Hybrid Engine Cold Start Speed Control via Phase Transition

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Solution Overview

Problem

Electrically-variable transmissions face challenges in starting internal combustion engines during cold conditions due to batteries with narrow operating ranges, which can be damaged by charging spikes, and existing methods do not effectively control engine speed without interacting electric machines.

Innovation Solution

A hybrid powertrain system that includes an internal combustion engine, an energy storage device, and an electro-mechanical transmission with electric machines, allowing for controlled engine start by initiating crankshaft rotation, controlling engine speed with electric machines until a flare threshold, and then managing speed through combustion parameters without electric machine interaction, reducing high charging spikes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the electric machine is used to control engine speed during the entire engine firing process, then engine speed control is maintained, but the battery is subjected to high charging spikes that can damage it

Engineering Contradiction:

Improvebattery reliabilityVSAvoidcharging spikes

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The engine start process is divided into distinct phases: an initial phase where the electric machine controls engine speed, and a subsequent phase where combustion parameter control takes over. This segmentation allows the electric machine to disengage before charging spikes occur, protecting the battery while maintaining speed control through combustion adjustments in the later phase.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system performs preliminary speed control using the electric machine during the initial engine firing phase, then transitions to combustion parameter control before the charging spike condition occurs. This preliminary action ensures the engine is properly stabilized before the electric machine disengages, preventing the need for later electric intervention that would cause battery damage.

Inventive Principle:

Principle #10Preliminary action

2Measurement precision

If the electric machine interacts with the engine throughout the firing process, then engine speed control is precise, but the complexity of the control system increases

Engineering Contradiction:

Improveengine speed control precisionVSAvoidcontrol system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The control system dynamically transitions between two control modes: electric machine-based speed control during the initial phase, and combustion parameter-based control during the firing phase. This dynamic switching reduces complexity by allowing each control method to operate in its optimal phase without requiring continuous complex coordination between both systems.

Inventive Principle:

Principle #15Dynamics

3Adaptability or versatility

If the engine is started during cold conditions, then the hybrid powertrain can operate, but the battery with narrow operating range is at risk from charging spikes

Engineering Contradiction:

Improvepowertrain operational capabilityVSAvoidbattery reliability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The system converts the potentially harmful charging spike condition into a beneficial control transition point. By detecting when charging spikes would occur, the system uses this moment to switch from electric machine control to combustion parameter control, thereby protecting the battery while maintaining engine operation capability during cold conditions.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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

The system effectively starts the engine during cold conditions while minimizing battery charging spikes and maintaining control over engine speed, ensuring efficient operation within the battery's operating range.

Implementation Method 1

initiating rotation of a crankshaft of the engine with the at least one electric machine until a first predetermined crankshaft speed is achieved

Methodology Applied

Scientific EffectElectromagnetic conversion: Electromagnetic Induction

Implementation Method 2

firing the engine while controlling engine speed with the at least one electric machine until a flare threshold occurs

Methodology Applied

Scientific EffectElectromagnetic conversion: Electromagnetic Induction

Data Source

PatentUS8620505B2Stand alone engine speed control at cold start for hybrid transmission

Publication Date: 2013.12.31 GM GLOBAL TECHNOLOGY OPERATIONS LLC

AI summary

A hybrid powertrain includes and internal combustion engine, an energy storage device, an electro-mechanical transmission having at least one electric machine rotatably coupled to the engine. The electro-mechanical transmission is selectively controllably operative to transmit torque among the engine and the at least one electric machine. A method to start operation of the internal combustion engine includes initiating rotation of a crankshaft of the engine with the at least one electric machine until a first predetermined crankshaft speed is achieved, firing the engine while controlling engine speed with the at least one electric machine until a flare threshold occurs, controlling the engine speed without any interaction from the at least one electric machine based on controlling combustion parameters of the engine, and when a predetermined condition occurs, controlling the engine speed with the at least one electric machine while the engine is still firing.