Breastpump having improved valve mechanism

In a breastpump comprising a hood body for placement over a breast, the hood body having a main funnel-shaped portion within which the breast is received and a tubular extension extending downstream from the main funnel portion, means for connecting the tubular extension of the hood body with a vacuum line to periodically withdraw air from the hood body in a manner that draws the breast into the main funnel portion and thereby expresses milk from the breast into the tubular extension, the vacuum line connecting means including a sleeve having interior threads to which a vacuum pump is threadably attached in an airtight engagement, said sleeve threads being broken in places, a catch chamber for expressed milk connected with the tubular extension, the catch chamber being located downstream from the tubular extension and having an inlet and an outlet which outlet communicates with a container to which the breastpump is attached in an airtight fit via a collared cap, the improvement comprising:

• a valve mechanism having a housing including an upper portion removably attachable to said catch chamber outlet and a lower portion having a first widened opening defined through said lower portion adjacent a bottom to said lower portion through which first widened opening milk can pass, and a thin flexible membrane sized to cover and close said first widened opening when a negative pressure is applied within said housing and allow milk to pass through said first widened opening when said negative pressure is removed, said thin flexible membrane being generally circular in shape and removably mounted to said lower portion by a knob formed integral with and at the center of said membrane, which knob is inserted into a second opening defined in said lower portion in a snap fit, said thin flexible membrane having bosses located on the side of the membrane that is outboard to said lower portion, said bosses overlying said first and widened opening and being of sufficient size to reinforce said thin flexible membrane to prevent said thin flexible membrane from being drawn into said first opening when said negative pressure is applied inside said housing member, and
• a closed airflow path provided in said breastpump for forcibly moving said thin flexible membrane away from said first opening and purging milk from said lower portion, said airpath extending from the vacuum line through the tubular extension and catch chamber into said valve mechanism, then through said first opening into the container, then through a passageway in the cap extending between the cap and the sleeve, and out from the sleeve through the broken threads.