Dynamic Engine Auto-Stop Delay Calibration for Battery SOC
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Solution Overview
Problem
In hybrid vehicles, frequent engine stop/start events can lead to battery state of charge (SOC) depletion, causing fuel economy benefits to be lost due to premature engine shutdowns, and potentially compromising system durability.
Innovation Solution
A controller calibrates engine auto-stop delay times based on battery SOC, increasing the delay as SOC decreases and decreasing it as SOC increases, to maintain battery charge above the threshold necessary for engine restart, thereby optimizing fuel economy and system durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If engine auto-stop delay time is kept short to maximize fuel economy benefits, then fuel consumption is reduced, but battery state of charge depletes prematurely causing engine restart failures
Solution Approach 1:
The engine auto-stop delay time is made dynamic rather than fixed. The controller continuously monitors battery state of charge and automatically adjusts the delay time parameter - extending it when battery charge is high and shortening it when battery charge is low - to optimize both fuel economy and ensure reliable engine restart capability throughout the battery charge cycle
Solution Approach 2:
The patent changes the parameter of auto-stop delay time based on the battery state of charge parameter. By establishing a relationship between these two parameters, the system adapts the timing characteristic to match battery conditions, allowing longer delays when battery can support them and shorter delays when battery charge is limited, thus resolving the contradiction between fuel savings and restart reliability
2Reliability
If engine auto-stop delay time is extended to preserve battery charge, then battery state of charge is maintained, but fuel economy benefits are reduced due to prolonged engine idling
Solution Approach 1:
The system dynamically adjusts the auto-stop delay time based on real-time battery state of charge measurements. When battery charge is high, the delay is extended to preserve charge and ensure restart capability. When battery charge is low, the delay is reduced to minimize fuel waste from prolonged idling, thus dynamically balancing battery preservation against fuel economy
Solution Approach 2:
The patent establishes a functional relationship where the auto-stop delay time parameter is modified according to the battery state of charge parameter. This parameter coupling allows the system to optimize the trade-off between maintaining sufficient battery charge and minimizing fuel consumption during idle periods
3Loss of energy
If frequent engine stop/start events are implemented to maximize fuel economy, then fuel consumption decreases, but system durability is compromised
Solution Approach 1:
The system implements periodic engine operation with strategically timed stop/start cycles rather than continuous operation. By controlling the frequency and timing of these periodic stop/start events based on battery charge levels and driving conditions, the system achieves fuel economy benefits while preventing excessive wear that would result from overly frequent cycling
Solution Approach 2:
The auto-stop function is dynamically controlled based on multiple parameters including battery state of charge, engine temperature, and driving conditions. This dynamic control prevents stop/start events under conditions that would harm system durability (such as when battery charge is low or engine is cold) while allowing them when conditions are favorable, thus balancing fuel economy with durability
Data Source
AI summary
A auto-stop/start vehicle with an engine and a battery includes at least one controller that calibrates an engine auto-stop delay time based on a state of charge (SOC) of a battery. The calibrated engine auto-stop delay time increases as the SOC of the battery decreases, and decreases as the SOC of the battery increases. The controller further initiates shutdown of an engine upon expiration of the calibrated engine auto-stop delay time.