WO2022077872A1 - 谐波齿轮装置及执行器 - Google Patents

谐波齿轮装置及执行器 Download PDF

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Publication number
WO2022077872A1
WO2022077872A1 PCT/CN2021/083685 CN2021083685W WO2022077872A1 WO 2022077872 A1 WO2022077872 A1 WO 2022077872A1 CN 2021083685 W CN2021083685 W CN 2021083685W WO 2022077872 A1 WO2022077872 A1 WO 2022077872A1
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WIPO (PCT)
Prior art keywords
teeth
tooth
gear
flexible external
trimming
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PCT/CN2021/083685
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English (en)
French (fr)
Inventor
王刚
林文捷
峯岸清次
伊佐地毅
郭子铭
Original Assignee
灵智信息服务（深圳）有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Application filed by 灵智信息服务（深圳）有限公司 filed Critical 灵智信息服务（深圳）有限公司
Priority to CN202180042972.5A priority Critical patent/CN115803545A/zh
Priority to EP21878927.9A priority patent/EP4198349A4/en
Publication of WO2022077872A1 publication Critical patent/WO2022077872A1/zh
Priority to US18/135,082 priority patent/US20230250865A1/en

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    • 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
    • F16H49/001—Wave gearings, e.g. harmonic drive transmissions
    • 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
    • F16H49/001—Wave gearings, e.g. harmonic drive transmissions
    • F16H2049/003—Features of the flexsplines therefor
    • 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
    • F16H55/00—Elements with teeth or friction surfaces for conveying motion; Worms, pulleys or sheaves for gearing mechanisms
    • F16H55/02—Toothed members; Worms
    • F16H55/08—Profiling
    • F16H55/0833—Flexible toothed member, e.g. harmonic drive

Definitions

  • the embodiments of the present disclosure generally relate to a harmonic gear device and an actuator, and more specifically, to a harmonic gear device and an actuator having a rigid internal gear, a flexible external gear, and a wave generator.
  • Patent Document 1 discloses surface treatment of a flexible external gear in a harmonic gear device (flexural meshing gear device) by nitriding.
  • the harmonic gear device includes: a ring-shaped rigid internal gear; a cup-shaped flexible external gear arranged on the inner side; and an elliptical wave generator embedded in the inner side.
  • the flexible external gear includes a cylindrical body portion and external teeth formed on the outer peripheral surface of the body portion.
  • the flexible external gear is deflected into an elliptical shape by a wave generator, and portions of the external teeth located at both ends in the long axis direction of the elliptical shape mesh with the internal teeth formed on the inner peripheral surface of the rigid internal gear.
  • Patent Document 1 Japanese Patent Laid-Open No. 2001-59153
  • the harmonic gear device deflects the flexible external gear and transmits the power through the meshing between the internal teeth and the external teeth, especially if it is used for a long period of time, for example, due to the contact between the internal teeth and the external teeth.
  • Foreign matter such as metal powder or nitride may be generated due to defects or wear caused by it. Due to the generation of such foreign matter, foreign matter may be caught between the internal and external teeth, or the foreign matter may enter the bearing of the wave generator and cause bearing damage, which may affect the reliability of the harmonic gear device.
  • the embodiments of the present disclosure are made in view of the above-mentioned reasons, and an object thereof is to provide a harmonic gear device and an actuator with high 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 disposed inside the rigid internal gear.
  • the wave generator is arranged inside the flexible external gear and causes the flexible external gear to deflect.
  • the harmonic gear device deforms the flexible external gear in accordance with the rotation of the wave generator centered on the rotating shaft, and meshes a part of the external teeth with a part of the internal teeth, so that the The flexible external gear relatively rotates with respect to the rigid internal gear according to the difference in the number of teeth between the flexible external gear and the rigid internal gear.
  • the internal teeth have a tooth direction trimming portion at at least one end of the tooth direction of the internal teeth.
  • An actuator includes the above-described harmonic gear device, a drive source, and an output portion.
  • the drive source rotates the wave generator.
  • the output unit takes out, as an output, the rotational force of either the rigid internal gear and the flexible external gear.
  • harmonic gear devices and actuators capable of providing high reliability.
  • 1A is a cross-sectional view showing a schematic configuration of a harmonic gear device according to an embodiment.
  • FIG. 1B is an enlarged view of the region Z1 of FIG. 1A .
  • FIG. 2 is a schematic diagram of the above-described harmonic gear device viewed from the input side of the rotating shaft.
  • 3A is a schematic exploded perspective view of the above-described harmonic gear device as viewed from the output side of the rotating shaft.
  • 3B is a schematic exploded perspective view of the above-described harmonic gear device as viewed from the input side of the rotating shaft.
  • FIG. 4 is a cross-sectional view showing a schematic configuration of an actuator including the above-described harmonic gear device.
  • FIG. 5A is a schematic cross-sectional view of the internal teeth and external teeth of the above-described harmonic gear device.
  • FIG. 5B is a cross-sectional view taken along line A1-A1 of FIG. 5A .
  • FIG. 6 is a conceptual explanatory diagram showing the amount of dressing of the internal teeth and the external teeth of the above-described harmonic gear device.
  • FIG. 7A is a cross-sectional view taken along line B1-B1 of FIG. 5A .
  • FIG. 7B is a cross-sectional view taken along line B2-B2 of FIG. 5A .
  • FIG. 7C is a cross-sectional view taken along line B3-B3 of FIG. 5A .
  • 8A is a schematic cross-sectional view of the periphery of the inner peripheral surface of the flexible external gear of the above-described harmonic gear device.
  • FIG. 8B is an enlarged view of the region Z1 of FIG. 8A .
  • FIG. 9 is a cross-sectional view showing an example of a robot using the above-described harmonic gear device.
  • 10A is a cross-sectional view of a main part of a harmonic gear device according to a first modification of the embodiment.
  • 10B is a cross-sectional view of a main part of the harmonic gear device according to the second modification of the embodiment.
  • 10C is a cross-sectional view of a main part of a harmonic gear device according to a third modification of the embodiment.
  • 10D is a cross-sectional view of a main part of a harmonic gear device according to a fourth modification of the embodiment.
  • FIG. 11A is a schematic cross-sectional view looking at internal teeth and external teeth of a harmonic gear device according to another embodiment.
  • FIG. 11B is a cross-sectional view taken along line A1-A1 of FIG. 11A .
  • FIG. 12A is a cross-sectional view taken along line B1-B1 of FIG. 11A .
  • FIG. 12B is a cross-sectional view taken along line B2-B2 of FIG. 11A .
  • FIG. 12C is a cross-sectional view taken along line B3-B3 of FIG. 11A .
  • FIG. 13 is a schematic cross-sectional view as seen by focusing on internal teeth and external teeth of a harmonic gear device according to still another embodiment.
  • FIGS. 1A to 4 The drawings referred to in the embodiments of the present disclosure are all schematic diagrams, and the respective ratios of the sizes and thicknesses of the constituent elements in the drawings are not necessarily limited to reflect the actual size ratios.
  • FIGS. 2 to 3B the tooth shape, size, and number of teeth of the inner teeth 21 and the outer teeth 31 are only schematically shown for illustration, and the gist thereof is not limited to the shapes shown in the drawings.
  • 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 further 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 deflecting the flexible external gear 3 into a non-circular shape.
  • the meshing position of the inner teeth 21 and the outer teeth 31 moves in the circumferential direction of the rigid inner gear 2, and generates a deflection between the two gears (the rigid inner gear 2 and the flexible outer gear 3).
  • the relative rotation of the rigid external gear 3 and the number of teeth of the rigid internal gear 2 is performed.
  • the rigid internal gear 2 is fixed, the flexible external gear 3 rotates with the relative rotation of the two gears.
  • a rotational output reduced by a relatively high reduction ratio according to the difference in the number of teeth between the two gears can be obtained from the flexible external gear 3 .
  • the wave generator 4 for causing the flexible external gear 3 to deflect includes a non-circular cam 41 and a bearing 42 that are driven to rotate about an 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 by the ball-shaped rolling elements 423 .
  • the outer ring 421 can rotate relative to the inner ring 422 by rolling the rolling elements 423.
  • the wave generator 4 having the bearing 42 realizes power transmission by the meshing of the internal teeth 21 and the external teeth 31 while deflecting the flexible external gear 3 . Therefore, in particular, when used for a long time, foreign substances X1 such as metal powder and nitrides are generated due to contact between the inner teeth 21 and the outer teeth 31 due to chipping or abrasion (see FIG. 8B ). Since such foreign matter X1 is generated, the foreign matter X1 may be caught between the inner teeth 21 and the outer teeth 31 or the foreign matter X1 may enter the bearing 42 of the wave generator 4 and cause damage to the bearing 42 , which may affect the harmonic gear device 1 reliability.
  • foreign substances X1 such as metal powder and nitrides are generated due to contact between the inner teeth 21 and the outer teeth 31 due to chipping or abrasion (see FIG. 8B ). Since such foreign matter X1 is generated, the foreign matter X1 may be caught between the inner teeth 21 and the outer teeth 31 or the foreign matter X1 may enter the bearing 42 of the
  • the outer ring 421 , the inner ring 422 and the rolling elements 423 are rolled on the outer ring 421 , the inner ring 422 and the rolling elements 423 , starting from the indentation generated by the foreign matter X1 biting into the outer ring 421 or between the inner ring 422 and the rolling elements 423 of the bearing 42 .
  • a certain surface of the body 423 may be damaged. Such damage (surface-origin-type peeling) causes deterioration of the quality, characteristics, and the like of the harmonic gear device 1 , and as a result, reduces the reliability of the harmonic gear device 1 .
  • the harmonic gear device 1 according to the present embodiment has the following structure to make it difficult to generate foreign matter X1, thereby making it difficult 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 ; Generator 4.
  • the flexible external gear 3 is arranged inside the rigid internal gear 2 .
  • the wave generator 4 is arranged inside the flexible external gear 3 and causes the flexible external gear 3 to deflect.
  • the harmonic gear device 1 deforms the flexible external gear 3 in accordance with the rotation of the wave generator 4 centered on the rotation axis Ax1, meshes a part of the external teeth 31 with a part of the internal teeth 21, and causes the flexible external gear 3 to meet the It rotates relative to the rigid internal gear 2 by a difference in the number of teeth with the rigid internal gear 2 .
  • the inner teeth 21 have a tooth direction trimming part 210 at at least one end of the tooth direction D1 of the inner teeth 21 .
  • the inner tooth 21 has the tooth direction trimming portion 210 at at least one end of the tooth direction D1 of the inner tooth 21 . Since a “relief portion” is formed between the tooth direction trimming portion 210 of the inner teeth 21 and the outer teeth 31 , at least one end of the tooth direction D1 of the inner teeth 21 can be adjusted by the inner teeth due to the tooth direction trimming portion 210 . Stress concentration due to excessive tooth contact between 21 and external teeth 31 is difficult to generate. In particular, in the harmonic gear device 1, since the wave generator 4 deflects the flexible external gear 3, the external teeth 31 may be deformed such as torsion and skew (tilt) with respect to the rotation axis Ax1.
  • the tooth direction trimming portion 210 can make such a stress concentration less likely to occur. Thereby, foreign matter X1 due to chipping, abrasion, etc. caused by the contact between the inner teeth 21 and the outer teeth 31 is less likely to occur, and the harmonic gear device 1 with high reliability can be provided. Furthermore, since the tooth direction trimming portion 210 is provided on the rigid internal gear 2, the tooth direction trimming is not required for the flexible external gear 3 or the amount of trimming can be reduced, and it is easy to suppress the application of teeth to the flexible external gear 3. The strength of the flexible external gear 3 due to the trimming decreases.
  • the surface hardness of the inner teeth 21 is lower than the surface hardness of the outer teeth 31 .
  • the outer teeth 31 protrude toward at least one of the teeth directions D1 with respect to the inner teeth 21 .
  • the external teeth 31 with relatively high surface hardness protrude in at least one of the tooth directions D1 with respect to the internal teeth 21 , so that the tooth surfaces of the internal teeth 21 are less likely to be uneven due to wear in at least one of the tooth directions D1 Difference. That is, in at least one of the tooth directions D1, the inner teeth 21 with relatively low surface hardness are uniformly worn due to the tooth contact of the outer teeth 31, so that the tooth surfaces of the inner teeth 21 are less likely to be locally dented (differences in height). Therefore, even if the tooth contact position deviates in the tooth direction D1 due to some jitter, it is easy to suppress the harmonic gear device caused by the excessive load acting on the meshing portion between the inner teeth 21 and the outer teeth 31 1 exception occurs.
  • the harmonic gear device 1 of the present embodiment since the foreign matter X1 is less likely to be generated, an effect of high reliability can be obtained.
  • the harmonic gear device 1 according to the present embodiment is less likely to decrease in reliability even during long-term use, and further, the harmonic gear device 1 can achieve longer life and higher performance.
  • the harmonic gear device 1 of the present embodiment constitutes an actuator 100 together with a drive source 101 and an output unit 102 .
  • the actuator 100 of the present embodiment includes the harmonic gear device 1 , the drive source 101 , and the output unit 102 .
  • the drive source 101 rotates the wave generator 4 .
  • the output unit 102 takes out, as an output, the rotational force of either of the rigid internal gear 2 and the flexible external gear 3 .
  • the actuator 100 of the present embodiment there is an advantage that the reliability of the harmonic gear device 1 is not easily degraded.
  • the term "annular” refers to a shape like a ring (circle) that forms an enclosed space (region) on the inside at least in a plan view, and is not limited to a perfect circle or a certain circle in a plan view
  • the shape (annulus) may be, for example, an elliptical shape, a polygonal shape, or the like. Further, for example, it may have a shape like a cup-shaped flexible external gear 3 having a bottom portion 322 , and if its body portion 321 is annular, it is called an “annular” flexible external gear 3 .
  • the "tooth direction trimming” refers to the trimming of the tooth direction D1
  • the tooth direction trimming portion 210 of the inner tooth 21 is the portion of the inner tooth 21 where the tooth direction trimming is performed.
  • the normal tooth direction shape of the gear can be consciously bulged or the torsion angle can be changed.
  • As representative processes of the tooth direction dressing there are drum dressing and edging processing (tooth edge trimming).
  • the crowning is a process in which the center part of the tooth direction D1 of the gear is rounded toward the center part of the tooth direction D1 so that the center part thereof becomes convex.
  • the edge trimming is a processing method in which both ends of the tooth direction D1 are appropriately avoided.
  • the bulging is processing over substantially the entire length of the tooth direction D1 that has rounded corners toward the center, while the edging is processing to evade only the both ends of the tooth direction D1.
  • the tooth contact position with the counterpart gear can be brought closer to the center vicinity of the tooth direction D1.
  • the “foreign matter” referred to in the embodiments of the present disclosure refers to substances other than the original constituent elements of the harmonic gear device 1 , and as an example, there are defects or wear caused by the contact between the inner teeth 21 and the outer teeth 31 , etc. of metal powder or nitride, etc.
  • the foreign matter X1 that is prevented from entering by the lubricant Lb1 is not limited to substances generated inside the harmonic gear device 1 , but includes, for example, entering from outside the harmonic gear device 1 . waste, sand or dust, etc.
  • the "obstruction” mentioned here refers to interference or obstruction, and is not limited to complete obstruction, including all cases where the foreign matter X1 is difficult to enter.
  • the term "difficult to generate foreign matter X1" in the embodiments of the present disclosure means that at least one of the generation amount, generation rate, and generation frequency of foreign matter X1 (hereinafter referred to as "generation amount, etc.") is reduced.
  • the generation amount and the like refer to the value of the foreign matter X1 in terms of hardness and size, which may cause the reliability of the harmonic gear device 1 to deteriorate, and the foreign matter X1 is less likely to be generated, including, for example, a hard (comparatively high hardness) foreign matter X1. decrease in quantity, etc.
  • the case where the foreign matter X1 is not generated at all is also included in the case where the foreign matter X1 is hardly generated.
  • the amount of foreign matter X1 generated and the like is reduced compared to the case where this configuration is not adopted.
  • the present embodiment by adopting a structure in which the external teeth 31 with relatively high surface hardness protrude in at least one of the tooth directions D1 with respect to the internal teeth 21, the amount of foreign matter X1 generated, etc. reduce.
  • the "rigidity” mentioned in the embodiments of the present disclosure refers to the property of the object to resist the deformation when an external force is applied to the object and the object is to be deformed. In other words, a rigid object is difficult to deform even if an external force is applied.
  • the "flexibility” referred to in the embodiments of the present disclosure refers to the property of elastically deforming (deflecting) an object 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.
  • “rigid” and “flexible” are the opposite.
  • the "rigidity" of the rigid internal gear 2 and the “flexibility” of the flexible external gear 3 are used in a relative sense. That is, the "rigidity" of the rigid internal gear 2 means that the rigid internal gear 2 has relatively high rigidity at least compared to the flexible external gear 3 , that is, the rigid internal gear 2 is hard to deform even if an external force is applied. Similarly, the "flexibility" of the flexible external gear 3 means that the flexible external gear 3 has a relatively high flexibility at least compared to the rigid internal gear 2, that is, the flexible external gear 3 is easily elastic when an external force is applied deformed.
  • one side of the rotation axis Ax1 (the right side in FIG. 1A ) may be referred to as the “input side”, and the other side (the left side in FIG. 1A ) of the rotation axis Ax1 may be referred to as the “output side”. 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 the purpose of description, and the gist thereof is not intended to limit the positional relationship between the input and the output viewed from the harmonic gear device 1 .
  • non-circular shape refers to a shape that is not a perfect circle, for example, including an oval 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 all shapes in which a perfect circle is flattened and the intersection of the long axis and the short axis that are orthogonal to each other is located at the center, and is not limited to being formed by a certain shape on a plane.
  • a curve formed by a set of points whose sum of the distances of two fixed points is constant is a mathematical "ellipse”. That is, the cam 41 in the present embodiment may be in the shape of a curve formed by a set of points whose distances from two fixed points on a plane are the same as a mathematical "ellipse", or may not be a mathematical "ellipse". Ellipse” but an oval shape like an oval.
  • the drawings referred to in the embodiments of the present disclosure are all schematic diagrams, and the respective ratios of the sizes and thicknesses of the structural elements in the drawings are not necessarily limited to reflect the actual size ratios. Therefore, for example, in FIG. 2 , the shape of the cam 41 of the wave generator 4 is assumed to be a slightly exaggerated elliptical shape, but the intention is not to limit the actual shape of the cam 41 .
  • the "rotation axis" referred to in the embodiments of the present disclosure refers to an imaginary axis (straight line) that becomes the center of the rotational motion of the rotating body. That is, the rotation axis Ax1 is an imaginary axis not accompanied by a substance.
  • the wave generator 4 rotates around the rotation axis Ax1.
  • the "internal teeth” and “external teeth” mentioned in the embodiments of the present disclosure respectively refer to a collection (group) of a plurality of "teeth” rather than a single “teeth”. That is, the internal teeth 21 of the rigid internal gear 2 include a plurality of sets of teeth formed on the inner peripheral surface of the rigid internal gear 2 . Similarly, the external teeth 31 of the flexible external gear 3 include a plurality of sets of teeth formed on the outer peripheral surface of the flexible external gear 3 .
  • the “parallel” mentioned in the embodiments of the present disclosure is except the case where two straight lines on a plane do not intersect no matter where they are extended, that is, the angle between the two is strictly 0 degrees (or 180 degrees). In addition, it also refers to a relationship in which the angle between the two is within an error range of about a few degrees (eg, less than 10 degrees) with respect to 0 degrees. Similarly, the “orthogonal” mentioned in the embodiments of the present disclosure, except that the angle between the two intersects strictly at 90 degrees, also means that the angle between the two is within a few degrees relative to 90 degrees (for example, less than 90 degrees). 10 degrees) the relationship of the error range.
  • FIG. 1A is a cross-sectional view showing a schematic configuration of the harmonic gear device 1
  • FIG. 1B is an enlarged view of a region Z1 of FIG. 1A
  • FIG. 2 is a schematic diagram of the harmonic gear device 1 viewed from the input side (right side of FIG. 1A ) of the rotation axis Ax1
  • FIG. 3A is a schematic exploded perspective view of the harmonic gear device 1 viewed from the output side (the left side of FIG. 1A ) of the rotation axis Ax1
  • FIG. 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. As shown in FIG.
  • the harmonic gear device 1 of the present embodiment includes the rigid internal gear 2 , the flexible external gear 3 , and the wave generator 4 .
  • the rigid internal gear 2 , the flexible external gear 3 and the wave generator 4 which are components of the harmonic gear device 1 are made of stainless steel, cast iron, carbon steel for machine structure, chrome molybdenum steel, phosphorus Metals such as bronze or aluminum bronze.
  • the metal referred to here includes a metal subjected to surface treatment such as nitriding.
  • a cup-type harmonic gear device is exemplified. That is, in the harmonic gear device 1 of the present embodiment, the cup-shaped flexible external gear 3 is used. 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 device 1 is used in a state where the rigid internal gear 2 is fixed to the input side casing 111 (see FIG. 4 ) and the output side casing 112 (see FIG. 4 ). Thereby, along with the relative rotation of the rigid internal gear 2 and the flexible external gear 3, the flexible external gear 3 relatively rotates with respect to the fixed member (input side housing 111 and the like).
  • the harmonic gear device 1 when the harmonic gear device 1 is used for the actuator 100 , by applying the rotational force as the input to the wave generator 4 , the rotational force as the output is taken out from the flexible external gear 3 . . That is, the harmonic gear device 1 operates with the rotation of the wave generator 4 as the input rotation and the rotation of the flexible external gear 3 as the output rotation. As a result, in the harmonic gear device 1 , it is possible to obtain an output rotation that is reduced by a relatively high reduction ratio with respect to the input rotation.
  • the rotation axis Ax1 on the input side and the rotation axis Ax2 on the output side are 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 device 1, on the coaxial line, the output rotation reduced by the high reduction ratio with respect to the input rotation can be obtained.
  • 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 at least an annular shape whose inner peripheral surface is a perfect circle in plan view.
  • 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 .
  • the plurality of teeth constituting the internal teeth 21 are all of 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 inner 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 formed over the entire length in the thickness direction of the rigid internal gear 2 .
  • 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 casing 111 (see FIG. 4 ), the output side casing 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 formed into a cup shape using a relatively thin metal elastic body (metal plate). That is, the flexible external gear 3 possesses flexibility because its thickness is relatively small (thin).
  • the flexible external gear 3 has a cup-shaped main body portion 32 .
  • the main body portion 32 has a body portion 321 and a bottom portion 322 .
  • at least the inner peripheral surface 301 of the trunk portion 321 has a cylindrical shape that is a perfect circle in plan view.
  • the central axis of the trunk portion 321 coincides with the rotation axis Ax1.
  • the bottom part 322 is arrange
  • the bottom part 322 is arrange
  • the main body portion 32 has a bottomed cylindrical shape, that is, a cup-like shape that is open to the input side of the rotation axis Ax1 by the entire body portion 321 and the bottom portion 322 .
  • the opening surface 35 is formed in the end surface on the opposite side to the bottom part 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 of the tooth direction D1 (here, the input side of the rotation axis Ax1).
  • the body portion 321 and the bottom portion 322 are integrally formed with a single metal member, whereby a seamless body portion 32 can be realized.
  • the wave generator 4 having a non-circular shape (elliptical shape) is fitted inside the body portion 321, and the wave generator 4 is combined with the flexible external gear 3.
  • the flexible external gear 3 receives an external force in the radial direction (direction orthogonal to the rotation axis Ax1 ) from the wave generator 4 from the inside to the outside, and thereby elastically deforms into a non-circular shape.
  • the wave generator 4 is combined with the flexible external gear 3, whereby the body portion 321 of the flexible external gear 3 is elastically deformed into an elliptical shape.
  • the state in which the flexible external gear 3 is not elastically deformed refers to a state in which the wave generator 4 is not combined with the flexible external gear 3 .
  • the state in which the flexible external gear 3 is elastically deformed refers to a state in which the wave generator 4 has been combined with the flexible external gear 3 .
  • the wave generator 4 is fitted into the end portion of the inner peripheral surface 301 of the trunk portion 321 on the opposite side 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 side of the opening surface 35 in the direction of the rotation axis Ax1 of the body portion 321 of the flexible external gear 3 . Therefore, in a state in which the flexible external gear 3 is elastically deformed, the end of the flexible external gear 3 on the side of the opening surface 35 in the direction of the rotation axis Ax1 is deformed more than the end on the bottom 322 side, and is closer to in the shape of an ellipse.
  • the inner peripheral surface 301 of the body portion 321 of the flexible external gear 3 includes a taper inclined with respect to the rotation axis Ax1 shape surface 302 (refer to FIG. 8A ).
  • the outer teeth 31 are formed along the circumferential direction of the trunk portion 321 at an end portion of the outer peripheral surface of the trunk portion 321 at least on the side opposite to the bottom portion 322 (input side of the rotation axis Ax1 ).
  • the external teeth 31 are provided at the end portion on the side of the opening surface 35 in at least the direction of the rotation axis Ax1 in the body portion 321 of the flexible external gear 3 .
  • All of the plurality of teeth constituting the external teeth 31 have the same shape, and are provided at equal intervals over the entire area in the circumferential direction of the outer peripheral surface of the flexible external gear 3 .
  • the pitch circle of the external teeth 31 is a perfect circle in plan view.
  • the external teeth 31 are formed only in a range of a constant width from the edge of the trunk portion 321 on the side of the opening 35 (the input side of the rotation axis Ax1).
  • the outer teeth 31 are formed on the outer peripheral surface of the body portion 321 at least in the portion (the end portion on the opening surface 35 side) where the wave generator 4 is fitted in the direction of the rotation axis Ax1 .
  • the tooth directions of the external teeth 31 are all parallel to the rotation axis Ax1.
  • the tooth directions of the internal teeth 21 of the rigid internal gear 2 and the external teeth 31 of the flexible external gear 3 are both parallel to the rotation axis Ax1. Therefore, in the present embodiment, the "tooth direction D1" is a direction parallel to the rotation axis Ax1.
  • the dimension of the tooth direction D1 of the inner teeth 21 is the tooth width of the inner teeth 21
  • the dimension of the tooth direction D1 of the outer teeth 31 is the tooth width of the outer teeth 31, so the tooth direction D1 is synonymous with the tooth width direction.
  • the rotation of the flexible external gear 3 is taken out as the output rotation. Therefore, the output part 102 of the actuator 100 is attached to the flexible external gear 3 (see FIG. 4 ).
  • a plurality of mounting holes 33 for mounting the shaft as the output portion 102 are formed in the bottom portion 322 of the flexible external gear 3 .
  • the penetration hole 34 is formed in the center part of the bottom part 322 . The periphery of the penetration hole 34 in the bottom portion 322 is thicker than other parts of the bottom portion 322 .
  • the flexible external gear 3 configured in this way is arranged inside the rigid internal gear 2 .
  • the flexible external gear 3 is connected to the rigid internal gear 2 so that only the end of the outer peripheral surface of the body portion 321 opposite to the bottom portion 322 (the input side of the rotation axis Ax1 ) is inserted inside the rigid internal gear 2 2 combinations. That is, the flexible external gear 3 is inserted into the rigid internal gear 2 by inserting the portion (the end on the opening surface 35 side) of the body portion 321 into which the wave generator 4 is fitted in the direction of the rotation axis Ax1 .
  • the external teeth 31 are formed on the outer peripheral surface of the flexible external gear 3
  • the 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 arranged inside the rigid internal gear 2, the external teeth 31 and the internal teeth 21 face each other.
  • the number of teeth of the internal teeth 21 in the rigid internal gear 2 is larger than the number of teeth of the external teeth 31 of the flexible external gear 3 by 2N (N is a positive integer).
  • N is "1”
  • the number of teeth (of the external teeth 31 ) of the flexible external gear 3 is greater than that of the rigid internal gear 2 (of the internal teeth 21 ) by "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 .
  • the flexible external gear 3 is set so that the center of the tooth direction D1 of the external teeth 31 faces the center of the tooth direction D1 of the internal teeth 21 .
  • the dimension (tooth width) of the tooth direction D1 of the outer teeth 31 is larger than the dimension (tooth width) of the tooth direction D1 of the inner teeth 21 .
  • the inner teeth 21 are received within the range of the tooth direction of the outer teeth 31 in the direction parallel to the rotation axis Ax1.
  • the outer teeth 31 protrude toward at least one side of the tooth direction D1 with respect to the inner teeth 21 . Details are described in the column of "(4.3) Tooth width.”
  • the external teeth 31 protrude on both sides of the tooth direction D1 (input side and output side of the rotation axis Ax1 ) with respect to the internal teeth 21 .
  • the pitch circle of the external teeth 31 that draw a perfect circle is set to be more positive than that drawn in the same way.
  • the pitch circle of the round 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 face each other with a gap therebetween and do not mesh with each other.
  • the trunk portion 321 is deflected into an elliptical shape (non-circular shape), so The external teeth 31 of the flexible external gear 3 are partially meshed with the internal teeth 21 of the rigid internal gear 2 . That is, the body portion 321 of the flexible external gear 3 (at least the end portion on the side of the opening surface 35 ) is elastically deformed into an elliptical shape, whereby as shown in FIG. The inner teeth 21 mesh.
  • the long diameter of the pitch circle of the external teeth 31 that draw an ellipse matches the diameter of the pitch circle of the internal teeth 21 that draw a perfect circle
  • the short diameter of the pitch circle of the external teeth 31 that draw an ellipse is larger than the diameter of the inner tooth 21 that draws a perfect circle.
  • the diameter of the pitch circle is small.
  • the wave generator 4 is also referred to as a wave generator, and is a component that deflects the flexible external gear 3 to generate harmonic motion of the external teeth 31 of the flexible external gear 3 .
  • the wave generator 4 is a member whose outer peripheral shape is a non-circular shape, specifically, an elliptical shape in plan view.
  • the wave generator 4 has a cam 41 of a non-circular shape (here, an elliptical shape) and a bearing 42 fitted on the outer circumference of the cam 41 . That is, the cam 41 having a non-circular shape (elliptical shape) is fitted into the inner ring 422 of the bearing 42, and the cam 41 is combined with the bearing 42. As shown in FIG. As a result, the bearing 42 is elastically deformed into a non-circular shape by receiving an external force in the radial direction (direction perpendicular to the rotation axis Ax1 ) from the cam 41 from the inner side to the outer side of the inner ring 422 .
  • a non-circular shape here, an elliptical shape
  • the state in which the bearing 42 is not elastically deformed refers to a state in which the cam 41 is not combined with the bearing 42 .
  • the state in which the bearing 42 is elastically deformed refers to a state in which the cam 41 is combined with the bearing 42 .
  • the cam 41 is a member of a non-circular shape (here, an elliptical shape) that is driven to rotate around the input-side rotation axis Ax1.
  • the cam 41 has an outer peripheral surface 411 (see FIG. 1B ), and at least the outer peripheral surface 411 is formed of a metal plate having an elliptical shape in plan view.
  • the cam 41 has a predetermined thickness in the direction of the rotation axis Ax1 (that is, the tooth direction D1). Thereby, the cam 41 has a rigidity equivalent to that of the rigid internal gear 2 . However, the thickness of the cam 41 is smaller (thinner) than the thickness 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 portion 103 is formed in the center portion 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 includes a deep groove ball bearing using 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 ring-shaped members using a thin metal elastic body (metal plate). That is, both the outer ring 421 and the inner ring 422 have flexibility due to their relatively small (thin) thicknesses. In the present embodiment, both the outer ring 421 and the inner ring 422 have an annular shape that is a perfect circle in plan view when the bearing 42 is not elastically deformed (a state in which the bearing 42 is combined with the cam 41 ). The inner ring 422 is one turn smaller than the outer ring 421 and is arranged inside the outer ring 421 . Here, since the inner diameter of the outer ring 421 is larger than the outer diameter of the inner ring 422 , a gap is generated between the inner peripheral surface of the outer ring 421 and the outer peripheral surface of the inner ring 422 .
  • the plurality of rolling elements 423 are arranged in the gap between the outer ring 421 and the inner ring 422 .
  • the plurality of rolling elements 423 are arranged in a row along the circumferential direction of the outer ring 421 .
  • the plurality of rolling elements 423 are all metal balls (balls) of the same shape, and are provided at equal intervals over the entire area of the outer ring 421 in the circumferential direction.
  • the bearing 42 further includes a retainer, and the plurality of rolling elements 423 are held between the outer ring 421 and the inner ring 422 by the retainer.
  • 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, whereby 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 similar to the outer peripheral shape of the cam 41 .
  • the outer ring 421 of the bearing 42 is pressed by the inner ring 422 via the plurality of rolling elements 423 and elastically deformed into an elliptical shape.
  • both the outer ring 421 and the inner ring 422 of the bearing 42 are elastically deformed into an elliptical shape.
  • the outer ring 421 and the inner ring 422 have elliptical shapes similar to each other.
  • the outer peripheral shape of the wave generator 4 which is an elliptical shape viewed from the input side of the rotation axis Ax1, is accompanied by the cam 41 so that its long axis rotates around the rotation axis Ax1. changes with the rotation.
  • the thus configured wave generator 4 is arranged inside the flexible external gear 3 .
  • the flexible external gear 3 and the wave generator 4 are combined so that only the end portion on the opposite side (opening surface 35 side) of the inner peripheral surface 301 of the body portion 321 from the bottom portion 322 is fitted into the wave generator 4 .
  • 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 in which the bearing 42 is not elastically deformed is the same as the outer diameter of the flexible external gear 3 (the body portion 321 ) in the state in which the elastic deformation is not produced. of the same inner diameter. Therefore, the outer peripheral surface of the outer ring 421 of the wave generator 4 is in contact with the inner peripheral surface 301 of the flexible external gear 3 over the entire circumference in the circumferential direction of the bearing 42 .
  • the trunk portion 321 is deflected into an elliptical shape (non-circular shape).
  • the flexible external gear 3 is fixed to the outer ring 421 of the bearing 42 .
  • the harmonic gear device 1 having the above-described configuration, as shown in FIG. 2 , when the body portion 321 of the flexible external gear 3 is bent into an elliptical shape (non-circular shape), the external teeth 31 of the flexible external gear 3 and The internal teeth 21 of the rigid internal gear 2 mesh locally. That is, by elastically deforming (the body portion 321 of) the flexible external gear 3 into an elliptical shape, the external teeth 31 at two locations corresponding to both ends in the long axis direction of the elliptical shape mesh with the internal teeth 21 .
  • the flexible external gear 3 is deformed with the rotation of the wave generator 4 centered on the rotation axis Ax1, and a part of the external teeth 31 and the internal teeth are deformed. A part of 21 meshes, so that the flexible external gear 3 rotates according to the difference in the number of teeth with the rigid internal gear 2 .
  • the 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 . 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 reduction ratio R1 is represented by the following formula 1.
  • the reduction ratio R1 becomes "35".
  • the cam 41 makes one clockwise rotation (360 degrees) around the rotation axis Ax1 when viewed from the input side of the rotation axis Ax1
  • the flexible external gear 3 rotates counterclockwise around the rotation axis Ax1
  • the number of teeth differs by the amount of "2" (ie 10.3 degrees).
  • such a high reduction ratio R1 can be realized by the combination of one-stage gears (the rigid internal gear 2 and the flexible external gear 3 ).
  • the harmonic gear device 1 only needs to include at least the rigid internal gear 2, the flexible external gear 3 and the wave generator 4.
  • it may further include the spline bushing 113 described in the column of "(3.2) Actuator", etc. as a constituent element.
  • 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 the drive source 101 and the 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 further includes an input unit 103, an input side housing 111, an output side housing 112, a spline bush 113, a spacer 114, The first stopper 115 , the second stopper 116 and the mounting plate 117 .
  • the actuator 100 further includes the input side bearings 118 and 119 , the input side oil seal 120 , the output side bearings 121 and 122 , and the output side oil seal 123 .
  • the materials of the components other than the driving source 101 , the input side oil seal 120 and the output side oil seal 123 in the actuator 100 are stainless steel, cast iron, mechanical structural carbon steel, chrome molybdenum steel, phosphor bronze or aluminum bronze etc. metal.
  • the drive source 101 is a power generation source of a motor (electric motor) or the like.
  • the power generated by the drive source 101 is transmitted to the cam 41 of the wave generator 4 in the harmonic gear device 1 .
  • the drive source 101 is connected to a shaft serving as the input unit 103 , and the 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 output-side rotation axis Ax2.
  • 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 portion 102 is fixed to the bottom portion 322 of the main body portion 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 part 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 which 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 part 103 is attached to the cam 41 of the wave generator 4, and rotates together with the cam 41 about the rotation axis Ax1. That is, the input unit 103 transmits the power (rotational force) generated by the drive source 101 to the cam 41 as an input.
  • the input-side rotation axis Ax1 and the output-side rotation axis Ax2 are located on the same straight line, so the input unit 103 and the output unit 102 are located coaxially.
  • the input side housing 111 holds the input unit 103 rotatably via the input side bearings 118 and 119 .
  • the pair of input side bearings 118 and 119 are arranged in a row along the rotation axis Ax1 with an interval therebetween.
  • the shaft serving as the input unit 103 penetrates through the input side housing 111 , and the front end of the input unit 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.
  • a gap between the input side end surface of the rotation shaft Ax1 of the input side housing 111 and the input portion 103 is closed by the input side oil seal 120 .
  • the output side housing 112 holds the output unit 102 rotatably via the output side bearings 121 and 122 .
  • the pair of output side bearings 121 and 122 are arranged in a row along the rotation axis Ax2 with an interval therebetween.
  • the shaft serving as the output unit 102 passes through the output side housing 112 , and the front end of the output unit 102 extends from the output side end surface (the left end surface in FIG. 4 ) of the rotation axis Ax1 in the output side housing 112 . protrude.
  • the output-side oil seal 123 closes the gap between the output-side housing 112 and the output portion 102 on the output-side end surface of the rotation shaft Ax1 .
  • the input side case 111 and the output side case 112 sandwich the rigid internal gear 2 of the harmonic gear device 1 from both sides of the direction parallel to the rotation axis Ax1, that is, the tooth direction D1. combined with each other.
  • the input side housing 111 is in contact with the rigid internal gear 2 from the input side of the rotation shaft Ax1
  • the output side housing 112 is in contact with the rigid internal gear 2 from the output side of the rotation shaft Ax1 .
  • the input side case 111 and the output side case 112 are connected to the input side case 111 and the output side case 112 by screws (bolts) through the plurality of fixing holes 22
  • the body 112 is fastened and fixed.
  • the input side housing 111 , the output side housing 112 , and the rigid internal gear 2 are combined with each other to be integrated.
  • the rigid internal gear 2 together with the input side housing 111 and the output side housing 112 constitute the outer contour of the actuator 100 .
  • the spline bush 113 is a cylindrical member for connecting the shaft serving as the input portion 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 portion 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 portion 103 is restricted in the rotational direction around the rotational axis Ax1, and the spline bush 113 is restricted in the direction parallel to the rotational axis Ax1.
  • 113 is movable relative to at least the input unit 103 .
  • the spline connection structure can be realized as the connection structure of the input portion 103 and the cam 41 .
  • the cam 41 can move along the rotation axis Ax1 with respect to the input unit 103 and rotate together with the input unit 103 around the rotation axis Ax1.
  • the spacer 114 is a member that fills the gap between the spline bush 113 and the cam 41 .
  • the first stopper 115 is a member that prevents the spline bush 113 from falling off the cam 41 .
  • the first stopper 115 is formed of, for example, an E-ring, and is attached to the spline bush 113 at a position on the input side of the rotation shaft Ax1 with respect to the cam 41 .
  • the second stopper 116 is a member that prevents the input portion 103 from falling 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 be in contact with the spline bush 113 from the output side of the rotation shaft Ax1 .
  • the attachment plate 117 is a member for attaching the shaft as the output portion 102 to the bottom portion 322 of the flexible external gear 3 . Specifically, in a state where the portion around the penetration hole 34 in the bottom portion 322 is sandwiched between the mounting plate 117 and the flange portion of the output portion 102 , screws (bolts) are passed through the plurality of mounting holes 33 . The mounting plate 117 is fastened and fixed to the flange portion. Thereby, the shaft as the output portion 102 is fixed to the bottom portion 322 of the flexible external gear 3 .
  • FIG. 5A is a cross-sectional view of FIG. 1B looking at the inner teeth 21 and the outer teeth 31
  • FIG. 5B is a cross-sectional view taken along the line A1 - A1 in FIG. 5A
  • FIG. 6 is a conceptual explanatory diagram showing the dressing amounts Q1 and Q2 of the inner teeth 21 and the outer teeth 31 , and shows a state in which the meshing of the inner teeth 21 and the outer teeth 31 is released from the state shown in FIG. 5A
  • 7A is a cross-sectional view taken along line B1-B1 of FIG. 5A
  • FIG. 7B is a cross-sectional view taken along line B2-B2 of FIG. 5A
  • FIG. 7C is a cross-sectional view taken along line B3-B3 of FIG. 5A .
  • 8A is a cross-sectional view showing a tapered surface 302 inclined with respect to the rotation axis Ax1 in the inner peripheral surface 301 of the flexible external gear 3
  • FIG. 8B is an enlarged view of a region Z1 in FIG. 8A .
  • the drawings referred to in the embodiments of the present disclosure are schematic drawings, and the respective ratios of the sizes and thicknesses of the constituent elements in the drawings do not necessarily reflect the actual size ratios. Therefore, for example, in FIGS.
  • the dressing amounts Q1 and Q2 of the tooth direction dressing are shown to be large, and the gist is not limited to the actual shapes of the inner teeth 21 and the outer teeth 31 .
  • the hatching (hatched line) of a cross section is abbreviate
  • the surface hardness of the inner teeth 21 is lower than the surface hardness of the outer teeth 31 . That is, the surface of the outer teeth 31 is higher in hardness (harder) than the surface of the inner teeth 21 .
  • the "hardness" referred to in the embodiments of the present disclosure refers to the degree of hardness of an object, and the hardness of a metal is represented by, for example, the size of an indentation formed by pressing a steel ball with a certain pressure.
  • the hardness of metal there are Rockwell hardness (HRC), Brinell hardness (HB), Vickers hardness (HV), Shore hardness (Hs), and the like.
  • the hardness is represented by Vickers hardness (HV) unless it is particularly limited.
  • As means for increasing the hardness (hardening) of metal parts for example, alloying, heat treatment, and the like are exemplified.
  • the surfaces of the external teeth 31 of the flexible external gear 3 are 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 lower hardness than the external teeth 31 .
  • the outer teeth 31 are those obtained by subjecting nickel-chromium-molybdenum steel specified as "SNCM439" by Japanese Industrial Standards (JIS) to heat treatment (quenching and tempering).
  • the inner teeth 21 are made of spheroidal graphite cast iron specified by Japanese Industrial Standards (JIS) as "FCD800-2".
  • the surface hardness of the internal teeth 21 which becomes relatively low hardness compared with the external teeth 31 is HV350 or less.
  • the surface hardness of the inner teeth 21 is selected within a range of HV250 or more and less than HV350.
  • the lower limit value of the surface hardness of the inner 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 inner 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 having a relatively higher hardness than the internal teeth 21 is HV380 or more.
  • the surface hardness of the external teeth 31 is selected in the range of HV380 or more and HV450 or less.
  • the lower limit value 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, HV370, or the like.
  • the upper limit of the surface hardness of the inner 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 inner teeth 21 and the surface hardness of the outer teeth 31 is HV50 or more. That is, the surface hardness of the outer teeth 31 is set to be higher than the surface hardness of the inner teeth 21 by HV50 or more. In short, if the surface hardness of the inner teeth 21 is HV350, for example, the surface hardness of the outer teeth 31 is HV400 or more. Furthermore, if the surface hardness of the outer teeth 31 is HV380, the surface hardness of the inner teeth 21 is HV330 or less.
  • the difference between the surface hardness of the inner teeth 21 and the surface hardness of the outer teeth 31 is not limited to HV50 or more, and may be, for example, HV20 or more, HV30 or more, or HV40 or more.
  • the surface hardness of the inner teeth 21 is set to be lower than the surface hardness of the outer teeth 31 . Therefore, if the inner teeth 21 and the outer teeth 31 come into contact with each other when the harmonic gear device 1 is in operation, the inner teeth 21 having a relatively low surface hardness are worn more aggressively than the outer teeth 31 . When two members (the inner teeth 21 and the outer teeth 31 ) having different surface hardnesses come into contact, the wear of the relatively soft inner teeth 21 progresses, thereby suppressing the wear of the relatively hard outer teeth 31 .
  • the tooth surfaces of the inner teeth 21 are moderately worn, and as a result, the real contact area between the inner teeth 21 and the outer teeth 31 expands, and the surface pressure decreases, so the outer teeth 31 are worn out. difficult to produce. Furthermore, when the surface hardness of the inner teeth 21 is HV350 or less as in the present embodiment, even if the foreign matter X1 is generated due to the chipping or abrasion of the inner teeth 21 due to the contact between the inner teeth 21 and the outer teeth 31, the foreign matter X1 is relatively soft. quality.
  • the foreign matter X1 due to wear which is easily generated in the initial stage of use of the harmonic gear device 1 , is made into the soft foreign matter X1 generated from the relatively soft inner teeth 21 , so that, for example, even if the foreign matter X1 enters the bearing 42 , it is possible to prevent the foreign matter X1 from entering the bearing 42 . Damage to bearing 42. As a result, for example, it is possible to suppress the amount of generation of the hard foreign matter X1 that greatly damages the bearing 42 and the like. In particular, when the difference between the surface hardness of the inner teeth 21 and the surface hardness of the outer teeth 31 is a relatively large value such as HV50 or more, the above-mentioned effect is remarkable.
  • the effect of suppressing sintering of the tooth surfaces of the inner teeth 21 and the outer teeth 31 can be expected during the initial wear of the inner teeth 21 .
  • the lubricating effect of the meshing portion of the inner teeth 21 and the outer teeth 31 can be obtained, and the power transmission efficiency of the harmonic gear device 1 can be improved.
  • the surface hardness of the inner teeth 21 and the outer teeth 31 is not necessarily specified by the Vickers hardness (HV), and can also be determined 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 inner tooth 21 has a tooth bottom 212 and a tooth top 213 .
  • the inner teeth 21 are arranged on the inner peripheral surface of the rigid inner gear 2, so the tooth bottom 212 of the inner teeth 21 corresponds to the inner peripheral surface of the rigid inner gear 2, and the tooth tops 213 face inward from the inner peripheral surface of the rigid inner gear 2 (rigid inner gear 2). center of gear 2) protruding.
  • the outer teeth 31 have tooth bottoms 312 and tooth tops 313 .
  • the external teeth 31 are provided on the outer peripheral surface of the flexible external gear 3 (the body part 321 ), so the tooth bottom 312 of the external teeth 31 corresponds to the outer peripheral surface of the flexible external gear 3 (the body part 321 ), and the tooth tops 313 are from the flexible external gear 3 (the body part 321 ).
  • the outer peripheral surface of (the body portion 321 of) the external gear 3 protrudes outward.
  • the tooth tops 313 of the external teeth 31 are inserted between the adjacent pair of tooth tops 213 of the internal teeth 21 , so that the internal teeth 21 and the external teeth 31 are engaged.
  • the tooth tops 313 of the external teeth 31 are opposite to the tooth bottoms 212 of the internal teeth 21
  • the tooth tops 213 of the internal teeth 21 are opposite to the tooth bottoms 312 of the external teeth 31 .
  • the opposing tooth surfaces of the inner teeth 21 and the outer teeth 31 in the tooth thickness direction D2 (see FIG. 5B ) contact each other, and power is transmitted between the rigid inner gear 2 and the flexible outer gear 3 .
  • the inner teeth 21 have chamfered portions 211 at both end portions in the tooth direction D1.
  • the chamfered portion 211 is a C surface that reduces the protruding amount of the inner teeth 21 toward both sides of the tooth direction D1 , and is a portion that basically does not contribute to the meshing of the inner teeth 21 and the outer teeth 31 . That is, the chamfered portion 211 of the inner teeth 21 does not contact the outer teeth 31 even at the meshing positions of the inner teeth 21 and the outer teeth 31 .
  • the outer teeth 31 have chamfered portions 311 at both end portions in the tooth direction D1.
  • the chamfered portion 311 is a C surface that reduces the protruding amount of the inner teeth 21 toward both sides of the tooth direction D1, and is a portion that basically does not contribute to the meshing of the inner teeth 21 and the outer teeth 31. That is, the chamfered portion 311 of the external teeth 31 does not contact the internal teeth 21 even at the meshing positions of the internal teeth 21 and the external teeth 31 .
  • the internal teeth 21 of the rigid internal gear 2 have tooth direction trimming portions 210 . That is, in the harmonic gear device 1, at least the inner teeth 21 are trimmed in the tooth direction.
  • the tooth direction trimming portion 210 of the inner teeth 21 is provided at at least one end portion of the tooth direction D1.
  • the inner tooth 21 has the tooth direction trimming portion 210 at at least one end of the tooth direction D1 of the inner tooth 21 .
  • the tooth direction trimming parts 210 are provided at both ends of the tooth direction D1 of the inner teeth 21 .
  • the external teeth 31 of the flexible external gear 3 also have the tooth direction trimming portion 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 direction dressing.
  • the tooth direction trimming portion 310 of the external teeth is provided at at least one end portion of the tooth direction D1.
  • the external teeth 31 have the tooth direction trimming portion 310 at at least one end of the tooth direction D1 of the external teeth 31 .
  • the tooth direction trimming parts 310 are provided at both ends of the tooth direction D1 of the external teeth 31 .
  • the harmonic gear device 1 of the present embodiment at least one of the inner teeth 21 and the outer teeth 31 has the tooth direction trimming parts 210 and 310 .
  • the tooth direction dressing parts 210 and 310 can make it difficult to generate stress concentration caused by excessive tooth contact between the inner teeth 21 and the outer teeth 31 , and as a result, the tooth contact between the inner teeth 21 and the outer teeth 31 can be improved. Thereby, foreign matter X1 due to chipping, abrasion, etc. caused by the contact between the inner teeth 21 and the outer teeth 31 is less likely to be generated, and the harmonic gear device 1 with high reliability can be realized.
  • the tooth direction trimming portion 210 is provided at least on the inner teeth 21 .
  • the tooth direction trimming portion 210 is provided on the rigid internal gear 2 (internal teeth 21 ), thereby eliminating the need for tooth direction trimming for the flexible external gear 3 (external teeth 31 ) or reducing the amount of trimming, and it is easy to suppress the deflection of the flexible external gear 3 (external teeth 31 ).
  • the strength of the flexible external gear 3 is reduced due to the tooth orientation trimming of the flexible external gear 3 . That is, the flexible external gear 3 is formed of a relatively thin metal elastic body (metal plate) as described above, and has flexibility due to its relatively small (thin) thickness.
  • the flexible external gear 3 which is originally thin will become thinner, and the strength of the flexible external gear 3 may decrease.
  • the tooth bottom 312 of the external teeth 31 is subjected to excessive tooth direction trimming, it is difficult to secure the thickness required for the body portion 321 to maintain strength.
  • the tooth direction dressing portion 210 on the internal teeth 21, the tooth direction dressing of the flexible external gear 3 can be reduced in the amount of dressing, and as a result, the flexible external gear 3 can be easily maintained. Strength of.
  • the tooth direction trimming portions 210 and 310 are provided with the tooth direction trimming parts 210 and 310 . Therefore, it is not necessary to perform excessive tooth direction dressing on the inner teeth 21, and desired performance can be achieved by the tooth direction dressing with an appropriate amount of dressing.
  • the tooth direction trimming portion 210 of the inner teeth 21 is also referred to as the “first trimming portion”. 210"
  • the tooth direction trimming portion 310 of the external teeth 31 is referred to as a "second trimming portion 310".
  • the inner teeth 21 have the first trimming portion 210 as the tooth-direction trimming portion 210 .
  • the outer teeth 31 have a second trimming portion 310 , and the second trimming portion 310 is a tooth-direction trimming portion 310 that is different from the first trimming portion 210 .
  • the total of the dressing amount Q1 of the internal teeth 21 and the dressing amount Q2 of the external teeth 31 can be regarded as the The trimming amount of the tooth direction trimming of the teeth 31 . Therefore, if the dressing amount for the tooth direction dressing of the inner teeth 21 and the outer teeth 31 is the same amount, the dressing amount Q1 of the inner teeth 21 can be suppressed to be reduced compared with the case where the tooth direction dressing is performed only on the inner teeth 21 . The amount of the trimming amount Q2 of the small external teeth 31 . In FIG.
  • the normal tooth shape is represented by imaginary lines (dashed two-dotted lines), and the maximum displacement amounts from the normal tooth shape achieved by the tooth shape dressing are represented as dressing amounts Q1 and Q2 . That is, as shown in FIG. 6 , the trimming amount Q1 of the inner teeth 21 is the displacement amount (in the tooth height direction) of the center portion of the tooth direction D1 of the tooth tip 213 . Similarly, the trimming amount Q2 of the external teeth 31 is the displacement amount (in the direction of the tooth height) of the center portion of the tooth direction D1 with respect to the tooth tip 313 . In FIG.
  • the trimming amounts Q1 and Q2 of the tooth tops 213 and 313 are illustrated, but the trimming amounts are not limited to the tooth tops 213 and 313 , and the same applies to the trimming amounts of the tooth bottoms 212 and 312 or one end face in the tooth thickness direction D2 .
  • the tooth direction trimming portion (first trimming portion) 210 of the inner teeth 21 is formed by drum trimming. . That is, the 1st trim part 210 is formed by performing the process which rounds the inner teeth 21 toward the center part of the tooth direction D1 so that the center part of the tooth direction D1 may become convex.
  • the tooth direction trimming portion (second trimming portion) 310 of the outer teeth 31 is also formed by drum trimming. That is, the 2nd trimming part 310 is formed by performing the process of rounding the external teeth 31 toward the center part of the tooth direction D1 so that the center part of the tooth direction D1 becomes convex.
  • the first trimming portion 210 and the second trimming portion 310 include the same type of trimming. That is, both the first trimming portion 210 and the second trimming portion 310 are based on the same type of tooth direction trimming (here, drum trimming).
  • the tooth direction trimming portion (first trimming portion) 210 of the internal tooth 21 includes at least one of the tooth bottom 212 , the tooth top 213 , and the end face in the tooth thickness direction D2 of the inner tooth 21 including an inclined surface inclined with respect to the tooth direction D1 . That is, the tooth direction trimming portion 210 is formed by subjecting at least one of the tooth bottom 212 , the tooth top 213 , and the one end face in the tooth thickness direction D2 of the inner tooth 21 to machining for tooth direction trimming (here, drum trimming). . In the case of the tooth direction dressing of the tooth bottom 212, an inclined surface inclined with respect to the tooth direction D1 is formed in the tooth bottom 212 so that the tooth bottom 212 is lowered as it approaches both ends of the tooth direction D1.
  • an inclined surface inclined with respect to the tooth direction D1 is formed so that the tooth top 213 is lowered as it approaches both ends of the tooth direction D1.
  • the one end face in the tooth thickness direction D2 is formed with an inclination relative to the tooth direction D1 so that the tooth thickness decreases as it approaches both ends of the tooth direction D1 noodle.
  • the tooth bottom 212 , the tooth top 213 , and both end surfaces in the tooth thickness direction D2 of the inner tooth 21 are trimmed in the tooth direction.
  • the tooth direction trimming portion 210 includes an inclined surface at least on the tooth bottom 212 , so that the interference between the tooth tops 313 of the outer teeth 31 and the tooth bottoms 212 of the inner teeth 21 is easily avoided. That is, if the tooth bottom 212 of the inner tooth 21 is trimmed in the tooth direction, the clearance for the "relief portion" of the tooth tip 313 of the outer tooth 31 can be ensured, and the tooth tip 313 of the outer tooth 31 and the tooth of the inner tooth 21 can hardly be generated. Excessive stress concentration caused by interference of bottom 212.
  • the tooth direction trimming portion (second trimming portion) 310 includes at least one of the tooth bottom 312, the tooth top 313, and the end face in the tooth thickness direction D2 of the external teeth 31 including an inclination with respect to the tooth direction D1. noodle. That is, the tooth direction trimming portion 310 is formed by subjecting at least one of the tooth bottom 312 , the tooth top 313 , and the end face in the tooth thickness direction D2 of the external teeth 31 to machining for tooth direction trimming (here, drum trimming). In this embodiment, as shown in FIGS. 5A and 5B , the tooth bottom 312 , the tooth top 313 , and both end surfaces in the tooth thickness direction D2 of the external teeth 31 are trimmed in the tooth direction.
  • the tooth thicknesses of the inner teeth 21 and the outer teeth 31 are the largest at the center of the tooth direction D1, and go toward both ends of the tooth direction D1 by the tooth direction dressing performed on the both end surfaces in the tooth thickness direction D2. and gradually decreased. Therefore, regarding the meshing position of the inner teeth 21 and the outer teeth 31 , the gap between the inner teeth 21 and the outer teeth 31 is the smallest at the center portion where the tooth direction D1 is not subjected to tooth direction trimming (here, drum trimming).
  • the portion where the tooth direction dressing is not performed on the tooth direction D1 of the internal teeth 21 and the external teeth 31 that is, the portion that is still in the normal tooth direction shape is also referred to as a “non-dressing portion”. Therefore, in terms of the meshing positions of the inner teeth 21 and the outer teeth 31, basically, the inner teeth 21 and the outer teeth 31 first come into contact with each other at the "non-dressing portion" located at the center of the tooth direction D1.
  • FIG. 7A which shows the cross section of the center part of the tooth direction D1
  • the clearance gap G1 of the inner teeth 21 and the outer teeth 31 is the smallest. That is, the gap G1 between the inner teeth 21 and the outer teeth 31 increases toward one end of the tooth direction D1 (the output side of the rotation axis Ax1 ) in the order of FIGS. 7B and 7C .
  • the tooth direction dressing the tooth surface is gradually displaced in the negative direction as the distance from the center portion of the tooth direction D1 is increased, so that the gap G1 between the inner teeth 21 and the outer teeth 31 increases.
  • such a non-dressing portion (central portion in the tooth direction D1 ) is arranged at a position overlapping the rolling elements 423 of the bearing 42 in the tooth direction D1 .
  • the undressed portion (central portion of the tooth direction D1 ) is located on a straight line (imaginary straight line) that is orthogonal to the rotation axis Ax1 and passes through the center of the rolling elements 423 .
  • the first trimming portion 210 of the inner teeth 21 and the second trimming portion 310 of the outer teeth 31 have differences in the trimming amounts Q1 and Q2.
  • the trimming amount Q2 of the second trimming portion 310 is smaller than the trimming amount Q1 of the first trimming portion 210 (Q1>Q2).
  • the flexible external gear 3 has a function of elastic deformation (deflection), which is different from the power transmission function, and the stress generated by the deflection is inherent. Therefore, the external teeth 31 of the flexible external gear 3 are required to be resistant to bending stress. acceptability.
  • the root of the external teeth 31 is basically thin, and thus the resistance to bending stress is lowered, and the durability of the flexible external gear 3 is lowered.
  • the internal teeth 21 of the rigid internal gear 2 since the rigid internal gear 2 does not need to be elastically deformed, the internal teeth 21 of the rigid internal gear 2 also do not require resistance to bending stress. Therefore, even if the tooth root of the internal teeth 21 is thinned by performing the tooth direction trimming on the internal teeth 21 , the durability of the rigid internal gear 2 is hardly affected. Therefore, by making the dressing amount Q2 of the external teeth 31 smaller than the dressing amount Q1 of the internal teeth 21 , it is possible to ensure a sufficient dressing amount as the tooth direction dressing for the internal teeth 21 and the external teeth 31 and suppress the durability of the harmonic gear device 1 . Sexual decline.
  • the tooth direction trimming parts 210 are provided on both ends of the tooth direction D1 of the inner teeth 21 .
  • the tooth direction trimming portion 210 is provided at both the input side and the output side end portions of the rotation axis Ax1 of the inner teeth 21 . That is, the tooth direction trimming portion 210 is provided on at least the end portion on the side of the opening surface 35 in the tooth direction D1 of the internal teeth 21 .
  • the end of the flexible external gear 3 on the side of the opening surface 35 in the direction of the rotation axis Ax1 is deformed more than the end on the side of the bottom 322 , and becomes more A shape close to an oval shape.
  • the tooth direction trimming portion 210 can prevent stress concentration from occurring.
  • the tooth direction dressing part (1st dressing part) 210 of the internal tooth 21 is formed using the blade for scraping, for example. That is, with respect to the internal teeth 21 formed on the inner peripheral surface of the rigid internal gear 2, the tooth direction dressing portion 210 can be formed by the tooth direction dressing using the blade for scraping.
  • the scraping tool has a plurality of pinion-shaped cutting edge portions that form gear portions (internal teeth 21) on the workpiece (rigid internal gear 2).
  • the counter-rotating scraping tool is driven to rotate around a tool axis different from the workpiece axis, and rotates synchronously with the workpiece to cut the workpiece by relatively moving along the tooth direction D1.
  • the gear portion (internal teeth 21 ) to which the tooth direction trimming has been performed is formed on the workpiece (rigid internal gear 2 ).
  • tooth shape dressing is performed on the internal teeth 21 and the external teeth 31, but also tooth shape dressing is performed as shown in FIGS. 7A to 7C .
  • the amount of dressing is determined so as to satisfy the following conditions when the elastically deformed flexible external gear 3 is disposed inside the rigid internal gear 2 and power is not transmitted. That is, the condition is that no gap is generated near the pitch point of the meshing position of the internal teeth 21 and the external teeth 31, and a gap is generated between the tooth tops 313 of the external teeth 31 and the tooth bottoms 212 of the internal teeth 21, for example, about 0.1 modulus or more. gap.
  • the tooth profile of the inner teeth 21 and the outer teeth 31 is trimmed to have rounded corners toward the central portion in the tooth height direction so that the central portion in the tooth height direction becomes convex.
  • the external teeth 31 of the flexible external gear 3 protrude toward at least one of the tooth directions D1 with respect to the internal teeth 21 of the rigid internal gear 2 . That is, as described above, in the external teeth 31 of the flexible external gear 3 and the internal teeth 21 of the rigid internal gear 2, the position of the center of the tooth direction D1 corresponds to the same position in the direction of the rotation axis Ax1. In addition, the dimension (tooth width) of the tooth direction D1 of the outer teeth 31 is larger than the dimension (tooth width) of the tooth direction D1 of the inner teeth 21 . Therefore, in the tooth direction D1 , the inner teeth 21 are received within the range of the tooth direction of the outer teeth 31 , and the outer teeth 31 protrude toward at least one of the tooth directions D1 with respect to the inner teeth 21 .
  • the outer teeth 31 protrude in both sides of the tooth direction D1 (the input side and the output side of the rotation axis Ax1 ) with respect to the inner teeth 21 .
  • the outer teeth 31 protrude from the end edge of the inner teeth 21 by a protruding amount L1 toward one side of the tooth direction D1 (the input side of the rotation axis Ax1 ).
  • the outer teeth 31 protrude from the edge of the inner teeth 21 by a protruding amount L2 toward the other side of the tooth direction D1 (the output side of the rotation axis Ax1).
  • the protruding amounts L1 and L2 of the outer teeth 31 protruding from the inner teeth 21 are substantially the same on both sides of the tooth direction D1.
  • the protruding amounts L1 and L2 are represented by comparison of the portion other than the chamfered portion 211 of the inner teeth 21 and the portion of the outer teeth 31 other than the chamfered portion 311 . That is, on one side of the tooth direction D1 (input side of the rotation axis Ax1), the distance from the start point of the chamfered portion 211 of the inner teeth 21 to the start point of the chamfered portion 311 of the outer teeth 31 is the protrusion amount L1.
  • the distance from the start point of the chamfered portion 211 of the inner teeth 21 to the start point of the chamfered portion 311 of the outer teeth 31 is the protrusion amount L2.
  • the surface hardness of the inner teeth 21 is lower than the surface hardness of the outer teeth 31 . Furthermore, in the present embodiment, since the external teeth 31 with relatively high surface hardness protrude in at least one of the tooth directions D1 with respect to the internal teeth 21 , wear on the tooth surfaces of the internal teeth 21 is unlikely to occur in at least one of the tooth directions D1 resulting height difference. That is, on at least one of the tooth directions D1, the inner teeth 21 with relatively low surface hardness are uniformly worn by the tooth contact of the outer teeth 31, and local dents (height differences) are less likely to occur on the tooth surfaces of the inner teeth 21.
  • the outer teeth 31 protrude toward both sides of the tooth direction D1 with respect to the inner teeth 21 . That is, the outer teeth 31 protrude toward at least the opening surface 35 of the tooth direction D1 with respect to the inner teeth 21 .
  • the end of the flexible external gear 3 on the side of the opening surface 35 in the direction of the rotation axis Ax1 deforms more than the end on the side of the bottom 322 , and becomes more A shape close to an oval shape.
  • the inner peripheral surface 301 of the body portion 321 of the flexible external gear 3 Due to such a difference in the amount of deformation in the direction of the rotation axis Ax1, 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 generates relative to the rotation axis Ax1. Inclined tapered surface 302 (see FIG. 8A ).
  • the outer teeth 31 protrude from the inner teeth 21 on the side of the opening surface 35 of the tooth direction D1, so that the corners of the front ends of the outer teeth 31 inclined by the tapered surfaces 302 can be prevented from contacting the inner teeth 21. Therefore, even at the end portion on the opening surface 35 side of the tooth direction D1 where stress concentration due to deformation of the outer teeth 31 is particularly likely to occur, the tooth surface of the inner teeth 21 is less likely to be locally dented (difference in height).
  • the end of the flexible external gear 3 on the side of the opening surface 35 in the direction of the rotation axis Ax1 is deformed more than the end on the side of the bottom portion 322 , so that the A shape closer to an oval shape. Therefore, when the flexible external gear 3 is elastically deformed, as shown in FIGS. 8A and 8B , the inner peripheral surface 301 of the body portion 321 of the flexible external gear 3 includes a tapered surface 302 inclined with respect to the rotation axis Ax1 .
  • the tapered surface 302 is inclined by an inclination angle ⁇ 1 with respect to the rotation axis Ax1. Since such a tapered surface 302 is generated, the outer peripheral surface 424 (refer to FIG. 8B ) of the outer ring 421 of the bearing 42 of the wave generator 4 fitted to the inside of the body portion 321 and the inner peripheral surface 301 (tapered surface 302 ) The gap between them gradually increases toward the opening surface 35 side.
  • the inner peripheral surface 301 of the flexible external gear 3 has a tapered surface 302 at a position facing the outer peripheral surface 424 of the wave generator 4 (the outer ring 421 of the bearing 42 ), and the tapered surface 302 faces along the rotation axis Ax1
  • the gap with the outer peripheral surface 424 of the wave generator 4 is increased in one direction (the side of the opening surface 35 ).
  • the gap generated between the tapered surface 302 and the outer peripheral surface 424 of the wave generator 4 is a minute gap.
  • the minute gap generated between the tapered surface 302 and the outer peripheral surface 424 of the wave generator 4 is used for holding the lubricant Lb1 .
  • the liquid or gel lubricant Lb1 can be held in the minute gap between the tapered surface 302 and the outer peripheral surface 424 of the wave generator 4 .
  • liquid or gel lubricant is injected into the meshing portion of the inner teeth 21 and the outer teeth 31 and between the outer ring 421 and the inner ring 422 of the bearing 42 .
  • Agent Lb1 As an example, the lubricant Lb1 is a liquid lubricating oil (oil). Furthermore, when the harmonic gear device 1 is used, as shown in FIG. 8B , the lubricant Lb1 also enters between the outer ring 421 (outer peripheral surface 424 ) of the bearing 42 and the tapered surface 302 of the flexible external gear 3 . Thereby, the lubricant Lb1 seals the gap between the outer peripheral surface 424 and the tapered surface 302 .
  • the space on the input side (the right side in FIG. 8A ) of the rotation axis Ax1 and the space on the output side (the left side in FIG. 8A ) of the rotation axis Ax1 can pass through the outer peripheral surface 424 and the cone
  • the gaps of the shape surfaces 302 are connected.
  • the gap forming the narrow path connecting the outer side (input side of the rotation axis Ax1 ) and the inner side (the output side of the rotation axis Ax1 ) of the wave generator 4 is filled with the lubricant Lb1 .
  • the space on the input side of the rotating shaft Ax1 and the space on the output side of the rotating shaft Ax1 are shielded by the lubricant Lb1. Therefore, as shown in FIG. 8B , the entry of the foreign matter X1 from one side (input side) of the rotation axis Ax1 to the inside of the wave generator 4 is hindered by the lubricant Lb1 .
  • the lubricant Lb1 is held in the gap between the tapered surface 302 and the outer peripheral surface 424 of the wave generator 4 . More specifically, as shown in FIG. 8B , the lubricant Lb1 is held by the capillary phenomenon in the minute gap between the tapered surface 302 and the outer peripheral surface 424 of the wave generator 4 . Therefore, the state in which the gap between the tapered surface 302 and the outer peripheral surface 424 of the wave generator 4 is filled with the lubricant Lb1 can be maintained.
  • the magnitude of the holding force due to the capillary phenomenon also varies according to the "wettability" between the tapered surface 302 and the outer peripheral surface 424 and the lubricant Lb1. Therefore, at least the tapered surface 302 and the outer peripheral surface 424 preferably do not have oleophobicity.
  • the inclination angle ⁇ 1 of the tapered surface 302 with respect to the rotation axis Ax1 is not limited to 5 degrees or less, and may be, for example, 10 degrees or less, 15 degrees or less, or 20 degrees or less.
  • holding the lubricant Lb1 in the gap between the tapered surface 302 and the outer peripheral surface 424 of the wave generator 4 is not essential to the harmonic gear device 1, and the lubricant Lb1 may not be held in the gap.
  • the harmonic gear device 1 partially meshes the internal teeth 21 with the external teeth 31 in a state in which the flexible external gear 3 is elastically deformed. Therefore, the meshing of the internal teeth 21 and the external teeth 31 is accompanied by a tooth profile direction (with the The "slip" of the teeth in the direction orthogonal to D1) and the direction of the teeth D1. In addition, in the rotational speed region of the relative rotation of the two gears (the rigid internal gear 2 and the flexible external gear 3) during normal use of the harmonic gear device 1, the flow rate of the lubricant Lb1 is relatively low.
  • the flow of the relatively low-speed lubricant Lb1 is generated in both the tooth shape direction and the tooth direction D1, and the inner teeth 21 and the outer teeth are caused by the lubricant Lb1. It is difficult for the foreign matter X1 generated between the teeth 31 to flow to the outside of the harmonic gear device 1 . As a result, as described above, the foreign matter X1 that has already been generated tends to stop in the harmonic gear device 1 , and the foreign matter X1 enters the bearing 42 and the like, causing peeling of the surface starting point type, resulting in a decrease in the reliability of the harmonic gear device 1 . Condition.
  • the harmonic gear device 1 of the present embodiment it is difficult to generate the foreign matter X1 in the first place, so that the above-mentioned problems caused by the countermeasures for the bearing 42 can also be eliminated. That is, in the harmonic gear device 1, it is particularly useful to suppress the generation of the foreign matter X1 as in the present embodiment, and thus, there is an advantage that not only is the reliability of the harmonic gear device 1 less likely to be degraded, but also easy to implement. Longer life and improved power transmission efficiency.
  • the function as the bearing 42 is hindered, and the operation as the harmonic gear device 1 may fail.
  • the harmonic gear device 1 of the present embodiment it is inherently difficult to generate the foreign matter X1 , so that the entry of such foreign matter X1 into the bearing 42 can be overwhelmingly reduced, thereby contributing to the reliability of the harmonic gear device 1 . improve. In particular, even in long-term use, the reliability is hardly deteriorated, and therefore, it also contributes to the longer life and higher performance of the harmonic gear device 1 .
  • the surface hardness of the inner teeth 21 is lower than the surface hardness of the outer teeth 31 . Therefore, the tooth width of the inner teeth 21 is larger than the tooth width of the outer teeth 31, and when the outer teeth 31 are retracted within the range of the tooth direction of the inner teeth 21, a part of the tooth direction D1 of the tooth surface of the inner teeth 21 will be Due to wear and the like due to the contact of the teeth 31, local dents (differences in height) may occur. In such a state where the depression is generated, if the tooth contact position deviates in the tooth direction (in the direction parallel to the rotation axis Ax1) due to some jitter, the meshing portion between the inner teeth 21 and the outer teeth 31 will act.
  • the external teeth 31 protrude in at least one of the tooth directions D1 with respect to the internal teeth 21 . Therefore, in at least one of the tooth directions D1, the inner teeth 21 with relatively low surface hardness are uniformly worn due to the tooth contact of the outer teeth 31, and the tooth surfaces of the inner teeth 21 are less likely to be locally dented (differences in height). Therefore, even if the tooth contact position deviates in the tooth direction D1 due to some jitter, it is easy to suppress the harmonic gear device 1 from causing excessive load to act on the meshing portion between the inner teeth 21 and the outer teeth 31 . Exception generation. That is, it is difficult to generate a corner portion of the outer teeth 31 such as the one end portion of the tooth direction D1, and as a result, it is difficult to generate a hard (comparatively high hardness) foreign material X1.
  • the tooth direction trimming portion 210 is provided at least at the end portion on the side of the opening surface 35 of the tooth direction D1 of the internal teeth 21 .
  • the meshing between the inner teeth 21 and the outer teeth 31 is reduced at the end on the opening surface 35 side where the sliding amount in the tooth direction D1 is particularly large, thereby reducing meshing loss and improving power transmission efficiency.
  • the startability of the harmonic gear device 1 in a low temperature environment where the lubricant Lb1 is easily hardened can be realized by improving the power transmission efficiency. improve.
  • FIG. 9 is a cross-sectional view showing an example of a robot 9 using the harmonic gear device 1 of the present embodiment.
  • the robot 9 is a horizontal multi-joint robot, a so-called Selective Compliance Assembly Robot Arm (SCARA: Selective Compliance Assembly Robot Arm) type robot.
  • SCARA Selective Compliance Assembly Robot Arm
  • the robot 9 includes two harmonic gear devices 1 and a connecting rod 91 .
  • the two harmonic gear devices 1 are respectively provided in the joint parts of two parts in the robot 9 .
  • the link 91 connects the joint parts of the two parts.
  • the harmonic gear device 1 is not a cup type, but is constituted by a top hat type harmonic gear device. That is, in the harmonic gear device 1 illustrated in FIG. 9 , the flexible external gear 3 formed in the shape of a hat is used.
  • FIGS. 10A to 10D illustrate a modification of the above-described embodiment, and are diagrams illustrating the relationship between the inner teeth 21 and the outer teeth 31 , corresponding to the cross-sectional view taken along the line A1 - A1 in FIG. 5A .
  • the hatching (shaded line) of the cross section is omitted.
  • the tooth direction trimming portions (first trimming portions) 210 of the inner teeth 21 are formed only on the rotation of the flexible external gear 3 on both end surfaces in the tooth thickness direction D2 of the inner teeth 21 .
  • the tooth direction trimming portion (second trimming portion) 310 of the external teeth 31 is formed only on one end surface on the opposite side to the rotation direction R1 of the flexible external gear 3 among both end surfaces in the tooth thickness direction D2 of the external teeth 31 . .
  • the tooth-direction dressing portions (first dressing portions) 210 of the internal teeth 21 are formed only on the rotation of the flexible external gear 3 on both end surfaces in the tooth thickness direction D2 of the internal teeth 21 .
  • the tooth direction trimming portion (second trimming portion) 310 of the external teeth 31 is formed only on one end surface on the rotational direction R1 side of the flexible external gear 3 among both end surfaces in the tooth thickness direction D2 of the external teeth 31 . Even in this configuration, the same effects as those of the above-described embodiment can be expected by the tooth-direction trimming parts 210 and 310 .
  • only the inner teeth 21 and the outer teeth 31 are provided with a tooth direction trimming portion (first trimming portion) 210 , and the outer teeth 31 are not provided with a tooth direction trimming portion.
  • first trimming portion first trimming portion
  • the outer teeth 31 are not provided with a tooth direction trimming portion.
  • the same effects as those of the above-described embodiment can be expected by the tooth-direction trimming portion 210 .
  • only the outer teeth 31 of the internal teeth 21 and the external teeth 31 may be provided with the tooth direction trimming portion (second trimming portion) 310, and the inner teeth 21 may not be provided with the tooth direction trimming portion.
  • the tooth direction trimmer (first trimmer) 210 is provided only at one end of the tooth direction D1 of the inner teeth 21 , and the teeth are provided only at one end of the tooth direction D1 of the outer teeth 31 .
  • the trimming part (second trimming part) 310 is provided to the trimming part (second trimming part) 310 .
  • the tooth direction trimming parts 210 and 310 are both provided at the ends on the side of the opening surface 35 in the tooth direction D1.
  • at least one of the tooth direction trimming parts 210 and 310 may be provided at the end portion on the opposite side of the opening surface 35 in the tooth direction D1.
  • the configurations of the modified examples shown in FIGS. 10A to 10D can be appropriately combined and applied.
  • the third modification example and the fourth modification example only the inner teeth 21 of the inner teeth 21 and the outer teeth 31 can be provided with the tooth direction trimming portion 210 , and the tooth direction trimming portion 210 can be provided only on the inner teeth 21 .
  • the teeth face one end of D1.
  • the harmonic gear device 1 it is not necessary for the harmonic gear device 1 to perform tooth profile modification on the inner teeth 21 and the outer teeth 31 .
  • at least one of the inner teeth 21 and the outer teeth 31 may not be trimmed.
  • the structure in which the inner teeth 21 have the tooth direction dressing portion 210 and the structure in which the surface hardness of the inner teeth 21 is lower than the surface hardness of the outer teeth 31 and the outer teeth 31 protrude in at least one of the teeth direction D1 relative to the inner teeth 21 may be respectively used alone. That is, even if the surface hardness of the inner teeth 21 is lower than the surface hardness of the outer teeth 31 alone, and the outer teeth 31 protrude in at least one of the teeth directions D1 relative to the inner teeth 21, it is difficult to cause the inner teeth 21 and the outer teeth 31 to Foreign matter X1 caused by defects or wear caused by contact. Therefore, even if the inner teeth 21 do not have the tooth direction dressing portion 210 , the harmonic gear device 1 with high reliability can be realized.
  • the structure which holds the lubricant Lb1 in the clearance gap between the tapered surface 302 and the outer peripheral surface 424 of the wave generator 4 it can also be used independently. That is, even if the inner teeth 21 do not have the tooth direction trimming portion 210 and the outer teeth 31 do not protrude in at least one of the tooth directions D1 with respect to the inner teeth 21, the gap between the tapered surface 302 and the outer peripheral surface 424 of the wave generator 4 The lubricant Lb1 can also be held.
  • the harmonic gear device 1 is not limited to the cup type described in the above-mentioned embodiment, and may be, for example, a hat type, a ring type, a differential type, a flat type (flat type), a casing type, or the like.
  • a hat-shaped harmonic gear device 1 as illustrated in FIG. 9 may be used, which has a cylindrical flexible external gear 3 having an opening surface 35 on one side of the tooth direction D1 as in the cup type. That is, the hat-shaped flexible external gear 3 has a flange portion at one end portion of the rotation axis Ax1, and has an opening surface 35 at an end portion opposite to the flange portion. Even the hat-shaped flexible external gear 3 has external teeth 31 at the end on the opening surface 35 side, and the wave generator 4 is fitted therein.
  • the configuration of the actuator 100 is not limited to the configuration described in the above-mentioned embodiment, and can be appropriately changed.
  • the connection structure between the input portion 103 and the cam 41 is not limited to the spline connection structure, and an Oldham joint or the like can be used.
  • the Oldham joint as the connection structure between the input portion 103 and the cam 41 , the eccentricity between the input-side rotary shaft Ax1 and the wave generator 4 (cam 41 ) can be canceled, and the rigid internal gear 2 and the cam 41 can be The eccentricities of the flexible external gear 3 cancel each other out.
  • the cam 41 may be immovable along the rotation axis Ax1 with respect to the input portion 103 .
  • the application example of the harmonic gear device 1 and the actuator 100 of the present embodiment is not limited to the above-mentioned horizontal articulated robot, for example, an industrial robot other than a horizontal articulated robot, a robot other than an industrial robot, etc. may be used.
  • industrial robots other than the horizontal articulated robot include a vertical articulated robot, a parallel link robot, and the like.
  • robots other than industrial use there are a home robot, a nursing robot, a medical robot, and the like.
  • the bearing 42 is not limited to a deep groove ball bearing, For example, an angular contact ball bearing or the like may be used.
  • the bearing 42 is not limited to a ball bearing,
  • a roller bearing such as a cylindrical roller bearing, a needle roller bearing, or a tapered roller bearing in which the rolling elements 423 are composed of "rollers" that are not spherical may be used.
  • each component of the harmonic gear device 1 or the actuator 100 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), and may be a gel substance such as grease.
  • the protrusion amounts L1 and L2 of the outer teeth 31 from the inner teeth 21 are not limited to be substantially the same on both sides in the tooth direction D1.
  • the protrusion amount L1 on one side of the tooth direction D1 may be larger than the protrusion amount L2 on the other side (the output side of the rotation axis Ax1 ) of the teeth direction D1 .
  • the protruding amount L1 of the teeth on one side of D1 (the input side of the rotation axis Ax1 ) may be smaller than the protrusion amount L2 of the teeth on the other side (the output side of the rotation axis Ax1 ) of the teeth.
  • the trimming amount Q2 of the second trimming portion 310 is smaller than the trimming amount Q1 of the first trimming portion 210 is not an essential configuration for the harmonic gear device 1 .
  • the tooth direction trimming portion (first trimming portion) 210 of the inner teeth 21 is formed by edge trimming, which is similar to the harmonic wave of the above-described embodiment.
  • the gear unit 1 is different.
  • symbol is attached
  • FIG. 11A is a sectional view focusing on the inner teeth 21 and the outer teeth 31
  • FIG. 11B is a sectional view taken along the line A1-A1 in FIG. 11A
  • 12A is a cross-sectional view taken along line B1-B1 of FIG. 11A
  • FIG. 12B is a cross-sectional view taken along line B2-B2 of FIG. 11A
  • FIG. 12C is a cross-sectional view taken along line B3-B3 of FIG. 11A .
  • the tooth direction trim portion (first trim portion) 210 of the inner teeth 21 is formed by drum trimming in the above-described embodiment, but is formed by edge trimming in the present embodiment. That is, the first trimming portion 210 processes only the both ends of the tooth direction D1 so that the center portion of the tooth direction D1 becomes convex, the center portion of the tooth direction D1 is still a regular tooth direction shape, and the inner teeth 21 are processed. Cone shaped.
  • the tooth-direction trimming portion (second trimming portion) 310 of the external teeth 31 is formed by edge trimming. In this way, the first trimming portion 210 and the second trimming portion 310 are both based on the same type of tooth direction trimming (here, trimming).
  • the tooth bottom 212 , the tooth top 213 , and both end surfaces in the tooth thickness direction D2 of the inner tooth 21 are subjected to tooth direction dressing by edge processing.
  • tooth direction dressing by edging is performed on the tooth bottoms 312 , the tooth tops 313 , and both end surfaces in the tooth thickness direction D2 of the external teeth 31 .
  • the respective tooth thicknesses of the inner teeth 21 and the outer teeth 31 are the largest at the center of the tooth direction D1 , and the tooth thicknesses of the inner teeth 21 and the outer teeth 31 are the largest in the center part of the tooth direction D1 , and the tooth thickness is increased toward the teeth after the start point of the trimming process. It gradually decreases towards both ends of D1. Therefore, at the meshing position of the internal teeth 21 and the external teeth 31, in the tooth direction D1, in the center part (non-trimming part) where the tooth direction dressing (here, the edge trimming) is not performed, the internal teeth 21 and the external teeth The gap of 31 becomes minimal.
  • the gap G1 between the inner teeth 21 and the outer teeth 31 is the smallest in FIG. 12A , which is a cross section at the start point of the trimming process in the tooth direction D1 . That is, the gap G1 between the inner teeth 21 and the outer teeth 31 increases toward one end of the tooth direction D1 (the output side of the rotation axis Ax1 ) in the order of FIGS. 12B and 12C . In this way, the tooth surface is gradually displaced in the negative direction as it is separated from the center portion of the tooth direction D1 by the tooth direction dressing, so that the gap G1 between the inner teeth 21 and the outer teeth 31 increases.
  • the first trimming portion 210 and the second trimming portion 310 may have different types of tooth directions, as in the case where the first trimming portion 210 is edged and the second trimming portion 310 is drum trimmed. trim.
  • the first trimming portion 210 may be drum-shaped trimming
  • the second trimming portion 310 may be trimming.
  • the harmonic gear device 1B differs from the harmonic gear device 1 of the above-described embodiment in that the external teeth 31 protrude in only one of the tooth directions D1 with respect to the internal teeth 21 .
  • FIG. 13 is a cross-sectional view focusing on the inner teeth 21 and the outer teeth 31, and the hatching (shaded line) of the cross section is omitted.
  • symbol is attached
  • the external teeth 31 protrude to both sides of the tooth direction D1 (the input side and the output side of the rotation axis Ax1 ) with respect to the internal teeth 21 . Protrudes unilaterally toward the teeth toward D1.
  • the outer teeth 31 protrude toward the opening surface 35 side of the tooth direction D1 , that is, the input side of the rotation axis Ax1 , with respect to the inner teeth 21 .
  • the outer teeth 31 protrude toward the opening surface 35 of the tooth direction D1 (the input side of the rotation axis Ax1 ) with respect to the inner teeth 21 , and do not protrude toward the opposite side (the rotation axis) of the opening surface 35 of the tooth direction D1
  • the output side of Ax1) protrudes.
  • the end of the flexible external gear 3 on the side of the opening surface 35 in the direction of the rotation axis Ax1 is deformed more than the end on the side of the bottom portion 322 , and becomes more A shape close to an oval shape.
  • the outer teeth 31 protrude from the inner teeth 21 on the side of the opening surface 35 of the tooth direction D1, whereby the corners of the front ends of the outer teeth 31 and the inner teeth which are inclined by the tapered surfaces 302 can be avoided. 21 contacts.
  • the tooth surface of the inner teeth 21 it is difficult for the tooth surface of the inner teeth 21 to locally dent in the tooth surface of the inner teeth 21 at the end portion on the side of the opening surface 35 of the tooth direction D1 where stress concentration due to deformation of the outer teeth 31 is particularly likely to occur. (Height difference).
  • the external teeth 31 may correspond to the internal teeth 21, and may protrude only to the side opposite to the opening surface 35 of the teeth direction D1, that is, to the output side of the rotation axis Ax1.
  • the outer teeth 31 do not protrude toward the opening surface 35 side of the tooth direction D1 (the input side of the rotation axis Ax1 ) with respect to the inner teeth 21 .
  • the harmonic gear device (1, 1A, 1B) of the first form 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 which has external teeth (31) and is arranged inside the rigid internal gear (2).
  • the wave generator (4) is arranged inside the flexible external gear (3), and causes the flexible external gear (3) to flex.
  • the harmonic gear device (1, 1A, 1B) deforms the flexible external gear (3) along with the rotation of the wave generator (4) centered on the rotation axis (Ax1), and causes a part of the external teeth (31) to be in contact with each other.
  • a part of the internal teeth (21) meshes so that the flexible external gear (3) rotates relative to the rigid internal gear (2) according to the difference in the number of teeth between the flexible external gear (3) and the rigid internal gear (2).
  • the inner teeth (21) have a tooth direction trimming part (210) at at least one end of the tooth direction (D1) of the inner teeth (21).
  • a "relief portion” is formed between the tooth direction trimming portion (210) of the inner teeth (21) and the outer teeth (31), and at least one end of the tooth direction (D1) of the inner teeth (21) is formed.
  • the stress concentration caused by excessive tooth contact with the outer teeth (31) can hardly be generated.
  • the wave generator (4) deflects the flexible external gear (3), thereby sometimes generating external teeth (31) with respect to the rotation axis (Ax1). deformation such as torsion and deflection (tilt).
  • the inner teeth (21) have a first trimming portion (210) as a tooth direction trimming portion (210).
  • the outer teeth (31) have a second trimming portion (310), and the second trimming portion (310) is a tooth-direction trimming portion (310) different from the first trimming portion (210).
  • both the inner teeth (21) and the outer teeth (31) have the tooth direction trimming parts (210, 310), the tooth contact between the inner teeth (21) and the outer teeth (31) can be improved.
  • the trimming amount (Q2) of the second trimming portion (310) is greater than the trimming amount (Q2) of the first trimming portion (210).
  • Q1 Small.
  • the first trimming part (210) and the second trimming part (310) include the same type of trimming.
  • the processing of the first trimming portion (210) and the second trimming portion (310) is easy.
  • the inner peripheral surface (301) of the flexible external gear (3) is connected to the harmonic wave generator.
  • the portion facing the outer peripheral surface (424) of (4) has a tapered surface (302).
  • the tapered surface (302) increases the gap with the outer peripheral surface (424) of the wave generator (4) toward one direction along the rotation axis (Ax1).
  • the lubricant (Lb1) is held in the gap between the tapered surface (302) and the outer peripheral surface (424) of the wave generator (4).
  • the inclination angle ( ⁇ 1) of the tapered surface (302) with respect to the rotation axis (Ax1) is 5 degrees or less.
  • the gap between the tapered surface (302) and the outer peripheral surface (424) of the wave generator (4) can be made a small gap, for example, the lubricant (Lb1) can be held by capillary action.
  • the tooth direction dressing portion (210) is formed on the tooth bottom (212) of the inner tooth (21).
  • at least one of the tooth tip (213) and one end surface in the tooth thickness direction (D2) includes an inclined surface. The inclined surface is inclined with respect to the tooth direction (D1).
  • the tooth contact can be improved by trimming at least one of the tooth bottom (212), tooth top (213), and one end face in the tooth thickness direction (D2) of the inner tooth (21).
  • the tooth direction trimming portion (210) includes an inclined surface at least on the tooth bottom (212).
  • the flexible external gear (3) has an opening surface in one of the tooth directions (D1). (35) cylindrical shape.
  • the tooth direction trimming portion (210) is provided on at least the end portion on the side of the opening surface (35) of the tooth direction (D1) of the internal teeth (21).
  • the tooth direction trimming portion (210) can be less likely to occur. Stress concentration.
  • the actuator (100) of the tenth aspect includes the harmonic gear device (1, 1A, 1B) of any one of the first to ninth aspects, a drive source (101), and an output unit (102).
  • the drive source (101) rotates the wave generator (4).
  • the output part (102) takes out the rotational force of any one of the rigid internal gear (2) and the flexible external gear (3) as an output.
  • foreign matter (X1) caused by chipping or abrasion caused by the contact between the inner teeth (21) and the outer teeth (31) is less likely to be generated, and a highly reliable actuator (100) can be provided.
  • the configuration of the harmonic gear device (1, 1A, 1B) of the fifth aspect can be adopted independently regardless of the presence or absence of the tooth direction dressing portion (210) of the first aspect. That is, the harmonic gear device (1, 1A, 1B) 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 which has external teeth (31) and is arranged inside the rigid internal gear (2).
  • the wave generator (4) is arranged on the inner side of the flexible external gear (3), and bends the flexible external gear (3).
  • the harmonic gear device (1, 1A, 1B) deforms the flexible external gear (3) along with the rotation of the wave generator (4) centered on the rotation axis (Ax1), so that a part of the external teeth (31) is A part of the internal teeth (21) meshes, so that the flexible external gear (3) rotates relative to the rigid internal gear (2) according to the difference in the number of teeth between the flexible external gear (3) and the rigid internal gear (2).
  • the inner peripheral surface (301) of the flexible external gear (3) has a tapered surface (302) at a position opposite to the outer peripheral surface (424) of the wave generator (4).
  • the tapered surface (302) increases the gap with the outer peripheral surface (424) of the wave generator (4) toward one direction along the rotation axis (Ax1).
  • the lubricant (Lb1) is held in the gap between the tapered surface (302) and the outer peripheral surface (424) of the wave generator (4).
  • the configurations of the second to ninth aspects are not essential to the harmonic gear device (1, 1A, 1B), and can be appropriately omitted.
  • Tooth trimming section (first trimming section)
  • a highly reliable harmonic gear device and an actuator can be provided.

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Abstract

一种可靠性高的谐波齿轮装置(1)及执行器(100)，该谐波齿轮装置(1)包括刚性内齿轮(2)、挠性外齿轮(3)和波发生器(4)，刚性内齿轮(2)是具有内齿(21)的环状的部件，挠性外齿轮(3)是具有外齿(31)且配置在刚性内齿轮(2)的内侧的环状的部件，波发生器(4)配置在挠性外齿轮(3)的内侧，使挠性外齿轮(3)产生挠曲，该谐波齿轮装置(1)伴随着以旋转轴(Ax1)为中心的波发生器(4)的旋转而使挠性外齿轮(3)变形，使外齿(31)的一部分与内齿(21)的一部分啮合，从而使挠性外齿轮(3)根据挠性外齿轮(3)与刚性内齿轮(2)的齿数差而相对于刚性内齿轮(2)相对旋转，内齿(21)在内齿(21)的齿向(D1)的至少一方的端部具有齿向修整部(210)。

Description

谐波齿轮装置及执行器
相关申请的交叉引用
本申请基于申请号为特愿2020-174376、申请日为2020年10月16日的日本专利申请提出，并要求上述日本专利申请的优先权，该日本专利申请的全部内容在此引入本申请作为参考。
技术领域
本公开实施例一般性涉及谐波齿轮装置及执行器，更详细而言，涉及具备刚性内齿轮、挠性外齿轮和波发生器的谐波齿轮装置及执行器。
背景技术
在专利文献1中公开了通过渗氮进行谐波齿轮装置(挠曲啮合式齿轮装置)中的挠性外齿轮的表面处理。
谐波齿轮装置具有：环状的刚性内齿轮；配置于其内侧的杯形的挠性外齿轮；和嵌入其内侧的椭圆形的波发生器。挠性外齿轮包括圆筒状的躯体部和形成于躯体部的外周面的外齿。挠性外齿轮通过波发生器而挠曲为椭圆形，位于该椭圆形状的长轴方向的两端的外齿的部分与形成于刚性内齿轮的内周面的内齿啮合。
当波发生器通过马达等旋转时，两个齿轮的啮合位置沿圆周方向移动，在两个齿轮之间产生与内齿和外齿的齿数差(2N(N为正整数))对应的相对旋转。此处，当刚性内齿轮一侧被固定时，能够从挠性外齿轮一侧得到与两个齿轮的齿数差相应地被大幅减速了的旋转输出。
现有技术文献
专利文献
专利文献1：日本特开2001-59153号公报
发明内容
然而，由于谐波齿轮装置一边使挠性外齿轮挠曲一边通过内齿与外齿的啮合而进行动力的传递，所以特别是如果长时期使用的话，则例如由于内齿与外齿的接触所引起的缺欠或磨损等而会产生金属粉或氮化物等异物。由于产生这样的异物，因此可能导致在内齿及外齿间有异物啮入或是异物进入波发生器的轴承而引起轴承损伤，从而可能给谐波齿轮装置的可靠性造成影响。
本公开实施例鉴于上述事由而作出，其目的在于提供可靠性高的谐波齿轮装置及执行器。
本公开实施例的一方式的谐波齿轮装置包括刚性内齿轮、挠性外齿轮和波发生器。所述刚性内齿轮是具有内齿的环状的部件。所述挠性外齿轮是具有外齿且配置在所述刚性内齿轮的内侧的环状的部件。所述波发生器配置在所述挠性外齿轮的内侧并使所述挠性外齿轮产生挠曲。所述谐波齿轮装置伴随着以旋转轴为中心的所述波发生器的旋转而使所述挠性外齿轮变形，使所述外齿的一部分与所述内齿的一部分啮合，从而使所述挠性外齿轮根据所述挠性外齿轮与所述刚性内齿轮的齿数差而相对于所述刚性内齿轮相对旋转。所述内齿在所述内齿的齿向的至少一方的端部具有齿向修整部。
本公开实施例的一方式的执行器包括上述的谐波齿轮装置、驱动源和输出部。所述驱动源使所述波发生器旋转。所述输出部将所述刚性内齿轮及所述挠性外齿轮的任一方的旋转力取出而作为输出。
根据本公开实施例，具有能够提供可靠性高的谐波齿轮装置及执行器。
附图说明
图1A是示出一实施方式的谐波齿轮装置的概略结构的剖视图。
图1B是图1A的区域Z1的放大图。
图2是从旋转轴的输入侧观察到的上述的谐波齿轮装置的概略图。
图3A是从旋转轴的输出侧观察到的上述的谐波齿轮装置的概略分解立体图。
图3B是从旋转轴的输入侧观察到的上述的谐波齿轮装置的概略分解立体图。
图4是示出包含上述的谐波齿轮装置的执行器的概略结构的剖视图。
图5A是着眼于上述的谐波齿轮装置的内齿及外齿观察到的概略剖视图。
图5B是图5A的A1-A1线剖视图。
图6是用于示出上述的谐波齿轮装置的内齿及外齿的修整量的概念性说明图。
图7A是图5A的B1-B1线剖视图。
图7B是图5A的B2-B2线剖视图。
图7C是图5A的B3-B3线剖视图。
图8A是上述的谐波齿轮装置的挠性外齿轮的内周面周边的概略剖视图。
图8B是图8A的区域Z1的放大图。
图9是示出使用了上述的谐波齿轮装置的机器人的一例的剖视图。
图10A是一实施方式的第一变形例的谐波齿轮装置的主要部分的剖视图。
图10B是一实施方式的第二变形例的谐波齿轮装置的主要部分的剖视图。
图10C是一实施方式的第三变形例的谐波齿轮装置的主要部分的剖视图。
图10D是一实施方式的第四变形例的谐波齿轮装置的主要部分的剖视图。
图11A是着眼于另一实施方式的谐波齿轮装置的内齿及外齿观察到的概略剖视图。
图11B是图11A的A1-A1线剖视图。
图12A是图11A的B1-B1线剖视图。
图12B是图11A的B2-B2线剖视图。
图12C是图11A的B3-B3线剖视图。
图13是着眼于再一实施方式的谐波齿轮装置的内齿及外齿观察到的概略剖视图。
具体实施方式
(1)概要
以下，参照图1A～图4，说明本实施方式的谐波齿轮装置1的概要。本公开实施例所参照的附图均为示意图，图中的各构成要素的大小及厚度各自的比不一定限于反映实际的尺寸比。例如，图2～图3B中的、内齿21及外齿31的齿形、尺寸及齿数等都只不过是为了说明而示意性地表示的，其主旨并非限定于图示的形状。
本实施方式的谐波齿轮装置1是包括刚性内齿轮2、挠性外齿轮3和波发生器4的齿轮装置。该谐波齿轮装置1中，在环状的刚性内齿轮2的内侧配置有环状的挠性外齿轮3，进一步在挠性外齿轮3的内侧配置有波发生器4。波发生器4通过使挠性外齿轮3挠曲为非圆形状，从而使挠性外齿轮3的外齿31局部性地与刚性内齿轮2的内齿21啮合。当波发生器4旋转时，内齿21与外齿31的啮合位置沿刚性内齿轮2的圆周方向移动，并在两个 齿轮(刚性内齿轮2和挠性外齿轮3)之间产生使挠性外齿轮3按照与刚性内齿轮2的齿数差进行的相对旋转。此处，如果刚性内齿轮2被固定，则挠性外齿轮3伴随着两个齿轮的相对旋转而旋转。其结果是，可从挠性外齿轮3获得与两个齿轮的齿数差相应地、按照比较高的减速比进行了减速的旋转输出。
另外，使挠性外齿轮3产生挠曲的波发生器4具有以输入侧的旋转轴Ax1(参照图1A)为中心被驱动旋转的非圆形状的凸轮41、和轴承42。轴承42配置于凸轮41的外周面411与挠性外齿轮3的内周面301之间。轴承42的内圈422固定于凸轮41的外周面411，轴承42的外圈421通过滚珠状的滚动体423被凸轮41按压而弹性变形。此处，通过滚动体423滚动，外圈421能够相对于内圈422相对地旋转，因此当非圆形状的凸轮41旋转时，内圈422的旋转不传递至外圈421，而是在被凸轮41按压的挠性外齿轮3的外齿31发生谐波运动。由于发生外齿31的谐波运动，所以如上所述内齿21与外齿31的啮合位置沿刚性内齿轮2的圆周方向移动，从而在挠性外齿轮3与刚性内齿轮2之间发生相对旋转。
总而言之，在这种谐波齿轮装置1中，具有轴承42的波发生器4一边使挠性外齿轮3挠曲一边实现通过内齿21与外齿31的啮合而进行的动力传递。因此，特别是如果长期使用，则例如由于内齿21与外齿31的接触，因缺欠或磨损等而会产生金属粉或氮化物等异物X1(参照图8B)。由于产生这样的异物X1，因此可能导致在内齿21及外齿31间有异物X1啮入或异物X1进入波发生器4的轴承42而引起轴承42损伤，从而可能会影响谐波齿轮装置1的可靠性。作为一例，当异物X1进入轴承42时，以异物X1向轴承42的外圈421或内圈422与滚动体423之间啮入而产生的压痕为起点，在外圈421、内圈422及滚动体423的某表面会产生损伤。这样的损伤(表面起点型的剥落)会导致谐波齿轮装置1的品质及特性等的劣化，其结果是导致谐波齿轮装置1的可靠性下降。本实施方式的谐波齿轮装置1 通过以下的结构使异物X1难以产生，由此不容易产生可靠性下降。
即，如图1A～图3B所示，本实施方式的谐波齿轮装置1包括：具有内齿21的环状的刚性内齿轮2；具有外齿31的环状的挠性外齿轮3；波发生器4。挠性外齿轮3配置在刚性内齿轮2的内侧。波发生器4配置在挠性外齿轮3的内侧，使挠性外齿轮3产生挠曲。谐波齿轮装置1伴随着以旋转轴Ax1为中心的波发生器4的旋转而使挠性外齿轮3变形，使外齿31的一部分与内齿21的一部分啮合，使挠性外齿轮3根据与刚性内齿轮2的齿数差而相对于刚性内齿轮2相对旋转。其中，内齿21在内齿21的齿向D1的至少一方的端部具有齿向修整部210。
根据该方式，内齿21在内齿21的齿向D1的至少一方的端部具有齿向修整部210。在内齿21的齿向修整部210与外齿31之间形成“避让部”，因此在内齿21的齿向D1的至少一方的端部，由于齿向修整部210而能够使得因内齿21与外齿31的过度的齿接触引起的应力集中难以产生。特别是在谐波齿轮装置1中，由于波发生器4使挠性外齿轮3挠曲，因此有时会相对于旋转轴Ax1产生外齿31的扭转及偏斜(倾斜)等变形。因此，虽然在内齿21的齿向D1的至少一方的端部容易产生因外齿31的变形而引起的应力集中，但是，通过齿向修整部210能够使这样的应力集中难以产生。由此，难以产生由内齿21与外齿31的接触导致的缺欠或磨损等引起的异物X1，能够提供可靠性高的谐波齿轮装置1。而且，由于将齿向修整部210设置于刚性内齿轮2，因此对于挠性外齿轮3，不需要齿向修整或能够减小修整量，容易抑制对具有挠性的挠性外齿轮3实施齿向修整而引起的挠性外齿轮3的强度下降。
另外，在本实施方式的谐波齿轮装置1中，内齿21的表面硬度比外齿31的表面硬度低。外齿31相对于内齿21向齿向D1的至少一方突出。
根据该形态，相对于内齿21，表面硬度相对高的外齿31在齿向D1的至少一方突出，因此在齿向D1的至少一方，在内齿21的齿面难以产生因 磨损导致的高低差。即，在齿向D1的至少一方，表面硬度相对低的内齿21由于外齿31的齿接触而均匀地磨损，因此在内齿21的齿面难以产生局部性的凹陷(高低差)。因此，即使因某些跳动而存在齿接触位置沿齿向D1偏离的情况，也容易抑制因在内齿21与外齿31之间的啮合部位作用有过大的负载而引起的谐波齿轮装置1的异常的发生。即，难以产生外齿31中的齿向D1的一端部那样的角部分的缺欠，结果是，难以产生硬质的(硬度比较高的)异物X1。由此，难以产生由内齿21与外齿31的接触导致的缺欠或磨损等引起的异物X1，能够提供可靠性高的谐波齿轮装置1。
总之，根据本实施方式的谐波齿轮装置1，由于难以产生异物X1，因此能够获得可靠性高的效果。并且，本实施方式的谐波齿轮装置1特别是即使在长期使用时可靠性也难以下降，进而，实现谐波齿轮装置1的长寿命化及高性能化。
另外，如图4所示，本实施方式的谐波齿轮装置1与驱动源101及输出部102一起构成执行器100。换言之，本实施方式的执行器100包括谐波齿轮装置1、驱动源101和输出部102。驱动源101使波发生器4旋转。输出部102将刚性内齿轮2及挠性外齿轮3的任一方的旋转力取出作为输出。
根据本实施方式的执行器100，具有谐波齿轮装置1的可靠性难以下降的优点。
(2)定义
本公开实施例中所说的“环状”是指至少在俯视观察下在内侧形成包围的空间(区域)的环(圈)那样的形状，并不局限于在俯视观察下正圆和某圆形状(圆环状)，例如也可以为椭圆形状及多边形形状等。进一步，例如，也可以是如杯状的挠性外齿轮3那样具有底部322那样的形状，若其躯体部321为环状，则称为“环状”的挠性外齿轮3。
本公开实施例中所说的“齿向修整”是指齿向D1的修整，内齿21的齿向修整部210是内齿21中的实施了齿向修整的部位。通过齿向修整，能够 使齿轮的正规的齿向形状带有有意识的鼓起或是改变扭转角。作为齿向修整的代表性加工，存在鼓形修整和修缘加工(齿端修缘)。鼓形修整是以齿轮的齿向D1的中央部成为凸起的方式朝向齿向D1的中央部具有圆角的加工。修缘加工是使齿向D1的两端部适度地避让的加工方法。鼓形修整是朝向中央部具有圆角那样的遍及齿向D1的大致全长的加工，相对于此，修缘加工是仅使齿向D1的两端部避让的加工。无论是鼓形修整还是修缘加工，都通过使齿向D1的两端部的齿厚比中央部小而能够使与对方齿轮的齿接触位置靠近齿向D1的中心附近。通过这样的齿向修整，能抑制由于齿轮的制作误差或组装误差而齿接触偏向齿向D1的一端部的“一端接触”，特别是齿向D1的端部(齿宽端部)的应力集中得以缓和，齿接触得以改善。
本公开实施例中所说的“异物”是指谐波齿轮装置1的本来的构成要素以外的物质，作为其一例，存在由于内齿21与外齿31的接触引起的缺欠或磨损等而产生的金属粉或氮化物等。而且，通过后述的润滑剂Lb1(参照图8B)等而被阻碍进入的异物X1并不局限于在谐波齿轮装置1的内部产生的物质，例如，包含从谐波齿轮装置1的外部进入的废物、沙尘或尘埃等。在此所说的“阻碍”是指干扰或阻碍，并不局限于完全阻断，包括异物X1难以进入的全部情况。
本公开实施例中所说的“难以产生异物X1”是指异物X1的产生量、产生率及产生频度的至少一个(以下称为“产生量等”)减少。在此，产生量等是特别关于成为谐波齿轮装置1的可靠性下降的原因的硬度及尺寸的异物X1的值，异物X1难以产生包括例如硬质的(硬度比较高的)异物X1的产生量等减少的情况。当然，异物X1完全不产生的情况也包含在异物X1难以产生的情况中。即，在本实施方式中，通过采用在内齿21的齿向D1的至少一方的端部设置齿向修整部210的结构，与未采用该结构的情况相比，异物X1的产生量等减少。同样，在本实施方式中，通过采用表面硬度相对高的外齿31相对于内齿21向齿向D1的至少一方突出的结构，与未采 用该结构的情况相比，异物X1的产生量等减少。
本公开实施例中所说的“刚性”是指对物体施加外力而物体要变形时，物体抵抗该变形的性质。换言之，具有刚性的物体即使施加外力也难以变形。而且，本公开实施例中所说的“挠性”是指在向物体施加了外力时物体发生弹性变形(挠曲)的性质。换言之，具有挠性的物体在施加了外力时容易弹性变形。因此，“刚性”与“挠性”是相反的意思。
特别是在本公开实施例中，刚性内齿轮2的“刚性”与挠性外齿轮3的“挠性”按相对性的意思使用。即，刚性内齿轮2的“刚性”是指至少与挠性外齿轮3相比，刚性内齿轮2具有相对高的刚性，也就是说刚性内齿轮2即使被施加外力也难以变形。同样，挠性外齿轮3的“挠性”是指至少与刚性内齿轮2相比，挠性外齿轮3具有相对高的挠性，也就是说挠性外齿轮3在被施加外力时容易弹性变形。
另外，在本公开实施例中，有时将旋转轴Ax1的一方侧(图1A的右侧)称为“输入侧”，将旋转轴Ax1的另一方侧(图1A的左侧)称为“输出侧”。即，在图1A的例子中，挠性外齿轮3在旋转轴Ax1的“输入侧”具有开口面35。但是，“输入侧”及“输出侧”只不过是为了说明而附加的标签，其主旨并不是限定从谐波齿轮装置1观察到的输入及输出的位置关系。
本公开实施例中所说的“非圆形形状”是指非正圆的形状，例如，包括椭圆形状及长圆形状等。在本实施方式中，作为一例，波发生器4的非圆形形状的凸轮41为椭圆形状。即，在本实施方式中，波发生器4使挠性外齿轮3挠曲成椭圆形状。
本公开实施例中所说的“椭圆形状”是指将正圆被压扁而相互正交的长轴与短轴的交点位于中心那样的所有形状，并不局限于由与一个平面上的某两个定点的距离之和为恒定的点的集合构成的曲线即数学上的“椭圆”。即，本实施方式中的凸轮41可以为数学上的“椭圆”那样由与一个平面上的某两个定点的距离之和为恒定的点的集合构成的曲线状，也可以不是数学 上的“椭圆”而是像长圆那样的椭圆形状。如上所述，本公开实施例中所参照的附图均为示意图，图中的各结构要素的大小和厚度各自的比不一定限于反映实际的尺寸比。因此，虽然例如在图2中，将波发生器4的凸轮41的形状作为稍稍夸大的椭圆形状，但其主旨并不是限定实际的凸轮41的形状。
本公开实施例中所说的“旋转轴”是指成为旋转体的旋转运动的中心的假想的轴(直线)。即，旋转轴Ax1是不伴有实体的假想轴。波发生器4以旋转轴Ax1为中心进行旋转运动。
本公开实施例中所说的“内齿”及“外齿”分别指多个“齿”的集合(组)而不是单体的“齿”。也就是说，刚性内齿轮2的内齿21包括形成于刚性内齿轮2的内周面的多个齿的集合。同样，挠性外齿轮3的外齿31包括形成于挠性外齿轮3的外周面的多个齿的集合。
本公开实施例中所说的“平行”除了如果为一平面上的二直线则无论延长至何处都不相交的情况、即二者间的角度严格为0度(或180度)的情况之外，也指二者间的角度处于相对于0度而收敛于几度(例如小于10度)程度的误差范围的关系。同样，本公开实施例中所说的“正交”除了二者间的角度严格以90度相交的情况之外，也指二者间的角度处于相对于90度而收敛于几度(例如小于10度)程度的误差范围的关系。
(3)结构
以下，参照图1A～图6C，说明本实施方式的谐波齿轮装置1及执行器100的详细结构。
图1A是示出谐波齿轮装置1的概略结构的剖视图，图1B是图1A的区域Z1的放大图。图2是从旋转轴Ax1的输入侧(图1A的右侧)观察到的谐波齿轮装置1的概略图。图3A是从旋转轴Ax1的输出侧(图1A的左侧)观察到的谐波齿轮装置1的概略分解立体图。图3B是从旋转轴Ax1的输入侧观察到的谐波齿轮装置1的概略分解立体图。图4是示出包含谐 波齿轮装置1的执行器100的概略结构的剖视图。
(3.1)谐波齿轮装置
如上所述，本实施方式的谐波齿轮装置1包括刚性内齿轮2、挠性外齿轮3和波发生器4。在本实施方式中，作为谐波齿轮装置1的结构要素的刚性内齿轮2、挠性外齿轮3及波发生器4的材质为不锈钢、铸铁、机械结构用碳素钢、铬钼钢、磷青铜或铝青铜等金属。此处所说的金属包含实施了渗氮等表面处理的金属。
另外，在本实施方式中，作为谐波齿轮装置1的一例，例示杯型的谐波齿轮装置。即，在本实施方式的谐波齿轮装置1中，使用形成为杯状的挠性外齿轮3。波发生器4以收容于杯状的挠性外齿轮3内的方式与挠性外齿轮3组合。
另外，在本实施方式中，作为一例，谐波齿轮装置1在刚性内齿轮2固定于输入侧壳体111(参照图4)及输出侧壳体112(参照图4)等的状态使用。由此，伴随着刚性内齿轮2与挠性外齿轮3的相对旋转，挠性外齿轮3相对于固定构件(输入侧壳体111等)相对旋转。
此外，在本实施方式中，在将谐波齿轮装置1使用于执行器100的情况下，通过向波发生器4施加作为输入的旋转力，从而从挠性外齿轮3取出作为输出的旋转力。即，谐波齿轮装置1以波发生器4的旋转为输入旋转，以挠性外齿轮3的旋转为输出旋转而动作。由此，在谐波齿轮装置1中，能够得到相对于输入旋转以比较高的减速比进行了减速的输出旋转。
此外，在本实施方式的谐波齿轮装置1中，输入侧的旋转轴Ax1与输出侧的旋转轴Ax2处于同一直线上。换言之，输入侧的旋转轴Ax1与输出侧的旋转轴Ax2为同轴。在此，输入侧的旋转轴Ax1是施加有输入旋转的、波发生器4的旋转中心，输出侧的旋转轴Ax1是产生输出旋转的挠性外齿轮3的旋转中心。也就是说，在谐波齿轮装置1中，在同轴上，能够得到相对于输入旋转以较高的减速比进行了减速的输出旋转。
刚性内齿轮2也称为刚轮(circular spline)，是具有内齿21的环状的部件。在本实施方式中，刚性内齿轮2具有至少内周面在俯视时为正圆的圆环状。在圆环状的刚性内齿轮2的内周面，沿着刚性内齿轮2的圆周方向形成有内齿21。构成内齿21的多个齿为全部相同的形状，且以等间隔设置在刚性内齿轮2的内周面的圆周方向的整个区域。也就是说，内齿21的节圆在俯视时为正圆。另外，刚性内齿轮2在旋转轴Ax1的方向上具有规定的厚度。内齿21均形成于刚性内齿轮2的厚度方向的整个长度上。内齿21的齿线均与旋转轴Ax1平行。
如上所述，刚性内齿轮2固定于输入侧壳体111(参照图4)及输出侧壳体112(参照图4)等。因此，在刚性内齿轮2形成有固定用的多个固定孔22(参照图3A及图3B)。
挠性外齿轮3也称为柔轮(flex spline)，是具有外齿31的环状的部件。在本实施方式中，挠性外齿轮3是使用比较薄壁的金属弹性体(金属板)形成为杯状的部件。也就是说，挠性外齿轮3由于其厚度比较小(薄)而拥有挠性。挠性外齿轮3具有杯状的主体部32。主体部32具有躯体部321和底部322。在挠性外齿轮3未产生弹性变形的状态下，躯体部321的至少内周面301具有在俯视时为正圆的圆筒状。躯体部321的中心轴与旋转轴Ax1一致。底部322配置于躯体部321的一方的开口面，并具有在俯视时为正圆的圆盘状。底部322配置于躯体部321的一对开口面中的、靠旋转轴Ax1的输出侧的开口面。根据上述内容，主体部32通过躯体部321和底部322的整体实现向旋转轴Ax1的输入侧开放的、有底的圆筒状即杯状的形状。换言之，在挠性外齿轮3的旋转轴Ax1的方向上的与底部322相反侧的端面形成有开口面35。即，挠性外齿轮3是在齿向D1的一侧(在此为旋转轴Ax1的输入侧)具有开口面35的筒状。在本实施方式中，躯体部321和底部322由一个金属构件一体形成，由此能够实现无缝的主体部32。
在此，将非圆形形状(椭圆形状)的波发生器4嵌入于躯体部321的 内侧而将波发生器4组合于挠性外齿轮3。由此，挠性外齿轮3从内侧朝向外侧地从波发生器4承受径向方向(与旋转轴Ax1正交的方向)的外力，由此弹性变形成非圆形形状。在本实施方式中，波发生器4与挠性外齿轮3组合，由此挠性外齿轮3的躯体部321弹性变形成椭圆形状。即，挠性外齿轮3未发生弹性变形的状态是指未对挠性外齿轮3组合波发生器4的状态。相反，挠性外齿轮3发生弹性变形的状态是指已对挠性外齿轮3组合波发生器4的状态。
更详细而言，波发生器4嵌入于躯体部321的内周面301中的与底部322相反侧(旋转轴Ax1的输入侧)的端部。换言之，波发生器4嵌入于挠性外齿轮3的躯体部321中的、旋转轴Ax1的方向上的开口面35侧的端部。因此，在挠性外齿轮3发生弹性变形的状态下，挠性外齿轮3在旋转轴Ax1的方向上的开口面35侧的端部处比底部322侧的端部更大地变形，成为更接近于椭圆形状的形状。由于这样的旋转轴Ax1方向上的变形量的差异，在挠性外齿轮3发生弹性变形的状态下，挠性外齿轮3的躯体部321的内周面301包含相对于旋转轴Ax1倾斜的锥形面302(参照图8A)。
另外，在躯体部321的外周面中的至少与底部322相反的一侧(旋转轴Ax1的输入侧)的端部沿躯体部321的圆周方向形成有外齿31。换言之，外齿31设置在挠性外齿轮3的躯体部321中的至少旋转轴Ax1的方向上的开口面35侧的端部。构成外齿31的多个齿全部为同一形状，且以等间隔设置在挠性外齿轮3的外周面的圆周方向的整个区域。即，在挠性外齿轮3未发生弹性变形的状态下，外齿31的节圆在俯视观察下为正圆。外齿31仅在躯体部321的距开口面35侧(旋转轴Ax1的输入侧)的端缘为一定宽度的范围形成。具体而言，在躯体部321中的、在旋转轴Ax1的方向上至少供波发生器4嵌入的部分(开口面35侧的端部)，在外周面形成有外齿31。外齿31的齿向均与旋转轴Ax1平行。
总之，在本实施方式的谐波齿轮装置1中，刚性内齿轮2的内齿21及 挠性外齿轮3的外齿31的齿向均与旋转轴Ax1平行。由此，在本实施方式中，“齿向D1”是与旋转轴Ax1平行的方向。并且，内齿21的齿向D1的尺寸为内齿21的齿宽，同样，外齿31的齿向D1的尺寸为外齿31的齿宽，因此齿向D1与齿宽方向同义。
在本实施方式中，如上所述，挠性外齿轮3的旋转作为输出旋转被取出。因此，在挠性外齿轮3安装有执行器100的输出部102(参照图4)。在挠性外齿轮3的底部322形成有用于安装作为输出部102的轴的、多个安装孔33。进一步，在底部322的中央部形成有穿透孔34。底部322中的穿透孔34的周围比底部322的其他部位壁厚。
这样构成的挠性外齿轮3配置于刚性内齿轮2的内侧。此处，挠性外齿轮3以仅躯体部321的外周面中的与底部322相反的一侧(旋转轴Ax1的输入侧)的端部插入于刚性内齿轮2的内侧的方式与刚性内齿轮2组合。即，挠性外齿轮3将躯体部321中的、在旋转轴Ax1的方向上供波发生器4嵌入的部分(开口面35侧的端部)插入于刚性内齿轮2的内侧。此处，在挠性外齿轮3的外周面形成外齿31，在刚性内齿轮2的内周面形成内齿21。因此，在刚性内齿轮2的内侧配置有挠性外齿轮3的状态下，外齿31与内齿21相互相对。
此处，刚性内齿轮2中的内齿21的齿数比挠性外齿轮3的外齿31的齿数多2N(N为正整数)。作为本实施方式的一例，N为“1”，挠性外齿轮3的(外齿31的)齿数比刚性内齿轮2的(内齿21的)齿数多“2”。这种挠性外齿轮3与刚性内齿轮2的齿数差对在谐波齿轮装置1中的、输出旋转相对于输入旋转的减速比进行规定。
在此，在本实施方式中，作为一例，如图1A及图1B所示，以外齿31的齿向D1的中心与内齿21的齿向D1的中心相对的方式设定挠性外齿轮3与刚性内齿轮2在旋转轴Ax1的方向上的相对位置。即，对于挠性外齿轮3的外齿31和刚性内齿轮2的内齿21，其齿向D1的中心的位置对合于旋 转轴Ax1的方向的同一位置。而且，在本实施方式中，外齿31的齿向D1的尺寸(齿宽)比内齿21的齿向D1的尺寸(齿宽)大。因此，在与旋转轴Ax1平行的方向上，内齿21收在外齿31的齿向的范围内。换言之，外齿31相对于内齿21向齿向D1的至少一侧突出。详情在“(4.3)齿宽”一栏中说明，在本实施方式中，外齿31相对于内齿21向齿向D1的两侧(旋转轴Ax1的输入侧及输出侧)突出。
在此，在挠性外齿轮3未发生弹性变形的状态(未对挠性外齿轮3组合波发生器4的状态)下，描绘正圆的外齿31的节圆设定为比同样描绘正圆的内齿21的节圆小一圈。即，在挠性外齿轮3未发生弹性变形的状态下，外齿31与内齿21隔着间隙相对而相互未啮合。
另一方面，在挠性外齿轮3发生了弹性变形的状态(对挠性外齿轮3组合了波发生器4的状态)下，躯体部321挠曲成椭圆形状(非圆形形状)，因此挠性外齿轮3的外齿31与刚性内齿轮2的内齿21局部性地啮合。即，挠性外齿轮3的躯体部321(的至少开口面35侧的端部)弹性变形为椭圆形状，由此如图2所示，位于椭圆形状的长轴方向的两端的外齿31与内齿21啮合。换言之，描绘椭圆的外齿31的节圆的长径与描绘正圆的内齿21的节圆的直径一致，描绘椭圆的外齿31的节圆的短径比描绘正圆的内齿21的节圆的直径小。这样，当挠性外齿轮3发生弹性变形时，构成外齿31的多个齿中的一部分齿与构成内齿21的多个齿中的一部分齿啮合。结果是，在谐波齿轮装置1中，能够使外齿31的一部分与内齿21的一部分啮合。
波发生器4也称为波形产生器(wave generator)，是使挠性外齿轮3产生挠曲从而使挠性外齿轮3的外齿31产生谐波运动的部件。在本实施方式中，波发生器4是在俯视观察下外周形状成为非圆形形状、具体而言椭圆形状的部件。
波发生器4具有非圆形形状(此处为椭圆形状)的凸轮41和在凸轮41的外周装配的轴承42。即，向轴承42的内圈422的内侧嵌入非圆形形状(椭 圆形状)的凸轮41而将凸轮41组合于轴承42。由此，轴承42从内圈422的内侧朝向外侧地、从凸轮41承受径向方向(与旋转轴Ax1正交的方向)的外力而弹性变形为非圆形形状。即，轴承42未发生弹性变形的状态是指未对轴承42组合凸轮41的状态。相反，轴承42发生弹性变形的状态是指对轴承42组合了凸轮41的状态。
凸轮41是以输入侧的旋转轴Ax1为中心被驱动旋转的、非圆形形状(在此为椭圆形状)的部件。凸轮41具有外周面411(参照图1B)，至少外周面411由在俯视观察下为椭圆形状的金属板构成。凸轮41在旋转轴Ax1的方向上(即齿向D1)具有规定的厚度。由此，凸轮41具有与刚性内齿轮2同等程度的刚性。但是，凸轮41的厚度比刚性内齿轮2的厚度小(薄)。在本实施方式中，如上所述，以波发生器4的旋转为输入旋转。因此，在波发生器4安装有执行器100的输入部103(参照图4)。在波发生器4的凸轮41的中央部形成有用于安装作为输入部103的轴的凸轮孔43。
轴承42具有外圈421、内圈422和多个滚动体423。在本实施方式中，作为一例，轴承42包括使用滚珠作为滚动体423的深沟球轴承。
外圈421及内圈422均为环状的部件。外圈421和内圈422均是使用壁较薄的金属弹性体(金属板)形成为环状的部件。也就是说，外圈421和内圈422由于其厚度比较小(薄)而均拥有挠性。在本实施方式中，外圈421和内圈422在轴承42未产生弹性变形的状态(为对凸轮41组合轴承42的状态)下，均具有俯视时为正圆的圆环状。内圈422比外圈421小一圈并配置于外圈421的内侧。此处，外圈421的内径由于比内圈422的外径大，所以在外圈421的内周面与内圈422的外周面之间产生间隙。
多个滚动体423配置于外圈421与内圈422之间的间隙。多个滚动体423沿外圈421的圆周方向排列配置。多个滚动体423为全部相同形状的金属球(滚珠)，且以等间隔设置在外圈421的圆周方向的整个区域。此处虽然未特别图示，但是轴承42还具有保持器，多个滚动体423通过保持器 被保持于外圈421与内圈422之间。
另外，在本实施方式中，作为一例，外圈421及内圈422的宽度方向(与旋转轴Ax1平行的方向)的尺寸与凸轮41的厚度相同。即，外圈421及内圈422的宽度方向的尺寸比刚性内齿轮2的厚度小。
通过这样的轴承42的结构，凸轮41与轴承42组合，由此轴承42的内圈422固定于凸轮41，内圈422弹性变形为与凸轮41的外周形状相似的椭圆形状。此时，轴承42的外圈421经由多个滚动体423被内圈422按压而弹性变形为椭圆形状。由此，轴承42的外圈421和内圈422均弹性变形为椭圆形状。这样，在轴承42产生弹性变形的状态(对凸轮41组合了轴承42的状态)下，外圈421和内圈422成为彼此相似的椭圆形状。
即使是在轴承42产生弹性变形的状态下，由于多个滚动体423介于外圈421与内圈422之间，所以外圈421与内圈422之间的间隙在外圈421的整周被维持为大致恒定。并且，在该状态下，通过外圈421与内圈422之间的多个滚动体423滚动，从而外圈421能够相对于内圈422进行相对旋转。由此，在轴承42产生弹性变形的状态下，当凸轮41以旋转轴Ax1为中心旋转时，凸轮41的旋转不传动至外圈421，而内圈422的弹性变形经由多个滚动体423传动至外圈421。也就是说，在波发生器4中，当凸轮41以旋转轴Ax1为中心旋转时，外圈421以使得外圈421所仿效出的椭圆形状的长轴以旋转轴Ax1为中心进行旋转弹性变形。因此，对于波发生器4整体而言，从旋转轴Ax1的输入侧观察到的成为椭圆形状的波发生器4的外周形状以其长轴以旋转轴Ax1为中心进行旋转的方式伴随着凸轮41的旋转而变化。
这样构成的波发生器4配置在挠性外齿轮3的内侧。此处，挠性外齿轮3与波发生器4组合为仅躯体部321的内周面301中的与底部322相反的一侧(开口面35侧)的端部嵌合于波发生器4。此时，波发生器4的轴承42配置于凸轮41的外周面411与挠性外齿轮3的内周面301之间。此 处，在轴承42未产生弹性变形的状态(凸轮41未与轴承42组合的状态)下的外圈421的外径与同样未产生弹性变形状态下的挠性外齿轮3(躯体部321)的内径相同。因此，波发生器4的外圈421的外周面在轴承42的圆周方向上的整周上与挠性外齿轮3的内周面301相接。由此，在挠性外齿轮3产生了弹性变形的状态(波发生器4与挠性外齿轮3组合的状态)下，躯体部321挠曲为椭圆形状(非圆形形状)。在该状态下，挠性外齿轮3相对于轴承42的外圈421被固定。
在上述的结构的谐波齿轮装置1中，如图2所示，通过挠性外齿轮3的躯体部321挠曲为椭圆形状(非圆形状)，从而挠性外齿轮3的外齿31与刚性内齿轮2的内齿21局部性地啮合。也就是说，通过挠性外齿轮3(的躯体部321)弹性变形为椭圆形状，从而与该椭圆形状的长轴方向的两端相应的两个部位的外齿31啮合于内齿21。并且，当凸轮41以旋转轴Ax1为中心旋转时，凸轮41的旋转不传动至外圈421和挠性外齿轮3，而内圈422的弹性变形经由多个滚动体423传动至外圈421和挠性外齿轮3。因此，从旋转轴Ax1的输入侧观察到的、成为椭圆形的挠性外齿轮3的外周形状以其长轴以旋转轴Ax1为中心进行旋转的方式伴随着凸轮41的旋转而变化。
其结果是，在形成于挠性外齿轮3的外周面的外齿31发生波动运动。由于发生外齿31的波动运动，所以内齿21与外齿31的啮合位置沿刚性内齿轮2的圆周方向移动，从而使挠性外齿轮3在与刚性内齿轮2之间发生相对旋转。也就是说，外齿31由于在挠性外齿轮3(的躯体部321)所形成的椭圆形状的长轴方向的两端处与内齿21啮合，所以通过该椭圆形状的长轴以旋转轴Ax1为中心进行旋转，从而使内齿21与外齿31的啮合位置移动。如此，对于本实施方式所涉及的谐波齿轮装置1而言，伴随着以旋转轴Ax1为中心的波发生器4的旋转而使挠性外齿轮3变形，使外齿31的一部分与内齿21的一部分啮合，从而使挠性外齿轮3按照与刚性内齿轮2的齿数差而进行旋转。
然而，在谐波齿轮装置1中，如上所述，挠性外齿轮3与刚性内齿轮2的齿数差规定了谐波齿轮装置1中的输出旋转相对于输入旋转的减速比。即，在将刚性内齿轮2的齿数设为“V1”，将挠性外齿轮3的齿数设为“V2”的情况下，减速比R1由下述式1表示。
R1＝V2/(V1-V2)…(式1)
总之，刚性内齿轮2与挠性外齿轮3的齿数差(V1-V2)越小，则减速比R1越大。作为一例，如果刚性内齿轮2的齿数V1为“72”，挠性外齿轮3的齿数V2为“70”，其齿数差(V1-V2)为“2”，则根据上述式1，减速比R1成为“35”。在该情况下，从旋转轴Ax1的输入侧观察时，当凸轮41以旋转轴Ax1为中心顺时针地旋转一周(360度)时，挠性外齿轮3以旋转轴Ax1为中心逆时针地旋转齿数差“2”的量(即10.3度)。
根据本实施方式的谐波齿轮装置1，如此高的减速比R1通过一级的齿轮(刚性内齿轮2及挠性外齿轮3)的组合就能够实现。
另外，谐波齿轮装置1只要至少包括刚性内齿轮2、挠性外齿轮3和波发生器4即可，例如，可以还包括“(3.2)执行器”一栏说明的花键衬套113等作为构成要素。
(3.2)执行器
接下来，更详细地说明本实施方式的执行器100的结构。
如图4所示，本实施方式的执行器100包括本实施方式的谐波齿轮装置1、驱动源101和输出部102。即，执行器100除了构成谐波齿轮装置1的刚性内齿轮2、挠性外齿轮3及波发生器4之外，还包括驱动源101及输出部102。而且，执行器100除了谐波齿轮装置1、驱动源101及输出部102之外，还包括输入部103、输入侧壳体111、输出侧壳体112、花键衬套113、间隔件114、第一止挡件115、第二止挡件116及安装板117。而且，在本实施方式中，执行器100还包括输入侧轴承118、119、输入侧油封120、 输出侧轴承121、122及输出侧油封123。
在本实施方式中，执行器100中的除驱动源101、输入侧油封120及输出侧油封123以外的部件的材质为不锈钢、铸铁、机械结构碳素钢、铬钼钢、磷青铜或铝青铜等金属。
驱动源101是马达(电动机)等的动力的产生源。通过驱动源101产生的动力传递至谐波齿轮装置1中的波发生器4的凸轮41。具体而言，驱动源101与作为输入部103的轴相连，通过驱动源101产生的动力经由输入部103传递至凸轮41。由此，驱动源101能够使凸轮41旋转。
输出部102是沿着输出侧的旋转轴Ax2配置的圆柱状的轴。作为输出部102的轴的中心轴与旋转轴Ax2一致。输出部102通过输出侧壳体112保持为能够以旋转轴Ax2为中心旋转。输出部102固定于挠性外齿轮3中的主体部32的底部322，并以旋转轴Ax2为中心与挠性外齿轮3一起旋转。也就是说，输出部102将挠性外齿轮3的旋转力作为输出而取出。
输入部103是沿着输入侧的旋转轴Ax1配置的圆柱状的轴。作为输入部103的轴的中心轴与旋转轴Ax1一致。输入部103通过输入侧壳体111保持为能够以旋转轴Ax1为中心旋转。输入部103安装于波发生器4的凸轮41，并以旋转轴Ax1为中心与凸轮41一起旋转。也就是说，输入部103将驱动源101所产生的动力(旋转力)作为输入传递至凸轮41。如上所述，在本实施方式中，输入侧的旋转轴Ax1与输出侧的旋转轴Ax2位于同一直线上，因此输入部103与输出部102位于同轴上。
输入侧壳体111经由输入侧轴承118、119将输入部103保持为输入部103能够旋转。一对输入侧轴承118、119沿着旋转轴Ax1空出间隔而排列配置。在本实施方式中，作为输入部103的轴贯穿通过输入侧壳体111，且输入部103的前端部从输入侧壳体111中的旋转轴Ax1的输入侧的端面(图4的右端面)突出。输入侧壳体111的旋转轴Ax1的输入侧的端面中的、与输入部103之间的间隙由输入侧油封120堵塞。
输出侧壳体112经由输出侧轴承121、122将输出部102保持为输出部102能够旋转。一对输出侧轴承121、122沿着旋转轴Ax2空出间隔而排列配置。在本实施方式中，作为输出部102的轴贯穿通过输出侧壳体112，且输出部102的前端部从输出侧壳体112中的旋转轴Ax1的输出侧的端面(图4的左端面)突出。输出侧壳体112的旋转轴Ax1的输出侧的端面中的、与输出部102之间的间隙由输出侧油封123堵塞。
在此，如图4所示，输入侧壳体111和输出侧壳体112在从与旋转轴Ax1平行的方向、即齿向D1的两侧夹持谐波齿轮装置1的刚性内齿轮2的状态下彼此结合。具体而言，输入侧壳体111从旋转轴Ax1的输入侧与刚性内齿轮2接触，输出侧壳体112从旋转轴Ax1的输出侧与刚性内齿轮2接触。如此，在将刚性内齿轮2夹持于输入侧壳体111与输出侧壳体112之间的状态下，穿过多个固定孔22利用螺钉(螺栓)使输入侧壳体111与输出侧壳体112紧固固定。由此，输入侧壳体111、输出侧壳体112和刚性内齿轮2彼此结合而成为一体。换言之，刚性内齿轮2与输入侧壳体111和输出侧壳体112一起构成执行器100的外轮廓。
花键衬套113是用于将作为输入部103的轴与凸轮41连结的筒状的部件。花键衬套113插入于形成在凸轮41的凸轮孔43，作为输入部103的轴以贯穿通过花键衬套113的方式插入于花键衬套113。此处，在以旋转轴Ax1为中心的旋转方向上，花键衬套113相对于凸轮41和输入部103这两者的移动被限制，在与旋转轴Ax1平行的方向上，花键衬套113至少能够相对于输入部103移动。由此，能够实现将花键连结结构作为输入部103与凸轮41的连结结构。由此，凸轮41能够相对于输入部103沿着旋转轴Ax1移动，并以旋转轴Ax1为中心与输入部103一起旋转。
间隔件114是填补花键衬套113与凸轮41之间的间隙的部件。第一止挡件115是防止花键衬套113从凸轮41脱落的部件。第一止挡件115例如由E型圈构成，安装于花键衬套113中的就凸轮41而言旋转轴Ax1的输入 侧的位置。第二止挡件116是防止输入部103从花键衬套113脱落的部件。第二止挡件116例如由E型圈构成，以从旋转轴Ax1的输出侧与花键衬套113接触的方式安装于输入部103。
安装板117是用于将作为输出部102的轴安装于挠性外齿轮3的底部322的部件。具体而言，在将底部322中的穿透孔34的周围的部分夹持于安装板117与输出部102的凸缘部之间的状态下，穿过多个安装孔33利用螺钉(螺栓)使安装板117与凸缘部紧固固定。由此，在挠性外齿轮3的底部322固定有作为输出部102的轴。
(4)内齿及外齿的结构
接下来，参照图5A～图8B，更详细地说明本实施方式的谐波齿轮装置1的内齿21及外齿31的结构。
图5A是图1B的着眼于内齿21及外齿31观察到的剖视图，图5B是图5A的A1-A1线剖视图。图6是用于示出内齿21及外齿31的修整量Q1、Q2的概念性的说明图，示出从图5A所示的状态解除了内齿21与外齿31的啮合的状态。图7A是图5A的B1-B1线剖视图，图7B是图5A的B2-B2线剖视图，图7C是图5A的B3-B3线剖视图。图8A是示出挠性外齿轮3的内周面301中的相对于旋转轴Ax1倾斜的锥形面302的剖视图，图8B是图8A的区域Z1的放大图。如上所述，本公开实施例参照的附图都是示意性的图，图中的各构成要素的大小及厚度各自的比未必反映实际的尺寸比。因此，例如，在图5A～图7C中，将齿向修整的修整量Q1、Q2表示得很大，其主旨并非限定实际的内齿21及外齿31的形状。此外，在图5A～图7C中，省略剖面的剖面线(斜线)。
(4.1)表面硬度
首先，说明本实施方式中的内齿21及外齿31的表面硬度。
在本实施方式中，如上所述，内齿21的表面硬度比外齿31的表面硬度低。即，外齿31的表面与内齿21的表面相比硬度高(硬)。本公开实 施例所说的“硬度”是指物体的坚硬的程度，金属的硬度例如由以一定的压力按压钢球而形成的压痕的大小来表示。具体而言，作为金属的硬度的一例，有洛氏硬度(HRC)、布氏硬度(HB)、维氏硬度(HV)或肖氏硬度(Hs)等。在本实施方式中，只要没有特别限定，则用维氏硬度(HV)来表示硬度。作为提高金属部件的硬度(变硬)的手段，例如有合金化或热处理等。
在本实施方式中，挠性外齿轮3的外齿31的表面由高硬度且高韧性(强韧)的材质构成，刚性内齿轮2的内齿21由硬度比外齿31低的材质构成。在本实施方式中，作为一例，外齿31使用对于由日本产业标准(JIS：Japanese Industrial Standards)规定为“SNCM439”的镍铬钼钢实施了热处理(淬火回火)而得的材料。内齿21使用由日本产业标准(JIS)规定为“FCD800-2”的球状石墨铸铁。
此外，与外齿31相比成为相对低硬度的内齿21的表面硬度优选为HV350以下。在本实施方式中，作为一例，内齿21的表面硬度在HV250以上且小于HV350的范围内选择。内齿21的表面硬度的下限值并不局限于HV250，例如，可以为HV150、HV160、HV170、HV180、HV190、HV200、HV210、HV220、HV230或HV240等。同样，内齿21的表面硬度的上限值并不局限于HV350，例如，可以为HV360、HV370、HV380、HV390、HV400、HV410、HV420、HV430、HV440或HV450等。
相对于此，与内齿21相比成为相对高硬度的外齿31的表面硬度优选为HV380以上。在本实施方式中，作为一例，外齿31的表面硬度在HV380以上且HV450以下的范围内选择。外齿31的表面硬度的下限值并不局限于HV380，例如，可以为HV280、HV290、HV300、HV310、HV320、HV330、HV340、HV350、HV360或HV370等。同样，内齿21的表面硬度的上限值并不局限于HV450，例如，可以为HV460、HV470、HV480、HV490、HV500、HV510、HV520、HV530、HV540或HV550等。
另外，在本实施方式中，内齿21的表面硬度与外齿31的表面硬度的 差为HV50以上。即，外齿31的表面硬度设定得比内齿21的表面硬度高HV50以上。总之，若例如内齿21的表面硬度为HV350，则外齿31的表面硬度为HV400以上。而且，如果外齿31的表面硬度为HV380，则内齿21的表面硬度为HV330以下。内齿21的表面硬度与外齿31的表面硬度的差并不局限于HV50以上，例如，可以为HV20以上、HV30以上或HV40以上。此外，内齿21的表面硬度与外齿31的表面硬度的差越大越优选，例如，更优选为HV60以上、HV70以上、HV80以上、HV90以上或HV100以上。如果内齿21的表面硬度与外齿31的表面硬度的差为HV100以上，则在内齿21的表面硬度为HV350时，外齿31的表面硬度为HV450以上。
如上所述，在本实施方式中，内齿21的表面硬度设定得比外齿31的表面硬度低。因此，在谐波齿轮装置1工作时，如果内齿21与外齿31接触，则表面硬度相对低的内齿21比外齿31积极地磨损。在表面硬度不同的两个部件(内齿21及外齿31)接触时，相对软质的内齿21的磨损进展，由此能抑制相对硬质的外齿31的磨损。即，在谐波齿轮装置1的使用初期的阶段，内齿21的齿面适度磨损，由此内齿21与外齿31之间的真实接触面积扩大，面压下降，因此外齿31的磨损难以产生。而且，如本实施方式那样内齿21的表面硬度为HV350以下时，即使由于内齿21与外齿31的接触，因内齿21的缺欠或磨损等而产生异物X1，该异物X1也比较软质。总之，使得谐波齿轮装置1的使用初期容易产生的因磨损导致的异物X1为从比较软质的内齿21产生的软质的异物X1，由此，即使例如异物X1进入轴承42也能够抑制对轴承42的损害。结果是，例如，能抑制对轴承42损害大的硬质的异物X1的产生量等。特别是如果内齿21的表面硬度与外齿31的表面硬度的差为HV50以上那样比较大的值，则上述效果显著。
此外，通过使用球状石墨铸铁作为内齿21的材料，则能够期待在内齿21的初期磨损时抑制内齿21与外齿31的齿面的烧结的效果。由此，能得到内齿21与外齿31的啮合部位的润滑效果，能够提高谐波齿轮装置1的 动力传递效率。
内齿21及外齿31的表面硬度并非必须由维氏硬度(HV)规定，也可以通过其他的硬度，例如洛氏硬度(HRC)、布氏硬度(HB)或肖氏硬度(Hs)来规定内齿21及外齿31的表面硬度。
(4.2)齿向修整
接下来，说明本实施方式的内齿21及外齿31的齿向修整。
作为前提，如图5A所示，内齿21具有齿底212及齿顶213。内齿21设置于刚性内齿轮2的内周面，因此内齿21的齿底212相当于刚性内齿轮2的内周面，齿顶213从刚性内齿轮2的内周面朝向内侧(刚性内齿轮2的中心)突出。
另一方面，如图5A所示，外齿31具有齿底312及齿顶313。外齿31设置于挠性外齿轮3(的躯体部321)的外周面，因此外齿31的齿底312相当于挠性外齿轮3(的躯体部321)的外周面，齿顶313从挠性外齿轮3(的躯体部321)的外周面朝向外侧突出。
在内齿21与外齿31的啮合位置处，向内齿21的相邻的一对齿顶213之间插入外齿31的齿顶313，从而内齿21与外齿31啮合。此时，外齿31的齿顶313与内齿21的齿底212相对，内齿21的齿顶213与外齿31的齿底312相对。并且，理想的情况是，在内齿21的齿底212与外齿31的齿顶313之间、外齿31的齿底312与内齿21的齿顶213之间确保微小的间隙。在该状态下，内齿21与外齿31的沿齿厚方向D2(参照图5B)相对的齿面彼此接触，进行刚性内齿轮2与挠性外齿轮3之间的动力传递。
此外，内齿21在齿向D1的两端部具有倒角部211。倒角部211是朝向齿向D1的两侧使内齿21的突出量减小的C面，是基本上对内齿21与外齿31的啮合不起作用的部位。即，内齿21的倒角部211即使在内齿21与外齿31的啮合位置处也不与外齿31相接。同样，外齿31在齿向D1的两端部具有倒角部311。倒角部311是朝向齿向D1的两侧使内齿21的突出 量减小的C面，是基本上对内齿21与外齿31的啮合不起作用的部位。即，外齿31的倒角部311即使在内齿21与外齿31的啮合位置处也不与内齿21相接。
在此，在本实施方式中，如图5A、图5B及图6所示，刚性内齿轮2的内齿21具有齿向修整部210。即，对于谐波齿轮装置1，至少在内齿21实施齿向修整。内齿21的齿向修整部210设置于齿向D1的至少一方的端部。换言之，内齿21在内齿21的齿向D1的至少一方的端部具有齿向修整部210。在本实施方式中，齿向修整部210设置于内齿21的齿向D1的两端部。
另外，在本实施方式中，挠性外齿轮3的外齿31也具有齿向修整部310。即，对于谐波齿轮装置1，不仅在内齿21而且在外齿31也实施齿向修整。外齿的齿向修整部310设置于齿向D1的至少一方的端部。换言之，外齿31在外齿31的齿向D1的至少一方的端部具有齿向修整部310。在本实施方式中，齿向修整部310设置于外齿31的齿向D1的两端部。
这样，在本实施方式的谐波齿轮装置1中，内齿21及外齿31的至少一方具有齿向修整部210、310。通过齿向修整部210、310，能够使内齿21与外齿31的过度齿接触引起的应力集中难以产生，结果是，能够改善内齿21与外齿31的齿接触情况。由此，由内齿21与外齿31的接触导致的缺欠或磨损等所引起的异物X1难以产生，能够实现可靠性高的谐波齿轮装置1。
在此，齿向修整部210至少设置于内齿21。齿向修整部210设置于刚性内齿轮2(内齿21)，由此对于挠性外齿轮3(外齿31)不需要齿向修整或能够减小修整量，容易抑制对具有挠性的挠性外齿轮3实施齿向修整引起的挠性外齿轮3的强度下降。即，挠性外齿轮3如上所述由比较薄壁的金属弹性体(金属板)形成，因其厚度比较小(薄)而具有挠性。因此，如果对挠性外齿轮3的外齿31实施过度的齿向修整，则原本就薄的挠性外齿轮3会变得更薄，从而可能导致挠性外齿轮3的强度下降。特别是如果 对外齿31的齿底312实施过度的齿向修整，则难以确保躯体部321维持强度而所需的厚度。相对于此，在本实施方式中，通过在内齿21设置齿向修整部210，由此对于挠性外齿轮3的齿向修整能够减小修整量，结果是，容易维持挠性外齿轮3的强度。
另外，在本实施方式中，不仅在内齿21而且也在外齿31、即在内齿21及外齿31双方设置齿向修整部210、310。因此，对于内齿21也不需要实施过度的齿向修整，以适度的修整量的齿向修整就能够实现所希望的性能。在本公开实施例中，在区分内齿21的齿向修整部210与外齿31的齿向修整部310的情况下，也将内齿21的齿向修整部210称为“第一修整部210”，将外齿31的齿向修整部310称为“第二修整部310”。即，在本实施方式中，内齿21具有作为齿向修整部210的第一修整部210。外齿31具有第二修整部310，该第二修整部310是与第一修整部210不同的齿向修整部310。
在对内齿21及外齿31双方实施齿向修整的情况下，如图6所示，可以将内齿21的修整量Q1与外齿31的修整量Q2的合计看作对内齿21及外齿31的齿向修整的修整量。因此，如果对内齿21及外齿31的齿向修整的修整量为相同量，则与仅对内齿21实施齿向修整的情况相比，能够将内齿21的修整量Q1抑制得减小外齿31的修整量Q2的量。在图6中，将正规的齿向形状通过想像线(双点划线)表示，将通过齿向修整实现的、相对于正规的齿向形状的最大位移量表示为修整量Q1、Q2。即，如图6所示，内齿21的修整量Q1是相对于齿顶213的齿向D1的中央部的(齿高方向的)位移量。同样，外齿31的修整量Q2是相对于齿顶313的齿向D1的中央部的(齿高方向的)位移量。在图6中，例示了齿顶213、313的修整量Q1、Q2，但是并不局限于齿顶213、313，关于齿底212、312或齿厚方向D2的一端面的修整量也同样。
然而，如上所述，齿向修整的代表性的加工包括鼓形修整和修缘加工 时，在本实施方式中，内齿21的齿向修整部(第一修整部)210通过鼓形修整形成。即，第一修整部210通过对内齿21以齿向D1的中央部成为凸起的方式实施朝向齿向D1的中央部使内齿21具有圆角的加工而形成。同样，外齿31的齿向修整部(第二修整部)310也通过鼓形修整而形成。即，第二修整部310通过对外齿31以齿向D1的中央部成为凸起的方式实施朝向齿向D1的中央部使外齿31具有圆角的加工而形成。这样，在本实施方式中，第一修整部210与第二修整部310包含同一种类的修整。即，第一修整部210和第二修整部310都是基于同一种类(在此为鼓形修整)的齿向修整。
另外，内齿21的齿向修整部(第一修整部)210使内齿21的齿底212、齿顶213、齿厚方向D2的一端面的至少一个包含相对于齿向D1倾斜的倾斜面。即，齿向修整部210是通过对内齿21的齿底212、齿顶213、齿厚方向D2的一端面的至少一个实施齿向修整用的加工(在此为鼓形修整)而形成的。如果是齿底212的齿向修整，则在齿底212形成以使得随着接近齿向D1的两端而齿底212降低的方式相对于齿向D1倾斜的倾斜面。如果是齿顶213的齿向修整，则在齿顶213形成以使得随着接近齿向D1的两端而齿顶213降低的方式相对于齿向D1倾斜的倾斜面。如果是齿厚方向D2的一端面的齿向修整，则在齿厚方向D2的一端面形成以使得随着接近齿向D1的两端而齿厚变小的方式相对于齿向D1倾斜的倾斜面。在本实施方式中，如图5A及图5B所示，对内齿21的齿底212、齿顶213、齿厚方向D2的两端面都实施齿向修整。
特别是齿向修整部210至少在齿底212包含倾斜面，由此容易避免外齿31的齿顶313与内齿21的齿底212的干涉。即，若对内齿21的齿底212实施齿向修整，则能够确保外齿31的齿顶313的“避让部”用的间隙，难以产生外齿31的齿顶313与内齿21的齿底212的干涉引起的过度的应力集中。
关于外齿31也同样，齿向修整部(第二修整部)310使外齿31的齿底312、齿顶313、齿厚方向D2的一端面的至少一个包含相对于齿向D1倾斜的倾斜面。即，齿向修整部310是通过对外齿31的齿底312、齿顶313、齿厚方向D2的一端面的至少一个实施齿向修整用的加工(在此为鼓形修整)而形成的。在本实施方式中，如图5A及图5B所示，对外齿31的齿底312、齿顶313、齿厚方向D2的两端面都实施齿向修整。
通过对齿厚方向D2的两端面实施的齿向修整，如图5B所示，内齿21及外齿31的各自的齿厚在齿向D1的中央部最大，并朝向齿向D1的两端而逐渐减小。因此，就内齿21与外齿31的啮合位置而言，在齿向D1上未实施齿向修整(在此为鼓形修整)的中央部，内齿21与外齿31的间隙最小。将在内齿21及外齿31的齿向D1上未实施齿向修整的部位、即仍为正规的齿向形状的部位也称为“非修整部”。由此，就内齿21与外齿31的啮合位置而言，基本上是内齿21与外齿31在处于齿向D1的中央部的“非修整部”最先接触。
总之，在图7A～图7C的例子中，在示出齿向D1的中央部的剖面的图7A中，内齿21与外齿31的间隙G1最小。即，朝向齿向D1的一端(旋转轴Ax1的输出侧)，内齿21与外齿31的间隙G1按照图7B、图7C的顺序变大。这样，通过齿向修整，越是远离齿向D1的中央部，则齿面越逐渐向负方向移位，因此内齿21与外齿31的间隙G1变大。
在本实施方式中，这样的非修整部(齿向D1的中央部)在齿向D1上配置于与轴承42的滚动体423重复的位置。严格来说，非修整部(齿向D1的中央部)位于与旋转轴Ax1正交且通过滚动体423的中心的直线(假想直线)上。由此，经由轴承42的外圈421从多个滚动体423向挠性外齿轮3传递的应力主要作用于非修整部，容易使内齿21与外齿31在非修整部最先接触。
另外，在本实施方式中，在内齿21的第一修整部210和外齿31的第 二修整部310中，修整量Q1、Q2存在差异。第二修整部310的修整量Q2比第一修整部210的修整量Q1小(Q1>Q2)。挠性外齿轮3具有与动力传递功能不同的发生弹性变形(挠曲)的功能，通过挠曲而产生的应力是固有的，因此挠性外齿轮3的外齿31要求有对弯曲应力的耐受性。并且，如果对外齿31实施齿向修整，则基本上外齿31的齿根变细，因此对于弯曲应力的耐受性下降，挠性外齿轮3的耐久性下降。另一方面，刚性内齿轮2不需要弹性变形，因此刚性内齿轮2的内齿21也不要求对弯曲应力的耐受性。因此，即使对内齿21实施齿向修整而内齿21的齿根变细，也几乎不会影响刚性内齿轮2的耐久性。由此，通过使外齿31的修整量Q2比内齿21的修整量Q1小，作为对于内齿21及外齿31的齿向修整，能够确保充分的修整量并抑制谐波齿轮装置1的耐久性的下降。
另外，齿向修整部210设置于内齿21的齿向D1的两端部。换言之，齿向修整部210设置于内齿21的旋转轴Ax1的输入侧及输出侧这两方的端部。即，齿向修整部210设置于内齿21中的齿向D1的至少开口面35侧的端部。在此，在挠性外齿轮3产生弹性变形的状态下，挠性外齿轮3在旋转轴Ax1的方向上的开口面35侧的端部处比底部322侧的端部更大地变形，成为更接近于椭圆形状的形状。由于这样的在旋转轴Ax1的方向上的变形量的差异，在挠性外齿轮3发生弹性变形的状态下，在挠性外齿轮3的躯体部321的内周面301产生相对于旋转轴Ax1倾斜的锥形面302(参照图8A)。并且，通过在齿向D1的开口面35侧设置齿向修整部210，能够进行内齿21的齿向修整以避让(避开)因这样的锥形面302而倾斜的外齿31。因此，即使在外齿31的变形所导致的应力集中特别容易产生的齿向D1的开口面35侧的端部，通过齿向修整部210，也能够使应力集中难以产生。
另外，内齿21的齿向修整部(第一修整部)210例如使用旋刮用刀具形成。即，对于在刚性内齿轮2的内周面形成的内齿21，通过使用了旋刮用刀具的齿向修整，能够形成齿向修整部210。旋刮用刀具具有在工件(刚 性内齿轮2)形成齿轮部(内齿21)的小齿轮状的多个切刃部。对旋刮用刀具以不同于工件轴芯的刀具轴芯为中心驱动使之旋转，一边与工件同步旋转，一边通过沿齿向D1相对移动而切削工件。由此，在工件(刚性内齿轮2)形成实施了齿向修整的齿轮部(内齿21)。
此外，在本实施方式中，在内齿21及外齿31，不仅实施上述的齿向修整，而且如图7A～图7C所示，也实施齿形修整。关于齿形修整，在发生弹性变形的状态的挠性外齿轮3配置于刚性内齿轮2的内侧的状态且未进行动力传递的状态下，以满足以下条件的方式确定修整量。即，条件是：在内齿21及外齿31的啮合位置的齿距点附近不产生间隙且在外齿31的齿顶313与内齿21的齿底212之间产生例如0.1模数程度以上的间隙。为了满足这样的条件，将内齿21及外齿31以齿高方向的中央部成为凸起的方式齿形修整为朝向齿高方向的中央部具有圆角的形状。由此，即使刚性内齿轮2的内齿21产生磨损，齿底接触也难以产生。
(4.3)齿宽
接下来，说明本实施方式的内齿21及外齿31的齿宽(齿向D1的尺寸)。
在本实施方式中，如图5A所示，挠性外齿轮3的外齿31相对于刚性内齿轮2的内齿21向齿向D1的至少一方突出。即，如上所述，在挠性外齿轮3的外齿31和刚性内齿轮2的内齿21中，齿向D1的中心的位置对合于旋转轴Ax1的方向的同一位置。并且，外齿31的齿向D1的尺寸(齿宽)比内齿21的齿向D1的尺寸(齿宽)大。因此，在齿向D1上，内齿21收于外齿31的齿向的范围内，外齿31相对于内齿21向齿向D1的至少一方突出。
特别是在本实施方式中，如图5A所示，外齿31相对于内齿21向齿向D1的两方(旋转轴Ax1的输入侧及输出侧)突出。朝向齿向D1的一方侧(旋转轴Ax1的输入侧)，外齿31从内齿21的端缘突出了突出量L1。朝向齿向D1的另一方侧(旋转轴Ax1的输出侧)，外齿31从内齿21的端 缘突出了突出量L2。在本实施方式中，作为一例，外齿31从内齿21突出的突出量L1、L2在齿向D1的两侧大致相同。
在此，突出量L1、L2通过内齿21中的除了倒角部211之外的部位与外齿31中的除了倒角部311之外的部位的比较来表示。即，在齿向D1的一方侧(旋转轴Ax1的输入侧)，从内齿21的倒角部211的开始点至外齿31的倒角部311的开始点的距离为突出量L1。同样，在齿向D1的另一方侧(旋转轴Ax1的输出侧)，从内齿21的倒角部211的开始点至外齿31的倒角部311的开始点的距离为突出量L2。
另外，如“(4.1)表面硬度”一栏中说明那样，内齿21的表面硬度比外齿31的表面硬度低。并且，在本实施方式中，表面硬度相对高的外齿31相对于内齿21向齿向D1的至少一方突出，因此在齿向D1的至少一方，难以在内齿21的齿面产生因磨损导致的高低差。即，在齿向D1的至少一方，表面硬度相对低的内齿21由于外齿31的齿接触而均匀地磨损，在内齿21的齿面难以产生局部性的凹陷(高低差)。因此，即使由于某些跳动而存在齿接触位置沿齿向D1偏离的情况，也容易抑制因在内齿21与外齿31之间的啮合部位作用有过大的负载而引起的谐波齿轮装置1的异常的产生。由此，难以产生因内齿21与外齿31的接触引起的缺欠或磨损等所导致的异物X1，能够实现可靠性高的谐波齿轮装置1。
另外，外齿31相对于内齿21向齿向D1的两方突出。即，外齿31相对于内齿21向齿向D1的至少开口面35侧突出。此处，在挠性外齿轮3发生弹性变形的状态下，挠性外齿轮3在旋转轴Ax1的方向上的开口面35侧的端部处比底部322侧的端部更大地变形，成为更接近于椭圆形状的形状。由于这样的在旋转轴Ax1的方向上的变形量的差异，在挠性外齿轮3发生弹性变形的状态下，在挠性外齿轮3的躯体部321的内周面301产生相对于旋转轴Ax1倾斜的锥形面302(参照图8A)。并且，在齿向D1的开口面35侧，外齿31从内齿21突出，由此能够避免因这样的锥形面302而倾 斜的外齿31的前端的角部与内齿21的接触。因此，即使在外齿31的变形引起的应力集中特别容易产生的齿向D1的开口面35侧的端部，在内齿21的齿面也难以产生局部性的凹陷(高低差)。
(4.4)锥形面
接下来，说明在相当于外齿31的里侧的、挠性外齿轮3的内周面301产生的锥形面302。
如上所述，在挠性外齿轮3发生弹性变形的状态下，挠性外齿轮3在旋转轴Ax1的方向上的开口面35侧的端部处比底部322侧的端部更大地变形，成为更接近于椭圆形状的形状。因此，在挠性外齿轮3发生弹性变形的状态下，如图8A及图8B所示，挠性外齿轮3的躯体部321的内周面301包含相对于旋转轴Ax1倾斜的锥形面302。
锥形面302相对于旋转轴Ax1倾斜了倾斜角度θ1。由于产生这样的锥形面302，因此向躯体部321的内侧嵌入的波发生器4的轴承42的外圈421的外周面424(参照图8B)与内周面301(锥形面302)之间的间隙朝向开口面35侧逐渐变大。总之，挠性外齿轮3的内周面301在与波发生器4(的轴承42的外圈421)的外周面424相对的部位具有锥形面302，该锥形面302朝向沿旋转轴Ax1的一方向(开口面35侧)而增大与波发生器4的外周面424之间的间隙。
此处，锥形面302相对于旋转轴Ax1的倾斜角度θ1为5度以下。因此，在锥形面302与波发生器4的外周面424之间产生的间隙为微小的间隙。在本实施方式中，将在锥形面302与波发生器4的外周面424之间产生的微小的间隙用于润滑剂Lb1的保持。具体而言，锥形面302与波发生器4的外周面424之间的微小的间隙中能够保持液状或凝胶状的润滑剂Lb1。
即，在本实施方式的谐波齿轮装置1中，例如，向内齿21与外齿31的啮合部分、及轴承42的外圈421与内圈422之间等注入液状或凝胶状的润滑剂Lb1。作为一例，润滑剂Lb1为液状的润滑油(油)。并且，在谐 波齿轮装置1的使用时，如图8B所示，润滑剂Lb1也进入轴承42的外圈421(外周面424)与挠性外齿轮3的锥形面302之间。由此，润滑剂Lb1将外周面424与锥形面302之间的间隙密封。
在此，相对于波发生器4的轴承42，旋转轴Ax1的输入侧(图8A的右侧)的空间与旋转轴Ax1的输出侧(图8A的左侧)的空间可通过外周面424与锥形面302的间隙相连。这样，形成使波发生器4的外侧(旋转轴Ax1的输入侧)与内侧(旋转轴Ax1的输出侧)相连的狭路的间隙被润滑剂Lb1填埋。因此，旋转轴Ax1的输入侧的空间与旋转轴Ax1的输出侧的空间被润滑剂Lb1遮蔽。因此，如图8B所示，异物X1从旋转轴Ax1的一方侧(输入侧)向波发生器4的内侧的进入受到润滑剂Lb1的阻碍。
即，在本实施方式中，在锥形面302与波发生器4的外周面424之间的间隙中保持润滑剂Lb1。更详细而言，如图8B所示，在锥形面302与波发生器4的外周面424之间的微小的间隙内，通过毛细管现象保持润滑剂Lb1。因此，能维持锥形面302与波发生器4的外周面424的间隙被润滑剂Lb1填埋的状态。毛细管现象产生的保持力的大小也根据锥形面302及外周面424与润滑剂Lb1之间的“浸润性”而变化。因此，至少关于锥形面302及外周面424，优选不具有疏油性。
锥形面302相对于旋转轴Ax1的倾斜角度θ1并不局限于5度以下，例如，可以为10度以下、15度以下或20度以下。而且，在锥形面302与波发生器4的外周面424之间的间隙中保持润滑剂Lb1的情况对于谐波齿轮装置1并非必须的结构，也可以不在该间隙保持润滑剂Lb1。
(5)作用
接下来，更详细地说明本实施方式的谐波齿轮装置1的作用。
谐波齿轮装置1在使挠性外齿轮3发生了弹性变形的状态下，使内齿21与外齿31局部性地啮合，因此内齿21与外齿31的啮合伴有齿形方向(与齿向D1正交的方向)和齿向D1这两个方向上的“滑动”。并且，在谐波齿 轮装置1的通常使用时的两齿轮(刚性内齿轮2及挠性外齿轮3)的相对旋转的转速区域中，润滑剂Lb1的流速为比较低的速度。因此，在内齿21与外齿31的啮合部位，这样比较低速的润滑剂Lb1的流动会在齿形方向及齿向D1这两个方向上产生，通过润滑剂Lb1使在内齿21与外齿31之间产生的异物X1难以向谐波齿轮装置1的外部流动。由此，如上述那样，已经产生的异物X1容易停止于谐波齿轮装置1内，由于这样的异物X1进入轴承42等，引起表面起点型的剥落，导致谐波齿轮装置1的可靠性下降的情况。
作为针对这样的谐波齿轮装置1的可靠性下降的对策，可考虑将轴承42的侧面通过密封构件闭塞(密封)而抑制异物X1向轴承42进入的情况。但是，关于在比较高的减速比且发生弹性变形的轴承42中使用的密封构件，摩擦损失大而难以长寿命化，而且动力传递效率的下降也成为问题。作为其他的对策，例如，可考虑对轴承42的外圈421及内圈422实施抗微点蚀损伤强的渗碳氮化处理等热处理来提高外圈421及内圈422的表面硬度。但是，存在为了避免阻碍轴承42的弹性变形而不怎么能提高外圈421及内圈422的表面硬度这样的问题。
相对于此，在本实施方式的谐波齿轮装置1中，原本就难以产生异物X1，从而也能够消除上述那样的针对轴承42的对策中产生的问题。即，在谐波齿轮装置1中，如本实施方式那样抑制异物X1的产生本身特别有用处，由此，具有下述优点，即：不仅谐波齿轮装置1的可靠性难以下降，而且容易实现长寿命化及动力传递效率的提高。
作为一例，在外圈421的内周面(滚动面)产生因异物X1的进入引起的剥落的情况下，对作为轴承42的功能产生障碍，作为谐波齿轮装置1的动作可能会出现故障。在本实施方式的谐波齿轮装置1中，原本就难以产生异物X1，由此能够压倒性地减少这样的异物X1进入轴承42内的情况，因此有助于谐波齿轮装置1的可靠性的提高。特别是即使在长期使用时也难以产生可靠性的下降，因此，进而也有助于谐波齿轮装置1的长寿命化 及高性能化。
另外，在谐波齿轮装置1中，内齿21的表面硬度比外齿31的表面硬度低。因此，内齿21的齿宽比外齿31的齿宽大，在外齿31收于内齿21的齿向的范围内的情况下，在内齿21的齿面的齿向D1的一部分，由于外齿31接触引起的磨损等而有时会产生局部性的凹陷(高低差)。在这样的产生了凹陷的状态下，如果由于某些跳动而齿接触位置沿齿向(与旋转轴Ax1平行的方向)偏离，则在内齿21与外齿31之间的啮合部位会作用有过大的负载，会导致谐波齿轮装置1的异常。即，即使是表面硬度相对高的外齿31，由于齿向D1的一端部那样的角部分与内齿21的高低差接触，也存在其角部分缺欠而产生硬质的(硬度比较高的)异物X1的可能性。
相对于此，在本实施方式的谐波齿轮装置1中，外齿31相对于内齿21向齿向D1的至少一方突出。因此，在齿向D1的至少一方，表面硬度相对低的内齿21由于外齿31的齿接触而均匀地磨损，在内齿21的齿面难以产生局部性的凹陷(高低差)。因此，即使由于某些跳动而存在齿接触位置沿齿向D1偏离的情况，也容易抑制在内齿21与外齿31之间的啮合部位作用有过大的负载引起的谐波齿轮装置1的异常的产生。即，难以产生外齿31中的齿向D1的一端部那样的角部分的缺欠，结果是，难以产生硬质的(硬度比较高的)异物X1。
另外，作为谐波齿轮装置1的基本结构，由于内齿21及外齿31的同时啮合的齿数比较多，因此具有啮合载荷被分散的优点，另一方面，伴有啮合的滑动比较大而啮合损失容易增大。这样的啮合损失会成为特别是润滑剂Lb1容易硬化的低温环境下等的谐波齿轮装置1的起动性恶化的主要原因。相对于此，根据本实施方式的谐波齿轮装置1，在内齿21中的齿向D1的至少开口面35侧的端部设置齿向修整部210。因此，在齿向D1上滑动量特别大的开口面35侧的端部处的、内齿21与外齿31的啮合减少，从而能够降低啮合损失，能够实现动力传递效率的提高。这样，在本实施方 式的谐波齿轮装置1中，不仅长寿命化，而且通过动力传递效率的提高，还能够实现例如润滑剂Lb1容易硬化的低温环境下的谐波齿轮装置1的起动性的改善。
(6)适用例
接下来，参照图9，说明本实施方式的谐波齿轮装置1及执行器100的适用例。
图9是表示使用了本实施方式的谐波齿轮装置1的机器人9的一例的剖视图。该机器人9是水平多关节机器人，所谓的选择柔性组合机器人臂(SCARA：Selective Compliance Assembly Robot Arm)型机器人。
如图9所示，机器人9包括两个谐波齿轮装置1、连杆91。两个谐波齿轮装置1分别设置于机器人9中的两个部位的关节部。连杆91将两个部位的关节部连结。在图9的例子中，谐波齿轮装置1不是杯型，而是由礼帽型的谐波齿轮装置构成。即，在图9例示的谐波齿轮装置1中，使用形成为礼帽状的挠性外齿轮3。
(7)变形例
上述实施方式只不过是本公开实施例的各种实施方式的一个。上述实施方式只要能够实现本发明的目的，就可以根据设计等进行各种变更。而且，本公开实施例参照的附图都是示意性的图，图中的各结构要素的大小及厚度各自的比未必反映实际的尺寸比。以下，列举上述实施方式的变形例。以下说明的变形例可以适当组合适用。
图10A～图10D示出上述实施方式的变形例，是相当于图5A的A1-A1线剖视图的示出内齿21及外齿31的关系性的图。在图10A～图10D中，省略剖面的剖面线(斜线)。
在图10A所示的第一变形例中，内齿21的齿向修整部(第一修整部)210仅形成于内齿21的齿厚方向D2的两端面中的挠性外齿轮3的旋转方向R1侧的一端面。此外，外齿31的齿向修整部(第二修整部)310仅形 成于外齿31的齿厚方向D2的两端面中的与挠性外齿轮3的旋转方向R1相反的一侧的一端面。由此，在动力传递时，内齿21与外齿31的形成有齿向修整部210、310的齿面彼此接触，因此能够期待与上述实施方式同样的效果。
在图10B所示的第二变形例中，内齿21的齿向修整部(第一修整部)210仅形成于内齿21的齿厚方向D2的两端面中的挠性外齿轮3的旋转方向R1侧的一端面。此外，外齿31的齿向修整部(第二修整部)310仅形成于外齿31的齿厚方向D2的两端面中的挠性外齿轮3的旋转方向R1侧的一端面。在该结构中，通过齿向修整部210、310，也能够期待与上述实施方式同样的效果。
在图10C所示的第三变形例中，仅在内齿21和外齿31中的内齿21设置齿向修整部(第一修整部)210，在外齿31未设置齿向修整部。在该结构中，通过齿向修整部210，能够期待与上述实施方式同样的效果。作为又一例，可以是仅在内齿21和外齿31中的外齿31设置齿向修整部(第二修整部)310，在内齿21未设置齿向修整部的结构。
在图10D所示的第四变形例中，仅在内齿21的齿向D1的一端部设置齿向修整部(第一修整部)210，仅在外齿31的齿向D1的一端部设置齿向修整部(第二修整部)310。在图10D的例子中，齿向修整部210、310都设置于齿向D1的开口面35侧的端部。作为又一例，齿向修整部210、310的至少一方可以设置于齿向D1的开口面35的相反侧的端部。
图10A～图10D所示的变形例的结构可以适当组合适用。例如，通过第三变形例与第四变形例的组合，可以仅在内齿21和外齿31中的内齿21设置齿向修整部210，且齿向修整部210仅设置于内齿21的齿向D1的一端部。
另外，对内齿21及外齿31实施齿形修整的情况对于谐波齿轮装置1不是必须的结构。例如，也可以对内齿21和外齿31中的至少一方不实施 齿形修整。
另外，内齿21具有齿向修整部210的结构、和内齿21的表面硬度比外齿31的表面硬度低且外齿31相对于内齿21向齿向D1的至少一方突出的结构可以分别单独采用。即，即使单独为内齿21的表面硬度比外齿31的表面硬度低且外齿31相对于内齿21向齿向D1的至少一方突出的结构，也难以产生因内齿21与外齿31的接触引起的缺欠或磨损等所导致的异物X1。因此，即使内齿21不具有齿向修整部210，也能够实现可靠性高的谐波齿轮装置1。另一方面，即使单独为内齿21具有齿向修整部210的结构，也难以产生因内齿21与外齿31的接触引起的缺欠或磨损等所引起的异物X1。因此，即使外齿31相对于内齿21不向齿向D1的至少一方突出，也能够实现可靠性高的谐波齿轮装置1。
此外，关于在锥形面302与波发生器4的外周面424之间的间隙保持润滑剂Lb1的结构，也可以将其单独采用。即，即使内齿21不具有齿向修整部210且外齿31相对于内齿21不向齿向D1的至少一方突出，在锥形面302与波发生器4的外周面424之间的间隙也能够保持润滑剂Lb1。
另外，谐波齿轮装置1并不局限于上述实施方式中说明的杯型，例如，可以为礼帽型、环型、差动型、平坦型(扁平型)或罩壳型等。例如，可以是图9例示那样的礼帽型的谐波齿轮装置1，与杯型同样，具有在齿向D1的一方具有开口面35的筒状的挠性外齿轮3。即，礼帽状的挠性外齿轮3在旋转轴Ax1的一方侧的端部具有凸缘部，在与凸缘部相反一侧的端部具有开口面35。即使是礼帽状的挠性外齿轮3，在开口面35侧的端部也具有外齿31且供波发生器4嵌入。
另外，关于执行器100的结构，也并不局限于上述实施方式中说明的结构，可以适当变更。例如，关于输入部103与凸轮41的连结结构，并不局限于花键连结结构，可以使用欧氏接头等。通过使用欧氏接头作为输入部103与凸轮41的连结结构，能够使输入侧的旋转轴Ax1与波发生器4(凸 轮41)之间的偏芯相抵消，而且，能够使刚性内齿轮2与挠性外齿轮3的偏芯相抵消。此外，凸轮41可以是相对于输入部103不能沿旋转轴Ax1移动。
另外，本实施方式的谐波齿轮装置1及执行器100的适用例并不局限于上述那样的水平多关节机器人，例如，可以是水平多关节机器人以外的产业用机器人或产业用以外的机器人等。在水平多关节机器人以外的产业用机器人中，作为一例，存在垂直多关节型机器人或平行连杆型机器人等。在产业用以外的机器人中，作为一例，存在家庭用机器人、护理用机器人或医疗用机器人等。
另外，轴承42并不局限于深沟球轴承，例如，可以为角接触球轴承等。此外，轴承42并不局限于球轴承，例如，可以是滚动体423由不是球状的“滚子”构成的圆柱滚子轴承、针状滚子轴承或圆锥滚子轴承等滚子轴承。
另外，谐波齿轮装置1或执行器100的各结构要素的材质并不局限于金属，例如，可以为工程塑料等树脂。
另外，润滑剂Lb1并不局限于润滑油(油)等液状的物质，可以为润滑脂等凝胶状的物质。
另外，外齿31从内齿21的突出量L1、L2并不局限于在齿向D1的两侧大致相同。例如，齿向D1的一方侧(旋转轴Ax1的输入侧)的突出量L1可以比齿向D1的另一方侧(旋转轴Ax1的输出侧)的突出量L2大。相反，齿向D1的一方侧(旋转轴Ax1的输入侧)的突出量L1可以比齿向D1的另一方侧(旋转轴Ax1的输出侧)的突出量L2小。
另外，第二修整部310的修整量Q2比第一修整部210的修整量Q1小的情况对于谐波齿轮装置1并非必须的结构。例如，第二修整部310的修整量Q2可以与第一修整部210的修整量Q1相等(Q1＝Q2)，也可以比第一修整部210的修整量Q1大(Q1<Q2)。
如图11A～图12C所示，另一实施方式的谐波齿轮装置1A在内齿21 的齿向修整部(第一修整部)210通过修缘加工形成这一点上与上述实施方式的谐波齿轮装置1不同。以下，关于与上述实施方式同样的结构，标注相同的符号而适当省略说明。
图11A是着眼于内齿21及外齿31的剖视图，图11B是图11A的A1-A1线剖视图。图12A是图11A的B1-B1线剖视图，图12B是图11A的B2-B2线剖视图，图12C是图11A的B3-B3线剖视图。
内齿21的齿向修整部(第一修整部)210在上述实施方式中通过鼓形修整而形成，而在本实施方式中是通过修缘加工而形成的。即，第一修整部210是对内齿21以齿向D1的中央部成为凸起的方式，使齿向D1的中央部仍为正规的齿向形状、仅将齿向D1的两端部加工成锥形状而成的。在本实施方式中，同样，外齿31的齿向修整部(第二修整部)310也通过修缘加工形成。这样，第一修整部210和第二修整部310都是基于同一种类(在此为修缘加工)的齿向修整。
在本实施方式中，如图11A及图11B所示，对内齿21的齿底212、齿顶213、齿厚方向D2的两端面都实施由修缘加工构成的齿向修整。关于外齿31也同样，对于外齿31的齿底312、齿顶313、齿厚方向D2的两端面都实施由修缘加工构成的齿向修整。
根据上述那样的齿向修整部210、310，如图11B所示，内齿21及外齿31的各自的齿厚在齿向D1的中央部最大，在修缘加工的开始点以后，朝向齿向D1的两端逐渐减小。因此，在内齿21与外齿31的啮合位置处，在齿向D1上，在未实施齿向修整(在此为修缘加工)的中央部(非修整部)，内齿21与外齿31的间隙变得最小。
总之，在图12A～图12C的例子中，在齿向D1上的修缘加工的开始点的剖面即图12A中，内齿21与外齿31的间隙G1变得最小。即，朝向齿向D1的一端(旋转轴Ax1的输出侧)，内齿21与外齿31的间隙G1按照图12B、图12C的顺序变大。这样，通过齿向修整，越从齿向D1的中央部 分离，则齿面越逐渐向负方向移位，因此内齿21与外齿31的间隙G1变大。
作为本实施方式的变形例，例如，可以如第一修整部210为修缘加工而第二修整部310为鼓形修整那样，第一修整部210与第二修整部310为不同种类的齿向修整。相反，可以是第一修整部210为鼓形修整，第二修整部310为修缘加工。
本实施方式的结构(包括变形例)可以与上述实施方式中说明的结构(包括变形例)适当组合适用。
如图13所示，再一实施方式的谐波齿轮装置1B在外齿31相对于内齿21仅向齿向D1的一方突出的点上与上述实施方式的谐波齿轮装置1不同。图13是着眼于内齿21及外齿31的剖视图，省略剖面的剖面线(斜线)。以下，关于与上述实施方式同样的结构，标注相同的符号而适当省略说明。
即，外齿31在上述实施方式中相对于内齿21向齿向D1的两方(旋转轴Ax1的输入侧及输出侧)突出，相对于此，在本实施方式中相对于内齿21仅向齿向D1的单方突出。特别是在本实施方式中，外齿31相对于内齿21向齿向D1的开口面35侧，即旋转轴Ax1的输入侧突出。即，在本实施方式中，外齿31相对于内齿21向齿向D1的开口面35侧(旋转轴Ax1的输入侧)突出，不向齿向D1的开口面35的相反侧(旋转轴Ax1的输出侧)突出。
在此，在挠性外齿轮3发生弹性变形的状态下，挠性外齿轮3在旋转轴Ax1的方向上的开口面35侧的端部处比底部322侧的端部更大地变形，成为更接近于椭圆形状的形状。如本实施方式那样，在齿向D1的开口面35侧，外齿31从内齿21突出，由此能够避免由于这样的锥形面302而倾斜的外齿31的前端的角部与内齿21的接触。因此，根据本实施方式的结构，在因外齿31的变形而引起的应力集中特别容易产生的齿向D1的开口面35侧的端部，在内齿21的齿面难以产生局部性的凹陷(高低差)。
作为本实施方式的变形例，外齿31可以相当于内齿21，仅向齿向D1 的开口面35的相反侧、即旋转轴Ax1的输出侧突出。在该情况下，外齿31相对于内齿21不向齿向D1的开口面35侧(旋转轴Ax1的输入侧)突出。
本实施方式的结构(包括变形例)可以与上述实施方式或上述另一实施方式中说明的结构(包括变形例)适当组合地适用。
(总结)
如以上说明所述，第一形态的谐波齿轮装置(1、1A、1B)包括刚性内齿轮(2)、挠性外齿轮(3)和波发生器(4)。刚性内齿轮(2)是具有内齿(21)的环状的部件。挠性外齿轮(3)是具有外齿(31)且配置在刚性内齿轮(2)的内侧的环状的部件。波发生器(4)配置在挠性外齿轮(3)的内侧，使挠性外齿轮(3)产生挠曲。谐波齿轮装置(1、1A、1B)伴随着以旋转轴(Ax1)为中心的波发生器(4)的旋转而使挠性外齿轮(3)变形，使外齿(31)的一部分与内齿(21)的一部分啮合，从而使挠性外齿轮(3)根据挠性外齿轮(3)与刚性内齿轮(2)的齿数差而相对于刚性内齿轮(2)相对旋转。内齿(21)在内齿(21)的齿向(D1)的至少一方的端部具有齿向修整部(210)。
根据该形态，通过内齿(21)的齿向修整部(210)与外齿(31)之间形成“避让部”，在内齿(21)的齿向(D1)的至少一方的端部，能够难以产生与外齿(31)的过度的齿接触引起的应力集中。特别是在谐波齿轮装置(1、1A、1B)中，波发生器(4)使挠性外齿轮(3)挠曲，由此有时会相对于旋转轴(Ax1)产生外齿(31)的扭转及偏斜(倾斜)等变形。因此，在内齿(21)的齿向(D1)的至少一方的端部，容易产生由外齿(31)的变形引起的应力集中，但是通过齿向修整部(210)，能够使这样的应力集中难以产生。由此，由内齿(21)与外齿(31)的接触导致的缺欠或磨损等引起的异物(X1)难以产生，能够提供可靠性高的谐波齿轮装置(1、1A、1B)。而且，由于齿向修整部(210)设置于刚性内齿轮(2)，因此对于 挠性外齿轮(3)不需要齿向修整或能够减小修整量，容易抑制对具有挠性的挠性外齿轮(3)实施齿向修整引起的挠性外齿轮(3)的强度下降。
在第二形态的谐波齿轮装置(1、1A、1B)中，以第一形态为基础，内齿(21)具有作为齿向修整部(210)的第一修整部(210)。外齿(31)具有第二修整部(310)，该第二修整部(310)是与第一修整部(210)不同的齿向修整部(310)。
根据该形态，由于内齿(21)及外齿(31)双方具有齿向修整部(210、310)，因此能够改善内齿(21)与外齿(31)的齿接触情况。
在第三形态的谐波齿轮装置(1、1A、1B)中，以第二形态为基础，第二修整部(310)的修整量(Q2)比第一修整部(210)的修整量(Q1)小。
根据该形态，通过将外齿(31)的修整量(Q2)抑制得小，容易实现对发生弹性变形(挠曲)的挠性外齿轮(3)的外齿(31)所要求的弯曲应力的耐受性。
在第四形态的谐波齿轮装置(1、1A、1B)中，以第二或第三形态为基础，第一修整部(210)和第二修整部(310)包含同一种类的修整。
根据该形态，第一修整部(210)及第二修整部(310)的加工容易。
在第五形态的谐波齿轮装置(1、1A、1B)中，以第一～第四的任一形态为基础，挠性外齿轮(3)的内周面(301)在与波发生器(4)的外周面(424)相对的部位具有锥形面(302)。锥形面(302)朝向沿旋转轴(Ax1)的一个方向而增大与波发生器(4)的外周面(424)的间隙。在锥形面(302)与波发生器(4)的外周面(424)之间的间隙保持润滑剂(Lb1)。
根据该形态，容易抑制异物(X1)通过锥形面(302)与波发生器(4)的外周面(424)之间的间隙进入。
在第六形态的谐波齿轮装置(1、1A、1B)中，以第五形态为基础，锥形面(302)相对于旋转轴(Ax1)的倾斜角度(θ1)为5度以下。
根据该形态，能够使锥形面(302)与波发生器(4)的外周面(424) 之间的间隙成为微小的间隙，例如，能够利用毛细管现象保持润滑剂(Lb1)。
在第七形态的谐波齿轮装置(1、1A、1B)中，以第一～第六的任一形态为基础，齿向修整部(210)在内齿(21)的齿底(212)、齿顶(213)、齿厚方向(D2)的一端面的至少一个包含倾斜面。倾斜面相对于齿向(D1)倾斜。
根据该形态，通过对内齿(21)的齿底(212)、齿顶(213)、齿厚方向(D2)的一端面的至少一个进行的齿向修整，能够改善齿接触情况。
在第八形态的谐波齿轮装置(1、1A、1B)中，以第七形态为基础，齿向修整部(210)至少在齿底(212)包含倾斜面。
根据该形态，容易避免外齿(31)的齿顶(313)与内齿(21)的齿底(212)的接触。
在第九形态的谐波齿轮装置(1、1A、1B)中，以第一～第八的任一形态为基础，挠性外齿轮(3)为在齿向(D1)的一方具有开口面(35)的筒状。齿向修整部(210)设置于内齿(21)中的齿向(D1)的至少开口面(35)侧的端部。
根据该形态，在由外齿(31)的变形导致的应力集中特别容易产生的齿向(D1)的开口面(35)侧的端部处，通过齿向修整部(210)，能够难以产生应力集中。
第十形态的执行器(100)包括第一～第九的任一形态的谐波齿轮装置(1、1A、1B)、驱动源(101)和输出部(102)。驱动源(101)使波发生器(4)旋转。输出部(102)将刚性内齿轮(2)及挠性外齿轮(3)中的任一方的旋转力取出而作为输出。
根据该形态，由内齿(21)与外齿(31)的接触导致的缺欠或磨损等引起的异物(X1)难以产生，能够提供可靠性高的执行器(100)。
另外，第五形态的谐波齿轮装置(1、1A、1B)的结构无论第一形态的齿向修整部(210)的有无，都可以单独采用。即，谐波齿轮装置(1、1A、 1B)包括刚性内齿轮(2)、挠性外齿轮(3)和波发生器(4)。刚性内齿轮(2)是具有内齿(21)的环状的部件。挠性外齿轮(3)是具有外齿(31)且配置在刚性内齿轮(2)的内侧的环状的部件。波发生器(4)配置在挠性外齿轮(3)的内侧，使挠性外齿轮(3)产生挠曲。谐波齿轮装置(1、1A、1B)伴随着以旋转轴(Ax1)为中心的波发生器(4)的旋转而使挠性外齿轮(3)变形，使外齿(31)的一部分与内齿(21)的一部分啮合，使挠性外齿轮(3)根据挠性外齿轮(3)与刚性内齿轮(2)的齿数差而相对于刚性内齿轮(2)相对旋转。其中，挠性外齿轮(3)的内周面(301)在与波发生器(4)的外周面(424)相对的部位具有锥形面(302)。锥形面(302)朝向沿旋转轴(Ax1)的一个方向而增大与波发生器(4)的外周面(424)的间隙。在锥形面(302)与波发生器(4)的外周面(424)之间的间隙保持润滑剂(Lb1)。
关于第二～第九形态的结构，对于谐波齿轮装置(1、1A、1B)并非必须的结构，可以适当省略。
附图标记说明
1、1A、1B 谐波齿轮装置
2 刚性内齿轮
3 挠性外齿轮
4 波发生器
21 内齿
31 外齿
35 开口面
100 执行器
101 驱动源
102 输出部
210 齿向修整部(第一修整部)
212 齿底
213 齿顶
301 (挠性外齿轮的)内周面
302 锥形面
310 齿向修整部(第二修整部)
424 (波发生器的)外周面
Ax1 旋转轴
D1 齿向
D2 齿厚方向
Lb1 润滑剂
Q1 第一修整部的修整量
Q2 第二修整部的修整量
θ1 倾斜角度
工业实用性
根据本公开实施例，能够提供可靠性高的谐波齿轮装置及执行器。

Claims (10)

  1. 一种谐波齿轮装置，包括：
    具有内齿的环状的刚性内齿轮；
    具有外齿且配置在所述刚性内齿轮的内侧的环状的挠性外齿轮；和
    配置在所述挠性外齿轮的内侧并使所述挠性外齿轮产生挠曲的波发生器，
    所述谐波齿轮装置伴随着以旋转轴为中心的所述波发生器的旋转而使所述挠性外齿轮变形，使所述外齿的一部分与所述内齿的一部分啮合，从而使所述挠性外齿轮根据所述挠性外齿轮与所述刚性内齿轮的齿数差而相对于所述刚性内齿轮相对旋转，
    其中，所述内齿在所述内齿的齿向的至少一方的端部具有齿向修整部。
  2. 根据权利要求1所述的谐波齿轮装置，其中，
    所述内齿具有作为所述齿向修整部的第一修整部，
    所述外齿具有第二修整部，所述第二修整部是与所述第一修整部不同的齿向修整部。
  3. 根据权利要求2所述的谐波齿轮装置，其中，
    所述第二修整部的修整量比所述第一修整部的修整量小。
  4. 根据权利要求2或3所述的谐波齿轮装置，其中，
    所述第一修整部和所述第二修整部包含同一种类的修整。
  5. 根据权利要求1～4中任一项所述的谐波齿轮装置，其中，
    所述挠性外齿轮的内周面在与所述波发生器的外周面相对的部位具有锥形面，所述锥形面朝向沿着所述旋转轴的一个方向而增大与所述波发生器的所述外周面之间的间隙，
    在所述锥形面与所述波发生器的所述外周面之间的间隙保持润滑剂。
  6. 根据权利要求5所述的谐波齿轮装置，其中，
    所述锥形面相对于所述旋转轴的倾斜角度为5度以下。
  7. 根据权利要求1～6中任一项所述的谐波齿轮装置，其中，
    所述齿向修整部在所述内齿的齿底、齿顶、齿厚方向的一端面的至少一个包含相对于所述齿向倾斜的倾斜面。
  8. 根据权利要求7所述的谐波齿轮装置，其中，
    所述齿向修整部至少在所述齿底包含所述倾斜面。
  9. 根据权利要求1～8中任一项所述的谐波齿轮装置，其中，
    所述挠性外齿轮为在所述齿向的一方具有开口面的筒状，
    所述齿向修整部设置于所述内齿的所述齿向的至少所述开口面侧的端部。
  10. 一种执行器，包括：
    权利要求1～9中任一项所述的谐波齿轮装置；
    使所述波发生器旋转的驱动源；和
    将所述刚性内齿轮及所述挠性外齿轮的任一方的旋转力取出而作为输出的输出部。
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Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3996816A (en) * 1974-08-01 1976-12-14 The Secretary Of State For Defence In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern Ireland Harmonic drives
JP2001059153A (ja) 1999-08-19 2001-03-06 Harmonic Drive Syst Ind Co Ltd 異なる板厚部分を備えた金属部材の表面硬化方法
CN104514847A (zh) * 2014-12-19 2015-04-15 西安交通大学 一种具有鼓形轮齿的扁平谐波传动装置
CN204748646U (zh) * 2015-07-02 2015-11-11 成都三译智能技术有限公司 一种机器人关节减速器
CN106090185A (zh) * 2016-06-16 2016-11-09 南通慧幸智能科技有限公司 三维高刚性谐波减速器的齿型设计方法
CN109695694A (zh) * 2018-12-10 2019-04-30 广州市昊志机电股份有限公司 渐开线谐波齿轮的修形方法及谐波减速器
JP2020174376A (ja) 2016-07-29 2020-10-22 エルジー イノテック カンパニー リミテッド カメラモジュール及びその組立方法

Family Cites Families (33)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3161082A (en) * 1962-04-11 1964-12-15 United Shoe Machinery Corp Wave generator
JPS60215139A (ja) * 1984-04-09 1985-10-28 Nippon Seiko Kk 調和駆動減速装置
DD244796A1 (de) * 1985-12-23 1987-04-15 Wtz Getriebe & Kupplungen Veb Verzahnung an wellgetrieben, insbesondere mit topffoermigem elastischen rad
KR20090098533A (ko) * 2008-03-14 2009-09-17 이부락 하모닉 감속기 치형 구조
JP5275150B2 (ja) * 2009-06-23 2013-08-28 株式会社ハーモニック・ドライブ・システムズ 波動歯車装置
JP5275265B2 (ja) * 2010-01-18 2013-08-28 株式会社ハーモニック・ドライブ・システムズ ３次元接触の正偏位歯形を有する波動歯車装置
DE112011103908T5 (de) * 2011-02-04 2013-09-19 Harmonic Drive Systems Inc. Wellgetriebe mit einem Evolventen-Zahnprofil mit positiver Verbiegung, das dreidimensional im Kontakt steht
JP5734102B2 (ja) * 2011-06-01 2015-06-10 株式会社ハーモニック・ドライブ・システムズ テーパ型の可撓性外歯車を備えた波動歯車装置
CN103827542B (zh) * 2011-09-29 2016-09-21 谐波传动系统有限公司 具有锥形可挠性外齿轮的波动齿轮装置
KR101782041B1 (ko) * 2012-01-10 2017-10-23 가부시키가이샤 하모닉 드라이브 시스템즈 림 두께를 고려한 인벌류트 양편위 치형을 갖는 파동 기어 장치
CN103547830B (zh) * 2012-05-23 2016-01-13 谐波传动系统有限公司 波动齿轮装置的波动发生器
US9003924B2 (en) * 2012-05-23 2015-04-14 Harmonic Drive Systems Inc. Wave gear device and flexible externally toothed gear
DE102012109774B9 (de) * 2012-10-15 2016-12-22 Ovalo Gmbh Elastisch verformbares Getriebebauteil und Spannungswellengetriebe mit einem solchen Getriebebauteil
WO2015079576A1 (ja) * 2013-11-29 2015-06-04 株式会社ハーモニック・ドライブ・システムズ ２度接触の負偏位歯形を有する波動歯車装置
JP2015209931A (ja) * 2014-04-28 2015-11-24 キヤノン株式会社 波動歯車装置及びロボットアーム
JP6218691B2 (ja) * 2014-07-23 2017-10-25 株式会社ハーモニック・ドライブ・システムズ デュアルタイプの波動歯車装置
DE102015104135A1 (de) * 2015-03-19 2016-09-22 Harmonic Drive Ag Wellgetriebe mit Trockenlauf
RU2728990C1 (ru) * 2017-01-21 2020-08-03 Хармоник Драйв Системс Инк. Волновая передача
CN107100982B (zh) * 2017-05-16 2020-07-31 王家梁 一种零回差谐波齿轮传动装置
JP6830736B2 (ja) * 2017-06-05 2021-02-17 株式会社ハーモニック・ドライブ・システムズ ２応力純分離の波動歯車装置
JP6912989B2 (ja) * 2017-09-27 2021-08-04 住友重機械工業株式会社 撓み噛合い式歯車装置
JP2019138412A (ja) * 2018-02-14 2019-08-22 セイコーエプソン株式会社 ロボットおよび歯車装置
JPWO2019220515A1 (ja) * 2018-05-14 2021-02-12 株式会社ハーモニック・ドライブ・システムズ 波動歯車装置
JP2021175916A (ja) * 2020-04-28 2021-11-04 霊智信息服務（深▲セン▼）有限公司 波動歯車装置、アクチュエータ及びカバー体
JP2022065727A (ja) * 2020-10-16 2022-04-28 霊智信息服務（深▲セン▼）有限公司 波動歯車装置及びアクチュエータ
CN112610599B (zh) * 2020-12-01 2022-10-28 广州市昊志机电股份有限公司 一种柔性轴承和谐波减速器
CN112483625B (zh) * 2020-12-09 2022-07-26 广州市昊志机电股份有限公司 一种谐波齿轮的修形方法和谐波减速器
KR102431777B1 (ko) * 2021-01-26 2022-08-16 주식회사 에스 피 지 외치 기어 및 이를 구비하는 파동 기어 장치
JP7490618B2 (ja) * 2021-07-19 2024-05-27 美的集団股▲フン▼有限公司 波動歯車装置及びアクチュエータ
JP7490627B2 (ja) * 2021-10-25 2024-05-27 美的集団股▲フン▼有限公司 波動歯車装置の製造方法
JP2023063961A (ja) * 2021-10-25 2023-05-10 美的集団股▲フン▼有限公司 波動歯車装置、波動歯車装置の製造方法、ロボット用関節装置及び歯車部品
CN115492912A (zh) * 2022-09-30 2022-12-20 南通振康机械有限公司 一种高精度低振动的双刚轮谐波减速机
CN117628141A (zh) * 2024-01-26 2024-03-01 广东极亚精机科技有限公司 柔性外齿齿轮、谐波齿轮装置以及机器人用关节装置

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3996816A (en) * 1974-08-01 1976-12-14 The Secretary Of State For Defence In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern Ireland Harmonic drives
JP2001059153A (ja) 1999-08-19 2001-03-06 Harmonic Drive Syst Ind Co Ltd 異なる板厚部分を備えた金属部材の表面硬化方法
CN104514847A (zh) * 2014-12-19 2015-04-15 西安交通大学 一种具有鼓形轮齿的扁平谐波传动装置
CN204748646U (zh) * 2015-07-02 2015-11-11 成都三译智能技术有限公司 一种机器人关节减速器
CN106090185A (zh) * 2016-06-16 2016-11-09 南通慧幸智能科技有限公司 三维高刚性谐波减速器的齿型设计方法
JP2020174376A (ja) 2016-07-29 2020-10-22 エルジー イノテック カンパニー リミテッド カメラモジュール及びその組立方法
CN109695694A (zh) * 2018-12-10 2019-04-30 广州市昊志机电股份有限公司 渐开线谐波齿轮的修形方法及谐波减速器

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of EP4198349A4

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