Engine Aircharge Estimation Using Oxygen Sensor Segmentation

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Solution Overview

Problem

Existing methods for estimating intake aircharge in engines using oxygen sensors are inaccurate for torque control due to diluent corrections, leading to excess torque and limited adaptive learning windows, as they require disabling EGR, purge, and crankcase ventilation.

Innovation Solution

Utilizing the unadjusted output of an intake oxygen sensor for fuel control and a diluent-adjusted output for torque control, allowing for accurate fuel and torque estimation independent of diluents, and enabling adaptive fuel learning during EGR, purge, and crankcase ventilation operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If diluent corrected aircharge estimate is used for torque control, then fueling accuracy is improved, but torque production becomes excessive and drivability is affected

Engineering Contradiction:

Improveaircharge estimation accuracyVSAvoidexcess torque

Core Design Contradiction:

Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The patent segments the aircharge estimation into two distinct pathways: one for fuel control (using diluent-corrected oxygen sensor output) and one for torque control (using uncorrected oxygen sensor output). This segmentation allows each pathway to use the appropriate measurement method for its specific purpose, preventing the harmful effect of excess torque while maintaining accurate fueling control.

Inventive Principle:

Principle #1Segmentation

2Measurement precision

If diluent corrections are applied during aircharge estimation, then fuel control accuracy is improved, but adaptive learning window is limited

Engineering Contradiction:

Improveaircharge estimation accuracyVSAvoidadaptive learning window

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent implements dynamic selection of oxygen sensor output processing based on operating conditions. The system can switch between using diluent-corrected output and uncorrected output depending on whether adaptive learning is being performed or normal operation is occurring. This dynamic approach expands the adaptive learning window while maintaining accuracy during normal operation.

Inventive Principle:

Principle #15Dynamics

3Adaptability or versatility

If unadjusted oxygen sensor output is used for fuel control, then adaptive learning can be performed with EGR and purge enabled, but torque estimation accuracy deteriorates

Engineering Contradiction:

Improveadaptive learning windowVSAvoidtorque estimation accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent applies different quality processing to the oxygen sensor output based on the specific control function needed. For torque control applications, the unadjusted output is used to maintain adaptability during learning. For fuel control applications, the diluent-corrected output is used to maintain precision. Each local application receives the appropriate quality of measurement.

Inventive Principle:

Principle #3Local quality

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach improves engine fueling accuracy, expands the adaptive learning window, and enhances engine performance by accurately controlling fuel and torque without compensating for diluents, enabling more comprehensive adaptive learning across various operating conditions.

Implementation Method 1

the sensor measures the partial pressure of oxygen in the aircharge following equilibration

Methodology Applied

Scientific EffectPartial pressure measurement:

Implementation Method 2

a catalyzing oxygen sensor measures the net air concentration that needs a matching amount of fuel

Methodology Applied

Scientific EffectCatalysis: Catalysis

Implementation Method 3

the diluent hydrocarbons that are corrected for during the aircharge estimation participate in cylinder combustion

Methodology Applied

Scientific EffectChemical reaction:

Data Source

PatentUS10876484B2Methods and systems for engine fuel and torque control

Publication Date: 2020.12.29 FORD GLOBAL TECH LLC

AI summary

Methods and systems are provided for accurately estimating intake aircharge based on the output of an intake oxygen sensor while flowing EGR, purge, or PCV hydrocarbons to the engine. The unadjusted aircharge estimate is used for engine fuel control while the hydrocarbon adjusted aircharge estimate is used for engine torque control. A controller is configured to sample the oxygen sensor at even increments in a time domain, stamp the sampled data in a crank angle domain, store the sampled data in a buffer, and then select one or more data samples corresponding to a last firing period from the buffer for estimating the intake aircharge.