Charge Air Temperature Control via Switchable Coolant Loops
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Solution Overview
Problem
Existing systems for controlling intake air temperature in internal combustion engines face challenges in achieving efficient combustion characteristics and emission control, particularly due to the limitations of high pressure exhaust gas recirculation, which compromises turbocharger performance and introduces soot, and low pressure recirculation, which requires higher recirculation amounts and poor mixture ratios.
Innovation Solution
A system utilizing a water-to-charge air heat exchanger with switchable piping and control of different temperature coolant volume flows, allowing for independent heating or cooling of intake air, thereby optimizing intake air temperature without relying on high pressure exhaust gas recirculation, and ensuring efficient combustion conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If high pressure exhaust gas recirculation is used to raise intake air temperature, then combustion efficiency is improved, but turbocharger performance deteriorates and soot introduction increases
Solution Approach 1:
The system segments the exhaust gas recirculation into two distinct pressure stages: high pressure EGR (HP-EGR) and low pressure EGR (LP-EGR). The HP-EGR handles temperature control while the LP-EGR manages quantity control, separating the conflicting functions to avoid compromising turbocharger performance while still achieving the required intake air temperature elevation.
Solution Approach 2:
A coolant circuit acts as an intermediary thermal management system between the exhaust gas recirculation and the intake air. The coolant absorbs or releases heat to the intake air in a heat exchanger, providing temperature control without directly mixing hot exhaust gas with the intake charge, thereby avoiding soot introduction and turbocharger performance loss.
2Reliability
If low pressure exhaust gas recirculation is used to raise intake air temperature, then turbocharger performance is maintained, but higher recirculation amounts are required and mixture quality deteriorates
Solution Approach 1:
The system divides the EGR function into two segmented stages with distinct roles: HP-EGR for thermal energy transfer and LP-EGR for mass flow control. This segmentation allows the LP-EGR to operate at lower pressures that preserve turbocharger performance while the HP-EGR provides the necessary thermal input, achieving both goals simultaneously.
Solution Approach 2:
The system changes the thermal parameters of the recirculated exhaust gas by passing it through a coolant heat exchanger. The exhaust gas temperature is adjusted to optimal levels before re-introduction, improving combustion efficiency without requiring excessive recirculation amounts that would degrade mixture quality.
3Temperature
If exhaust gas recirculation amount is increased to achieve higher intake air temperature, then temperature control is improved, but mixture quality deteriorates
Solution Approach 1:
The coolant heat exchanger serves as an intermediary that transfers thermal energy between the exhaust gas and the intake air without requiring direct mixing. This allows precise temperature control of the intake charge while maintaining optimal air-fuel mixture ratios, avoiding the deterioration that occurs with excessive exhaust gas recirculation.
Solution Approach 2:
The system independently controls the temperature parameter of the intake air through coolant temperature adjustment in the heat exchanger. This decouples temperature control from mixture composition control, allowing optimal intake air temperature to be achieved without compromising mixture quality.
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 solution provides efficient combustion characteristics, reduces emissions, avoids turbocharger performance loss, and simplifies the exhaust gas recirculation system, leading to lower costs and higher reliability by maintaining optimal intake air temperature through rapid temperature adjustments and minimizing soot introduction.
Implementation Method 1
a water-to-charge air heat exchanger (1) which cools down or heats up the charge air (Tg1)
Implementation Method 2
exchanging heat between coolant and charge air
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A system for controlling an intake temperature (Tg2) of a charge air, which is fed into an internal combustion engine (2) of a vehicle, wherein the system comprises: a water-to-charge air heat exchanger (1), which is switchable connected to a high temperature coolant loop (3) and/or to a low temperature coolant loop (4) to exchange heat; and control device (5); wherein the control device (5) selects a target temperature for the intake temperature of the charge air that is fed into the internal combustion engine (2) according to a detected at least one environmental or powertrain parameter; and wherein the coolant loops (3, 4) are switched to be connected or disconnected with the water-to-charge air heat exchanger (1) such that the intake temperature (Tg2) of charge air is heated up or cooled down to the selected target temperature.