A movable lid is mounted to a valve body movably in an up-and down direction toward and away from the valve body whereby the valve body is lowered to be open against force of a spring by pressing a suction nozzle of an electric vacuum cleaner onto the movable lid and at the same time an exhaust of a...http://www.google.es/patents/US6712334?utm_source=gb-gplus-sharePatente US6712334 - Exhaust valve for a bag
