motor

Abstract

A motor according to one embodiment of the present invention comprises: a rotor having a covered cylindrical rotor core and a hollow cylindrical magnet, the rotor core having a shaft extending along a central axis, the magnet being arranged on the inner circumferential side of the rotor core; a detection element detecting a magnetic flux density of the magnet; and a signal output unit outputting a signal related to a rotation speed of the rotor according to the magnetic flux density, wherein a first pole and a second pole of the magnet are alternately arranged in a circumferential direction, and the magnet comprises a first magnetization boundary portion in which the first pole and the second pole are arranged in a direction opposite to a rotation direction, and a second magnetization boundary portion in which the second pole and the first pole are arranged in a direction opposite to a rotation direction, and when viewed from above in a direction along the central axis, the first magnetization boundary portion is located on a straight line passing through a central axis of the magnet and a central axis passing through the center of the magnet.

Description

Technical Field

[0001] The present invention relates to motors.

[0002] This application claims priority based on Japanese Patent Application No. 2018-183961 filed in Japan on September 28, 2018, and the contents are incorporated herein by reference. Background Art

[0003] In recent years, brushless DC motors have been used as motors mounted in electronic devices. Patent Document 1 below discloses a technology for controlling the rotation of an outer rotor type brushless DC motor by using an FG signal related to the rotation speed of the rotor. In this brushless DC motor, a sensor is used to detect the magnetism from a magnet provided on the rotor, and an FG signal is generated based on the detection result.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2010-41872 Summary of the invention

[0007] Problems to be solved by the invention

[0008] The rotor is constructed by attaching magnets to the inner circumference of the rotor core, but it is difficult to accurately fit the rotor core and the magnets, and the rotor core and the magnets are in a state where the central axes are offset from each other. In this way, the magnets with a position offset relative to the rotor core are eccentric when the rotor rotates. The position of the magnet rotating in an eccentric state changes radially relative to the sensor, so although the rotation accuracy of the rotor is good, the rotation accuracy of the FG signal is deteriorated.

[0009] In view of the above circumstances, one object of the present invention is to provide a motor capable of reducing deterioration in rotation accuracy of an FG signal even when eccentricity occurs during rotor rotation.

[0010] Means for solving problems

[0011] A motor according to one embodiment of the present invention comprises: a rotor having a covered cylindrical rotor core and a hollow cylindrical magnet, the rotor core having a shaft extending along a central axis, the magnet being arranged on the inner circumferential side of the rotor core; a detection element detecting a magnetic flux density of the magnet; and a signal output unit outputting a signal related to a rotation speed of the rotor according to the magnetic flux density, wherein a first pole and a second pole of the magnet are alternately arranged along a circumferential direction, and the magnet comprises a first magnetization boundary portion of the first pole and the second pole arranged from the rear in the rotation direction to the front in the rotation direction, and a second magnetization boundary portion of the second pole and the first pole arranged from the rear in the rotation direction to the front in the rotation direction, wherein the first magnetization boundary portion is located on a straight line passing through a central axis of the magnet and the central axis, the central axis of the magnet passing through the center of the magnet.

[0012] Effects of the Invention

[0013] According to one aspect of the present invention, there is provided a motor capable of reducing deterioration in rotation accuracy of an FG signal even when eccentricity occurs during rotation of a rotor. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a cross-sectional view of the motor.

[0015] Figure 2 This is a top view of the magnets that make up the rotor.

[0016] Figure 3 It is a graph showing the relationship between the magnetic flux density and the FG signal.

[0017] Figure 4 1 is a diagram showing the positional relationship between the detection element and the magnet in the non-eccentric rotor.

[0018] Figure 5A It is a top view of the first rotor.

[0019] Figure 5B It is a top view of the second rotor.

[0020] Figure 5C This is a top view of the third rotor.

[0021] Figure 6 It is a diagram showing changes in the positional relationship between the magnet and the detection element when the third rotor rotates.

[0022] Fig. 7A This is a diagram for explaining the vibration detection process.

[0023] Figure 7B This is a diagram for explaining the marking process.

[0024] Figure 7C This is a diagram for explaining the magnetization process.

[0025] Figure 8 It is a diagram showing the appearance of a motor.

[0026] Fig. 9 It is a horizontal cross-sectional view of a vehicle headlamp. DETAILED DESCRIPTION

[0027] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the scope of the present invention is not limited to the following embodiments, and can be arbitrarily changed within the scope of the technical concept of the present invention.

[0028] A motor according to the present embodiment relates to a motor for driving a rotating reflector that forms a light distribution pattern and is incorporated in a vehicle headlamp.

[0029] Figure 1 2 is a cross-sectional view of the motor of this embodiment. The motor of this embodiment is an outer rotor type motor. Figure 1 As shown, the motor 10 of the present embodiment includes a stator 1, a rotor 2, a bearing 3, a circuit board 4, and a detection element 5. The motor 10 of the present embodiment is an outer rotor type motor in which the rotor 2 is arranged on the outer peripheral side of the stator 1.

[0030] Including Figure 1 In the following drawings, in order to facilitate understanding of each structure, the actual structure may be different from the scale or number of each structure. Unless otherwise specified, the direction parallel to the central axis J is referred to as the "axial direction", the radial direction centered on the central axis J is referred to as the "radial direction", and the circumferential direction centered on the central axis J, that is, the direction around the central axis J is referred to as the "circumferential direction". In addition, in the following description, "top view" refers to the state of viewing from the axial direction.

[0031] The stator 1 has: a roughly cylindrical bearing retaining portion 1a centered on the central axis J; a stator core 1b mounted on the radially outer side of the bearing retaining portion 1a; and a coil 1c mounted on the stator core 1b. The bearing retaining portion 1a supports two bearings 3 as part of a bearing mechanism in the axial direction. The stator core 1b is formed as a stacked body formed by stacking a plurality of plate-like bodies. On the outer periphery of the stator core 1b, a plurality of teeth serving as each magnetic pole are arranged at predetermined intervals in the circumferential direction. In addition, the coil 1c is wound around the arm portion of the magnetic circuit constituting the inner side of each tooth via an insulating member (not shown). In this way, a stator 1 having a coil 1c wound on the stator core 1b is formed.

[0032] The rotor 2 is supported so as to be rotatable relative to the stator 1 about the central axis J via the bearing 3. The rotor 2 includes: a metal rotor core 8, which is substantially cylindrical with a cover and has magnetism, centered on the central axis J; a magnet 6, which is provided on the inner side (i.e., the inner circumference) of the side wall portion of the rotor core 8 and is arranged opposite to the coil 1c of the stator 1; and a shaft 9, which extends from the rotor core 8 along the central axis J. The center of the shaft 9 coincides with the central axis J. In addition, the shaft 9 may be composed of the same component as the rotor core 8, or may be composed of a component different from the rotor core 8. A rotating body (not shown) rotated by a motor 10 is mounted on the shaft 9. The motor 10 controls the rotation of the rotating body mounted on the shaft 9.

[0033] The rotor 2 of this embodiment is configured by fixing the magnet 6 to the inner circumference of the rotor core 8 via the adhesive 7. Thus, in the rotor 2 of this embodiment, the rotor core 8 and the magnet 6 can be easily fixed, so the manufacturing process of the rotor 2 is easy.

[0034] Figure 2 This is a top view of the magnets that make up the rotor.

[0035] like Figure 2 As shown, the magnet 6 is formed of a substantially hollow cylindrical shape extending along the magnet center axis 6C, and two S poles (first pole) 6s and two N poles (second pole) 6n are arranged alternately along the circumferential direction. The magnet center axis 6C passes through the center of gravity of the magnet 6. In the magnet 6 of this embodiment, a plurality of magnetization boundary portions 15 are arranged at intervals of 90° in the entire circumferential direction. The magnetization boundary portion 15 constitutes the boundary between the S pole 6s and the N pole 6n.

[0036] The rotor 2 of the present embodiment is a four-pole rotor. The rotor 2 of the present embodiment rotates in a counterclockwise rotation direction R in a plan view.

[0037] The plurality of magnetization boundary portions 15 include a pair of first magnetization boundary portions 16a, 16b and a pair of second magnetization boundary portions 17a, 17b. The first magnetization boundary portions 16a, 16b are magnetization boundaries where the S pole 6s and the N pole 6n are arranged in a direction opposite to the rotation direction R of the magnet 6. The second magnetization boundary portions 17a, 17b are magnetization boundaries where the N pole 6n and the S pole 6s are arranged in a direction opposite to the rotation direction R of the magnet 6.

[0038] return Figure 1 The circuit board 4 is held by being inserted into the bearing holding portion 1a of the stator 1. The circuit board 4 is in a substantially annular plate shape and is electrically connected to a lead wire (not shown) led out from the coil 1c of the stator 1 to control the rotation of the rotor 2. In addition to the detection element 5, the circuit board 4 is also equipped with, for example, an integrated circuit and a capacitor (not shown).

[0039] The motor 10 of this embodiment generates magnetic fields alternately from each tooth by passing an alternating current through the coil 1c, thereby generating attractive forces and repulsive forces between the magnetic fields from each tooth and the magnet 6. As a result, the rotor 2 rotates around the central axis J.

[0040] In the present embodiment, the detection element 5 is disposed on the upper surface 4a of the circuit board 4 that is opposite to the rotor 2. The detection element 5 is composed of a Hall element such as a Hall IC. The detection element 5 detects the magnetic flux density of the magnet 6 in the rotating rotor 2 and sends the detection result to the circuit board 4. The circuit board 4 includes an output unit 4b that outputs an FG signal according to the magnetic flux density of the magnet 6. The FG signal is a signal containing a frequency component corresponding to the rotation speed of the rotor 2, and is output from the output unit 4b of the circuit board 4. The FG signal is used for the rotating reflector 124 described later (refer to Fig. 9 ) in the light distribution control.

[0041] Here, the relationship between the magnetic flux density and the FG signal will be described with reference to the drawings.

[0042] Figure 3 It is a graph showing the relationship between the magnetic flux density and the FG signal. Figure 3 The upper part of represents the magnetic flux density detected by the detection element 5, the horizontal axis corresponds to the rotation angle of the motor (the unit is deg), and the vertical axis corresponds to the magnetic flux density (the unit is mT). Figure 3 The lower part shows the FG signal output according to the magnetic flux density.

[0043] First, the magnetic flux density is explained. When the magnetic flux from the S pole 6s of the magnet 6 is detected by the detection element 5, the first detection value of the magnetic flux density of the detection element 5 is "negative". In addition, when the magnetic flux from the N pole of the magnet 6 is detected by the detection element 5, the second detection value of the magnetic flux density of the detection element 5 is "positive". Therefore, as the rotor 2 rotates, the magnetic pole position of the magnet 6 relative to the detection element 5 changes, and the magnetic flux density is changed from Figure 3 The periodically changing waveform shown is specified.

[0044] When the rotor rotates, the magnetic pole detected by the detection element 5 switches from the S pole 6s to the N pole 6n before and after the first magnetization boundary portions 16a and 16b pass through the detection element 5. That is, when the first magnetization boundary portions 16a and 16b pass through the detection element 5, the magnetic flux density of the detection element 5 changes from the first detection value (negative value) to the second detection value (positive value).

[0045] On the other hand, when the rotor rotates, the magnetic pole detected by the detection element 5 switches from the N pole 6n to the S pole 6s before and after the second magnetization boundary portions 17a and 17b pass through the detection element 5. That is, when the second magnetization boundary portions 17a and 17b pass through the detection element 5, the magnetic flux density of the detection element 5 changes from the second detection value (positive value) to the first detection value (negative value).

[0046] The circuit board 4 of this embodiment generates and outputs the FG signal through the output unit 4b according to the timing of switching the magnetic flux density sent from the detection element 5 from the first detection value to the second detection value. In other words, it can be said that the FG signal is generated according to the timing when the first magnetization boundary portions 16a and 16b pass through the detection element 5.

[0047] The FG signal is defined by a pulse that falls from "high" to "low" when the first magnetization boundary portions 16a and 16b pass through the detection element 5 and rises from "low" to "high" when the second magnetization boundary portions 17a and 17b pass through the detection element 5.

[0048] As mentioned above, Figure 1 As shown, the rotor 2 of the present embodiment is configured by fixing the magnet 6 to the inner circumference of the rotor core 8 via an adhesive 7 .

[0049] However, the adhesive 7 changes in volume before and after curing, and the thickness tends to become uneven depending on the location. Therefore, in the rotor 2 of the present embodiment, the magnet 6 is positionally offset relative to the rotor core 8. Specifically, in the rotor 2 of the present embodiment, the center axis J of the rotor core 8 and the magnet center axis 6C of the magnet 6 are arranged in different locations. Therefore, in the rotor 2 of the present embodiment, the magnet 6 rotates in an eccentric state relative to the shaft 9 (center axis J) which is the rotation axis of the rotor 2. Hereinafter, the rotor 2 in which the magnet 6 rotates in an eccentric state is referred to as an "eccentric rotor", and the rotor 2 in which the magnet rotates in an ideal state without eccentricity is referred to as a "non-eccentric rotor".

[0050] Here, for comparison, a non-eccentric rotor is considered. That is, the non-eccentric rotor refers to a state in which the thickness of the adhesive 7 is uniform and the central axis J of the rotor core 8 is consistent with the magnet central axis 6C of the magnet 6. Such a non-eccentric rotor rotates in a state in which the central axis J of the rotor core 8 is consistent with the magnet central axis 6C of the magnet 6. In this case, in the non-eccentric rotor, the magnet 6 rotates around the magnet central axis 6C.

[0051] Figure 4 1 is a diagram showing the positional relationship between the detection element and the magnet in a non-eccentric core rotor.

[0052] Figure 4The figure shows the change in the positional relationship between the detection element 5 and the magnet 6 when the rotation angle of the non-eccentric rotor 12 changes from 0° to 90°. Figure 4 In order to facilitate observation of the figure, the position of the detection element 5 is moved to the radially outer side of the magnet 6 for illustration.

[0053] exist Figure 4 In the embodiment, the rotation angle of the rotor 12 is set to 0° when the first magnetization boundary 16a of the magnet 6 is located on a line (hereinafter referred to as a reference line K) passing through the detection element 5 and the center axis J. When the rotation angle of the rotor 12 is 0°, the state in which the first magnetization boundary 16a is located on the reference line K corresponds to the timing when the magnetic flux density in the detection element 5 switches from the first detection value (negative) to the second detection value (positive). In addition, during the rotation of the non-eccentric rotor 12, the positional relationship between the center axis J (magnet center axis 6C) and the detection element 5 does not change but remains constant.

[0054] like Figure 4 As shown, in the non-eccentric core rotor 12, the magnet 6 rotates 180° after the first magnetization boundary portion 16a passes the reference line K until the first magnetization boundary portion 16b passes the reference line K. Similarly, the magnet 6 rotates 180° after the first magnetization boundary portion 16b passes the reference line K until the first magnetization boundary portion 16a passes the reference line K. Therefore, in the non-eccentric core rotor 12, the magnetic flux density in the detection element 5 switches from "negative: first detection value" to "positive: second detection value" every time it rotates 180°.

[0055] Thus, according to the non-eccentric rotor 12, the magnetic flux density changes in a certain period (a period of half a rotation of the rotor). Therefore, the rotation accuracy of the FG signal output according to the magnetic flux density also becomes higher. Here, the high rotation accuracy of the FG signal means Figure 3 The time of one pulse of the FG signal shown is in a constant state.

[0056] Therefore, a high rotational accuracy FG signal can be generated as long as there is no eccentric rotor 12. On the other hand, in an eccentric rotor, as described later, the magnetic flux density periodically fluctuates, so there is a problem that the rotational accuracy of the FG signal output according to the magnetic flux density is reduced.

[0057] In contrast, the present inventors have found that by appropriately setting the positional relationship between the magnet center axis 6C, the center axis J, and the first magnetization boundary portions 16a and 16b, the deterioration of the rotation accuracy of the FG signal can be reduced even in an eccentric rotor 2. And the rotor 2 of this embodiment is completed. That is, according to the rotor 2 of this embodiment, as described later, even if the magnet 6 rotates in an eccentric state (that is, an eccentric rotor 2), the deterioration of the rotation accuracy of the FG signal can be reduced.

[0058] Here, the first rotor, the second rotor, and the third rotor are described as examples in which the eccentric directions of the magnet center axis 6C with respect to the center axis J are different. Figure 4 The non-eccentric rotor 12 shown has a structure in which the positions of the magnets 6 at a rotation angle of 0° are eccentric from the central axis J in different directions.

[0059] Figure 5A is a top view of the first rotor. Figure 5A As shown, in the first rotor 2A, the magnet center axis 6C is eccentric to one side (eg, lower left side) in an inclined direction intersecting the reference line K at an angle of 45° with respect to the center axis J. In addition, the magnet 6 rotates around the center axis J counterclockwise.

[0060] Here, a first imaginary line L1 connecting the radially inner end surface 16a1 of the first magnetization boundary portion 16a and the central axis J and a second imaginary line L2 connecting the radially inner end surface 16b1 of the first magnetization boundary portion 16b and the central axis J are defined.

[0061] Furthermore, an angle formed between the first imaginary line L1 and the second imaginary line L2 located in the clockwise direction relative to the first imaginary line L1 is set as a first angle θ1, and an angle formed between the first imaginary line L1 and the second imaginary line L2 located in the counterclockwise direction relative to the first imaginary line L1 is set as a second angle θ2. The first angle θ1 is smaller than 180 degrees, and the second angle θ2 is larger than 180 degrees.

[0062] The first angle θ1 corresponds to the first rotation angle of the first rotor 2A until the first magnetization boundary portions 16a and 16b pass through the detection element 5. The second angle θ2 corresponds to the second rotation angle of the first rotor 2A until the first magnetization boundary portions 16b and 16a pass through the detection element 5.

[0063] In this way, when a difference occurs between the first rotation angle and the second rotation angle, a difference occurs between a first period of the first magnetic flux density generated by the first rotor 2A rotating at the first rotation angle and a second period of the second magnetic flux density generated by the first rotor 2A rotating at the second rotation angle. Specifically, the first period in which the rotation angle (first rotation angle) of the first rotor 2A is small is shorter than the second period in which the rotation angle (second rotation angle) of the first rotor 2A is large.

[0064] Thus, when the period of the first magnetic flux density and the second magnetic flux density differ, the pulse period of the FG signal outputted according to the first magnetic flux density and the second magnetic flux density is not constant. That is, the time of one pulse of the FG signal outputted according to the first magnetic flux density and the second magnetic flux density differs. Therefore, the rotation accuracy of the generated FG signal is reduced.

[0065] In addition, in the first rotor 2A, the eccentric direction of the magnet center axis 6C relative to the center axis J is described as being the left oblique lower side, but the eccentric direction of the magnet center axis 6C is not limited to this. That is, the eccentric direction of the magnet center axis 6C is not particularly limited as long as it is a direction that intersects the reference line K at an angle other than 45° (except 90° described later). For example, the eccentric direction of the magnet center axis 6C relative to the center axis J may be the right oblique upper side, the right oblique lower side, or the left oblique upper side.

[0066] Therefore, if the rotor 2 of this embodiment adopts the structure of the first rotor 2A, the accuracy of the FG signal generated due to the influence of eccentricity decreases. Therefore, the rotor 2 of this embodiment adopts a structure different from the first rotor 2A.

[0067] Figure 5B is a top view of the second rotor. Figure 5B As shown, in the second rotor 2B, the magnet center axis 6C is eccentric to one side (eg, lower side) in the vertical direction intersecting (perpendicular to) the reference line K at an angle of 90° with respect to the center axis J. In addition, the magnet 6 rotates around the center axis J counterclockwise.

[0068] In the second rotor 2B, the first imaginary line L1, the second imaginary line L2, the first angle θ1, and the second angle θ2 are defined in the same manner as in the first rotor 2A. Figure 5B As shown, the first angle θ1 is smaller than 180°, and the second angle θ2 is larger than 180°.

[0069] like Figure 5B As shown, in the second rotor 2B, the first rotation angle and the second rotation angle also differ, so the periods of the first magnetic flux density and the second magnetic flux density differ. Therefore, the pulse period of the FG signal outputted according to the first magnetic flux density and the second magnetic flux density is not constant. That is, the time of one pulse of the FG signal outputted according to the first magnetic flux density and the second magnetic flux density differs. Therefore, the rotation accuracy of the generated FG signal is reduced.

[0070] In the second rotor 2B, the eccentric direction of the magnet center axis 6C relative to the center axis J is described as being the lower side, but the eccentric direction of the magnet center axis 6C is not limited thereto. That is, the eccentric direction of the magnet center axis 6C relative to the center axis J may be the upper side.

[0071] Therefore, if the rotor 2 of this embodiment adopts the structure of the second rotor 2B, the rotation accuracy of the FG signal generated due to the influence of eccentricity decreases. Therefore, the rotor 2 of this embodiment adopts a structure different from the second rotor 2B.

[0072] Figure 5C is a top view of the third rotor. Figure 5C As shown, in the third rotor 2C, the magnet center axis 6C is eccentric to one side (e.g., left side) in the direction along the reference line K relative to the center axis J. In addition, the magnet 6 rotates counterclockwise around the center axis J. In addition, the rotor 2 of this embodiment adopts the structure of the third rotor 2C. The reason for adopting the third rotor 2C is described below.

[0073] Specifically, in the third rotor 2C, the first magnetization boundary portions 16a and 16b are located on a straight line L passing through the magnet center axis 6C and the center axis J. That is, the first magnetization boundary portions 16a and 16b, the magnet center axis 6C, and the center axis J are arranged on the straight line L.

[0074] In the present embodiment, the first magnetization boundary portions 16a, 16b have a predetermined width in the circumferential direction. Therefore, in the present embodiment, the first magnetization boundary portions 16a, 16b, the magnet center axis 6C, and the center axis J are arranged on the straight line L, which is not limited to the state where the circumferential center of the first magnetization boundary portions 16a, 16b is completely consistent with the straight line L, and also includes, for example, the state where at least a portion of the first magnetization boundary portions 16a, 16b overlaps with the straight line L in the circumferential direction.

[0075] In the third rotor 2C, the first imaginary line L1, the second imaginary line L2, the first angle θ1, and the second angle θ2 are defined similarly to the first rotor 2A and the second rotor 2B. Figure 5C As shown, in the third rotor 2C, the first magnetization boundary portions 16 a and 16 b and the central axis J are arranged on a straight line, so the first angle θ1 and the second angle θ2 are each 180°.

[0076] In the third rotor 2C, the rotor rotation angle (first rotation angle) until the first magnetization boundary portions 16a, 16b sequentially pass the detection element 5 and the rotor rotation angle (second rotation angle) until the first magnetization boundary portions 16b, 16a sequentially pass the detection element 5 are both 180°.

[0077] Figure 6 : is a diagram showing the change in the positional relationship between the magnet and the detection element when the third rotor rotates. Figure 6 As shown, in the third rotor 2C, although the magnet 6 rotates in an eccentric state, the first magnetization boundary portions 16 a and 16 b pass through the detection element 5 every time the rotor rotates 180°.

[0078] Therefore, the periods of the first magnetic flux density and the second magnetic flux density generated each time the third rotor 2C rotates half a turn (rotates 180 degrees) are equal. Therefore, the pulse period (one pulse time) of the FG signal output according to the first magnetic flux density and the pulse period (one pulse time) of the FG signal output according to the second magnetic flux density are constant. That is, there is no difference in the time of one pulse of the FG signal output according to the first magnetic flux density and the second magnetic flux density, respectively, so it is possible to output a FG signal with high rotation accuracy without being affected by the eccentricity of the magnet 6.

[0079] In addition, in the third rotor 2C, the eccentric direction of the magnet center axis 6C relative to the center axis J is described as being on the left side of the direction along the reference line K, but the eccentric direction of the magnet center axis 6C is not limited thereto. That is, the eccentric direction of the magnet center axis 6C is not particularly limited as long as it is along the reference line K, and for example, it may be on the right side of the direction along the reference line K.

[0080] For the reasons described above, the rotor 2 of the present embodiment adopts the structure of the third rotor 2C. That is, in the rotor 2 of the present embodiment, the first magnetization boundary portions 16a, 16b, the magnet center axis 6C, and the center axis J are arranged on the straight line L. Therefore, according to the motor 10 of the present embodiment having the rotor 2 adopting the structure of the third rotor 2C, even when the magnet 6 rotates in an eccentric state, it is possible to reduce the deterioration of the rotation accuracy of the FG signal.

[0081] Therefore, the motor 10 of the present embodiment can reduce the deterioration of the rotation accuracy of the FG signal without being affected by the eccentricity generated in the rotor. Therefore, the motor 10 of the present embodiment can output the FG signal with high rotation accuracy.

[0082] (Motor Manufacturing Method)

[0083] Next, a method for manufacturing the motor 10 of the present embodiment will be described. In this description, a method for manufacturing the rotor 2 in the motor 10 is characteristic, and therefore the description will be centered on the method for manufacturing the rotor 2 .

[0084] Figure 7A to Figure 7C This is a diagram for explaining a method for manufacturing the rotor 2 .

[0085] First, a vibration detection process is performed. Fig. 7A This is a diagram for explaining the vibration detection process.

[0086] In the vibration detection process, Fig. 7AAs shown in the figure, a rotor structural member 20 is prepared in which a hollow cylindrical magnet material 26 is attached to the inner peripheral side of a covered cylindrical rotor core 8 having a shaft 9 extending along a central axis J. The magnet material 26 is a material composed of a magnetic body, and forms the above-mentioned magnet 6 by magnetization. The magnet material 26 is attached to the inner peripheral side of the rotor core 8 with the aid of an adhesive 7.

[0087] As described above, the adhesive 7 changes in volume before and after curing, and the thickness becomes non-uniform depending on the location, so the magnet material 26 is positionally offset relative to the rotor core 8. Specifically, in the rotor structural member 20, the center axis J of the rotor core 8 and the center axis (magnet material center axis) 26C of the magnet material 26 are arranged at different positions. In addition, the center axis 26C coincides with the magnet center axis 6C of the magnet 6.

[0088] Next, the direction of the vibration E of the center axis 26C relative to the center axis J (shaft 9) is determined in the rotor structural member 20. As a method for determining the vibration direction, for example, the roller is moved over the entire area of ​​the inner circumference by rotating the rotor structural member 20 while the roller is in contact with the inner circumference of the magnet material 26, thereby determining the position of the center axis 26C of the magnet material 26 and detecting the vibration of the center axis 26C relative to the center axis J.

[0089] In this way, the vibration detection step of detecting the vibration E in the rotor structural member 20 is completed.

[0090] In the vibration detection step, after the vibration of the rotor component 20 is detected, the rotor component 20 is fixed by vacuum, for example, and then the rotor component 20 is handed over to a marking device for a marking step described later while maintaining its orientation.

[0091] Next, a marking process is performed. Figure 7B This is a diagram for explaining the marking process.

[0092] In the marking process, Figure 7B As shown, the outer peripheral surface 8a of the rotor core 8 is marked based on the detection results of the above-mentioned vibration detection step. Specifically, in the marking step, the outer peripheral surface 8a is marked at a location having a predetermined positional relationship with respect to the straight line L3 passing through the center axis 26C and the center axis J.

[0093] In this embodiment, the location on the outer peripheral surface 8a having a predetermined positional relationship with the straight line L3 is a location overlapping the straight line L3. That is, the mark (marking portion) M marked in the marking step is aligned with the central axis 26C and the central axis J on a straight line.

[0094] In this embodiment, as the position accuracy of the mark, the mark M is set within a range of ±3° or less relative to the straight line L3 in the circumferential direction. For example, in the case where the size of the rotor component 20 (rotor core 8) is In the case of , the width H1 of the mark M of the marking that converges within the range of ±3° or less in the circumferential direction is 1.08 mm or less.

[0095] Here, the marking method is not particularly limited, and for example, a magic pen may be used to mark the mark M on the outer peripheral surface 8 a.

[0096] In this embodiment, the mark M composed of a plurality of ink droplets is marked by using an inkjet method using an inkjet device. The inkjet device performs marking, for example, in a state where the rotor component 20 is fixed in a vacuum. In addition, the inkjet device may use an imaging device such as a CCD camera after marking to determine whether the mark M is accurately marked.

[0097] In the marking process of this embodiment, the inkjet method is used, so by ejecting ink droplets onto the outer peripheral surface 8a of the rotor core 8, the mark M can be marked with a desired width with high accuracy. In addition, unlike laser marking, marking by the inkjet method can mark the mark M without damaging the surface of the rotor core 8.

[0098] In this way, the marking process of the rotor structural component 20 is completed.

[0099] Next, a magnetization process is performed. Figure 7C This is a diagram for explaining the magnetization process.

[0100] In the magnetization process, Figure 7C As shown, the magnet material 26 is magnetized according to the symbol M in the marking step to obtain the magnet 6 . Specifically, the rotor component 20 is inserted into the magnetizing yoke 40 , and the magnet material 26 is magnetized from the outside of the rotor core 8 .

[0101] like Figure 2 As shown, the magnet 6 has the first magnetization boundary portions 16a and 16b in which the S pole 6s and the N pole 6n are arranged from the rear to the front in the rotation direction R. In the magnetization step, according to the symbol M, the magnet material 26 and the magnetizing yoke 40 are magnetized in a state where they are aligned so that the first magnetization boundary portions 16a and 16b are located on the straight line L3.

[0102] According to the present embodiment, by aligning the magnet material 26 and the magnetizing yoke 40 using the mark M located on the straight line L3 as a marker, the magnet 6 in which the first magnetization boundary portions 16 a and 16 b are located on the straight line L3 can be produced.

[0103] In this way, the magnetization process of the magnet 6 is completed.

[0104] In the present embodiment, as described above, the mark M is set within a range of ±3° or less relative to the straight line L3 in the circumferential direction. In the magnetization process of the present embodiment, the magnet material 26 and the magnetizing yoke 40 are aligned and magnetized according to the mark M, so that the error of the magnetization position generated by the magnet 6 can be suppressed to, for example, ±8° or less in the circumferential direction.

[0105] In addition, the center axis 26C coincides with the magnet center axis 6C of the magnet 6, and therefore the straight line L3 passing through the center axis 26C and the center axis J corresponds to the straight line L passing through the magnet center axis 6C and the center axis J. Therefore, according to the magnetization process of this embodiment, the rotor 2 in which the first magnetization boundary portions 16a and 16b are located on the straight line L can be manufactured.

[0106] In addition, in the marking process when manufacturing the motor 10, the position where the mark M is set is not limited to the place overlapping with the straight line L3. That is, when the magnet material 26 is magnetized to generate the magnet 6, the place where the mark M is set can be any place as long as the position of the straight line L3 passing through the center axis 26C and the center axis J can be determined based on the mark M. As long as the position of the straight line L3 can be determined, the magnet material 26 can be magnetized in a state where it is aligned with the magnetizing yoke 40 so that the first magnetization boundary portions 16a and 16b are located on the straight line L3. In addition, the mark M can also be composed of multiple parts. For example, the mark M can also be composed of two marks in a separated manner on the circumferential direction of the outer peripheral surface 8a. In this case, it is sufficient to constitute the mark M in such a way that the center of the two marks in the circumferential direction is located on the straight line L3. The mark M has a predetermined positional relationship relative to the straight line L3, that is, the midpoint of the two marks is located on the straight line L3.

[0107] Next, by assembling the stator 1, the rotor 2, the bearing 3, the circuit board 4, and the detection element 5 to the rotor 2 manufactured as described above, it is possible to manufacture Figure 1 The motor 10 is shown.

[0108] Figure 8 It is a diagram showing the appearance of the motor according to the present embodiment.

[0109] like Figure 8As shown, the motor 10 of the present embodiment has a mark (marking portion) M provided on the outer peripheral surface 8a of the rotor core 8. The mark M is formed by the above-mentioned marking process. As described above, the center axis 26C coincides with the magnet center axis 6C. Therefore, the mark M is provided on the outer peripheral surface 8a in a manner having a predetermined positional relationship with respect to the above-mentioned straight line L passing through the magnet center axis 6C and the center axis J. Specifically, the mark M is provided on the outer peripheral surface 8a located on the straight line L. In the motor 10 of the present embodiment, the mark M, the first magnetization boundary portions 16a, 16b, the magnet center axis 6C, and the center axis J are located on the straight line L.

[0110] As described above, according to the motor 10 of the present embodiment, the magnet 6 is magnetized according to the symbol M, thereby having the rotor 2 in which the first magnetization boundary portions 16a, 16b, the magnet center axis 6C, and the center axis J are arranged on the straight line L. Therefore, according to the motor 10 having the rotor 2, even when the rotor is eccentric, it is possible to reduce the deterioration of the rotation accuracy of the FG signal without being affected by the eccentricity.

[0111] Next, a vehicle headlamp equipped with the motor 10 according to the present embodiment will be described in outline. Fig. 9 It is a horizontal cross-sectional view of a vehicle headlamp. Fig. 9 The vehicle headlamp 100 shown is a left-side headlamp mounted on the left side of the front end of the vehicle, and has the same structure as the headlamp mounted on the right side except that they are bilaterally symmetrical. Therefore, the left-side vehicle headlamp 100 will be described in detail below, and the description of the right-side vehicle headlamp will be omitted.

[0112] like Fig. 9 As shown, the vehicle headlamp 100 includes a lamp body 112 having a recessed portion opened forward. The front opening of the lamp body 112 is covered by a transparent front cover 114 to form a lamp chamber 116. The lamp chamber 116 functions as a space for accommodating a lamp unit 118.

[0113] The lamp unit 118 is a unit using the ADB technology of the blade scanning method, and is configured to emit a so-called variable high beam. The lamp unit 118 has an optical unit 120 and a projection lens 122. The optical unit 120 has a rotating reflector 124 and a light source 126. The projection lens 122 uses, for example, a convex lens. The shape of the convex lens can be appropriately selected according to the required light distribution pattern or illumination distribution and other light distribution characteristics, but an aspherical lens or a free-form surface lens is used. In addition, an extended reflector 123 is provided around the projection lens 122.

[0114] The rotating reflector 124 is configured to reflect the light emitted from the light source 126 while rotating in one direction with the rotation axis O1 as the center by the motor 10 as the driving source, and to form a light distribution pattern by scanning the reflected light. In addition, the rotating reflector 124 has an annular reflection area 124a, which is configured to reflect the light emitted from the light source 126 while rotating to form a desired light distribution pattern. In addition, the control circuit 148 controls the light distribution pattern using the FG signal output from the motor 10. The motor 10 of this embodiment outputs an FG signal with high rotation accuracy, so the control circuit 148 can control the light distribution pattern with high accuracy.

[0115] The light source 126 is preferably capable of being controlled to light up and turn off in a short time, and is preferably a semiconductor light emitting element such as an LED, LD, or EL element.

[0116] The motor 10 is mounted on a substrate 132. The substrate 132 is mounted and fixed on a mounting surface 134a of a heat sink 134. The mounting surface 134a is configured so that the rotation axis O1 of the rotating reflector 124 is inclined with respect to the optical axis AX or the vehicle front direction when the substrate 132 is mounted.

[0117] The light source 126 is mounted on a substrate 136. In addition, a lens 138 as a primary optical system is provided in the light emitting direction of the light source 126 and between the rotating reflector 124. The lens 138 converges the emitted light of the light source 126 so that the light emitted from the light source 126 is directed toward the reflection area 124a of the rotating reflector 124. The substrate 136 is mounted on a heat sink 140. The heat sink 134 and the heat sink 140 are fixed to a metal plate-shaped support member 142. Furthermore, the lamp unit 118 is supported by a unit using a calibration screw 144 and a nut 146 via the support member 142 so as to be freely tiltable relative to the lamp body 112.

[0118] The control circuit 148 is connected to the light source 126 and the motor 10 via the respective substrates, transmits a signal for controlling the light source 126 and the motor 10 , and receives an FG signal output from the motor 10 .

[0119] An embodiment of the present invention has been described above, but the various structures and their combinations in the embodiment are examples, and addition, omission, substitution and other changes of structures can be made within the scope of the present invention. In addition, the present invention is not limited to the embodiment.

[0120] Description of symbols

[0121] 2, 12: rotor; 4b: output part; 5: detection element; 6: magnet; 6n: N pole (second pole); 6s: S pole (first pole); 6C: center axis of magnet; 7: adhesive; 8: rotor core; 9: shaft; 10: motor; 15: magnetization boundary; 16a, 16b: first magnetization boundary; 17a, 17b: second magnetization boundary; 26C, J: center axis; L: straight line; R: rotation direction.

Claims

1. A motor comprising: A rotor having a covered cylindrical rotor core and a hollow cylindrical magnet, wherein the rotor core has a shaft extending along a central axis, and the magnet is disposed on an inner peripheral side of the rotor core; a detection element for detecting the magnetic flux density of the magnet; and a signal output unit that outputs a signal related to the rotation speed of the rotor according to the magnetic flux density, The first pole and the second pole of the magnet are alternately arranged along the circumferential direction, and the magnet includes a first magnetization boundary portion obtained by arranging the first pole and the second pole in a direction opposite to the rotation direction, and a second magnetization boundary portion obtained by arranging the second pole and the first pole in a direction opposite to the rotation direction. When viewed from above in the direction along the central axis, the detection element and the first magnetization boundary portion are located on a straight line passing through the central axis of the magnet and the central axis, the central axis of the magnet passing through the center of the magnet, The signal output unit outputs the signal according to a timing at which the first magnetization boundary portion passes through one of the detection elements.

2. The motor according to claim 1, wherein: The motor further includes a substrate, which is arranged opposite to the rotor. The detection element is provided on a surface of the substrate facing the rotor.

3. The motor according to claim 2, wherein: The signal output unit is disposed on the substrate.

4. The motor according to any one of claims 1 to 3, wherein: The magnet is adhered to the rotor core by an adhesive.

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