Abstract:
A threaded connecting assembly includes a first threaded connecting member having a body portion, an end portion, a bore extending axially from the end portion enabling the passage of a fluid through the body portion, and a plurality of spaced apart three sided threads defining grooves therebetween projecting along an exterior surface of the body portion at the end portion, and a cap member having a plurality of complementary three sided threads adapted to mate with the plurality of the three sided threads of the first threaded connecting member by seating in the grooves, and an opening configured for engagement with the bore of the first threaded connecting member to provide a passageway for the flow of the fluid therebetween.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a threaded connecting assembly, more particularly to a threaded connecting assembly for forming a fluid connection between two fluid conduits in a manner providing high pressure durability, wear resistance, and rapid sealing therebetween. 
     BACKGROUND OF THE INVENTION 
     Compressed fluids including gas, liquid and combinations thereof, are widely used throughout the food industry. Carbon dioxide gas and inert gases such as argon, helium, and nitrogen are extensively utilized for carbonation and food preservation, for example. Such food processing operations typically employ a fluid dispensing apparatus, a fluid source for supplying pressurized fluid, and a means for fluidly connecting the fluid source to the fluid dispensing apparatus. The fluid source is usually in the form of a compressed gas-containing cylinder which can store pressurized gas at pressures ranging from about 35 to 2,700 pounds per square inch (p.s.i.). 
     Such gas-containing cylinders typically include a fluid-tight vessel body with a cavity therein. The vessel body has a tapered neck with an outlet located at one end thereof. The cylinder is composed of a metal material for durability and strength. The compressed gas-containing cylinder may be sealed with a plate crimped at an outlet end for providing safe storage and transport. In order to dispense the compressed gas in a controlled manner, a fluid dispensing apparatus is ordinarily employed. The neck of the cylinder is mated with the gas port of the apparatus where a connecting pin is adapted to pierce through the cylinder plate for releasing the gas contents therethrough. 
     Generally, there are two types of cylinders used in the industry: those having threads and those that are unthreaded. Unthreaded cylinders are the most common and economical. However, fluid dispensing apparatuses which utilize such unthreaded cylinders usually require an assembly for positioning the cylinder to provide a secure fluid connection. The assembly holds the cylinder neck in position against the port, and applies a sufficient force to the cylinder to drive the neck end into the connecting pin for puncturing the plate and forming a fluid connection therebetween. Fluid connections of this type are disadvantageous because the cylinder neck is simply press fitted into position against the port which can result in leaking of the fluid at the junction of the cylinder neck and port. 
     Threaded cylinders typically include narrow, tapered threads extending along the surface of the cylinder neck. The threads substantially improve the quality of the fluid seal in the connection and provide a fluid connection which is more resistant to shock and vibration as compared to unthreaded fluid connections. However, the narrow, tapered threads cost substantially more to fabricate, have relatively low wear resistance and thread strength, and require many screw-turns for adequate seating within the port. These and other limitations associated with such threaded cylinders have restricted their use. 
     It would be a significant advance in the art of threaded connectors to provide a threaded connecting assembly for use especially with a compressed fluid which overcomes many of the limitations associated with prior art threaded connectors. The threaded connecting assembly of the present invention is constructed in a cost efficient and effective manner having minimal parts while providing the benefits of high thread strength, high pressure durability, ease of use, high wear resistance, and rapid-sealing. 
     SUMMARY OF THE INVENTION 
     The present invention is generally directed to a threaded connecting assembly comprising: 
     a first threaded connecting member having a body portion, an end portion, a bore extending axially from the end portion enabling the passage of a fluid through the body portion, and a plurality of spaced apart three sided threads defining grooves therebetween projecting along an exterior surface of the body portion at the end portion; and 
     a cap member having a plurality of complementary three sided threads adapted to mate with the plurality of the three sided threads of the first threaded connecting member by seating in the grooves, and an opening configured for engagement with the bore of the first threaded connecting member to provide a passageway for the flow of the fluid therebetween. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The following drawings in which like reference characters indicate like parts are illustrative of embodiments of the invention and are not to be construed as limiting the invention as encompassed by the claims forming part of the application. 
     FIG. 1 is an elevational view of a prior art device including a compressed gas-containing cylinder and a conventional threaded connector for forming a threaded connecting assembly of the prior art; 
     FIG. 2 is a partial cross sectional view of the prior art threaded connecting assembly utilizing the prior art device shown in FIG. 1; 
     FIG. 3 is a cross sectional view of a portion of the first threaded connector threads of the prior art device of FIG. 1 for illustrating the prior art thread pattern; 
     FIG. 4 is an elevational view of an embodiment of a device including a compressed gas-containing cylinder and a threaded connector for forming a threaded connecting assembly of the present invention; 
     FIG. 5 is a partial cross sectional view of the a threaded connecting assembly of the present invention utilizing the device shown in FIG. 4; 
     FIG. 6 is an exploded cross sectional view of the first threaded connector shown for illustrating a representative thread pattern of the threaded connecting assembly shown in FIG. 5; 
     FIG. 7 is an exploded cross sectional view of the first threaded connector illustrating a thread pattern for a second embodiment of the present invention; 
     FIG. 8A is partial side elevational view of the first threaded connector of a device for a third embodiment of the present invention in the form of a compressed gas-containing cylinder; 
     FIG. 8B is an exploded cross sectional view of the first threaded connector of the compressed gas-containing cylinder shown in FIG. 8A; and 
     FIG. 8C is an enlarged detailed cross sectional view of a portion of the first threaded connector as indicated by a circle marked “FIG.  8 C” in FIG.  8 B. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention is generally directed to a threaded connecting assembly designed and constructed in a manner that provides a durable, rapid-sealing fluid connection for safe, reliable passage of a pressurized fluid between two locations. The threaded connecting assembly is constructed with the advantage of low cost, long term dependability, and ease of use as desired by the consumer. In addition, the threaded connecting assembly may be constructed in a manner which permits passage of high pressure fluid including gas, liquid and combinations thereof. The cost effective and efficient manner by which the threads are constructed and by which the threaded connecting assembly can be implemented makes the connecting assembly especially suitable for a variety of industrial and consumer uses including, but not limited to, gas actuation assemblies of the type shown and described in U.S. Pat. Nos. 5,458,165 and 5,566,730. 
     While this invention is being described in its preferred embodiment as being adaptable for use with compressed gas-containing cylinders and gas dispensing apparatuses, it will be understood that the invention may be utilized with other kinds of fluid delivering devices or conduits which require a threaded connection means for effecting movement of a fluid including gas, liquid and combinations thereof, from one location to another. It will also be understood that the invention has application for any environment and purpose particularly where it is desirable to create a durable, rapid-sealing fluid connection between two or more fluid delivering devices or conduits. 
     Referring to FIG. 1, a compressed gas-containing cylinder  2  of the prior art is shown. The cylinder  2  includes a storage vessel  4  for storing a fixed volume of a compressed gas, and a first threaded connector  6  positioned in the neck  7  of the cylinder  2  for coupling with a second threaded connector or gas port of a gas dispensing apparatus as will be described hereinafter. It will be understood that the first threaded connector  6  may be located in other positions of the cylinder  2 , not just the neck  7 . The first threaded connector  6  includes an opening (not shown) at the top  8  thereof which is sealed by a plate  10  to secure the containment of compressed gas therein during storage and transport. The first threaded connector  6  further includes a plurality of narrow, triangularly-shaped and spaced exterior threads  12  separated by correspondingly shaped grooves  5  (see FIG. 3) extending therearound. The threads  12  of the prior art are  2  sided threads in that their opposed tapered sides meet at a point or tip portion  13  as shown best in FIG.  3 . 
     Referring now to FIG. 2, the first threaded connector  6  is coupled to a gas port  16  by the mating engagement between the respective threads,  12  and  14  which seat within the grooves  5  to form a prior art threaded fluid connector assembly  9 . The first threaded connector  6  must be screw-turned for six or more turns to achieve full seating within the port  16 . 
     The gas port  16  includes a centrally located hollow connecting pin  18 with a bore  19 . The hollow connecting pin  18  is configured to pierce through the plate  10  as the first threaded connector  6  becomes seated within the port  16 . Upon piercing the plate  10 , the compressed gas within the cylinder  2  is discharged through the bore  19  of the hollow connecting pin  18  and into the gas dispensing apparatus (not shown). During such fluid connections, the engaged threads experience substantial shearing forces generated by the high pressured gas contained therein. With prolonged and repeated use, the  2  sided threads  12  and  14  are prone to cracking under pressure resulting in the failure of the fluid connection and consequential leaking of the stored fluid. In addition, the threads  12  and  14  possess limited wear resistance thus increasing the rate of connection failures after repeated use. 
     With reference to FIG. 3, a sectional view of a portion of the  2  sided threads  12  of the first connector  6  is shown. The threads  12  include corner portions  22  which lie at the base of the respective threads  12 . The threads  12  are vulnerable to stress fractures especially at the corner portions  22  because the high shearing forces that are generated by the high pressure gas, are focused along the threads which over time may result in material fatigue and premature failure. Such stress fractures often bring about leakage of fluid and compromised cylinder retainment within the gas port  16 . As previously indicated, each of the  2  sided threads  12  include a substantially narrow tip portion  13  which is prone to breakage during implementation of the fluid connection. The same limitations described above likewise pertain to the complementary threads  14  of the gas port  16  (see FIG.  2 ). 
     The present invention at least substantially reduces the occurrence of stress fractures by providing a connecting assembly which is less vulnerable to potentially damaging shearing forces. The present invention can be best understood by reference to FIGS. 4-8C, showing various embodiments of a threaded connecting assembly of the present invention. 
     Referring to FIG. 4, a compressed gas-containing cylinder  30  is provided with a first threaded connector  32  for establishing a threaded connecting assembly for one embodiment of the present invention. The cylinder  30  further includes a storage vessel  4  for storing a fixed quantity of a compressed fluid. By way of illustration only, the storage vessel  4  contains a compressed gas such as carbon dioxide, nitrogen, argon, helium and the like. A first threaded connector  32  is configured for threaded coupling with a second threaded connector in the form of a gas port  36  (see FIG. 5) and includes a plurality of exterior three sided threads  34  as defined herein, each having a broader profile than those found in the prior art connectors. It will be understood that the first threaded connector is shown at the neck region of the compressed gas containing cylinder but may be positioned at other regions as necessary to form a fluid connection therebetween. The term “ 3  sided thread” as used herein refers generally to the threads having three sides including an opposed pair of sides which may or may not be parallel to each other, connected to each other through a third side which may be straight or have one or more curvilinear portions. 
     The threads  34  are configured to withstand the shearing forces associated with high pressure fluid connections as will be described hereinafter. In a preferred embodiment particularly suited for connections of a compressed gas-containing cylinder to a gas actuator assembly similar to one shown in U.S. Pat. Nos. 5,458,165 and 5,566,730, the first threaded connector  32  is about ⅜″ in length and about ⅜″ in diameter. The threads  34  may number preferably from about two to four, and most preferably three. The width of each thread  34  is preferably about {fraction (1/16)}″. In addition, the preferred embodiment has each of the threads  34  being separated by a {fraction (1/16)}″ groove. The cylinder  30  may be adapted to retain a compressed gas at pressures ranging from about 35 to 2,700 pounds per square inch (p.s.i.). The cylinder  30  may be further composed of a suitable durable material such as steel, aluminum, plastic, carbon fiber composite, and the like for safe containment of the fluid contents therein. 
     Referring to FIG. 5, the present invention is shown generally as a threaded connection between two conduits enabling fluid passage therebetween. FIG. 5 is a cross sectional view through the engaged threaded connectors, and illustrate the first threaded connector  32  on the left and the second threaded connector in the form of the gas port  36  on the right. As shown, the first threaded connector  32  is formed with a plurality of exterior three sided threads  34  on the end thereof. 
     In accordance with the present invention, the external threads  34  are synchronized, such that rotating the first threaded connector  32  in a clockwise direction enables the external threads  34  to travel along and engage the mating threads on the gas port  36 . In this regard, the gas port  36  includes a plurality of complementary interior threads  38  which are configured to engage with the exterior threads  34  of the first threaded connector  32  as the two threaded connectors are screw threaded together to form a threaded connecting assembly  11  of the present invention. 
     The threaded connecting assembly  11  may further optionally include an O-ring  24  in the gas port  36  for improving the quality of the fluid seal between the first threaded connector  32  and the gas port  36 . The fluid seal may further be effected by sealing means other than O-rings, i.e. by any fluid seal design or type that is typical for the particular industry in which fluid connectors are utilized as for examples washers, TEFLON tapes, sealant substances, and the like. 
     Referring to FIG. 6, an exploded cross sectional view of the threads  34  of the first threaded connector  32  is shown for illustrating a representative thread pattern referred generally by reference numeral  37  of a plurality of three sided threads  34 . The three sided threads  34  have a generally wider profile than  2  sided conventional threads for improved wear resistance and capacity to withstand shearing forces associated with high pressure fluid connections. Each of the three sided threads  34  includes a pair of opposed side portions  35  which may or may not be parallel to each other and connected together through a top portion  31  which may be flat or contain one or more curvilinear portions. 
     Each of the three sided threads  34  also includes corner portions  40  and  42  at areas where the side portions  35  meet with the top portions  31 , and the side portions  35  meet with base portions  33  of the first threaded connector  32 , respectively. The corner portions  40  and  42  are preferably curvilinear for minimizing stress fractures typically associated with sharp angular areas (i.e. perpendicular junction areas). 
     The three sided threads of the present invention provide the structural strength necessary to resist the shearing forces often encountered by the threaded connecting assembly  11  of the type shown in FIG.  5 . The curvilinear corner portions  40  and  42  function to distribute at least a significant portion of the shearing forces over a larger surface area to effectively reduce the potential for the formation of stress fractures and improve the overall wear resistance of the three sided threads  34 . The threads  34  further include grooves  29  including the base portion  33  for receiving the three sided threads  38  having a shape complementary to the shape of the three sided threads  34  to establish the threaded connecting assembly  11  of FIG.  5 . 
     Due to improved structural strength and locking strength of the threads  34  and  38  (see FIG.  5 ), the number of threads necessary to secure the component parts of the threaded connecting assembly  11  together are reduced, typically to about two to four, preferably to three. A reduction in the number of threads in accordance with the present invention, reduces the number of screw-turns required to fully seat the first threaded connector  32  into the gas port  36 . The first threaded connector  32  is fully seated within the gas port  36  after about two to four, and preferably about three screw-turns. The rapid seating provides a quick fluid connection with minimal initial leakage of compressed gas from the threaded connecting assembly  11 , and further provides ergonomic convenience to the user especially to those who may suffer from arthritis or other disabilities associated with loss of manual dexterity. 
     Referring to FIG. 7, an exploded cross sectional view of the first threaded connector  32  illustrating a thread pattern  44  for a second embodiment of the present invention is shown. It will be understood that the corresponding gas port  36  of the threaded connecting assembly  11  for the second embodiment includes a complementary thread pattern which is synchronized with the thread pattern  44  as shown, such that a secure threaded engagement is achieved therebetween. 
     The three sided thread pattern  44  of the first threaded connector  32  includes a plurality of spaced apart three sided threads  46 , each having a flat top portion  48  and a pair of opposed sloping side portions  50  having grooves therebetween including respective base portions  52 . The sloping side portions  50  are oriented at an angle a measured from the vertical axis. The angle a is preferably within the range of from about 10° to 20°, and more preferably at about 15°. 
     The base portion  52 , located between respective side portions  50 , includes two or more of angled surfaces (two angle surfaces  54   a  and  54   b  are shown). Each of the surfaces  54   a  and  54   b  is slanted upwardly from a common point  56  to the respective side portion  50  at an angle β measured from the horizontal axis. The angle β is preferably within the range from about 6° to 18°, more preferably within the range of from about 10° to 14°, and most preferably at about 12°. The adjacent surfaces  54   a  and  54   b  in combination, form a groove  53  therebetween for receiving the complementarily shaped three sided threads of the corresponding gas port  36  as the two connectors are threadedly fastened to one another. During manufacturing, the configuration of the groove  53  serves to facilitate the removal of excess waste material formed between the threads  46  during the thread cutting process. 
     The profile of the three sided threads  46  provides the structural strength necessary to withstand the shearing forces associated with prolonged and repeated use. The sloping side portions  50  and the flat top portion  48  of the three sided thread  46 , in combination forms an outside corner  58  on each side thereof. The sloping side portion  50  and the corresponding angled surfaces  54   a ,  54   b  of the thread  46 , in combination form an inside corner  60  on each side thereof. The side portion  50  and the corresponding surface  54   a  or  54   b , are oriented at the angles α and β respectively, to form two facets for effectively distributing the shearing force in two directions through the material rather than concentrating the shearing in one area or region as observed in the prior art threaded fluid connection  9  of FIGS. 1-3. 
     Referring to FIG. 8A, the first threaded connector  32  is shown on the gas-containing cylinder  30  to establish the threaded connecting assembly  11  for a third embodiment of the present invention. The first threaded connector  32  includes a plurality of three sided threads  62  configured for threaded coupling with a gas port (not shown) having a complementary set of three sided threads for forming the threaded connecting assembly  11  of the present invention. In this embodiment, the first threaded connector  32  further includes a nose section  64  at an end thereof. The nose section  64  facilitates the seating of the first threaded connector  32  into the gas port  36  and onto the O-ring or gasket located therein for improved ease of use and better quality gas seal. 
     With reference to FIG. 8B, an exploded cross sectional view of a thread pattern referred generally by the reference numeral  66  of the first threaded connector  32  is shown. The three sided threads  62  include a narrow groove  68  with a flat horizontal base portion  73  disposed therebetween for receiving the complementarily shaped threads of the corresponding gas port  36 . Each thread  62  is provided with a top surface  70  having a curvilinear portion and substantially vertical side portions  72  which in combination establish a desirable profile for improved wear resistance and resistance to shearing forces associated with high pressure fluid connections. With reference to FIG. 8C, the thread  62  further includes corner portions  74  and  76  having a curvilinear shape. As described above, the curvilinear corner portions  74  and  76  resist stress fractures by uniformly distributing the shearing forces over the total surface of the corner portions  74  and  76  rather at select focused points as observed in prior art threaded connections. In this embodiment of the invention, the threads are press-formed by a metal rolling technique whereby the metal material is effectively shifted by pressure to form the corresponding threads and groove. Accordingly, the corner portion  74  includes a slight bulge caused by the displacement of the metal from the groove  68 . 
     The foregoing discussion discloses and describes merely exemplary embodiments of the present invention. One skilled in the art will readily recognize from such discussion, and from the accompanying drawings and claims, that various changes, modifications and variations can be made therein without departing from the spirit and scope of the invention as defined in the following claims.