JP7050237B2 - Brushless DC motor - Google Patents

Description

The present disclosure relates to a brushless DC motor provided in a ceiling fan.

Ceiling fans equipped with brushless DC motors are known. For example, Patent Document 1 describes a ceiling fan in which a blade for blowing air is provided at the tip of a cylindrical housing extending downward from the ceiling. This ceiling fan is equipped with a brushless DC motor for rotating the blades. The brushless DC motor has a motor body including a stator and a rotor, and a drive circuit for driving the motor body. The drive circuit is arranged above the motor body in the housing.

Japanese Unexamined Patent Publication No. 2016-03678

In a ceiling fan equipped with a brushless DC motor, it is desirable that the height of the blades from the floor surface be set at a high position from the viewpoint of distributing the air flow over a wide range. Therefore, when the ceiling height is fixed, it is advantageous that the housing of the ceiling fan is short in the vertical direction. In order to shorten the housing vertically, it is necessary to reduce the thickness of the brushless DC motor that combines the motor body and the drive circuit.

The present disclosure has been made to solve the above problems, and an object of the present disclosure is to provide a brushless DC motor capable of reducing the thickness of a ceiling fan.

In order to solve the above problems, the brushless DC motor according to an embodiment of the present invention is a brushless DC motor provided in a ceiling fan, and is fixed to a stator having a stator core around which a coil is wound and a center portion of the stator core. A secondary that converts the voltage supplied by the primary power supply circuit and the primary power supply circuit between the shaft, the bearing, the rotor having a magnet that surrounds the stator core, and the stator core and the bearing in the axial direction. A circuit board having a side power supply circuit and a motor drive circuit that supplies a drive current to the coil based on the power supplied from the secondary side power supply circuit , a board holding portion that holds the circuit board in the stator core, and a board. The board holding section is provided with a heat radiating section that dissipates heat from the motor drive circuit between the holding section and the circuit board, and a support column that holds the circuit board on the surface of the board holding section that is opposite to the stator core. It is located between the stator core and the circuit board, has substantially the same shape as the axial end of the stator core in the axial view, and the support column holds the heat dissipation part and the circuit board.

It should be noted that the expression of the present disclosure converted between methods, devices, systems, recording media, computer programs and the like is also effective as an aspect of the present disclosure.

According to the present disclosure, it is possible to provide a brushless DC motor capable of reducing the thickness of a ceiling fan.

FIG. 1 is a perspective view showing a ceiling fan provided with a motor according to an embodiment. FIG. 2 is a cross-sectional view showing the peripheral structure of the motor of FIG. FIG. 3 is an exploded perspective view of the motor of FIG. FIG. 4 is a side view showing the stator of the motor of FIG. FIG. 5 is a bottom view showing the circuit board of the motor of FIG. FIG. 6 is a block diagram showing the configuration of the circuit board of the motor of FIG. FIG. 7 is a perspective view of the substrate holding portion of the motor of FIG. 1 as viewed from the stator core side. FIG. 8 is a cross-sectional view taken along the line AA showing the relationship between the substrate holding portion and the stator core. FIG. 9 is an enlarged view of a portion B showing a positioning protrusion of the substrate holding portion and an opening of the stator core. FIG. 10 is a perspective view of the board holding portion as viewed from the circuit board side. FIG. 11 is an exploded perspective view showing the relationship between the heat radiation portion of the stator and the circuit board. 12A and 12B are a plan view (a) and a cross-sectional view taken along the line CC (b) showing a state in which the lead wire is held by the stator. FIG. 13 is a cross-sectional view taken along the line DD showing a state in which the substrate holding portion and the circuit board sandwich the heat radiating portion.

Hereinafter, embodiments for carrying out the present disclosure will be described with reference to the accompanying drawings. In the embodiments and modifications, the same or equivalent components and members are designated by the same reference numerals, and duplicate description thereof will be omitted as appropriate. Further, the dimensions of the members in each drawing are shown in an appropriately enlarged or reduced size for easy understanding. In addition, some of the members that are not important for explaining the embodiment in each drawing are omitted and displayed.

Also, terms including ordinal numbers such as 1st and 2nd are used to describe various components, but this term is used only for the purpose of distinguishing one component from other components, and this term is used. The components are not limited by.

The motor 10 according to the embodiment of the present disclosure is a brushless DC motor provided in the ceiling fan 1. First, the overall configuration of the ceiling fan 1 will be described. FIG. 1 is a perspective view showing a ceiling fan 1. The ceiling fan 1 is attached to the ceiling 4 and functions as a fan having a plurality of blades 2 that generate an air flow by rotating. The ceiling fan 1 includes a motor 10 for rotating a plurality of blades 2 and a housing 5 extending downward from the ceiling 4 and surrounding the motor 10. The ceiling fan 1 is provided with a lighting unit 3 having a light emitting element such as an LED at the lower end thereof.

The housing 5 has a substantially conical first portion 5a whose diameter gradually decreases downward from the ceiling side, and a substantially conical second portion whose diameter gradually increases downward from the lower portion of the first portion 5a. Has 5b and. The connecting portion 5c of the first portion 5a and the second portion 5b is narrowed down more than the first portion 5a and the second portion 5b. The lower part of the second portion 5b exhibits a cylindrical shape having a constant diameter. The second portion 5b functions as an outer shell that houses the motor 10.

2 to 4 will be referred to. FIG. 2 is a cross-sectional view showing the peripheral structure of the motor 10 of the ceiling fan 1. FIG. 3 is an exploded perspective view of the motor 10. FIG. 4 is a side view showing the stator 20. The motor 10 mainly includes a stator 20, a shaft 30, a rotor 40, a first bearing 32, a second bearing 34, a circuit board 48, a blade holder 70, and a rotation detection unit 400. Hereinafter, the direction along the central axis La of the shaft 30 is referred to as "axial direction", and the circumferential direction and the radial direction of the circle centered on the central axis La are referred to as "circumferential direction" and "diametrical direction", respectively. Further, hereinafter, for convenience, one side (upper side in the figure) in the axial direction is referred to as "upper" and "upper", and the other side (lower side in the figure) is referred to as "lower" and "lower". The notation in such a direction does not limit the posture in which the motor 10 is used, and the motor 10 can be used in any posture.

First, the operation of the motor 10 and the ceiling fan 1 will be described. In the ceiling fan 1, the stator 20, the shaft 30, the circuit board 48, and the rotation detection unit 400 form a stationary body, and the rotor 40, the blade holder 70, and the plurality of blades 2 form a rotating body. The circuit board 48 supplies a drive current to the stator 20 based on the detection signal of the rotation detection unit 400. The stator 20 generates a rotating magnetic field according to the driving current. The rotor 40 rotates around the central axis La according to the rotating magnetic field. The blade holder 70 rotates a plurality of blades 2 by rotating integrally with the rotor 40. The plurality of blades 2 rotate to generate a downward air flow. Hereinafter, each part will be described in detail.

The first bearing 32, the rotor 40 and the stator 20, the circuit board 48, and the second bearing 34 are arranged in this order from top to bottom and surround the shaft 30. The rotor 40 is arranged so as to face the stator 20 in the radial direction. The rotor 40 and the stator 20 have a larger diameter than the first bearing 32, and the circuit board 48 has a larger diameter than the rotor 40 and the stator 20. The shaft 30 is a pipe-shaped member having a hollow portion in the center for passing a wire for wiring. The hollow portion of the shaft 30 penetrates up and down, and a horizontal hole 30h for passing a wire is provided on the side surface of the shaft 30.

The stator 20 has a stator core 22 around which the coil 24 is wound. The coil 24 constitutes a three-phase armature coil. The shaft 30 is fixed to the central portion of the stator core 22. The rotor 40 has a magnet 42 that surrounds the stator core 22 and is fixed to the outer ring of the first bearing 32.

The stator core 22 has a plurality of (for example, 12) teeth portions 22t and a plurality of slots 22s provided between the plurality of teeth portions 22t. The side surface of each slot 22s leads to the opening 22k of the stator core 22. An insulating sheet 23 made of a resin film is inserted into each slot 22s. The insulating sheet 23 includes a slot insulator 23b that covers the inner side surface (the surface on the slot 22s side) of the teeth portion 22t, and a slot key 23c provided on the outer peripheral side of the slot 22s. The insulating sheet 23 of this example protrudes in the axial direction from the end surface of the tooth portion 22t. Insulating members 200 are provided on the upper surface and the lower surface of the stator core 22, respectively. The insulating member 200 functions as a core cover that covers a part of each tooth portion 22t. The insulating member 200 is a resin member formed by molding.

The coil 24 includes a plurality of (for example, 12) coil main body portions 24a wound around each tooth portion 22t. The plurality of coil main bodies 24a are connected in series for each phase. The terminal of the coil main body portion 24a of each phase is connected to a motor drive circuit described later.

The rotor 40 has a rotor yoke 44. The rotor yoke 44 includes a hollow disk-shaped top plate portion 44a, a cylindrical magnet support portion 44b extending downward from the outer peripheral portion of the top plate portion 44a, and a donut extending radially outward from the lower portion of the magnet support portion 44b. It has an extension portion 44c in the shape of an extension. The central portion of the top plate portion 44a is fixed to the outer ring of the first bearing 32. The magnet 42 is fixed to the inner peripheral surface of the magnet support portion 44b. The outer peripheral portion of the extending portion 44c is fixed to the blade holder 70 by the male screw S1.

The magnet 42 has a plurality of (for example, 10) magnetic poles that supply field magnetic flux to the stator core 22. The magnet 42 is divided into a plurality of segments. As shown in FIG. 4, the upper end and the lower end of the magnet 42 extend up and down by a predetermined dimension (for example, 5 mm) of the stator core 22.

As shown in FIG. 3, the rotor 40 has a magnet holder 300 that holds the magnet 42 in a predetermined position. The magnet holder 300 is arranged above and below the magnet 42 to limit the axial position of the magnet 42. The magnet holder 300 includes a first holder 310 arranged on the lower side of the magnet 42 and a second holder 320 arranged on the upper side of the magnet 42. The outer peripheral portion of the first holder 310 is locked to the rotor yoke 44, which limits the downward movement of the magnet 42. The second holder 320 limits the upward movement of the magnet 42. The first holder 310 and the second holder 320 are substantially ring-shaped resin members that can be elastically deformed.

As shown in FIG. 2, the first bearing 32 and the second bearing 34 are rolling bearings having a rolling element 33 such as a ball. The inner rings of the first bearing 32 and the second bearing 34 are fixed to the shaft 30 via the E washers 32c and 34c. The first bearing 32 and the second bearing 34 are arranged vertically apart from each other with the stator core 22 and the circuit board 48 interposed therebetween. The first bearing 32 is arranged above the stator core 22. The second bearing 34 is arranged below the circuit board 48 on the opposite side of the stator core 22 from the first bearing 32.

5 and 6 are also referred to. FIG. 5 is a bottom view showing the circuit board 48. FIG. 6 is a block diagram showing the configuration of the circuit board 48. The circuit board 48 includes a wiring board 50, a primary power supply circuit 51, a secondary power supply circuit 52, and a motor drive circuit 53. The primary side power supply circuit 51, the secondary side power supply circuit 52, and the motor drive circuit 53 are provided on the wiring board 50. The wiring board 50 is a printed wiring board (Printed Circuit Board).

The primary power supply circuit 51 rectifies the input AC voltage (for example, 220V to 240V) and supplies the first DC voltage V1 (for example, 310V to 340V). The secondary power supply circuit 52 supplies a second DC voltage V2 of 15 V and a third DC voltage V3 of 5 V by the DC-DC converters 52a and 52b based on the first DC voltage.

The motor drive circuit 53 includes a microprocessor 53a, a control unit 53b, and a switching unit 53c, and supplies a drive current to the coil 24. The first DC voltage V1 is mainly supplied to the switching unit 53c. The second DC voltage V2 is mainly supplied to the control unit 53b.
The third DC voltage V3 is mainly supplied to the microprocessor 53a. The control unit 53b generates an FG signal based on the position signals Hs acquired from the Hall elements HE1, HE2, and HE3 of the rotation detection unit 400, and outputs the FG signal to the microprocessor 53a.

The microprocessor 53a generates a rotation control signal Cs for controlling the rotation of the motor 10 based on the FG signal output from the control unit 53b, and outputs the rotation control signal Cs to the control unit 53b. The control unit 53b generates a phase switching signal Qs for energizing phase switching based on the position signal Hs acquired from the Hall element of the rotation detection unit 400. The control unit 53b generates a PWM signal Ps based on the rotation control signal Cs output from the microprocessor 53a and the phase switching signal Qs, and outputs the PWM signal Ps to the switching unit 53c.

The switching unit 53c includes a switching element (not shown) constituting the three-phase bridge. The switching unit 53c controls the continuity / non-passage of the switching element based on the PWM signal Ps output from the control unit 53b, and causes a drive current to flow through the coil 24. The control unit 53b and the switching unit 53c form a three-phase inverter. The switching unit 53c of this embodiment is realized by a one-chip motor drive IC.

As shown in FIG. 5, the circuit board 48 of this embodiment communicates with the sub-wiring board 49, the lighting drive circuit 55 for driving the lighting unit 3, and the remote controller (not shown) for remotely controlling the ceiling fan 1. Further includes a communication circuit 56. The illumination drive circuit 55 is provided on the sub wiring board 49, and the communication circuit 56 is provided on the wiring board 50. The sub wiring board 49 is a printed wiring board.

As shown in FIG. 4, the circuit board 48 has a ring shape surrounding the shaft 30 and is provided between the stator core 22 and the second bearing 34 in the axial direction. The circuit board 48 is supported by the stator core 22 by fixing the wiring board 50 to the stator core 22 via the board holding portion 100. The substrate holding portion 100 is located between the stator core 22 and the circuit board 48, and has substantially the same shape as the axial end portion of the stator core 22 in the axial view. As a result, the insulation distance between the coil 24 wound around the stator core 22 and the circuit board 48 can be secured, so that the insulation safety can be kept high and the thickness can be reduced. The sub-wiring board 49 is fixed to the lower surface of the wiring board 50 via the board holder 60. As shown in FIG. 5, the wiring board 50 is a ring-shaped circular member having a central hole 50h, and the sub-wiring board 49 is a partial member in the ring shape.

As shown in FIG. 5, a wiring connection component 58 such as a connector for connecting wiring is mounted on the lower surface 50j of the wiring board 50 on the side opposite to the stator core 22. The wiring connection component 58 in this example is a male connector. As a result, at the time of assembling the motor 10, the female connector to which the lead wire is connected to the wiring connection component 58 can be easily attached / detached while the circuit board 48 is fixed to the stator core 22 via the substrate holding portion 100. Assembly workability and maintainability are improved. Further, since the wiring board 50 can be brought close to the stator core 22, it is advantageous for thinning.

As shown in FIG. 4, the electronic component 51p constituting the primary side power supply circuit 51 is mounted on the lower surface 50j of the wiring board 50 on the side opposite to the stator core 22. As a result, the heat generated in the electronic component 51p is blocked by the wiring board 50, so that heat conduction to the stator 20 and the rotor 40 is reduced, the temperature rise of the coil 24 is suppressed, and quality deterioration can be prevented.

As shown in FIG. 3, a heat radiating section 46 that dissipates heat from the motor drive circuit 53 is provided between the board holding section 100 and the wiring board 50. The heat radiating unit 46 promotes heat dissipation from the motor drive IC (switching unit 53c) of the motor drive circuit 53 and suppresses the temperature rise.

As shown in FIG. 4, the rotation detection unit 400 includes Hall elements HE1, HE2, HE3 for detecting the magnetic flux of the magnet 42, and a HE holder 410. The Hall elements HE1, HE2, and HE3 are arranged at positions deviated by 120 degrees in the electrical angle in the circumferential direction. The Hall element HE2 is arranged at a position of a predetermined opening 22k (hereinafter referred to as an opening 22k (H)) in the circumferential direction. The input / output terminals of the Hall elements HE1, HE2, and HE3 are connected to the circuit board 48. The output signals of the Hall elements HE1, HE2, and HE3 are input to the control unit 53b. The HE holder 410 is a member that supports the Hall elements HE1, HE2, and HE3, is held by the substrate holding portion 100, and is sandwiched and fixed between the wiring board 50 and the stator core 22. The HE holder 410 has a convex portion 420 that projects upward and engages the opening 22k (H).

As shown in FIG. 2, the blade holder 70 rotates integrally with the rotor 40 and transmits the rotation of the rotor 40 to a plurality of (for example, five) blades 2. The blade holder 70 is a hollow circular member, and is radially inward from the holder cylindrical portion 70a, the trumpet-shaped portion 70b extending downward from the lower portion of the holder cylindrical portion 70a, and the lower portion of the holder cylindrical portion 70a. It has a hollow disk-shaped holder disk portion 70c extending and a holder flange portion 70d extending radially outward from the lower portion of the trumpet-shaped portion 70b.

As shown in FIG. 2, the upper portion of the holder cylindrical portion 70a is fixed to the extending portion 44c of the rotor yoke 44. The holder cylindrical portion 70a surrounds the circuit board 48 with a gap. The outer ring of the second bearing 34 is fixed to the center of the holder disk portion 70c. A plurality of blades 2 are fixed to the holder flange portion 70d. The plurality of blades 2 are arranged at predetermined intervals in the circumferential direction and extend radially outward from the holder flange portion 70d. The lower portion of the trumpet-shaped portion 70b surrounds the upper portion of the illumination portion 3 with a gap. The upper part of the illumination unit 3 is fixed to the lower part of the shaft 30.

The surface 102 (upper surface) of the substrate holding portion 100 facing the stator core 22 will be described with reference to FIGS. 4, 7, and 8. FIG. 7 is a perspective view of the substrate holding portion 100 as viewed from the stator core 22 side. FIG. 8 is a cross-sectional view taken along the line AA showing the relationship between the substrate holding portion 100 and the stator core 22. The substrate holding portion 100 is a substantially disk-shaped member made of resin, and is provided between the stator core 22 and the circuit board 48 to hold the circuit board 48.

As shown in FIG. 7, a hollow cylindrical cylindrical portion 120 extending vertically is provided at the center of the substrate holding portion 100. The cylindrical portion 120 circumscribes the outer peripheral surface of the shaft 30. As a result, since the cylindrical portion 120 extends vertically, the contact area with the shaft 30 increases, and the substrate holding portion 100 and the wiring board 50 can be held on a surface orthogonal to the shaft 30. As a result, the components of the primary power supply circuit 51 and the motor drive circuit 53 can be stably held. As shown in FIG. 7, the cylindrical portion 120 is provided with two slits 122 notched with a width of approximately 30 ° at intervals of 180 ° in the circumferential direction.

As shown in FIG. 7, a plurality of positioning protrusions 110 are provided on the surface 102 of the substrate holding portion 100 facing the stator core 22. The positioning projection 110 extends upward from the outer peripheral portion of the substrate holding portion 100. In this example, the four positioning protrusions 110 are arranged at intervals of 90 ° in the circumferential direction. At the base of each positioning protrusion 110, a seat portion 112 with which the stator core 22 abuts is provided. Each positioning protrusion 110 vertically engages with an opening 22k provided on the side surface of the stator core 22. As a result, the positioning accuracy of the substrate holding portion 100 and the wiring board 50 with respect to the stator core 22 is improved.

As shown in FIG. 4, the positioning projection 110 is provided at least at a position near the Hall elements HE1, HE2, and HE3 and a position on the opposite side of the peripheral position in the circumferential direction (position separated by 180 ° in the circumferential direction). .. As a result, the positional relationship between the wiring board 50 and the Hall elements HE1, HE2, and HE3 is stabilized. Further, since the number of the positioning protrusions 110 can be reduced, the mold for manufacturing the substrate holding portion 100 can be simplified, and the amount of resin can be reduced. The position near the Hall elements HE1, HE2, and HE3 is the position of the opening 22k (A) adjacent to the opening 22k (H) corresponding to the Hall element HE2.

As shown in FIG. 7, a plurality of (for example, 12) radial ribs 130 are provided on the surface 102 of the substrate holding portion 100 facing the stator core 22. This makes it possible to increase the strength of the substrate holding portion 100, which is advantageous for reducing the thickness. The radial rib 130 extends radially outward from the outer circumference of the cylindrical portion 120. In this example, twelve radial ribs 130 are arranged at 30 ° intervals in the circumferential direction. As shown in FIG. 8, the radial rib 130 is located at the center of each slot 22s in the circumferential direction so as to avoid the coil 24 in a plan view. In other words, the position avoiding the coil 24 is an intermediate position between the adjacent coils 24 in a plan view, and is a position corresponding to the space provided between the adjacent coils 24. As a result, interference between the radial rib 130 and the coil 24 can be avoided, which is advantageous for reducing the thickness of the substrate holding portion 100.

On the outer peripheral side of the surface 102 of the substrate holding portion 100 facing the stator core 22, the outer peripheral diameter of the stator core 22 and the outer peripheral diameter are substantially the same, and a hollow annular rib 140 is provided. Thereby, the strength on the outer peripheral side of the substrate holding portion 100 can be improved. Further, it is possible to suppress the floating of the positioning protrusion 110 due to the deformation of the substrate holding portion 100. The circumferential rib 140 extends in a circumferential shape to connect the positioning protrusions 110.

FIG. 9 is an enlarged view of a portion B showing an opening 22k of the positioning protrusion 110 and the stator core 22. As shown in FIG. 9, the positioning projection 110 has a tapered shape along the inner wall surface 22m of the opening 22k in a plan view. As a result, the protrusion of the positioning protrusion 110 from the opening 22k to the outside in the radial direction is restricted, and contact with the rotor 40 can be prevented. In the example of FIG. 9, the wall surface 22m is a peripheral end surface of the teeth portion 22t, and is a wall surface extending inward in the radial direction from the outer peripheral side of the opening portion 22k of the teeth portion 22t. That is, the wall surface 22m is a wall surface extending inward in the radial direction from the opening 22k of the stator core 22.

With reference to FIGS. 10 to 13, the surface 150 of the substrate holding portion 100 opposite to the stator core 22 will be described. FIG. 10 is a perspective view of the substrate holding portion 100 as viewed from the circuit board 48 side. FIG. 11 is an exploded perspective view showing the relationship between the heat radiating portion 46 of the stator 20 and the circuit board 48. 12A and 12B are a plan view (a) and a cross-sectional view taken along the line CC (b) showing a state in which the lead wire 154 is held by the stator 20. FIG. 13 is a cross-sectional view taken along the line DD showing a state in which the substrate holding portion 100 and the circuit board 48 sandwich the heat radiating portion 46. In order to explain the assembly workability, in FIGS. 10 to 13, the floor surface (lower side) is shown as the upper side (upper side) of the drawing.

As shown in FIG. 10, a plurality of support columns 151 for holding the circuit board 48 are provided on the surface 150 of the substrate holding portion 100 opposite to the stator core 22. The support column portion 151 extends upward from the outer peripheral portion of the substrate holding portion 100. In this example, the four strut portions 151 are arranged at intervals of 90 ° in the circumferential direction. The strut portion 151 holds the heat radiating portion 46 and the circuit board 48. The strut portion 151 shares the central axis and includes two arrangement surfaces 151a and 151b having different radial lengths and axial heights from the central axis. Further, a lead wire holding portion 155 for holding a plurality of lead wires 154 connected on the circuit board 48 through the hollow space of the shaft 30 is provided.

As shown in FIG. 11, the heat radiating portion 46 includes a thin plate-shaped heat sink 46h, an insulating film 46f, and a heat radiating gel sheet 46g made of silicon having high thermal conductivity. As a result, the motor drive IC (switching unit 53c) of the motor drive circuit 53 mounted on the wiring board 50 of the circuit board 48 is thermally connected to the heat sink 46h via the heat dissipation gel sheet 46g.

As shown in FIG. 12, the end portion of the lead wire holding portion 155 opposite to the stator core 22 penetrates the notched inner peripheral side space 50k of the circuit board 48 and is the primary side power supply in the circuit board 48. It extends to the arrangement surface 50j of the circuit 51. As a result, when assembling the motor 10, the lead wire 154 is not held by the circuit board 48, but is held by the lead wire holding portion 155 of the board holding portion 100 that penetrates the lead wire 154, so that the lead wire 154 is held by the circuit board 48. It can be easily wired. Therefore, assembly workability and maintainability are improved. Further, since the wiring board 50 can be brought close to the stator core 22, the thickness can be reduced.

As shown in FIG. 13, the heat radiating portion 46 is arranged on one of the arrangement surfaces 151a of the support column 151, and the circuit board 48 is arranged on the other arrangement surface 151b. Here, the arrangement surface 151a is the same as the surface 150, but it may be arranged between the surface 150 and the arrangement surface 151b. The support column portion 151 has a substantially cylindrical shape having a hole for fastening the circuit board 48 from above with a male screw S2. The outer diameter of the arrangement surface 151a of the support column 151 is larger than the outer diameter of the arrangement surface 151b. As a result, the heat radiating unit 46 can be reliably held in a predetermined position.

By having the heat radiating unit 46, heat radiating is promoted and the temperature rise of the motor drive IC is suppressed. Further, with this configuration, the heat sink 46h can be arranged in a narrow space, which is advantageous for thinning. Since the temperature rise of the motor drive IC is suppressed, the output of the motor 10 can be increased accordingly to increase the air volume of the ceiling fan 1.

According to this embodiment, the motor 10 can be easily made thinner. The blade 2 of the ceiling fan 1 can be arranged at a high position according to the thickness of the motor 10. As a result, the downward air flow can be spread over a wide range, so that the unevenness of the air volume near the floor can be reduced and the comfort can be improved. In addition, interference with humans can be avoided. Further, by making the motor 10 thinner, the connection portion 5c of the housing 5 can be made thinner, so that the air flow guided to the blade 2 becomes smooth at this portion, which is advantageous in reducing power consumption.

The outline of one aspect of the present disclosure is as follows. The brushless DC motor (10) of the present disclosure is a brushless DC motor provided in the ceiling fan (1), and has a stator (20) having a stator core (22) around which a coil (24) is wound, and a stator core. A shaft (30) fixed to the center of (22), a bearing (34), a rotor (40) having a magnet (42) surrounding the stator core (22), and a stator core (22) in the axial direction. Between the bearing (34), the primary side power supply circuit (51), the secondary side power supply circuit (52) that converts the voltage supplied from the primary side power supply circuit (51), and the secondary side power supply circuit. It comprises a circuit board (48) having a motor drive circuit (53) that supplies a drive current to the coil (24) based on the power supplied from (52).

The brushless DC motor (10) further includes a substrate holding portion (100) for holding the circuit board (48) on the stator core (22), and the substrate holding portion (100) includes the stator core (22) and the circuit board (48). It may be located between the above and have substantially the same shape as the axial end portion of the stator core (22) in the axial view.

The substrate holding portion (100) may have a cylindrical portion (120) circumscribing the outer peripheral surface of the shaft (30).

A heat radiating section (46) that dissipates heat from the motor drive circuit (53) may be provided between the board holding section (100) and the circuit board (48).

A support column (151) for holding the circuit board (48) is provided on the surface (150) of the substrate holding portion (100) opposite to the stator core (22), and the support column (151) is a heat dissipation unit (46). And the circuit board (48) may be held.

The strut portion (151) has two arrangement surfaces (151a) and an arrangement surface (151b) that share a central axis and have different radial lengths from the central axis and different axial heights, and one of them. The heat radiating portion (46) may be arranged on the arrangement surface (151a), and the circuit board (48) may be arranged on the other arrangement surface (151b).

A wiring connection component (58) for connecting wiring may be provided on the surface (50j) of the circuit board (48) opposite to the stator core (22).

An electronic component (51p) constituting the primary power supply circuit (51) may be provided on the surface (50j) of the circuit board (48) opposite to the stator core (22).

A plurality of lead wires (154) connected on the circuit board (48) through the hollow space of the shaft (30) on the surface (150) of the board holding portion (100) opposite to the stator core (22). The lead wire holding portion (155) for holding is provided, and the end portion of the lead wire holding portion (155) opposite to the stator core (22) penetrates the inner peripheral side space (50k) of the circuit board (48). It may be extended to the arrangement surface (50j) of the primary side power supply circuit (51) on the circuit board (48).

The substrate holding portion (100) may have a positioning projection (110) that engages with the opening (22k) of the stator core (22).

The positioning projection (110) may be provided at a position near the Hall element (HE1, HE2, HE3) that detects the magnetic flux of the magnet (42) and a position opposite to the circumferential direction of the position.

The positioning projection (110) may have a shape along the wall surface (22 m) of the opening (22 k).

A radial rib (130) may be provided at a position avoiding the coil (24) on the surface (102) of the substrate holding portion (100) facing the stator core (22).

A circumferential rib (140) may be provided on the outer peripheral side of the surface (102) of the substrate holding portion (100) facing the stator core (22).

The present disclosure has been described above based on the examples. It will be appreciated by those skilled in the art that this embodiment is exemplary and that various variations of each of these components or combinations of processing processes are possible and that such modifications are also within the scope of the present disclosure. ..

1 ceiling fan, 4 ceiling, 5 housing, 10 motor, 20 stator, 22 stator core, 24 coil, 30 shaft, 32 1st bearing, 34 2nd bearing, 40 rotor, 42 magnet, 46 heat sink, 46g heat sink, 46f Insulation film, 46h heat sink, 48 circuit board, 50 wiring board, 51 primary side power supply circuit, 52 secondary side power supply circuit, 53 motor drive circuit, 58 wiring connection parts, 60 board holder, 100 board holder, 110 positioning Projections, 130 radial ribs, 140 circumferential ribs, 151 strut parts, 151a placement surface, 151b placement surface, 154 lead wires, 155 lead wire holding parts, 400 rotation detection parts.

Claims (11)

A brushless DC motor installed in a ceiling fan.
A stator with a stator core around which a coil is wound, and a stator
A shaft fixed to the center of the stator core and
Bearings and
A rotor having a magnet surrounding the stator core, and
It is supplied from the primary side power supply circuit, the secondary side power supply circuit that converts the voltage supplied from the primary side power supply circuit, and the secondary side power supply circuit between the stator core and the bearing in the axial direction. A circuit board having a motor drive circuit that supplies a drive current to the coil based on the electric power
A board holding portion that holds the circuit board in the stator core,
A heat radiating section that dissipates heat from the motor drive circuit between the board holding section and the circuit board.
A support column for holding the circuit board is provided on the surface of the substrate holding portion on the side opposite to the stator core.
The substrate holding portion is located between the stator core and the circuit board, and has substantially the same shape as the axial end portion of the stator core in an axial view.
The strut portion
A brushless DC motor that holds the heat dissipation unit and the circuit board . The brushless DC motor according to claim 1 , wherein the substrate holding portion has a cylindrical portion circumscribing the outer peripheral surface of the shaft. The strut portion
It has two arrangement surfaces that share a central axis and have different radial lengths and axial heights from the central axis.
The heat radiating portion is arranged on one of the arranged surfaces, and the heat radiating portion is arranged.
The brushless DC motor according to claim 1 , wherein the circuit board is arranged on the other arrangement surface. The brushless DC motor according to any one of claims 1 to 3 , wherein a wiring connection component for connecting wiring is provided on a surface of the circuit board opposite to the stator core. The brushless DC motor according to any one of claims 1 to 4 , wherein an electronic component constituting the primary power supply circuit is provided on a surface of the circuit board opposite to the stator core. On the surface of the substrate holding portion on the side opposite to the stator core,
A lead wire holding portion for holding a plurality of lead wires connected on the circuit board through the hollow space of the shaft is provided.
The end of the lead wire holding portion on the opposite side of the stator core
The brushless DC motor according to claim 5 , wherein the brushless DC motor penetrates the inner peripheral space of the circuit board and extends to the arrangement surface of the primary power supply circuit in the circuit board. The brushless DC motor according to any one of claims 1 to 6 , wherein the substrate holding portion has a positioning protrusion that engages with an opening of the stator core. The brushless DC motor according to claim 7 , wherein the positioning protrusion is provided at a position near the Hall element that detects the magnetic flux of the magnet and a position opposite to the circumferential direction of the position. The brushless DC motor according to claim 7 or 8 , wherein the positioning protrusion has a shape along the wall surface of the opening. The brushless DC motor according to any one of claims 1 to 9 , wherein a radial rib is provided at a position of the substrate holding portion facing the stator core so as to avoid the coil. The brushless DC motor according to any one of claims 1 to 10 , wherein a circumferential rib is provided on the outer peripheral side of the surface of the substrate holding portion facing the stator core.

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