Control system for controlling the supply of a predetermined quantity of fluid

Claim 1

A control system for controlling a supply of a predetermined quantity of fluid, said control system comprising: a pump for supplying a fluid; a motor for driving said pump, said motor being rotated when a current is applied thereto; measuring means for measuring a flow quantity of the fluid which is supplied by said pump, said measuring means also measuring an oversupply quantity ΔQ of the fluid which is supplied by the pump after the current to the motor is cut off; presetting means for presetting, before starting a fluid supplying operation, a preset value P which is indicative of a desired fluid supplying quantity; and control means supplied with a measured flow quantity from said measuring means and the preset value P from said presetting means for controlling the application of the current to said motor, said control means comprising memory means for storing minute current applying durations and a predetermined value K, where K is a predetermined value greater than said oversupply quantity ΔQ, each of said minute current applying durations stored in said memory means corresponding to minute quantities of fluid which will be supplied by the pump when the current is applied to the motor for said minute current applying durations, first means for applying the current to said motor until the measured flow quantity from said measuring means becomes equal to P-K, and second means for applying the current to the motor m times for selected minute current applying durations until a total flow quantity Q of supplied fluid measured by said measuring means becomes approximately equal to the preset value P, where m is an integer, ##EQU3## and q'n is a quantity inclusive of an oversupply quantity measured by said measuring means in each of the minute current applying durations, said second means successively calculating a difference P-Q between said preset value P and the total flow quantity Q of supplied fluid measured by said measuring means, successively selecting a current applying duration out of the minute current applying durations stored in said memory means so that the selected current applying duration corresponds to the calculated difference P-Q, and applying the current to said motor for the selected current applying duration to drive said pump so as to reduce the calculated difference.