Ningbo Kaiven Pneumatic Cylinders Co.,Ltd >> Proportional Solenoid Valves
A proportional solenoid valve utilizes the same elements as a regular pneumatic or hydraulic solenoid valve but with more advanced flow control capabilities. A solenoid, or electromagnetic coil, is used to trigger the valve flow with electronic pulses, moving the magnetized coil at appropriate times. In direct-acting solenoid valves, a plunger is in direct contact with the in-flow opening in the valve body, or orifice. This plunger opens and closes the orifice through the movement of the solenoid, permitting or hindering flow. Pilot-operated solenoid valves work with a diaphragm rather than a plunger, using differential pressure to control the flow of fluids. In pilot-operated valves there is a solenoid-operated vent which is opened to allow the pressure to equalize, permitting fluids or gases to flow through.
Both direct-acting and pilot-operated proportional solenoid valves regulate flow based on linearity, frequency response and hysteresis. Linearity refers to the valve’s ability to actuate – that is, to switch on and off – in a way that creates a smooth line of input and output. An example of linear regulation is that of a car’s cruise control feature as opposed to a typical heat thermostat. The heating thermostat is actuated only after the temperature in a room has dropped below programmed temperature and switches off only after room temperature has risen above it; cruise control, on the other hand, regulates a vehicles speed more precisely, maintaining a steady gas input and adjusting minutely to compensate for factors such as wind and incline. Both demonstrate hysteresis, or path-dependent “memory”, but only cruise control demonstrates true linearity; proportional valves utilize both traits. Frequency response refers to the valve’s capability to respond to outside frequencies aimed at regulating valve flow. Proportional valves with high frequency response, linearity and hysteresis control flow accurately based on repeatability within close tolerances.
