PROBLEM TO BE SOLVED: To attain a pump system accurately detecting flow rates of pumps, controlling the flow rates in real time and inhibiting a flow rate error due to generation of pulsations.
SOLUTION: Control of pump rotation speed by a pressure sensor has low responsibility in a low pressure region and is incomplete in correlation with the flow rates in a large flow rate region. A flow rate sensor 10 is therefore disposed in an outlet port 9 of the second pump 4. A position sensor 14 detects a time point when the first pump 3 is changed from a suction mode to a discharge mode, and when the flow rate sensor 10 detects that there is only discharge from the pump 4 without discharge from the pump 3, a control device 15 doubles previous rotation speed of a motor 12 (two times of normal rotation speed). When the flow rate sensor 10 detects a flow rate rise at the outlet port 9 of the second pump 4, the control device 15 returns the rotation speed of the motor 12 to the normal rotation speed. The generation of pulsations can be inhibited by the control of rotation speed of the motor 12 with accurate flow rate diction by flow rate sensor 10.
COPYRIGHT: (C)2007,JPO&INPIT