SYRINGE PLUNGER JACKET WITH EXPANDABLE SEAL

• US 20070233002A1
• Filed: 06/08/2007
• Published: 10/04/2007
• Est. Priority Date: 04/13/2005
• Status: Active Grant

• Current Assignee: Coeur, Inc. (Illinois Tool Works Inc.)
• Original Assignee: US Bank National Association (US Bancorp)
• Inventors: Cude, J.
• Granted Patent: US 7,819,845 B2
• Time in Patent Office: Days
• US Class Current: 604/131
• CPC Class Codes: A61M 5/14546 Front-loading type injectors
• CPC Class Codes: A61M 5/14566 with a replaceable reservoir for receiving a piston rod of the pump
• CPC Class Codes: A61M 5/31513 Piston constructions to improve sealing or sliding

Abstract

A syringe plunger/jacket assembly may comprise a flexible jacket attached to a rigid plunger. The jacket may comprise at least two sealing rings (front and rear) that prevent fluid from leaking out of the rear of the barrel during injection of fluid from the syringe. The rear sealing ring may or may not contact or seal the interior surface of the syringe barrel in an unloaded state. In the loaded state, when force is applied in the direction of the forward discharge end of the syringe, pressure is created on the jacket. This condition causes the rear seal to expand and contact and/or seal the interior surface of the syringe barrel.

Claims

1. A plunger assembly for an associated syringe, comprising:

a plunger body; and

,

a plunger jacket at least partially covering the plunger body, the plunger jacket having at least a front sealing ring and a rear sealing ring, wherein an outer diameter of at least one of the front sealing ring and the rear sealing ring increases when force is applied to the plunger jacket.

2. The plunger assembly of claim 1, wherein the plunger assembly includes an axis defining forward motion of travel for the plunger assembly, and,

wherein the outer diameters of at least one of the front sealing ring and the rear sealing ring increases when axial force is applied to the plunger jacket.

3. The plunger assembly of claim 2, wherein an outer diameter of at least one of the front sealing ring and the rear sealing ring increases in proportion to the axial force applied to the plunger jacket.

4. The plunger assembly of claim 1, wherein the outer diameter of only the rear sealing ring increases when force is applied to the plunger jacket.

5. A syringe assembly for injecting an associated fluid under pressure, comprising:

a barrel having a generally tubular main body portion, the body portion having a discharge aperture fashioned in an enclosed forward end, the body portion having an open rear end;

a plunger assembly received at least partially within the body portion for expelling associated fluid through the discharge aperture, the plunger assembly including a plunger body and a plunger jacket at least partially covering the plunger body, wherein the plunger jacket includes at least a first sealing ring; and

,

wherein the sealing capability of the at least a first sealing ring increases responsive to expelling associated fluid through the discharge aperture.

6. The syringe assembly of claim 5, wherein an outer diameter of the at least a first sealing ring and the interior surface of the body portion comprise an interference fit, and,

wherein the interference fit increases responsive to pressure generated in the body portion from expelling the associated fluid.

7. The syringe assembly of claim 6, wherein the plunger jacket further comprises at least a second sealing ring on a radially-outward surface spaced apart from the first sealing ring.

8. The syringe assembly of claim 7, wherein the at least a first and second sealing rings contact the interior surface of the body portion in a loaded and in an unloaded state.

9. The syringe assembly of claim 7, wherein the at least a first sealing ring has an interference fit for creating an effective seal in either a loaded state or an unloaded state;

and,

wherein the at least a second sealing ring has an interference fit that varies forming an effective seal only in a loaded state.

10. The syringe assembly of claim 7, wherein the interference fit of both the at least a first and second sealing rings increase in a loaded state with respect to an unloaded state.

11. The syringe assembly of claim 7, wherein at least a portion of the at least a second sealing ring contacts the interior surface of the body portion.

12. The syringe assembly of claim 7, wherein at least a portion of the outer diameter of the plunger jacket is fashioned from a thermoset material.

13. The syringe assembly of claim 12, wherein the plunger jacket is fashioned from one or more of the following materials, consisting of:

Chlorobutyl, Bromobutyl and Polyisoprene.

14. The syringe assembly of claim 7, wherein the plunger jacket is fashioned from a thermoplastic material.

15. The syringe assembly of claim 14, wherein the plunger jacket is fashioned from one or more materials, consisting of:

Santoprene, Kraton, PVC or Ployurethane.

16. The syringe assembly of claim 7, wherein the first sealing ring and the second sealing ring have substantially the same outer diameter.

17. The syringe assembly of claim 7, wherein the at least a second sealing ring intermittently contacts the barrel and forms an effective seal between the plunger assembly and the barrel only when pressure is generated in the body portion from expelling the associated fluid.

18. The syringe assembly of claim 7, wherein the at least a second sealing ring does not contact the barrel in an unloaded state, and wherein at least a second sealing ring contacts the barrel in a loaded state forming an effective seal between the plunger assembly and the barrel when pressure is generated in the body portion from expelling the associated fluid.

19. A method of injecting fluid into an animal, comprising the steps of:

providing a syringe barrel having an axis, an interior surface, a forward discharge end, and an open rear end;

providing a plunger assembly being substantially coaxial with the syringe barrel and received at least partially within the syringe barrel to enclose the open rear end, the plunger assembly including a plunger body and a plunger jacket at least partially covering the plunger body, wherein the plunger jacket comprises a forward circumferential sealing ring and a rearward circumferential sealing ring;

filling the syringe barrel with an associated liquid; and

,

actuating the plunger assembly to expel at least a portion of the associated liquid from the syringe barrel under pressure thereby expanding at least one of the forward and rearward circumferential sealing rings.

20. The method of claim 19, wherein both the forward circumferential sealing ring and the rearward circumferential sealing ring expand when the plunger assembly is driven forward.

21. The method of claim 19, wherein the forward circumferential sealing ring and the rearward circumferential sealing ring have substantially the same outer diameter.

22. The method of claim 19, wherein the forward circumferential sealing ring and the rearward circumferential sealing ring have substantially different outer diameters.

23. The method of claim 21, wherein at least one of the forward circumferential sealing ring and the rearward circumferential sealing ring forms an effective seal that prevents fluid from within the syringe barrel under pressure from leaking past the respective sealing ring only when the plunger assembly is subjected to axial force.