Patent Publication Number: US-6711898-B2

Title: Fuel manifold block and ring with macrolaminate layers

Description:
RELATED CASES 
     This application is a continuation-in-part of U.S. patent application Ser. No. 10/125,301, filed Apr. 17, 2002; which is a continuation of U.S. patent application Ser. No. 09/976,948, filed Oct. 12, 2001 abandoned; which is a continuation of U.S. patent application Ser. No. 09/361,954, filed Jul. 27, 1999, now U.S. Pat. No. 6,321,541; which claims priority to U.S. Provisional Application Ser. No. 60/127,307; filed Apr. 1, 1999 and U.S. Provisional Application Ser. No. 60/127,993; filed Apr. 6, 1999, the disclosures of all of which are incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to fuel injectors, and more particularly, to fuel injectors useful for gas turbine combustion engines. 
     BACKGROUND OF THE INVENTION 
     Fuel injector assemblies useful for such applications as gas turbine combustion engines, direct pressurized fuel from a manifold to one or more combustion chambers. Fuel injectors also function to prepare the fuel for mixing with air prior to combustion. Each injector typically has an inlet fitting connected either directly or via tubing to the manifold, a tubular extension or stem connected at one end to the fitting, and one or more spray nozzles connected to the other end of the stem for directing the fuel into the combustion chamber. A fuel passage (e.g., a tube or cylindrical passage) extends through the stem to supply the fuel from the inlet fitting to the nozzle. Appropriate valves and/or flow dividers can be provided to direct and control the flow of fuel through the nozzle. The fuel injectors are often placed in an evenly-spaced annular arrangement to dispense (spray) fuel in a uniform manner into the combustor chamber. Additional concentric and/or series combustion chambers each require their own arrangements of nozzles that can be supported separately or on common stems. The fuel provided by the injectors is mixed with air and ignited, so that the expanding gases of combustion can, for example, move rapidly across and rotate turbine blades in a gas turbine engine to power an aircraft, or in other appropriate manners in other combustion applications. 
     A fuel injector typically includes one or more heat shields surrounding the portion of the stem and nozzle exposed to the heat of the combustion chamber. The heat shields are considered necessary because of the high temperature within the combustion chamber during operation and after shut-down, and prevent the fuel from breaking down into solid deposits (i.e., “coking”) which occurs when the wetted walls in a fuel passage exceed a maximum temperature (approximately 400° F. (200° C.) for typical jet fuel). The coke in the fuel nozzle can build up and restrict fuel flow through the fuel nozzle rendering the nozzle inefficient or unusable. 
     One particularly useful heat shield assembly is shown in Stotts, U.S. Pat. No. 5,598,696, owned by the assignee of the present application. This heat shield assembly includes a pair of U-shaped heat shield members secured together to form an enclosure for the stem portion of the fuel injector. At least one flexible clip member secures the heat shield members to the injector at about the midpoint of the injector stem. The upper end of the heat shield is sized to tightly receive an enlarged neck of the injector to prevent combustion gas from flowing between the heat shield members and the stem. The clip member thermally isolates the heat shield members from the injector stem. The flexibility of the clip member permits thermal expansion between the heat shield members and the stem during thermal cycling, while minimizing the mechanical stresses at the attachment points. 
     Another useful stem and heat shield assembly is shown in Pelletier, U.S. patent application Ser. No. 09/031,871, filed Feb. 27, 1998, and also owned by the assignee of the present application. In this heat shield assembly, the fuel tube is completely enclosed in the injector stem such that a stagnant air (dry territory) gap is provided around the tube. The fuel tube is fixedly attached at its inlet end and its outlet end to the inlet fitting and nozzle, respectively, and includes a coiled or convoluted portion which absorbs the mechanical stresses generated by differences in thermal expansion of the internal nozzle component parts and the external nozzle component parts during combustion and shut-down. 
     Many fuel tubes also require secondary seals (such as elastomeric seals) and/or sliding surfaces to properly seal the heat shield to the fuel tube during the extreme operating conditions occurring during thermal cycling. 
     While such heat shield assemblies as described above are useful in certain applications, they require a number of components, and additional manufacturing and assembly steps, which can increase the overall cost of the injector, both in terms of original purchase as well as a continuing maintenance. In addition, the heat shield assemblies can take up valuable space in and around the combustion chamber, block air flow to the combustor, and add weight to the engine. This can all be undesirable with current industry demands requiring reduced cost, smaller injector size (“envelope”) and reduced weight for more efficient operation. 
     Because of limited fuel pressure availability and a wide range of required fuel flow, many fuel injectors include pilot and secondary nozzles, with only the pilot nozzles being used during start-up, and both nozzles being used during higher power operation. The flow to the secondary nozzles is reduced or stopped during start-up and lower power operation. Such injectors can be more efficient and cleaner-burning than single nozzle fuel injectors, as the fuel flow can be more accurately controlled and the fuel spray more accurately directed for the particular combustor requirement. The pilot and secondary nozzles can be contained within the same nozzle stem assembly or can be supported in separate nozzle assemblies. Dual nozzle fuel injectors can also be constructed to allow further control of the fuel for dual combustors, providing even greater fuel efficiency and reduction of harmful emissions. 
     As should be appreciated, fuel injectors with pilot and secondary nozzles require complex and sophisticated routing of the fuel to the spray orifices in the nozzle. The fuel not only has to be routed through the nozzle portion of the fuel injector, but also through the stem, and in some applications, through upstream tubing connecting the injector to the manifold. Such routing becomes all the more complex with multiple fuel circuits, and in multiple nozzle arrangements, where multiple nozzles are fed along a common stem. The routing also becomes more complex if cooling circuits are included to cool the tubing and the injector. 
     A typical technique for routing fuel through the stem portion of the fuel injector is to provide concentric passages within the stem, with the fuel being routed separately through different passages. The fuel is then directed through passages and/or annular channels in the nozzle portion of the injector to the spray orifice(s). Mains, U.S. Pat. No. 5,413,178, for example, which is also owned by the assignee of the present application, shows concentric passages where the pilot fuel stream is routed down and back along the secondary nozzle for cooling purposes. This can also require a number of components, and additional manufacturing and assembly steps, which can all be contrary to the demands of cost reduction and weight, and small injector envelope. 
     With current trends toward developing even more efficient and cleaner-burning combustors, it is a continuing challenge to develop improved fuel injector assemblies to properly deliver fuel to a combustion chamber for operation of the gas turbine engine, and which will fit into a small envelope, have a reduced weight, fewer components, and can be manufactured and assembled in an economical manner. 
     SUMMARY OF THE PRESENT INVENTION 
     The present invention provides a novel and unique fuel injector assembly for directing fuel from a manifold and dispensing the fuel within the combustion chamber of a combustion engine. The fuel injector assembly can include multiple fuel circuits, single or multiple nozzle assemblies, and cooling circuits. The injector assembly overall has few components for weight reduction and thereby increased fuel efficiency. The fuel injector assembly of the present invention also fits within a small envelope and is economical to manufacture and assemble. In many applications, the fuel injector assembly reduces the need for heat shielding around the assembly, for additional reliability, weight and cost reduction. The fuel injector assembly is particularly useful for gas turbine combustion engines on aircraft, but can also be useful in other combustion applications, such as in ground vehicles and stationary applications. 
     According to one embodiment of the present invention, the fuel injector includes an inlet fitting, a stem connected at one end to the inlet fitting, and one or more nozzle assemblies, connected to the other end of the stem and supported at or within the combustion chamber of the engine. An elongated feed strip extends through the stem to the nozzle assemblies to supply fuel from the inlet fitting to the nozzle(s) in the nozzle assemblies. The upstream end of the feed strip can be directly attached (such as by brazing or welding) to the inlet fitting without additional sealing components (such as elastomeric seals). The downstream end of the feed strip is preferably connected in a unitary (one-piece) manner to the nozzle. The feed strip has convolutions along its length to provide increased relative displacement flexibility along the axis of the stem and reduce stresses caused by differential thermal expansion due to the extreme temperatures in the combustion chamber. The need for additional heat shielding of the stem portion of the injector can therefore be reduced, if not eliminated in many applications. 
     The feed strip and nozzle are preferably formed from a plurality of plates. Each plate includes an elongated, feed strip portion and a unitary head (nozzle) portion, substantially perpendicular to the feed strip portion. Passages and openings in the plates are formed by selectively etching the surfaces of the plates. The plates are then arranged in surface-to-surface contact with each other and fixed together such as by brazing or diffusion bonding, to form an integral structure. Selectively etching the plates allows multiple fuel circuits, single or multiple nozzle assemblies and cooling circuits to be easily provided in the injector. The etching process also allows multiple fuel paths and cooling circuits to be created in a relatively small cross-section, thereby reducing the size of the injector. 
     The feed strip portion of the plate assembly is then mechanically formed (bent) to provide the convoluted form. In one form of the invention the plates all have a T-shape in plan view. In this form, the head portions of the plate assembly can be mechanically formed (bent) into a cylinder, or other appropriate shape. The ends of the head can be spaced apart from one another, or can be brought together and joined, such as by brazing or welding. Spray orifices are provided on the radially outer surface, radially inner surface and/or ends of the cylindrical nozzle to direct fuel radially outward, radially inward and/or axially from the nozzle. The integral feed strip and nozzle unit requires only a small envelope, is economical to manufacture and assemble, and it is believed will have reduced maintenance and service costs over time. 
     According to a second embodiment, an elongated feed strip extends from the manifold to a remote connection with one or more fuel injectors. In a preferred form, the feed strip fluidly interconnects multiple fuel injectors, which are arranged for directing fuel into the combustor. The upstream end of the feed strip can be attached (such as by brazing or welding) directly to the manifold, or can be directly attached to a connector block (by brazing or welding), which itself is connected to the manifold (such as by bolts). As in the first embodiment, the feed strip is formed of multiple plates arranged in surface-to-surface adjacent relation with one another, preferably with etched passages providing fluid flow between the plates, and can have a convoluted form, which allow the injector assembly to be fit into tight envelopes and reduces stresses causes by differential thermal expansion. The strip can have passages for cooling purposes, which reduces, if not eliminates, the heatshielding requirements of the feed strip. 
     According to a further aspect of this embodiment, a manifold block can be attached to the manifold and direct fuel in multiple pathways to the feed strip. The manifold block is preferably also formed of multiple plates, arranged in surface-to-surface relation with one another, and having multiple internal passages formed such as by etching the plates. A plurality of passages can be formed having different flow characteristics, which can control the flow through the feed strip to the nozzles. The feed strip can be directly attached to the manifold (such as by brazing or welding), or if a connector block is used, the connector block can be attached to the manifold block such as with bolts, to allow removal and inspection/replacement of the feed strip and associated injector(s). 
     Thus, as described above, a novel and unique fuel injector assembly for combustion engines is provided which directs fuel from a manifold to a combustion chamber. The fuel injector assembly is economical to manufacture and assemble, and can be incorporated into a small envelope. The injector assembly has few components for weight reduction, which thereby increases the fuel efficiency of the engine. 
     Further features and advantages of the present invention will become apparent to those skilled in the art upon reviewing the following specification and attached drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an elevated perspective view of the inlet into a dual concentric combustion chamber for a gas turbine engine, showing a fuel injector assembly constructed according to the principles of the present invention; 
     FIG. 2 is an elevated perspective view of a fuel injector for the engine of FIG. 1; 
     FIG. 3 is a cross-sectional side view of the fuel injector of FIG. 2; 
     FIG. 4 is an elevated perspective view of a first integral fuel feed strip and nozzle unit for the fuel injector of FIG. 2; 
     FIG. 5A is a plan view of the inner surface of a first plate for the fuel feed and injection unit of FIG. 4; 
     FIG. 5B is a plan view of the outer surface of the plate of FIG. 5A; 
     FIG. 6A is a plan view of the inner surface of a second plate for the unit of FIG. 4; 
     FIG. 6B is a plan view of the outer surface of the plate of FIG. 6A; 
     FIG. 7A is a plan view of the inner surface of a third plate for the unit of FIG. 4; 
     FIG. 7B is a plan view of the outer surface of the plate of FIG. 7A; 
     FIG. 8A is a plan view of the inner surface of a fourth plate for the unit of FIG. 4; 
     FIG. 8B is a plan view of the outer surface of the plate of FIG. 7A; 
     FIG. 9 is an enlarged cross-sectional side view of a portion of the fuel injector of FIG. 3; 
     FIG. 10 is an enlarged cross-sectional side view of a portion of the fuel feed and injection unit of the fuel injector; 
     FIG. 11 is a cross-sectional end view of the fuel injector taken substantially along the plane described by the lines  11 — 11  of FIG. 3; 
     FIG. 12 is an elevated perspective view of a second integral fuel feed strip and nozzle unit for the fuel injector of FIG. 2; 
     FIG. 13 is an elevated perspective view of a fuel injector assembly constructed according to another embodiment of the present invention; 
     FIG. 14 is an elevated perspective view of the fuel injector assembly as of FIG. 13, shown with the fuel injectors removed; 
     FIG. 15 is an enlarged view of a portion of the fuel injector assembly of FIG. 14; 
     FIG. 16 is a top plan view of the right ring manifold portion of the manifold ring illustrated in FIG. 14; 
     FIG. 17 is a side view of the right ring manifold portion of FIG. 16; 
     FIG. 18 is a top plan view of the left ring manifold portion of the manifold ring illustrated in FIG. 14; 
     FIG. 19 is a side view of the left ring manifold portion of FIG. 18; 
     FIG. 20 is a schematic illustration of the inlet end of the right ring manifold portion, taken substantially along the plane described by the lines  20 — 20  of FIG. 16; 
     FIG. 21 is a schematic illustration of the inlet end of the left ring manifold portion, taken substantially along the plane described by the lines  21 — 21  of FIG. 18; 
     FIG. 22 is a side view of the connector block for the inlet end of the right ring manifold portion of FIG. 20; 
     FIG. 23 is an end view of the connector block of FIG. 22; 
     FIG. 24 is a cross-sectional end view of the right ring manifold portion taken substantially along the plane described by the lines  24 — 24  in FIG. 17; 
     FIG. 25 is an elevated perspective view of the manifold block for the fuel injector assembly of FIG. 13; 
     FIG. 26 is an end view of the manifold block of FIG. 25, showing the multiple plates of the manifold block; 
     FIG. 27 is a side view of the manifold block of FIG. 25, taken substantially along the plane described by the lines  27 — 27  of FIG. 26, illustrating certain internal passages in one of the plates; and 
     FIG. 28 is a cross-sectional side view of the feed strip, illustrating a connection with a fuel injector. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to the drawings and initially to FIG. 1, a portion of a combustion engine is indicated generally at  20 . The upstream, front wall of a dual combustion chamber for the engine is shown at  22 , and a plurality of fuel injectors, for example as indicated generally at  24 , are shown supported within the combustion chamber. The fuel injectors  24  atomize and direct fuel into the combustion chamber  22  for burning. Combustion chamber  22  can be any useful type of combustion chamber, such as a combustion chamber for a gas turbine combustion engine of an aircraft, however, the present invention is believed useful for combustion chambers for any type of combustion application, such as in land vehicles. In any case, the combustion chamber will not be described herein for sake of brevity, with the exception that as should be known to those skilled in the art, air at elevated temperatures (up to 1300° F. in the combustion chamber of an aircraft), is directed into the combustion chamber to allow combustion of the fuel. 
     As illustrated in FIG. 1, a dual nozzle arrangement for each injector is shown, where each of the fuel injectors  24  includes two nozzle assemblies for directing fuel into radially inner and outer zones of the combustion chamber. It should be noted that this multiple nozzle arrangement is only provided for exemplary purposes, and the present invention is useful with a single nozzle assembly, as well injectors having more than two nozzle assemblies in a concentric or series configuration. It should also be noted that while a number of such injectors are shown in an evenly-spaced annular arrangement, the number and location of such injectors can vary, depending upon the particular application. One of the advantages of the present invention it is that is useful with a variety of different injector configurations. 
     The fuel injectors  24  are typically identical. Referring now to FIGS. 2 and 3, each fuel injector  24  includes a nozzle mount or flange  30  adapted to be fixed and sealed to the wall of the combustor casing (such as with appropriate fasteners); a housing stem  32  integral or fixed to flange  30  (such as by brazing or welding); and one or more nozzle assemblies such as at  36 ,  37 , supported on stem  32 . Stem  32  includes an open inner chamber  39 . The various components of the fuel injector  24  are preferably formed from material appropriate for the particular application as should be known to those skilled in the art. 
     An inlet assembly, indicated generally at  41 , is disposed above or within the open upper end of chamber  39 , and is integral with or fixed to flange  30  such as by brazing. Inlet assembly  41  is also formed from material appropriate for the particular application and includes inlet ports  46 - 49  which are designed to fluidly connect with the fuel manifold (not shown) to direct fuel into the injector  24 . 
     Referring now to FIGS. 3,  4  and  9 , each of the nozzle assemblies  36 ,  37  is illustrated as including a pilot nozzle, indicated generally at  58 , and a secondary nozzle, indicated generally at  59 . Both nozzles  58 ,  59  are generally used during normal and extreme power situations, while only pilot nozzle  58  is generally used during start-up. Again, a pilot and secondary nozzle configuration is shown only for exemplary purposes, and it is within the scope of the present invention to provide only a single nozzle for each nozzle assembly  36 ,  37 , or for more than two nozzles for each nozzle assembly. 
     An elongated feed strip, indicated generally at  64 , provides fuel from inlet assembly  41  to nozzle assemblies  36 ,  37 . Feed strip  64  is an expandable feed strip formed from a material which can be exposed to combustor temperatures in the combustion chamber without being adversely affected. To this end, feed strip  64  has a convoluted (or tortuous) shape, and includes at least one, and preferably a plurality of laterally-extending, regular or irregular bends or waves as at  65 , along the longitudinal length of the strip from inlet end  66  to outlet end  69 . The convoluted shape allows expansion and contraction of the feed strip in response to thermal changes in the combustion chamber while reducing mechanical stresses within the injector. The convoluted feed strip thereby eliminates the need for additional heat shielding of the steam portion in many applications, although in some high-temperature situations an additional heat shield may still be necessary or desirable. 
     By the term “strip”, it is meant that the feed strip has an elongated, essentially flat shape (in cross-section), where the side surfaces  70 ,  71  of the strip are essentially parallel, and oppositely facing from each other; and the essentially perpendicular edges  72 ,  73  of the strip are also essentially parallel and oppositely-facing. The strip has essentially a rectangular shape in cross-section (as compared to the cylindrical shape of a typical fuel tube), although this shape could vary slightly depending upon manufacturing requirements and techniques. It is preferred that the feed strip have enough convolutions along the length of the strip to allow the strip to easily absorb thermal changes within the combustion chamber without providing undue stress on inlet assembly  41  and nozzle  59 . The strip should not have too many convolutions, however, as the strip may then exhibit resonant behavior in the combustion system. It is believed that the number and configuration of the convolutions appropriate for the particular application can be easily determined by simple experimentation, including analytical modeling and/or resonant frequency testing. 
     The strip  84  is shown as having its side surfaces substantially perpendicular to the direction of air flow through the combustion chamber. This may block some air flow through the combustor, and in appropriate applications, the strip may be aligned in the direction of air flow. 
     Feed strip  64  includes a plurality of inlet ports, where each port fluidly connects with inlet ports  46 - 49  in inlet assembly  41  to direct fuel into the feed strip. The inlet ports feed multiple fuel paths down the length of the strip to pilot nozzles  58  and secondary nozzles  59  in both nozzle assemblies  36 ,  37 , as well as provide cooling circuits for thermal control in both nozzle assemblies. For ease of manufacture and assembly, the feed strip  64  and secondary nozzle  59  are integrally connected to each other, and preferably formed unitarily with one another, to define a fuel feed strip and nozzle unit. 
     Referring now to FIGS. 5A-8B, the feed strip  64  and secondary nozzle  59  are preferably formed from relatively thin (e.g., 0.005-0.090 inches thick), flat, plates  76 - 79  which are located in adjacent, surface-to-surface contact with each other (see FIG.  10 ); with plate  76  being the innermost plate, and plate  79  being the outermost plate. The plates are each preferably formed in one piece from a metal sheet of an appropriate material such as INCONEL 600, and can be formed in the required configuration (such as the illustrated T-shape configuration) by durable etching, stamping or die-cutting. While four plates are illustrated and described, it is of course possible that a greater or lesser number of plates could be provided, and that the shape of the individual plates may be other than as illustrated, for example, the plates could all be simply in the form of a strip. It is also possible that the feed strip  64  and secondary nozzle  59  could be formed separately and then later attached together. However, to reduce the number of individual components and manufacturing and assembly steps, it is preferred that these components be formed together (unitarily) from one-piece plates. 
     As shown in FIGS. 5A and 5B, the first plate  76  has a longitudinally-extending feed portion  80  and a head nozzle portion  82 , extending substantially perpendicular to the feed portion  80 . An inlet opening  84  is provided for a first fuel circuit to the secondary nozzle  59  in both nozzle assemblies  36 ,  37 ; and an inlet opening  86  is provided for a second fuel circuit to the secondary nozzle  59  in both nozzle assemblies  36 ,  37 . An inlet opening  88  is provided for the first pilot nozzle  58  in nozzle assembly  36 ; while an inlet opening  89  is provided for the second pilot nozzle in the nozzle assembly  37 . An outlet opening  92  in head  82  is provided for fluid connection to the pilot nozzle  58  in the nozzle assembly  36 . 
     Openings  84 - 89  extend from the inner surface  90  to the outer surface  91  of plate  76  to fuel passages extending longitudinally through feed portion  80  toward head  82  on the outer surface  91  (see FIG.  5 B). Specifically, inlet opening  86  is fluidly connected to passages  94  and  96 , while inlet opening  84  is fluidly connected to passages  100 ,  101 . Passages  100 ,  101  are fluidly connected together by a short passage  102 . Passages  100 ,  101  fluidly connect to outwardly-projecting distribution passages  103 ,  104 , extending outwardly along head portion  82 . 
     Pilot inlet opening  89  is fluidly connected to a short flow passage  106 ; while pilot opening  88  is connected to flow passages  108  extending along the length of feed portion  80 . Surface  91  of plate  76  further includes partial flow passages  109 - 115 . 
     Referring now to FIG. 6A, plate  77  has an inner surface  120  which is located in adjacent, surface-to-surface contact with outer surface  91  of plate  76 . Plate  77  has substantially the same configuration as plate  76 , and includes a longitudinally-extending feed strip portion  121 , and a head (nozzle) portion  122 , substantially perpendicular to feed strip portion  121 . Inner surface  120  of plate  77  has a similar flow path configuration as surface  80  of plate  76 , including flow passages  124  and  126  aligned with flow passages  94  and  96 , respectively, in plate  76 ; flow passages  128 - 129  aligned with flow passages  100 ,  101 , respectively, in plate  76 ; flow passage  130  aligned with flow passage  106  in plate  76 ; and flow passages  132  aligned with flow passages  108  in plate  76 . A short flow passage  133  fluidly interconnects passages  128  and  129 . Flow passages  128  and  129  extend longitudinally to outward-projecting distribution passages  134 ,  136  in the head portion  122  of plate  77 , which are aligned with distribution passages  103 ,  104 , respectively, in plate  76 . An opening  137  is also provided in alignment with opening  92  in plate  76 . Plate  77  further includes partial flow passages  138 - 140  which are aligned with flow passages  109 - 111 , respectively in plate  76 ; and partial flow passages  141 - 143  which are aligned with partial flow passages  112 - 114  in plate  76 . A flow passage  142  is aligned with flow passage  115  in plate  76 . 
     The outer surface  148  (FIG. 6B) of plate  77  includes openings  152 - 155  which fluidly connect with passages  124 ,  126 ,  128 ,  130  and  129  (FIG.  6 A). Plate  77  further includes openings  160  fluidly connected to passages  126 ; openings  162  fluidly connected to passages  124 ; and openings  164  fluidly connected to passages  132 . Opening  165  is fluidly connected to one end of partial flow passage  142 . A passage  166  fluidly connects opening  137  with opening  165 . Plate  77  further includes openings  168 - 170  fluidly connected to one end of partial passages  138 - 140 , respectively. An opening  167  is provided to fluidly connect to one end of partial passage  142 . Openings  174 - 176  are connected to the other end of partial passages  138 - 140 , respectively. 
     Openings  181 - 183  are also provided which are fluidly connected to the other end of partial flow passages  141 - 143 , respectively. Openings  184 - 186  are fluidly connected to the other end of partial flow passages  141 - 143 , respectively. 
     A series of circular distribution chambers, as indicated generally at  190 , fluidly connect with flow distribution pathways  134  and  136 . 
     Referring now to FIGS. 7A and 7B, plate  78  is shown as also having a similar configuration in plan view, with a longitudinally-extending feed strip portion  200  and a head (nozzle) portion  202 , extending substantially perpendicular to feed portion  200 . 
     The inner surface  204  of plate  78  (FIG. 7A) is disposed in surface-to-surface contact with the outer surface  148  of plate  77 . Inner surface  204  includes an opening  208  which fluidly connects openings  153  and  155  in plate  77 . Opening  208  provides fluid communication between openings  153  and  155  in plate  77 , such that flow is provided along both branches of passages  100 ,  101  (FIG.  5 B). An opening  210  is also provided in alignment with opening  154  in plate  77 ; and an opening  212  is provided in alignment with opening  152  in plate  77 . Partial flow passages  213 - 215  are provided in fluid communication with openings  168 - 170 , respectively, in plate  77 . Partial flow passages  216 - 218  are provided in fluid communication with openings  181 - 183 , respectively in plate  77 . Openings  220  are provided in alignment with openings  164  in plate  77 . Openings  222 - 224  are also provided in alignment with openings  174 - 176 , respectively, in plate  77 ; while openings  225 - 227  are provided in alignment with openings  184 - 186 , respectively, in plate  77 . Opening  228  is provided in alignment with opening  167  in plate  77 . Opening  229  is in alignment with opening  137  in plate  77 . Distribution passages  230 ,  231 , project outward along head  202 , and are in fluid communication with openings  160 ,  162  in plate  77 . 
     Distribution flow passages  230 ,  231  feed a plurality of swirl chambers, such as at  232 , through non-radial feed passages, such as at  233 . Three non-radial feed passages  233  are provided for each swirl chamber  232 , and provide a vortex swirl to fuel flowing into the swirl chambers  232 . The distribution passages  230 ,  231  have a tapered configuration to ensure the even distribution of fuel to all of the feed passages  233  and swirl chambers  232 . 
     Plate  78  similarly includes swirl chambers as at  234 , which are in fluid communication with openings  190  in plate  77 . Non-radial flow passages  235  provide a vortex swirl to fuel flowing into the swirl chambers  234 . Two non-radial passages  235  are provided for each swirl chamber  234 . Openings  190  in plate  77  feed fuel to the non-radial flow passages  235 . 
     As shown in FIG. 7B, flow opening  208  fluidly connects to flow passages  242  on the outer surface  243  of plate  78 . Passages  242  extend along the feed strip portion  200  of plate  78 , and outward along the head portion  202 . Opening  210  fluidly connects to flow passages  244  which also extend along the feed strip portion  200  and then outward along the head portion  202 . Opening  212  is fluidly connected to passages  246  which also extend along the feed strip portion  200 , and then outward along the head portion  202 . Openings  222 - 224  and  225 - 227  are in fluid communication with the outer ends of passages  242 ,  244  and  246 , respectively. 
     Referring now to FIGS. 8A and 8B, plate  79  also has a similar configuration in plan view with a longitudinally-extending feed strip portion  248  and a head (nozzle) portion  250 , extending substantially perpendicular to the feed strip portion  248 . The inner surface  252  of plate  79  is in surface-to-surface contact with surface  243  of plate  78 . Surface  252  of plate  79  includes flow passages  256 - 258  which are in fluid alignment with passages  242 ,  244  and  246  in plate  78 . Opening  262  in head portion  250  of plate  79  is in fluid communication with opening  229  in plate  78 . Passages  264  in head portion  250  are in fluid communication with openings  220  in plate  78 . Circular openings such as  268  and  270  are in fluid communication with openings such as at  232  and  234 , respectively, in plate  78 . Fluid passages  264  surround openings  268 ,  269  in a circuitous manner for cooling purposes. Passages  132  (which feed passages  264 ) also cool the feed strip portion of the unit. The outer surface  274  of plate  79  (FIG. 7B) includes discharge orifices such as at  276 ,  278 , for openings  268 ,  270 , respectively. The number (and location) of discharge orifices  276 ,  278  can vary depending upon the particular application. Outlet openings  280 - 282  are provided in fluid communication with fluid passages  256 - 258 , respectively. 
     As should be appreciated, when plates  76 - 79  are disposed in surface-to-surface contact with each other, as described above, the flow openings and passages between the plates direct fuel from the inlet opening  84  (FIG. 5A) through fuel paths  283  (FIG. 11) formed by passages  100 ,  101  in plate  76  and passages  128 ,  129  in plate  77 , to spray discharge orifices such as at  276  (FIG.  8 B); and from inlet opening  86  (FIG. 5A) through fuel paths  284  (FIG. 11) formed by passages  94  and  96  in plate  76  and passages  124 ,  126  in plate  77 , to spray discharge orifices such as at  278  (FIG. 8B) to the first and second fuel circuits in nozzle assembly  36 . Fuel is also directed through fuel paths  285  (FIG. 11) formed by passages  242  in plate  78  and passages  256  in plate  79  to opening  280 ; and through fuel paths  286  (FIG. 11) formed by passages  246  in plate  78  and passages  258  in plate  79  to opening  282 , to the first and second fuel circuits in nozzle assembly  37 . Inlet opening  88  (FIG. 5A) directs fuel in a fuel path  287  (FIG. 11) formed by passages  108  in plate  76  and passages  132  in plate  77  to pilot outlet  262  (FIG. 8B) in nozzle assembly  36 ; while inlet opening  89  (FIG. 5A) directs fuel in a separate fuel path  288  (FIG. 15) formed by passages  244  in plate  78  and passages  257  in plate  79  to pilot outlet  281  (FIG.  8 B), in the other nozzle assembly  37 . 
     While the secondary nozzles in nozzle assemblies  36 ,  37  are described as being in series, that is, where the first circuit spray orifices  278  in nozzle assemblies  36  and  37  both receive fuel from inlet port  47 , and second circuit spray orifices  276  in nozzle assemblies  36  and  37  both receive fuel from inlet port  48 , these orifices could also be separately connected to separate inlet ports so that the circuits are separately controlled between the nozzle assemblies. This could be simply provided with additional openings and passages along the plates. 
     The flow passages, openings and various components of the spray devices in plates  76 - 79  can be formed in any appropriate manner, and it is preferred that they be formed by etching, such as chemical etching. The chemical etching of such plates should be known to those skilled in the art, and is described for example in Simmons, U.S. Pat. No. 5,435,884, which is hereby incorporated by reference. The etching of the plates allows the forming of very fine, well-defined and complex openings and passages, which allow multiple fuel circuits to be provided in the feed strip  64  and nozzle  59  while maintaining a small cross-section for these components. As should be appreciated from the Simmons patent, the hydraulically-natural shape of the swirl chambers, and of the feed passages into the swirl chambers and the discharge orifices form the swirl chambers, provide improved atomized sprays from the nozzles. 
     The plates  76 - 79  can be fixed together in an appropriate manner and it is preferred that the plates are fixed together in surface-to-surface contact with a bonding process such as brazing or diffusion bonding. Such bonding processes are well-know to those skilled in the art, and provide a very secure connection between the various plates. Diffusion bonding is particularly useful, as it causes boundary cross-over (atom interchange) between the adjacent layers. Diffusion bonding is provided through appropriate applications of heat and pressure, typically under an applied vacuum in an inert atmosphere. A more detailed discussion of diffusion bonding can be found, for example, in U.S. Pat. Nos. 5,484,977; 5,479,705; and 5,038,857, among others. 
     After the plates  76 - 79  are bonded together, the head portions of all the plates can be mechanically formed (bent) into an appropriate configuration, if necessary. As shown in FIG. 4, the head portions are illustrated as being formed into a cylindrical configuration. This can be accomplished using appropriate equipment, for example, a cylindrical mandrel or other appropriately-shaped tool. The bonding process (such as brazing or diffusion bonding) maintains the various plates in fixed relation with respect to one another during this forming step. The radially-outer distal ends of the plates (for example, radially-outer ends  290 ,  291  in FIG. 5A) can then be joined together by an appropriated process such as brazing or welding to form a continuously cylindrical nozzle, or the ends of the plates could be spaced apart from each other. The plates could also be formed into shapes other than cylindrical, or even provided without forming, in appropriate applications. 
     As should be appreciated, spray orifices such as at  276 ,  278  are provided around the radially-outer surface of the nozzle  59  in the illustrated embodiment to provide sprays of fuel radially-outward from the nozzle. However, by appropriate routing of the fuel passages between the plates, the spray orifices could likewise be formed in the radially-inner surface to direct fuel radially inward into the nozzle. It is likewise possible that the spray orifices could be formed at the axial downstream end of the nozzle  59 , if desirable. In fact, the nozzle could essentially be incorporated into the stem portion by forming orifices at the downstream end of the stem portion. The orifices could also be configured to direct the sprays in other than radial or axial directions, if necessary or desirable for a particular application. 
     As apparent in FIG. 4, an outlet flange  293  is formed by the multi-plate structure for connection to the pilot nozzle  58 . Outlet flange  293  includes opening  262  in plate  79  (FIG.  8 B), to direct fuel to the pilot nozzle in nozzle assembly  36 . Likewise an outlet flange  295  is formed for connection to nozzle assembly  37 . Outlet flange  295  includes openings  280 - 282  (FIG. 8B) to direct fuel to the pilot and secondary nozzles in nozzle assembly  37 . 
     As shown in FIG. 4, feed strip  64  has a series of lateral convolutions along the longitudinal length of the strip. The convolutions can be formed by conventional mechanical forming methods, such as placing the feed strip between the two surfaces of a convoluted die. Most if not all of the convolutions can be formed in the feed strip before the stem is assembled with the feed strip, although it may be necessary to form one or more convolutions during later assembly steps, in order that the stem  32  can be fitted over the feed strip. As indicated previously, it is preferred that at least one convolution be formed in the feed strip  64 , but it is more preferred that a plurality of convolutions be formed. Again, the convolutions allow axial expansion of the feed strip during the extreme operating conditions found in most combustion engines, and thereby reduce the mechanical stresses on the other components of the injector. 
     Appropriate heat shielding is provided for the nozzle assemblies  36 ,  37  of the injector. For example, referring now to FIG. 9, first and second cylindrical outer heat shields  300 ,  301  are received around the outer diameter of the nozzle portion  59 . Heat shields  300 ,  301  each include a plurality of openings  302  aligned with spray orifices  276  (FIG.  8 B); and a plurality of openings  304  aligned with spray discharge orifice  278  (FIG.  8 B). Heat shields  300 ,  301  can be fixed to stem  32  in an appropriate manner, such as by welding or brazing. An air gap as at  305  is provided between the first shield  300  and the second heat shield  301 . While not shown, inner heat shields can also be provided closely bounding the radially-inner surface of nozzle portion  59 . The inner and outer heat shields are preferably conventional in design, as should be appreciated by those skilled in the art. 
     The pilot nozzle  58  is also connected to nozzle  59 , and includes an inlet fuel tube  314  with an inner passage  316  which is fluidly connected to passage  262  (FIG. 8B) in plate  79  to receive fuel from the pilot flow circuit in the nozzle. Tube  314  is attached to flange  293  (FIG. 4) of nozzle  59  such as by brazing or welding. For purposes of clear understanding, pilot nozzle  58  is shown rotated 90° from its actual location. As can be seen in FIG. 4, attachment flange  293  is actually along the side of nozzle  59 . 
     A cylindrical heat shield  318  surrounds tube  314 , and includes an air gap  320  for cooling purposes. Heat shield  318  is attached to stem  32  in an appropriate manner. Pilot nozzle  58  can be any appropriate nozzle configuration, and preferably includes an outer shroud  322  integral (in one piece) with heat shield  318 , and any other appropriate heat shield layers. While pilot nozzle  58  is illustrated as a simple jet spray nozzle, the pilot nozzle can have any configuration as necessary, to provide fuel in a stream or spray (such as a swirling spray). A plug  336  is then connected to the upstream end of shroud  322  after the pilot nozzle is properly connected and positioned. 
     After stem  32  is connected to heat shields  300 ,  301 , any final convolution(s) in the feed strip can then be formed. The support flange  30  can then be attached to stem  32 , such as by brazing or welding or other appropriate attachment technique, and inlet assembly  41  can be fitted into the support flange  30 , and attached thereto. Inlet assembly  41  is also attached to feed strip  64  (such as by brazing or welding) to provide a fluid-tight structure, with the inlet ports  46 - 49  in inlet assembly  41  in fluid alignment with the inlet openings  84 ,  86 ,  88 ,  89 , respectively, in the feed strip. As should be appreciated, the fixed attachment between the feed strip  64  and the inlet assembly  41 , and between the feed strip and nozzle  59 , is provided without seals (such as elastomer seals) or sliding components. This reduces the chance of leak paths, and provides a dry tertiary chamber  39 . This is useful as fuel is thereby prevented from entering the chamber and coking over time. 
     The second nozzle assembly  37  can then be attached to the first nozzle assembly  36 . As shown in FIG. 12, the second nozzle assembly  37  also includes a secondary nozzle  340  with a unitary feed strip  342 . Feed strip  342  includes an inlet end  343  which is fluidly connected to an inlet assembly, indicated generally at  346  in FIG. 3, which itself is fluidly connected to the outlet openings  280 - 282  (FIG. 8B) in plate  79 . Inlet assembly  346 , like inlet assembly  41 , includes inlet ports to fluidly connect the outlet openings of nozzle assembly  37  with the inlet openings in feed strip  342 . 
     Feed strip  342  and second nozzle  340  of nozzle assembly  37  are preferably formed in a similar manner as feed strip  64  and secondary nozzle  59  of nozzle assembly  36 . The flow passages through feed strip  64  and secondary nozzle  59  of nozzle assembly  37  are essentially the same (except that only one pilot fuel circuit is provided), and will not be described in detail. Feed strip  342  includes a generally right-angle bend  345  in its connection with nozzle  344 , which serves to absorb mechanical stresses in the nozzle assembly  37  due to thermal cycling. Multiple convolutions are generally not necessary in feed strip  342 , as this feed strip is shorter than feed strip  64 , and because of space constraints, although multiple convolutions can certainly be provided in appropriate applications. 
     Nozzle  37  is supported with respect to nozzle  36  by first and second stem portions  348 ,  350  which are connected together by an appropriate method, such as by brazing or welding. Appropriate inner and outer heat shields can be provided for nozzle  340 , as described above with respect to nozzle  59 , and also will not be described for sake of brevity. A pilot nozzle, generally indicated at  356 , is also supported within nozzle assembly  37 . Pilot nozzle  356  is also preferably the same as the pilot nozzle  58  in nozzle assembly  36 , and also will not be described. Pilot nozzle  356  is fluidly connected to outlet flange  357  in secondary nozzle  340 , in the same manner as described with respect to pilot nozzle  58 . 
     As should be appreciated, air at elevated temperatures is provided around the nozzles. When fuel passes through the pilot nozzle  58 , the fuel leaves the nozzle, and is impacted by the air. The fuel/air mixture then passes out through the nozzle for burning in the combustion chamber. 
     The secondary nozzle  59 , as described above, provides a radially outward directed spray through either (or both) sets of spray orifices  276 ,  278  (FIG.  8 B), depending upon whether fuel is provided to either or both of the fuel circuits. The outward-directed spray is impacted by and directed downstream by air within the combustion chamber and is then ignited. The fuel in passages  264  assist in cooling the nozzle area surrounding openings  268 ,  269 ; while the fuel in passages  132  (as well as the other passages in the stem) assist in cooling the feed strip portion of the injector. 
     Again, while a dual nozzle configuration is shown, such a structure is only for exemplary purposes, and it is possible that only a single nozzle assembly can be provided in an annular configuration (or otherwise) for each injector; and each nozzle can have only a single nozzle, rather than separate pilot and secondary nozzles. Likewise, while a radially outer spray from the secondary nozzle is shown, the spray can likewise be radially inward, or even axially outward away from the end of the nozzle. 
     According to a further embodiment of the present invention shown in FIGS. 13-15, one or more elongated feed strips  360  are provided to direct fuel from a fuel manifold (not shown) to a remote connection with one or more fuel injectors, indicated generally at  362 . The injectors  362  can be mounted in any appropriate manner, and are illustrated as being connected by a mounting ring  364 , which itself is attached in an appropriate manner to the combustor casing or other structural location. 
     The injectors in this embodiment can be conventional injectors, or can be the multi-plate injectors described above, depending upon the particular application. 
     In a preferred form of the invention, a pair of feed strips  366 ,  367  are provided, which each fluidly interconnect multiple fuel injectors via tubing as at  368 . The upstream end of each feed strip can be attached (such as by brazing or welding) directly to the manifold, or can be attached to a connector block  370  (by brazing or welding). The connector block  370  can be directly connected to the manifold (such as with bolts), or as will be described more fully below, can be connected to a manifold block  372 , which itself is connected to the manifold. 
     As in the first embodiment, each feed strip is formed of multiple plates arranged in surface-to-surface adjacent relation with one another, preferably with etched passages in at least one of the plates providing fluid flow between the plates. The plates are then fixed together in a permanent, fluid-tight manner, such as by diffusion bonding. For example, referring now to FIGS. 16,  17 ,  20  and  24 , the fuel feed strip portion  366 , illustrated extending from the right side of the manifold block in FIG. 13, includes multiple plates  373 - 376 , arranged in surface-to-surface adjacent relation with one another. The feed strip  366  has an inlet end  377  with a series of inlet openings as at  378  in the side surface of the strip fluidly connected to respective internal passages as at  379 . The internal passages  379  are formed along one or more of the plates (see, e.g., FIG. 24) and extend along the strip to appropriate outlet opening locations along the length of the strip for the tubing  368  fluidly interconnecting the strip with a respective fuel injector. 
     The number of internal fuel passages in each strip is dictated by the number of injectors it is desired to separately feed from the feed strip, and the number of fuel circuits required for each injector. As can be appreciated, etching of the internal fuel passages in the feed strip, in the manner described previously, is a repeatable, precise process which allows multiple passages to be formed along the strip to feed multiple injectors, while minimizing the outer dimensions of the feed strip. In addition, the etching process allows the fuel passages to be individually tailored to the required fuel flow through each passage for its respective injector. This allows significant control of the fuel dispensed through each injector. 
     The right side feed strip portion  366  is formed from a material (e.g., an appropriate stainless steel). The strip can have a convoluted or tortuous shape (such as like a “ribbon”), which allows the injector assembly to be fit into tight envelopes and reduces stresses causes by differential thermal expansion. As described above, the number and configurations of the convolutions appropriate for the particular application can be easily determined by simple experimentation. In addition, while only four plates are shown and described for feed strip  366 , it should be understood that the feed strip can have additional (or fewer) plates, depending on the number of fuel passages and/or the thermal control requirements. 
     The other feed strip portion  367 , illustrated in FIG. 13 as extending from the left side of the manifold block, is similar in construction to the right side feed strip portion  366 , and will not be described in detail for sake of brevity. As shown in FIG. 21, the inlet end  380  of the left side feed strip portion  367  also includes a plurality of inlet openings as at  382  which direct fuel along respective internal passages as at  384 , to appropriate outlet openings along the length of the strip. 
     Each strip can have passages, such as at  390  in FIGS. 20,  21  and  24 , along the sides of the strips and between adjacent plates, creating stagnant air pockets for cooling purposes, that is, to reduce the wetted wall temperatures of the adjacent fuel passages. Cooling fluid (air, etc.) can also be routed up and down these passages for thermal control, if necessary or desirable. This can reduce, if not eliminate, the heatshielding requirements of the feed strip. 
     Referring now to FIGS. 22 and 23, the connector block  370  preferably has a flat base  396  with openings as at  398  for bolting or otherwise attaching the connector block to the manifold block; and a box-shaped body or enclosure  399 . Inlet openings  400  are provided in base  396 , and are fluidly-interconnected by respective cross-passages  401  with outlet openings  402  in the flat side surface  403  of the body of the connector block. The side surface at the inlet end  379 / 380  of the respective strip is located against the outer, flat side surface  403 , with the inlet openings  378 / 382  in the respective strip fluidly aligned with the respective inlet openings  402  in the connector block. The feed strip is then permanently fixed to the block such as by face brazing to form a fluid-tight connection. The connector block is used to facilitate the attachment of the feed strips to the manifold, but may not be necessary in every application, such as if the feed strip is directly connected to the manifold block, or to the manifold. 
     While the feed strip is shown having inlet openings along a side surface, it is possible that the inlet openings could be at an axial end of the strip, in which case the outlet openings in the connector block would be moved appropriately. 
     Referring now to FIGS. 25-27, the manifold block  372  is attached to the manifold and directs fuel in multiple pathways to the respective feed strip via the connector block. The manifold block  372  includes a flat base  410  with appropriate holes as at  412  for bolts or other attachment means; and a body  414  projecting outwardly, preferably perpendicular to the base  410 . Inlet openings  416 ,  417  are formed in base  410 , and internal flow passages as at  418  fluidly interconnect the inlet openings  416 ,  417  with appropriate outlet openings  420  along the side surface of body  414 . Two inlet openings  416 ,  417  are illustrated in FIG. 25, fluidly interconnecting fourteen outlet openings. The fluid passages  418  intersect at the respective inlet opening  416 ,  417 , and then branch off to a respective outlet opening. In the illustrated example shown in FIG. 26, inlet opening  416  feeds six outlet openings for the left side fuel manifold ring portion  367 ; while inlet opening  417  feeds eight outlet openings for the right side fuel manifold ring portion  366 . The number of fluid passages and outlet openings can vary depending upon the particular application (e.g., the number of separate fluid circuits and the desired fluid flow). It is also possible in certain applications that a single inlet opening will be provided for all the outlet openings, or that separate inlet openings will be required for each respective outlet opening. 
     The manifold block  372  is preferably of a multi-piece design, with a first, side piece  424  being of solid, one-piece construction and including a portion of the body  414  and the base  410 ; a second, base piece  426  also being of a solid, one-piece construction; and a third, side piece  428  being of a multi-plate construction, with the plates being arranged in surface-to-surface relation with one another, and having multiple internal passages (see, e.g., FIG. 27) formed such as by etching at least one of the plates, in the manner as described previously. The separate pieces of the manifold block can be fixed together in a permanent, fluid-tight manner, such as by diffusion bonding. The third, side piece  428  includes inlet openings  416 ,  417 , in base  410 , while the first, side piece  424  can have cross-bores as at  429  drilled therethrough to fluidly connect the outlet openings  420  in the side of the body  414  with the respective internal fuel passage  418  in the third piece  428 . A plurality of passages can thereby be formed through the manifold block having different flow characteristics, which can control the flow through the feed strip to the nozzles. 
     As with the plates of the fuel feed strip, the etching process of the plates in the manifold block allows the fuel passages to be individually tailored to the required fuel flow through each passage for its respective injector. This allows further control of the fuel dispensed through each injector. Alternatively or in addition to varying the passage dimensions, a restrictor as at  438  can be provided in bores  429  to control the flow through the passage. As before, the number of plates of the third side piece  428  can vary depending on the number of fluid circuits and the desired flow. While an etched, multi-plate manifold box is preferred, it is also possible that at least some of the benefits of the present invention may be realized with a single-piece manifold, where the passages are mechanically formed (e.g., drilled). 
     In any case, the connector block  370  is mounted on the side of the body  414  of the manifold block  410 , with the outlet openings  420  in the side of the manifold block fluidly aligned with the respective inlet openings  396  (FIG. 23) in the connector block. As illustrated in FIG. 15, the base of one connector block for the right fuel manifold ring portion  366  is attached to one location on the side surface of the manifold body  414 , and attached thereto (such as with bolts) at a location such that fuel flow through certain of the outlet openings  420  is directed into the feed strip  366 ; while the base of the connector block for the left fuel manifold ring portion  367  is attached to another location on the side surface of the manifold body  414 , and attached thereto (such as with bolts) at a location such that fuel flow through other of the outlet openings  420  is directed into the feed strip  367 . 
     Referring finally to FIG. 28, one of the tubular sections  368  for the fuel injectors is illustrated, and is shown extending through one of the outlet openings  439  in one of the feed strips and fluidly-connecting with a fuel passage  379 / 384  in the feed strip. A braze ring  440  is shown fixedly connecting the tubing to the side of the feed strip in a fluid-tight manner. 
     As should be appreciated, the feed strips, connector block and manifold block provide significant advantages in controlling the flow to the fuel injectors. If desirable, the flow characteristics for each injector can be fine tuned to increase the efficiency of the engine. The multi-plate designs and etched passages are also repeatable and accurate, for consistent manufacturing and assembly. The connector block can also be easily removed from the manifold block for inspection of the injectors and/or the feed strip. 
     Thus, as described above, the present invention provides a novel and unique fuel injector assembly for a combustion engine, and particularly a gas turbine combustion engine, which can include multiple fuel circuits, single or multiple nozzle assemblies, and cooling circuits. The injector assembly overall has few components for weight reduction and thereby increased fuel efficiency. The fuel injector assembly fits within a small envelope and is economical to manufacture and assemble. 
     The principles, preferred embodiments and modes of operation of the present invention have been described in the foregoing specification. The invention which is intended to be protected herein should not, however, be construed as limited to the particular form described as it is to be regarded as illustrative rather than restrictive. Variations and changes may be made by those skilled in the art without departing from the scope and spirit of the invention as set forth in the appended claims.