outer rotor motor

Abstract

An outer rotor type motor that can be easily assembled and that can reliably achieve axial and rotational positioning of a stator and a motor board with a simple configuration. [Solution] A cylindrical portion 7a extending in the axial direction radially inside an insulator 7 covering a stator core 5a has snap fits 7b provided at multiple locations around the circumferential direction of the cylindrical portion 7a, which are inserted into through holes in a motor board 6 and engage with locking recesses formed in the wall surface of the through hole to position and hold the motor board 6 in the axial and radial directions relative to the stator 5, and the stator 5 is concentrically assembled to the outer periphery of a housing storage portion 4d that stores a bearing housing 8a, with the motor board 6 positioned and held by the snap fits 7b.

Description

[Technical Field]

[0001] The present invention relates to an outer rotor motor used as a drive source for, for example, in-vehicle equipment or HVAC (heating, ventilation, and air conditioning) equipment. [Background technology]

[0002] For example, in an outer rotor brushless motor, a motor board equipped with a Hall IC (magnetic pole detection element) that detects the rotor magnetic pole position using a permanent magnet is positioned and fixed on a housing that has a bearing storage section, and a spacer that stores the Hall element is positioned and fixed on the motor board. The lead terminals of the Hall IC are soldered to the motor board. A stator core, with motor coils wound around the stator pole teeth, is attached to the spacer. Finally, the housing, motor board, and stator core are fastened together with screws, and the Hall IC, stator core, and motor board are positioned relative to each other and assembled (Patent Document 1; JP 10-191612 A).

[0003] A cylindrical bearing housing is fixed to the base, and a motor board assembled around the bearing housing is inserted into and locked with hooks protruding from the insulator. Hooks protrude axially from the insulator at positions corresponding to the tips of the stator pole teeth, and are inserted into and locked with the holes in the motor board. The lead terminals of the stator winding are soldered to the motor board (Patent Document 2; JP 9-252557 A). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 10-191612 [Patent Document 2] Japanese Patent Application Publication No. 9-252557 Summary of the Invention [Problem to be solved by the invention]

[0005] In the above-mentioned Patent Document 1, the Hall IC is housed and assembled between the motor board and the stator core via a spacer, which results in a large number of parts and increases the size in the axial direction. In addition, the number of processing and assembly steps required to position the housing, motor board, spacer, and stator core increases, resulting in higher manufacturing costs.

[0006] Furthermore, in the configuration of Patent Document 2, in which the motor board is held by a hook protruding from the insulator, the assembly posture of the motor board relative to the rotor shaft, i.e., the axial perpendicularity, is easily affected, which may cause variations in the position of the Hall IC relative to the rotor magnetic poles and result in degraded motor performance. In particular, motors used in automotive equipment are subject to external vibrations depending on the operating environment in addition to rotational vibrations, which can cause misalignment of the stator and motor board in the axial and rotational directions. This can lead to cracks in the solder joints between the lead terminals of the motor coil and the board terminals of the motor board. Furthermore, a misalignment of the Hall IC by 1° in mechanical angle results in a misalignment of the Hall IC detection signal by 3° in electrical angle, resulting in degraded motor controllability. [Means for solving the problem]

[0007] The present invention has been made to solve these problems, and its purpose is to provide an outer rotor type motor that is easy to assemble and has a simple configuration that ensures reliable axial and rotational positioning of the stator and motor board.

[0008] In order to achieve the above object, the present invention has the following configuration. an outer rotor motor including a stator in which stator poles are formed by windings wound via an insulator around a plurality of pole teeth protruding from a stator core; and a rotor in which rotor poles made of permanent magnets are arranged radially outside the stator opposite the stator poles, and a motor board on which magnetic pole detection elements are provided to detect the position of the rotor magnetic poles, wherein a cylindrical portion extending axially on the radial inside of the insulator covering the stator core has snap fits provided at multiple locations around the cylindrical portion to be inserted into through holes in the motor board and engage with locking recesses formed in the wall surface of the through hole to position and hold the motor board axially and radially relative to the stator, and the stator is concentrically assembled to the outer periphery of a housing storage portion that stores a bearing housing, with the motor board positioned and held by the snap fits. In this way, multiple snap fits protruding circumferentially from the cylindrical portion of the insulator are inserted into the through holes of the motor board and engage with the locking recesses formed in the wall surface of the through holes to hold the motor board, thereby positioning the motor board axially relative to the stator and also positioning the motor board rotationally relative to the stator.

[0009] It is preferable that the snap fit has a retaining portion protruding from the cylindrical portion of the insulator, which is tapered with a radially inner tapered portion and a radially outer tapered portion, and is engaged with the motor board by a stepped portion protruding radially outward from the radially outer tapered portion. As a result, when assembling the stator and motor board, the radially outward tapered portion of the snap fit holding portion is guided by the peripheral edge of the through hole in the motor board, deforming radially inward while engaging with the opposite surface of the board at the stepped portion, so the motor board can be positioned and held on the stator. Also, when assembling the stator (stator assembly) with the assembled motor board concentrically to the outer periphery of the housing accommodating portion that houses the bearing housing, the radially inward tapered portion of the snap fit is guided by the open end of the housing accommodating portion and deforming radially outward, avoiding interference with the housing accommodating portion, making it easy to assemble the stator into the housing.

[0010] The snap fits are preferably provided to protrude between the stator pole teeth in the circumferential direction of the cylindrical portion. When the snap fits are provided between the stator pole teeth in this way, the snap fits do not affect the winding operation of a winding machine when winding the motor coil around the stator pole teeth.

[0011] An abutting member may be provided between the snap fits of the cylindrical portion, the abutting member being abutted against the motor board surface in the axial direction and sandwiching the motor board together with the snap fits to determine the axial position. As a result, when assembling the stator and motor board, the cylindrical part of the insulator is inserted into the through hole of the motor board, and the abutment member abuts against the upper surface of the board, and when the snap fit is inserted into the through hole, the retaining part engages with the lower surface of the board, thereby determining the axial position of the motor board relative to the stator.

[0012] Between the snap fits of the cylindrical portion, protrusions may be provided that fit into notches provided at radially opposing positions of the through holes of the motor board for positioning in the rotational direction. As a result, when the stator is attached to the motor board, the cylindrical portion of the insulator is inserted into the through-hole of the motor board, and the protrusions between the snap fits fit into the notches provided at diametrically opposed positions in the through-hole, thereby positioning the motor board in the rotational direction and reliably preventing rotation. This reduces variations during assembly and prevents deterioration of motor performance due to misalignment of the motor board with respect to the stator caused by motor vibration or external vibration due to the usage environment.

[0013] The insulator may be insert-molded with the stator core to provide the cylindrical portion, and the cylindrical portion may have a holding portion formed at the tip of a leaf spring-shaped protrusion. This reduces the number of parts and makes the motor more compact than when the insulator is a separate part, and also simplifies the assembly of the stator and the assembly of the stator and motor board. [Effects of the Invention]

[0014] The present invention provides an outer rotor motor that is easy to assemble and that can reliably achieve axial and rotational positioning of the stator and motor board with a simple configuration. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a plan view of a centrifugal blower. [Figure 2] 2 is a cross-sectional view of the centrifugal blower of FIG. 1 taken along the arrow BB. [Figure 3] FIG. 3A is a perspective view of the stator, and FIG. 3B is a plan view of the stator. [Figure 4] FIG. 4A is a perspective view of the stator with the motor board assembled to it, as seen from the stator side; FIGS. 4B and 4C are perspective views of the stator with the motor board assembled to it, as seen from the board side; and FIG. 4D is a plan view of the stator with the motor board assembled to it, as seen from the board side. [Figure 5] 5A is a front view showing a process of assembling a stator assembly, in which a motor board is assembled to a stator, into a bottom housing, and FIG. 5B is a cross-sectional view taken along the arrow AA in FIG. 5A. [Figure 6] 6A is a front view of a state in which a stator assembly in which a motor board is assembled to a stator is assembled to a bottom housing, and FIG. 6B is a cross-sectional view taken along the arrow AA in FIG. 6A. DETAILED DESCRIPTION OF THE INVENTION

[0016] An embodiment of an outer rotor motor according to the present invention will be described below with reference to the accompanying drawings. First, the schematic configuration of the outer rotor motor will be described with reference to Figs. 1 to 6. The outer rotor motor M will be described by taking as an example a DC brushless motor used in in-vehicle equipment. Below, a centrifugal blower using an outer rotor motor as a drive source will be described by taking as an example a centrifugal blower using an outer rotor motor as a drive source.

[0017] In Fig. 1, centrifugal blower 1 has centrifugal fan 2 and rotor 3 assembled together, and an outer rotor motor M that rotates and drives them is housed in blower housing 4. In Fig. 2, blower housing 4 is formed by combining top housing 4a assembled to cover centrifugal fan 2 with bottom housing 4b that rotatably supports outer rotor motor M (rotor 3 and stator 5). An intake opening 4c is provided in the center of top housing 4a, and air is taken in through intake opening 4c and pressurized from the radial outside and then exhausted in the circumferential direction.

[0018] The centrifugal fan 2 has a hub 2a that is assembled integrally with the rotor yoke 3a at its radial center. The centrifugal fan 2 is insert-molded with the rotor yoke 3a, and the top surface of the rotor yoke 3a is integrated with the hub 2a. A main plate 2b that is continuous with the hub 2a extends radially outward in a stepped manner, and multiple impellers 2c that are curved from the radial inside to the radial outside are formed upright on the main plate 2b.

[0019] The outer rotor motor M includes a rotor 3 and a stator 5. The rotor 3 has a rotor shaft 3b attached to the hub of a rotor yoke 3a formed in a cup shape. An annular rotor magnet 3c is provided on the inner peripheral surface of the rotor yoke 3a. The rotor magnet 3c is formed with rotor poles made of a permanent magnet that is magnetized with alternating north and south poles in the circumferential direction. The rotor 3 is attached to the radial outside of the stator 5 so that the rotor poles made of the rotor magnet 3c face the stator poles.

[0020] 3A and 3B, the stator 5 has a plurality of pole teeth 5c projecting radially outward from an annular stator core 5a. A motor coil 5d is wound around the pole teeth 5c via an insulator 7 to form stator poles. In this embodiment, a single-phase coil is wound, but a three-phase coil may also be used. The insulator 7 has two coil pins 5e connected to the motor coil 5d. Coil leads extending from the motor coil 5d are connected to the coil pins 5e. As shown in FIG. 3B, a groove 5f1 is formed on the inner peripheral surface of the annular stator core 5a for positioning with a winding machine during assembly. Because the outer shape of the pole teeth 5c is eccentric, a groove 5f2 is formed to determine the orientation of the stator core 5a relative to the housing compartment 4d.

[0021] In FIG. 2, a cylindrical metal bearing housing 8a is insert-molded into the bottom housing 4b of the blower housing 4 and integrally assembled with the housing compartment 4d. The upper end 4e of the housing compartment 4d determines the installation position of the stator core 5a, as described below. A pair of bearings 8b are inserted into the cylindrical bore of the bearing housing 8a, one on each longitudinal side of the bearing housing 8a. The rotor shaft 3b is inserted into the bearing housing 8a and rotatably supported by the pair of bearings 8b. A retaining washer 8c is fitted onto the rotor shaft 3b at its axial end, and its axial movement is restricted by the bearing 8b at its axially lower end. A preload spring 8d is fitted around the rotor shaft 3b between the hub of the rotor yoke 3a and the bearing 8b at its axially upper end in a state compressed from its natural length to enhance the rotational stability of the rotor 3.

[0022] As shown in FIG. 4A, the motor board 6 is provided with a magnetic pole detection element 6a, such as a Hall IC, for detecting the magnetic pole position of the rotor 3. The motor board 6 is fixed to the blower housing 4 (bottom housing 4b), as will be described later. In addition, coil pins 5e connected to motor coils 5d wound around pole teeth 5c of the stator core 5a are inserted into and soldered to board terminal holes 6b (see FIGS. 4B and 4C). The magnetic pole detection element 6a detects the magnetic pole position of the rotor 3 and switches the direction of current flowing through the motor coil 5d, thereby forcing the rotor 3 to rotate.

[0023] 3A and 3B, the stator core 5a is assembled to the insulator 7 by integral molding. The insulator 7 is formed by insert molding the stator core 5a using, for example, PBT (polybutylene terephthalate) resin. Note that instead of using insert molding, the insulator 7 may be molded alone and assembled around the pole teeth 5c of the stator core 5a.

[0024] Cylindrical portions 7a protrude on both axial sides radially inward of the stator core 5a of the insulator 7. As will be described later, a motor board 6 is assembled to one of the cylindrical portions 7a (see FIG. 4), and the stator 5 and motor board 6 (stator assembly) are assembled to the bottom housing 4b (see FIG. 2) with the cylindrical portion 7a concentrically fitted into the outer periphery of the housing accommodation portion 4d that accommodates a metallic cylindrical bearing housing 8a.

[0025] Snap fits 7b are provided at multiple locations (e.g., four locations) on the axial end of the cylindrical portion 7a. The snap fits 7b are inserted into the through-hole 6c of the motor board 6 and engage with the locking recesses 6d formed around the through-hole 6c. The snap fits 7b are provided at multiple locations between the pole teeth 5c of the stator core 5a (see FIG. 3B). The snap fits 7b are cantilever-type locking members, each of which has a leaf spring-like protrusion extending axially from the cylindrical portion 7a and a retaining portion 7c at its tip. Specifically, as shown in FIG. 3A, the retaining portion 7c is tapered, consisting of a radially inner tapered portion 7c1 and a radially outer tapered portion 7c2. A stepped portion 7c3 projects radially outward from the radially outer tapered portion 7c2. The stepped portion 7c3 engages with the locking recesses 6d formed on the wall surface of the through-hole 6c of the motor board 6. As a result, the snap fits 7b position and hold the motor board 6 relative to the stator 5 in the axial and radial directions.

[0026] 3A, abutment members 7d having a shorter length than the snap fits 7b of the cylindrical portion 7a are provided between the snap fits 7b. As a result, when the cylindrical portions 7a of the insulator 7 are inserted into the through holes 6c of the motor board 6 during assembly of the stator 5 to the motor board 6, the abutment members 7d come into contact with the board surface on the front side in the insertion direction of the motor board 6, and when the holding portions 7c of the snap fits 7b are inserted through the through holes 6c, the stepped portions 7c3 are engaged with and sandwiched in the locking recesses 6d against the board surface on the rear side in the insertion direction of the motor board 6, thereby defining the axial position of the motor board 6 with respect to the stator 5.

[0027] In this way, when the stator 5 is assembled to the motor board 6, the radially outer tapered portion 7c2 is guided along the edge of the through-hole 6c of the motor board 6 and deforms radially inward while the stepped portion 7c3 engages with the opposite surface of the board, thereby positioning and holding the motor board 6. Furthermore, when the stator 5 (stator assembly) assembled with the motor board 6 is assembled to the housing storage portion 4d formed upright in the bottom housing 4b, the radially inner tapered portion 7c1 of the holding portion 7c of the snap fit 7b moves radially outward to avoid interference with the upper end portion 4e of the housing storage portion 4d (the abutment portion of the stator core 5a), making assembly easy.

[0028] 3A, the cylindrical portion 7a is provided with a pair of protrusions 7e that fit into notches 6e provided at radially opposing positions in the through-hole 6c of the motor substrate 6 (see FIG. 4D). The length of the protrusions 7e is equal to or greater than the thickness of the motor substrate 6, and the width of the protrusions 7e is formed to be approximately equal to the width of the notches 6e. In this case, the clearance around the rotor shaft 3b between the protrusion 7e closest to the Hall IC and the notch 6e of the pair of protrusions 7e may be formed to be tighter than the clearance between the protrusion 7e and the notch 6e at the opposing position. As a result, when the cylindrical portion 7a of the insulator 7 is inserted into the through-hole 6c of the motor board 6 during assembly of the motor board 6 to the stator 5, the protrusions 7e provided between the snap fits 7b fit into the notches 6e provided at radially opposing positions in the through-hole 6c, thereby reliably preventing the motor board 6 from rotating in the direction of rotation relative to the stator 5. This reduces variations during assembly and prevents deterioration of motor characteristics due to misalignment of the motor board 6 with respect to the stator 5 caused by motor vibration or external vibration depending on the usage environment.

[0029] An example of assembling an outer rotor motor M will now be described with reference to Figures 5 to 7. A stator 5 is prepared in which an insulator 7 is insert-molded together with a stator core 5a, and motor coils 5d are wound around pole teeth 5c covered by the insulator 7. Snap fits 7b, abutment members 7d, and protrusions 7e are each equiangularly arranged at the axial end of the cylindrical portion 7a of the insulator 7 (see Figure 3A).

[0030] First, as shown in FIGS. 5A and 5B, the motor board 6 is assembled to the stator 5 (see FIG. 4A). The stator 5 is inserted into the through-hole 6c of the motor board 6 from the cylindrical portion 7a. At this time, the snap fit 7b is aligned with the locking recess 6c, and the protrusion 7e is aligned with the notch 6e (see FIGS. 4B to 4D). The snap fit 7b is inserted while deforming radially inward, with the radially outer tapered portion 7c2 of the holding portion 7c guided into the through-hole 6c, until the stepped portion 7c3 continuing from the radially outer tapered portion 7c2 engages with the locking recess 6c of the motor board 6. The coil pin 5e is soldered after being inserted into the board terminal hole 6b.

[0031] Next, as shown in Figures 6A and 6B, the stator 5, which holds the motor board 6, is assembled into the housing compartment 4d, which houses the bearing housing 8a insert-molded into the bottom housing 4b. The stator 5 is assembled by fitting the inner peripheral surface of the annular stator core 5a into the outer peripheral surface of the housing compartment 4d, so that the stator core 5a abuts against the upper end 4e (see Figure 6B) of the housing compartment 4d. At this time, the inner peripheral surface of the annular stator core 5a and the outer peripheral surface of the housing compartment 4d are adhesively fixed together.

[0032] Furthermore, when the cylindrical portion 7a is concentrically fitted into the bearing housing 8a, the radially inner tapered portion 7c1 (see Figure 3A) of the retaining portion 7c of the snap fit 7b moves radially outward to avoid interference with the upper end portion 4e of the housing storage portion 4d that stores the bearing housing 8a, allowing the stator 5 to be smoothly assembled to the bottom housing 4b.

[0033] A rotor 3 is prepared in which the rotor shaft 3b is attached to the hub of the rotor yoke 3a, and the rotor yoke 3a and centrifugal fan 2 are molded as one unit. The rotor 3 is then attached to the stator 5. The rotor shaft 3b is inserted into a bearing housing 8a and rotatably supported by a pair of bearings 8b. A retaining washer 8c is fitted near the end of the rotor shaft 3b to prevent it from coming loose. This positions the rotor poles radially outward of the stator poles, and the outer rotor motor M is assembled (see Figure 2).

[0034] As described above, the snap fit 7b provided at the axial end of the cylindrical portion 7a of the insulator 7 is inserted into the through hole 6c of the motor board 6 and engages with the engagement recess 6d formed around the through hole 6c to hold the motor board 6, thereby enabling the motor board 6 to be positioned axially relative to the stator 5. Therefore, the axial and rotational positioning of the stator 5 and the motor board 6 can be reliably achieved with a simple configuration, and an outer rotor type motor M with good assembly properties can be provided.

[0035] In the above-described embodiment, the snap fit 7b, the abutment member 7d, and the protrusion 7e were each equiangularly arranged at the axial end of the cylindrical portion 7a of the insulator 7, but these are not necessarily limited to being equiangularly arranged, for example, if the pole teeth 5c of the stator core 5a are arranged non-equangularly.

[0036] Furthermore, while a magnetic pole detection element 6a such as a Hall IC was provided on the motor board 6, the magnetic pole detection element 6a is not necessary in the case of, for example, a sensorless DC brushless motor. In this case, the protrusion 7e provided to prevent rotation of the motor board 6 in the rotation direction at a position facing the cylindrical portion 7a of the insulator 7 and the notch 6e provided at a position facing the through-hole 6c of the motor board 6 in the radial direction can be omitted. Furthermore, the insulator 7 does not have to be integrally formed with the stator core 5a, but may be formed separately and then assembled. [Explanation of symbols]

[0037] 1 Centrifugal blower 2 Centrifugal fan 2a Hub 2b Main plate 2c Impeller M Outer rotor type motor 3 Rotor 3a Rotor yoke 3b Rotor shaft 3c Rotor magnet 4 Blower housing 4a Top housing 4b Bottom housing 4c Intake opening 4d Housing storage section 4e Upper end 5 Stator 5a Stator core 5b Back yoke 5c Pole teeth 5d Motor coil 5e Coil pin 5f1, 5f2 Groove 6 Motor board 6a Magnetic pole detection element 6b Board terminal hole 6c Through hole 6d Locking recess 6e Notch 7 Insulator 7a Cylindrical section 7b Snap fit 7c Holding section 7c1 Radially inward tapered section 7c2 Radially outward tapered section 7c3 Stepped section 7d Abutment member 7e Protrusion 8a Bearing housing 8b Bearing 8c Retaining washer 8d Preload spring

Claims

1. An outer rotor motor includes a stator in which stator poles are formed by windings, with an insulator interposed between the windings and a rotor in which rotor poles made of permanent magnets are arranged radially outside the stator to face the stator poles, and the stator is provided with a motor substrate on which magnetic pole detection elements for detecting the rotor magnetic pole positions are provided, an outer rotor type motor, characterized in that a cylindrical portion extending in the axial direction radially inside the insulator covering the stator core has snap fits provided at multiple locations around the circumferential direction of the cylindrical portion, the snap fits being inserted into through holes in the motor board and engaging with locking recesses formed in the wall surface of the through hole to position and hold the motor board in the axial and radial directions relative to the stator, and the stator is concentrically assembled to the outer periphery of a housing storage portion that stores a bearing housing, with the motor board positioned and held in place by the snap fits.

2. 2. The outer rotor motor according to claim 1, wherein the snap fit has a retaining portion provided at a tip end, which is tapered with a radially inner tapered portion and a radially outer tapered portion, and is engaged with the motor base by a stepped portion protruding radially outward from the radially outer tapered portion.

3. 3. The outer rotor motor according to claim 1, wherein the snap fit is provided to protrude between the stator pole teeth in the circumferential direction of the cylindrical portion.

4. 3. An outer rotor type motor according to claim 1, wherein abutment members are provided between the snap fits of the cylindrical portion, which abut against the motor substrate surface in the axial direction and sandwich the motor substrate together with the snap fits to determine its axial position.

5. 3. An outer rotor type motor according to claim 1, wherein a protrusion is provided between the snap fits of the cylindrical portion, the protrusion fitting into a notch provided at a radially opposite position of the through hole of the motor base plate for positioning in the rotational direction.

6. 3. An outer rotor type motor according to claim 1, wherein the insulator is insert-molded with the stator core to form the cylindrical portion, and the cylindrical portion has a retaining portion formed at the tip of a leaf spring-shaped protrusion.

Images