Flow control element including elastic membrane with pinholes

A flow control element for controlling the flow of a liquid, the flow control element comprising:

• a tube-like wall section having a first end and a second end, the wall section defining a liquid flow channel extending from the first end to the second end of the wall section;
• and
• a substantially flat membrane connected to the wall section such that the membrane is disposed between the liquid flow channel and an external region located outside of the flow control element,
• wherein the membrane defines a plurality of pinholes that are formed such that when the membrane is subjected to normal atmospheric conditions and the membrane remains undeformed, the plurality of pinholes remain closed to prevent liquid flow between the liquid flow channel and the external region through the membrane, and when the membrane is deformed in response to an applied pressure differential between the liquid flow channel and the external region, the plurality of pinholes open to facilitate liquid flow through the membrane, and
• wherein the plurality of pinholes include a first pinhole and a second pinhole that are formed such that when the membrane is subjected to a first, relatively low applied pressure differential, the first pinhole remains closed and the second pinhole opens to facilitate a first, relatively low liquid flow rate through the membrane, and when the membrane is subjected to a second, relatively high applied pressure differential, both the first pinhole and the second pinhole open to facilitate a second, relatively high liquid flow rate through the membrane.

A flow control element for controlling the flow of a liquid, the flow control element comprising:

• a wall section surrounding a liquid flow channel;
• and
• a substantially flat elastic membrane connected to the wall section and extending across the liquid flow channel,
• wherein the elastic membrane defines a plurality of first pinholes and a plurality of second pinholes,
• wherein said pluralities of first pinholes and second pinholes are formed such that:
• when the membrane is subjected to normal atmospheric conditions, both the first pinholes and the second pinholes remain closed to prevent liquid flow from the liquid flow channel through the membrane,
• when the membrane is subjected to a first, relatively low applied pressure differential, the first pinholes remain closed and the second pinholes open to facilitate a first, relatively low liquid flow rate through the membrane, and
• when the membrane is subjected to a second, relatively high applied pressure differential, both the first pinholes and the second pinholes open to facilitate a second, relatively high liquid flow rate through the membrane.

A method for manufacturing a flow control element, the flow control element including a tube-like wall section surrounding a fluid flow channel, and an elastic membrane integrally formed with the wall section and extending across the fluid flow channel, the method comprising:

• stretching the elastic membrane by applying a tensile force along the radial axis;
• piercing the stretched elastic membrane using a plurality of pins, thereby forming a plurality of pinholes;
• and
• removing the plurality of pins and releasing the tensile force, whereby each of the plurality of pinholes is closed by elastomeric material surrounding said each pinhole and the elastic membrane is subjected to normal atmospheric conditions,
• wherein piercing comprises inserting a first pin having a first diameter into the stretched elastic membrane to form a first pinhole, and inserting a second pin having a second diameter into the stretched elastic membrane to form a second pinhole, wherein the first diameter is smaller than the second diameter.