Piezoelectric Injector Pressure Control for Fuel Cells
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Solution Overview
Problem
Mechanical pressure regulators used in fuel cells suffer from decreased spring force over time, temperature sensitivity, and flow rate influence, leading to pressure set point deviations and leaks, requiring multiple stages for pressure reduction with low tolerance.
Innovation Solution
A fuel supply system utilizing a piezoelectric injector and pressure sensor to control pressure at the fuel cell inlet, eliminating the need for multiple mechanical regulators and improving accuracy and signal quality by controlling pressure pulses and flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical pressure regulators are used to control pressure at the fuel cell inlet, then pressure control is achieved, but the spring force decreases over time and is affected by temperature, leading to pressure set point deviations
Solution Approach 1:
The patent replaces the mechanical spring-based pressure regulator with a piezoelectric injector system. The piezoelectric injector uses electrical signals to control gas flow, eliminating the mechanical spring component that degrades over time. This substitution resolves the reliability issue by removing the parts subject to wear, temperature sensitivity, and aging effects.
Solution Approach 2:
The patent implements a feedback control system using a pressure sensor to monitor the actual pressure at the fuel cell inlet and compare it with the reference pressure. The controller adjusts the piezoelectric injector based on the pressure difference, ensuring stable pressure control despite variations in flow rate or temperature, thereby resolving the set point deviation problem.
2Reliability
If mechanical pressure regulators are used, then pressure control is provided, but leaks in the line cannot be avoided because spring forced pressure regulators do not close very tightly
Solution Approach 1:
The piezoelectric injector replaces the mechanical spring regulator, enabling much tighter closure. The piezoelectric mechanism can achieve near-complete shut-off by precisely controlling the opening of the gas passage, eliminating the leakage issues inherent in mechanical spring-based systems where friction and wear prevent tight sealing.
3Manufacturing precision
If several pressure steps are installed with mechanical spring forced pressure regulators to realize small tolerance at the target pressure, then pressure reduction is achieved, but device complexity increases
Solution Approach 1:
The feedback control system with pressure sensor and controller enables a single piezoelectric injector to achieve precise pressure control with small tolerance. The continuous monitoring and adjustment eliminate the need for multiple pressure reduction stages, simplifying the device while maintaining or improving pressure precision.
Solution Approach 2:
The piezoelectric injector performs multiple functions that previously required separate components: it provides both pressure reduction and precise pressure control in a single device. The ability to modulate flow precisely through electrical control allows one injector to replace what would have been multiple mechanical regulators.
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 system provides stable and accurate pressure control with reduced component count, avoiding temperature and flow rate influences, and enabling smaller pressure sensor full scale with tight tolerance, thus enhancing fuel cell system performance.
Implementation Method 1
a piezoelectric injector in fluid communication with the fuel spending line
Implementation Method 2
a pressure sensor connected to the fuel spending line and positioned between the fuel supply vessel and the fuel cell
Data Source
AI summary
A fuel supply system for a fuel cell is described. One embodiment of the fuel supply system includes a fuel supply vessel; a fuel spending line in fluid communication with the fuel supply vessel and the fuel cell; a piezoelectric injector in fluid communication with the fuel spending line; and a pressure sensor connected to the fuel spending line and positioned between the fuel supply vessel and the fuel cell. A method for controlling the pressure to a fuel cell is also described.