Vehicle Heater Coolant Switching to Prevent EV Mode Temperature Drop
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Solution Overview
Problem
In vehicle air conditioners, when switching the flow path for heating the heat transfer medium from the first flow path to the second flow path, the temperature of the heat transfer medium in the second flow path may drop due to exposure to outside air at a low temperature.
Innovation Solution
The vehicle air conditioner includes a control device that mixes the heat transfer medium from the first flow path with a coolant from a third flow path before switching to the second flow path, thereby preventing a significant temperature drop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the three-way valve switches the flow path from the first flow path to the second flow path, then the heat transfer medium can be heated by the second heat source, but the temperature of the heat transfer medium in the second flow path drops due to exposure to outside air
Solution Approach 1:
The control device performs preliminary action by switching the three-way valve to the third opening state before switching to the second flow path. This allows the heat transfer medium in the third flow path to be heated in advance by the second heat source, so that when the system switches to the second flow path, the temperature drop is minimized because the medium has already been pre-heated.
Solution Approach 2:
The third flow path acts as an intermediary between the first and second flow paths. The control device uses this intermediate state to gradually transition the heat transfer medium from one heating source to another, allowing the medium to be progressively heated by the second heat source before full switching occurs, thereby reducing thermal shock and temperature instability.
2Productivity
If the heat transfer medium circulates in the second flow path that is closed by the three-way valve, then the flow path can be optimized for EV mode, but the temperature of the stagnant heat transfer medium drops due to low temperature outside air
Solution Approach 1:
The control device maintains continuity of useful action by keeping the second heat source active and the third flow path open during the transition period. Even when the system is in EV mode with the second flow path closed, the second heat source continues to heat the heat transfer medium in the third flow path, ensuring continuous heating action and preventing temperature drop of stagnant medium.
Solution Approach 2:
The system uses self-service by having the second heat source serve dual purposes: it heats the heat transfer medium for EV mode operation and simultaneously maintains the temperature of stagnant medium in the third flow path. The heat transfer medium essentially serves itself by circulating through the third flow path and being heated, eliminating the need for additional heating measures.
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
This configuration effectively suppresses the temperature drop of the heat transfer medium in the second flow path during the switching process, maintaining the heater core temperature.
Implementation Method 1
the control device controls opening and closing of the three-way valve so as to mix the heat transfer medium in the first flow path and the heat transfer medium in the third flow path before the switching
Implementation Method 2
In the first flow path, the heat transfer medium is heated by heat from a first heat source
Implementation Method 3
In the second flow path, the heat transfer medium is heated by heat from a second heat source
Data Source
AI summary
The engine, the heater, and the heater core are connected by pipes. When the traveling mode is HEV traveling mode or the engine single traveling mode, a flow path formed of pipes is formed, and the coolant is heated by the engine to heat the heater core. When the traveling mode is EV traveling mode, a flow path including a pipe is formed, and the coolant is heated by the heater to heat the heater core.