Control Unit Housing Liquid Ingress Detection Using Humidity and Temperature
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Solution Overview
Problem
Existing methods for detecting liquid entry into control unit housings, such as those caused by leaks, are unreliable and can lead to functional failures in vehicle electronics, compromising safety.
Innovation Solution
A method involving the measurement of temperature and relative humidity variables, combined with power consumption analysis, to detect liquid entry by comparing these variables against predetermined thresholds, using models like August-Roche-Magnus to differentiate between moisture storage effects and actual liquid ingress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If moisture sensors are used to detect condensation by measuring relative humidity, then detection capability is provided, but false positives occur due to local condensation on heat sinks where temperature is below dew point
Solution Approach 1:
The detection system is segmented into multiple independent measurement points (first sensor for temperature, second sensor for relative humidity) positioned at different locations within the housing. This allows differentiation between localized condensation on heat sinks and general humidity increases indicating liquid ingress, thereby resolving false positives while maintaining detection capability.
Solution Approach 2:
The system transitions from single-point humidity measurement to multi-dimensional monitoring by simultaneously measuring temperature and relative humidity at multiple locations. This dimensional expansion enables the system to distinguish between condensation phenomena and liquid ingress by analyzing spatial and temporal patterns across multiple measurement points.
2Reliability
If the housing is sealed to prevent liquid entry, then protection of electronics is improved, but temperature and humidity equalization between inside and outside is hindered
Solution Approach 1:
The system performs preliminary measurements of temperature and relative humidity at multiple locations and stores these values for later comparison. By having baseline data from multiple time points, the system can detect deviations indicating liquid ingress even when the housing is sealed, without requiring the seal to be perfectly airtight for equalization to occur.
Solution Approach 2:
The control unit continuously monitors temperature and humidity measurements, compares them against stored baseline values and predetermined thresholds, and provides feedback to detect liquid ingress. This feedback mechanism allows the system to adapt to sealed housing conditions by identifying anomalies in humidity patterns rather than relying on perfect equalization.
3Measurement precision
If multiple sensors are deployed to improve detection accuracy, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The control unit performs multiple functions: it stores baseline measurement data, processes real-time temperature and humidity measurements, compares measurements against thresholds, and detects liquid ingress. By consolidating these functions in the existing control unit rather than adding dedicated detection hardware, the system achieves high measurement precision without proportionally increasing device complexity.
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
Enhances the reliability of detecting liquid entry by distinguishing between normal moisture dynamics and actual ingress, thereby preventing electronic failures in control units.
Implementation Method 1
measuring a first characteristic variable, which characterizes a temperature within the housing
Implementation Method 2
measuring a second characteristic variable, which characterizes a relative humidity within the housing
Implementation Method 3
local condensation can occur, for example condensation on a heat sink, on which the temperatures are below the dew point
Implementation Method 4
local condensation can occur, for example condensation on a heat sink, on which the temperatures are below the dew point
Data Source
AI summary
A device and method for detecting entry of liquid, in particular liquid including water, for example water, into a housing of a control unit, in particular a control unit of a steer-by-wire steering system are disclosed. The method includes (i) measuring a first characteristic variable, which characterizes a temperature within the housing, (ii) measuring a second characteristic variable, which characterizes a relative humidity within the housing, (iii) storing in each case at least one value of the first characteristic variable and the second characteristic variable, which in each case characterizes a temperature and relative humidity present within the housing at at least one previous point in time, in particular at predetermined time intervals, (iv) determining an operating state of the control unit depending on a power consumption of the control unit and/or the first characteristic variable, wherein the control unit includes a first operating state and a second operating state, wherein the first operating state has a lower power consumption than the second operating state, and (v) detecting the entry of liquid depending on the determined operating state, the first characteristic variable, and the second characteristic variable.