Engine Cooling Control Preventing Local Boiling
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Solution Overview
Problem
The existing cooling apparatus for internal combustion engines faces the challenge of local boiling of cooling water in narrow channels when the target temperature is set near the boiling point, leading to increased risk of boiling as the flow rate through the radiator decreases.
Innovation Solution
A control unit is implemented to adjust the circulation flow rate using a feedforward model, reducing the flow rate as the target temperature increases and decreasing it further when the radiator outlet water temperature drops, and dynamically changing the target temperature to prevent local boiling by increasing the flow rate when boiling is predicted.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the target temperature of cooling water is set to a temperature in the vicinity of the boiling point to reduce friction, then friction between pistons and cylinders is decreased, but local boiling of cooling water is liable to occur in narrow flow channels
Solution Approach 1:
The control unit predicts the risk of local boiling before it occurs by calculating a boiling risk indicator based on the relationship between circulation flow rate and engine outlet water temperature. When the indicator exceeds a threshold, the control unit preemptively adjusts the flow rate control valve to increase circulation flow rate, preventing local boiling before it happens rather than reacting after it occurs.
Solution Approach 2:
The system implements a feedback mechanism where the control unit continuously monitors the circulation flow rate and engine outlet water temperature, calculates a boiling risk indicator based on their relationship, and adjusts the flow rate control valve accordingly. This closed-loop control ensures that the circulation flow rate is maintained at levels that prevent local boiling while still allowing the system to operate at optimal temperatures for reducing friction.
2Force
If the opening degree of the flow rate control valve is reduced to maintain cooling water temperature near the boiling point, then friction is reduced, but the risk of local boiling increases immediately
Solution Approach 1:
The control unit calculates a boiling risk indicator that predicts when local boiling might occur based on the current circulation flow rate and engine outlet water temperature. Before the actual boiling occurs, the control unit adjusts the flow rate control valve to increase the circulation flow rate, preemptively eliminating the harmful effect rather than allowing it to manifest.
Solution Approach 2:
The system uses feedback control where the control unit continuously monitors the relationship between circulation flow rate and engine outlet water temperature, calculates a boiling risk indicator, and adjusts the flow rate control valve in real-time. This ensures that the circulation flow rate is maintained at sufficient levels to prevent local boiling while still allowing the cooling water temperature to be optimized for friction reduction.
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 approach effectively suppresses local boiling of cooling water by maintaining an optimal flow rate, reducing the risk of boiling without significantly increasing fuel consumption, thus ensuring efficient engine cooling.
Implementation Method 1
a cooling apparatus for an internal combustion engine that circulates cooling water between the internal combustion engine and a radiator
Implementation Method 2
a feedforward model that is constructed so as to reduce the circulation flow rate with increasing the target temperature of the engine outlet water temperature and with decreasing a radiator outlet water temperature
Data Source
AI summary
A change in a valve opening degree from an opening degree (a) to an opening degree (d) is caused by a decrease in a radiator outlet water temperature, and at such time a flow rate through a radiator enters a boiling region. Therefore, when such entry is predicted, a target engine outlet water temperature is forcedly changed from 105° C. to 100° C. Thereupon, the valve opening degree is changed from the opening degree (a) to an opening degree (f). The flow rate through the radiator when the valve opening degree is the opening degree (f) is greater than the flow rate through the radiator when the valve opening degree is the opening degree (d), and furthermore, the flow rate through the radiator does not enter the boiling region while the valve opening degree is changing from the opening degree (a) to the opening degree (f).