Blow Filter Device Motor Speed Control via PWM
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Solution Overview
Problem
Existing blow filter devices for breathing masks and hoods are costly and require frequent recalibration due to the use of pressure sensors and manual adjustments for maintaining airflow volume, especially when filter resistance changes.
Innovation Solution
A blow filter device using an electronically commutated direct current motor controlled by pulse width modulation, with an electronic control system that automatically adjusts motor speed based on calibration curves for different filter resistances and operation modes, and includes a sensing and control system to detect the type of head part connected, allowing for automatic mode setting and recalibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pressure sensors are used to measure differential pressure and control blower speed, then airflow volume can be maintained constant, but device complexity and cost increase significantly
Solution Approach 1:
The patent replaces the mechanical pressure sensor measurement system with an electronic control system that uses motor current and speed measurements to infer and control airflow volume. The microcontroller monitors motor parameters and adjusts blower speed accordingly, eliminating the need for physical pressure sensors while maintaining airflow control functionality.
Solution Approach 2:
The patent introduces motor current and speed as intermediary parameters to indirectly measure and control airflow volume. Instead of directly measuring differential pressure with sensors, the system uses motor electrical parameters as mediators to infer filter resistance changes and adjust blower performance to maintain constant airflow.
2Reliability
If voltage and current correction is continuously applied to control motor output, then airflow volume can be maintained, but operational cost increases
Solution Approach 1:
The patent implements a feedback control system where the microcontroller continuously monitors motor current and speed, compares these measurements against desired operating parameters, and automatically adjusts voltage and current output accordingly. This closed-loop feedback mechanism maintains optimal airflow while minimizing energy consumption by only applying corrections when necessary.
Solution Approach 2:
The system dynamically adjusts motor operating parameters based on real-time conditions. The electronic control system modifies voltage and current output adaptively rather than applying continuous correction, allowing the blower to operate efficiently across varying filter resistance conditions while maintaining constant airflow volume.
3Manufacturing precision
If manual recalibration is performed for each filter used, then accurate airflow control is achieved, but ease of operation deteriorates
Solution Approach 1:
The patent enables the system to automatically adapt to different filters without requiring manual recalibration. The electronic control system monitors motor parameters and automatically adjusts operating conditions based on the specific filter's resistance characteristics, allowing the device to serve itself and eliminate the need for user intervention in the calibration process.
Solution Approach 2:
The system performs preliminary characterization of filter resistance by monitoring motor current and speed during initial operation. By pre-measuring and storing the electrical characteristics of connected filters, the system prepares the optimal control parameters in advance, eliminating the need for manual recalibration when filters are changed.
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 device provides a simple, cost-efficient solution that maintains optimal airflow volume automatically, reducing the need for manual recalibration and extending filter life by automatically adjusting to changes in filter resistance, and includes a display unit for signaling airflow volume limits.
Implementation Method 1
an electronically commutated direct current motor associated with the blower and controlled by the electronic control system using a pulse width modulation ratio as a control variable to generate a specific motor speed and a respective airflow volume
Implementation Method 2
controlled by the electronic control system using a pulse width modulation ratio as a control variable to generate a specific motor speed
Data Source
AI summary
A blow filter device for breathing masks and hoods, comprising a blower which is driven by a motor and at least one filter which is arranged upstream from the blower, in addition to an electronic control system for adjusting a predefined airflow volume. The invention is characterized in that the motor is an electronically commutated direct current motor (6) which is controlled with the aid of a pulse width modulation ratio as a control variable, wherein a calibrating curve is created and stored in the memory (14) of the electronic control system and is based on a plurality of different filter resistances and a respectively corresponding pulse-width modulation ratio (PWM) and the respective motor speed (n) for a specific volume of air. The direct current motor can be controlled in the hood mode according to the speed (n) measured in relation to the respective filter resistance after activation with the aid of the associated pulse-width modulation ratio read from the calibrating curve and can be controlled in the mask mode independently of the respective filter resistance with a respective specific constant pulse-width modulation ratio (PWM) for the associated mask type, wherein the electronic control system (5) is associated with an identifying means (19,20) which is used to recognize the associated head part and to adjust the operational mode concerned.