Abstract:
A gas flow regulator includes a one-piece housing with an internally disposed flowmeter. The flowmeter is screwed into the housing. A fitting, such as a hose barb, extends through the housing and into the body of the flowmeter to secure the pieces together. Similarly, an inner core assembly can be separately fabricated, screwed into the housing and secured by fittings. This allows a full brass core for oxygen regulators.

Description:
RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Application No. 60/091,127 filed on Jun. 29, 1998, U.S. Provisional Application No. 60/119,745 filed on Feb. 9, 1999, U.S. Provisional Application No. 60/124,704 filed on Mar. 15, 1999 and U.S. Provisional Application No. 60/127,961 filed on Apr. 6, 1999; the teachings of which are all incorporated herein by reference in their entirety. 
    
    
     BACKGROUND 
     Gas flow regulators are used to provide a medical gas, such as oxygen, to a patient from a source supply of the gas. The gas is normally stored in a cylinder or supply vessel under high pressure. The gas flow regulator reduces the high pressure (about 500-3000 psi) to a lower pressure (about 50 p.s.i.) and provides the gas at a metered flow rate, measured in liters/minute. It is desirable to manufacture gas flow regulators as a compact, light weight and smooth to the touch package. It is also desirable to color code the devices to indicate the gas being handled (e.g., green for oxygen) or the preference of the owner of the device. 
     In the prior art, compact gas flow regulators are generally constructed in either a one-piece or two-piece aluminum alloy housing. In one-piece regulators, a pressure reducing element and flow control subassembly is typically held into the housing using a c-clip or snap ring. In these devices, the c-clips do not offer adequate stability. In addition, the flow control knob is usually snapped into place and can, therefore, accidentally separate from the regulator. 
     In two-piece regulators, a pressure reducing element and a piston are disposed within the yoke housing and a flow control housing, having a flow control element therein, screws together with the yoke housing. Consequently, the two-piece regulators have a characteristic division line between the yoke housing and the flow control housing. The use of two pieces also results in additional cosmetic problems. For example, it can be difficult to uniformly color the two housings due to variations in anodizing the pieces. Although two-piece regulators have a less desirable cosmetic appearance than one-piece regulators, the threaded attachment provides certain durability advantages. 
     SUMMARY OF THE DISCLOSURE 
     In accordance with a preferred embodiment of the invention,a gas flow regulator combines the durability advantages of two-piece “screw together” regulators with the cosmetic advantages of one-piece “c-clip” regulators. In particular, internal components are fabricated with a thread over their major diameter and are screwed into a yoke body which is fabricated to have a threaded minor diameter. The internal components are further secured in place by a fitting. 
     This combination of parts yields a one-piece regulator with improved durability and stability. In addition, the flow control knob is connected to the flow control body in such a way that the knob cannot separate from the regulator during use. 
     The modular system also permits the use of internal components which are fabricated from a different material than the yoke body. As such, the yoke body can be made from aluminum and the internal components can be made from brass. The resulting regulator can thus realize the advantageous of each material. 
     In accordance with an embodiment of the invention, a gas flow device includes an outer body with an inner cavity formed therein. The inner cavity is bounded by an inner wall of the outer body, the inner wall having a first coupling feature. An inner element, such as a pressure reducing element or a flow meter assembly, is disposed in the inner cavity. The inner element has an external wall with a second coupling feature. The inner element is secured within the inner cavity by mating the first and second coupling features. 
     The first and second coupling features can be matable threads. In addition, a fitting extends through the outer body and engages with the inner element to further secure the inner element within the outer body. 
     In accordance with another embodiment of the invention, a medical gas flow device provides gas at a selected flow rate from a pressurized supply tank. The device includes an outer body of a first material for physically connecting to the supply tank. 
     An inner core assembly is disposed within the outer body. The inner core assembly has an inlet for interfacing with gas from the supply tank and an outlet for outputting the gas at the selected flow rate. The gas traverses a gas flow path formed from a second material through the inner core assembly from the inlet to the outlet. In a particular embodiment, the outer body and the inner element or core assembly are of different materials. Specifically, the outer body is made of aluminum and the inner element is substantially made of brass. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of embodiments of the gas flow device, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. 
     FIG. 1 is a cross-sectional diagram of a particular gas flow regulator. 
     FIG. 2 is a cross-sectional diagram of the gas flow regulator of FIG. 1, rotated 90°. 
     FIG. 3 is an exploded view, partially in cross-section, of the gas flow regulator of FIG.  2 . 
     FIG. 4 is a cross-sectional diagram of a gas flow regulator with a full-core insert. 
     FIG. 5 is a diagram of the yoke body of FIG. 4 rotated 90°. 
     FIG. 6 is a cross-sectional diagram of the pressure reduction element of FIG.  4 . 
     FIG. 7 is a schematic diagram of the primary gas flow paths through the regulator of FIG.  4 . 
    
    
     DETAILED DESCRIPTION 
     FIGS. 1 and 2 are cross-sectional drawings of a particular gas flow regulator. The regulator  1  includes a yoke body or housing  10 , a flowmeter assembly element  20 , a piston element  30 , a fitting such as a hose barb  40 , a gauge  50  and a T-handle  60 . The yoke body  10  is of a unibody construction to facilitate a secure and stable attachment to a gas supply cylinder (not shown). At a proximal end, the regulator is clamped to a cylinder or tank post of the supply cylinder by the handle  60 . A pressure reducing region  11  of the yoke body  10  reduces the supply tank pressure to about 50 psi, as known in the art. 
     The piston  30  and flowmeter assembly  20  cooperate to supply the desired gas flow. The flowmeter  20  includes a control knob  25  for selection of a metered gas flow rate. A flowrate view window  15  through the yoke body  10  allows the user to view a selected flow rate registered to the setting (not shown) of the knob  25 . Note that in FIG. 2 the flowrate view window  15  is shown rotated 45° from its true position to show details. The metered gas from the flowmeter  20  exits the regulator through the hose barb  40  at a distal end. A relief vent  16  extends through the yoke body  10  into the region of the piston  30  to vent high pressure gas in the event of a piston failure. 
     FIG. 3 is an exploded view, partially in cross section, of the gas flow regulator of FIG.  2 . The piston  30  is received by a piston cavity  13  formed in the yoke body  10 . Likewise, the flowmeter element  20  is received by a second cavity  12  in the yoke body  10 . As illustrated, the flowmeter element  20  has a nominal major diameter D 20  which matches a nominal minor diameter d 12  of the flowmeter cavity  12 . The piston  30  also has a major diameter D 30  which matches the minor diameter d 13  of the piston cavity  13 . 
     The flow rate is determined by an orifice plate  21 , which is attached to the knob  25  and thus the flowmeter element  20  by a retaining screw  22 . Details of the orifice plate can be found in co-pending U.S. Ser. No. 08/941,356, entitled “Orifice Plate” by LeNoir E. Zaiser et al., the teachings of which are incorporated herein by reference in their entirety. As can be seen, the retaining screw  22  secures the knob  25  to the flowmeter element  20 . 
     The flowmeter element  20  is, in turn, secured to the yoke body  10  by respective matable threads  27 ,  17  and the engagable barb  40 . The threads  17 ,  27  are timed such that a barb port  24  in the flowmeter element  20  is center aligned with an output aperture  14  through the yoke body  10  and the flowrate view window  15  is aligned with flow rate numberings (not shown) on the knob  25  when the flowmeter element  20  is properly torqued into the yoke body  10 . The yoke body  10  and flowmeter element  20  are locked in place by the barb  40 , which is screwed through the output aperture  14  and into the barb port  24 . This interlocking arrangement of parts using the threads  27  on the major diameter D 20  of the flowmeter body  20  yields a strong, durable and stable connection. 
     It should be understood that other output connectors, such as a DISS check valve, can be used in place of, or in addition to, the hose barb  40 . It should also be understood that for clarity of description certain parts, such as O-rings and pins, are not illustrated. Although the piston cavity  13  and piston  30  are not shown as being threaded, threads may be included. 
     Because the exterior housing of the regulator can be a single piece, the regulator enjoys the cosmetic benefits of prior one-piece regulators, but in a more durable and stable package. For example, the one-piece yoke body  10  can be anodized or otherwise processed to a desired color. Consequently, the regulator can easily be manufactured to have a uniform color. In addition, the yoke body  10  can be laser etched. 
     In the embodiment shown in FIGS. 1-3, the pressure reducing region  11  is fabricated from the same material as the yoke body  10 , namely an aluminum alloy. The piston  30  and the flowmeter  20  are fabricated from brass. It is currently believed that the use of aluminum in the flow path of oxygen, especially at high pressure, may contribute to a fire potential in medical oxygen regulators due to the relatively low burning point of aluminum. 
     One approach to remove aluminum from the gas flow path is to fabricate the main body of the regulator from brass or other suitable alloys. That brass main body can then be coupled to a stronger aluminum yoke. Unlike aluminum, however, brass cannot be anodized, which limits the manufacture&#39;s ability to color code the regulators. Perhaps more importantly, it may be more difficult to manufacture a suitably secure and rigid coupling. In addition, the increased amount of brass would increase the cost of the regulator without necessarily offering improved quality. 
     FIG. 4 is a cross-sectional diagram of a gas flow regulator with a full-core insert. As illustrated, the regulator is similar to the regulator of FIGS. 1-3, except that the yoke body  100  receives a pressure reduction element  170 . The piston  30  resides inside a cavity of the pressure reduction element  170  defined by an extended wall  175 . The flowmeter assembly  20  interfaces with the piston  30  within the cavity of the pressure reduction element  170 . Also shown is a yoke inlet  180  for interfacing with the supply tank (not shown). A high pressure gauge port  150 L,  150 R for left or right-handed gauges is also shown. 
     As shown, the pressure reduction element  170  includes a vent hole  176 . The yoke body  100  includes a vent window  106  having a larger diameter than the vent hole  176 . As such, a user can see a section of the pressure reduction element  170  through the vent window  106  and can visually verify that the core is a suitable material such as brass. More importantly, in the event of a fire, the larger diameter vent window  106  in the aluminum yoke body  100  reduces the opportunity for any flames ejected from the piston area through the vent hole  176  to ignite the aluminum. 
     FIG. 5 is a diagram of the yoke body of FIG. 4 rotated 90°. Exterior features include a hose barb output aperture  104 , a high pressure gauge aperture  102 , a vent window  106 , and a flowrate view window  105 . Interior features include a main cavity  130  having a minor diameter d 130  for receiving the pressure reduction element  170  (FIG.  4 ). Threads  117  are formed at a neck region  111  of the main cavity  130 . The neck cavity  111  has a minor diameter d 111 . 
     FIG. 6 is a cross-sectional diagram of the pressure reduction element of FIG.  4 . The pressure reduction element  170  includes the pressure reducing features  110  for yielding a 50 psi internal pressure from the supply pressure. An inlet cavity  179  receives the inlet  180  (FIG.  4 ). 
     A neck portion  171  has a major diameter d 171  which matches the minor diameter d 111  of the neck cavity  111  (FIG.  5 ). Threads  177  on the neck  171  of the pressure reduction element  170  mate with the threads  117  (FIG. 5) of the yoke body  100 . The body of the pressure reduction element  170  has a major diameter D 170  which matches the minor diameter d 130  of the main cavity  130  (FIG.  5 ). Note that the piston cavity  13  is now located within the pressure reduction element  170 . 
     It should be recognized that the extended wall  175  can be further extended to receive the flowmeter assembly  20 . For example, the wall  175  may extend to the output aperture  104  or to the flowrate view window  105  (FIG.  5 ). Such a configuration can be achieved by increasing the diameter D 170  of the pressure reduction element  170  and increasing the diameter d 130  of the main cavity  130  a suitable amount. Alternatively, the piston  30  may reside in a cavity defined by a wall of the flowmeter element  20  instead of the pressure reduction element  170 . Such embodiments may reduce the need for certain O-rings, reducing the number of parts and simplifying assembly of the parts. 
     When assembled, the high pressure gauge  50  extends through the gauge aperture  102  and engages a gauge port  150 L,  150 R to help secure the pressure reduction element  170  in place. The threads  117 ,  177  are timed such that, when the pressure reduction element  170  is properly torqued, the gauge port  150  is concentrically aligned with the gauge aperture  102  and the vent hole  176  is concentrically aligned with the vent aperture  104 , within allowed tolerances. Because the gauge  50  screws into the pressure reduction element  170 , the high pressure gas flow directly from the pressure reduction element  170  to the gauge  50  without being exposed to the aluminum in the yoke body  100 . In a particular embodiment, a Teflon shim at the neck  171  of the pressure reduction element  170  is used to further secure the pressure reduction element  170  without the yoke body  100 . 
     FIG. 7 is a schematic cross-sectional diagram of the primary gas flow paths through the regulator of FIG.  4 . High pressure gas from a supply tank  2  enters the regulator through the coupler  180  and flows along a high pressure passage  172  of the pressure reducing element  170  to the pressure reducing feature  110 , which can be a smaller diameter passage dimensioned to provide a working pressure. The high pressure gas also flows into one or more high pressure ports  150 , which are threaded to receive a pressure gauge  50  or other high pressure devices. This constitutes a normal high pressure flow path  1000 . If the pressure reducing element is operating correctly, the gas pressure is reduced and flows into the piston chamber  13 . The low pressure gas is maintained at the desired pressure by a piston assembly  30 , which is shown compressed to its over-pressurize position. 
     Normally, the low pressure gas flows along a piston passage  35  of the piston assembly  30  and through the orifice plate  21 , which determines the flow rate of the gas. After passing through the orifice plate  21 , the gas flows through a flowmeter passage  23  and enters an output port  24  to which a barb  40  or other fitting (FIG. 3) is coupled to deliver the gas to the patient. This is the delivery flow path  1002 . 
     In the event of an abnormal pressure buildup, such as resulting from a failure of the pressure reducing feature  110 , high pressure gas can enter the piston chamber  13 . To prevent this over-pressurized gas from being delivered along the delivery path  1002  to the patient, there is a vent  176  to the atmosphere. More particularly, as the pressure in the piston chamber increases, the piston assembly  30  compresses its spring until the piston chamber  13  is in communication with the vent  176  forming a vent pathway  1004 . The corresponding opening  106  in the housing  100  is dimensioned to be outside the flow path. 
     Regulators embodying aspects of the invention are commercially available from Inovo, Inc. of Naples Fla. and distributed by various distributers, including Tri-anim of Sylmar, Calif. under the trademark Magnus. 
     While this invention has been particularly shown and described with references to embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. 
     For example, although the interior elements are shown and described as coupling with the exterior yoke body using matched and timed threads, other couplings may be used, including twist-lock couplings. In addition, the configuration required to couple the regulator to a gas supply source is defined by the Compressed Gas Association (CGA). The configuration described herein is for a CGA-870 tank connection, but the invention can be employed in other configuration including CGA-540 nut and nipple connections. Furthermore, aspects of the invention can be employed in other gas flow devices, such as pressure reducers.