Combustion Engine Exhaust Backpressure Estimation from Upstream Pressure
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Solution Overview
Problem
Existing methods for determining exhaust backpressure downstream of an exhaust gas turbocharger in internal combustion engines are imprecise, making it difficult to effectively control the engine's operation.
Innovation Solution
Measure the pressure in a first section of the exhaust line upstream of the turbocharger and use the relationship between this pressure and the pressure in a second section downstream of the turbocharger, determined at specific operating points and crankshaft angles, to accurately derive the exhaust backpressure without the need for a sensor in the second section.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a pressure sensor is installed in the second section downstream of the exhaust turbocharger to directly measure exhaust backpressure, then the measurement precision is improved, but the device complexity and installation cost increase
Solution Approach 1:
The patent uses the exhaust manifold pressure (measured by an existing sensor upstream of the turbocharger) as an intermediary parameter to indirectly determine the exhaust backpressure downstream of the turbocharger. By establishing a correlation between upstream pressure and downstream backpressure through regression analysis, the system avoids direct installation of sensors in the difficult-to-access second section while achieving accurate backpressure measurement.
Solution Approach 2:
The patent creates a virtual copy of the exhaust backpressure signal by using regression analysis to establish a mathematical relationship between the easily measurable exhaust manifold pressure and the difficult-to-measure exhaust backpressure. This virtual sensor approach replicates the backpressure information without requiring physical sensor installation in the exhaust downstream section.
2Device complexity
If estimation methods are used to determine exhaust backpressure from upstream pressure measurements, then the device complexity is reduced, but the measurement precision deteriorates
Solution Approach 1:
The patent performs preliminary calibration during a test bench procedure where both upstream and downstream pressure sensors are temporarily installed. Regression analysis is executed in advance to establish the specific correlation between exhaust manifold pressure and exhaust backpressure for each engine configuration. This pre-established relationship is then used during normal operation to accurately determine backpressure without requiring downstream sensors.
Solution Approach 2:
The patent transforms the measurement approach by changing from direct physical measurement to indirect mathematical determination. By using regression analysis to establish a dynamic relationship between upstream pressure and downstream backpressure, the system converts an easily measurable parameter (exhaust manifold pressure) into an accurate indicator of the difficult-to-measure parameter (exhaust backpressure), achieving high precision without complex sensor installation.
Data Source
Figure 1~2
AI summary
The invention relates to a method for operating an internal combustion engine (1) with an exhaust gas line (2) which directs an exhaust gas (3) from the internal combustion engine (1) via an exhaust gas turbocharger (4), wherein a second pressure (7) in a second section (8) of the exhaust gas line (2) downstream of the exhaust gas turbocharger (4) is determined by measuring a first pressure (5) in a first section (6) of the exhaust gas line (2) downstream of the internal combustion engine (1) and upstream of the exhaust gas turbocharger (4); wherein this determination of the second pressure (7) is derived from the condition that at certain operating points (9) of the internal combustion engine (1) at certain crankshaft angle positions (10) the first pressure (5) corresponds to the second pressure (7).