JP2024097105A - Rotary electric machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce an influence by a rotor on a detection result of a sensor that utilizes eddy current, in a rotary electric machine.

SOLUTION: A rotary electric machine disclosed herein comprises: a rotor; a non-rotating part; a sensor rotor that rotates integrally with the rotor; and a sensing part having a coil axially opposed to the sensor rotor, and generating an electric signal according to a value of a parameter related to rotation of the rotor by generating eddy current in the sensor rotor due to magnetic flux generated by passing current through the coil. The sensor rotor has a portion whose outer diameter or the like at a circumferential position axially opposed to the sensing part periodically changes every time a rotation angle of the rotor changes by a predetermined angle. The rotor has a sensor adjacent portion that comes adjacent from a side opposite to the sensing part with respect to the sensor rotor. A magnitude of the eddy current generated by the magnetic flux in the sensor adjacent portion periodically changes every time a rotation angle of the rotor changes by a predetermined angle or an integral multiple thereof.

SELECTED DRAWING: Figure 9

COPYRIGHT: (C)2024,JPO&INPIT

Description

This disclosure relates to rotating electrical machines.

A rotation detector is known that uses eddy currents generated in a sensor rotor by a magnetic field generated by a coil in the sensing section to generate an electrical signal in the sensing section that corresponds to the value of a parameter related to the rotation of the rotor (e.g., the rotation angle).

JP 2012-231648 A

In rotating electrical machines, various components are arranged in a limited space inside the case, and so there are often metal parts other than the sensor rotor located around the sensing part. Therefore, the detection results of a sensor that uses eddy currents are easily affected by such surrounding metal parts. In this regard, the rotor, one of the surrounding metal parts, is likely to affect the detection results of the sensor because the part adjacent to the sensor rotor in the axial direction extends radially outward.

Therefore, in one aspect, the present disclosure aims to reduce the influence of the rotor on the detection results of a sensor that uses eddy currents in a rotating electric machine.

In one aspect, a rotor;
A non-rotating portion that rotatably supports the rotor;
a sensor rotor that rotates integrally with the rotor;
a sensing unit having a coil axially opposed to the sensor rotor, and configured to generate an electric signal corresponding to a parameter value relating to the rotation of the rotor by generating an eddy current in the sensor rotor due to a magnetic flux generated by energizing the coil,
the sensor rotor has a portion in which an outer diameter or an axial thickness at a circumferential position axially opposed to the sensing portion changes periodically every time a rotation angle of the rotor changes by a predetermined angle,
the rotor has a sensor adjacent portion adjacent to the sensor rotor in the axial direction from a side opposite to the sensing portion,
A rotating electric machine is provided in which the magnitude of eddy currents generated by the magnetic flux in the portion adjacent to the sensor changes periodically each time the rotation angle of the rotor changes by the specified angle or by an integer multiple of the specified angle.

In one aspect, the present disclosure makes it possible to reduce the influence of the rotor on the detection results of a sensor that uses eddy currents in a rotating electric machine.

1 is a cross-sectional view showing a schematic cross-sectional structure of a motor according to an embodiment of the present invention. FIG. 1B is an enlarged view of part Q1 of FIG. 1A. 2 is a perspective view showing a sensor rotor and a sensing portion in the rotation sensor according to the present embodiment. FIG. 3 is a diagram showing the relationship between a sensing portion and a sensor rotor of the rotation sensor according to the present embodiment. FIG. 3 is a diagram showing a portion of the sensor rotor according to the embodiment that faces a sensing portion in the axial direction, as viewed in the axial direction. FIG. 5A to 5C are schematic diagrams illustrating waveforms of sensor outputs generated by a sensing unit according to the present embodiment. FIG. 2 is an explanatory diagram conceptually illustrating the configuration features of the present embodiment, and is a perspective view of the sensor rotor and part of its periphery (part of the rotor) as viewed from the X1 side. FIG. 7 is a perspective view of the sensor rotor removed from FIG. 6 . FIG. 7 is a plan view showing a state in which the sensor rotor is removed from FIG. 6 . FIG. 7 is a plan view of FIG. 6 as viewed in the axial direction, showing only the upper half of the rotating shaft. 5A and 5B are diagrams illustrating the effect of a portion of the rotor adjacent to the sensor on a sensor output. FIG. 13 is a diagram showing a waveform of a sensor output generated by a sensing portion, the waveform of the sensor output being influenced by a sensor adjacent portion. FIG. 13 is an axial plan view that illustrates a sensor adjacent portion and a sensor rotor according to a comparative example. FIG. 13 is a diagram showing a waveform of a sensor output generated by a sensing unit, the waveform being influenced by a sensor adjacent unit according to a comparative example. FIG. 11 is an axial plan view that illustrates a sensor adjacent portion and a sensor rotor in a motor according to a second embodiment. FIG. 11 is an axial plan view that illustrates a sensor adjacent portion and a sensor rotor in a motor according to a third embodiment. FIG. 11 is a perspective view of a sensor rotor according to a third embodiment. FIG. 13 is a diagram showing a waveform of a sensor output generated by a sensing unit in Example 3, the waveform of the sensor output being influenced by a sensor adjacent unit.

Each embodiment will be described in detail below with reference to the attached drawings. Note that the dimensional ratios in the drawings are merely examples and are not limiting. Also, shapes in the drawings may be partially exaggerated for the sake of explanation.

[Example 1]
Fig. 1A is a cross-sectional view showing a schematic cross-sectional structure of a motor 1 according to the present embodiment, and Fig. 1B is an enlarged view of a portion Q1 in Fig. 1A.

Figure 1A shows the rotating shaft 12 of the motor 1. In the following description, the axial direction refers to the direction in which the rotating shaft (center of rotation) 12 of the motor 1 extends, and the radial direction refers to the radial direction centered on the rotating shaft 12. Therefore, the radially outer side refers to the side away from the rotating shaft 12, and the radially inner side refers to the side toward the rotating shaft 12. Additionally, the circumferential direction corresponds to the direction of rotation around the rotating shaft 12.

In addition, in FIG. 1A, the X1 side and the X2 side are defined along the X direction parallel to the direction of the rotation axis 12 (i.e., the axial direction). In the following description, the terms X1 side and X2 side may be used to indicate the relative positional relationship.

Motor 1 may be a motor for driving a vehicle, such as that used in a hybrid vehicle or an electric vehicle. However, motor 1 may also be used for any other purpose.

The motor 1 is an inner rotor type, and the stator 21 is arranged to surround the radial outside of the rotor 30. The radial outside of the stator 21 is fixed to the motor housing 10. The stator 21 has a stator core 211 made of, for example, a circular ring-shaped laminated steel plate of a magnetic material, and a plurality of slots (not shown) are formed on the radial inside of the stator core 211, around which the coils 22 are wound.

The rotor 30 is disposed radially inside the stator 21. The rotor 30 includes a rotor core 32 and a rotor shaft 34. The rotor core 32 is fixed to the radially outer surface of the rotor shaft 34 and rotates together with the rotor shaft 34. The rotor core 32 may be fixed to the rotor shaft 34 by shrink fitting or the like. The rotor shaft 34 is rotatably supported in the motor housing 10 via bearings 14a and 14b. The rotor shaft 34 defines the rotating shaft 12 of the motor 1.

The rotor core 32 is made of, for example, laminated steel plates of a magnetic material in a circular ring shape. Permanent magnets 321 are embedded in the magnet holes 324 of the rotor core 32. Alternatively, permanent magnets such as the permanent magnet 321 may be embedded in the outer circumferential surface of the rotor core 32. The arrangement of the permanent magnets 321 is arbitrary.

End plates 35A, 35B are attached to both axial sides of rotor core 32. End plates 35A, 35B cover the axial end faces of rotor core 32. End plates 35A, 35B have a function to prevent permanent magnets 321 from coming off rotor core 32, and may also have a function to adjust imbalance of rotor 30 (a function to eliminate imbalance by cutting, etc.).

The end plates 35A, 35B are made of a non-magnetic material. The end plates 35A, 35B are preferably made of aluminum. In this case, cutting is easy, and the end plates 35A, 35B can effectively adjust the imbalance of the rotor 30. However, in a modified example, the end plates 35A, 35B may be made of stainless steel, etc.

As shown in FIG. 1A, the rotor shaft 34 has a hollow portion 34A. The hollow portion 34A extends over the entire axial length of the rotor shaft 34. The hollow portion 34A may be open in the axial direction on both sides. The hollow portion 34A may function as an oil passage 801 through which cooling oil passes.

In this embodiment, the magnetic pole configuration of the rotor core 32 is arbitrary. For example, the number of magnetic poles may be eight or other than eight, and instead of or in addition to the permanent magnet 321, the pair of permanent magnets forming each magnetic pole may be arranged such that the circumferential distance increases toward the radially outward side. The rotor core 32 may also be formed with a flux barrier, oil passages, etc.

In this embodiment, the rotor shaft 34 has a hollow portion 34A, but may be solid. The rotor shaft 34 may be formed by joining two or more parts. The motor 1 may be cooled with cooling water (e.g., lifelong coolant) instead of or in addition to oil. In this embodiment, the motor 1 is an inner rotor type, but may be an outer rotor type.

In this embodiment, the motor 1 has a rotation sensor 80 that detects the value of a parameter related to the rotation of the rotor 30. The parameter related to the rotation of the rotor 30 is arbitrary, and may be, for example, the presence or absence of rotation of the rotor 30, the rotation angle of the rotor 30 from a predetermined reference angle, the rotation speed, the magnetic pole position, etc. In the following, as an example, the rotation sensor 80 is assumed to detect the rotation angle of the rotor 30.

The rotation sensor 80 is provided at one end of the rotor shaft 34. In this embodiment, the rotation sensor 80 is provided at the X1 end of the rotor shaft 34 as shown in FIG. 1A, but may be provided at the X2 end.

Figure 2 is a perspective view showing the sensor rotor 81 and sensing unit 82 of the rotation sensor 80 as viewed from the X1 side. Note that the sensor support unit 84 is not shown in Figure 2 (as is Figure 3 below).

The rotation sensor 80 comprises a sensor rotor 81, a sensing part 82, and a sensor support part 84.

The sensor rotor 81 is formed of a conductor and rotates integrally with the rotor 30. The sensor rotor 81 is in the form of an annular ring having a circular central hole 811 centered on the rotation axis 12. The sensor rotor 81 may be attached so as to rotate together with the rotor shaft 34 by having the rotor shaft 34 pass through the central hole 811. For example, the sensor rotor 81 may have a radial recess or protrusion formed on the rotor shaft 34, and a radial protrusion or recess formed on the inner peripheral edge of the central hole 811 of the sensor rotor 81 that fits into the radial recess or protrusion of the rotor shaft 34.

The sensor rotor 81 has an outer diameter that changes periodically. As a result, the outer diameter of the sensor rotor 81 at a circumferential position axially opposite the sensing portion 82 changes periodically every time the rotation angle of the rotor 30 changes by a predetermined angle. The predetermined angle may be appropriately determined during design depending on the number of magnetic poles, etc. In this embodiment, the sensor rotor 81 has eight alternating radial convex and concave portions per revolution. In this case, the outer diameter of the sensor rotor 81 at a circumferential position axially opposite the sensing portion 82 changes periodically every time the rotation angle of the rotor 30 changes by 45 degrees.

In a modified example, the sensor rotor 81 may have a periodically changing thickness (axial thickness) instead of or in addition to the periodically changing outer diameter. In this case, the thickness of the sensor rotor 81 at a circumferential position axially opposite the sensing portion 82 changes periodically every time the rotation angle of the rotor 30 changes by a predetermined angle.

The sensing unit 82 is in the form of a substrate 820, and is arranged so as to face the sensor rotor 81 in the axial direction and be close to it. As shown in FIG. 2, the substrate 820 may be arc-shaped when viewed in the axial direction, and may extend only over a portion of the entire circumference. The substrate 820 may not only be arc-shaped, but may also extend over the entire circumference. The sensing unit 82 is supported on a non-rotating portion of the motor 1 (the motor housing 10 in this embodiment) by a sensor support portion 84 (see FIG. 1B).

The sensing unit 82 detects the rotation angle of the rotor 30 using eddy currents. Figures 3 to 5 are explanatory diagrams of the detection principle by the sensing unit 82. Figure 3 is a diagram showing the relationship between the sensing unit 82 of the rotation sensor 80 and the sensor rotor 81, and Figure 4 is a diagram showing the part of the sensor rotor 81 that faces the sensing unit 82 in the axial direction as viewed in the axial direction. Figure 5 is a schematic diagram explaining the waveform of the sensor output (electrical signal) generated by the sensing unit 82. In Figure 5, the horizontal axis represents the rotation angle of the rotor 30, and the vertical axis represents the magnitude of the sensor output, and the time series waveform of the sensor output (electrical signal) generated by the sensing unit 82 is shown. Note that Figure 5 shows a time series waveform for a predetermined angle (45 degrees in this embodiment) in the rotation angle of the rotor 30.

As shown in FIG. 2, the sensing unit 82 may be in the form of a substrate 820 on which a sensor coil 821 and a processing circuit unit 822 are mounted. Note that some or all of the functions of the processing circuit unit 822 may be realized by an external control device (not shown).

The sensor coil 821 may be formed on both surfaces of the substrate 820, for example, as shown in FIG. 3. In a modified example, the sensor coil 821 may be formed on an inner layer of the substrate 820 instead of or in addition to the both surfaces of the substrate 820. The sensor coil 821 may be formed of, for example, a printed conductor. The sensor coil 821 is wound around a central axis O parallel to the X direction.

The processing circuit unit 822 generates an eddy current in the sensor rotor 81 by energizing the sensor coil 821. Specifically, as shown in FIG. 3, when the sensor coil 821 is energized, a magnetic flux B1 penetrating the sensor coil 821 is generated. When the magnetic flux B1 penetrating the sensor coil 821 comes into contact with the surface of the sensor rotor 81 that faces the sensor coil 821 in the axial direction, an eddy current is generated on the surface of the sensor rotor 81. In FIG. 4, the generation mode of the eddy current is shown by an arrow Ie. Note that, although a specific direction of the eddy current is shown in FIG. 4, the direction of the eddy current is determined according to the direction of the current flowing through the sensor coil 821. The eddy current is generated in a direction that generates a magnetic flux that reduces the magnetic flux B1. Therefore, due to the eddy current, a magnetic flux B2 (not shown) that reduces the magnetic flux B1 is generated. The magnitude of the magnetic flux B2 is proportional to the magnitude of the eddy current. The magnitude of the eddy current increases as the surface area of the portion of the sensor rotor 81 axially facing the sensor coil 821 increases. In this embodiment, since the sensor rotor 81 has an outer diameter that changes periodically as described above, the surface area of the portion of the sensor rotor 81 axially facing the sensor coil 821 changes as the rotation angle of the rotor 30 changes. More specifically, the surface area of the portion of the sensor rotor 81 axially facing the sensor coil 821 changes in a sinusoidal manner as the rotation angle of the rotor 30 changes. For this reason, in this embodiment, the time series waveform of the sensor output (electrical signal) generated by the sensing unit 82 draws one period of a sine wave every time the rotation angle of the rotor 30 changes by 45 degrees, as shown in FIG. 5. Therefore, the rotation angle of the rotor 30 can be detected based on such a sensor output (electrical signal).

The sensor support portion 84 is fixed to the non-rotating portion of the motor 1 (the motor housing 10 in this embodiment) (schematically shown in FIGS. 1A and 1B) and supports the sensing portion 82. The sensor support portion 84 may support the sensing portion 82 by any means such as an adhesive, a fastener, or fitting. In this embodiment, as an example, the sensor support portion 84 supports the sensing portion 82 via, for example, a potting resin portion 86 for sealing. In this case, the potting resin portion 86 is joined to the sensing portion 82 and the sensor support portion 84 to integrate the sensing portion 82 and the sensor support portion 84. In this case, the number of parts can be reduced compared to when the sensing portion 82 and the sensor support portion 84 are separate parts. In addition, since the assembly of the sensing portion 82 is realized by assembling the sensor support portion 84 to the motor housing 10, the assembly is easier than when the sensing portion 82 and the sensor support portion 84 are separate parts. The potting resin part 86 may be filled from the opening on the X2 side of the sensor support part 84.

The sensor support portion 84 preferably supports the sensing portion 82 so that the sensing portion 82 is axially close to the sensor rotor 81. In this case, the sensor support portion 84 may realize a positional relationship between the sensor rotor 81 and the sensing portion 82 such that the axial gap between the sensor rotor 81 and the sensing portion 82 corresponds to the minimum clearance required between the movable portion and the fixed portion.

Here, the features of the configuration of this embodiment will be conceptually explained with reference to Figures 6 to 11.

6 to 9 are explanatory diagrams conceptually explaining the features of the configuration of this embodiment, in which FIG. 6 is a perspective view of the sensor rotor 81 and a part of its periphery (part of the rotor 30) viewed from the X1 side, FIG. 7 is a perspective view of FIG. 6 with the sensor rotor 81 removed, and FIG. 8 is a plan view (plan view viewed in the axial direction) of FIG. 6 with the sensor rotor 81 removed. FIG. 9 is a plan view of FIG. 6 viewed in the axial direction, showing only the upper half above the rotating shaft 12. Note that FIGS. 6 to 9 are conceptual diagrams, and the configuration of the rotor 30 in particular is shown very diagrammatically. FIG. 10 is an explanatory diagram of the effect of the sensor adjacent portion 300 of the rotor 30 on the sensor output, and is a diagram that shows the flow of magnetic flux. Note that the flow of magnetic flux shown in FIG. 10 is shown diagrammatically before being affected by the sensor adjacent portion 300 and the sensor rotor 81. FIG. 11 is a diagram showing the waveform of the sensor output (electrical signal) generated by the sensing unit 82 in this embodiment, and the waveform of the sensor output influenced by the sensor adjacent unit 300. In FIG. 11, the horizontal axis represents the rotation angle of the rotor 30, and the vertical axis represents the magnitude of the sensor output, and the time series waveform of the sensor output (electrical signal) generated by the sensing unit 82 is shown typically. Note that FIG. 11 (as well as FIG. 13 and FIG. 17 described later) shows a time series waveform for twice a predetermined angle (45 degrees in this embodiment) of the rotation angle of the rotor 30 (two periods).

The rotor 30 has a sensor adjacent portion 300 that is adjacent to the sensor rotor 81 in the axial direction from the opposite side (X2 side in this embodiment) to the sensing portion 82. The sensor adjacent portion 300 may be realized by any one or more components of the rotor 30 (components that rotate with the rotor shaft 34), and may be, for example, the X1 side end of the rotor shaft 34, the X1 side end of the rotor core 32, the end plate 35A, the washer 39, etc. in the example shown in FIG. 1A. The washer 39 is provided between the flange portion 346 (the portion of the X1 side end of the rotor shaft 34) and the rotor core 32 in the axial direction, and may have the function of reducing stress that may occur in the rotor core 32 due to the axial force applied from the flange portion 346 to the end plate 35A (and the rotor core 32 via the end plate 35A).

The sensor adjacent portion 300 is disposed on the opposite side of the sensor rotor 81 from the sensing portion 82 (X2 side in this embodiment), but since it is disposed near the sensor rotor 81 and extends radially outward from the sensor rotor 81, it may affect the magnetic flux B1 (see magnetic flux B1-1 in FIG. 10) that penetrates the sensor coil 821. In other words, eddy currents may be generated in the sensor adjacent portion 300 due to the magnetic flux B1 that penetrates the sensor coil 821. Similar to the eddy currents in the sensor rotor 81, these eddy currents generate magnetic flux B3 (not shown) in a direction that reduces the magnetic flux B1.

In this regard, in this embodiment, the sensor adjacent portion 300 is configured so that the magnitude of the eddy current generated by the magnetic flux B1 in the sensor adjacent portion 300 changes periodically each time the rotation angle of the rotor 30 changes by a predetermined angle (45 degrees in this embodiment).

6 to 9, the sensor adjacent portion 300 has a first portion 301 having a constant outer diameter and a second portion 302 having an outer diameter significantly larger than that of the first portion 301, which are arranged periodically along the circumferential direction. That is, the sensor adjacent portion 300 has an outer diameter that changes periodically with the same phase and period as the sensor rotor 81. In other words, the sensor rotor 81 has a small diameter portion 810 at a circumferential position corresponding to the first portion 301, and the sensor rotor 81 has a large diameter portion 812 at a circumferential position corresponding to the second portion 302. In this case, the outer diameter of the large diameter portion 812 is significantly smaller than the outer diameter of the second portion 302 (see FIG. 9). Thus, in this embodiment, the outer diameter of the sensor adjacent portion 300 at a circumferential position axially opposite the sensing portion 82 changes periodically every time the rotation angle of the rotor 30 changes by a predetermined angle (45 degrees in this embodiment). In this specification, "the outer diameter of one of the two parts is significantly larger or smaller than the other" refers to a state in which a significant difference (e.g., a difference that exceeds the minimum resolution of the sensor output) occurs in the sensor output between when one part faces the sensor coil 821 in the axial direction and when the other part faces the sensor coil 821 in the axial direction.

The magnitude of the eddy current in the sensor adjacent portion 300 increases as the surface area of the portion of the sensor adjacent portion 300 that directly faces the sensor coil 821 in the axial direction increases, as in the case of the sensor rotor 81 described above. The sensor adjacent portion 300 directly faces the sensor coil 821 in the axial direction refers to a positional relationship in which the magnetic flux B1 can reach the sensor coil 821 without being blocked by the sensor rotor 81. In this embodiment, the sensor adjacent portion 300 has an outer diameter that changes periodically as described above, so that the surface area of the portion of the sensor rotor 81 that directly faces the sensor coil 821 in the axial direction changes when the rotation angle of the rotor 30 changes. More specifically, the surface area of the portion of the sensor adjacent portion 300 that axially faces the sensor coil 821 changes in a manner corresponding to one period of a sine wave, a rectangular wave, a triangular wave, or the like, every time the rotation angle of the rotor 30 changes by 45 degrees.

For this reason, in this embodiment, the eddy currents generated in the sensor adjacent portion 300 due to the magnetic flux B1 change periodically, in a manner that describes one cycle of a sine wave, a square wave, or a triangular wave, every time the rotation angle of the rotor 30 changes by 45 degrees. Therefore, the magnetic flux B3 generated due to the eddy currents generated in such a sensor adjacent portion 300 also changes periodically, in a manner that describes one cycle of a sine wave, a square wave, a triangular wave, or the like, every time the rotation angle of the rotor 30 changes by 45 degrees.

In addition, in this embodiment, the sensor rotor 81 has a portion (small diameter portion 810 and large diameter portion 812) whose outer diameter at a circumferential position axially opposite to the sensing portion 82 changes periodically every time the rotation angle of the rotor 30 changes by 45 degrees. As a result, in this embodiment, the time series waveform of the sensor output (electrical signal) generated by the sensing portion 82 is a waveform having a substantially constant offset caused by the sensor adjacent portion 300 (a portion extending radially outward from the sensor rotor 81 as viewed in the axial direction) with respect to the basic waveform caused by the small diameter portion 810 and the large diameter portion 812 of the sensor rotor 81. Specifically, in this embodiment, the time series waveform of the sensor output (electrical signal) generated by the sensing portion 82 is a waveform 501 that is offset by a constant offset amount (see Δ1 in FIG. 11) corresponding to the magnetic flux B3 with respect to the ideal waveform 500 shown in FIG. 5, as shown in FIG. 11. In this embodiment, as described above, the magnetic flux B3 changes periodically every time the rotation angle of the rotor 30 changes by a predetermined angle (45 degrees in this embodiment), so the offset waveform 501 also changes periodically every time the rotation angle of the rotor 30 changes by 45 degrees (in FIG. 11, it changes periodically in a manner that draws a sine wave). Therefore, the rotation angle of the rotor 30 can be detected with high accuracy based on such a sensor output (electrical signal).

In the examples shown in Figures 6 to 9, the second portion 302 is a radial convex portion relative to the first portion 301, and the first portion 301 is a radial concave portion relative to the second portion 302. In this case, either the first portion 301 or the second portion 302 is an example of a "base portion" in the claims, and the other is an example of a "specific portion" in the claims.

When the sensor adjacent portion 300 includes an end plate 35A, the protrusions and recesses of the sensor adjacent portion 300 may be realized by oil grooves (including oil holes, oil passages, etc., hereinafter the same) or balance adjustment holes (holes for adjusting the imbalance of the rotor 30) that can be formed in the end plate 35A. In addition, in a configuration in which the end plate 35A is not provided, the sensor adjacent portion 300 may include the end portion on the X1 side of the rotor core 32. In this case, the protrusions and recesses may be realized by oil grooves, flux barriers, crimping portions, etc. that can be formed in the end portion on the X1 side of the rotor core 32. In this case, the crimping portion may be a crimping portion for fixing the rotor shaft 34 to the rotor shaft 34. In addition, when the sensor adjacent portion 300 includes the rotor shaft 34 (motor hub), the protrusions and recesses may be realized by oil grooves, welded portions, etc. that can be formed in the rotor shaft 34.

Here, the effect of this embodiment will be described in comparison with the comparative example with reference to Figs. 12 and 13. Fig. 12 is an axial plan view showing the sensor adjacent portion 300' and the sensor rotor 81 according to the comparative example, and shows only the upper half above the rotating shaft 12, as in Fig. 9. Fig. 13 shows the waveform of the sensor output (electrical signal) generated by the sensing portion 82 in the comparative example, and is a diagram showing the waveform of the sensor output influenced by the sensor adjacent portion 300' according to the comparative example. In Fig. 13, the horizontal axis shows the rotation angle of the rotor 30, the vertical axis shows the magnitude of the sensor output, and the time series waveform of the sensor output (electrical signal) generated by the sensing portion 82 is shown diagrammatically.

As shown in FIG. 12, the sensor adjacent portion 300' in the comparative example has a first portion 301' with a constant outer diameter and a second portion 302' with an outer diameter significantly larger than that of the first portion 301', which are arranged irregularly along the circumferential direction. For example, the second portion 302'-1 has a wider circumferential extension range than the second portion 302'-2, and extends continuously over an angle of 45 degrees or more. In such an irregular configuration, as shown in FIG. 13, the time series waveform of the sensor output (electrical signal) generated by the sensing unit 82 becomes irregular. In other words, in the comparative example, the sensor output does not have the regularity of drawing one period of a sine wave every time the rotation angle of the rotor 30 changes by 45 degrees. In the example shown in FIG. 13, in an angle range A1 of one cycle, the center value of the sensor output is offset upward (see arrow R1301) from the ideal median value (e.g., the center value of the amplitude of the ideal waveform 500 shown in FIG. 5) shown by the dotted line 1300 in FIG. 13, whereas in an angle range A2 of the next cycle, the center value of the sensor output is offset downward (see arrow R1302) from the ideal median value, and the offset amount is not constant. In such a case, the rotation angle of the rotor 30 cannot be detected with high accuracy based on such a sensor output (electrical signal). For example, it is difficult to correct the offset of the sensor output, and the reliability of the sensor information from the rotation sensor 80 may be reduced.

In contrast, according to this embodiment, as described above, it is possible to obtain a sensor output of waveform 501 (see FIG. 11) that is offset by a certain offset amount corresponding to magnetic flux B3. Therefore, according to this embodiment, it is possible to effectively reduce the possibility that the reliability of the sensor information from the rotation sensor 80 will decrease due to the sensor adjacent portion 300.

In this embodiment, as described above, the sensor adjacent portion 300 is configured so that the magnitude of the eddy current generated by the magnetic flux B1 in the sensor adjacent portion 300 changes periodically every time the rotation angle of the rotor 30 changes by a predetermined angle (45 degrees in this embodiment), but this is not limited to this. For example, in a modified example, the sensor adjacent portion 300 may be configured so that the magnitude of the eddy current generated by the magnetic flux B1 in the sensor adjacent portion 300 changes periodically every time the rotation angle of the rotor 30 changes by an integer multiple of the predetermined angle (for example, 90 degrees). In this case, the offset amount (see Δ1 in FIG. 11) is not constant, but changes periodically with a period that is two or more integer multiples of the change period of the outer diameter of the sensor rotor 81 (period corresponding to the predetermined angle). Therefore, in this case as well, a sensor output that can detect the rotation angle of the rotor 30 with higher accuracy than the comparative example can be obtained.

[Example 2]
In the following description of the second embodiment, components that may be similar to those in the first embodiment described above will be given the same reference numerals and descriptions thereof may be omitted.

Figure 14 is an axial plan view that shows a schematic diagram of the sensor adjacent portion 300 and the sensor rotor 81A in the motor 1A according to the second embodiment, and like Figure 9, shows only the upper half above the rotating shaft 12.

The motor 1A according to the second embodiment differs from the motor 1 according to the first embodiment described above in that the sensor rotor 81 is replaced with a sensor rotor 81A.

In the above-described first embodiment, the magnitude of the eddy current generated in the sensor adjacent portion 300 due to the magnetic flux B1 from the sensing portion 82 is periodically changed every time the rotation angle of the rotor 30 changes by a predetermined angle, together with the magnitude of the eddy current generated in the sensor rotor 81 due to the magnetic flux B1 from the sensing portion 82.

In contrast, in this embodiment, the configuration of the sensor rotor 81A maintains the magnitude of the eddy current that may occur in the sensor adjacent portion 300 due to the magnetic flux B1 from the sensing portion 82 at a substantially constant value regardless of the rotation angle of the rotor 30, thereby achieving a similar effect.

Specifically, in this embodiment, the sensor rotor 81A is arranged so as to overlap the first portion 301 and the second portion 302 of the sensor adjacent portion 300 when viewed in the axial direction, as shown in FIG. 14. The sensor rotor 81A has a small diameter portion 810A at a circumferential position corresponding to the first portion 301, and the sensor rotor 81A has a large diameter portion 812A at a circumferential position corresponding to the second portion 302, and the outer diameter of the small diameter portion 810A may be equal to or larger than the outer diameter of the first portion 301, and the outer diameter of the large diameter portion 812A may be equal to or larger than the outer diameter of the second portion 302. Note that the portion 304 radially outward of the second portion 302 in the sensor adjacent portion 300 is a portion that does not have irregularities or holes, and is a portion where eddy currents that may be generated due to the magnetic flux B1 from the sensing portion 82 are approximately constant.

In this case, the first portion 301 and the second portion 302 of the sensor adjacent portion 300 do not directly face the sensor coil 821 in the axial direction, so the magnitude of the eddy current generated in the sensor adjacent portion 300 due to the magnetic flux B1 from the sensing portion 82 is an approximately constant value caused by the portion 304 (a portion that does not have irregularities or holes, etc.) radially outward of the second portion 302 in the sensor adjacent portion 300. As a result, the magnitude of the eddy current that may be generated in the sensor adjacent portion 300 due to the magnetic flux B1 from the sensing portion 82 can be maintained at an approximately constant value regardless of the rotation angle of the rotor 30. Note that the approximately constant value is a concept that includes a state in which the amount of fluctuation is within about 10%.

Also in this embodiment, the sensor rotor 81A has a portion (small diameter portion 810A and large diameter portion 812B) whose outer diameter at a circumferential position axially opposite to the sensing portion 82 changes periodically every time the rotation angle of the rotor 30 changes by a predetermined angle. As a result, in this embodiment, the time series waveform of the sensor output (electrical signal) generated by the sensing portion 82 has a waveform having a substantially constant offset amount due to the portion 304 (a portion having no irregularities or holes, etc.) radially outward of the second portion 302 in the sensor adjacent portion 300, with respect to the waveform due to the small diameter portion 810A and the large diameter portion 812A. Specifically, in this embodiment, the time series waveform of the sensor output (electrical signal) generated by the sensing portion 82 is similar to the waveform 501 shown in FIG. 11. Therefore, the rotation angle of the rotor 30 can be detected with high accuracy based on such a sensor output (electrical signal).

The sensor rotor 81A according to this embodiment is configured to cover the second portion 302, which has a larger outer diameter than the first portion 301, in the axial direction, and therefore extends radially outward further than the sensor rotor 81 in the above-described first embodiment, which does not cover the second portion 302 in the axial direction. That is, the small diameter portion 810A and the large diameter portion 812A of the sensor rotor 81A according to this embodiment have larger outer diameters than the small diameter portion 810 and the large diameter portion 812 of the sensor rotor 81 in the above-described first embodiment. Correspondingly, in this embodiment, the sensing portion 82 may be disposed radially outward from the mounting position (see FIGS. 1A and 1B) in the above-described first embodiment.

In addition, since the sensor rotor 81A according to this embodiment has a form that covers the second portion 302 in the axial direction, the sensor output of the sensing unit 82 is not substantially affected by the second portion 302. Therefore, the sensor rotor 81A according to this embodiment may be applied to a sensor adjacent portion that does not have the second portion 302 periodically, instead of the sensor adjacent portion 300. That is, in this embodiment, one or more second portions 302 in the sensor adjacent portion 300 may be arranged at a radial position corresponding to one of the large diameter portions 812A of the sensor rotor 81A, and it is not necessary that the second portion 302 is arranged in a one-to-one correspondence with each of the large diameter portions 812A of the sensor rotor 81A. For example, the sensor adjacent portion may have only seven second portions 302 instead of eight, and in this case, each of the seven second portions 302 may be arranged at a corresponding one radial position of the large diameter portion 812A of the sensor rotor 81A.

[Example 3]
In the following description of the third embodiment, components that may be similar to those in the first embodiment described above will be given the same reference numerals and descriptions thereof may be omitted.

Figure 15 is an axial plan view that shows a schematic diagram of the sensor adjacent portion 300 and the sensor rotor 81B in the motor 1B according to the third embodiment, and like Figure 9, shows only the upper half of the motor 1B above the rotating shaft 12. Figure 16 is a perspective view of the sensor rotor 81B according to this embodiment, and Figure 17 shows the waveform of the sensor output (electrical signal) generated by the sensing unit 82 in this embodiment, and the waveform of the sensor output influenced by the sensor adjacent portion 300. In Figure 17, the horizontal axis represents the rotation angle of the rotor 30, and the vertical axis represents the magnitude of the sensor output, and the time series waveform of the sensor output (electrical signal) generated by the sensing unit 82 is shown as a schematic diagram.

The motor 1B according to the third embodiment differs from the motor 1 according to the first embodiment described above in that the sensor rotor 81 is replaced with a sensor rotor 81B.

In the above-described first embodiment, the magnitude of the eddy current generated in the sensor adjacent portion 300 due to the magnetic flux B1 from the sensing portion 82 is periodically changed every time the rotation angle of the rotor 30 changes by a predetermined angle, together with the magnitude of the eddy current generated in the sensor rotor 81 due to the magnetic flux B1 from the sensing portion 82.

In contrast, in this embodiment, the configuration of the sensor rotor 81B maintains the magnitude of the eddy current that may occur in the sensor adjacent portion 300 due to the magnetic flux B1 from the sensing portion 82 at a substantially constant value regardless of the rotation angle of the rotor 30, thereby achieving a similar effect.

Specifically, in this embodiment, the sensor rotor 81B has a cover portion 813B on the radial outside of each of the small diameter portion 810 and the large diameter portion 812, as shown in Figures 15 and 16. The cover portion 813B may be formed thinner than each of the small diameter portion 810 and the large diameter portion 812. The cover portion 813B is formed of the same material as the small diameter portion 810 and the large diameter portion 812, but in a modified example, it may be formed of a material different from the small diameter portion 810 and the large diameter portion 812 (e.g., a high magnetic permeability material). The cover portion 813B is continuous with the radially outer edge portions of each of the small diameter portion 810 and the large diameter portion 812, and extends radially so that the outer diameter of the entire sensor rotor 81B is constant. In this case, the outer diameter of the sensor rotor 81B is determined by the radially outer edge portion of the cover portion 813B. The cover portion 813B extends radially so as to overlap the second portion 302 (not visible in FIG. 15 due to the cover portion 813B) of the sensor adjacent portion 300 when viewed in the axial direction. The outer diameter of the sensor rotor 81B may be equal to or greater than the outer diameter of the second portion 302 (see FIG. 8) of the sensor adjacent portion 300.

In this case, the first portion 301 and the second portion 302 of the sensor adjacent portion 300 do not directly face the sensor coil 821 in the axial direction, so the magnitude of the eddy current that may occur in the sensor adjacent portion 300 due to the magnetic flux B1 from the sensing portion 82 is an approximately constant value caused by the portion 304 (a portion that does not have irregularities or holes, etc.) radially outward of the cover portion 813B in the sensor adjacent portion 300. As a result, the magnitude of the eddy current that may occur in the sensor adjacent portion 300 due to the magnetic flux B1 from the sensing portion 82 can be maintained at an approximately constant value regardless of the rotation angle of the rotor 30.

Also, in this embodiment, the sensor rotor 81B has a portion (small diameter portion 810 and large diameter portion 812) whose outer diameter at a circumferential position axially facing the sensing portion 82 changes periodically every time the rotation angle of the rotor 30 changes by a predetermined angle. Also, in this embodiment, the cover portion 813B of the sensor rotor 81B directly faces the sensor coil 821 in the axial direction, but the magnitude of the eddy current that may be generated in the cover portion 813B due to the magnetic flux B1 from the sensing portion 82 is approximately constant. This is because, as described above, the outer diameter of the cover portion 813B is constant. As a result, in this embodiment, the time-series waveform of the sensor output (electrical signal) generated by the sensing portion 82 has a waveform having an approximately constant offset amount due to the cover portion 813B and the portion 304 with respect to the waveform due to the small diameter portion 810 and the large diameter portion 812. Specifically, in this embodiment, as shown in FIG. 17, the waveform 502 has a substantially constant offset (see Δ2 in FIG. 17) with respect to the ideal waveform 500 shown in FIG. 5. Therefore, based on such a sensor output (electrical signal), the rotation angle of the rotor 30 can be detected with high accuracy.

In addition, since the sensor rotor 81B according to this embodiment has a configuration in which the second portion 302 is covered in the axial direction by the cover portion 813B, the sensor output of the sensing portion 82 is not substantially affected by the second portion 302. Therefore, instead of the sensor adjacent portion 300, the sensor rotor 81B may be applied to a sensor adjacent portion that does not have the second portion 302 periodically. In particular, in the case of this embodiment, since the cover portion 813B is formed around the entire circumference, the second portion 302 may be formed at any position in the circumferential direction. Therefore, according to this embodiment, the design freedom of the sensor adjacent portion 300 can be effectively increased.

Although each embodiment has been described in detail above, it is not limited to a specific embodiment, and various modifications and changes are possible within the scope of the claims. It is also possible to combine all or a combination of multiple components of the above-mentioned embodiments. Furthermore, among the effects of each embodiment, the effects related to the dependent claims are additional effects that are distinguished from the superordinate concept (independent claim).

For example, in the above-mentioned Example 1 (similar to Examples 2 and 3), the sensor rotor 81 has an outer diameter that changes periodically along a period, but instead of or in addition to the periodically changing outer diameter, the sensor rotor 81 may have a thickness (axial thickness) that changes periodically. In this case, the thickness of the sensor rotor 81 at a circumferential position axially opposite the sensing portion 82 changes periodically every time the rotation angle of the rotor 30 changes by a predetermined angle.

1...motor (rotating electric machine), 10...motor housing (non-rotating part), 30...rotor, 300...sensor adjacent part, 301...first part (base part or specific part, concave part), 302...second part (base part or specific part, convex part), 81...sensor rotor, 810, 810A...small diameter part (part), 812, 812A...large diameter part (part), 82...sensing part, 821...sensor coil (coil)

Claims (5)

A rotor;
A non-rotating portion that rotatably supports the rotor;
a sensor rotor that rotates integrally with the rotor;
a sensing unit having a coil axially opposed to the sensor rotor, and configured to generate an electric signal corresponding to a parameter value relating to the rotation of the rotor by generating an eddy current in the sensor rotor due to a magnetic flux generated by energizing the coil,
the sensor rotor has a portion in which an outer diameter or an axial thickness at a circumferential position axially opposed to the sensing portion changes periodically every time a rotation angle of the rotor changes by a predetermined angle,
the rotor has a sensor adjacent portion adjacent to the sensor rotor in the axial direction from a side opposite to the sensing portion,
A rotating electric machine in which the magnitude of the eddy current generated by the magnetic flux in the portion adjacent to the sensor changes periodically each time the rotation angle of the rotor changes by the specified angle or by an integer multiple of the specified angle. the sensor adjacent portion has a base portion and a specific portion in which a magnitude of an eddy current generated by the magnetic flux when the specific portion faces the sensing portion in the axial direction is different from that of the base portion;
The rotating electric machine according to claim 1 , wherein the specific portion faces the sensing portion in the axial direction every time a rotation angle of the rotor changes by the predetermined angle or by an integral multiple of the predetermined angle. A rotor;
A non-rotating portion that rotatably supports the rotor;
a sensor rotor that rotates integrally with the rotor;
a sensing unit having a coil axially opposed to the sensor rotor, and configured to generate an electric signal corresponding to a parameter value relating to the rotation of the rotor by generating an eddy current in the sensor rotor due to a magnetic flux generated by energizing the coil,
the sensor rotor has a portion in which an outer diameter or an axial thickness at a circumferential position axially opposed to the sensing portion changes periodically every time a rotation angle of the rotor changes by a predetermined angle,
the rotor has a sensor adjacent portion adjacent to the sensor rotor in the axial direction from a side opposite to the sensing portion,
A rotating electric machine, wherein a magnitude of an eddy current generated by the magnetic flux in the portion adjacent to the sensor remains substantially constant even when a rotation angle of the rotor changes. the sensor adjacent portion has a base portion and a specific portion in which a magnitude of an eddy current generated by the magnetic flux when the specific portion faces the sensing portion in the axial direction is different from that of the base portion;
The rotating electric machine according to claim 3 , wherein the sensor rotor is disposed so as to overlap the base portion and the specific portion when viewed in the axial direction. The rotating electric machine according to claim 2 or 4, wherein the specific portion includes at least one of a convex portion having an outer diameter larger than that of the base portion and a concave portion having an outer diameter smaller than that of the base portion.

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