Infusion device and actuator for same

• US 20070086904A1
• Filed: 10/18/2005
• Published: 04/19/2007
• Est. Priority Date: 10/18/2005
• Status: Active Grant

• Current Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Inventors: Gray, John
• Granted Patent: US 7,753,660 B2
• Time in Patent Office: Days
• US Class Current: 417/417
• CPC Class Codes: A61M 5/14216 Reciprocating piston type
• CPC Class Codes: A61M 5/14236 Screw, impeller or centrifugal type pumps
• CPC Class Codes: A61M 5/14276 specially adapted for implantation
• CPC Class Codes: A61M 5/168 Means for controlling media flow to the body or for metering media to the body, e.g. drip meters, counters ; Monitoring media flow to the body flow control in general G05D7/00
• CPC Class Codes: F04B 13/00 Pumps specially modified to deliver fixed or variable measured quantities
• CPC Class Codes: F04B 17/048 the fluid flowing around the moving part of the motor

Abstract

An apparatus for delivering a fluid includes a housing, an inlet in the housing for receiving the fluid, and an outlet in the housing for discharging the fluid. A piston channel is provided within the housing through which the fluid flows from the inlet to the outlet. An actuator is positioned within the housing and is moveable between a retracted position and a forward position, the actuator defining a piston chamber for storing fluid received through the inlet when the actuator is in the retracted position and for driving the fluid stored in the piston chamber toward the outlet when the actuator transitions from the retracted position to the forward position. The actuator includes an armature and a piston coupled to the armature and moveable within the piston channel. The piston is provided with a groove in an outer surface for conducting fluid from the inlet to the outlet.

Claims

1. An apparatus for delivering a fluid, the apparatus comprising:

a housing;

an inlet in the housing for receiving the fluid;

an outlet in the housing for discharging the fluid;

a piston channel within the housing through which the fluid flows from the inlet to the outlet; and

an actuator positioned within the housing and moveable between a retracted position and a forward position, the actuator defining a piston chamber for storing fluid received through the inlet when the actuator is in the retracted position, the actuator driving the fluid stored in the piston chamber toward the outlet when the actuator transitions from the retracted position to the forward position, the actuator comprising;

an armature; and

a piston coupled to the armature and moveable within the piston channel, the piston having a groove in an outer surface for conducting fluid from the inlet to the outlet.

2. The apparatus of claim 1, wherein the groove is a helical groove around the piston.

3. The apparatus of claim 2, wherein the helical groove includes about 1-7 turns around the piston.

4. The apparatus of claim 3, wherein the helical groove includes 2-5 turns around the piston.

5. The apparatus of claim 1, wherein the groove has a hemispherical cross-section.

6. The apparatus of claim 5, wherein the groove has rounded edges.

7. The apparatus of claim 1, wherein the groove has a depth of about 0.001 inch.

8. The apparatus of claim 1, wherein the groove has a depth of about 0.004 inch.

9. The apparatus of claim 1, wherein the groove has a width of about 0.002 inch.

10. The apparatus of claim 1, wherein the groove has a width of about 0.020 inch.

11. The apparatus of claim 1, wherein the groove has a pitch of about 0.006 inch.

12. The apparatus of claim 1, wherein the groove has a pitch of about 0.050 inch.

13. The apparatus of claim 1, wherein the groove has a cross-sectional area of about 0.00001 square inches.

14. The apparatus of claim 1, wherein the groove has a cross-sectional area of about 0.00003 square inches.

15. The apparatus of claim 1, wherein the groove has a depth that is approximately 1.5-6% of the diameter of the piston.

16. The apparatus of claim 1, wherein the groove has a width that is approximately 3-30% of the diameter of the piston.

17. The apparatus of claim 1, wherein the groove has a pitch that is approximately 8-70% of the diameter of the piston.

18. The apparatus of claim 1, wherein the groove has a cross-sectional area of approximately 0.2-0.6% of the area of the piston.

19. The apparatus of claim 1, wherein the groove is configured to convert laminar flow to turbulent flow when the actuator is transitioning from the retracted position.

20. The apparatus of claim 1, wherein the groove includes a plurality of grooves.

21. The apparatus of claim 20, wherein the plurality grooves includes first and second oppositely wound helical grooves.

22. The apparatus of claim 20, wherein the plurality of grooves includes a plurality of substantially straight longitudinal grooves.

23. The apparatus of claim 1, further comprising a coil located within the housing and in a position relative to the armature to generate an electromagnetic field upon energization sufficient to cause the armature and piston to move from a quiescent position to the forward position.

24. The apparatus of claim 23, further comprising a valve member located on the opposite end of the piston channel relative to the armature, wherein the piston chamber is located between the piston and the valve member.

25. The apparatus of claim 1, further including means for urging the piston and armature toward the retracted position.

26. The apparatus of claim 25, wherein the urging means includes a spring.

27. The apparatus of claim 26, further including an adjuster for enabling adjustment of the piston chamber volume.

28. An actuator for delivering fluid through a piston channel from an inlet to an outlet, the actuator comprising:

an armature configured to move between a forward position and a retracted position; and

a piston coupled to the armature and moveable within the piston channel, the piston having a groove in an outer surface for conducting fluid through the groove.

29. An actuator mechanism, comprising:

an armature portion; and

a piston portion coupled to the armature portion and having a groove in an outer surface.