Hybrid Engine Stop Routine for Quick Restart

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Solution Overview

Problem

The existing engine start/stop systems in hybrid vehicles experience a time delay when restarting the engine, which decreases vehicle drivability, especially when torque is requested during the engine stop routine.

Innovation Solution

The method involves reducing torque in the engine while the clutch remains engaged, then disengaging it to synchronize the engine speed with the electric machine, slowing it to idle, and maintaining the idle state before restarting, allowing for early termination of the stop routine and swift restart when torque is needed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the engine completes its stop routine before commencing restart routine, then the engine stopping is thorough and complete, but the drivability and responsiveness deteriorate due to time delay

Engineering Contradiction:

Improveengine stop completenessVSAvoidengine restart delay

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The system performs preliminary synchronization of engine speed with electric machine speed during the stop routine, so that when restart is requested, the engine is already prepared and can be restarted immediately without waiting for speed matching. This preliminary preparation eliminates the restart delay while maintaining complete stopping.

Inventive Principle:

Principle #10Preliminary action

2Loss of time

If the engine stop routine is terminated early to reduce restart delay, then the drivability improves, but the engine stop completeness may be compromised

Engineering Contradiction:

Improveengine restart delayVSAvoidengine stop completeness

Core Design Contradiction:

Loss of timeVSReliability

Solution Approach 1:

The system maintains continuous readiness for restart by keeping the engine at synchronized speed with the electric machine throughout the stop routine. This continuous state allows the stop routine to be terminated at any point without compromising restart capability, as the engine remains in a restart-ready state throughout the entire stop process.

Inventive Principle:

Principle #20Continuity of useful action

3Loss of energy

If more conditions are specified for ESS stop, then the fuel economy improvement increases, but the complexity of control increases

Engineering Contradiction:

Improvefuel economyVSAvoidcontrol system complexity

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The engine stop routine is designed to serve multiple functions: it achieves complete engine stopping for fuel economy, simultaneously prepares the engine for potential restart by synchronizing speeds, and maintains readiness for torque requests. This multi-functionality allows the same routine to satisfy multiple conditions without requiring separate control logic for each scenario.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS9272698B2Stopping a hybrid engine with engine start anticipation

Publication Date: 2016.03.01 FORD GLOBAL TECH LLC

AI summary

A hybrid electric automotive powertrain includes an engine start/stop system to improve fuel economy. The stop routine provides for quick restarting to avoid delay in a driver change of mind case. The stop routine may be terminated prior to full engine stop when a torque request is received during the stop routine.