Flexible Printed Resistive Ink Fuel Level Sensors
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Automobile fuel gauges are notoriously inaccurate due to mechanical malfunctions associated with floating parts and the irregular shapes of fuel tanks, leading to delayed indication of fullness and incorrect empty tank readings.
Innovation Solution
The use of flexible, elongated substrates with printed resistive ink patterns that can be cut to customized lengths, allowing for accurate liquid level sensing in irregularly shaped fuel tanks and deep vessels, utilizing a lookup table for precise fuel volume measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a mechanical float apparatus is used to indicate fuel level, then the structure is simple and manufacturing cost is low, but the measurement accuracy is poor and mechanical malfunctions occur
Solution Approach 1:
The patent replaces the mechanical float-wiper-resistor system with a printed circuit board-based sensor that uses electrical resistance measurements. The PCB sensor includes conductive traces and resistive elements that eliminate moving parts, directly measuring fuel level through electrical properties rather than mechanical displacement.
Solution Approach 2:
The patent changes the measurement parameter from mechanical position to electrical resistance. By using resistive ink patterns on the PCB that vary in resistance based on fuel contact, the system achieves accurate measurement without mechanical components. The resistance value changes correlate directly with fuel level, providing precise indication.
2Reliability
If a float apparatus with connecting rod is used, then the device is simple to manufacture, but the float sticking causes inaccuracy and delayed indication
Solution Approach 1:
The patent eliminates the mechanical float and connecting rod assembly by using a rigid PCB structure with conductive traces. The sensor responds directly to fuel contact through electrical resistance changes, removing all moving parts that could stick or malfunction, thereby significantly improving reliability.
3Adaptability or versatility
If discrete probes of limited length are manufactured, then the manufacturing process is simple, but customization for different tank depths is difficult and time-consuming
Solution Approach 1:
The patent uses flexible PCB material that can be manufactured in long continuous rolls. These flexible substrates can be cut to any required length and conform to various tank shapes, providing both customization capability and manufacturing efficiency through roll-to-roll production processes.
Solution Approach 2:
The patent manufactures sensors in long roll form with all electrical connections and resistive patterns already established during the printing process. This preliminary preparation allows rapid cutting and deployment of custom-length sensors without requiring post-manufacturing assembly or joining operations.
4Measurement precision
If traditional fuel tank shapes are used to fit tight spaces, then the design flexibility is good, but the irregular shapes cause inaccuracies in fuel level indication
Solution Approach 1:
The flexible PCB sensor can be conformally mounted to the irregular inner surfaces of complexly-shaped fuel tanks. The flexible substrate adapts to any tank geometry, ensuring consistent contact with fuel across varying tank shapes and providing accurate measurements regardless of tank configuration.
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 provides accurate and flexible liquid level sensors that can be positioned anywhere in a fuel tank, offering high resolution measurements and reduced manufacturing costs, capable of measuring fuel levels with precision in varying tank shapes and depths.
Implementation Method 1
The variable resistor consists of a strip of resistive material... In accordance with Ohm's Law, the more resistance there is, the less current will flow
Data Source
AI summary
First and second elongated flexible insulated substrates have patterns of resistive liquid level sensor sections along the substrate lengths, each pattern comprising printable resistive ink of the same resistivity (ohms-squared), wherein the patterns can be simultaneously printed upon each substrate to save manufacturing costs. The substrates can be separated by an elongated spacer that couples longitudinal edges of the facing substrates together with an appropriate adhesive. Alternatively, the facing substrates can be folded along a central fold line to form a first longitudinal edge and adhesively joined along a second longitudinal edge opposite the first longitudinal edge. The flexibility of the substrates enables the low manufacturing cost liquid level sensors to be positioned in for example in a highly irregularly shaped vehicle fuel tank. Also, sections of varying lengths to be cut from the rolls on demand by users to form customized lengths of liquid level sensors for numerous applications.