A battery cover includes first and second cover portions and a coupling portion that is arranged in a position lower than upper surfaces of the first and second cover portions, between the first and second cover portions. The coupling portion includes a connection portion that is fixed to the second cover portion and a hinge portion that is thinner than the connection portion. The hinge portion is provided such that hinge end portions on both sides are thicker than a hinge center portion. Each of the hinge end portions is formed such that a side end surface thereof is a curved surface which is gently inclined from the first cover portion to the second cover portion and that an upper surface thereof is formed into a substantially arc-shaped curved surface which is thinnest in its center and inclined upward to gradually become thicker from the center toward both support ends.
1. A cover comprising:
a first cover portion;
a second cover portion; and
a coupling portion that is arranged in a position lower than upper surfaces of the first cover portion and the second cover portion, between the first cover portion and the second cover portion, wherein
the coupling portion includes a connection portion that is fixed to at least any one of the first cover portion and the second cover portion and a hinge portion that is thinner than the connection portion,
the second cover portion is provided rotatably with respect to the first cover portion using the hinge portion as a supporting point for rotation,
the hinge portion is provided such that hinge end portions on both sides are thicker than a hinge center portion, and
each of the hinge end portions decrease its width from a side of the first cover portion to a side of the second cover portion and is formed such that a side end surface of the hinge end portions is a curved surface which is gently inclined from a side of the first cover portion to a side of the second cover portion and that an upper surface of the hinge end portions is formed into a substantially arc-shaped curved surface which is thinnest in its center and inclined upward to gradually become thicker from the center toward both support ends.
2. The cover of claim 1 , wherein
a dimension of the hinge portion in a coupling direction is 3 mm,
a dimension from an upper surface of the connection portion to a center position of the hinge end portions that are lowest is 0.75 mm,
the side end surface of the hinge end portions are formed into a curved surface such that an amount of shift of inclination between the support end on the side of the first cover portion and the support end on the side of the second cover portion in a width direction falls within a range of 0.2 mm to 0.6 mm, and
the upper surface of the hinge end portions are formed into a curved surface such that a position 0.2 mm to 0.4 mm downward from the upper surface of the connection portion is the support end.
3. The cover of claim 1 , wherein
a dimension of the hinge portion in a coupling direction is 3 mm,
a dimension from an upper surface of the connection portion to a center position of the hinge end portions that are lowest is 0.75 mm,
the side end surface of the hinge end portions are formed into a curved surface such that an amount of shift of inclination between the support end on the side of the first cover portion and the support end on the side of the second cover portion in a width direction is 0.3 mm, and
the upper surface of the hinge end portions are formed into a curved surface such that a position 0.3 mm downward from the upper surface of the connection portion is the support end.