Link actuating device

1. A link actuating device comprising:

a proximal end side link hub;

a distal end side link hub;

three or more link mechanisms which couples the distal end side link hub with the proximal end side link hub such that a posture of the distal end side link hub can be changed relative to the proximal end side link hub; and

a posture control actuator configured to arbitrarily change the posture of the distal end side link hub relative to the proximal end side link hub, the posture control actuator being provided to each of two or more link mechanisms of the three or more link mechanisms, wherein

each of the link mechanisms includes: a proximal side end link member having one end rotatably coupled to the proximal end side link hub; a distal side end link member having one end rotatably coupled to the distal end side link hub; and an intermediate link member having opposite ends rotatably coupled to other ends of the proximal side and distal side end link members, respectively,

the proximal side end link member has a bent portion and a rotation shaft mounting portion that is fixed to one end of the bent portion and to which a rotation shaft located at an axis of a revolute pair between the proximal end side link hub and the proximal side end link member is mounted, and

at least a part of a gear mechanism configured to transmit rotary motion by the posture control actuator to the proximal side end link member is mounted on the rotation shaft mounting portion and disposed in a space between two virtual planes obtained by extending a radially inner edge and a radially outer edge of the one end of the bent portion in a longitudinal direction of the rotation shaft mounting portion.

2. The link actuating device as claimed in claim 1 , wherein the rotation shaft mounting portion includes two rotation shaft mounting bodies that are disposed so as to oppose each other and to which the rotation shaft is mounted, and the at least a part of the gear mechanism is disposed between these two rotation shaft mounting bodies.

3. The link actuating device as claimed in claim 2 , wherein each of the rotation shaft mounting bodies is composed of a plate-shaped member detachably mounted on the bent portion.

4. The link actuating device as claimed in claim 3 , wherein both or one of the two rotation shaft mounting bodies is formed in a bent shape such that an interval between the two rotation shaft mounting bodies at a location where the rotation shaft is mounted to the two rotation shaft mounting bodies is larger than that at a location where the two rotation shaft mounting bodies are fixed to the bent portion.

5. The link actuating device as claimed in claim 2 , wherein bearings that rotatably support both ends of the rotation shaft are disposed at an outer side in a direction in which the two rotation shaft mounting bodies are aligned.

6. The link actuating device as claimed in claim 1 , wherein the gear mechanism comprises a speed reduction mechanism configured to transmit the rotary motion by the posture control actuator to the proximal side end link member while reducing a speed of the rotary motion.

7. The link actuating device as claimed in claim 1 , further comprising a gear box that accommodates the gear mechanism, wherein

the gear box is fixed to the proximal end side link hub,

the rotation shaft is rotatably supported by the gear box via a bearing,

a driving gear of the gear mechanism is mounted on an input shaft of the gear box coupled to the posture control actuator, and

a driven gear of the gear mechanism is mounted on the rotation shaft.