MONOLITHIC FUEL DELIVERY SYSTEM

Abstract

A monolithic fuel delivery system for gasoline direct injection to an engine. The system has a common rail tube body from which injector sockets smoothly and seamlessly extend. Uninterrupted junctions are formed between the rail tube body and the injector sockets. The seamless junctions present a sealed relationship between the tube body and the injector sockets.

Claims

1. A monolithic fuel delivery system for gasoline direct injection to an engine, the system comprising a common rail tube body with a longitudinal axis, an internal and an external wall, an upstream end and a downstream end, the tube body having one or more passages extending between the internal and external walls; one or more injector sockets that are adapted to extend seamlessly from the one or more passages, each injector socket having a proximal end region extending from the tube body and a distal end region through which fuel is delivered to the engine, seamless junctions being formed between the tube body and the injector sockets, the seamless junctions presenting a sealed relationship between the tube body and the injector sockets; and one or more mounting bosses that seamlessly extend from the fuel rail body for securing the fuel delivery system to the engine, wherein the one or more injector sockets and the one or more mounting bosses are aligned.

2. (canceled)

3. The monolithic fuel delivery system of claim 1, wherein the fuel is injected into the engine at pressures up to 5000 psi.

4. The monolithic fuel delivery system of claim 1 made by a 3-D printing process.

5. The monolithic fuel delivery system of claim 1 wherein there are 3 injector sockets.

6. The monolithic fuel delivery system of claim 1 wherein there are 4 injector sockets.

7. The monolithic fuel delivery system of claim 1 wherein there are 6 injector sockets.

8. The monolithic fuel delivery system of claim 1 wherein there are 3 mounting bosses.

9. The monolithic fuel delivery system of claim 1 wherein there are 4 mounting bosses.

10. The monolithic fuel delivery system of claim 1 wherein there are 6 mounting bosses.

11. The monolithic fuel delivery system of claim 1 wherein there are 2 sets of 3 injector sockets for a 6-cylinder engine with 3 sockets on each side of the fuel rail body.

12. The monolithic fuel delivery system of claim 1 wherein there are 2 sets of 4 injector sockets for an 8-cylinder engine with 4 sockets on each side of the fuel rail body.

13. The monolithic fuel delivery system of claim 1 wherein there are 2 sets of 3 mounting bosses for a 6-cylinder engine with 3 mounting bosses on each side of the fuel rail body.

14. The monolithic fuel delivery system of claim 1 wherein there are 2 sets of 4 mounting bosses for an 8-cylinder engine with 4 mounting bosses on each side of the fuel rail body.

15. The monolithic fuel delivery system of claim 1, further comprising end threads defined in the internal wall at the upstream and downstream ends of the tube; a fuel inlet with threads that engage the upstream end thread at the upstream end of the tube; and an end cap or pressure sensor boss with threads that engage the downstream end thread at the downstream end of the tube.

16. The monolithic fuel delivery system of claim 1, made by a 3-D printing method.

17. The monolithic fuel delivery system of claim 1, made by a laser printing method.

18. A method of making the monolithic fuel delivery system of claim 1, comprising the steps of: preparing a CAD drawing of the fuel rail body, injector sockets and mounting bosses extending therefrom, wherein the injector sockets and the mounting bosses are aligned; communicating design details of the fuel rail, injector sockets and mounting bosses to a 3-D printer; building a green part component by extruding rods of metal powder and a binder through a nozzle and printing layer by layer; delivering the green part component to a de-binder that prepares green parts for sintering by using a fluid solution to remove a wax portion and produce a brown part; and forwarding the brown part to a furnace that uses a hybrid application of conventional heating and microwave energy to densify the brown part by removing the binder through evaporation, thus fusing metal particles together.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] FIG. 1 is a quartering perspective view of a monolithic fuel rail according to one embodiment of the invention;

[0019] FIG. 2 is a top view thereof;

[0020] FIG. 3 is a back side view thereof;

[0021] FIG. 3A is a sectional view taken along the line A-A in FIG. 3;

[0022] FIG. 4 is an end view of a monolithic fuel rail; and

[0023] FIG. 5 is a sectional view taken along the line B-B in FIG. 4.

DETAILED DESCRIPTION OF THE INVENTION

[0024] One aspect of this disclosure involves gasoline direct injection fuel delivery systems that are made preferably by 3-D or laser printing and operate under pressures that may be as high as 35 MPa (5000 PSI). One design objective is to provide a monolithic, single piece fuel delivery system with a rail body 10 from which one or more injector sockets 12 extend to withstand increased pressure and performance requirements (FIGS. 1-5).

[0025] As described further below, one departure from conventional approaches and structures includes a method of making a one-piece structure that includes unifying the injector sockets 12 and the fuel rail body 10 so that there is no intermediate joint or seam from that may induce turbulent flow or from which fluid under high pressure may leak. A brazing step is no longer used. Injector sockets need no longer to be screwed into the fuel rail body. The disclosed structure and its method of making allow safe and reliable operation under high fuel rail pressures and provide structural reliability while decreasing fuel delivery system complexity.

[0026] The Article of Manufacture

[0027] In one form, the present disclosure relates to a fuel delivery system including a rail body 10 with integral fuel injector sockets 12 for supplying high-pressure fuel from fuel booster pumps through a tube inlet 11. Fuel is directly injected into engine cylinders 13 through one or more fuel injection nozzles that extend from the injector sockets 12.

[0028] One embodiment of a fuel delivery system for gasoline direct injection of fuel to an engine includes a common rail tube body 10 with internal 14 and external 16 walls (FIG. 4), an upstream end 18 and a downstream end 20. The tube 10 has threaded passages only at the upstream and downstream ends. There are no threads, joints or seams that secure the injector sockets to the rail body because the injector sockets extend from the fuel rail body as a one-piece construction (further described below).

[0029] One consequence of the disclosed fuel delivery system is that it presents internal fluid conduits that have smooth walls. As a result, fluid flow is relatively unobstructed. Back pressures and flow disturbance that would otherwise be caused by internal wall discontinuities are avoided.

[0030] Each of the injector sockets 12 receives an injector that has a proximal end region 22 that forms a junction that seamlessly extends from the tube body 10 and a distal end region 24 which is juxtaposed with an engine cylinder 13. It will be appreciated that the number of injector sockets will vary depending on the number of engine cylinders to which fuel is delivered, e.g., 4 for a 4-cylinder engine and 2×3 for a 6-cylinder engine with 3 sockets on each side of the fuel rail body and 2× for an 8-cylinder engine 4 with 4 sockets on each side of the fuel rail body Similarly, for the number of mounting bosses.

[0031] To secure the one-piece fuel delivery system 10 to an engine block 13, one or more mounting bosses 50 seamlessly extend from the rail body 20.

[0032] In some embodiments, the fuel rail assembly has end threads defined in the internal wall at the upstream 18 and downstream ends 20 of the tube 10. A fuel inlet with threads engages the upstream end thread at the upstream end 18 of the tube 10. An end cap sensor boss with threads engages the downstream end thread at the downstream end 20 of the tube.

[0033] Method of Making

[0034] A preferred method of making the disclosed fuel delivery system is by 3-D printing. In one approach to additive manufacturing, a monolithic fuel delivery system is made, preferably by a 3-D metal printing process using a Studio System offered by Desktop Metal of Burlington, Mass. See, www.desktopmetal.com/products/studio, the disclosure of which is incorporated by reference. To create complex metal parts, a typical system includes a printer, a de-binder and a furnace. Each of the three hardware components of the system is controlled by cloud-connected software.

[0035] Beginning with a monolithic fuel delivery system design in a native CAD format, the printer builds a green part component by extruding rods of metal powder and a binder (feedstock) through a nozzle and prints layer by layer in precise geometric shapes. The de-binder prepares green parts for sintering by using a fluid solution to remove a wax portion and produce a brown part. The furnace sinter may use a hybrid application of conventional heating and microwave energy to densify the brown part by removing the binder through evaporation, thus fusing metal particles together. If desired, multiple furnaces could be associated with one printer.

[0036] To achieve high resolution, tolerances in the fabricated monolithic fuel delivery system are expected to be up to two thousandths of an inch per inch, with densities around 96-99 percent. Materials to be handled by the Studio System may include 17-4 PH Stainless, 316L Stainless, H13 Tool Steel, 4140 Chrome Moly, Inconel 625 Superalloy and Kovar F-15. Other materials are under development for use in serial production in an additive manufacturing environment.

[0037] The disclosed additive manufacturing process allows for designs that currently cannot be achieved with a one-piece forged rail approach.

[0038] Another possible manufacturing technique is to use laser printing.

[0039] As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention.

[0040] While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. Additionally, the features of various implementing embodiments may be combined to form further embodiments of the invention.