ABSTRACT

Static Characteristics Static characteristics of flow rate were measured using a personal computer. Duty ratio of a PWM signal was slowly changed from 0 to 1. The PWM signal was fed to a driver circuit through a D/A converter. Once in a duty cycle, flow rate signal was sampled by an A/D converter. An example of static characteristics is shown in FIGURE 4. For duty ratio from 0.5 to 0.9, flow rate was controlled by a PWM signal. For duty ratio of less than 0. 1, the pilot solenoid valve had a dead band and it did not respond to a PWM signal. For duty ratio of less than 0.5, displacement of a main poppet became very small.