Needle free medical connector with expanded valve mechanism and method of fluid flow control

1. A medical fluid connector configured to allow fluid to flow through the connector when a cannula is inserted into the connector, the connector comprising:

a housing including a first port sized to receive the cannula, a second port, a first inner housing portion adjacent the first port and having a first internal diameter, and a second inner housing portion having a second internal diameter greater than the first internal diameter; and

a moveable element providing a fluid passageway through the moveable element connecting the cannula and the second port of the housing, the moveable element disposed within the housing to contact the cannula as the cannula is inserted into the housing, the moveable element being moveable between a first position in which the cannula has not been inserted into the housing and a second position in which the cannula has been inserted into the housing, the moveable element having:

a head element moveable in an axial direction away from the first port in response to insertion of the cannula into the housing;

a compressible section having a first wall element, a second wall element, and a variable internal volume between the first and second wall elements, the compressible section configured to self-expand from a compressed configuration to an expanded configuration, the first and second wall elements being spaced farther apart when the compressible section is in the expanded configuration, the compressible section being moveable to a location adjacent the second inner housing portion when the moveable element is in the first position, the compressible section being moveable to a location away from the second inner housing portion when the moveable element is in the second position, the compressible section comprising a plurality of flexible membrane elements that connect the first wall elements to the second wall elements, the first wall elements and the second wall elements being relatively inflexible;

wherein when the moveable element is in the first position, the second inner housing portion wall applies a radially compressive force to the compressible section sufficient to move the first wall element toward the second wall element; and

wherein when the moveable element is in the second position, the compressible section self-expands during which the first wall element moves away from the second wall element.

2. The connector cf claim 1 wherein the fluid passageway has a passageway length that extends axially and that decreases when the moveable element is moved from the first position to the second position.

3. The connector of claim 2 wherein the fluid passageway defines a fluid path volume, and when the moveable element moves to the second position, the first and second wall elements of the compressible section are configured to move apart by a selected width so that the fluid path volume stays the same, thereby creating a neutral-bolus effect.

4. The connector of claim 2 wherein the fluid passageway defines a fluid path volume, and when the moveable element moves to the second position, the first and second wall elements of the compressible section are configured to move apart by a selected width so that the fluid path volume increases, thereby creating a positive-bolus effect.

5. The connector of claim 1 wherein the inner conduit of the compressible section has a length that extends axially and that remains substantially constant under the radially compressive force.

6. The connector of claim 1 wherein the head includes a normally open bore and a moveable shoulder aijacent the bore;

wherein when the moveable element is in the first position, the shoulder contacts the first inner housing portion and the bore is closed to fluid flow; and

wherein when the moveable element is in the second position, the bore self-opens to allow fluid flow.

7. The connector of claim 1 wherein the moveable element further comprises a spring section disposed between the compressible section and the second port of the housing, the spring section configured to axially contract, the spring section forming a part of the fluid passageway;

wherein when the moveable element is in the first position, the spring section has a first spring section internal volume; and

wherein when the moveable element is in the second position, the spring section has a second spring section internal volume greater than the first spring section internal volume.

8. The connector of claim 7 wherein the fluid passageway defines a fluid path volume, and when the moveable element moves to the second position, the increase in the spring section internal volume adds to the fluid path volume.

9. The connector of claim 1 wherein the first and second wall elements are connected to each other by a fiexible element, the first and second wall elements being stiffer than the flexible element.

10. The connector of claim 9 wherein the flexible element folds into a space between the first and second wall elements.

11. A medical fluid connector configured to allow fluid to flow through the connector when a cannula is inserted into the connector, the connector comprising:

a housing including a first port sized to receive the cannula, a second port, a first inner housing portion adjacent the first port and having a first internal diameter, and a second inner housing portion having a second internal diameter greater than the first internal diameter; and

a moveable element providing a fluid passageway through the moveable element connecting the cannula and the second port of the housing, the moveable element disposed within the housing to contact the cannula as the cannula is inserted into the housing, the moveable element being moveable between a first position in which the cannula has not been inserted into the housing and a second position in which the cannula has been inserted into the housing, the moveable element having:

a compressible section having a first wall element, a second wall element, and a variable internal volume between the first and second wall elements, the compressible section configured to self-expand from a compressed configuration to an expanded configuration, the first and second wall elements being spaced farther apart when the compressible section is in the expanded configuration, the compressible section being moveable to a location adjacent the second inner housing portion when the moveable element is in the first position, the compressible section being moveable to a location away from the second inner housing portion when the moveable element is in the second position, the compressible section comprising a plurality of flexible membrane elements that connect the first wall elements to the second wall elements, the first wall elements and the second wall elements being relatively inflexible; and

a spring section disposed between the compressible section and the second port of the housing, the spring section configured to axially contract, the spring scetion forming a part of the fluid passageway;

wherein when the moveable element is in the first position, the spring section has a first spring section internal volume and the second inner housing portion wall applies a radially compressive force to the compressible section sufficient to move the first wall element toward the second wall element; and

wherein when the moveable element is in the second position, the spring section has a second spring section internal volume greater than the first spring section internal volume and the compressible section self-expands during which the first wall element moves away from the second wall element.

12. The connector of claim 11 wherein the fluid passageway has a passageway length that extends axially and that decreases when the moveable element is moved from the first position to the second position.

13. The connector of claim 12 wherein the fluid passageway defines a fluid path volume, and when the moveable element moves to the second position, the first and second wall elements of the compressible section are configured to move apart by a selected width so that the fluid path volume stays the same, thereby creating a neutral-bolus effect.

14. The connector of claim 12 wherein the fluid passageway defines a fluid path volume, and when the moveable element moves to the second position, the first and second wall elements of the compressible section are configured to move apart by a selected width so that the fluid path volume increases, thereby creating a positive-bolus effect.

15. The connector of claim 11 wherein the inner conduit of the compressible section has a length that extends axially and that remains substantially constant under the radially compressive force.

16. The connector of claim 11 wherein the moveable element further comprises a head moveable in an axial direction away from the first port in response to insertion of the cannula into the housing, the head having a normally open bore and a moveable shoulder adjacent the bore;

wherein when the moveable element is in the first position, the shoulder contacts the first inner housing portion and the bore is closed to fluid flow; and

wherein when the moveable element is in the second position, the bore self-opens to allow fluid flow.

17. The connector of claim 11 wherein the fluid passageway defines a fluid path volume, and when the moveable element moves to the second position, the increase in the spring section internal volume adds to the fluid path volume.

18. The connector of claim 11 wherein the flexible element folds into a space between the first and second wall elements.