Vehicle Engine Stop Control Device Using Average Charging Current
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Solution Overview
Problem
Existing control devices for vehicles with engine stop and start systems struggle to determine the optimal time for engine stop and restart based on battery charging state, leading to potential engine failure due to insufficient battery power during restart.
Innovation Solution
A control device that includes a battery current detecting unit, battery temperature detecting unit, deceleration state detecting unit, fuel supply stop unit, average charging current calculating unit, and SOC estimating unit to determine the State of Charge (SOC) of the battery and calculate engine stoppable time, allowing for automatic engine stop and restart based on the charging state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the engine stop and start device is used to improve fuel efficiency, then fuel consumption is reduced, but the battery may not have sufficient charge for engine restart
Solution Approach 1:
The system performs preliminary actions by detecting deceleration states and calculating average charging currents before engine restart is needed. It estimates SOC in advance and determines engine stoppable time, ensuring the battery will have sufficient charge when restart is required, thus preventing restart failures while maintaining fuel efficiency benefits.
Solution Approach 2:
The system implements feedback by continuously monitoring battery current during deceleration, calculating average charging current, and estimating SOC. This feedback loop allows the control device to adjust engine stop decisions based on real-time battery charging state, ensuring reliable restart while maximizing fuel efficiency through intelligent stop timing.
2Loss of energy
If the engine is stopped frequently to improve fuel efficiency, then fuel consumption is reduced, but the battery charging state becomes unpredictable
Solution Approach 1:
The system performs preliminary calculation of average charging current during deceleration phases before engine stop decisions are made. By calculating the average current over the deceleration period and using it to estimate SOC in advance, the system achieves precise prediction of battery charging state, enabling reliable fuel efficiency optimization through accurate stop timing control.
3Loss of energy
If regenerative charging is used to charge the battery during deceleration, then fuel efficiency is improved, but the battery current varies making SOC estimation difficult
Solution Approach 1:
The system performs preliminary calculation of average charging current during the entire deceleration phase before making engine stop decisions. By integrating and averaging the variable battery current over the deceleration period, the system obtains a stable representative value that accurately reflects the charging state, enabling precise SOC estimation despite current variations during regenerative charging.
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
Enables accurate determination of engine stop and restart feasibility and calculates the optimal engine stop time, ensuring reliable engine operation and improved fuel efficiency by utilizing regenerative energy for battery charging during vehicle deceleration.
Implementation Method 1
a battery current detecting unit configured to detect an electric current of the battery
Implementation Method 2
a battery configured to supply electric power to the engine stop and start device
Implementation Method 3
a regenerative charging device which charges a battery using energy during deceleration of the vehicle
Data Source
AI summary
A control device for a vehicle including an engine stop and start device includes a battery and a vehicle speed detecting unit and includes a battery current detecting unit, a battery temperature detecting unit, a deceleration state detecting unit, a fuel supply stop unit, an average charging current calculating unit, and an SOC estimating unit. The control device calculates, with the average charging current calculating unit, an average of a battery current in a predetermined time from detection of a stop of fuel supply to an engine in a deceleration state of the vehicle. The control device permits a stop of the engine when an SOC calculated by the SOC estimating unit is larger than a predetermined value.