| 摘要 |
PROBLEM TO BE SOLVED: To cut off electric current by bursting the fragile part under specified pressure or more, to secure stability of a battery from heating and explosion, and to easily and accurately set working pressure of the fragile part by forming the mechanically fragile part on one side of a circuit breaker. SOLUTION: A circuit breaker 82 has a fixing part welded to the under side of a plate 14 and a notch 820 of the fragile part for bursting under prescribed pressure or more on the periphery. The plate 14 having a safety valve is pushed up by an increase in internal pressure of a secondary battery, and when the pressure becomes a specified value or more the notch 820 of the circuit breaker 82 will burst. At this time, since the circuit breaker 82 is firmly welded to the plate 14, the mechanically weak notch 820 bursts, and separates from the other part to cut off an electric current. Here, the notch 820 bursts under specific level pressure or less for pushing up the plate 14 and is formed so as to burst under battery internal pressure of 7 to 15 kgf/cm2. |
