Metering dispenser for aerosol with fluid pressure operated piston

Claim 1

A DISPENSING DEVICE FOR DELIVERING METERED QUANTITIES OF AN AEROSOL COMPOSITION, WHICH COMPRISES A CYLINDRICAL CHAMBER ADAPTED TO BE SEALED INTO THE NECK OF A CONTAINER, AN ELASTIC SEALING WASHER AT THE OUTER END OF SAID CHAMBER CLOSING THE CHAMBER WITH RESPECT TO THE CONTAINER, SAID CHAMBER HAVING AN INLET AT THE INNER END THEREOF FOR COMMUNICATION WITH THE INTERIOR OF THE CONTAINER AND HAVING A SEALING RING DISPOSED CIRCUMFERENTIALLY OF THE INTERIOR SURFACE OF THE SIDE WALL OF THE CHAMBER AT A POINT INTERMEDIATE THE INNER AND OUTER ENDS OF THE CHAMBER, A PISTON MEMBER DISPOSED WITHIN SAID CHAMBER SO AS TO BE RECIPROCABLE THEREIN IN SEALING ENGAGEMENT AROUND THE SIDES THEREOF WITH SAID SEALING RING, A DISCHARGE TUBE MOUNTED IN SAID SEALING WASHER AND EXTENDING THERETHROUGH AND ENGAGABLE WITH SAID PISTON MEMBER AND ADAPTED TO BE SEALED THEREBY, SAID DISCHARGE TUBE BEING RESILIENTLY BIASSED IN AN OUTWARD DIRECTION AND BEING MOVABLE AXIALLY OF THE CHAMBER SO AS, IN ONE DIRECTION OF MOVEMENT, TO DEPRESS THE PISTON MEMBER TO A POSITION IN WHICH THE PISTON MEMBER IS PAST THE SEALING RING AND IS NO LONGER SEALED BY SAID SEALING RING, AND IN THE OTHER DIRECTION TO BE SEPARABLE FROM THE PISTON MEMBER AFTER THE PISTON MEMBER HAS ENGAGED THE SEALING RING AND HAS BEEN SEALED THEREBY, WHEREBY THE METERED QUANTITY OF LIQUID IN THE OUTER PART OF THE CHAMBER IS PUMPED THERETHROUGH TO THE ATMOSPHERE BY FURTHER OUTWARD MOVEMENT OF THE PISTON MEMBER UNDER THE PRESSURE DIFFERENTIAL ON OPPOSITE SIDES OF THE PISTON MEMBER.