Fuel rail assembly

1. A fuel rail assembly for an internal combustion engine, the fuel rail assembly comprising:

an elongate, common fuel rail having a reservoir for a fuel supply;

a plurality of adapters spaced along and fixed to a wall of the elongate, common fuel rail for hydraulically connecting a respective fuel injector to the reservoir in the elongate, common fuel rail; and

a respective fuel passage associated with each adapter of the plurality of adapters, each of the fuel passages directing fuel from the reservoir to the associated adapter; wherein each of the fuel passages comprises an inlet end open to the reservoir and an upstream end section adjacent to the inlet end having a length and a cross-sectional area forming a smoothing function to smooth pressure fluctuations in fuel entering the respective fuel passages;

each of the fuel passages has a downstream end section adjacent to the associated adapter;

each of the fuel passages includes a radially extending wall perpendicular to the axis of the upstream end section and connecting a downstream end of the upstream end section with an upstream end of the downstream end section; and

the radially extending wall includes an annular channel configured to provide a relief channel to absorb excess brazing material during a brazing process for fixing the respective adapter to the wall of the elongate, common fuel rail.

2. The fuel rail assembly according to claim 1 , wherein each of the fuel passages comprises a respective through-hole in the wall of the elongate, common fuel rail.

3. The fuel rail assembly according to claim 2 , wherein a thickness of the wall in the region of each of the fuel passages is such as to provide a length required for the fuel passage.

4. The fuel rail according to claim 1 , wherein the wall is generally cylindrical and comprises a flattening comprising the fuel passage.

5. The fuel rail assembly according to claim 1 , wherein:

each of the adapters comprises an injector cup adapted to receive an inlet end of the respective fuel injector; and

each of the injector is mechanically secured to the wall of the elongate, common fuel rail and includes an orifice hydraulically connected to a downstream end of the respective fuel passage, remote from the inlet end of the respective fuel passages.

6. The fuel rail assembly according to claim 5 , wherein each of the fuel passages is configured to accommodate a ring of brazing material at a periphery of the fuel passage through which ring of brazing material the injector cup is brazed to the elongate, common fuel rail.

7. The fuel rail assembly according to claim 1 , wherein each of the downstream end sections adjacent to the associated adapters has a larger cross-sectional area than the cross-sectional area of the upstream end sections.

8. The fuel rail assembly according to claim 7 , wherein each of the fuel passages comprises a frusta-conical section expanding from the upstream end section to the downstream end section.

9. The fuel rail assembly according to claim 8 , wherein the frusta-conical section includes a surface profile or roughness configured to control a flow of brazing material thereacross during the brazing process.

10. The fuel rail assembly according to claim 7 , wherein:

the upstream end section and the downstream end section are generally cylindrical;

the downstream end section comprises a generally cylindrical part having a larger diameter than the upstream end section.

11. The fuel rail assembly according to claim 10 , wherein the radially extending wall comprises a surface profile or roughness configured to control a flow of brazing material during the brazing process.

12. The fuel rail assembly according to claim 1 , wherein the radially extending wall comprises a plurality of concentrically disposed annular channels.

13. The fuel rail assembly according to claim 1 , wherein the upstream end section of the fuel passage is chamfered or curved at its upstream end and/or at its downstream end.