Adjustable nozzle dental syringe with pull-back valve

Claim 2

A dental syringe including a handle portion and a tip portion interconnected by a valve body portion and comprising: a. liquid conduit means extending through said syringe from an inlet in said handle portion to an outlet at the free end of said tip portion; b. liquid control means in said valve body portion interposed in said liquid conduit between said inlet and outlet thereof; c. gas conduit means extending through said syringe independently of said liquid conduit means from an inlet in said handle portion to an outlet at the free end of said tip portion; d. gas control means in said valve body portion interposed in said gas conduit between said inlet and outlet thereof; e. nozzle means at the free end of said tip portion communicating with said outlets of both said liquid conduit and said gas conduit; said nozzle means including means providing an orifice of adjustable diameter at said outlet of said liquid conduit, means providing a fixed orifice at said outlet of said gas conduit, and means for adjusting the diameter of said orifice at said outlet of said liquid conduit without change in said fixed orifice at said outlet of said gas conduit and without substantial change in the relationship of said fixed orifice to said adjustable orifice.

Claim 3

A dental syringe as claimed in claim 1 wherein the said liquid control means and said gas control means are arranged with respect to each other to enable both to be actuated simultaneously by a single digit of the hand of an operator thereof.

Claim 4

A dental syringe as claimed in claim 1 wherein said nozzle means comprises: a. a tubular member of elastic material coaxial with the terminal portion of said liquid conduit at said free end of said tip and surrounding said outlet of said liquid conduit with one end of said tubular member in abutment with the end of said liquid conduit to provide said orifice of adjustable diameter at said outlet of said liquid conduit; and b. a tubular member of rigid material having an annular passageway extending coaxially within the wall thereof from one end toward the other end thereof and aperture means at said other end thereof for communication with said outlet of said gas conduit to provide said fixed orifice of said gas conduit in annular form at said one end of said tubular member of rigid material; and c. said tubular member of rigid material coaxially surrounding the outlet portion of said liquid conduit including said tubular member of elastic material, said tubular member of rigid material being provided with annular compression means internally at said one end thereof for abutment with the other end of said tubular member of elastic material and said other end of said tubular member of rigid material being mounted on said liquid conduit for selective axial movement with respect to said liquid conduit to provide said means for adjusting the diameter of said orifice at said outlet of said liquid conduit by axial compression of said tubular member of elastic material.

Claim 5

A dental syringe as claimed in claim 1 wherein said liquid control means comprises an elongated cavity, first aperture means at one end of said elongated cavity communicating with said inlet of said liquid conduit, second aperture means spaced along said cavity from both said first aperture means and the other end of said elongated cavity communicating with said outlet of said liquid conduit, and valve means extending across said cavity intermediate said first aperture means and said secoNd aperture means adapted to selectively interrupt fluid communication between said first aperture means and said second aperture means, said valve means including a plunger having transverse dimensions which slidably fit the transverse dimensions of said elongated cavity, said plunger being located adjacent said second aperture means when said valve means is actuated and being biased to return to a location adjacent said first aperture means when said valve means is not actuated, whereby a reduced pressure is provided in said other end of said elongated cavity to withdraw fluid from said outlet of said liquid conduit.

Claim 6

In a dental syringe comprising a handle portion and a tip portion interconnected by a valve body portion; a. liquid conduit means extending through said syringe from an inlet in said handle portion to an outlet at the free end of said tip portion; b. liquid control means in said valve body interposed in said liquid conduit between the inlet and outlet thereof; said control means comprising an elongated cavity in said valve body, said inlet of said conduit communicating with said cavity through a first aperture at one end thereof, said outlet of said conduit communicating with said cavity through a second aperture spaced along said cavity from both said first aperture and the other end of said elongated cavity and a valve means extending across said elongated cavity intermediate said first and second apertures adapted to selectively interrupt liquid communication between said inlet and said outlet of said conduit, said valve means including a plunger having transverse dimensions which slidably fit the transverse dimensions of said elongated cavity, said plunger being located adjacent said second aperture when said valve is actuated and being spring biased to return to a location adjacent said first aperture when said valve means is not actuated, whereby a reduced pressure is provided in said other end of said elongated cavity to withdraw liquid from said outlet of said conduit; c. gas conduit means extending through said syringe independently of said liquid conduit means from an inlet in said handle to an outlet at the free end of said tip portion, at least a portion of said gas conduit at the outlet thereof coaxially surrounding a portion of said liquid conduit at said outlet of said liquid conduit; and d. gas control means in said valve body portion interposed in said gas conduit between said inlet and outlet thereof.

Claim 7

In a dental syringe comprising a handle portion and a tip portion interconnected by a valve body portion; a. liquid conduit means extending through said syringe from an inlet in said handle portion to an outlet at the free end of said tip portion; b. liquid control means in said valve body interposed in said liquid conduit between the inlet and outlet thereof; said control means comprising an elongated cavity in said valve body, said inlet of said conduit communicating with said cavity through a first aperture at one end thereof, said outlet of said conduit communicating with said cavity through a second aperture spaced along said cavity from both said first aperture and the other end of said elongated cavity and a valve means extending across said elongated cavity intermediate said first and second apertures adapted to selectively interrupt liquid communication between said inlet and said outlet of said conduit, said valve means including a plunger having transverse dimensions which slidably fit the transverse dimensions of said elongated cavity, said plunger being located adjacent said second aperture when said valve is actuated and being spring biased to return to a location adjacent said first aperture when said valve means is not actuated, whereby a reduced pressure is provided in said other end of said elongated cavity to withdraw liquid from said outlet of said conduit; c. gas conduit means extending through said syringe independently of said liquid conduit means from an inlet in said handle to an outlet at the free end of said tip portion, at least a portion of said gas conduit at the outlet thereof coaxially surrounding a portion of said liquid conduit at said outlet of said liquid conduit; and d. gas control means in said valve body portion interposed in said gas conduit between said inlet and outlet thereof.