Hybrid Vehicle Intake Condensation Control via EGR Heat Exchanger
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Solution Overview
Problem
In hybrid vehicles equipped with an EGR device, condensed water can form in the intake passage when the engine is stopped, potentially leading to ignition issues and misfires due to cooling by traveling wind, which existing technologies have not effectively addressed.
Innovation Solution
A hybrid vehicle configuration that includes a water-cooled heat exchanger and a control device to manage coolant supply, ensuring the coolant temperature is higher than the gas temperature in the intake passage, thereby preventing condensation by regulating coolant flow based on temperature differences and vehicle speed, and switching between coolant circuits to optimize heat exchange.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the engine is stopped during vehicle travel to improve fuel efficiency, then fuel consumption is reduced, but condensed water is generated in the intake passage due to cooling by traveling wind
Solution Approach 1:
The system applies preliminary anti-action by detecting conditions that would lead to condensed water formation (engine stoppage during travel with moisture in intake passage) and counteracting this harmful effect before it occurs. The control device activates the water-cooled heat exchanger to heat the intake passage, preventing condensed water formation in advance while maintaining the engine stoppage for fuel efficiency.
Solution Approach 2:
The system changes the temperature parameter of the intake passage by utilizing the water-cooled heat exchanger to transfer thermal energy from the coolant to the intake passage. This parameter change (increasing temperature) prevents the phase change of moisture from liquid to condensed water, resolving the contradiction between fuel efficiency and condensed water prevention.
2Temperature
If the water-cooled heat exchanger is supplied with coolant at normal operating conditions, then the gas in the intake passage is cooled for efficient combustion, but condensed water is generated when the engine is stopped due to excessive cooling
Solution Approach 1:
The system applies dynamics by making the coolant supply to the water-cooled heat exchanger conditional and variable rather than constant. The control device dynamically adjusts the coolant flow based on engine operation state (running vs. stopped), vehicle speed, and temperature differential, allowing the gas temperature to be cooled during operation but prevented from excessive cooling during stoppage, thus preventing condensed water formation.
Solution Approach 2:
The system implements feedback control by continuously monitoring the temperature difference between coolant and intake passage gas, vehicle speed, and engine operation state. The control device uses this feedback information to adjust coolant supply to the heat exchanger, ensuring optimal temperature control that prevents condensed water while maintaining combustion 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
Effectively suppresses the generation of condensed water in the intake passage during engine stoppage, preventing ignition issues and improving fuel efficiency by maintaining optimal gas temperatures and reducing energy waste.
Implementation Method 1
a water-cooled heat exchanger to perform heat exchange with gas flowing in an intake passage on a downstream side of an EGR gas-introduction portion
Implementation Method 2
heat exchange is performed between gas and coolant having a temperature higher than the temperature of the gas in the water-cooled heat exchanger
Implementation Method 3
the intake passage is cooled by traveling wind
Implementation Method 4
the moisture contained in the gas mixture may be condensed and condensed water may be generated
Data Source
Figure 1
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Figure 4~5
AI summary
An engine includes an EGR device and a water-cooled heat exchanger. The water-cooled heat exchanger is provided on a downstream side of an EGR gas-introduction portion of an intake passage into which EGR gas is to be introduced and exchanges heat with gas flowing in the intake passage. A control device is programmed to execute condensed water-suppression control that supplies coolant having a temperature higher than the temperature of the gas heat-exchanged in the water-cooled heat exchanger to the water-cooled heat exchanger while a hybrid vehicle is traveling in a state in which the engine is stopped.