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

Patent metadata

Field	Value
Publication number	US-9976603-B2
Application number	US-201615067680-A
Country	US
Kind code	B2
Filing date	Mar 11, 2016
Priority date	Nov 4, 2011
Publication date	May 22, 2018
Grant date	May 22, 2018

Abstract

A parallel link mechanism includes 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 has a trinodal structure. Each revolute pair of each of the link mechanisms includes one pair of pair constituent members connected to each other via a bearing. 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.

First claim

What is claimed is:

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, and
wherein each bearing of the revolute pairs has a critical oscillation angle smaller than a maximum value in a range of a bending angle which is defined as an angle between a central axis of the proximal end side link hub and a central axis of the distal end side link hub.

2. The parallel link mechanism as claimed in claim 1 , wherein the critical oscillation angle is smaller than a maximum value of the bending angle obtained in a predetermined work operation.

3. The parallel link mechanism as claimed in claim 1 , wherein the bearing is a deep groove ball bearing, a number of rolling elements of the deep groove ball bearing is represented by Z, and the critical oscillation angle is set to be 2·180/(0.555·Z·π)[deg].

4. The parallel link mechanism as claimed in claim 1 , wherein a number of rolling elements of the bearing is represented by Z, and the critical oscillation angle is set to be 2.180/(0.37·(Z+0.1)·7)[deg].

5. The parallel link mechanism as claimed in claim 1 , wherein a number of rolling elements of the bearing is represented by Z, and the critical oscillation angle is set to be 2·180/(0.544·Z·π)[deg].

6. A constant velocity universal joint comprising the parallel link mechanism as claimed in claim 1 , wherein the proximal end side link hub of the parallel link mechanism is provided with an input shaft, and the distal end side link hub of the parallel link mechanism is provided with an output shaft.

7. The parallel link mechanism as claimed in claim 1 , further comprising a position changing actuator formed in each of two or more link mechanisms of the three or more link mechanisms in the parallel link mechanism to change an angle of at least one revolute pair of the four revolute pairs thereof.

Assignees

• Ntn Toyo Bearing Co Ltd

Inventors

• Sone Keisuke
• Isobe Hiroshi
• Yamada Hiroyuki

Classifications

• Y10T74/20335

  Wrist · CPC title

• F16D3/30 Primary

  in which the coupling is specially adapted to constant velocity-ratio · CPC title

• B25J9/108

  Bearings specially adapted therefor (bearings in general F16C) · CPC title

• F16H21/46

  with movements in three dimensions [3D] · CPC title

• F16C19/46

  with one row or needles · CPC title