Vehicle Cooling System Fail-Safe Control for Sensor Malfunction
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Solution Overview
Problem
Vehicle cooling systems face operational restrictions and safety issues when a water temperature sensor malfunctions, leading to improper engine performance and potential overheating, as existing methods rely solely on a single sensor for temperature measurement and control.
Innovation Solution
A fail-safe control method is implemented using both an inlet and an outlet water temperature sensor, with a flow rate control valve and an exhaust gas recirculation cooler, where a controller diagnoses sensor malfunctions, calculates water temperature based on engine conditions and ambient data, and adjusts the cooling assembly and engine operations to maintain proper functioning even if one or both sensors fail.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single water temperature sensor is used for cooling system control, then the device complexity is reduced, but the reliability deteriorates when the sensor malfunctions
Solution Approach 1:
The cooling system divides temperature measurement into two separate sensors (inlet water temperature sensor and outlet water temperature sensor) positioned at different locations. This segmentation allows the system to identify which specific sensor has failed while maintaining overall system functionality through the other sensor's data.
Solution Approach 2:
The system implements a fail-safe control method that prepares compensation strategies in advance. When one sensor fails, the controller can compensate using data from the functioning sensor along with engine operating conditions, vehicle speed, and ambient temperature to maintain reliable cooling control.
2Object-affected harmful factors
If a limp-home function restricts engine torque and maximizes cooling fan operation, then engine overheating is prevented, but vehicle operating performance deteriorates
Solution Approach 1:
The controller continuously monitors both temperature sensors and engine operating conditions, comparing actual temperatures with expected values based on engine load, speed, and ambient conditions. This feedback mechanism allows the system to distinguish between normal temperature variations and actual overheating conditions, enabling more nuanced control responses.
Solution Approach 2:
The system dynamically adjusts cooling control parameters based on the specific failure mode detected. Instead of always applying maximum cooling fan operation, the controller modifies fan duty cycle and engine torque restrictions based on the calculated compensation temperature, allowing partial maintenance of vehicle performance while preventing overheating.
3Reliability
If the cooling fan is started immediately when a sensor malfunction is detected, then engine overheating is prevented, but unnecessary cooling operation occurs when the thermostat functions properly
Solution Approach 1:
The controller uses feedback from the functioning temperature sensor combined with engine operating conditions to calculate whether actual overheating is occurring. This allows the system to activate the cooling fan only when truly necessary, rather than immediately upon sensor failure detection.
Solution Approach 2:
The system changes the control parameter from binary (fan on/off upon failure) to continuous (fan operation based on calculated temperature deficit). The controller adjusts fan duty cycle proportionally to the temperature difference between actual and expected values, reducing energy consumption when only minor compensation is needed.
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
This method ensures the vehicle can operate safely and efficiently by preventing overheating, even when one or both water temperature sensors are malfunctioning, by compensating for sensor failures and controlling the flow rate and exhaust gas recirculation systems to maintain engine load and cooling performance.
Implementation Method 1
an exhaust gas recirculation cooler disposed between the flow rate control valve and a water pump
Implementation Method 2
maximizing the operation of the cooling fan
Data Source
AI summary
A fail-safe control method for a vehicle cooling system, in which an engine and a vehicle can be properly operated even when a water temperature sensor malfunctions. When only one of two water temperature sensors malfunctions, control may be performed so that an engine and a vehicle can properly operate. When both the two water temperature sensors malfunction, the fail-safe function of the flow rate control valve can be enabled to entirely prevent cooling water from being overheated, thereby improving the reliability of the operation of the vehicle.