Patent ID: 8641008
Filing Date: 2014-02-04
Classification: F04B

Abstract:
1. Method for controlling the position of an electromechanical actuator for reciprocating compressor valves, said actuator comprising a member movable in a direction parallel to the direction for opening and closing of the obturator of said valve, between a position corresponding to the closed position and a position corresponding to the open position of said obturator, said member being provided with an element arranged to act on the said obturator and with a magnetisable portion co-operating with two electromagnets and being arranged in equilibrium between the two electro-magnets, said method comprising the following operational steps: a) release for opening: energizing the magnets so as to allow separation of the portion of the movable member from the magnet directed away from the said valve and cause its displacement towards the other magnet; b) current-controlled opening: moving the movable member, as a result of the action of the magnets, towards the position for opening the obturator of the valve; c) position-controlled opening: regulating the current in the magnets so as to brake the movable member during the final section of its stroke; d) retention in open position: retaining the movable member in the position for opening the valve obturator for a given time interval; e) release for closure: energizing the magnets so as to allow separation of the movable member portion from the magnet directed towards said valve and cause its displacement towards the other magnet; f) current-controlled closing: moving the movable member, as a result of the action of the magnets, towards the position for closing the obturator of the valve; g) position-controlled closing: regulating the current in the magnets so as to brake the movable member during the final section of its stroke; and h) retention in closed position: retaining the movable member in the position for closing the obturator of the valve until a new transition signal is generated, for execution of step a) again; the method being carried out by using a processing unit connected to a sensor for detecting the position of the movable member of the said actuator and a detector for detecting the strength of the current flowing in the two said magnets, said processing unit comprising a module for inputting the enable and start-up and opening signals, a non-volatile memory module storing the program for processing the data acquired and the predefined reference values, a module for generating the trajectory of the said movable member, a module for adjusting the position of the said movable member, a module for regulating the current which controls a power supply section connected to a power supply input and interfaced with the detector for detecting the strength of the current flowing in the said magnets.