Hydraulic flow control valve - has electrically positioned piston and uses comparison of piston position and stepping motor demand signals

摘要

An electrically positioned hydraulic flow regulating valve has a slider varying the connections between several separate chambers. It is applicable to thermoplastic injection moulding systems and may be driven directly by a continuous electrical drive independent of variable system parameters using a program input. It can be inserted in hydraulic circuits without damping elements. A driving stepping motor is connected to one side of the slider whose other side is connected to a position sensor. The sensor actual position signal is compared in a comparator circuit with a demanded stepper motor position signal generated by the machine controller. The slider is in the form of a piston whose rod extends through the housing wall and is driven from the motor via a drive screw and threaded sleeve.