Virtual-pressure based control system and method for a filling machine flow regulating valve

1 . A method for controlling a flow regulating valve of a filling machine configured to form composite packages from a multilayer composite packaging material and to fill the composite packages with a pourable filling product, wherein a position of the regulating valve adjusts the flow of the product filling the packages, the method comprising:

implementing a flow feedback control, receiving a flow set point and an inlet flow measurement of the filling product from a flow meter and generating a feedback control contribution based on a difference between the inlet flow measurement and the flow set point;

implementing a flow feed-forward control, receiving the flow set point and generating a feed-forward control contribution using fluid-dynamic maps mapping an output position of the regulating valve with respect to flow and pressure of the filling product;

generating a virtual pressure based on the feedback control contribution at the output of the flow feedback control module;

receiving, in the flow feed-forward control, the virtual pressure, and generating at its output the feedforward control contribution based on the flow set point and the virtual pressure using the fluid-dynamic maps; and

generating a control signal for controlling an operating position of the flow regulating valve from the feedforward control contribution.

2 . The method according to claim 1 , wherein the virtual pressure is an estimate indication of the pressure of the filling product.

3 . The method according to claim 1 , comprising determining the virtual pressure as a function of the feedback control contribution at the output of the flow feedback control module and of a reference pressure value.

4 . The method according to claim 3 , comprising determining the virtual pressure as a difference between the reference pressure value and the feedback control contribution.

5 . The method according to claim 3 , wherein the reference pressure value corresponds to a maximum pressure value, which can be reached by the filling product during operation of the filling machine.

6 . The method according to claim 1 , wherein the fluid dynamics maps provide the operating position of the flow regulating valve from the values of the virtual pressure and flow set point.

7 . The method according to claim 1 , wherein the flow set point is indicative of a target flow of product through the regulating valve, determined as a function of one or more of: a start flow percentage, a nominal flow percentage, a machine speed flow percentage, a level set point and a product level measured by a level detector.

8 . The method according to claim 1 , wherein the flow feedback control is implemented by a proportional-integral-derivative, PID, module.

9 . The method according to claim 1 , further comprising:

receiving a product level measurement from a level detector;

determining a further control contribution by a proportional-integral-derivative control, based on a difference between the product level measurement and a level set point; and

wherein the flow set point is a function of said control contribution.

10 . The method according to claim 1 , wherein the filling machine is configured to form a tube from a web of the multilayer composite packaging material and comprises a filling pipe for filling the tube with the filling product; the regulating valve being configured to couple the filling pipe to a product processing line.

11 . A control system for controlling a flow regulating valve of a filling machine configured to form composite packages from a multilayer composite packaging material and to fill the composite packages with a pourable filling product, wherein the regulating valve is configured to adjust the flow of the product filling the packages, the control system comprising:

a control unit configured to determine a control signal for controlling an operating position the flow regulating valve, and

wherein the control unit is configured to implement the method according to claim 1 .

12 . A filling machine, comprising the control system, according to claim 11 .

13 . The filling machine according to claim 12 , configured to form a tube from a web of the multilayer composite packaging material and comprising a filling pipe for filling the tube with the filling product,

wherein the regulating valve is configured to couple the filling pipe to a product processing line.

14 . The filling machine according to claim 13 , wherein the flow meter is arranged upstream of the regulating valve with respect to a direction of flow of said filling product from the processing line to the filling pipe.

15 . The filling machine according to claim 12 , wherein the control unit does not receive a product pressure measurement as a control parameter to determine the control signal.