CN219162049U

CN219162049U - Low-adsorption photoionization sensor

Info

Publication number: CN219162049U
Application number: CN202223608061.5U
Authority: CN
Inventors: 熊志红; 王艳波; 古盛少
Original assignee: Shenzhen Noan Intelligent Co ltd
Current assignee: Shenzhen Noan Intelligent Co ltd
Priority date: 2022-12-30
Filing date: 2022-12-30
Publication date: 2023-06-09
Anticipated expiration: 2032-12-30

Abstract

The utility model discloses a low-adsorption photoionization sensor, which comprises an air chamber, an electrode assembly, an ionic membrane, an ultraviolet light source, an air pump and a circuit board, wherein the air chamber is arranged on the air pump; the air chamber comprises an air inlet, an air outlet and an ionization chamber, and the ionization chamber is respectively communicated with the air inlet and the air outlet; the ion membrane is provided with an opening hole; the outer shell of the air chamber is fixed on the circuit board, the electrode assembly is positioned in the ionization chamber and fixed on the circuit board, the ultraviolet light source is positioned above the ionization chamber and connected with the outer shell of the air chamber, the ion membrane is arranged between the ultraviolet light source and the electrode assembly, and the air pump is communicated with the ionization chamber through the air inlet; the electrode assembly comprises a first electrode and a second electrode, the two electrodes are positioned on the same plane, a gap is formed between the two electrodes, and the opening hole is opposite to the gap between the two electrodes. This application has reduced the gaseous adsorptivity of volatile organic compound through improving electrode assembly's structure, has reduced the influence of condensation steam to the electrode when humidity and temperature change, improves the accuracy and the stability of sensor long-term work.

Description

Low-adsorption photoionization sensor

Technical Field

The utility model relates to the technical field of gas detectors, in particular to a low-adsorption photoionization sensor.

Background

The photoionization sensor is a gas detector that can detect the concentration level of volatile organic compounds. The principle of operation of a photoionization sensor is that ultraviolet light generated by an ultraviolet light source is adopted to ionize gas in an ionization chamber, an electric field is established between two electrodes by applying an externally applied bias voltage, generated ions are collected at the electrodes under the action of the electric field, so that a current is established between the electrodes, and the concentration of ionized gas is determined by amplifying, filtering and analyzing the current signal.

In long-term operation of the photoionization sensor, leakage current interference is easy to generate due to the change of humidity and temperature, so that detection current signals are influenced, and the accuracy of detection results is influenced.

Disclosure of Invention

In order to overcome the defects of the prior art, the utility model provides a low-adsorption photoionization sensor.

The technical scheme of the utility model is as follows: a low-adsorption photoionization sensor comprising a gas chamber, an electrode assembly, an ion membrane, an ultraviolet light source, an air pump and a circuit board; the air chamber comprises an air inlet, an air outlet and an ionization chamber, and the ionization chamber is respectively communicated with the air inlet and the air outlet; the ion membrane is provided with an opening hole, the ion membrane is used for blocking ultraviolet light, and the opening hole is used for allowing the ultraviolet light to pass through; the outer shell of the air chamber is fixedly connected to the circuit board, the electrode assembly is positioned in the ionization chamber and fixed on the circuit board, the ultraviolet light source is positioned above the ionization chamber and fixedly connected with the outer shell of the air chamber, the ion membrane is arranged between the ultraviolet light source and the electrode assembly, and the air pump is communicated with the ionization chamber through the air inlet; the electrode assembly comprises a first electrode and a second electrode, wherein the first electrode and the second electrode are positioned on the same plane and have a gap therebetween, and the opening hole is opposite to the gap between the first electrode and the second electrode.

Further, in an embodiment, the first electrode is provided with a U-shaped groove, the second electrode is provided with a strip-shaped protrusion, the strip-shaped protrusion of the second electrode extends into the U-shaped groove of the first electrode, the first electrode is V-shaped, and the second electrode is convex.

Further, in an embodiment, the open hole is two annular grooves parallel to each other.

Further, in an embodiment, a hole gap width of the open hole is smaller than a gap width between the first electrode and the second electrode.

Further, in an embodiment, the air inlet is aligned with an outer side of the first electrode.

Further, in an embodiment, the electrode assembly is solder-connected with the circuit board.

Further, in an embodiment, the ionic membrane is made of teflon.

Further, in an embodiment, the air pump is connected to the air chamber connection pipe.

Further, in an embodiment, an extension tube is connected to the air outlet, and the extension tube is used for discharging the gas recovered after ionization away from the circuit board.

Further, in an embodiment, a transimpedance amplifier circuit and a low pass filter circuit are disposed on the circuit board to output a voltage signal indicative of the gas concentration of the test gas.

According to the scheme, the electrode assembly structure of the photoionization sensor is improved, the first electrode and the second electrode in the electrode assembly are arranged on the same surface, the facing area of the electrodes is reduced, the adsorptivity of volatile organic compounds is reduced, the influence of humidity and temperature changes on the electrode assembly is reduced, and therefore the long-term accuracy and stability of detection are maintained.

Drawings

FIG. 1 is a schematic diagram of a low-adsorption photoionization sensor according to an embodiment of the present utility model;

FIG. 2 is a schematic diagram of an exploded structure of the low adsorption photoionization sensor of the embodiment of FIG. 1;

FIG. 3 is a top view of an electrode assembly of an embodiment low adsorption photoionization sensor;

fig. 4 is a top view of a separator of an embodiment low adsorption photoionization sensor.

In the figure, 100, air cells; 110. an ionization chamber; 120. an air inlet; 130. an air outlet; 200. an electrode assembly; 210. a first electrode; 220. a second electrode; 300. an ionic membrane; 310. an opening hole; 400. an ultraviolet light source; 500. an air pump; 600. a circuit board; 700. a connecting pipe; 800. and (5) extending the tube.

Detailed Description

The utility model is further described below with reference to the drawings and embodiments. It will be understood that when an element is referred to as being "fixed" to another element, it can be directly on the other element or one or more intervening elements may be present therebetween. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or one or more intervening elements may be present therebetween. The terms "vertical," "horizontal," "left," "right," "inner," "outer," and the like are used in this specification for purposes of illustration only. In the description of the present utility model, the terms "first", "second" are used for descriptive purposes only and are not to be construed as indicating relative importance or implicitly indicating the number of technical features indicated. Thus, unless otherwise indicated, features defining "first", "second" may include one or more such features either explicitly or implicitly; the meaning of "plurality" is two or more. The terms "comprises," "comprising," and any variations thereof, are intended to cover a non-exclusive inclusion, such that one or more other features, integers, steps, operations, elements, components, and/or groups thereof may be present or added.

Furthermore, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; either directly or indirectly through intermediaries, or in communication with each other. All technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this utility model belongs. The terminology used in the description of the utility model herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the utility model. The term "and/or" as used in this specification includes any and all combinations of one or more of the associated listed items.

In addition, the technical features mentioned in the different embodiments of the utility model described below can be combined with one another as long as they do not conflict with one another.

As shown in fig. 1-2, the present application provides a low-adsorption photoionization sensor including a gas cell 100, an electrode assembly 200, an ion membrane 300, an ultraviolet light source 400, an air pump 500, and a circuit board 600. The gas chamber 100 includes a gas inlet 120, a gas outlet 130, and an ionization chamber 110, the ionization chamber 110 being in communication with the gas inlet 120 and the gas outlet 130, respectively. The ion membrane 300 is provided with an opening 310, and the ion membrane 300 is made of teflon. Wherein the housing of the gas chamber 100 is fixedly connected to the circuit board 600, the electrode assembly 200 is positioned in the ionization chamber 110 and fixed to the circuit board 600, the ultraviolet light source 400 is positioned above the ionization chamber 110 and fixedly connected to the housing of the gas chamber 100, the ion membrane 300 is disposed between the ultraviolet light source 400 and the electrode assembly 200, and the air pump 500 is connected to the air inlet 120 through a connection pipe 700 so as to be communicated with the ionization chamber 110. The air pump 500 pumps the gas molecules in the environment into the ionization chamber 110 from the air inlet 120, pumps the gas particles after ionization detection in the ionization chamber 110 out of the ionization chamber 110 from the air outlet 130, the ultraviolet light source 400 can emit ultraviolet light to provide excitation energy for ionization of the gas to be detected, an externally applied bias voltage is applied to the electrode assembly 200, and an electric field is generated in the electrode assembly 200. The electrode assembly 200 includes a first electrode 210 and a second electrode 220, the first electrode 210 and the second electrode 220 being in the same plane with a gap therebetween, and the opening hole 310 facing the gap between the first electrode 210 and the second electrode 220. The first electrode 210 and the second electrode 220 are on the same plane, so that the facing area of the first electrode 210 and the second electrode 220 can be effectively reduced, the gas is liquefied and adsorbed on the electrode assembly 200 when the temperature and the humidity change, the interference of leakage current is reduced, and the influence of the humidity and the temperature change on the electrode assembly 200 is reduced, so that the long-term accuracy and the stability of detection are maintained. .

Referring to fig. 3, in this embodiment, a U-shaped groove is formed on the first electrode 210, a strip-shaped protrusion is formed on the second electrode 220, the strip-shaped protrusion of the second electrode 220 extends into the U-shaped groove of the first electrode 210, the structure of the first electrode 210 is in an axisymmetric V-shape, and the second electrode 220 is also in an axisymmetric convex shape. The widths of the gaps at the opposite sides of the first electrode 210 and the second electrode 220 are maintained to be uniform. The structural cooperation of the first electrode 210 and the second electrode 220 in this embodiment effectively prolongs the length of the opposite surfaces of the first electrode 210 and the second electrode 220, and ensures the accuracy of the sensor detection.

In this embodiment, the air inlet 120 is aligned with the outer side of the first electrode 210, so that the flow of ionized gas particles between the first electrode 210 and the second electrode 220 can be reduced as much as possible, and the influence of the air flow on the detection structure can be reduced, thereby ensuring the detection accuracy.

The aperture gap width of the open aperture 310 in this embodiment is generally smaller than the gap width between the first electrode 210 and the second electrode 220. Since the teflon material is a good material capable of blocking the irradiation of ultraviolet light, the ultraviolet light emitted from the ultraviolet light source 400 can only be emitted into the ionization chamber 110 from the opening 310, i.e., the ultraviolet light can only be emitted to the gap between the first electrode 210 and the second electrode 220, but can not be emitted to the first electrode 210 and the second electrode 220, so that the reduction of the damage of the ultraviolet light to the ionization chamber 110 is beneficial to prolonging the service time of the low-adsorption photoionization sensor.

The general working procedure of this embodiment is that an applied bias voltage is applied to the first electrode 210 and the second electrode 220, and an electric field is established between the first electrode 210 and the second electrode 220; the air pump 500 pumps the gas molecules in the environment into the ionization chamber 110 from the air inlet 120 through the connection pipe 700, the gas molecules in the ionization chamber 110 can absorb the energy of the ultraviolet light injected from the opening hole 310 to form ionized gas molecules, the ionized gas molecules establish current between the first electrode 210 and the second electrode 220 under the action of the electric field, the formed current can output corresponding voltage signals after being collected and processed by the circuit board 600, and the voltage signals can indicate the concentration of the gas (one or more target gases) to be detected in the ionization chamber 110, namely, the concentration of the gas to be detected in the environment is detected. After the ionization detection is finished, the gas molecules are restored to the original gas molecules again, and the gas molecules are pumped out of the ionization chamber 110 by the gas pump 500 from the gas outlet 130. The air pump 500 pumps out the gas molecules to the outside of the ionization chamber 110 to reduce ion adsorption on the electrode assembly 200, thereby ensuring the surface of the electrode assembly 200 to be clean.

Referring to fig. 4, in this embodiment, the open hole 310 is two annular grooves parallel to each other. The distance width between the two adjacent sides of the two annular grooves is not smaller than the width of the protruding strip on the second electrode 220, so that the second electrode 220 is not irradiated by ultraviolet light.

In one embodiment, the electrode assembly 200 is solder-connected with the circuit board 600. Namely, the first electrode 210 and the second electrode 220 are respectively welded on the circuit board 600, so that the stability and reliability of the electrode assembly 200 are ensured, and the first electrode 210 and the second electrode 220 can be cleaned regularly without being damaged, thereby being beneficial to the later maintenance of the sensor and ensuring the stability of the sensor.

In one embodiment, the air outlet 130 is connected with an extension tube 800, and the extension tube 800 is used for discharging the gas recovered after ionization away from the circuit board 600, so as to prevent the discharged gas from affecting the circuit board 600 and the air chamber 100.

In one embodiment, a transimpedance amplifier circuit and a low pass filter circuit are disposed on the circuit board 600, and the electrode assembly 200, the transimpedance amplifier circuit and the low pass filter circuit are sequentially connected in series, and the transimpedance amplifier circuit and the low pass filter circuit process the received current and finally output a voltage signal to indicate the gas concentration of the test gas.

It will be understood that modifications and variations will be apparent to those skilled in the art from the foregoing description, and it is intended that all such modifications and variations be included within the scope of the following claims.

While the utility model has been described above with reference to the accompanying drawings, it will be apparent that the implementation of the utility model is not limited by the above manner, and it is within the scope of the utility model to apply the inventive concept and technical solution to other situations as long as various improvements made by the inventive concept and technical solution are adopted, or without any improvement.

Claims

1. The low-adsorption photoionization sensor is characterized by comprising a gas chamber, an electrode assembly, an ionic membrane, an ultraviolet light source, an air pump and a circuit board;

the air chamber comprises an air inlet, an air outlet and an ionization chamber, and the ionization chamber is respectively communicated with the air inlet and the air outlet;

the ion membrane is provided with an opening hole, the ion membrane is used for blocking ultraviolet light, and the opening hole is used for allowing the ultraviolet light to pass through;

the outer shell of the air chamber is fixedly connected to the circuit board, the electrode assembly is positioned in the ionization chamber and fixed on the circuit board, the ultraviolet light source is positioned above the ionization chamber and fixedly connected with the outer shell of the air chamber, the ion membrane is arranged between the ultraviolet light source and the electrode assembly, and the air pump is communicated with the ionization chamber through the air inlet;

the electrode assembly comprises a first electrode and a second electrode, wherein the first electrode and the second electrode are positioned on the same plane and have a gap therebetween, and the opening hole is opposite to the gap between the first electrode and the second electrode.

2. The low adsorption photoionization sensor of claim 1, wherein the first electrode has a U-shaped groove, the second electrode has a rectangular protrusion, the rectangular protrusion of the second electrode extends into the U-shaped groove of the first electrode, the first electrode has a V-shape, and the second electrode has a convex shape.

3. The low adsorption photoionization sensor of claim 2, wherein the open aperture is two annular grooves parallel to each other.

4. The low adsorption photoionization sensor of claim 3, wherein the aperture gap width of the open aperture is less than the gap width between the first electrode and the second electrode.

5. The low adsorption photoionization sensor of claim 4, wherein the gas inlet is aligned with a side of the first electrode.

6. The low adsorption photoionization sensor of claim 1, wherein the electrode assembly is solder-connected to the circuit board.

7. The low adsorption photoionization sensor of claim 1, wherein the ionic membrane is teflon.

8. The low adsorption photoionization sensor of claim 1, wherein the air pump is connected to the air cell connection tube.

9. The low adsorption photoionization sensor of claim 8, wherein an extension tube is connected to the gas outlet, the extension tube being adapted to expel the ionized gas away from the circuit board.

10. The low adsorption photoionization sensor of claim 1, wherein a transimpedance amplifier circuit and a low pass filter circuit are disposed on the circuit board to output a voltage signal indicative of the gas concentration of the test gas.