| 摘要 |
PURPOSE: To shorten the dwell time of sealing oil by setting flow-through cross sectional area of a sealing oil groove in the inner wall of a pump piston bush to a maximum 100% of the cross sectional area of a supply bore for the sealing oil, preferably 50%. CONSTITUTION: In the bottom dead point (a) of a pump piston 2, a groove or an area portion 10 provided in a side face axial direction controls not the sealing oil bore 6 of a pump piston bush 1 but the sealing oil bore 6 at the height of a top dead point (b), and connects the sealing oil bore 6 to a flow-out portion in the side portion of a pump element 19 positioned toward the opening portion 15 of a sealing oil supply bore 7. Leaked oil is returned through a groove 4 and a bore 5 into a suction bore 3, and the mixed oil of heavy oil fuel and lubricating oil is discharged through a groove 8 and a bore 9. Here, the flow-through cross sectional area of the sealing oil groove 6 is formed to be 100% at a highest of the supply bore 17, preferably 50%. Thus, the dwell time of the sealing oil is shortened, deposits in the heating area of the pump element 9 are eliminated or avoided, and piston locking is prevented. |
