Capacitor for high vibration environments having a controlled gas reservoir

摘要

An electrolytic capacitor capable of withstanding high vibration environments includes a cylindrical capacitor case having an open end and a closed end, and cylindrically rolled alternate wraps of electrolyte impregnated paper and metal foil films with tabs abutting the foil films to electrically connect each of the foil films to a terminal. With the paper film on the outside of the cylindrical roll, the roll's outside diameter is tightly controlled to provide a snug fit when inserted in the case while the inside diameter of the roll is sized to provide a cylindrical volume in cubic inches equal to approximately 1.2 times the actual capacitance in farads times the desired rated voltage in volts so as to prevent a large pressure rise due to gas generation during capacitor operation. The paper films are axially longer than the other films towards the open end of the case while one of the foil films is axially longer towards the closed end of the case than the other films. When a cap and seal assembly is forced into the case to seal the open end, the terminals extend through the cap with one insulated and the other uninsulated from the cap. At the same time, the paper films are crushed against the cap to prevent flexing of the tabs between the foil films and the cap while the long foil film which is connected to the uninsulated terminal is crushed against the closed end of the capacitor case to allow heat transfer between the foil and the case.