Method and apparatus for proportional valve actuation in a plasma cutter

A plasma cutting system, comprising:

• a gas supply system constructed to provide a pressurized gas to a plasma torch;
• and
• a proportional valve configured to regulate flow of the pressurized gas, the proportional valve comprising:
• a body;
• a valve seat positioned within the body and defining a valve orifice;
• a plunger having a mating surface on a first end and a pressure receiving surface on an opposite second end, the mating surface configured to mate with the valve seat and the valve orifice;
• an inlet configured to receive the pressurized gas and to distribute the pressurized gas to the valve orifice and the pressure receiving surface of the plunger;
• and
• an electrical solenoid mounted in the body and configured to electro-magnetically translate the plunger;
• wherein the pressurized gas urges the plunger toward the valve orifice when electrical power is reduced to the electrical solenoid.

A proportional valve, comprising:

• an inlet chamber connected to a gas source for receiving pressurized gas therefrom;
• a valve chamber fluidly connected to and positioned downstream from the inlet chamber;
• a plunger configured to translate within the valve chamber between an open position and a closed position, the plunger having a mating surface on a first end and a pressure receiving surface on an opposite second end, wherein the plunger is biased toward the closed position by a pressurized gas closing force applied by the pressurized gas against the pressure receiving surface;
• a valve seat positioned within the valve chamber adjacent the mating surface of the plunger when the plunger is in the closed position, the valve seat defining an orifice that enables an output gas flow therethrough when the plunger is in a position other than the closed position;
• and
• a coil configured to apply an opening force to the plunger to regulate the output gas flow through the orifice.

A method, comprising:

• supplying a flow of pressurized gas to an inlet of a proportional valve;
• transferring the flow of pressurized gas from the inlet of the proportional valve inlet to a valve chamber within the proportional valve, wherein the valve chamber comprises an orifice and a plunger positioned therein, wherein the plunger is configured to translate relative to the orifice between an open position and a closed position to control an output gas flow through the orifice;
• biasing the plunger toward the orifice using the pressurized gas, wherein the pressurized gas has a pressure sufficient to bias the plunger to the closed position;
• and
• activating a coil to translate the plunger relative to the orifice and adjust the output gas flow to a desired output gas flow set point.