Flow-based control method for an engine control valve

Abstract

An improved control methodology for an engine control valve, in which the valve is positioned in response to a commanded flow rate of the controlled medium. The method involves a valve characterization procedure in which the actual flow rate is measured for various combinations of valve position and pressure ratio across the valve, subject to a standard set of upstream pressure and temperature values. This results in a table of valve position in terms of pressure ratio and standard flow rate—that is, flow rate under the standard upstream pressure and temperature values. In operation, a controller addresses the table to obtain the desired valve position as a function of a determined pressure ratio across the valve, and a desired standard flow rate determined based on the commanded flow rate and the pressure and temperature of the controlled medium upstream of the valve, relative to the standard pressure and temperature values. The required calibration effort is significantly reduced compared to the usual ad-hoc approach, and the control is based on the physical characteristics of the valve so that the commanded flow rate can be scheduled based on engine control considerations. Additionally, the control is modular in nature, which minimizes the re-design and re-calibration efforts required due to changes in system design.

Dependencies are inferred from the claim text.