Syringe with passive safety lock

[0001] The invention here disclosed relates primarily to syringes and in particular those typically used for medical purposes that allow unintended dispensement of fluid substances from the syringes main staging chamber.

[0002] The main purpose of the improvement here disclosed is to provide a reliable, safe, simple and low cost method of passively and automatically locking a syringe from unintended dispensement of its contents when and only when not engaged for its ultimate purpose and allowing for automatic unlocking whenever and however many times a syringe is engaged for its ultimate purpose upon at least two points of contact.

[0003] Various attempts to create syringe locks have been made such as the locking mechanism disclosed by Watts (20070049872-A1 US). These attempts allow effective locking control by way of the deliberative action of the user to engage the locking mechanism. Further, the locking mechanism is disclosed as a separate part which will lead to inconsistent use where safety is a factor.

[0004] The invention here disclosed provides passive locking control of the syringe plunger in its preferred embodiments. Further, the preferred embodiments accomplish the said passive locking control within a simple low cost and easy to manufacture and implement structure.

[0005] Passive locking control is necessary to ensure maximum effective use, application safety enhancement and reduced waste including that of sometimes expensive medical supplies.

[0010] As illustrated by FIGS. 1,2 & 5, the syringe cylinder-case, FIG. ______, is molded with a locking slip collar ______ attached in a manner to allow purposeful concentric engagement with the open end of the syringe cylinder-case ______ after the plastic molding process is complete as illustrated in FIG. 2.

[0011] As illustrated in FIG. 2 once the locking slip collar ______ is rotated and locked into its final working position the attaching flexible plastic strip acts both as a hinge and spring in order to bias the locking slip collar in the preferred opposite direction away from the syringe cylinder-case's open end ______.

[0012] As illustrated in FIG. 3 a plunger arrangement ______ is inserted into and past the locking slip collar ______ and into the cylinder-case simultaneously. The locking slip collar ______ is designed with a slight interference around the plunger's concentrically round tube base ______. As the plunger arrangement ______ is displaced toward the distal end of the cylinder-case ______ the locking slip collar ______ is driven into a wedge seat arrangement designed within the open end of the cylinder-case ______ designed to engage a corresponding wedge seat as part of the locking slip collar ______. The engagement of the said wedge seat arrangement exponentially increases resistance between the locking slip collar ______ and the plunger's concentrically round tube base ______ which ultimately locks the said plunger arrangement and disallows further unintentional displacement of the plunger arrangement therein ______ towards the distal end of the cylinder-case ______ which prevents unintentional dispensement of the contents therein.

[0013] As illustrated in FIGS. 2+3 once the locking slip collar ______ is rotated into its final working position engagement of the syringe arrangement for its intended purpose automatically and reliably displaces the locking slip collar ______ in the opposite direction of the displacement of the plunger arrangement ______ and the wedge seat arrangement ______ which facilitates disengagement of the locking slip collar allowing low resistance displacement of the plunger arrangement ______ towards the distal end of the cylinder-case end to a selectively desired displacement.

[0014] As illustrated in FIGS. ______+______ the locking slip collar ______ can be manually rotated clockwise engaging thread tabs as part of the syringe cylinder ______ that effectively drive and lock the locking slip collar linearly into its fully engaged position restricting free displacement of the plunger assembly ______. Rotating the locking slip collar counter clockwise past the neutral default-passive position engages thread tabs ______ that effectively drive and lock the locking slip collar linearly in its fully disengaged position allowing free displacement of the plunger assembly ______.

[0015] In the preferred embodiment the plunger ______ includes a simple one way locking lip ______ at it's distil end which allows the plunger ______ to pass through the locking slip collar ______ and allows a full range of dual direction slidable connection with the locking slip collar ______ but disallows reverse direction disengagement of the plunger passed the locking lip ______ in order to discourage disengagement of the primary purpose passive safety feature as may be desired.