JP4748476B2 - Particle measuring device - Google Patents

Description

  The present invention relates to a technique for measuring fine particles in a fluid continuously and including information on particle diameter.

  Since the internal combustion engine is small and has an excellent characteristic of being able to output relatively large power, it can be used as a power source for various transportation engines such as automobiles, ships and aircraft, or as a power source for various stationary devices. As widely used. These internal combustion engines have an operating principle of combusting an air-fuel mixture compressed in a combustion chamber, converting the combustion pressure generated at that time into mechanical work, and taking it out as power.

  Among such internal combustion engines, an internal combustion engine (a so-called diesel engine, in-cylinder injection gasoline engine, etc.) that directly injects fuel into the combustion chamber and diffuses and burns fuel spray has excellent characteristics such as high fuel consumption efficiency. ing. However, on the other hand, particulate matter (Paticulate Matter, hereinafter referred to as PM) contained in exhaust gas has been pointed out to have an adverse effect on health. In addition, there is a legal regulation that suppresses the weight concentration of PM contained in the exhaust gas to a value below an allowable value. In recent years, it has been pointed out that particulates with a specific particle size range that is relatively small among PMs may have some effect on the human body. The impact of these particulates on health, including the need for regulation, has been examined. Has been.

  As a technique for measuring such fine particles in the exhaust gas, for example, a technique for collecting and measuring fine particles according to particle diameter using a collecting member (for example, Patent Document 1), light in the exhaust gas is used. A technique for measuring the concentration of fine particles based on scattered light from the fine particles when incident (for example, Patent Document 2), and further, the difference in speed at which the charged fine particles move in the electric field while receiving resistance from the fluid. A technique (Patent Document 3) that uses and measures fine particles while classifying them has been proposed.

JP 2003-35636 A JP 2003-114192 A JP 2005-24409 A

  However, all of the proposed techniques have a problem that it is difficult to stably and accurately measure fine particles having a small particle size range to be measured in a time series. That is, in the small particle size range to be measured, actions such as intermolecular force, electrostatic force, and thermophoresis appear greatly, so if the particles are collected using a collection member, the measurement conditions are strongly affected. Therefore, it is difficult to measure only fine particles having a target particle size range with high accuracy and stability. Of course, time series measurements cannot be performed. In addition, in the method of detecting scattered light from fine particles, time series measurement is possible, but it is difficult to obtain information on the particle size of the fine particles. Furthermore, the method of measuring particles while classifying the particles using the difference in the speed at which the charged particles move in the electric field is capable of highly accurate and stable time-series measurement, but it is possible to measure in advance. Only fine particles in a very narrow particle size range (substantially a specific particle size) set for the target can be measured. Therefore, in order to measure the target particle size range, it is necessary to divide the particle size to be measured little by little and measure it several times. Measurement accuracy is also reduced.

  In addition, the above-described problem is not limited to measuring fine particles in exhaust gas, but also when trying to continuously measure only fine particles in a particle size range to be measured from fine particles in fluid. It can occur just as well.

  The present invention has been made to solve the above-described problems in the prior art, and among the fine particles contained in the fluid, only fine particles within a predetermined particle size range can be stably and accurately obtained. Moreover, it aims to provide a technique that enables time-series measurement.

In order to solve at least a part of the problems described above, the fine particle measuring apparatus of the present invention employs the following configuration. That is,
A particle measuring device for measuring particles contained in a fluid,
A passage portion in which a measurement target fluid, which is a fluid containing fine particles to be measured, and a carrier fluid supplied together with the measurement target fluid flow in layers;
A fine particle charging portion provided on the upstream side of the passage portion to charge the fine particles;
An electric field forming unit that forms an electric field in a direction crossing the flow of the carrier fluid on the downstream side of the fine particle charging unit;
When the measurement target fluid and the carrier fluid pass through the electric field, the speed at which the charged fine particles move in the direction crossing the flow of the carrier fluid under the force of the electric field depends on the particle size of the fine particles. Correspondingly by utilizing different properties, from among the charged particles, the moving speed is fine particles having a small than a predetermined first threshold speed, the first to be removed as fine particles of a large diameter outside the measurement object A particulate removal section;
A second particle in which the moving speed is larger than a predetermined second threshold speed (however, larger than the first threshold speed) is removed from the charged fine particles as small-sized fine particles that are not to be measured. A fine particle removing portion of
A fine particle detection unit that detects the remaining fine particles from which the large-sized fine particles and the small-sized fine particles that are not measured are removed , and
The first fine particle removing portion is protruded from a side surface of the passage portion, and a tip is formed in an edge shape,
The gist of the present invention is that the second fine particle removing portion protrudes from the side surface of the passage portion on the upstream side of the first fine particle removing portion and has a tip formed in an edge shape .

Oite the particulate measurement equipment such invention, and inclusive measurement object fluid particles to be measured, and a carrier fluid, previously formed flow state where layered in the passage, intersecting the flow In addition to applying an electric field in the direction of the flow, the particles to be measured are charged upstream of the flow. The charged fine particles are carried on the flow of the fluid to be measured from the upstream to the downstream, receive the force from the electric field, move little by little in the direction crossing the flow, and eventually enter the carrier fluid. Here, the speed at which the charged fine particles move in the direction intersecting the flow varies depending on the particle diameter of the fine particles, and the larger the particle diameter, the greater the resistance received from the fluid, so the moving speed becomes smaller. As a result, the charged fine particles are caused to flow downstream in the passage through different paths depending on the particle diameter.

In the fine particle measurement apparatus and measurement method of the present invention, using these properties, the fine particles are separated depending on whether the moving speed is larger or smaller than a predetermined threshold speed, and one of the fine particles is detected. That is, by using the first fine particle removing portion that protrudes from the side surface of the passage portion and has a tip formed in an edge shape, fine particles whose moving speed is smaller than the first threshold speed are excluded from the measurement target. Remove as. Further, by using a second fine particle removal unit that protrudes from the side surface of the passage portion upstream from the first fine particle removal unit and has a tip formed in an edge shape, a predetermined second threshold speed (however, Fine particles larger than the first threshold speed are removed as small-diameter fine particles that are not measured. As described above, if the moving speed is different, the path through which the fine particles pass in the passage is also different. Therefore, the first fine particle removing portion and the second fine particle removing portion are protruded at appropriate positions from the side surface of the passage portion. In this way, it is possible to remove large-sized fine particles that are not measured and small-sized fine particles that are not measured. Then, the remaining fine particles excluding the large-sized fine particles that are not measured and the small-sized fine particles that are not measured are detected as fine particles to be measured .

As described above, as the particle size of the particles increases, the moving speed in the direction crossing the flow decreases, so when only fine particles whose moving speed is greater than the threshold speed are collected, the particle size is larger than the corresponding particle size. When only small particles are detected, and conversely, when only particles having a moving speed smaller than the threshold speed are collected, only large particles are detected. Therefore, Oite the particulate measuring equipment of the present invention, the strength and the electric field, the flow rate of the carrier fluid, and sampling position of the particles, on a preset properly, the first threshold speed and a second By appropriately setting the threshold speed, it is possible to measure only fine particles having a desired particle size range with high accuracy and stability in a time series.

Further, according to the fine particle measuring equipment of the present invention, the measurement object fluid and transport fluid, keep flowing in the passage in a state where the layered each other, it charges the fine particles on the upstream side, to form an electric field in the downstream With such a very simple configuration, only fine particles having a desired particle size range can be detected. For this reason, since the whole apparatus can be made into a simple structure, it becomes possible to set it as the measurement apparatus with high reliability, and being small and easy to manufacture.

Further, the fine measurement equipment of the present invention, the particle size range of the detected particles, the strength and the electric field, the flow rate of the carrier fluid, and the like sampling position of the fine particles, is determined accurately and uniquely regardless of the calibration be able to. For this reason, it becomes possible to obtain a highly reliable measurement value.

  Hereinafter, the above-described invention of the present application will be described in detail based on examples. FIG. 1 is an explanatory view conceptually showing a state in which fine particles contained in the exhaust gas of the internal combustion engine 10 are measured using the fine particle measuring apparatus 100 of the present embodiment. First, the rough structure of the illustrated particle measuring apparatus 100 will be described.

  As shown in FIG. 1, the particle measuring apparatus 100 of the present embodiment is roughly composed of a classification passage 110, a particle detector 120, a high-voltage power source 130, and the like. Connected to the upstream side of the classification passage 110 are a measurement target fluid introduction pipe 140 for introducing a measurement target fluid containing fine particles and a transport fluid supply pipe 150 for supplying the transport fluid into the classification passage. A discharge passage 160 for discharging the measurement target fluid and the carrier fluid is connected to the downstream side of the classification passage 110. A charger 170 is provided in the middle of the measurement target fluid introduction pipe 140. The charger 170 can give electric charge to the passing fine particles by performing corona discharge or the like inside. The classification passage 110 has a substantially circular cross section, and a columnar electrode 180 is provided at substantially the center of the classification passage 110. An electric field can be formed between the electrode 180 and the inner wall surface of the classification passage 110 by the high voltage power source 130.

  When the particulate measurement device 100 is used to measure particulates contained in the exhaust gas of the internal combustion engine 10, the measurement target fluid introduction pipe 140 is attached to the exhaust pipe 12 of the internal combustion engine and the exhaust passage is connected to the discharge passage 160. 20 is connected and the exhaust gas is sucked into the measurement target fluid introduction pipe 140. The fine particles contained in the exhaust gas flow into the classification passage 110 after being charged by the charger 170 provided in the measurement target fluid introduction pipe 140. Further, the upstream of the carrier fluid supply pipe 150 is connected to the pressure feed pump 30, and the carrier gas is supplied from the carrier fluid supply pipe 150 into the classification passage 110 in accordance with the inflow of exhaust gas. As the carrier gas, various gases that do not contain fine particles, such as air, can be used.

  In FIG. 1, the flow of exhaust gas containing fine particles is represented by hatched arrows, and the flow of carrier gas is represented by white arrows. As shown in the figure, the exhaust gas and the carrier gas flow in the classification passage 110 with being mixed with each other in a layered state. As described above, since an electric field is formed between the electrode 180 provided at the center of the classification passage 110 and the inner wall surface of the classification passage 110, the fine particles contained in the exhaust gas are separated from the electric field. It moves in the direction crossing the flow under the Coulomb force.

  A large sampling port 122 is provided on the wall surface of the classification passage 110. As described above, since the particulates in the exhaust gas are caused to flow downstream in the classification passage 110 by the exhaust gas or the carrier gas, the particulates that move too slowly across the flow are not collected at the sampling port 122. Then, it is discharged into the discharge passage 160. In addition, fine particles whose movement speed is too fast are captured by the inner wall surface of the classification passage 110 on the upstream side of the collection port 122 and are not collected by the collection port 122. As a result, only fine particles having a predetermined particle size range are collected at the collection port 122 and guided to the particle detector 120. The mechanism by which only fine particles having a predetermined particle size range are collected at the collection port 122 will be described in detail later.

  As the particle detector 120, a particle counter that counts the number of particles using an optical technique can be suitably used. Alternatively, the carbon concentration contained in the fine particles is detected using a so-called FID (flame ionization detector), or the flow of charged fine particles is directly detected as a current using a so-called Faraday cup. It is also possible to apply other various methods.

  FIG. 2 is an explanatory diagram showing a mechanism by which only fine particles having a predetermined particle size range are collected by the collection port 122 from the fine particles contained in the exhaust gas. The fine particles contained in the exhaust gas are given electric charges when passing through the charger 170 and flow into the classification passage 110 from the measurement target fluid introduction pipe 140. The black circles shown in the figure indicate the fine particles contained in the exhaust gas. In FIG. 2, only the relatively large particles DPL and the relatively small particles DPS in the particle size range to be measured are displayed among the particles included in the exhaust gas, in order to avoid complicated illustration. Has been.

  A carrier fluid supply pipe 150 is provided around the measurement target fluid introduction pipe 140, and the carrier gas pumped by the pressure pump 30 is supplied from the carrier fluid supply pipe 150 in accordance with the inflow of exhaust gas. The The inflow speed of the carrier gas is adjusted to be the same as the inflow speed of the exhaust gas. In FIG. 2, the flow of the carrier gas is represented by a white arrow. The size of the classification passage 110 and the inflow speed of the exhaust gas (accordingly, the inflow speed of the carrier gas) are set to appropriate values so that the number of lay nozzles is a predetermined value or less. The flow of the carrier gas is maintained in a so-called laminar flow state, so that the exhaust gas and the carrier gas hardly mix with each other, and flow in the classification passage 110 while maintaining a layered state. As a result, an exhaust gas flow is formed around the electrode 180 provided in the center of the classification passage 110, and a carrier gas flow is formed in a layered manner around the exhaust gas flow.

  Next, an electric field is formed between the electrode 180 and the classification passage 110 by applying a voltage from the high-voltage power supply 130. Since the exhaust gas and the carrier gas flow along the classification passage 110, the electric field is formed in a direction crossing this flow. The direction of the electric field is determined by the electric charge applied to the fine particles. That is, when a positive charge is applied to the fine particles, an electric field is formed from the electrode 180 toward the classification passage 110. Such an electric field can be formed, for example, by applying a positive voltage to the electrode 180 and grounding the classification passage 110, or by grounding the electrode 180 and applying a negative voltage to the classification passage 110. Conversely, when a negative charge is applied to the fine particles, a negative voltage may be applied to the electrode 180 to ground the classification passage 110, or the electrode 180 may be grounded to apply a positive voltage to the classification passage 110.

In this way, when an electric field is formed according to the electric charge applied to the fine particles, the fine particles receive a Coulomb force in a direction away from the electrode 180. As a result, the fine particles in the exhaust gas move little by little in the direction across the flow, enter the carrier gas layer, and eventually reach the inner wall of the classification passage 110. The speed Zp at which the charged fine particles move in the direction across the flow in this way is determined by the balance between the Coulomb force received from the electric field and the resistance received from the fluid, and can be calculated by the following equation.
Zp = Cm × np × e / (3πμ × dp)
Here, np represents the number of charges applied to the fine particles, e represents the elementary charge, μ represents the viscosity coefficient of the gas, and dp represents the particle size of the fine particles. Further, the correction coefficient Cm is called a Cunningham correction coefficient, and is a coefficient for correcting the influence caused by the fact that the particle size of the fine particles is small and the gas cannot be regarded as a continuous fluid.

  As is clear from the above equation, the fine particles move slowly across the flow as the particle size increases. This is because the larger the fine particles, the greater the resistance from the fluid. Thus, since the flow slowly traverses when the fine particles become large, a long distance is caused to flow on the flow of exhaust gas and carrier gas before reaching the inner wall surface of the classification passage 110. On the other hand, since the small particles quickly cross the flow, they reach the inner wall surface of the classification passage 110 without being flowed so much. Eventually, the position that reaches the inner wall surface of the classification passage 110 is on the upstream side with respect to the smaller fine particles, and on the downstream side with respect to the larger fine particles. For this reason, if a large collection port 122 as shown in FIG. 2 is provided on the side surface of the classification passage 110 to collect fine particles, it is possible to collect only fine particles having a predetermined particle size range. In the example shown in FIG. 2, a state in which only fine particles having a particle size larger than the fine particle DPS and smaller than the fine particle DPL is collected from the collection port 122 is shown.

  FIG. 3 is an enlarged cross-sectional view conceptually showing the detailed structure of the sampling port 122 provided in the classification passage 110. As illustrated, the upper end and the lower end of the sampling port 122 are each formed in an edge shape. As described above, since the finer particle having a smaller particle diameter crosses the flow more quickly, the finer particle having a smaller particle diameter than the fine particle DPS is in the classification passage 110 on the upstream side of the edge part 122a on the upper end side of the sampling port 122. It reaches the wall surface and is captured by the wall surface, or is swept away by the carrier gas and flows to the downstream side next to the sampling port 122. Further, fine particles having a particle size larger than the fine particle DPL reach the inner wall surface of the classification passage 110 on the downstream side of the edge portion 122b on the lower end side of the sampling port 122, or on the downstream side without reaching the inner wall surface. It will be washed away. Only fine particles having a particle size range larger than the fine particle DPS and smaller than the fine particle DPL are collected from the collection port 122. For this reason, in the illustrated fine particle measuring apparatus 100, the edge portion 122a on the upper end side of the sampling port 122 has a function of separating fine particles having a smaller particle diameter and larger fine particles than the fine particles SP. It can be said that the edge part 122b of the lower end part of this has the function to isolate | separate the microparticles | fine-particles smaller than the microparticles LP, and a large microparticle.

  FIG. 4 is an explanatory diagram showing a typical particle size distribution of fine particles contained in the exhaust gas. On the horizontal axis, the particle diameter of the fine particles is logarithmically displayed. As shown in the figure, the fine particles in the exhaust gas include two types of fine particles, a small fine particle having a peak in the vicinity of 10 nm to 30 nm, and a large fine particle having a peak in the vicinity of 40 nm to 120 nm with about 80 nm as the center. It is known that Among these, the finer particles having a smaller particle size have a large emission amount due to a slight difference in operating conditions of the internal combustion engine 10 and are composed of unstable substances. Tend to fluctuate greatly. On the other hand, the fine particles having a larger particle diameter are made of a more stable material than the fine particles having a smaller particle diameter, and the measured value does not vary greatly depending on the measurement conditions. For this reason, if fine particles having a larger particle diameter are detected, highly reliable data can be obtained without being affected by the difference in measurement conditions.

  In consideration of such a particle size distribution of the fine particles, the position and size of the sampling port 122 are set in the fine particle measuring apparatus 100 of the present embodiment so as to detect only the fine particles having the larger particle diameter. . As described with reference to FIG. 3, only the fine particles having a particle size range larger than the fine particle DPS and smaller than the fine particle DPL are taken into the sampling port 122, and other fine particles enter the sampling port 122. It has no structure. The fine particles taken into the sampling port 122 are immediately supplied to the particle detector 120, and all the fine particles are detected. As a result, the particle measuring apparatus 100 of the present embodiment has a very high detection sensitivity for the particles in the particle size range to be measured, while almost detecting sensitivity for the particles outside the particle size range. It can be said that it has a characteristic that does not have For reference, the sensitivity characteristics of the particle measuring apparatus 100 of the present embodiment are conceptually shown in FIG. As shown in the figure, the particle measuring apparatus 100 of the present embodiment has a substantially rectangular sensitivity characteristic that has sensitivity only in the particle size range of the detection target.

  Since the particle measuring apparatus 100 of the present embodiment has such sensitivity characteristics, it can be used very suitably when measuring particles contained in the exhaust gas of the internal combustion engine 10. Hereinafter, this point will be described. As described above, the fine particles contained in the exhaust gas of the internal combustion engine 10 have two peaks, one having a small particle size and one having a large particle size. Among these, the fine particles having a smaller particle diameter largely fluctuate due to a slight difference in operating conditions of the internal combustion engine 10, and the obtained values tend to vary greatly depending on the difference in conditions on the measurement side. For this reason, unless the discharge behavior of fine particles having a smaller particle size is specifically measured, if a peak component having a smaller particle size is mixed into the measured value, it becomes a strong noise and hinders analysis. However, as shown in FIG. 5, the particle measuring apparatus 100 according to the present embodiment has high detection sensitivity for particles in the particle size range to be measured, but for particles having a particle size outside the object to be measured. , Has little detection sensitivity. For this reason, only the peak component with a large particle size can be detected almost completely without being affected by the peak component with a small particle size, and as a result, highly reliable data can be stably measured. It becomes possible.

  Of course, such a characteristic of the particulate measuring device 100 of the present embodiment is not limited to the case of measuring particulates contained in the exhaust gas of the internal combustion engine 10, but only particulates having a specific particle size range are accurately obtained. In addition, when it is necessary to measure stably, it can be said that the characteristics are extremely suitable.

  Moreover, the particle measuring apparatus 100 of the present embodiment can acquire time-series data with high time resolution. For this reason, for example, when applied to measure the particulates in the exhaust gas, it is possible to suitably measure the transient particulate discharge behavior when the operating condition of the internal combustion engine 10 changes.

  Further, in the particle measuring apparatus 100 of the present embodiment, only particles having a particle size range to be measured can be collected by a simple mechanism, and there is no element that causes clogging like a filter. For this reason, it is possible to perform stable measurement with high accuracy without deterioration of characteristics even if the use is continued for a long period of time.

  Furthermore, since the particle measuring apparatus 100 of the present embodiment has a simple structure, the entire apparatus can be made extremely small. Moreover, since the particle size range of the detected fine particles can be determined based on the flow rate passing through the classification passage 110, the voltage applied to the electrode 180, and the position and size of the sampling port 122, no calibration is necessary. Therefore, simple measurement is possible. In addition, by adjusting the voltage applied to the electrode 180 and the flow rate of the fluid to be measured (exhaust gas in the example described above) or the carrier fluid (carrier gas in the example described above), particles having different particle size ranges can be obtained. It is also possible to detect.

  Various modifications exist in the fine particle measuring apparatus 100 described above. In the following, a description will be given of these modified particle measuring apparatuses.

(1) First modification:
In the fine particle measuring apparatus 100 described above, it was possible to detect fine particles having different particle diameter ranges by adjusting the voltage applied to the electrode 180 and the flow rate of the exhaust gas or the carrier gas. It is also possible to optimize the shape of the sampling port 122 on the assumption that the particle size range is fixed.

  FIG. 6 is an explanatory diagram conceptually showing the shape of the sampling port 122 in the particle measuring apparatus 100 of the first modified example. Arrows indicated by thin solid lines in the figure indicate streamlines of exhaust gas and carrier gas passing through the classification passage 110. When the exhaust gas, the flow rate of the carrier gas, the position of the sampling port 122, and the like are fixed, the streamline in the classification passage 110 is automatically determined. Therefore, in consideration of this streamline, if the cross-sectional shape of the sampling port 122 is set so as not to disturb the flow in the classification passage 110, only the fine particles that have reached the sampling port 122 can be reliably sampled. It becomes possible. That is, when the flow is disturbed, the movement of the fine particles is strongly influenced not only by the Coulomb force received from the electric field but also by the disturbance. On the other hand, if no disturbance has occurred, the path along which the fine particles move along the flow can be determined from the Coulomb force received from the electric field. Therefore, by providing the collection port 122 in the path of the fine particles, it is possible to collect almost completely the fine particles in the particle size range to be measured.

  In the example shown in FIG. 6, the edge 122a on the upper end side of the sampling port 122 is set to have a cross-sectional shape that prevents the flow of fine particles smaller than the particle size to be measured, The edge portion 122b is set to have a cross-sectional shape in which only the fine particles to be measured flow. By doing in this way, it becomes possible to make the sensitivity characteristic with respect to a particle size closer to an ideal characteristic.

(2) Second modification:
In the fine particle measuring apparatus 100 described above, the collection port 122 is described as being provided on the side surface of the classification passage 110, but the collection port 122 is not necessarily provided on the side surface of the classification passage 110.

  FIG. 7 is an explanatory diagram illustrating the rough structure of the particle measuring apparatus 100 of the second modification example. In the illustrated example, the classification passage 110 has a rectangular cross section, and an electrode 180 is provided on one side surface. Then, exhaust gas and carrier gas are supplied in a layered manner in the classification passage 110, and an electric field is formed in a direction crossing the flow. In this way, since the particles are classified into small particles and large particles on the downstream side of the flow, one of the particles may be guided to the particle detector 120 to detect the particles.

  By using such a particle measuring apparatus 100 of the second modified example, only one of fine particles larger than a predetermined particle size or small particles is measured with high accuracy and stability in a time series. It becomes possible. In addition, since it is not necessary to provide the collection port 122 on the side surface of the classification passage 110, the classification passage 110 can be shortened, and the entire apparatus can be made simple and small.

  Alternatively, as shown in FIG. 8, fine particles may be collected from a collection port 122 provided on the downstream side of the classification passage 110. In this way, it is possible to stably measure only fine particles having a predetermined particle size range with high accuracy.

  While various embodiments of the present invention have been described above, the present invention is not limited to this, and is not limited to the wording of each claim unless it departs from the scope described in each claim. It is possible to appropriately add an improvement based on the knowledge that a person skilled in the art normally has, and also to the extent that those skilled in the art can easily replace them.

It is explanatory drawing which showed notionally the mode that the microparticles | fine-particles contained in the exhaust gas of an internal combustion engine were measured using the microparticles | fine-particles measuring apparatus of a present Example. It is explanatory drawing which showed the mechanism in which only the microparticles | fine-particles of the predetermined particle diameter range are extract | collected by the collection port from the microparticles | fine-particles contained in exhaust gas. It is the expanded sectional view which showed notionally the detailed structure of the sampling port provided in the classification passage. It is explanatory drawing which showed the typical particle size distribution of the microparticles | fine-particles contained in exhaust gas. It is explanatory drawing which showed notionally the sensitivity characteristic with respect to the particle size which the fine particle measuring device of a present Example has. It is explanatory drawing which showed notionally the cross-sectional shape of the collection port in the microparticle measuring device of a 1st modification. It is explanatory drawing which showed an example of the particulate measuring device of the 2nd modification. It is explanatory drawing which showed another example of the fine particle measuring apparatus of the 2nd modification.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine, 12 ... Exhaust pipe, 20 ... Exhaust blower,
30 ... Pressure pump, 100 ... Particle measuring device, 110 ... Classification passage,
120 ... Particle detector 122 ... Sampling port 122a ... Edge part
122b: edge portion, 130: high-voltage power supply, 140: measurement target fluid introduction pipe,
150 ... conveying fluid supply pipe, 160 ... discharge passage, 170 ... charger,
180 ... electrode

Claims (1)

A particle measuring device for measuring particles contained in a fluid,
A passage portion in which a measurement target fluid, which is a fluid containing fine particles to be measured, and a carrier fluid supplied together with the measurement target fluid flow in layers;
A fine particle charging portion provided on the upstream side of the passage portion to charge the fine particles;
An electric field forming unit that forms an electric field in a direction crossing the flow of the carrier fluid on the downstream side of the fine particle charging unit;
When the measurement target fluid and the carrier fluid pass through the electric field, the speed at which the charged fine particles move in the direction crossing the flow of the carrier fluid under the force of the electric field depends on the particle size of the fine particles. Correspondingly by utilizing different properties, from among the charged particles, the moving speed is fine particles having a small than a predetermined first threshold speed, the first to be removed as fine particles of a large diameter outside the measurement object A particulate removal section;
A second particle in which the moving speed is larger than a predetermined second threshold speed (however, larger than the first threshold speed) is removed from the charged fine particles as small-sized fine particles that are not to be measured. A fine particle removing portion of
A fine particle detection unit that detects the remaining fine particles from which the large-sized fine particles and the small-sized fine particles that are not measured are removed , and
The first fine particle removing portion is protruded from a side surface of the passage portion, and a tip is formed in an edge shape,
The second particle removing unit is a particle measuring device that protrudes from a side surface of the passage portion upstream of the first particle removing unit and has a tip formed in an edge shape .

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