Thermostat Diagnosis via Electric Pump Control
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Solution Overview
Problem
The existing cooling apparatus for internal combustion engines fails to accurately diagnose thermostat failures at cold starts due to the electric pump being stopped until the cooling water reaches a certain temperature, leading to inappropriate diagnosis.
Innovation Solution
A cooling apparatus configuration that includes a radiator, an electric pump, a first flow path through the radiator, a second flow path without the radiator, a thermostat, and a controller that keeps the electric pump stopped at cold starts until the cooling water reaches a lower second predetermined temperature, then starts the pump and diagnoses thermostat failure based on temperature variations detected by a sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the electric pump is stopped from the beginning of engine start until cooling water reaches a certain temperature level to quickly warm up the engine, then the engine warm-up speed is improved, but the thermostat failure diagnosis accuracy deteriorates
Solution Approach 1:
The system performs preliminary action by stopping the electric pump at cold start to allow rapid engine warm-up. The controller maintains the pump in a stopped state from engine start until cooling water temperature reaches a second predetermined temperature level, thereby quickly raising engine temperature without compromising thermostat diagnosis capability.
Solution Approach 2:
The system uses feedback from temperature sensors to determine when to start the electric pump and perform thermostat diagnosis. The controller monitors cooling water temperature and engine temperature, and only initiates pump operation and thermostat failure diagnosis when both temperatures reach their respective predetermined levels, ensuring accurate diagnosis while maintaining efficient warm-up.
2Productivity
If the electric pump is kept stopped during cold start to raise cooling water temperature quickly, then the engine warm-up efficiency is improved, but the cooling water circulation is reduced, leading to inaccurate thermostat diagnosis
Solution Approach 1:
The system dynamically adjusts electric pump operation based on real-time temperature conditions. The controller keeps the pump stopped during the warm-up phase when temperatures are low, then dynamically switches to pump operation when both cooling water and engine temperatures reach their respective predetermined levels, thereby achieving both efficient warm-up and reliable thermostat diagnosis.
Solution Approach 2:
The system changes the operational parameters of the electric pump based on temperature parameters. By monitoring cooling water temperature and engine temperature, the controller transitions the pump from a stopped state during cold start to an operating state when temperature thresholds are met, enabling accurate thermostat failure diagnosis without compromising warm-up efficiency.
3Measurement precision
If the electric pump is started early to enable thermostat diagnosis, then the thermostat failure diagnosis accuracy is improved, but the engine warm-up speed deteriorates
Solution Approach 1:
The system performs preliminary action by maintaining the electric pump in a stopped state during the critical warm-up phase. The pump remains stopped until both cooling water temperature and engine temperature reach their respective predetermined levels, ensuring rapid engine warm-up. Only after this preliminary warm-up phase does the system initiate pump operation for thermostat diagnosis.
Solution Approach 2:
The system uses temperature parameters as triggers for changing pump operation state. By setting predetermined temperature levels for both cooling water and engine, the system dynamically changes the pump state from stopped to running only when both temperature conditions are satisfied, thereby avoiding premature pump operation that would hinder engine warm-up while ensuring accurate thermostat diagnosis.
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
Ensures accurate diagnosis of thermostat failures by differentiating between normal and open failure conditions through controlled temperature variations, preventing inappropriate diagnosis at cold starts.
Implementation Method 1
a thermostat that is configured to prevent the cooling water from being flowed to the first flow path until temperature of the cooling water in the second flow path reaches a first predetermined temperature
Implementation Method 2
a temperature sensor that is mounted on an upstream side of the radiator in the first flow path to detect temperature of the cooling water in the first flow path
Implementation Method 3
an electric pump that is configured to supply cooling water to an inlet of a cooling water flow path in an internal combustion engine
Data Source
AI summary
A thermostat is diagnosed as open failure when a specified time variation in radiator inflow water temperature from a temperature sensor mounted in a first flow path running through a radiator at a time of starting an electric water pump at a cold start of an engine is equal to or greater than a predetermined variation. In the case of open failure of the thermostat, starting the electric water pump causes cooling water from a cooling water flow path of the engine to be flowed to the first flow path, as well as to a second flow path. The radiator inflow water temperature detected by the temperature sensor mounted in the first flow path is raised by the cooling water from the cooling water flow path of the warmed engine.