Real-time, table-based estimation of diesel engine emissions

• US 7,676,318 B2
• Filed: 11/21/2007
• Issued: 03/09/2010
• Est. Priority Date: 12/22/2006
• Status: Expired due to Fees

• Current Assignee: Detroit Diesel Corporation (Mercedes-Benz Group AG)
• Original Assignee: Detroit Diesel Corporation (Mercedes-Benz Group AG)
• Inventors: Allain, Marc Christian
• Primary Examiner(s): WOLFE JR, WILLIS RAY
• Application Number:
  US11/943,826
• Publication Number:
  US 20080149081A1
• Time in Patent Office: 839 Days
• Field of Search: 701101-105, 701109-111, 701/115, 123/568.11, 123/568.21, 123/672, 602/74, 602/85, 60299-300, 603/11, 702182-185, 702/187, 702/188
• US Class Current: 701/103
• CPC Class Codes: F02B 29/0406 Layout of the intake air cooling or coolant circuit
• CPC Class Codes: F02B 3/06 with compression ignition compression ignition engines using air or gas for blowing fuel into compressed air in cylinder F02B13/02
• CPC Class Codes: F02B 37/00 Engines characterised by provision of pumps driven at least for part of the time by exhaust
• CPC Class Codes: F02D 2200/1012 Engine speed gradient
• CPC Class Codes: F02D 41/021 Introducing corrections for particular conditions exterior to the engine conjoint control of vehicle sub-units for propelling the vehicle B60W30/18
• CPC Class Codes: F02D 41/029 the exhaust gas treating apparatus being a particulate filter
• CPC Class Codes: F02D 41/045 Detection of accelerating or decelerating state detection thereof in general G01P
• CPC Class Codes: F02D 41/1462 with determination means using an estimation
• CPC Class Codes: F02D 41/1467 with determination means using an estimation
• CPC Class Codes: F02M 26/05 High pressure loops, i.e. wherein recirculated exhaust gas is taken out from the exhaust system upstream of the turbine and reintroduced into the intake system downstream of the compressor
• CPC Class Codes: F02M 26/23 Layout, e.g. schematics
• CPC Class Codes: F02M 26/48 EGR valve position sensors details of the sensor installation in the valve housing F02M26/72

Abstract

A real-time, on board, diesel engine emissions estimation with an empirical, table-based approach that accounts for up to eight (8) input parameters, for optimum emissions estimation under steady state or transient engine operation. The method considers a steady state NOx model, steady state Particulate Matter model, transient NOx model and transient Particulate Matter models to populate a table in memory. The switch between steady state and transient models, real time emissions estimations is based on the rate of change of engine speed (RPM). If the rate of change of RPM exceeds a predetermined threshold, transient models for NOx and Particulate Matter are used to operate the engine and reduce emissions of NOx and Particulate Matter.

Claims

1. A method to operate an electronically controlled internal combustion engine equipped with an electronic control unit (ECU) having memory and tables resident therein to provide real time estimation of engine out emissions;

said method comprising;

determining a steady state NOx model for engine emissions based a combination of more than one two dimensional tables whose inputs are engine speed, engine load, fresh air flow rate, EGR flow rate, injection timing and injection pressure to populate tables in memory with values, summing outputs of said tables and saturating the outputs to populate tables in memory with values representative of steady state NOx emissions;

determining a steady state particulate matter model for engine emissions based upon a combination of more than one two dimensional tables whose inputs are engine speed, engine load, fresh air flow rate, EGR flow rate, injection timing and injection pressure to populate tables in memory with values, summing outputs of said tables and saturating the outputs to populate tables in memory with values representative of steady state particulate matter emissions;

determining a transient NOx model made of a combination of two dimensional tables whose inputs are engine speed, engine load, fresh air flow rate, EGR flow rate, injection timing, injection pressure, rate of change of engine speed and rate of change of engine load, summing outputs of said tables and saturating the outputs to populate tables in memory with values representative of steady state particulate matter emissions;

determining a transient particulate matter model made of a combination of two dimensional tables whose inputs are engine speed, engine load, fresh air flow rate, EGR flow rate, injection timing, injection pressure, rate of change of engine speed and rate of change of engine load, summing outputs of said tables and saturating the outputs to populate tables in memory with values representative of steady state particulate matter emissions; and

switching between steady state and transient models for real time estimation of engine emissions based upon a rate of change of engine speed.

2. The method of claim 1, wherein said steady state NOx model is made based upon a combination of three two dimensional tables.

3. The method of claim 1, wherein said steady state particulate models is made based upon a combination of three two dimensional tables.

4. The method of claim 1, wherein said transient state NOx model is made upon a combination of four two dimensional tables.

5. The method of claim 1, wherein said transient particulate matter model is made based upon a combination of four two dimensional tables.

6. The method claim 1, wherein when said engine switches operation from a steady state model to a transient state model when the engine speed rate of change exceeds 10 RPM per second.

7. The method of claim 1, further including generation said tables according to the formula:

z=c₁x²+c₂y²+c₃y²+c₄y+c₅x²y²+c₆xy+c₇x²y+c₈xy²+c₉

wherein;

z is the table output;

z=a*c

a is the following vector;

a=[x² x y² y x²y² xy x²y xy² 1]

c=[a′

*a]<sup>−

1</sup>*a′

*z

x is the tablets first input (row input)

y is the table'"'"'s second input (column input)

c₁, c₂, c₃, c₄, c₅, c₆, c₇, c₈, and c₉ are the coefficients of the polynomial.

8. The method of claim 1, wherein said engine speed is determined from crankshaft magnetic pick-up sensors.

9. The method of claim 1, wherein fresh air flow rate is determined from at least one of a percentage of EGR as measured by a venture across a differential pressure sensor or hot film mass flow sensor, or as an estimation using mass balance across an engine intake and exhaust system.

10. The method of claim 1, wherein said change of engine load is determined by a change in fueling rate of the engine.