Syringe piston with check valve seal

• US 9,199,043 B2
• Filed: 09/30/2013
• Issued: 12/01/2015
• Est. Priority Date: 12/22/2009
• Status: Active Grant

• Current Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Inventors: Chattaraj, Sarnath, Gulati, Poonam S., Hoffman, Lance P., Dang, Kiem
• Primary Examiner(s): Bosques, Edelmira
• Application Number:
  US14/041,039
• Publication Number:
  US 20140031749A1
• Time in Patent Office: 792 Days
• Field of Search: 604/22
• US Class Current: 1/1
• CPC Class Codes: A61M 5/31511 Piston or piston-rod constructions, e.g. connection of piston with piston-rod A61M5/5066 takes precedence
• CPC Class Codes: A61M 5/31513 Piston constructions to improve sealing or sliding
• CPC Class Codes: A61M 5/36 with means for eliminating or preventing injection or infusion of air into body dialysis systems, blood oxygenators A61M1/14; haemofiltration equipment A61M1/34; automatic tube cut-off A61M39/281
• CPC Class Codes: Y10T 29/49826 Assembling or joining

Abstract

A fluid syringe of the type used with fluid infusion devices is presented here. The fluid syringe generally includes a barrel, a piston, and a check valve seal. The barrel has an interior wall and a sealed main fluid chamber. The piston is slidably coupled within the barrel, and the piston has a piston seal forming an interference fluid seal against the interior wall. The check valve seal is coupled to the piston, and it is located between the piston seal and the main fluid chamber. The check valve seal forms an interference fluid seal against the interior wall when the piston is unloaded, and it disengages the interior wall to allow gas flow from the main fluid chamber toward the piston seal when the piston is loaded.

Claims

1. A syringe piston comprising:

a piston body having a fluid end and an actuator end opposite the fluid end;

a piston seal coupled to the piston body and located between the fluid end and the actuator end, wherein the piston seal forms an interference fluid seal with an interior wall of a syringe barrel;

a check valve seal coupled to the piston body and positioned such that the piston seal is located between the check valve seal and the actuator end, the check valve seal having a major outer surface that faces a main fluid chamber of the syringe barrel; and

a gas entrapment zone defined between the check valve seal and the piston seal, wherein the check valve seal allows one-way gas flow from the main fluid chamber of the syringe barrel and into the gas entrapment zone, and the piston seal inhibits or prevents gas flow from the gas entrapment zone.

2. The syringe piston of claim 1, wherein the check valve seal comprises a flap that forms an interference fluid seal with the interior wall of the syringe barrel under nominal operating conditions.

3. The syringe piston of claim 1, wherein the check valve seal inhibits gas flow from the gas entrapment zone into the syringe barrel.

4. The syringe piston of claim 1, further comprising an end seal coupled around the piston body and positioned such that the piston seal is located between the check valve seal and the end seal.

5. The syringe piston of claim 4, wherein the piston seal inhibits gas flow from the gas entrapment zone toward the end seal.

6. The syringe piston of claim 4, further comprising a buffer zone defined between the piston seal and the end seal.

7. The syringe piston of claim 1, wherein:

the piston seal is formed from a first resilient material having a first durometer; and

the check valve seal is formed from a second resilient material having a second durometer that is different than the first durometer.

8. The syringe piston of claim 1, wherein:

the check valve seal comprises a flap that cooperates with the interior wall of the syringe barrel;

the flap seals against the interior wall of the syringe barrel when the syringe barrel is closed and the syringe piston is uncompressed;

the flap disengages the interior wall of the syringe barrel when the syringe barrel is closed and the syringe piston is compressed; and

the flap seals against the interior wall of the syringe barrel when the syringe barrel is open and the syringe piston is compressed for purposes of dispensing fluid.

9. A syringe piston comprising:

a piston body having a fluid end and an actuator end opposite the fluid end;

a piston seal coupled to the piston body and located between the fluid end and the actuator end, wherein the piston seal forms an interference fluid seal with an interior wall of a syringe barrel;

a check valve seal coupled to the piston body and positioned such that the piston seal is located between the check valve seal and the actuator end, the check valve seal having a major outer surface that faces a main fluid chamber of the syringe barrel, and the check valve seal comprising a flap having asymmetric deflection characteristics such that the flap is easier to deflect in a direction toward the actuator end, relative to deflection in a direction away from the actuator end; and

a gas entrapment zone defined between the check valve seal and the piston seal, wherein the check valve seal allows one-way gas flow from the main fluid chamber of the syringe barrel and into the gas entrapment zone, and the piston seal inhibits or prevents gas flow from the gas entrapment zone.

10. The syringe piston of claim 9, wherein the flap functions as a one-way fluid flow regulator.

11. The syringe piston of claim 9, wherein the flap forms an interference fluid seal with the interior wall of the syringe barrel under nominal operating conditions.

12. The syringe piston of claim 9, wherein the check valve seal inhibits gas flow from the gas entrapment zone into the syringe barrel.

13. The syringe piston of claim 9, further comprising an end seal coupled around the piston body and positioned such that the piston seal is located between the check valve seal and the end seal.

14. The syringe piston of claim 9, wherein:

the piston seal is formed from a first resilient material having a first durometer; and

the check valve seal is formed from a second resilient material having a second durometer that is different than the first durometer.

15. The syringe piston of claim 9, wherein:

the flap cooperates with the interior wall of the syringe barrel;

the flap seals against the interior wall of the syringe barrel when the syringe barrel is closed and the syringe piston is uncompressed;

the flap disengages the interior wall of the syringe barrel when the syringe barrel is closed and the syringe piston is compressed; and

the flap seals against the interior wall of the syringe barrel when the syringe barrel is open and the syringe piston is compressed for purposes of dispensing fluid.

16. A syringe piston comprising:

a piston body having a fluid end and an actuator end opposite the fluid end;

a piston seal coupled to the piston body and located between the fluid end and the actuator end, wherein the piston seal forms an interference fluid seal with an interior wall of a syringe barrel;

a check valve seal coupled to the piston body and positioned such that the piston seal is located between the check valve seal and the actuator end, the check valve seal having a major outer surface that faces a main fluid chamber of the syringe barrel, and the check valve seal comprising a flap that cooperates with the interior wall of the syringe barrel; and

a gas entrapment zone defined between the check valve seal and the piston seal, wherein the check valve seal allows one-way gas flow from the main fluid chamber of the syringe barrel and into the gas entrapment zone, the check valve seal inhibits gas flow from the gas entrapment zone into the syringe barrel, and the piston seal inhibits or prevents gas flow from the gas entrapment zone;

wherein

the flap seals against the interior wall of the syringe barrel when the syringe barrel is closed and the syringe piston is uncompressed;

the flap disengages the interior wall of the syringe barrel when the syringe barrel is closed and the syringe piston is compressed; and

the flap seals against the interior wall of the syringe barrel when the syringe barrel is open and the syringe piston is compressed for purposes of dispensing fluid.

17. The syringe piston of claim 16, further comprising an end seal coupled around the piston body and positioned such that the piston seal is located between the check valve seal and the end seal.

18. The syringe piston of claim 17, wherein the piston seal inhibits gas flow from the gas entrapment zone toward the end seal.

19. The syringe piston of claim 17, further comprising a buffer zone defined between the piston seal and the end seal.

20. The syringe piston of claim 16, wherein:

the piston seal is formed from a first resilient material having a first durometer; and

the check valve seal is formed from a second resilient material having a second durometer that is different than the first durometer.