Syringe plunger system with self-locking threaded geometry
AssigneeTolmar Therapeutics, Inc.
InventorsKevin McCann, Eric Mugoye, Dominic Madril
Life of this patent
Estimating the term…
Abstract
A plunger rod system for syringes is provided. The system comprises at least one plunger and an associated rod for imparting force to the plunger. The rod comprises an end with a threaded member, and the threaded member comprises threads of a certain geometry that enable ease of installation of the rod within the plunger while also providing resistance to pull-out forces such as may be imparted when pulling or extracting the rod or plunger from a barrel.
Claims19
A plunger rod useful for supporting and sliding a stopper in a syringe barrel, the plunger rod comprising:
- a first end and a second end;
- the first end comprising a user-interface portion having a flange;
- the second end comprising a threaded portion adapted for interconnection to a stopper;
- wherein the threaded portion comprises a shaft having an external male thread and a predetermined thread geometry;
- the external male thread comprising a locking element, wherein the locking element comprises a planar surface and a projection having a point, wherein the projection extends at an angle relative to the planar surface and terminates at the point, and wherein the locking element departs from a general path of the threaded portion, wherein the projection and the point extend over the external male thread, and wherein the external male thread provides enhanced pull-out resistance of the stopper;
- and
- wherein the locking element comprises a deviation from the external male thread wherein a thread angle of the locking element is greater than a thread angle of the external male thread.
A plunger rod useful for supporting and sliding a stopper in a syringe barrel, the plunger rod comprising:
- a first end and a second end;
- the first end comprising a user-interface portion;
- the second end comprising a threaded portion adapted for interconnection to a stopper;
- wherein the threaded portion comprises an external male thread and a predetermined thread geometry having a first thread angle;
- the external male thread comprising a locking element, wherein the locking element comprises a planar surface and at least one projection departing from a general path of the threaded portion, the projection comprising a second thread angle and terminating at a point and wherein the second thread angle is greater than the first thread angle;
- wherein the projection and the point extend over a portion of the external male thread;
- wherein the point is operable to extend at least partially into a stopper in an assembled state;
- wherein the locking element permits threaded insertion of the external male thread into a stopper by rotation in a first direction and inhibits a reverse rotation, and wherein the external male thread provides enhanced pull-out resistance of the stopper, and wherein removal of the stopper from the plunger rod by rotation is inhibited by the locking element.
A syringe including a barrel, a plunger rod, and a stopper, the plunger rod comprising:
- a first end and a second end;
- the first end comprising a user-interface portion;
- the second end comprising a threaded portion;
- wherein the threaded portion comprises an external male thread and a predetermined thread geometry having a first thread angle;
- a stopper connected to the second end of the plunger rod;
- the external male thread comprising a locking element, wherein the locking element comprises a planar surface and at least one projection extending at an angle relative to the planar surface, and wherein the at least one projection departs from a general path of a pitch of the threaded portion, the projection comprising a second thread angle and a point, the projection and point extending over a portion of the external male thread;
- wherein the second thread angle is greater than the first thread angle;
- and
- wherein the point extends at least partially into the stopper, the plunger rod provides enhanced pull-out resistance of the stopper, and a removal rotation of the plunger rod is operable to force the locking element further into the stopper.
Dependencies are inferred from the claim text.