JP2016212024A - Fine particle detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fine particle detection device capable of detecting an accurate fine particle amount even in oblique arrangement while configured to determine the fine particle amount in air based upon an updraft due to heat generation and reflection of light.SOLUTION: There is obtained a fine particle detection device comprising: openings 2a, 2b provided at an upper and a lower part of a light-non-transmissive, hollow outer hull 1 and a flow passage 3 connecting the openings together; heating means 4 arranged at a lower part in the flow passage 3 and generating an upward current; detecting means 6 of detecting fine particles passing in the flow passage 3 with the upward current based upon reflection of light above the heating means 4, and outputting a pulse signal; and determining means 7 of determining the amount of fine particles included in air based upon the pulse signal, the determining means 7 being configured to correct a result of the determination on the amount of fine particles based upon a tilt angle of the outer hull 1, thereby detecting the amount of fine particles relatively accurately even under a use condition in which the device should be arranged in a tilted state.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fine particle detection device for measuring the amount of dust contained in air, which is used to determine the contamination state of fine air dust.

  In recent years, pollutants, allergic house dusts, and health problems related to dust, which is fine particles floating in the air, such as PM2.5, are socially expanding. In order to cope with such a problem, it is effective to use an air conditioner such as an air purifier that keeps clean air quality by collecting dust in the air.

  In addition, it is desirable for air purifiers, etc., to automatically operate according to the generation of dust from the viewpoint of energy saving and convenience, and those that perform automatic operation more optimally according to the amount of dust in the air are required. It has been.

  However, in order to accurately detect the amount of dust in the air, it is necessary to use a high-precision particle mass concentration measuring device, but it is very expensive and cannot be used in general home appliances. .

  Therefore, there is an increasing demand for a device that can detect the amount of dust in the air relatively accurately and inexpensively.

  2. Description of the Related Art Conventionally, a fine particle detection apparatus that detects the amount of dust in the air of this type is known based on scattered light reflected by dust of irradiated light (see, for example, Patent Document 1).

  Hereinafter, the particle detection apparatus will be described with reference to FIG.

  As shown in the figure, the conventional particle detecting apparatus has a hollow housing 100 having a light shielding property as an outer shell, and the housing 100 has an inlet 101 for taking in air at the lower end and an air outlet for discharging air at the upper end. An exhaust port 102 is opened, and a flow path 103 is linearly communicated therein.

  In addition, a heater 104 made of a resistance element that causes the introduced air to flow from the bottom to the top by heat generation is provided at the upper portion of the intake port 101, and a light emitting means 105 and a light receiving means 106 are provided at a substantially central portion of the flow path 103. It is prepared symmetrically.

  The position where the light irradiation direction of the light emitting means 105 intersects the center of the light receiving area of the light receiving means 106 is a measurement area R. Between the measurement area R and the heater 104, introduced air is measured in the measurement area R. An airflow guide plate 107 is provided for reducing the size to the same size as or slightly smaller than the size of R.

  Further, a first condenser lens 108 and a second condenser lens 109 for condensing light are disposed in the light irradiation direction of the light emitting means 105 and the light receiving direction of the light receiving means 106.

  Here, the light emitting means 105 is made of, for example, a semiconductor laser, and the light receiving means 106 measures (detects) scattered light caused by suspended particles from the measurement region R due to light irradiation of the light emitting means 105 and corresponds to the received scattered light. For example, a photodiode that outputs a pulse current is used.

  In such a configuration, when the heater 104 is heated by energization of the power source, an upward airflow is generated by the chimney effect of the housing 100, and indoor air is sucked from the lower intake port 101. The sucked air is squeezed so as to pass through the measurement region R by the airflow guide plate 107, passes through the measurement region R, and is exhausted into the room from the exhaust port 102.

  When an upward air flow is generated in the housing 100, scattered light is emitted from suspended particles existing in the air by light emitted from the light emitting means 105 in the measurement region R. When the scattered light is received by the light receiving means 106, the light receiving means 106 receives the scattered light. Output pulse current.

  The number of pulses of the output pulse current is counted, the corresponding pulse width is calculated, and the amount of dust existing in the corresponding air is detected by performing a determination process such as comparison with a previously obtained data table. It was a thing.

Japanese Patent No. 4555664

  In such a conventional fine particle detection device, as described above, based on the updraft generated in the flow path 103 in the housing 100 due to the temperature rise of the heater 104, the floating that rides on the updraft and passes through the measurement region R. A pulse current corresponding to the amount of received light obtained by the light receiving means 106 receiving the scattered light of the light emitted from the light emitting means 105 by the particles was obtained. Then, the number of pulses is counted from the obtained pulse current, the corresponding pulse width is calculated, etc., and a judgment process such as comparison with a data table obtained in advance is performed, so that dust present in the corresponding air is present. It was configured to detect the amount.

  Therefore, if there is a change in the arrangement or the like of the device at the time when the data table is created in advance, a difference in the detection result of the dust amount will occur even in a spatial condition where the same amount of fine particles are latent.

  In particular, when the housing 100 must be tilted, the flow path 103 is tilted, and the passing speed of the suspended particle measurement region R based on the rising air flow of the heater 104 is also changed. However, there was a problem that an accurate amount of dust could not be detected.

  SUMMARY OF THE INVENTION The present invention solves the above-described conventional problems, and an object of the present invention is to provide a particulate detection device that can detect a relatively accurate amount of dust even under use conditions in which the device must be tilted. And

  In order to achieve this object, the present invention includes an outer shell that does not transmit light inside and is hollow, an opening provided below and above the outer shell, and a flow path that connects the two openings. A heating means for generating an updraft disposed below in the flow path, and a detection means for detecting a particulate passing through the flow path by the updraft based on reflection of light and outputting a pulse signal Determination means for determining the amount of the fine particles based on a pulse signal output from the detection means, inclination storage means for storing the inclination angle of the outer body, determination results by the determination means, The present invention provides a fine particle detection device including a correction unit that corrects the amount of the fine particles according to an inclination angle, thereby achieving an intended purpose.

  According to the present invention, the determination result of the amount of fine particles can be corrected according to the inclination angle even when the outer body needs to be inclined, so the apparatus must be inclined. It is possible to obtain an effect that the amount of fine particles can be detected relatively accurately even under use conditions.

1 is a side view showing a schematic configuration of a particulate detection device according to a first embodiment of the present invention, partially cut away. A circuit diagram showing a schematic circuit structure of the particle detecting means The graph which shows the detail of the production | generation of the pulse signal output from the detection means of the apparatus Side view schematically showing a partial cut of the state of the upward air flow with respect to the tilt of the device The graph which showed an example of the determination result of the amount of fine particles with respect to the arrangement inclination angle of the same device Side view showing a schematic configuration of a conventional particle detector partially cut away

  The fine particle detection device according to the present invention includes an outer body that does not transmit light inside and is hollow, an opening provided below and above the outer body, a flow path that connects the two openings, and the flow path A heating means for generating an updraft disposed below, a detection means for detecting particulates passing through the flow path by the updraft based on light reflection, and outputting a pulse signal; and the detection means Based on the determination means for determining the amount of the fine particles based on the pulse signal output from the inclination storage means for storing the inclination angle of the outer body, the determination result by the determination means, and the inclination angle of the outer body Correction means for correcting the amount of the fine particles. This makes it possible to correct the determination result of the amount of fine particles to a value when there is no inclination according to the inclination angle even if it is necessary to arrange the outer body at an inclination. The amount of fine particles can be detected with relative accuracy even under unavoidable use conditions.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The fine particles defined in the present invention include pollen, house dust (dust), suspended particulate matter (SPM: particles of 10 μm or less), PM2.5 (particles of 2.5 μm or less suspended in the atmosphere). ) Etc. are included.

(Embodiment 1)
As shown in FIG. 1, openings 2 a and 2 b are respectively provided below and above a hollow outer body 1 that retains the overall shape of the apparatus so that air can enter and exit the outer body 1.

  Inside the outer shell 1, openings 2a and 2b are connected so that air can pass therethrough, and a flow path 3 is provided, and the lower part of the flow path 3 is schematically shown by an arrow line on the figure based on heat generation. A heating means 4 for generating an updraft is arranged.

  Above this heating means 4, a detection means 6 enclosed by a dotted line in FIG.

  The detection means 6 detects fine particles as dust that pass through the detection region 5 fixed in the flow path 3 while being included in the rising airflow, and outputs a pulse signal based on the reflection of light.

  Further, a determination means 7 for determining the amount of fine particles by reading the pulse signal output from the detection means 6 is provided. The determination means 7 is provided with an inclination storage means 7a and a correction means 7b according to the inclination angle at the time of attachment of the outer body 1 with respect to product mounting, and corrects the determination result of the amount of fine particles.

  Here, as long as the outer body 1 is a member that retains the overall shape of the device and does not transmit light inside, the constituent material is not specified. For example, the outer body 1 is molded from a resin material such as black-colored ABS.

  Here, there is no special requirement for the heating means 4 as long as it generates a certain amount of heat. For example, the heating means 4 uses a resistance element that generates heat (temperature rise) by consuming a certain amount of power when a constant voltage power supply is applied. It's okay.

  Here, the detection means 6 is a light emitting element 8 that irradiates light, a light receiving element 9 that receives light and outputs a current signal corresponding to the amount of light, and a particle detected from the current signal output from the light receiving element 9. The signal conversion means 10 converts and outputs a pulse signal corresponding to the quantity.

  The light emitting element 8 and the light receiving element 9 are disposed so as to face each other so that the center of the light irradiation direction and the center of the light receiving direction are not orthogonal so that the irradiated light is not directly received.

  As the light-emitting element 8, for example, a light-emitting LED or a semiconductor laser that emits light in one direction when a power source is applied is used.

  The light receiving element 9 uses, for example, a photodiode whose conduction current changes according to the amount of received light.

  In addition, the lenses 11a and 11b are arranged in the light irradiation direction of the light emitting element 8 and the light receiving direction of the light receiving element 9 to collect light so that the amount of light in the detection region 5 can be increased and finer fine particles can be detected. I have to.

  Since the lenses 11a and 11b increase the amount of light, they are not essential as long as the target detection specifications can be satisfied without being arranged.

  Here, the signal converting means 10 comprises an amplifying means 12, a comparing means 13 and a voltage converting means 14 as shown by the one-dot chain line in FIG.

  In the amplifying means 12, a current signal output as a result of receiving light received by the light receiving element 9 from light emitted from the light emitting element 8 and scattered by air fine particles schematically shown by the fine particles 15 in the figure is expressed as a voltage value. Amplify after conversion. As a result, a voltage signal having a size that is easy to handle can be obtained.

  The comparing unit 13 compares the voltage signal obtained by the amplifying unit 12 with a voltage threshold value that is a determination reference value, thereby converting the voltage signal into a pulsed rectangular waveform and outputting the voltage signal.

  The voltage conversion means 14 converts the voltage signal converted into a rectangular waveform into a voltage value suitable for reading by the determination means 7 and is a pulse that becomes a pulsed voltage signal output from the detection means 6. A signal is generated.

  The amplifying means 12, the comparing means 13, and the voltage converting means 14 which are constituent elements of the signal converting means 10 are operated by stabilized DC power supplied from the power supply means 16.

  Here, the amplifying unit 12 does not require a specific specification, and is configured by a circuit mainly including a general DC type operational amplifier (op-amp) for amplifying a minute voltage signal to a required voltage.

  Further, the comparison means 13 compares a voltage signal input without obtaining a specific specification with a voltage threshold value serving as a determination reference value, thereby converting the voltage signal into a pulse voltage signal and outputting the general comparator ( Comparator) is the main circuit.

  In addition, the voltage conversion means 14 converts the voltage value of the pulse signal into a value suitable for the input of the determination means 7, and is constituted by a switch circuit combining a simple transistor element and a resistance element, for example.

  Further, the power supply means 16 is not specified as long as it can supply stabilized DC power, and its configuration is not related to the gist of the present embodiment, so that detailed description thereof is omitted.

  Note that the comparison unit 13 and the voltage conversion unit 14 are not absolutely necessary.

  For example, the voltage conversion means 14 may be omitted if the pulsed voltage signal output from the comparison means 13 is within a voltage value suitable for the input of the determination means 7.

  Similarly, the comparison means 13 can be omitted if the amplified voltage signal output from the signal conversion means 12 is within a voltage value suitable for the input of the determination means 7.

  Here, the determination means 7 is configured using, for example, a one-chip microcomputer.

  This microcomputer has a central processing unit that performs calculation and determination processing, an input / output terminal, an A / D input terminal, a read-only memory, a random access memory, and the like. The input / output terminal captures and outputs an external voltage change signal, and the A / D input terminal captures the analog voltage signal by converting it into a digital value. The read-only memory stores the operation procedure as software. The random access memory temporarily stores calculation and determination states.

  In the determination means 7 constituted by such a microcomputer, the pulse signal output from the detection means 6 via the input terminal 17 provided is converted into a digital value change from a change in Hi potential, Lo potential, or analog voltage value. It is here to read inside.

  Note that the Hi potential is a voltage potential (for example, 5 V) of the driving power source defined by the specification of an electrical signal having an allowable voltage. The Lo potential is a reference potential (GND).

  In addition, a series of procedures for determining the amount of fine particles is stored in a read-only memory as a program written in software, and this procedure is synchronized with the specified timing to change the digital value of the electric signal read inside. The determination process required by executing the process accordingly is realized.

  Next, details of generation of the pulse signal output from the detection means 6 will be described using the graph shown in FIG.

  This figure is output from the light receiving means 9, converted by the amplifying means 12, and compared with the amplified voltage signal (Vs in the figure) by the comparing means 13, and the voltage converting means 14 converts the voltage into a pulse shape. An example of a change in a pulse signal (Sp in the figure) output as a voltage signal is shown.

  In the figure, the vertical axis represents each voltage value, and the horizontal axis represents time (T in the figure), indicating the state of change of each signal with time.

  Note that the pulse signal Sp in the figure is an output signal from the detection means 6, but the voltage state on the lower side of the signal is in a state where the fine particles 15 are detected.

  Here, an updraft is generated in the flow path 3 at a substantially constant speed based on the constant heat generation of the heating means 4.

  Fine particles contained in the air also pass through the detection region 5 at a constant speed in accordance with the size and weight of the rising airflow at a constant speed.

  Therefore, the current signal output from the light receiving means 9 has a longer duration as the particle diameter of the fine particles 15 increases.

  For this reason, the voltage signal Vs output from the amplifying unit 12 also has a shape in which the pulse width and voltage value increase as the particle diameter of the fine particles 15 to be detected increases, and change in an analog manner.

  The comparison means 13 compares the voltage signal Vs with the threshold voltage (Vr in the figure) indicated by the alternate long and short dash line in the figure, so that if the voltage signal Vs changes more than the threshold voltage Vr, the voltage signal Vs has a pulse shape. A voltage signal having a rectangular waveform is output.

  The voltage conversion means 14 changes the voltage signal output to perform only voltage conversion into the same shape (or inverted shape) as the rectangular waveform output from the comparison means 13, and this signal is converted into a pulse signal (in the figure). Sp) is output from the detection means 6.

  From the above, the pulse width (time) of the pulse signal Sp output from the detection means 6 increases in proportion to the particle diameter of the fine particles 15 that are to be detected that pass through the detection region 5 at a constant speed.

  Further, since the fine particles 15 to be detected pass through the detection region 5 at a constant speed, the amount of fine particles contained in the air increases as the number of pulse signals Sp obtained in a certain unit time increases. Indicates.

  Therefore, the time ratio is obtained from the total time width of all the pulse signals Sp per unit time, for example, the relationship with the mass concentration of fine particles in air obtained by simultaneous measurement with a high-precision fine particle mass concentration measuring instrument (correlation). ), The amount of fine particles contained in the air can be specified.

  In the determination means 7, the above relationship is stored on the microcomputer, and a series of processes for obtaining the time ratio in the unit time of the pulse signal Sp to be read is executed, so that it is included in the air based on the correlation. The amount of fine particles can be determined.

  Next, correction of the determination result of the fine particle amount with respect to the inclination angle of the outer body 1 will be described with reference to FIGS. 4 and 5.

  FIG. 4 shows a change in the state of the rising air flow in the flow path 3 with respect to the inclination of the apparatus. When the outer body 1 as the main configuration is viewed from the side, openings 2a and 2b are provided at the upper and lower ends, and the flow path 3 It is regarded as an upright hollow body connected by the above, and only the heating means 4 is arranged below and expressed in a simplified manner.

  Further, in the figure, the inclination increases from the left side to the right side.

  Here, the ascending force of the air based on the heat generated by the heating means 4 is always a force directed vertically upward.

  Therefore, in the state where there is no leftmost inclination in the figure, this ascending force (expressed by a thick arrow line pointing upwards in the figure) acts most strongly on the air in the flow path 3 and produces the fastest ascending airflow. Cause it to occur.

  As the inclination increases, the ascending force is divided into the inclination direction of the flow path 3 and the force that presses the inner surface of the outer shell body 1 in the vertical direction, so that the force acting directly on the inclination direction of the flow path 3 becomes smaller (see FIG. Above, represented by a dashed-dotted line and a dashed arrow line).

  Therefore, in principle, the ascending air current that is the air flow generated in the flow path 3 is also slowed in accordance with the inclination angle of the outer shell 1.

  However, in an actual structure, the velocity and distribution of the ascending airflow passing through the detection region 5 change due to the influence of the unevenness of the inner surface configuration of the flow path 3 and the bias of the air flow when inclined.

  Due to the influence of such various factors, the determination result of the amount of fine particles also changes when the inclination angle of the outer body 1 is changed under the condition that the amount of fine particles in the air is the same.

  An example of the determination result of the fine particle amount with respect to the inclination angle of the outer body 1 is shown in FIG.

  In the figure, the horizontal axis represents the inclination angle, the vertical axis represents the change rate of the mass concentration of the fine particle amount that is the determination result, and the inclination angle of the outer body 1 (expressed by d in the drawing) in the state where the amount of fine particles in the air is the same condition. ) (Represented by Rc on the figure) and measured several times and recorded (dots on the figure).

  In this example, as shown in the figure, as the angle increases from a state without inclination, the density ratio decreases almost linearly up to a certain angle range (represented by nd in the figure). .

  This is because, as described above, as the inclination angle increases, the force that contributes to the ascending current of the ascending force of the air based on the heat generated by the heating means 4 becomes smaller. This is because the variation in the determination result of the amount of the fine particles becomes larger when the value is superior.

  As described above, since the concentration ratio Rc can be considered to decrease linearly with respect to the change in inclination up to this angle nd, the reciprocal of the inclination ratio of this straight line is obtained in advance as the correction coefficient α, and the determination result of the amount of fine particles It can be seen that the amount of fine particles with no inclination can be determined by multiplying by.

  Therefore, if the correction coefficient α for the inclination angle when the outer body 1 is mounted on the device is obtained in advance, and correction is performed at the time of determination of the amount of fine particles using this correction coefficient α, the correct fine particles (with no inclination) The amount can be determined. In other words, the correct amount of fine particles can be determined by performing correction using the inclination angle of the outer shell 1. This correction method is routineized by the judging means 7 and the correction process is stored on the microcomputer.

  Specifically, a predetermined inclination angle is stored in the inclination storage means 7a, or a correction coefficient α based on this inclination angle is stored (in this embodiment, the description of the inclination angle is a correction coefficient α. Included). Then, the correcting unit 7b corrects the fine particle amount based on the inclination angle and the determined fine particle amount. Based on this correction, the actual amount of fine particles is determined.

  Then, after executing a series of processes for obtaining a time ratio in the unit time of the pulse signal Sp to be read, it is possible to continuously determine the amount of fine particles contained in the air irrespective of the mounting inclination of the outer body 1 by adding correction. Thus, accurate detection of the amount of fine particles can be realized.

  Actually, the relationship between the inclination angle of the outer shell 1 and the concentration ratio Rc may not change linearly due to the influence of the inner surface structure of the flow path 3 of the apparatus.

  However, it goes without saying that correction can be made by obtaining in advance the correction coefficient α at one point of the inclination angle in the state of being arranged in the apparatus.

  It should be noted that the flow rate of the ascending air flow based on the heat generated by the heating means 4 is hardly affected by the amount of fine particles contained in the air. Therefore, if there is no change in the structure of the flow path 3 of the apparatus, the relationship between the inclination angle of the outer body 1 and the concentration ratio Rc does not change greatly, and therefore, the difference in the amount of fine particles does not normally need to be considered for correction.

  However, if the relationship between the inclination angle and the concentration ratio Rc is influenced by the amount of fine particles contained in the air in actual measurement, the concentration ratio Rc with respect to the determination value before correction of the fine particle amount for the fine particles contained in the air is displayed. And store it as a database.

  If the determination result of the amount of fine particles is corrected using the data-made concentration ratio Rc, the correct amount of fine particles can be detected.

  According to such a fine particle detection apparatus, the outer shell 1 that does not transmit light inside and is hollow, the openings 2a and 2b provided below and above the outer shell, and the two openings 2a and 2b are connected. A flow path 3; heating means 4 for generating an updraft disposed in the flow path 3; and fine particles passing through the flow path 3 by the updraft based on reflection of light. Detection means 6 for outputting a pulse signal; determination means 7 for determining the amount of fine particles based on the pulse signal output from the detection means 6; inclination storage means 7a for storing the inclination angle of the outer body; And a correction means 7b for correcting the amount of the fine particles according to the determination result (fine particle amount determination) by the determination means 7 and the inclination angle of the outer body.

  As a result, the determination result of the amount of fine particles can be corrected in accordance with the arrangement inclination angle of the device, so that the amount of fine particles can be set relatively accurately even under use conditions in which the device must be inclined and arranged. Can be detected.

  In the present embodiment, the detection means 6 and the determination means 7 are described as being separated from each other. However, the detection means 6 and the determination means 7 may be integrated in the configuration of the apparatus, and the effects differ. There is no.

  Further, the determination means 7 may be made unnecessary on the assumption that the determination means 7 is executed on a product control apparatus (mainly composed of a microcomputer) equipped with the determination and correction processing of the amount of fine particles. There is no difference in effect.

  When the inclination angle of the outer body 1 is determined in advance, the inclination angle (including the correction coefficient α based on the inclination angle) may be stored in advance. However, in the case where the inclination angle changes depending on the installation state, an inclination detection means for detecting the inclination angle and storing it in the inclination storage means 7a or further calculating the correction coefficient α may be provided.

  As a result, an accurate amount of fine particles can be obtained even when the tilt angle is not constant.

  The fine particle detection device according to the present invention detects the amount of fine particles composed of fine particles present in the air based on the intensity of reflected light due to scattering of irradiation light, and the angle of the device is necessary even if the device is inclined. Therefore, it is useful as a particle detector that can detect the amount of particles more accurately under various arrangement conditions. is there.

DESCRIPTION OF SYMBOLS 1 Outer body 2a, 2b Opening 3 Flow path 4 Heating means 6 Detection means 7 Determination means 7a Inclination memory | storage means 7b Correction means

Claims (2)

An outer shell that does not transmit light inside and is hollow;
Openings provided below and above the outer body;
A flow path connecting the two openings;
A heating means for generating an upward air flow disposed below in the flow path;
Detection means for detecting fine particles passing through the flow path by the updraft based on reflection of light and outputting a pulse signal;
Determination means for determining the amount of the fine particles based on a pulse signal output from the detection means;
An inclination storage means for storing an inclination angle of the outer body;
A fine particle detection apparatus comprising: a correction unit that corrects the amount of the fine particles based on a determination result by the determination unit and an inclination angle of the outer body. Inclination detection means for detecting the inclination angle of the outer body and storing it in the inclination storage means,
2. The particle detecting apparatus according to claim 1, wherein the correcting unit corrects the amount of the particle based on a determination result by the determining unit and an inclination angle of the outer body detected by the inclination detecting unit.

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