Patent ID: 7080792

Claim:
A liquid pressurizing device comprising: a reciprocating pump for pressurizing and delivering a high pressure liquid through reciprocating motion of a plurality of plungers; rotary servo motor means for driving the reciprocating motion of the plurality of plungers; pressure measuring means for measuring an actual delivery pressure value of said high pressure liquid; pressure control means for adjusting a feed rate of reciprocating motion of said plungers so that the actual delivery pressure value measured by said pressure measuring means is converged to a preset pressure value as a desired value; means to compare the measured actual delivery pressure value with a predetermined threshold which is close to and lower than said preset pressure value; means to control the reciprocating motion of the plurality of plungers through said rotary servo motor means depending on the result of the comparison to make the actual delivery pressure value reach the predetermined threshold if the threshold has not been reached; means to determine the feed rate as an optimum feed rate of the reciprocating motion of the plurality of plungers when the threshold is reached; and means to control the feed rate of the reciprocating motion of the plurality of plungers through said rotary servo motor means at said optimum feed rate after the threshold has been reached.