Vehicle Cabin Air Recirculation Control for Windshield Condensation

Solution Overview

Problem

The use of cabin air for heating in vehicles increases the risk of condensation on the windshield due to higher moisture content, and existing HVAC systems struggle to efficiently manage this while optimizing energy consumption.

Innovation Solution

A continuous-feedback loop control system that adjusts cabin air recirculation based on sensor inputs, performing a mass balance to optimize the ratio of recirculated and external air, and adjusts HVAC blower valve and speed to maintain a dew point temperature below the window glass temperature, thereby preventing condensation and reducing battery consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If recirculated air from the cabin is used for heating, then energy consumption is reduced, but condensation risk on the windshield increases

Engineering Contradiction:

Improveheating energy consumptionVSAvoidcondensation on windshield

Core Design Contradiction:

Use of energy by moving objectVSObject-affected harmful factors

Solution Approach 1:

The control module continuously monitors cabin humidity levels and adjusts the recirculation valve position in real-time based on sensor feedback. When humidity approaches levels that could cause condensation, the system automatically reduces recirculation intensity or switches to fresh air mode, thereby preventing condensation while maximizing energy savings during safe operating conditions.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system dynamically adjusts the recirculation valve position and blower motor speed based on real-time humidity conditions rather than operating in fixed modes. This allows the system to optimize the balance between energy efficiency and condensation prevention by continuously adapting recirculation intensity to current cabin environmental conditions.

Inventive Principle:

Principle #15Dynamics

2Loss of energy

If recirculated air with higher moisture content is used, then heating efficiency improves, but the risk of condensation formation increases

Engineering Contradiction:

Improveheating energy lossVSAvoidmoisture accumulation

Core Design Contradiction:

Loss of energyVSObject-generated harmful factors

Solution Approach 1:

The control module continuously monitors cabin humidity levels and adjusts the recirculation valve position in real-time based on sensor feedback. When humidity approaches levels that could cause condensation, the system automatically reduces recirculation intensity or switches to fresh air mode, thereby preventing condensation while maximizing energy savings during safe operating conditions.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system changes operational parameters (recirculation valve position, blower speed) based on humidity levels to maintain optimal balance between energy efficiency and condensation prevention

Inventive Principle:

Principle #35Parameter changes

3Object-affected harmful factors

If the HVAC system increases fresh air intake to prevent condensation, then condensation risk decreases, but energy consumption increases

Engineering Contradiction:

Improvecondensation preventionVSAvoidheating energy consumption

Core Design Contradiction:

Object-affected harmful factorsVSUse of energy by moving object

Solution Approach 1:

The control module continuously monitors cabin humidity levels and adjusts the recirculation valve position in real-time based on sensor feedback. When humidity approaches levels that could cause condensation, the system automatically reduces recirculation intensity or switches to fresh air mode, thereby preventing condensation while maximizing energy savings during safe operating conditions.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system dynamically adjusts the recirculation valve position and blower motor speed based on real-time humidity conditions rather than operating in fixed modes. This allows the system to optimize the balance between energy efficiency and condensation prevention by continuously adapting recirculation intensity to current cabin environmental conditions.

Inventive Principle:

Principle #15Dynamics

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

The system effectively prevents condensation on vehicle windows while minimizing energy usage, enhancing battery life in electric vehicles and fuel efficiency in internal combustion vehicles.

Implementation Method 1

The system uses a mass balance on the interior of the vehicle to monitor and reduce the amount of dissolved water vapor in the passenger cabin

Methodology Applied

Scientific EffectMass balance:

Implementation Method 2

maintain a dew point temperature below the window glass temperature, thereby preventing condensation

Methodology Applied

Scientific EffectCondensation: Condensation

Data Source

PatentUS20250313061A1Air recirculation control system

Publication Date: 2025.10.09 MAHLE INT GMBH

AI summary

A method of controlling air recirculation via a continuous-feedback loop control system that adjusts cabin air recirculation in vehicles based on a number of different sensor inputs. The system uses a mass balance on the interior passenger compartment of the vehicle to monitor and reduce the amount of dissolved water vapor in the cabin, leading to reduced risk of condensation while simultaneously improving battery consumption.