Vehicle Heater Core Coolant Flow Control for Extended Engine Auto-Stop
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Solution Overview
Problem
When an engine is automatically stopped, the HVAC system's ability to cool air diminishes due to stagnant refrigerant, leading to increased cabin temperature and potential engine restart, which affects fuel economy.
Innovation Solution
A system with a bypass valve and flapper valve control module that adjusts coolant flow and airflow through the heater core to maintain cabin temperature during engine auto-stop, using the heater core as a cold storage device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the engine is automatically stopped to improve fuel economy, then fuel consumption is reduced, but the HVAC system's ability to cool air diminishes due to stagnant refrigerant, leading to increased cabin temperature and potential engine restart
Solution Approach 1:
The system performs preliminary cooling of the heater core coolant and preliminary charging of the evaporator refrigerant before the engine auto-stop event. This ensures that the HVAC system maintains cooling capability during the engine stop period, allowing the engine to remain stopped longer and thus improving fuel economy without compromising cabin temperature comfort.
Solution Approach 2:
The system changes the temperature parameter of the heater core coolant to a lower value before engine stop, and adjusts refrigerant flow parameters in the evaporator. These parameter changes enable the HVAC system to maintain effective cooling during the engine auto-stop period, resolving the contradiction between fuel savings and cabin temperature control.
2Loss of energy
If the engine is automatically stopped to improve fuel economy, then fuel consumption is reduced, but the engine restarts prematurely due to inadequate cooling capacity
Solution Approach 1:
The control system performs preliminary actions before engine stop including cooling the heater core coolant and charging the evaporator with sufficient refrigerant. This preparation extends the duration the engine can remain stopped by ensuring adequate HVAC cooling capacity is available during the stop period, thus maximizing fuel economy benefits without premature restart.
Solution Approach 2:
The system uses feedback from temperature sensors and system state monitoring to dynamically adjust the auto-stop duration. By continuously monitoring cabin temperature, evaporator temperature, and coolant temperature, the system can extend the engine stop period as long as cooling requirements are met, optimizing the balance between fuel savings and HVAC performance.
3Temperature
If coolant flows continuously through the heater core to maintain cabin temperature, then cooling capacity is maintained, but coolant energy is wasted when the engine is stopped
Solution Approach 1:
The system performs preliminary cooling of the heater core coolant before the engine stop event. This pre-cooling stores thermal energy in the coolant, eliminating the need for continuous coolant circulation during the engine stop period. The coolant can remain stagnant without compromising cabin temperature control, thus saving pump energy and reducing unnecessary thermal energy transfer.
Solution Approach 2:
The system extracts the cooling function from the active coolant circulation system and stores it in the pre-cooled heater core coolant and charged evaporator refrigerant. This allows the coolant circulation to be stopped or reduced during engine auto-stop, eliminating energy waste from continuous coolant flow while maintaining cabin temperature control capability.
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
Extends the engine auto-stop period, improving fuel economy by maintaining desired cabin temperatures and reducing the need for premature engine restarts.
Implementation Method 1
The bypass valve control module is configured to adjust a bypass valve to a bypass position to prevent engine coolant from flowing from the engine to a heater core of the vehicle when the engine is stopped independent of the ignition system
Implementation Method 2
Engine coolant flowing through the heater core rejects heat to air flowing through the heater core, thereby heating the air
Implementation Method 3
The position of the flapper valve controls the amount of airflow through the heater core in order to achieve a desired air temperature within a cabin of the vehicle
Implementation Method 4
Refrigerant flowing through coils in the evaporator absorbs heat from air flowing across coils in the evaporator, thereby cooling the air
Data Source
AI summary
A system according to the present disclosure includes a start-stop module, a bypass valve control module, and a flapper valve control module. The start-stop module is configured to stop an engine of a vehicle independent of an ignition system of the vehicle. The bypass valve control module is configured to adjust a bypass valve to a bypass position to prevent engine coolant from flowing from the engine to a heater core of the vehicle when the engine is stopped independent of the ignition system. The flapper valve control module is configured to control a flapper valve to adjust an amount of airflow from an evaporator of the vehicle to a cabin of the vehicle through the heater core.