JP7617813B2 - Gear motor - Google Patents

Description

This disclosure relates to a gear motor.

Patent document 1 discloses a gear motor equipped with a motor and a reducer.

JP 2019-97364 A

Gear motors may require some ingenuity in dissipating heat generated in the gear motor to the outside. The inventors of the present application recognized that there is room for improvement in the technology of Patent Document 1 in terms of obtaining good heat dissipation characteristics in relation to the rotating shaft of the gear motor.

One of the objectives of this disclosure is to provide a gear motor that can achieve good heat extraction characteristics.

The gear motor of the present disclosure is a gear motor equipped with a motor and a reducer, and is equipped with a rotating shaft constituted by at least one of the motor shaft of the motor and the input shaft of the reducer, and the rotating shaft is equipped with a hollow portion penetrating in the axial direction, a resin portion constituted by a resin-based material, a metal portion constituted by a metal-based material, and an airflow generating portion provided on the inner circumference of the resin portion constituting the hollow portion and generating an airflow within the hollow portion by the rotation of the rotating shaft.

The gear motor disclosed herein can provide good heat dissipation characteristics.

1 is a side cross-sectional view of a gear motor according to a first embodiment. FIG. FIG. 2 is a side cross-sectional view of the rotating shaft of the first embodiment. FIG. 2 is a perspective cross-sectional view of a rotating shaft according to the first embodiment. 5A to 5C are explanatory diagrams relating to the operation of the gear motor of the first embodiment. FIG. 11 is a perspective cross-sectional view of a rotating shaft according to a second embodiment. FIG. 11 is a side cross-sectional view illustrating a schematic view of a portion of a rotating shaft according to a third embodiment. FIG. 7 is a view taken along the arrow A in FIG. 6 . FIG. 8A is a diagram showing a state in which the rotating shaft rotates in the forward direction, and FIG. 8B is a diagram showing a state in which the rotating shaft rotates in the reverse direction. FIG. 13 is a side cross-sectional view illustrating a schematic view of a portion of a rotating shaft according to a fourth embodiment.

The following describes the embodiments. Identical components are given the same reference numerals, and duplicate explanations will be omitted. In each drawing, components are omitted, enlarged, or reduced as appropriate for the sake of convenience. The drawings should be viewed according to the orientation of the reference numerals.

(First embodiment) See FIG. 1. A gear motor 10 connects a first mating member 12 and a second mating member 14. The gear motor 10 can rotate the second mating member 14 relative to the first mating member 12. For example, the first mating member 12 is a base that supports the gear motor 10, and the second mating member 14 is part of a driven machine such as a conveyor.

The gear motor 10 includes a motor 18 having a motor shaft 16, a reducer 22 having an input shaft 20 to which the rotation of the motor shaft 16 is input, and a rotating shaft 24 composed of at least one of the motor shaft 16 and the input shaft 20. The rotating shaft 24 of this embodiment is integrally composed of both the motor shaft 16 and the input shaft 20. The gear motor 10 of this embodiment is characterized by the rotating shaft 24, but the peripheral structure will be explained first. Hereinafter, the direction along the rotation center line CL1 of the rotating shaft 24 will be referred to as the axial direction X, and the circumferential direction and radial direction of the circle centered on the rotation center line CL1 will be referred to as the "circumferential direction" and the "radial direction", respectively. In addition, the side from the motor 18 toward the reducer 22 in the axial direction X (left side in FIG. 1) will be referred to as the load side, and the opposite side of the axial direction X (right side in FIG. 1) will be referred to as the anti-load side.

The motor 18 is, for example, a permanent magnet motor. Specific examples of the motor 18 are not particularly limited, and may be an induction motor, a reluctance motor, a coreless motor, etc. In addition to the motor shaft 16, the motor 18 includes a stator 26 and a rotor 28 that generate a rotating magnetic field, and a motor housing 30 that houses the stator 26 and the rotor 28. The stator 26 is fixed to the motor housing 30. The rotor 28 is fixed to the motor shaft 16, and the motor shaft 16 rotates integrally with the rotor 28. In this embodiment, the rotor 28 is formed of a permanent magnet.

In addition to the input shaft 20, the reducer 22 includes a reduction mechanism 32 that reduces the rotation of the input shaft 20, an output member 34 that outputs the reduced output rotation from the reduction mechanism 32, a reduction housing 36 that houses the reduction mechanism 32, and a number of bearings 38A, 38B, and 38C that are arranged on the outer periphery of the input shaft 20.

The reduction mechanism 32 operates by driving the driven gear 40 by the input shaft 20. When the reduction mechanism 32 operates, the output rotation of the reduction mechanism 32 is taken out from the output member 34. The reduction mechanism 32 of this embodiment is a flexible mesh type gear mechanism that rotates one of the external gear 42 and the internal gears 44A, 44B (here, the external gear 42) by flexibly deforming the flexible gear as the driven gear 40. The flexible gear that becomes the driven gear 40 in this embodiment is the external gear 42, but it may be the internal gears 44A, 44B. The output member 34 can take out the rotation component as the output rotation by synchronizing with the rotation component of one of the external gear 42 and the internal gears 44A, 44B. The reduction mechanism 32 of this embodiment is a cylindrical flexible mesh type gear mechanism using multiple internal gears 44A, 44B. The operating principle of this type of reduction mechanism 32 is well known, so a description thereof will be omitted here.

The input shaft 20 is equipped with a gear drive unit 46 that drives the driven gear 40 of the reduction mechanism 32 by its rotation. The gear drive unit 46 used in the flexible meshing gear mechanism has an elliptical shape in a cross section perpendicular to the axial direction. The "ellipse" here is not limited to a strict geometric ellipse, but also includes an approximate ellipse. The gear drive unit 46 has a degree of rigidity that allows the flexible gear to bend. The gear drive unit 46 functions as a vibrator that, by its rotation, flexibly deforms the flexible gear to form an elliptical shape that matches the gear drive unit 46.

The reduction mechanism 32 includes an external gear 42 arranged on the outer periphery of the input shaft 20, and internal gears 44A and 44B that mesh with the external gear 42. The external gear 42 is rotatably supported on the input shaft 20 via a gear bearing 38A arranged between the input shaft 20 and a gear drive unit 46. The internal gears 44A and 44B include a first internal gear 44A whose relative rotation with respect to the reduction gear housing 36 is restricted, and a second internal gear 44B that can rotate relative to the reduction gear housing 36. The first internal gear 44A is arranged on the anti-load side, and the second internal gear 44B is arranged on the load side. The first internal gear 44A has a number of internal teeth (e.g., 102) different from the number of external teeth (e.g., 100) of the external gear 42, and the second internal gear 44B has a number of internal teeth equal to the number of external teeth of the external gear 42.

The reducer housing 36 is connected to the motor housing 30 using bolts or the like. In this embodiment, the reducer housing 36 includes a first housing member 48 that also serves as the first internal gear 44A, and a second housing member 50 that is disposed radially outward from the second internal gear 44B. The first housing member 48 and the second housing member 50 are connected to each other using screws or the like. A main bearing 52 is disposed between the reducer housing 36 and the second internal gear 44B. The first mating member 12 is integrated with the reducer housing 36 using screws or the like.

The output member 34 in this embodiment is a carrier 54 that is disposed on the axial load side of the reduction mechanism 32. The carrier 54 has a through hole 54a that passes through the carrier 54 in the axial direction X. The carrier 54 is integrated with the second internal gear 44B, for example, by using a screw or the like. The second mating member 14 is integrated with the output member 34 by using a screw or the like.

The multiple bearings 38A, 38B, 38C include a gear bearing 38A arranged between the gear drive portion 46 of the input shaft 20 and the driven gear 40, and input bearings 38B, 38C spaced apart from the gear bearing 38A in the axial direction X. The input bearings 38B, 38C include a first input bearing 38B arranged between the reducer housing 36 and the input shaft 20, and a second input bearing 38C arranged between the carrier 54 and the input shaft 20.

The operation of the reducer 22 of the gear motor 10 described above will be explained. When rotation is input from the motor shaft 16 to the input shaft 20, the input shaft 20 rotates, and the reduction mechanism 32 operates. When the reduction mechanism 32 operates, the output rotation of the reduction mechanism 32, which is slower than the rotation of the input shaft 20, is taken out from the output member 34, and the output member 34 rotates. When the output member 34 rotates, the second mating member 14 rotates relative to the first mating member 12.

Refer to Figures 2 and 3. We will now move on to the explanation of the rotating shaft 24. As mentioned above, the rotating shaft 24 is composed of at least one of the motor shaft 16 and the input shaft 20. Here, "composed of at least one" means that it is composed of one or both of the motor shaft 16 and the input shaft 20. Here, "a rotating shaft composed of one" refers to a single rotating shaft composed of only one of the motor shaft 16 and the input shaft 20. Also, here, "a rotating shaft composed of both" includes two rotating shafts that are individually composed of the motor shaft 16 and the input shaft 20 and are connected to each other, in addition to a single rotating shaft that is integrally composed of both the motor shaft 16 and the input shaft 20 as in the embodiment.

The rotating shaft 24 includes a hollow portion 56 that passes through the rotating shaft 24 in the axial direction X, a rotor arrangement portion 58 in which the rotor 28 is arranged, and bearing arrangement portions 60A, 60B, and 60C in which the bearings 38A, 38B, and 38C are arranged.

The hollow portion 56 has an opening 62 that opens to the axial end of the rotating shaft 24. The opening 62 connects an axial space 64 on the axial outside of the rotating shaft 24 to an internal space 66 inside the hollow portion 56. The axial space 64 is connected to the external space itself outside the gear motor 10, or to an external space.

The rotor placement section 58 is provided on the outer periphery of the rotating shaft 24 at a location that will become the motor shaft 16. The rotor 28 is integrated into the rotor placement section 58 by insert molding, in which the rotor 28 is used as an insert part and injection molding is performed, or by bonding, fitting, etc.

The bearing arrangements 60A, 60B, and 60C are provided on the outer periphery of the rotating shaft 24 at a location that will become the input shaft 20. The bearing arrangements 60A, 60B, and 60C include the gear bearing arrangement 60A where the gear bearing 38A is arranged, and the input bearing arrangements 60B and 60C where the input bearings 38B and 38C are arranged. The gear bearing arrangement 60A is provided on the outer periphery of the gear drive section 46 of the input shaft 20. The input bearing arrangements 60B and 60C are provided on the outer periphery of the input shaft 20 at a position offset in the axial direction X from the gear drive section 46 of the input shaft 20. The input bearing arrangements 60B and 60C include a first input bearing arrangement 60B arranged on the load side, and a second input bearing arrangement 60C arranged on the anti-load side.

The rotating shaft 24 of this embodiment includes a shaft body portion 68 and an input shaft component portion 70 that constitutes the outer periphery of the input shaft 20. The shaft body portion 68 is continuous from the non-load side end to the load side end of the rotating shaft 24. In this embodiment, the shaft body portion 68 is provided with a rotor arrangement portion 58. The input shaft component portion 70 is arranged on the outer periphery of the shaft body portion 68 at a location that becomes the input shaft 20. The input shaft component portion 70 is provided with a plurality of bearing arrangement portions 60A, 60B, 60C.

The rotating shaft 24 has a resin portion 72 made of a resin material and a metal portion 74 made of a metal material. In FIG. 3, a dot pattern is applied to the metal portion 74.

The resin-based material constituting the resin portion 72 refers to a material that is primarily made of resin. The resins used here are, for example, general-purpose engineering plastics, special engineering plastics, etc. In the case of general-purpose engineering plastics, for example, polyamide (e.g., PA46), polyacetal, etc. are used. The resin-based material may be composed only of a resin that is the primary material, or may be composed of a composite material of a resin that is the primary material and another material. Examples of such composite materials include carbon fiber reinforced resin, glass fiber reinforced resin, etc.

The metallic material constituting the metal portion 74 refers to a material that is primarily made of metal. The metals used here are, for example, iron-based materials such as cast iron and steel, and aluminum-based materials such as aluminum alloys. The metallic material may be made only of the metal that is the primary material, or may be made of a composite material of the metal that is the primary material and another material. The composite material here is, for example, a fiber-reinforced metal.

The thermal conductivity [W/(m·K)] of the resin material constituting the resin portion 72 is smaller than the thermal conductivity of the metal material constituting the metal portion 74. To achieve this, for example, the resin portion 72 may be made of engineering plastic, and the metal portion 74 may be made of an iron-based material or an aluminum-based material.

The metal part 74 is a metal processed product that can be obtained by metal processing such as cutting and casting. The resin part 72 is a resin molded product that can be obtained by resin molding such as injection molding and 3D printing. In this embodiment, the metal part 74 and the resin part 72 are integrated by insert molding, in which injection molding is performed using the metal part 74 as an insert part. In addition, the method of integrating the metal part 74 and the resin part 72 is not limited to insert molding. For example, the metal part 74 and the resin part 72 that have been prepared in advance may be integrated by gluing, fitting, or the like. In addition, the metal part 74 and the resin part 72 may be integrated using hybrid 3D printing, which can simultaneously create a three-dimensional shape of metal and resin.

The resin portion 72 constitutes the shaft body portion 68 of the rotating shaft 24. The resin portion 72 constitutes the rotor arrangement portion 58, just like the shaft body portion 68. The resin portion 72 constitutes the parts of the rotating shaft 24 other than the metal portion 74.

The metal portion 74 constitutes the input shaft component 70 of the rotating shaft 24. The metal portion 74 constitutes at least the outer periphery of the gear drive portion 46, i.e., the gear bearing arrangement portion 60A. In this embodiment, the metal portion 74 also constitutes the outer periphery of the input bearing arrangement portions 60B and 60C. The metal portion 74 constitutes the outer periphery of the rotating shaft 24 in the axial range from the first input bearing arrangement portion 60B to the second input bearing arrangement portion 60C.

The metal portion 74 includes an outer cylindrical portion 76 that constitutes the input shaft component 70. The resin portion 72 includes an inner cylindrical portion 78 that is disposed inside the outer cylindrical portion 76. The outer cylindrical portion 76 includes a plurality of metal protrusions 80 that penetrate the inner cylindrical portion 78 in the radial direction. The hollow portion 56 is formed by the inner circumference of the shaft main body portion 68 that constitutes the resin portion 72 and the inner circumference of the metal protrusions 80 of the metal portion 74.

The rotating shaft 24 includes an airflow generating section 90 provided on the inner circumference of the resin portion 72 that constitutes the hollow portion 56. The airflow generating section 90 of this embodiment is provided integrally with the resin portion 72 as part of the same member as the resin portion 72. The airflow generating section 90 of this embodiment is integrally formed by injection molding from the same resin material as the resin portion 72. The airflow generating section 90 is also made of a resin material like the resin portion 72. The airflow generating section 90 of this embodiment is provided on the inner circumference of the motor shaft 16. More specifically, the airflow generating section 90 is provided on the inner circumference of the motor shaft 16 at a location that radially overlaps with at least a portion of the axial range of the rotor 28.

The airflow generating section 90 of this embodiment is a fin 92 extending in the axial direction X. Here, "extending in the axial direction X" is not limited to the case where the longitudinal direction of the fin 92 is parallel to the axial direction X, but may be any angle between the longitudinal direction of the fin 92 and the axial direction X that is less than 45 degrees. This angle is preferably 30 degrees or less. A plurality of airflow generating sections 90 of this embodiment are arranged at intervals in the circumferential direction. Figures 2 and 3 show cross sections of the rotating shaft 24 in different rotation phases. Also, Figure 2 shows only a part of the airflow generating section 90 of Figure 3, and Figure 3 shows the airflow generating section 90 in a schematic manner. The fin 92 of this embodiment is provided so as to protrude radially inward from the inner circumference of the hollow section 56.

The airflow generating unit 90 can generate an airflow in the hollow portion 56 by stirring the air in the hollow portion 56 by the rotation of the rotating shaft 24. The fins 92 in this embodiment are inclined with respect to the axial direction X so as to move toward one circumferential side Da (counterclockwise in the example of FIG. 3) as they move toward the load side. This allows the air to be pushed in different directions in the axial direction X depending on the rotation direction of the rotating shaft 24, thereby generating an airflow in the hollow portion 56 toward the axial direction X. For example, when the rotating shaft 24 rotates toward the other circumferential side Db (clockwise in the example of FIG. 3), the fins 92 push air toward the load side, thereby generating an airflow in the hollow portion 56 toward the load side. Also, when the rotating shaft 24 rotates toward one circumferential side Da, the fins 92 push air toward the anti-load side, thereby generating an airflow in the hollow portion 56 toward the anti-load side.

The inner diameter of the hollow portion 56 at the motor shaft 16 where the airflow generating portion 90 is provided is referred to as the inner diameter Ra. The inner diameter of the hollow portion 56 at the input shaft 20 is referred to as the inner diameter Rb. The inner diameter Rb of the input shaft 20 refers to, for example, the inner diameter of the hollow portion 56 at the location where the gear drive portion 46 of the input shaft 20 is located (the location where it radially overlaps with the external gear 42). The inner diameter here refers to the radius of the inscribed circle with the maximum diameter inscribed at the location in question, and is concentric with the rotation center line CL1 of the rotating shaft 24.

Refer to FIG. 1. The motor housing 30 and the reducer housing 36 are made of a resin-based material. In this embodiment, the first housing member 48 and the second housing member 50 of the reducer housing 36 are each made of a resin-based material. The resin-based material making up the motor housing 30 and the reducer housing 36 may be the same resin-based material as the resin portion 72 of the rotating shaft 24, or may be a different resin-based material from the resin portion 72. In addition, all or part of the first internal gear 44A, the second internal gear 44B, and the carrier 54 may be made of a resin-based material.

The operation and effect of the gear motor 10 described above will be described. See FIG. 4. When the rotating shaft 24 rotates, an airflow F is generated in the hollow portion 56 by the airflow generating portion 90 of the rotating shaft 24. In the hollow portion 56, an airflow F is generated toward at least the axial direction X. Here, it is assumed that the rotating shaft 24 rotates toward the other circumferential side Db (see FIG. 3) and generates an airflow F toward the load side in the hollow portion 56. In this case, when an airflow F is generated in the hollow portion 56, air in the axial space 64 is taken into the internal space 66 through the opening 62 of the rotating shaft 24. In this embodiment, air in the axial space 64 on the opposite side (anti-load side) to the flow direction of the airflow in the axial direction X (load side) is taken into the internal space 66. At the same time, air in the internal space 66 is blown out into the axial space 64. In this embodiment, air is blown out from the internal space 66 into the axial space 64 on the load side, which is the flow direction of the airflow in the axial direction X.

In addition, the second mating member 14 of this embodiment does not seal the internal space 66 of the rotating shaft 24, but opens the internal space 66 to the space around the second mating member 14 in the axial space 64. Therefore, while the rotating shaft 24 is rotating, air can continue to be blown from the internal space 66 to the axial space 64 on the load side.

(A) As described above, by blowing the air in the internal space 66 of the rotating shaft 24 into the axial space 64, it is possible to promote forced convection from the internal space 66 to the axial space 64. This allows the heat dissipated from the rotating shaft 24 into the internal space 66 to be released to the outside of the rotating shaft 24 (axial space 64), thereby enabling forced air cooling of the rotating shaft 24. As a result, the amount of heat dissipated from the rotating shaft 24 to the outside can be increased, resulting in good heat dissipation characteristics.

In addition, to achieve such forced air cooling of the rotating shaft 24, there is no need to install a dedicated fan in the gear motor 10, which simplifies the configuration of the gear motor 10.

The main modes of heat dissipation generated by the gear motor 10 can be classified into thermal conduction, radiation, and diffusion. Here, in the case of a metal gear motor whose main components are made of metal, the amount of heat dissipation by thermal conduction is large. The main components here refer to, for example, the rotor 28, stator 26, motor shaft 16, and motor housing 30 of the motor 18, as well as the input shaft 20, reduction mechanism 32, and reduction gear housing 36 of the reduction gear 22. In contrast, in the case of a hybrid gear motor whose main components are made of resin-based materials and metal-based materials, heat conduction is difficult in the resin-based materials, which have a lower thermal conductivity than the metal-based materials. For this reason, in the case of a hybrid gear motor, the proportion of heat dissipation by thermal conduction to the total heat dissipation is smaller than in a metal gear motor, and the proportion of heat dissipation by convection to the total heat dissipation tends to be larger.

According to this embodiment, the forced convection of air within the hollow portion 56 is promoted by generating an airflow within the hollow portion 56 using the airflow generating unit 90, so that the amount of heat dissipated by convection can be effectively increased. Even in cases where the amount of heat dissipated by thermal conduction is small, such as in a hybrid gear motor, the total amount of heat dissipated can be effectively increased by increasing the amount of heat dissipated by convection.

(B) The airflow generating section 90 is provided integrally with the resin part 72. Therefore, compared to a case where the airflow generating section 90 is provided on the inner circumference of the metal part 74, it is easy to mold the resin part 72 with the airflow generating section 90 having a complex shape by resin molding.

Furthermore, when the airflow generating unit 90 is provided on the inner circumference of the metal portion 74, metal processing such as cutting is required for the hollow portion 56 of the rotating shaft 24. It is difficult to provide a complex-shaped airflow generating unit 90 in such a location by metal processing, and this creates restrictions on the shape and dimensions that can be achieved. In this regard, according to the present embodiment, the resin portion 72 provided with the complex-shaped airflow generating unit 90 can be easily molded by resin molding, thereby easing the restrictions on the shape and dimensions that can be achieved.

(C) The motor housing 30 and the reducer housing 36 tend to be larger in volume than the components of the gear motor 10 that are placed inside them. By constructing the motor housing 30 and the reducer housing 36 from a resin-based material, it is possible to effectively reduce the weight compared to constructing them from a metal-based material. When the motor housing 30 and the reducer housing 36 are constructed from a resin-based material in this way, as described above, it becomes difficult to transfer heat by thermal conduction. Even in this case, by providing an airflow generating section 90 on the inner circumference of the hollow section 56 of the rotating shaft 24, it is possible to promote heat transfer by diffusion within the hollow section 56. As a result, it is possible to achieve both good heat removal characteristics and weight reduction.

(D) Consider the heat transfer path of the heat generated in the rotor 28, which is the heat source. As an example, a heat transfer path in which heat is transferred by thermal conduction in the order of the rotor 28 → the rotating shaft 24 → the reduction mechanism 32 → the reducer housing 36 → the first mating member 12 is considered. In addition, a heat transfer path in which heat is transferred by thermal conduction in the order of the rotor 28 → the rotating shaft 24 → the reduction mechanism 32 → the carrier 54 → the second mating member 14 is considered. Here, as described above, the thermal conductivity of the resin-based material is smaller than that of the metal-based material. Therefore, when both the metal-based material and the resin-based material are used for the rotating shaft 24, it is more difficult to remove heat through the heat transfer path by thermal conduction via the rotating shaft 24 than when only the metal-based material is used. Even in this case, by providing an airflow generating section 90 on the inner circumference of the motor shaft 16, it is possible to promote heat transfer by diffusion within the motor shaft 16 close to the rotor 28, which is the heat source. In addition, it becomes possible to effectively remove heat from the motor shaft 16, which is difficult to remove by thermal conduction, by convection.

(E) The inner diameter Ra of the motor shaft 16 is greater than the inner diameter Rb of the input shaft 20. This allows the position of the airflow generating unit 90 to be shifted radially outward, compared to when the inner diameter Ra of the motor shaft 16 is equal to or smaller than the inner diameter Rb of the input shaft 20. This makes it easier to avoid interference between the object (e.g., the insertion member 142 described below) inserted into the hollow portion 56 of the motor shaft 16 and the airflow generating unit 90. This in turn makes it easier to prevent entrapment by the airflow generating unit 90.

Next, other features of the gear motor 10 of this embodiment will be described. Please refer to FIG. 1. The gear motor 10 includes a detector 100 that detects the rotation of the motor shaft 16, and electrical devices 102A and 102B that use electric power.

The detector 100 is a rotary encoder. The detector 100 includes a detected member 104 that can rotate integrally with the rotating shaft 24, and a sensor 106 that can detect the detected member 104. For example, the detected member 104 is an encoder disk, and the sensor 106 is an optical sensor or a magnetic sensor. The detected member 104 is disposed at the anti-load end of the rotating shaft 24. The sensor 106 is mounted on a sensor board (second electrical component 102B) described later. The detector 100 can detect the rotation of the motor shaft 16 by detecting the detected member 104 with the sensor 106.

The electric devices 102A and 102B of this embodiment are circuit boards provided separately from the stator 26 and rotor 28 of the motor 18. The electric devices 102A and 102B as circuit boards include a first electric device 102A consisting of a control board that controls the motor 18, and a second electric device 102B consisting of a sensor board on which a sensor 106 is mounted. In addition to a control element 108 that controls the motor 18, a driver element 110 that supplies power to the motor 18 under the control of the control element 108 is mounted on the control board. The control element 108 is, for example, a combination of a CPU, RAM, ROM, etc., and the driver element 110 is, for example, a driver IC, etc. The control element 108 is electrically connected to the sensor 106 via wiring (not shown), and controls the motor 18 based on the detection result of the sensor 106.

The electrical components 102A and 102B are attached to the motor housing 30 via the holder 112. The electrical components 102A and 102B are arranged outside the rotating shaft 24 on the anti-load side of the motor shaft 16 in the axial direction X. The electrical components 102A and 102B are arranged in the axial space 64 on the anti-load side of the rotating shaft 24.

The reducer 22 includes an attachment member 114 for attaching the second mating member 14. In this embodiment, the attachment member 114 is the output member 34 (carrier 54). The second mating member 14 includes an attachment receiving portion 116 for attaching to the attachment member 114 of the reducer 22. The attachment receiving portion 116 is disposed on the load side of the input shaft 20. The attachment receiving portion 116 is disposed in the axial space 64 on the load side of the rotating shaft 24. In this embodiment, the second mating member 14 is attached to the reducer 22 by tightening the attachment receiving portion 116, the attachment member 114, and the second internal gear 44B together with the bolt 118 while the attachment receiving portion 116 is abutted against the attachment member 114.

The airflow generating unit 90 of the rotating shaft 24 can generate an airflow toward the load side in the axial direction X in the hollow portion 56. That is, the airflow generating unit 90 generates an airflow in the opposite direction to the axial space 64 in which the electrical equipment 102A and 102B are located. To achieve this, the motor 18 of this embodiment can rotate the rotating shaft 24 in a constant rotation direction (the other side Db in the circumferential direction in the example of FIG. 3) without switching the rotation direction of the rotating shaft 24. In addition, the airflow generating unit 90 of the rotating shaft 24 can generate an airflow toward the load side when the rotating shaft 24 rotates in the constant rotation direction. In addition, to achieve this, as described in the example of FIG. 6, the airflow generating unit 90 may always generate an airflow toward the load side in the axial direction X regardless of the rotation direction of the rotating shaft 24. In any case, the gear motor 10 may be configured to always generate an airflow toward the load side by the airflow generating unit 90.

(F) This allows the heat radiated from the rotating shaft 24 to the internal space 66 to be sent in the opposite direction to the electrical equipment 102A, 102B in the axial direction X. As a result, the space around the electrical equipment 102A, 102B (axial space 64) is less likely to be heated by the heat radiated from the rotating shaft 24, ensuring the safety of the electrical equipment 102A, 102B.

The airflow generated in the hollow portion 56 of the rotating shaft 24 is discharged to the outside (axial space 64) from an opening 62 on the load side of the rotating shaft 24. The airflow discharged to the outside of the rotating shaft 24 passes through the through hole 54a of the carrier 54 and hits the mounting portion 116 of the second mating member 14 on the load side of the rotating shaft 24.

(G) As a result, by cooling the second mating member 14 with the airflow, the temperature difference between the second mating member 14 and the mounting member 114 can be increased, and heat conduction via these can be promoted. In addition, by cooling the surrounding structure of the mounting member 114 in the reducer 22 (e.g., the rotating shaft 24, the mounting member 114) with the airflow, heat conduction from the high-temperature motor shaft 16 side, which is the heat source, to the low-temperature mounting member 114 side can be promoted. As a result, the amount of heat dissipated from the gear motor 10 as a whole can be increased.

In order to obtain the effects of (F) and (G) described above, the direction of the airflow generated by the airflow generating unit 90 may be switched between the load side and the anti-load side depending on the rotation direction of the rotating shaft 24. Even in this case, the effects described in (F) and (G) can be obtained when the airflow direction is the load side.

In addition, even if the airflow generating unit 90 generates an airflow toward the anti-load side, the airflow can promote heat transfer by diffusion in the axial space 64 in which the electrical equipment 102A, 102B is located, and the electrical equipment 102A, 102B can be cooled. Even with this configuration, the safety of the electrical equipment 102A, 102B can be ensured to a certain extent.

(Second embodiment) See FIG. 5. In this embodiment, another form of the airflow generating unit 90 will be described. The fins 92 of the airflow generating unit 90 in this embodiment extend linearly along the axial direction. With this configuration, when the rotating shaft 24 rotates, the airflow generating unit 90 generates an airflow toward one or both of the load side and the anti-load side. In this way, the specific arrangement and number of the fins 92 are not particularly limited.

Consider a case where one opening 62 of the hollow portion 56 (e.g., the opening 62 on the load side) is blocked by the second mating member 14 with such a fin 92 configuration. In this case, an airflow toward the load side is generated in the hollow portion 56, and an airflow toward the anti-load side is generated when the airflow toward the load side hits the second mating member 14 and turns back. In this case, air is taken in at a part of the other opening 62 of the hollow portion 56 (e.g., the opening 62 on the anti-load side), while air is blown out at another part of the opening 62. In this way, the opening 62 for taking in air into the hollow portion 56 and the opening 62 for blowing air out into the hollow portion 56 may be the same or different.

(Third embodiment) Please refer to Figures 6 and 7. In this embodiment, another form of the airflow generating unit 90 will be described. The airflow generating unit 90 in this embodiment is a movable fin 92 extending in the axial direction X. There are multiple airflow generating units 90 (fins 92) in this embodiment. The fins 92 are generally plate-shaped. The fins 92 have a base end 92a provided on one end side in the axial direction X and a tip end 92b provided on the other end side in the axial direction X. The base end 92a of the fin 92 is a fixed end that is connected to the hollow portion 56 of the rotating shaft 24 and integrated with the resin part 72. The tip end 92b of the fin 92 is located on the tip side of the part extending from the base end 92a of the fin 92, and is a free end that is not connected to the hollow portion 56 of the rotating shaft 24. In this embodiment, the base end 92a of the fin 92 is provided on the anti-load side, and the tip end 92b of the fin 92 is provided on the load side. Hereinafter, the direction from the base end side to the tip end side of the airflow generating unit 90 (fins 92) in the axial direction X is referred to as the tip direction Dc.

Refer to Figures 8(A) and 8(B). Figure 8(A) shows the state in which the rotating shaft 24 rotates in one circumferential direction (hereinafter referred to as the forward rotation direction Dd1). Figure 8(B) shows the state in which the rotating shaft 24 rotates in the other circumferential direction (hereinafter referred to as the reverse rotation direction Dd2).

The fin 92 can move in both circumferential directions with respect to the hollow portion 56 of the rotating shaft 24 in an axial range including at least the tip 92b of the fin 92. The fin 92 of this embodiment can move in both circumferential directions by deforming so as to bend in an axial range including at least the tip 92b of the fin 92. In addition, the entire fin 92 may be able to move in both circumferential directions without deformation of the fin 92. This assumes, for example, a case in which the fin 92 is connected to the hollow portion 56 of the rotating shaft 24 rotatably around a radial axis via a rotational connection mechanism such as a hinge or ball joint. In this case, the fin 92 is provided separately from the rotating shaft 24.

To facilitate the circumferential deformation of the fin 92, the fin 92 may be configured so that at least one of the circumferential dimension La (see FIG. 7) and the radial dimension Lb (see FIG. 6) decreases toward the tip side. The fin 92 of this embodiment is configured so that both the circumferential dimension La and the radial dimension Lb decrease. These dimensions may decrease stepwise or continuously toward the tip side of the fin 92.

As the rotating shaft 24 rotates, the fins 92 can move in the circumferentially opposite direction (hereinafter referred to as the counter-rotation direction De) to the rotational direction of the rotating shaft 24, at least in an axial range including the tip 92b of the fin 92, due to the resistance of the air hitting the fin 92. At this time, the fin 92 is inclined with respect to the axial direction X so as to move toward the counter-rotation direction De as it moves toward the tip direction Dc of the fin 92, in the axial range including the tip 92b of the fin 92. As a result, when the rotating shaft 24 is in a rotating state, the fin 92 can push air in the tip direction Dc of the fin 92, regardless of the rotational direction of the rotating shaft 24.

For example, as shown in FIG. 8A, when the rotating shaft 24 rotates in the forward rotation direction Dd1, in the axial range including the tip 92b of the fin 92, the fin 92 moves in the counter-rotation direction De opposite to the forward rotation direction Dd1. As a result, when the fin 92 is in a state where it is rotating in the forward rotation direction Dd1, the fin 92 can generate an airflow F toward the tip direction Dc. Also, as shown in FIG. 8B, when the rotating shaft 24 rotates in the reverse rotation direction Dd2, in the axial range including the tip 92b of the fin 92, the fin 92 moves in the counter-rotation direction De opposite to the reverse rotation direction Dd2. As a result, when the fin 92 is in a state where it is rotating in the reverse rotation direction Dd2, the fin 92 can generate an airflow F toward the tip direction Dc.

As a result, airflow F can be generated in the hollow portion 56 of the rotating shaft 24 in the same direction (tip direction Dc) regardless of the rotation direction of the rotating shaft 24. Therefore, even if the rotation direction of the rotating shaft 24 in the gear motor 10 changes, airflow F can be generated in the same direction.

In this way, the fins 92 may be movable, or may not move regardless of the direction of rotation of the rotating shaft 24. Furthermore, the number of movable fins 92 that satisfy the conditions described here is not particularly limited. Some of the multiple fins 92 that make up the airflow generating unit 90 may be movable fins 92, or all of them may be movable fins.

In addition, the airflow generating unit 90 may generate an airflow F in the same direction at all times, regardless of the rotation direction of the rotating shaft 24, without using fins 92. In generating such an airflow F, the airflow generating unit 90 may move in conjunction with the rotation of the rotating shaft 24, or may not move in conjunction with the rotation. Furthermore, when moving in conjunction with the rotation of the rotating shaft 24 in this manner, the airflow generating unit 90 may move in a direction other than the opposite direction to the rotation direction of the rotating shaft 24.

The gear motor 10 of this embodiment also has the components (not shown) described above in (A) to (G), thereby achieving the effects corresponding to those descriptions.

(Fourth embodiment) See FIG. 9. In this embodiment, another form of the rotating shaft 24 is described. The rotating shaft 24 has a double cylinder section 130 that is provided in at least a part of the axial range of the rotating shaft 24. The double cylinder section 130 in this embodiment is provided in a part of the axial range of the motor shaft 16 in the rotating shaft 24.

The double cylinder portion 130 has a cylindrical outer cylinder portion 132, a cylindrical inner cylinder portion 134 arranged inside the outer cylinder portion 132, and an inter-cylinder opening 136 formed between the axial end of the inner cylinder portion 134 (the axial end on the anti-load side in this embodiment) and the outer cylinder portion 132. The outer cylinder portion 132 constitutes the outer periphery of the rotating shaft 24. The hollow portion 56 of the rotating shaft 24 is provided inside the outer cylinder portion 132 at the location where the double cylinder portion 130 is provided. The inner cylinder portion 134 divides the internal space 66 of the hollow portion 56 of the rotating shaft 24 into an inter-cylinder space 138 between the outer cylinder portion 132 and the inner cylinder portion 134, and an intra-cylinder space 140 inside the inner cylinder portion 134.

The gear motor 10 includes an insertion member 142 that is inserted into the hollow portion 56 of the rotating shaft 24. In this embodiment, the insertion member 142 is a cable such as a power cable or a signal cable. The cable is connected, for example, to a control board (first electrical component 102A) of the gear motor 10. There are no particular limitations on the specific example of the insertion member 142. In addition, the insertion member 142 may be, for example, a shaft that is separate from the rotating shaft 24 and rotates integrally with the output member 34. The insertion member 142 is disposed in the intra-cylinder space 140 in the axial range of the rotating shaft 24 where the double cylinder portion 130 is provided.

The airflow generating section 90 is disposed in the inter-cylinder space 138 in the axial range of the rotating shaft 24 where the double cylinder section 130 is provided. The airflow generating section 90 is not disposed in the intra-cylinder space 140 in the same axial range. This allows the inner cylinder section 134 to prevent interference between the airflow generating section 90 and the insertion member 142 inserted into the hollow section 56 of the rotating shaft 24. This in turn prevents the insertion member 142 from being caught in the airflow generating section 90 when the rotating shaft 24 rotates.

The inner cylinder portion 134 has ventilation holes 144 that communicate between the inter-cylinder space 138 and the internal space 66. The ventilation holes 144 penetrate the inner cylinder portion 134 in the radial direction. In this embodiment, the inner cylinder portion 134 has multiple ventilation holes 144, and the multiple ventilation holes 144 are arranged in a mesh pattern. The arrangement of the multiple ventilation holes 144 is not particularly limited, and they may be arranged in a row in the axial direction X or circumferential direction. In addition, the number of ventilation holes 144 is not particularly limited, and the inner cylinder portion 134 may have only a single ventilation hole 144. In addition, the shape of the ventilation hole 144 is not particularly limited, and it may be a slit-like shape that is long in the axial direction X or circumferential direction.

The ventilation holes 144 serve to ventilate air between the inter-cylinder space 138 and the in-cylinder space 140 when the airflow generating unit 90 generates an airflow in the inter-cylinder space 138. For example, consider a case where the airflow generating unit 90 generates an airflow in the inter-cylinder space 138 in the axial direction toward the inter-cylinder opening 136 side (the anti-load side in the illustrated example). In this case, air is taken in from the in-cylinder space 140 to the inter-cylinder space 138 through the ventilation holes 144, and air is blown out from the inter-cylinder space 138 through the inter-cylinder opening 136. In this case, in the illustrated example, an airflow toward the anti-load side is generated by the airflow generating unit 90 within the hollow portion 56 of the rotating shaft 24.

In addition, consider a case where the airflow generating unit 90 generates an airflow in the inter-cylinder space 138 in the axial direction X toward the opposite side of the inter-cylinder opening 136 (the load side in the illustrated example). In this case, air is taken into the inter-cylinder space 138 through the inter-cylinder opening 136, and air is blown out from the inter-cylinder space 138 to the intra-cylinder space 140 through the ventilation hole 144. In this case, in the illustrated example, an airflow toward the load side is generated by the airflow generating unit 90 within the hollow portion 56 of the rotating shaft 24.

In this way, by providing the inner cylinder portion 134 with the ventilation holes 144, if a double cylinder portion 130 is present, an airflow can also be generated in the cylinder inner space 140 of the double cylinder portion 130. In addition, by promoting forced convection from the internal space 66 to the axial space 64 over a wide range within the hollow portion 56, forced air cooling of the rotating shaft 24 can be achieved over a wide range within the hollow portion 56.

The gear motor 10 of this embodiment also has the components (not shown) described above in (A) to (G), and can obtain the effects corresponding to those descriptions. Even if the inner cylinder portion 134 does not have the ventilation hole 144, the airflow generating unit 90 can generate an airflow in the inter-cylinder space 138. In this case, as described above, an airflow that turns back is generated in the inter-cylinder space 138. At this time, air is taken in from a part of the inter-cylinder opening 136, and air is blown out from another part of the inter-cylinder opening 136. As a result, forced convection can be promoted by blowing the air in the inter-cylinder space 138 through the inter-cylinder opening 136 into the axial space 64. Therefore, even if the inner cylinder portion 134 does not have the ventilation hole 144, forced air cooling of the rotating shaft 24 can be performed as described above in (A).

Other variations of each component are described.

Specific examples of the first mating member 12 and the second mating member 14 are not particularly limited. The first mating member 12 and the second mating member 14 may be, for example, a combination of a driven machine and a base, or may be either a base member and an arm member that constitute a multi-joint arm of a robot device. The robot device here is, for example, an industrial robot, a service robot, etc. Furthermore, the driven machine is not limited to a conveyor, and may be, for example, a wheel, a machine tool, etc.

Although an example in which the motor shaft 16 and the input shaft 20 are integrally configured has been described, they may be configured separately from each other and connected by a connecting member. In this case, either the motor shaft 16 or the input shaft 20 may be the rotating shaft 24 having the airflow generating section 90.

Specific examples of the reduction mechanism 32 of the reducer 22 are not particularly limited. In addition to a flexible meshing gear mechanism, the reduction mechanism 32 may be, for example, an eccentric oscillating gear mechanism, a planetary gear mechanism, an orthogonal shaft gear mechanism, a parallel shaft gear mechanism, etc. In the case of a flexible meshing gear mechanism, specific examples are not particularly limited. In addition to a cylindrical type, for example, a cup type or a top hat type may be used. In the case of an eccentric oscillating gear mechanism, either a center crank type or a distribution type may be used.

In the above example, the output member 34 of the reducer 22 is a carrier 54, but it may also be a reducer housing 36.

Specific examples of electrical equipment are not particularly limited. For example, the electrical equipment may be composed of only the control element 108, the driver element 110, and the sensor 106, or may be a battery or the like. The use of the sensor 106 of the electrical equipment is not particularly limited. The sensor 106 may be used as a pressure detector, a temperature detector, or the like, in addition to being used as a rotation detector. When the sensor 106 is used as a rotation detector, it may be, for example, a resolver, a Hall element, or the like.

An example has been described in which the resin portion 72 of the rotating shaft 24 constitutes the shaft main body 68, and the metal portion 74 constitutes the input shaft constituent portion 70. As long as the resin portion 72 and the metal portion 74 are integrated in the rotating shaft 24, their specific constituent locations are not particularly limited. For example, the entire hollow portion 56 of the rotating shaft 24 may be constituted only by the resin portion 72. The metal portion 74 may also constitute the outer peripheral portions of both the motor shaft 16 and the input shaft 20, or may only constitute the outer peripheral portion of the motor shaft 16. The majority of the hollow portion 56 may be constituted by the metal portion 74, and only the airflow generating portion 90 provided in the hollow portion 56 may be constituted by the resin portion 72.

The airflow generating section 90 of the rotating shaft 24 needs only to be able to generate an airflow within the hollow section 56 by the rotation of the rotating shaft 24. To achieve this, the airflow generating section 90 may be something other than the fins 92, and may be, for example, a groove extending in the axial direction provided on the inner circumference of the hollow section 56. This groove may extend linearly or spirally in the axial direction on the inner circumference of the hollow section 56.

Even when the airflow generating unit 90 is something other than the fin 92, the components described as the characteristics of the fin 92 may be applied to the airflow generating unit 90 other than the fin 92. For example, like the fin 92, the airflow generating unit 90 may have a base end 92a that is integrated with the resin part 72 and serves as a fixed end, and a tip end 92b that is at the end of the part extending from the base end 92a and serves as a free end. In addition, such an airflow generating unit 90 may deform in accordance with the rotation of the rotating shaft 24.

The airflow F generated by the airflow generating unit 90 may take in air from the axial space 64 on the load side into the internal space 66, and blow air from the internal space 66 into the axial space 64 on the anti-load side.

The airflow generating section 90 may be provided on the inner periphery of the resin section 72 separately from the resin section 72. In this case, the airflow generating section 90 may be made of either a metal-based material or a resin-based material.

An example in which the motor housing 30 and the reducer housing 36 are made of a resin-based material has been described, but this is not limiting. The motor housing 30 and the reducer housing 36 may be made of, for example, a metal-based material.

In the above example, the airflow generating unit 90 is provided on the inner circumference of the motor shaft 16. Alternatively, the airflow generating unit 90 may be provided on the inner circumference of the input shaft 20, or on the inner circumferences of both the motor shaft 16 and the input shaft 20.

In the above example, the inner diameter Ra of the motor shaft 16 is larger than the inner diameter Rb of the input shaft 20. Alternatively, the inner diameter Ra may be smaller than or equal to the inner diameter Rb.

The axial range in which the double cylinder section 130 is provided in the rotating shaft 24 is not particularly limited. The double cylinder section 130 may be provided in the entire axial range of the rotating shaft 24, or may be provided in part or all of the axial range of the input shaft 20.

The airflow generating unit 90 of the third embodiment is configured to deform in response to the rotation of the rotating shaft 24 for the purpose of generating an airflow in the same direction regardless of the direction of rotation of the rotating shaft 24. The configuration in which the airflow generating unit 90 deforms in response to the rotation of the rotating shaft 24 is not limited to this purpose, and may be used for a different purpose. This different purpose is, for example, the purpose of changing the speed of the airflow.

To achieve this objective, for example, the airflow generating unit 90 may be deformed in the opposite direction to the rotation direction of the rotating shaft 24 so that it is parallel to the axial direction X when the rotation speed of the rotating shaft 24 is slow, and is inclined relative to the axial direction X when the rotation speed of the rotating shaft 24 is fast. This makes it easier to increase the speed of the airflow generated by the airflow generating unit 90 when the rotation speed of the rotating shaft 24 increases, as compared to when the rotation speed of the rotating shaft 24 is slow. In any case, it can be understood that the airflow generating unit 90 deforms in accordance with the rotation of the rotating shaft 24, and thus the way the airflow flows can be changed before and after the deformation.

The above embodiments and variations are merely examples. The technical ideas that abstract these should not be interpreted as being limited to the contents of the embodiments and variations. Many design changes are possible for the contents of the embodiments and variations, such as changing, adding, or deleting components. In the above embodiments, the contents in which such design changes are possible are emphasized by adding the notation "embodiment". However, design changes are also permitted even in contents not so notated. Hatching on cross sections in the drawings does not limit the material of the objects that are hatched.

Any combination of the above components is also valid. For example, any of the description matters of other embodiments may be combined with the embodiment, and any of the description matters of the embodiment and other modified forms may be combined with the modified form. As an example of this, the movable fin 92 of the third embodiment may be combined with the double cylinder section 130 of the fourth embodiment. Similarly, the fin 92 of the first or second embodiment may be combined with the double cylinder section 130 of the fourth embodiment.

10...gear motor, 16...motor shaft, 18...motor, 20...input shaft, 22...reduction gear, 24...rotating shaft, 30...motor housing, 36...reduction gear housing, 56...hollow portion, 66...internal space, 72...resin portion, 74...metal portion, 90...airflow generating portion, 92...fins, 102A, 102B...electrical components, 130...double cylinder portion, 132...outer cylinder portion, 134...inner cylinder portion, 138...inter-cylinder space, 144...ventilation hole.

Claims (13)

A gear motor including a motor and a reducer,
a rotating shaft formed by at least one of a motor shaft of the motor and an input shaft of the reducer,
The rotation shaft is
A hollow portion penetrating in the axial direction;
a resin portion that constitutes at least a part of the hollow portion and is made of a resin-based material;
a metal portion that constitutes at least a part of an outer circumferential portion of the rotating shaft and is made of a metal material;
an airflow generating portion provided on the inner periphery of the resin portion and generating an airflow within the hollow portion by rotation of the rotating shaft. The gear motor according to claim 1, wherein the airflow generating section is integrally formed with the resin portion. the motor comprises a motor housing;
The reducer includes a reducer housing connected to the motor housing,
3. The gear motor according to claim 1, wherein the motor housing and the reducer housing are made of a resin material. The rotating shaft is integrally formed by both the motor shaft and the input shaft,
The gear motor according to claim 1 , wherein the airflow generating portion is provided on an inner periphery of the motor shaft. The gear motor according to claim 4, wherein the inner diameter of the motor shaft is larger than the inner diameter of the input shaft at the location where the airflow generating section is provided. A gear motor according to any one of claims 1 to 5, wherein the airflow generating unit generates an airflow in the same direction in the axial direction regardless of the direction of rotation of the rotating shaft. The gear motor according to claim 6, wherein the airflow generating section moves with the rotation of the rotating shaft, thereby generating an airflow in the same direction in the axial direction, regardless of the direction of rotation. A gear motor according to any one of claims 1 to 7, wherein the airflow generating section deforms as the rotating shaft rotates. an electric device disposed on an axially opposite load side of the motor shaft,
The gear motor according to claim 1 , wherein the airflow generating section generates an airflow toward a load side in the axial direction. The reducer is attached to a mating member that is disposed on a load side of the input shaft,
The gear motor according to claim 1 , wherein the airflow generating section generates an airflow toward a load side in the axial direction. The rotating shaft includes a double cylinder portion having an outer cylinder portion and an inner cylinder portion,
The gear motor according to claim 1 , wherein the airflow generating portion is disposed between the outer cylinder portion and the inner cylinder portion. The gear motor according to claim 11, wherein the inner cylinder portion has a ventilation hole that connects the inter-cylinder space between the outer cylinder portion and the inner cylinder portion with the intra-cylinder space inside the inner cylinder portion. The gear motor according to claim 1 , wherein the metal portion is disposed outside the resin portion.

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