| 摘要 |
PROBLEM TO BE SOLVED: To restrain a wall surface at a fuel sump part from being damaged in an early stage due to cavitation errosion, and thereby lengthen the life of a pump. SOLUTION: This pump permits a fuel introducing hole 22 to be opened/ closed by the reciprocal movement of a planger 6, and allows fuel in a fuel sump part 20 to be introduced to a pump chamber 9, and furthermore, permits fuel in the pump chamber 9 to be returned to the fuel sump part 20 whose wall surface is covered with a protective cylindrical body 25. A spiral groove 27 is provided for the fuel introduction hole 22, which transforms both a high pressure over-flow jet A to be jetted to the fuel introduction hole 22 out of the pump chamber 9, and the flow of return jet B, into a spiral shaped flow. By this constitution, the energy of jet is damped, which is jetted to the introduction hole 22 out of the pump chamber 9 so as to allow the generation of bubbles to be followed simultaneously, and aforesaid jetting and bubbles are prevented from arriving at the cylindrical body 25, the occurrence of cavitation errosion due to the breaking of bubbles in the inner surface of the cylindrical body 25, is also restrained, and as a result, the wall surface of the fuel sump part 20 is thereby prevented from being damaged. |
