Particulate matter concentration detection device

Abstract

The invention relates to a particulate matter concentration detection device. The device comprises an upper shell, a lower shell, an airflow channel, a laser emission device and a photoelectric conversion device. The device has the advantages that filtered clean air enters a sealed sheath flow channel through the two sides of a measuring channel, and the clean air is isolated from the measured airflow, so that the clean air is prevented from diffusing in a free space; a flow guide plate and a laminar flow sheet are arranged on a clearance area of the photoelectric conversion device of the lower shell, the clean air flows under the laminar flow sheet through the flow guide groove, the measured airflow flows above the laminar flow sheet through the flow guide plate, and the clean air forms alaminar flow (cleaning barrier) to wrap and blow the photoelectric conversion device, so that a probability that the particulate matters are deposited on the photoelectric conversion device is reduced, the technical problem that the particulate matter detection is misjudged due to the fact that the background noise caused by deposition of particulate matters in the measured airflow on the photoelectric conversion device is large is overcome, and the technical effects of improving the accuracy and stability of particulate matter concentration detection and prolonging the service life of the device are achieved.

Description

technical field [0001] The invention relates to the field of air quality detection, in particular to a particle concentration detection device. Background technique [0002] The particle concentration detection device is a device that uses the MIE scattering theory to measure the mass concentration of particles in the measured airflow. The particle concentration detection device usually includes an air flow channel for the air flow to be measured, a laser emitting device for generating laser light, and a photoelectric conversion device for sensing scattered light. The measured airflow flows in the airflow channel. When the particles in the measured airflow pass through the photosensitive area above the photoelectric conversion device, they are irradiated by laser light to generate scattered light. The photoelectric conversion device receives the scattered light and outputs an electrical signal. The output electrical signal obtains the particle concentration in the measured ...

AI Technical Summary

Problems solved by technology

However, the disclosed particle concentration detection device includes a flow meter, which has the technical defects of bulky device, complex structure, high cost, and unfavorable batch matching use.

[0005] In order to simplify the structure of the device and reduce the cost of the device, a particle concentration detection device is disclosed in the patent document WO2018100209A, which prevents the particles in the measured air flow from depositing on the photoelectric conversion device by setting three paths of clean air to wrap the measured air flow. One path of clean air includes two paths of clean air located on both sides of the measured airflow and parallel to the measured airflow, and one path of clean air perpendicular to the measured airflow. This device has a simple structure, low cost, and is convenient for batch use. A path of clean air perpendicular to the measured air flow, which is likely to impact the measured air flow in the air flow channel, affecting the accuracy and stability of particle detection

And because the sheath flow channel and the air flow channel are located at the same height, the clean air is easy to mix with the measured air flow, and the clean air does not have an obvious isolation effect on the measured air flow and the photoelectric conversion device, which still leads to dust deposition

Dust deposition will increase the background noise of particle detection, causing misjudgment of particle detection. Therefore, the particle concentration detection device in the prior art has low accuracy and poor stability of particle detection.

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