Engine Torque Estimation Using Cylinder Pressure Timing

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Solution Overview

Problem

Existing engine torque estimators face challenges in accurately calculating engine torque during transient driving due to variations in combustion states, particularly in assessing pump loss torque, which affects the precision of engine torque estimation.

Innovation Solution

An engine torque estimator that includes a cylinder internal pressure sensor, an indicated-torque calculating unit, a pump loss torque calculating unit, and an engine torque calculating unit, where the indicated torque and pump loss torque are calculated based on cylinder internal pressure detected from the exhaust stroke of a previous combustion cycle to the expansion stroke of the current cycle, allowing for advanced computation timing and improved accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If pump loss torque is calculated using intake pressure and rotational speed during transient driving, then calculation speed is maintained, but measurement precision of engine torque deteriorates due to combustion state variations

Engineering Contradiction:

Improvecalculation speedVSAvoidengine torque estimation accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent performs preliminary calculation of pump loss torque during the exhaust stroke of the previous combustion cycle, before the current combustion cycle begins. This advance calculation allows the engine control unit to have torque data ready before transient conditions fully develop, improving response time without sacrificing accuracy during combustion variations.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent replaces the conventional method of calculating pump loss torque based on intake pressure and rotational speed with a method based on cylinder internal pressure detection. By using cylinder pressure data from the exhaust stroke, the system achieves more accurate pump loss torque calculation that accounts for actual combustion state variations, substituting a more direct measurement approach for the indirect calculation method.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If engine torque is calculated after completion of all combustion cycles, then data accuracy is improved, but loss of time increases due to delayed control response

Engineering Contradiction:

Improvetorque calculation accuracyVSAvoidcontrol response time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The system performs preliminary calculation of indicated torque and pump loss torque during the exhaust stroke of the previous combustion cycle. This allows the engine control unit to prepare torque data in advance, reducing the time delay between combustion events and control actions while maintaining calculation accuracy through proper sequencing of computational steps.

Inventive Principle:

Principle #10Preliminary action

3Measurement precision

If cylinder internal pressure is detected throughout the entire combustion cycle, then measurement precision is improved, but use of energy increases due to continuous sensing requirements

Engineering Contradiction:

Improvepressure detection accuracyVSAvoidenergy consumption for sensing

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent extracts only the essential pressure data from the exhaust stroke of the previous combustion cycle that is needed for torque calculation. Instead of continuously monitoring pressure throughout the entire combustion cycle, the system selectively uses pressure information during the exhaust stroke period, reducing energy consumption while maintaining the precision needed for accurate torque estimation.

Inventive Principle:

Principle #2Taking out (Extraction)

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 solution enables accurate detection of engine torque and enhances control response by calculating engine torque earlier in the cycle, reducing computation load and improving precision in transient driving conditions.

Implementation Method 1

a cylinder internal pressure sensor configured to detect a pressure in the cylinder as a cylinder internal pressure

Methodology Applied

Scientific EffectPressure detection:

Data Source

PatentUS10048167B2Engine torque estimator for internal combustion engine and method of estimating engine torque for internal combustion engine

Publication Date: 2018.08.14 HONDA MOTOR CO LTD

AI summary

An engine torque estimator for an internal combustion engine, includes a cylinder internal pressure sensor, an indicated-torque calculator, a pump loss torque calculator, and an engine torque calculator. The cylinder internal pressure sensor detects a cylinder internal pressure in a cylinder. The indicated-torque calculator calculates an indicated torque in a second combustion cycle based on the cylinder internal pressure detected in a period from an exhaust stroke in a first combustion cycle to an expansion stroke in the second combustion cycle. The second combustion cycle that follows the first combustion cycle. The pump loss torque calculator calculates a pump loss torque in the second combustion cycle based on the cylinder internal pressure detected in the period. The engine torque calculator calculates an engine torque of the internal combustion based on the indicated torque and the pump loss torque.