Hybrid Starter Generator Torque Learning for Engine Friction

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Solution Overview

Problem

Hybrid and plug-in hybrid vehicles face challenges in accurately learning engine friction torque due to minimized engine idle states, which limits the effectiveness of existing methods that rely on engine idling for torque determination.

Innovation Solution

The use of a Hybrid Starter & Generator (HSG) to provide a torque for maintaining a target engine RPM, allowing for accurate engine friction torque learning even in a stop state, by determining and storing engine friction torque information through a controller module that performs a PUC diagnosis and compares torque generated by the HSG to a moving mean value.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If engine idle state is minimized to improve fuel efficiency in hybrid vehicles, then fuel efficiency is improved, but the ability to perform accurate engine friction torque learning deteriorates

Engineering Contradiction:

Improvefuel efficiencyVSAvoidengine friction torque learning accuracy

Core Design Contradiction:

Loss of energyVSMeasurement precision

Solution Approach 1:

The patent introduces HSG torque as an intermediary measurement to enable engine friction torque learning without requiring engine idle operation. By measuring the torque generated by the HSG during engine start, the system can calculate engine friction torque indirectly, thus resolving the contradiction between minimizing idle time for fuel efficiency and maintaining accurate torque learning capability

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the measurement parameter from engine operating conditions (RPM, load) during idle to HSG-generated torque during engine start. This parameter transformation allows friction torque learning to occur during transient start conditions rather than requiring sustained idle operation, thereby maintaining learning accuracy while improving fuel efficiency

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If engine idle state is required for friction torque learning, then accurate torque learning can be performed, but fuel efficiency deteriorates due to extended idle operation

Engineering Contradiction:

Improveengine friction torque learning accuracyVSAvoidfuel efficiency

Core Design Contradiction:

Measurement precisionVSLoss of energy

Solution Approach 1:

The patent performs friction torque learning during the preliminary engine start phase using HSG torque measurement, rather than requiring a separate dedicated idle learning phase. This preliminary action during necessary engine operations eliminates the need for extended idle operation, thus maintaining learning accuracy without energy penalty

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The HSG torque serves as a mediator that enables friction torque determination during engine start without requiring the engine to be in idle state. This intermediary measurement approach allows learning to occur during necessary transient operations rather than requiring wasteful extended idle operation

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS9914450B2Apparatus and method for learning engine friction torque of hybrid vehicle

Publication Date: 2018.03.13 HYUNDAI MOTOR CO LTD

AI summary

The present disclosure provides a technology of determining an engine friction torque even when idling of an engine is not performed, by providing a certain engine Revolutions per Minute (RPM) in stop state of the engine using Hybrid Starter & Generator (HSG) connected to an engine pulley. The present disclosure provides a technology of determining an accurate engine friction torque using a torque provided from the outside of an engine instead of a torque generated the engine itself.