Patent Application
20100081108
1. The Field of the Invention
The present invention generally relates to a coupling adapter for use with an air/water tip of a fluid dispensing apparatus known as a “three-way” syringe.
2. The Relevant Technology
One drawback of existing adapters and delivery tip systems is their tendency to inhibit fluid flow or at least require additional adjustment when attempting to deliver an air-water mixture through a very small orifice delivery tip. In other words, when attempting to deliver an air-water mix under such conditions, the result is that either only air is delivered, only water is delivered, or substantially no fluid flow occurs at all. When attempting to deliver a mixture of air and water, the practitioner must fine tune the water and air pressures on the instrument head 12. Each attempted adjustment may or may not be successful, typically requiring further adjustments and fine tuning. Such fine tuning and troubleshooting with the controls on head 12 can be annoying and time consuming from the perspective of the practitioner, particularly because the success rate of ad hoc adjustment is low.
The present invention is directed to an adapter for use with an air/water tip (e.g., a three-way dental syringe). The adapter comprises a body including proximal and distal ends, a mixing chamber extending between the ends, one or more water delivery lumens extending through the proximal end for delivering water to the mixing chamber, and one or more air delivery lumens extending through the proximal end for delivering air to the mixing chamber. The total cross-sectional area of the water delivery lumens at their distal orifices (i.e., at a location adjacent the mixing chamber) is greater than the total cross-sectional area of the air delivery lumens at their distal orifices (i.e., at a location adjacent the mixing chamber). Providing one or more water lumens with greater cross-sectional area relative to the cross-sectional area of the air lumens automatically aids in balancing the fluid pressures at the lumen orifices into the mixing chamber, preventing inhibition of either fluid stream flow. In addition, balancing of fluid pressures provides a ratio of volumetric flow rate of water to air that is between about 0.5:1 and about 2:1. Ideally, the ratio of volumetric flow rate of water to air is about 1:1.
Water is of much greater density than air (about 800 times greater), while the viscosity of water is significantly greater than that of air (about 50 times greater). Because of this, all else being equal, the flow of water will be inhibited relative to the flow of air. Reducing the lumen cross-section through which the air flows acts to inhibit air flow relative to water flow, which helps to balance the pressures of air and water, and to bring the ratio of volumetric flow rate of water to air closer to 1:1. In a typical three-way syringe, pressurized air may be provided at about 0.5 to 0.6 MPa, while pressurized water may be provided at about 0.2 to about 0.4 MPa. The small diameter air lumen acts to reduce the air pressure so as to be more in line with the water pressure. Balancing the back pressures of the air and water streams at the orifices into the mixing chamber minimizes the tendency for one stream to shut down under back pressure from the other.
From a practical perspective, providing separate lumens for water and air flow, and sizing the lumens so as to provide a ratio of volumetric flow rate of water to air within this range, advantageously allows the practitioner to couple a small orifice delivery tip to the adapter, and still deliver a mix of air and water without having to make manual adjustments to the pressures of air or water, as is normally required in the absence of using the inventive adapter. In addition, by providing a water lumen orifice cross-sectional area that is greater than 1 to about 4 times greater than the air lumen orifice cross-sectional area, the inventors have surprisingly and unexpectedly observed a tendency of the water/air mixture to pulsate when exiting the delivery tip. This results in air/water mixture fluid flows of predominantly water followed spontaneously by predominantly air, which is then followed spontaneously again by an air/water mixture flow of predominantly water. Such pulsation continues indefinitely. This pulsation effect (more water/less air followed by more air/less water) aids in agitating and breaking up materials against which the fluid stream flow is directed. In other words, a pulsating air/water stream tends to apply dynamic and greater forces against the target materials compared to a continuous air/water stream of the same diameter and average pressure. The pulsation effect is believed to result from air bubbles within the mixing chamber being compressed as they move through the small diameter delivery tip and then collapsing just prior to exit.
In one embodiment, a single lumen is provided for water delivery, while a separate single lumen is provided for air delivery. The water delivery lumen is sized larger than the air delivery lumen in order to provide sufficient water flow relative to air flow. For example, the ratio of the diameter of the water delivery lumen adjacent the mixing chamber relative to the diameter of the air delivery lumen adjacent the mixing chamber is greater than 1:1 and less than about 2:1. Sizing the water delivery lumen to be larger than the air delivery lumen advantageously balances the fluid pressures and provides the ability to deliver a water/air mixture at a ratio of water volume flow to air volume flow that is more balanced (i.e., ideally about 1:1), which provides the ability to deliver the mixture without the need to adjust the air or water pressures on the fluid dispensing device. Furthermore, it surprisingly and unexpectedly provides the pulsation characteristic described above.
These and other benefits, advantages and features of the present invention will become more full apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter.
In order that the manner in which the above recited and other benefits, advantages and features of the invention are obtained, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments of the invention and are not therefore to be considered limiting of its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:
I. Introduction
The present invention is directed to an adapter for use with an air/water tip (e.g., a three-way dental syringe). The adapter comprises a body including a proximal end and a distal end with a mixing chamber disposed between the proximal and distal ends of the body, one or more water delivery lumens extending through the proximal end for delivering water from a coupleable fluid dispensing device to the mixing chamber, and one or more air delivery lumens extending through the proximal end for delivering air from a coupleable fluid dispensing device to the mixing chamber. The total cross-sectional area of the one or more water delivery lumens at their distal orifices (i.e., where the lumens enter the mixing chamber) is greater than the total cross-sectional area of the one or more air delivery lumens at their distal orifices (i.e., where the lumens enter the mixing chamber). The relative areas are configured so as to balance the air and water pressures entering into the mixing chamber, and to provide a ratio of volumetric flow rate of water to air that is between about 0.5:1 to about 2:1, more preferably about 0.75:1 to about 1.33:1, and most preferably between about 0.9:1 and about 1.1:1 (e.g., 1:1 being ideal).
Providing one or more water lumens that are relatively larger than the provided air lumen(s) aids in balancing the fluid pressures at the lumen orifices and within the mixing chamber, preventing inhibition of either fluid stream flow. For example, typically the water stream has a more difficult time passing through a small orifice because of its greater viscosity and density. Reducing the size of the air lumen(s) permits the water to flow more freely relative to the air, helping to equalize applied back pressures within the delivery lumens for air and water, while at the same time providing a more balanced volumetric ratio of fluid flow through the mixing chamber and out the dispensing tip.
As used herein, the term water is used to include water as well as aqueous solutions and mixtures. In its broadest sense, the term water may also refer to other non-aqueous liquids, for example if a device similar to a three-way dental syringe were being used to deliver a liquid other than water.
II. Exemplary Adapters and Fluid Dispensing Systems
The inventive adapter serves to adjust the ratio of volumetric flow of water to air much closer to an ideal ratio of 1:1, which advantageously prevents the dispensing system from inhibiting or halting fluid flow when attempting to deliver an air/water mix through a small orifice delivery tip. Adapter 102 includes a proximal end 106 and a distal end 108. Proximal end 106 is configured to be received within and to couple with dispensing head 12. Distal end 108 is configured to couple with separate dispensing tip 104, through which the air, water, or air/water mixture is dispensed.
As shown in
The cross-sectional area of air delivery lumen 116 at location 116a adjacent to mixing chamber 112 where lumen 116 enters mixing chamber 112 is advantageously smaller than the cross-sectional area of water delivery lumen 114 at location 114a adjacent to mixing chamber 112 where lumen 114 enters mixing chamber 112. The relative diameters of lumens 114 and 116 are advantageously sized so as to balance internal back pressure within the mixing chamber, and to provide a ratio of volumetric flow rate of water to air that is between about 0.5:1 and about 2:1 when delivering an air/water mixture. Ideally, the ratio of volumetric flow rate of water to air is maintained at about 1:1, although excellent results (i.e., the ability to deliver an air/water mixture through a coupled small orifice dispensing tip 104, particularly in a pulsing fashion) are still attainable at ratios of volumetric flow rate of water to air between about 0.5:1 and about 2:1, although better results are possible at ratios between about 0.75:1 and about 1.33:1. Optimum results are achieved at ratios between about 0.9:1 and about 1.1:1 (e.g., about 1:1).
The embodiment of
As perhaps best seen in
The foregoing size relationships provide multiple benefits. For example, the length of mixing chamber 112 allows the air and water streams from lumens 116 and 114, respectively, to flow into mixing chamber 112. Because of the length of the chamber 112, good mixing of the streams is possible prior to compression of the mixture once it enters the reduced diameter lumen of the delivery tip 104.
In addition, according to one embodiment, the adapter is manufactured relatively inexpensively by injection molding a suitable plastic material (e.g., polypropylene and/or polyethylene). The adapter may advantageously be molded as a single integral piece, requiring no assembly. Such manufacturing methods allow the adapter to be sold at low cost, encouraging disposal after use. Promoting single use and disposability advantageously reduces the risk of cross-contamination if used with multiple patients. For example, existing adapters in use are typically formed of metal, which manufacture is complex and expensive. The result is that such adapters are not readily disposable, but must be disinfected when reused. It is impractical to dispose of an adapter costing hundreds of dollars after a single use.
When injection molding the inventive adapter, multiple core pins may be used. The core pins of the mold may occupy the mixing chamber on one end, and the water and air delivery lumens on the other end. The relative shortness of the water and air delivery lumens is a practical advantage from a manufacturing perspective as the core pins occupying these spaces (which spaces are very narrow—necessitating thin core pins) can be short, promoting their rigidity during manufacture of the adapters by molding. In one example, it may be desirable to use a core pin that is thicker at the proximal base end relative to the distal tip. Such is possible because it is the diameter and cross-sectional area at locations 116a and 114a that are more important to regulating the ratio of volumetric flow of water to that of air. As such, the core pin (e.g., particularly the smallest core pin that fits within air delivery lumen 116 during molding) may be thicker at its proximal end as compared to the distal end adjacent mixing chamber 112. Such thickening of a portion of the core pin may provide additional rigidity to the core pin, which is advantageous during manufacture of the adapters by injection molding. Such a tapered core pin results in a tapered lumen.
Water flow is selectively provided from dispensing head 12 into the open proximal end of water delivery lumen 114. Air flow is selectively provided from dispensing head 12 into the open proximal end of air delivery lumen 116. In the illustrated embodiment, water lumen 114 extends proximally further than air delivery lumen 116, such that water lumen 114 is longer than air lumen 116. Such a configuration is helpful in preventing water from entering into the proximal end of air lumen 116, and vice versa. Although the open proximal ends of lumens 114 and 116 are illustrated as opening at locations parallel to the longitudinal axis of adapter 102, alternative designs may provide the proximal opening at another location (e.g., so that the opening is perpendicular to the longitudinal axis). In either case, air and water enter the proximal portions of respective lumens 116 and 114. The smaller diameter of the air delivery lumen 116 advantageously provides a balancing of back pressures in the mixing chamber at orifices 116a and 114a. In addition, the balancing of back pressures provides a more balanced volumetric flow of water and air that is within the ranges described above. In the case of delivery of an air/water mixture, the air and water enter into mixing chamber 112 from lumens 116 and 114 respectively, where they mix together as the mixture moves distally towards coupled delivery tip 104 to be delivered as described above.
Such an embodiment performs similarly to that of
Such an example may be less preferred relative to that of
In embodiments where the back flow pressures of air and water within mixing chamber 112 at locations 114a and 116a are balanced, the ability to deliver an air/water mix through the orifice 122 of tip 104 is optimized. In other words, a ratio of volumetric flow rate of water to air of about 1:1 is achieved by providing a ratio of total cross-sectional area of the water delivery lumen(s) to the total cross-sectional area of the water delivery lumen(s) that is about 2.25:1. Such difference in sizing accounts for differences in the densities and viscosities of the air and water streams, as well as the differences in typically provided water pressure relative to typically provided air pressure within standard three-way dental syringes.
As shown in
Although perhaps not fully understood, it is believed that the pulsation effect at least partially results from a balancing of the back pressures so as to provide balanced volumetric flow of air and water to mixing chamber 112, in addition to the compression and eventual cavitation that the air/water mixture undergoes as it progresses towards the small diameter orifice of delivery tip 104. Bubbles initially present within mixing chamber 112 begin to compress as they move into narrower delivery tip 104. Continuing compression of the mixture as a result of the narrowing tip 104 results in formation of cavitation microbubbles, which rapidly collapse under pressure from the surrounding fluid and narrowing delivery tip 104. As the cavitation bubbles collapse, a shock wave is released, which is believed to be at least partially responsible for the observed dynamic pulsation effect. For example, the shock wave may result in movement of the air and water components within the mixture, resulting in portions of predominantly air and predominantly water being grouped together.
It will be appreciated that the present claimed invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative, not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.
The present application claims the benefit of U.S. Patent Application Ser. No. 61/101,371, filed Sep. 30, 2008, entitled “THREE-WAY SYRINGE ADAPTER”, the disclosure of which is incorporated by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61101371 | Sep 2008 | US |
