Proportional Solenoid Valve with Electronic Flow Control

This paper presents a proportional solenoid valve with electronic flow control along with its testing results, conducted on purpose-built test benches. The results demonstrate the precise proportional action and wide displacement capabilities in certain domain. Through its unique design, the position of mobile equipment of proportional electromagnetic actuator from the component of the proportional solenoid valve has a wide range, of 0 to 14 mm. This is achievable by the balance between the electromagnetic force and elastic force of a spring. Using the Pulse Width Modulation (PWM) principle, the electronic dedicated module can precisely control the position of the hydraulic piston, by adjusting the duty cycle factor and respectively the coil current of actuator. The device precision was enhanced by adding a magnetic Hall sensor providing real-time feedback on the piston position. The displacement of the moving component of the linear proportional electromagnetic actuator depends only on the ratio between the pulse duration and the PWM voltage period, i.e. of the duty cycle, for a fixed frequency of the PWM control voltage, of 24 kHz, and the set a peak-to-peak amplitude of the applied voltage of 24 V. Many experiments were carried out with and without hydraulic fluid for an in-depth analysis of the proportional solenoid valve behaviour in a given range of pressures and flow rates. The results highlighted that the device has optimum performance in terms of hydraulic losses if the flow section is maintained around 50 mm2 for a pressure up to 30 bar. The results also confirm that the electromagnetic force generated by the actuator increases with both piston stroke (which, by design, corresponds to a decrease in the air gap) and the applied current. The quasi-linear region within the mid-range of displacement (2 mm to 6 mm) defines a stable control range of proportional solenoid valve with electronic control. The obtained results aim the increasing of the performance and the precision control for a for certain imposed parameters of the hydraulic fluid.