Electric fuel pump for use in the fuel injection system or a spark-ignition internal combustion engine

An electrically-operated fuel pump for use in the fuel injection system of a spark-ignition internal combustion engine, said pump comprising:

• a tubular casing with respective means defining a fuel input at one end of said casing and a fuel output at the opposite end of the casing,
• a spindle and two spaced supports mounting the spindle longitudinally within said casing,
• an electric motor housed within said casing and comprising a stator, and a rotor carried on said spindle,
• a pumping assembly arranged within said casing and including a rotatably mounted impeller, said impeller being supported on said spindle and being drivingly coupled to the rotor of the motor,
• electrical connection means for supplying electric current to the said motor, and
• first valve means for preventing the build up of excess pressure in the fuel contained in the casing, and second valve means for preventing the return flow of fuel back through said fuel output,
• said casing as well as serving as a containment member for the fuel and a mechanical supporting structure for the components of the pump, also constituting the magnetic frame of the stator of the electric motor,
• wherein said spindle is formed with an internal longitudinal passage, said passage having an outlet which opens into the low-pressure side of the pumping assembly adjacent the fuel input, and an inlet which opens into the interior of the pump on the high-pressure side of the pumping assembly, the said first valve means being situated adjacent the said outlet of the passage and being constituted by a valve closure member in the form of a ball and a spring arranged to urge the ball towards the passage outlet whereby to close off this latter, and
• wherein said pumping assembly comprises, in addition to said impeller, a base part and a stator supported thereby, said base part being formed with a cavity having a first portion wherein the said ball of the first valve means is located, and a second portion wherein one end of the spindle is supported with the said outlet of the spindle passage facing towards the said first portion of the cavity.