Fuel rail

A fuel rail containing injectors for delivering fuel to an engine has a large passage supplying fuel to the injectors and a small fuel return passage. The injectors are received in sockets each of which has a restricted vent extending to the return passage. The fuel rail is formed by molding or extruding a body with the supply and return passages, and a single circular plug at one end provides a closure for the associated ends of both the supply and return passages.

THE PREFERRED EMBODIMENT 
Referring to the drawing, each combustion chamber 10 of an automotive spark 
ignition engine 12 receives a mixture of air and fuel through an inlet 
port 14 controlled by an inlet valve 16. Inlet port 14 receives air from 
an inlet manifold 18 and fuel from a fuel rail 20. 
Fuel rail 20 has a plurality of fuel injector sockets 22 each of which 
contains a fuel injector 24. A fuel supply passage 26 receives fuel 
through a fuel line 28 from a low pressure fuel supply pump (not shown). 
Passage 26 intersects each of the sockets 22 to supply fuel to sockets 22, 
and each injector 24 delivers fuel from the lower portion 30 of its socket 
22 into its associated engine inlet port 14. 
Fuel injectors 24 preferably are conventional electromagnetic fuel 
injectors energized by a conventional electronic control unit (not shown) 
to deliver timed pulses of fuel for mixture with the air which flows into 
combustion chamber 10 through inlet port 14. 
Fuel rail 20 also has a fuel return passage 32 parallel to supply passage 
26. Return passage 32 is connected to supply passage 26 by a channel 34 at 
the left hand end of fuel rail 20 and discharges fuel through a pressure 
regulator 35. Return passage 32 has approximately the same fuel flow area 
as fuel line 28, but supply passage 26 has a fuel flow area substantially 
greater than the fuel flow area of fuel line 28 and return passage 32. The 
substantially greater fuel flow area of supply passage 26 effectively 
minimizes the velocity and turbulence of fuel flow in supply passage 26, 
allowing fuel vapor to separate from the liquid fuel in supply passage 26. 
The fuel vapor, of course, accumulates along the top of supply passage 26, 
and the lower portion 30 of injector sockets 22 is filled with liquid fuel 
to assure that injectors 24 receive only liquid fuel for delivery to 
engine 12. 
In addition, the upper portion 36 of each injector socket 22 has a 
restricted vent 38 extending to return passage 32. Vents 38 allow fuel 
vapor accumulating in supply passage 26 and injector sockets 22 to be 
discharged directly to return passage 32. Vents 38 thus assure that 
little, if any, fuel vapor is reentrained in the liquid fuel flowing 
through supply passage 26 from one injector socket to another. Vents 38 
also allow liquid fuel to circulate through injector sockets 22 to cool 
injectors 24. 
The left hand end of fuel rail 20 has a circular recess 40 which 
encompasses the associated ends of supply passage 26 and return passage 
32. A circular plug 42 is received in and seals recess 40 and provides a 
single closure for the associated ends of both supply passage 26 and 
return passage 32. 
The fuel rail shown in the drawing is molded of plastic, and plug 42 may be 
secured in recess 40 by any satisfactory technique such as bolts 44. 
It will be appreciated that each of the various features of the fuel rail 
depicted here may be used without employing all of the remaining features. 
In combination, however, they provide a fuel rail of particularly 
advantageous construction.