Parametric Investigation on the Responsibility of Dual Solenoid Fuel Injectors with Multiple Injection Strategies

To improve the flexibility of injection rate control, this study developed a set of drive current timing strategies for a dual-solenoid-valve injector (DSVCI) featuring (NCV-1) and (NCV-2). These strategies enabled operation in single-valve rectangular, dual-valve rectangular, and ramp injection modes. The corresponding injection characteristics, including injection rate profiles, injection delay, duration, and fuel quantity, were systematically examined across a wide range of conditions. Results show that the ramp mode initiates with a gradual increase in injection rate driven by NCV-1, followed by a sharp acceleration upon NCV-2 activation. The opening delay in ramp mode closely matches that of the single-valve rectangular mode, while its injection onset occurs 0.23 ms later than in dual-valve operation. In contrast, the closing delay in ramp mode aligns with the dual-valve rectangular mode and exceeds that of the single-valve mode. Both ramp and dual-valve modes exhibit reduced injection durations with increasing pressure, whereas the single-valve mode maintains a nearly constant duration at low pressures. Under long-duration injections, the fuel quantity increases linearly in rectangular modes but displays an accelerating growth trend in the ramp mode as NCV-2 activation time increases. These findings provide new insights into the dynamic behavior of the dual-solenoid-valve control injector and highlight the potential of ramp shaping for advanced injection rate control.