A hydraulic device for supplying a fluid to a plurality of hydraulic consumers of an injection molding machine, comprising:
- a reservoir for the fluid;
- a variable capacity pump connected to said reservoir for feeding the consumers with the fluid from said reservoir, said pump having a controlling device for controlling a flow of the fluid from said pump;
- a sole control valve connected to said pump, and having at least three selectable control positions each defining a different flow path of the fluid;
- a first connecting line connecting said sole control valve with a first and second consumer;
- a second connecting line connecting said sole control valve with the first and the second consumer, said first and second connecting lines selectively serving as a discharge connecting line for providing said sole control valve with the fluid discharged from the consumers, and a feed connecting line for supplying the consumers with the fluid from said sole control valve, respectively, in dependence of a selected control position of said sole control valve;
- a control unit programmable with preset nominal values;
- first transducing means connected to said control unit and being in communication with said first connecting line for measuring an adjusted actual value and generating a signal in relation thereto;
- second transducing means connected to said control unit and being in communication with said second connecting line for measuring an adjusted actual value and generating a signal in relation thereto, the signals of said first and second transducing means being transmitted to said control unit and being compared with the preset nominal values in said control unit for forming a regulating variable therein;
- the control positions of said sole control valve being controlled in a closed loop arrangement by said control unit as a function of the regulating variable, whereby said control valve simultaneously controls both an influx flow and a reflux flow of the fluid through the first and second consumers;
- first and second 4/2-way connecting valves being in communication with said first and second consumers, respectively, and being arranged in said first and second connecting lines for establishing a fluid connection between the first and second consumers and said control valve;
- and
- a feedback line connected to said controlling device and connecting said controlling device with said first and second connecting lines, said controlling device responding to a highest pressure of a first pressure within said first connecting line and of a second pressure within said second connecting line by continuously adjusting an output of said pump in a closed loop arrangement to maintain a constant operational pressure gradient between said pump and a position downstream of said control valve.