Hybrid Vehicle Engine Start Control via Acceleration Power Accumulation

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Solution Overview

Problem

Hybrid vehicles experience frequent mode switching from EV to HEV mode due to premature engine start when the accelerator pedal output value decreases, leading to negative impacts on fuel efficiency and state of charge (SOC) management.

Innovation Solution

A method and system that calculate and accumulate the acceleration demanded power from the accelerator pedal sensor when its variance is a positive threshold value, controlling the engine start and switching to the HEV mode only when the accumulated power exceeds a set value, thereby optimizing fuel efficiency and SOC management.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the engine starts when the accelerator pedal output value decreases (conventional mode switching condition), then the battery SOC management is maintained, but the fuel efficiency deteriorates due to unnecessary engine starts

Engineering Contradiction:

Improvefuel efficiencyVSAvoidbattery SOC management

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The system performs preliminary accumulation of acceleration demanded power before triggering engine start. By continuously summing the acceleration demanded power values when variance is positive, the system prepares in advance with an accumulated value, ensuring that engine start occurs only when sufficient acceleration demand has been established, thereby avoiding premature starts while maintaining SOC management.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system uses feedback from the accelerator pedal sensor by continuously monitoring the output value variance and adjusting the accumulation process. When the variance becomes negative (accelerator pedal released), the feedback mechanism stops accumulation and resets the counter, allowing the system to respond dynamically to driver input and avoid unnecessary engine starts.

Inventive Principle:

Principle #23Feedback

2Reliability

If the engine starts frequently to maintain battery SOC, then the battery charge status is managed, but the noise vibration harshness (NVH) increases

Engineering Contradiction:

Improvebattery SOC managementVSAvoidnoise vibration harshness

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The system accumulates acceleration demanded power in advance before triggering engine start. This preliminary accumulation process creates a threshold effect where multiple positive variance events must occur before engine start is activated, thereby reducing the frequency of engine starts and associated NVH while still ensuring battery SOC management is maintained.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If the engine starts based on preset time conditions, then the battery SOC is managed, but the fuel consumption increases

Engineering Contradiction:

Improvebattery SOC managementVSAvoidfuel consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The system changes the parameter for engine start decision from a fixed time-based threshold to a dynamically accumulated acceleration demanded power value. By converting the time-based condition into a power-accumulation-based condition, the system adapts to actual driving demands and only starts the engine when genuine acceleration needs are detected, thereby reducing unnecessary fuel consumption while maintaining SOC management.

Inventive Principle:

Principle #35Parameter changes

4Use of energy by moving object

If the EV mode operates longer to improve fuel efficiency, then the fuel consumption decreases, but the battery charge status deteriorates

Engineering Contradiction:

Improvefuel consumptionVSAvoidbattery charge status

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The system continuously monitors the accelerator pedal sensor output and uses feedback to determine when to extend EV mode operation. By accumulating positive variance values and comparing against a threshold, the system dynamically adjusts EV mode duration based on actual acceleration demands, allowing longer EV operation when appropriate while ensuring battery SOC management is maintained through timely engine starts when needed.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS9145134B2Method and system for controlling engine start of hybrid vehicle

Publication Date: 2015.09.29 HYUNDAI MOTOR CO LTD

AI summary

Provided is a method and a system for controlling engine start of a hybrid vehicle based on acceleration demanded power of a driver. More specifically, a variance of an output signal of an accelerator pedal sensor (APS) senses manipulation of an accelerator pedal reflecting an acceleration demand of a driver. When the variance of the output signal of the accelerator pedal sensor is a positive threshold value, acceleration demanded power corresponding to the output signal of the accelerator pedal sensor is calculated in a section in which the variance is positive and the calculated acceleration demanded power is accumulated. The accumulated acceleration demanded power is then compared with a set power value, and the engine is started to switch from the EV mode to the HEV mode when the accumulated acceleration demanded power is equal to or greater than the set power value.