Lead screw driven reservoir with integral plunger nut and method of using the same

• US 20040176725A1
• Filed: 03/05/2003
• Published: 09/09/2004
• Est. Priority Date: 03/05/2003
• Status: Active Grant

• Current Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Inventors: Talbot, Cary D., Stutz, William H. Jr., Renger, Herman L.
• Granted Patent: US 7,390,314 B2
• Time in Patent Office: Days
• US Class Current: 604/155
• CPC Class Codes: A61M 2005/14573 with a replaceable reservoir for quick connection/disconnection with a driving system
• CPC Class Codes: A61M 5/1456 with a replaceable reservoir comprising a piston rod to be moved into the reservoir, e.g. the piston rod is part of the removable reservoir

Abstract

An improved reservoir is provided for use in a medication infusion device for operating the reservoir to administer a fluid to a patient. The reservoir comprises a hollow barrel adapted to receive a supply of fluid for delivery through infusion tubing or the like to the patient, in combination with a reservoir plunger. The reservoir plunger is designed to engage a motor-driven lead screw of the medication infusion device. The reservoir plunger has an integral split nut connector formed on the end of the plunger, which is in co-axial alignment with the lead screw whereby the split nut connector can be engaged directly to the lead screw

Claims

1. A reservoir for use with a medication infusion device having a rotatable lead screw for controllably dispensing fluid from the reservoir, the reservoir comprising:

a hollow reservoir barrel adapted for receiving and supporting a supply of the fluid; and

a reservoir plunger slidably received into the barrel and movable within the barrel to deliver the fluid from the barrel;

wherein the reservoir plunger has an integral split nut connector formed on a rear end of the plunger adapted for co-axial alignment with the lead screw whereby the split nut connector is adapted to be engaged directly to the lead screw.

2. The reservoir according to claim 1, wherein the reservoir plunger includes at least two legs and the integral split nut connector comprises at least a partial nut formed at the end of each leg of the plunger such that the plunger is adapted to permit the lead screw to fit between the at least two legs and the partial nut on each leg can simultaneously engage the lead screw when the legs are compressed.

3. The reservoir according to claim 2, wherein the partial nuts are engaged to the lead screw by a camming receptacle, wherein the camming receptacle has camming surfaces to press the partial nuts together to form a whole nut over the lead screw when the plunger is twisted within the camming receptacle.

4. The reservoir according to claim 3, wherein the plunger is twisted a quarter-turn to engage the lead screw and keep the plunger engaged to the lead screw.

5. The reservoir according to claim 4, wherein the plunger is twisted in a reverse direction to disengage the lead screw and allow removal of the reservoir.

6. The reservoir according to claim 1, wherein the reservoir plunger includes two legs and the integral split nut connector comprises a half nut formed at the end of each leg of the plunger such that the lead screw can fit between the two legs and the half nut on each leg can simultaneously engage the lead screw when the legs are compressed.

7. The reservoir according to claim 1, wherein the reservoir can be engaged to the lead screw with the reservoir being at any fill level.

8. The reservoir according to claim 1, wherein the medication infusion device has a unidirectional drive system.

9. The reservoir according to claim 1, wherein a locking cap is used to lock the reservoir inside the medication infusion device and to engage the reservoir to the lead screw.

10. The reservoir according to claim 9, wherein the cap allows the medication infusion device to be water resistant.

11. The reservoir according to claim 1, wherein the integral split nut is surrounded by flexible members which allow the split nut to be forced over the lead screw to a starting position.

12. A method of placing a reservoir in a medication infusion device having a rotatable lead screw for controllably dispensing fluid from the reservoir, wherein the reservoir comprises a hollow reservoir barrel and a reservoir plunger, the method comprising:

forming an integral split nut connector on a rear end of the plunger;

aligning coaxially the split nut connector with the lead screw; and

engaging the split nut connector directly to the lead screw.

13. The method according to claim 12, wherein the step of forming an integral split nut connector further comprises:

manufacturing a plunger with at least two legs and a partial nut at the end of each leg of the plunger such that the lead screw can fit between the at least two legs and the partial nut on each leg can simultaneously engage the lead screw when the legs are compressed.

14. The method according to claim 12, wherein the step of engaging the split nut connector further comprises:

twisting the plunger within a camming receptacle, wherein the camming receptacle has camming surfaces such that the camming surfaces push the partial nuts together to form a whole nut over the lead screw when the plunger is twisted within the camming receptacle.

15. An infusion device system comprising:

a reservoir having a reservoir barrel adapted to be filled with a fluid, and a reservoir plunger slidably received into the barrel and movable within the barrel to deliver the fluid from the barrel, and

an infusion device including a device housing defining a reservoir compartment for receiving and supporting the reservoir, and drive means for engaging and controllably moving the plunger to deliver the fluid from the reservoir, the drive means including a rotatably driven lead screw;

wherein the reservoir plunger has an integral split nut connector formed on a rear end of the plunger adapted for co-axial alignment with the lead screw whereby the split nut connector is adapted to be engaged directly to the lead screw.

16. The system according to claim 15, wherein the reservoir plunger includes at least two legs and the integral split nut connector comprises a partial nut formed at the end of each leg of the plunger such that the lead screw can fit between the at least two legs and the partial nut on each leg can simultaneously engage the lead screw when the legs are compressed.

17. The system according to claim 16, wherein the partial nuts are engaged to the lead screw by a camming receptacle, wherein the camming receptacle has camming surfaces to press the partial nuts together to form a whole nut over the lead screw when the plunger is twisted within the camming receptacle.

18. The system according to claim 17, wherein the plunger is twisted a quarter-turn to engage the lead screw and keep the plunger engaged to the lead screw.

19. The system according to claim 18, wherein the plunger is twisted in a reverse direction to disengage the lead screw and allow removal of the reservoir.

20. The system according to claim 15, wherein the reservoir plunger includes two legs and the integral split nut connector comprises a half nut formed at the end of each leg of the plunger such that the lead screw can fit between the two legs and the half nut on each leg can simultaneously engage the lead screw when the legs are compressed.

21. The system according to claim 15, wherein the reservoir can be engaged to the lead screw with the reservoir being at any fill level.

22. The system according to claim 15, wherein the medication infusion device has a unidirectional drive system.

23. The system according to claim 15, wherein a locking cap is used to lock the reservoir inside the medication infusion device and to engage the reservoir to the lead screw.

24. The system according to claim 23, wherein the cap allows the medication infusion device to be water resistant.

25. The system according to claim 15, wherein the integral split nut is surrounded by flexible members which allow the split nut to be forced over the lead screw to a starting position.