Electrohydraulic actuator

摘要

The electrohydraulic actuator has a valve device (16) with which a hydraulic motor (30) can be reversed. The valve device (16) is moved by a control part (15) which is a component of a compensation mechanism (14). A displacement movement preset by a stepping motor (10) is imparted to the presetting part (13) which adjusts the control part (15). The output of the hydraulic motor (30) is coupled to an answer part (28) which cancels the adjustment of the control part (15) as soon as the desired position is reached. An actuator of this type has the disadvantage that, if the hydraulic supply fails or is cut off, an adjusting command not yet performed remains stored by the position of the control part (15) and is still performed after the hydraulic system is switched on again. To achieve a defined initial position when the hydraulic system is switched on, the control part (15) is coupled to a sensor device (35) which controls the stepping motor (10) in a preparation phase via a microprocessor (11) in such a way that the control part (15) is put into the neutral position. The sensor device (35) also performs the function of the limit switches. Its sensors are checked for serviceability in the preparation phase. <IMAGE>