Torque sensor
This torque sensor includes: an outer circumferential part and an inner circumferential part that have an annular shape and are disposed concentrically with a gap therebetween in the radial direction thereof; a plurality of double-supported beam-like connecting beam parts that are disposed with gaps therebetween in the circumferential direction and connect the outer circumferential part and the inner circumferential part; and detecting parts that detect the torque applied about a central axis to the outer circumferential part and the inner circumferential part, wherein both side surfaces of the connecting beam parts in the circumferential direction have concave curved shapes the respective radii of curvature of which gradually increase from the inner circumferential surface of the outer circumferential part and the outer circumferential surface of the inner circumferential part toward the center in the length direction of the connecting beam parts when seen in the direction of the central axis.
1 . A torque sensor comprising:
an annular outer circumferential part and an annular inner circumferential part that are disposed concentrically with a gap therebetween in a radial direction;
a plurality of double-supported-beam-like connecting beam parts disposed with a gap therebetween in a circumferential direction and connecting the outer circumferential part and the inner circumferential part to each other; and
a detecting part that detects torque applied around a center axis between the outer circumferential part and the inner circumferential part,
wherein, when viewed from a direction of the center axis, opposite side surfaces of each connecting beam part in the circumferential direction each have a concave curved shape with a radius of curvature that gradually increases from an inner circumferential surface of the outer circumferential part and an outer circumferential surface of the inner circumferential part toward a center in a length direction of the connecting beam part,
wherein the curved shape is constituted of a portion of an ellipse whose major axis is disposed parallel to the length direction of the connecting beam part, and
wherein the ellipse has an ellipticity that is greater than 0% and smaller than or equal to 57%.
2 . The torque sensor according to claim 1 , wherein the curved shape belonging to each side surface of the connecting beam part in the circumferential direction and extending from the outer circumferential part to the inner circumferential part is constituted of a portion of a single ellipse.
3 . The torque sensor according to claim 1 , wherein, in each side surface of the connecting beam part in the circumferential direction, the curved shape extending from the inner circumferential surface of the outer circumferential part toward the center in the length direction of the connecting beam part and the curved shape extending from the outer circumferential surface of the inner circumferential part toward the center in the length direction of the connecting beam part are different from each other.
4 . The torque sensor according to claim 1 , wherein the ellipse has an ellipticity that ranges between 20% and 55% inclusive.