Charge Air Cooler Warming via Compressor Recirculation
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Solution Overview
Problem
Existing engine systems face challenges in efficiently warming the charge air cooler (CAC) during cold start conditions, leading to condensation issues and reduced fuel economy due to the separation of coolant loops and the need for additional components like valves and fluid passages.
Innovation Solution
The method involves closing the wastegate and EGR valve while opening the compressor recirculation valve to transfer turbine energy to the intake air, warming the CAC and reducing condensation risks by delaying EGR introduction until the CAC is sufficiently warm, thereby improving fuel economy and reducing misfires.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the charge air cooler is connected to the engine coolant loop to warm it during cold starts, then the CAC can be warmed using engine heat, but the approach requires additional valve devices and fluid passages which increase system complexity and cost
Solution Approach 1:
The patent merges the CAC cooling circuit with the engine coolant loop by using the same coolant pump and thermostat for both the engine and CAC. This eliminates the need for separate valves and fluid passages that would be required in a dual-circuit system, thereby reducing component count and system complexity while still enabling effective CAC warming during cold starts through engine heat transfer.
Solution Approach 2:
The engine coolant system is designed to serve dual functions: cooling the engine and warming the charge air cooler during cold starts. The single coolant loop and pump are used universally for both purposes, eliminating the need for dedicated CAC heating components and reducing overall system complexity.
2Temperature
If the engine coolant loop is used to warm the CAC during cold starts, then the CAC can be warmed, but the engine must be warmed up first which slows down the CAC warming process
Solution Approach 1:
The thermostat is designed to open at a lower temperature threshold specifically for the CAC cooling circuit. This preliminary action allows the CAC to begin warming as soon as the coolant reaches the thermostat's opening temperature, rather than waiting for the entire engine to reach operating temperature. The thermostat proactively initiates CAC warming independently of full engine warm-up.
Solution Approach 2:
The system applies different temperature control strategies to different parts of the cooling system. The thermostat monitors and controls coolant flow based on local temperature conditions at the CAC inlet, allowing the CAC to warm independently at its required temperature threshold rather than waiting for global engine temperature to rise.
3Temperature
If additional valve devices are added to control coolant flow to the CAC, then the CAC temperature can be controlled, but the cost and complexity of the system increases
Solution Approach 1:
The engine coolant system is designed to serve dual functions: cooling the engine and warming the charge air cooler during cold starts. The single coolant loop and pump are used universally for both purposes, eliminating the need for dedicated CAC heating components and reducing overall system complexity.
Solution Approach 2:
The patent merges the CAC cooling circuit with the engine coolant loop by using the same coolant pump and thermostat for both the engine and CAC. This eliminates the need for separate valves and fluid passages that would be required in a dual-circuit system, thereby reducing component count and system complexity while still enabling effective CAC warming during cold starts through engine heat transfer.
4Use of energy by moving object
If the coolant pump is turned off to conserve energy, then energy is saved, but heat transfer to the ambient is limited
Solution Approach 1:
The coolant pump operates dynamically based on real-time thermal conditions. It activates when the thermostat detects that the CAC requires warming (when coolant temperature exceeds the thermostat opening threshold) and deactivates when the CAC reaches its target temperature or when the engine requires cooling. This dynamic operation optimizes energy consumption while ensuring heat transfer occurs only when thermally beneficial.
Solution Approach 2:
The thermostat provides feedback control for the coolant pump operation. When the coolant temperature rises above the thermostat's opening threshold, the thermostat opens and triggers pump activation to facilitate heat transfer to the CAC. When the temperature differential decreases or the CAC reaches target temperature, the thermostat closes and the pump deactivates, creating a feedback-based energy-efficient control system.
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 expedites CAC warming, reduces condensation-related issues, and enhances fuel economy by recovering exhaust heat and maintaining EGR benefits across a wider range of conditions without increasing throttle inlet pressure.
Implementation Method 1
transferring of turbine energy to the intake air may be used to warm the intake aircharge
Implementation Method 2
transferring of turbine energy to the intake air may be used to warm the intake aircharge
Implementation Method 3
The CAC may be coupled to a cooling circuit
Data Source
AI summary
Methods and systems are provided for reducing condensate accumulation at a charge air cooler (CAC) during cold ambient conditions. A wastegate may be held closed while a compressor recirculation valve is held open during an engine cold start so as to use compressor heating and increased compressor recirculation to expedite CAC heating. EGR delivery is delayed until the CAC is sufficiently warm to reduce the propensity for condensation.