Compression Ignition Engine Coolant Temperature Control
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Solution Overview
Problem
In compression ignition engines with superchargers, high engine loads lead to premature ignition timing, increasing combustion noise and NOx emissions, while reducing output torque and fuel efficiency due to elevated combustion chamber temperatures.
Innovation Solution
The engine coolant's target temperature is lowered during high-load operating conditions to prevent excessive combustion chamber temperatures, allowing for a controlled start timing of compression ignition combustion, achieved through a cooling system configuration and valve management in the intake passage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the engine load is high and the supercharger boosts the intake air, then the engine output increases, but the combustion chamber temperature becomes too high causing premature CI combustion start timing
Solution Approach 1:
The patent changes the cooling system parameters by lowering the engine coolant target temperature specifically during high-load operating conditions. This parameter change allows the combustion chamber temperature to be controlled at an appropriate level even when the supercharger is boosting intake air, preventing premature CI combustion start timing while maintaining high engine output.
2Power
If the CI combustion start timing becomes too early, then the combustion chamber pressure and temperature increase abruptly, but combustion noise and NOx emissions increase
Solution Approach 1:
The patent implements a feedback control mechanism where the ECU monitors the operating conditions (load, temperature) and adjusts the engine coolant target temperature accordingly. This feedback loop ensures that the combustion chamber temperature is maintained at levels that prevent premature CI combustion, thereby reducing combustion noise and NOx emissions while preserving combustion efficiency.
Solution Approach 2:
The patent dynamically changes the cooling system parameters based on operating conditions. By lowering the coolant target temperature during high-load conditions, the system controls the combustion chamber temperature to delay CI combustion start timing, effectively reducing harmful emissions and noise.
3Object-generated harmful factors
If the CI combustion start timing is delayed, then the combustion noise and NOx emissions are reduced, but the engine output torque decreases
Solution Approach 1:
The patent optimizes the coolant target temperature parameter to achieve the right balance. By setting an appropriate (lowered but not excessive) target temperature during high-load conditions, the system delays CI combustion timing enough to reduce emissions and noise, while maintaining it early enough to preserve engine output torque and fuel efficiency.
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 prevents premature ignition, reduces combustion noise and NOx emissions, and maintains output torque and fuel efficiency by ensuring suitable ignition timing during high-load operations.
Implementation Method 1
the target temperature of engine coolant to be supplied to a radiator from an engine body is lowered when an operating state of the engine body is in a high-load operating range
Implementation Method 2
as the temperature inside the combustion chamber increases by the generation of heat due to the flame propagation combustion, unburnt mixture gas is self-ignited
Data Source
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AI summary
A compression ignition engine with a supercharger is provided, which includes one or more valves configured to switch a state between a first state where intake air is boosted by the supercharger and a second state where it is not boosted, a fluid temperature adjuster configured to adjust a temperature of engine coolant to be supplied to a radiator from an engine body, and a controller. When the engine operates in a high-load range, the controller controls the combustion mode to be in a compression ignition combustion mode, and causes the valve(s) to be in the first state, and in a low-load range, the controller causes the valve(s) to be in the second state. In the high-load range, the controller outputs a control signal to the fluid temperature adjuster so that a target temperature of the engine coolant is lowered than that in the low-load range.