Pressure controlled valve

1 . A medical valve comprising:

a housing forming a first port, a second port, and a control port configured to receive an externally applied positive and/or negative control pressure;

a fluid channel within the housing between the first port and the second port; and

a normally non-flat diaphragm at least partly within the housing and configured to isolate the control port from the fluid channel, first port, and the second port,

the diaphragm having an exposed surface area,

the diaphragm configured to control fluid flow through the fluid channel in response to four forces including:

i) a first force generated on the diaphragm from a differential fluid pressure between the first port and the control port times the exposed surface area of the diaphragm,

ii) a second force generated on the diaphragm from a differential fluid pressure between the second port and the control port times the exposed surface area of the diaphragm,

iii) a third force generated by elastic deformation of the diaphragm, and

iv) a fourth force generated by a pressure drop due to fluid flow in the fluid channel due to the Venturi effect.

2 . The medical valve as defined by claim 1 wherein the housing comprises two separate pieces coupled together to form the fluid channel and at least partly encapsulate the diaphragm.

3 . The medical valve as defined by claim 1 wherein the diaphragm is configured so that an increase in inlet force increases fluid flow resistance through the fluid channel, the increased fluid flow resistance causing the fluid channel to be self-regulating to produce a regulated fluid flow rate.

4 . The medical valve as defined by claim 3 wherein the fluid channel includes an interior opening with an inner dimension, further wherein the diaphragm has a stem extending through the interior opening, the stem having an outer dimension, the stem outer dimension being smaller than the interior opening inner dimension, the stem configured to selectively occlude fluid flow through the fluid channel.

5 . The medical valve as defined by claim 1 wherein the diaphragm is biased closed with the diaphragm in compression.

6 . The medical valve as defined by claim 5 wherein the housing has a valve seat surrounding a given portion of the fluid channel, further wherein the diaphragm has a sealing portion extending into the fluid channel and normally seated against the valve seat and surrounding the given portion of the fluid channel, the fluid channel being closed when the sealing portion is seated against the valve seat.

7 . The medical valve as defined by claim 1 wherein the diaphragm forms a fluid-tight barrier separating (i) a control chamber in fluid communication with the control port from (ii) the fluid channel, such that there is no fluidic communication between the control chamber and the fluid channel.

8 . The medical valve as defined by claim 1 wherein the valve has an open mode and a closed mode, the diaphragm having a normally convex portion with a convex surface in fluid communication with the control port, the normally convex portion forming a concave surface in fluid communication with the fluid channel, the concave surface configured to have an increasing radius as the valve moves toward the open mode, the normally convex portion forming a pre-load bias toward the closed mode.

9 . The medical valve as defined by claim 1 wherein the flow resistance of the fluid channel between the first port and the second port changes non-linearly with the displacement of the diaphragm.

10 . The medical valve as defined by claim 1 wherein the first and second fluid ports are substantially in-line.

11 . A medical valve comprising:

a housing forming first means for porting fluid, second means for porting fluid, and controlling means for receiving a positive or negative pressure;

channeling means for channeling fluid within the housing between the first porting means and the second porting means; and

sealing means configured to isolate the pressure means from the channeling means, the first porting means and the second porting means, the sealing means having a sealing means force,

the sealing means configured to control fluid flow through the channeling means in response to four forces including:

i) a first force generated on the sealing means from a differential fluid pressure between the first porting means and the controlling means times the exposed surface area of the sealing means,

ii) a second force generated on the sealing means from a differential fluid pressure between the second porting means and the controlling means times the exposed surface area of the sealing means,

iii) a third force generated by elastic deformation of the sealing means, and

iv) a fourth force generated by a pressure drop due to fluid flow in the fluid channel due to the Venturi effect.

12 . The medical valve as defined by claim 11 wherein the sealing means is configured so that an increase in inlet force increases fluid flow resistance through the channeling means, the increased fluid flow resistance causing the channeling means to be self-regulating to produce a regulated fluid flow rate.

13 . The medical valve as defined by claim 12 wherein the channeling means includes stem receiving means with an inner dimension, further wherein the sealing means has a stem extending through the stem receiving means, the stem having an outer dimension, the stem outer dimension being smaller than the stem receiving means inner dimension, the stem configured to selectively occlude fluid flow through the channeling means.

14 . The medical valve as defined by claim 11 wherein the sealing means is biased closed with the sealing means in tension.

15 . The medical valve as defined by claim 11 wherein the housing has a valve seat surrounding a given portion of the channeling means, further wherein the sealing means has a sealing portion extending into the channeling means and normally seated against the valve seat and surrounding the given portion of the channeling means, the channeling means being closed when the sealing portion is seated against the valve seat.

16 . A method of controlling fluid flow through a valve, the method comprising:

coupling tubing to a first port and to a second port of a housing of a closed valve, the housing forming a fluid channel between the first port and the second port;

managing, via a control port configured to an externally applied positive and/or negative control pressure, a bias of a diaphragm having a shaped surface, the diaphragm positioned in the housing to isolate the control port from the fluid channel, first port, and the second port;

applying a differential pressure between the first and second ports; and

applying a control pressure to the control port to change the sealing force of the diaphragm, applying comprising producing fluid flow through the fluid channel as the diaphragm moves from a fully closed position to a partially opened position, and further to a fully open position.

17 . The method as defined by claim 16 wherein managing the diaphragm bias comprises applying a positive pressure to the diaphragm via the control port.

18 . The method as defined by claim 16 wherein managing the diaphragm bias comprises applying a negative pressure to the diaphragm via the control port.

19 . The method as defined by claim 16 further comprising increasing inlet force via the first port to increase fluid flow resistance through the flow channel, the increased fluid flow resistance causing the fluid channel to be self-regulating to produce a regulated fluid flow rate.

20 . The method as defined by claim 16 wherein the diaphragm is biased closed with the diaphragm in tension.

21 . The method as defined by claim 16 wherein the valve has an open mode and a closed mode, the diaphragm having a normally convex portion with a convex surface in fluid communication with the control port, the normally convex portion forming a concave surface in fluid communication with the fluid channel, the concave surface configured to have an increasing radius as the valve moves toward an open mode, the normally convex portion forming a pre-load bias toward the closed mode,

the method further controlling the diaphragm to move toward an open mode, controlling comprising increasing the radius of the concave surface against the pre-load bias.

22 . The method as defined by claim 16 wherein fluid flow through the fluid channel is controlled in response to four forces including:

i) a first force generated on the diaphragm from a differential fluid pressure between the first port and the control port times the exposed surface area of the diaphragm,

ii) a second force generated on the diaphragm from a differential fluid pressure between the second port and the control port times the exposed surface area of the diaphragm,

iii) a third force generated by elastic deformation of the diaphragm, and

iv) fourth force generated by a reduced static pressure at a throat of a Venturi section of the fluid channel, the Venturi sect on comprising a converging region, the throat, and a diverging region, the reduced static pressure being generated during fluid flow through the throat.