JP2021046793A - Electric blower - Google Patents

Abstract

To propose an electric blower which has a simpler structure than that of a conventional electric blower having a labyrinth structure and can prevent reverse flow of a centrifugal fan in a more reliable manner.SOLUTION: An electric blower 1 has: a centrifugal fan 2 having a hub 11 having a conical shape, blades 12 extending from the hub 11 to a fan cover 7, and a shroud 13 which is connected with front edges of part of or all of the blades 12 to couple the part of or all of the blades 12; and a fan cover 7 which has a suction port 6 leading to the centrifugal fan 2 and covers the centrifugal fan 2. A gap between the shroud 13 and the fan cover 7 is narrower than a gap between the blades 12 and the fan cover 7.SELECTED DRAWING: Figure 2

Description

The embodiment according to the present invention relates to an electric blower.

The turbofan of a centrifugal blower has a plurality of blades and a shroud extending from the front edge to the trailing edge of the plurality of blades. Further, the centrifugal blower has a labyrinth structure formed between the fan cover and the shroud ring, which is located on the outer side in the radial direction from the inner peripheral end of the shroud. This labyrinth structure suppresses the backflow flow rate of the turbofan.

JP-A-2018-168852

The conventional centrifugal blower suppresses the backflow of the turbofan by a labyrinth structure located outside the turbofan in the radial direction from the suction port of the centrifugal blower.

Therefore, an object of the present invention is to propose an electric blower having a simpler structure than a conventional electric blower having a labyrinth structure and capable of more reliably preventing backflow of a centrifugal fan.

In order to solve the above problems, the electric blower according to the embodiment of the present invention includes a centrifugal fan, a fan cover having a suction port connected to the centrifugal fan and covering the centrifugal fan, and an electric motor for rotating the centrifugal fan. The centrifugal fan comprises a conical hub, a plurality of blades extending from the hub toward the fan cover, and the plurality of blades connected to a part or all front edges of the plurality of blades. A shroud that connects a part or all of the blades is provided, and the gap between the shroud and the fan cover is narrower than the gap between the plurality of blades and the fan cover.

The vertical sectional view of the electric blower which concerns on embodiment of this invention. Partial sectional perspective view of the electric blower which concerns on embodiment of this invention. It is an exploded perspective view of the centrifugal fan of the electric blower which concerns on this embodiment. FIG. 5 is a cross-sectional view of a first example of a seal structure of an electric blower according to the present embodiment. FIG. 2 is a cross-sectional view of a second example of a seal structure of an electric blower according to the present embodiment. FIG. 3 is a cross-sectional view of a third example of a seal structure of an electric blower according to the present embodiment.

An embodiment of the electric blower according to the present invention will be described with reference to FIGS. 1 to 6. In the plurality of drawings, the same or corresponding configurations are designated by the same reference numerals.

FIG. 1 is a vertical sectional view of an electric blower according to an embodiment of the present invention.

FIG. 2 is a partial cross-sectional perspective view of the electric blower according to the embodiment of the present invention.

As shown in FIGS. 1 and 2, the electric blower 1 according to the present embodiment includes a centrifugal fan 2, an electric motor 3 that rotationally drives the centrifugal fan 2, and a diffuser 5 that guides the fluid blown out from the centrifugal fan 2 to the electric motor 3. A fan cover 7 having a suction port 6 connected to the centrifugal fan 2 and covering the centrifugal fan 2 and a frame 8 for supporting the centrifugal fan 2 and the electric motor 3 are provided. The fluid is exclusively a gas and is air.

The centrifugal fan 2 is a molded product or a molded product of a resin such as polyetheretherketone (PEEK). The centrifugal fan 2 is rotationally and integrally fixed to a shaft 9 corresponding to the output shaft of the electric motor 3. The centrifugal fan 2 is arranged on the upstream side of the diffuser 5.

The centrifugal fan 2 includes a conical hub 11, a plurality of blades 12 protruding from the hub 11, and a shroud 13 connecting a part or all of the plurality of blades 12. The centrifugal fan 2 has a hub 11 corresponding to a rear shroud and a shroud 13 corresponding to a front shroud.

The hub 11 has a truncated cone shape in which the diameter gradually increases from the central portion where the fluid is sucked toward the outer edge portion where the fluid is blown out. A hole 11a for arranging the shaft 9 is provided in the center of the hub 11. The hole 11a penetrates the hub 11 along the rotation center line of the centrifugal fan 2.

The plurality of blades 12 extend from the hub 11 toward the inner surface of the fan cover 7. The plurality of blades 12 are so-called circular blade trains. The plurality of blades 12 are arranged at equal intervals in the circumferential direction of the hub 11. Each blade 12 has a twisted shape that gradually rises toward the fan cover 7 from the central portion of the hub 11 toward the outer edge portion of the hub. In other words, the plurality of blades 12 are so-called three-dimensional blades in which the airfoil or the wing section changes from the front edge to the trailing edge.

The shroud 13 is connected to the front edge 12f of a part or all of the plurality of blades 12, but does not reach the trailing edge 12b of a part or all of these blades 12. In other words, the shroud 13 is interrupted in the middle of the blades 12 from the front edges 12f of a part or all of the blades 12. Therefore, the blade 12 has an upstream portion covered with the shroud 13 and a downstream portion not covered with the shroud 13. When the shroud 13 connects a part of the plurality of blades 12, the plurality of blades 12 include the blades 12 not covered by the shroud 13 from the front edge 12f to the trailing edge 12b.

A retaining portion 15 is provided at the tip of the shaft 9 to prevent the centrifugal fan 2 from coming off the shaft 9. The retaining portion 15 is, for example, a hardened adhesive or a nut fastened to a screw portion provided on the shaft 9. When the centrifugal fan 2 rotates and the electric blower 1 sucks the fluid, a load, a so-called thrust load, acts on the centrifugal fan 2 in the direction of coming out of the shaft 9. The retaining portion 15 prevents the centrifugal fan 2 from coming out of the shaft 9 against the thrust load acting on the centrifugal fan 2.

The electric motor 3 is a non-commutator electric motor, which is a so-called DC brushless motor. The electric motor 3 is arranged on the downstream side of the diffuser 5. The electric motor 3 is an inner rotor type. The electric motor 3 includes a rotor 16 and a stator 17 that is fixed to the frame 8 and surrounds the rotor 16.

The rotor 16 is rotationally and integrally fixed to the shaft 9. That is, the rotor 16 of the electric motor 3 and the centrifugal fan 2 are rotationally fixed to the shaft 9. The shaft 9 is rotatably supported by the frame 8 via a pair of bearings 18. The rotor 16 is arranged so as to be sandwiched between the pair of bearings 18.

The rotor 16 includes a plurality of magnetic poles arranged in the rotation direction. Each magnetic pole has at least one permanent magnet. The polarities of the magnetic poles alternate in the direction of rotation.

The stator 17 generates a rotating magnetic field (rotating magnetic field) that rotates the rotor 16. The stator 17 includes an iron core 21, an insulator 22, a plurality of windings 23, and terminals 25.

The iron core 21 has a plurality of thin plates laminated and integrated in the axial direction of the shaft 9. The thin plate is, for example, an electromagnetic steel plate. The iron core 21 has a cylindrical shape. The iron core 21 is fixed to the frame 8 with a fastening member 31, for example, a screw.

The insulator 22 is a molded product of a synthetic resin having an insulating property. The insulator 22 insulates between the iron core 21 and the winding 23 and between the iron core 21 and the terminal 25, and supports the winding 23 and the terminal 25.

The plurality of windings 23 form a rotating magnetic field in the iron core 21. The plurality of windings 23 alternately generate magnetic fields having different polarities in the rotation direction of the rotor 16.

The terminal 25 electrically connects each of the windings 23 to the control circuit.

Further, the stator 17 includes a sensor substrate 32. The sensor substrate 32 detects the rotation angle of the rotor 16 by detecting the polarity of the magnetic poles of the rotor 16. The sensor substrate 32 includes, for example, a Hall IC. The sensor substrate 32 faces the rear end surface of the rotor 16, that is, the end surface far from the centrifugal fan 2, and is along the outer circumference of the magnet of the rotor 16. The sensor substrate 32 is fixed to the insulator 22 with a substrate fastening member 33, for example, a screw.

The diffuser 5 decelerates the fluid blown out from the centrifugal fan 2. The diffuser 5 is a resin molded product or a resin molded product, for example, an integrally molded product or an integrally molded product of polyethylene terephthalate resin (PET) containing glass fiber. The diffuser 5 includes a tubular outer frame portion 35, a disk-shaped hub 36 concentrically arranged in the outer frame portion 35, and a plurality of guide vanes 37 erected between the outer frame portion 35 and the hub 36. And have.

The outer frame portion 35 supports the frame 8. The outer frame portion 35 is an outer shell of the diffuser 5 and is a part of the outer shell of the electric blower 1. A groove is provided on the inner surface of the outer frame portion 35 to fit a part of the frame 8 and determine the positional relationship between the outer frame portion 35 and the frame 8.

A recess 38 in which the outer edge of the centrifugal fan 2 is arranged is provided in the central portion of the hub 36. Further, a mounting opening 39 for fitting a part of the frame 8 is provided in the central portion of the hub 36.

The mounting opening 39 penetrates the recess 38 in the longitudinal direction of the shaft 9. A plurality of holes are provided in the vicinity of the mounting opening 39. A fastening member for fixing the diffuser 5 to the frame 8, for example, a screw is inserted into this hole.

The inner diameter of the outer frame portion 35 is larger than the outer diameter of the hub 36. That is, there is an annular gap between the outer frame portion 35 and the hub 36. The annular gap guides the fluid blown out from the centrifugal fan 2 to the electric motor 3.

The plurality of guide vanes 37 integrate the outer frame portion 35 and the hub 36. The plurality of guide vanes 37 have a two-dimensional airfoil. The plurality of guide vanes 37 are provided at intervals in the circumferential direction.

The diffuser 5 may be provided with a plurality of radial guide vanes. A plurality of radial guide vanes are provided on the outer annular portion 41 of the hub 36 at intervals in the circumferential direction. The radial guide vane also has a two-dimensional airfoil. When a plurality of radial guide vanes are provided in the diffuser 5, a plurality of recesses corresponding to the plurality of radial guide vanes are provided on the inner surface of the fan cover 7. Each of the radial guide vanes plunges into their respective recesses and is fixed to the diffuser 5.

Further, the diffuser 5 may be a so-called vaneless diffuser without a guide vane.

The fan cover 7 is a fat-molded product or a resin-molded product, and is, for example, an integrally-molded product or an integrally-molded product of polyethylene terephthalate resin (PET) containing glass fiber. The fan cover 7 covers the centrifugal fan 2 and is adhesively fixed to the diffuser 5.

The fan cover 7 faces the shroud 13 of the centrifugal fan 2 and the blade 12 not covered by the shroud 13. The portion where the fan cover 7 and the shroud 13 face each other is a seal structure 42 that prevents the backflow of air flow by the centrifugal fan 2.

The fan cover 7 has a flat shape with a shaft dimension smaller than the diameter dimension. The outer diameter of the fan cover 7 is substantially equal to the outer diameter of the outer frame portion 35 of the diffuser 5.

The fan cover 7 includes a wall portion 45 that covers the centrifugal fan 2 and the upstream side of the diffuser 5. The wall portion 45 includes a cylindrical first wall 46 having a suction port 6 for guiding a fluid to the centrifugal fan 2, a conical second wall 47 gradually expanding along the shroud 13 and blades 12 of the centrifugal fan 2. It has a thin annular third wall 48 that closes the upstream side of the diffuser 5.

The suction port 6 is a fluid inlet of the electric blower 1 and has a circular opening. The suction port 6 faces the front edge of the blade 12 of the centrifugal fan 2.

The fan cover 7 is fixed to the outer frame portion 35 of the diffuser 5 by an adhesive portion 51 obtained by curing the adhesive. A fan cover 7 covering the upstream side of the centrifugal fan 2 and the diffuser 5 defines a flow path from the fluid inlet of the electric blower 1, that is, the suction port 6, to the fluid outlet, that is, the trailing edges of the plurality of guide vanes 37.

The fan cover 7 has a lightening portion 55 extending from the boundary portion between the second wall 47 and the third wall 48 to the outer surface of the third wall 48. The lightening portion 55 reduces the weight of the fan cover 7. A plurality of lightening portions 55 are provided in the circumferential direction of the fan cover 7. A rib portion 56 extending radially along the radial direction of the fan cover 7 is provided between two adjacent lightening portions 55.

The frame 8 is a molded product or a molded product of a lightweight and conductive metal member such as an aluminum alloy or a magnesium alloy. The frame 8 houses the electric motor 3. The frame 8 rotatably supports the rotor 16 of the electric motor 3 via a pair of bearings 18. The frame 8 supports the stator 17 of the electric motor 3. The frame 8 includes a first frame half body 61 and a second frame half body 62. The frame 8 accommodates the electric motor 3 sandwiched between the first frame half body 61 and the second frame half body 62 from one side and the other side of the shaft 9. The first frame half body 61 and the second frame half body 62 are connected by a fastening member 31, for example, a screw.

The first frame half body 61 is arranged between the centrifugal fan 2 and the electric motor 3.

The first frame half body 61 includes a cylindrical fitting portion 63 that is fitted into the mounting opening 39 of the diffuser 5, and a first bearing holding portion 65 that holds one of the bearings 18 that support the shaft 9. .. The first frame half body 61 has a frame intake port 66 that guides the fluid flowing out of the diffuser 5 to the electric motor 3. The first frame half body 61 has a screw hole 67 for tightening the fastening member 31.

Further, the first frame half body 61 includes a tubular second outer frame portion 68. The second outer frame portion 68 is an outer shell of the frame 8 and is a part of the outer shell of the electric blower 1. The outer frame portion 35 of the diffuser 5 and the second outer frame portion 68 of the frame 8 are a part of the tubular outer shell of the electric blower 1, and are the case 71 of the electric blower 1. The outer frame portion 35 of the diffuser 5 and the second outer frame portion 68 of the frame 8 have substantially the same outer diameter.

A part of the case 71 of the electric blower 1 according to the present embodiment, that is, the outer frame portion 35 is integrated with the diffuser 5, but the outer frame portion 35 is not integrated with the diffuser 5. good. In other words, the case 71 of the electric blower 1 may be integrated with the diffuser 5 or may be a separate body. The case 71 may be a case in which the outer frame portion 35 is separated from the diffuser 5 and the outer frame portion 35 and the second outer frame portion 68 are integrated.

The second frame half body 62 includes a second bearing holding portion 72 that holds the other of the bearings 18 that support the shaft 9. The second frame half body 62 has a hole 73 through which the fastening member 31 is inserted. The second frame half body 62 has a frame exhaust port 75 from which the fluid that cools the electric motor 3 is blown out.

The electric blower 1 is driven by, for example, a driver including an inverter circuit and a control circuit including a control unit that PWM-controls the driver. The terminal 25 and the sensor board 32 are connected to the control circuit. The control circuit switches the magnetic poles generated in the iron core 21 of the stator 17 via each winding 23 every hour by controlling the direction of the current flowing through the winding 23 and the energizing time by the driver.

FIG. 3 is an exploded perspective view of the centrifugal fan of the electric blower according to the present embodiment.

As shown in FIG. 3, the centrifugal fan 2 of the electric blower 1 according to the present embodiment according to the present embodiment includes a shroud 13.

As shown in FIG. 3, the shroud 13 connecting all the blades 12 is a band-shaped ring having a constant length in the direction along the air flow in the centrifugal fan 2.

The shroud 13 connecting some of the blades 12 has a strip shape having a certain length in the direction along the air flow in the centrifugal fan 2, but has an arc shape interrupted at at least one point. There is.

As shown in FIG. 3, the centrifugal fan 2 is an integrally molded product or an integrally molded hub 11 and a plurality of blades 12, and a shroud 13 that is separate from these, for example, integrated by adhesion. Is also good. Further, the centrifugal fan 2 is obtained by integrally molding or integrally molding the hub 11, the plurality of blades 12, and the shroud 13, and may not be disassembled as shown in FIG.

Next, the seal structure 42 of the electric blower 1 will be described. The seal structure 42 of the first example, the seal structure 42A of the second example (hereinafter, simply referred to as “seal structure 42A”), and the seal structure 42B of the third example (hereinafter, simply referred to as “seal structure 42B”). ), The same reference numerals will be given to the same configurations, and duplicate description will be omitted.

FIG. 4 is a cross-sectional view of a first example of the seal structure of the electric blower according to the present embodiment.

As shown in FIG. 4, the seal structure 42 of the first example of the electric blower 1 according to the present embodiment includes a shroud 13 that is closer to the fan cover 7 than the outer peripheral virtual line VL of the plurality of blades 12.

The outer peripheral virtual line VL is a locus of the blades 12 of the rotating centrifugal fan 2.

There is a flow path through which a fluid flows between the blades 12 adjacent to each other in the rotation direction of the centrifugal fan 2. In the portion not covered by the shroud 13, this flow path is open toward the fan cover 7. Therefore, the flow path of this portion can be a backflow path, and does not substantially have a sealing property to prevent backflow due to the negative pressure generated by the centrifugal fan 2. On the other hand, in the portion covered with the shroud 13, this flow path is blocked. The gap between the shroud 13 and the fan cover 7 is narrower than the gap between the plurality of blades 12 and the fan cover 7. Therefore, the gap between the shroud 13 and the fan cover 7 increases the pressure loss against the backflow and reduces the flow rate of the backflow.

Further, the shroud 13 is connected to the front edge 12f of the blade 12. Therefore, the peripheral length of the gap between the shroud 13 and the fan cover 7 (the length in the rotation direction of the centrifugal fan 2) is shorter than when the shroud 13 is separated from the front edge 12f of the blade 12. Further, this circumference is the smallest at the upstream end of the shroud 13. This maximizes the pressure loss for backflow and significantly reduces the backflow flow rate.

Further, the shroud 13 protrudes from the plurality of blades 12 in the suction direction of the centrifugal fan 2. In other words, the end surface 13f on the upstream side of the shroud 13 protrudes from the front edge 12f of the blade 12 in the suction direction of the centrifugal fan 2. This further increases the pressure loss for backflow and further reduces the backflow flow rate, as compared to the case where the upstream end face 13f of the shroud 13 coincides with the front edge 12f of the blade 12.

FIG. 5 is a cross-sectional view of a second example of the seal structure of the electric blower according to the present embodiment.

As shown in FIG. 5, the seal structure 42A of the second example of the electric blower 1 according to the present embodiment includes a fan cover 7A that overlaps the end surface 13f on the upstream side of the shroud 13. That is, the inner diameter Di of the suction port 6 of the fan cover 7A is smaller than the minimum outer diameter Ds_min of the shroud 13.

Therefore, the gap between the fan cover 7A and the shroud 13 increases the flow path length of the gap that prevents backflow and increases the flow path length of the backflow, as compared with the gap between the fan cover 7 and the shroud 13 of the first example. Change the flow direction. This further increases the pressure loss for backflow and further reduces the backflow flow rate.

FIG. 6 is a cross-sectional view of a third example of the seal structure of the electric blower according to the present embodiment.

As shown in FIG. 6, the seal structure 42B of the third example of the electric blower 1 according to the present embodiment includes a fan cover 7B having a recess 81 for arranging the end surface 13f on the upstream side of the shroud 13. That is, the inner diameter of the suction port 6 of the fan cover 7B is smaller than the minimum outer diameter of the shroud 13.

Therefore, the gap between the fan cover 7B and the shroud 13 has a labyrinth structure at the outlet of the backflow. The peripheral length of this labyrinth structure is shorter than the peripheral length of the labyrinth structure located on the outer peripheral side of the centrifugal fan like a conventional electric blower. This maximizes the pressure loss due to the labyrinth structure and significantly reduces the backflow flow rate.

As described above, the electric blower 1 according to the present embodiment includes a shroud 13 that is connected to the front edges of a part or all of the plurality of blades 12 to connect a part or all of the plurality of blades 12, and the shroud 13 is provided. The gap between the fan cover 7 and 7A and 7B is narrower than the gap between the plurality of blades 12 and the fan covers 7, 7A and 7B.

Therefore, the electric blower 1 has an electric blower having an open type centrifugal fan 2 having no shroud 13 and a labyrinth structure for suppressing backflow on the outer side in the radial direction from the inner peripheral end of the shroud 13 of the centrifugal fan 2. Compared with the conventional electric blower arranged, the pressure loss against the backflow can be increased and the flow rate of the backflow can be reduced.

Further, the electric blower 1 reduces the peripheral length of the gap between the shroud 13 and the fan covers 7, 7A and 7B as compared with the case where the shroud 13 is separated from the front edge 12f of the blade 12. Therefore, the electric blower 1 can maximize the pressure loss against the backflow and extremely reduce the flow rate of the backflow as compared with the electric blower having the open type centrifugal fan 2 and the conventional electric blower.

Further, the electric blower 1 according to the present embodiment includes a shroud 13 that protrudes in the suction direction of the centrifugal fan 2 from the plurality of blades 12. Therefore, the electric blower 1 is compared with an electric blower having an open type centrifugal fan 2, a conventional electric blower, and an electric blower in which the end face 13f on the upstream side of the shroud 13 coincides with the front edge 12f of the blade 12. The pressure loss for backflow is further increased to further reduce the backflow flow rate.

Further, the electric blower 1 according to the present embodiment has a fan cover 7A that overlaps the end surface 13f on the upstream side of the shroud 13. Therefore, the electric blower 1 increases the flow path length of the gap between the fan cover 7A and the shroud 13 to prevent the backflow, and changes the flow direction of the backflow to further increase the pressure loss against the backflow. Further reduce the backflow flow rate.

Further, the electric blower 1 according to the present embodiment includes a fan cover 7B having a recess 81 for arranging the end surface 13f on the upstream side of the shroud 13. Therefore, the electric blower 1 can minimize the peripheral length of the labyrinth structure that prevents the backflow of the centrifugal fan 2, maximize the pressure loss due to the labyrinth structure, and extremely reduce the flow rate of the backflow.

Therefore, according to the electric blower 1 according to the present embodiment, the backflow of the centrifugal fan can be prevented more reliably with a structure simpler than that of the electric blower having a conventional labyrinth structure.

Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are also included in the scope of the invention described in the claims and the equivalent scope thereof.

1 ... Electric blower, 2 ... Centrifugal fan, 3 ... Electric motor, 5 ... Diffuser, 6 ... Suction port, 7, 7A, 7B ... Fan cover, 8 ... Frame, 9 ... Shaft, 11 ... Hub, 11a ... Hub hole, 12 ... blades, 12f ... front edge, 12b ... trailing edge, 13 ... shroud, 15 ... retaining part, 16 ... rotor, 17 ... stator, 18 ... bearing, 21 ... iron core, 22 ... insulator, 23 ... winding , 25 ... Terminal, 31 ... Fastening member, 32 ... Sensor board, 33 ... Board fastening member, 35 ... Outer frame, 36 ... Hub, 37 ... Guide vane, 38 ... Recess, 39 ... Mounting opening, 41 ... Outer ring Part, 42, 42A, 42B ... Seal structure, 45 ... Wall part, 46 ... First wall, 47 ... Second wall, 48 ... Third wall, 51 ... Adhesive part, 55 ... Lightening part, 56 ... Rib part, 61 ... First frame half body, 62 ... Second frame half body, 63 ... Cylindrical fitting part, 65 ... First bearing holding part, 66 ... Frame intake port, 67 ... First frame half body hole, 68 ... No. Two outer frame parts, 71 ... case, 72 ... second bearing holding part, 73 ... holes in the second frame half body, 75 ... frame exhaust port, 81 ... recessed parts.

Claims (4)

Centrifugal fan and
A fan cover having a suction port connected to the centrifugal fan and covering the centrifugal fan,
An electric motor for rotationally driving the centrifugal fan is provided.
The centrifugal fan
With a conical hub
A plurality of blades extending from the hub to the fan cover,
A shroud that connects to a part or all of the front edges of the plurality of blades and connects a part or all of the plurality of blades.
An electric blower in which the gap between the shroud and the fan cover is narrower than the gap between the plurality of blades and the fan cover. The electric blower according to claim 1, wherein the shroud protrudes from the plurality of blades in the suction direction of the centrifugal fan. The electric blower according to claim 1 or 2, wherein the fan cover overlaps an end surface on the upstream side of the shroud. The electric blower according to claim 1, wherein the fan cover has a recess for arranging an end face on the upstream side of the shroud.

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