Personal Air Sampler Closed Loop Flow Control
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Solution Overview
Problem
Existing personal air samplers face inefficiencies in maintaining a stable air flow rate under varying inlet pressures due to filter loading, which affects battery run time and device performance.
Innovation Solution
A battery-powered personal air sampler employing a closed loop control circuit with a coreless DC motor and a regulator sub-system, utilizing a proportional-integral-derivative control algorithm to adjust pump power and maintain a constant flow rate, optimized by a look-up table and PID control process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a conventional pump system is used without closed loop control, then the device complexity is reduced, but the air flow rate stability deteriorates under varying inlet pressures
Solution Approach 1:
The patent implements a closed-loop feedback control system where a pressure sensor continuously monitors the air flow rate and feeds this information back to a processor. The processor compares the measured flow rate with a target set point and adjusts the pump power accordingly to maintain stable air flow rate despite varying inlet pressures caused by filter loading.
Solution Approach 2:
The system dynamically adjusts the pump power in real-time based on changing operating conditions. The controller modifies the power delivered to the pump motor continuously to compensate for varying inlet pressures, transforming a static pump system into a dynamic adaptive system that maintains optimal performance.
2Stability of the object's composition
If pump power is increased to maintain air flow rate, then the air flow rate stability is improved, but the energy consumption increases
Solution Approach 1:
The feedback control system precisely modulates pump power only to the extent necessary to maintain the target air flow rate. Rather than operating at constant high power, the system adjusts power delivery dynamically, consuming more energy only when and where needed to compensate for pressure drops, thereby optimizing the balance between flow stability and energy consumption.
Solution Approach 2:
The system changes the operating parameters of the pump (power, speed) in response to measured conditions. By adjusting these parameters dynamically rather than maintaining fixed high-power operation, the system achieves flow rate stability while minimizing unnecessary energy consumption during periods when less compensation is required.
3Measurement precision
If a closed loop control system is implemented, then the air flow rate accuracy is improved, but the device complexity increases
Solution Approach 1:
The closed-loop feedback system continuously measures the actual air flow rate using a pressure sensor and compares it with the target set point. This feedback mechanism enables precise control by making real-time adjustments based on the difference between measured and desired values, significantly improving measurement precision and control accuracy.
Solution Approach 2:
The patent replaces complex mechanical flow control mechanisms with an electronic control system. Instead of using mechanical adjustments or complex valve systems to control air flow, the invention uses electronic sensors, processors, and motor control to achieve precise flow rate management, thereby improving accuracy while managing overall system complexity through electronic rather than mechanical means.
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
This solution enhances the efficiency of the electronic and pumping systems, optimizing battery run time and device size by maintaining a stable and accurate air flow rate independent of inlet pressure changes, demonstrating a 40% increase in run time at specific flow benchmarks compared to conventional systems.
Implementation Method 1
A coreless DC motor drives the pump and a battery provides a voltage to the DC coreless motor
Implementation Method 2
a pressure sensing sub-system generates a signal indicative of the air flow rate
Implementation Method 3
A regulator sub-system, having a switch and an inductor, is electrically coupled to and disposed between the battery and the coreless DC motor
Data Source
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AI summary
A battery powered, personal air sampler is described which uses a closed loop control circuit to adjust the power that is delivered to an internal pump such that a stable and accurate flow rate is maintained independent of changes in inlet pressure due to filter loading. Furthermore, the described personal air sampler provides improved efficiency to the entire electronic and flow pumping system which, in turn functions to optimize the available battery run time of the device.