SYRINGE PLUNGER JACKET WITH EXPANDABLE SEAL

• US 20070088270A1
• Filed: 04/13/2006
• Published: 04/19/2007
• Est. Priority Date: 04/13/2005
• Status: Active Grant

• Current Assignee: Coeur, Inc. (Illinois Tool Works Inc.)
• Original Assignee: Coeur, Inc. (Illinois Tool Works Inc.)
• Inventors: Cude, J.
• Granted Patent: US 7,955,309 B2
• Time in Patent Office: Days
• US Class Current: 604/151
• 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 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 a syringe, the plunger assembly comprising:

a plunger body; and

,

a jacket at least partially covering the plunger body, the jacket having a front sealing ring and a rear sealing ring, wherein the front sealing ring has a larger outer diameter than the rear sealing ring.

2. A syringe assembly, comprising:

a barrel having a generally cylindrical main body portion having an interior surface and an exterior surface, a closed forward end having a discharge aperture, and an open rear end;

a plunger assembly located at least partially within the barrel, the plunger assembly including a plunger body and a jacket at least partially covering the plunger body;

wherein,

the plunger jacket comprises a forwardmost sealing ring on a radially-outward surface and at least one auxiliary sealing ring on a radially-outward surface spaced rearwardly of the forwardmost sealing ring, and wherein the at least one auxiliary sealing ring forms a seal between the plunger assembly and the barrel only when a force is applied to the plunger assembly in the direction of the discharge aperture.

3. The syringe assembly of claim 2, wherein the auxiliary sealing ring contacts the interior of the syringe barrel only when the force is applied to the plunger assembly in the direction of the discharge aperture.

4. The syringe assembly of claim 3, wherein a resting gap between the auxiliary sealing ring and the interior surface of the barrel is at least 0.001 inches.

5. The syringe assembly of claim 4, wherein the resting gap is between 0.005 inches and 0.020 inches.

6. The syringe assembly of claim 2, wherein the auxiliary sealing ring at least intermittently contacts the syringe barrel at all times but forms a seal between the plunger assembly and the barrel only when the force is applied to the plunger assembly in the direction of the discharge aperture.

7. The syringe assembly of claim 2, wherein the plunger jacket comprises chlorobutyl rubber.

8. The syringe assembly of claim 2, wherein the plunger jacket comprises a conical front surface.

9. The syringe assembly of claim 8, wherein the plunger jacket comprises an intermediate conical surface.

10. The syringe assembly of claim 9, wherein the opening angle of the front conical surface is greater than the opening angle of the intermediate conical surface.

11. The syringe assembly of claim 2, wherein the plunger jacket comprises a conical surface.

12. The syringe assembly of claim 2, wherein the plunger body includes an elongated member extending rearwardly from the rear end of the barrel.

13. A syringe plunger jacket having an axis, comprising:

a forward surface;

an intermediate surface; and

,

a rear surface;

wherein the jacket includes a recess extending forwardly from the rear surface and terminating at the intermediate surface, and wherein,

a thickness as measured between the forward surface and intermediate surface increases as the distance from the axis increases.

14. The syringe assembly of claim 13, wherein the plunger jacket comprises chlorobutyl rubber.

15. The syringe assembly of claim 13, wherein the front surface is conical.

16. The syringe assembly of claim 15, wherein intermediate surface is conical.

17. The syringe assembly of claim 13, wherein intermediate surface is conical.