# US 11,441,466 B2 · Systems and methods for determining exhaust flow rate

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- Number: US 11,441,466 B2
- Document ID: US11441466B2
- Status: Granted
- Kind: B2
- Application number: 16/968,952
- Filed: 2018-02-15
- Published: 2020-11-26
- Granted: 2022-09-13
- Earliest claimed: 2018-02-15
- Assignees: Cummins Emission Solutions Inc.
- Applicants: Cummins Emission Solutions Inc.
- Inventors: Tarek Elharis
- Web page: https://patentgrep.com/patent/US11441466B2

## CPC

- F01N 3/208: {Control of selective catalytic reduction [SCR], e.g. by adjusting the dosing of reducing agent}
- F01N 3/2803: {characterised by structure, by material or by manufacturing of catalyst support}
- F01N 9/00: Electrical control of exhaust gas treating apparatus (monitoring or diagnostic devices for exhaust-gas treatment apparatus F01N11/00; conjoint electrical control of two or more combustion engine functions F02D43/00)
- G01F 9/00: Measuring volume flow relative to another variable, e.g. of liquid fuel for an engine
- G01N 33/0037: {NOx}
- F01N 2430/06: by varying fuel-air ratio, e.g. by enriching fuel-air mixture
- F01N 2560/025: for measuring or detecting O2, e.g. lambda sensors
- F01N 2560/026: for measuring or detecting NOx
- F01N 2560/07: the means being an exhaust gas flow rate or velocity meter or sensor, intake flow meters only when exclusively used to determine exhaust gas parameters
- F01N 2610/02: the substance being ammonia or urea
- F01N 2900/08: said parameters being related to the engine
- F01N 2900/1402: Exhaust gas composition
- F01N 2900/1411: Exhaust gas flow rate, e.g. mass flow rate or volumetric flow rate
- F01N 2900/1812: Flow rate
- F01N: GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES (arrangements in connection with gas exhaust of propulsion units in vehicles B60K13/00; combustion-air intake silencers specially adapted for, or arranged on, internal-combustion engines F02M35/00; protecting against, or damping, noise in general G10K11/16)
- G01F: MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)

## Abstract

A system for determining an exhaust flow rate of an exhaust gas produced by an engine comprises a first sensor configured to measure an amount of NOx gases in the exhaust gas. A controller is communicatively coupled to the first sensor. The controller is configured to receive a first sensor signal from the first sensor. The controller is also configured to receive a fuel rate signal corresponding to a rate of fuel consumption by the engine. The controller is configured to determine an air-fuel ratio from the first sensor signal and determine a fuel rate from the fuel rate signal. Furthermore, the controller is configured to determine the exhaust flow rate from the air-fuel ratio and the fuel rate.

## Claims

### Claim 1

A system for determining an exhaust flow rate of an exhaust gas produced by an engine, comprising:
a first sensor comprising a NOx sensor configured to measure an amount of NOx gases in the exhaust gas, the first sensor further configured to measure an amount of oxygen included in the exhaust gas; and
a controller communicatively coupled to the first sensor, the controller configured to:
receive a first sensor signal from the first sensor;
receive a fuel rate signal corresponding to a rate of fuel consumption by the engine;
determine an oxygen fraction in the exhaust gas from the first sensor signal;
determine an air-fuel ratio from the oxygen fraction;
determine a fuel rate from the fuel rate signal; and
determine the exhaust flow rate from the air-fuel ratio and the fuel rate.

### Claim 2 (depends on 1)

The system of claim 1, wherein the controller is further configured to adjust an amount of a reductant inserted into the exhaust gas based on the determined exhaust flow rate.

### Claim 3 (depends on 1)

The system of claim 1, wherein the controller is further configured to:
determine a stoichiometric coefficient comprising a ratio of the air-fuel ratio to a stoichiometric air fuel ratio from the oxygen fraction; and
determine the air-fuel ratio from the stoichiometric coefficient.

### Claim 4 (depends on 1)

The system of claim 1, wherein:
the oxygen fraction comprises an oxygen molar fraction; and
the controller is further configured to:
determine an oxygen mass fraction from the oxygen molar fraction; and
determine the air-fuel ratio from the oxygen mass fraction.

### Claim 5 (depends on 1)

The system of claim 1, wherein the controller is configured to determine the exhaust flow rate using the following equation:
exhaust flow rate=(1+air−fuel ratio)× fuel rate.

### Claim 6 (depends on 1)

The system of claim 1, further comprising:
a fuel rate sensor configured to be operably coupled to the engine, the fuel rate sensor being configured to determine the fuel rate and generate the fuel rate signal;
wherein the controller is communicatively coupled to the fuel rate sensor and configured to receive the fuel rate signal therefrom.

### Claim 7

An aftertreatment system for treating an exhaust gas produced by an engine, the aftertreatment system comprising:
a selective catalytic reduction system;
a first sensor comprising a NOx sensor configured to measure an amount of NOx gases in the exhaust gas flowing into the selective catalytic reduction system, the first sensor further configured to measure an amount of oxygen included in the exhaust gas; and
a controller communicatively coupled to the first sensor, the controller configured to:
receive a first sensor signal from the first sensor;
receive a fuel rate signal corresponding to a rate of fuel consumption by the engine;
determine an oxygen fraction in the exhaust gas from the first sensor signal;
determine an air-fuel ratio from the oxygen fraction;
determine a fuel rate from the fuel rate signal; and
determine an exhaust flow rate from the air-fuel ratio and the fuel rate.

### Claim 8 (depends on 7)

The aftertreatment system of claim 7, further comprising a reductant insertion assembly configured to insert a reductant into the selective catalytic reduction system, wherein the controller is communicatively coupled to the reductant insertion assembly and configured to adjust an amount of the reductant inserted into the selective catalytic reduction system based on the determined exhaust flow rate.

### Claim 9 (depends on 7)

The aftertreatment system of claim 7, wherein the selective catalytic reduction system comprises:
an inlet conduit configured to receive the exhaust gas,
a catalyst formulated to decompose constituents of the exhaust gas, and
an outlet conduit configured to expel treated exhaust gas,
wherein the first sensor is positioned in the inlet conduit.

### Claim 10 (depends on 7)

The aftertreatment system of claim 7, wherein the controller is further configured to:
determine a stoichiometric coefficient comprising a ratio of the air-fuel ratio to a stoichiometric air-fuel ratio from the oxygen fraction; and
determine the air-fuel ratio from the stoichiometric coefficient.

### Claim 11 (depends on 7)

The aftertreatment system of claim 7, wherein:
the oxygen fraction comprises an oxygen molar fraction;
the controller is further configured to determine an oxygen mass fraction from the oxygen molar fraction; and
determine the air-fuel ratio from the oxygen mass fraction.

### Claim 12 (depends on 7)

The aftertreatment system of claim 7, wherein the controller is configured to determine the exhaust flow rate using the following equation:
exhaust flow rate=(1+air−fuel ratio)× fuel rate.

### Claim 13 (depends on 7)

The aftertreatment system of claim 7, further comprising:
a fuel rate sensor configured to be operably coupled to the engine, the fuel rate sensor configured to determine the fuel rate and generate the fuel rate signal,
wherein the controller is communicatively coupled to the fuel rate sensor and configured to receive the fuel rate signal therefrom.

### Claim 14

A method of determining an exhaust flow rate of an exhaust gas produced by an engine, the method comprising:
determining an oxygen fraction in the exhaust gas;
determining an air-fuel ratio of the exhaust gas based on the oxygen fraction;
determining a fuel rate corresponding to a rate of consumption of a fuel by the engine;
determining the exhaust flow rate from the air-fuel ratio and the fuel rate;
generating an exhaust flow rate signal indicative of the exhaust flow rate; and
adjusting an amount of a reductant inserted into the exhaust gas based on the determined exhaust flow rate.

### Claim 15 (depends on 14)

The method of claim 14, further comprising:
determining a stoichiometric coefficient comprising a ratio of the air-fuel ratio to a stoichiometric air-fuel ratio from the oxygen fraction;
wherein the air-fuel ratio is determined from the stoichiometric coefficient.

### Claim 16 (depends on 14)

The method of claim 14, wherein:
the oxygen fraction comprises an oxygen molar fraction;
the method further comprises determining an oxygen mass fraction from the oxygen molar fraction; and
the air-fuel ratio is determined from the oxygen mass fraction.

### Claim 17 (depends on 14)

The method of claim 14, wherein the exhaust flow rate is determined using the following equation:
exhaust flow rate=(1+air−fuel ratio)× fuel rate.

### Claim 18

A control circuitry for determining an exhaust flow rate of an exhaust gas produced by an engine, the control circuitry comprising:
a controller configured to be a communicatively coupled to a first sensor, the first sensor configured to measure an amount of NOx gases in the exhaust gas, the controller being configured to:
receive a first sensor signal from the first sensor;
receive a fuel rate signal corresponding to a rate of fuel consumption by the engine;
determine an oxygen fraction in the exhaust gas from the first sensor signal;
determine an air-fuel ratio from the oxygen fraction;
determine a fuel rate from the fuel rate signal;
determine the exhaust flow rate from the air-fuel ratio and the fuel rate; and
generate an exhaust flow rate signal indicative of the exhaust flow rate.

### Claim 19 (depends on 18)

The control circuitry of claim 18, wherein the controller is further configured to adjust an amount of a reductant inserted into the exhaust gas based on the determined exhaust flow rate.

### Claim 20 (depends on 18)

The control circuitry of claim 18, wherein the controller is further configured to:
determine a stoichiometric coefficient comprising a ratio of the air-fuel ratio to a stoichiometric air fuel ratio from the oxygen fraction; and
determine the air-fuel ratio from the stoichiometric coefficient.

### Claim 21 (depends on 18)

The control circuitry of claim 18, wherein:
the oxygen fraction comprises an oxygen molar fraction; and
wherein the controller is further configured to:
determine an oxygen mass fraction from the oxygen molar fraction, and
determine the air-fuel ratio from the oxygen mass fraction.