JP2005024409A - Method and instrument for measuring particulate in exhaust gas - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure particulates contained in an exhaust gas continuously inclusive of the data related to the particle size of fine particles. <P>SOLUTION: The exhaust gas and a feed gas are allowed to flow in a classifying passage in a mutually layered state. The particulates in the exhaust gas are charged by the charger provided on the upstream side in the classifying passage and an electric field is formed on the downstream side thereof in the direction traversing the flows of both gases. A plurality of sampling ports are provided on the side surface of the classifying passage so as to be positionally different from each other in the flow direction. The particulates in the exhaust gas receive the effect of the electric field to move in the direction traversing the flows of the gases to arrive at the wall surface of the classifying passage. The particulates thus moved are taken in from a plurality of the sampling ports to be detected by a particle detector. Since the moving speed of smaller particulates is high, small particulates are detected at the sampling port on the upstream side of the flows of the gases and the larger particulates are detected on the downstream side. By this method, the particulates in the exhaust gas can be continuously detected while classified. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a technique for measuring fine particles contained in exhaust gas continuously and including information related to particle size.
[0002]
[Prior art]
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.
[0003]
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, it has been pointed out that particulate matter (PM) in the exhaust gas may adversely affect 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 small particles (hereinafter referred to as nanoparticles) having a particle size of 50 nm or less among PMs may have some specific effects on the human body. It is being considered including the necessity of regulation.
[0004]
In such studies, it is necessary to measure the concentration of nanoparticles in exhaust gas, but it is suggested that the degree of influence and mechanism on human health may vary depending on the particle size of nanoparticles. Therefore, it is necessary to measure information on the particle size distribution. Furthermore, from the viewpoint of effectively suppressing the emission of nanoparticles by improving the internal combustion engine, in order to clarify the emission behavior of nanoparticles, the nanoparticles in the exhaust gas including the particle size distribution are real-time. It is desirable to measure with.
[0005]
As a technique for measuring the particulate matter in the exhaust gas, for example, a technique for measuring the particle size distribution by collecting the particulate matter in the exhaust gas for each particle size using a plurality of collecting members (for example, , Patent Document 1), or a technique (for example, Patent Document 2) that measures the concentration in real time by measuring the scattered light from the particulate matter by entering light into the exhaust gas has been proposed. .
[0006]
[Patent Document 1]
JP 2003-35636 A
[Patent Document 2]
JP 2003-114192 A
[0007]
[Problems to be solved by the invention]
However, since the nanoparticles are very small in particle size and are easily affected by intermolecular force, electrostatic force, thermophoresis, etc., as collected by the collecting member as proposed in Patent Document 1, Due to the strong influence of measurement conditions, accurate measurement is very difficult. In addition, it is impossible to measure the nanoparticle concentration in the exhaust gas in real time. Moreover, according to the technique proposed in Patent Document 2, although it is possible to measure in real time, it is difficult to obtain information on the particle size distribution. Of course, if the intensity of light scattered by each particle is analyzed, it is possible in principle to extract information on the particle size distribution. However, since nanoparticles have a small particle size and low scattered light intensity, It is difficult to measure accurate data, and it cannot be a practical and simple measurement method.
[0008]
The present invention has been made to solve these problems in the prior art, and provides a technique that can easily measure nanoparticles in exhaust gas in real time in a state including information on particle size distribution. The purpose is to do.
[0009]
[Means for solving the problems and their functions and effects]
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 particulate measuring device for measuring particulates contained in exhaust gas of an internal combustion engine,
A passage portion through which the exhaust gas and the carrier gas not containing fine particles flow in a layered state,
A fine particle charging portion provided on the upstream side of the passage portion and charging the fine particles in the exhaust gas;
An electric field forming unit for forming an electric field in a direction across the flow of the carrier gas on the downstream side of the fine particle charging unit;
A sampling port for continuously collecting the fine particles, which have moved across the flow of the carrier gas under the action of the formed electric field, together with the carrier gas;
A fine particle detector for detecting fine particles collected together with the carrier gas;
With
A plurality of the sampling ports are provided at different positions in the direction of the carrier gas flow.
[0010]
Further, the fine particle measurement method of the present invention corresponding to the fine particle measurement device described above,
A fine particle measurement method for measuring fine particles contained in exhaust gas of an internal combustion engine,
Forming a flow in which the exhaust gas and the carrier gas not containing particulates are layered together in a passage;
Charging the particulates in the exhaust gas upstream of the passage;
Forming an electric field in a direction across the flow of the carrier gas downstream of the particulate charging unit;
The fine particles that have moved across the flow of the carrier gas under the action of the formed electric field continuously with the carrier gas at a plurality of positions that are different from each other in the direction of the carrier gas flow. The process of collecting
Measuring fine particles collected together with the carrier gas;
It is a summary to provide.
[0011]
In the particulate measuring apparatus and particulate measuring method of the present invention, the exhaust gas of the internal combustion engine and the carrier gas not containing particulates are circulated in the passage in a state of being layered with each other. Further, the fine particles in the exhaust gas are charged on the upstream side of the passage, and an electric field is formed in the direction crossing the flow on the downstream side. The charged fine particles are gradually moved in the direction intersecting with the flow by receiving the force from the electric field while flowing from the upstream to the downstream on the flow of the exhaust gas. Eventually, the gas moves from the exhaust gas region to the carrier gas region, and finally reaches the inner wall surface of the passage. In this way, the fine particles that have moved across the flow under the force of the electric field while flowing in the carrier gas are continuously collected and measured together with the carrier gas.
[0012]
The speed at which the fine particles move in the direction intersecting the flow depends on the Coulomb force received from the electric field, the resistance received by the fine particles from the fluid, and the like, and the resistance received from the fluid increases as the fine particles increase. For this reason, large particles that receive large resistance move slowly across the flow, and small particles that do not receive much resistance move quickly across the flow. Therefore, if the sample is continuously collected together with the carrier gas at a plurality of locations with different positions in the direction of the carrier gas flow and the particulates contained in the carrier gas are detected, the flow can be quickly crossed upstream. Small particles that have been produced, and large particles that have slowly traversed the flow on the downstream side are detected.
[0013]
In the fine particle measuring apparatus and the fine particle measuring method of the present application, since the fine particles are detected using such a method, the fine particles in the exhaust gas can be continuously measured. Moreover, since the particulates in the exhaust gas can be detected in a classified state according to the detection locations provided with different positions in the flow direction, information on the particle size distribution of the particulates can also be continuously and simply. It becomes possible to detect.
[0014]
Further, in the particulate measuring apparatus and particulate measuring method of the present application, the exhaust gas and the carrier gas are allowed to flow in the passage in a state of being layered together, the particulates are charged on the upstream side, and an electric field is formed on the downstream side. Fine particles are classified with an extremely simple structure. Therefore, it is possible to reduce the size of the device with a simple configuration as a whole and improve the reliability.
[0015]
In addition, the particle size of the fine particles contained in the exhaust gas is distributed over a wide range. However, since the fine particles are classified and supplied to the detection unit, each detection unit is required to have a wide detection range. There is nothing to do. For this reason, it becomes possible to detect fine particles with high accuracy and stability.
[0016]
Furthermore, in the above-described method, the difference in the detection position of the fine particles corresponds to the difference in the size of the fine particles to be detected as it is. Accordingly, there is an advantage that even when detecting a fine particle having a new particle diameter, it is possible to easily cope with the problem by simply adding a detection position to the corresponding position.
[0017]
Further, in the fine particle measuring apparatus and the fine particle measuring method of the present application, even when it is necessary to increase the number of sampling ports in order to classify the fine particles more finely, the sampling ports are provided with different positions in the flow direction. Therefore, it is possible to easily increase the number of installations.
[0018]
In addition, if the sampling port is provided on the side of the flow in this way, it is easy to improve the resolution when classifying the fine particles. First, fine particles in the exhaust gas are allowed to flow over a long distance from the carrier gas flow to the inner wall surface of the passage. In order to allow the fine particles to flow over a long distance, for example, the flow rate of the carrier gas (and exhaust gas) may be increased, or the strength of the electric field to be formed may be decreased. In this state, a sampling port is provided at a position corresponding to the size of the fine particles to be classified. By doing so, it is possible to improve the resolution at the time of classifying the microparticles very simply even when a sampling port of the same size is used.
[0019]
In such a fine particle measuring apparatus, the exhaust gas and the carrier gas may be flown through the passage while maintaining the so-called laminar flow.
[0020]
If the flow of the exhaust gas and the carrier gas is in a so-called turbulent state in the passage, a flow in which the exhaust gas and the carrier gas are mixed with each other is generated, and the fine particles are carried into the carrier gas by this flow. The classification error will increase. On the other hand, if the flow of exhaust gas and carrier gas is kept in a laminar flow state in the passage, it becomes possible to avoid the introduction of errors due to these factors, and thus fine particles in the exhaust gas can be accurately removed. Since it becomes possible to measure, it is preferable.
[0021]
In such a particle measuring apparatus, a collection port for collecting particles may be provided in the carrier gas from the inner wall of the passage.
[0022]
If fine particles smaller than the fine particles to be detected are contained in the exhaust gas, the fine particles quickly cross the flow of the exhaust gas and the carrier gas and reach the inner wall of the passage upstream from the sampling port. Then, it may move downstream along the inner wall and flow in from the sampling port together with fine particles of a size to be detected. On the other hand, if the sampling port protrudes from the inner wall of the passage, even if the exhaust gas contains fine particles smaller than the fine particles to be detected, it is possible to avoid such small fine particles from being mixed in. Therefore, it is possible to classify and detect fine particles with high accuracy.
[0023]
Or it is good also as providing the protrusion which prevents inflow of the microparticles | fine-particles which have moved along the inner wall in the upstream of a collection port.
[0024]
Even in this case, it is possible to effectively avoid the small classification of the fine particles and the classification accuracy to be lowered, so that the fine particles can be accurately measured.
[0025]
The fine particle measuring apparatus described above may be provided with sampling ports at two locations by making the positions different from each other in the direction of the flow of the carrier gas.
[0026]
In the exhaust gas, it is known that there are two types of fine particles, fine particles having a size of about 10 nm to 30 nm and fine particles having a size of about 100 nm to 300 nm. Therefore, it is preferable to provide the collection ports for the fine particles at two locations corresponding to these sizes because the discharge behavior of the fine particles can be easily measured.
[0027]
Furthermore, it is good also as providing a sampling port between these two sampling ports and providing a sampling port in a total of three locations.
[0028]
This is preferable because more detailed information on the particle size distribution of the fine particles can be easily obtained.
[0029]
In addition, the fine particle detector provided at least on the upstream side of the fine particle measurement device described above may count the fine particles using an optical technique.
[0030]
Since small particles are detected on the upstream side, the number of particles increases compared to the weight. Therefore, on the upstream side, it is possible to detect fine particles with high accuracy by counting the number of particles using an optical method.
[0031]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the above-described invention of the present application will be described in detail based on examples. FIG. 1 is an explanatory diagram conceptually showing the structure of the particle measuring apparatus 100 of the present embodiment. The fine particle measuring apparatus 100 is roughly composed of a classification passage 110, a plurality of particle detectors 120, a high-voltage power supply 130, and the like. An upstream side of the classification passage 110 is connected with an exhaust gas introduction pipe 140 for introducing exhaust gas into the classification passage and a carrier gas supply pipe 150 for supplying carrier gas into the classification passage. A discharge passage 160 for discharging the exhaust gas and the carrier gas is connected to the downstream side of the classification passage 110. A charger 170 is provided in the middle of the exhaust gas introduction pipe 140. The charger 170 can give a 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.
[0032]
When measuring the particulates contained in the exhaust gas of the internal combustion engine 10 using the particulate measurement device 100, the exhaust gas introduction pipe 140 is attached to the exhaust pipe 12 of the internal combustion engine, and the exhaust blower 20 is disposed in the discharge passage 160. And exhaust gas is sucked into the exhaust gas introduction pipe 140. The fine particles contained in the exhaust gas are charged by a charger 170 provided in the exhaust gas introduction pipe 140 and then flow into the classification passage 110. Further, upstream of the carrier gas supply pipe 150 is connected to the pressure feed pump 30, and the carrier gas is supplied from the carrier gas 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.
[0033]
In FIG. 1, the flow of exhaust gas 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.
[0034]
A plurality of sampling ports 122 are provided on the wall surface of the classification passage 110 in different positions in the flow direction, and the sampling ports 122 are connected to the particle detectors 120 provided in each. As described above, since the plurality of sampling ports 122 are provided in the classification passage 110 with different flow directions, the fine particles in the exhaust gas are collected in a state where they are classified by the electric field while passing through the classification passage. It reaches the mouth 122 and flows into the particle detector 120 connected to each sampling port 122. A mechanism for classifying the fine particles in the classification passage 110 will be described later.
[0035]
As the particle detector 120, a particle counter that counts the number of particles using an optical technique can be suitably used. Alternatively, a so-called FID (Flame Ionization Detector) is used to detect the concentration of carbon contained in the fine particles, and furthermore, 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.
[0036]
FIG. 2 is an explanatory view showing a mechanism by which fine particles in the exhaust gas are classified in the classification passage 110. The fine particles contained in the exhaust gas are charged when passing through the charger 170 and flow into the classification passage 110 from the exhaust gas introduction pipe 140. The black circles shown in the figure indicate the fine particles contained in the exhaust gas. In FIG. 2, for convenience of explanation, it is assumed that the exhaust gas contains only two kinds of fine particles, large fine particles LP and small fine particles SP.
[0037]
A carrier gas supply pipe 150 is provided around the exhaust gas introduction pipe 140, and the carrier gas pumped by the pressure pump 30 is supplied from the carrier gas supply pipe 150 in accordance with the inflow of the exhaust gas. . 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, a flow situation is formed in which the exhaust gas flow is present around the electrode 180 provided in the center of the classification passage 110 and the carrier gas flow is present in layers around the electrode 180. It will be.
[0038]
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.
[0039]
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 crossing the flow, enter the carrier gas layer, and finally reach the inner wall of the classification passage 110. The speed Zp at which the charged fine particles move in the direction crossing the flow is determined by the balance between the Coulomb force received from the electric field and the resistance received from the fluid, and can be obtained 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 an 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.
[0040]
As is clear from the above equation, large particles move slowly across the flow. This is because the larger the fine particles, the greater the resistance from the fluid. In this way, since the large fine particles slowly cross the flow, they reach the inner wall surface of the classification passage 110 and are carried over a long distance on the flow of the exhaust gas and the carrier gas. On the other hand, since the small fine particles with low fluid resistance quickly cross the flow, they can reach the inner wall surface of the classification passage 110 without much flow. That is, as shown in FIG. 2, only small particles SP are detected at the sampling port 122 provided on the upstream side of the flow, and only large particles LP are detected at the sampling port 122 provided on the downstream side of the flow. Become. In this way, if the fine particles are detected at a plurality of locations provided in different positions in the flow direction in the classification passage 110, the fine particles can be detected in a state where the fine particles are classified.
[0041]
FIG. 3 is a perspective view conceptually showing the structure of the sampling port 122 provided in the classification passage 110. As shown in the drawing, the classification passage 110 is provided with a collection ring 124 so as to surround the outer periphery, and the collection ring 124 and the classification passage 110 communicate with each other through a collection port 122. The fine particles classified in the classification passage 110 flow into the collection ring 124 from the collection port 122 and are guided from the collection ring 124 to the particle detector 120 through the pipe 126. In this way, since all classified fine particles can be supplied to the particle detector 120, high detection sensitivity can be obtained.
[0042]
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. The solid line in the figure shows the measured value of the weight at each particle size, and the broken line in the figure shows the number of particles at each particle size. 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 100 nm to 300 nm. Are known. That is, if the discharge behavior of the fine particles is measured in these two particle size ranges, it is possible to grasp the rough discharge behavior of all the fine particles.
[0043]
In consideration of such particle size distribution of the fine particles, the fine particle measuring apparatus 100 of the present embodiment is provided with one sampling port 122 on each of the upstream side and the downstream side of the classification passage 110, and the upstream sampling port. 122 is a position for detecting particles in the particle size range indicated by “A” in FIG. 3, and the sampling port 122 on the downstream side detects particles in the particle size range indicated by “B” in FIG. It is provided in the position to do. By providing each sampling port 122 at such a position, it is possible to detect the rough discharge behavior of the fine particles in the exhaust gas in real time. Of course, if fine particles are detected even in the particle size range indicated by “C” in FIG. 3, a more detailed particle size distribution can be detected.
[0044]
As described above, the particle measuring apparatus 100 of the present embodiment can continuously detect the particles in the exhaust gas in a classified state. Since the classification of the fine particles can be performed quickly only by passing the exhaust gas and the carrier gas through the classification passage 110 to which an electric field is applied, the transient fine particles when the operating condition of the internal combustion engine 10 is changed can be obtained. The discharge behavior can also be detected with sufficient time resolution.
[0045]
In addition, in the particle measuring apparatus 100 of the present embodiment, the particles are classified by an extremely simple mechanism, and there is no element that causes clogging such as 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. The fine particles are collected at the collection port 122 and do not adhere to the electrode 180. For this reason, even when used for a long period of time, there is almost no need for maintenance.
[0046]
In addition to the simple classification mechanism as described above, if the position where the sampling port is provided is limited to two or three, the entire measuring device can be made extremely small. Although it is not possible to obtain a detailed particle size distribution due to the small number of sampling ports, as described above, stable measurement can be performed with high accuracy over a long period of time without maintenance. It can be suitably used as an inspection tool used in a maintenance shop.
[0047]
The fine particle measuring apparatus 100 of the present embodiment has not only a simple structure, but also has an excellent feature that it is highly responsive and can measure stably and accurately. Therefore, if a large number of sampling ports 122 are provided in the longitudinal direction of the classification passage 110, it is effective as a highly accurate research tool for detailed study of the discharge behavior of fine particles in the exhaust gas, taking advantage of these features. Can be used.
[0048]
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.
[0049]
In the fine particle measuring apparatus 100 described above, the sampling ring 124 is provided on the outer periphery of the classification passage 110 and the sampling port 122 is provided over the entire circumference of the classification passage 110 as shown in FIG. However, for convenience, the sampling ports 122 may be provided by standing the pipes 126 radially in the classification passage 110. FIG. 5 is an explanatory view illustrating a state in which a plurality of sampling ports 122 are thus provided. Here, as shown in FIG. 5A, the sampling port 122 provided on the upstream side of the classification passage 110 and the sampling port 122 on the downstream side may be provided at positions that are staggered when viewed from the flow direction. Good. In this way, the downstream sampling port can collect the fine particles at the downstream sampling port in the same manner as the upstream sampling port, that is, almost without being affected by the upstream sampling port. Therefore, it is possible to improve the classification accuracy.
[0050]
On the other hand, as shown in FIG. 5 (b), when provided at the same position when viewed from the flow direction, small particles are collected at the upstream sampling port 122, and therefore provided at the downstream side. There is no risk of mixing in the sampling port 122. For this reason, it is possible to improve classification accuracy.
[0051]
The sampling port 122 may be provided so as to protrude from the inner wall surface of the classification passage 110 in the flow of the carrier gas. FIG. 6 is an explanatory view illustrating the sampling port 122 thus protruding. As described above, since the small particles receive less resistance from the fluid, they quickly cross the flow under the influence of the electric field and reach the inner wall surface of the classification passage 110 on the upstream side. The small particles that have reached the inner wall surface are then flowed downstream along the inner wall surface. The arrows indicated by broken lines in FIG. 6 conceptually show how small particles move in this way along the inner wall surface. Even when a large number of such small particles are present, if the sampling port 122 is provided in a projecting manner, it is possible to avoid collecting such particles, so that the particles can be classified with high accuracy. Is possible.
[0052]
Or it is good also as providing the protrusion 128 which prevents a small microparticle in the upstream of the collection port 122. FIG. FIG. 7 is an explanatory diagram illustrating such a protrusion 128. As indicated by the dashed arrows in the figure, even if small particles move from the upstream along the inner wall surface, they do not flow into the sampling port 122 because they are blocked by the protrusions 128. As a result, the fine particles can be classified with high accuracy.
[0053]
Moreover, although the cross-sectional shape of the classification channel | path 110 was demonstrated as the substantially circular shape and the electrode 180 was provided in the substantially center in the Example mentioned above, a classification channel | path is not restricted to such a structure. For example, the classification passage 110 may have a rectangular cross section, and the electrode 180 may be provided on one side as shown in FIG. Even in such a configuration, if an electric field is formed in a direction crossing the flow of the exhaust gas and the carrier gas, the fine particles can be classified by the mechanism described with reference to FIG. In this case, since it is not necessary to provide the electrode 180 inside the classification passage 110, the particle measuring device can be made a simpler structure.
[0054]
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.
[0055]
【The invention's effect】
As described above, according to the present invention, the structure is simple, the reliability is high, the response speed is excellent, and the fine particles in the exhaust gas can be measured with high accuracy including the information on the particle size distribution. become.
[Brief description of the drawings]
FIG. 1 is an explanatory view conceptually showing the structure of a particle measuring apparatus of the present embodiment.
FIG. 2 is an explanatory diagram showing a mechanism by which fine particles in exhaust gas are classified in a classification passage.
FIG. 3 is a perspective view conceptually showing the structure of a sampling port provided in a classification passage.
FIG. 4 is an explanatory diagram showing a typical particle size distribution of fine particles contained in exhaust gas.
FIG. 5 is an explanatory diagram illustrating a state in which a plurality of sampling ports are provided in the classification passage.
FIG. 6 is an explanatory view illustrating a sampling port projecting from the inner wall surface of the classification passage.
FIG. 7 is an explanatory view exemplifying a state in which a protrusion for preventing mixing of fine particles is provided on the upstream side of the sampling port.
FIG. 8 is an explanatory view exemplifying a configuration of a classification passage having an electrode provided on a side surface thereof.
[Explanation of symbols]
10 ... Internal combustion engine
12 ... Exhaust pipe
20 ... exhaust blower
30 ... Pressure pump
100: Fine particle measuring device
110 ... Classification passage
120 ... Particle detector
122 ... sampling port
124 ... Collection ring
126 ... Pipe
128 ... protrusion
130: High voltage power supply
140 ... Exhaust gas introduction pipe
150 ... carrier gas supply pipe
160 ... Release passage
170: Charger
180 ... electrode

Claims (8)

A particulate measuring device for measuring particulates contained in exhaust gas of an internal combustion engine,
A passage portion through which the exhaust gas and the carrier gas not containing fine particles flow in a layered state,
A fine particle charging portion provided on the upstream side of the passage portion and charging the fine particles in the exhaust gas;
An electric field forming unit for forming an electric field in a direction across the flow of the carrier gas on the downstream side of the fine particle charging unit;
A sampling port for continuously collecting the fine particles, which have moved across the flow of the carrier gas under the action of the formed electric field, together with the carrier gas;
A fine particle detector for detecting fine particles collected together with the carrier gas,
A fine particle measuring apparatus, wherein a plurality of the sampling ports are provided at different positions in the direction of the flow of the carrier gas. The fine particle measuring apparatus according to claim 1,
The particulate measuring device, wherein the passage portion is a passage portion through which the exhaust gas and the carrier gas flow in a laminar flow state. The fine particle measuring apparatus according to claim 1 or 2,
The sampling port is a fine particle measuring device that protrudes into the carrier gas from the inner wall of the passage portion. The fine particle measuring apparatus according to claim 1 or 2,
The particulate collection device is provided with a protrusion that prevents the collection of the particulate that has moved from the upstream side along the inner wall of the passage portion. The fine particle measuring apparatus according to claim 1 or 2,
2. The fine particle measuring apparatus according to claim 1, wherein the sampling ports are provided at two positions with different positions in the direction of the flow of the carrier gas. The fine particle measuring apparatus according to claim 1 or 2,
The fine particle measuring apparatus, wherein the sampling ports are provided at three positions with different positions in the direction of the flow of the carrier gas. The fine particle measuring apparatus according to claim 1 or 2,
The fine particle detector is a fine particle measuring device that is a measuring unit that counts the fine particles collected together with the carrier gas by an optical method. A fine particle measurement method for measuring fine particles contained in exhaust gas of an internal combustion engine,
Forming a flow in which the exhaust gas and the carrier gas not containing particulates are layered together in a passage;
Charging the particulates in the exhaust gas upstream of the passage;
Forming an electric field in a direction across the flow of the carrier gas downstream of the particulate charging unit;
The fine particles that have moved across the flow of the carrier gas under the action of the formed electric field continuously with the carrier gas at a plurality of positions that are different from each other in the direction of the carrier gas flow. The process of collecting
And a step of measuring fine particles collected together with the carrier gas.

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