Abstract:
A fluid fitting is provided for connecting two members transmitting a high pressure fluid. The fitting includes an elongated tubular stem, a first connecting member, and a second connecting member. A hydraulic seal may be effected by an interference fit between the second connecting member and the stem. The first connecting member may be a flare nut. The second connecting member may be a plug fitting. The fluid fitting preferably provides a connection between a fuel oil valve and an oil burner nozzle. The valve may be rigidly mounted to the burner nozzle without the use of additional mounting hardware and within a small space adjacent to the burner.

Description:
FIELD OF THE INVENTION 
     This invention relates to fluid fittings, and in particular, to fluid fittings used as a connector to effect a hydraulic seal for transmitting pressurized fluid. 
     BACKGROUND OF THE INVENTION 
     Fluid fittings, such as connectors between two members transmitting a fluid, are common and used in many industrial, commercial, and residential applications. The actual fluid transmitted through the connectors, the temperature of the fluid, and the pressure of the fluid are parameters that define the performance characteristics required by a fluid fitting. In certain applications, unique connector assemblies have been developed in the art, while in other applications, conventional hard plumbing connections are used. 
     Conventional fuel oil burners generally include a fuel supply line. Each fuel supply line is connected at one end to a fuel supply pump and terminates at the other end at a burner inlet nozzle. A valve used to regulate fuel flow is included in the fuel supply line. The fuel oil is typically pumped under relatively high pressures. It is conventional in the prior art to hard plumb the supply line from the fuel oil pump, to the valve, and to the burner inlet nozzle. The plumbing operation uses conventional elbow fittings, threaded fittings, and nipples to effect a sealed supply line. The use of conventional plumbing requires the supply line to transverse space outside the immediate burner proximity. 
     Conventional burners of this type often are installed within an application environment by an original equipment manufacturer. A design concern for burner suppliers is to limit the volumetric footprint of the burner. The less volume the burner assembly occupies, the more advantageous the burner is to the original equipment manufacturers. Another design concern for connectors of this type is to effect a hydraulic seal at high pressure. 
     Conventional connectors typically mount the valve at a relative distance away from and above the burner nozzle line. To hard mount the valve, additional mounting hardware parts are required. During the off-cycle of a burner, air tends to gather in the nozzle line of the burner. 
     The air tends to result in less-reliable burner light-offs and shut-downs. 
     Another concern with convention plumbing is that in-the-field maintenance requires disassembly of the plumbing connections in order to service the valve or the burner. The disassembly increases maintenance costs and equipment down time. 
     Thus, there is a need for a connector providing a hydraulic seal for transmitting high pressure fuel oil which allows the hard mounting of a valve without valve mounting parts required, while at the same time minimizing air trapped in a nozzle line, while providing a reduced volumetric footprint attractive to original equipment manufacturers. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a fluid fitting suitable for connecting first and second members that transmit pressurized fluid. The fitting effects a hydraulic seal. In a preferred embodiment, the connector is directed to providing a connection for a fuel oil line leading from a valve to an oil burner. The first member of the connection is a standard flare fitting leading to an inlet nozzle line feeding a burner. The second member is valve including a standard pipe fitting. 
     The fluid fitting comprises an elongated tubular stem a first connecting member (e.g. a nut), a second connecting member (e.g. a plug), and a hydraulic seal. The elongated tubular stem comprises a first end portion having a first outer diameter, a flange having a second outer diameter and disposed at a second end portion of the stem, and an intermediate portion axially spaced between the first end portion and the flange. The intermediate portion has an outer diameter. A shoulder is disposed between the intermediate portion and the first end portion. An internal fluid passageway extends throughout the stem. The second diameter is larger than the intermediate portion diameter, while the intermediate portion diameter is larger than the first diameter. 
     The first connecting member comprises an inner opening extending therethrough that receives the intermediate portion of the stem and permits relative rotation between the first connecting member and the stem. An internal abutment surface engages the flange and prevents axial movement of the first connecting member on the stem. A threaded portion is adapted to engage threads of the first member to be connected to the fitting. A polygonal shaped exterior tool engaging surface is included. In a preferred embodiment, the first connecting member is a flare nut sized to engage a standard flare fitting. 
     The second connecting member comprises an inner opening extending therethrough which receives the first end portion of the stem. A threaded portion is adapted to engage threads of the second member to be connected to the fitting. An abutment face at one end engages the shoulder of the elongated tubular stem. A polygonal shaped exterior tool engaging surface is included. In a preferred embodiment, the second connecting member is a tapered pipe fitting. 
     The hydraulic seal may be comprised by an internal diameter of the inner opening of the second connecting member and the first diameter of the stem being sized effective to form an interference fit between the second connecting member and the first end portion of the elongated tubular stem. 
     In a preferred embodiment, the threaded portion of the first connecting member may comprise threads disposed on an internal surface and the threaded portion of the second connecting member comprises threads disposed on an external surface. An axial length of the first end portion of the stem may be longer than an axial length of said second connecting member. A diameter of the second member may be larger than a diameter of the first member, as in the case of an internal diameter of a threaded opening of a valve (second member) which is larger than an external diameter of a threaded nipple on a flare fitting (first member). 
     The invention also comprises the combination of the valve connector, the valve, and the flare fitting attached to a fuel conduit of a burner. 
     A method for assembling a fluid fitting assembly, suitable for connecting first and second members that contain pressurized fluid, comprises the first step of providing an elongated tubular stem according to the present invention. A first connecting member according to the present invention is oriented such that the threaded portion of the first connecting member is directed toward the first end portion of the elongated stem. The first connecting member is slipped over the first end portion such that the flange of the elongated tubular stem contacts the internal abutment surface of the first connecting member. 
     A second connecting member is oriented such that the threaded portion of the second connecting portion is directed away from the first end portion of the elongated stem. The first end portion is inserted into the interior opening of the second connecting member such that the second connecting member contacts the shoulder of the elongated tubular stem. 
     The threaded portion of said first connecting member is connected to a threaded portion of the first member. The threaded portion of the second connecting member is connected to a threaded portion of the second member. 
     In a preferred embodiment, the first end portion of the stem is staked onto a tapered end of the second connecting member by the use of a tool. 
     The present invention offers advantages over connectors available in the prior art. A connector in accordance with the present invention permits a valve to be rigidly mounted to a nozzle line feeding an oil burner without the use of any additional valve mounting hardware. During the off-cycle of a burner, air tends to gather in the nozzle line of the burner. A connector assembled in accordance with the present invention can be rigidly mounted at the height of the nozzle line. Mounting in this location advantageously minimizes air trapped in the nozzle line. Further, the valve may be mounted within the limited spacing directly adjacent the burner, minimizing unused space and an overall volume occupied by the burner system. No connector in the prior art permits this accomplishment. 
     Many additional features, advantages and a fuller understanding of the invention will be had from the accompanying drawings and the detailed description that follows. It should be understood that the above Summary of the Invention describes the invention in broad terms while the following Detailed Description of Preferred Embodiments describes the invention more narrowly and presents preferred embodiments which should not be construed as necessary limitations of the broad invention as defined in the claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a plan view of a fluid fitting assembled in accordance with the present invention; 
     FIG. 2A is a vertical cross-sectional view of the elongated tubular stem shown in FIG. 1 as seen approximately from a plane taken along the lines  2 A— 2 A of FIG. 2B; 
     FIG. 2B is an axial view of the elongated tubular stem of FIG. 2A; 
     FIG. 3A is a vertical cross-sectional view of the flare nut shown in FIG. 1 as seen approximately from a plane taken along the lines  3 A— 3 A of FIG. 3B; 
     FIG. 3B is an axial view of the flare nut of FIG. 3A; 
     FIG. 4A is a vertical cross-sectional view of the plug fitting shown in FIG. 1 as seen approximately form a plane taken along the lines  4 A— 4 A of FIG. 4B; 
     FIG. 4B is an axial view of the plug fitting of FIG. 4A; 
     FIG. 5 is a perspective view of a 45° flare fitting to which the flare nut of FIG. 3A will be connected in accordance with the present invention; 
     FIG. 6 is a plan view of a valve to which the plug fitting of FIG. 4A will be assembled in accordance with the present invention; 
     FIG. 7A is a perspective view of a fluid fitting assembled in accordance with the present invention after a staking method step has been performed on the plug fitting; 
     FIG. 7B is a perspective view of a fluid fitting assembled in accordance with the present invention after an alternative staking method step has been performed on the plug fitting; and 
     FIG. 8 is a perspective view of a burner assembly, including a connector, a valve, and a fuel conduit, constructed in accordance with the present invention. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring to FIG. 1, the illustrated fluid fitting  10  is a connector assembly. The connector is utilized to connect a first member to a second member. The connector  10  includes an elongated tubular stem  20  inserted first through a first connecting member  40 , and then through a second connecting member  60 . The assembled fluid fitting  10  includes an internal passageway  12  through which fluid may pass. In the preferred embodiment, the first connecting member is a flare nut  40  and the second connecting member is a plug fitting  60 . The flare nut  40  connects to a flare fitting  70 , as shown in FIG. 5, and the plug fitting  60  connects to an internal fitting of a valve  80 , as shown in FIG.  6 . The connector  10  effects a hydraulic seal suitable for transmitting highly pressurized fluids. In the preferred embodiment, the first member is a flare fitting and the second member is a valve. The fuel oil is transmitted under pressure from a pump, through a valve to the connector  10 , and to a flare fitting, which leads to a nozzle of an oil burner. 
     Referring to FIG. 2A, a vertical cross-sectional view of an elongated tubular stem  20  is shown as seen approximately from a plane taken along the lines  2 A— 2 A of FIG.  2 B. The elongated tubular stem  20  includes a first end portion  22 , a flange  24  disposed at a second end portion of the stem, and an intermediate portion  26  axially spaced between the first end portion  22  and the flange  24 . The first end portion has a first diameter D 1 , while the flange has a diameter D f , and the intermediate portion has a diameter D m . As shown in FIG. 2A, the flange outer diameter D f  is larger than the intermediate portion outer diameter D m , while the diameter D m  of the intermediate portion is larger than the first end portion outer diameter D 1 . The first end portion  22  has a length L 1 , which will be discussed in more detail later. In the preferred embodiment, the length L 1  is 0.590 inches. 
     An internal passageway  28  extends through the tubular stem  20  and offers a travel path for fluids. In the. preferred embodiment, fluid flows within the internal passageway  28  from the first end portion in the direction of the flange. A shoulder  30  is disposed between the intermediate portion  26  and the first end portion  22 . 
     The internal passageway  28  expands in cross-sectional area within the flange  24 . The flange  24  includes a flared exit orifice defined by a conical shaped mating surface  32 . The orifice expands to an exit diameter D r  larger than the diameter of the internal passageway  28 . The exit orifice is formed by the conical surface  32  at an acute angle with respect to a longitudinal axis A of the tubular stem  20 . In the preferred embodiment, the mating face  32  is angled at 45° with respect to the longitudinal axis A. It should be appreciated by those skilled in the art, that other angles may be used. As shown in FIG. 2A, the orifice diameter D r  is less than the flange diameter D f . In the preferred embodiment, the flange diameter Df is 0.330 inches while the orifice diameter D r  is 0.282 inches. 
     Referring to FIG. 3A, a vertical cross-sectional view of a first connecting member  40  is shown as seen approximately from.a plane taken along the lines  3 A- 3 A of FIG.  3 B. In the preferred embodiment, the first connecting member is a flare nut fitting  40 . The flare nut  40  includes an inner opening  42  extending throughout the flare nut. During the assembly of the connector  10 , the inner opening  42  receives the intermediate portion  26  of the tubular stem  20  and permits relative rotation between the flare nut  40  and the tubular stem  20 . The first connecting member  40  includes a threaded portion  44  adapted to engage threads  72  of a first member  70 , as shown in FIG. 5, to be connected to the first connecting member  40 . In the preferred embodiment, the threads  44  are disposed on an internal surface of the flare nut  40 . As shown in FIG. 3A, a portion of the inner opening  42  includes an internally threaded region  44 . 
     An internal abutment surface  46  is included in the flare nut. As the first end portion  22  of the tubular stem  20  is inserted into the threaded section of the flare nut  40 , the abutment surface  46  engages the flange  24  and prevents further axial movement of the flare nut  40  on the tubular stem  20 . A polygonal shaped exterior tool engaging surface  48  is included. In the preferred embodiment, the engaging surface  48  forms a conventional-hexagon as shown in FIG.  3 B. 
     Referring to FIG. 4A, a vertical cross-sectional view of a second connecting member  60  is shown as seen approximately from a plane taken along the lines  4 A- 4 A of FIG.  4 B. In the preferred embodiment, the second connecting member is a plug fitting  60 . The plug fitting  60  includes an inner opening  62  extending throughout its length. The inner opening is defined by a diameter D p . During the assembly of the connector  10 , the inner opening  62  receives the first end portion  22  of the tubular stem  20 . A hydraulic seal is effected by the interference fit wherein the internal diameter D p  of the inner opening of the second connecting member is approximately the same as the diameter D 1  of the first end portion  22  of the elongated tube stem  20 . The interference fit prohibits rotational movement between the plug fitting  60  and the tubular stem  20 . In the preferred embodiment, the diameter D p  of the inner opening is slightly less than the outer diameter D 1  of the tubular stem first end portion  22 . 
     As shown in FIG. 4A, the diameter D p  of the inner opening may range from 0.2000 to 0.2007 inches. As shown in FIG. 2A, the outer diameter D 1  of the first end portion may range from 0.2012 to 0.2017 inches. Therefore, the interference may range from a minimum of 0.0005 inches to a maximum of 0.0017 inches. It should be understood by those skilled in the art that the above ranges are exemplary and other minimum and maximum ranges of interference may be used. 
     The second connecting member  60  includes a threaded portion  64  adapted to engage threads  82  of a second member  80 , as shown in FIG. 6, to be connected to the connector  10 . In the preferred embodiment, the threads  64  are disposed on an external surface of the plug fitting  60 . As shown in FIG. 4A, a portion of the plug  60  includes an externally threaded region  64 . 
     An abutment face  66  at one end of the plug  60  engages the shoulder  30  of the tubular stem  20 . The plug  60 , includes a polygonal shaped exterior tool engaging surface  68 . In the preferred embodiment, the engaging surface  68  forms a conventional hexagon as shown in FIG.  4 B. 
     In the preferred embodiment, the axial length L 1  of the first end portion  22  is longer than the axial length L p  of the plug fitting  60 . As shown in FIG. 4A, the axial length L p  of the plug  60  is 0.560 inches. The axial length L 1  of the first end portion  22  is 0.590 inches as shown in FIG.  2 A. In other words, after the interference fit is made, the first end portion protrudes a certain distance, (e.g. 0.030 inches), beyond the plug fitting  60 . It should be understood by those skilled in the art that the length of this protrusion is exemplary and may vary. The protrusion will be discussed in more detail later. 
     The connector  10  as described allows for a first member with a diameter to be connected to a second member with a diameter, where the diameter of the second member is larger than the diameter of the first member. No other similar interference fit type fluid fitting assembly in the prior art teaches this type of connection. 
     A method for assembling a fluid fitting in accordance with the present invention, suitable for connecting first and second members that contain pressurized fluid, includes several mechanical operational steps. The elongated tubular stem is provided in accordance with the present invention. The first connecting member according to the present invention is oriented such that the threaded portion of the first connecting member is directed toward the first end portion of the elongated stem. In the preferred embodiment, the first connecting member is a flare nut. The flare nut  40  is slipped over the first end portion  22  such that the flange  24  of the elongated stem contacts the internal abutment surface  46  of the flare nut  40 . 
     The second connecting member is oriented such that the threaded portion of the second connecting portion is directed away from the first end portion of the elongated stem. In the preferred embodiment, the second connecting member is a plug fitting  60 . The first end portion  22  is inserted into the interior opening of the plug fitting  60  such that abutment face  66  of the plug fitting  60  contacts the shoulder  30  of the elongated stem. Either a mechanical or hydraulic press with customized tooling may be used to perform the insertion. An interference fit is formed to effect a hydraulic seal. The connector  10  as assembled in accordance with the present invention is shown in FIG.  1 . 
     The connection of the first and second members may be performed after the connector  10  assembly is complete. The threaded portion of the second connecting member is connected to a threaded portion of the second member. In the preferred embodiment, the second member is a standard threaded fitting  82  of a valve  80  as shown in FIG.  6 . The external threaded portion  64  of the plug fitting  60  is connected to the internal threaded fitting  82  of the valve  80 . An operator engages the polygonal shaped exterior tool engaging surface  68  to complete the connection. The plug fitting  60  is rotatably connected to the valve  80  under sufficient torque known in the art. 
     Prior to connecting the connector assembly  10  to the valve  80 , a staking operation may be performed to prevent the plug from moving off the stem. In a preferred embodiment, the protrusion of the first end portion  22  of the stem is staked, i e. deformed under force, into a tapered void in the plug fitting by the use of a tool. One possible resulting connection  90  is shown in FIG.  7 A. In the preferred embodiment, a tool with a cross member resembling a Phillips head screwdriver is used to apply force to the protrusion. Alternatively, a rounded solid tool may be used, producing the circumferential style staked connection  95  shown in FIG.  7 B. The staking operation provides an added security by restricting relative motion of the stem  20  with the plug  60 , thus ensuring a fluid tight fitting. Other staking methods known to those skilled in the art may also be used. 
     The threaded portion of the first connecting member is connected to a threaded portion of the first member. In the preferred embodiment, the first member is a flare fitting as shown in FIG.  5 . The internal threaded portion  44  of the flare nut  40  is connected to an external threaded portion  72  of the flare fitting  70 . An operator engages the polygonal shaped exterior tool engaging surface  48  to complete the connection. The flare nut  40  is rotatably connected to the flare fitting  70  until the conical shaped mating surface  32  of the flare nut contact the conical shaped mating surface  74  of the flare fitting. After sufficient torque is applied to the polygonal shaped exterior tool engaging surface  48 , a fluid tight seal is achieved. Neither a gasket nor any sealing material is required to achieve the fluid tight seal. 
     The hydraulic sealed connector been tested to pressures of 1000 psig. Further, UL specified pressure and torque tests have been performed. All test data indicates the connector effects an hydraulic seal. The results have been consistent using an elongated stem constructed of brass or steel, although other metals may be used. 
     The tool engaging surfaces  48 ,  68  allow the connector  10  to be connected to the first and second member within a limited volumetric space. Prior art connections have required repeated 360° rotation of the flare elbow fitting, which is eliminated in this connection method. 
     The invention also comprises the combination of the valve connector, the valve and the flare fitting attached to a fuel conduit of a burner. Referring to FIG. 8, a burner assembly  100  comprising a burner, a valve connector  10 , a first member, a second member, a fuel pump, and a fuel conduit is shown. In a preferred embodiment, the first member is a flare fitting. The flare fitting, which is the end of the inlet nozzle line of the burner, connects to the flare nut. The second member is a fuel control valve. The valve comprises two internal threaded connections. The valve connects the fuel conduit leading from a fuel pump on one end and to the plug fitting on the other end. 
     Many modifications and variations of the invention will be apparent to those of ordinary skill in the art in light of the foregoing disclosure. Therefore, it is to be understood that, within the scope of the appended claims, the invention can be practiced otherwise than has been specifically shown and described.