PLUNGER FOR INJECTOR, AND SYRINGE AND PREFILLED SYRINGE THAT USES THE SAME

• US 20110178475A1
• Filed: 07/31/2006
• Published: 07/21/2011
• Est. Priority Date: 08/01/2005
• Status: Active Grant

• Current Assignee: Nipro Corporation
• Original Assignee: Nipro Corporation
• Inventors: Tanaka, Shigeki, Iwasa, Masanobu, Hirobe, Teruhisa, Kato, Hidero, Namba, Ryohei
• Granted Patent: US 9,731,077 B2
• Time in Patent Office: Days
• US Class Current: 604/222
• 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 5/31515 Connection of piston with piston rod

Abstract

A plunger for a syringe, in which a plunger rod can be prevented by a simple structure from unavoidably falling out of place.

The plunger for a syringe includes the plunger rod and a gasket. The gasket is closed at its upper end and has an inner space, and an opening having a diameter smaller than the diameter of the inner space is provided in the lower end of the gasket. The plunger rod has a collar installed at the tip of the plunger rod. When the collar is positioned in the inner space of the gasket, the plunger rod and the gasket are freely movably fitted together without intimate contact between them.

Claims

1. A syringe plunger including a plunger rod and a gasket;

wherein the gasket includes a closed upper end and an inner space, and is provided with an opening having a diameter smaller than the diameter of the inner space at a lower end thereof;

the plunger rod includes a collar to be attached to a distal end of the plunger rod;

and the plunger rod and the gasket are in a loosely-fitted state without being in tight contact with each other when the collar is positioned in the inner space of the gasket.

2. The syringe plunger according to claim 1, wherein when an external force is applied to the plunger rod, the collar slips in the gasket so attachment of the collar and the plunger rod is not released.

3. The syringe plunger according to claim 1, wherein smooth movement of the collar with respect to a ceiling surface of the gasket is impaired and slipping of the collar is controllable when the collar top face is brought into press contact with the ceiling surface of the inner space of the gasket.

4. The syringe plunger according to claim 1, wherein a projection is provided on the collar top face and a recess to be engaged or fitted to the projection is provided on the ceiling surface of the gasket.

5. The syringe plunger according to claim 1, wherein a recess is provided on the collar top face and a projection to be engaged or fitted to the recess is provided on the ceiling surface of the gasket.

6. The syringe plunger according to claim 1, wherein the contour of the collar is formed into a tapered shape reducing in diameter thereof toward a distal end thereof.

7. The syringe plunger according to claim 1, wherein the plunger rod and the collar are attached by screw-engagement between a male thread provided at a distal end of the plunger rod and a female thread provided inside the collar.

8. The syringe plunger according to claim 7, wherein the screw-engagement and release of the screw-engagement between the plunger rod and the collar are freely achieved when the collar top face is brought into press contact with the ceiling surface of the inner space of the gasket.

9. A syringe including the syringe plunger according to claim 1 being inserted into a barrel so as to be liquid-tight and slidable.

10. A prefilled syringe containing medicament in a space surrounded by the gasket and the barrel of the syringe according to any one of claims 1 to 9.