ELECTROHYDRAULIC CONTROL SYSTEM Russian patent published in 1995 - IPC

FIELD: mechanical engineering. SUBSTANCE: drain line from pressure reducing valve is connected to pressure station of hydraulic control valve and further on through all its distribution sections and also through its drain section to tank. With such connection difference of pressures at the pressure reducing valve and at the outlet of drain pipe remains constant. In the course of operation, electromagnet coils in distribution sections of proportional control warm up and load current decreases. This results in reduction of resistor voltage at input of second operational amplifier and voltage of negative feedback at second input of first operational amplifier. This, in turn, leads to restoration of previous current value in electromagnet coils providing for constant speed of tree doser operation. Union of pressure section connected with hydraulic pump contains throttle made in the form of bushing with male thread and hole with starting chamfer. Location of this throttle inside union contributes in simplifying application of control pressure and improving reliability of the whole system. Distribution sections of discrete control are protected against accidental switching-in of electromagnets. To this end button switch "RESET" is cut into control circuit so that both the electromagnets are interlocked and, when one of them is switched on, the second can not be switched on until button switch "RESET" is depressed. EFFECT: improved reliability of operation under extreme temperature conditions. 3 cl, 2 dwg