CONTROL METHOD OF LIQUID CONSTANT FEEDER

PROBLEM TO BE SOLVED: To provide a control method of a liquid constant feeder capable of conducting a pulse-free operation by a simple control without using a pressure sensor in a feedback process as pressure adjustment by a torque calculation is conducted in an operation initial period. SOLUTION: In the liquid constant feeder for continuously feeding liquid sucked in by a plurality of reciprocating pumps 1 to a liquid feed line 2 by applying pressure and discharging the liquid alternatively, torque of a corresponding pump drive motor 3 is calculated from pressure from the liquid feed line 2 and a pressure adjustment distance is calculated by sucking the liquid in by the reciprocating pumps 1, closing a discharge valves 41 and intake valves 42 and compressing the liquid by pistons 5 and moving the pistons 5 until the torque is achieved. As the liquid is taken in additionally only for the pressure adjustment distance and compressed by moving the piston the pressure adjustment distance while waiting for discharge, an inner pressure of the reciprocating pumps 1 is maintained approximately equal to that of the liquid feed line 2 before discharge. COPYRIGHT: (C)2008,JPO&INPIT