Pump unit for supplying fuel, preferably diesel oil, to an internal combustion engine

A pump unit for supplying fuel to an internal combustion engine, the pump unit comprising a high-pressure pump (2) for supplying the fuel to the internal combustion engine, and a pre-supply pump (3) for supplying the fuel to the high-pressure pump (2);

• the high-pressure pump (2) comprising at least two cylinders (10) having respective longitudinal axes (8) parallel to one another;
• a respective piston (13) slidingly engaged in each cylinder (10);
• a respective at least one head (9) for each cylinder, each head (9) having at least one through bore, which is coaxial with a corresponding longitudinal axis (8), wherein each head comprises a first portion forming a corresponding cylinder (10) and a second portion forming a fuel inlet (11) of the corresponding cylinder (10);
• and, for each cylinder (10), a respective intake valve (15) interposed between the cylinder (10) and a corresponding inlet (11) to selectively control the supply of fuel to the cylinder (10);
• each intake valve (15) comprising a valve body (16) and a shutter member (17) movable through the valve body (16) between an open position and a closed position of the intake valve (15);
• wherein the valve body (16) of each intake valve (15) is formed in one piece with the corresponding head (9), and wherein one cover (33) closes all the inlets (11) of said at least two cylinders, wherein the cover (33) is fixed to the heads (9) of the cylinders, wherein the pump unit further comprises a hydraulic circuit (34) for supplying the fuel to the inlets (11) of the cylinders (10), the hydraulic circuit (34) being formed entirely outside said at least one head (9), wherein the hydraulic circuit (34) comprises a distribution manifold (37) formed at least partially through the cover (33), and, for each inlet (11), a respective supply conduit (40), which extends between the distribution manifold (37) and the inlet (11), and is formed entirely through the cover (33).