Method of estimating oxygen storage capacity of catalyst

Patent metadata

Field	Value
Publication number	US-11085848-B2
Application number	US-201916560361-A
Country	US
Kind code	B2
Filing date	Sep 4, 2019
Priority date	Sep 4, 2019
Publication date	Aug 10, 2021
Grant date	Aug 10, 2021

Abstract

A method of estimating the oxygen storage capacity of a catalyst includes providing an engine system having an internal combustion engine and an exhaust system having a catalyst and an oxygen sensor, providing a three-way catalyst observer model having a Kalman filter and a three-way catalyst kinetic model, estimating a three-way catalyst next time step state and a modeling error, linearizing the three-way catalyst observer model, filtering the estimated three-way catalyst next time step state, and calculating a covariance.

First claim

The invention claimed is:

1. A method of estimating an oxygen storage capacity of a three-way catalyst in an engine system having an internal combustion engine with an exhaust system including a three-way catalyst and an oxygen sensor, an engine control module, and a three-way catalyst observer model including a Kalman filter and a three-way catalyst kinetic model with a three-way catalyst thermal model, the method comprising steps of:
sensing a plurality of instant engine control inputs via at least one sensor;
estimating of the oxygen storage capacity of the three-way catalyst based on the plurality of the instant engine control inputs via the three-way catalyst observer model;
calculating an estimated three-way catalyst oxygen storage capacity next time step state using:
{circumflex over (x)} k|k-1 =f ( {circumflex over (x)} k-1|k-1 ,u k ), and
a modeling error using:
{tilde over (y)} k =z k −h ( {circumflex over (x)} k|k-1 ), and
wherein {circumflex over (x)} k-1|k-1 is a previous estimated three-way catalyst oxygen storage capacity, uk represents the plurality of the instant engine control inputs, and z k represents a voltage output of the oxygen sensor;

linearizing the three-way catalyst observer model using:

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filtering the estimated three-way catalyst oxygen storage capacity next time step state to provide an updated estimated three-way catalyst oxygen storage capacity; and
adjusting, using the engine control module, a plurality of engine control parameters based on the updated estimated three-way catalyst oxygen storage capacity.

2. The method of claim 1 , wherein the steps of sensing the plurality of the instant engine control inputs include sensing at least one of a pre-catalyst equivalence ratio, a fuel flow rate, exhaust gas pressure, ambient temperature, a pre-catalyst exhaust gas temperature, oxygen sensor voltage, a metered air per cylinder value, an engine speed value, and a fuel control state value via the at least one sensor.

3. The method of claim 1 , wherein the steps of filtering the estimated three-way catalyst oxygen storage capacity next time step state to provide an updated estimated three-way catalyst oxygen storage capacity further comprise filtering the estimated three-way catalyst oxygen storage capacity next time step state to provide an updated estimated three-way catalyst oxygen storage capacity using:
P k|k-1 =F k P k-1|k-1 F k T <+Q k ,
S k =H k P k|k-1 H k T R k ,
K k =P k|k-1 H k T S k −1 , and
{circumflex over (x)} k|k ={circumflex over (x)} k|k-1 +K k {tilde over (y)} k .

4. The method of claim 3 , further comprising calculating a result covariance for use in calculating the estimated three-way catalyst oxygen storage capacity next time step state using:
P k|k =( I−K k H k ) P k|k-1 .

5. The method of claim 1 , the oxygen sensor is a post oxygen switch sensor.

6. The method of claim 1 , the oxygen sensor is a pre-catalyst wide-range post oxygen sensor.

7. An engine system for a vehicle, the engine system comprising:
an internal combustion engine having an exhaust gas outlet;
an exhaust system having a three-way catalyst and an oxygen sensor, and an exhaust gas inlet in downstream communication with the exhaust gas outlet of the internal combustion engine; and
an engine control module having a control logic sequence which includes:
a first control logic for presenting a plurality of instant engine control inputs being sensed by at least one sensor;
a second control logic for estimating a three-way catalyst oxygen storage capacity next time step state using:
{circumflex over (x)} k|k-1 =f ( {circumflex over (x)} k-1|k-1 ,u k ),
and a modeling error using:
{tilde over (y)} k =z k −h ( {circumflex over (x)} k|k-1 ),
wherein {circumflex over (x)} k-1|k-1 is a previous estimated three-way catalyst oxygen storage capacity, U k represents the plurality of the instant engine control inputs, and z x represents a voltage output of the oxygen sensor;

a third control logic for linearizing the three-way catalyst observer model using:

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Assignees

• Gm Global Tech Operations Llc

Inventors

• Sun Min
• Davis Jonathan M
• Fedewa Andrew M
• Wittkopp Scott H
• Cimini Gionata

Classifications

• F02D2200/0814

  Oxygen storage amount · CPC title

• F01N2900/0406

  using a model with a division of the catalyst or filter in several cells · CPC title

• F01N2900/1624

  Catalyst oxygen storage capacity · CPC title

• F01N11/00 Primary

  Monitoring or diagnostic devices for exhaust-gas treatment apparatus · CPC title

• F02D2200/0816

  Oxygen storage capacity · CPC title