Gas Sensor Head with Permeable Membrane for Mode Switching
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Solution Overview
Problem
Existing gas-measuring device sensor heads face challenges in easily and reliably switching between diffusion and pump operation modes, with inflow of atmospheric gas into the inner volume during pump operation often falsifying measurement results and requiring complex mechanical switching mechanisms.
Innovation Solution
A sensor head design featuring a gas-permeable membrane positioned in front of a membrane opening, creating a pressure difference to prevent atmospheric gas inflow during pump operation and allowing direct diffusion in diffusion mode, with a disk-shaped inner volume and annular duct for efficient gas flow and measurement, and additional protective structures to prevent wind interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a mechanical switching device is used to switch between pump and diffusion operation, then mode switching is possible, but the device becomes complex, requires maintenance, and is unreliable
Solution Approach 1:
The patent replaces mechanical switching devices with a pressure-based control system. A pump creates positive pressure in the inner volume to prevent atmospheric gas infiltration during pump operation, eliminating the need for mechanical switches, caps, or closure elements. This substitution reduces device complexity, removes moving parts that require maintenance, and improves reliability while maintaining the ability to switch between operational modes.
2Productivity
If the membrane opening is left open during pump operation, then gas can flow freely, but atmospheric gas infiltrates into the inner volume and falsifies measurement results
Solution Approach 1:
The patent applies pneumatic pressure control by using a pump to generate positive pressure in the inner volume during pump operation. This pressure differential (higher inside than outside) prevents atmospheric gas from infiltrating through the membrane opening, even though the opening remains physically open. This allows free gas flow for measurement while maintaining measurement accuracy by blocking unwanted atmospheric gas infiltration through pressure control rather than mechanical closure.
3Measurement precision
If the membrane is positioned in front of the sensor opening, then gas can reach the sensor, but atmospheric gas can also infiltrate into the inner volume during pump operation
Solution Approach 1:
The patent changes the pressure parameter within the inner volume to resolve the contradiction. By maintaining positive pressure inside the inner volume during pump operation, the system allows the membrane to remain in front of the sensor opening for proper gas access while simultaneously preventing atmospheric gas infiltration. The pressure parameter change enables both functions to coexist without compromise.
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
Enables simple, quick, and reliable switching between operation modes without mechanical parts, ensuring accurate and fast measurement responses with minimal maintenance, and effectively blocking atmospheric gas from affecting measurement results during pump operation.
Implementation Method 1
In diffusion mode, the gas mixture to be detected usually flows through water-impermeable, gas-permeable membranes to the sensors
Implementation Method 2
a gas-permeable membrane that is provided on the housing in order to be flowed through by gas flowing to the sensor device
Implementation Method 3
the gas-permeable membrane provided in front of the membrane opening creates a slight overpressure in the interior volume compared to the atmosphere surrounding the sensor head, preferably from 1 to 5 mbar above this atmospheric pressure, so that an Inflow or diffusion of gas of lower pressure from the atmosphere surrounding the housing of the sensor head is prevented by the membrane
Data Source
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AI summary
A sensor head (1) for a gas measuring device is shown and described, comprising a housing (5) enclosing an inner volume (3), a gas supply (7) provided in the housing (5) for supplying gas into the inner volume (3), a sensor device (11) provided on the housing (5) which is in gas communication with the inner volume (3) via a sensor opening (9) in the housing (5), and a gas-permeable membrane (17) provided on the housing (5) which is intended to be permeated by gas flowing to the sensor device (11).The object of the present invention, to provide a sensor head for a gas measuring device which enables controlled switching between pump and diffusion operation in the simplest and most reliable way possible, is achieved by providing a membrane opening (13) in the housing (5) which establishes a gas connection between the internal volume (3) and the atmosphere (15) surrounding the sensor head (1), and by arranging the gas-permeable membrane (17) in front of the membrane opening (13) in such a way that it completely covers the membrane opening (13).