Gear device and robot

{
  "publication_number": "US11441661B2",
  "country": "US",
  "kind": "B2",
  "title": "Gear device and robot",
  "abstract": "A gear device includes an internal gear, an external gear having flexibility configured to partially mesh with the internal gear and rotate, and a wave generator provided on an inner side of the external gear and configured to move a meshing position of the internal gear and the external gear in a circumferential direction around the rotation axis. A main material of the internal gear includes graphite particles. A tooth surface of an internal tooth of the internal gear has a convex pattern including a first convex part and a second convex part extending in a first direction having a component along the rotation axis and arranged side by side in a second direction crossing the first direction, and 10≤D≤40 and S−D≤20, wherein D [μm] is an average particle diameter of the graphite particles and S [μm] is a separation distance between the first convex part and the second convex part in the second direction.",
  "claims": [
    "1. A gear device comprising: an internal gear; an external gear having flexibility configured to partially mesh with the internal gear and relatively rotate around a rotation axis with respect to the internal gear; and a wave generator provided on an inner side of the external gear and configured to move a meshing position of the internal gear and the external gear in a circumferential direction around the rotation axis, wherein a main material of the internal gear includes graphite particles, a tooth surface of an internal tooth of the internal gear has a convex pattern including a first convex part and a second convex part extending in a first direction having a component along the rotation axis and arranged side by side in a second direction crossing the first direction, and 10≤D≤40 and S−D≤20, wherein D [μm] is an average particle diameter of the graphite particles and S [μm] is a separation distance between the first convex part and the second convex part in the second direction.",
    "2. The gear device according to claim 1, wherein the internal gear satisfies S−D≤10.",
    "3. The gear device according to claim 2, wherein the internal gear satisfies S−D≤−10.",
    "4. The gear device according to claim 1, wherein a main material of the external gear is nickel-chrome-molybdenum steel.",
    "5. A robot comprising: a first member; a second member configured to turn with respect to the first member; the gear device according to claim 1 configured to transmit driving force for relatively turning the second member with respect to the first member; and a driving source configured to output the driving force toward the gear device."
  ],
  "description_excerpt": "The present application is based on, and claims priority from JP Application Serial Number 2020-033255, filed Feb. 28, 2020, the disclosure of which is hereby incorporated by reference herein in its entirety.\n\nThe present disclosure relates to a gear device and a robot.\n\nIn a robot including a robot arm including at least one arm, for example, a joint section of the robot arm is turned by motor driving. Rotation of a motor is decelerated by a speed reducer and transmitted to the robot arm.\n\nAs such a speed reducer, for example, a wave gear device described in JP-A-2002-307237 (Patent Literature 1) is known. The wave gear device described in Patent Literature 1 is configured by a rigid internal gear formed in an annular shape, a cup-like flexible external gear disposed on the inner side of the internal gear, and a wave generator having an elliptical contour fit on the inner side of the external gear. Spherical graphite cast iron is used as a material forming the internal gear. The spherical graphite cast iron includes graphite particles and can impart satisfactory lubricity by the graphite particles to a meshing position of the internal gear and the external gear. Consequently, extension of the life of the wave gear device can be achieved.\n\nHowever, even if the internal gear includes the graphite particles, if the graphite particles exposed to a position where internal teeth and external teeth rub with each other are few, sufficient lubricity cannot be imparted to the meshing position of the internal gear and the external gear. In this case, extension of the life of the wave gear device cannot be achieved.",
  "cpc": [
    "F16H 49/001",
    "B25J 9/102",
    "B25J 9/1025",
    "F16H 57/041",
    "F16H 57/0464"
  ],
  "ipc": [
    "B25J 9/10",
    "F16H 49/00"
  ],
  "assignees": [
    "Seiko Epson Corp"
  ],
  "inventors": [
    "Satoru MASAI",
    "Yuya KATAOKA",
    "Nobuyuki TAKEHANA",
    "Yoshiyuki SOYA"
  ],
  "filing_date": "2021-02-26",
  "publication_date": "2022-09-13",
  "grant_date": "2022-09-13",
  "priority_date": "2020-02-28",
  "application_number": "US-202117186020-A",
  "family_id": "77414486",
  "cited_by_count": 0,
  "citations": [
    "JP2002307237A",
    "US20040103536A1",
    "US20110154928A1",
    "US10941847B2",
    "US20150323053A1",
    "US20160258522A1",
    "US10151377B2",
    "US11198181B2",
    "US11185921B2"
  ]
}