Plunger for nozzle assembly

• US 5,921,967 A
• Filed: 12/24/1996
• Issued: 07/13/1999
• Est. Priority Date: 02/29/1996
• Status: Expired due to Term

• Current Assignee: Eli Lilly and Company
• Original Assignee: Medi-Ject Corporation
• Inventors: Mulhauser, Paul, Schiff, David, Stoeckmann, Walter, Sadowski, Peter L.
• Primary Examiner(s): YASKO JR, JOHN D
• Application Number:
  US08/773,660
• Time in Patent Office: 931 Days
• Field of Search: 604/110, 604/218, 604/228, 604/187
• US Class Current: 604/218
• CPC Class Codes: A61M 2005/31516 reducing dead-space in the syringe barrel after delivery
• CPC Class Codes: A61M 2005/5073 by breaking or rupturing the connection parts
• CPC Class Codes: A61M 5/30 Syringes for injection by jet action, without needle, e.g. for use with replaceable ampoules or carpules
• CPC Class Codes: A61M 5/31515 Connection of piston with piston rod
• CPC Class Codes: A61M 5/5066 Means for preventing re-use by disconnection of piston and piston-rod

Abstract

The present invention is directed toward a plunger provided for use in a nozzle assembly. The nozzle assembly includes an internal chamber with an outwardly tapered portion at one end thereof. The plunger includes a plurality of outwardly curved prongs or legs which mate with an inwardly tapered portion of the internal chamber in order to allow the piston of the injector to be released from the plunger. As a result, the plunger may be removed from the injector when the nozzle assembly is removed therefrom. This plunger may include a frangible portion so that, upon firing, a first driving member of the plunger breaks away from a second driving member of the plunger. As a result of this frangible connection, the first driving member remains lodged in a distal portion of the chamber to prevent reuse of the nozzle assembly.

Claims

1. A plunger slidingly movable within a fluid chamber for expelling fluid out of or drawing fluid into the chamber by moving the plunger relative to the chamber, the plunger comprising first and second driving members which include respective end and base portions retained in spaced relation by a frangible connection therebetween, with the second driving member being spaced apart from the first driving member by a gap, such that when a force sufficient to break the frangible connection is applied to the second driving member in a direction toward the first driving member, the frangible connection is broken and the second driving member moves across said gap toward the first driving member for urging the first driving member towards an end of the chamber to expel fluid therefrom, and when the second driving member is thereafter moved away from the first driving member, the first driving member remains in the chamber to prevent reuse of the plunger.

2. The plunger according to claim 1, further comprising means for connection to a force generating component.

3. The plunger according to claim 2, wherein the connection means comprises a plurality of outwardly flared prongs.

4. The plunger according to claim 1, wherein the plunger is cylindrical and the first and second driving members meet to define the frangible connection therebetween, said frangible connection having at least a portion which extends across the diameter of the plunger.

5. The plunger according to claim 1, wherein the first driving member has a seal in contact with the chamber.

6. The plunger according to claim 1, wherein the frangible connection is disposed perpendicular to the planes formed by the surfaces of the end portions of the first and second driving members.

7. The plunger of claim 1, wherein the frangible connection is spaced radially relative to the longitudinal axis.

8. The plunger of claim 1, wherein the chamber includes a tapered portion adjacent the orifice and the first driving member includes a tapered member which conforms to the tapered portion of the chamber.

9. The plunger of claim 1, wherein the end and base portions of the first and second driving members face each other and are joined by the frangible connection.

10. The plunger of claim 9, wherein the first driving member is separated from the second driving member by a gap, and the frangible connection extends from the second driving member to connect the end portions of the first and second driving members, such that when a force sufficient to break the frangible connection is applied to the second driving member, the frangible connection is broken and the second driving member moves across the gap toward the first driving member with the base portion of the second driving member contacting the end portion of the first driving member as the end portion of the second driving member contacts the base portion of the first driving member for urging the first driving member towards the end of the chamber.

11. The plunger according to claim 10, wherein when the second driving member is thereafter moved away from the first driving member, the first driving member remains in the chamber to prevent reuse of the plunger.

12. The plunger of claim 10, wherein each of the end portions is configured and dimensioned to occupy more than half the cross-sectional area of the plunger, wherein the first and second end portions are positioned in subjacent relation after the second member moves across the gap.

17. A nozzle assembly adapted for use with an injection device comprising:

a chamber for holding a fluid and having an orifice for fluid passage at one end;

a force generating component for generating a force to expel fluid out of or to draw fluid into the chamber; and

the plunger of claim 2.

19. The nozzle assembly of claim 17, wherein the plunger is made of an acrylic polymer.

13. A plunger slidingly movable within a fluid chamber having proximal and distal ends with an outwardly flared portion adjacent the proximal end thereof, which plunger comprises:

a body member having a distal end and a proximal end, said distal end for expelling fluid out of or drawing fluid into the chamber; and

a plurality of outwardly flared prongs located at the proximal end of the plunger, said prongs being operatively associated with a force generating component for movement of the body member and being configured and dimensioned to be received in the outwardly flared portion of the chamber in order to allow release of the force generating component from the prongs without removing the prongs from the chamber.

14. The plunger of claim 13, wherein the outwardly flared prongs have an inner surface and an outer surface and a lip portion is located on the inner surface.

15. The plunger of claim 14, wherein the outwardly flared prongs have a ridge portion positioned on the outer surface and said outwardly flared portion of the internal chamber includes an annular groove for receiving the ridge portion.

16. The plunger of claim 14, wherein the force generating component includes a lead portion and the lip portions of the prongs engage the lead portion when the prongs are positioned within the chamber.

18. A nozzle assembly adapted for use with an injection device comprising:

a chamber for holding a fluid and having a proximal end, a distal end, an outwardly flared portion adjacent the proximal end, and an orifice for fluid passage at the distal end;

a force generating component for generating a force to expel fluid out of or to draw fluid into the chamber; and

the plunger of claim 13.

20. The nozzle assembly of claim 18, wherein the plunger is constructed of a material which includes a polymer selected from the group consisting of polycarbonate, polypropylene, polystyrene, and acrylic.