To prevent flow of liquid phase fuel into a cam chamber from a fuel pressurizing chamber to secure good pump performance in a plunger reciprocating type fuel pump.
In the fuel pump that comprises a leaked fuel pooling chamber 33A formed on an inner circumferential side of a cylinder 34 and a leaked fuel recovery way 7 that connects it to a fuel tank 2, and returns the leaked fuel that has passed through a clearance between the cylinder 34 and a plunger 35 to the fuel tank 2, the leaked fuel pooling chamber 33A is connected to the cam chamber 31 by communication ways 38 and 39. On the way, a gas-liquid separation chamber 37 is formed, and a valve 37b is disposed at a gas phase part of the gas-liquid separation chamber 37 for opening and closing the communication way 39 leading to the open cam chamber 31 by the vertical motion of a float 37a. When the volume of leaked fuel in the gas-liquid separation chamber 37 is below a predetermined level, the valve 37b maintains the opened state to balance the pressure of the leaked fuel pooling chamber 33A and the pressure of the cam chamber 31, and when the volume is at the predetermined level or higher, the valve 37b closes to prevent the leaked fuel in the liquid phase from flowing into the cam chamber 31 through the communication ways 38 and 39.
WAKABAYASHI AKIYUKI
SHIN GENKUN
Kyoko Hashimoto
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