PRESSURE-DISCHARGED VENTING SYSTEM FOR RECHARGABLE BATTERY

摘要

A vent system for a secondary battery is provided to ensure accurate opening/closing operation of a piston, thereby preventing an increase in the internal pressure of a battery and degradation of the efficiency of a battery, and to allow complete sealing at a gas discharge portion. A vent system provided in a cap assembly of a secondary battery comprises: a vent housing(10) including a space for receiving parts with a top opening, and having a gas inlet(11) formed at the lower part therein and communicating with the inner part of the battery; a vent cap(20) coupled to the top opening of the vent housing and having at least one gas discharge port(25); a piston(31) received movably along the longitudinal direction in the space, and having a central retention shaft(31b) with such a length that the piston passes through the gas inlet at the whole positions in the longitudinal direction; a spring(33) interposed between the vent cap and the piston for pressurizing the piston downwardly; and a packing(35) coupled to the central retention shaft for opening/closing the gas inlet.