Method and system for leak detection at a particulate filter

Patent metadata

Field	Value
Publication number	US-2020300148-A1
Application number	US-201916358588-A
Country	US
Kind code	A1
Filing date	Mar 19, 2019
Priority date	Mar 19, 2019
Publication date	Sep 24, 2020
Grant date	—

Abstract

Methods and systems are provided for diagnosing a gasoline particulate filter in an engine exhaust passage. A pressure-flow relationship of the filter is learned in a low engine speed and high engine speed range. Degradation of the filter is identified based on a substantial separation between the curve fits at the high and low speed range.

First claim

1 . A method for an engine exhaust, comprising:
comparing a first relationship between exhaust flow rate and differential pressure across an exhaust particulate filter, in a first engine speed range, to a second relationship between exhaust flow rate and differential pressure across the particulate filter, in a second engine speed range; and indicating particulate filter degradation based on the comparing.

2 . The method of claim 1 , wherein the indicating includes illuminating a warning light.

3 . The method of claim 1 , wherein the comparing is performed while exhaust flow rate is above a threshold flow rate.

4 . The method of claim 1 , wherein the first engine speed range includes engine speed lower than a threshold speed, and the second engine speed range includes engine speed higher than the threshold speed, and wherein the first engine speed range is non-overlapping with the second speed range.

5 . The method of claim 4 , wherein the comparing includes comparing the first relationship over a first flow and pressure range to the second relationship over the same first flow and pressure range, and wherein the indicating based on the comparing includes indicating no degradation when the first and second relationship are aligned with one another within a threshold, and includes indicating degradation when the first and second relationship are misaligned from one another by greater than the threshold.

6 . The method of claim 1 , wherein the differential pressure is estimated by one of a single gage pressure sensor coupled upstream of the particulate filter in the engine exhaust, a differential pressure sensor coupled across the filter, and a pair of gage pressure sensors coupled upstream and downstream of the filter in the engine exhaust.

7 . The method of claim 1 , wherein the indicating includes indicating degradation responsive to a higher than threshold difference between the first and the second relationship, the threshold difference adjusted as a function of barometric pressure.

8 . The method of claim 1 , wherein the first relationship includes a first curve fit of the exhaust flow rate and the differential pressure measured in the first speed range, and the second relationship includes a second curve fit of the exhaust flow rate and the differential pressure measured in the second speed range.

9 . The method of claim 1 , wherein the indicating includes indicating degradation responsive to, at a given exhaust flow rate, a higher than threshold differential pressure across the filter in the first engine speed range and a lower than threshold differential pressure across the filter in the second engine speed range.

10 . The method of claim 1 , wherein the indicating degradation includes indicating that the filter is leaking or missing, and wherein the exhaust particulate filter is a gasoline particulate filter.

11 . An engine method, comprising:
initiating a monitor responsive to exhaust flow being higher than a threshold rate; incrementing or decrementing a counter based on sensed differential pressure across a gasoline particulate filter relative to a threshold pressure, the threshold pressure based on engine speed; retrieving an output of the counter after a duration since initiating the monitor; and responsive to the output being higher than a threshold value, indicating degradation of the filter.

12 . The method of claim 11 , wherein the threshold pressure is further based on barometric pressure and the incrementing or decrementing includes:
incrementing the counter responsive to sensed differential pressure falling below the threshold pressure; and decrementing the counter responsive to sensed differential pressure exceeding the threshold pressure.

13 . The method of claim 12 , wherein the incrementing includes incrementing the output of the counter by an amount based on a difference between the sensed differential pressure and the threshold pressure, and wherein the decrementing includes decrementing the output of the counter by an amount based on the difference between the sensed differential pressure and the threshold pressure.

14 . The method of claim 11 , wherein the duration is based on a total time spent with flow and engine speed within corresponding target ranges over an average drive cycle.

15 . The method of claim 11 , wherein the sensed differential pressure is sensed via one of a single gage pressure sensor coupled upstream of the particulate filter in an engine exhaust, a differential pressure sensor coupled across the filter, and a pair of gage pressure sensors coupled upstream and downstream of the filter in the engine exhaust.

16 . The method of claim 11 , wherein indicating degradation of the filter includes distinguishing between filter leakage and filter absence based on a measured relationship between the exhaust flow and the sensed differential pressure.

17 . An engine system, comprising:
an engine including an exhaust passage; a gasoline particulate filter coupled in the exhaust passage; one or more gage pressure sensors coupled to the filter for estimating a differential pressure across the filter; a flow sensor coupled upstream of the filter in the exhaust passage for estimating an exhaust flow rate through the filter; and a controller with computer readable instructions stored on non-transitory memory that when executed cause the controller to: measure pressure data via the one or more pressure sensors while the exhaust flow rate is higher than a threshold rate; and in response to a curve fit of the pressure data being lower than a threshold, indicate degradation of the filter, the threshold based on the exhaust flow rate and engine speed.

18 . The system of claim 17 , wherein the engine further comprises an engine intake passage including an intake throttle, and wherein the controller includes further instructions to: responsive to the indicating of degradation, limit an opening of the intake throttle to limit engine output torque.

19 . The system of claim 17 , wherein the indicating degradation includes:
in response to the curve fit of the pressure data being lower than the threshold, incrementing a counter stored in the memory of the controller; and indicating degradation of the filter responsive to an output of the counter, retrieved after a duration of measuring the pressure data, being higher than a threshold value.

20 . The system of claim 17 , wherein the pressure data is measured while engine speed is higher than an idling speed.

Assignees

• Ford Global Tech Llc

Inventors

• Beatham Eric
• Van Nieuwstadt Michiel J
• Lehmen Allen
• Martin Douglas
• Berger Raymond Henry

Classifications

• Y02T10/40

  Engine management systems · CPC title

• Y02T10/12

  Improving ICE efficiencies · CPC title

• F01N2560/05

  the means being a particulate sensor · CPC title

• F01N3/023

  using means for regenerating the filters, e.g. by burning trapped particles · CPC title

• F01N11/002 Primary

  the diagnostic devices measuring or estimating temperature or pressure in, or downstream of the exhaust apparatus · CPC title