Terminal connecting structure and female terminal

1. A terminal connecting structure comprising:

a male terminal having a plated columnar rod portion;

a female terminal having a cylindrical portion defining cavity configured to receive the rod portion of the male terminal therein; and

an elastic member attached to the cylindrical portion of the female terminal,

wherein the elastic member energizes the rod portion of the male terminal toward a central portion of an inner surface of the cylindrical portion when the rod portion of the male terminal is inserted into the cylindrical portion of the female terminal;

wherein the female terminal has a plurality of projection portions protruding inward from respective regions located at only both sides of the central portion of the inner surface of the cylindrical portion as seen from a front view; and

wherein a tip end of each of the plurality of projection portions has a curved surface which is inwardly concave toward the cavity defined by the cylindrical portion according to a circumferential shape of the rod portion of the male terminal.

2. The terminal connecting structure according to claim 1 , wherein a radius of curvature of the curved surface of the tip end of each of the projection portion is larger than a radius of curvature of a circumferential surface of the rod portion of the male terminal in a cross section orthogonal to an axis of the cylindrical portion.

3. The terminal connecting structure according to claim 1 , wherein the elastic member includes two half-ring-shaped frame members spaced apart from each other and located on a tip end side and a rear end side of the cylindrical portion, and includes a plurality of plate springs curved inward of the cylindrical portion and connecting the two frame members;

wherein the plurality of projection portions include two or more projection portions provided at the tip end side and the rear end side of the cylindrical portion respectively; and

wherein the frame member on the rear end side is in contact with or close to the projection portion on the rear end side of the cylindrical portion of the female terminal.

4. The terminal connecting structure according to claim 3 , wherein a width of the projection portions provided at the tip end side is larger than that of the projection portions provided at the rear end side in a peripheral direction of the cylindrical portion.

5. The terminal connecting structure according to claim 1 , wherein a front end face of the cylindrical portion has a groove extending toward an outer side of the cylindrical portion while expanding a width of the groove;

wherein the elastic member has a tongue piece with a shape matching with the groove; and

wherein the tongue piece is configured to be fit in the groove.

6. A female terminal comprising:

a cylindrical portion defining a cavity configured to receive a plated columnar rod portion of a male terminal; and

a plurality of projection portions protruding inward from respective regions located at only both sides of a central portion of an inner surface of the cylindrical portion as seen from a front view,

wherein when an elastic member is attached to the cylindrical portion of the female terminal and the rod portion of the male terminal is inserted into the cylindrical portion of the female terminal, the elastic member energizes the rod portion of the male terminal toward the central portion of the inner surface of the cylindrical portion; and

wherein a tip end of each of the plurality of projection portions has a curved surface which is inwardly concave toward the cavity defined by the cylindrical portion according to a circumferential shape of the rod portion of the male terminal.

7. A terminal connecting structure comprising:

a male terminal having a plated columnar rod portion;

a female terminal having a cylindrical portion configured to receive the rod portion of the male terminal therein; and

an elastic member attached to the cylindrical portion of the female terminal,

wherein the elastic member energizes the rod portion of the male terminal toward an inner surface of the cylindrical portion when the rod portion of the male terminal is inserted into the cylindrical portion of the female terminal;

wherein the female terminal has a plurality of projection portions protruding inward from respective regions located at both sides of a central portion of the inner surface of the cylindrical portion as seen from a front view,

wherein a tip end of each of the plurality of projection portions has a curved surface which is concave toward an outer side of the cylindrical portion,

wherein the elastic member includes two half-ring-shaped frame members spaced apart from each other and located on a tip end side and a rear end side of the cylindrical portion, and includes a plurality of plate springs curved inward of the cylindrical portion and connecting the two frame members,

wherein the plurality of projection portions include two or more projection portions provided at the tip end side and the rear end side of the cylindrical portion respectively, and

wherein the frame member on the rear end side is in contact with or close to the projection portion on the rear end side of the cylindrical portion of the female terminal.

8. The terminal connecting structure according to claim 7 , wherein a width of the projection portions provided at the tip end side is larger than that of the projection portions provided at the rear end side in a peripheral direction of the cylindrical portion.