Dual-Circuit Coolant Control for Engine and EGR Cooling
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Solution Overview
Problem
Current cooling systems struggle to efficiently manage engine cooling and exhaust gas recirculation under varying external temperatures, leading to increased NOx emissions and fuel consumption, especially with stringent exhaust regulations like RDE.
Innovation Solution
A coolant control system with a high temperature radiator and a low temperature radiator, along with a control method that uses sensors and valves to selectively direct coolant flow through a water-cooled intercooler, managed by a controller, to optimize cooling efficiency based on vehicle operation and ambient conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single cooling system is used for both engine cooling and EGR cooling, then the system structure is simple, but the cooling efficiency decreases under varying external temperatures
Solution Approach 1:
The cooling system is divided into two independent circuits: a high-temperature cooling circuit for engine cooling and a low-temperature cooling circuit for EGR cooling. This segmentation allows each circuit to be optimized for its specific function and operating conditions, resolving the contradiction between system simplicity and cooling efficiency.
Solution Approach 2:
The water-cooled intercooler serves multiple functions: it acts as a heat exchanger for the low-temperature cooling circuit, provides aftercooling for EGR gas, and can be bypassed when not needed. This multi-functionality maintains system efficiency across varying external temperatures without requiring excessive complexity.
2Reliability
If coolant flows through the water-cooled intercooler in all conditions, then EGR cooling is maintained, but intake air temperature increases in cold conditions
Solution Approach 1:
The system uses dynamic control through bypass valves and a thermostat to adjust coolant flow paths based on real-time temperature conditions. In cold conditions, the bypass valve directs coolant away from the intercooler, preventing excessive cooling of intake air. This dynamic adjustment resolves the contradiction between maintaining EGR cooling and preventing intake air temperature increase.
Solution Approach 2:
Temperature sensors provide feedback to the control unit, which adjusts the bypass valve and thermostat positions accordingly. This feedback mechanism ensures the system automatically adapts to changing thermal conditions, maintaining optimal EGR cooling while preventing intake air temperature issues in cold conditions.
3Reliability
If the high temperature coolant pump operates continuously, then engine cooling is maintained, but fuel consumption increases
Solution Approach 1:
The high-temperature coolant pump operates periodically rather than continuously, activating only when the thermostat detects that cooling is required. This periodic operation maintains engine cooling reliability while significantly reducing fuel consumption compared to continuous pump operation.
Solution Approach 2:
The thermostat automatically controls coolant flow based on engine temperature, eliminating the need for continuous pump operation. The system self-regulates by opening the coolant passage when cooling is needed and closing it when the engine is warm, reducing energy consumption while maintaining cooling reliability.
4Reliability
If the low temperature coolant pump operates continuously, then EGR cooling is maintained, but fuel consumption increases
Solution Approach 1:
The low-temperature coolant pump operates periodically based on control unit signals that monitor thermal conditions. The pump activates only when EGR cooling is required and deactivates when cooling demand is low, maintaining EGR cooling reliability while minimizing fuel consumption.
Solution Approach 2:
Temperature sensors and the control unit provide feedback to regulate low-temperature coolant pump operation. This feedback control ensures the pump operates only when necessary for EGR cooling, resolving the contradiction between maintaining cooling reliability and reducing energy consumption.
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 system enhances cooling efficiency, reduces NOx emissions, and improves fuel consumption by selectively controlling coolant flow, ensuring effective engine cooling and emission control across different temperature conditions.
Implementation Method 1
a water-cooled intercooler connected to the low temperature coolant line and the high temperature coolant line
Implementation Method 2
a high temperature radiator communicating with an engine through a high temperature coolant line
Implementation Method 3
a low temperature radiator communicating with an exhaust gas recirculation (EGR) cooler for cooling EGR gas flowing into the engine through a low temperature coolant line
Implementation Method 4
a coolant temperature sensor detecting a temperature of a high temperature coolant flowing through the engine and the high temperature radiator
Data Source
AI summary
A coolant control system includes: a high temperature radiator communicating with an engine through a high temperature coolant line, a high temperature coolant pump, a coolant temperature sensor, a low temperature radiator, a low temperature coolant pump, a water-cooled intercooler, an intake air temperature sensor, bypass valves provided upstream and downstream of the water-cooled intercooler for selectively controlling the high temperature coolant or the low temperature coolant to flow through the water-cooled intercooler, an ambient temperature sensor, a radiator bypass line connected to the high temperature coolant line and bypassing the high temperature radiator, a thermostat to selectively flow the high temperature coolant to the radiator bypass line, and a controller for controlling the operations of the low temperature coolant pump, the bypass valve and the thermostat in accordance with a vehicle operation state.