| 摘要 |
A safety device for a closed cell, for preventing rupture due to a sudden increase of the inner pressure caused by overcharging and short circuit. The safety device can be manufactured at low cost and comprises a positive plate cap (16) including a pressure-receiving plate (18) constituting an innermost cap, a shield plate (20) constituting an intermediate cap, and a sealing plate (21) constituting an outermost cap. A projection (28) of the pressure-receiving plate (18), in a first flat joining face (27), is joined to a second flat joining face (29) of the shield plate (20), thus forming a central joining part (19). A C-shaped groove (31) is formed around the second flat joining face (29). A strength-weakening groove (32) bending in such a direction in which the groove (32) is opposed to the C-shaped groove (31) is formed surrounded by the C-shaped groove (31). Between both ends (32a) of the strength-weakening groove (32) and portions (31a) away from both ends of the C-shaped groove (31) by predetermined distance, narrow portions (33) to be bent are formed. |
