Dynamic control of fluid pressure within a fluid flow circuit

An inkjet printing system comprising:

• an inlet line and an outlet line;
• an ink circulation system configured to supply ink through the inlet line and return undispensed ink through the outlet line;
• a printhead comprising at least one nozzle fluidically coupled to the inlet line and the outlet line and configured to dispense ink, wherein the printhead defines a pressure-controlled point and wherein the printhead is selectively movable, relative to the ink circulation system;
• a first proportional valve disposed in the inlet line and configured to selectively modulate an inlet fluid pressure in the inlet line between the first proportional valve and the at least one nozzle;
• a first pressure sensor between the first proportional valve and the printhead and configured to measure the inlet fluid pressure in the inlet line;
• a second proportional valve disposed in the outlet line and configured to selectively modulate an outlet fluid pressure in the outlet line between the at least one nozzle and the second proportional valve;
• a second pressure sensor between the printhead and the second proportional valve and configured to measure the outlet fluid pressure in the outlet line;
• and
• a controller operably coupled to the first proportional valve, the first pressure sensor, the second proportional valve, the second pressure sensor, and the printhead, wherein the controller is configured to control the first proportional valve so that the inlet fluid pressure is maintained at a target inlet fluid pressure and control the second proportional valve so that the outlet fluid pressure is maintained at a target outlet fluid pressure and wherein the controller is configured to control the at least one nozzle to selectively dispense ink onto a surface.

A method for dynamically controlling fluid pressure within a fluid flow circuit, the method comprising:

• determining a target inlet fluid pressure in an inlet line supplying a working fluid to a fluid management device;
• determining a target outlet fluid pressure in an outlet line returning working fluid from the fluid management device based on a desired average fluid pressure of the working fluid at the fluid management device and a desired fluid flow rate at the fluid management device;
• controlling an inlet fluid pressure to maintain the target inlet fluid pressure by actuating a first proportional valve, wherein the inlet fluid pressure is measured by a first pressure sensor;
• and
• controlling an outlet fluid pressure to maintain the target outlet fluid pressure by actuating a second proportional valve, wherein the outlet fluid pressure is measured by a second pressure sensor.