Electromagnetically actuated, proportionally operating directional control valve

摘要

An electromagnetically actuated, proportionally operating directional control valve (10) is proposed in which a pulsed switching magnet (22) controls a servo valve spool (17) and hence a quantity of pressure medium proportional to an analogue input signal (43). The armature of the switching magnet (22) is coupled via a pretensioned actuating spring (32) to the servo valve spool (17), on which a restoring spring (26), which is weaker than the actuating spring, acts in the opposite direction. A restrictor (35) in a channel (34) which connects both end control spaces (23, 25) limits the actuating speed of the servo valve spool (17). As a result of the characteristics (46, 47), which run obliquely with respect to one another, of the actuating spring (32) and of the restoring spring (26), the servo valve spool (17) assumes a stable central position as a function of the duty ratio of the input pulses (44) to the switching magnet (22), in which stable central position it carries out small oscillating movements. The directional control valve (10), which is simple and cheap to construct, operates proportionally and with low hysteresis. IMAGE