Calibration device for particle number measurement device, calibration program, method for determining particle diameter for calibration, and calibration method for particle number measurement device

Abstract

The invention provides a correction device for a particle number measurement device, a correction program, a method for determining a particle size for correction, and a correction method for a particle number measurement device, which can reduce the influence of particle size change after classification and perform more accurate correction. A correction device (1) is provided with: a particle generation unit (10); an input unit (51); a particle classification unit (20); a particle detection unit (30); and a calculation unit (52) that, on the basis of a physical quantity factor that causes a change in the particle diameter in the particle detection unit (30) or the particle diameter distribution of the particles in the particle detection unit (30), determines the degree of change in the particle diameter of the particles reaching the particle detection unit (30) from the target particle diameter, and calculates the correction amount for the particle diameter extracted by the particle classification unit (20) on the basis of the degree of change. The particle diameter reaching the particle detection unit (30) becomes a target particle diameter. And a correction instruction unit (53) that instructs the particle classification unit (20) on the basis of the correction amount calculated by the calculation unit (52) so as to change the particle size of the particles extracted by the particle classification unit (20) to the particle size for correction.

Description

Technical Field

[0001] The present disclosure relates to a calibration device for a particle number measuring device, a calibration program, a method for determining a particle diameter for calibration, and a method for calibrating a particle number measuring device. Background Art

[0002] In recent years, in order to improve the cleanliness of automobile exhaust gas, it has become increasingly important to count the number of so-called nanoparticle-level particles contained in the exhaust gas, which have a smaller particle size than before. In the measurement of such nanoparticle-level particles, a particle number measuring device such as a condensation particle counter (CPC) is used. In order to use a particle number measuring device to count fine particles with high precision, it is necessary to properly calibrate the particle number measuring device. In the past, the particle number measuring device was calibrated by counting particles of a specified particle size using a particle generator that generates particles of droplets and a particle classifier that classifies the particles generated by the particle generator.

[0003] On the other hand, Patent Document 1 describes that evaporation occurs in liquid particles and the particle size of the liquid particles changes. Furthermore, Patent Document 2 describes that the counting efficiency of an condensation particle counter changes depending on the particle size.

[0004] Patent Document 1: Japanese Patent Application Laid-Open No. 2008-185559 Patent Document 2: Japanese Patent Publication No. 7-104259 Summary of the Invention Problems to be solved by the invention

[0005] However, in the calibration equipment and calibration method of the conventional particle number measuring device using a particle classifier, the particle classifier extracts particles of a desired particle size for calibration, but no consideration is given to the possibility that the particle size of the particles classified and extracted by the particle classifier may vary.

[0006] The present disclosure aims to provide a calibration device for a particle count measurement device, a calibration program, a method for determining a calibration particle size, and a calibration method for a particle count measurement device, which can reduce the influence of changes in particle size after classification and perform more accurate calibration. Means for solving problems

[0007] The present disclosure solves the above-mentioned problems by the following solution means. In addition, for easy understanding, the present disclosure is described with reference numerals corresponding to the embodiments thereof, but the present disclosure is not limited thereto.

[0008] The first disclosure is a calibration device (1, 1B) for calibrating a particle number measuring device (31), comprising: a particle generating unit (10) for generating particles; an input unit (51) for receiving an input of a target particle size; a particle classification unit (20) for classifying particles generated from the particle generating unit (10) and extracting particles having a target particle size received by the input unit (51); a particle detection unit (30) for detecting particles extracted by the particle classification unit (20); and a calculation unit (52) for calculating a particle size change based on a physical quantity factor or a factor that causes a change in particle size in the particle detection unit (30). The particle size distribution of the particles in the particle detection section (30) is calculated, the degree of change of the particle size of the particles reaching the particle detection section (30) from the target particle size is calculated, and a correction amount of the particle size extracted by the particle classification section (20) is calculated based on the degree of change so that the particle size reaching the particle detection section (30) becomes the target particle size; and a correction indication section (53) is used to indicate the particle classification section (20) based on the correction amount calculated by the calculation section (52) so as to change the particle size of the particles extracted by the particle classification section (20) to the correction particle size.

[0009] The second disclosure is a calibration device (1, 1B) for a particle number measuring device (31). In the calibration device (1, 1B) for the particle number measuring device (31) described in the first disclosure, a physical quantity factor detection unit (40) is provided. The physical quantity factor detection unit (40) detects the physical quantity factor, and the calculation unit (52) calculates the calibration quantity using at least the physical quantity factor obtained by the physical quantity factor detection unit (40).

[0010] The third disclosure is a calibration device (1) for a particle number measuring device (31). In the calibration device (1, 1B) for the particle number measuring device (31) described in the first disclosure, there is a particle size distribution measuring unit (33), the particle size distribution measuring unit (33) is arranged in the particle detection unit (30), and detects the particle size distribution of particles reaching the particle detection unit (30), and the calculation unit (52) uses the particle size distribution detected by the particle size distribution measuring unit (33) to calculate the correction amount.

[0011] The fourth disclosure is a calibration device (1, 1B). In the calibration device (1, 1B) of the particle number measuring device (31) described in technical solution 1 or 2, the physical quantity factor is at least one of the temperature, humidity, pressure, flow rate and residence time of the fluid in the flow path from the particle classification part (20) to the particle detection part (30).

[0012] The fifth disclosure is a calibration device (1) for a particle number measuring device (31). In the calibration device (1) for the particle number measuring device (31) described in the third disclosure, the particle size distribution measuring section (33) comprises: a second particle classification section (34) for classifying particles arriving at the particle size distribution measuring section (33); and a particle number counting section (35) connected to the downstream side of the second particle classification section (34) for counting the number of particles after classification by the second particle classification section (34).

[0013] The sixth disclosure is a calibration device (1) for a particle number measuring device (31). In the calibration device (1) for the particle number measuring device (31) described in the third disclosure or the fifth disclosure, the input unit (51) is capable of accepting a function representing the detection efficiency of each particle size of the particle number measuring device (31) of the calibration object, and the calculation unit (52) uses the particle size distribution detected by the particle size distribution measurement unit (33) to calculate the detection efficiency achieved by the particle number measuring device (31) of the calibration object at the target particle size.

[0014] The seventh disclosure is a calibration device (1, 1B) of a particle number measuring device (31). In the calibration device (1, 1B) of the particle number measuring device (31) described in any one of the first to sixth disclosures, the calibration indication unit (53) indicates to the particle classification unit (20) to change the voltage applied to the classification tube of the particle classification unit (20).

[0015] The eighth disclosure is a calibration device (1, 1B) for a particle number measuring device (31). In the calibration device (1, 1B) for a particle number measuring device (31) described in any one of the first to seventh disclosures, the particles generated by the particle generating section (10) are mainly composed of polyα-olefin, and the solvent for diluting the polyα-olefin is ethanol at a weight ratio of more than 50%.

[0016] The ninth disclosure is a calibration device (1, 1B) of a particle number measuring device (31). In the calibration device (1, 1B) of the particle number measuring device (31) described in any one of the first to eighth disclosures, the flow path from the particle generating section (10) to the particle classification section (20) is an evaporation flow path in which components from the particle surface are evaporated in advance, so that the reduction rate of the particle size due to the evaporation of components from the particle surface in the flow path from the particle classification section (20) to the particle detection section (30) is less than 3%.

[0017] The tenth disclosure is a calibration program for calibrating a particle number measuring device (31), which causes a computer (50) to execute the following steps: a step in which a particle generating unit (10) generates particles; a step in which an input unit (51) receives an input of a target particle size from a user; a step in which a particle classification unit (20) classifies particles generated from the particle generating unit (10) and extracts particles having a target particle size received from the input unit (51); a step in which a particle detection unit (30) detects particles extracted by the particle classification unit (20); a step in which a calculation unit (52) calculates a particle size based on a particle size change in the particle detection unit (30). The invention further comprises the following steps: determining a physical quantity factor or a particle size distribution of particles in the particle detection section (30), calculating a degree of change of the particle size of particles arriving at the particle detection section (30) from the target particle size, and calculating a correction amount of the particle size extracted by the particle classification section (20) based on the degree of change so that the particle size arriving at the particle detection section (30) becomes the target particle size; and instructing the particle classification section (20) to change the particle size of the particles extracted by the particle classification section (20) to a correction particle size based on the correction amount calculated by the calculation section (52).

[0018] The eleventh disclosure is a correction procedure, which includes a step in which a physical quantity factor detection unit (40) detects the physical quantity factor, and the calculation unit (52) uses at least the physical quantity factor obtained by the physical quantity factor detection unit (40) to calculate the correction amount.

[0019] The twelfth disclosure is a correction procedure, which includes a step in which the particle size distribution measuring unit (33) detects the particle size distribution of particles reaching the particle detection unit (30), and the calculation unit (52) uses the particle size distribution detected by the particle size distribution measuring unit (33) to calculate the correction amount.

[0020] The thirteenth disclosure is a method for determining a particle size for calibration, which is used for calibrating a particle number measuring device (31), comprising: a step in which a particle generating unit (10) generates particles; a step in which an input unit (51) receives an input of a target particle size from a user; a step in which a particle classification unit (20) classifies particles generated from the particle generating unit (10) and extracts particles corresponding to the target particle size received from the input unit (51); a step in which a particle detection unit (30) detects particles extracted by the particle classification unit (20); and a step in which a calculation unit (52) calculates the particle size based on a physical factor that causes a change in the particle size in the particle detection unit (30). The method further comprises the following steps: determining a quantity factor or a particle size distribution of particles in the particle detection section (30), calculating a degree of change of the particle size of the particles arriving at the particle detection section (30) from the target particle size, and calculating a correction amount of the particle size extracted by the particle classification section (20) based on the degree of change so that the particle size arriving at the particle detection section (30) becomes the target particle size; and instructing the particle classification section (20) to change the particle size of the particles extracted by the particle classification section (20) to a correction particle size based on the correction amount calculated by the calculation section (52).

[0021] The fourteenth disclosure is a method for determining a particle size for correction. In the method for determining a particle size for correction described in the thirteenth disclosure, the method includes a step in which a physical quantity factor detection unit (40) detects the physical quantity factor, and the calculation unit (52) calculates the correction quantity using at least the physical quantity factor obtained by the physical quantity factor detection unit (40).

[0022] The fifteenth disclosure is a method for determining the particle size for correction. In the method for determining the particle size for correction described in the thirteenth disclosure, it includes a step in which the particle size distribution measuring unit (33) detects the particle size distribution of particles reaching the particle detection unit (30), and the calculation unit (52) uses the particle size distribution detected by the particle size distribution measuring unit (33) to calculate the correction amount.

[0023] The sixteenth disclosure is a calibration method for a particle number measuring device (31), wherein the particle classification section (20) extracts particles according to a calibration particle size determined by a calibration particle size determination method described in any one of the thirteenth to fifteenth disclosures, and calibrates the particle number measuring device (31) of the calibration object using the particles of the calibration particle size extracted by the particle classification section (20).

[0024] According to the present disclosure, it is possible to provide a particle count measurement device calibration apparatus, a calibration program, a method for determining a calibration particle size, and a particle count measurement device calibration method that can reduce the influence of changes in particle size after classification and perform more accurate calibration. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 1 is a block diagram showing the configuration of a calibration device 1 of the particle number measuring apparatus according to the embodiment. Figure 2 This is a diagram showing an example of a function of the detection efficiency of the particle number measuring device 31 for each particle size. Figure 3 This is a diagram summarizing the flow channel morphologies of the flow channel F1 before classification and the flow channel F4 after classification, which were obtained from an experiment for investigating the relationship between the retention time of particles in the flow channel and the reduction in size of the particles. Figure 4 This is a graph in which the effect of the post-classification residence time on the particle diameter reaching the particle detection unit 30 is plotted against the pre-classification residence time. Figure 5 This is a graph showing the effect of the residence time before classification on the reduction rate. Figure 6 This is a diagram mainly showing the flow of operations when the control unit 50 implements the method for determining the correction particle diameter and the correction method. Figure 7 This is a graph summarizing the detection efficiencies obtained for each particle size in Examples and Comparative Examples. Figure 8 This is a graph in which the particle size change ΔDp (nm) due to evaporation is obtained as the difference between the particle size after classification and the measured particle size, and the result is plotted for each measured particle size. Figure 9 This is a graph showing the difference in detection efficiency between the comparative example and the example with a particle size of 10 nm. Figure 10 This is a graph showing the difference in detection efficiency between the comparative example and the example with a particle size of 15 nm. Figure 11 1 is a block diagram showing the configuration of a calibration device 1B of a particle number measuring apparatus according to a second embodiment. DETAILED DESCRIPTION

[0026] Hereinafter, one embodiment of the present disclosure will be described with reference to the drawings and the like.

[0027] (First embodiment) Figure 1 1 is a block diagram showing the configuration of a calibration device 1 of a particle number measuring apparatus according to a first embodiment. Figure 1 In the drawings, the following figures are schematically shown, and the size and shape of each part are appropriately exaggerated or omitted for ease of understanding. In addition, in the following description, specific numerical values, shapes, materials, etc. are shown for explanation, but these can be appropriately changed.

[0028] The particle number measurement device calibration apparatus 1 includes a particle generator 10 , a first particle classifier 20 , a particle detector 30 , a physical quantity factor detector 40 , and a control unit 50 , and is used when calibrating a particle number measurement device 31 as a calibration target.

[0029] The particle generator (particle generating unit) 10 is an electronic sprayer that generates a plurality of liquid particles. The particles generated by the particle generator 10 of this embodiment are made of a material generally referred to as poly-alpha-olefin (Poly-Alpha-Olefins: PAO). In the particle generator 10 of this embodiment, the poly-alpha-olefin is used in a state diluted with a solvent having ethanol as the main component. The solvent for diluting the poly-alpha-olefin is composed of an organic solvent containing a lower alcohol, and ethanol is preferably 50% or more, more preferably 75% or more, and ideally 100% by weight. In addition, the solvent may contain, for example, toluene in addition to the lower alcohol. In this embodiment, the solvent for diluting the poly-alpha-olefin is 100% ethanol by weight. As the solvent, for example, a mixture of ethanol and isopropyl alcohol can also be used as the solvent. However, since ethanol has a greater polarity, the number of particles generated by the particle generator 10 can be increased by increasing the proportion of ethanol. In addition, in order to increase the number of particles generated by the particle generator 10, the electrolyte contained in the solvent can also be increased.

[0030] The first particle classifier (particle classification unit) 20 classifies the particles generated by the particle generator 10, extracts particles corresponding to the target particle size received by the input unit described later, and discharges them downstream. The first particle classifier 20 uses a differential electrostatic classifier (Differential Mobility Analyzer: DMA). The first particle classifier 20 has a double-cylindrical classification tube that functions as an electrode. The first particle classifier 20 only extracts (classifies) particles of a particle size corresponding to the voltage applied to the classification tube. Therefore, the first particle classifier 20 can extract particles of various particle sizes by changing the voltage applied to the classification tube.

[0031] The particle detection section 30 is provided with a detector for detecting particles classified and extracted by the first particle classifier 20. The particle detection section 30 is provided at a position where a particle number measuring device 31 to be calibrated can be arranged. Here, "being provided at a position where a particle number measuring device 31 can be arranged" means that the particle number measuring device 31 may be provided or not provided, as long as it can be provided. This includes the case where the particle number measuring device 31 and the particle size distribution measuring section 33 described later are configured to be replaceable. In addition, for ease of understanding, the particle number measuring device 31 and the particle size distribution measuring section 33 are described here in a manner such that they cannot be replaced but are arranged side by side. The particle detection section 30 of this embodiment is provided with a particle number measuring device 31, a reference device 32, and a particle size distribution measuring section 33.

[0032] The particle number measuring device 31 is a condensation particle counter (CPC) that is the object of calibration by the calibration device 1 of this embodiment. The particle number measuring device 31 is used for particle measurement in, for example, automobile manufacturing plants, inspection agencies, or research institutions, etc., to confirm that harmful particles in exhaust gas are within a specified value. The particle number measuring device 31 can measure exhaust gas directly or indirectly. In order for the particle number measuring device 31 to accurately measure, the calibration operation is performed using the calibration device 1 of this embodiment. In addition, the particle number measuring device 31 can also measure particles generated from the brakes of the vehicle (brake dust), particles generated from the tires (tire dust), particles contained in the exhaust gas from the factory, or particles contained in the atmosphere.

[0033] The reference device 32 measures the number of particles serving as a reference. The reference device 32 can be, for example, an electrometer. By measuring the current, the electrometer can measure the number of uniformly charged particles regardless of the particle size, and thus can obtain the number of particles serving as a reference for calibrating the particle number measuring device 31. However, the electrometer is not suitable for counting particles that have not been subjected to a charge treatment, such as particles of a target particle size in exhaust gas. In the calibration device 1 of the present embodiment, since the first particle classifier 20 including the charge neutralizer is provided on the upstream side, only particles of a target particle size with a univalent charge can be accurately counted. In addition, as the reference device 32, in addition to the electrometer, for example, a CPC having a higher accuracy than the CPC of the calibration object can also be used.

[0034] The particle generator 10, first particle classifier 20, particle count measuring device 31, and reference device 32 described so far are identical to conventional calibration equipment, and previously, calibration of the particle count measuring device 31 was performed using this configuration. However, in recent years, exhaust gas measurement has required counting the number of so-called nanoparticle-level particles contained in the exhaust gas, which have a smaller particle size than previously. Furthermore, the applicant's research has revealed that changes in the particle size of particles classified and extracted by the particle classifier affect the calibration accuracy when nanoparticles are used as the target. Changes in the particle size of particles classified and extracted by the particle classifier were not previously considered in calibration operations, but because the target particles were larger in size, the impact on calibration accuracy was considered small and negligible. However, it has been discovered that when calibrating a particle count measuring device for very fine particles with a particle size of 15 nm or less, and particularly when calibrating a particle count measuring device for very fine particles with a particle size of 10 nm or less, changes in the particle size of particles classified and extracted by the particle classifier can significantly affect calibration accuracy.

[0035] Particle generator 10 has been used in calibration operations in the past and is also used in this embodiment. Particle generator 10 uses an electronic atomizer to generate liquid particles, which are then used for calibration. However, since these are liquid particles, the liquid in the liquid particles continues to evaporate immediately after generation, causing the particle size of the liquid particles to gradually decrease. Figure 2 : is a graph showing an example of a function of the detection efficiency of the particle number measuring device 31 for each particle size. Figure 2 The relationship between the particle size and the detection efficiency shown also shows that the particle number measuring device has a stable detection efficiency of about 100% in a region with a relatively large particle size (stable region), regardless of changes in the particle size. In contrast, the particle number measuring device has a region (cutoff region) where the detection efficiency decreases significantly when the particle size becomes smaller. In the cutoff region, the detection efficiency changes significantly due to small changes in the particle size. In a particle number measuring device that has a cutoff region in a relatively large particle size range (a range where the particle size is greater than a specified value (for example, 15nm)) as in the past, the change in particle size reduction from the particle generator to the particle number measuring device is small and has almost no effect on the measurement results. However, it can be seen that in a range where the particle size is relatively small compared to the past (for example, a range where the particle size is less than 15nm), the change in particle size reduction from the particle generator to the particle number measuring device has a greater impact on the measurement results. Therefore, the correction device 1 of the particle number measuring device of this embodiment has a structure including a particle size distribution measuring unit 33 (a second particle classifier 34 and a particle number counter 35), a physical quantity factor detection unit 40 and a control unit 50 as described below, so as to calibrate the particle number measuring device 31 more accurately.

[0036] The particle size distribution measuring section 33 detects the particle size distribution of the particles arriving at the particle detection section 30. The particle size distribution measuring section 33 of this embodiment is composed of a second particle classifier 34 and a particle number counter (particle number counting section) 35. The second particle classifier 34 sequentially classifies the particles arriving at the particle size distribution measuring section according to the particle size, and the classified particle size is transported to the particle number counter 35 on the downstream side according to the particle size. The particle number counter 35 is connected to the downstream side of the second particle classifier 34 and counts the number of particles classified by the second particle classifier 34. By cooperating with the second particle classifier 34 and the particle number counter 35, the particle size to be counted is changed in sequence, and the number of particles at each particle size is counted, thereby obtaining a particle size distribution representing the distribution of the particle size. The information obtained by the second particle classifier 34 and the particle number counter 35 or the information related to the particle size distribution is sent to the control section 50 (input section 51). In this embodiment, a CPC having a smaller cutoff diameter (ie, a higher counting sensitivity for nanoparticles) than that of the particle counting device 31 to be calibrated is used as the particle counter 35 .

[0037] Flow paths F1 to F5 are formed from the particle generator 10 to the particle detection unit 30 and between the second particle classifier 34 and the particle number counter 35. Specifically, flow path F1 is a flow path connecting the particle generator 10 and the first particle classifier 20. Flow path F2 is a flow path connecting the first particle classifier 20 and the particle number measuring device 31. Flow path F3 is a flow path connecting the first particle classifier 20 and the reference device 32. Flow path F4 is a flow path connecting the first particle classifier 20 and the second particle classifier 34. Flow path F5 is a flow path connecting the second particle classifier 34 and the particle number counter 35. Flow paths F2, F3, and F4 are configured so that the particle size changes are the same. For example, flow paths F2, F3, and F4 can be configured so that their respective inner diameters and tube lengths are the same, or they can be configured so that the residence time of the flowing fluids is the same.

[0038] The physical quantity factor detection unit 40 detects or inputs a physical quantity factor that causes particle size change and transmits the detection result to the calculation unit 52. Examples of the physical quantity factor that causes particle size change include factors such as the temperature, humidity, pressure, flow rate, and / or residence time of the fluid in the flow path from the first particle classifier 20 to the particle detection unit 30, which can cause particle size change. Alternatively, the physical quantity factor may be the length and / or inner diameter of the flow path from the first particle classifier 20 to the particle detection unit 30.

[0039] The control unit 50 includes an input unit 51, a calculation unit 52, and a calibration instruction unit 53. The control unit 50, which is configured to include the input unit 51, the calculation unit 52, and the calibration instruction unit 53, can be implemented by, for example, installing a calibration program (computer program) in a computer device and executing it. The control unit 50 can be a general-purpose smartphone, tablet terminal, personal computer, etc., or a dedicated computer used for the calibration device 1 of the particle number measuring device. The computer device referred to in the present invention refers to an information processing device including a control unit and a storage device. By executing the above-mentioned calibration program, the control unit 50 can implement a method for determining a calibration particle size and a calibration method for calibrating the particle number measuring device 31.

[0040] The input unit 51 receives an input of a target particle size from the user P or the like. In addition, the input unit 51 can receive a function representing the detection efficiency of each particle size of the particle number measuring device 31 to be calibrated from the user P or the like. As a function input to the input unit 51, for example, Figure 2 The function is obtained by functionalizing the curve of Figure 2 The data group of the curve is input as a function (a function of detection efficiency with particle size as a variable). By accepting the function, in the operation unit 52, the detection efficiency measurement result in the state of not being reduced and corrected (based on the feedback of the particle size distribution measurement unit) is applied to the vertical axis, and the particle size data of the particle size distribution measurement unit is applied to the horizontal axis, so that the detection efficiency under the target particle size can be estimated. Furthermore, the input unit 51 can accept input of data related to the particle size distribution detected by the particle size distribution measurement unit 33. The input unit 51 can accept input, for example, through a pointing device such as a mouse, a keyboard or a touch panel, or can accept input through communication via an external network. The information input to the input unit 51 is transmitted to the operation unit 52.

[0041] The calculation unit 52 uses the information input to the input unit 51, the information obtained from the physical quantity factor detection unit 40, and the particle size distribution detected by the particle size distribution measurement unit to determine the degree of change in the particle size of the particles reaching the particle detection unit 30 from the target particle size. In this embodiment, since the liquid particles shrink in size due to evaporation, the degree of particle size reduction is determined for this degree of change. The degree of change (reduction) determined here can be a ratio or a differential value. Furthermore, the calculation unit 52 calculates a correction value for the particle size extracted by the first particle classifier 20 based on the determined degree of change, so that the particle size reaching the particle detection unit 30 reaches the target particle size. Furthermore, "bringing the particle size reaching the particle detection unit 30 to the target particle size" does not simply mean that the particle size reaching the particle detection unit 30 completely matches the target particle size. It also includes calculating a correction value to bring the particle size reaching the particle detection unit 30 closer to the target particle size, thereby bringing the particle size reaching the particle detection unit 30 to a value that is close to the target particle size. The correction amount calculated by the calculation unit 52 is transmitted to the correction instruction unit 53. The calculation unit 52 also calculates the detection efficiency achieved by the particle number measurement device 31 to be calibrated at the target particle size using the particle size distribution detected by the particle size distribution measurement unit 33.

[0042] The correction instruction unit 53 instructs the first particle classifier 20 to change the particle size of the particles classified and extracted by the first particle classifier 20 to the correction particle size based on the correction amount calculated by the calculation unit 52. The correction particle size reflects the change in the particle size from the target particle size from the classification and extraction by the first particle classifier 20 to the arrival at the particle detection unit 30. That is, the correction particle size is the particle size set in the first particle classifier 20 in order to make the particle size of the particles arriving at the particle detection unit 30 the same as the target particle size or a particle size close to the target particle size. As previously described, the first particle classifier 20 only extracts (classifies) particles of a particle size corresponding to the voltage applied to the classifier. Therefore, the correction instruction unit 53 issues an instruction to the first particle classifier 20 to change the voltage applied to the classifier provided by the first particle classifier 20 to a voltage for extracting (classifying) particles of the correction particle size.

[0043] In the example of this embodiment where liquid particles shrink in size due to evaporation, the calibration particle diameter is set to a larger diameter than the target particle diameter to compensate for the reduction. For example, to calibrate the particle count measurement device 31 at a particle diameter of 10 nm, particles classified and extracted by the first particle classifier 20 at a target particle diameter of 10 nm have already shrunk to 9.8 nm by the time they reach the particle detector 30. In this case, the degree of change in outer diameter is represented by a difference value of -0.2 nm or a rate of change of 98%, for example. The calibration indicator 53 compensates for this change by setting the calibration particle diameter at a particle diameter of 10 nm or very close to 10 nm upon arrival at the particle detector 30. Alternatively, the calibration particle diameter could be set to 10.2 nm in this case, but assuming that the degree of shrinkage due to evaporation varies depending on the particle size, a value that takes this effect into account can also be set. By performing the above operations by the calculation unit 52 and the calibration indicator 53, the calibration device 1 of this embodiment enables more accurate calibration.

[0044] Alternatively, the calibration device 1 may generate individual particles (e.g., sucrose) that do not cause particle size reduction using the particle generator 10, extract 10 nm sucrose particles using the particle classification unit 20, and measure these particles using the particle size distribution measurement unit 33. This operation enables confirmation and adjustment of the particle size measurement accuracy caused by a deviation in the particle transport time between the second particle classifier 34 and the particle counter 35 constituting the particle size distribution measurement unit 33.

[0045] By the above structure, the calibration device 1 of the present embodiment can perform calibration more accurately than before. However, in addition to performing calibration, it is preferable to suppress the change in particle size from the first particle classifier 20 to the particle detection unit 30. The reduction in particle size due to evaporation is a phenomenon that occurs mainly in all flow paths of flow path F1, flow path F2, flow path F3, flow path F4 and flow path F5. Therefore, it is believed that the time that particles stay (pass through) in these flow paths F1 to flow path F5 (hereinafter referred to as the residence time) is closely related to the evaporation time of the particles. Therefore, a variety of flow path inner diameters and tube lengths of the flow path F1 before classification and the flow path F4 after classification were prepared, and an experiment was conducted to investigate the relationship between the residence time of particles in these flow paths and the reduction of particles. In addition, the flow paths are all tubular.

[0046] Figure 3This is a diagram summarizing the flow path morphology of flow path F1 before classification and flow path F4 after classification used in an experiment to investigate the relationship between the retention time of particles in a flow path and the reduction of particles. As the retention time before classification of flow path F1, relative to condition B0: +0.0 sec (as a reference condition), condition B1: +6.0 sec, condition B2: +9.0 sec, condition B3: +10.5 sec, and flow paths with respectively extended retention times were set. In addition, the actual retention time before classification under condition B0: +0.0 sec was 0.26 sec. The specific morphology of flow path F1 is as follows. Figure 3 As shown. In addition, as the post-fractionation retention time of flow path F4, condition A1: +0.3 sec, condition A2: +0.6 sec, condition A3: +0.9 sec, condition A4: +1.2 sec and flow paths with respectively extended retention time are set relative to condition A0: +0.0 sec (as a reference condition). The specific form of flow path F4 is as follows Figure 3 As shown. Furthermore, the actual post-classification residence time under condition A0 at +0.0 sec was 0.22 sec. The four combinations of pre-classification flow path F1 and the five combinations of post-classification flow path F4 were combined, and the particle size distribution was determined by the particle size distribution measurement unit 33. Changes in the particle size reaching the particle detection unit 30 were confirmed. The particle size of the particles classified and extracted by the first particle classifier 20 was set to 10 nm.

[0047] Figure 4 This is a graph showing the effect of the retention time after classification on the particle size reaching the particle detection unit 30, plotted against the retention time before classification. Figure 4 The particle size on the vertical axis is set as GMD (Geometric Mean Diameter). Figure 4 As shown in Figure 2, as the residence time after classification increases, the particle size decreases. Furthermore, it can be seen that as the residence time before classification increases, the reduction rate (slope) and reduction amplitude (intercept) decrease, i.e., the reduction decreases. Therefore, to facilitate understanding of the influence of the residence time before classification, we will focus on the relationship between the residence time before classification and the reduction rate. Figure 5 This is a graph showing the effect of the residence time before classification on the reduction rate. Figure 5 , it can be seen that the shrinking speed begins to converge when the retention time before classification exceeds +8 seconds relative to the reference (+0 seconds), and the shrinking speed becomes quite stable when the retention time before classification exceeds +10 seconds. Therefore, in this embodiment, the flow path F1 before classification is set as an evaporation flow path that promotes evaporation in advance, so that it can be expected that Figure 5 The effect of increasing the retention time before classification by about +8 seconds is achieved. By ensuring an appropriate retention time before classification in the evaporation flow path, the reduction in particle size after classification can be suppressed.

[0048] The effect of increasing the retention time before classification by about +8 seconds is that the increase in the retention time before classification is between 6 seconds and 9 seconds. Figure 4 This was confirmed to occur in the regions where the particle size reduction rate due to evaporation of components from the particle surface in the flow paths F2, F3, and F4 from the first particle classifier 20 to the particle detector 30 was less than 3% (particle size 9.7 nm or greater). Specifically, the flow path F1 from the particle generator 10 to the first particle classifier 20 was configured as an evaporation flow path, where components from the particle surface were previously evaporated, so that the particle size reduction rate due to evaporation of components from the particle surface in the flow paths F2, F3, and F4 from the first particle classifier 20 to the particle detector 30 was less than 3%. However, it is assumed that by configuring flow path F1 as an evaporation flow path, the pre-classification retention time is prolonged, thereby reducing the number of particles resulting from, for example, particles adhering to the flow path walls. Therefore, in this embodiment, as previously described, the solvent for diluting the poly-α-olefin is 100% ethanol by weight, and this ethanol contains an appropriate amount of electrolyte (e.g., ammonium acetate), thereby increasing the number of particles generated by the particle generator 10.

[0049] In addition, refer to Figure 4 Even if the components are fully evaporated in advance in the flow path F1 from the particle generator 10 to the first particle classifier 20, if the residence time (increase time) after classification becomes longer, the reduction in particle size will be further aggravated. Therefore, with respect to the flow paths F2, F3, and F4 from the first particle classifier 20 to the particle detection unit 30, it is preferable to shorten the retention time of the particles (retention time after classification) as much as possible. In addition, for the purpose of accurately measuring the particle size at the inlet of the particle number measurement device 31 of the calibration object, it is preferable that the particle size reduction range, that is, the retention time in the flow paths F2, F3, and F4 is consistent. For example, for the purpose of suppressing the reduction range to less than 0.1 nm, it is preferable that the retention time of the flow paths F2, F3, and F4 from the first particle classifier 20 to the particle detection unit 30 is less than 1 second.

[0050] (Determination and calibration method of the calibration particle size) Figure 6 This is a diagram mainly showing the flow of operations when the control unit 50 implements the method for determining the correction particle diameter and the correction method.

[0051] In step (hereinafter referred to as S) 11, the particle generator 10 generates particles. In step S12, the input unit 51 receives input of a target particle size from the user. In step S13, the first particle classifier 20 classifies the particles generated by the particle generator 10 and extracts particles corresponding to the target particle size received by the input unit 51.

[0052] In S14 , the particle size distribution measurement unit 33 of the particle detection unit 30 detects the particle size distribution of the particles extracted by the first particle classifier 20 and reaching the particle detection unit 30 .

[0053] In S15 , the physical quantity factor detection unit 40 detects physical quantity factors that affect particle size changes, such as temperature, humidity, and air pressure.

[0054] In S16 , the calculation unit 52 uses the physical quantity factor obtained by the physical quantity factor detection unit 40 and the particle size distribution obtained by the particle size distribution measurement unit 33 to determine the degree of change in the particle size reaching the particle detection unit 30 from the target particle size.

[0055] In S17 , the calculation unit 52 calculates the correction amount of the particle size extracted by the first particle classifier 20 based on the degree of change so that the particle size reaching the particle detection unit 30 becomes the target particle size.

[0056] In S18 , the correction instructing unit 53 instructs the first particle classifier 20 to change the particle size of the particles extracted by the first particle classifier 20 to the correction particle size based on the correction amount calculated by the calculating unit 52 .

[0057] In S19 , particles extracted and classified by the first particle classifier 20 at a particle size changed to the calibration particle size are counted by the reference device 32 and the particle number measuring device 31 to calculate the detection efficiency, that is, perform calibration at the target particle size.

[0058] By performing the above-described operation for each required target particle size, the calibration work of the particle number measuring device 31 is completed.

[0059] (Example) The following describes the results of actually manufacturing the calibration device 1 of this embodiment having the above-described structure and comparing it with a conventional calibration device. Figure 3 Condition B0 in the above method is sufficient to carry out evaporation before classification. In addition, the flow paths F2 to F4 after classification are configured as Figure 3 Condition A0 in the embodiment was used to suppress the reduction in particle size due to evaporation after classification. Furthermore, as a comparative example, the same configuration as in the embodiment was employed, except that the control unit 50 did not perform the correction operation. The particle sizes evaluated (target particle sizes) were 7 nm, 8 nm, 9.8 nm, 10 nm, 10.2 nm, 11 nm, 13 nm, and 15 nm.

[0060] Figure 7 : is a graph summarizing the detection efficiencies obtained for each particle size in the examples and comparative examples. Figure 7As shown in FIG, the calibration operation is performed by determining the detection efficiency for each target particle size. If the detection efficiency is accurately determined, the actual number of particles can be accurately determined based on the counting results of the corresponding particle size and the detection efficiency. Figure 7 As shown, when the particle size is below 10 nm, a difference occurs between the Example and the Comparative Example. The conditions of the Example, which performs calibration, can achieve higher detection efficiency compared to the Comparative Example, which does not perform calibration. This is believed to be because the calibration process in the Comparative Example measures the detection sensitivity at a particle size smaller than the target particle size. In contrast, the measurement results of the Example use the target particle size for the detection sensitivity measurement, thus enabling accurate detection sensitivity measurement and achieving higher-precision calibration.

[0061] Figure 8 The graph is a graph in which the particle size change ΔDp (nm) due to evaporation is plotted as the difference between the particle size after classification and the measured particle size for each measured particle size. Figure 8 The data above will not be Figure 7 The data of the examples and comparative examples are summarized and shown separately. This is because, although corrections were made in the examples, the change in particle size after classification was no different from that of the comparative examples. Figure 8 The particle size on the horizontal axis is set as the particle size input to the first particle classifier 20. Therefore, the following relationship is established: (particle size input to the first particle classifier 20: horizontal axis) - (ΔDp: vertical axis) ≈ particle size measured by the particle size distribution measurement unit 33. Figure 8 It can be seen that at a particle size of 15 nm, the particle size barely changes (ΔDp≈0), and the smaller the particle size, the greater the reduction. It can be confirmed that particles smaller than 15 nm are more susceptible to reduction, and if the reduction is not corrected, the detection sensitivity measurement results will vary.

[0062] In addition, the above Figure 7 The numerical data of 10nm and 15nm are summarized in the table. Figure 9 and Figure 10 . Figure 7 The measurements were performed for 3 days, and therefore individual data and average data are shown. Figure 9 This is a graph showing the difference in detection efficiency between the comparative example and the example when the particle diameter is 10 nm. Figure 10 This is a graph showing the difference in detection efficiency between the comparative example and the example when the particle size is 15 nm. Figure 9 、 Figure 10 As can be seen from the numerical values, a difference of -2.82 in detection sensitivity was observed when the particle size was 10 nm. In contrast, when the particle size was 15 nm, there was almost no difference in detection sensitivity even after 3 days.

[0063] As described above, according to the calibration device 1 of the first embodiment, the first particle classifier 20 actually measures the degree of change in the particle size of particles arriving at the particle detection unit 30 after classification, and uses this result to calibrate the particle size classified and extracted by the first particle classifier 20. Therefore, for example, it is possible to compensate for the decrease in calibration accuracy caused by the reduction in particle size due to evaporation, which is particularly significant for very small particles of approximately 10 nm, enabling higher-precision calibration. Furthermore, since the flow path F1 from the particle generator 10 to the first particle classifier 20 is provided with an evaporation flow path that has been preliminarily used to evaporate components, the degree of change in the particle size of particles arriving at the particle detection unit 30 after classification by the first particle classifier 20 can be reduced, thereby reducing the calibration error itself that occurs before calibration. According to the calibration device 1 of this embodiment, it is possible to address the calibration error in the detection sensitivity of particles as small as 10 nm that has arisen with the implementation of new regulations on automobile exhaust particulate matter in Europe, and to optimize calibration. According to the calibration device 1 of this embodiment, by measuring the diameter reduction of the calibration particle component, ie, PAO, caused by evaporation in the calibration device 1 and correcting the influence of this on the detection sensitivity correction, calibration with good reproducibility can be achieved.

[0064] (Second embodiment) Figure 11 This is a block diagram showing the configuration of a calibration device 1B of a particle count measurement apparatus according to a second embodiment. The calibration device 1B of the second embodiment differs from the calibration device 1 of the first embodiment in that the particle detection unit 30B does not include a structure corresponding to the particle size distribution measurement unit 33 of the first embodiment. Since other aspects are identical to the calibration device 1 of the first embodiment, components that perform the same functions as those of the first embodiment are denoted by the same reference numerals, and duplicate descriptions are omitted as appropriate.

[0065] In the correction device 1B of the second embodiment, since it does not have a structure equivalent to the particle size distribution measuring section 33 in the first embodiment, the operation section 52 calculates the degree of change of the particle size reaching the particle detection section 30 from the target particle size based on the information from the physical quantity factor detection section 40. Here, since the measurement result of the particle size actually reaching the particle detection section 30 is not obtained, in the operation section 52 of the second embodiment, the retention time of the particles can also be calculated by pre-inputting or inputting the information of the flow paths F1, F2, and F3 of the correction device 1B via the input section 51. Alternatively, the retention time of the particles can also be detected or input as a physical quantity factor. In addition, the operation section 52 pre-stores the information related to the flow paths F1, F2, and F3. Figure 4 and Figure 5 Based on this information, the calculation unit 52 can determine the degree of change in the particle size of the particles reaching the particle detection unit 30 from the target particle size. The subsequent operation is the same as that of the first embodiment.

[0066] According to the calibration device 1B of the second embodiment, high-precision calibration can be performed with a simpler structure. Furthermore, since measurement work using the particle size distribution measuring unit 33 is unnecessary, calibration work can also be performed simply.

[0067] (Deformation method) The present invention is not limited to the above-described embodiment, and various modifications and changes are possible, and these are also within the scope of the present disclosure.

[0068] The first embodiment has been described as an example in which the calculation unit 52 uses information from both the physical quantity factor detection unit 40 and the particle size distribution measurement unit 33 to determine the degree of change in the particle size of particles arriving at the particle detection unit 30 from the target particle size. This is not limiting. For example, the calculation unit 52 may determine the degree of change in the particle size of particles arriving at the particle detection unit 30 from the target particle size without using the physical quantity factor. In this case, the physical quantity factor detection unit 40 may be omitted.

[0069] In the first and second embodiments, the physical quantity factor detection unit 40 may be omitted. In this case, the physical quantity factor may be input via the input unit 51, or a physical quantity factor calculated or stored in advance may be used.

[0070] In the second embodiment, instead of calculating the particle size reduction rate based on the physical quantity factor, a previously calculated particle size reduction rate may be used as long as the physical quantity factor is the same. In this case, the physical quantity factor detection unit 40 may be omitted.

[0071] Furthermore, in the first and second embodiments, when the length and / or residence time of the flow path F1 are adjusted so that components in the flow path F1 from the particle generator 10 to the first particle classifier 20 are sufficiently evaporated in advance, the particle size after passing through the first particle classifier 20 is substantially not reduced. In this case, the calibration device 1 may not include part or all of the control unit 50. In other words, the calibration device may include the particle generator 10, the flow path F1 in which the residence time is adjusted so that components are sufficiently evaporated in advance, the first particle classifier 20, and the particle detector 30 (30B).

[0072] In each embodiment, the case where the particle size is reduced is described as an example, but the present invention is not limited thereto. For example, the calibration device of the present invention can also be used when the particle size is increased. Description of reference numerals:

[0073] 1, 1B: calibration device; 10: particle generator; 20: first particle classifier; 30, 30B: particle detection unit; 31: particle number measuring device; 32: reference device; 33: particle size distribution measuring unit; 34: second particle classifier; 35: particle number counter; 40: physical quantity factor detection unit; 50: control unit; 51: input unit; 52: operation unit; 53: calibration indication unit; F1 to F5: flow path.

Claims

1. A calibration device for a particle number measuring device, for use in calibrating a particle number measuring device, wherein: have: a particle generating unit for generating particles; An input portion, receiving an input of a target particle size; a particle classification unit for classifying the particles generated from the particle generation unit and extracting particles having a target particle size corresponding to that received by the input unit; a particle detection unit for detecting particles extracted by the particle classification unit; a calculation unit that calculates a degree of change in the particle size of particles arriving at the particle detection unit from the target particle size based on a physical quantity factor causing a change in the particle size at the particle detection unit or a particle size distribution of particles at the particle detection unit, and calculates a correction amount for the particle size extracted by the particle classification unit based on the degree of change so that the particle size arriving at the particle detection unit becomes the target particle size; as well as The correction instructing unit instructs the particle classification unit to change the particle size of particles extracted by the particle classification unit to a correction particle size based on the correction amount calculated by the calculation unit.

2. The calibration device for a particle number measuring apparatus according to claim 1, wherein The calibration device of the particle number measuring apparatus includes a physical quantity factor detection unit that detects the physical quantity factor. The calculation unit calculates the correction amount using at least the physical quantity factor obtained by the physical quantity factor detection unit.

3. The calibration device for a particle number measuring apparatus according to claim 1, wherein The calibration device of the particle number measuring device includes a particle size distribution measuring unit, which is provided at the particle detection unit and detects the particle size distribution of particles reaching the particle detection unit. The calculation unit calculates the correction amount using the particle size distribution detected by the particle size distribution measurement unit.

4. The calibration device for a particle number measuring apparatus according to claim 1 or 2, wherein: The physical quantity factor is at least one of temperature, humidity, pressure, flow rate, and residence time of a fluid in a flow path from the particle classification section to the particle detection section.

5. The calibration device for a particle number measuring apparatus according to claim 3, wherein The particle size distribution measurement section includes: a second particle classification section for classifying particles reaching the particle size distribution measurement section; and a particle number counting section connected to a downstream side of the second particle classification section for counting the number of particles classified by the second particle classification section.

6. The calibration device for a particle number measuring apparatus according to claim 3 or 5, wherein: The input unit is capable of receiving a function representing the detection efficiency of each particle size of the particle number counting device to be calibrated. The calculation unit calculates the detection efficiency achieved by the particle number measuring device to be calibrated at the target particle size using the particle size distribution detected by the particle size distribution measurement unit.

7. The calibration device for a particle number measuring apparatus according to any one of claims 1 to 3, wherein The correction instructing unit instructs the particle classifying unit to change a voltage applied to a classifying tube included in the particle classifying unit.

8. The calibration device of the particle number measuring apparatus according to any one of claims 1 to 3, wherein The particles generated by the particle generating section contain poly-α-olefin as a main component, and the solvent used to dilute the poly-α-olefin contains ethanol at a weight ratio of 50% or more.

9. The calibration device of the particle number measuring apparatus according to any one of claims 1 to 3, wherein The flow path from the particle generating section to the particle classification section is an evaporation flow path in which components from the particle surface are evaporated in advance, so that the reduction rate of the particle size due to evaporation of components from the particle surface in the flow path from the particle classification section to the particle detection section is less than 3%.

10. A calibration procedure for calibrating a particle number measuring device, wherein: The calibration program is used to enable the computer to execute the following steps: a step of generating particles in a particle generating unit; The input unit receives an input of a target particle size from a user; a step of classifying the particles generated from the particle generating portion and extracting particles having a target particle size received by the input portion; a step of detecting the particles extracted by the particle classification section by a particle detection section; a step of calculating, by a calculation unit, a degree of change in the particle size of particles reaching the particle detection unit from the target particle size based on a physical quantity factor causing a change in the particle size in the particle detection unit or a particle size distribution of particles in the particle detection unit, and calculating a correction amount for the particle size extracted by the particle classification unit based on the degree of change so that the particle size reaching the particle detection unit becomes the target particle size; and The step includes a step of instructing the particle classification unit to change the particle size of particles extracted by the particle classification unit to a correction particle size based on the correction amount calculated by the calculation unit.

11. The calibration program according to claim 10, wherein: The physical quantity factor detecting unit includes the steps of detecting the physical quantity factor. The calculation unit calculates the correction amount using at least the physical quantity factor obtained by the physical quantity factor detection unit.

12. The calibration program according to claim 10, wherein: The method comprises the step of detecting the particle size distribution of particles reaching the particle detection section by a particle size distribution measurement section, The calculation unit calculates the correction amount using the particle size distribution detected by the particle size distribution measurement unit.

13. A method for determining a calibration particle size for use in calibrating a particle number measuring device, wherein: include: a step of generating particles in a particle generating unit; The input unit receives an input of a target particle size from a user; a step of classifying the particles generated from the particle generating portion and extracting particles having a target particle size received by the input portion; a step of detecting the particles extracted by the particle classification section by a particle detection section; a step of calculating, by a calculation unit, a degree of change in the particle size of particles reaching the particle detection unit from the target particle size based on a physical quantity factor causing a change in the particle size in the particle detection unit or a particle size distribution of particles in the particle detection unit, and calculating a correction amount for the particle size extracted by the particle classification unit based on the degree of change so that the particle size reaching the particle detection unit becomes the target particle size; and The step includes a step of instructing the particle classification unit to change the particle size of particles extracted by the particle classification unit to a correction particle size based on the correction amount calculated by the calculation unit.

14. The method for determining the correction particle size according to claim 13, wherein: The physical quantity factor detecting unit includes the steps of detecting the physical quantity factor. The calculation unit calculates the correction amount using at least the physical quantity factor obtained by the physical quantity factor detection unit.

15. The method for determining the correction particle size according to claim 13, wherein: The method comprises the step of detecting the particle size distribution of particles reaching the particle detection section by a particle size distribution measurement section, The calculation unit calculates the correction amount using the particle size distribution detected by the particle size distribution measurement unit.

16. A method for calibrating a particle number measuring device, wherein: The particle classification unit extracts particles based on the calibration particle size determined by the calibration particle size determination method according to any one of claims 13 to 15. The particle number measuring device to be calibrated is calibrated using the particles of the calibration particle size extracted by the particle classification unit.

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