Flow-based control method for an engine control valve

• US 6,293,267 B1
• Filed: 03/23/2000
• Issued: 09/25/2001
• Est. Priority Date: 03/23/2000
• Status: Expired due to Fees

• Current Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Original Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Inventors: Maloney, Peter James, Smith, James Craig
• Primary Examiner(s): Wolfe, Willis R.
• Assistant Examiner(s): Castro, Arnold
• Application Number:
  US09/532,431
• Time in Patent Office: 551 Days
• Field of Search: 123/568.21, 123/568.22, 123/339.14, 123/339.19, 123/339.2, 123/399, 701/108
• US Class Current: 123/568.22
• CPC Class Codes: F02D 2041/1433 using a model or simulation of the system
• CPC Class Codes: F02D 35/0007 using electrical feedback F02D35/0015 takes precedence
• CPC Class Codes: F02D 41/0077 Control of the EGR valve or actuator, e.g. duty cycle, closed loop control of position EGR valve position sensor F02M26/48
• CPC Class Codes: F02M 26/47 the characteristics being temperatures, pressures or flow rates
• CPC Class Codes: F02M 26/48 EGR valve position sensors details of the sensor installation in the valve housing F02M26/72
• CPC Class Codes: F02M 26/72 Housings
• CPC Class Codes: Y02T 10/40 Engine management systems

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.

Claims

1. A control methodology for positioning a control valve in a vehicle engine to achieve a commanded mass flow rate of a compressible medium through the valve, comprising the steps of:

collecting valve characterizing data by measuring standard flow rates through the valve for various combinations of valve position and pressure ratio across the valve, subject to standard pressure and temperature conditions of the medium upstream of the valve;

converting the collected valve characterizing data to form a table of standard flow rate in terms of valve position and pressure ratio across the valve;

during operation of the engine, determining a pressure ratio across the valve, and pressure and temperature conditions of the medium upstream of the valve;

addressing the table based on the determined pressure ratio, the commanded flow rate, and the determined pressure and temperature conditions to obtain a position command for the valve; and

controlling the position of the valve based on the position command.

2. The control methodology of claim 1, wherein the step of addressing the table includes the steps of:

determining a standard flow rate corresponding to the commanded flow rate, based on the determined pressure and temperature conditions relative to the standard pressure and temperature conditions; and

addressing the table based on the determined pressure ratio and the determined standard flow rate.

3. The control methodology of claim 2, wherein the standard flow rate is determined in accordance with:

 

FRstd=FRcmd[(Pstd/Pu)* (Tu/Tstd)^½

]

where FRstd is the standard flow rate, FRcmd is the commanded flow rate, Pstd and Tstd are the standard pressure and temperature conditions, and Pu and Tu are the determined pressure and temperature conditions.

4. The control methodology of claim 1, wherein the control valve is an exhaust gas recirculation valve that returns the commanded mass flow rate of engine exhaust gas from an engine exhaust manifold to an engine intake manifold, and the upstream pressure and temperature conditions are the pressure and temperature of the exhaust gas in the engine exhaust manifold.