Gas Sensor Protector Nested Structure for Exhaust Responsiveness
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Solution Overview
Problem
Existing gas sensors face challenges in efficiently introducing and discharging gases, leading to reduced responsiveness and increased costs due to the need for multiple sensors to monitor inter-cylinder differences in exhaust gas pressure, which affects their ability to quickly respond to exhaust gases from each cylinder.
Innovation Solution
A gas sensor design with a protector system that includes an inner and outer protector with specific hole configurations and overlapping structures to enhance gas introduction and discharge performance, ensuring efficient gas flow to the detection element while protecting it from water adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single gas sensor is provided on an exhaust gas assembly to monitor air/fuel ratio in multiple cylinders, then cost is reduced, but the sensor cannot quickly respond to exhaust gases from each cylinder due to the need to monitor inter-cylinder differences in exhaust gas pressure
Solution Approach 1:
The gas flow passage is divided into multiple independent paths: a first gas flow passage extending from the first gas introduction hole to the detection element, and a second gas flow passage extending from the second gas introduction hole to the detection element. This segmentation allows exhaust gas from different cylinders to reach the detection element through separate routes, enabling the sensor to monitor inter-cylinder differences in exhaust gas pressure while maintaining quick response capability.
2Reliability
If water droplets are allowed to reach the detection element in exhaust gas, then gas flow is maintained, but the detection element suffers damage such as cracking due to thermal shock
Solution Approach 1:
A protector is provided that covers the detection element, with a first gas introduction hole in the first protector and a second gas introduction hole in the second protector. The gas flow passages are arranged so that exhaust gas flows through the protector from the first gas introduction hole, around the detection element, and out through the second gas introduction hole. This nested structure protects the detection element from direct exposure to water droplets while maintaining gas flow for detection.
3Productivity
If multiple gas sensors are provided on respective cylinders to monitor inter-cylinder differences in exhaust gas pressure, then responsiveness is improved, but cost increases
Solution Approach 1:
The gas sensor is designed with a universal structure that can monitor exhaust gas from multiple cylinders simultaneously. The first and second gas introduction holes are positioned to receive exhaust gas from different cylinders, and both gas flow passages converge at the detection element. This multi-functional design allows a single sensor to perform the monitoring function that would otherwise require multiple sensors, reducing cost while maintaining responsiveness.
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 improved gas sensor design enhances responsiveness by optimizing gas flow and discharge rates, reducing the need for multiple sensors and protecting the detection element from water damage, thus meeting stringent exhaust gas emission regulations.
Implementation Method 1
a detection element which generates an electromotive force having a magnitude which changes in accordance with the concentration of a particular gas, such as NOx (nitrogen oxides) or oxygen, contained in the exhaust gas
Implementation Method 2
a detection element whose resistance changes in accordance with the concentration of the particular gas
Implementation Method 3
if a water droplet contained in the exhaust gas adheres to the detection element when heated to a high temperature, the detection element may suffer damage, such as cracking, due to thermal shock
Data Source
AI summary
In a gas sensor (100), a base end portion (175b) of a second outer wall (175) of an outer protector (171) is connected airtightly to a forward end portion (164c) of a first inner wall (164) of an inner protector (161), and relations of A≦B<C<D and (0.6×B)≦A are satisfied, wherein A represents the total opening area of a second outer hole (176) of the outer protector (171), B represents the total opening area of a second inner hole (166) of the inner protector (161), C represents the total opening area of a first inner hole (167), and D represents the total opening area of a first outer hole.