WO2023115848A1 - 谐波齿轮装置以及机器人用关节装置 - Google Patents

谐波齿轮装置以及机器人用关节装置 Download PDF

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Publication number
WO2023115848A1
WO2023115848A1 PCT/CN2022/099435 CN2022099435W WO2023115848A1 WO 2023115848 A1 WO2023115848 A1 WO 2023115848A1 CN 2022099435 W CN2022099435 W CN 2022099435W WO 2023115848 A1 WO2023115848 A1 WO 2023115848A1
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WIPO (PCT)
Prior art keywords
gear
flexible external
external gear
teeth
wave generator
Prior art date
Application number
PCT/CN2022/099435
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English (en)
French (fr)
Chinese (zh)
Inventor
王刚
林文捷
峯岸清次
伊佐地毅
郭子铭
Original Assignee
美的集团股份有限公司
广东极亚精机科技有限公司
广东美的制冷设备有限公司
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Application filed by 美的集团股份有限公司, 广东极亚精机科技有限公司, 广东美的制冷设备有限公司 filed Critical 美的集团股份有限公司
Priority to CN202280076192.7A priority Critical patent/CN118284757A/zh
Publication of WO2023115848A1 publication Critical patent/WO2023115848A1/zh

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
    • B25J17/00—Joints
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H1/00—Toothed gearings for conveying rotary motion
    • F16H1/28—Toothed gearings for conveying rotary motion with gears having orbital motion
    • F16H1/32—Toothed gearings for conveying rotary motion with gears having orbital motion in which the central axis of the gearing lies inside the periphery of an orbital gear
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H49/00—Other gearings
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H57/00—General details of gearing
    • F16H57/04—Features relating to lubrication or cooling or heating

Definitions

  • Embodiments of the present disclosure generally relate to a harmonic gear device and a joint device for a robot, and more specifically, relate to a harmonic gear device and a joint device for a robot including a rigid internal gear, a flexible external gear, and a wave generator.
  • Patent Document 1 discloses that the surface treatment of a flexible external gear in a harmonic gear device (flexural mesh gear device) is carried out by nitriding treatment.
  • the harmonic gear unit has a ring-shaped rigid internal gear, a cup-shaped flexible external gear arranged inside, and an elliptical wave generator embedded in the inside.
  • the flexible external gear includes a cylindrical body and external teeth formed on the outer peripheral surface of the body.
  • the flexible external gear is bent into an ellipse by the action of the wave generator, and the external teeth of the flexible external gear located at both ends of the ellipse in the direction of the major axis mesh with internal teeth formed on the inner peripheral surface of the rigid internal gear.
  • Patent Document 1 Japanese Patent Application Laid-Open No. 2001-59153
  • Embodiments of the present disclosure have been made in view of the above-mentioned circumstances, and an object of the present disclosure is to provide a harmonic gear device and a robot joint device that are unlikely to cause a decrease in reliability.
  • a harmonic gear device includes a rigid internal gear, a flexible external gear, and a wave generator.
  • the rigid internal gear is an annular member having internal teeth.
  • the flexible external gear is an annular member having external teeth and arranged inside the rigid internal gear.
  • the wave generator has a non-circular cam driven to rotate about a rotation axis, and a bearing mounted on the outside of the cam. The wave generator is disposed inside the flexible external gear and causes the flexible external gear to bend.
  • the flexible external gear is deformed as the cam rotates, a part of the external teeth meshes with a part of the internal teeth, and the flexible external gear Relative rotation is performed with respect to the rigid internal gear according to the difference in the number of teeth of the flexible external gear and the rigid internal gear.
  • a chemical conversion treatment coating is provided on a target surface constituted by at least one of the outer peripheral surface of the wave generator and the inner peripheral surface of the flexible external gear.
  • a joint device for a robot includes the harmonic gear device, a first member fixed to the rigid internal gear, and a second member fixed to the flexible external gear.
  • FIG. 1A is a cross-sectional view showing a schematic configuration of a harmonic gear device according to Embodiment 1.
  • FIG. 1A is a cross-sectional view showing a schematic configuration of a harmonic gear device according to Embodiment 1.
  • FIG. 1B is an enlarged view of area Z1 of FIG. 1A .
  • FIG. 2A is a schematic view of the above-mentioned harmonic gear device viewed from the input side of the rotary shaft.
  • FIG. 2B is an enlarged view of area Z1 of FIG. 2A .
  • 3A is a schematic exploded perspective view of the harmonic gear device viewed from the output side of the rotary shaft.
  • 3B is a schematic exploded perspective view of the harmonic gear device viewed from the input side of the rotary shaft.
  • FIG. 4 is a cross-sectional view showing a schematic structure of an actuator including the above-mentioned harmonic gear device.
  • FIG. 5 is an enlarged schematic cross-sectional view of a main part of a range corresponding to FIG. 1B .
  • FIG. 6 is a schematic diagram of the inner peripheral surface of the flexible external gear viewed from the bearing side of the harmonic gear device.
  • Fig. 7A is a schematic view showing the surface state of the inner peripheral surface of the flexible external gear and the outer peripheral surface of the wave generator in the section along line A1-A1 in Fig. 6 .
  • FIG. 7B is an enlarged schematic view of the region Z1 in FIG. 7A .
  • 8A is a schematic view showing the surface state of the inner peripheral surface of the flexible external gear and the outer peripheral surface of the wave generator in the cross section of line A2-A2 in FIG. 6 .
  • FIG. 8B is an enlarged schematic diagram of the area Z1 in FIG. 8A .
  • FIG. 9 is a schematic diagram schematically showing changes in the state of the target surface of the above-mentioned harmonic gear device, which is a schematic diagram showing the surface state of the external teeth in the area Z1 of FIG. A schematic diagram of the surface state of an external tooth.
  • FIG. 10 is a conceptual explanatory view for illustrating the operation of the long-axis side and the short-axis side of the tapered surface of the harmonic gear device.
  • Fig. 11 is a cross-sectional view showing an example of a robot using the above-mentioned harmonic gear device.
  • FIG. 12A is a cross-sectional view illustrating a schematic configuration of a harmonic gear device according to a modified example of the first embodiment.
  • FIG. 12B is an enlarged view of the area Z1 of FIG. 12A .
  • 13A is a schematic view showing the surface state of the inner peripheral surface of the flexible external gear and the outer peripheral surface of the wave generator in the section along line A1-A1 of FIG. 6 in the harmonic gear device according to the second embodiment.
  • FIG. 13B is an enlarged schematic view of the region Z1 in FIG. 13A .
  • FIGS. 1A to 5 The drawings referred to in the embodiments of the present disclosure are all schematic drawings, and the size and thickness ratios of the structural elements in the drawings do not necessarily reflect the actual size ratios.
  • the tooth shape, size, and number of teeth of the internal teeth 21 and the external teeth 31 in FIGS. 2A to 3B are only schematically shown for illustration, and are not intended to be limited to the illustrated shapes.
  • the harmonic gear device 1 of the present embodiment is a gear device including a rigid internal gear 2 , a flexible external gear 3 , and a wave generator 4 .
  • an annular flexible external gear 3 is arranged inside an annular rigid internal gear 2
  • a wave generator 4 is arranged inside the flexible external gear 3 .
  • the wave generator 4 partially meshes the external teeth 31 of the flexible external gear 3 with the internal teeth 21 of the rigid internal gear 2 by flexing the flexible external gear 3 into a non-circular shape.
  • the wave generator 4 rotates, the meshing position of the internal teeth 21 and the external teeth 31 moves in the circumferential direction of the rigid internal gear 2, and a flexible force is generated between the two gears (the rigid internal gear 2 and the flexible external gear 3).
  • the external gear 3 rotates relative to the tooth number difference between the flexible external gear 3 and the rigid internal gear 2 .
  • the rigid internal gear 2 is fixed, the flexible external gear 3 rotates with the relative rotation of both gears.
  • a rotational output decelerated at a relatively high reduction ratio according to the difference in the number of teeth of both gears can be obtained from the flexible external gear 3 .
  • the wave generator 4 that flexes the flexible external gear 3 has a non-circular cam 41 and a bearing 42 that are driven to rotate around the input side rotation axis Ax1 (see FIG. 1A ).
  • the bearing 42 is arranged between the outer peripheral surface 411 of the cam 41 and the inner peripheral surface 301 of the flexible external gear 3 .
  • the inner ring 422 of the bearing 42 is fixed to the outer peripheral surface 411 of the cam 41 , and the outer ring 421 of the bearing 42 is elastically deformed by being pressed by the cam 41 via a ball-shaped rolling element 423 .
  • the rolling elements 423 roll so that the outer ring 421 can rotate relative to the inner ring 422.
  • the wave generator 4 having the bearing 42 transmits power by meshing the internal teeth 21 and the external teeth 31 while flexing the flexible external gear 3 .
  • the contact portion between the flexible external gear 3 and the wave generator 4 may Fretting wear occurs. If fretting wear occurs, it may cause roughness of the surface, rust caused by wear powder, and damage to the wave generator 4 (bearing 42) caused by the wear powder entering the inside of the wave generator 4, etc., affecting Reliability of the harmonic gear unit 1.
  • the rotation of the wave generator 4 requires excess energy, resulting in a decrease in power transmission efficiency, or by the force applied to the bearing 42. Life shortening due to increased load, etc.
  • the wear powder enters the bearing 42, starting from the indentation formed by the bite of the wear powder between the outer ring 421 or the inner ring 422 and the rolling element 423 of the bearing 42, the outer ring 421, the inner ring 422 and the The surface of any of the rolling elements 423 may be damaged.
  • the harmonic gear device 1 suppresses the occurrence of fretting wear by the following configuration, and makes it less likely to cause a decrease in reliability.
  • the harmonic gear device 1 of the present embodiment includes an annular rigid internal gear 2 having internal teeth 21 , an annular flexible external gear 3 having external teeth 31 , and a wave harmonic gear. generator 4.
  • the flexible external gear 3 is disposed inside the rigid internal gear 2 .
  • the wave generator 4 is disposed inside the flexible external gear 3 and causes the flexible external gear 3 to bend.
  • the wave generator 4 has a non-circular cam 41 driven to rotate around the rotation axis Ax1 , and a bearing 42 attached to the outside of the cam 41 .
  • the flexible external gear 3 is deformed with the rotation of the cam 41, a part of the external teeth 31 meshes with a part of the internal teeth 21, and the flexible external gear 3 follows the shape of the flexible external gear 3.
  • the difference in the number of teeth from the rigid internal gear 2 makes relative rotation with respect to the rigid internal gear 2 .
  • the chemical conversion treatment coating C1 is provided on the target surface S1 constituted by at least one of the outer peripheral surface 424 of the wave generator 4 and the inner peripheral surface 301 of the flexible external gear 3 .
  • the contact portion of the flexible external gear 3 with the wave generator 4 (bearing 42 ) has a surface state that is easily maintained covered with the lubricant Lb1 (see FIG. 4 ).
  • the lubricant Lb1 is held (soaked) in the chemical conversion treatment coating C1, and the position is easily maintained lubricated. The state covered by agent Lb1.
  • fretting wear is suppressed by preventing "lubricant depletion" in which the lubricant Lb1 is insufficient or exhausted at the contact portion of the outer ring 421 and the flexible external gear 3 generation.
  • a relatively soft chemical conversion treatment coating C1 such as a phosphate coating is provided on the outer peripheral surface 424 of the wave generator 4 and/or the inner peripheral surface 301 of the flexible external gear 3, thereby The contact portion between the external gear 3 and the wave generator 4 maintains sufficient lubricant Lb1.
  • the harmonic gear device 1 of the present embodiment As a result, the surface of the contact portion of the flexible external gear 3 with the bearing 42 (the outer ring 421 ) is covered with the lubricant Lb1, and the occurrence of fretting wear is suppressed. Therefore, in the harmonic gear device 1 of the present embodiment, troubles caused by fretting wear between (the outer ring 421 of) the bearing 42 and the flexible external gear 3 are less likely to occur, and reliability reduction is less likely to occur.
  • the harmonic gear device 1 of the present embodiment is less prone to decrease in reliability especially when used for a long period of time, so that the transmission efficiency of the harmonic gear device 1 is further improved, its life is increased, and its performance is improved. .
  • the chemical conversion treatment coating C1 may be provided on at least one of the outer peripheral surface 424 of (the bearing 42 of) the wave generator 4 and the inner peripheral surface 301 of the flexible external gear 3 .
  • the chemical conversion treatment coating C1 provided on the flexible external gear 3 is called
  • the chemical conversion treatment coating C2 (see FIG. 13A ) provided on the wave generator 4 is referred to as the "first chemical conversion treatment coating” and the "second chemical conversion treatment coating”.
  • the chemical conversion treatment coating C1 is provided only on the inner peripheral surface 301 of the flexible external gear 3 among the outer peripheral surface 424 of the wave generator 4 and the inner peripheral surface 301 of the flexible external gear 3 .
  • the chemical conversion treatment coating C1 includes the “first chemical conversion treatment coating” provided on the target surface S1 constituted by the inner peripheral surface 301 of the flexible external gear 3 .
  • the chemical conversion treatment coating (second chemical conversion treatment coating) on the wave generator 4 side will be described in the second embodiment.
  • the harmonic gear device 1 of the present embodiment constitutes an actuator 100 together with a drive source 101 and an output unit 102 as shown in FIG. 4 .
  • the actuator 100 of this embodiment includes the harmonic gear device 1 , the driving source 101 and the output unit 102 .
  • the drive source 101 rotates the wave generator 4 .
  • the output unit 102 takes out the rotational force of either one of the rigid internal gear 2 and the flexible external gear 3 as an output.
  • the harmonic gear device 1 of the present embodiment constitutes a robot joint device 130 together with a first member 131 and a second member 132 as shown in FIG. 4 .
  • the robot joint device 130 of this embodiment includes the harmonic gear device 1 , the first member 131 and the second member 132 .
  • the first member 131 is fixed to the rigid internal gear 2 .
  • the second member 132 is fixed to the flexible external gear 3 . Accordingly, relative rotation occurs between the flexible external gear 3 and the rigid internal gear 2 in the harmonic gear device 1, so that the first member 131 and the second member 132 in the robot joint device 130 are relatively rotated.
  • annulus refers to a shape such as a circle (ring) that forms a space (region) surrounded on the inside at least when viewed from above, and is not limited to a circular shape (annular shape) that is a perfect circle when viewed from above. ), may also be, for example, an ellipse shape, a polygonal shape, and the like. Also, for example, even if it has a bottom portion 322 like the cup-shaped flexible external gear 3 , as long as the trunk portion 321 is ring-shaped, it is called a “ring-shaped” flexible external gear 3 .
  • the "rigidity” mentioned in the embodiments of the present disclosure refers to the property that an object resists the deformation when an external force is applied to the object and the object is about to be deformed. In other words, a rigid object is difficult to deform even when an external force is applied.
  • the "flexibility” mentioned in the embodiments of the present disclosure refers to the property of an object elastically deforming (flexing) when an external force is applied to the object. In other words, a flexible object is easily deformed elastically when an external force is applied. Therefore, "rigid” and “flexible” are opposite meanings.
  • the "rigidity" of the rigid internal gear 2 and the “flexibility” of the flexible external gear 3 are used in opposite meanings. That is, the “rigidity” of the rigid internal gear 2 means that the rigid internal gear 2 has relatively higher rigidity than at least the flexible external gear 3 , that is, the rigid internal gear 2 is hardly deformed even if an external force is applied thereto. Similarly, the “flexibility” of the flexible external gear 3 means that the flexible external gear 3 has relatively higher flexibility than the rigid internal gear 2 at least, that is, it is easily elastically deformed when an external force is applied.
  • one side of the rotation axis Ax1 (right side in FIG. 1A ) is sometimes referred to as “input side”, and the other side of the rotation axis Ax1 (left side in FIG. 1A ) is sometimes referred to as “input side”.
  • output side That is, in the example of FIG. 1A , the flexible external gear 3 has the opening surface 35 on the "input side” of the rotation axis Ax1.
  • input side and “output side” are merely labels added for explanation, and are not intended to limit the positional relationship between the input and the output when viewed from the harmonic gear device 1 .
  • non-circular shape refers to a shape that is not a perfect circle, including, for example, an elliptical shape and an oblong shape.
  • the non-circular cam 41 of the wave generator 4 has an elliptical shape. That is, in the present embodiment, the wave generator 4 bends the flexible external gear 3 into an elliptical shape.
  • the "elliptical shape” mentioned in the embodiments of the present disclosure refers to the overall shape in which the perfect circle is flattened and the intersection point of the major axis and the minor axis orthogonal to each other is located in the center, and it is not limited to the distance between two fixed points on a plane.
  • the curve formed by the set of points where the sum of the distances is constant is the "ellipse” in mathematics. That is to say, the cam 41 in the present embodiment may be a curved line formed by a collection of points whose distances from two fixed points on a plane are constant as the mathematical "ellipse", or may not be
  • the "ellipse” in mathematics is an ellipse like a long circle.
  • the drawings referred to in the embodiments of the present disclosure are all schematic drawings, and the ratios of the sizes and thicknesses of the structural elements in the drawings do not necessarily reflect the actual size ratios. Therefore, for example, in FIG. 2A , the shape of the cam 41 of the wave generator 4 is a slightly exaggerated elliptical shape, but it is not intended to limit the actual shape of the cam 41 .
  • the “rotational axis” mentioned in the embodiments of the present disclosure refers to an imaginary axis (straight line) that is the center of the rotational motion of the rotating body. That is, the rotation axis Ax1 is a virtual axis without a real body.
  • the wave generator 4 rotates around the rotation axis Ax1.
  • the internal teeth 21 of the rigid internal gear 2 are composed of a set of teeth formed on the inner peripheral surface of the rigid internal gear 2 .
  • the external teeth 31 of the flexible external gear 3 are composed of a set of teeth formed on the outer peripheral surface of the flexible external gear 3 .
  • the “chemical conversion treatment coating” mentioned in the embodiments of the present disclosure is a coating formed by chemical treatment (chemical treatment), which is formed by performing chemical conversion treatment on an object surface to cover the object surface.
  • Chemical conversion treatment is one of the forms of surface treatment, which causes a chemical reaction by causing a treatment agent to act on the surface of a material (especially a metal), thereby imparting corrosion resistance and affinity with paint, etc. Different properties are handled. Therefore, properties different from those of the target surface S1 before the chemical conversion treatment are imparted to the chemical conversion treatment coating C1 .
  • the chemical conversion treatment include electrochemical oxidation or sulfurization, chemical oxidation or reduction, and film formation using oxides or phosphates of aluminum, chromium, or zinc, and the like.
  • the chemical conversion treatment using phosphate for iron when the iron is immersed in the treatment solution, the iron dissolves and the pH of the solution near the iron rises, whereby the metal ions in the solution become insoluble salts and Precipitation, thereby forming a chemical conversion treatment film covering iron.
  • the "parallel” mentioned in the embodiments of the present disclosure refers to the situation that two straight lines on a plane are extended to any position and do not intersect, that is, the angle between the two is strictly 0 degrees (or 180 degrees) Except for the case of , the angle between the two is in a relationship within an error range that converges to a few degrees (for example, less than 10 degrees) relative to 0 degrees.
  • the "orthogonal" mentioned in the embodiments of the present disclosure means that, except for the case where the angle between the two intersects strictly at 90 degrees, the angle between the two is within a few degrees relative to 90 degrees. (for example, less than 10 degrees) degree of error range relationship.
  • FIG. 1A is a cross-sectional view showing a schematic configuration of a harmonic gear device 1
  • FIG. 1B is an enlarged view of a region Z1 in FIG. 1A
  • 2A is a schematic view of the harmonic gear device 1 viewed from the input side of the rotation axis Ax1 (the right side of FIG. 1A )
  • FIG. 2B is an enlarged view of a region Z1 in FIG. 2A
  • FIG. 3A is a schematic exploded perspective view of the harmonic gear device 1 viewed from the output side of the rotation axis Ax1 (the left side in FIG. 1A ).
  • 3B is a schematic exploded perspective view of the harmonic gear device 1 viewed from the input side of the rotation axis Ax1.
  • FIG. 4 is a cross-sectional view showing a schematic configuration of the actuator 100 including the harmonic gear device 1 and the robot joint device 130 .
  • the harmonic gear device 1 of this embodiment includes the rigid internal gear 2, the flexible external gear 3, and the wave generator 4 as described above.
  • the materials of the rigid internal gear 2, the flexible external gear 3, and the wave generator 4, which are the structural elements of the harmonic gear device 1 are stainless steel, cast iron, carbon steel for mechanical structure, chrome-molybdenum steel, or phosphor bronze. or metals such as aluminum bronze.
  • the metal mentioned here includes metals subjected to surface treatment such as nitriding treatment.
  • a cup-shaped harmonic gear device is illustrated as an example of the harmonic gear device 1 . That is, the cup-shaped flexible external gear 3 is used in the harmonic gear device 1 of the present embodiment.
  • the wave generator 4 is combined with the flexible external gear 3 so as to be accommodated in the cup-shaped flexible external gear 3 .
  • the harmonic gear unit 1 is used in a state where the rigid internal gear 2 is fixed to the input side case 111 (see FIG. 4 ) and the output side case 112 (see FIG. 4 ). . Accordingly, the flexible external gear 3 relatively rotates with respect to the fixed member (input-side housing 111 and the like) in association with the relative rotation of the rigid internal gear 2 and the flexible external gear 3 .
  • the harmonic gear device 1 when the harmonic gear device 1 is used for the actuator 100, by applying a rotational force as an input to the wave generator 4, the rotation as an output is taken out from the flexible external gear 3. force. That is, the harmonic gear device 1 operates so as to take the rotation of the wave generator 4 as an input rotation and the rotation of the flexible external gear 3 as an output rotation. Accordingly, in the harmonic gear unit 1 , it is possible to obtain an output rotation decelerated at a relatively high reduction ratio relative to the input rotation.
  • the input-side rotational axis Ax1 and the output-side rotational axis Ax2 are located on the same straight line.
  • the rotation axis Ax1 on the input side and the rotation axis Ax2 on the output side are coaxial.
  • the rotation axis Ax1 on the input side is the rotation center of the wave generator 4 to which the input rotation is applied
  • the rotation axis Ax1 on the output side is the rotation center of the flexible external gear 3 which generates the output rotation. That is, in the harmonic gear unit 1 , the output rotation can be coaxially reduced by a relatively high reduction ratio relative to the input rotation.
  • the rigid internal gear 2 is also called a circular spline and is an annular member having internal teeth 21 .
  • the rigid internal gear 2 has an annular shape in which at least the inner peripheral surface is a perfect circle in plan view.
  • the internal teeth 21 are formed on the inner peripheral surface of the annular rigid internal gear 2 along the circumferential direction of the rigid internal gear 2 . All the plurality of teeth constituting the internal teeth 21 have the same shape and are provided at equal intervals over the entire area in the circumferential direction of the inner peripheral surface of the rigid internal gear 2 . That is, the pitch circle of the internal teeth 21 is a perfect circle in plan view.
  • the rigid internal gear 2 has a predetermined thickness in the direction of the rotation axis Ax1.
  • the internal teeth 21 are all formed over the entire length of the rigid internal gear 2 in the thickness direction.
  • the tooth lines of the internal teeth 21 are all parallel to the rotation axis Ax1.
  • the rigid internal gear 2 is fixed to the input-side housing 111 (see FIG. 4 ), the output-side housing 112 (see FIG. 4 ), and the like. Therefore, a plurality of fixing holes 22 for fixing are formed in the rigid internal gear 2 (see FIGS. 3A and 3B ).
  • the flexible external gear 3 is also called a flex spline and is an annular member having external teeth 31 .
  • the flexible external gear 3 is a cup-shaped member formed of a relatively thin metal elastic body (metal plate). That is, the flexible external gear 3 has flexibility because its thickness is relatively small (thin).
  • the flexible external gear 3 has a cup-shaped body portion 32 .
  • the main body part 32 has a body part 321 and a bottom part 322 .
  • the body portion 321 has a cylindrical shape in which at least the inner peripheral surface 301 is a perfect circle in plan view in a state where the flexible external gear 3 is not elastically deformed.
  • the central axis of the body part 321 coincides with the rotation axis Ax1.
  • the bottom portion 322 is disposed on one opening surface of the trunk portion 321 and has a disc shape that is a perfect circle in plan view.
  • the bottom portion 322 is arranged on the opening surface on the output side of the rotation axis Ax1 among the pair of opening surfaces of the trunk portion 321 .
  • the body part 32 has a bottomed cylindrical shape, that is, a cup shape that is open to the input side of the rotation axis Ax1 in the whole body part 321 and the bottom part 322 .
  • the opening surface 35 is formed on the end surface on the opposite side to the bottom portion 322 in the direction of the rotation axis Ax1 of the flexible external gear 3 .
  • the flexible external gear 3 has a cylindrical shape having an opening surface 35 on one side in the tooth line direction D1 (here, the input side of the rotation axis Ax1).
  • the body part 321 and the bottom part 322 are integrally formed by one metal member, thereby realizing the seamless body part 32 .
  • the wave generator 4 having a non-circular shape (elliptical shape) is fitted inside the body part 321 with respect to the flexible external gear 3 , and the wave generator 4 is combined.
  • the flexible external gear 3 is elastically deformed into a non-circular shape by receiving an external force from the wave generator 4 in the radial direction (direction perpendicular to the rotation axis Ax1) from the inside toward the outside.
  • the body portion 321 of the flexible external gear 3 is elastically deformed into an elliptical shape. That is, the state where the flexible external gear 3 is not elastically deformed refers to the state where the wave generator 4 is not combined with the flexible external gear 3 .
  • the elastically deformed state of the flexible external gear 3 refers to the state in which the wave generator 4 is combined with the flexible external gear 3 .
  • the wave generator 4 is fitted into an end portion of the inner peripheral surface 301 of the trunk portion 321 on the side opposite to the bottom portion 322 (the input side of the rotation axis Ax1 ).
  • the wave generator 4 is fitted into the end portion on the opening surface 35 side in the direction of the rotation axis Ax1 of the body portion 321 of the flexible external gear 3 . Therefore, in the state where the flexible external gear 3 is elastically deformed, the end portion of the flexible external gear 3 on the opening surface 35 side in the direction of the rotation axis Ax1 is deformed more than the end portion on the bottom 322 side, Becomes a shape closer to an elliptical shape.
  • the inner peripheral surface 301 of the body portion 321 of the flexible external gear 3 includes a portion inclined with respect to the rotation axis Ax1.
  • the tapered surface 302 (see Figure 9).
  • external teeth 31 are formed along the circumferential direction of the body portion 321 at an end portion of at least the side opposite to the bottom portion 322 (input side of the rotation axis Ax1 ) in the outer peripheral surface of the body portion 321 .
  • the external teeth 31 are provided at least at the end portion on the opening surface 35 side in the direction of the rotation axis Ax1 of the body portion 321 of the flexible external gear 3 .
  • All the plurality of teeth constituting the external teeth 31 have the same shape and are provided at equal intervals over the entire area of the outer peripheral surface of the flexible external gear 3 in the circumferential direction. That is, the pitch circles of the external teeth 31 are perfect circles in plan view when the flexible external gear 3 is not elastically deformed.
  • the external teeth 31 are formed only within a constant width from the end edge of the trunk portion 321 on the opening surface 35 side (the input side of the rotation axis Ax1 ). Specifically, the external teeth 31 are formed on the outer peripheral surface of at least the part where the wave generator 4 is fitted in the direction of the rotation axis Ax1 in the trunk part 321 (the end part on the side of the opening surface 35 ). The tooth lines of the external teeth 31 are all parallel to the rotation axis Ax1.
  • the tooth line of any one of the internal teeth 21 of the rigid internal gear 2 and the external teeth 31 of the flexible external gear 3 is parallel to the rotation axis Ax1 . Therefore, in the present embodiment, the "tooth line direction D1" is a direction parallel to the rotation axis Ax1. Moreover, the size of the tooth line direction D1 of the internal teeth 21 is the tooth width of the internal teeth 21. Similarly, the size of the tooth line direction D1 of the external teeth 31 is the tooth width of the external teeth 31. Therefore, the tooth line direction D1 and the tooth width direction mean the same.
  • the rotation of the flexible external gear 3 is taken out as the output rotation. Therefore, the output unit 102 of the actuator 100 is attached to the flexible external gear 3 (see FIG. 4 ).
  • a plurality of mounting holes 33 for mounting a shaft serving as the output unit 102 are formed in the bottom portion 322 of the flexible external gear 3 .
  • a through hole 34 is formed in the central portion of the bottom portion 322 . The periphery of the through hole 34 in the bottom 322 is thicker than other parts of the bottom 322 .
  • the flexible external gear 3 configured in this way is disposed inside the rigid internal gear 2 .
  • the flexible external gear 3 is connected to the rigid internal gear 2 so that only the end portion on the side opposite to the bottom 322 (the input side of the rotation axis Ax1 ) of the outer peripheral surface of the body portion 321 is inserted into the inside of the rigid internal gear 2 .
  • Gear 2 combo That is, the portion (the end portion on the side of the opening surface 35 ) into which the wave generator 4 is fitted in the direction of the rotation axis Ax1 of the body portion 321 of the flexible external gear 3 is inserted inside the rigid internal gear 2 .
  • external teeth 31 are formed on the outer peripheral surface of the flexible external gear 3
  • internal teeth 21 are formed on the inner peripheral surface of the rigid internal gear 2 . Therefore, in a state where the flexible external gear 3 is disposed inside the rigid internal gear 2 , the external teeth 31 and the internal teeth 21 face each other.
  • the number of internal teeth 21 of the rigid internal gear 2 is greater than the number of external teeth 31 of the flexible external gear 3 by 2N (N is a positive integer).
  • N is "1" as an example, and the number of teeth of the flexible external gear 3 (of the external teeth 31 ) is "2" larger than the number of teeth of the rigid internal gear 2 (of the internal teeth 21 ).
  • Such a difference in the number of teeth of the flexible external gear 3 and the rigid internal gear 2 defines the reduction ratio of the output rotation relative to the input rotation in the harmonic gear device 1 .
  • the rotation is set so that the center of the outer tooth 31 in the tooth line direction D1 faces the center of the inner tooth 21 in the tooth line direction D1.
  • the dimension (tooth width) of the external teeth 31 in the tooth line direction D1 is larger than the dimension (tooth width) of the internal teeth 21 in the tooth line direction D1. Therefore, in the direction parallel to the rotation axis Ax1 , the internal teeth 21 are accommodated within the range of the tooth line of the external teeth 31 .
  • the external teeth 31 protrude in at least one of the tooth line directions D1 with respect to the internal teeth 21 .
  • the external teeth 31 protrude toward both sides (the input side and the output side of the rotation axis Ax1 ) in the tooth line direction D1 with respect to the internal teeth 21 .
  • the pitch circles of the external teeth 31 that draw a perfect circle are set to be larger than those drawn in the same manner.
  • the pitch circle of the perfect circle internal teeth 21 is one circle smaller. That is, in a state where the flexible external gear 3 is not elastically deformed, the external teeth 31 and the internal teeth 21 are opposed to each other with gaps therebetween and do not mesh with each other.
  • the trunk portion 321 is bent into an elliptical shape (non-circular shape)
  • the The external teeth 31 of the flexible external gear 3 partially mesh with the internal teeth 21 of the rigid internal gear 2 . That is, the body portion 321 (at least the end portion on the opening surface 35 side) of the flexible external gear 3 is elastically deformed into an elliptical shape, thereby, as shown in FIG.
  • the teeth 31 mesh with the internal teeth 21 .
  • the major diameter of the pitch circle of the external teeth 31 that draws an ellipse coincides with the diameter of the pitch circle of the inner teeth 21 that draws a perfect circle
  • the minor diameter of the pitch circle of the outer teeth 31 that draws an ellipse is smaller than that of the inner teeth 21 that draws a perfect circle.
  • the diameter of the pitch circle is small.
  • the wave generator 4 is also called a wave generator (wave generator), and is a component that causes the flexible external gear 3 to flex to cause the external teeth 31 of the flexible external gear 3 to produce wave motion.
  • the wave generator 4 has a non-circular outer peripheral shape, specifically an elliptical shape in plan view.
  • the wave generator 4 has a cam 41 having a non-circular shape (here, an ellipse) and a bearing 42 mounted on the outer periphery of the cam 41 . That is, with respect to the bearing 42 , the cam 41 having a non-circular shape (elliptical shape) is fitted inside the inner ring 422 of the bearing 42 to combine the cam 41 . Accordingly, the bearing 42 is elastically deformed into a non-circular shape by receiving an external force from the cam 41 in the radial direction (direction perpendicular to the rotation axis Ax1 ) from the inner side toward the outer side of the inner ring 422 .
  • the state where the bearing 42 is not elastically deformed refers to the state where the cam 41 is not combined with the bearing 42 .
  • the state where the bearing 42 is elastically deformed refers to the state where the cam 41 is combined with the bearing 42 .
  • the cam 41 is a member having a non-circular shape (here, an elliptical shape) driven to rotate around the rotation axis Ax1 on the input side.
  • the cam 41 has an outer peripheral surface 411 (see FIG. 1B ), and at least the outer peripheral surface 411 is formed of an elliptical metal plate in plan view.
  • the cam 41 has a predetermined thickness in the direction of the rotation axis Ax1 (that is, the tooth line direction D1).
  • the cam 41 has the same level of rigidity as the rigid internal gear 2 .
  • the thickness of the cam 41 is smaller (thinner) than that of the rigid internal gear 2 .
  • the rotation of the wave generator 4 is used as the input rotation. Therefore, the input unit 103 of the actuator 100 is attached to the wave generator 4 (see FIG. 4 ).
  • a cam hole 43 for attaching a shaft serving as the input unit 103 is formed at the center of the cam 41 of the wave generator 4 .
  • the bearing 42 has an outer ring 421 , an inner ring 422 and a plurality of rolling elements 423 .
  • the bearing 42 is constituted by a deep groove ball bearing using spherical balls as the rolling elements 423 .
  • Both the outer ring 421 and the inner ring 422 are annular members. Both the outer ring 421 and the inner ring 422 are annular members formed of a relatively thin metal elastic body (metal plate). That is, the outer ring 421 and the inner ring 422 have flexibility because they are relatively thin (thin). In the present embodiment, both the outer ring 421 and the inner ring 422 have a perfect circular ring shape in plan view when the bearing 42 is not elastically deformed (the cam 41 is not combined with the bearing 42 ). The inner ring 422 is one turn smaller than the outer ring 421 and is disposed inside the outer ring 421 .
  • the inner diameter of the outer ring 421 is larger than the outer diameter of the inner ring 422 , a gap is formed between the inner peripheral surface 425 of the outer ring 421 and the outer peripheral surface of the inner ring 422 .
  • a plurality of rolling elements 423 is disposed in a gap between the outer ring 421 and the inner ring 422 .
  • the plurality of rolling elements 423 are arranged in line in the circumferential direction of the outer ring 421 .
  • All the plurality of rolling elements 423 are metal balls (balls) of the same shape, and are arranged at equal intervals over the entire area of the outer ring 421 in the circumferential direction.
  • the bearing 42 further has a cage, and a plurality of rolling elements 423 are held between the outer ring 421 and the inner ring 422 by the cage, although not shown in particular.
  • the dimension in the width direction (direction parallel to the rotation axis Ax1 ) of the outer ring 421 and the inner ring 422 is the same as the thickness of the cam 41 . That is, the dimension in the width direction of the outer ring 421 and the inner ring 422 is smaller than the thickness of the rigid internal gear 2 .
  • the cam 41 and the bearing 42 are combined, the inner ring 422 of the bearing 42 is fixed to the cam 41 , and the inner ring 422 is elastically deformed into an elliptical shape following the outer peripheral shape of the cam 41 .
  • the outer ring 421 of the bearing 42 is elastically deformed into an elliptical shape by being pressed by the inner ring 422 via the plurality of rolling elements 423 . Therefore, both the outer ring 421 and the inner ring 422 of the bearing 42 are elastically deformed into an elliptical shape. In this way, in the state where the bearing 42 is elastically deformed (the state where the cam 41 is combined with the bearing 42 ), the outer ring 421 and the inner ring 422 form elliptical shapes that are similar to each other.
  • the outer peripheral shape of the wave generator 4 having an ellipse shape rotates around the rotation axis Ax1 as its major axis, following the cam. 41 rotations vary.
  • the wave generator 4 configured in this way is disposed inside the flexible external gear 3 .
  • the flexible external gear 3 is connected to the wave generator 4 in such a manner that only the end portion of the inner peripheral surface 301 of the trunk portion 321 on the side opposite to the bottom 322 (opening surface 35 side) is fitted to the wave generator 4 . combination.
  • the bearing 42 of the wave generator 4 is arranged between the outer peripheral surface 411 of the cam 41 and the inner peripheral surface 301 of the flexible external gear 3 .
  • the outer diameter of the outer ring 421 in the state where the bearing 42 is not elastically deformed is the same as the outer diameter of the flexible external gear 3 (the body part 321 ) in the state where the elastic deformation is not generated. ) have the same inner diameter. Therefore, the outer peripheral surface 424 (see FIG. 5 ) of the outer ring 421 in the wave generator 4 is in contact with the inner peripheral surface 301 of the flexible external gear 3 over the entire circumference of the bearing 42 in the circumferential direction.
  • the trunk portion 321 bends into an elliptical shape (non-circular shape).
  • the flexible external gear 3 is fixed to the outer ring 421 of the bearing 42 .
  • the "gap" mentioned in the embodiments of the present disclosure means a space that may be generated between opposing surfaces of two objects, and a gap may be generated between the two objects even if the two objects are not separated. That is, even if two objects are in contact, a gap may be slightly generated between the two objects.
  • a gap is generated between the outer peripheral surface 424 of the outer ring 421 and the inner peripheral surface 301 of the flexible external gear 3 , which are opposed to each other. X1.
  • the outer peripheral surface 424 of the outer ring 421 is in contact with the inner peripheral surface 301 of the flexible external gear 3, there is no large gap X1 therebetween.
  • the gap X1 between the outer ring 421 and the flexible external gear 3 is a small gap that can be locally generated between the outer peripheral surface 424 of the outer ring 421 and the inner peripheral surface 301 of the flexible external gear 3 .
  • a microscopic gap X1 is formed between the outer peripheral surface 424 of the outer ring 421 and the inner peripheral surface 301 of the flexible external gear 3 such that the lubricant Lb1 can penetrate.
  • the harmonic gear device 1 having the above-mentioned structure, as shown in FIG. 2A , by flexing the body part 321 of the flexible external gear 3 into an elliptical shape (non-circular shape), the external teeth 31 of the flexible external gear 3 are relatively The internal teeth 21 of the rigid internal gear 2 are partially meshed. That is, when (the trunk portion 321 of) the flexible external gear 3 is elastically deformed into an elliptical shape, two external teeth 31 corresponding to both ends of the elliptical shape in the long-axis direction mesh with the internal teeth 21 .
  • a wave motion occurs in the external teeth 31 formed on the outer peripheral surface of the flexible external gear 3 .
  • the meshing position of the internal teeth 21 and the external teeth 31 moves in the circumferential direction of the rigid internal gear 2 and generates relative rotation between the flexible external gear 3 and the rigid internal gear 2 . That is, the external teeth 31 mesh with the internal teeth 21 at both ends in the direction of the major axis of the elliptical shape formed by the flexible external gear 3 (the body portion 321 of the flexible external gear 3 ), so that the rotation axis passes through the major axis of the ellipse.
  • Ax1 rotates as a center, the meshing position of the internal teeth 21 and the external teeth 31 moves.
  • the flexible external gear 3 is deformed as the wave generator 4 rotates about the rotation axis Ax1, and a part of the external teeth 31 and a part of the internal teeth 21 are separated. Mesh, and make the flexible external gear 3 rotate according to the tooth number difference between the flexible external gear 3 and the rigid internal gear 2.
  • the difference in the number of teeth between the flexible external gear 3 and the rigid internal gear 2 defines the reduction ratio of the output rotation to the input rotation in the harmonic gear device 1 . That is, when the number of teeth of the rigid internal gear 2 is "V1" and the number of teeth of the flexible external gear 3 is "V2", the speed reduction ratio R1 is expressed by the following formula 1.
  • the deceleration The ratio R1 is "35".
  • the cam 41 rotates clockwise around the rotation axis Ax1 once (360 degrees) when viewed from the input side of the rotation axis Ax1
  • the flexible external gear 3 rotates counterclockwise around the rotation axis Ax1.
  • the amount corresponding to the tooth number difference "2" that is, 10.3 degrees).
  • such a high reduction ratio R1 can be realized by combining the first-stage gears (the rigid internal gear 2 and the flexible external gear 3 ).
  • the harmonic gear device 1 only needs to include at least a rigid internal gear 2, a flexible external gear 3, and a wave generator 4, and may further include, for example, the spline described in the column of "(3.2) Actuator".
  • the bushing 113 and the like are used as structural elements.
  • the actuator 100 of the present embodiment includes the harmonic gear device 1 of the present embodiment, a drive source 101 , and an output unit 102 . That is, the actuator 100 includes a drive source 101 and an output unit 102 in addition to the rigid internal gear 2 , the flexible external gear 3 , and the wave generator 4 constituting the harmonic gear device 1 .
  • the actuator 100 includes an input unit 103 , an input side case 111 , an output side case 112 , a spline bush 113 , and a spacer 114 in addition to the harmonic gear unit 1 , the drive source 101 , and the output unit 102 . , the first stopper 115 , the second stopper 116 and the mounting plate 117 .
  • the actuator 100 further includes input side bearings 118 , 119 , an input side oil seal 120 , output side bearings 121 , 122 , and an output side oil seal 123 .
  • the materials of the actuator 100 other than the driving source 101, the input side oil seal 120 and the output side oil seal 123 are stainless steel, cast iron, carbon steel for mechanical structure, chromium molybdenum steel, phosphor bronze or aluminum bronze. and other metals.
  • the driving source 101 is a power generation source such as a motor (electric motor). Power generated by drive source 101 is transmitted to cam 41 of wave generator 4 in harmonic gear unit 1 . Specifically, the drive source 101 is connected to a shaft as the input unit 103 , and power generated by the drive source 101 is transmitted to the cam 41 via the input unit 103 . Thereby, the drive source 101 can rotate the cam 41 .
  • the output unit 102 is a cylindrical shaft arranged along the rotation axis Ax2 on the output side.
  • the central axis which is the axis of the output unit 102 coincides with the rotation axis Ax2.
  • the output unit 102 is held by the output-side housing 112 so as to be rotatable about the rotation axis Ax2.
  • the output part 102 is fixed to the bottom 322 of the main body part 32 of the flexible external gear 3 , and rotates together with the flexible external gear 3 around the rotation axis Ax2 . That is, the output unit 102 takes out the rotational force of the flexible external gear 3 as an output.
  • the input unit 103 is a cylindrical shaft arranged along the rotation axis Ax1 on the input side.
  • the central axis that is the axis of the input unit 103 coincides with the rotation axis Ax1.
  • the input unit 103 is held by the input-side housing 111 so as to be rotatable about the rotation axis Ax1.
  • the input unit 103 is attached to the cam 41 of the wave generator 4, and rotates together with the cam 41 around the rotation axis Ax1. That is, the input unit 103 transmits power (rotational force) generated by the drive source 101 as an input to the cam 41 .
  • the input side rotation axis Ax1 and the output side rotation axis Ax2 are on the same straight line, so the input unit 103 and the output unit 102 are coaxially located.
  • the input side housing 111 holds the input unit 103 rotatably via input side bearings 118 and 119 .
  • a pair of input-side bearings 118 and 119 are arranged along the rotation axis Ax1 at intervals.
  • the shaft serving as the input part 103 passes through the input side housing 111, and the front end of the input part 103 extends from the input side end surface (the right end surface in FIG. 4 ) of the rotation axis Ax1 in the input side housing 111. protrude.
  • the input side oil seal 120 closes the gap between the input side end surface of the rotation shaft Ax1 of the input side housing 111 and the input portion 103 .
  • the output side housing 112 holds the output unit 102 rotatably via output side bearings 121 and 122 .
  • a pair of output-side bearings 121 and 122 are arranged along the rotation axis Ax2 at intervals.
  • the output side oil seal 123 closes the gap between the output side end surface of the output side housing 112 on the output side of the rotation shaft Ax1 and the output portion 102 .
  • the input-side housing 111 and the output-side housing 112 sandwich the rigid internal gear of the harmonic gear unit 1 from both sides in the direction parallel to the rotation axis Ax1, that is, the tooth line direction D1. 2 combined with each other.
  • the input-side housing 111 contacts the rigid internal gear 2 from the input side of the rotation axis Ax1
  • the output-side housing 112 contacts the rigid internal gear 2 from the output side of the rotation axis Ax1 .
  • the input-side housing 111 passes through the plurality of fixing holes 22 in a state where the rigid internal gear 2 is sandwiched between the output-side housing 112 and is fastened and fixed to the output-side housing 112 by screws (bolts). .
  • the input-side housing 111 , the output-side housing 112 , and the rigid internal gear 2 are joined together and integrated.
  • the rigid internal gear 2 constitutes the outer contour of the actuator 100 together with the input side housing 111 and the output side housing 112 .
  • the spline bushing 113 is a cylindrical member for coupling the shaft serving as the input unit 103 to the cam 41 .
  • the spline bushing 113 is inserted into the cam hole 43 formed in the cam 41 , and the shaft serving as the input unit 103 is inserted into the spline bushing 113 so as to pass through the spline bushing 113 .
  • the movement of the spline bush 113 relative to both the cam 41 and the input unit 103 is restricted in the rotational direction centering on the rotational axis Ax1, and the spline bush 113 can at least move in a direction parallel to the rotational axis Ax1. Move relative to the input unit 103 .
  • a spline connection structure is realized as a connection structure between the input unit 103 and the cam 41 . Therefore, the cam 41 is movable along the rotation axis Ax1 relative to the input unit 103 and rotates together with the input unit 103 around the rotation axis Ax1.
  • the spacer 114 fills the gap between the spline bushing 113 and the cam 41 .
  • the first stopper 115 is a component that prevents the spline bushing 113 from coming off the cam 41 .
  • the first stopper 115 is constituted by, for example, an E-ring, and is attached at a position on the input side of the rotation shaft Ax1 when viewed from the cam 41 in the spline bush 113 .
  • the second stopper 116 is a member that prevents the input portion 103 from coming off the spline bush 113 .
  • the second stopper 116 is formed of, for example, an E-ring, and is attached to the input portion 103 so as to come into contact with the spline bush 113 from the output side of the rotation axis Ax1 .
  • the mounting plate 117 is a member for mounting the shaft as the output unit 102 on the bottom 322 of the flexible external gear 3 .
  • the mounting plate 117 passes through the plurality of mounting holes 33 while sandwiching the peripheral portion of the through hole 34 in the bottom 322 with the flange portion of the output unit 102, and is screwed relative to the flange portion. (Bolts) are fastened.
  • the shaft serving as the output unit 102 is fixed to the bottom portion 322 of the flexible external gear 3 .
  • the lubricant Lb1 is sealed inside the outer contour of the actuator 100 constituted by the input-side housing 111 , the output-side housing 112 , and the rigid internal gear 2 . That is, in the space surrounded by the input-side case 111 , the output-side case 112 , and the rigid internal gear 2 , there is a “lubricant reservoir” capable of storing the liquid or gel-like lubricant Lb1 .
  • the meshing portion of the internal teeth 21 and the external teeth 31, and between the outer ring 421 and the inner ring 422 of the bearing 42, etc. are injected with a liquid or a gel.
  • the lubricant Lb1 is liquid lubricating oil (oil).
  • the lubricant Lb1 also enters the gap X1 between the outer ring 421 (outer peripheral surface 424 ) of the bearing 42 and the flexible external gear 3 .
  • the liquid level of lubricant Lb1 is located below the lower ends of output side bearings 121 and 122 , only in the lower part of the outer contour of actuator 100 ( The lower part in the vertical direction) stores the lubricant Lb1. Therefore, only a part in the rotation direction of the external teeth 31 and the outer ring 421 of the bearing 42 and the like are immersed in the lubricant Lb1 in the state of FIG. 4 . From this state, when the output unit 102 rotates with the rotation of the input unit 103, the outer ring 421 and the flexible external gear 3 also rotate around the rotation axis Ax1. As a result, the outer teeth 31 and the outer ring 421 of the bearing 42 The entirety of the rotation direction of etc. is immersed in the lubricant Lb1.
  • the robot joint device 130 of the present embodiment includes the harmonic gear device 1 of the present embodiment, a first member 131 , and a second member 132 as shown in FIG. 4 . That is, the robot joint device 130 includes a first member 131 and a second member 132 in addition to the rigid internal gear 2 , the flexible external gear 3 , and the wave generator 4 constituting the harmonic gear device 1 .
  • the first member 131 is a member fixed to the rigid internal gear 2
  • the second member 132 is a member fixed to the flexible external gear 3 . Therefore, relative rotation occurs between the flexible external gear 3 and the rigid internal gear 2 in the harmonic gear device 1 , thereby generating relative rotation between the first member 131 and the second member 132 .
  • the joint device 130 for a robot constitutes a connection point when two or more members (the first member 131 and the second member 132 ) are connected (movably connected) in a mutually movable state via the harmonic gear device 1 .
  • first member 131 and the second member 132 may be directly or indirectly fixed to the rigid internal gear 2 and the flexible external gear 3 , respectively.
  • first member 131 is indirectly coupled (fixed) to the rigid internal gear 2 by being coupled to the output side case 112 .
  • the second member 132 is indirectly coupled (fixed) to the flexible external gear 3 by being coupled to the output portion 102 .
  • robot joint device 130 configured in this way, for example, when cam 41 of wave generator 4 is rotated by power generated by drive source 101 , relative rotation occurs between flexible external gear 3 and rigid internal gear 2 . Then, along with the relative rotation of the flexible external gear 3 and the rigid internal gear 2 , between the first member 131 and the second member 132 centering on the output side rotation axis Ax2 (coaxial with the input side rotation axis Ax1 ) produce relative rotation. As a result, according to the joint device 130 for a robot, the first member 131 and the second member 132 connected via the harmonic gear device 1 can be driven so as to relatively rotate about the rotation axis Ax1. Thus, the robot joint device 130 can realize joint mechanisms of various robots.
  • FIG. 5 is an enlarged schematic cross-sectional view of a main part of a range corresponding to FIG. 1B .
  • FIG. 6 is a schematic view of the inner peripheral surface 301 of the flexible external gear 3 viewed from the bearing 42 side of FIG. 5 .
  • the cylindrical inner peripheral surface 301 is actually developed along the circumferential direction D2 of the harmonic gear device 1, and is shown as a plan view in the tooth line direction D1 and the circumferential direction D2 orthogonal to each other.
  • the "circumferential direction D2" mentioned here is the circumferential direction centering on the rotation axis Ax1.
  • the outer ring 421 of the bearing 42 and the through-hole H1 are shown by imaginary lines (two-dot chain line).
  • FIG. 7A is a schematic diagram showing the surface state of the inner peripheral surface 301 of the flexible external gear 3 and the outer peripheral surface 424 of the wave generator 4 (the outer ring 421) in the cross section of the A1-A1 line in FIG. An enlarged schematic view of area Z1 in FIG. 7A .
  • FIG. 7A is a cross section taken along the tooth line direction D1 of the harmonic gear device 1 , and thus corresponds to an enlarged view of a region Z1 in FIG. 5 .
  • 8A is a schematic diagram showing the surface state of the inner peripheral surface 301 of the flexible external gear 3 and the outer peripheral surface 424 of the wave generator 4 (the outer ring 421) in the cross section of the A2-A2 line in FIG.
  • An enlarged schematic diagram of area Z1 in FIG. 8A is a schematic diagram schematically showing changes in the state of the target surface S1 (inner peripheral surface 301 of the flexible external gear 3 ).
  • At least one of the outer ring 421 of the bearing 42 and the external teeth 31 of the flexible external gear 3 is provided with a through hole H1 along the radial direction. It passes through in the direction and is connected to the gap X1 between the outer ring 421 and the flexible external gear 3 . That is, the inner peripheral surface 425 (refer to FIG. 5 ) that is the rolling surface of the plurality of rolling elements 423 in the outer ring 421 of the bearing 42 and the inner peripheral surface 425 (see FIG. 5 ) that is the contact with the internal teeth 21 of the external teeth 31 of the flexible external gear 3 At least one of the outer peripheral surfaces of the engaging surfaces communicates with the gap X1 via the through-hole H1. Therefore, the lubricant Lb1 can be supplied through the gap X1 between the outer ring 421 and the flexible external gear 3 through the through hole H1 .
  • the harmonic gear device 1 of the present embodiment can supply the lubricant Lb1 to the contact portion of the flexible external gear 3 and the wave generator 4 through the through hole H1 by providing the through hole H1, thereby, the contact portion Sufficient lubricant Lb1 is maintained.
  • "lubricant depletion" is prevented, the surface of the contact portion between the outer ring 421 and the flexible external gear 3 is covered with the lubricant Lb1, and the occurrence of fretting wear is suppressed. Therefore, in the harmonic gear device 1 of the present embodiment, troubles caused by fretting wear between the outer ring 421 and the flexible external gear 3 are less likely to occur, and a harmonic gear device that is less likely to cause a decrease in reliability can be provided. 1.
  • the through hole H1 may be provided in at least one of the outer ring 421 and the external teeth 31 of the flexible external gear 3 .
  • the through-holes H1 provided in the outer ring 421 are referred to as "the second The first through hole” and the through hole H2 (see FIG. 12B ) provided in the external teeth 31 of the flexible external gear 3 are called “second through hole”.
  • the through-hole H1 is provided only in the outer ring 421 and the outer ring 421 of the external teeth 31 in the flexible external gear 3 .
  • the through hole H1 includes the “first through hole” provided in the outer ring 421 .
  • the through-hole H2 (second through-hole) on the side of the external teeth 31 of the flexible external gear 3 will be described in "(8) Modification".
  • the “passing through in the radial direction” mentioned in the embodiments of the present disclosure refers to passing through in the radial direction, that is, the direction perpendicular to the rotation axis Ax1 , that is, the radial direction. That is, as long as it is the through-hole H1 provided in the outer ring 421 as in this embodiment, the through-hole H1 may pass through between the inner peripheral surface 425 and the outer peripheral surface 424, which are two surfaces in the radial direction of the outer ring 421, or may be Tilted with respect to, for example, a radial direction.
  • the through hole H1 (first through hole) provided in the outer ring 421 penetrates through the outer ring 421 in the radial direction.
  • one opening surface of the through hole H1 faces the gap X1 between the outer ring 421 and the flexible external gear 3 , and the other opening surface of the through hole H1 opens to the inner peripheral surface 425 of the outer ring 421 . Therefore, one end of the through hole H1 is connected to the gap X1 between the outer ring 421 and the flexible external gear 3 , and the other end is connected to the space between the inner peripheral surface 425 of the outer ring 421 and the outer peripheral surface of the inner ring 422 .
  • the through hole H1 is a circular hole having a circular (perfect circle) cross-sectional shape perpendicular to the radial direction.
  • the center line of the through hole H1 is parallel to the radial direction. That is, the through hole H1 is a hole extending straight in the radial direction from the inner peripheral surface 425 to the outer peripheral surface 424 of the outer ring 421 .
  • the cross-sectional shape of the through hole H1 perpendicular to the radial direction is the same shape over the entire length of the through hole H1 in the radial direction. That is, a cylindrical space is formed inside the through-hole H1.
  • the diameter ⁇ 1 (see FIG. 5 ) of the through hole H1 is the smaller of 0.1 times or less than the diameter ⁇ 2 (see FIG. 5 ) of each of the plurality of rolling elements 423 or 1.0 mm or less.
  • the diameter ⁇ 1 of the through-hole H1 referred to here refers to its diameter when the cross-sectional shape of the through-hole H1 is a perfect circle, and refers to its short diameter when the cross-sectional shape of the through-hole H1 is a non-circular shape (such as an elliptical shape). Axial dimension.
  • the diameter ⁇ 1 of the through hole H1 is not more than 0.1 times the diameter ⁇ 2 of the rolling element 423 and not more than 1.0 mm. According to such a diameter ⁇ 1 of the through hole H1, the lubricant Lb1 can be efficiently supplied to the gap X1 between the H1 outer ring 421 and the flexible external gear 3 through the through hole.
  • the space between the outer ring 421 and the inner ring 422 is connected to the gap X1 between the outer ring 421 and the flexible external gear 3 through the through hole H1, therefore, the space between the outer ring 421 and the inner ring 422
  • the lubricant Lb1 is supplied to the gap X1 through the through hole H1.
  • the flow of the lubricant Lb1 in the through hole H1 is schematically indicated by dotted arrows.
  • the rolling elements 423 function as a pump and can send the lubricant Lb1 between the outer ring 421 and the inner ring 422 into the gap X1 through the through hole H1 .
  • “lubricant depletion” in which the lubricant Lb1 is insufficient or exhausted at the contact portion between the outer ring 421 and the flexible external gear 3 is prevented, and the occurrence of fretting wear is easily suppressed.
  • the harmonic gear device 1 of the present embodiment includes a pump structure for supplying the lubricant Lb1 to the gap X1 through the through hole H1 when the flexible external gear 3 rotates relative to the rigid internal gear 2 .
  • the plurality of rolling elements 423 of the bearing 42 roll in the circumferential direction of the outer ring 421 , so the plurality of rolling elements 423 function as a pump as described above. That is, a plurality of rolling elements 423 constitute a pump structure.
  • the rolling element 423 rolls in the space between the outer ring 421 and the inner ring 422, thereby increasing the pressure in the space between the outer ring 421 and the inner ring 422, so that the outer ring The lubricant Lb1 between 421 and the inner ring 422 is extruded to the side of the gap X1 through the through hole H1.
  • the rolling elements 423 constitute a positive displacement pump such as a vane pump, and squeeze out the lubricant Lb1 to the gap X1 side with sufficient pressure, so that a sufficient amount of the lubricant Lb1 can be easily supplied into the gap X1.
  • the opening surface of the through hole H1 on the inner peripheral surface 425 side of the outer ring 421 opens on the bottom surface of the rolling groove 426 formed in the inner peripheral surface 425 of the outer ring 421 . That is, a rolling groove 426 extending in the circumferential direction over the entire circumference of the outer ring 421 is formed at the center of the inner peripheral surface 425 of the outer ring 421 in the width direction (tooth line direction D1). scroll.
  • the same rolling groove 427 is also formed on the outer peripheral surface of the inner ring 422 , and a plurality of rolling elements 423 are held between these rolling grooves 426 , 427 facing each other so as to be sandwiched.
  • the through holes H1 are arranged in the range where the rolling grooves 426 are formed in the width direction (tooth line direction D1 ) of the outer ring 421 so as to open to the bottom surface of the rolling grooves 426 of the outer ring 421 .
  • the through-hole H1 is arrange
  • the through hole H1 is arranged at the center of the rolling groove 426 in the width direction (tooth line direction D1 ) of the outer ring 421 .
  • the centers of the plurality of rolling elements 423 pass through the opening surface of the through hole H1, so that when the rolling elements 423 rotate, the rolling elements 423 effectively function as pumps, and it is easy to pass through the through hole H1 to the gap X1.
  • the outer ring 421 and the flexible external gear 3 are in contact mainly at both ends of the outer ring 421 in the width direction (tooth line direction D1 ). Therefore, the through-hole H1 is formed at the center of the outer ring 421 in the width direction (tooth line direction D1), so that when the outer ring 421 comes into contact with the flexible external gear 3, the outer ring 421 is less likely to be damaged due to the through-hole H1. reduction in strength.
  • the cross-sectional shape of the rolling grooves 426 and 427 perpendicular to the circumferential direction of the outer ring 421 is formed in an arc shape.
  • the curvature of the circular arc in the cross-sectional shape of the rolling grooves 426 and 427 is larger than the curvature of each of the plurality of rolling elements 423 .
  • the radius of curvature of the arc in the cross-sectional shape of the rolling grooves 426 and 427 is smaller than the radius of curvature of the rolling element 423 .
  • each rolling element 423 is supported at four points in total, which are both end edges of the rolling groove 426 in the outer ring 421 in the width direction (tooth line direction D1 ) and the inner ring 422 . Both ends of the rolling groove 427 in the width direction (tooth line direction D1).
  • the rolling elements 423 are supported by a pair of end edges that are diagonally opposed to each other.
  • the opening surface of the through-hole H1 formed in the bottom surface of the rolling groove 426 faces the surface of the rolling element 423 with the above-mentioned gap therebetween.
  • the opening surface of the through-hole H1 formed in the bottom surface of the rolling groove 426 faces the surface of the rolling element 423 with the above-mentioned gap therebetween.
  • a distance (gap) equal to or greater than a predetermined value is ensured between the opening surface of the through-hole H1 and the rolling element 423, so that the through-hole H1 will not be blocked by rolling elements 423 . Accordingly, even when the plurality of rolling elements 423 pass through the through-hole H1 while rolling, the plurality of rolling elements 423 do not collide with the opening edge of the through-hole H1. As a result, when the rolling elements 423 pass through the through-hole H1, the impact caused by the rolling elements 423 colliding with the opening edge of the through-hole H1 can be avoided, and the outer ring 421, the rolling elements 423, etc. can be easily protected from the impact. .
  • the through hole H1 includes a plurality of first through holes provided in the outer ring 421 so as to be aligned in the circumferential direction of the outer ring 421 .
  • the through-holes H1 are composed only of the first through-holes provided in the outer ring 421 , and therefore, all of the plurality of through-holes H1 are aligned in the circumferential direction of the outer ring 421 .
  • three through-holes H1 are provided in the outer ring 421 .
  • the lubricant Lb1 can be supplied through the gap X1 between the outer ring 421 and the flexible external gear 3 at a plurality of places (three places in the present embodiment) in the circumferential direction of the outer ring 421 through the through hole H1 .
  • the interval P1 of the plurality of through holes H1 is a value other than a multiple of the interval P2 of the plurality of rolling elements 423 .
  • the bearing 42 has 26 rolling elements 423 and the outer ring 421 has three through holes H1.
  • the 26 rolling elements 423 and the three through-holes H1 are respectively provided at equal intervals (equal intervals) in the circumferential direction of the outer ring 421 .
  • the interval P1 is a value expressed by the distance between the centers of two through-holes H1 adjacent in the circumferential direction of the outer ring 421 by an angle around the rotation axis Ax1.
  • the distance between the centers of two adjacent rolling elements 423 is a value represented by an angle around the rotation axis Ax1.
  • the rolling elements 423 do not exist at positions corresponding to all the through holes H1 at the same time. That is, in a state where one rolling element 423 is located at a position corresponding to one through-hole H1, the rolling element 423 is not located at a position corresponding to the other two through-holes H1. Therefore, in the harmonic gear device 1 of the present embodiment, it is possible to avoid a relatively large impact that may occur when a plurality of rolling elements 423 are simultaneously fitted (or pulled out) into a plurality of through-holes H1, and it is easy to protect the outer ring 421. And the rolling elements 423 etc. are protected from impact. In addition, the pumping action by the rolling of the rolling elements 423 is also more efficient than when the rolling elements 423 are positioned on all the through holes H1 at the same time.
  • the chemical conversion treatment coating C1 is provided on the target surface S1 constituted by the inner peripheral surface 301 of the flexible external gear 3 . That is, by subjecting the inner peripheral surface 301 of the flexible external gear 3 as the target surface S1 to chemical conversion treatment, chemical conversion is formed so as to cover the target surface S1 (the inner peripheral surface 301 of the flexible external gear 3 ).
  • the chemical conversion treatment coating C1 is a phosphate coating formed by chemical conversion treatment (Parkerizing treatment) using phosphate.
  • Such a chemical conversion treatment coating C1 is formed on the outermost surface of the target surface S1 (the inner peripheral surface 301 of the flexible external gear 3 in this embodiment).
  • the chemical conversion treatment coating C1 is made of a material softer than at least the target surface S1 itself. That is, the hardness of the chemical conversion coating C1 is lower than the hardness of parts of the target surface S1 other than the chemical conversion coating C1 .
  • the surface hardness of the chemical conversion coating C1 is lower (softer) than that of the flexible external gear 3 and the outer ring 421 of the bearing 42 of the wave generator 4 .
  • the chemical conversion treatment coating C1 interposed therebetween serves as a buffer, and damage to the flexible external gear 3 and the wave generator 4 can be suppressed.
  • the flexible external gear 3 and the wave generator 4 are assembled or when the harmonic gear device 1 is initially used, etc., at the contact portion of the flexible external gear 3 and the wave generator 4, there is a phenomenon called "bite". In the case of local adhesive wear of "connection" (galling).
  • the relatively low-hardness chemical conversion treatment coating C1 is peeled (peeled off) from the target surface S1, so that the flexible external gear 3 And the growth of wear of the wave generator 4 is suppressed, which is beneficial to the protection of the flexible external gear 3 and the wave generator 4 .
  • the chemical conversion treatment coating C1 is a porous coating having many fine pores (microscopic pores) during its formation (chemical conversion treatment). Therefore, the chemical conversion treatment coating C1 can soak the lubricant Lb1 like a sponge by introducing the lubricant Lb1 (see FIG. 4 ) into the pores. Then, the lubricant Lb1 soaked in the chemical conversion treatment coating C1 seeps out from the chemical conversion treatment coating C1 appropriately according to temperature, pressure, and the like. In this way, the chemical conversion treatment coating C1 is configured to be able to hold the lubricant Lb1. Therefore, the lubricant is likely to remain in the contact portion of the Lb1 flexible external gear 3 with the wave generator 4 , and sufficient lubricant Lb1 can be maintained at the contact portion.
  • the inner peripheral surface 301 of the flexible external gear 3 on which the chemical conversion treatment coating C1 is formed is always maintained with lubricating performance by the lubricant Lb1.
  • the chemical conversion treatment film C1 is different from a self-low-friction film such as diamond-like carbon (DLC: Diamond-Like Carbon), and realizes the flexible external gear 3 and the wave generator 4 by holding the lubricant Lb1. low-friction contact between them. Therefore, as long as the chemical conversion treatment coating C1 in the state of holding the lubricant Lb1 exists in the gap X1 between the flexible external gear 3 and the wave generator 4, the flexible external gear 3 can be realized for a long period of time using the lubricant Lb1. Low-friction contact with the wave generator 4.
  • DLC Diamond-Like Carbon
  • the chemical conversion treatment coating C1 may peel (peel off) from the target surface S1 due to abrasion such as "seizing". Therefore, in the harmonic gear device 1 in which contamination of foreign matter (contamination) may be a problem, the chemical conversion treatment coating C1 cannot generally be employed.
  • the chemical conversion treatment coating after peeling (peeling) is adopted. C1 leaves the following structure in the gap X1 (between the flexible external gear 3 and the wave generator 4 ).
  • the groove 303 capable of holding at least the chemical conversion treatment coating C1 is formed on the target surface S1 .
  • a plurality of grooves 303 are formed on the inner peripheral surface 301 (target surface S1 ) facing the gap X1 in the flexible external gear 3 .
  • Concavities and convexities are formed on the target surface S1 by the plurality of grooves 303 . That is, the portion of the target surface S1 where the groove 303 is formed becomes a relatively concave recess, and the portion where the groove 303 is not formed becomes a relatively protruding protrusion 304 (see FIG. 7A ).
  • the target surface S1 can hold the chemical conversion treatment coating C1 (after peeling off) in the groove 303 which is a concave portion.
  • the groove 303 is formed by utilizing the processing marks generated on the inner peripheral surface 301 of the flexible external gear 3 by honing. That is, in the honing process, mesh-shaped (twill-shaped) scratch marks called "cross-hatching" remain on the polished surface.
  • the cross hatching is composed of a plurality of first grooves 303 a and a plurality of second grooves 303 b intersecting at an intersection angle of 20 degrees or more and 60 degrees or less, and is formed on the inner peripheral surface of the honed flexible external gear 3 Roughly the entire area of the 301.
  • the plurality of grooves 303 extend in both the tooth line direction D1 and the circumferential direction D2 on the inner peripheral surface 301 of the flexible external gear 3 , and define a plurality of convex portions 304 that are rhombus-shaped in plan view. That is, the slots 303 include first slots 303 a and second slots 303 b intersecting each other.
  • the lubricant Lb1 can easily spread over a relatively wide range in the gap X1. That is, the lubricant Lb1 infiltrated into the chemical conversion treatment coating C1 easily diffuses in both the tooth line direction D1 and the circumferential direction D2 in the gap X1 through the groove 303 .
  • the lubricant Lb1 can be expected to diffuse in the tooth line direction D1 and the circumferential direction D2 due to, for example, capillarity.
  • the mesh-like groove 303 includes the first groove 303a and the second groove 303b intersecting each other as cross-hatched, the lubricant Lb1 not only easily spreads in either the tooth line direction D1 or the circumferential direction D2, but also And it is easy to spread to both of them.
  • the target surface S1 (the inner periphery of the flexible external gear 3 in this embodiment) formed by shearing metal crystal grains such as cutting, grinding, or honing, surface 301), producing a plurality of grooves 303.
  • scaly "burrs" protrusions
  • the boundary between the concavo-convex (groove 303 and convex portion 304 ) has a rounded shape, so that, for example, “snitching” is less likely to occur at the initial stage of use of the harmonic gear device 1 .
  • the chemical conversion treatment coating C1 is formed so as to cover the entire area of the target surface S1 on the target surface S1 subjected to shot peening, barrel grinding, or the like in this way. That is, the chemical conversion treatment coating C1 is seamlessly formed on both the inner surface of the groove 303 and the surface of the convex portion 304 as shown in FIGS. 7A to 8B .
  • the thickness L2 of the chemical conversion treatment coating C1 is smaller than the depth L1 of the groove 303 .
  • the depth L1 of the groove 303 referred to here is the distance from the convex portion 304 to the bottom of the groove 303 .
  • the depth L1 of the groove 303 is not less than 2 ⁇ m and not more than 8 ⁇ m, and the thickness L2 of the chemical conversion treatment film C1 is not less than 1 ⁇ m and not more than 5 ⁇ m.
  • the thickness L2 of the chemical conversion treatment coating C1 is 3 ⁇ m.
  • the thickness L2 of the chemical conversion coating C1 smaller than the depth L1 of the groove 303, the entire thickness of the chemical conversion coating C1 is accommodated in the groove 303, and the outer peripheral surface 424 of the wave generator 4 and the groove 303 are suppressed.
  • the chemical conversion treatment film C1 in the tank 303 contacts.
  • the thickness L2 of the chemical conversion coating C1 is greater than that of the flexible external gear 3 when the wave generator 4 is combined with the flexible external gear 3 in the state where the chemical conversion coating C1 is removed.
  • the gap generated between the wave generator 4 is small. That is, the thickness L2 of the chemical conversion treatment coating C1 is smaller than the distance between the flexible external gear 3 and the wave generator 4 in the state P11 of FIG. 9 .
  • the chemical conversion treatment coating C1 is less likely to be compressed. Damaged under action.
  • the surface state of the inner peripheral surface 301 of the flexible external gear 3 changes as shown in FIG. 9 as the harmonic gear device 1 is used.
  • 9 shows the state P11 before the chemical conversion coating C1 is formed, the state P12 after the chemical conversion coating C1 is formed and before the use of the harmonic gear device 1 starts, and the state where the chemical conversion coating C1 is partially worn. P13, and a state P14 in which the chemical conversion treatment coating C1 is further worn.
  • the chemical conversion treatment coating C1 is uniformly provided on the target surface S1 (in this embodiment, the inner circumference of the flexible external gear 3). Both the groove 303 and the protrusion 304 in the surface 301).
  • the cam 41 of the wave generator 4 rotates to elastically deform the outer ring 421 and the flexible external gear 3, and along with this, the outer ring 421 and the flexible external gear 3 are elastically deformed. Relative rotation may occur between the external gears 3 . This relative rotation is, for example, about a few thousandths or a few hundredths of the rotation speed of the cam 41.
  • the peeled chemical conversion treatment coating C10 remains between the wave generator 4 (outer ring 421) and the flexible external gear 3 by being held in the groove 303.
  • the hardness of the chemical conversion treatment film C1 is lower than the hardness of either the flexible external gear 3 or the outer ring 421 of the bearing 42 of the wave generator 4 as described above. Therefore, even if the peeled chemical conversion treatment coating C1 leaks (overflows) from the gap X1 between the flexible external gear 3 and the wave generator 4, the foreign matter made of the chemical conversion treatment coating C1 is relatively soft. In short, by using the foreign matter caused by abrasion that tends to occur at the initial stage of use of the harmonic gear device 1 as the soft foreign matter coming out of the relatively soft chemical conversion treatment coating C1, for example, even if the foreign matter enters the bearing 42, it is possible to suppress damage to the bearing 42. Damage to bearing 42. As a result, for example, the amount of generation of hard foreign matter that damages the bearing 42 and the like is suppressed.
  • the surface hardness of the internal teeth 21 is lower than that of the external teeth 31 . That is, the hardness of the surface of the external teeth 31 is higher (harder) than that of the internal teeth 21 .
  • the "hardness” mentioned in the embodiments of the present disclosure refers to the degree of hardness of an object, for example, the hardness of a metal is represented by the size of a depression formed by pushing a steel ball with a certain pressure.
  • examples of the hardness of metals include Rockwell hardness (HRC), Brinell hardness (HB), Vickers hardness (HV), and Shore hardness (Hs).
  • HRC Rockwell hardness
  • HB Brinell hardness
  • HV Vickers hardness
  • Hs Shore hardness
  • hardness is represented by Vickers hardness (HV).
  • As a method of increasing (hardening) the hardness of a metal member there are, for example, alloying or heat treatment.
  • the surface of the external teeth 31 of the flexible external gear 3 is made of a material with high hardness and high toughness (toughness), and the internal teeth 21 of the rigid internal gear 2 are made of a material with a hardness lower than that of the external teeth 31 .
  • the following material is used for the external teeth 31, that is, a material obtained by heat-treating (quenching and tempering) nickel-chromium-molybdenum steel specified as "SNCM439" in Japanese Industrial Standards (JIS: Japanese Industrial Standards) .
  • Spherical graphite cast iron specified as "FCD800-2" in Japanese Industrial Standards (JIS) is used for the internal teeth 21 .
  • the surface hardness of the internal teeth 21 which is relatively low in hardness compared with the external teeth 31 , is preferably HV350 or less.
  • the surface hardness of the internal teeth 21 is selected within the range of HV250 or more and less than HV350.
  • the lower limit of the surface hardness of the internal teeth 21 is not limited to HV250, and may be, for example, HV150, HV160, HV170, HV180, HV190, HV200, HV210, HV220, HV230, or HV240.
  • the upper limit of the surface hardness of the internal teeth 21 is not limited to HV350, and may be, for example, HV360, HV370, HV380, HV390, HV400, HV410, HV420, HV430, HV440, or HV450.
  • the surface hardness of the external teeth 31 which is relatively harder than the internal teeth 21 , is preferably HV380 or higher.
  • the surface hardness of the external teeth 31 is selected within the range of not less than HV380 and not more than HV450.
  • the lower limit of the surface hardness of the external teeth 31 is not limited to HV380, and may be, for example, HV280, HV290, HV300, HV310, HV320, HV330, HV340, HV350, HV360, or HV370.
  • the upper limit of the surface hardness of the internal teeth 21 is not limited to HV450, and may be, for example, HV460, HV470, HV480, HV490, HV500, HV510, HV520, HV530, HV540, or HV550.
  • the difference between the surface hardness of the internal teeth 21 and the surface hardness of the external teeth 31 is HV50 or more. That is, the surface hardness of the external teeth 31 is set to be higher than the surface hardness of the internal teeth 21 by HV50 or more. In short, for example, if the surface hardness of the internal teeth 21 is HV350, the surface hardness of the external teeth 31 is HV400 or more. In addition, if the surface hardness of the external teeth 31 is HV380, the surface hardness of the internal teeth 21 is HV330 or less.
  • the difference between the surface hardness of the internal teeth 21 and the surface hardness of the external teeth 31 is not limited to HV50 or greater, and may be, for example, HV20 or greater, HV30 or greater, or HV40 or greater. Furthermore, the difference between the surface hardness of the internal teeth 21 and the surface hardness of the external teeth 31 is preferably large, for example, more preferably HV60 or higher, HV70 or higher, HV80 or higher, HV90 or higher, or HV100 or higher. If the difference between the surface hardness of the internal teeth 21 and the surface hardness of the external teeth 31 is HV100 or more, when the surface hardness of the internal teeth 21 is HV350, the surface hardness of the external teeth 31 is HV450 or more.
  • the surface hardness of the internal teeth 21 is set lower than the surface hardness of the external teeth 31 . Therefore, when the internal teeth 21 contact the external teeth 31 during operation of the harmonic gear device 1 , the internal teeth 21 having a relatively lower surface hardness than the external teeth 31 are actively worn. When two members (the inner teeth 21 and the outer teeth 31 ) having different surface hardnesses contact each other, the wear of the relatively soft inner teeth 21 is accelerated, and the wear of the relatively hard outer teeth 31 is suppressed.
  • the tooth surfaces of the internal teeth 21 are moderately worn, thereby increasing the actual contact area between the internal teeth 21 and the external teeth 31 and reducing the surface pressure, making it difficult to Wear of the external teeth 31 occurs.
  • the surface hardness of the internal teeth 21 is HV350 or less as in the present embodiment, even if foreign matter occurs due to chipping or wear of the internal teeth 21 due to the contact between the internal teeth 21 and the external teeth 31, the foreign matter is relatively soft. quality.
  • the harmonic gear device 1 by using the foreign matter caused by wear that is likely to occur at the initial stage of use of the harmonic gear device 1 as a soft foreign matter that comes out of the relatively soft internal teeth 21, for example, even if the foreign matter enters the bearing 42, it is possible to suppress damage to the bearing 42. damage. As a result, for example, the amount of generation of hard foreign matter that greatly damages the bearing 42 is suppressed. Especially when the difference between the surface hardness of the internal teeth 21 and the surface hardness of the external teeth 31 is a relatively large value such as HV50 or more, the above-mentioned effect is remarkable.
  • the surface hardness of the internal teeth 21 and the external teeth 31 does not have to be specified by Vickers hardness (HV), and can also be specified by other hardness, such as Rockwell hardness (HRC), Brinell hardness (HB) or Shore hardness (Hs).
  • HV Vickers hardness
  • HRC Rockwell hardness
  • HB Brinell hardness
  • Hs Shore hardness
  • the surface hardness of the internal teeth 21 is preferably HRC30 or less.
  • the surface hardness of the internal teeth 21 is selected within a range of not less than HRC20 and less than HRC30.
  • the lower limit of the surface hardness of the internal teeth 21 is not limited to HRC20, and may be, for example, HRC10, HRC15, or HRC25.
  • the upper limit of the surface hardness of the internal teeth 21 is not limited to HRC30, and may be, for example, HRC35, HRC40, or HRC45.
  • the surface hardness of the external teeth 31 is preferably HRC40 or higher.
  • the surface hardness of the external teeth 31 is selected within the range of not less than HRC40 and not more than HRC60.
  • the lower limit of the surface hardness of the external teeth 31 is not limited to HRC40, and may be, for example, HRC30, HRC35, or the like.
  • the upper limit of the surface hardness of the external teeth 31 is not limited to HRC60, and may be, for example, HRC50, HRC55, HRC65, HRC70, or HRC75.
  • the target surface S1 constituted by at least one of the outer peripheral surface 424 of the wave generator 4 and the inner peripheral surface 301 of the flexible external gear 3 is provided with a By chemically converting the coating C1, a sufficient lubricant Lb1 can be maintained at the contact portion between the flexible external gear 3 and the wave generator 4. Therefore, the surface of the contact portion of the flexible external gear 3 with the bearing 42 (the outer ring 421 ) is covered with the lubricant Lb1, and the occurrence of fretting wear is suppressed. The generation of hard foreign matter coming out of the gear 3 or the outer ring 421.
  • the damage caused by relatively hard foreign matter entering the bearing 42 is less likely to occur, and the reduction in reliability is less likely to occur especially during long-term use, so that the transmission efficiency of the harmonic gear device 1 is further improved. Improvement, long life and high performance.
  • the internal teeth 21 have a dedendum 212 and a dedendum 213 as shown in FIG. 1B .
  • the internal teeth 21 are provided on the inner peripheral surface of the rigid internal gear 2, so the dedendum 212 of the internal teeth 21 corresponds to the inner peripheral surface of the rigid internal gear 2, and the addendum 213 faces inward from the inner peripheral surface of the rigid internal gear 2 (the rigid internal gear 2 center of gear 2) protrudes.
  • the external tooth 31 has a dedendum 312 and a dedendum 313 as shown in FIG. 1B .
  • the external teeth 31 are arranged on the outer peripheral surface of the flexible external gear 3 (the body part 321), so the dedendum 312 of the external teeth 31 is equivalent to the outer peripheral surface of the flexible external gear 3 (the body part 321), and the addendum 313 is from the flexible external gear 3 (the body part 321).
  • the outer peripheral surface of (the body part 321 of) the external gear 3 protrudes outward.
  • the crests 313 of the external teeth 31 are inserted between adjacent pairs of crests 213 of the internal teeth 21 , so that the internal teeth 21 and the external teeth 31 are meshed.
  • the dedendum 313 of the external tooth 31 is opposed to the dedendum 212 of the internal tooth 21
  • the dedendum 213 of the internal tooth 21 is opposed to the dedendum 312 of the external tooth 31 .
  • the internal teeth 21 have chamfered portions 211 at both end portions in the tooth line direction D1.
  • the chamfered portion 211 is a C surface obtained by reducing the protruding amount of the internal teeth 21 toward both sides in the tooth line direction D1 , and is basically a portion that does not contribute to the meshing of the internal teeth 21 and the external teeth 31 . That is, the chamfered portion 211 of the internal tooth 21 does not contact the external tooth 31 even at the meshing position of the internal tooth 21 and the external tooth 31 .
  • the external teeth 31 have chamfered portions 311 at both end portions in the tooth line direction D1.
  • the chamfered portion 311 is a C surface obtained by reducing the protruding amount of the internal teeth 21 toward both sides in the tooth line direction D1 , and is basically a portion that does not contribute to the meshing of the internal teeth 21 and the external teeth 31 . That is, the chamfered portion 311 of the external tooth 31 does not contact the internal tooth 21 even at the meshing position between the internal tooth 21 and the external tooth 31 .
  • the internal teeth 21 of the rigid internal gear 2 have tooth line trimming portions 210 . That is, in the harmonic gear device 1 , at least the internal teeth 21 are subjected to tooth line dressing.
  • the tooth line trimming portion 210 of the internal teeth 21 is provided at at least one end in the tooth line direction D1.
  • the inner tooth 21 has the tooth line trimming portion 210 at least one end portion of the internal tooth 21 in the tooth line direction D1.
  • the tooth line trimming portion 210 is provided at both ends of the internal tooth 21 in the tooth line direction D1.
  • the external teeth 31 of the flexible external gear 3 also have tooth line trimming portions 310 . That is, in the harmonic gear device 1 , not only the internal teeth 21 but also the external teeth 31 are subjected to tooth line dressing.
  • the tooth line trimming portion 210 of the external teeth is provided at at least one end portion in the tooth line direction D1.
  • the external teeth 31 have the tooth line trimming portion 310 on at least one end portion of the external teeth 31 in the tooth line direction D1.
  • the tooth line trimming portion 310 is provided at both ends of the external teeth 31 in the tooth line direction D1.
  • the harmonic gear device 1 of the present embodiment at least one of the internal teeth 21 and the external teeth 31 has the tooth line trimming portion 210 , 310 .
  • the tooth line trimmers 210 and 310 make it difficult to generate stress concentration due to excessive tooth contact between the internal teeth 21 and the external teeth 31 , and as a result, the tooth contact between the internal teeth 21 and the external teeth 31 can be improved. Therefore, foreign matter due to chipping or abrasion due to contact between the internal teeth 21 and the external teeth 31 is less likely to occur, and it is possible to realize the harmonic gear device 1 that is less likely to decrease in reliability.
  • the contact between the flexible external gear 3 and the wave generator 4 Parts may experience fretting wear. Moreover, if fretting wear occurs, it may cause roughness of the surface, rust caused by abrasive powder, and damage to the wave generator 4 (the bearing 42) caused by the abrasive powder entering the inside of the wave generator 4, etc. This affects the reliability of the harmonic gear device 1 .
  • the cause of such fretting wear is considered to be "lubricant depletion" in which the lubricant Lb1 is insufficient or exhausted at the contact portion between the flexible external gear 3 and the wave generator 4 . That is, it can be estimated that the contact portion between the flexible external gear 3 and the wave generator 4 is originally in an environment where fretting wear is likely to occur due to microvibration between the contact surfaces in a state where the lubricant Lb1 is insufficient. environment. Specifically, the following two reasons can be considered as the reason why such fretting wear is likely to occur in an environment.
  • the first reason is that the flexible external gear 3 frequently repeats elastic deformation. That is to say, during one rotation of the cam 41 of the wave generator 4, the flexible external gear 3 repeats two elastic deformations with the long axis of the ellipse in one direction (for example, the vertical direction in FIG. 2A ). Therefore, when the cam 41 rotates at high speed, the flexible external gear 3 is elastically deformed repeatedly at high speed, and vibrations are likely to be generated at the contact portion between the flexible external gear 3 and the wave generator 4 as the elastic deformation is repeated. As a result, microvibration occurs in a state where the lubricant Lb1 is insufficient at the contact portion between the flexible external gear 3 and the wave generator 4 .
  • the end of the flexible external gear 3 on the opening surface 35 side in the direction of the rotation axis Ax1 deforms more than the end on the bottom 322 side. , and become a shape closer to an ellipse shape. Therefore, in the state where the flexible external gear 3 is elastically deformed, the inner peripheral surface 301 of the body portion 321 of the flexible external gear 3 includes a tapered surface inclined by an inclination angle ⁇ 1 with respect to the rotation axis Ax1 as shown in FIG. 10 . 302. Furthermore, the inclination angle ⁇ 1 of the tapered surface 302 changes with the elastic deformation of the flexible external gear 3 .
  • the inclination angle ⁇ 1 of the tapered surface 302 is the largest at both ends of the ellipse in the major axis direction ("major axis side" in FIG. 10 ),
  • the inclination angle ⁇ 1 of the tapered surface 302 is the smallest at both ends in the minor axis direction of the ellipse ("minor axis side” in FIG. 10 ). Therefore, the inclination angle ⁇ 1 of the tapered surface 302 also changes at high speed due to the frequent and repeated elastic deformation of the flexible external gear 3, whereby the inner peripheral surface 301 (tapered surface 302) of the flexible external gear 3 repeatedly impacts the outer ring.
  • the outer peripheral surface 424 of 421 vibrates. As described above, microvibrations accompanying impacts are generated, and as a result, fretting wear is likely to occur at the contact portion between the flexible external gear 3 and the wave generator 4 .
  • the second reason is that the relative rotation between the outer ring 421 and the flexible external gear 3 is at a low speed. That is to say, under the influence of the gap X1 between the outer ring 421 and the flexible external gear 3, the cam 41 of the wave generator 4 rotates and the outer ring 421 and the flexible external gear 3 elastically deform. Relative rotation may occur between the ring 421 and the flexible external gear 3 . However, this relative rotation is, for example, a low-speed rotation of about a few thousandths or a few hundredths of the rotation speed of the cam 41 .
  • the lubricant Lb1 cannot be expected to flow due to the relative rotation, and it is disadvantageous to form a film (oil film) of the lubricant Lb1 at the contact portion. environment of. However, since relative rotation may occur between the outer ring 421 and the flexible external gear 3 , the outer ring 421 and the flexible external gear 3 rub against each other, creating an environment where fretting wear easily occurs.
  • the lubricant Lb1 can be forcibly supplied to the contact portion between the outer ring 421 and the flexible external gear 3 in an environment where fretting wear is likely to occur. That is, the harmonic gear device 1 can supply the lubricant Lb1 to the contact portion of the flexible external gear 3 and the wave generator 4 through the through hole H1 , thereby maintaining sufficient lubricant Lb1 at the contact portion. In this way, occurrence of fretting wear is suppressed by preventing "lubricant depletion" in which the lubricant Lb1 is insufficient or exhausted at the contact portion between the outer ring 421 and the flexible external gear 3 .
  • the target surface S1 constituted by at least one of the outer peripheral surface 424 of the wave generator 4 and the inner peripheral surface 301 of the flexible external gear 3 is provided with a chemical conversion treatment coating.
  • the harmonic gear device 1 of the present embodiment As a result, the surface of the contact portion between the outer ring 421 and the flexible external gear 3 is covered with the lubricant Lb1, and the occurrence of fretting wear is suppressed. Therefore, in the harmonic gear device 1 of the present embodiment, troubles caused by fretting wear between the outer ring 421 and the flexible external gear 3 are less likely to occur, and a harmonic gear device that is less likely to cause a decrease in reliability can be provided. 1. In addition, the harmonic gear device 1 of the present embodiment is less prone to reliability degradation, especially during long-term use, so that the transmission efficiency, longer life, and higher performance of the harmonic gear device 1 are further brought about.
  • the harmonic gear device 1 since the lubricant Lb1 is supplied to the contact portion between the outer ring 421 and the flexible external gear 3, it is difficult to hinder the deformation followability of the flexible external gear 3, resulting in improvement of power transmission efficiency, Longer life due to reduction of the load applied to the bearing 42 and the like. Moreover, since the wear powder generated by fretting wear is also prevented from entering the bearing 42, etc., the occurrence of damage starting from the indentation formed by the bite of the wear powder (flaking of the surface origin type) is also reduced. . Therefore, as the harmonic gear device 1 , a longer life and higher performance can be expected.
  • the through-hole H1 is provided so that when the eye-catching portion of the outer ring 421 passes through the lubricant reservoir, lubrication is replenished only through the gap between the outer ring 421 and the inner ring 422 .
  • lubricant Lb1 the lubricant Lb1 can also be supplied to the gap X1. That is, since the lubricant Lb1 replenished between the outer ring 421 and the inner ring 422 is supplied to the gap X1 through the through hole H1, friction at the contact portion with the flexible external gear 3 is less likely to occur on the entire circumference of the outer ring 421. "Lubricant exhausted".
  • the rolling elements 423 when the bearing 42 operates to rotate the plurality of rolling elements 423 , the rolling elements 423 function as a pump, whereby the lubricant Lb1 can be forcibly sent into the gap X1 through the through hole H1 .
  • the chemical conversion treatment coating C1 is provided on the target surface S1 constituted by at least one of the outer peripheral surface 424 of the wave generator 4 and the inner peripheral surface 301 of the flexible external gear 3 . According to these configurations, the lubricant Lb1 supplied to the gap X1 via the through hole H1 is likely to remain on the inner peripheral surface 301 of the flexible external gear 3, and the depletion of the lubricant in the gap X1 can be efficiently eliminated.
  • the rapid change of the inclination angle ⁇ 1 of the tapered surface 302 due to repeated elastic deformation of the flexible external gear 3 also contributes to the diffusion of the lubricant Lb1 in the gap X1.
  • the startability of the harmonic gear device 1 can be improved in a low-temperature environment where the lubricant Lb1 is likely to solidify, for example.
  • FIG. 11 is a cross-sectional view showing an example of a robot 9 using the harmonic gear device 1 according to this embodiment.
  • the robot 9 is a horizontal multi-joint robot, a so-called SCARA (Selective Compliance Assembly Robot Arm) type robot.
  • SCARA Selective Compliance Assembly Robot Arm
  • the robot 9 includes two robot joint devices 130 (including the harmonic gear device 1 ) and a link 91 .
  • the two robot joint devices 130 are respectively provided at the joints of two places in the robot 9 .
  • the link 91 connects the two robot joint devices 130 .
  • the harmonic gear unit 1 is not a cup-shaped harmonic gear unit but a hat-shaped harmonic gear unit. That is, in the harmonic gear device 1 illustrated in FIG. 11 , the flexible external gear 3 formed in the shape of a top hat is used.
  • a surface processing step of processing the surface of the outer ring 421 (in particular, the inner peripheral surface 425 serving as the rolling surface) after the drilling step of forming the through-hole H1. That is, it is preferable that compressive residual stress remains around the through-hole H1 in the outer ring 421 so that the through-hole H1 does not become a starting point of cracking of the outer ring 421 . For this reason, it is preferable to form the through-hole H1 before performing a surface processing step such as quenching on the outer ring 421 so that compressive residual stress due to heat treatment remains.
  • the periphery of the through hole H1 in the outer ring 421 may be subjected to processing such as shot peening in which the surface is modified and solidified by projecting a small spherical projection, thereby improving the appearance. Fatigue strength of ring 421.
  • Embodiment 1 is just one of various implementations of the embodiments of the present disclosure. Embodiment 1 Various changes can be made according to the design, as long as the purpose of the embodiments of the present disclosure can be achieved.
  • the drawings referred to in the embodiments of the present disclosure are all schematic drawings, and the size and thickness ratios of the structural elements in the drawings do not necessarily reflect the actual size ratio. Modified examples of the first embodiment are listed below. Modifications described below can be applied in combination as appropriate.
  • the through hole H1 may be at a position deviated from the center of the plurality of rolling elements 423 in the direction parallel to the rotation axis Ax1 (tooth line direction D1).
  • the through hole H1 is disposed at a position deviated from the center of the rolling element 423 toward the opening surface 35 , that is, at a position between the center of the rolling element 423 and the opening surface 35 in the tooth line direction D1 .
  • the through-hole H1 may be provided in a plurality of places in the direction (tooth line direction D1) parallel to the rotation axis Ax1.
  • the opening area of the through hole H1 on the side of the gap X1 may be smaller than the opening area of the through hole H1 on the side opposite to the gap X1. That is, in the (first) through-hole H1 provided in the outer ring 421 , the opening area of the through-hole H1 on the side of the gap X1 , that is, the outer peripheral surface 424 , is larger than that of the through-hole H1 on the side opposite to the gap X1 , that is, the inner peripheral surface 425 .
  • the side opening area is small. Thereby, the pressure of the lubricant Lb1 supplied to the gap X1 through the through hole H1 can be increased.
  • FIGS. 12A and 12B are cross-sectional views showing modifications of the first embodiment, and corresponding to FIGS. 1A and 1B .
  • (second) through holes H2 are provided in the external teeth 31 of the flexible external gear 3 .
  • the through-holes H include "second through-holes" provided in the external teeth 31 of the flexible external gear 3.
  • the through-hole H2 provided in the part of the external teeth 31 of the flexible external gear 3, that is, the through-hole H2 provided in the position corresponding to the bearing 42 in the direction of the rotation axis Ax1, passes the flexible external gear 3 in the radial direction. .
  • one opening surface of the through hole H2 faces the gap X1 between the outer ring 421 and the flexible external gear 3 , and the other opening surface of the through hole H2 becomes the same as that of the external teeth 31 of the flexible external gear 3 .
  • the outer peripheral surfaces of the meshing surfaces of the internal teeth 21 are open. Therefore, one end of the through hole H2 is connected to the gap X1 between the outer ring 421 and the flexible external gear 3 , and the other end is connected to the space between the outer teeth 31 and the inner teeth 21 . Therefore, the space between the external teeth 31 and the internal teeth 21 communicates with the gap X1 between the outer ring 421 and the flexible external gear 3 via the through hole H2. Therefore, the lubricant Lb1 in the space between the external teeth 31 and the internal teeth 21 can be supplied to the gap X1 between the outer ring 421 and the flexible external gear 3 through the through hole H2.
  • the external teeth 31 and the internal teeth 21 constitute a positive displacement pump such as a vane pump, and squeeze out the lubricant Lb1 to the gap X1 side with sufficient pressure, so that sufficient lubricant Lb1 can be easily supplied into the gap X1.
  • the (second) through hole H2 is located between the center of the external teeth 31 and the end on the opening surface 35 side in a direction parallel to the rotation axis Ax1 (tooth line direction D1 ).
  • the (second) through hole H2 is arranged at the dedendum 312 and the dedendum 313 of the dedendum 313 of the external teeth 31 .
  • the through holes H1 and H2 may be provided on both the outer ring 421 and the external teeth 31 of the flexible external gear 3 .
  • the lubricant Lb1 in the space between the outer ring 421 and the inner ring 422 of the bearing 42 can be supplied to the gap X1 between the outer ring 421 and the flexible external gear 3 through the through hole H1.
  • the lubricant Lb1 in the space between the external teeth 31 and the internal teeth 21 can be supplied to the gap X1 between the outer ring 421 and the flexible external gear 3 through the through-hole H2. Therefore, the lubricant Lb1 can be supplied to the gap X1 from both sides (inside and outside) in the radial direction.
  • the (first) through hole H1 and the (second) through hole H2 preferably have different positions in the tooth line direction D1 of the inner teeth 21 .
  • the harmonic gear device 1 it is not an essential configuration of the harmonic gear device 1 to perform tooth profile modification on the internal teeth 21 and the external teeth 31 .
  • at least one of the internal teeth 21 and the external teeth 31 may not be profiled.
  • ensuring a distance equal to or greater than a predetermined value in the radial direction between the tracks of the plurality of rolling elements 423 and the opening surface of the (first) through-hole H1 provided in the outer ring 421 is very important for the harmonic gear device 1 .
  • Language is not a necessary structure. That is, in a state where the rolling elements 423 are present at positions corresponding to the through-holes H1, no gap is generated between the opening surface of the through-holes H1 and the rolling elements 423, and the rolling elements 423 may close the through-holes H1. .
  • each rolling element 423 is not an essential structure of the harmonic gear device 1, and each rolling element 423 may be supported by two points, for example.
  • the harmonic gear device 1 is not limited to the cup type described in the first embodiment, and may be, for example, a top hat type, a ring type, a differential type, a flat type (doughnut type), or a shield type.
  • a top-hat type harmonic gear device 1 as illustrated in FIG. 10 has a cylindrical flexible external gear 3 similar to the cup type. It has an open face 35 . That is, the hat-shaped flexible external gear 3 has a flange portion at one end of the rotation axis Ax1 and has an opening surface 35 at an end opposite to the flange portion. Even the top-hat-shaped flexible external gear 3 has external teeth 31 at the end on the opening surface 35 side, into which the wave generator 4 is fitted.
  • the structure of the actuator 100 is not limited to the structure described in Embodiment 1, and can be appropriately changed.
  • the connection structure between the input unit 103 and the cam 41 is not limited to a spline connection structure, and a cross joint or the like may be used.
  • the Oldham joint as the connection structure between the input part 103 and the cam 41, the eccentricity between the input side rotation axis Ax1 and the wave generator 4 (cam 41) can be canceled out, and thus the rigid internal gear 2 and the flexible external gear 3 can be cancelled. of eccentricity.
  • the cam 41 does not have to be movable along the rotation axis Ax1 relative to the input portion 103 .
  • the application examples of the harmonic gear device 1, the actuator 100, and the robot joint device 130 of this embodiment are not limited to the above-mentioned horizontal articulated robot, and may be industrial robots or industrial robots other than the horizontal articulated robot, for example. Use other than robots etc. Examples of industrial robots other than horizontal articulated robots include vertical articulated robots, parallel link robots, and the like. Examples of robots other than industrial use include home-use robots, care-use robots, and medical-use robots.
  • the bearing 42 is not limited to a deep groove ball bearing, For example, an angular contact ball bearing etc. may be sufficient.
  • the bearing 42 is not limited to a ball bearing, and may be a cylindrical roller bearing, a needle roller bearing, or a tapered roller bearing such as a roller bearing such as a "roller" in which the rolling elements 423 are not ball-shaped. Even with the rolling elements 423 other than the ball shape (spherical body shape), a pressure difference is generated by the rolling elements 423 rolling, whereby the rolling elements 423 function as a pump structure.
  • each component of the harmonic gear device 1 , the actuator 100 , or the robot joint device 130 is not limited to metal, and may be resin such as engineering plastic, for example.
  • the lubricant Lb1 is not limited to a liquid substance such as lubricating oil (oil), but may be a gel-like substance such as grease.
  • the number and arrangement of the through holes H1 are not limited to those described in the first embodiment.
  • one, two, or four through holes H1 may be provided.
  • the interval P1 of the plurality of through-holes H1 may be a multiple of the interval P2 of the plurality of rolling elements 423, and the plurality of through-holes H1 are not necessarily arranged at equal intervals. .
  • the chemical conversion treatment coating C1 is not limited to a phosphate coating formed by a chemical conversion treatment using phosphate, and may be another chemical conversion treatment coating.
  • the plurality of grooves 303 may be formed not only on the inner peripheral surface 301 of the flexible external gear 3 but also on the outer peripheral surface 424 of the wave generator 4 .
  • the peeled chemical conversion treatment film C10 may also be held in the groove on the outer peripheral surface 424 side of the wave generator 4 .
  • FIG. 13A is a schematic diagram showing the surface state of the inner peripheral surface 301 of the flexible external gear 3 and the outer peripheral surface 424 of the wave generator 4 (outer ring 421) in the A1-A1 line section of FIG.
  • FIG. 13B is an enlarged schematic view of the region Z1 in FIG. 13A .
  • the chemical conversion coatings C1 and C2 are provided on both the outer peripheral surface 424 of the wave generator 4 and the inner peripheral surface 301 of the flexible external gear 3 .
  • the chemical conversion coatings C1 and C2 include the "first chemical conversion coating” provided on the target surface S1 constituted by the inner peripheral surface 301 of the flexible external gear 3, and the "first chemical conversion coating” provided on The “second chemical conversion treatment coating” of the target surface S2 constituted by the outer peripheral surface 424 of the wave generator 4 .
  • the (second) chemical conversion treatment coating C2 is also constituted by a phosphate coating as an example, similarly to the (first) chemical conversion treatment coating C1 .
  • both the chemical conversion coating C1 of the inner peripheral surface 301 of the flexible external gear 3 and the chemical conversion coating C2 of the outer peripheral surface 424 of the wave generator 4 can hold (wet) the lubricant Lb1. Therefore, the lubricant Lb1 is more likely to remain in the contact portion of the flexible external gear 3 with the wave generator 4, and more sufficient lubricant Lb1 can be maintained at the contact portion.
  • the compositions of the chemical conversion coatings C1 and C2 are the same on the outer peripheral surface 424 of the wave generator 4 and the inner peripheral surface 301 of the flexible external gear 3 . That is, both the (first) chemical conversion treatment coating C1 and the (second) chemical conversion treatment coating C2 are phosphate coatings and are composed of coatings with the same composition. Therefore, it is difficult for the (first) chemical conversion treatment film C1 and the (second) chemical conversion treatment film C2 to have a variation in peeling amount, and both the chemical conversion treatment films C1 and C2 are easily peeled off in a balanced manner.
  • a "groove” may be formed on the target surface S2 constituted by the outer peripheral surface 424 of the wave generator 4, similarly to the groove 303 on the target surface S1 (inner peripheral surface 301 of the flexible external gear 3).
  • the peeled chemical conversion treatment coatings C1 and C2 can also be held in the grooves of the target surface S2.
  • the chemical conversion treatment coating C2 may be provided only on the outer peripheral surface 424 of the wave generator 4 among the outer peripheral surface 424 of the wave generator 4 and the inner peripheral surface 301 of the flexible external gear 3 .
  • Embodiment 2 can be applied in combination with the configuration (including modifications) described in Embodiment 1 as appropriate.
  • the harmonic gear unit (1, 1A, 1B) of the first aspect includes a rigid internal gear (2), a flexible external gear (3), and a wave generator (4).
  • the rigid internal gear (2) is an annular member having internal teeth (21).
  • the flexible external gear (3) is an annular member having external teeth (31) and arranged inside the rigid internal gear (2).
  • the wave generator (4) has a non-circular cam (41) that is driven to rotate around the rotation axis (Ax1), and a bearing (42) mounted on the outside of the cam (41).
  • the wave generator (4) is arranged inside the flexible external gear (3), and causes the flexible external gear (3) to bend.
  • the flexible external gear (3) is deformed with the rotation of the cam (41), and a part of the external teeth (31) meshes with a part of the internal teeth (21) , and make the flexible external gear (3) relatively rotate relative to the rigid internal gear (2) according to the tooth number difference between the flexible external gear (3) and the rigid internal gear (2).
  • a chemical conversion treatment film ( C1, C2, C10).
  • occurrence of fretting wear is suppressed by preventing "lubricant depletion” in which the lubricant (Lb1) is insufficient or exhausted at the contact portion of the wave generator (4) and the flexible external gear (3).
  • the conversion coatings (C1, C2, C10) can maintain sufficient lubricant (Lb1) at the contact portion of the flexible external gear (3) and the wave generator (4).
  • the surface of the contact portion of the flexible external gear (3) with the wave generator (4) is covered with the lubricant (Lb1), and the occurrence of fretting wear is suppressed. Therefore, troubles caused by fretting wear between the wave generator (4) and the flexible external gear (3) are less likely to occur, and it is possible to provide a harmonic gear device (1, 1A, 1B) that is less likely to cause a decrease in reliability. .
  • the target surface (S1, S2) is formed with a film (C1, C2, C10) capable of holding at least the chemical conversion treatment. ) slot (303).
  • the chemical conversion treatment coatings (C1, C2, C10) can be left in the wave generator ( 4) Between the flexible external gear (3).
  • the slots (303) include first slots (303a) and second slots (303b) intersecting each other.
  • the lubricant (Lb1) easily spreads over a relatively large range in the gap (X1) between the wave generator (4) and the flexible external gear (3).
  • the thickness (L2) of the chemical conversion treatment film (C1, C2, C10) is smaller than that of the groove ( 303) has a small depth (L1).
  • the chemical conversion treatment coatings (C1, C2, C10) are accommodated in the tank (303), and the chemical conversion treatment coatings (C1, C2, C10) are hardly exposed from the tank (303).
  • the hardness ratio of the chemical conversion treatment film (C1, C2, C10) is The hardness of the parts other than the chemical conversion treatment coating (C1, C2, C10) among the surfaces (S1, S2) is low.
  • the chemical conversion treatment film (C1, C2, C10) sandwiched between the two serves as a buffer, which can suppress the flexibility. Damage to the external gear (3) and the wave generator (4).
  • the chemical conversion treatment film (C1, C2, C10) is configured to maintain Lubricant (Lb1).
  • the lubricant (Lb1) is likely to remain in the contact portion between the flexible external gear (3) and the wave generator (4), and sufficient lubricant (Lb1) can be maintained at the contact portion.
  • the chemical conversion treatment film (C1, C2, C10) is arranged on the wave generator Both the outer peripheral surface (424) of (4) and the inner peripheral surface (301) of the flexible external gear (3).
  • the chemical conversion treatment coatings (C1, C2, C10) have the same composition.
  • the chemical conversion treatment film (C1) on the side of the flexible external gear (3) and the chemical conversion treatment film (C2) on the side of the wave generator (4) are less likely to produce deviations in the peeling amount, and the chemical conversion treatment Both the films (C1, C2) are easily peeled off in a balanced manner.
  • the outer ring (421) of the bearing (42) and the flexible external gear At least one of the external teeth (31) in (3) is provided with a through hole (H1, H2), the through hole (H1, H2) passes through in the radial direction, and is connected with the outer ring (421) and the flexible
  • the gap (X1) between the external gears (3) is connected.
  • the lubricant (Lb1) can be supplied through the gap (X1) between the outer ring (421) and the flexible external gear (3) through the through holes (H1, H2). Accordingly, occurrence of fretting wear can be further suppressed by preventing "lubricant depletion" in which the lubricant (Lb1) is insufficient or exhausted at the contact portion between the outer ring (421) and the flexible external gear (3).
  • the robot joint device (130) of the ninth aspect includes the harmonic gear device (1, 1A, 1B) of any one of the first to eighth aspects, and a first member (131) fixed to the rigid internal gear (2). ), and a second member (132) fixed to the flexible external gear (3).
  • the structures of the second to eighth solutions are not necessary for the harmonic gear device (1, 1A, 1B) and can be appropriately omitted.

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JP2002349645A (ja) * 2001-05-23 2002-12-04 Harmonic Drive Syst Ind Co Ltd 無潤滑型波動歯車装置
CN103758990A (zh) * 2014-01-02 2014-04-30 上海宇航系统工程研究所 一种月面大载荷空间机构润滑装置
CN206738541U (zh) * 2017-04-24 2017-12-12 大族激光科技产业集团股份有限公司 机器人、机器人关节及其谐波减速器
CN108180272A (zh) * 2017-12-25 2018-06-19 香河皓达机器人谐波减速器制造有限公司 压力控制谐波减速器
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US20210341048A1 (en) * 2018-11-22 2021-11-04 Harmonic Drive Systems Inc. Strain wave gearing device

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JP4603668B2 (ja) 2000-10-11 2010-12-22 住友重機械工業株式会社 外歯歯車の製造方法
JP7221077B2 (ja) 2019-02-20 2023-02-13 住友重機械工業株式会社 撓み噛合い式歯車装置及びその製造方法

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JPH1019092A (ja) * 1996-07-03 1998-01-20 Harmonic Drive Syst Ind Co Ltd 撓み噛み合い式歯車装置の摩耗防止機構
JP2002349645A (ja) * 2001-05-23 2002-12-04 Harmonic Drive Syst Ind Co Ltd 無潤滑型波動歯車装置
CN103758990A (zh) * 2014-01-02 2014-04-30 上海宇航系统工程研究所 一种月面大载荷空间机构润滑装置
CN206738541U (zh) * 2017-04-24 2017-12-12 大族激光科技产业集团股份有限公司 机器人、机器人关节及其谐波减速器
CN108180272A (zh) * 2017-12-25 2018-06-19 香河皓达机器人谐波减速器制造有限公司 压力控制谐波减速器
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US20210341048A1 (en) * 2018-11-22 2021-11-04 Harmonic Drive Systems Inc. Strain wave gearing device

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