Patent Application
20140000563
The present disclosure relates generally to dual fuel common rail systems, and more particularly to a coaxial quill assembly that includes a matched pair of outer and inner quills kept together during pre-installation handling with a retainer.
Co-owned U.S. Patent application publication 2012/0055448 shows a co-axial quill assembly for a dual fuel common rail system in which inner and outer quills sealingly engage a common conical seat on individual fuel injectors. That references teaches the utilization of separate loading devices to ensure that the inner and outer quills sealingly engage the fuel injector despite dimensional tolerance variations that would be expected during the manufacture of the individual inner and outer quills, fuel injector and other engine components. While such a strategy may permit any outer quill to be matched with any inner quill at the time the fuel system is assembled to an engine, the separate loading strategy for each quill may be cumbersome and occupy more space than desirable in and around the engine.
The present disclosure is directed toward one or more of the problems set forth above.
In one aspect, a coaxial quill assembly includes an outer quill with a first dimension along a centerline. An inner quill is positioned inside the outer quill and has a second dimension along the centerline. The outer quill and the inner quill are a matched pair such that the first dimension and the second dimension have a difference corresponding to a fuel system dimensional specification. The inner quill defines a first fuel passage, and a second fuel passage is defined by and between the inner quill and the outer quill. A retainer is positioned in, but not obstructing, the second fuel passage in frictional contact with an interior surface of the outer quill and an exterior surface of the inner quill. The retainer permits movement of the first quill relative to the second quill along the centerline with an application of an adjustment force, but resists separation of the first quill from the second quill absent a forced disassembly.
In another aspect, a dual fuel common rail fuel system includes a first common rail, a second common rail, and a plurality of fuel injectors that each define a first fuel inlet and a second fuel inlet that open through a common conical seat. A plurality of quill assemblies each defines first and second fuel passages that fluidly connect the first common rail and the second common rail, respectively, to an individual one of the fuel injectors. Each of the quill assemblies includes matched inner and outer quills that are out of contact with each other but retained together during pre-installation handling by a retainer positioned in the second fuel passage. The match is based on a first dimension of the outer quill and a second dimension of the inner quill having a difference corresponding to a fuel system dimensional specification that causes both the inner and outer quills to sealingly engage the common conical seat. The retainer resists separation of the first quill from the second quill absent a forced disassembly during pre-installation handling, but is inert to operation of the fuel system.
In still another aspect, a method of assembling a fuel system includes pre-assembling a plurality of quill assemblies by matching inner and outer quills for each quill assembly. The match is based on a first dimension of the outer quill and a second dimension of the inner quill having a difference corresponding to a fuel system dimensional specification that causes both the inner and outer quills to sealingly engage a common conical seat of one of the fuel injectors. A first common rail and a second common rail are fluidly connected to the plurality of fuel injectors with a plurality of quill assemblies. The matched inner and outer quills are retained together during pre-installation handling with a retainer positioned between the inner and outer quills. The retainers are left in place between their respective inner and outer quills after the rails are fluidly connected to the fuel injectors.
Referring initially to
The retainer 60 resists separation of the inner quill 40 from its matched outer quill 50 absent a forced disassembly during pre-installation handling. However, after installation, the retainer 60 may be inert to operation of the fuel system 11. Forced disassembly means that the matched quill pair 40, 50 will not accidently separate, such as by being dropped or maybe even mishandled. The forced disassembly requires an intent and maybe a tool(s) to separate one of the inner quill 40 and outer quill 50 from the retainer 60. Being inert to the operation of the fuel system 11 means that fuel flows through or past the retainer 60 without interfering with the flow to the fuel injectors 20.
The inner quill 40 has a spherical end 46 that is in contact with the common conical seat 23 at a gage line 48. In addition, the outer quill 50 includes a spherically shaped end 53 that is also in contact with common conical seat 23 at a gage line 54. The previously identified fuel system dimensional specification that causes the inner and outer quills 40, 50 to sealingly engage the common conical seat 23 may be prescribed by a specific distance “b” along a centerline 25 between gage line 48 and gage line 54.
In the illustrated embodiment, the inner quill 40 has another spherical end 45 that defines an inlet 43 to the first fuel passage 41. As shown in
As stated earlier, the first common rail 13 may contain a liquid fuel, such as distillate diesel fuel, and the second common rail 14 may contain a gaseous fuel, such as natural gas. Nevertheless, those skilled in the art will appreciate that first and second common rails 13 and 14 could include different liquid fuels, or possibly even the same liquid fuels at different pressures without departing from the present disclosure.
Referring more specifically to
Depending upon the structure of coaxial quill assembly 30, the difference S may include a distance “b” along centerline 25 between a first gage line 54 of the outer quill 50 and a second gage line 48 of the inner quill 40. The outer quill 50 may include a spherically shaped end 53 that includes gage line 54, and inner quill 40 may also have a spherically shaped end 46 that includes the gage line 48. The dimension D2, of the example embodiment shown corresponds to the distance between gage line 48 and gage line 47 on inner quill 40 along centerline 25. The first dimension D1 may correspond to a distance along centerline 25 between a first end of outer quill 50 and the gage line 54 at outlet 55. In this specific embodiment, the first dimension D1 is less than a length L1 of the outer quill 50 along centerline 25. In addition in the specific embodiment, the second dimension D2 is less than a length L2 of the inner quill 40 along centerline 25.
The inner quill 40 may have spherical shaped ends 45 and 46 that define an inlet 43 and an outlet 44, respectively, to the first fuel passage 41. The outer quill 50 also has a spherically shaped end 53 that defines an outlet 55 from the second fuel passage 51.
The dimension “a” in
Referring specifically to
Because achieving sealing contact of both inner quill 40 and outer quill 50 at common conical seat 23 of fuel injector 20 is sensitive to the geometry at the contact location(s), one might expect at least one outer quill 50 of at least one quill assembly 30 would not be a match for an inner quill 40 of at least one other quill assembly 30 in a typical engine 10. Thus, although the inner quills 40 and the outer quills 50 in the fuel system 11 may have slightly different dimensions from one another, the matched pairs all have a common fuel system dimensional specification. The retainers 60 of each quill assembly 30 may comprise an identical piece, such as spring steel, that is elastically deformed between the inner quill 40 and the outer quill 50. As stated earlier, in the specific embodiment illustrated, the retainer 60 is illustrated, for example, as each being an identical piece of spring steel that defines an open square shape 61 around centerline 25.
The present disclosure relates generally to fuel systems which need to bring two fuels that differ in at least one of identification, pressure and liquid or gaseous state from each other. The present disclosure finds specific application to fuel systems that supply liquid compression ignition fuel and natural gas fuel for combustion in an engine 10. The present disclosure is specifically applicable to supplying fuels to fuel injectors 20 through an individual opening, for instance, in the engine head of engine 10. Finally, the present disclosure finds specific application to a strategy for matching inner and outer quills 40, 50 and retaining them together with a retainer 60 during pre-installation handling.
In one aspect, a method of assembling a fuel system 11 includes pre-assembling a plurality of quill assemblies 30. Each preassembled quill assembly 30 includes a matching pair of an inner quill 40 with an outer quill 50 that is based on a first dimension D1 of the outer quill 50 and a second dimension D2 of the inner quill 40 having a difference S corresponding to a fuel system dimensional specification that causes both the inner and outer quills 40, 50 to sealingly engage a common conical seat 23 of one of the fuel injectors 20 in the fuel system 11. A first common rail 13 and a second common rail 14 are fluidly connected to fuel injectors 20 with the plurality of quill assemblies 30. Each matched inner and outer quill pair 40, 50 is retained together during pre-installation handling with a retainer 60 positioned between the inner and outer quills 40, 50. The retainers 60 are left in place between the respective inner and outer quills 40, 50 after the fluid connect step is completed by installing fuel system 11 in an engine 10.
By preassembling matched pairs of inner and outer quills 40, 50, the assembly of the fuel system 11 to engine 10 can be simplified and streamlined by avoiding specific adjustment features, while still ensuring that each quill 40, 50 sealingly engages the common conical seat 23 of a fuel injector 20. By having specific matched dimensional pairs, any pair should properly be installable and inter-changeable with any of the engine cylinders 12 of engine 10 despite the fact that one could expect at least one outer quill 50 of at least one quill assembly 30 to not match at least one inner quill 40 of another quill assembly 30.
It should be understood that the above description is intended for illustrative purposes only, and is not intended to limit the scope of the present disclosure in any way. Thus, those skilled in the art will appreciate that other aspects of the disclosure can be obtained from a study of the drawings, the disclosure and the appended claims.
