# US 2014/0190944 A1 · Method and apparatus for automatically controlling gas pressure for a plasma cutter > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0190944 A1 - Document ID: US20140190944A1 - Status: Published application - Kind: A1 - Application number: 14/204,913 - Filed: 2014-03-11 - Published: 2014-07-10 - Earliest claimed: 2006-07-27 - Assignees: Illinois Tool Works Inc. - Applicants: Illinois Tool Works Inc. - Inventors: Anthony V. Salsich; Joseph C. Schneider; James F. Ulrich - Web page: https://patentgrep.com/patent/US20140190944A1 ## CPC - B23K 10/006: {Control circuits therefor} - H05H 1/34: Details, e.g. electrodes, nozzles - H05H 1/36: Circuit arrangements (H05H1/38, H05H1/40 take precedence) - B23K: SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM - H05H: PLASMA TECHNIQUE (apparatus or processes specially adapted for producing X-rays H05G2/00); PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS ## Abstract A system for providing a dynamically controlled plasma cutting system. The plasma cutting system includes a proportional valve and a sensing device arrangement and a controller connected to this arrangement. The system is configured to dynamically control gas flow in a plasma torch. The system measures gas pressure at a proportional valve and makes necessary gas pressure adjustments in the system by way of controlling a drive signal sent to the proportional valve to control gas flow. ## Claims ### Claim at position 1 -24. (canceled) ### Claim 25 A plasma cutting system comprising: a power source configured to generate plasma cutting power; a plasma torch coupled to the power source; a gas flow system configured to receive pressurized gas and provide a gas flow to the plasma torch; a proportional valve configured to regulate the gas flow; and a controller configured to regulate operation of the proportional valve by controlling a drive signal sent to the proportional valve, wherein the controller determines input pressure of the plasma cutting system based on an output pressure of the plasma cutting system and the drive signal. ### Claim 26 (depends on 25) The plasma cutting system of claim 25, wherein the drive signal is one of a current signal and a voltage signal. ### Claim 27 (depends on 25) The plasma cutting system of claim 25, wherein the proportional valve has an adjustable orifice to control gas flow incrementally with the drive signal. ### Claim 28 (depends on 27) The plasma cutting system of claim 27, wherein a size of the adjustable orifice is controlled by the drive signal. ### Claim 29 (depends on 27) The plasma cutting system of claim 27, wherein the gas flow through the orifice is blocked when the drive signal is terminated, and the controller alters the drive signal to achieve a desired pressure set point based on output pressure feedback from the proportional valve. ### Claim 30 (depends on 29) The plasma cutting system of claim 29, comprising a pressure sensor configured to measure the proportional valve output pressure. ### Claim 31 (depends on 25) The plasma cutting system of claim 25, comprising a flow sensor configured to measure gas flow through the proportional valve. ### Claim 32 (depends on 25) The plasma cutting system of claim 25, comprising an adjustable operating mode selector configured to provide predetermined gas pressure levels. ### Claim 33 (depends on 25) The plasma cutting system of claim 25, wherein the controller compares the drive signal to an expected drive signal of a cutting process performed by the plasma cutting system. ### Claim 34 (depends on 33) The plasma cutting system of claim 33, wherein the controller selectively initiates user notification that the determined input pressure of the plasma cutting system is not at an expected pressure level based on a comparison of the drive signal to the expected drive signal. ### Claim 35 (depends on 33) The plasma cutting system of claim 33, wherein the controller selectively adjusts the input pressure of the plasma cutting system based on a comparison of the drive signal to the expected drive signal. ### Claim 36 (depends on 25) The plasma cutting system of claim 25, comprising a pressure sensor configured to measure one of input pressure and input gas flow. ### Claim 37 A plasma cutting system comprising: a plasma torch; a gas flow system configured to receive pressurized gas; a proportional valve having a control to regulate gas flow; and a controller configured to regulate operation of the proportional valve control by controlling a drive signal sent to the proportional valve control, wherein the controller is configured to determine an input gas pressure of the plasma cutting system based on an output gas pressure and the drive signal. ### Claim 38 (depends on 37) The plasma cutting system of claim 37, comprising an adjustable operating mode selector coupled to the controller to enable selection of a desired cutting operation from a plurality of cutting operations, wherein each cutting operation is associated with predetermined gas flow and gas pressure set points. ### Claim 39 (depends on 38) The plasma cutting system of claim 38, wherein the controller is configured to adjust gas flow and gas pressure to the set points by way of the drive signal sent to the proportional valve. ### Claim 40 (depends on 38) The plasma cutting system of claim 38, wherein the controller is configured to detect an out-of-spec input pressure by comparing an expected drive signal for a given input pressure and output pressure to an actual drive signal for achieving a desired gas pressure set point for the desired cutting operation. ### Claim 41 (depends on 40) The plasma cutting system of claim 40, wherein the controller is configured to selectively adjust the input gas pressure of the plasma cutting system based on a comparison of the actual drive signal to the expected drive signal. ### Claim 42 (depends on 37) The plasma cutting system of claim 37, wherein the drive signal is one of a current signal and a voltage signal. ### Claim 43 (depends on 37) The plasma cutting system of claim 37, wherein the proportional valve contains an orifice regulated by the controller, and wherein a size of the orifice is adjusted by varying the drive signal to the proportional valve control. ### Claim 44 A method comprising: selecting a desired cutting operation to be performed by a plasma cutting system; determining a desired gas pressure set point for the cutting operation; detecting one of an output gas pressure and an input gas pressure upon initiation of the cutting operation; determining a drive signal to achieve the desired gas pressure set point in response to the detected one of the output gas pressure and the input gas pressure; and adjusting gas pressure or gas flow in the plasma cutting system based on the drive signal to bring the output gas pressure toward the desired gas pressure set point. ### Claim 45 (depends on 44) The method of claim 44, comprising determining an input gas pressure based on the output gas pressure and the drive signal. ### Claim 46 (depends on 45) The method of claim 45, comprising detecting if the input gas pressure is out-of-spec by comparing an expected drive signal for a given input gas pressure and output gas pressure to the drive signal to achieve the desired gas pressure set point for the desired cutting operation, and if an out-of-spec input gas pressure is detected, notifying a user thereof.