| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a hermetically sealed square battery which is designed to have its cleavage vent actuated by a low working pressure, so that it excels in impact durability when, for example, the battery is dropped. <P>SOLUTION: A hermetically sealed square battery includes a laterally long lid which covers an open top face of a battery can and a cleavage vent having a thin wall valve body, disposed on the lid, which cleaves when the internal pressure of the battery rises abnormally. In the battery, the cleavage vent has an elliptically shaped peripheral groove formed inside an elliptically shaped coining part on an outer surface side of the lid and close to either end in the lateral direction of the lid and a thin wall valve body surrounded therewith. The elliptically shaped peripheral groove is composed of long sided thin film portions parallel to the longer direction of the lid and arcuate thin wall portions connecting these long sided portions, where the thin wall portion of the long sided portion on one side, the thin wall portion of the long sided portion on the other side and the thin wall valve body of the cleavage vent have their wall thicknesses thickened in that order. <P>COPYRIGHT: (C)2013,JPO&INPIT |
