Internally engaged planetary gear device and robot joint device
An internally engaged planetary gear device includes a bearing member, an internally toothed gear, a planetary gear, a plurality of inner pins, and a plurality of rolling bearings. When respectively inserted into a plurality of inner pin holes formed in the planetary gear, the plurality of inner pins are configured to rotate relative to the internally toothed gear while revolving in the inner pin holes. The plurality of rolling bearings are configured to hold respective inner pins of the plurality of inner pins at two sides in a direction parallel to a rotation axis Ax 1 with respect to the planetary gear. Each inner pin of the plurality of inner pins is configured to be held on each rolling bearing in a state capable of rotation.
1. An internal-meshing planetary gear device, comprising:
a bearing member, provided with an outer ring, and an inner ring arranged on an inner side of the outer ring and supported to be rotatable relative to the outer ring with a rotation axis as a center;
an internally toothed gear, provided with internal teeth and fixed to the outer ring;
a planetary gear, provided with external teeth partially meshing with the internal teeth; and
a plurality of inner pins, configured to revolve in a plurality of inner pin holes formed in the planetary gear and configured to rotate relative to the internally toothed gear, in a state where the plurality of inner pins are inserted into the plurality of inner pin holes respectively, and
a plurality of sets of rolling bearings configured to hold each of the plurality of inner pins at both sides of the planetary gear in a direction parallel to the rotation axis,
wherein each of the plurality of inner pins is held on each corresponding set of rolling bearings in a self-rotatable state.
2. The internal-meshing planetary gear device of claim 1 , further comprising:
an inner-side bearing member configured to keep an eccentric shaft which allows the planetary gear to swing eccentrically, and configured to be rotatable relative to the inner ring,
at least a part of the plurality of sets of rolling bearings arranged at a same position as the inner-side bearing member, in the direction parallel to the rotation axis.
3. The internal-meshing planetary gear device of claim 1 , wherein an inner peripheral surface of each of the plurality of inner pin holes is configured to press against each corresponding inner pin of the plurality of inner pins to apply a pre-pressure to each corresponding inner pin of the plurality of inner pins, when the plurality of inner pins do not rotate relative to the internally toothed gear.
4. The internal-meshing planetary gear device of claim 3 , wherein the pre-pressure is applied by a bending moment generated from each of the plurality of inner pins.
5. The internal-meshing planetary gear device of claim 1 , wherein each of the plurality of sets of rolling bearings comprises a plurality of rolling bodies,
the plurality of rolling bodies are configured to press against each of the plurality of inner pins, to apply an inner pin-side pre-pressure to each of the plurality of inner pins.
6. The internal-meshing planetary gear device of claim 1 , wherein the plurality of sets of rolling bearings are arranged at equal intervals along a circumferential direction around the rotation axis along the direction parallel to the rotation axis.
7. The internal-meshing planetary gear device of claim 1 , wherein a center of a virtual circle passing through centers of the plurality of sets of rolling bearings is consistent with the rotation axis, along the direction parallel to the rotation axis.
8. A joint device for a robot, comprising:
the internal-meshing planetary gear device comprising:
a bearing member, provided with an outer ring, and an inner ring arranged on an inner side of the outer ring and supported to be rotatable relative to the outer ring with a rotation axis as a center;
an internally toothed gear, provided with internal teeth and fixed to the outer ring;
a planetary gear, provided with external teeth partially meshing with the internal teeth; and
a plurality of inner pins, configured to revolve in a plurality of inner pin holes formed in the planetary gear and configured to rotate relative to the internally toothed gear, in a state where the plurality of inner pins are inserted into the plurality of inner pin holes respectively, and
a plurality of sets of rolling bearings configured to hold each of the plurality of inner pins at both sides of the planetary gear in a direction parallel to the rotation axis,
wherein each of the plurality of inner pins is held on each corresponding set of rolling bearings in a self-rotatable state;
a first member fixed to the outer ring; and
a second member fixed to the inner ring.
9. The joint device for the robot of claim 8 , further comprising:
an inner-side bearing member configured to keep an eccentric shaft which allows the planetary gear to swing eccentrically, and configured to be rotatable relative to the inner ring,
at least a part of the plurality of sets of rolling bearings arranged at a same position as the inner-side bearing member, in the direction parallel to the rotation axis.
10. The joint device for the robot of claim 8 , wherein an inner peripheral surface of each of the plurality of inner pin holes is configured to press against each corresponding inner pin of the plurality of inner pins to apply a pre-pressure to each corresponding inner pin of the plurality of inner pins, when the plurality of inner pins do not rotate relative to the internally toothed gear.
11. The joint device for the robot of claim 10 , wherein the pre-pressure is applied by a bending moment generated from each of the plurality of inner pins.
12. The joint device for the robot of claim 8 , wherein each of the plurality of sets of rolling bearings comprises a plurality of rolling bodies,
the plurality of rolling bodies are configured to press against each of the plurality of inner pins, to apply an inner pin-side pre-pressure to each of the plurality of inner pins.
13. The joint device for the robot of claim 8 , wherein the plurality of sets of rolling bearings are arranged at equal intervals along a circumferential direction around the rotation axis along the direction parallel to the rotation axis.
14. The joint device for the robot of claim 8 , wherein a center of a virtual circle passing through centers of the plurality of sets of rolling bearings is consistent with the rotation axis, along the direction parallel to the rotation axis.