Rotor, motor and wiper motor

Abstract

A rotor, motor, and wiper motor are provided that suppress the degradation of operating noise or rotor characteristics and reduce the material cost of permanent magnets. The arc center of the outer circumferential surface of the rotor core and the arc center of the inner circumferential surface of the permanent magnet are offset radially outward from the rotation axis in a manner that the circumferential center protrudes to the outermost radial direction. The angle formed by the opposing sides of two adjacent poles in the circumferential direction is the same as the angle formed by the sides of the permanent magnet in the circumferential direction. When the distance between the outer circumferential surface of the rotor core and the outermost radial end of the pole is set to Lt, and the distance between the inner circumferential surface of the permanent magnet and the outermost radial end of the side of the magnet is set to Lme, the distances Lt and Lme are set to satisfy Lme < Lt.

Description

Technical Field

[0001] This invention relates to a rotor, a motor, and a windshield wiper motor. Background Technology

[0002] It has been known that there is a surface magnet (SPM) type rotor in which multiple permanent magnets for excitation are arranged circumferentially on the outer peripheral surface of the rotor core. In addition, among this type of surface magnet rotor, there is a so-called insertion type rotor that includes multiple protruding poles that protrude radially outward from the outer peripheral surface of the rotor core and are arranged between adjacent permanent magnets in the circumferential direction.

[0003] In this type of insert rotor, the rotor core and the protruding poles are formed of magnetic material. The protruding poles of the rotor core protrude radially outwards, thus becoming the direction in which the linkage magnetic flux generated by the stator coils easily flows. Furthermore, the protruding poles generate a reluctance torque that rotates the rotor core by reducing the reluctance of the magnetic circuit that reduces the linkage magnetic flux.

[0004] Furthermore, due to manufacturing errors in the permanent magnet or rotor core, the circumferential width of the permanent magnet may be larger than the width between adjacent poles in the circumferential direction. In this case, forcibly placing the permanent magnet on the outer circumferential surface of the rotor core may apply excessive stress to the permanent magnet, leading to damage. Therefore, in most cases, the circumferential width of the permanent magnet is made smaller than the width between adjacent poles in the circumferential direction.

[0005] In addition, in order to increase the rotational torque of the permanent magnet towards the rotor core, the radial wall thickness of the permanent magnet is made to gradually increase towards the circumferential center by making the circumferential center protrude outwards.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: International Publication No. 2015 / 102047 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] Furthermore, as a method for fixing permanent magnets to the rotor core, a magnet cover is sometimes provided to cover the outer circumferential surface of the permanent magnet, and the permanent magnet is fixed to the rotor core using the magnet cover. Here, if, as in the prior art, the circumferential width of the permanent magnet is smaller than the width between adjacent poles in the circumferential direction, then when the permanent magnet is fixed to the rotor core using the magnet cover, the permanent magnet will wobble with the gap between the permanent magnet and the pole, which may degrade the operating sound. Even if adhesive is used to fix the permanent magnet to the rotor core, the adhesive may peel off, causing the permanent magnet to wobble. In addition, due to the positional displacement of the permanent magnet, the rotor characteristics may degrade.

[0011] Furthermore, if the radial wall thickness of the permanent magnet is made to gradually increase towards the center in the circumferential direction, as in the prior art, there is a problem of increased material cost of the permanent magnet.

[0012] Therefore, the present invention provides a rotor, motor, and wiper motor that suppresses the degradation of operating noise or rotor characteristics and reduces the material cost of permanent magnets.

[0013] Technical means to solve the problem

[0014] To solve the aforementioned problem, the rotor of the present invention includes: a shaft that rotates about a rotation axis; a rotor core fixed to the shaft and rotating radially around the rotation axis; a plurality of permanent magnets arranged circumferentially on the outer peripheral surface of the rotor core; and a plurality of protruding poles protruding from the outer peripheral surface of the rotor core toward the radially outer side and disposed between adjacent permanent magnets in the circumferential direction, and formed into a rectangular shape that is radially elongated when viewed from the direction of the rotation axis. The arc center of the outer peripheral surface of the rotor core between the plurality of protruding poles is offset radially outward from the rotation axis in such a way that it protrudes most radially outward from the circumferential center between adjacent protruding poles in the circumferential direction of the outer peripheral surface of the rotor core. Each permanent magnet has an inner peripheral surface and an outer peripheral surface, the inner peripheral surface being an arc-shaped radial surface when viewed from the direction of the rotation axis. The outer circumferential surface, when viewed from the direction of the rotation axis, is an arc-shaped radially outer side, and the permanent magnet is formed symmetrically about the center of the circumferential direction. The arc center of the inner circumferential surface of the permanent magnet is offset radially outward from the rotation axis in a manner corresponding to the outer circumferential surface of the rotor core. The angle formed by the opposing sides of two adjacent protruding poles in the circumferential direction is the same as the angle formed by the two sides of the permanent magnet in the circumferential direction facing the sides of the protruding poles in the circumferential direction. When the distance between the outer circumferential surface of the rotor core and the outermost radial end of the protruding pole is set as Lt, and the distance between the inner circumferential surface of the permanent magnet and the outermost radial end of the side of the permanent magnet is set as Lme, each distance Lt and distance Lme is set to satisfy Lme < Lt.

[0015] With this configuration, even when the circumferential width of the permanent magnet is smaller than the width between adjacent circumferential poles, the side surface of the permanent magnet will not come into contact with the side surface of the pole due to the movement of the pole and the permanent magnet; instead, only the outermost radial side of the magnet's side surface abuts against the pole. Therefore, even when the circumferential width of the permanent magnet is smaller than the width between adjacent circumferential poles, the circumferential movement range of the permanent magnet can be reduced. Thus, the degradation of operating noise or rotor characteristics can be suppressed.

[0016] Furthermore, the center of the arc on the inner circumferential surface of the permanent magnet is offset radially outward, thus allowing for a corresponding reduction in the wall thickness on the inner circumferential surface compared to previous designs. In other words, the radial wall thickness of the permanent magnet can be reduced. Therefore, the material cost of the permanent magnet can be lowered.

[0017] The motor of the present invention includes: a stator having an annular stator core and a plurality of racks protruding from the inner circumferential surface of the stator core toward the radially inner side; a coil mounted on the racks; and the aforementioned rotor disposed on the radially inner side relative to the plurality of racks, and rotating in both clockwise and counterclockwise directions when viewed from the direction of the rotation axis.

[0018] In this type of motor with bidirectional rotor rotation, the circumferential wobbling of the permanent magnet can be suppressed to prevent the deterioration of the operating sound, making it particularly suitable for use.

[0019] The wiper motor of the present invention includes: the motor described above; and a reduction unit that reduces the rotation of the rotating shaft and outputs the speed.

[0020] With this configuration, a wiper motor can be provided that suppresses the deterioration of operating noise or rotor characteristics and reduces the material cost of permanent magnets.

[0021] The effects of the invention

[0022] According to the present invention, even when the circumferential width of the permanent magnet is smaller than the width between adjacent circumferential poles, the side surface of the permanent magnet will not come into contact with the side surface of the pole due to the movement of the pole and the permanent magnet; instead, only the outermost radial side of the magnet's side surface abuts against the pole. Therefore, even when the circumferential width of the permanent magnet is smaller than the width between adjacent circumferential poles, the circumferential movement range of the permanent magnet can be reduced. Thus, the degradation of operating noise or rotor characteristics can be suppressed.

[0023] Furthermore, because the center of the arc on the inner circumferential surface of the permanent magnet is radially outward, the wall thickness on the inner circumferential surface of the permanent magnet can be correspondingly reduced compared to the past. That is, the radial wall thickness of the permanent magnet can be thinned. Therefore, the material cost of the permanent magnet can be reduced. Attached Figure Description

[0024] Figure 1 This is a perspective view of the wiper motor in an embodiment of the present invention.

[0025] Figure 2 It is along Figure 1 A cross-sectional view of line AA.

[0026] Figure 3 This is a radial cross-sectional view of the stator and rotor in an embodiment of the present invention.

[0027] Figure 4 This is a plan view of the rotor of an embodiment of the present invention viewed from the axial direction.

[0028] Figure 5It is a magnified plan view of a portion of the rotor viewed from the axial direction. Figure 5 (a) represents the existing rotor. Figure 5 (b) represents the rotor of this embodiment.

[0029] Figure 6 This is an illustration of the circumferential swaying of a permanent magnet. Figure 6 (a) represents the existing rotor. Figure 6 (b) represents the rotor of this embodiment.

[0030] Figure 7 Indicates a part of the rotor. Figure 7 (a) is Figure 6 Enlarged view of part B in (a), Figure 7 (b) is Figure 6 Enlarged view of part C in (b).

[0031] [Explanation of reference numerals in the attached figures]

[0032] 1: Wiper motor

[0033] 2: Motor section (motor)

[0034] 3: Deceleration section

[0035] 8: Stator

[0036] 9: Rotor

[0037] 22: rack and pinion

[0038] 24: Coil

[0039] 31: Shaft

[0040] 32: Rotor core

[0041] 32b: outer peripheral surface

[0042] 33: Permanent magnet

[0043] 33a: Magnet side (side view)

[0044] 33b: Inner circumferential surface

[0045] 33c: outer peripheral surface

[0046] 35: Sudden pole

[0047] 35a: Sudden pole side (side)

[0048] C1: Axis of rotation

[0049] C2, C3, C4: Center of the arc

[0050] θ1, θ2: Angles Detailed Implementation

[0051] Next, embodiments of the present invention will be described with reference to the accompanying drawings.

[0052] (Windshield wiper motor)

[0053] Figure 1 This is a 3D view of wiper motor 1. Figure 2 It is along Figure 1 A cross-sectional view of line AA.

[0054] like Figure 1 , Figure 2 As shown, the wiper motor 1 serves as the drive source for a wiper mounted on a vehicle. The wiper motor 1 includes: a motor unit (motor) 2, a reduction unit 3 that reduces the rotation of the motor unit 2 and outputs the speed, and a controller unit 4 that controls the drive of the motor unit 2.

[0055] Furthermore, in the following description, when referred to as axial, it refers to the direction of the rotation axis C1 of the rotating shaft 31 of the motor part 2; when referred to as circumferential, it refers to the circumferential direction of the rotating shaft 31; and when referred to as radial, it refers to the radial direction of the rotating shaft 31.

[0056] (Motor Section)

[0057] The motor unit 2 includes: a motor housing 5, a generally cylindrical stator 8 housed within the motor housing 5, and a rotor 9 disposed radially inside the stator 8 and rotatable relative to the stator 8. The motor unit 2 is a so-called brushless motor that does not require brushes when supplying power to the stator 8.

[0058] (Motor housing)

[0059] The motor housing 5 is formed of a material with excellent heat dissipation, such as die-cast aluminum. The motor housing 5 includes a first motor housing 6 and a second motor housing 7, which are configured to be axially separable. The first motor housing 6 and the second motor housing 7 are each formed into a bottomed cylindrical shape.

[0060] The first motor housing 6 is integrally formed with the gear housing 40 of the reduction section 3 in such a way that the bottom 10 engages with the gear housing 40 of the reduction section 3. A through hole 10a is formed approximately in the radial center of the bottom 10, through which the shaft 31 of the rotor 9 can be inserted.

[0061] Furthermore, an outer flange 16 extending radially outward is formed at the opening 6a of the first motor housing 6. Similarly, an outer flange 17 extending radially outward is formed at the opening 7a of the second motor housing 7. These outer flanges 16 and 17 are joined together to form a motor housing 5 with an internal space. Moreover, within the internal space of the motor housing 5, the outer peripheral surface of the stator 8 is fitted onto the inner peripheral surfaces of the first motor housing 6 and the second motor housing 7.

[0062] (stator)

[0063] Figure 3 This is a radial cross-sectional view of the stator 8 and rotor 9.

[0064] like Figure 2 , Figure 3 As shown, the stator 8 includes a stator core 20, which is integrally formed by a cylindrical core 21 with a generally annular cross-sectional shape along the radial direction and a plurality of racks 22 (e.g., six in this embodiment) protruding radially inward from the core 21.

[0065] The stator core 20 is formed by stacking multiple metal plates along the axial direction. Furthermore, the stator core 20 is not limited to being formed by stacking multiple metal plates along the axial direction; for example, it can also be formed by pressing soft magnetic powder.

[0066] The rack 22 is integrally formed of a rack body 101 that protrudes radially from the inner circumferential surface of the core 21 and a flange portion 102 that extends circumferentially from the inner radial end of the rack body 101. The flange portion 102 is formed to extend circumferentially from both sides of the rack body 101. Furthermore, a groove 19 is formed between adjacent flange portions 102 in the circumferential direction.

[0067] Furthermore, the inner circumferential surface of the core 21 and the rack 22 are covered by a resin insulator 23. Coils 24 are wound from the insulator 23 onto each rack 22. Each coil 24 generates a magnetic field to rotate the rotor 9 by means of power supplied from the controller unit 4.

[0068] (rotor)

[0069] Figure 4 This is a plan view of rotor 9 taken from the axial direction.

[0070] like Figure 3 , Figure 4 As shown, the rotor 9 is rotatably disposed on the radial inner side of the stator 8 with a small gap. The rotor 9 includes: a worm shaft 44 (see reference 3) that forms the reduction unit 3. Figure 2The motor unit 2 comprises an integrally formed rotating shaft 31, a generally cylindrical rotor core 32 fitted and fixed to the outer peripheral surface of the rotating shaft 31 and rotating about the axis C1 of the rotating shaft 31, and four permanent magnets 33 disposed on the outer peripheral surface of the rotor core 32. Thus, in the motor unit 2, the ratio of the number of magnetic poles of the permanent magnets 33 to the number of slots 19 (racks 22) is 4:6.

[0071] The rotor core 32 is formed by stacking multiple metal plates along the axial direction. Furthermore, the rotor core 32 is not limited to being formed by stacking multiple metal plates along the axial direction; for example, it can also be formed by pressing soft magnetic powder.

[0072] Furthermore, a through hole 32a extending axially is formed approximately at the radial center of the rotor core 32. The rotating shaft 31 is pressed into the through hole 32a. Alternatively, the rotating shaft 31 can be inserted relative to the through hole 32a, and the rotor core 32 can be fixed to the rotating shaft 31 using an adhesive or the like.

[0073] Furthermore, four protruding poles 35 are provided at equal intervals along the circumferential direction on the outer peripheral surface 32b of the rotor core 32. The protruding poles 35 protrude radially outward and are formed to extend integrally along the axial direction of the rotor core 32. The protruding poles 35 are formed into a rectangular shape that is radially longer when viewed from the axial direction, and have protruding pole side surfaces 35a on both sides in the circumferential direction and a front end surface 35b on the radially outer side.

[0074] On the front end face 35b of the protruding electrode 35, a rounded chamfered portion 35c is formed at both corners in the circumferential direction and throughout the axial direction. In addition, on the front end face 35b of the protruding electrode 35, a recessed portion 35d is formed at the center in the circumferential direction and throughout the axial direction.

[0075] At the root of the protruding electrode 35, that is, at the connection between the protruding electrode side surface 35a and the outer peripheral surface 32b of the protruding electrode 35, an arcuate portion 32c is formed. The protruding electrode side surface 35a and the outer peripheral surface 32b are connected via the arcuate portion 32c.

[0076] The arc center C2 of the outer peripheral surface 32b of the rotor core 32 protrudes radially outward from the center of the circumferential direction between the adjacent poles 35 in the outer peripheral surface 32b, thus offsetting from the rotation axis C1 to the radially outward and becoming eccentric.

[0077] In the outer peripheral surface 32b of the rotor core 32 thus formed, magnet housing portions 36 are respectively formed between two adjacent circumferential poles 35. Permanent magnets 33 are respectively disposed in these magnet housing portions 36.

[0078] The permanent magnet 33 is, for example, a ferrite magnet. When viewed from the axial direction, the permanent magnet 33 is generally arc-shaped and symmetrical about the center line in the circumferential direction. The permanent magnet 33 has: a flat magnet side surface 33a facing the pole side surface 35a in the circumferential direction; an arc-shaped inner circumferential surface 33b in the radial direction; an arc-shaped outer circumferential surface 33c in the radial direction; a parallel surface 33d formed at the connection between the magnet side surface 33a and the outer circumferential surface 33c and formed parallel to both sides in the circumferential direction; and a circular chamfered portion 33e formed at the connection between the magnet side surface 33a and the inner circumferential surface 33b.

[0079] The inner circumferential surface 33b of the permanent magnet 33 is formed in the same manner as the outer circumferential surface 32b of the rotor core 32. The arc center C3 of the inner circumferential surface 33b of the permanent magnet 33 coincides with the arc center C2 of the outer circumferential surface 32b of the rotor core 32. The circumferential center of the inner circumferential surface 33b of the permanent magnet 33 protrudes to the outermost radial direction.

[0080] The arc center C4 of the outer peripheral surface 33c of the permanent magnet 33 is also offset radially outward from the axis of rotation C1, thus becoming eccentric. The outer peripheral surface 33c is formed such that the circumferential center protrudes to the outermost radial direction.

[0081] Here, when the radius of curvature of the inner circumferential surface 33b of the permanent magnet 33 is set to Ri and the radius of curvature of the outer circumferential surface 33c is set to Ro, the radii of curvature Ri and Ro are set to satisfy...

[0082] Ro>Ri…(1)

[0083] Furthermore, the arc center C4 of the outer peripheral surface 33c of the permanent magnet 33 coincides with the arc center C3 of the inner peripheral surface 33b of the permanent magnet 33 and the arc center C2 of the outer peripheral surface 32b of the rotor core 32.

[0084] In addition, when the angle between the opposing pole sides 35a of the adjacent poles 35 in the circumferential direction is set to θ1, and the angle between the magnet sides 33a on both sides of the permanent magnet 33 in the circumferential direction is set to θ2, the angles θ1 and θ2 are set to satisfy θ1≒θ2…(2).

[0085] In addition, when the distance between the outer peripheral surface 32b of the rotor core 32 and the outermost radial end of the protruding pole side surface 35a of the permanent magnet 33, that is, the distance between the outer peripheral surface 32b of the rotor core 32 (excluding the arc portion 32c) and the outermost radial end of the protruding pole 35, is set to Lt, the distance between the inner peripheral surface 33b of the permanent magnet 33 and the outermost radial end of the magnet side surface 33a is set to Lme, and the radial wall thickness at the circumferential center of the permanent magnet 33 is set to Lm, the distance Lt, the distance Lme, and the wall thickness Lm are set to satisfy Lme < Lm < Lt…(3).

[0086] After the permanent magnet 33 is disposed in the magnet housing 36 of the rotor core 32, it is fixed by a magnet cover 37. The magnet cover 37 is formed to cover the outer peripheral surface 33c of the permanent magnet 33. The magnet cover 37 is formed by pressing a sheet of magnetic material. Alternatively, in addition to the magnet cover 37, the permanent magnet 33 can also be glued to the rotor core 32 using an adhesive (not shown). With this configuration, the permanent magnet 33 can be firmly fixed to the rotor core 32.

[0087] (Circumferential swaying of a permanent magnet)

[0088] Next, based on Figure 5 (a)~ Figure 7 (a) The circumferential oscillation of the permanent magnet 33 of the rotor 9 in this embodiment is compared with the circumferential oscillation of the permanent magnet 133 of the conventional rotor 109 and explained.

[0089] Figure 5 It is a magnified plan view of a portion of the rotor viewed from the axial direction. Figure 5 (a) represents the existing rotor 109. Figure 5 (b) indicates the rotor 9 in this embodiment. Figure 5 of (a), Figure 5 (b) corresponds to the Figure 4 Furthermore, in the following description, in order to avoid repeating the description of the permanent magnet 33 in this embodiment, the names of the rotor core 132 and the permanent magnet 133 of the conventional rotor 109 are the same as the names of the rotor core 32 and the permanent magnet 33 of the rotor 9 in this embodiment, and the same symbols are used for description.

[0090] As described above, in the rotor 9 of this embodiment, the arc center C2 of the outer peripheral surface 32b of the rotor core 32 and the arc center C3 of the inner peripheral surface 33b of the permanent magnet 33 are offset radially outward from the rotation axis C1, resulting in eccentricity. In contrast, as... Figure 5 As shown in (a), in the existing rotor 109, the arc center C2 of the outer peripheral surface 32b of the rotor core 132 and the arc center C3 of the inner peripheral surface 33b of the permanent magnet 133 are not eccentric and are consistent with the rotation axis C1.

[0091] like Figure 5 As shown in (a), a gap S1 is formed between the magnet side surfaces 33a on both sides of the existing permanent magnet 133 in the circumferential direction and the pole facet 35a facing these magnet side surfaces 33a in the circumferential direction. Additionally, as... Figure 5As shown in (b), gaps S2 are formed between the magnet side surfaces 33a on both sides of the permanent magnet 33 in this embodiment and the pole facets 35a facing these magnet side surfaces 33a in the circumferential direction. These gaps S1 and gaps S2 are formed to be the same size.

[0092] Figure 6 This is an illustration of the circumferential swaying of a permanent magnet. Figure 6 (a) represents the existing rotor 109. Figure 6 (b) indicates the rotor 9 in this embodiment. Figure 6 (a) corresponds to the above. Figure 5 (a) Figure 6 (b) corresponds to the above. Figure 5 (b) Figure 7 (a) is Figure 6 Enlarged view of part B of (a). Figure 7 (b) is Figure 6 Enlarged view of part C in (b).

[0093] Based on the structure described above, such as Figure 6 of (a), Figure 6 As shown in (b), when the permanent magnets 33 and 133 are brought close to one of the two adjacent poles 35 in the circumferential direction, the magnet side surface 33a of each permanent magnet 33 and 133 abuts against the pole side surface 35a. The method of abutting between the magnet side surface 33a and the pole side surface 35a in this embodiment differs from that in the conventional embodiment.

[0094] That is, relative to such Figure 7 As shown in (a), the contact area between the magnet side surface 33a and the pole side surface 35a of the existing rotor 109 is as follows: Figure 7 As shown in (b), the contact area between the magnet side surface 33a and the pole side surface 35a of the rotor 9 in this embodiment is small. More specifically, in the rotor 9 of this embodiment, only the radially outer portion of the magnet side surface 33a contacts the pole side surface 35a (see Figure 1). Figure 7 (D in (b)). This is because, in this embodiment, the arc center C2 of the outer peripheral surface 32b of the rotor core 32 and the arc center C3 of the inner peripheral surface 33b of the permanent magnet 33 are offset radially outward from the rotation axis C1 and thus become eccentric.

[0095] That is, if the centers C2 and C3 of each arc are so eccentric, the radii of curvature of the outer circumferential surface 32b of the rotor core 32 and the inner circumferential surface 33b of the permanent magnet 33 are smaller than before. Therefore, when the permanent magnet 33 is brought close to the pole 35, the tilt of the magnet side surface 33a relative to the pole side surface 35a increases. As a result, as... Figure 7As shown in (b), in this embodiment, when the magnet side surface 33a and the pole side surface 35a are in contact, a gap S3 remains between the radial inner side of the pole side surface 35a and the radial inner side of the magnet side surface 33a.

[0096] Here, in the rotor 9 of this embodiment, the angle θ1 formed by the opposing pole sides 35a of adjacent poles 35 in the circumferential direction and the angle θ2 formed by the two magnet sides 33a of the permanent magnet 33 in the circumferential direction are set to satisfy the above equation (2). In addition, the distance Lt between the outer peripheral surface 32b of the rotor core 32 and the outermost radial end of the pole 35, and the distance Lme between the inner peripheral surface 33b of the permanent magnet 33 and the outermost radial end of the magnet side 33a are set to satisfy the above equation (3). Therefore, when the permanent magnet 33 approaches the pole 35, the outermost radial portion of the magnet side 33a reliably abuts against the pole 35.

[0097] Therefore, when permanent magnets 33 and 133 are brought close to the pole break 35, relative to... Figure 6 As shown in (a), the existing rotor 109 has a gap S1' between the pole facet 35a and the magnet facet 33a, as shown in (a). Figure 6 As shown in (b), the gap S2' between the pole side 35a and the magnet side 33a of the rotor 9 in this embodiment is small. Therefore, compared with the conventional rotor 109, the circumferential wobble of the permanent magnet 33 of the rotor 9 in this embodiment is small.

[0098] (Deceleration section)

[0099] return Figure 1 , Figure 2 The reduction unit 3 includes a gear housing 40 on which the motor housing 5 is mounted, and a worm gear reduction mechanism 41 housed within the gear housing 40. The gear housing 40 is formed of a material with excellent heat dissipation, such as die-cast aluminum. The gear housing 40 is box-shaped with an opening 40a on one side, and has a gear receiving portion 42 inside that houses the worm gear reduction mechanism 41. In addition, an opening 43 is formed on the side wall 40b of the gear housing 40 at a location where the first motor housing 6 is integrally formed, and the opening 43 communicates the through hole 10a of the first motor housing 6 with the gear receiving portion 42.

[0100] Additionally, a generally cylindrical bearing boss 49 protrudes from the bottom wall 40c of the gear housing 40. The bearing boss 49 rotatably supports the output shaft 48 of the worm gear reducer 41. A sliding bearing (not shown) is provided on the inner circumferential surface of the bearing boss 49. An O-ring (not shown) is installed on the inner circumferential edge of the front end of the bearing boss 49. This prevents dust or water from entering the interior from the outside through the bearing boss 49. Multiple ribs 52 are provided on the outer circumferential surface of the bearing boss 49. This ensures the rigidity of the bearing boss 49.

[0101] The worm gear reducer 41 housed in the gear housing 42 includes a worm shaft 44 and a worm wheel 45 meshing with the worm shaft 44. The worm shaft 44 and the rotating shaft 31 of the motor unit 2 are arranged coaxially. Furthermore, both ends of the worm shaft 44 are rotatably supported by bearings 46 and 47 provided in the gear housing 40. The end of the worm shaft 44 on the motor unit 2 side protrudes into the opening 43 of the gear housing 40 via the bearing 46. The protruding end of the worm shaft 44 is joined to the end of the rotating shaft 31 of the motor unit 2, thus integrating the worm shaft 44 and the rotating shaft 31. Alternatively, the worm shaft 44 and the rotating shaft 31 can also be formed as one piece by molding the worm shaft portion and the rotating shaft portion from a single base material.

[0102] An output shaft 48 is disposed at the radial center of a worm gear 45 that meshes with a worm shaft 44. The output shaft 48 is coaxial with the rotation axis of the worm gear 45. The output shaft 48 protrudes outward from the gear housing 40 via a bearing boss 49. A spline 48a is formed at the protruding front end of the output shaft 48, which can be connected to an electrical component (not shown).

[0103] Additionally, a sensor magnet (not shown) is provided on the surface opposite to the side protruding from the output shaft 48, at the radial center of the worm gear 45. This sensor magnet constitutes one component of a rotational position detection unit 60 that detects the rotational position of the worm gear 45. A magnetic detection element 61, constituting the other component of the rotational position detection unit 60, is provided in a controller unit 4, which is positioned facing the worm gear 45 on the sensor magnet side (the opening 40a side of the gear housing 40).

[0104] (Controller Department)

[0105] The controller unit 4, which performs drive control of the motor unit 2, includes a controller board 62 on which a magnetic detection element 61 is mounted, and a cover 63 provided in a manner that closes the opening 40a of the gear housing 40. Moreover, the controller board 62 is arranged facing the sensor magnet side of the worm gear 45 (the opening 40a side of the gear housing 40).

[0106] The controller substrate 62 is a substrate formed on a so-called epoxy board with a plurality of conductive patterns (not shown). The terminal portion of the coil 24, which extends from the stator core 20 of the motor section 2, is connected to the controller substrate 62, and terminals (not shown) of a connector provided in the cover 63 are electrically connected to it. In addition to the magnetic detection element 61, a power module (not shown) is also mounted on the controller substrate 62. This power module includes switching elements such as field-effect transistors (FETs) that control the current supplied to the coil 24. Furthermore, a capacitor (not shown) is mounted on the controller substrate 62 to smooth the voltage applied to the controller substrate 62.

[0107] The cover 63 covering the controller substrate 62 thus constructed is formed of resin. In addition, the cover 63 is formed to bulge slightly outward. Moreover, the inner surface of the cover 63 is formed into a controller receiving portion 56 for accommodating the controller substrate 62 and the like.

[0108] Additionally, a connector (not shown) is integrally formed on the outer periphery of the cover 63. This connector is configured to engage with a connector extending from an external power source (not shown). Furthermore, a controller board 62 is electrically connected to the connector terminals (not shown). This allows power from an external power source to be supplied to the controller board 62.

[0109] Here, the controller board 62 energizes the coil 24 with an advance angle and a wide-angle energization with an electrical angle θ ranging from 121° to 180°. In addition, the controller board 62 applies a drive current to the coil 24 that overlaps with the 5th higher harmonic.

[0110] Furthermore, a fitting portion 81 is formed protruding from the opening edge of the cover 63 to engage with the end of the side wall 40b of the gear housing 40. The fitting portion 81 includes two walls 81a and 81b along the opening edge of the cover 63. Then, the end of the side wall 40b of the gear housing 40 is inserted (fitted) between the two walls 81a and 81b. Thus, a labyrinth portion 83 is formed between the gear housing 40 and the cover 63. The labyrinth portion 83 prevents dust or water from seeping in from between the gear housing 40 and the cover 63. Furthermore, the gear housing 40 and the cover 63 are secured by tightening bolts (not shown).

[0111] (The operation of the windshield wiper motor)

[0112] Next, the operation of the wiper motor 1 will be explained.

[0113] In the wiper motor 1, the power supplied to the controller board 62 via connector 11 is selectively supplied to each coil 24 of the motor section 2 via a power module (not shown). The current flowing in each coil 24 then forms a predetermined linked magnetic flux in the stator 8 (rack 22). This linked magnetic flux generates magnetic attraction or repulsion (magnetic torque) between itself and the effective magnetic flux formed by the permanent magnets 33 of the rotor 9.

[0114] In addition, the salient poles 35 of the rotor core 32 generate reluctance torque that makes the salient direction a direction in which the linkage flux from the stator 8 (rack 22) can easily flow, and reduces the reluctance of the linkage flux's magnetic circuit. The torque and reluctance torque generated by these permanent magnets 33 keep the rotor 9 rotating.

[0115] Here, at the front end face 35b of the protruding pole 35 of the rotor core 32 of the rotor 9, a recess 35d is formed throughout the axial direction at the center of the circumference. Therefore, the radial spacing between the front end face 35b of the protruding pole 35 and the rack 22 (particularly the flange portion) of the stator 8 becomes uneven. As a result, during the rotation of the rotor 9, the abrupt change in magnetic flux density generated in the rack 22 (particularly the flange portion) before and after the protruding pole 35 passes between the rack 22 is suppressed, thereby suppressing abrupt torque fluctuations and increases in torque pulsation in the rotor 9.

[0116] Furthermore, compared to the existing rotor 109, the rotor 9 exhibits less circumferential wobble in the permanent magnet 33. When viewed axially, the rotor 9 rotates in both clockwise and counterclockwise directions. Thus, even when the rotor 9 rotates in both directions, the range of circumferential movement of the permanent magnet 33 relative to the rotor core 32 is minimized. Therefore, even in the event of, for example, a positional shift of the permanent magnet 33 causing it to collide with the protruding pole 35 of the rotor core 32, the collision noise is significantly reduced.

[0117] The rotation of rotor 9 is transmitted to worm shaft 44, which is integrated with shaft 31, and then to worm wheel 45, which meshes with worm shaft 44. The rotation of worm wheel 45 is then transmitted to output shaft 48, which is connected to worm wheel 45, and output shaft 48 drives desired electrical components (e.g., windshield wipers).

[0118] Additionally, a detection signal indicating the rotational position of the worm gear 45, detected by the magnetic detection element 61 mounted on the controller board 62, is output to an external device (not shown). This external device is, for example, a software function unit that functions by executing a predetermined program by a processor such as a central processing unit (CPU). The software function unit may be a processor such as a CPU, a read-only memory (ROM) for storing the program, a random access memory (RAM) for temporarily storing data, and an electronic control unit (ECU) including electronic circuitry, such as a counter. Furthermore, at least a portion of the external device (not shown) may be an integrated circuit such as a large-scale integrated circuit (LSI).

[0119] An external device (not shown) controls the switching timing of switching elements in a power module (not shown) based on the rotational position detection signal of the worm gear 45 to drive the motor unit 2. Furthermore, the output of the power module's drive signal and the drive control of the motor unit 2 can also be performed by the controller unit 4, replacing the external device (not shown).

[0120] Thus, in the rotor 9 of this embodiment, the arc center C2 of the outer peripheral surface 32b of the rotor core 32 protrudes radially outward from the center of the circumferential direction between adjacent protrusion poles 35 in the outer peripheral surface 32b, and is offset radially outward from the axis of rotation C1. The permanent magnet 33 is formed in a generally arc shape when viewed from the axial direction, and is formed symmetrical about the center line of the circumferential direction. In addition, the arc center C3 of the inner peripheral surface 33b of the permanent magnet 33 coincides with the arc center C2 of the outer peripheral surface 32b of the rotor core 32. Furthermore, the angle θ1 formed between the opposing protrusion pole sides 35a of adjacent protrusion poles 35 in the circumferential direction and the angle θ2 formed between the magnet sides 33a on both sides of the permanent magnet 33 in the circumferential direction are set to satisfy the above equation (2). Furthermore, the distance Lt between the outer peripheral surface 32b of the rotor core 32 and the outermost radial end of the protruding pole 35, and the distance Lme between the inner peripheral surface 33b of the permanent magnet 33 and the outermost radial end of the magnet side surface 33a are set to satisfy the above equation (3). Therefore, even when the circumferential width of the permanent magnet 33 is smaller than the width between adjacent protruding poles 35 in the circumferential direction (refer to...) Figure 5In the gap S2 in (b), the magnet side 33a will not come into contact with the surface of the pole side 35a due to the shaking of the pole 35 and the permanent magnet 33. Instead, only the outermost radial part of the magnet side 33a abuts against the pole 35. Therefore, the circumferential movement range of the permanent magnet 33 can be reduced, and the degradation of the operating sound or the rotor characteristics of the rotor 9 can be suppressed.

[0121] Furthermore, because the arc center C3 of the inner circumferential surface 33b of the permanent magnet 33 is offset radially outward from the rotation axis C1, it is eccentric. Therefore, the position of the inner circumferential surface 33b of the existing permanent magnet 133 (refer to...) Figure 5 Compared to the double-dotted line in (b), the position of the inner peripheral surface 33b of the permanent magnet 33 in this embodiment can be made further outward in the radial direction. Compared to the conventional method, the wall thickness on the inner peripheral surface 33b side of the permanent magnet 33 can be correspondingly removed, thereby making the radial wall thickness of the permanent magnet 33 thinner. Therefore, the material cost of the permanent magnet 33 can be reduced.

[0122] Furthermore, the arc center C4 of the outer peripheral surface 33c of the permanent magnet 33 is also offset radially outward from the rotation axis C1, thus becoming eccentric. The radial wall thickness Lm at the circumferential center of the permanent magnet 33 is set to satisfy the aforementioned equation (3). Therefore, the material cost of the permanent magnet 33 can be reduced, and by forming the outer peripheral surface 33c of the permanent magnet 33 so that the circumferential center protrudes radially outward, the rotor characteristics can be improved.

[0123] Furthermore, the radius of curvature Ri of the inner peripheral surface 33b and the radius of curvature Ro of the outer peripheral surface 33c of the permanent magnet 33 are set to satisfy the aforementioned equation (1). Therefore, the outer peripheral surface 33c of the permanent magnet 33 can be a gently sloping arc shape, and the inner peripheral surface 33b can be a tighter arc shape relative to the outer peripheral surface 33c. Therefore, compared to the past, the wall thickness on the inner peripheral surface 33b side of the permanent magnet 33 can be reliably removed.

[0124] Furthermore, when viewed axially, the rotor 9 rotates in both clockwise and counterclockwise directions. Thus, even when the rotor 9 rotates in both directions, the circumferential movement of the permanent magnet 33 relative to the rotor core 32 is significantly suppressed. Therefore, even if, for example, the permanent magnet 33 shifts position and collides with the pole face 35 of the rotor core 32, the collision noise can be greatly reduced. Therefore, this structure can be suitably used in a motor unit 2 where the rotor 9 rotates in both directions.

[0125] Furthermore, the present invention is not limited to the described embodiments, but includes embodiments in which various modifications are made to the described embodiments without departing from the spirit of the present invention.

[0126] For example, the wiper motor 1 is listed as an example in the described embodiment, but in addition to the wiper motor 1, the structure of the wiper motor 1 can also be used as a device to drive electrical components (such as power windows, sunroof, power seats, etc.) mounted on a vehicle, or for other various purposes.

[0127] Furthermore, in the described embodiment, the case where the arc center C4 of the outer peripheral surface 33c of the permanent magnet 33 is also offset radially outward from the rotation axis C1, thus becoming eccentric, has been explained. However, this is not a limitation; the arc center C4 of the outer peripheral surface 33c of the permanent magnet 33 may also be non-eccentric.

[0128] Furthermore, in the described embodiment, the distance Lt between the outer peripheral surface 32b of the rotor core 32 and the outermost radial end of the pole 35, the distance Lme between the inner peripheral surface 33b of the permanent magnet 33 and the outermost radial end of the magnet side surface 33a, and the radial wall thickness Lm at the circumferential center of the permanent magnet 33 are set to satisfy the aforementioned equation (3). However, it is not limited to this, as long as at least the distances Lt and Lme are set to satisfy Lme < Lt. With this configuration, the outermost radial end of the magnet side surface 33a can reliably abut against the pole 35.

[0129] Furthermore, in the described embodiment, the arc center C4 of the outer peripheral surface 33c of the permanent magnet 33 coincides with the arc center C3 of the inner peripheral surface 33b of the permanent magnet 33, and the arc center C2 of the outer peripheral surface 32b of the rotor core 32. However, as long as the radius of curvature Ri of the inner peripheral surface 33b of the permanent magnet 33 and the radius of curvature Ro of the outer peripheral surface 33c satisfy the above equation (1), the arc center C4 of the outer peripheral surface 33c may also be offset radially outward than the arc center C3 of the inner peripheral surface 33b.

Claims

1. A rotor, characterized in that, include: The pivot rotates about the axis of rotation; The rotor core is fixed to the rotating shaft and rotates radially around the axis of rotation. Multiple permanent magnets are arranged circumferentially on the outer peripheral surface of the rotor core; as well as Multiple protruding poles protrude from the outer peripheral surface of the rotor core toward the radially outward side and are disposed between adjacent permanent magnets in the circumferential direction, and are formed into a rectangular shape that is radially elongated when viewed from the direction of the rotation axis. The arc center of the outer peripheral surface of the rotor core between the plurality of protruding poles is offset radially outward from the axis of rotation, with the circumferential center between adjacent protruding poles on the outer peripheral surface of the rotor core projecting outward most radially. The permanent magnet has an inner peripheral surface and an outer peripheral surface. The inner peripheral surface is an arc-shaped radially inner side when viewed from the direction of the axis of rotation, and the outer peripheral surface is an arc-shaped radially outer side when viewed from the direction of the axis of rotation. The permanent magnet is formed symmetrical about the center of the circumferential direction. The arc center of the inner peripheral surface of the permanent magnet is offset radially outward from the rotor core. The outer peripheral surface of the rotor core is offset radially outward from the axis of rotation, and the angle between the opposing sides of two adjacent protrusions in the circumferential direction is the same as the angle between the two sides of the permanent magnet in the circumferential direction facing each other. When the distance between the outer peripheral surface of the rotor core and the outermost radial end of the protrusion is set to Lt, and the distance between the inner peripheral surface of the permanent magnet and the outermost radial end of the side of the permanent magnet is set to Lme, each distance Lt and distance Lme is set to satisfy Lme < Lt.

2. A motor, characterized in that, include: The stator has an annular stator core and a plurality of racks protruding from the inner circumferential surface of the stator core toward the radial direction. A coil is mounted on the rack; as well as The rotor according to claim 1 is arranged radially inside the plurality of racks, and when viewed from the direction of the rotation axis, the rotor rotates in both clockwise and counterclockwise directions.

3. A windshield wiper motor, characterized in that, include: The motor as described in claim 2; And a deceleration unit, which reduces the rotation of the shaft and outputs the deceleration.

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