Cantilever Density Sensor for Fuel Cell Systems
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Solution Overview
Problem
Existing fuel cell systems face challenges in accurately measuring fuel solution density, particularly in the presence of impurities, and require cost-effective, fast, and temperature-independent density measurement solutions to optimize operation efficiency.
Innovation Solution
A density sensing device with a protective chamber and a cantilever density sensor, which includes a sensing plate and variable resistor, is used to measure fuel solution density independently of ambient temperature, and a heating member with an isothermal controller maintains constant temperature to prevent impurity collisions and ensure accurate measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a density measurement device is installed to measure fuel solution density, then operation efficiency can be improved through optimized fuel density control, but the device must satisfy multiple requirements (small size, accurate measurement, fast detection, low cost) which creates complexity in device selection and implementation
Solution Approach 1:
The patent replaces complex mechanical density measurement systems with a cantilever-based sensing mechanism that utilizes elastic deformation and vibrational properties. The density sensor employs a cantilever beam with a sensing plate that detects density changes through mechanical deflection and resonant frequency variations, eliminating the need for complex mechanical assemblies while achieving accurate, fast, and cost-effective measurement
Solution Approach 2:
The patent utilizes changes in physical parameters of the cantilever structure (deflection amount, resonant frequency, oscillation period) in response to density variations of the fuel solution. By measuring these parameter changes, the system achieves accurate density detection without requiring complex measurement devices, thereby improving operation efficiency while simplifying the overall system
2Measurement precision
If existing density sensors (polymer adsorptive, ultrasonic, resistance measurement types) are used, then density measurement can be achieved, but they do not sufficiently satisfy all requirements (small size, accurate measurement, fast detection, low cost) simultaneously
Solution Approach 1:
The patent divides the density sensing function into separate modular components: a cantilever beam structure, a sensing plate, a variable resistor for detection, and a protective chamber. This segmentation allows each component to be optimized independently for specific functions (mechanical sensing, electrical detection, protection), achieving high measurement precision while maintaining small size, fast response, and low cost
Solution Approach 2:
The patent employs a thin cantilever beam with a sensing plate that acts as a flexible mechanical element. The cantilever's thin structure allows it to respond rapidly to density changes in the fuel solution while maintaining small overall dimensions. The flexibility of the cantilever enables accurate detection of subtle density variations without requiring complex sensor assemblies
3Measurement precision
If solid impurities are present in the fuel solution, then density measurement errors occur, but adding protection mechanisms increases device complexity
Solution Approach 1:
The patent incorporates a protective chamber that encloses the cantilever density sensor before impurities can cause damage. This protective structure is designed in advance to filter or block solid impurities from reaching the sensing elements, preventing measurement errors and device damage without requiring complex active protection mechanisms or post-failure repairs
Solution Approach 2:
The protective chamber acts as an intermediary element between the fuel solution containing impurities and the delicate cantilever density sensor. This intermediate structure allows the fuel solution to be measured while preventing direct contact between impurities and the sensing elements, thereby maintaining measurement precision without significantly increasing device complexity
4Measurement precision
If temperature varies, then density measurement accuracy decreases, but adding temperature control mechanisms increases device complexity and cost
Solution Approach 1:
The patent replaces complex thermal control systems with a mechanical-vibrational sensing approach. The cantilever density sensor measures density through mechanical deflection and vibrational frequency changes that are inherently less sensitive to temperature variations. By utilizing the cantilever's natural resonant properties and mechanical response, the system achieves temperature-independent measurement without requiring heaters, coolers, or complex thermal compensation electronics
Solution Approach 2:
The patent measures density by detecting changes in the cantilever's mechanical parameters (deflection, resonant frequency, oscillation period) rather than relying on electrical or chemical parameters that are more temperature-sensitive. These mechanical parameters can be calibrated to compensate for temperature effects, enabling accurate density measurement across varying temperatures without additional control mechanisms
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, fast, and cost-effective density measurements, improving fuel cell system operation efficiency by maintaining constant temperature and protecting the sensor from impurities, thus enhancing measurement accuracy and system performance.
Implementation Method 1
The heating member heats the fuel solution in the sensing region
Implementation Method 2
a density sensor for measuring a density of a fuel solution of the fuel cell system
Implementation Method 3
a temperature sensor for measuring a temperature of the fuel solution in the sensing region
Implementation Method 4
an isothermal controller for controlling the heating member such that the temperature of the fuel solution in the sensing region is constant
Data Source
Figure 1~2
Figure 3A
Figure 3B
AI summary
Disclosed is a density sensing device of a fuel cell system and a fuel cell system having the density sensing device. The density sensing device includes a density sensor that includes a collision sensor and a variable resistor coupled to the collision sensor. The collision sensor is dipped into a fuel solution, and the collisions of molecules of the fuel solution are detected in the collision sensor. The resistance of the variable resistor varies depending on an amount of the collision detected by the collision sensor. The resistance further is converted to a density by the use of a table that includes a relationship between resistance and density. The density sensing device can further include a sensor driver. The sensor driver can be a piezoelectric member that is attached to the collision sensor. The collision sensor vibrates together with the piezoelectric member when a driving signal is applied to the piezoelectric member, which improves the accuracy of the measurement of the density.