Capacitive Fluid Quality Sensor With Integrated Temperature Measurement
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Solution Overview
Problem
Existing fluid quality sensors are limited to specific applications, often placed in supply or reservoir tanks, and lack versatility and adequate temperature measurement capabilities with rapid response times.
Innovation Solution
A sensor design featuring a first electrode with a fluid passageway and a second electrode that operates as a capacitor, supported by a mounting member with a thermally coupled temperature sensor, allowing for secure assembly and accurate fluid property and temperature determination in-line with fluid flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If capacitor-based measurement technique is used for fluid quality sensing, then measurement capability is provided, but the device is limited to very specific applications
Solution Approach 1:
The sensor device is designed with a universal structure that can be applied across multiple fluid handling applications. The capacitor-based measurement technique is integrated into a modular sensor assembly that can monitor various fluid properties (alcohol content, urea concentration) in different systems (fuel injection systems, catalytic converter arrangements), making the device adaptable to diverse applications while maintaining measurement precision
2Measurement precision
If sensor is placed in supply or reservoir tank, then fluid quality determination is possible, but placement is limited and integration flexibility is reduced
Solution Approach 1:
The sensor device is segmented into distinct functional components: capacitor elements for measurement, mounting members for secure attachment, and temperature sensor assemblies. This segmentation allows the sensor to be installed in various locations within fluid handling systems, not limited to supply or reservoir tanks, while maintaining measurement capability
3Measurement precision
If traditional temperature sensing is used, then temperature measurement is provided, but response time is insufficiently rapid
Solution Approach 1:
The temperature sensor is integrated with a thin-walled mounting member structure that facilitates rapid thermal response. The mounting member has sufficient thermal conductivity and minimal thermal mass to quickly transmit fluid temperature to the sensor element, achieving sufficiently rapid response time while maintaining accurate temperature measurement
4Measurement precision
If capacitor-based sensor design is used, then fluid quality measurement is achieved, but assembly and positioning precision is difficult to confirm
Solution Approach 1:
The assembly method includes preliminary positioning steps where the mounting member is temporarily secured to the capacitor elements before final installation. This preliminary action allows verification of correct positioning and secure attachment of the capacitor elements within the sensor housing, ensuring manufacturing precision before the sensor is integrated into the fluid handling system
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
Enables versatile fluid quality monitoring in various applications with improved temperature sensing and rapid response, facilitating integration into fluid handling systems and enhancing performance compared to previous designs.
Implementation Method 1
A first electrode has a fluid passageway extending through at least a portion of the first electrode. A second electrode cooperates with the first electrode to function as a capacitor.
Implementation Method 2
A temperature sensor is thermally coupled with the mounting member such that the temperature sensor obtains a temperature indication from fluid contacting a portion of the mounting member within the fluid passageway.
Data Source
AI summary
A fluid quality sensor includes a first electrode (24) that has a fluid passageway (22) that is adapted to be placed in line with at least one fluid conduit (30). A second electrode (40) is supported within the fluid passageway (22) and electrically isolated from the first electrode (24). The first electrode (24) and the second electrode (40) operate as a capacitor for making fluid quality determinations. A disclosed example includes a temperature sensor (50) thermally coupled with a mounting member (42) that supports the second electrode (40) within the first electrode 24. A disclosed example includes a multiple piece first electrode that allows for at least a portion of the second electrode (40) to be exposed and accessible near one end of at least one piece of the first electrode during a selected portion of an example assembly process.