Patent ID: 8121658

Claim:
An elastic device comprising: a torsion spring including a spiral part wound while making a spiral shape without a vertical overlapping portion of the spiral part; an arm member connected with the inner end of the spiral part, the arm member changing a degree of winding of the spiral part depending on a rotational angle with respect to the torsion spring and being provided with elastic force caused by torsion moment corresponding to the degree of winding of the spiral part, wherein the arm member is fixedly connected with the inner end of the spiral part and has a connection part for rotatably connecting with an associated member of the connection part, and wherein the arm member has a first sheet member and a second sheet member facing each other and one end of the torsion spring is located in an interval formed between the first sheet member and the second sheet member, the second sheet member being fixed to the first sheet member; a gap is formed at one of the first sheet member and the second sheet member so that one end of the torsion spring can be inserted into the gap, and a torsion spring connecting protrusion is formed at both sides of the gap in such a manner that the torsion spring connecting protrusion is pressed toward an interior so as to protrude; and one end or the other end of the torsion spring is engaged with the gap so as to be connected with the arm member.