Electric motor

Abstract

To disclose one example of an electric motor in which a gear for a speed reducer, etc. are abolished.SOLUTION: An electric motor 1 comprises: an annular ring rotor 3 which is arranged in a stator 2 with a second center O2 as a center, and has the smaller number of permanent magnets 3A, 3B than the number of stator coils 2B, and in which N poles and S poles of the permanent magnets 3A, 3B are alternately arranged along an outer peripheral surface; an eccentric shaft 4 which rotatably supports the ring rotor 3 with the second center O2 as a center and is rotatably supported with a first center O1 as a center; an output unit which outputs rotation of the ring rotor 3 with the second center O2 as a center; a detection unit which detects a position of the ring rotor 3; and a control unit which controls timing for energizing each of the plurality of stator coils 2B by using a detection signal of the detection unit and controls energization to the stator coils 2B by using one or the plurality of stator coils 2B as one set.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to electric motors. [Background technology]

[0002] As shown in Patent Document 1, many electric motors supply rotational force to a driven part via a reducer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2009-517105 Summary of the Invention [Problem to be solved by the invention]

[0004] Since reducers are composed of multiple moving parts such as gears, they are prone to generating noise and vibration. In response to this, currently, strict control is required for the dimensional accuracy and assembly accuracy of each moving part, and sound-insulating materials are used. The present disclosure discloses an example of an electric motor that takes these points into consideration. [Means for solving the problem]

[0005] An electric motor having a stator (2) with a plurality of stator coils (2B) arranged along its circumference, when the center of the circumference is defined as a first center (O1) and a position shifted from the first center (O1) is defined as a second center (O2), preferably has the following configuration requirements:

[0006] That is, the constituent elements are: an annular ring rotor (3) arranged within the stator (2) and centered on a second center (O2); the ring rotor (3) has fewer permanent magnets (3A, 3B) than the stator coils (2B), and the north and south poles of the permanent magnets (3A, 3B) are arranged alternately along the outer circumferential surface; an eccentric shaft (4) that supports the ring rotor (3) rotatably around the second center (O2) and is also supported rotatably around the first center (O1); an output unit (5) that outputs the rotation of the ring rotor (3) centered on the second center (O2); a detection unit (7) that detects the position of the ring rotor (3) or the eccentric shaft (4); and a control unit (8) that uses the detection signal of the detection unit (7) to control the timing of applying current to each of the multiple stator coils (2B).

[0007] As a result, the output portion 5 of the electric motor rotates at a reduced speed of the eccentric shaft 4. Therefore, the electric motor can generate less noise and vibration than a reducer using multiple gears.

[0008] The electric motor may have the following configuration, for example. That is, when the ring rotor (3) is the first ring rotor (31), the output section (5) is the first output section (51), and a position 180 degrees shifted from the second center (O2) around the first center (O1) is the third center (O3), the second ring rotor (32) is arranged in the stator while being rotatably supported by the eccentric shaft (4) around the third center (O3), and is annular and centered on the third center (O3), and has fewer permanent magnets than the stator coils, and the north and south poles of the permanent magnets are arranged alternately along the outer circumferential surface, and a second output section (52) that outputs the rotation of the second ring rotor (32) around the third center (O3).

[0009] As a result, in the electric motor, the first ring rotor (31) and the second ring rotor (32) revolve at positions circumferentially offset by 180 degrees from each other about the first center (O1).

[0010] Therefore, the eccentric force generated by the rotation of the first ring rotor (31) is offset by the eccentric force generated by the rotation of the second ring rotor (32), which in turn can reduce vibrations generated in the electric motor.

[0011] In the electric motor, the first output portion (51) includes a first rotary plate (51A) supported rotatably about a first center (O1) and a first swivel plate (51C) integrated with the first ring rotor (31), one (51A) of the first rotary plate (51A) and the first swivel plate (51C) is provided with a first protrusion (51D) protruding toward the other plate (51C), and the other plate (51C) is provided with a first hole (51F) into which the first protrusion (51D) can fit. The second output portion (52) is configured to rotate around the first center (O1). The rotor (51A) preferably includes a second rotary plate (52A) rotatably supported on the rotor (51A) and a second swivel plate (52C) ​​integrated with the second ring rotor (32), one (52A) of the second rotary plate (52A) and the second swivel plate (52C) ​​is provided with a second protrusion (52D) protruding toward the other plate (52C), and the other plate (52C) ​​is provided with a second hole (52F) into which the second protrusion (52D) can fit, and further includes a transmission part (53) that transmits the rotation of the second rotary plate (52A) to the first rotary plate (51A).

[0012] Furthermore, it is desirable that the first rotating plate (51A) and the second rotating plate (52A) are configured in a disk shape and have gear teeth (51G, 52G) on their outer peripheries, and that the transmission part (53) has a first gear part (53A) that meshes with the tooth part (51G) of the first rotating plate (51A) and a second gear part (53B) that meshes with the tooth part (52G) of the second rotating plate (52A).

[0013] Furthermore, it is preferable that the core 2A of the stator 2 is provided with a through hole 2E through which the transmission part 53 passes. Incidentally, the symbols in each of the parentheses above are examples showing the correspondence with the specific configurations, etc. described in the embodiments described below, and the present disclosure is not limited to the specific configurations, etc. shown by the symbols in the parentheses above. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a diagram showing the structure of an electric motor according to a first embodiment. [Figure 2] 1 is a cross-sectional view showing the structure of an electric motor according to a first embodiment. [Figure 3] FIG. 1 is an exploded view showing the structure of an electric motor according to a first embodiment. [Figure 4] 1 is a diagram showing the structure of an electric motor according to a first embodiment. [Figure 5] FIG. 2 is a diagram showing a stator according to the first embodiment. [Figure 6] 2 is a diagram showing an eccentric shaft and a ring rotor according to the first embodiment. FIG. [Figure 7] FIG. 2 is a diagram illustrating an output unit according to the first embodiment. [Figure 8] 4 is a chart showing energization timing of the control unit according to the first embodiment. [Figure 9] FIG. 2 is an explanatory diagram of the operation of the electric motor according to the first embodiment. [Figure 10] FIG. 2 is an explanatory diagram of the operation of the electric motor according to the first embodiment. [Figure 11] FIG. 2 is an explanatory diagram of the operation of the electric motor according to the first embodiment. [Figure 12] FIG. 2 is an explanatory diagram of the operation of the electric motor according to the first embodiment. [Figure 13] FIG. 2 is an explanatory diagram of the operation of the electric motor according to the first embodiment. [Figure 14] FIG. 2 is an explanatory diagram of the operation of the electric motor according to the first embodiment. [Figure 15] FIG. 2 is an explanatory diagram of the operation of the electric motor according to the first embodiment. [Figure 16] FIG. 2 is an explanatory diagram of the operation of the electric motor according to the first embodiment. [Figure 17]FIG. 2 is an explanatory diagram of the operation of the electric motor according to the first embodiment. [Figure 18] FIG. 6 is a diagram showing the structure of an electric motor according to a second embodiment. [Figure 19] FIG. 6 is a cross-sectional view showing the structure of an electric motor according to a second embodiment. [Figure 20] FIG. 3 is a diagram showing the relative positions of a first ring rotor and a second ring rotor. [Figure 21] FIG. 3 is a diagram showing the relative positions of a first ring rotor and a second ring rotor. [Figure 22] FIG. 6 is a cross-sectional view showing the structure of an electric motor according to a second embodiment. [Figure 23] 10 is a chart showing energization timing of a control unit according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0015] The following "embodiments of the invention" are examples of embodiments that fall within the technical scope of the present disclosure. In other words, the invention-specific matters described in the claims are not limited to the specific configurations and structures shown in the following embodiments.

[0016] In this embodiment, an electric motor according to the present disclosure is applied to an electric motor that supplies driving force to a movable part of a seat (hereinafter referred to as a vehicle seat) mounted on a vehicle such as a car. Arrows and diagonal lines indicating directions in each figure are provided to facilitate understanding of the relationships between the figures and the shapes of components or parts.

[0017] At least one of a component or part that is described with a reference numeral is provided unless otherwise specified, such as "one." The electric motor shown in this disclosure includes at least one of the components such as the component or part that is described with a reference numeral and the structural parts shown in the drawings.

[0018] (First embodiment) <1. Electric motor configuration (see Figs. 1 to 6)> The electric motor 1 includes at least a stator 2 (see Figure 5), a ring rotor 3 (see Figure 6), an eccentric shaft 4 (see Figure 6), an output section 5 (see Figure 2), a housing 6 (see Figures 1 to 3), a detection section 7 (see Figure 2), and a control section 8 (see Figure 2).

[0019] <Stator> As shown in Fig. 5, the stator 2 includes an annular core (also called a yoke) 2A and multiple stator coils 2B. Each stator coil 2B is a winding that generates electromagnetic force. The stator coils 2B are arranged along the circumference.

[0020] The core 2A is a member that forms a magnetic path for the magnetic flux induced by each stator coil 2B. As shown in Fig. 4, the core 2A has an annular ring portion 2C and multiple magnetic pole portions 2D. The number of the magnetic pole portions 2D is the same as the number of the stator coils 2B.

[0021] Each magnetic pole portion 2D is a portion that protrudes from the inner periphery of the ring portion 2C toward the center of the ring portion 2C. Each stator coil 2B is composed of a winding wound around the corresponding magnetic pole portion 2D. The ring portion 2C and each magnetic pole portion 2D are an integrated part made of multiple electromagnetic steel plates.

[0022] The electromagnetic steel plates are laminated in a direction parallel to the rotation axis of the ring rotor 3 (see FIG. 2). Hereinafter, as shown in FIG. 4, the center of the ring portion 2C is referred to as a first center O1, and a position shifted from the first center O1 is referred to as a second center O2.

[0023] <Ring rotor> As shown in Fig. 4, the ring rotor 3 is an annular member disposed within the stator 2 and centered on the second center O2. As shown in Fig. 6, the ring rotor 3 has fewer permanent magnets 3A and 3B than the magnetic pole portions 2D.

[0024] Since the number of permanent magnets 3A, 3B is less than the number of magnetic pole portions 2D (stator coils 2B), the center-to-center angle between adjacent permanent magnets 3A, 3B is greater than the center-to-center angle between adjacent magnetic pole portions 2D (stator coils 2B).

[0025] The center-to-center angle of the permanent magnets 3A and 3B refers to the angle formed by an imaginary line connecting the center of each of the permanent magnets 3A and 3B and the second center O2. The center-to-center angle of the magnetic pole portion 2D (stator coil 2B) refers to the angle formed by an imaginary line connecting the center of each of the magnetic pole portions 2D and the first center O1.

[0026] In this embodiment, the number of magnetic pole portions 2D is 12, and the number of permanent magnets 3A, 3B is 10. Therefore, the center-to-center angle between the permanent magnets 3A, 3B is 36 degrees, and the center-to-center angle between the magnetic pole portions 2D is 30 degrees.

[0027] The permanent magnets 3A and 3B are arranged so that their north and south poles alternate along the outer periphery. Each permanent magnet 3A and 3B is fixed to the outer periphery of a cylindrical collar 3C. In other words, the collar 3C and the ring rotor 3 are integrated.

[0028] <Eccentric shaft> As shown in Fig. 6, the eccentric shaft 4 supports the ring rotor 3 rotatably about the second center O2. Specifically, the collar 3C is cylindrical with the second center O2 as its central axis. A bearing 3D is provided on the inner periphery of the collar 3C, as shown in Fig. 2.

[0029] Therefore, the ring rotor 3 can rotate about the second center O2 relative to the eccentric shaft 4. Note that hereinafter, the rotation of the ring rotor 3 about the second center O2 will also be referred to as "the ring rotor 3 rotating on its axis."

[0030] 2, the eccentric shaft 4 is directly or indirectly supported by the housing 6 so as to be rotatable about a first center O1. That is, one axial end of the eccentric shaft 4 is directly supported by the housing 6 via a bearing 6C.

[0031] The other axial end of the eccentric shaft 4 is indirectly supported by the housing 6 via a bearing 6D. Specifically, the bearing 6D is provided on the rotating plate 5A of the output unit 5. The rotating plate 5A, i.e., the output shaft 5B of the output unit 5, is rotatably supported by the housing 6 via a bearing 5F.

[0032] <Housing> The housing 6 is a casing that houses the stator 2 and other components. The housing 6 according to this embodiment is configured to include a first housing 6A and a second housing 6B. A bearing 5F is disposed in the first housing 6A. A bearing 6C is disposed in the second housing 6B.

[0033] <Output section> The output unit 5 outputs the rotation of the ring rotor 3 about the second center O2, that is, the rotation of the ring rotor 3. Specifically, as shown in Fig. 2, the output unit 5 has at least a rotating plate 5A, an output shaft 5B, and a swiveling plate 5C.

[0034] The rotary plate 5A and the output shaft 5B are integrated. The output shaft 5B is supported via a bearing 5F so as to be rotatable about a first center O1. In other words, the rotary plate 5A and the output shaft 5B are rotatable about the first center O1.

[0035] The rotating plate 5A is a disk-shaped member and has a plurality of columnar or cylindrical protrusions 5D on a circumference centered on the first center O1, as shown in Fig. 7. These protrusions 5D protrude toward the swivel plate 5C.

[0036] 2, the swivel plate 5C is a member integrated with the ring rotor 3 via a collar 3C. That is, the swivel plate 5C is rotatably supported on the eccentric shaft 4 via a bearing 5E around the second center O2.

[0037] 7, the swivel plate 5C is provided with the same number of holes or recesses (through holes 5F in this embodiment) as the number of protrusions 5D. These through holes 5F are holes into which the protrusions 5D can fit, and are provided on a circumference centered on the second center O2.

[0038] The distance r1 from the center of each protrusion 5D to the first center O1 is the same as the distance r2 from the center of each through hole 5F to the second center O2. Furthermore, the radius of each through hole 5F is the same as the distance between the first center O1 and the second center O2. The outer peripheral surface of each protrusion 5D can come into sliding contact with the inner peripheral surface of the corresponding through hole 5F.

[0039] <Detection section> The detection unit 7 detects the position of the ring rotor 3 or the eccentric shaft 4 (in this embodiment, the eccentric shaft 4). As shown in Fig. 2, the detection unit 7 is configured to include a sensor magnet plate 7A that rotates integrally with the eccentric shaft 4, a sensor substrate 7B, and the like.

[0040] One or more magnetic bodies such as permanent magnets are arranged on the sensor magnet plate 7A. The sensor board 7B has a sensor that detects changes in the magnetic field, such as a Hall IC. The sensor board 7B detects the rotation angle of the eccentric shaft 4 by utilizing the change in the magnetic field that accompanies the rotation of the eccentric shaft 4.

[0041] <Control unit> The control unit 8 controls the timing of energizing each of the plurality of stator coils 2B using the detection signal of the detection unit 7. Specifically, the control unit 8 controls energization of one or more stator coils 2B as a group.

[0042] 8, the control unit 8 according to this embodiment energizes the stator coils 2B one by one along the ring portion 2C. In other words, an electromagnetic force that rotates along the ring portion 2C is generated in the stator 2. Hereinafter, such a magnetic field is also referred to as a rotating magnetic field.

[0043] 2. Operation of the electric motor according to this embodiment Hereinafter, the stator coils 2B will be referred to as winding A, winding B, ..., and winding L, as shown in Fig. 9. The permanent magnets 3A and 3B will be referred to as magnet a, magnet b, ..., and magnet j. The control unit 8 then applies current to each stator coil 2B in the following order: winding A → winding B → ... → winding L → winding A → winding B → ... → winding L → winding A → winding B → ... (see Fig. 8).

[0044] In this embodiment, each stator coil 2B is configured so that the polarity of the magnetic field generated by adjacent stator coils 2B is different. In other words, the magnetic pole generated when current is applied to winding A is different from the magnetic pole generated when current is applied to winding B.

[0045] 9, when a current is applied to the winding A, the magnet a located close to the winding A is electromagnetically attracted to the winding A and moves close to the winding A. At this time, the ring rotor 3 and the eccentric shaft 4 rotate so that the center of the winding A (hereinafter referred to as the winding center A), the second center O2, and the first center O1 are positioned on the straight line LA.

[0046] That is, the ring rotor 3 can rotate about the second center O2, and the eccentric shaft 4 can rotate about the first center O1. When the winding A is energized and the winding center A, the second center O2, and the first center O1 are positioned on the straight line LA, the rotational force that rotates the ring rotor 3 and the eccentric shaft 4 becomes zero.

[0047] Therefore, when current is applied to any of the multiple windings A to L, the ring rotor 3 and the eccentric shaft 4 attempt to rotate and displace until the winding center of the energized stator coil 2B, the second center O2, and the first center O1 are positioned on a straight line.

[0048] Then, when the current-carrying winding is switched from winding A to winding B, the ring rotor 3 and the eccentric shaft 4 rotate so that the winding center B, which is the center of winding B, the second center O2, and the first center O1 are positioned on the straight line LB (see Figure 10).

[0049] Specifically, the eccentric shaft 4 rotates through the angle formed by the straight lines LA and LB (30 degrees in this embodiment). Similarly, the second center O2 rotates through the above angle (30 degrees in this embodiment) around the first center O1.

[0050] The center-to-center angle between the permanent magnets 3A and 3B is larger than the center-to-center angle between the magnetic pole portion 2D. Therefore, in order for the winding center, the second center O2, and the first center O1 to be aligned on the same straight line, the ring rotor 3 must rotate in the direction opposite to the direction of rotation of the eccentric shaft 4.

[0051] That is, the center of magnet b is offset by 36 degrees around the second center O2 from the center of magnet a. Therefore, in order for the winding center B, the second center O2, and the first center O1 to be positioned on the straight line LB, the ring rotor 3 is forced to rotate by 6 degrees around the second center O2 in the direction opposite to the direction of rotation of the eccentric shaft 4.

[0052] Therefore, when current is sequentially applied to each stator coil 2B in the order of winding A → winding B →... → winding L → winding A, the eccentric shaft 4 rotates 30 degrees to the right each time the current is switched, as shown in the order of, for example, Figures 9 → 10 → 11 → 12 → 13 → 14 → 5 → 15 → 17, and finally rotates 360 degrees.

[0053] In other words, each time the current flow is switched, the straight line L passing through the winding center, the second center O2, and the first center O1 rotates to the right around the first center O1 by 30 degrees each time in the order LA → LB → LC → LD → ···LG → ···LK, and finally rotates 360 degrees.

[0054] At this time, the ring rotor 3 rotates counterclockwise by 6 degrees around the second center O2 each time the power supply is switched, and finally rotates by 72 degrees. Note that the second center O2 rotates clockwise around the first center O1, so the ring rotor 3 rotates clockwise around the first center O1 (hereinafter, this rotation is referred to as orbiting).

[0055] Incidentally, the ring rotor 3 rotates leftward while revolving rightward relative to the housing 6. Therefore, the rotation of the ring rotor 3 cannot be directly used as an output. For this reason, in this embodiment, the swivel plate 5C rotates and rotates integrally with the ring rotor 3, and the swivel plate 5C and the rotating plate 5A convert the rotation of the ring rotor 3 into rotation around the first center O1.

[0056] That is, in this embodiment, the swivel plate 5C and the rotation plate 5A form a joint that absorbs the misalignment of the rotation center axes of the output shaft 5B and the ring rotor 3, and the rotation of the ring rotor 3.

[0057] 3. Features of the electric motor according to this embodiment As described above, the rotation of the ring rotor 3 converted into rotation about the first center O1 is output to the outside via the output shaft 5B. In other words, the electric motor 1 according to this embodiment can produce less noise and vibration than a reducer using multiple gears.

[0058] (Second embodiment) <1. Configuration of the electric motor according to this embodiment> 18 to 21, the electric motor 1 according to this embodiment at least includes a first ring rotor 31, a second ring rotor 32, and a transmission part 53. Each of the ring rotors 31, 32 is the same ring rotor as the ring rotor 3 according to the first embodiment.

[0059] As shown in FIG. 20, the first ring rotor 31 is supported by an eccentric shaft 4 so as to be rotatable about a second center O2, similar to the ring rotor 3 according to the first embodiment.

[0060] The second ring rotor 32 is supported by the eccentric shaft 4 so as to be rotatable about a third center O3. As shown in Fig. 21, the third center O3 is a position that is circumferentially shifted 180 degrees from the second center O2 around the first center O1.

[0061] Therefore, the third center O3 is located on a virtual line passing through the first center O1 and the second center O2, and is located on the opposite side of the first center O1 from the second center O2. The distance between the first center O1 and the third center O3 is the same as the distance between the first center O1 and the second center O2.

[0062] 18, the first output section 51 that transmits the rotation of the first ring rotor 31 to the output shaft 5B is the same as the output section 5 according to the first embodiment. Specifically, the first output section 51 is configured to include a first rotating plate 51A and a first swivel plate 51C.

[0063] The first rotating plate 51A corresponds to the rotating plate 5A and is a disk-shaped member supported rotatably around the first center O1. The first swivel plate 51C corresponds to the swivel plate 5C and is a disk-shaped member integrated with the first ring rotor 31.

[0064] The first rotating plate 51A is provided with a first protrusion 51D that protrudes toward the first swivel plate 51C. The first swivel plate 51C is provided with a first hole 51F into which the first protrusion 51D can fit.

[0065] 19, the second output section 52 for transmitting the rotation of the second ring rotor 32 to the output shaft 5B is the same as the output section 5 according to the first embodiment. Specifically, the second output section 52 is configured to include a second rotating plate 52A and a second swivel plate 52C.

[0066] The second rotating plate 52A corresponds to the rotating plate 5A and is a disk-shaped member supported rotatably around the first center O1. The second swivel plate 52C corresponds to the swivel plate 5C and is a disk-shaped member integrated with the second ring rotor 32.

[0067] The second rotating plate 52A is provided with a second protrusion 52D that protrudes toward the second swivel plate 52C. The second swivel plate 52C is provided with a second hole 52F into which the second protrusion 52D can fit.

[0068] 22, the transmission part 53 is a member that extends in a direction parallel to the axial direction of the eccentric shaft 4 and transmits the rotation of the second rotating plate 52A to the first rotating plate 51A. In this embodiment, a plurality of transmission parts 53 are arranged along the circumferential direction.

[0069] That is, teeth 51G and 52G for forming gears are provided on the outer peripheries of the first rotating plate 51A and the second rotating plate 52A. Each transmission part 53 is provided with at least a first gear part 53A and a second gear part 53B.

[0070] The first gear portion 53A is a gear portion that meshes with the tooth portion 51G of the first rotating plate 51A. The second gear portion 53B is a gear portion that meshes with the tooth portion 52G of the second rotating plate 52A. The core 2A of the stator 2 is provided with a through hole 2E through which the transmission portion 53 passes.

[0071] In addition, each through hole 2E in this embodiment is a concave hole that is recessed from the outer periphery of the core 2A toward the eccentric shaft 4, and is composed of a hole that penetrates the core 2A in a direction parallel to the axial direction of the eccentric shaft 4.

[0072] 23, the control unit 8 according to this embodiment sequentially energizes the two stator coils 2B, which are positioned 180 degrees apart along the ring portion 2C, along the ring portion 2C. This causes the first ring rotor 31 and the second ring rotor 32 to rotate by the same operation as in the first embodiment.

[0073] The rotation of the second ring rotor 32 is transmitted to the first rotating plate 51A via the second output portion 52 and the multiple transmission portions 53. The rotation of the first ring rotor 31 is transmitted to the first rotating plate 51A. Therefore, the rotational force generated in the first ring rotor 31 and the second ring rotor 32 is output from the output shaft 5B via the first rotating plate 51A.

[0074] The same components as those in the above-described embodiment are denoted by the same reference numerals, and therefore, redundant explanations will be omitted in this embodiment. 2. Features of the electric motor according to this embodiment In the electric motor 1 according to this embodiment, the first ring rotor 31 and the second ring rotor 32 are arranged at positions offset from each other by 180 degrees in the circumferential direction and revolve around the first center O1.

[0075] Therefore, the eccentric force generated as the first ring rotor 31 rotates is offset by the eccentric force generated as the second ring rotor 32 rotates. As a result, it may be possible to reduce vibrations generated in the electric motor 1.

[0076] (Other embodiments) In the above-described embodiment, the control is such that the plurality of stator coils 2B are energized one by one in sequence. However, the present disclosure is not limited to this. That is, the present disclosure may be configured such that, for example, two or more stator coils 2B are grouped together, and the plurality of stator coils 2B constituting the group are treated as one unit, and energization is switched and controlled.

[0077] In the above-described embodiment, the position of the ring rotor 3 or the eccentric shaft 4 is detected by a magnetic sensor. However, the present disclosure is not limited to this. That is, the present disclosure may be configured to detect the position of the ring rotor 3 or the eccentric shaft 4 by, for example, an optical sensor.

[0078] In the above-described embodiment, an electric motor according to the present disclosure is applied to an electric motor that supplies driving force to a movable part of a vehicle seat. However, the present disclosure is not limited to this. That is, the present disclosure may be applied to, for example, other applications.

[0079] In the above-described embodiment, the ring rotor 3 and the eccentric shaft 4 are rotated only by the attractive force generated between the stator coil 2B and the permanent magnets 3A and 3B. However, the present disclosure is not limited to this. That is, the present disclosure may rotate the ring rotor 3 and the eccentric shaft 4 by a combination of attractive force and repulsive force.

[0080] In the second embodiment described above, a plurality of transmission parts 53 are provided, and the core 2A is provided with a through hole 2E. However, the present disclosure is not limited to this. That is, at least one transmission part 53 is sufficient, and the through hole 2E may be eliminated.

[0081] Furthermore, the present disclosure is not limited to the above-described embodiments as long as it conforms to the spirit of the disclosure described in the above-described embodiments. Therefore, the present disclosure may be a configuration in which at least two of the above-described embodiments are combined, or a configuration in which any of the components illustrated or described with reference numerals in the above-described embodiments is eliminated. [Explanation of symbols]

[0082] 1... Electric motor 2... Stator 2B... Stator coil 2A... Core 2C... Ring 2D... Magnetic pole 3... Ring rotor 3A, 3B... Permanent magnet 4... Eccentric shaft 5... Output section 5A... Rotating plate 5B... Output shaft 5C... Swivel plate 6... Housing 7...Detection unit 8...Control unit

Claims

1. In an electric motor having a stator with a plurality of stator coils arranged along the circumference, When the center of the circumference is defined as a first center and a position shifted from the first center is defined as a second center, a ring rotor disposed within the stator and having an annular shape centered on the second center, the ring rotor having fewer permanent magnets than the stator coils, and having N poles and S poles of the permanent magnets alternately arranged along an outer circumferential surface; an eccentric shaft that supports the ring rotor rotatably about the second center and is supported rotatably about the first center; an output unit that outputs the rotation of the ring rotor around the second center; a detection unit that detects the position of the ring rotor or the eccentric shaft; a control unit that controls timing for energizing each of the plurality of stator coils using a detection signal from the detection unit; An electric motor comprising:

2. When the ring rotor is a first ring rotor, the output portion is a first output portion, and a position shifted 180 degrees from the second center about the first center is a third center, a second ring rotor disposed within the stator in a state of being rotatably supported by the eccentric shaft about the third center, the second ring rotor being annular and centered on the third center, the second ring rotor having a number of permanent magnets fewer than the number of the stator coils, and the north poles and south poles of the permanent magnets being alternately arranged along an outer circumferential surface; a second output section that outputs the rotation of the second ring rotor around the third center; The electric motor of claim 1 .

3. the first output portion includes a first rotary plate supported rotatably about the first center and a first swivel plate integrated with the first ring rotor, one of the first rotating plate and the first swivel plate is provided with a first protrusion protruding toward the other plate, and the other plate is provided with a first hole into which the first protrusion can fit; the second output portion includes a second rotary plate supported rotatably about the first center and a second swivel plate integrated with the second ring rotor, one of the second rotating plate and the second swivel plate is provided with a second protrusion protruding toward the other plate, and the other plate is provided with a second hole into which the second protrusion can fit; a transmission section for transmitting the rotation of the second rotary plate to the first rotary plate; The electric motor of claim 2 .

4. the first rotating plate and the second rotating plate are configured in a disk shape and have gear teeth on their outer peripheries, 4. The electric motor according to claim 3, wherein the transmission portion has a first gear portion that meshes with the teeth of the first rotary plate, and a second gear portion that meshes with the teeth of the second rotary plate.

5. 5. The electric motor according to claim 4, wherein the core of the stator is provided with a through hole through which the transmission portion passes.

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