Auto Bleed Valve Circuit for Transient Bubble Filtering
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Solution Overview
Problem
Auto bleed valves experience transient bubbles that cause the air vent solenoid to activate rapidly, leading to shortened life and reduced reliability due to brief and unhelpful relay and valve actuations.
Innovation Solution
An automatic bleed valve system utilizing an LED and phototransistor to detect air in the plenum chamber, with a comparator and integrator circuit to provide a constant output voltage and delay solenoid actuation until a predetermined threshold is met, ensuring reliable gas detection and venting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the air vent solenoid is activated rapidly in response to transient bubbles, then air detection sensitivity is improved, but valve reliability deteriorates due to shortened life from frequent actuations
Solution Approach 1:
The integrator circuit performs preliminary integration of the sensor signal over a predetermined time period before triggering the solenoid actuator. This preliminary action filters out transient bubbles by requiring the air detection signal to persist for a specific duration, thereby preventing premature or spurious valve actuations while maintaining sensitivity to genuine air presence.
Solution Approach 2:
The integrator circuit acts as an intermediary between the sensor and the solenoid actuator. It processes the raw sensor signal by integrating it over time, transforming transient fluctuations into sustained signals that only trigger actuation when genuine air presence is confirmed, thus mediating between sensitive detection and reliable actuation.
2Speed
If the solenoid actuator is triggered by transient bubble detection, then air venting responsiveness is improved, but device lifespan deteriorates due to frequent operations
Solution Approach 1:
The system performs preliminary integration of the detection signal before triggering actuation. This ensures that only sustained air presence (not transient bubbles) initiates the venting action, maintaining responsiveness to genuine air conditions while preventing unnecessary operations that would reduce valve lifespan.
Solution Approach 2:
The integrator circuit provides feedback control by continuously monitoring the sensor signal and adjusting the actuation decision based on the integrated history of air detection. This feedback mechanism ensures that venting occurs only when warranted by sustained air presence, optimizing both responsiveness and durability.
3Measurement precision
If the relay and valve actuate briefly in response to transient bubbles, then detection accuracy is improved, but system reliability worsens due to unhelpful brief actuations
Solution Approach 1:
The integrator circuit performs preliminary time-based filtering of the detection signal before actuation. This preliminary action maintains detection accuracy by still responding to air presence but adds a time-discrimination function that prevents brief actuations from transient bubbles, thereby improving system reliability.
Solution Approach 2:
The system dynamically evaluates the detection signal over time through integration, adapting the actuation decision based on the duration and consistency of air presence. This dynamic approach maintains sensitivity to genuine air conditions while automatically filtering out transient false positives, balancing detection accuracy with system reliability.
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 effectively prevents spurious venting and enhances reliability by ensuring accurate detection of air presence and controlled solenoid actuation, reducing wear and tear and improving system reliability.
Implementation Method 1
an air detection system comprising an LED and a photoelectric diode, the LED configured to illuminate the photoelectric diode when air is detected in the plenum chamber
Data Source
AI summary
An auto bleed valve and method of bleeding a hydraulic system of an aircraft is accomplished by illuminating a plenum of a bleed valve using an LED oriented to illuminate a phototransistor when air is present in the plenum. A comparator circuit is used on an output of the phototransistor such that a predetermined voltage output corresponds to air detected in the plenum. An integrating circuit and a second comparator in series with the first comparator circuit is used to determine when a predetermined time period is met in which air is continuously detected in the plenum. Thereafter an air bleed solenoid can be used to vent the air upon a signal from the aircraft computer logic system.