HVAC Mode Door Actuator Control for Windshield Condensation
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Solution Overview
Problem
Automotive HVAC systems face challenges in preventing external condensation on vehicle windshields during high-temperature and high-humidity conditions, which can impair driver visibility and compromise passenger comfort by degrading cooling performance when attempting to address condensation through temperature adjustments or air flow modifications.
Innovation Solution
A method involving a controller that adjusts the voltage applied to mode door actuators and sets specific operating conditions for the defrost, air blower, and air distribution outlets to minimize external condensation without degrading the cooling performance, including closing or partially closing the defrost outlet, adjusting the air blower voltage, and automatically operating the windshield wiper when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the temperature of air directed toward the front windshield is increased or the flow of air toward the front windshield is blocked to remove external condensation, then external condensation is removed, but the cooling performance of the passenger compartment deteriorates and passenger comfort is reduced
Solution Approach 1:
The air distribution system is segmented into separate controllable outlets: a front outlet for the front windshield and a rear outlet for the rear windshield. This allows independent control of air flow to each windshield, enabling condensation prevention at the front windshield without affecting cooling performance in the passenger compartment through the rear outlet
Solution Approach 2:
Different air flow characteristics are applied to different regions: heated air is directed specifically to the front windshield to prevent condensation, while cooled air is maintained in the passenger compartment for comfort. The mode door actuator locally adjusts the front outlet opening degree to achieve this localized quality difference
2Illumination intensity
If air is directed toward the front windshield in defrost mode, floor mode, or mix mode to improve visibility, then windshield visibility is improved, but external condensation occurs on the windshield
Solution Approach 1:
The system changes the temperature parameter of air directed to the front windshield by heating it before delivery. This parameter change prevents condensation formation on the windshield surface while maintaining air flow to improve visibility, resolving the contradiction between visibility and condensation prevention
Solution Approach 2:
The mode door actuator dynamically adjusts the opening degree of the front outlet based on detected condensation conditions and voltage signals. This dynamic adjustment allows the system to respond to changing environmental conditions and maintain optimal air flow characteristics to prevent condensation while preserving visibility
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
Effectively prevents or minimizes external condensation on vehicle windshields while maintaining the cooling performance of the passenger compartment by strategically managing air flow and outlet openings, ensuring driver safety and comfort.
Implementation Method 1
The evaporator cools the air
Implementation Method 2
the heater core heats the air entering the passenger compartment
Data Source
AI summary
A method of controlling an automotive heating, ventilation, and air conditioning (HVAC) system includes steps of: comparing, by a controller, a voltage applied to a mode door actuator with a first operating voltage, a second operating voltage, and a third operating voltage when a driving condition of a vehicle meets an external condensation occurrence condition; and controlling, by the controller, a defrost mode door to close a defrost outlet or adjust an opening degree of the defrost outlet to be less than a reference opening degree when the voltage applied to the mode door actuator is greater than or equal to the first operating voltage, where the defrost outlet directs air toward a front windshield, and the reference opening degree is an opening degree of the defrost outlet which has been set when the driving condition of the vehicle does not meet the external condensation occurrence condition.