EGR Control System Using Compressor Speed Ratio Feedback
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Solution Overview
Problem
Existing exhaust gas recirculation systems in internal combustion engines face challenges in properly controlling EGR operation across various engine operational conditions, particularly in managing the pressure and flow rate of recirculated exhaust gases effectively.
Innovation Solution
A control system that utilizes a feedback signal, defined as the speed ratio of the second compressor to the first compressor, to adjust the control signal for the second compressor, ensuring efficient recirculation by comparing this ratio to a predefined reference signal, thereby optimizing the EGR flow rate and pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a second compressor is used to pressurize recirculated exhaust gas, then the EGR flow rate and pressure can be controlled, but the system complexity increases
Solution Approach 1:
The control system uses feedback from sensors monitoring engine operating conditions (intake manifold pressure, exhaust manifold pressure, engine speed, load) to continuously adjust the second compressor's operation. This feedback mechanism enables precise control of EGR flow rate and pressure while allowing the system to adapt to varying engine demands, resolving the contradiction between control capability and system complexity.
Solution Approach 2:
The system dynamically adjusts the second compressor's speed and operation based on real-time engine conditions through the control unit. The compressor can vary its output to match changing engine requirements for EGR flow, enabling flexible control across different operating points without requiring excessive system complexity for all possible conditions.
2Measurement precision
If the second compressor is controlled independently, then precise EGR control is achieved, but the control system complexity increases
Solution Approach 1:
The control unit performs multiple functions: it processes signals from various sensors (intake manifold pressure sensor, exhaust manifold pressure sensor, engine speed sensor, load sensor), calculates required EGR flow rates, and controls the second compressor's operation. This multi-functional approach achieves precise EGR control while minimizing the number of separate control components needed.
Solution Approach 2:
The control unit acts as an intermediary that integrates information from multiple sensors and coordinates the second compressor's operation. Rather than direct independent control of the compressor, the control unit mediates between sensor inputs and compressor output, achieving precise control through coordinated regulation based on multiple parameters.
3Object-generated harmful factors
If exhaust gas is recirculated to lower peak temperature, then NOx production is reduced, but the combustion efficiency may be affected
Solution Approach 1:
The system dynamically adjusts EGR flow rate parameters based on engine operating conditions. The control unit modifies the amount of exhaust gas recirculated to optimize the balance between NOx reduction and combustion efficiency. By changing EGR flow parameters in response to engine speed, load, and temperature conditions, the system achieves NOx control without significantly compromising combustion efficiency.
Solution Approach 2:
The EGR system operates dynamically, adjusting recirculation rates in real-time based on engine conditions. During high-load conditions, EGR flow is reduced to maintain combustion efficiency, while during lower-load conditions, EGR flow is increased to reduce NOx production. This dynamic adaptation allows the system to optimize the trade-off between NOx reduction and combustion efficiency across varying operating points.
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 allows for precise control of the EGR system, ensuring efficient recirculation of exhaust gases across varying engine conditions, reducing NOx production and improving engine performance by maintaining optimal combustion temperatures.
Implementation Method 1
combustion gas is pressurized by a first compressor and introduced into the engine
Implementation Method 2
the portion of the exhaust gas is pressurized by a controllable second compressor and introduced into the combustion gas
Implementation Method 3
The recirculated exhaust gas lowers the peak temperature produced during combustion
Data Source
Figure 1
Figure 2
AI summary
Invention relates to method of controlling the operating an internal combustion engine (1), in which method combustion gas is pressurized by a first compressor (18) and introduced into the engine; fuel is combusted in the engine making use of the pressurized combustion gas thus forming exhaust gas; exhaust gas is removed from the engine; a portion of the exhaust gas is recirculated by including the portion into the combustion gas prior to its introduction into the engine; the portion of the exhaust gas is pressurized by a controllable second compressor (30) and introduced into the combustion gas; further a first signal (S1) indicative to the rotational speed of the first compressor (14) is acquired; a second signal (S2) indicative to the rotational speed of the second compressor (30) is acquired; feedback signal (F) is acquired as a function of the first signal and the second signal; and the feedback signal is used in process of providing a control signal (C) used for controlling the operation of the second compressor.