THREADED FUEL RAILS

Abstract

A fuel rail assembly for gasoline direct injection fuel delivery to an engine. The assembly has a common rail tube. In the tube there are threaded orifices extending laterally. Injector sockets are adapted to mate with the threaded orifices. Each injector socket has a proximal nipple end region connected to the tube and a distal end region through which fuel is delivered to the engine. Screw threads are disposed around the proximal nipple end region. The screw threads include a lead thread that is received by the threaded orifices, thereby forming mechanical connections between the injector sockets and the tube that are adapted to withstand maximum pressures of fuel up tp 2900 psi.

Claims

1. A fuel rail assembly for gasoline direct injection fuel delivery to an engine, the assembly comprising a common rail tube with a longitudinal axis, internal and external walls, an upstream end and a downstream end, the tube having one or more threaded orifices extending between the internal and external walls; and one or more injector sockets that are adapted to mate with the threaded orifices, each injector socket having a proximal nipple end region connected to the tube and a distal end region through which fuel is delivered to the engine; screw threads disposed around the proximal nipple end region, the screw threads including a lead thread, the screw threads being received by the one or more threaded orifices, thereby forming one or more mechanical connections between the injector sockets and the tube that are adapted to withstand a maximum pressure of fuel; an orientation notch provided in the distal end region of at least some of the injector sockets, the lead thread of an injector socket being formed so that it is pre-aligned with an associated orientation notch, the orientation notch being located in relation to the longitudinal axis after threading engagement of the proximal nipple end regions of the one or more injector sockets with the tube at a pre-defined angular position in relation to the longitudinal axis of the tube after torquing the injector sockets to seal the mechanical connections thereby formed between the tube and the injector sockets.

2. The fuel rail assembly 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 sensor boss with threads that engage the downstream end thread at the downstream end of the tube.

3. The fuel rail assembly of claim 1 wherein imaginary centers of the one or more threaded orifices are aligned with the longitudinal axis.

4. The fuel rail assembly of claim 1, further comprising end threads defined in the internal wall at the upstream end of the tube; and a fuel inlet with threads that engage the upstream end thread at the upstream end of the tube.

5. The fuel rail assembly of claim 1, further comprising end threads defined in the internal wall at the downstream ends of the tube; and an end cap sensor boss with threads that engage the downstream end thread at the downstream end of the tube.

6. The fuel rail assembly of claim 1, wherein the maximum pressure is 2900 psi.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] FIG. 1 is a quartering perspective view of a threaded fuel rail assembly according to one embodiment of the invention;

[0016] FIG. 2 is a top view thereof;

[0017] FIG. 3 is a longitudinal sectional view taken along the line 3-3 in FIG. 2;

[0018] FIG. 4 is a sectional view of the fuel rail assembly taken along the line 4-4 in FIGS. 2 and 5; and

[0019] FIG. 5 is an enlargement of one representative injection socket shown in FIG. 3.

DETAILED DESCRIPTION OF THE INVENTION

[0020] One aspect of this disclosure involves gasoline direct injection fuel delivery systems that operate under pressures that may be as high as 35 MPa (5000 PSI). Preferably, precisely oriented screw threads are provided on the components to be assembled. This allows for process control that will ensure a reliable connection between a tube 10 and an injector socket 12 that can withstand the increased pressure and performance requirements (FIGS. 1-5). As described further below, one departure from conventional approaches and structures includes the method of attachment of the injectors 12 to the tube 10. A brazing step is no longer used. The disclosed attachment method allows safe and reliable operation under high rail pressures and provides structural reliability while decreasing rail cost.

[0021] In one form, the present disclosure relates to a fuel rail (a delivery pipe, 10) for supplying high-pressure fuel from fuel booster pumps through an inlet 11. Fuel is injected through a fuel injector (an injection nozzle, 12) directly into an engine cylinder 13.

[0022] One embodiment of a fuel rail assembly for gasoline direct injection fuel delivery to an engine includes a common rail tube 10 with internal 14 and external 16 walls, an upstream end 18 and a downstream end 20. The tube 10 has one or more threaded orifices 21 extending between the internal and external walls 14, 16. Injector sockets 12 are threadingly engaged with the orifices 32.

[0023] Each of the injector sockets 12 has a proximal nipple end region 22 to be connected to the tube 10 and a distal end region 24. Screw threads 26 are disposed around the proximal nipple end region 22. The screw threads 26 begin with a lead thread which mates with a lead thread 30 in an aperture 32 that extends through the tube wall, thereby forming mechanical connections between the injector sockets 12 and the tube 10 that are adapted to withstand higher maximum pressures than those at which conventional fuel rail assemblies can operate safely.

[0024] An orientation notch 34 is provided in the distal end region 24 of at least some of the injector sockets 12. On a given injector socket, the lead thread 28 is formed so that it is aligned with an associated orientation notch 34. The orientation notch 34 is oriented before engagement with the tube 10 in relation with a longitudinal axis A-A of the tube 10. After threading engagement of the proximal nipple end regions 22 of the one or more injector sockets 12 and after subjecting the injector nozzle 12 to a predefined torque, the injector sockets 12 are turned into registration with the tube 10 so that their rotational movement ends at a home or seated position (e.g. 20 degrees, FIG. 2). In that position, sealed mechanical connections are thereby formed between the tube 10 and the injector sockets 12.

[0025] 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 38 (FIG. 3) with threads engages the upstream end thread at the upstream end 18 of the tube 10. An end cap sensor boss 44 with threads engages the downstream end thread at the downstream end 20 of the tube.

[0026] 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.

[0027] 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.