Exhaust Sensor Boss for Representative Sampling
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Solution Overview
Problem
Existing exhaust gas sensors often fail to provide representative measurements due to non-uniform distributions of substances across the exhaust pipe diameter, especially in applications like urea/SCR systems and diesel engines with particulate filters, where substances like ammonia and soot are temperature-dependent, leading to incomplete detection and inefficient emissions control.
Innovation Solution
A closed-ended sensor boss structure that extends into the exhaust pipe with inlets and outlets positioned to passively redirect a representative cross-section of the fluid flow towards the sensor, allowing for improved sampling and reducing the need for vacuum pumps, while optionally providing passive cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sensor is mounted at the pipe wall where exhaust flow is accessible and cooler, then the sensor is protected from high temperatures and easier to access, but the sensor does not detect the bulk flow composition accurately due to non-uniform distribution of substances
Solution Approach 1:
A sampling probe structure is introduced as an intermediary element between the exhaust flow and the sensor. The probe extends into the exhaust pipe to capture bulk flow samples and redirect them to the sensor, allowing accurate representation of the entire cross-section without requiring the sensor to be positioned in the harsh center environment.
Solution Approach 2:
The solution transitions from a two-dimensional wall-mounted sensor position to a three-dimensional sampling approach. The sampling probe creates a virtual sampling plane across the exhaust pipe cross-section, effectively adding a spatial dimension to the sampling process and enabling comprehensive bulk flow representation.
2Measurement precision
If a sampling probe with multiple inlets and vacuum pump is used to extract bulk flow samples, then accurate bulk flow composition detection is achieved, but the system complexity, cost, and packaging requirements increase significantly
Solution Approach 1:
The invention extracts only the essential function of bulk flow sampling while removing unnecessary components. The sampling probe structure captures representative exhaust samples and redirects them to the sensor, eliminating the need for vacuum pumps, multiple complex inlets, and associated control systems while maintaining sampling accuracy.
Solution Approach 2:
The sampling probe is designed to operate passively using the natural exhaust flow pressure and velocity. The probe geometry itself directs the flow to the sensor without requiring external power sources or active pumping, making the system self-sufficient and reducing overall complexity.
3Reliability
If the sensor is positioned some distance away from the exhaust flow to protect from high temperatures, then the sensor is protected, but the sensor cannot detect the desired substance in the bulk flow accurately
Solution Approach 1:
The sampling probe acts as a mediator that bridges the gap between the hot exhaust flow and the temperature-sensitive sensor. It captures samples from the bulk flow and transports them to the sensor, allowing the sensor to remain physically separated from the harsh environment while still detecting bulk flow composition accurately.
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 enhances sensor performance by providing a more accurate representation of the bulk fluid composition, improving emissions control and fuel economy without the complexity and cost of additional sampling devices.
Implementation Method 1
the structure passively redirects substantially all fluid flowing from the at least one inlet to the at least one outlet toward the sensor
Implementation Method 2
The present invention may be used to provide passive cooling of the exhaust gas or other fluid prior to reaching an associated sensor
Data Source
AI summary
A system and method for improving sensor performance of an on-board vehicle sensor, such as an exhaust gas sensor, while sensing a predetermined substance in a fluid flowing through a pipe include a structure for extending into the pipe and having at least one inlet for receiving fluid flowing through the pipe and at least one outlet generally opposite the at least one inlet, wherein the structure redirects substantially all fluid flowing from the at least one inlet to the sensor to provide a representative sample of the fluid to the sensor before returning the fluid through the at least one outlet.