Torque transfer joint and electric motor with worm reduction gear

A torque transmission joint, comprising:

• a first rotating member having first convex portions protruding toward axial one side at a plurality of locations in a circumferential direction on an axial one side surface;
• a second rotating member having second convex portions protruding toward axial other side at a plurality of locations in the circumferential direction on an axial other side surface;
• a coupling having first recess portions which are opened at least on the axial other side surface and with which the first convex portions are respectively engaged to allow relative displacement in the circumferential direction at a plurality of locations in the circumferential direction and second recess portions which are opened at least on the axial one side surface and with which the second convex portions are respectively engaged to allow relative displacement in the circumferential direction at a plurality of locations in the circumferential direction which deviate from the first recess portions in the circumferential direction;
• a first elastic body having a plurality of first elastic pieces pinched in the circumferential direction between the respective first convex portions and the coupling;
• and
• a second elastic body having a plurality of second elastic pieces pinched in the circumferential direction between the respective second convex portions and the coupling, wherein:
• the coupling includes:
• a boss portion having a cylindrical or columnar shape;
• a plurality of arm portions protruding outward in a radial direction from a plurality of circumferential locations on an outer peripheral surface of the boss portion;
• a plurality of first side plate portions which protrude outward in the radial direction from a plurality of circumferential locations on an outer peripheral surface of an axial one side end of the boss portion and connect axial one side ends of a pair of the arm portions adjacent in the circumferential direction in the circumferential direction;
• and
• a plurality of second side plate portions which protrude outward in the radial direction from a plurality of circumferential locations deviating from the first side plate portions in the circumferential direction of an outer peripheral surface of an axial other side end of the boss portion and connect axial other side ends of a pair of the arm portions adjacent in the circumferential direction in the circumferential direction;
• each of the first recess portions is defined by an outer peripheral surface of the boss portion, an axial other side surface of each of the first side plate portions, and circumferential side surfaces of a pair of the arm portions facing each other with axial one side ends connected to each of the first side plate portions;
• and
• each of the second recess portions is defined by the outer peripheral surface of the boss portion, an axial one side surface of each of the second side plate portions, and circumferential side surfaces of a pair of the arm portions facing each other with axial other side ends connected to each of the second side plate portions.