Temperature Controlled EGR Venturi with Liquid Heat Exchange Chamber
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Solution Overview
Problem
Conventional venturis in EGR systems are prone to overheating and suffer from reduced reliability due to diesel combustion product buildup and sensitivity to temperature variations, affecting accurate mass flow measurement in turbocharged diesel engines.
Innovation Solution
A temperature-controlled EGR venturi design featuring an interior liquid heat exchange chamber surrounding the throat and sensor ports, integrated with the engine's coolant system to maintain a stable temperature, preventing combustion product buildup and ensuring accurate differential pressure measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional venturis are used in EGR systems, then the structure is simple and easy to manufacture, but the sensor overheats and reliability decreases due to exposure to hot exhaust gases
Solution Approach 1:
The venturi body is segmented into distinct functional zones: a hot exhaust gas flow path and a cooled sensor housing chamber. The sensor is physically isolated in a separate thermal environment through internal walls and cooling passages, allowing the measurement function to operate independently from the high-temperature exhaust flow.
Solution Approach 2:
A cooling fluid acts as an intermediary substance, circulating through passages in the sensor housing to absorb heat from the sensor area and transfer it away. This thermal mediator creates a temperature buffer between the hot exhaust gases and the sensitive sensor components.
2Measurement precision
If conventional venturis are used in EGR systems, then the design is simple, but combustion product buildup affects internal geometry and measurement accuracy
Solution Approach 1:
Different surface properties are applied to different areas of the venturi. The exhaust gas flow path features smooth, non-stick coatings to prevent soot adhesion, while the sensor housing interior maintains clean, temperature-controlled surfaces. This localized quality differentiation prevents buildup in critical measurement areas.
Solution Approach 2:
The cooling fluid circulation operates continuously or periodically to prevent combustion products from condensing and adhering to surfaces. By maintaining temperatures above dew point through periodic or continuous cooling cycles, the system prevents the formation of sticky combustion residue that would alter internal geometry.
3Measurement precision
If the sensor is remotely mounted or shielded to protect from heat, then the sensor is protected from overheating, but the measurement accuracy decreases due to temperature variations
Solution Approach 1:
Temperature sensors monitor the thermal conditions in the sensor housing and provide feedback to the cooling system control. This allows the cooling fluid flow rate to be adjusted dynamically to maintain a stable temperature environment, compensating for ambient temperature variations and ensuring consistent measurement conditions.
Solution Approach 2:
The cooling system is integrated into the sensor housing structure itself, allowing the sensor assembly to self-regulate its thermal environment. The housing acts as both a structural component and a heat exchanger, providing passive thermal management that stabilizes sensor operating conditions without external intervention.
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
The solution effectively prevents combustion product buildup and maintains sensor accuracy and reliability across varying ambient conditions, enhancing the precision and durability of EGR flow measurement.
Implementation Method 1
an interior liquid heat exchange chamber adjacent to the throat... The heat exchange chamber is in fluid communication with the liquid coolant system
Implementation Method 2
fluid may be circulated through cooling cover... a first flow path and a second flow path in order to communicate with a differential pressure sensor
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
An EGR venture (56) for use in an EGR system of an IC engine (10) includes a body (64) defining a converging inlet section (66), a throat (68), and an interior liquid heat exchange chamber (60) adjacent to the throat (68).