DOSING PUMP FOR LIQUID DISPENSERS

A dispenser for dispensing metered amounts of a viscous liquid includes a liquid reservoir and a pump chamber having an opening in communication with the reservoir. A dispensing orifice is defined in the pump chamber. A pump mechanism is configured with the pump chamber and is movable from a rest position to a pressurizing position upon actuation thereof to pressurize liquid within the pump chamber. A check valve mechanism is disposed in the opening. A sealing member is disposed within the pump chamber to seal the dispensing orifice upon an initial movement of the pump mechanism to its pressurizing position. The sealing member is moveable within the pump chamber upon subsequent further movement of the pump mechanism to its pressurizing position to unseal the dispensing orifice. Upon initial return movement of the pump mechanism to its rest position, the sealing member remains unsealed relative to the dispensing orifice as a partial vacuum is drawn in the pump chamber and then moves to seal the dispensing orifice upon further subsequent movement of the pump mechanism to its rest position.