Bistable Valve Oxygen Flow Control via Sawtooth Signal
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current emergency oxygen supply systems for aircraft face challenges in controlling oxygen flow efficiently, as they rely on complex and energy-intensive pulse-width modulation systems, which are costly and require high-switching durability valves.
Innovation Solution
A method using a bistable on/off valve with a closed-loop control system that adjusts oxygen flow based on cabin pressure, activating the valve until a maximum error in oxygen supply is reached and then closing until a minimum error is met, reducing energy consumption and maintaining accurate oxygen delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pulse-width modulation with frequent valve activation is used to control oxygen flow, then control accuracy is improved, but energy consumption increases and valve durability requirements increase
Solution Approach 1:
The patent applies periodic action by using a sawtooth wave signal to periodically activate the valve in a time-dependent manner. Instead of continuous high-frequency PWM activation, the valve is activated periodically with a duty cycle that corresponds to the ratio of activation time to total period time, thereby reducing overall energy consumption while maintaining adequate control accuracy through the periodic nature of the activation pattern.
Solution Approach 2:
The patent changes the control parameter from duty cycle modulation at high frequency to time-dependent activation based on a sawtooth wave pattern. By varying the activation time within each period based on the sawtooth wave's linear increase and abrupt reset, the system achieves flow control with lower energy consumption and reduced valve switching frequency while maintaining acceptable control precision.
2Measurement precision
If complex PWM control modules are used to achieve precise oxygen flow control, then control accuracy is improved, but device complexity increases
Solution Approach 1:
The patent extracts the complex PWM control module and replaces it with a simpler time-dependent control mechanism using a sawtooth wave signal. By removing the need for complex PID modules and high-frequency switching circuitry, the invention simplifies the control architecture while maintaining adequate flow control accuracy through the periodic activation pattern and adjustable duty cycle.
Solution Approach 2:
The patent uses a sawtooth wave signal as a simplified copy or approximation of complex PWM control. Instead of implementing full PID control with multiple modules, the system uses the linear increase and abrupt reset characteristic of a sawtooth wave to achieve similar flow regulation effects with significantly reduced complexity, making the control system more reliable and easier to implement.
3Measurement precision
If high switching frequency valves are used for precise control, then control accuracy is improved, but valve durability requirements increase and cost increases
Solution Approach 1:
The patent applies periodic action by using a sawtooth wave signal to periodically activate the valve in a time-dependent manner. Instead of continuous high-frequency PWM activation, the valve is activated periodically with a duty cycle that corresponds to the ratio of activation time to total period time, thereby reducing overall energy consumption and switching frequency, which extends valve durability and improves reliability.
4Device complexity
If on/off valves with simple control are used, then device complexity is reduced, but control accuracy deteriorates
Solution Approach 1:
The patent applies periodic action by using a sawtooth wave signal to periodically activate the valve in a time-dependent manner. Instead of continuous high-frequency PWM activation, the valve is activated periodically with a duty cycle that corresponds to the ratio of activation time to total period time, thereby reducing overall energy consumption and switching frequency, which extends valve durability and improves reliability.
Data Source
AI summary
The invention relates to a method for the control of the breathing gas supply, in particular of the oxygen supply, from a pressure-leading supply conduit (1) to one or more breathing masks (3) of an oxygen emergency supply device in an air vehicle, in particular in an aircraft, with which an on/off valve (2) is arranged between the supply conduit (1) and the one or the several breathing masks (3), with which valve the conduit connection can be blocked or released, with which a desired mass flow dependent on cabin pressure is set and the actual mass flow is detected, wherein in a first method step the valve (2) is activated in an opening manner until the error between the actual mass flow and the desired mass flow and which is summed over time exceeds a previously fixed maximal error value (4), whereupon the valve (2) in a second method step is activated in a closing manner until the error between the actual mass flow and the desired mass flow and which is summed over time exceeds of a previously fixed minimal error value (15), whereupon the cycle is repeated beginning with the first method step.