion 632D, and the concave portion 633D, so that the two upper labyrinth portions 82D and 83D are formed in the outer radial gap 72D. Good.

  Moreover, about the detailed shape of each member, you may differ from the shape shown by each figure of this application. Moreover, you may combine suitably each element mentioned above in the range by which a contradiction does not arise.

  The present invention can be used for a centrifugal blower and a vacuum cleaner.

1, 1A, 1B, 1C, 1D Centrifugal blower 9, 9A Central shaft 10 Flow path 11, 11A Motor 12, 12A, 12B, 12C, 12D Impeller 13, 13A, 13C, 13D Blower casing 14, 14B Washer 20, 20A Stationary Part 22, 22A, 22B Motor cover 25 Upper bearing 27 Elastic member 30, 30A Rotating part 51, 51A Upper shroud 52, 52A, 52B Lower shroud 53, 53A Blade 61, 61C, 61D Inner annular part 62, 62C, 62D Connection annular Portion 63, 63C, 63D Outer annular portion 64 Casing protrusion 71, 71C, 71D Inner radial gap 71A Radial gap 72, 72C, 72D Outer radial gap 73, 73A, 73C, 73D Upper axial gap 74, 74A, 74B Lower axial clearance 81, 81A, 1C, 81D, 82, 82C, 82D, 83, 83D Upper labyrinth part 84, 84A, 84B, 85, 85A, 85B, 86, 86B Lower labyrinth part 89 Wide part 130 Central hole 131 Top plate part 132 Wall part 136 Annular Member 142, 142B Flange portion 226, 227, 228 Motor projection portion 511, 511A, 511C, 511D Tube portion 513, 513A Air intake hole 521B, 522B Impeller projection portion

Claims (15)

A motor having a stationary part having a motor cover and a rotating part rotating around a central axis extending vertically;
An impeller disposed above the motor and rotating together with the rotating part;
A blower casing that houses at least the upper end of the motor and the impeller radially inside;
Have
The impeller is
A plate-like lower shroud that extends substantially perpendicular to the central axis and whose lower surface faces the upper surface of the motor cover;
An upper shroud disposed above the lower shroud and having a suction hole in the center;
A plurality of blades disposed between the lower shroud and the upper shroud;
Have
The upper shroud is
A cylindrical portion forming the intake hole;
A hem that extends radially outward from the lower end of the tubular portion;
Have
The lower surface of the lower shroud and the upper surface of the motor cover are opposed to each other in the axial direction through a lower axial gap,
The lower axial gap has a lower labyrinth portion in which the axial width is partially narrowed,
The upper end surface of the cylindrical portion and the blower casing are opposed to each other in the axial direction through an upper axial gap,
The inner peripheral surface or outer peripheral surface of the cylindrical portion and the blower casing are opposed to each other in a radial direction through a radial gap,
The radial blower has an upper labyrinth portion whose radial width is narrower than the axial width of the upper axial gap. The centrifugal blower according to claim 1,
The motor cover is
Having an annular motor protrusion protruding upward from the upper surface of the motor cover;
The lower labyrinth portion is a centrifugal blower formed between the motor protrusion and a lower surface of the lower shroud. It is a centrifugal blower of Claim 2, Comprising:
The motor protrusion is a centrifugal blower disposed on a radially inner side than a radial middle point between the central shaft and an inner peripheral surface of the blower casing. It is a centrifugal blower of Claim 2 or Claim 3, Comprising:
An annular contact member located on the lower surface of the lower shroud of the impeller and in contact with the rotating portion;
The lower labyrinth part is a centrifugal blower formed between the motor protrusion and a lower surface of the contact member. The centrifugal blower according to any one of claims 1 to 4,
The impeller is
An annular impeller projection projecting downward from the lower surface of the lower shroud;
The lower labyrinth portion is a centrifugal blower formed between an upper surface of the motor cover and the impeller protrusion. The centrifugal blower according to any one of claims 1 to 5,
The lower axial gap is a centrifugal blower having a plurality of the lower labyrinth portions arranged in a radial direction. It is a centrifugal blower of Claim 6, Comprising:
The lower axial gap is a centrifugal blower having three or more lower labyrinth portions arranged in a radial direction. The centrifugal blower according to claim 6 or 7, wherein
One of the lower labyrinth parts is a centrifugal blower having a different axial height from the other one of the lower labyrinth parts. It is a centrifugal blower of Claim 8, Comprising:
The lower side labyrinth portion arranged at the innermost radial direction is a centrifugal blower arranged below the lower labyrinth portion arranged at the outermost radial direction. A centrifugal blower according to any one of claims 6 to 9,
The centrifugal blower in which one radial length of the lower labyrinth portion is longer than another radial length of the lower labyrinth portion. It is a centrifugal blower in any one of Claims 1 thru | or 10, Comprising:
The radial gap is
Two upper labyrinth sections;
A wide portion having a larger radial width than the upper labyrinth portion;
Have
The two upper labyrinth parts are respectively arranged in the axially upper side of the wide part and the axially lower side of the wide part. It is a centrifugal blower of Claim 11, Comprising:
The radial gap is located between the outer peripheral surface of the cylindrical portion and the inner peripheral surface of the blower casing,
The blower casing has a casing protrusion that protrudes radially inward on the inner peripheral surface thereof.
The upper labyrinth part is a centrifugal blower formed between the casing protruding part and an outer peripheral surface of the cylindrical part. A centrifugal blower according to any one of claims 1 to 12,
The centrifugal blower, wherein an axial width of the upper axial gap is wider than an axial width of the lower labyrinth part. The centrifugal blower according to any one of claims 1 to 13,
The motor is
A shaft to which the impeller is fixed directly or indirectly;
A ball bearing that rotatably supports the shaft with respect to the stationary portion;
An elastic member interposed between the motor cover and the ball bearing;
Have
The ball bearing is a centrifugal blower disposed below the lower labyrinth portion.   The vacuum cleaner which has a centrifugal blower in any one of Claims 1 thru | or 14.

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