Motor device

Abstract

To reduce a peak value of an angle error by suppressing influence of a current magnetic field formed by a conductor on a rotation angle sensor.SOLUTION: A motor device (1) includes: a stator; a rotor; a motor rotation shaft; a magnet; a rotor rotation angle detection unit; and a first lead wire (51), a second lead wire (52), and a third lead wire (53) connected to respective coils of a plurality of phases. The first lead wire (51), the second lead wire (52), and the third lead wire (53) are arranged such that a cross-sectional shape in a plane perpendicular to an axial direction of the motor rotation shaft makes substantially an equilateral triangle.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a motor device. [Background technology]

[0002] Motors such as brushless motors that control the current to the coil according to the rotation angle of the rotor are equipped with a rotor rotation angle sensor. The rotor rotation angle sensor detects the rotation angle from the magnetic field generated by the magnet attached to the motor shaft, but when a current flows through the conductor that carries the current to the coil, a magnetic field is generated, and the accuracy of the rotation angle detection decreases due to the effect of this magnetic field.

[0003] Therefore, in conventional technology, the first, second, and third conductors that supply current to the U-phase, V-phase, and W-phase coils are positioned so that they abut against the contact points of tangents on an imaginary circle centered on the detection unit of the rotation angle sensor, thereby attempting to cancel the current magnetic field formed by each conductor. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2012-39737 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in reality, there is a distance between the conductors, and the distance between the first conductor and the third conductor is longer than the distance between the first conductor and the second conductor, resulting in a problem that the peak value of the angle error becomes high.

[0006] Therefore, an object of the present disclosure is to suppress the influence of the current magnetic field generated by the conductor on the rotation angle sensor and reduce the peak value of the angle error. [Means for solving the problem]

[0007] In order to solve the above problems, a motor device according to one aspect of the present disclosure is a motor device having a motor main body including a stator having coils of multiple phases, a rotor rotatable relative to the stator, and a motor shaft that is coaxial with the rotor and rotates with the rotor, the motor device including a magnet that is provided at one end of the motor shaft and rotates with the rotor and the motor shaft, a rotor rotation angle detection unit that is provided in the axial direction of the motor shaft so as to face the magnet and detects the magnetism of the magnet, and a first conductor, a second conductor, and a third conductor that are connected to each of the coils of multiple phases, extend in the axial direction of the motor shaft, and supply power to the coils of multiple phases, respectively. The first conductor, the second conductor, and the third conductor are arranged such that the cross-sectional shapes of the first conductor, the second conductor, and the third conductor in a plane perpendicular to the axial direction of the motor shaft form a substantially equilateral triangle. Effect of the Invention

[0008] According to one aspect of the present disclosure, the influence of the current magnetic field generated by the conductor on the rotation angle sensor can be suppressed, and the peak value of the angle error can be reduced. [Brief description of the drawings]

[0009] [Figure 1] 1 is a vertical cross-sectional view showing an overall configuration of a motor device according to a first embodiment of the present disclosure. [Diagram 2] 2 is a cross-sectional view taken along line II-II in FIG. 1, illustrating the arrangement of each conductor of the motor device according to the first embodiment. [Diagram 3] 4 is a diagram showing how a magnetic field generated by a magnet provided on a motor rotating shaft of the motor device according to the first embodiment is detected by a magnetic sensor. FIG. [Figure 4] 5A to 5C are diagrams for explaining the influence of a magnetic field generated by a current flowing through a conductor of the motor device according to the first embodiment on a magnetic sensor. [Diagram 5] 10 is a cross-sectional view showing the arrangement of each conductor of a motor device according to a second embodiment. FIG. [Figure 6]11 is a cross-sectional view showing the arrangement of each conductor of a motor device according to a third embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] [Embodiment 1] A motor device 1 according to a first embodiment of the present disclosure will be described below with reference to FIGS. [Motor device configuration] Fig. 1 is a vertical cross-sectional view showing the overall configuration of a motor device. As shown in Fig. 1, the motor device 1 includes a motor body 10, a control unit 20, a magnet 30, a rotation angle sensor 40, and a conductor group 5. For ease of explanation, the up-down direction and the left-right direction of the motor device 1 are defined below as shown by the arrows in Fig. 1.

[0011] The motor device 1 is used, for example, as a drive source for discharging brake fluid in an on-vehicle brake device or as a drive source for an electro-mechanical brake device (EMB: Electro-Mechanical Brake). The motor device 1 may also be a drive source for an actuator other than the on-vehicle brake device. The motor device 1 is, for example, a brushless DC motor. The motor device 1 is not limited to a brushless DC motor and may be an AC motor or the like.

[0012] The motor body 10 includes a stator 11, a rotor 12, and a motor rotating shaft 13. The stator 11, the rotor 12, and the motor rotating shaft 13 are housed in a motor case (not shown).

[0013] Although not shown, the stator 11 has a stator core and three-phase coils having U-phase, V-phase, and W-phase. The stator 11 is fixed to a motor case and disposed radially outside the rotor 12. The stator core is made of, for example, an electromagnetic steel plate and has three salient poles. The three-phase coils are wound around each of the salient poles of the stator core.

[0014] The rotor 12 is configured to be rotatable relative to the stator 11. The rotation of the rotor 12 is controlled by a control unit 20. The rotor 12 has a rotor core and a permanent magnet, not shown. The rotor core is made of, for example, an electromagnetic steel plate. The permanent magnet is provided on the radial outside of the rotor core. The permanent magnet has north and south poles alternately provided in the circumferential direction of the rotor core. The number of magnetic poles is, for example, two or four. The number of poles is not limited to two or four, and may be ten.

[0015] The motor shaft 13 is attached to a motor case in a state in which it is rotatably supported by a bearing (not shown). The motor shaft 13 is disposed coaxially with the rotor 12 and rotates together with the rotor 12. The motor shaft 13 is an output shaft for the power generated by the motor device 1.

[0016] The board 200 is provided with a control unit 20. The control unit 20 has a CPU, a memory, and the like. The CPU controls the driving of the motor main body 10 by reading and executing a program stored in the memory. Note that the board 200 is not limited to a motor control board, and may be a sensor board on which the rotation angle sensor 40 is attached.

[0017] A detection signal from the rotation angle sensor 40 is input to the control unit 20. Based on the detection result of the rotation angle sensor 40, the control unit 20 controls the AC current flowing through the coils of each phase via an inverter (not shown), thereby controlling the rotation of the rotor 12 of the motor device 1.

[0018] The magnet 30 is disposed at the lower end of the motor rotating shaft 13 so as to face the rotation angle sensor 40. The magnet 30 rotates together with the rotor 12 and the motor rotating shaft 13. The magnet 30 has two poles, an N pole and an S pole.

[0019] The rotation angle sensor 40 is an example of a rotor rotation angle detection unit. The rotation angle sensor 40 is provided at a position along the axial direction of the motor rotating shaft 13 so as to face the magnet 30. The rotation angle sensor 40 is disposed on the upper surface of the substrate 200.

[0020] For example, a TMR (Tunnel Magnetoresistance Effect) sensor can be used as the rotation angle sensor 40. The rotation angle sensor 40 detects the rotation angle of the rotor 12 based on detecting the magnetism of the magnet 30, specifically, the change in the magnetic field that accompanies the rotation of the magnet 30.

[0021] The magnet 30 and the rotation angle sensor 40 are disposed between the motor body 10 and the control unit 20. A conductor group 5 is also disposed between the motor body 10 and the control unit 20. The conductor group 5 has a first conductor 51, a second conductor 52, and a third conductor 53. The first conductor 51, the second conductor 52, and the third conductor 53 extend in the axial direction of the motor rotating shaft 13, i.e., in the vertical direction in FIG. 1, and supply power to the three-phase coils, respectively.

[0022] [Layout of each conductor] Next, the arrangement of the conductors 51, 52, and 53 will be described with reference to Fig. 2. Fig. 2 is a cross-sectional view taken along line II-II, showing the arrangement of the conductors of the motor device. For ease of explanation, the front-rear direction and the left-right direction of the motor device 1 are defined as indicated by the arrows in Fig. 2.

[0023] 2, when the cross section taken along line II-II in FIG. 1 is viewed from above, the first conductor 51, the second conductor 52, and the third conductor 53 are arranged so that they are located at the vertices of a substantially inverted equilateral triangle and are in contact with each other. In other words, the first conductor 51, the second conductor 52, and the third conductor 53 are arranged so that their cross-sectional shapes in a plane perpendicular to the axial direction of the motor rotating shaft 13 form a substantially inverted equilateral triangle.

[0024] Here, "approximately" is not limited to a configuration that is strictly an inverted equilateral triangle, but includes an error of a few percent due to manufacturing variance, etc., as well as an error or deformation to the extent that the effect described below is obtained by the arrangement of each conductor.

[0025] In the first embodiment, the first conducting wire 51 is disposed at a position where the distance from the detection unit O of the rotation angle sensor 40 is the shortest among all the conducting wires. Moreover, the second conducting wire 52 and the third conducting wire 53 are disposed at equal distances from the detection unit O of the rotation angle sensor 40.

[0026] The above-mentioned "inverted equilateral triangle" refers to an equilateral triangle in which the apex where the first conducting wire 51 is located is located on the left side of Fig. 2, and the base connecting the apex where the second conducting wire 52 is located and the apex where the third conducting wire 53 is located is located on the right side of Fig. 2. Also, the "equilateral triangle" refers to an arrangement in which the first conducting wire 51, the second conducting wire 52, and the third conducting wire 53 are equally spaced from one another. Note that Fig. 2 shows an imaginary circle that has the detection unit O of the rotation angle sensor 40 as its center point and passes through the second conducting wire 52 and the third conducting wire 53.

[0027] One end of the first conductor 51 is connected to one end of the U-phase coil of the stator 11, as shown in Fig. 1. The other end of the first conductor 51 is connected to the control unit 20. A current flows through the first conductor 51 from the back of the paper in Fig. 2 to the front of the paper. A current to be supplied to the U-phase coil flows through the first conductor 51.

[0028] One end of the second conductor 52 is connected to one end of the V-phase coil of the stator 11. The other end of the second conductor 52 is connected to the control unit 20. A current flows through the second conductor 52 from the back of the page to the front of the page in Fig. 2. A current supplied to the V-phase coil flows through the second conductor 52.

[0029] One end of the third conductor 53 is connected to one end of the W-phase coil of the stator 11. The other end of the third conductor 53 is connected to the control unit 20. A current flows through the third conductor 53 from the front of the page to the back of the page in Fig. 2. A current supplied to the W-phase coil flows through the third conductor 53.

[0030] [Effect of current flowing through conductor on rotation angle sensor] Next, the effect of the magnetic field generated by the current flowing through each of the conductors 51, 52, and 53 on the detection accuracy of the rotation angle sensor 40 will be described with reference to Fig. 3 and Fig. 4. First, Fig. 3(a) is a vertical cross-sectional view showing the positional relationship between the magnet provided on the motor shaft of the motor device and the rotation angle sensor. Fig. 3(b) is a view of the direction of the magnetic field of the magnet in the rotation angle sensor as viewed from the motor main body side.

[0031] As shown in (a) of FIG. 3, when the north pole of magnet 30 is located on the left side and the south pole is located on the right side, the direction of magnetic field Bm detected by rotation angle sensor 40 is to the right, as shown in (b) of FIG. 3.

[0032] Next, Fig. 4(a) is a vertical cross-sectional view of a motor device when a third conductor is provided between the motor body and the control unit and a current flows through the third conductor, and Fig. 4(b) is a diagram showing the direction of the magnetic field obtained by superposing the magnetic field of the magnet in the rotation angle sensor and the magnetic field created by the current flowing through the third conductor, as viewed from the motor body.

[0033] As shown in FIG. 4A, for example, a current i is supplied from the W-phase coil of the stator 11 of the motor body 10 to the control unit 20 via the third conductor 53. 3 When a current flows through the third conductor 53, a clockwise current magnetic field is generated around the third conductor 53 according to the right-hand rule.

[0034] Here, if the distance between the third conducting wire 53 and the detection part O of the rotation angle sensor 40 is d and the magnetic permeability of air is μ, the current i flowing through the third conducting wire 53 is 3 The magnitude of the magnetic field Bd generated in the detection portion O of the rotation angle sensor 40 is calculated by the following formula (1). Bd=μ 0 i 3 / 2πd (1)

[0035] The current i flowing through the third conductor 53 3 The direction of the magnetic field Bd generated by the magnet 30 in the rotation angle sensor 40 is backward as shown in FIG. 4B. The direction of the magnetic field Bm generated by the magnet 30 in the rotation angle sensor 40 is rightward. Therefore, the magnetic field Bm of the magnet 30 and the current i3 The orientation of the magnetic field Bm+Bd, which is a magnetic field Bm created by the rotor 12 and the magnetic field Bd created by the rotor 12, as viewed by the rotation angle sensor 40 is shifted backward by θerr as shown in Fig. 4 from the right direction. In other words, a rotation angle error of θerr occurs in the rotation angle of the rotor 12 detected by the rotation angle sensor 40. Strictly speaking, the orientation of the magnetic field Bd as viewed by the rotation angle sensor 40 is shifted slightly to the right from the backward direction, but for convenience of explanation, it is shown as the backward direction in Fig. 4(b).

[0036] In this way, only the third conductor 53 is supplied with the current i 3 When the current i flows through the first conductor 51 and the second conductor 52, a rotation angle error θerr occurs in the rotation angle of the rotor 12 detected by the rotation angle sensor 40. 3 and the reverse current i 1 ,i 2 By passing the current, the effect of the current magnetic field on the rotation angle sensor 40 is reduced.

[0037] 2 to the first conductor 51 and the second conductor 52, a current magnetic field in the counterclockwise direction is formed around the first conductor 51 and the second conductor 52. As a result, the direction of the magnetic field Bd in the rotation angle sensor 40 is the forward direction.

[0038] In this way, the current i flowing through the third conductor 53 3 The current magnetic field created by the current i flowing through the first conductor 51 is 1 and the current i flowing through the second conductor 52 2 This is cancelled out by the magnetic field created by the current.

[0039] In the motor device 1 of the above-mentioned embodiment 1, the first conductor 51, the second conductor 52, and the third conductor 53 are arranged so as to be in contact with each other and at equal intervals from each other, thereby shortening the distance between each conductor as much as possible. This makes it possible to further increase the amount of cancellation of the above-mentioned current magnetic field at the center of the rotation angle sensor 40, and to further reduce the error in the rotation angle of the rotor 12 detected by the rotation angle sensor 40.

[0040] [Embodiment 2] Next, a motor device 1A according to a second embodiment will be described with reference to Fig. 5. For ease of explanation, members having the same functions as those described in the first embodiment will be denoted by the same reference numerals, and the description thereof will not be repeated.

[0041] [Layout of each conductor] Fig. 5 is a cross-sectional view showing the arrangement of each conductor in the motor device 1A. As shown in Fig. 5, the arrangement of each conductor in the motor device 1A is different from that of the motor device 1 of the first embodiment. In the motor device 1A, the first conductor 51, the second conductor 52, and the third conductor 53 are arranged so that their cross-sectional shapes in a plane perpendicular to the axial direction of the motor rotating shaft 13 form a substantially equilateral triangle, and are arranged so as to abut against each other. Note that Fig. 5 shows an imaginary circle that has the detection unit O of the rotation angle sensor 40 as its center point and passes through the second conductor 52.

[0042] In the second embodiment, the second conducting wire 52 is disposed at a position where the distance from the detection unit O of the rotation angle sensor 40 is the longest among the conducting wires. The first conducting wire 51 and the third conducting wire 53 are disposed at equal distances from the detection unit O of the rotation angle sensor 40. That is, as shown in Fig. 5, the first conducting wire 51, the second conducting wire 52, and the third conducting wire 53 are disposed so as to be located at the vertices of an equilateral triangle.

[0043] In the motor device 1A of the above-described embodiment 2, similarly to the motor device 1 of the embodiment 1, the current i 1 ,i 2 ,i 3 This can further increase the amount of cancellation of the current magnetic field created.

[0044] [Embodiment 3] Next, a motor device 1B according to a third embodiment of the present disclosure will be described with reference to Fig. 6. For ease of explanation, members having the same functions as those described in the first embodiment are denoted by the same reference numerals, and the explanation thereof will not be repeated.

[0045] Fig. 6 is a cross-sectional view showing the arrangement of conductors of each phase in the motor device 1B. As shown in Fig. 6, the motor device 1B of the third embodiment is different from the motor device 1 of the first embodiment in that the motor device 1B is a two-system motor device having two conductor groups 5 and 6.

[0046] The conductor group 5 is composed of a first conductor 51, a second conductor 52, and a third conductor 53. As in the first embodiment, the first conductor 51, the second conductor 52, and the third conductor 53 are arranged so that their cross-sectional shapes in a plane perpendicular to the axial direction of the motor rotating shaft 13 form approximately inverted equilateral triangles, and are arranged so as to abut against each other.

[0047] The conductor group 6 has a first conductor 61, a second conductor 62, and a third conductor 63. The first conductor 61, the second conductor 62, and the third conductor 63 are arranged at positions that are point-symmetric with respect to the first conductor 51, the second conductor 52, and the third conductor 53, with the detection unit O of the rotation angle sensor 40 as a reference. Note that Fig. 6 shows an imaginary circle that has the detection unit O of the rotation angle sensor 40 as its center point, passes through the second conductor 52 and the third conductor 53, and the second conductor 62 and the third conductor 63.

[0048] The first conductor 61, the second conductor 62, and the third conductor 63 are arranged so that their cross-sectional shapes in a plane perpendicular to the axial direction of the motor rotating shaft 13 form a substantially equilateral triangle and are arranged so as to abut against each other. Specifically, in the motor device 1B, the first conductor 61 is arranged at a position where the distance from the detection unit O of the rotation angle sensor 40 is the shortest among the conductors. The second conductor 62 and the third conductor 63 are arranged so as to be equidistant from the detection unit O of the rotation angle sensor 40.

[0049] One end of the first conductor 61 is connected to one end of the U-phase coil of the stator 11. The other end of the first conductor 61 is connected to the control unit 20. A current flows through the first conductor 51 from the back of the page to the front of the page in Fig. 6. A current to be supplied to the U-phase coil flows through the first conductor 61.

[0050] One end of the second conductor 62 is connected to one end of the V-phase coil of the stator 11. The other end of the second conductor 62 is connected to the control unit 20. A current flows through the second conductor 62 from the back of the page to the front of the page in Fig. 6. A current supplied to the V-phase coil flows through the second conductor 62.

[0051] One end of the third conductor 63 is connected to one end of the W-phase coil of the stator 11. The other end of the third conductor 63 is connected to the control unit 20. A current flows through the third conductor 63 from the front of the page to the back of the page in Fig. 6. A current supplied to the W-phase coil flows through the third conductor 63.

[0052] The arrangement is not limited to that of the third embodiment, and the second conductor 52 may be arranged at a position where the distance from the detection unit O of the rotation angle sensor 40 is the longest among the conductors, and the first conductor 51 and the third conductor 53 may be arranged at equal distances from the detection unit O of the rotation angle sensor 40. In this case, it is sufficient that the first conductor 61, the second conductor 62, and the third conductor 63 are arranged at positions that are point-symmetric with respect to the first conductor 51, the second conductor 52, and the third conductor 53 with respect to the detection unit O of the rotation angle sensor 40.

[0053] The motor device 1B of the embodiment 3 described above can also provide the same effects as the motor device 1 of the embodiment 1. In particular, the first conductor 51, the second conductor 52, and the third conductor 53, and the first conductor 61, the second conductor 62, and the third conductor 63 are arranged point-symmetrically with respect to the detection unit O of the rotation angle sensor 40 as the center point, so that the current magnetic field generated by the current flowing through the conductors 51, 52, 53, 61, 62, and 63 can be effectively canceled out in the detection unit O of the rotation angle sensor 40.

[0054] Other embodiments In the motor device 1 of the above-described embodiment 1, the first conductor 51, the second conductor 52, and the third conductor 53 are arranged so as to abut against each other, but this is not limited thereto. The first conductor 51, the second conductor 52, and the third conductor 53 only need to be arranged at equal intervals from each other and do not need to abut against each other.

[0055] In addition, in the above-described first and second embodiments, a TMR sensor is used as the rotation angle sensor 40. However, this is not limiting, and other sensors such as a GMR (Giant Magneto Resistive) sensor, an AMR (Anisotropic Magneto Resistive) sensor, and a Hall IC may also be used.

[0056] 〔summary〕 A motor device according to one aspect of the present disclosure is a motor device having a motor main body including a stator having coils of multiple phases, a rotor rotatable relative to the stator, and a motor shaft coaxially disposed with the rotor and rotating with the rotor, the motor device including a magnet disposed at one end of the motor shaft and rotating with the rotor and a rotor rotation angle detector disposed in the axial direction of the motor shaft so as to face the magnet and detecting the magnetism of the magnet, and a first conductor, a second conductor, and a third conductor connected to each of the coils of multiple phases, extending in the axial direction of the motor shaft, and supplying electric power to the coils of multiple phases, respectively. The first conductor, the second conductor, and the third conductor are arranged such that the cross-sectional shapes of the first conductor, the second conductor, and the third conductor in a plane perpendicular to the axial direction of the motor shaft form a substantially equilateral triangle. According to the present disclosure, the first, second, and third conductors connected to the U, V, and W phases, respectively, are arranged at equal intervals, shortening the distance between the three conductors, thereby increasing the amount of mutual cancellation of the current magnetic fields formed by the currents flowing through the conductors at the center of the motor shaft where the rotor rotation angle sensor is located. This reduces the effect of the current magnetic field on the rotor rotation angle sensor, thereby suppressing the peak value of the angle error.

[0057] In a motor device according to one embodiment of the present disclosure, the first conductor, the second conductor, and the third conductor are arranged so that one of the first conductor, the second conductor, and the third conductor is at the shortest distance from the rotor rotation angle detection unit, and the others are at equal distances from the rotor rotation angle detection unit. According to the present disclosure, by arranging three conductors in an inverted equilateral triangle, the number of conductors close to the rotor rotation angle sensor is reduced to one, thereby reducing the influence of the current magnetic field due to the close distance to the rotation angle sensor and suppressing angle errors.

[0058] In the motor device according to one aspect of the present disclosure, the first conductor, the second conductor, and the third conductor are in contact with each other. According to the present disclosure, by making the distance between each conductor as short as possible, it is possible to further increase the amount of cancellation of the current magnetic field created by the current flowing through each conductor at the center of the rotation angle sensor.

[0059] [Additional Notes] The present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present disclosure. [Explanation of symbols]

[0060] 1, 1A, 1B Motor Unit 10 Motor body 11 Stator 12 Rotor 13 Motor shaft 20 Control section 30 Magnet 40 Rotational angle sensor 51, 61 First conductor 52, 62 Second conductor 53, 63 Third Conductor

Claims

1. A motor device having a motor main body including a stator having a multi-phase coil, a rotor rotatable relative to the stator, and a motor shaft that is coaxial with the rotor and rotates together with the rotor, a magnet provided at one end of the motor shaft and rotating together with the rotor and the motor shaft; a rotor rotation angle detection unit that is provided in an axial direction of the motor shaft so as to face the magnet and detects magnetism of the magnet; a first conductor, a second conductor, and a third conductor connected to each of the coils of the multiple phases, extending in an axial direction of the motor rotation shaft, and supplying electric power to each of the coils of the multiple phases; Equipped with A motor device characterized in that the first conductor, the second conductor, and the third conductor are arranged so that their cross-sectional shapes in a plane perpendicular to the axial direction of the motor rotating shaft form approximately equilateral triangles.

2. 2. The motor device according to claim 1, wherein the first conductor, the second conductor, and the third conductor are arranged so that one of the first conductor, the second conductor, and the third conductor is located at the shortest distance from the rotor rotation angle detection unit, and the rest of the first conductor, the second conductor, and the third conductor are located at equal distances from the rotor rotation angle detection unit.

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