Volumetric Efficiency Estimation Using Cam Phaser Lookup Tables

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Solution Overview

Problem

Existing engine control systems with intake and exhaust cam phasers face challenges in accurately calculating volumetric efficiency (VE) due to increased complexity, leading to higher calibration efforts and reduced accuracy, especially when using mathematical relationships.

Innovation Solution

An engine control module employs a hybrid method combining table look-ups and mathematical functions to estimate VE, using a parked VE estimate and additional terms based on engine speed, load, intake cam phaser, and exhaust cam phaser positions, reducing calibration complexity and improving accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If mathematical relationships are used to calculate VE for engines with intake and exhaust cam phasers, then the system can handle the complexity of variable cam positions, but calibration effort and time increase significantly

Engineering Contradiction:

Improveability to handle cam phaser positionsVSAvoidcalibration time

Core Design Contradiction:

Adaptability or versatilityVSLoss of time

Solution Approach 1:

The patent segments the VE calculation into two distinct parts: a parked VE lookup table for base values and mathematical adjustment terms for cam phaser deviations. This segmentation allows the system to handle variable cam positions without requiring complete recalibration of the entire VE model, reducing calibration time while maintaining adaptability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent performs preliminary action by pre-calculating and storing the parked VE values in a lookup table before runtime operation. This pre-computed base VE data eliminates the need to calculate entire VE models during calibration, reducing calibration effort while preserving the ability to adapt to different cam positions through adjustment terms.

Inventive Principle:

Principle #10Preliminary action

2Adaptability or versatility

If mathematical relationships are used to calculate VE for engines with intake and exhaust cam phasers, then the system can accommodate variable valve timing, but accuracy may be reduced

Engineering Contradiction:

Improveability to handle cam phaser positionsVSAvoidVE estimation accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent changes parameters by separating the VE model into a parked VE base (stored in lookup table) and dynamic adjustment terms (mathematical relationships involving cam phaser positions, MAP, and RPM). This parameter separation maintains accuracy by preserving the detailed parked VE characteristics while adding adaptability through the adjustment terms that account for cam phaser deviations.

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If lookup tables are used for VE calculation, then the method is simple for engines without cam phasers, but it becomes cumbersome when intake and exhaust cam phasers are added

Engineering Contradiction:

Improvesimplicity of VE calculationVSAvoidcomplexity of VE table structure

Core Design Contradiction:

Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent segments the VE data structure into a compact parked VE lookup table and separate mathematical adjustment terms. This segmentation keeps the lookup table simple and small (containing only parked position data) while handling cam phaser complexity through external mathematical relationships, thus maintaining ease of implementation without increasing table complexity.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS20090024296A1System and method for estimating volumetric efficiency for engines with intake and exhaust cam phasers

Publication Date: 2009.01.22 GM GLOBAL TECHNOLOGY OPERATIONS LLC

AI summary

An engine control module comprises a table that outputs a parked VE estimate based on an input parameter when intake and exhaust cam phasers of an engine are in a parked position. A calculation module calculates VE estimate when the intake and exhaust cam phasers are not in a parked position based on the parked VE estimate and a mathematical relationship.