Stop/Start Engine Controller Defrost Activation Logic
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Solution Overview
Problem
Stop/start vehicles face challenges in managing engine auto-stop and auto-start functions when a rear defroster is activated, particularly due to insufficient battery charge to support electric current draw, leading to unnecessary engine idling and driver surprise from immediate engine restarts.
Innovation Solution
Implementing a controller that delays engine auto-start and defroster activation after a defroster request and inhibits engine auto-stop if the battery charge is insufficient, with a calibratable time interval and alert signaling to the driver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the engine is immediately restarted upon defroster activation request, then the defroster can be activated without delay, but the fuel conservation benefit of auto-stop is lost and driver surprise occurs
Solution Approach 1:
The system performs preliminary assessment of battery state of charge before committing to engine restart. The controller evaluates whether the battery can support the defroster load before activating the engine, allowing the engine to remain stopped when battery charge is sufficient, thereby conserving fuel while still enabling defroster operation when needed.
Solution Approach 2:
The system dynamically adjusts the engine restart decision based on real-time battery state of charge conditions. Rather than following a fixed immediate-restart policy, the controller adapts the restart timing and defroster activation strategy based on current battery capacity, optimizing the balance between defroster responsiveness and fuel conservation.
2Loss of energy
If the engine remains auto stopped to conserve fuel, then fuel efficiency is improved, but the battery may become insufficient to support the electric current draw of the defroster
Solution Approach 1:
The controller continuously monitors battery state of charge and uses this feedback to make informed decisions about engine restart timing and defroster activation. When the battery state of charge falls below a threshold required to support defroster operation, the system feedback triggers an engine restart to recharge the battery, ensuring reliable defroster functionality while minimizing unnecessary restarts.
Solution Approach 2:
The system performs preliminary assessment of battery state of charge before committing to defroster activation or engine restart decisions. By evaluating battery capacity in advance, the controller can determine whether the engine should remain stopped or restart, preventing situations where the battery cannot support the defroster load.
3Speed
If the engine is restarted immediately when defroster is requested, then the defroster activates quickly, but driver surprise occurs due to unexpected engine start
Solution Approach 1:
The controller performs preliminary evaluation of battery state of charge before initiating engine restart. This preliminary assessment allows the system to inform the driver of the upcoming engine restart in advance, giving the driver time to prepare mentally and reducing the surprise effect, while still enabling relatively quick defroster activation when battery charge is sufficient.
Data Source
AI summary
A method for controlling a stop/start vehicle includes commanding an engine auto start in response to a calibratable time interval elapsing after receiving an electric defroster activation request when the engine is auto stopped. The method may further include activating a defroster after the engine has been auto started. The method may additionally include activating a defroster indicator when the electric defroster activation is received. The method may further include inhibiting an engine auto stop in response to an electric defroster activation request when the engine is running and further in response to a battery charge being insufficient to support a predicted current draw, and signaling an alert to a vehicle driver.