Motor with speed reducer

Abstract

To contrive radial miniaturization of a motor with a speed reducer.SOLUTION: A motor 10 with a speed reducer comprises: a rotor 22 in which a magnet 32 is fixed to the radially outer surface of a ring gear 60; a stator 20; a first planetary gear 62; a first sun gear 66; a first carrier 64; a second planetary gear 68; a second sun gear 72; and a second carried 70. The motor 10 with the speed reducer further comprises an output shaft 12 which is rotated by receiving transmission of the rotational force of the second carrier 70.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] The following Patent Document 1 discloses a motor with a reducer in which a unit such as a reducer is disposed. The motor with a reducer described in this document includes a rotor that is rotatably supported, and a unit such as a reducer disposed radially inside the rotor. The rotation of the rotor is reduced in speed by the reducer and transmitted to an output shaft. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6278432 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, the configuration of the motor with a reducer described in the above Patent Document 1 aims to reduce the size of the motor with a reducer in the axial direction by disposing units such as the reducer on the radial inside of the rotor. However, this configuration leaves room for improvement in terms of reducing the size of the motor with a reducer in the radial direction.

[0005] In consideration of the above, an object of the present disclosure is to provide a motor with a reducer that can be made smaller in size in the radial direction. [Means for solving the problem]

[0006] A motor with a reducer that solves the above problem includes a ring gear (60) that is formed in an annular shape and has a plurality of first internal teeth (60A) and a plurality of second internal teeth (60B) formed on a radially inner surface thereof, a rotor (22) in which one of a magnet (32) and a coil (28) is fixed to a radially outer surface of the ring gear, a stator (20) including the other of the magnet and the coil that is disposed opposite one of the magnet and the coil, a first planetary gear (62) that is disposed radially inside the rotor and meshes with the first internal teeth, a first sun gear (66) that is disposed radially inside the first planetary gear and meshes with the first planetary gear, and a stator (20) that is disposed radially inside the rotor. the rotor is provided with a first carrier (64) that is disposed radially inward of the rotor and on one axial side of the first planetary gear and that meshes with the second internal teeth; a second sun gear (72) that is disposed radially inward of the second planetary gear, engages with the first sun gear in a state in which it is unable to rotate relative to the first sun gear, and meshes with the second planetary gear; a second carrier (70) that is disposed radially inward of the rotor, supports the second planetary gear, and rotates as the second planetary gear revolves around the second sun gear; and an output shaft (12) that rotates as a result of the transmission of the rotational force of the second carrier.

[0007] With this configuration, the motor with a reducer can be made smaller in the radial direction. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view showing a motor with a reducer according to a first embodiment. [Diagram 2] 2 is a cross-sectional perspective view showing the motor with a reducer taken along line 2-2 shown in FIG. 1. [Diagram 3] 2 is a side cross-sectional view showing a cross section of the gear-equipped motor shown in FIG. 1 taken along the axial direction. [Figure 4] 2 is an exploded perspective view showing the gear-equipped motor shown in FIG. 1; [Diagram 5] FIG. 2 is an exploded perspective view showing the stator. [Figure 6] FIG. 2 is an exploded perspective view showing the reducer. [Figure 7] FIG. 2 is an exploded perspective view showing a magnet and a magnet covering member. [Figure 8] 5 is a side cross-sectional view corresponding to FIG. 3 and showing a motor with a reducer according to a second embodiment. FIG. [Figure 9] 10 is a side cross-sectional view corresponding to FIG. 3 and showing a motor with a reducer according to a third embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] (First embodiment) A reduction geared motor 10 according to the first embodiment will be described with reference to Figures 1 to 7. Note that the directions of arrows Z, R, and C shown appropriately in the figures respectively indicate one side in the rotational axial direction, the outer side in the rotational radial direction, and one side in the rotational circumferential direction of the output shaft 12. In the following description, when the axial direction, radial direction, or circumferential direction is simply indicated, it refers to the rotational axial direction, rotational radial direction, and rotational circumferential direction of the output shaft 12 unless otherwise specified.

[0010] 1 to 4, the reducer-equipped motor 10 of this embodiment is a three-phase, eight-pole, twelve-slot reducer-equipped motor with a built-in reducer 14. This reducer-equipped motor 10 includes a motor case 16 and a motor cover 18, a stator 20, a rotor 22, and a reducer 14 that reduces the rotation speed of the rotor 22, all of which are disposed within the motor case 16, and an output shaft 12 that protrudes from the motor cover 18. Note that only a cross-sectional portion is shown in FIG. 3.

[0011] 2, 3, and 5, the motor case 16 is formed in a cylindrical shape with a bottom that is open on one axial side and closed on the other axial side. The motor case 16 includes a bottom wall portion 16A formed in a disk shape and a side wall portion 16B that bends and extends from a radially outer end of the bottom wall portion 16A toward one axial side.

[0012] As shown in Figs. 2, 3 and 4, the motor cover 18 has a lid portion 18A formed in a disk shape. An insertion hole 18B into which the output shaft 12 described later is inserted is formed in the radial center of the lid portion 18A. The motor cover 18 also has an annular first flange portion 18C protruding from the edge of the insertion hole 18B toward one axial side. A bearing 19 supporting the output shaft 12 is fixed to the inner periphery of the first flange portion 18C by press-fitting or the like. With the output shaft 12 inserted into the insertion hole 18B, the motor cover 18 is attached to the motor case 16, so that the open end side (one axial side) of the motor case 16 is closed by the lid portion 18A with the output shaft 12 protruding from the motor cover 18 toward one axial side. As shown in Figures 2 and 3, the motor cover 18 has an annular second flange portion 18D that protrudes from the radial middle portion of the cover portion 18A on the other axial side toward the other axial side. A sealed bearing 21 that supports a ring gear 60 that constitutes a part of the reducer 14 described later is fixed to the inner peripheral portion of this second flange portion 18D by press fitting or the like.

[0013] As shown in Fig. 4, the stator 20 is fixed to a radially inner surface of the side wall portion 16B of the motor case 16. As shown in Fig. 4 and Fig. 5, the stator 20 includes a stator core 24 formed in an annular shape, and a plurality of coil bodies 26 fixed to an inner circumferential surface of the stator core 24. As shown in Fig. 5, in this embodiment, twelve coil bodies 26 are arranged side by side in the circumferential direction.

[0014] Here, the coil body 26 includes a coil 28 formed by winding a conductor wire, and an insulator 30 having a locking portion 30A that holds the shape of the coil 28 and is locked to the stator core 24. The conductor wire constituting the coil 28 is a wire assembly formed by bundling conductive wires. The resistance between the bundled wires is greater than the resistance of the wires themselves. This reduces eddy current loss. The terminals of the coil 28 of each coil body 26 are connected to a bus bar 31. In this embodiment, as an example, the coil 28 of each coil body 26 is connected in a star connection via the bus bar 31. In this embodiment, a teeth-less structure is formed in which a part of the stator core 24 is not disposed inside the coil 28.

[0015] As shown in Figs. 4 and 7, the rotor 22 is configured by attaching an annular magnet 32 ​​to the outer peripheral surface of a ring gear 60 that constitutes a part of the reducer 14 described later. As shown in Fig. 7, the magnet 32 ​​of this embodiment is a magnet with eight poles of polar anisotropic orientation in which N poles and S poles are alternately arranged in the circumferential direction. In Fig. 7, the direction of magnetic flux in some of the magnets 32 is shown typically by an arrow W. The magnet 32 ​​may be a magnet with other orientations such as a Halbach orientation. The magnet 32 ​​of this embodiment is formed using a magnetic compound with a coercive force Hc of 400 kA / m or more and a residual magnetic flux density Br of 1.0 T or more. As an example, the magnet 32 ​​of this embodiment is made of NdFe 11 TiN, Nd2Fe 14 B, SmFe 17 It is formed using magnetic compounds such as N3 and FeNi.

[0016] Here, in the magnet 32 ​​of this embodiment, the orientation of the magnetic flux in the magnet 32 ​​is set so that the magnetic flux density measured along the circumferential direction on the outer peripheral surface 32A, which is the radially outer surface, is a peak value at the magnetic pole center of the N pole and the S pole. In addition, in the magnet 32 ​​of this embodiment, the orientation of the magnetic flux in the magnet 32 ​​is set so that the magnetic flux density measured along the circumferential direction on the inner peripheral surface 32B, which is the radially inner surface, is approximately zero at each position in the circumferential direction. As a result, the ring gear 60 to which the magnet 32 ​​is fixed is not a part of the magnetic circuit, which is a magnetic path. The outer peripheral surface 32A, the surface on one axial side, and the surface on the other axial side of the magnet 32 ​​attached to the outer peripheral surface of the ring gear 60 are each covered with a magnet covering member 33.

[0017] 6, the reducer 14 includes a cylindrical ring gear 60 that constitutes a part of the rotor 22. The reducer 14 also includes a first planetary gear 62, a first carrier 64, and a first sun gear 66 that are disposed on the other axial side inside the ring gear 60. The reducer 14 also includes a second planetary gear 68, a second carrier 70, and a second sun gear 72 that are disposed on one axial side inside the ring gear 60.

[0018] As shown in FIG. 2, FIG. 3, and FIG. 6, the ring gear 60 is formed in a cylindrical shape using a metal material. In this embodiment, each component constituting the reducer 14 is made of metal. A plurality of first internal teeth 60A are formed along the circumferential direction on the radially inner surface of the ring gear 60 on the other axial side. A plurality of second internal teeth 60B are formed along the circumferential direction on the radially inner surface of the ring gear 60 on one axial side. Here, in this embodiment, the inner diameter of the portion where the first internal teeth 60A are formed on the inner periphery of the ring gear 60 is larger than the inner diameter of the portion where the second internal teeth 60B are formed. In addition, a reduced diameter portion 60C protruding toward the radially inner side is formed at the boundary between the portion where the first internal teeth 60A are formed and the portion where the second internal teeth 60B are formed on the inner periphery of the ring gear 60. Furthermore, three stepped portions having height differences in the radial direction are formed on the outer periphery of the ring gear 60. The three steps are called the first step 60D, the second step 60E, and the third step 60F in order from one axial side. In this embodiment, the outer diameter of the portion between the second step 60E and the first step 60D in the outer periphery of the ring gear 60 is larger than the outer diameter of the portion on one axial side of the first step 60D. In addition, the outer diameter of the portion between the third step 60F and the second step 60E in the outer periphery of the ring gear 60 is larger than the outer diameter of the portion between the second step 60E and the first step 60D. In addition, the outer diameter of the portion on the other axial side of the third step 60F in the outer periphery of the ring gear 60 is larger than the outer diameter of the portion between the third step 60F and the second step 60E. In addition, the second step 60E is formed at the same axial position as the reduced diameter portion 60C. The magnet 32 ​​is fixed to the outer circumferential surface of the ring gear 60 with the inner circumferential end on the other axial direction of the magnet 32 ​​locked to the second step portion 60E. A portion of the ring gear 60 on one axial side of the first step portion 60D, which is the end portion on one axial side of the ring gear 60, is supported by a first seal bearing 21 fixed to the motor cover 18. A seal bearing 21 is fixed by press fitting or the like to an inner circumferential portion of a portion of the ring gear 60 on the other axial side of the third step portion 60F, which is the end portion on the other axial direction of the ring gear 60.

[0019] The first planetary gears 62 are disposed radially inside a portion on the other axial side of the ring gear 60. In this embodiment, three first planetary gears 62 are disposed at equal intervals along the circumferential direction. The three first planetary gears 62 are each meshed with a first internal tooth 60A of the ring gear 60.

[0020] The first carrier 64 includes a base plate portion 64A formed in a disk shape, and three shaft portions 64B that protrude from the base plate portion 64A toward one axial side and are arranged at equal intervals in the circumferential direction. The three shaft portions 64B rotatably support the three first planetary gears 62, respectively. The three first planetary gears 62 are arranged close to the reduced diameter portion 60C of the ring gear 60, so that the movement of the three first planetary gears 62 in a direction to come out of the shaft portion 64B is restricted. A circular opening 64C is formed at the axial center of the base plate portion 64A, and a bearing 76 that supports the end portion of the shaft member 74 on the other axial side, which will be described later, is fixed to the inner periphery of the opening 64C by press-fitting or the like. In this embodiment, the base plate portion 64A is fixed to the bottom wall portion 16A of the motor case 16. Furthermore, an inner race of the seal bearing 21 is engaged with the outer periphery of the base plate portion 64A of the first carrier 64.

[0021] The first sun gear 66 is disposed radially inside the three first planetary gears 62 and meshes with these three first planetary gears 62. The first sun gear 66 is fixed by press fitting or the like to a cylindrical shaft member 74 that is disposed coaxially with the output shaft 12. In this embodiment, the module and pitch circle diameter of the first sun gear 66 are set to be larger than the module and pitch circle diameter of a second sun gear 72, which will be described later.

[0022] The second planetary gears 68 are disposed radially inside one axial side portion of the ring gear 60. In this embodiment, three second planetary gears 68 are disposed at equal intervals along the circumferential direction. Moreover, the three second planetary gears 68 are meshed with the second internal teeth 60B of the ring gear 60, respectively. Furthermore, in this embodiment, the three second planetary gears 68 face each other in the axial direction via the first planetary gear 62 and the reduced diameter portion 60C of the ring gear 60.

[0023] The second carrier 70 includes a base plate portion 70A formed in a disk shape and three shaft portions 70B that protrude from the base plate portion 70A toward the other axial side and are arranged at equal intervals in the circumferential direction. The three shaft portions 70B rotatably support the three second planetary gears 68. The three second planetary gears 68 are arranged close to the reduced diameter portion 60C of the ring gear 60, so that the movement of the three second planetary gears 68 in the direction of coming out of the shaft portion 70B is restricted. In addition, a recess 70C that is open on the other axial side is formed in the axial center of the base plate portion 70A, and a bearing 76 that supports the end of the shaft member 74 on one axial side described above is fixed to the inner peripheral portion of this recess 70C by press-fitting or the like. In addition, the output shaft 12 protrudes toward one axial side from the center of the radial direction of the base plate portion 70A. That is, the second carrier 70 is configured integrally with the output shaft 12.

[0024] The second sun gear 72 is disposed radially inward of the three second planetary gears 68 and is in mesh with these three second planetary gears 68. The second sun gear 72 is fixed to the shaft member 74 by press fitting or the like. As a result, the second sun gear 72, the first sun gear 66 and the shaft member 74 form a sun gear assembly 78, and the second sun gear 72 is capable of rotating integrally with the first sun gear 66.

[0025] (Actions and Effects of the Present Embodiment) Next, the operation and effects of this embodiment will be described.

[0026] According to the geared motor 10 of the present embodiment described above, the current supply to the coils 28 of the coil bodies 26 constituting the stator 20 is switched by a control circuit (not shown), whereby the stator 20 generates a rotating magnetic field. This causes the rotor 22 to rotate. In other words, the ring gear 60 rotates together with the magnet 32.

[0027] When the ring gear 60 rotates, the three first planetary gears 62 that mesh with the first internal teeth 60A of the ring gear 60 also rotate.

[0028] When the three first planetary gears 62 rotate, the first sun gear 66 that meshes with the three first planetary gears 62 rotates together with the second sun gear 72 .

[0029] When the second sun gear 72 rotates, the three second planetary gears 68 meshing with the second sun gear 72 also rotate. Here, the three second planetary gears 68 also mesh with the ring gear 60. Therefore, the three second planetary gears 68 revolve around the second sun gear 72 at a rotation speed corresponding to the rotation speed of the second sun gear 72 and the rotation speed of the ring gear 60. As a result, the second carrier 70 supporting the three second planetary gears 68 rotates together with the output shaft 12 at a rotation speed corresponding to the revolution of the three second planetary gears 68.

[0030] Here, in the motor 10 with a reducer of this embodiment, the ring gear 60 constituting a part of the reducer 14 constitutes a part of the rotor 22. That is, the ring gear 60 constituting a part of the reducer 14 serves as a rotor core on which the magnet 32 ​​is supported. This allows the number of parts stacked in the radial direction in the motor 10 with a reducer to be reduced compared to a case in which the rotor core on which the magnet 32 ​​is supported is provided as a separate member from the ring gear 60. This allows the motor 10 with a reducer to be made smaller in the radial direction. Also, in this embodiment, a teethless structure is provided in which a part of the stator core 24 is not disposed inside the coil 28, so that the stator 20 can be made smaller in the radial direction. This allows the motor 10 with a reducer to be made smaller in the radial direction.

[0031] Furthermore, in the geared motor 10 of the present embodiment, the second carrier 70 is configured as one piece with the output shaft 12. This makes it possible to reduce the number of parts that constitute the geared motor 10, compared to a configuration in which the second carrier 70 and the output shaft 12 are separate.

[0032] In the motor 10 with a reducer of this embodiment, the first sun gear 66 and the second sun gear 72 are fixed to the shaft member 74 by press-fitting or the like to form a sun gear assembly 78. This allows the sun gear assembly 78 to be handled as one component in the assembly process of the motor 10 with a reducer, making it easier to assemble the motor 10 with a reducer. In addition, the module and pitch circle diameter of the first sun gear 66 are set to be larger than the module and pitch circle diameter of the second sun gear 72, making it possible to realize an assembly procedure of one-way assembly in which the sun gear assembly 78 is inserted into the inner peripheral portion of the ring gear 60 from the other axial side. Depending on the reduction ratio required for the reducer 14, the module and pitch circle diameter of the second sun gear 72 may be set to be larger than the module and pitch circle diameter of the first sun gear 66. In this case, a one-way assembly procedure can be realized in which the sun gear assembly 78 is inserted into the inner peripheral portion of the ring gear 60 from one axial side.

[0033] Furthermore, in the motor 10 with a reducer of this embodiment, the space on the radial inside of the ring gear 60 and the space on the radial outside of the ring gear 60 are configured to be separated via a pair of sealed bearings 21. This makes it possible to prevent lubricants such as grease in the space on the radial inside of the ring gear 60 and wear powder of the parts that make up the reducer 14 from penetrating into the space on the radial outside of the ring gear 60 in which the stator 20 and the like are arranged.

[0034] In addition, in the geared motor 10 of this embodiment, the ring gear 60 to which the magnet 32 ​​is fixed is configured not to be part of the magnetic circuit. This makes it possible to prevent wear powder and the like from the components that make up the gear reducer 14 from accumulating on the inner circumferential surface of the ring gear 60.

[0035] Furthermore, in the geared motor 10 of this embodiment, the magnet 32 ​​is fixed to the outer circumferential surface of the ring gear 60 while being engaged with the second stepped portion 60E, and as a result, the magnet 32 ​​and the stator 20 are disposed at a position radially opposed to the second sun gear 72, the second planetary gear 68, and the second carrier 70. This makes it possible to ensure a sufficient space for arranging the bus bar 31 on the other axial side of the stator 20, and allows the bus bar 31 and the stator 20 to be arranged overlapping in the axial direction.

[0036] Furthermore, the reducer 14 of the reducer-equipped motor 10 of this embodiment is a so-called compound planetary gear mechanism that is formed by all of the gears, namely, the ring gear 60, the first planetary gear 62, the first carrier 64, the first sun gear 66, the second planetary gear 68, the second carrier 70, and the second sun gear 72. This makes it possible to increase the reduction ratio of the reducer 14. In particular, in this embodiment, the first carrier 64 is fixed to the motor case 16, so that the reduction ratio of the reducer 14 can be particularly increased. Depending on the reduction ratio required for the reducer 14, the shaft member 74 of the sun gear assembly 78 may be fixed to the motor case 16, as in the reducer-equipped motor 80 of the second embodiment shown in FIG. 8. In the reducer-equipped motor 80 of the second embodiment, the members and parts corresponding to those of the reducer-equipped motor 10 of the first embodiment are denoted by the same reference numerals as those of those of the reducer-equipped motor 10 of the first embodiment.

[0037] In this embodiment, an example has been described in which the shaft member 74 of the sun gear assembly 78 is supported by a pair of bearings 76, but the shaft member 74 of the sun gear assembly 78 may be supported by a single bearing 76 as in a geared motor 82 according to a third embodiment shown in Fig. 9. With this configuration, the number of bearings 76 used in the geared motor 82 can be reduced compared to the geared motor 10 according to the first embodiment. In the geared motor 82 according to the third embodiment, members and parts corresponding to those of the geared motor 10 according to the first embodiment are denoted by the same reference numerals as those of the geared motor 10 according to the first embodiment.

[0038] In the above-described embodiments, the magnet 32 ​​is attached to the ring gear 60, but the present invention is not limited to this. For example, the ring gear 60 may be configured to have a plurality of coils and commutators attached thereto.

[0039] While one embodiment of the present disclosure has been described above, the present disclosure is not limited to the above, and it goes without saying that the present disclosure can be implemented in various other modified forms without departing from the spirit and scope of the present disclosure. [Explanation of symbols]

[0040] 10 motor with reduction gear, 12 output shaft, 20 stator, 21 sealed bearing, 22 rotor, 28 coil, 31 bus bar, 32 magnet, 60 ring gear, 60A first internal teeth, 60B second internal teeth, 62 first planetary gear, 64 first carrier, 66 first sun gear, 68 second planetary gear, 70 second carrier, 72 second sun gear, 74 shaft member, 76 bearing, 80 motor with reduction gear, 82 motor with reduction gear

Claims

1. a rotor (22) having a ring gear (60) formed in an annular shape and having a plurality of first internal teeth (60A) and a plurality of second internal teeth (60B) formed on a radially inner surface thereof, and one of a magnet (32) and a coil (28) fixed to a radially outer surface of the ring gear; a stator (20) including one of the magnet and the coil arranged to face the other of the magnet and the coil; a first planetary gear (62) disposed radially inside the rotor and meshing with the first internal teeth; a first sun gear (66) disposed radially inside the first planetary gear and meshing with the first planetary gear; a first carrier (64) disposed radially inside the rotor and supporting the first planetary gear; a second planetary gear (68) disposed radially inside the rotor and on one axial side of the first planetary gear, the second planetary gear meshing with the second internal teeth; a second sun gear (72) disposed radially inside the second planetary gear, engaged with the first sun gear in a state in which the second sun gear cannot rotate relative to the first sun gear, and meshing with the second planetary gear; a second carrier (70) disposed radially inside the rotor, supporting the second planetary gear, and rotating as the second planetary gear revolves around the second sun gear; an output shaft (12) that rotates by transmitting a rotational force of the second carrier; Equipped with A motor with a reduction gear (10, 80, 82) in which the orientation of the magnetic flux within the magnet is set so that the magnetic flux density at the outer circumferential surface of the magnet measured along the circumferential direction reaches its peak value at the magnetic pole centers of the N and S poles, and the orientation of the magnetic flux within the magnet is set so that the magnetic flux density at the inner circumferential surface of the magnet measured along the circumferential direction is zero at each position in the circumferential direction, and the ring gear is not part of a magnetic circuit, which is a magnetic path.

2. The motor with a reduction gear as described in claim 1, wherein the module and pitch circle diameter of one of the first sun gear and the second sun gear are set to be larger than the module and pitch circle diameter of the other of the first sun gear and the second sun gear.

3. A motor with a reduction gear as described in claim 1 or claim 2, wherein a space radially inside the ring gear and a space radially outside the ring gear are separated via a sealed bearing (21) that rotatably supports the ring gear.

4. The magnet is fixed to a radially outer surface of the ring gear, A motor with a reduction gear as described in any one of claims 1 to 3, wherein the coil and a bus bar (31) to which the terminal portion of the coil is connected are arranged in an axially overlapping state on the radially outer side of the ring gear.

5. The motor with a reducer according to any one of claims 1 to 4, wherein rotation of the first carrier is restricted.

6. The motor with a reducer according to any one of claims 1 to 4, wherein rotation of the first sun gear and the second sun gear is restricted.

7. A motor with a reduction gear as described in any one of claims 1 to 5, wherein the first sun gear and the second sun gear are rotatably supported by a single bearing (76) provided between the first sun gear and the second sun gear.

8. The motor with a reducer according to any one of claims 1 to 7, wherein the first sun gear and the second sun gear are fixed to a single shaft member (74).

9. The motor with a reducer according to any one of claims 1 to 8, wherein the output shaft and the second carrier are integrated.

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