EV Heat Pump HVAC Dry Mode to Prevent Windshield Flash Fogging
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Solution Overview
Problem
The existing electric vehicle air conditioning systems using a heat pump system with a 4-way valve experience flash fogging on the windshield when the system is switched from cooling mode to heating mode, due to moisture evaporation in the internal heat exchanger.
Innovation Solution
A control method and system that determines the current air conditioning mode and enters an internal heat exchanger dry mode when switching from cooling to heating, performing a drying operation using the heater core, blower fan, and compressor to remove residual moisture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a heat pump system with a 4-way valve is applied to an electric vehicle air conditioning system, then heating function is improved, but flash fogging occurs on the windshield when switching from cooling mode to heating mode
Solution Approach 1:
The patent applies preliminary action by introducing a pre-heating process before the main heating mode. When switching from cooling to heating mode, the system first activates the heater core to warm the internal heat exchanger and evaporate stored moisture, then transitions to the main heating operation. This preliminary moisture removal prevents flash fogging on the windshield while maintaining the desired heating functionality.
2Object-affected harmful factors
If the internal heat exchanger is dried before switching to heating mode, then flash fogging is prevented, but additional control complexity and operation time are required
Solution Approach 1:
The patent merges the drying function with the existing heater core that is already part of the HVAC system. Instead of adding a separate drying mechanism, the system utilizes the heater core's heating capability to evaporate moisture from the internal heat exchanger during mode transition. This integration avoids increasing device complexity while effectively preventing flash fogging.
Solution Approach 2:
The control system implements preliminary action by automatically activating the heater core before switching to heating mode. This pre-heating phase removes moisture from the internal heat exchanger, preventing flash fogging during the subsequent heating operation. The control logic seamlessly integrates this preliminary step into the mode transition process.
3Speed
If the air conditioning system operates in heating mode immediately after cooling mode, then response time is improved, but moisture evaporation causes flash fogging
Solution Approach 1:
The patent applies preliminary action by inserting a brief pre-heating phase between cooling mode shutdown and heating mode startup. During this intermediate phase, the heater core activates to warm the internal heat exchanger and evaporate stored moisture before the main heating operation begins. This preliminary step prevents flash fogging while maintaining relatively fast response time.
Solution Approach 2:
The system implements periodic action through staged heating operation. Instead of immediate full-power heating, the heater core activates first for moisture removal, then the main heating system engages. This periodic, multi-phase approach prevents flash fogging while minimizing overall delay in achieving desired heating效果.
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
Prevents flash fogging on the windshield by ensuring the internal heat exchanger is dry before switching to heating mode, enhancing safety and reducing power consumption by optimizing the air conditioning system's operation.
Implementation Method 1
a heater core supplied with cooling water to heat air discharged through the internal heat exchanger
Implementation Method 2
a blower fan to blow air to the internal heat exchanger
Implementation Method 3
a compressor configured to compress and discharge a refrigerant
Implementation Method 4
a 4-way valve configured to transfer the refrigerant discharged from the compressor to an external heat exchanger or an internal heat exchanger according to air conditioning modes
Implementation Method 5
the external heat exchanger configured to heat exchange between the refrigerant transferred from the compressor or the internal heat exchanger and air outside a vehicle
Implementation Method 6
the internal heat exchanger configured to heat exchange between the refrigerant transferred from the external heat exchanger and air supplied inside a HVAC module
Data Source
AI summary
Proposed is an electric vehicle air conditioning system and a control method therefor, the air conditioning system being capable of preventing a phenomenon in which flash fogging occurs on a windshield. The method for the electric vehicle air conditioning system includes determining whether a current air conditioning mode is set to a cooling mode or a heating mode, determining whether a request for entering an internal heat exchanger dry mode is received when the current air conditioning mode is set to the heating mode, entering the internal heat exchanger dry mode and performing an drying operation of an internal heat exchanger for a predetermined time when the request for entering the internal heat exchanger dry mode is received, and operating a set normal heating mode when the internal heat exchanger dry mode is finished.