Engine Air Heater Thermostat for EGR Freezing
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Solution Overview
Problem
In engines with exhaust-gas recirculation (EGR), sub-zero temperature air causes moisture in EGR gas to freeze, hindering the valve flap in the throttle body and reducing engine output due to motion obstruction and inefficient fuel-air mixture supply.
Innovation Solution
A temperature control device comprising an air heater that heats air using engine cooling water and a thermostat to regulate cooling water flow, preventing excessive heating and ensuring smooth engine operation by cutting off cooling water at set temperature ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If air is heated to prevent moisture freezing in EGR gas, then valve flap motion obstruction is prevented, but engine filling efficiency is reduced due to excessive heating
Solution Approach 1:
The system dynamically changes the heating parameter (cooling water flow rate through air heater) based on the temperature parameter of the air. When air temperature is below freezing point, heating is activated; when air temperature is above freezing point, heating is stopped. This parameter-based control prevents both freezing and excessive heating, resolving the contradiction between reliability and productivity.
Solution Approach 2:
The system uses temperature feedback from the air temperature sensor to control the heating process. The controller continuously monitors air temperature and adjusts the cooling water flow rate accordingly, creating a closed-loop control system that prevents both moisture freezing and excessive heating, thereby maintaining both valve flap reliability and engine filling efficiency.
2Reliability
If cooling water flow is increased to heat air, then valve flap obstruction is prevented, but unnecessary heating occurs that reduces engine efficiency
Solution Approach 1:
The system changes the cooling water flow rate parameter based on the detected air temperature. When air temperature indicates freezing risk, the cooling water flow rate is increased to provide heating; when air temperature is safe, the flow rate is reduced or stopped. This dynamic parameter adjustment prevents energy waste while ensuring reliable throttle body operation.
Solution Approach 2:
The system uses the engine's own cooling water to provide heating for the air heater, creating a self-service heating system. The cooling water that would otherwise be wasted is utilized to prevent moisture freezing, converting a potential loss into a useful function without requiring additional energy input, thus maintaining energy efficiency while ensuring reliable operation.
3Productivity
If air temperature is maintained low for engine efficiency, then filling efficiency is improved, but moisture freezing occurs that hinders valve flap rotation
Solution Approach 1:
The system selectively changes the temperature parameter of the air based on the detected air temperature. When air temperature approaches freezing point, heating is activated to prevent moisture freezing; when air temperature is safely above freezing, heating is stopped to maintain low temperature for optimal filling efficiency. This conditional parameter change resolves the contradiction between productivity and reliability.
Solution Approach 2:
The system applies preliminary heating action when freezing conditions are detected, preventing moisture freezing before it can hinder valve flap rotation. By detecting temperature trends and activating heating in advance, the system prevents the harmful freezing phenomenon while maintaining low temperature operation for efficiency during normal conditions.
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
Prevents valve flap obstruction and maintains engine efficiency by ensuring the air is heated just enough to prevent freezing, while avoiding unnecessary heating that could reduce filling efficiency.
Implementation Method 1
an air heater configured to heat air introduced into a throttle valve by a flow of engine cooling water
Implementation Method 2
a heating channel which is formed in an arc shape within the first end of the intake pipe so as to provide the flow of cooling water while enclosing a circumference of air introduced into the throttle body
Implementation Method 3
a valve apparatus configured to cut off the flow of the engine cooling water passing through the air heater at a set temperature range or more
Data Source
AI summary
A temperature control device for the engine may include an air heater configured to heat air introduced into a throttle valve by a flow of engine cooling water, and a valve apparatus configured to cut off the flow of the engine cooling water passing through the air heater at a set temperature range or more, without being supplied with a separate control signal.