Patent ID: 8479712

Claim:
A pulsation reducing apparatus for a fuel supply system of an internal combustion engine that includes a fuel pump, which pumps fuel out of a fuel tank, and a fuel filter, which receives the fuel from the fuel tank through a fuel passage upon pumping of the fuel by the fuel pump and filters the fuel, the pulsation reducing apparatus being adapted to reduce pressure pulsation of the fuel, which is generated in the fuel passage and is conducted to the fuel filter in the fuel passage due to operation of the fuel pump, and comprising: a passage cross-sectional area reducing device that reduces a passage cross-sectional area of a predetermined location of the fuel passage on an upstream side of the fuel filter in a flow direction of the fuel when a pressure of the fuel in the fuel passage becomes equal to or higher than a predetermined pressure, wherein the passage cross-sectional area reducing device is placed in the fuel passage on the upstream side of the fuel filter; a pulsation reducing device that reduces a pressure pulsation of the fuel on an upstream side of the predetermined location of the fuel passage in the flow direction of the fuel; and a connection passage that is connected to the fuel passage at one connection of the connection passage, which is located on the upstream side of the predetermined location of the fuel passage, wherein: the pulsation reducing device is placed in the connection passage; fluid communication between the fuel passage and the connection passage is enabled by reducing the passage cross-sectional area of the fuel passage with the passage cross-sectional area reducing device; the connection passage is further connected to the fuel passage at another connection of the connection passage, which is located on an upstream side of the one connection of the connection passage connected to the fuel passage; and the connection passage is adapted to output the fuel, which is supplied into the connection passage from the one connection of the connection passage, toward an upstream side of the connection passage.