Pressure hydraulic pump having first and second synchronously driven reciprocating pistons with a pressure control structure

摘要

A high pressure hydraulic pump apparatus constituting a two-stage pressurizing hydraulic booster combining a pair of plunger pumps. The first and second pumps are driven into a push-pull synchronous operation at the equal stroke with each other. The per-stroke displacement of the first pump is greater than that of the second pump. The first pump draws by self-suction the liquid from a reservoir while the second pump is on the pressurizing and delivery stroke. When the first pump is on the delivery stroke, the liquid pressurized to a certain intermediate pressure by the first pump is sucked into the second pump. During the next reverse stroke the second pump further pressurizes and discharges the liquid while the first pump effects the suction stroke. At the final pressurization by the second pump, the driving stroke length of the pump is controlled to a limited value which provides a minimum delivery flow required for the interior of a load vessel to attain a target pressure in accordance with the compressibility of the liquid and the detection of a load pressure.