| 摘要 |
<p>PURPOSE:To improve the pumping efficiency of a piston pump provided with an intake hole at the side face of a piston. CONSTITUTION:An intake chamber and a compression chamber are partitioned in front and in the rear of a piston 3 reciprocated in a cylinder 2, and an intake hole 8 opened at the side face of the piston 3 in such a way as to face the intake chamber in an intake position is closed by the cylinder wall from halfway in a compression stroke to perform discharge action. In such a piston pump, the cylinder 2 is formed of a sleeve 20 slidably fitted into a pump housing 1 through a seal 22, and a return spring 25 is provided to energize the sleeve 20 with smaller force than pressing force acting upon the sleeve 20 in the direction of the intake chamber on the basis of the pressure of the compression chamber at the time of discharge so as to lower the sleeve 20 on the basis of the pressure acting upon the compression chamber at the beginning of a discharge stroke. The closure of the intake hole 8 and pressure rise are thereby started early.</p> |
