Thermostat Malfunction Detection via Active Airflow Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing thermostat malfunction detection devices struggle to accurately detect a stuck open state, especially when a vehicle is equipped with an active grill shutter, as the reduced air flow through the radiator can mask temperature differences, leading to undetected malfunctions.
Innovation Solution
A thermostat malfunction detection device that includes an estimated water temperature calculation module, an actual water temperature detection unit, a first determination module for preliminary assessment based on temperature change rates, and a passing air amount control module to increase air flow by opening the grill shutter or activating an electric fan, thereby enhancing the temperature difference and enabling definitive malfunction diagnosis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the grill shutter is closed to reduce air resistance and improve fuel efficiency, then fuel efficiency is improved, but the passing air amount through the radiator is reduced making thermostat malfunction undetectable
Solution Approach 1:
The system performs preliminary determination by monitoring the rate of change of water temperature before making a final malfunction determination. This preliminary action allows the system to detect abnormal cooling rates that indicate thermostat malfunction even when the grill shutter is closed and air flow is restricted
Solution Approach 2:
The system continuously monitors water temperature and compares the actual cooling rate against expected cooling rates based on engine operation conditions. This feedback mechanism enables detection of thermostat malfunction by identifying deviations from normal cooling behavior patterns
2Use of energy by moving object
If the grill shutter is closed to improve fuel efficiency, then fuel efficiency is improved, but the water temperature difference between normal and malfunction states becomes smaller
Solution Approach 1:
The system changes the parameter being monitored from absolute water temperature to the rate of change of water temperature. This parameter transformation allows detection of thermostat malfunction by identifying abnormal cooling rates rather than relying on large temperature differences that may not exist when the grill shutter is closed
3Use of energy by moving object
If the passing air amount is reduced by closing the grill shutter, then fuel efficiency is improved, but the malfunction detection capability is degraded
Solution Approach 1:
The system performs preliminary determination by analyzing the rate of change of water temperature before final malfunction determination. This preliminary analysis of temperature change dynamics enables detection of thermostat malfunction even under restricted air flow conditions where traditional temperature difference methods fail
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 solution effectively increases the water temperature difference between normal and malfunction states, allowing for accurate detection of stuck open thermostat malfunctions even in vehicles with active grill shutters by forcibly increasing air flow, thereby improving detection accuracy.
Implementation Method 1
cooling water that cools a cylinder head, a cylinder liner, and the like of an engine is circulated in a radiator which is a heat exchanger, and is cooled by heat exchange with traveling wind
Data Source
AI summary
A thermostat malfunction detection device that detects a stuck open state of a thermostat includes: an estimated water temperature calculation module that calculates an estimated water temperature of a cooling water based on an operation state of an engine; an actual water temperature detection unit that detects an actual water temperature of the cooling water; a first determination module that establishes preliminary determination when an amount of change of a difference between the estimated water temperature and the actual water temperature within a determined period is equal to or larger than a first threshold value; a passing air amount control module that increases a passing air amount, when the preliminary determination is established; and a second determination module that establishes malfunction determination, when the difference is equal to or larger than a second threshold value, after the passing air amount has been increased.