Hydraulic pressure supply pump with simultaneous directly actuated

Abstract

A pump and associated method including the steps of pre-metering successive quantities of fuel from a reservoir to a positive displacement transfer pump, then actuating the transfer pump to raise the pressure of the successive quantities of fuel by at least about 100 psi, preferably 200-300 psi. Each quantity of fuel which was pressurized in the transfer pump, is delivered to a high pressure pumping chamber so that each pumping bore receives a certain, i.e., predetermined, charge of fuel within a first time interval. A plurality of plungers in the respective pumping bores are then simultaneously actuated to increase the pressure in the pumping chamber to the desired high pressure, preferably at least about 15,000 psi, within a second time interval, and to discharge the quantity of fuel through a high pressure discharge valve. The second time interval is of longer duration than the first time interval. As a result, the necessary quantity of fuel can be delivered to the pumping chamber in a relatively short time period. Therefore, each pumping plunger can be actuated by a dual rate cam profile over a relatively long time period such that at steady state the actuation occurs only along a relatively shallow slope of the cam profile, whereas when acceleration is required, the actuation can occur more quickly, along a steeper profile, before continuing along the relatively shallow profile.