| 摘要 |
PROBLEM TO BE SOLVED: To make a suction valve and a discharge valve in an invariably closing condition so as to prevent relief of a fluid from a discharging side to a suction side, and improve pump performance by forming a cam for performing reciprocating motion of a plunger in a shape formed in such a constitution that displacing speed and displacing acceleration of the plunger are set to 0 at the top dead point and the bottom dead point of the plunger. SOLUTION: When a cam 29 formed in a shape in which three crests are formed on a foundation circle starts rotation from a rotary angle 0 deg. positioned on a bottom dead point, a plunger 24 is lifted up, and fuel is pressurized in a pump chamber 33 in a cylinder. In this time, a fluid is discharged by closing a suction valve 39a as well as opening a discharging valve, and the plunger 24 reaches a top dead point at the time of rotating it by 48 deg.. When the plunger 24 falls down by changing the moving direction of the plunger 24 from the top dead point, the discharge valve 39b is closed as well as opening the suction valve 39a so as to supply fuel. In such suction and discharge strokes, since displacing speed and displacing acceleration are set to 0 at the top dead point and the bottom dead point of the plunger 24, the suction valve 39a and the discharging valve 39b are invariably closed so as to prevent relief of the fluid. |
