Method for determining load on particulate filter for engine exhaust, including estimation of ash content

• US 6,405,528 B1
• Filed: 11/20/2000
• Issued: 06/18/2002
• Est. Priority Date: 11/20/2000
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Carberry, Brendan Patrick, Christen, Urs, Moraal, Paul Eduard
• Primary Examiner(s): Denion, Thomas
• Assistant Examiner(s): NGUYEN, TU MINH
• Application Number:
  US09/716,650
• Time in Patent Office: 575 Days
• Field of Search: 602/74, 602/77, 602/86, 602/97, 603/11, 603/03, 602/95, 502/304
• US Class Current: 60/295
• CPC Class Codes: F01N 11/002 the diagnostic devices measuring or estimating temperature or pressure in, or downstream of the exhaust apparatus
• CPC Class Codes: F01N 13/0097 the purifying devices are arranged in a single housing
• CPC Class Codes: F01N 2550/04 Filtering activity of particulate filters
• CPC Class Codes: F01N 2560/08 the means being a pressure sensor
• CPC Class Codes: F01N 3/035 with catalytic reactors , e.g. catalysed diesel particulate filters
• CPC Class Codes: F01N 9/002 of filter regeneration, e.g. detection of clogging
• CPC Class Codes: F02B 29/0406 Layout of the intake air cooling or coolant circuit
• CPC Class Codes: F02B 37/22 by varying cross-section of exhaust passages or air passages , e.g. by throttling turbine inlets or outlets or by varying effective number of guide conduits F02B37/24 takes precedence
• CPC Class Codes: F02D 2200/0812 Particle filter loading
• 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: Y02T 10/40 Engine management systems

Abstract

A method for determining the load on an internal combustion engine exhaust particulate filter optimizes filter regeneration by determining the portion of the filter load constituted by accumulated ash. In one technique, the ash load is determined by recording the lowest value of DPF load over a time or distance interval. In another technique, an estimate is made of the amount of load remaining at each of a plurality of DPF regeneration events; the amount of remaining load immediately following the regeneration event corresponds to the amount of accumulated ash in the DPF. DPF load estimation is performed using equations for laminar or turbulent flow in pipes. These equations establish a linear or quadratic relationship between the flow through the DPF and the pressure drop measured across it.

Claims

1. A method of estimating the amount of inert, incombustible material accumulated in a particulate filter for an internal combustion engine exhaust, comprising the steps of:

(A) repeatedly measuring the backpressure load in said filter over a preselected interval, said backpressure load resulting from the trapping and accumulation of both combustible and said inert materials in said filter, the amount of said backpressure load varying over time in part as a result of said filter being periodically regenerated; and

(B) determining the smallest backpressure load measured in step (A) over said interval, said smallest determined backpressure load being related to said accumulated amount of inert material.

2. The method of claim 1, wherein step (B) includes:

storing at least certain of the loads measured in step (A) in a memory, and

updating said memory each time a load measured in step (A) is lower than the load currently stored in said memory, whereby said memory maintains storage of the lowest value of the load determined in step (A) during said interval.

3. The method of claim 2, including the step of recording the time during said each time said memory is updated.

4. A method of estimating the amount of inert material accumulated in a particulate filter for an internal combustion engine exhaust, comprising the steps of:

(A) regenerating said filter by increasing the temperature of exhaust gas entering said filter to a level sufficient to incinerate combustible particulates trapped in said filter and representing a backpressure load;

(B) detecting the end point of step (A);

(C) after completing step (B), determining the remaining load in said particulate filter, said remaining load being related to the accumulated amount of said inert material in said filter;

(D) successively repeating steps (A)-(C); and

(E) determining the minimum amount of remaining load determined over the successively repeated steps.

5. The method of claim 4, wherein step (B) is performed by sensing a change in temperature of the exhaust gas flowing through said filter.

6. The method of claim 4, wherein step (C) is performed by measuring the pressure drop across said filter after said endpoint has been detected in step (B).

7. The method of claim 4, wherein step (B) is performed by determining the rate of change of said measured backpressure load.

8. A method of determining the load in a particulate filter for an internal combustion engine resulting from the accumulation of incombustible particulates in said filter over a preselected interval, wherein the total load in said filter includes both said incombustible and combustible particulates, comprising the steps of:

(A) determining the value of the load in said filter at a first time point during said preselected interval;

(B) storing the value determined in step (A) in a memory;

(C) determining the value of said load in said filter at each of a plurality of time points during said subsequent to said first time point;

(D) comparing the values determined in step (C) with the value stored in step (B); and

(E) updating said memory based on the comparison performed in step (D) when the comparison performed in step (D) indicates that the value of the load determined at a subsequent time point is less than the previously stored load value, the value stored in said memory at the end of said interval representing said incombustible particulate load.

9. The method of claim 8, including the step of storing the value of an engine running time each time said memory is updated.