Engine Cooling System Cylinder Head Temperature Control
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Solution Overview
Problem
Existing engine cooling systems struggle to promptly increase and precisely control the temperature of the cylinder head, especially when switching between lean and stoichiometric combustion modes, which can lead to abnormal combustion such as knocking due to excessive temperature fluctuations.
Innovation Solution
The cooling system employs a temperature regulator and flow rate regulator to control the engine coolant's flow rate and temperature, using an electric thermostat valve and an on/off-type flow rate regulator valve, respectively, to manage the coolant's flow through the radiator and bypass passages, allowing for precise temperature control of the cylinder head.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the engine coolant flow rate is increased to cool the cylinder head, then the temperature control precision is improved, but the time required to warm up the engine is extended
Solution Approach 1:
The patent applies dynamics by making the coolant flow rate adjustable rather than fixed. The flow rate regulator valve dynamically changes the coolant flow rate based on engine operating conditions, allowing the system to adapt between warm-up mode (low flow rate) and temperature control mode (high flow rate), thereby resolving the contradiction between warm-up time and temperature control precision.
Solution Approach 2:
The patent changes the flow rate parameter of engine coolant as a key control variable. By regulating the flow rate parameter through the flow rate regulator valve, the system can optimize heat transfer efficiency at different stages, achieving both rapid warm-up and precise temperature control without being constrained by a fixed flow rate.
2Measurement precision
If the coolant flow through the head passage is increased to control cylinder head temperature, then the temperature control precision is improved, but the fuel economy deteriorates due to increased energy loss
Solution Approach 1:
The system dynamically adjusts coolant flow rate based on real-time temperature feedback and engine operating conditions. During lean combustion, the flow rate is optimized to maintain efficient heat transfer with minimal energy loss, while during stoichiometric combustion, the flow rate is increased to prevent knocking, thereby resolving the contradiction between temperature control precision and energy efficiency.
Solution Approach 2:
The patent implements a feedback control mechanism where the temperature sensor monitors cylinder head temperature and the ECU adjusts the flow rate regulator valve accordingly. This closed-loop feedback system ensures that coolant flow is optimized to achieve precise temperature control while minimizing unnecessary energy loss through the cooling system.
3Use of energy by moving object
If the engine operates in lean combustion mode to improve fuel economy, then the fuel economy is improved, but the risk of abnormal combustion increases due to temperature fluctuations
Solution Approach 1:
The feedback control system continuously monitors cylinder head temperature and adjusts coolant flow rate in response to temperature variations during lean combustion. This feedback mechanism compensates for temperature fluctuations that could lead to knocking, thereby maintaining combustion stability and reliability while preserving the fuel economy benefits of lean combustion mode.
Solution Approach 2:
The system changes the coolant flow rate parameter dynamically in response to combustion mode transitions. During lean combustion, the flow rate is optimized to maintain stable combustion, and when transitioning to stoichiometric combustion, the flow rate is adjusted to prevent knocking, thereby ensuring combustion stability across different operating modes while maintaining fuel efficiency.
Data Source
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AI summary
The cooling system includes: a radiator passage 65 that runs through a radiator 70; a radiator-bypass passage 66 that bypasses the radiator 70; a first fluid temperature sensor SW4 that acquires a fluid temperature of an engine coolant flowing through a bore passage 63 for cooling a cylinder 11; a second fluid temperature sensor SW5 that acquires the fluid temperature of the engine coolant flowing through a head passage 64 for cooling a cylinder head 13; a thermostat valve 80 arranged in the radiator passage 65; a flow rate regulator valve 90 arranged in the radiator-bypass passage 66; and an ECU 100. While controlling actuation of the thermostat valve 80 on the basis of a detection result of the first fluid temperature sensor SW4, the ECU 100 controls actuation of the flow rate regulator valve 90 on the basis of a detection result of the second fluid temperature sensor SW5.