Geared motor

Abstract

A geared motor (1) is constituted of an axial gap motor unit (2) and a planetary gear reduction unit (3), and has a base section (4) and an output section (5), wherein: the motor unit (2) has a stator (2a), a rotor (2b), and a motor shaft (2c) that rotates integrally with the rotor (2b); the reduction unit (3) has a sun gear (3a) that rotates integrally with the motor shaft (2c), a planetary gear (3b) having a first gear section (3b1) that meshes with the sun gear (3a) and a second gear section (3b2) that rotates integrally with the first gear section (3b1), a first internal tooth gear (3c) that meshes with the first gear section (3b1), and a second internal tooth gear (3d) that constitutes the output section (5) and meshes with the second gear section (3b2); the rotor (2b) has a plurality of permanent magnets (2b1); and the stator (2a) has a plurality of coils (2a1) and an insulating material (2a2) that is integrally molded so as to connect the plurality of coils (2a1) into a single unit, and has a bearing (6) that is mounted on an inner peripheral edge section of the stator (2a) and supports the motor shaft (2c).

Description

geared motor

[0001] The present invention relates to a geared motor.

[0002] A geared motor is known that is composed of a motor section and a planetary gear type reduction section, has a base section and an output section that rotates relative to the base section, the motor section has a rotating motor shaft, and the reduction section has a sun gear that rotates integrally with the motor shaft, a planetary gear having a first gear section and a second gear section, a first internal gear that is part of the base section and meshes with the first gear section of the planetary gear, and a second internal gear that forms the output section and meshes with the second gear section of the planetary gear, thereby achieving a high reduction ratio (see, for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2000-274495

[0004] When a geared motor having the above structure is mounted on a robot arm, an automatic guided vehicle (AGV), etc., it may be desirable to configure it as a flat, thin motor with a reduced axial length relative to the radial length.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a geared motor that is suitable for being constructed in a thin shape.

[0006] One aspect of the present invention is as follows.

[0007] [1] A geared motor comprising an axial gap motor section and a planetary gear reduction section, having a base and an output section that rotates relative to the base, wherein the motor section has a stator that is a part of the base, a rotor, and a motor shaft that rotates integrally with the rotor, wherein the reduction section has a sun gear that rotates integrally with the motor shaft, a planetary gear having a first gear section that meshes with the sun gear and a second gear section that rotates integrally with the first gear section, a first internal gear that is a part of the base and meshes with the first gear section of the planetary gear, and a second internal gear that constitutes the output section and meshes with the second gear section of the planetary gear, wherein the rotor has a plurality of permanent magnets arranged in a circumferential direction, and the stator has a plurality of coils arranged in a circumferential direction and an insulating material that is integrally molded to connect the plurality of coils together, and wherein the geared motor has a bearing attached to the inner peripheral edge of the stator to support the motor shaft.

[0008] [2] The geared motor according to [1], wherein the reduction section has a planetary carrier, and a second bearing is attached to the planetary carrier to support the motor shaft.

[0009] [3] The geared motor described in [2], wherein the output portion has an outer fitting portion, an inner fitting portion provided radially inward from the outer fitting portion, and a connecting portion that integrally connects the outer fitting portion to the inner fitting portion, the second internal gear is provided integrally with the inner peripheral surface of the outer fitting portion, a third bearing that is attached to the base and supports the outer peripheral surface of the outer fitting portion, and a fourth bearing that is attached to the outer peripheral surface of the inner fitting portion and supports the planetary carrier.

[0010] [4] The geared motor according to any one of [1] to [3], wherein the rotor is disposed adjacent to the planetary gear.

[0011] [5] The geared motor according to any one of [1] to [4], further comprising a stator yoke that rotates integrally with the motor shaft.

[0012] [6] The geared motor according to [5], wherein the stator yoke is provided on the opposite side of the rotor from the stator in the axial direction.

[0013] [7] The geared motor according to any one of [1] to [6], wherein the stator is an air-core type.

[0014] [8] The geared motor according to any one of [1] to [7], wherein the stator has a magnetic core made of a ferromagnetic material.

[0015] [9] The geared motor according to any one of [1] to [8], having a labyrinth structure that seals the boundary between the motor section and the reduction section.

[0016] According to the present invention, it is possible to provide a geared motor that is suitable for being configured to be thin.

[0017] Fig. 2 is a cross-sectional view of a geared motor according to an embodiment of the present invention; Fig. 3 is a cross-sectional perspective view showing a stator and a bearing separated from the geared motor shown in Fig. 1, with a second housing part and a stator yoke omitted; Fig. 4 is a cross-sectional perspective view showing an output section, a third bearing, and a fourth bearing omitted from the geared motor shown in Fig. 1; Fig. 5 is a conceptual diagram showing a modified example of a planetary carrier of the geared motor shown in Fig. 1;

[0018] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0019] As shown in FIGS. 1 to 3 , in one embodiment of the present invention, a geared motor 1 is configured with an axial gap motor unit 2 and a planetary gear reduction unit 3, and has a base unit 4 and an output unit 5 that rotates relative to the base unit 4. The motor unit 2 has a stator 2a that is a part of the base unit 4, a rotor 2b, and a motor shaft 2c that rotates integrally with the rotor 2b. The reduction unit 3 has a sun gear 3a that rotates integrally with the motor shaft 2c, a planetary gear 3b that has a first gear portion 3b1 that meshes with the sun gear 3a and a second gear portion 3b2 that rotates integrally with the first gear portion 3b1, a first internal gear 3c that is a part of the base unit 4 and meshes with the first gear portion 3b1 of the planetary gear 3b, and a second internal gear 3d that constitutes the output unit 5 and meshes with the second gear portion 3b2 of the planetary gear 3b. The rotor 2b has a plurality of permanent magnets 2b1 arranged circumferentially. The stator 2a has a plurality of coils 2a1 arranged in the circumferential direction and an insulating material 2a2 integrally molded to connect the plurality of coils 2a1. The geared motor 1 has a bearing 6 attached to the inner peripheral edge of the stator 2a to support the motor shaft 2c. The material of the insulating material 2a2 of the stator 2a is not particularly limited, and is, for example, resin. The material of the bearing 6 is not particularly limited, and is, for example, metal.

[0020] In this embodiment, the direction along the central axis O, which is the center of rotation of the motor shaft 2c, is called the axial direction, the side along the axial direction from the reduction unit 3 toward the motor unit 2 is called the one axial side, and the opposite side is called the other axial side, the direction perpendicular to the central axis O is called the radial direction, and the direction circumferentially around the central axis O is called the circumferential direction.

[0021] The reduction gear section 3 may be configured such that the first gear portion 3b1 and the second gear portion 3b2 of the planetary gear 3b have the same number of teeth and the first internal gear 3c and the second internal gear 3d have different numbers of teeth, or the first gear portion 3b1 and the second gear portion 3b2 of the planetary gear 3b have different numbers of teeth and the first internal gear 3c and the second internal gear 3d have the same number of teeth, or the first gear portion 3b1 and the second gear portion 3b2 of the planetary gear 3b have different numbers of teeth and the first internal gear 3c and the second internal gear 3d also have different numbers of teeth.

[0022] The above configuration includes a reduction gear unit 3 that achieves a thin profile and a high reduction ratio using a planetary gear 3b having a first internal gear 3c and a second internal gear 3d, and an axial gap motor unit 2 that can achieve the desired output by adjusting its diameter. Furthermore, by supporting the motor shaft 2c via a bearing 6 attached to the inner peripheral edge of the stator 2a, the axial length of the motor unit 2 can be reduced compared to a configuration in which the motor shaft 2c is supported at both axial ends of the base 4. Therefore, the above configuration facilitates the construction of a thin geared motor 1. Furthermore, heat generated in the coil 2a1 can be dissipated to the outside of the geared motor 1 via the bearing 6 and the motor shaft 2c, preventing the permanent magnet 2b1 facing the coil 2a1 from overheating due to a temperature rise in the coil 2a1 and becoming permanently demagnetized. Furthermore, the stator 2a is made of insulating material 2a2, preventing eddy currents from being generated by interlinked magnetic flux and generating heat.

[0023] The reduction gear unit 3 has a planetary carrier 3e, and the geared motor 1 has a second bearing 7 attached to the planetary carrier 3e and supporting the motor shaft 2c.

[0024] The output portion 5 has an outer fitting portion 5a, an inner fitting portion 5b provided radially inward of the outer fitting portion 5a, and a connecting portion 5c that integrally connects the outer fitting portion 5a to the inner fitting portion 5b. The second internal gear 3d is provided integrally with the inner circumferential surface of the outer fitting portion 5a. The geared motor 1 has a third bearing 8 attached to the base 4 and supporting the outer circumferential surface of the outer fitting portion 5a, and a fourth bearing 9 attached to the outer circumferential surface of the inner fitting portion 5b and supporting the planetary carrier 3e.

[0025] The rotor 2b is disposed adjacent to the planetary gear 3b. With the above configuration, heat from the rotor 2b can be dissipated by convection generated by the planetary gear 3b, further suppressing permanent demagnetization of the permanent magnets 2b1 due to heat. The rotor 2b has an annular back plate 2b2 connected to the motor shaft 2c so as to rotate integrally with the motor shaft 2c, and the plurality of permanent magnets 2b1 that rotate integrally with the back plate 2b2. The plurality of permanent magnets 2b1 are disposed on one axial side of the back plate 2b2, and the planetary gear 3b is disposed on the other axial side of the back plate 2b2.

[0026] As shown in FIG. 4 , the planetary carrier 3e may have vanes 3e1 that generate convection within the space S (see FIG. 1 ) that is surrounded by the rotor 2b (back plate 2b2), motor shaft 2c, second bearing 7, fourth bearing 9, output section 5, third bearing 8, and base section 4 (first internal gear member 4b) and accommodates the planetary carrier 3e. The number, arrangement, and structure of the vanes 3e1 can be set as appropriate. With this configuration, heat can be dissipated from the rotor 2b by the convection generated by the vanes 3e1 in addition to the convection generated by the planetary gears 3b, thereby further suppressing permanent demagnetization of the permanent magnets 2b1. Note that the rotation direction of the motor shaft 2c, shown in white in FIG. 4 , is clockwise when viewed from one axial direction, but is not limited to this and may be the opposite direction. In addition, although the blade 3e1 is depicted on the other axial side of the planetary carrier 3e in FIG. 4, this is not limiting, and the blade 3e1 may be provided on the other axial side of the planetary carrier 3e, or on the outer peripheral end surface of the planetary carrier 3e.

[0027] The geared motor 1 has a stator yoke 2d that rotates integrally with the motor shaft 2c. According to the above configuration, the stator yoke 2d is separate from the coil 2a1 and rotates integrally with the permanent magnet 2b1, thereby suppressing iron loss.

[0028] The stator yoke 2d is provided on the axially opposite side of the rotor 2b from the stator 2a. With the above configuration, heat from the coil 2a1 can be dissipated by convection within the motor section 2 generated by the rotor 2b, thereby improving the energy efficiency of the motor section 2.

[0029] The stator 2a is an air-core type in which the inside of the plurality of coils 2a1 is hollow. This configuration allows the geared motor 1 to be lightweight. It also promotes convection within the motor section 2, suppressing temperature increases in the coils 2a1 and permanent magnets 2b1. The stator 2a is not limited to an air-core type, and may be configured to have a magnetic core 2a3 made of a ferromagnetic material, as shown by the two-dot chain line in Figure 1. This configuration allows the output of the motor section 2 to be easily improved. The stator 2a may be configured such that the inside of the plurality of coils 2a1 is filled with insulating material 2a2.

[0030] The geared motor 1 has a labyrinth structure 10 that seals the boundary between the motor section 2 and the reduction section 3. This configuration prevents lubricant in the reduction section 3 from penetrating into the motor section 2. The labyrinth structure 10 is preferably configured by an annular protrusion 10a that is provided on one of the rotor 2b and the base 4, extends continuously in the circumferential direction, and protrudes in the axial direction, and an annular recess 10b that is provided on the other of the rotor 2b and the base 4, and into which the annular protrusion 10a is inserted. It is even more preferable to provide the annular protrusion 10a on the rotor 2b and the annular recess 10b on the base 4, as in this embodiment.

[0031] The reduction gear unit 3 has a plurality of planetary gears 3b, and a planetary carrier 3e rotates coaxially with the motor shaft 2c while rotatably holding the plurality of planetary gears 3b. The planetary carrier 3e has an inner peripheral surface on which a second bearing 7 is mounted, and a bearing portion 3e2 that rotatably holds the plurality of planetary gears 3b around their respective rotation axes P. The bearing portion 3e2 is constituted by planetary gear bearings 11, the number of which corresponds to the number of the planetary gears 3b.

[0032] The stator yoke 2d connected to the motor shaft 2c, the bearing 6 attached to the motor shaft 2c, the rotor 2b (back plate 2b2) connected to the motor shaft 2c, the sun gear 3a connected to the motor shaft 2c, and the second bearing 7 attached to the motor shaft 2c are arranged in this order toward the other axial direction. The second bearing 7 attached to the inner peripheral surface of the planet carrier 3e and the fourth bearing 9 attached to the inner peripheral surface of the planet carrier 3e are arranged in this order toward the other axial direction. The first gear portion 3b1 of the planet gear 3b, the bearing portion 3e2 of the planet carrier 3e, and the second gear portion 3b2 of the planet gear 3b are arranged in this order toward the other axial direction. The stator 2a, which is part of the base 4, the second internal gear 3d, which is part of the base 4, and the third bearing 8 attached to the base 4 are arranged in this order toward the other axial direction.

[0033] The configurations of the motor section 2 and the speed reducer section 3 in this embodiment will be described in more detail below, but the configuration of the geared motor 1 is not limited to this.

[0034] The base 4 has a housing 4a, a stator 2a fixed to the housing 4a, and a first internal gear member 4b having a first internal gear 3c and fixed to the housing 4a. The housing 4a is formed by integrally assembling a cylindrical first housing part 4a1 and an annular second housing part 4a2. Movement of the stator 2a toward one axial direction is restricted by the second housing part 4a2, movement of the third bearing 8 toward the other axial direction is restricted by the first housing part 4a1, and movement of the first internal gear member 4b toward one axial direction is restricted by the stator 2a and movement of the first axial direction is restricted by the third bearing 8.

[0035] The base 4 has a stator insertion tool 4c that is inserted radially into the stator 2a through the first housing part 4a1 to position the stator 2a in the circumferential direction relative to the housing 4a. The stator insertion tool 4c is formed by a bolt. The first internal gear 3c is provided integrally with the first internal gear member 4b. The base 4 has a first internal gear insertion tool 4d that is inserted radially into the first internal gear member 4b through the first housing part 4a1 to position the first internal gear 3c in the circumferential direction relative to the housing 4a. The first internal gear insertion tool 4d is formed by a bolt.

[0036] Each coil 2a1 is made of a wire wound around an axis extending in the axial direction. Each permanent magnet 2b1 has a magnetization direction extending in the axial direction. The multiple permanent magnets 2b1 are arranged so that the direction of their magnetic fields alternates in the circumferential direction.

[0037] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and the above-described embodiments can be modified in various ways without departing from the gist of the present invention.

[0038] REFERENCE SIGNS LIST 1 geared motor 2 motor section 2a stator 2a1 coil 2a2 insulating material 2a3 magnetic core 2b rotor 2b1 permanent magnet 2b2 back plate 2c motor shaft 2d stator yoke 3 reduction section 3a sun gear 3b planetary gear 3b1 first gear section 3b2 second gear section 3c first internal gear 3d second internal gear 3e planet carrier 3e1 blade 3e2 bearing section 4 base 4a housing 4a1 first housing part 4a2 second housing part 4b first internal gear member 4c stator insert 4d first internal gear insert 5 output section 5a outer fitting section 5b inner fitting section 5c connecting section 6 bearing 7 second bearing 8 third bearing 9 fourth bearing 10 Labyrinth structure 10a Annular convex portion 10b Annular concave portion 11 Planetary gear bearing O Central axis P Rotation axis S Space

Claims

1. A geared motor comprising an axial gap motor section and a planetary gear reduction section, having a base and an output section that rotates relative to the base, wherein the motor section has a stator that is part of the base, a rotor, and a motor shaft that rotates integrally with the rotor, wherein the reduction section has a sun gear that rotates integrally with the motor shaft, a planetary gear having a first gear section that meshes with the sun gear and a second gear section that rotates integrally with the first gear section, a first internal gear that is part of the base and meshes with the first gear section of the planetary gear, and a second internal gear that constitutes the output section and meshes with the second gear section of the planetary gear, wherein the rotor has a plurality of permanent magnets arranged circumferentially, and the stator has a plurality of coils arranged circumferentially and an insulating material that is integrally molded to connect the plurality of coils together, and wherein the geared motor has a bearing attached to the inner peripheral edge of the stator to support the motor shaft.

2. A geared motor according to claim 1, wherein the reduction section has a planetary carrier, and a second bearing attached to the planetary carrier to support the motor shaft.

3. A geared motor as described in claim 2, wherein the output section has an outer fitting section, an inner fitting section provided radially inward of the outer fitting section, and a connecting section that integrally connects the outer fitting section to the inner fitting section, the second internal gear is provided integrally with the inner peripheral surface of the outer fitting section, a third bearing attached to the base and supporting the outer peripheral surface of the outer fitting section, and a fourth bearing attached to the outer peripheral surface of the inner fitting section and supporting the planetary carrier.

4. The geared motor according to claim 1, wherein the rotor is disposed adjacent to the planetary gear.

5. A geared motor according to claim 1, further comprising a stator yoke that rotates integrally with the motor shaft.

6. A geared motor according to claim 5, wherein the stator yoke is provided on the opposite side of the rotor from the stator in the axial direction.

7. The geared motor according to claim 1, wherein the stator is an air-core type.

8. The geared motor according to claim 1, wherein the stator has a magnetic core made of a ferromagnetic material.

9. The geared motor according to claim 1, having a labyrinth structure that seals the boundary between the motor section and the reduction section.

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