Cup case for capacitor - has wall containing slot forming weak zone that bursts if internal pressure exceeds specified value

摘要

The case is made of a deformable material, pref. aluminium. In the wall (1) of the case is a slot (2), with a curved base; and the middle part of the slot (2) is deeper than its two ends (4). The slot (2) forms a weak zone in the wall (1) of the case; and this zone bursts if and when the vapour pressure of the liq. in the capacitor exceeds a specified value. The longitudinal axis of the slot (2) is pref. parallel with the longitudinal axis of the case (1); and the slot base pref. has a flat section (6) forming a weak zone with a specific thickness. The side walls of the slot pref. taper downwards. The slot is pref. made by placing the cup case on a mandrel and using a punch to press the slot in the wall (1) of the case. The capacitors are of the electrolytic type, and the case bursts at the slot if electrical and/or thermal overloads occur.