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Fuel supply pump mounted in fuel supply system of internal combustion engine, is arranged such that a predetermined relation is satisfied, at the time of approach of roller to the bottom dead center of the shoe, in imaginary state
Fuel supply pump mounted in fuel supply system of internal combustion engine, is arranged such that a predetermined relation is satisfied, at the time of approach of roller to the bottom dead center of the shoe, in imaginary state
The pump (1) has piston (2) mounted in pressure chamber (7). A plunger (3) has a roller (18) pressed and lifted upwards upon reaching bottom dead center of shoe (19) and set away from partial cylindrical surface (4) at upper dead center of shoe in imaginary condition in which the shoe is stopped at top dead center. At the time of approach of roller to bottom dead center of shoe in imaginary state, a relation comprising the values of distance in up-down direction from contact point defined between cam and roller to contact point of guide and roller, and diameter of roller is satisfied. The fuel supply pump has a piston arranged in a pressure chamber for fuel and which is moved in up-down direction, in order to increase or decrease the volume of pressure chamber, and a plunger which enables rotational movement of cam (13) placed at lower side of piston into linear back-and-forth motion. The plunger comprises a roller configured in cylindrical shape, in which the roller is reciprocally moved inside the cylinder (8) in the up-down direction. The roller contacts with outer peripheral surface (22) of cam, while rotating along outer peripheral surface of cam. A shoe rotatably supporting the roller is reciprocated in the up-down direction. A partial cylindrical surface which is a sliding surface is formed in the shoe. In cross-section, at right angles to rotation axis of roller, the cylindrical surface forms an arc which is arcuate about rotational axis of roller, which has a radius which is generally the same as radius of roller. The arc is placed on upper side of pivot of roller. A guide (5) is integrally fixed to the shoe. The roller is pressed and lifted upwards upon reaching the bottom dead center of the shoe and is set away from cylindrical surface at upper dead center of shoe in an imaginary condition in which the shoe is stopped at top dead center. At the time of approach of roller to bottom dead center of shoe in imaginary state, a first relation which comprises the values of distance in up-down direction from contact point defined between the cam and the roller to the contact point of the guide and roller, and the diameter of the roller, is satisfied.
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