| 摘要 |
PROBLEM TO BE SOLVED: To certainly avoid the leakage of fuel to the atmosphere side through a sliding part, and to reduce labor hours for maintenance, in a fuel pump pressurizing fuel and delivering it to an engine. SOLUTION: This fuel pump 1A introduces fuel to a fuel pressurizing chamber 7 arranged between a suction side fuel passage 50 and a delivery side fuel passage which are respectively provided with check valves 11, 12, and forcibly delivers fuel to the engine by varying the volume of the fuel pressurizing chamber 7 on the end side of a plunger 5 reciprocatingly sliding in a cylinder 4A. In a halfway position in the length direction of the cylinder 4A, a back pressure chamber 16 which is a clearance between the cylinder 4A and the plunger 5 and filled with oil adjusted to the same pressure as leaked fuel having pressure in a direction of a base end of the cylinder 4A, is arranged to surround the plunger 5 with the peripheral surface of the plunger 5 as a part of an inner wall. Fuel leakage via the base end side of the cylinder 4A is prevented by balancing oil pressure in the back pressure chamber 16 with leaked fuel pressure. COPYRIGHT: (C)2008,JPO&INPIT |
