Parallel link mechanism, constant velocity universal joint, and link actuator

{
  "publication_number": "US9316266B2",
  "country": "US",
  "kind": "B2",
  "title": "Parallel link mechanism, constant velocity universal joint, and link actuator",
  "abstract": "A parallel link mechanism includes proximal end side and distal end side link hubs, and three or more link mechanisms. Each link mechanism is a trinodal link mechanism including four revolute pairs, and includes proximal side and distal side end link members and an intermediate link member. In each revolute pair of the link mechanism, a pair of pair constituent members is connected to each other via a bearing. A shaft portion provided in one pair constituent member is fitted on an inner periphery of an inner ring of the bearing, and an annular inner face forming portion provided in the other pair constituent member is fitted on an outer periphery of the outer ring of the bearing. The shaft portion and the annular inner face forming portion define a sealing structure which regulates flow of a lubricant between inside and outside of the bearing.",
  "claims": [
    "1. A parallel link mechanism comprising: a proximal end side link hub; a distal end side link hub; and three or more link mechanisms that connect the distal end side link hub to the proximal end side link hub in a position-changeable fashion, each of the link mechanisms having a trinodal structure with four revolute pairs, and including a proximal side end link member, one end of the proximal side end link member being pivotably connected to the proximal end side link hub; a distal side end link member, one end of the distal side end link member being pivotably connected to the distal end side link hub; and an intermediate link member which is pivotably connected to the other ends of the proximal side end link member and the distal side end link member, and each of the link mechanisms having such a shape that a geometric model of the link mechanism represented by lines shows symmetry between a proximal end side portion thereof and a distal end side portion thereof with respect to a center portion of the intermediate link member, wherein each revolute pair of each of the link mechanisms includes one pair of pair constituent members connected to each other via a bearing, wherein one of the pair constituent members is formed with a shaft portion fitted to an inner periphery of an inner ring of the bearing, and the other of the pair constituent members is formed with an annular inner face forming portion fitted to an outer periphery of an outer ring of the bearing, wherein the shaft portion has a part formed as a stepped portion having an outer diameter greater than that of a portion of the shaft portion that is fitted to the inner periphery of the inner ring of the bearing, and having a stepped surface configured to abut against an end face of the inner ring to axially position the inner ring, wherein the annular inner face forming portion has a part formed as a stepped portion having an inner diameter smaller than that of a portion of the annular inner face forming portion that is fitted to the outer periphery of the outer ring of the bearing, and having a stepped surface configured to abut against an end face of the outer ring to axially position the outer ring, and wherein the shaft portion and the annular inner face forming portion cooperatively define a first sealing structure to regulate a flow of a lubricant between inside and outside of the bearing, the first sealing structure being defined in the form of a gap between an outer peripheral face of the stepped portion of the shaft portion and an inner peripheral face of the stepped portion of the annular inner face forming portion.",
    "2. A parallel link mechanism comprising: a proximal end side link hub; a distal end side link hub; and three or more link mechanisms that connect the distal end side link hub to the proximal end side link hub in a position-changeable fashion, each of the link mechanisms having a trinodal structure with four revolute pairs, and including a proximal side end link member, one end of the proximal side end link member being pivotably connected to the proximal end side link hub; a distal side end link member, one end of the distal side end link member being pivotably connected to the distal end side link hub; and an intermediate link member which is pivotably connected to the other ends of the proximal side end link member and the distal side end link member, and each of the link mechanisms having such a shape that a geometric model of the link mechanism represented by lines shows symmetry between a proximal end side portion thereof and a distal end side portion thereof with respect to a center portion of the intermediate link member, wherein each revolute pair of each of the link mechanisms includes one pair of pair constituent members connected to each other via a bearing, wherein one of the pair constituent members is formed with a shaft portion fitted to an inner periphery of an inner ring of the bearing, and the other of the pair constituent members is formed with an annular inner face forming portion fitted to an outer periphery of an outer ring of the bearing, the shaft portion and the annular inner face forming portion cooperatively define a first sealing structure to regulate a flow of a lubricant between inside and outside of the bearing, further comprising an inner ring fixation element to fix an axial position of the inner ring of the bearing, and a spacer member interposed between the inner ring fixation element and the inner ring of the bearing, wherein the spacer member and the annular inner face forming portion cooperatively define a second sealing structure to regulate a flow of a lubricant between inside and outside of the bearing.",
    "3. The parallel link mechanism as claimed in claim 2, wherein the second sealing structure is defined in the form of a gap between an outer peripheral face of a part of the spacer member and an inner peripheral face of a part of the annular inner face forming portion.",
    "4. The parallel link mechanism as claimed in claim 3, wherein the annular inner face forming portion has a portion formed as an outer ring fit portion having an inner diameter equal to an outer diameter of the outer ring of the bearing, and the outer ring is fitted on the outer ring fit portion.",
    "5. The parallel link mechanism as claimed in claim 3, wherein the part of the annular inner face forming portion is formed as a stepped portion having an inner diameter smaller than that of a portion of the annular inner face forming portion that is fitted to the outer periphery of the outer ring of the bearing, and having a stepped surface configured to abut against an end face of the outer ring to axially position the outer ring.",
    "6. The parallel link mechanism as claimed in claim 2, wherein the inner ring fixation element is a nut threadedly engaged on a threaded portion formed in the shaft portion.",
    "7. A parallel link mechanism comprising: a proximal end side link hub; a distal end side link hub; and three or more link mechanisms that connect the distal end side link hub to the proximal end side link hub in a position-changeable fashion, each of the link mechanisms having a trinodal structure with four revolute pairs, and including a proximal side end link member, one end of the proximal side end link member being pivotably connected to the proximal end side link hub; a distal side end link member, one end of the distal side end link member being pivotably connected to the distal end side link hub; and an intermediate link member which is pivotably connected to the other ends of the proximal side end link member and the distal side end link member, and each of the link mechanisms having such a shape that a geometric model of the link mechanism represented by lines shows symmetry between a proximal end side portion thereof and a distal end side portion thereof with respect to a center portion of the intermediate link member, wherein each revolute pair of each of the link mechanisms includes one pair of pair constituent members connected to each other via a bearing, wherein one of the pair constituent members is formed with a shaft portion fitted to an inner periphery of an inner ring of the bearing, and the other of the pair constituent members is formed with an annular inner face forming portion fitted to an outer periphery of an outer ring of the bearing, the shaft portion and the annular inner face forming portion cooperatively define a first sealing structure to regulate a flow of a lubricant between inside and outside of the bearing, and wherein the first sealing structure includes a labyrinth structure."
  ],
  "description_excerpt": "1. Field of the Invention\n\nThe present invention relates to a parallel link mechanism which can operate in a precise and wide operating range in a three-dimensional space, and relates to a constant velocity universal joint and a link actuator each equipped with the parallel link mechanism and used in a medical device, an industrial device, or the like.\n\n2. Description of Related Art\n\nOne example of a working device equipped with a parallel link mechanism is disclosed in Patent Document 1, one example of a constant velocity universal joint which performs power transmission between two shafts is disclosed in Patent Document 2, and one example of a link actuator used in a medical device, an industrial device, or the like is disclosed in Patent Document 3.\n\nIn the parallel link mechanism of Patent Document 1, the operation angle of each link is small. Therefore, in order to increase the operating range of the travelling plate, the parallel link mechanism is required to have an increased link length. Accordingly, a problem has been found that the dimensions of the mechanism as a whole increase and the apparatus tends to be bulky in size. Also, if the link length is increased, the rigidity of the mechanism as a whole tends to be lowered. For this reason, there has also been a problem that the weight of a tool mounted on the travelling plate, that is, the weight capacity of the travelling plate, is limited to a small value.",
  "cpc": [
    "F16D 3/30",
    "B25J 11/00",
    "B25J 19/0062",
    "B25J 3/00",
    "B25J 9/0048",
    "B25J 9/108",
    "F16C 19/06",
    "F16C 19/163",
    "F16C 19/26",
    "F16C 19/46",
    "F16C 19/543",
    "F16C 33/6674",
    "F16C 33/80",
    "F16D 3/84",
    "F16H 21/46",
    "F16H 21/48",
    "Y10S 464/905",
    "Y10T 74/20335"
  ],
  "ipc": [
    "B25J 17/00",
    "B25J 19/00",
    "B25J 9/00",
    "B25J 9/10",
    "F16D 3/30",
    "F16H 21/46"
  ],
  "assignees": [
    "NTN Corp"
  ],
  "inventors": [
    "Hiroshi Isobe",
    "Hiroyuki Yamada",
    "Keisuke Sone"
  ],
  "filing_date": "2012-10-30",
  "publication_date": "2016-04-19",
  "grant_date": "2016-04-19",
  "priority_date": "2011-11-04",
  "application_number": "US-201214352005-A",
  "family_id": "50997506",
  "cited_by_count": 8,
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}