Adjustable nozzle dental syringe with pull-back valve
United States Patent Buckley ADJUSTABLE NOZZLE DENTAL SYRINGE WITH PULL-BACK VALVE Apr. 1, 1975 Primary E.\&#39;aminerRobert Peshock Attorney, Agent, or FirmPhillips, Moore, Weissenberger Lempio &amp; Strabala [57] ABSTRACT A dental syringe connectable to sources of air and water under pressure for selectively providing a solid stream of water, a spray of water and air or a jet of air is described. An adjustable nozzle capable of varying the diameter of the stream of water without change in the water pressure at the orifice of the nozzle is disclosed The syringe includes a valve for controlling the stream of water, which valve provides a pull-back action with respect to the water at the orifice of the syringe when the water flow is interrupted.  
 5 Claims, 4 Drawing Figures ADJUSTABLE NOZZLE DENTAL SYRINGE WITH PULL-BACK VALVE BACKGROUND OF THE INVENTION This invention relates to means for forming and controlling streams or jets of fluids or mixtures of fluids in space and more particularly to a syringe capable of selectively providing a solid stream of water, a spray of water and air or a jet of dry air.  
  One of the instruments used by a dentist in the practice of his profession is a so called three-way dental syringe.&#34; Such a syringe is a hand held instrument connected to sources of air and water under pressure by appropriate tubing. The syringe includes air and water valves designed and positioned to enable them to be operated either independently or simultaneously by a digit or digits of the hand in which the syringe is held. The air and water orifices of the syringe are so located with respect to each other that the simultaneous operation of the air and water valves will produce a spray of water droplets.  
  In the practice of his profession, a dentist must often flush out the oral cavity or specific portions thereof with water. The dentist must also thoroughly dry specific portions of the oral cavity or of specific teeth in the performance of certain dental procedures. Thus, the three-way dental syringe provides a convenient instrument capable of providing a spray of water or a solid stream of water for flushing purposes or a jet of dry air for drying purposes.  
  However, three-way dental syringes of the prior art have not provided adequate control over the rate at which water is delivered when the water valve of the instrument is actuated. Such valves, by their nature,  
 tend to be on/off&#34; devices and it would be difficult and expensive to design such a valve capable of varying degrees of actuation in use in order to provide control over the rate at which water is delivered by the syringe. Thus, in the prior art, such control has been provided by adjusting, at the source, the pressure of water supplied to the syringe. It will be understood that, whether the rate at which water is delivered is controlled by partial actuation of the valve or by adjustment of the water pressure at the source, the net result will be to change the water pressure at the orifice of the syringe and thus the characteristics of the stream of water issuing from the syringe. In other words, the stream of water issuing from the syringe will tend to be weak and ineffective at low rates of delivery.  
  It is an object of this invention to provide an adjustable nozzle for a dental syringe or the like which will enable the rate of delivery of water thereby to be reduced without reducing the effectiveness of the stream of water issuing therefrom.  
  It is a further object of this invention to provide an adjustable nozzle for a dental syringe or the like capable of providing a solid stream of water of varying diameter without change in the water pressure at the orifice of the nozzle.  
  It is another object of this invention to provide an adjustable nozzle for a dental syringe or the like which is inexpensive to fabricate and convenient to use.  
  When the dentist wishes to use the three-way syringe to dry a portion of the oral cavity in the performance of certain dental procedures, it is necessary that there be no water present adjacent the air orifice of the syringe since such water would tend to be picked up in the jet of air issuing therefrom thus reducing the drying action of the jet of air. Since the water orifice of the syringe must be located adjacent the air orifice in order to provide the spray function of the syringe, it is necessary to provide means for withdrawing water from the water orifice when the flow of water is interrupted.  
  In the prior art, various methods and means have been used to withdraw or pull-back the water which would otherwise remain present at the water orifice of the syringe when activation of the water valve is discontinued. However. such methods and means have been complicated, expensive or relatively ineffective.  
  It is a still further object of this invention to provide a water valve for a dental syringe or the like which is designed to perform the pull-back function of withdrawing water from the downstream side of the conduit in which it is interposed.  
  It is yet another object of this invention to provide a water valve for a dental syringe or the like which is inexpensive to fabricate and convenient to operate and which provides the pull-back function automatically upon deactivation thereof.  
 SUMMARY OF THE INVENTION According to the teaching of this invention the adjustable nozzle comprises a conduit having one end adapted to be connected to a source of fluid under pressure and the other end provided with a surface extending transversely with respect to the axis of said conduit at said other end thereof. A tubular member of elastic material surrounds at least a portion of the orifice of such other end of the conduit coaxially therewith and a tubular compression member surrounds the tubular member of elastic material. One end of the tubular compression member is mounted on the conduit for axial movement with respect thereto and the tubular compression member terminates in an inwardly extending flange at its other end adapted to compressively contact the other end of the tubular member of elastic material. Thus, axial movement of the tubular compression member with respect to the conduit will subject the tubular member of elastic material to varying amounts of compression thereby changing the inner diameter thereof and the diameter of the fluid stream that will issue therefrom upon actuation of the fluid control valve interposed in such conduit between its ends. According to this invention such valve comprises a body having an elongated cavity therein with inlet means at one end of the cavity communicating with one end of the conduit and outlet means spaced along the cavity from the inlet means and from the other end of the cavity communicating with the other end of the conduit. A valve means extends across the cavity between the inlet means and the outlet means and is adapted to interrupt fluid communication therebetween The valve means includes a plunger having dimensions to slidably fit the cavity, the plunger being located adjacent the outlet means when the valve is actuated and adjacent the inlet means when the valve is not actuated.  
 BRIEF DESCRIPTION OF THE DRAWING This invention together with its objects and advantageous features will be more fully understood from a reading of the following description of a preferred embodiment thereof in conjunction with the attached drawing wherein:  
  FIG. 1 is a side view partially in elevation and partially in section of a dental syringe embodying this invention;  
  FIG. 2 is a fragmentary view in elevation taken along line 22 of FIG. 1 showing the valves thereof;  
  FIG. 3 is an enlarged fragmentary view in crosssection of the nozzle of the dental syringe of FIG. 1;  
  FIG. 4 is an enlarged fragmentary view in crosssection of the water valve structure of the dental syringe of FIG. 1.  
 DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1 a three-way dental syringe including a nozzle and valve according to the teaching of this invention is shown. The syringe comprises a handle portion 11 and a tip portion 12 interconnected by a valve body portion 13.  
  In the embodiment shown the handle portion 11 of the syringe 10 comprises a hollow tubular member dimensioned to provide a convenient grip for the human hand and may be made of any suitable material such as plastic or metal, for example. A pair of suitable tubes or hoses 14 and 15 extend through the hollow handle 11 and are connected to nipples 16 and 17 on the valve body portion 13. According to this embodiment of the invention one of the tubes 15 is connected to a source of water under pressure (not shown) and the other of the tubes 14 is connected to a source of air under pressure (not shown).  
  The tip 11 of the syringe comprises a pair of rigid coaxial tubes mounted at one end on the valve body 13 and extending transversely of the axis of the handle 12. The outer one 18 of the coaxial tubes of the tip 11 provides a conduit for air under pressure and the inner one 19 of the coaxial tubes provides a separate conduit for water under pressure.  
  As shown in FIG. 1 a valve mechanism 21 is installed in a cavity 23 in the valve body 13 with the control button 25 thereof projecting from the valve body 13. Passageways 27 and 29 formed in the valve body 13 communicate with the cavity 23 at spaced points and interconnect the inner tube 19 of the tip 11 with the nipple 17 through the cavity 23 to form a continuous conduit with the valve mechanism interposed between the ends thereof.  
  Referring to FIG. 2, it will be understood that a second valve mechanism (not shown) is installed in a second cavity in the valve body 13 with the control button 26 thereof projecting from the valve body 13 adjacent the control button 25. Appropriate passageways (not shown) formed in valve body 13 and communicating with the second cavity interconnect the outer tube 18 of the tip 11 with the nipple 16 through the second cavity to form a second continuous conduit with the second valve mechanism interposed between the ends thereof.  
  Thus, referring to FIGS. 1 and 2, it will be seen that the handle portion 12 of the syringe 10 may be held in the palm of the hand of the operator by his fingers with the tip portion 11 of the syringe pointing away from the operator in the manner of a pistol. The thumb of the hand of the operator will thus be in an appropriate position to operate the control buttons 25 and 26 projecting from the valve body portion 13 of the syringe.  
  When control button 25 is pressed down by the thumb of the operator a solid stream of water will be projected from the nozzle 30 at the free end of the tip 11 and when the control button 26 is pressed down by the thumb of the operator a jet of air will be projected from the nozzle 30 at the free end of the tip 11. Since the control buttons 25 and 26 are located adjacent each other, it is also convenient for the operator to press both of such buttons down simultaneously with his thumb, in which case both water and air are projected from the nozzle 30 at the free end of the tip 11 in the form of a spray.  
  Referring to FIG. 3 a nozzle 30 according to the teaching of this invention is shown in enlarged cross section mounted on the free end of the tip 11 and in fluid flow communication with the tubes 18 and 19. According to this embodiment of the invention the nozzle 30 comprises a tubular inner member 31 rigidly fixed to the free ends of the tubular 18 and 19 and forming an extension of the inner tube 19. The free end of the member 31 is provided with a surface 32 extending transversely of the axis of the conduit formed thereby and provides the orifice from which the stream of water is projected. A tubular member 33 of elastic material is compressively held against the surface 32 on the free end of the member 31 in coaxial alignment therewith by a flange 34 on the free end of an outer tubular compression member 35. The other end 36 of the outer tubular compression member 35 is provided with internal screw threads adapted to engage cooperating exterior screw threads on the free end of the tube 18. Thus, upon rotation of the outer tubular compression member 35, the engagement of the screw threads will cause it to move axially of the inner tubular member 31 to vary the compression force exerted on the tubular elastic member 33 between the flange 34 and surface 32.  
  It will be seen that when the compressive force exerted axially on the tubular elastic member 33 is increased by proper rotation of the compression member 35 to cause the flange 34 to approach the surface 32, the opening through the tubular elastic member 33 will be reduced by the inward expansion of the walls thereof. Such reduction in the opening through the tubular elastic member 33 will reduce the diameter of the orifice from which the stream of water is projected and will thus reduce the diameter of such stream and the rate of water flow in such stream without change in the pressure of the water in such stream.  
  It has been found that the nozzle 30 according to the teaching of this invention is most useful in dental procedures since it enables the quantity of water projected into the oral cavity to be reduced without reducing the effectiveness of the stream of water. Thus, for example, an extremely fine stream of water under good pressure may be directed into a small drilling to flush it out without using a sufficient quantity of water to require that the patient empty his mouth. This eliminates the delay involved in waiting for the patient to reposition himself in the chair before the drilling operation is continued. At the same time, the nozzle 30 may be quickly and conveniently readjusted to provide a greater quantity of water flow as required.  
  As indicated by dotted lines in FIG. 3 the inner tubular member 31 is provided with passageways 37 in the wall thereof communicating with the interior of tubular member 18 and with passageways 38 through the wall of the outer tubular compression member 35. The passageways 38, in turn, communicate with the interior of a tubular jacket member 39 which is mounted on the free end of the compression member 35 to provide an annular space thereabout terminating in an annular orifice coaxially surrounding the orifice of the water conduit. Thus, such passageways 37 and 38 and the annular space formed by the jacket member 39 about the free end of the compression member form an extension of the air conduit and the orifice of the air conduit is fixed in its relationship to the orifice of water conduit regardless of axial movement of the compression member 35.  
  It will be understood that it is necessary that there be no internal communication between the air and water conduits in order to enable a jet of dry air to be provided by the syringe when desired for the purpose of drying a portion of the oral cavity. Thus, an O-ring type sealing member 40 is provided between the inner tubular member 31 and the compression member 35. A set screw 41 passing through the wall of the compression member 35 and received in an annular groove or channel 42 in the exterior surface of the inner tubular member 31 limits the amount of relative axial movement of the compression member 35 with respect to the inner tubular member 31 and can be used to fix the adjustment of the nozzle at some particular setting between the established limits.  
  Thus, operation of the water valve 21 by pressing down on the button 25 will allow pressurized water from the source to flow through the tube and the conduit formed by the nipple 17, passageways 27 and 29, cavity 23 and inner tube 19 of tip 11, which water will be projected from the free end of the tip in a stream. The diameter of the projected stream will be established by the setting of the nozzle 30 as described above. When the button 25 is released the valve 21 will cut off the flow of water. However, the inner tube 19 of the tip 11 would tend to remain full of water and a large drop of water will tend to form at the orifice of the inner tube 19 if it were not for the novel features of the valve 2] according to the teaching of this invention.  
  It will be understood that if the inner tube 19 remain completely full of water, and more particularly if a drop of water should form at the end of the tube 19, then such water will tend to be picked up in the air jet projected from the tip 11 by subsequently pressing down on the button 26 to actuate the air valve. This is highly undesirable since it will tend to spray water directly on the area which it is desired to dry by means of the air et.  
  Thus, according to this invention the valve 21 functions to withdraw or pull-back the water that would otherwise remain in the tube 19 when the button 25 is released. Referring to FIG. 4 it will be seen that the passageways 27 and 29 communicate with the cavity 23 at points Spaced from each other along the axis of the cavity 23 and that the actual valve means of valve 21 is interposed across the cavity 23 between such points. The valve means includes a plunger 43 and an O-ring 44. The O-ring 44 is held tightly against the outer wall of the cavity 23 and the plunger 43 is provided with a conical surface dimensioned to compressively contact the inner periphery of the O-ring 44 when the valve 21 is in its off position as shown in FIG. 4. The plunger 43 6 is also dimensioned to fit within the cavity 23 with fairly close tolerance and is connected to the button 25 by a shaft 45 received through a bushing 46, which bushing is fixed in the cavity 23 with its inner end in compressive contact with the O-ring 44 by means of a wedging screw 47. A spring means 48 is mounted between the other end of the bushing 46 and the button 25 to bias the valve 21 to its off position. Further O-rings 49 and 50 are interposed between the bushing 46 and the cavity wall and between the bushing 46 and the shaft 45, respectively, in order to make the valve structure fully water right. An appropriate passageway 51 through the bushing 46 provides direct communication between the passageway 27 and the interior of O-ring 44.  
  Thus, when the button 25 is pressed down the spring means 48 will be compressed and the shaft will slide axially in the bushing 46 causing the plunger 43 to be moved axially away from compresson contact with the O-ring 44. Water will then flow from nipple 17 through passageway 27 into cavity 23 where it will pass through the passageway 51 and thus through the O-ring 44 and along the conical surface of the plunger 43 into the passageway 29 and from there into the tube 19 of the tip 1 l.  
  The axial movement of the plunger 43 is sufficient to cause the body thereof to be located at a point in the cavity 23 adjacent the passageway 29 thereby enabling direct communication between passageways 27 and 29 through the valve means when the button 25 is fully depressed. When the button 25 is released, the axial movement of the plunger 43 by the spring means 48 back past the passageway 29 and into compressive contact with the O-ring 44 will tend to withdraw or pull-back water from the passageway 29 and tube 19 of tip 11. The clearance between the plunger 43 and walls of cavity 23 in relation to the volume of the cavity 23 through which the body of the plunger 43 is moved will determine the amount of water withdrawn or pulled back from the tip 1 1 and is preferably adjusted to withdraw only that amount of water necessary to insure that, when the valve is in its off position, no water is present at the orifice of the tip 11 that can be picked up in the jet of dry air issuing from the tip 11 when the air system is actuated.  
  Although this invention has been described as applied to a syringe for projecting and controlling a stream of water and a jet of air in space, it will be understood that other fluids could be substituted for the water and air. It is believed that those skilled in the art will find other applications for this invention and that they will make obvious changes in the specific embodiment described herein without departing from the teaching of this invention.  
 What is claimed is:  
  l. 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.  
  2. 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.  
  3. 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.  
 4. 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.  
  5. 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 gas control means in said valve body portion interposed in said gas conduit between said inlet and outlet thereof.